@article{BraunschweigDewhurstSchwabetal.2010, author = {Braunschweig, Holger and Dewhurst, Rian D. and Schwab, Katrin and Wagner, Katharina}, title = {{N ',N ''-Bis[2,6-bis(1-methylethyl)phenyl]-N,N-dimethylguanidinato-kappa N-2 ',N ''}dibromidoborane}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67622}, year = {2010}, abstract = {In the molecular structure of the title compound, C27H40N3BBr2, the B atom is connected to two bromide substituents and a guanidinate scaffold, forming a four- membered ring. An aryl group is connected to each N atom in the ring that contains two isopropyl groups in positions 2 and 6.}, subject = {Anorganische Chemie}, language = {en} } @article{LandmannSchrammColditzetal.2010, author = {Landmann, Tobias and Schramm, Matthias and Colditz, Rene R. and Dietz, Andreas and Dech, Stefan}, title = {Wide Area Wetland Mapping in Semi-Arid Africa Using 250-Meter MODIS Metrics and Topographic Variables}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68628}, year = {2010}, abstract = {Wetlands in West Africa are among the most vulnerable ecosystems to climate change. West African wetlands are often freshwater transfer mechanisms from wetter climate regions to dryer areas, providing an array of ecosystem services and functions. Often wetland-specific data in Africa is only available on a per country basis or as point data. Since wetlands are challenging to map, their accuracies are not well considered in global land cover products. In this paper we describe a methodology to map wetlands using well-corrected 250-meter MODIS time-series data for the year 2002 and over a 360,000 km2 large study area in western Burkina Faso and southern Mali (West Africa). A MODIS-based spectral index table is used to map basic wetland morphology classes. The index uses the wet season near infrared (NIR) metrics as a surrogate for flooding, as a function of the dry season chlorophyll activity metrics (as NDVI). Topographic features such as sinks and streamline areas were used to mask areas where wetlands can potentially occur, and minimize spectral confusion. 30-m Landsat trajectories from the same year, over two reference sites, were used for accuracy assessment, which considered the area-proportion of each class mapped in Landsat for every MODIS cell. We were able to map a total of five wetland categories. Aerial extend of all mapped wetlands (class "Wetland") is 9,350 km2, corresponding to 4.3\% of the total study area size. The classes "No wetland"/"Wetland" could be separated with very high certainty; the overall agreement (KHAT) was 84.2\% (0.67) and 97.9\% (0.59) for the two reference sites, respectively. The methodology described herein can be employed to render wide area base line information on wetland distributions in semi-arid West Africa, as a data-scarce region. The results can provide (spatially) interoperable information feeds for inter-zonal as well as local scale water assessments.}, subject = {Geologie}, language = {en} } @article{Helmreich2010, author = {Helmreich, Ernst J. M.}, title = {Ways and means of coping with uncertainties of the relationship of the genetic blue print to protein structure and function in the cell}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68006}, year = {2010}, abstract = {As one of the disciplines of systems biology, proteomics is central to enabling the elucidation of protein function within the cell; furthermore, the question of how to deduce protein structure and function from the genetic readout has gained new significance. This problem is of particular relevance for proteins engaged in cell signalling. In dealing with this question, I shall critically comment on the reliability and predictability of transmission and translation of the genetic blue print into the phenotype, the protein. Based on this information, I will then evaluate the intentions and goals of today's proteomics and gene-networking and appraise their chances of success. Some of the themes commented on in this publication are explored in greater detail with particular emphasis on the historical roots of concepts and techniques in my forthcoming book, published in German: Von Molek{\"u}len zu Zellen. 100 Jahre experimentelle Biologie. Betrachtungen eines Biochemikers}, subject = {Genetik}, language = {en} } @inproceedings{Schmitz2010, author = {Schmitz, Barbara}, title = {War, violence and Tyrannicide in the Book of Judith}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67058}, year = {2010}, abstract = {No abstract available}, subject = {Judit }, language = {en} } @phdthesis{Huebner2010, author = {H{\"u}bner, Dominique}, title = {Vibronic and electronic excitations of large organic molecules in gas and condensed phase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66043}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In the frame of this thesis vibronic and electronic states of organic molecules have been examined. A central question is the interaction within and between the molecules in thin films and at metal-organic interfaces. The main experimental tools were high resolution electron energy loss spectroscopy (HREELS) and high resolution near edge X-ray absortion fine structure (NEXFAS). The electronic and vibronic structure of thin NTCDA films was examined with low energy electrons as probe, i.e. HREELS. The spectra of the electronic excited molecular orbitals of submonolayer NTCDA on a Ag(111) shows a partially filled orbital. The interaction between this orbital and the total symetric molecular vibrations leads to the typical Fano peak profiles which are seen in the vibrational spectra. The sub-monolayer superstructure can be driven to a phase transition into an disordered phase upon cooling, which is also seen in the electronic and vibronic excitation spectra. Multilayers show flat lying or upright standing molecules as a function of the preparation conditions. The upright standing molecules show an island growth mode, where the islands are well ordered and exhibit a structure in diffraction experiments which can be attributed to the molecular crystal structure. In order to examine the order in more detail various thin films were examined using SPALEED as function of film thickness and preparation parameters. In case of a low temperature substrate no long range order leading to a diffraction pattern was found. In contrast growth on room temperature substrates leads to island growth of films in a structure of the molecular crystal, where two preferred orientations of the islands relative to the substrate were found. In case of thick films the reference to the substrate gets lost and the molecular crystals grow with a defined crystal direction with respect to the surface but with an arbitrary azimuthal orientation leading to circles in the diffraction pattern. NTCDA monolayers on a Ag(111) surface using HREELS as a tool were examined. The electronic excitation spectra reveal a partially filled molecular orbital which is strongly shifted compared to the multilayer. The existence of this state is responsible for the activation of normally forbidden Ag modes in the vibrational spectra. Due to the electron phonon coupling these modes exhibit a Fano like peak shape. Cooling a monolayer leads to a phase transition with strong changes in the spectroscopic features both in electronic and vibronic excitations. In case of the molecule ANQ the intramolecular interaction was examined. In the oxygen NEXAFS spectra a vibronic fine structure is found, which leads to the conclusion that asymmetric potentials are involved. It is an interesting question if the fundamental vibration is has C-H or C=O character. In order to address this question spectra of condensed and gas phase ANQ were compared to an ANQ derivate (ANQ- Br\$_2\$Cl\$_2\$), with the conclusion that the coupling is most likely to a C=O mode. High resolution C1s spectra of hydrogenated and fully deuterated naphthalene both in gas and condensed phase have been presented. Depending on the final state orbital distinct differences have been found between gas and condensed phase. A energetic shift of resonances (Res. B, C, D) is interpreted as effect of \$\pi\$-\$\pi\$ interaction in the condensed phase. This is especially notable for resonance B which is undoubtly assigned to an excitation into a \$\pi^*\$ orbital. The results lead to an interpretation, that for organic molecular crystals more than pure van-derWaals interaction has to be taken into account. In summary it is found that the intramolecular interaction in NEXAFS spectra is preferentially coupled to one or a few vibronic progressions. Due to the delocalized electronic system maybe even states which are not spatially near the core excited atom can be involved. It could be shown that a condensation of the molecules in thin films leads to changes within the spectra. The influence the intermolecular interaction can be clearly seen in this finding, where additional hints are found that more than mere van-der-Waals binding has to be taken into account.}, subject = {Organisches Molek{\"u}l}, language = {en} } @phdthesis{Geissinger2010, author = {Geissinger, Ulrike}, title = {Vaccinia Virus-mediated MR Imaging of Tumors in Mice: Overexpression of Iron-binding Proteins in Colonized Xenografts}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48099}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Vaccinia virus plays an important role in human medicine and molecular biology ever since the 18th century after E. Jenner discovered its value as a vaccination virus against smallpox. After the successful eradication of smallpox, vaccinia virus, apart from its use as a vaccine carrier, is today mainly used as a viral vector in molecular biology and increasingly in cancer therapy. The capability to specifically target and destroy cancer cells makes it a perfect agent for oncolytic virotherapy. Furthermore, the virus can easily be modified by inserting genes encoding therapeutic or diagnostic proteins to be expressed within the tumor. The emphasis in this study was the diagnosis of tumors using different vaccinia virus strains. Viruses with metal-accumulating capabilities for tumor detection via MRI technology were generated and tested for their usefulness in cell culture and in vivo. The virus strains GLV-1h131, GLV-1h132, and GLV-1h133 carry the gene encoding the two subunits of the iron storage protein ferritin under the control of three different promoters. GLV-1h110, GLV-1h111, and GLV-1h112 encode the bacterial iron storage protein bacterioferritin, whereas GLV-1h113 encodes the codon-optimized version of bacterioferritin for more efficient expression in human cells. GLV-1h22 contains the transferrin receptor gene, which plays an important role in iron uptake, and GLV-1h114 and GLV-1h115 contain the murine transferrin receptor gene. For possibly better iron uptake the virus strains GLV-1h154, GLV-1h155, GLV-1h156, and GLV-1h157 were generated, each with a version of a ferritin gene and a transferrin receptor gene. GLV-1h154 carries the genes that encode bacterioferritin and human transferrin receptor, GLV-1h155 the human ferritin H-chain gene and the human transferrin receptor gene. GLV-1h156 and GLV-1h157 infected cells both express the mouse transferrin receptor and bacterioferritin or human ferritin H-chain, respectively. The virus strains GLV-1h186 and GLV-1h187 were generated to contain a mutated form of the ferritin light chain, which was shown to result in iron overload and the wildtype light chain gene, respectively. The gene encoding the Divalent Metal Transporter 1, which is a major protein in the uptake of iron, was inserted in the virus strain GLV-1h102. The virus strain GLV-1h184 contains the magA gene of the magnetotactic bacterium Magnetospirillum magnetotacticum, which produces magnetic nanoparticles for orientation in the earth's magnetic field. Initially the infection and replication capability of all the virus strains were analyzed and compared to that of the parental virus strain GLV-1h68, revealing that all the viruses were able to infect cells of the human cancer cell lines A549 and GI-101A. All constructs exhibited a course of infection comparable to that of GLV-1h68. Next, to investigate the expression of the foreign proteins in GI-101A and A549 cells with protein analytical methods, SDS-gelelectrophoresis, Western blots and ELISAs were performed. The proteins, which were expressed under the control of the strong promoters, could be detected using these methods. To be able to successfully detect the protein expression of MagA and DMT1, which were expressed under the control of the weak promoter, the more sensitive method RT-PCR was used to at least confirm the transcription of the inserted genes. The determination of the iron content in infected GI-101A and A549 cells showed that infection with all used virus strains led to iron accumulation in comparison to uninfected cells, even infection with the parental virus strain GLV-1h68. The synthetic phytochelatin EC20 was also shown to enhance the accumulation of different heavy metals in bacterial cultures. In vivo experiments with A549 tumor-bearing athymic nude mice revealed that 24 days post infection virus particles were found mainly in the tumor. The virus-mediated expression of recombinant proteins in the tumors was detected successfully by Western blot. Iron accumulation in tumor lysates was investigated by using the ferrozine assay and led to the result that GLV-1h68-infected tumors had the highest iron content. Histological stainings confirmed the finding that iron accumulation was not a direct result of the insertion of genes encoding iron-accumulating proteins in the virus genome. Furthermore virus-injected tumorous mice were analyzed using MRI technology. Two different measurements were performed, the first scan being done with a seven Tesla small animal scanner seven days post infection whereas the second scan was performed using a three Tesla human scanner 21 days after virus injection. Tumors of mice injected with the virus strains GLV-1h113 and GLV-1h184 were shown to exhibit shortened T2 and T2* relaxation times, which indicates enhanced iron accumulation. In conclusion, the experiments in this study suggest that the bacterioferritin-encoding virus strain GLV-1h113 and the magA-encoding virus strain GLV-1h184 are promising candidates to be used for cancer imaging after further analyzation and optimization.}, subject = {Vaccinia-Virus}, language = {en} } @article{EliasSchoulsvandePoletal.2010, author = {Elias, Johannes and Schouls, Leo M. and van de Pol, Ingrid and Keijzers, Wendy C. and Martin, Diana R. and Glennie, Anne and Oster, Philipp and Frosch, Matthias and Vogel, Ulrich and van der Ende, Arie}, title = {Vaccine Preventability of Meningococcal Clone, Greater Aachen Region, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68083}, year = {2010}, abstract = {No abstract available}, subject = {IMD}, language = {en} } @article{WahlenRoewerKranke2010, author = {Wahlen, Bianca M. and Roewer, Norbert and Kranke, Peter}, title = {Use of local anaesthetics and adjuncts for spinal and epidural anaesthesia and analgesia at German and Austrian University Hospitals: an online survey to access current standard practice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67847}, year = {2010}, abstract = {Background: The present anonymous multicenter online survey was conducted to evaluate the application of regional anaesthesia techniques as well as the used local anaesthetics and adjuncts at German and Austrian university hospitals. Methods: 39 university hospitals were requested to fill in an online questionnaire, to determine the kind of regional anaesthesia and preferred drugs in urology, obstetrics and gynaecology. Results: 33 hospitals responded. No regional anaesthesia is conducted in 47\% of the minor gynaecological and 44\% of the urological operations; plain bupivacaine 0.5\% is used in 38\% and 47\% respectively. In transurethral resections of the prostate and bladder no regional anaesthesia is used in 3\% of the responding hospitals, whereas plain bupivacaine 0.5\% is used in more than 90\%. Regional anaesthesia is only used in selected major gynaecological and urological operations. On the contrary to the smaller operations, the survey revealed a large variety of used drugs and mixtures. Almost 80\% prefer plain bupivacaine or ropivacaine 0.5\% in spinal anaesthesia in caesarean section. Similarly to the use of drugs in major urological and gynaecological operations a wide range of drugs and adjuncts is used in epidural anaesthesia in caesarean section and spontaneous delivery. Conclusions: Our results indicate a certain agreement in short operations in spinal anaesthesia. By contrast, a large variety concerning the anaesthesiological approach in larger operations as well as in epidural analgesia in obstetrics could be revealed, the causes of which are assumed to be primarily rooted in particular departmental structures.}, subject = {An{\"a}sthesiologie}, language = {en} } @phdthesis{Heldens2010, author = {Heldens, Wieke}, title = {Use of airborne hyperspectral data and height information to support urban micro climate characterisation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48935}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The urban micro climate has been increasingly recognised as an important aspect for urban planning. Therefore, urban planners need reliable information on the micro climatic characteristics of the urban environment. A suitable spatial scale and large spatial coverage are important requirements for such information. This thesis presents a conceptual framework for the use of airborne hyperspectral data to support urban micro climate characterisation, taking into account the information needs of urban planning. The potential of hyperspectral remote sensing in characterising the micro climate is demonstrated and evaluated by applying HyMap airborne hyperspectral and height data to a case study of the German city of Munich. The developed conceptual framework consists of three parts. The first is concerned with the capabilities of airborne hyperspectral remote sensing to map physical urban characteristics. The high spatial resolution of the sensor allows to separate the relatively small urban objects. The high spectral resolution enables the identification of the large range of surface materials that are used in an urban area at up to sub-pixel level. The surface materials are representative for the urban objects of which the urban landscape is composed. These spatial urban characteristics strongly influence the urban micro climate. The second part of the conceptual framework provides an approach to use the hyperspectral surface information for the characterisation of the urban micro climate. This can be achieved by integrating the remote sensing material map into a micro climate model. Also spatial indicators were found to provide useful information on the micro climate for urban planners. They are commonly used in urban planning to describe building blocks and are related to several micro climatic parameters such as temperature and humidity. The third part of the conceptual framework addresses the combination and presentation of the derived indicators and simulation results under consideration of the planning requirements. Building blocks and urban structural types were found to be an adequate means to group and present the derived information for micro climate related questions to urban planners. The conceptual framework was successfully applied to a case study in Munich. Airborne hyperspectral HyMap data has been used to derive a material map at sub-pixel level by multiple endmember linear spectral unmixing. This technique was developed by the German Research Centre for Geosciences (GFZ) for applications in Dresden and Potsdam. A priori information on building locations was used to support the separation between spectrally similar materials used both on building roofs and non-built surfaces. In addition, surface albedo and leaf area index are derived from the HyMap data. The sub-pixel material map supported by object height data is then used to derive spatial indicators, such as imperviousness or building density. To provide a more detailed micro climate characterisation at building block level, the surface materials, albedo, leaf area index (LAI) and object height are used as input for simulations with the micro climate model ENVI-met. Concluding, this thesis demonstrated the potential of hyperspectral remote sensing to support urban micro climate characterisation. A detailed mapping of surface materials at sub-pixel level could be performed. This provides valuable, detailed information on a large range of spatial characteristics relevant to the assessment of the urban micro climate. The developed conceptual framework has been proven to be applicable to the case study, providing a means to characterise the urban micro climate. The remote sensing products and subsequent micro climatic information are presented at a suitable spatial scale and in understandable maps and graphics. The use of well-known spatial indicators and the framework of urban structural types can simplify the communication with urban planners on the findings on the micro climate. Further research is needed primarily on the sensitivity of the micro climate model towards the remote sensing based input parameters and on the general relation between climate parameters and spatial indicators by comparison with other cities.}, subject = {Mikroklima}, language = {en} } @article{HommersLee2010, author = {Hommers, Wilfried and Lee, Wha-Yong}, title = {Unifying Kohlberg with Information Integration: The Moral Algebra of Recompense and of Kohlbergian Moral Informers}, series = {Psicol{\´o}gica}, journal = {Psicol{\´o}gica}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85875}, year = {2010}, abstract = {In order to unify two major theories of moral judgment, a novel task is employed which combines elements of Kohlberg´s stage theory and of the theory of information integration. In contrast to the format of Kohlberg´s moral judgment interview, a nonverbal and quantitative response which makes low demands on verbal facility was used . Moral informers differing in value, i.e. high and low, are presented. The differences in effect of those two pieces of information should be substantial for a person at that specific moral stage, but small for a person at a different stage. Hence, these differences may diagnose the person's moral stage in the simplest possible way as the two levels of each of the thoughts were about typical content of the four Kohlbergian preconventional and conventional stages. The novel task allowed additionally to measure the influence of another moral concept which was about the non-Kohlbergian moral concept of recompense. After a training phase, pairs of those thoughts were presented to allow for the study of integration and individual differences. German and Korean children, 8, 10, and 12 years in age, judged deserved punishment. The patterns of means, correlations and factor loadings showed that elements of both theories can be unified, but produced unexpected results also. Additive integration of each of the two pairs of moral informers appeared, either with two Kohlbergian moral informers or with another Kohlbergian moral informer in combination with information about recompense. Also cultural independence as well as dependence, developmental changes between 8 and 10 years, and an outstanding moral impact of recompense in size and distinctiveness were observed.}, language = {en} } @unpublished{Nassourou2010, author = {Nassourou, Mohamadou}, title = {Understanding the Vex Rendering Engine}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51333}, year = {2010}, abstract = {The Visual Editor for XML (Vex)[1] used by TextGrid [2]and other applications has got rendering and layout engines. The layout engine is well documented but the rendering engine is not. This lack of documenting the rendering engine has made refactoring and extending the editor hard and tedious. For instance many CSS2.1 and upcoming CSS3 properties have not been implemented. Software developers in different projects such as TextGrid using Vex would like to update its CSS rendering engine in order to provide advanced user interfaces as well as support different document types. In order to minimize the effort of extending Vex functionality, I found it beneficial to write a basic documentation about Vex software architecture in general and its CSS rendering engine in particular. The documentation is mainly based on the idea of architectural layered diagrams. In fact layered diagrams can help developers understand software's source code faster and easier in order to alter it, and fix errors. This paper is written for the purpose of providing direct support for exploration in the comprehension process of Vex source code. It discusses Vex software architecture. The organization of packages that make up the software, the architecture of its CSS rendering engine, an algorithm explaining the working principle of its rendering engine are described.}, subject = {Cascading Style Sheets}, language = {en} } @article{EhlingBittnerBobaketal.2010, author = {Ehling, P. and Bittner, S. and Bobak, N. and Schwarz, T. and Wiendl, H. and Budde, T. and Kleinschnitz, Christoph and Meuth, S. G.}, title = {Two pore domain potassium channels in cerebral ischemia: a focus on K2p9.1 (TASK3, KCNK9)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68129}, year = {2010}, abstract = {BACKGROUND: Recently, members of the two-pore domain potassium channel family (K2P channels) could be shown to be involved in mechanisms contributing to neuronal damage after cerebral ischemia. K2P3.1-/- animals showed larger infarct volumes and a worse functional outcome following experimentally induced ischemic stroke. Here, we question the role of the closely related K2P channel K2P9.1. METHODS: We combine electrophysiological recordings in brain-slice preparations of wildtype and K2P9.1-/- mice with an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of K2P9.1 in stroke formation. RESULTS: Patch-clamp recordings reveal that currents mediated through K2P9.1 can be obtained in slice preparations of the dorsal lateral geniculate nucleus (dLGN) as a model of central nervous relay neurons. Current characteristics are indicative of K2P9.1 as they display an increase upon removal of extracellular divalent cations, an outward rectification and a reversal potential close to the potassium equilibrium potential. Lowering extracellular pH values from 7.35 to 6.0 showed comparable current reductions in neurons from wildtype and K2P9.1-/- mice (68.31 +/- 9.80\% and 69.92 +/- 11.65\%, respectively). These results could be translated in an in vivo model of cerebral ischemia where infarct volumes and functional outcomes showed a none significant tendency towards smaller infarct volumes in K2P9.1-/- animals compared to wildtype mice 24 hours after 60 min of tMCAO induction (60.50 +/- 17.31 mm3 and 47.10 +/- 19.26 mm3, respectively). CONCLUSIONS: Together with findings from earlier studies on K2P2.1-/- and K2P3.1-/- mice, the results of the present study on K2P9.1-/- mice indicate a differential contribution of K2P channel subtypes to the diverse and complex in vivo effects in rodent models of cerebral ischemia.}, subject = {Kaliumkanal}, language = {en} } @phdthesis{Luetkenhaus2010, author = {L{\"u}tkenhaus, Katharina}, title = {Tumour development in Raf-driven cancer mouse models}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48332}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Metastasis is the cause of death in 90\% of cancer-related deaths in men. Melanoma and Non-Small-Cell Lung Cancer (NSCLC) are both tumour types with poor prognosis, lacking appropriate therapeutic possibilities, not least because of their high rate of metastasis. Thus understanding the process of metastasis might unravel therapeutic targets for developing further therapeutic strategies. The generation of a transgenic mouse model expressing B-RafV600E in melanocytes, a mutation that is found in about 60\% of all melanoma, would result in an ideal tool to study melanoma progression and metastasis. In this work, a doxycycline-inducible system was constructed for expression of B-RafV600E and transgenic animals were generated, but the expression system has to be improved, since this strategy didn't give rise to any viable, transgene carrying mice. Furthermore, since it was shown in the work of others that the metastatic behavior of tumour cell lines could be reversed by an embryonic microenvironment and the influence of a tumourigenic microenvironment on melanocytes lead to the acquisition of tumour cell-like characteristics, the question arose, whether B-Raf is as important in melanocyte development as it is in melanoma progression. In this work, the embryonal melanocyte development in B-Raf-deficient and wildtype mouse embryos was examined and there were no differences observed in the localization and number of neural crest stem cells as well as in the localization of the dopachrome-tautomerase positive melanoblasts in the embryos and in cultured neural tube explants. The expression of oncogenic C-Raf in lung epithelial cells has yielded a model for NSCLC giving rise to adenomas lacking spontaneous progression or metastasis. The co-expression of c-Myc in the same cells accelerates the tumour development and gives rise to liver and lymphnode metastases. The expression of c-Myc alone in lung epithelial cells leads to late tumour development with incomplete penetrance. A mutation screen in this work resulted in the observation that a secondary mutation in KRas or LKB1 is necessary for tumour formation in the c-Myc single transgenic animals and suggested metastasis as an early event, since the corresponding metastases of the mutation-prone primary lung tumours were negative for the observed mutations. Furthermore, in this work it was shown that the expression of chicken c-Myc in a non-metastatic NSCLC cell line leads to metastatic clones, showing that c-Myc is sufficient to induce metastasis. Additionally a panel of metastasis markers was identified, that might serve as diagnostic markers in the future.}, subject = {Raf }, language = {en} } @article{HerpinBraaschKraeusslingetal.2010, author = {Herpin, Amaury and Braasch, Ingo and Kraeussling, Michael and Schmidt, Cornelia and Thoma, Eva C. and Nakamura, Shuhei and Tanaka, Minoru and Schartl, Manfred}, title = {Transcriptional Rewiring of the Sex Determining dmrt1 Gene Duplicate by Transposable Elements}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68437}, year = {2010}, abstract = {Control and coordination of eukaryotic gene expression rely on transcriptional and posttranscriptional regulatory networks. Evolutionary innovations and adaptations often require rapid changes of such networks. It has long been hypothesized that transposable elements (TE) might contribute to the rewiring of regulatory interactions. More recently it emerged that TEs might bring in ready-to-use transcription factor binding sites to create alterations to the promoters by which they were captured. A process where the gene regulatory architecture is of remarkable plasticity is sex determination. While the more downstream components of the sex determination cascades are evolutionary conserved, the master regulators can switch between groups of organisms even on the interspecies level or between populations. In the medaka fish (Oryzias latipes) a duplicated copy of dmrt1, designated dmrt1bY or DMY, on the Y chromosome was shown to be the master regulator of male development, similar to Sry in mammals. We found that the dmrt1bY gene has acquired a new feedback downregulation of its expression. Additionally, the autosomal dmrt1a gene is also able to regulate transcription of its duplicated paralog by binding to a unique target Dmrt1 site nested within the dmrt1bY proximal promoter region. We could trace back this novel regulatory element to a highly conserved sequence within a new type of TE that inserted into the upstream region of dmrt1bY shortly after the duplication event. Our data provide functional evidence for a role of TEs in transcriptional network rewiring for sub- and/or neo-functionalization of duplicated genes. In the particular case of dmrt1bY, this contributed to create new hierarchies of sex-determining genes.}, subject = {Gen}, language = {en} } @article{Zeeshan2010, author = {Zeeshan, Ahmed}, title = {Towards Performance Measurement and Metrics Based Analysis of PLA Applications}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68188}, year = {2010}, abstract = {This article is about a measurement analysis based approach to help software practitioners in managing the additional level complexities and variabilities in software product line applications. The architecture of the proposed approach i.e. ZAC is designed and implemented to perform preprocessesed source code analysis, calculate traditional and product line metrics and visualize results in two and three dimensional diagrams. Experiments using real time data sets are performed which concluded with the results that the ZAC can be very helpful for the software practitioners in understanding the overall structure and complexity of product line applications. Moreover the obtained results prove strong positive correlation between calculated traditional and product line measures.}, subject = {Programmierbare logische Anordnung}, language = {en} } @article{KraftSchwarzMeijersetal.2010, author = {Kraft, Peter and Schwarz, Tobias and Meijers, Joost C. M. and Stoll, Guido and Kleinschnitz, Christoph}, title = {Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Deficient Mice Are Susceptible to Intracerebral Thrombosis and Ischemic Stroke}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68519}, year = {2010}, abstract = {Background: Thrombus formation is a key step in the pathophysiology of acute ischemic stroke and results from the activation of the coagulation cascade. Thrombin plays a central role in this coagulation system and contributes to thrombus stability via activation of thrombin-activatable fibrinolysis inhibitor (TAFIa). TAFIa counteracts endogenous fibrinolysis at different stages and elevated TAFI levels are a risk factor for thrombotic events including ischemic stroke. Although substantial in vitro data on the influence of TAFI on the coagulation-fibrinolysis-system exist, investigations on the consequences of TAFI inhibition in animal models of cerebral ischemia are still lacking. In the present study we analyzed stroke development and post stroke functional outcome in TAFI-/- mice. Methodology/Principal Findings: TAFI-/- mice and wild-type controls were subjected to 60 min transient middle cerebral artery occlusion (tMCAO) using the intraluminal filament method. After 24 hours, functional outcome scores were assessed and infarct volumes weremeasured from 2,3,5-Triphenyltetrazoliumchloride (TTC)-stained brain slices. Hematoxylin and eosin (H\&E) staining was used to estimate the extent of neuronal cell damage. Thrombus formation within the infarcted brain areas was analyzed by immunoblot. Infarct volumes and functional outcomes did not significantly differ between TAFI-/- mice and controls (p.0.05). Histology revealed extensive ischemic neuronal damage regularly including the cortex and the basal ganglia in both groups. TAFI deficiency also had no influence on intracerebral fibrin(ogen) formation after tMCAO. Conclusion: Our study shows that TAFI does not play a major role for thrombus formation and neuronal degeneration after ischemic brain challenge.}, subject = {Thrombus}, language = {en} } @article{BauerNadler2010, author = {Bauer, Wolfgang R. and Nadler, Walter}, title = {Thermodynamics of Competitive Molecular Channel Transport: Application to Artificial Nuclear Pores}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68484}, year = {2010}, abstract = {In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species' translocation probablity when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules.}, subject = {Thermodynamik}, language = {en} } @article{BollazziRoces2010, author = {Bollazzi, Martin and Roces, Flavio}, title = {The thermoregulatory function of thatched nests in the South American grass-cutting ant, Acromyrmex heyeri}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68225}, year = {2010}, abstract = {The construction of mound-shaped nests by ants is considered as a behavioral adaptation to low environmental temperatures, i.e., colonies achieve higher and more stables temperatures than those of the environment. Besides the well-known nests of boreal Formica wood-ants, several species of South American leaf-cutting ants of the genus Acromyrmex construct thatched nests. Acromyrmex workers import plant fragments as building material, and arrange them so as to form a thatch covering a central chamber, where the fungus garden is located. Thus, the degree of thermoregulation attained by the fungus garden inside the thatched nest largely depends on how the thatch affects the thermal relations between the fungus and the environment. This work was aimed at studying the thermoregulatory function of the thatched nests built by the grass-cutting ant Acromyrmex heyeri Forel (Hymenoptera: Formicidae: Myrmicinae). Nest and environmental temperatures were measured as a function of solar radiation on the long-term. The thermal diffusivity of the nest thatch was measured and compared to that of the surrounding soil, in order to assess the influence of the building material on the nest's thermoregulatory ability. The results showed that the average core temperature of thatched nests was higher than that of the environment, but remained below values harmful for the fungus. This thermoregulation was brought about by the low thermal diffusivity of the nest thatch built by workers with plant fragments, instead of the readily-available soil particles that have a higher thermal diffusivity. The thatch prevented diurnal nest overheating by the incoming solar radiation, and avoided losses of the accumulated daily heat into the cold air during the night. The adaptive value of thatching behavior in Acromyrmex leaf-cutting ants occurring in the southernmost distribution range is discussed.}, subject = {Acromyrmex heyeri}, language = {en} } @phdthesis{Fischer2010, author = {Fischer, Andreas}, title = {The Role of Protein-Protein Interactions in the Activation Cycle of RAF Kinases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48139}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Members of the RAF protein kinase family are key regulators of diverse cellular processes. The need for isoform-specific regulation is reflected by the fact that all RAFs not only display a different degree of activity but also perform isoform-specific functions at diverse cellular compartments. Protein-protein-interactions and phosphorylation events are essential for the signal propagation along the Ras-RAF-MEK-ERK cascade. More than 40 interaction partners of RAF kinases have been described so far. Two of the most important regulators of RAF activity, namely Ras and 14-3-3 proteins, are subject of this work. So far, coupling of RAF with its upstream modulator protein Ras has only been investigated using truncated versions of RAF and regardless of the lipidation status of Ras. We quantitatively analyzed the binding properties of full-length B- and C-RAF to farnesylated H-Ras in presence and absence of membrane lipids. While the isolated Ras-binding domain of RAF exhibit a high binding affinity to both, farnesylated and nonfarnesylated H-Ras, the full-length RAF kinases demonstrate crucial differences in their affinity to Ras. In contrast to C-RAF that requires carboxyterminal farnesylated H-Ras for interaction at the plasma membrane, B-RAF also binds to nonfarnesylated H-Ras in the cytosol. For identification of the potential farnesyl binding site we used several fragments of the regulatory domain of C-RAF and found that the binding of farnesylated H-Ras is considerably increased in the presence of the cysteine-rich domain of RAF. In B-RAF a sequence of 98 amino acids at the extreme N terminus enables binding of Ras independent of its farnesylation status. The deletion of this region altered Ras binding as well as kinase properties of B-RAF to resemble C-RAF. Immunofluorescence studies in mammalian cells revealed essential differences between B- and C-RAF regarding the colocalization with Ras. In conclusion, our data suggest that that B-RAF, in contrast to C-RAF, is also accessible for nonfarnesylated Ras in the cytosolic environment due to its prolonged N terminus. Therefore, the activation of B-RAF may take place both at the plasma membrane and in the cytosolic environment. Furthermore, the interaction of RAF isoforms with Ras at different subcellular sites may also be governed by the complex formation with 14-3-3 proteins. 14-3-3 adapter proteins play a crucial role in the activation of RAF kinases, but so far no information about the selectivity of the seven mammalian isoforms concerning RAF association and activation is available. We analyzed the composition of in vivo RAF/14-3-3 complexes isolated from mammalian cells with mass spectrometry and found that B-RAF associates with a greater variety of 14-3-3 proteins than C- and A-RAF. In vitro binding assays with purified proteins supported this observation since B-RAF showed highest affinity to all seven 14-3-3 isoforms, whereas C-RAF exhibited reduced affinity to some and A-RAF did not bind to the 14-3-3 isoforms epsilon, sigma, and tau. To further examine this isoform specificity we addressed the question of whether both homo- and heterodimeric forms of 14-3-3 proteins participate in RAF signaling. By deleting one of the two 14-3-3 isoforms in Saccharomyces cerevisiae we were able to show that homodimeric 14-3-3 proteins are sufficient for functional activation of B- and C-RAF. In this context, the diverging effect of the internal, inhibiting and the activating C-terminal 14-3-3 binding domain in RAF could be demonstrated. Furthermore, we unveil that prohibitin stimulates C-RAF activity by interfering with 14-3-3 at the internal binding site. This region of C-RAF is also target of phosphorylation as part of a negative feedback loop. Using tandem MS we were able to identify so far unknown phosphorylation sites at serines 296 and 301. Phosphorylation of these sites in vivo, mediated by activated ERK, leads to inhibition of C-RAF kinase activity. The relationship of prohibitin interference with 14-3-3 binding and phosphorylation of adjacent sites has to be further elucidated. Taken together, our results provide important new information on the isoform-specific regulation of RAF kinases by differential interaction with Ras and 14-3-3 proteins and shed more light on the complex mechanism of RAF kinase activation.}, subject = {Signaltransduktion}, language = {en} } @article{Dietl2010, author = {Dietl, Johannes}, title = {The Marketing Effect}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85868}, year = {2010}, language = {en} } @phdthesis{Martin2010, author = {Martin, Lee C.}, title = {The Kondo Lattice Model: a Dynamical Cluster Approximation Approach}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49446}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {We apply an antiferromagnetic symmetry breaking implementation of the dynamical cluster approximation (DCA) to investigate the two-dimensional hole-doped Kondo lattice model (KLM) with hopping \$t\$ and coupling \$J\$. The DCA is an approximation at the level of the self-energy. Short range correlations on a small cluster, which is self-consistently embedded in the remaining bath electrons of the system, are handled exactly whereas longer ranged spacial correlations are incorporated on a mean-field level. The dynamics of the system, however, are retained in full. The strong temporal nature of correlations in the KLM make the model particularly suitable to investigation with the DCA. Our precise DCA calculations of single particle spectral functions compare well with exact lattice QMC results at the particle-hole symmetric point. However, our DCA version, combined with a QMC cluster solver, also allows simulations away from particle-hole symmetry and has enabled us to map out the magnetic phase diagram of the model as a function of doping and coupling \$J/t\$. At half-filling, our results show that the linear behaviour of the quasi-particle gap at small values of \$J/t\$ is a direct consequence of particle-hole symmetry, which leads to nesting of the Fermi surface. Breaking the symmetry, by inclusion of a diagonal hopping term, results in a greatly reduced gap which appears to follow a Kondo scale. Upon doping, the magnetic phase observed at half-filling survives and ultimately gives way to a paramagnetic phase. Across this magnetic order-disorder transition, we track the topology of the Fermi surface. The phase diagram is composed of three distinct regions: Paramagnetic with {\it large} Fermi surface, in which the magnetic moments are included in the Luttinger sum rule, lightly antiferromagnetic with large Fermi surface topology, and strongly antiferromagnetic with {\it small} Fermi surface, where the magnetic moments drop out of the Luttinger volume. We draw on a mean-field Hamiltonian with order parameters for both magnetisation and Kondo screening as a tool for interpretation of our DCA results. Initial results for fixed coupling and doping but varying temperature are also presented, where the aim is look for signals of the energy scales in the system: the Kondo temperature \$T_{K}\$ for initial Kondo screening of the magnetic moments, the Neel temperature \$T_{N}\$ for antiferromagnetic ordering, a possible \$T^{*}\$ at which a reordering of the Fermi surface is observed, and finally, the formation of the coherent heavy fermion state at \$T_{coh}\$.}, subject = {Gittermodell}, language = {en} } @article{KoetschanFoersterKelleretal.2010, author = {Koetschan, Christian and Foerster, Frank and Keller, Alexander and Schleicher, Tina and Ruderisch, Benjamin and Schwarz, Roland and Mueller, Tobias and Wolf, Matthias and Schultz, Joerg}, title = {The ITS2 Database III-sequences and structures for phylogeny}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68390}, year = {2010}, abstract = {The internal transcribed spacer 2 (ITS2) is a widely used phylogenetic marker. In the past, it has mainly been used for species level classifications. Nowadays, a wider applicability becomes apparent. Here, the conserved structure of the RNA molecule plays a vital role. We have developed the ITS2 Database (http://its2.bioapps .biozentrum.uni-wuerzburg.de) which holds information about sequence, structure and taxonomic classification of all ITS2 in GenBank. In the new version, we use Hidden Markov models (HMMs) for the identification and delineation of the ITS2 resulting in a major redesign of the annotation pipeline. This allowed the identification of more than 160 000 correct full ength and more than 50 000 partial structures. In the web interface, these can now be searched with a modified BLAST considering both sequence and structure, enabling rapid taxon sampling. Novel sequences can be annotated using the HMM based approach and modelled according to multiple template structures. Sequences can be searched for known and newly identified motifs. Together, the database and the web server build an exhaustive resource for ITS2 based phylogenetic analyses.}, subject = {Biologie}, language = {en} } @article{VainshteinSanchezBrazmaetal.2010, author = {Vainshtein, Yevhen and Sanchez, Mayka and Brazma, Alvis and Hentze, Matthias W. and Dandekar, Thomas and Muckenthaler, Martina U.}, title = {The IronChip evaluation package: a package of perl modules for robust analysis of custom microarrays}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67869}, year = {2010}, abstract = {Background: Gene expression studies greatly contribute to our understanding of complex relationships in gene regulatory networks. However, the complexity of array design, production and manipulations are limiting factors, affecting data quality. The use of customized DNA microarrays improves overall data quality in many situations, however, only if for these specifically designed microarrays analysis tools are available. Results: The IronChip Evaluation Package (ICEP) is a collection of Perl utilities and an easy to use data evaluation pipeline for the analysis of microarray data with a focus on data quality of custom-designed microarrays. The package has been developed for the statistical and bioinformatical analysis of the custom cDNA microarray IronChip but can be easily adapted for other cDNA or oligonucleotide-based designed microarray platforms. ICEP uses decision tree-based algorithms to assign quality flags and performs robust analysis based on chip design properties regarding multiple repetitions, ratio cut-off, background and negative controls. Conclusions: ICEP is a stand-alone Windows application to obtain optimal data quality from custom-designed microarrays and is freely available here (see "Additional Files" section) and at: http://www.alice-dsl.net/evgeniy. vainshtein/ICEP/}, subject = {Microarray}, language = {en} } @phdthesis{Saverschek2010, author = {Saverschek, Nicole}, title = {The influence of the symbiotic fungus on foraging decisions in leaf-cutting ants - Individual behavior and collective patterns}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52087}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Foraging behavior is a particularly fascinating topic within the studies of social insects. Decisions made by individuals have effects not only on the individual level, but on the colony level as well. Social information available through foraging in a group modulates individual preferences and shapes the foraging pattern of a colony. Identifying parameters influencing foraging behavior in leaf-cutting ants is especially intriguing because they do not harvest for themselves, but for their symbiotic fungus which in turn influences their plant preferences after the incorporation of the substrate. To learn about the substrates' unsuitability for the fungus, ants need to be able to identify the incorporated substrate and associate it with detrimental effects on the fungus. Odor is an important plant characteristic known to be used as recognition key outside the nest in the context of foraging. Chapter 1 shows that foragers are able to recall information about the unsuitability of a substrate through odor alone and consequently reject the substrate, which leads to the conclusion that inside the nest, odor might be enough to indentify incorporated substrate. Identification of plant species is a key factor in the foraging success of leaf-cutting ants as they harvest a multitude of different plant species in a diverse environment and host plant availability and suitability changes throughout the year. Fixed plant preferences of individuals through innate tendencies are therefore only one factor influencing foraging decisions. On the individual as well as the colony level, foraging patterns are flexible and a result of an intricate interplay between the different members involved in the harvesting process: foragers, gardeners and the symbiotic fungus. In chapter 2 I identified several conditions necessary for na{\"i}ve foragers to learn about the unsuitability of substrate inside the nest. In order to exchange of information about the unsuitability of a substrate, the plant in question must be present in the fungus garden. Foragers can learn without own foraging experience and even without experiencing the effects of the substrate on the fungus, solely through the presence of experienced gardeners. The presence of experienced foragers alone on the other hand is not enough to lower the acceptance of substrate by na{\"i}ve foragers in the presence of na{\"i}ve gardeners, even if experienced foragers make up the majority of the workforce inside the nest. Experienced foragers are also able to reverse their previous negative experience and start accepting the substrate again. The individual behavior of foragers and gardeners with different experiential backgrounds in the presence of suitable or unsuitable substrate inside the fungus chamber was investigated in chapter 3 to shed some light on possible mechanisms involved in the flow of information about substrate suitability from the fungus to the ants. Gardeners as well as foragers are involved in the leaf processing and treatment of the applied leaf patches on the fungus. If the plant material is unsuitable, significantly more ants treat the plant patches, but foragers are less active overall. Contacts between workers initiated by either gardeners or foragers occur significantly more frequent and last longer if the substrate is unsuitable. Even though experienced gardeners increase na{\"i}ve foragers' contact rates and duration with other workers in the presence of suitable plant patches, na{\"i}ve foragers show no differences in the handling of the plant patches. This suggests that foragers gain information about plant suitability not only indirectly through the gardening workers, but might also be able to directly evaluate the effects of the substrate on the fungus themselves. Outside the nest, foragers influence each other the trail (chapter 4). Foraging in a group and the presence of social information is a decisive factor in the substrate choice of the individual and leads to a distinct and consentaneous colony response when encountering unfamiliar or unsuitable substrates. As leaf-cutting ants harvest different plant species simultaneously on several trails, foragers gain individual experiences concerning potential host plants. Preferences might vary among individuals of the same colony to the degree that foragers on the same trail perceive a certain substrate as either suitable or unsuitable. If the majority of foragers on the trail perceives one of the currently harvested substrates as unsuitable, na{\"i}ve foragers lower their acceptance within 4 hours. In the absence of a cue in the fungus, na{\"i}ve foragers harvesting by themselves still eventually (within 6 hours) reject the substrate as they encounter experienced gardeners during visits to the nest within foraging bouts. As foraging trails can be up to 100 m long and foragers spend a considerable amount of time away from the nest, learning indirectly from experienced foragers on the trail accelerates the distribution of information about substrate suitability. The level of rejection of a formerly unsuitable substrate after eight hours of foraging by na{\"i}ve foragers correlates with the average percentage of unladen experienced foragers active on the trail. This suggests that unladen experienced foragers might actively contact laden na{\"i}ve workers transmitting information about the unsuitability of the load they carry. Results from experiments were I observed individual laden foragers on their way back to the nest backed up this assumption as individuals were antennated and received bites into the leaf disk they carried. Individuals were contacted significantly more often by nestmates that perceived the carried leaf disk as unsuitable due to previous experience than by nestmates without this experience (chapter 6). Leaf-cutting ants constantly evaluate, learn and re-evaluate the suitability of harvested substrate and adjust their foraging activity accordingly. The importance of the different sources of information within the colony and their effect on the foraging pattern of the colony depend on the presence or absence of each of them as e.g. experienced foragers have a bigger influence on the plant preferences of na{\"i}ve foragers in the absence of a cue in the fungus garden.}, subject = {Blattschneiderameisen}, language = {en} } @article{GawlikWehnerMendeetal.2010, author = {Gawlik, Micha and Wehner, Ingeborg and Mende, Meinhard and Jung, Sven and Pfuhlmann, Bruno and Knapp, Michael and Stoeber, Gerald}, title = {The DAOA/G30 locus and affective disorders: haplotype based association study in a polydiagnostic approach}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67963}, year = {2010}, abstract = {Background: The DAOA/G30 (D-amino acid oxidase activator) gene complex at chromosomal region 13q32-33 is one of the most intriguing susceptibility loci for the major psychiatric disorders, although there is no consensus about the specific risk alleles or haplotypes across studies. Methods: In a case-control sample of German descent (affective psychosis: n = 248; controls: n = 188) we examined seven single nucleotide polymorphisms (SNPs) around DAOA/G30 (rs3916966, rs1935058, rs2391191, rs1935062, rs947267, rs3918342, and rs9558575) for genetic association in a polydiagnostic approach (ICD 10; Leonhard's classification). Results: No single marker showed evidence of overall association with affective disorder neither in ICD10 nor Leonhard's classification. Haplotype analysis revealed no association with recurrent unipolar depression or bipolar disorder according to ICD10, within Leonhard's classification manic-depression was associated with a 3-locus haplotype (rs2391191, rs1935062, and rs3916966; P = 0.022) and monopolar depression with a 5-locus combination at the DAOA/G30 core region (P = 0.036). Conclusion: Our data revealed potential evidence for partially overlapping risk haplotypes at the DAOA/G30 locus in Leonhard's affective psychoses, but do not support a common genetic contribution of the DAOA/G30 gene complex to the pathogenesis of affective disorders.}, subject = {Psychisch Kranker}, language = {en} } @phdthesis{Schulz2010, author = {Schulz, Sandra}, title = {The Contribution of Common and Rare Variants to the Complex Genetics of Psychiatric Disorders}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50677}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Attention deficit/hyperactivity disorder (ADHD), one of the most frequent childhood-onset, chronic and lifelong neurodevelopmental diseases, affects 5 - 10\% of school - aged children and adolescents, and 4\% of adults. The classified basic symptoms are - according to the diagnostic system DSM-VI - inattentiveness, impulsivity and hyperactivity. Also daily life of patients is impaired by learning problems, relationship crises, conflicts with authority and unemployment, but also comorbidities like sleep - and eating problems, mood - and anxiety disorders, depression and substance abuse disorders are frequently observed. Although several twin and family studies have suggested heritability of ADHD, the likely involvement of multiple genes and environmental factors has hampered the elucidation of its etiology and pathogenesis. Due to the successful medication of ADHD with dopaminergic drugs like methylphenidate, up to now, the search for candidate genes has mainly focused on the dopaminergic and - because of strong interactions - the serotonergic system, including the already analyzed candidate genes DAT1, DRD4 and 5, DBH or 5-HTTLPR. Recently, DNA copy number changes have been implicated in the development of a number of neurodevelopmental diseases and the analysis of chromosomal gains and losses by Array Comparative Genomic Hybridization (Array CGH) has turned out a successful strategy to identify disease associated genes. Here we present the first systematic screen for chromosomal imbalances in ADHD using sub-megabase resolution Array CGH. To detect micro-deletions and -duplications which may play a role in the pathogenesis of ADHD, we carried out a genome-wide screen for copy number variations (CNVs) in a cohort of 99 children and adolescents with severe ADHD. Using high-resolution aCGH, a total of 17 potentially syndrome-associated CNVs were identified. The aberrations comprise four deletions and 13 duplications with approximate sizes ranging from 110 kb to 3 Mb. Two CNVs occurred de novo and nine were inherited from a parent with ADHD, whereas five are transmitted by an unaffected parent. Candidates include genes expressing acetylcholine-metabolising butyrylcholinesterase (BCHE), contained in a de novo chromosome 3q26.1 deletion, and a brain-specific pleckstrin homology domain-containing protein (PLEKHB1), with an established function in primary sensory neurons, in two siblings carrying a 11q13.4 duplication inherited from their affected mother. Other genes potentially influencing ADHD-related psychopathology and involved in aberrations inherited from affected parents are the genes for the mitochondrial NADH dehydrogenase 1 alpha subcomplex assembly factor 2 (NDUFAF2), the brain-specific phosphodiesterase 4D isoform 6 (PDE4D6), and the neuronal glucose transporter 3 (SLC2A3). The gene encoding neuropeptide Y (NPY) was included in a ~3 Mb duplication on chromosome 7p15.2-15.3, and investigation of additional family members showed a nominally significant association of this 7p15 duplication with increased NPY plasma concentrations (empirical FBAT, p = 0.023). Lower activation of the left ventral striatum and left posterior insula during anticipation of large rewards or losses elicited by fMRI links gene dose-dependent increases in NPY to reward and emotion processing in duplication carriers. Additionally, further candidate genes were examined via Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). This method enables the analysis of SNPs directly from human genomic DNA without the need for initial target amplification by PCR. All these findings implicate CNVs of behavior-related genes in the pathogenesis of ADHD and are consistent with the notion that both frequent and rare variants influence the development of this common multifactorial syndrome. The second part of this work concentrates on MLC1, a gene associated with Megalencephalic leukoencephalopathy with subcortical cysts, located on chromosome 22q13.33. To get more insight in the disease itself, a targeting vector for a conditional knockout mouse was constructed using homologous recombination. Furthermore, MLC1 has been suggested as a risk gene for schizophrenia, especially the periodic catatonia subtype. An initially identified missense mutation was found to be extremely rare in other patient cohorts; however, a recent report again argued for an association of two intronic MLC1 SNPs with schizophrenia and bipolar disorder. A case-control study of these polymorphisms as well as SNPs in the transcriptional control region of MLC1 was conducted in 212 chronic schizophrenic patients, 56 of which suffered from periodic catatonia, 106 bipolar patients, and 284 controls. Both intronic and promoter polymorphisms were specifically and significantly associated with periodic catatonia but not schizophrenia or bipolar disorder in general. A haplotype constructed from all polymorphisms was also associated with periodic catatonia. The MLC1 variation is associated with periodic catatonia; whether it constitutes a susceptibility or a modifier gene has to be determined.}, subject = {Aufmerksamkeits-Defizit-Syndrom}, language = {en} } @article{KuehnPradel2010, author = {Kuehn, Andrea and Pradel, Gabriele}, title = {The Coming-Out of Malaria Gametocytes [Review Article]}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68196}, year = {2010}, abstract = {The tropical disease malaria, which results in more than one million deaths annually, is caused by protozoan parasites of the genus Plasmodium and transmitted by blood-feeding Anopheline mosquitoes. Parasite transition from the human host to the mosquito vector is mediated by gametocytes, sexual stages that are formed in human erythrocytes, which therefore play a crucial part in the spread of the tropical disease. The uptake by the blood-feeding mosquito triggers important molecular and cellular changes in the gametocytes, thus mediating the rapid adjustment of the parasite from the warm-blooded host to the insect host and subsequently initiating reproduction. The contact with midgut factors triggers gametocyte activation and results in their egress from the enveloping erythrocyte, which then leads to gamete formation and fertilization. This review summarizes recent findings on the role of gametocytes during transmission to themosquito and particularly focuses on the molecular mechanisms underlying gametocyte activation and emergence from the host erythrocyte during gametogenesis.}, subject = {Malaria}, language = {en} } @phdthesis{Ezeani2010, author = {Ezeani, Innocent Emezie}, title = {The Apologetic revisited: Exonerating Luke from an Ancestral Exegetical and Theological Burden}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-57476}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The trend in the scholarship of Luke has been that of presenting Luke as a theologian interested in the survival of Christianity in the Roman world. Becuase of this aim, he seems to overlook the wrongdoings of the Powerful in his time inorder not to endanger the peace of Christianity. However, the intention of this work is to show the defiance and fearlessness of Luke in his dealings with the Rich and the Powerful. He never compromised with the basic teachings of Christianity. A second proper look opens the critical dynamics of his Gospel and the acts, beginning with the Magnificat running through the angelic annunciation scene and the temptation and ending with the punishment of Herod Agrippa in the Acts. The reader beholds a hitherto unknown Luke, who operates within a particular critical stance to the Powerful.}, subject = {Apologetik}, language = {en} } @phdthesis{TuerkPereira2010, author = {T{\"u}rk Pereira, Philippe}, title = {Testing the sour-grapes effect - how food deprivation and reward expectancy change implicit and explicit food-liking and food-wanting}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50591}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The aim of the present thesis was to explore how food deprivation and reward expectancy versus frustrative nonreward change implicit and explicit food-liking and food-wanting. As a result, Experiment 1-3 were successful in revealing that liking- and wanting-related associations toward food stimuli dissociate as a function of food deprivation, given that participants were not rewarded with real food during the experiment. More specifically, whereas food-deprived participants showed more wanting-related associations toward food stimuli than satiated participants, the liking-related associations did not differ across both conditions of hunger. Overall, this effect could be replicated in 3 experiments using different manipulations of nonreward versus reward expectancy. However, neither food deprivation nor nonreward were found to influence participants' self-reported mood and frustration. Moreover, participants of Experiment 2 anticipating food consumption showed the same liking- and wanting-related responses due to food deprivation than participants in the nonreward condition. But providing participants with individual control over food consumption abolished the dissociation of liking- and wanting-related associations. In this condition, however, participants' liking- and wanting-related associations were not moderated by need state, maybe due to the (partial) consumption of snack food before the implicit attitude assessment. This, in turn, may have reduced participants' disposition to respond with more liking- and wanting-related associations when being hungry. Finally, Experiment 4 revealed that the presentation of need-relevant vs. need-irrelevant stimuli prompted different liking-related associations depending on the time participants had fasted before the experiment. Specifically, it could be demonstrated that whereas moderately-hungry compared to satiated participants responded with more positive associations toward need-relevant stimuli, 15 hours food-deprived participants responded with more negative associations compared to moderately-hungry and satiated participants. Respectively, a significant curvilinear function of need state was obtained. In addition, participants were found to immediately respond more negatively to need-irrelevant stimuli as soon as they became moderately hungry, evidencing devaluation effects (see Brendl, Markman, \& Messner, 2003) to also occur on an implicit level of responding. Contrary to the implicit liking- and wanting-related evaluations, self-reported explicit food-liking and food-wanting did not dissociate as a function of food deprivation and nonreward, revealing that participants' explicit self-reports of food-liking and food-wanting did not mirror their implicit responses. As the most important result, it could be demonstrated that explicit food-liking and food-wanting varied positively as a function of need state. The results were discussed on the background of different theoretical assumptions on the malleability of implicit and explicit need-relevant attitudes (e.g. motivational theories, frustrative nonreward).}, subject = {Hunger}, language = {en} } @phdthesis{Grohmann2010, author = {Grohmann, Constanze}, title = {Termite mediated heterogeneity of soil and vegetation patternsin a semi-arid savanna ecosystem in Namibia}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-54318}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Termites are the most important soil ecosystem engineers of semi-arid and arid habitats. They enhance decomposition processes as well as the subsequent mineralisation of nutrients by bacteria and fungi. Through their construction of galleries, nests and mounds, they promote soil turnover and influence the distribution of nutrients and also alter texture and hydrological properties of soils, thereby affecting the heterogeneity of their ecosystem. The main aim of the present thesis was to define the impact of termites on ecosys-tem functioning in a semi-arid ecosystem. In a baseline study, I assessed the diversity of termite taxa in relation to the amount of precipitation, the vegetation patterns and the land use systems at several sites in Namibia. Subsequently, I focussed on a species that is highly abundant in many African savannas, the fungus growing and mound building species Macro-termes michaelseni (Sj{\"o}stedt, 1914). I asked how this species influences the spatial hetero-geneity of soil and vegetation patterns. From repeated samplings at 13 sites in Namibia, I obtained 17 termite taxa of 15 genera. While the type of land use seems to have a minor effect on the termite fauna, the mean annual precipitation explained 96\% and the Simpson index of vascular plant diversity 81\% of the variation in taxa diversity. The number of termite taxa increased with both of these explanation variables. In contrast to former studies on Macrotermes mounds in several regions of Africa that I reviewed, soil analyses from M. michaelseni mounds in the central Namibian savanna revealed that they contain much higher nitrogen contents when compared to their parent material. Further analyses revealed that nitrate forms a major component of the nitrogen content in termite mounds. As nitrate solves easily in water, evaporation processes are most probably responsible for the transport of solved nitrates to the mound surface and their accumulation there. The analysed mounds in central Namibia contained higher sand propor-tions compared to the mounds of the former studies. Through the higher percentage of coarse and middle sized pores, water moves more easily in sandy soils compared to more clayey soils. In consequence, evaporation-driven nitrate accumulation can occur in the studied mounds at high rates. Hochgerechnet auf den Gesamtumfang der H{\"u}gel bedeckte das pro Jahr von einem bewohnten H{\"u}gel erodierte Material theoretisch einen 1 m breiten Kreisring um den Schwemmkegel des H{\"u}gels 2,4 mm hoch. Der entsprechende Wert f{\"u}r unbewohnte H{\"u}gel betrug 1,0 mm. To assess the amount of soil that erodes from termite mounds, I fastened four strong, 65 cm wide plastic bags at 14 mounds each and collected the soil that eroded during five rainfall events. Projected to the total mound circumference, the amount of soil eroded covers theoretically a 1 m wide circular ring around the pediment of an inhabited mound up to a height of 2.4 mm per year. For uninhabited mounds, the height of this soil layer would be 1.0 mm. Per hectare, roughly 245 kg eroded per year from the mounds. However, as the erosion rate depends on several factors such as rainfall intensity, soil texture and point of time within the rainy season, this is only a vague estimate. In order to determine up to which distance the soil erosion from the mounds still influences the chemical characteristics of the adjacent topsoil, I took samples from depth of 0-10 cm at 1, 5 and 25 m distances, respectively, from four different mounds and from the mounds themselves. The non-metric multidimensional scaling of the soil properties showed strong differences between mound and off-mound samples. Soil characteristics within the samples from the mounds did not differ largely. Similarly, I found no strong differences between the samples taken from the different distances from the mound. From these results I conclude that through the construction of foraging galleries and sheetings (soil constructions with which some termite species cover their food items), the soil eroding from termite mounds is quickly mixed with deeper soil layers. In consequence, mound material does not accumulate in the mound's vicinity. In order to reveal how plant growth is influenced by termite mound material, we assessed the number of grass and herb individuals as well as the biomass of plants growing in situ on the base of mounds compared to adjacent sites. While the numbers of both grass and herb individuals were significantly lower compared to adjacent sites, the total biomass of plants growing on the base of mounds was significantly higher. Reverse results were obtained by pot experiments with radish (Raphanus sativus subsp. sativus) and sorghum (Sorghum sp.) growth. Both species grew significantly weaker on mound soil compared to adjacent soil. The contradictory results concerning the biomass of in situ and pot experi-ments are most probably caused by the disturbance of the original soil structure during the potting process. The material was subsequently compacted through watering the plants. In contrast, Macrotermes mounds are pervaded by many macropores which seem to be essential for the plant roots to penetrate the soil. In the last part of this thesis, I posed the question how mounds of M. michaelseni are distributed and what factors might be responsible for this pattern. Former studies showed that mound size is correlated with the size of its inhabiting colony. With several multi-scale analyses, I revealed that larger inhabited mounds were regularly distributed. Additionally, mounds which were closer together tended to be smaller than on average. This indicates that intraspecific competition controls the distribution and size of colonies and their mounds. Former studies concerning Odontotermes mounds substantiated that they are local hotspots of primary productivity and animal abundance. Based on these findings, simulations revealed that a regular distribution of these mounds leads to a greater ecosystem-wide productivity compared to a random arrangement. As in the present study, plant biomass was higher at the mounds compared to off-mound sites, this might hold true for M. michaelseni mounds. From the results of this thesis, I draw the conclusion that through their mound building activities, M. michaelseni strongly influences the distribution patterns of soil nutrients within the central Namibian savanna. These termites create sharp contrasts in nutrient levels and vegetation patterns between mound soils and off-mound soils and enhance the heterogeneity of their habitats. Former studies revealed that habitat hetero-geneity is important in generating species diversity and species richness in turn is correlated positively with biomass production and positively affects ecosystem services. In conclusion, the present thesis underlines the importance of M. michaelseni for ecosystem functioning of the central Namibian savanna.}, subject = {Termiten}, language = {en} } @article{DoerckGoebelWeiseetal.2010, author = {Doerck, Sebastian and Goebel, Kerstin and Weise, Gesa and Schneider-Hohendorf, Tilman and Reinhardt, Michael and Hauff, Peter and Schwab, Nicholas and Linker, Ralf and Maeurer, Mathias and Meuth, Sven G. and Wiendl, Heinz}, title = {Temporal Pattern of ICAM-I Mediated Regulatory T Cell Recruitment to Sites of Inflammation in Adoptive Transfer Model of Multiple Sclerosis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68565}, year = {2010}, abstract = {Migration of immune cells to the target organ plays a key role in autoimmune disorders like multiple sclerosis (MS). However, the exact underlying mechanisms of this active process during autoimmune lesion pathogenesis remain elusive. To test if pro-inflammatory and regulatory T cells migrate via a similar molecular mechanism, we analyzed the expression of different adhesion molecules, as well as the composition of infiltrating T cells in an in vivo model of MS, adoptive transfer experimental autoimmune encephalomyelitis in rats. We found that the upregulation of ICAM-I and VCAM-I parallels the development of clinical disease onset, but persists on elevated levels also in the phase of clinical remission. However, the composition of infiltrating T cells found in the developing versus resolving lesion phase changed over time, containing increased numbers of regulatory T cells (FoxP3) only in the phase of clinical remission. In order to test the relevance of the expression of cell adhesion molecules, animals were treated with purified antibodies to ICAM-I and VCAM-I either in the phase of active disease or in early remission. Treatment with a blocking ICAM-I antibody in the phase of disease progression led to a milder disease course. However, administration during early clinical remission aggravates clinical symptoms. Treatment with anti-VCAM-I at different timepoints had no significant effect on the disease course. In summary, our results indicate that adhesion molecules are not only important for capture and migration of pro-inflammatory T cells into the central nervous system, but also permit access of anti-inflammatory cells, such as regulatory T cells. Therefore it is likely to assume that intervention at the blood brain barrier is time dependent and could result in different therapeutic outcomes depending on the phase of CNS lesion development.}, subject = {Multiple Sklerose}, language = {en} } @phdthesis{Hannaa2010, author = {Hannaa, Wagih}, title = {Taxonomy and palaeoecology of the Cenomanian-Turonian macro-invertebrate from eastern Sinai, Egypt}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-54405}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The present study concerened with taxonomy and palaeoecology of the Cenomanian-Turonian macrobenthic fauna which includes bivalves, gastropods, echinoids, and coral. In addtion, cephalopods are also taken in consideration. 144 taxa are identified and systematically described. Palaeoecological and taphonomic anylsis of the statistically sampled macrobenthos are also discussed. The biostratigraphic sequences along the Cenomanian-Turonian rocks were carried out on the basis of ammonites and other macrobenthic fauna such as corals and bivalves. In order to reconstruct benthic association, 41 statistically sampled were subjected to cluster ananlysis by using Past Programm (Hammer et al., 2001). 10 association and three assemblages were described in order to reconstruct the different depositional enviroments.}, subject = {Pal{\"a}ontologie}, language = {en} } @phdthesis{Goetzendoerfer2010, author = {G{\"o}tzend{\"o}rfer, Stefan}, title = {Synthesis of Copper-Based Transparent Conductive Oxides with Delafossite Structure via Sol-Gel Processing}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51601}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Starting off with solubility experiments of possible precursors, the present study reveals the whole development of a sol gel processing route for transparent p type semiconductive thin films with delafossite structure right to the fabrication of functional p-n junctions. The versatile sol formulation could successfully be modified for several oxide compositions, enabling the synthesis of CuAlO2, CuCrO2, CuMnO2, CuFeO2 and more. Although several differences in the sintering behaviour of powders and thin films could be observed, the powder experiments significantly contributed to the clearification of the intricate phase development during thermal annealing and also to optimization of the annealing sequence for thin film processing. Two different ternary systems turned out to be the most promising candidates for p-TCO application: Copper aluminum oxide for its high optical transmittance and copper chromium oxide for its low synthesis temperature, which allowed thin film deposition on low-cost borosilicate substrates. In order to combine the advantages of these two systems, the quaternary oxide composition CuAl1-xCrxO2 was investigated. With a higher optical transmittance than CuCrO2, a lower synthesis temperature than CuAlO2 and a lower resistivity than both parent systems, the optimum composition of the quaternary oxide is reached for x = 0.50. Compared to physical vapour deposition techniques, the undoped thin films presented here still need to make up some deficites in their optoelectronic performance. Although the best sol-gel samples are able to compete with RF sputtered samples or sampes deposited by PLD in transmittance, their resistivity is almost two orders of magnitude higher. The most probable reasons for this are the characteristic imperfections of sol-gel thin films like porosity and small crystallite size, which create barriers like grain boundaries and bottlenecks like barely connected particles. By additional effort such shortcomings can be repelled to a certain extend, but nevertheless the density of undoped sol-gel material always stays behind its pendants processed by physical vapour deposition.[246] Furthermore, such additional endeavour is likely to annihilate the advantage of sol-gel technique in processing costs. Extrinsic doping is a common method to decrease the resistivity of delafossite materials. Partially replacing the trivalent cations by divalent ones creates additional holes and thus generates additional charge carriers for p-type semiconductivity. This can improve the conductivity of delafossites by up to three orders of magnitude. Due to the compositorial flexibility of sol-gel processing, dopants could be introduced easily in this study by soluble precursors. However, improving the conductivity of CuAlO2 and CuAl0.5Cr0.5O2 via this method failed. Actually, this seems to be due to the fact that instead of being incorporated into the delafossite phase the dopant ions form intransparent phase impurities like spinels, which interfere with optical transmittance of the thin films. On the contrary, doping had a positive effect on the conductivity and the optical transmittance of copper chromium oxide, with magnesium being the most effective dopant. The resistivity could be decreased by more than three orders of magnitude, but in order to achieve this, much higher Mg concentrations than by other thin film deposition methods were necessary. This indicates a low doping efficiency in sol gel processed thin films, but also the ability of sol gel processing to incorporate more magnesium into the oxide than any other processing method. The extensive substitution of the chromium ions also increases the optical transmittance and allows sol gel processed thin films to draw level with thin films deposited by sputtering methods or PLD. Finally, the applicability of the delafossite thin films was proven by the asymmetric current voltage characteristics of heterojunctions between ITO and the delafossites. Shunting problems of the metallic contacts, on the other hand, reveal structural deficites of the delafossites, which should be the subject of further investigations.}, subject = {Transparent-leitendes Oxid}, language = {en} } @phdthesis{Declerck2010, author = {Declerck, P{\´e}lagie}, title = {Synthesis and technological processing of hybrid organic-inorganic materials for photonic applications}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56053}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Im Rahmen dieser Doktorarbeit wurden neue UV-strukturierbare organisch-anorganische hybride Polymere f{\"u}r photonische Anwendungen mit einem hohem Brechungsindex und der M{\"o}glichkeit, sie durch Ein- bzw. Zwei-Photonen-Polymerisation zu strukturieren, entwickelt. Die Materialien wurden in Bezug auf ihre chemische Struktur, ihre optischen Eigenschaften, und ihrer F{\"a}higkeit, durch 1PP und 2PP strukturierbar zu sein, untersucht. Besonders mit 2PP konnte man mit diesen neuartigen hybriden Materialien 3D-Strukturen erzeugen. ie Hydrolyse und Polykondensationsreaktionen wurden mit · Organo-Alkoxysilanen und Titanalkoxiden, modifiziert mit und ohne komplexierende Liganden und · Organo-Alkoxysilanen, Titanalkoxiden und Organophosphors{\"a}ure als Precrusoren durchgef{\"u}hrt. Prim{\"a}res Ziel dieser Arbeit war es, den Brechungsindex von ORMOCER®en, die auf der Basis von Organo-Alkoxysilan-Precursoren ohne Heteroelemente synthetisiert werden, zu vergr{\"o}ßern. Die chemische Struktur der synthetisierten Materialien und somit mit ihr die Parameter, die den Brechungsindex beeinflussen, wurden eingehend untersucht. Insbesondere die Synthese-Parameter, wie das Einsetzen der Titanalkoxide und ihrer Konzentration, der Organo-Alkoxysilane, die Katalysator-Konzentration, die verwendeten L{\"o}sungsmittel und auch die Verfahrensparameter f{\"u}r eine sp{\"a}tere Strukturierung durch lithographische Verfahren, wie die UV-Bestrahlungsdosis, die Initiator-Konzentration und der Entwickler, wurden untersucht.}, subject = {Brechzahl}, language = {en} } @phdthesis{Dehm2010, author = {Dehm, Volker Christoph}, title = {Synthesis and Characterization of an Oligo(Phenylene Ethynylene)-Based Perylene Bisimide Foldamer}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53211}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The present work is part of the currently only rudimentary understanding of the structure-property relationships in the self-assembly of pi-conjugated organic molecules. Such structures may reveal favorable photophysical and semiconducting properties due to the weak non-covalent pi-pi interactions between the monomer units. The specific mutual orientation of the dyes is known to evoke individual functional properties for the condensed matter, however, the related electronic processes are still not well-understood and further enhancements of functional properties are seldom triggered by rational design. The pi-pi self-assembly structures of perylene bisimide (PBI) dyes are promising, versatile materials for organic electronic devices and have been elected for this thesis as an archetype aggregate system to investigate the dye-dye interactions in more detail. In cooperation with experts in the field of spectroscopy and theory the development of reliable routines towards a better understanding of the origins of the functional properties may be feasible, and, on a longer time-line, such knowledge may enable optimization of functional organic materials. Having designed such structures entailed the challenge of developing feasible synthesis strategies, and to actually generate the targeted molecules by synthesis. Several synthesis approaches were conducted until finally a perylene bisimide foldamer was obtained based on a Sonogashira co-polymerization reaction. After purification and enrichment of the larger-sized species by means of semi-preparative gel permeation chromatography (GPC) the average size of an octamer (8500 Da) species was determined by analytical GPC. The low polydispersity index (PD) of 1.1 is indicative of a sharp size distribution of the oligomers. This average size was confirmed by performing diffusion ordered NMR spectroscopy (DOSY). Furthermore, MALDI-TOF mass analysis substantiated the structural integrity of the co-polymerization product. Solvent-dependent UV/vis spectroscopic investigations demonstrated that intramolecular PBI  aggregates are reversibly formed, indicating that this oligomer is able to fold and unfold in the intended manner upon changing external conditions. In the unfolded states, the PBI moieties are closely arranged due to the short OPE bridges (< 2.4 nm), which is expressed by an exciton coupling interaction of the dyes and therefore the characteristic monomer absorption pattern of the PBI chromophore cannot be obtained in the unfolded states. More interestingly, the folded state revealed a pronounced aggregate spectrum of the PBIs, however, striking differences in the shape of the absorption spectrum compared to our previously investigated PBI self-assembly were obtained.}, subject = {Perylenbisdicarboximide 2 μJy at 1 keV were considered. To avoid strong attenuation of the Gamma-rays in the extragalactic infrared background, the redshift was restricted to values between z < 0.15 and z < 0.4, depending on the declination of the objects. The latter determines the zenith distance during culmination which should not exceed 30° (for z < 0.4) and 45° (for z < 0.15), respectively. Between August 2005 and April 2009, a sample of 24 X-ray selected high-frequency peaked blazars has been observed with the MAGIC telescope. Three of them were detected including 1ES 1218+304 being the first high-frequency peaked BL Lacertae object (HBL) to be discovered with MAGIC in VHE Gamma-rays. One previously detected object was not confirmed as VHE emitter in this campaign by MAGIC. A set of 20 blazars previously not detected will be treated more closely in this work. In this campaign, during almost four years ~ 450 hrs or ~ 22\% of the available observation time for extragalactic objects were dedicated to investigate the baseline emission of blazars and their broadband spectral properties in this emission state. For the sample of 20 objects in a redshift range of 0.018 < z < 0.361 integral flux upper limits in the VHE range on the 99.7\% confidence level (corresponding to 3 standard deviations) were calculated resulting in values between 2.9\% and 14.7\% of the integral flux of the Crab Nebula. As the distribution of significances of the individual objects shows a clear shift to positive values, a stacking method was applied to the sample. For the whole set of 20 objects, an excess of Gamma-rays was found with a significance of 4.5 standard deviations in 349.5 hours of effective exposure time. For the first time a signal stacking in the VHE regime turned out to be successful. The measured integral flux from the cumulative signal corresponds to 1.4\% of the Crab Nebula flux above 150 GeV with a spectral index α = -3.15±0.57. None of the objects showed any significant variability during the observation time and therefore the detected signal can be interpreted as the baseline emission of these objects. For the individual objects lower limits on the broad-band spectral indices αX-Gamma between the X-ray range at 1 keV and the VHE Gamma-ray regime at 200 GeV were calculated. The majority of objects show a spectral behaviour as expected from the source class of HBLs: The energy output in the VHE regime is in general lower than in X-rays. For the stacked blazar sample the broad-band spectral index was calculated to αX-Gamma = 1.09, confirming the result found for the individual objects. Another evidence for the revelation of the baseline emission is the broad-band spectral energy distribution (SED) comprising archival as well as contemporaneous multi-wavelength data from the radio to the VHE band. The SEDs of known VHE Gamma-ray sources in low flux states matches well the SED of the stacked blazar sample.}, subject = {MAGIC-Teleskop}, language = {en} } @phdthesis{Glawion2010, author = {Glawion, Sebastian}, title = {Spectroscopic Investigations of Doped and Undoped Transition Metal Oxyhalides}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53169}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In this thesis the electronic and magnetic structure of the transition metal oxyhalides TiOCl, TiOBr and VOCl is investigated. The main experimental methods are photoemission (PES) and x-ray absorption (XAS) spectroscopy as well as resonant inelastic x-ray scattering (RIXS). The results are compared to density-functional theory, and spectral functions from dynamical mean-field theory and different kinds of model calculations. Questions addressed here are those of the dimensionality of the magnetic and electronic interactions, the suitability of the oxyhalides as prototypical strongly correlated model systems, and the possibility to induce a filling-controlled insulator-metal transition. It turns out that TiOCl is a quasi-one-dimensional system with non-negligible two-dimensional coupling, while the one-dimensional character is already quite suppressed in TiOBr. In VOCl no signatures of such one-dimensional behavior remain, and it is two-dimensional. In all cases, frustrations induced by the crystal lattice govern the magnetic and electronic properties. As it turns out, although the applied theoretical approaches display improvements compared to previous studies, the differences to the experimental data still are at least partially of qualitative instead of quantitative nature. Notably, using RIXS, it is possible for the first time in TiOCl to unambiguously identify a two-spinon excitation, and the previously assumed energy scale of magnetic excitations can be confirmed. By intercalation of alkali metal atoms (Na, K) the oxyhalides can be doped with electrons, which can be evidenced and even quantified using x-ray PES. In these experiments, also a particular vertical arrangement of dopants is observed, which can be explained, at least within experimental accuracy, using the model of a so-called "polar catastrophe". However, no transition into a metallic phase can be observed upon doping, but this can be understood qualitatively and quantitatively within an alloy Hubbard model due to the impurity potential of the dopants. Furthermore, in a canonical way a transfer of spectral weight can be observed, which is a characteristic feature of strongly correlated electron systems. Overall, it can be stated that the transition metal oxyhalides actually can be regarded as prototypical Mott insulators, yet with a rich phase diagram which is far from being fully understood.}, subject = {{\"U}bergangsmetall}, language = {en} } @phdthesis{Maier2010, author = {Maier, Florian C.}, title = {Spectromicroscopic characterisation of the formation of complex interfaces}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-65062}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Within the framework of this thesis the mechanisms of growth and reorganisation of surfaces within the first few layers were investigated that are the basis for the fabrication of high quality thin films and interfaces. Two model systems, PTCDA/Ag(111) and CdSe/ZnSe quantum dots (QD), were chosen to study such processes in detail and to demonstrate the power and improvements of the aberration corrected spectromicroscope SMART [1] simultaneously. The measurements benefit especially from the enhanced transmission of the microscope and also from its improved resolution. SMART, the first double-aberration corrected instrument of its kind [2], provided comprehensive methods (LEEM/PEEM, μ-LEED, μ-XPS) to study in-situ and in real time the surface reorganisation and to determine morphology, local structure and local chemical composition of the resulting thin film. Complementarily, a commercial AFM [3] was used ex-situ. XPEEM and μ-XPS measurements were made possible by attaching SMART to the high flux density beamline of the soft-X-ray source BESSY-II [4]. PTCDA/Ag(111) - Growth and structure of the first two layers Although PTCDA/Ag(111) is one of the most intensely studied model systems for the growth of organic semiconductor thin films, it still offers new insights into a complex growth behaviour. This study enlightens the temperature dependant influence of morphological features as small as monatomic Ag steps on the growth process of the first two layers. At low temperatures, single Ag steps act as diffusion barriers. But interdiffusion was observed already for the 2nd layer whereas domain boundaries in the 1st PTCDA-layer persist for crystallite growth in the 2nd layer. 1st layer islands are more compact and the more dendritic development of the 2nd layer indicates reduced interaction strength between 2nd and 1st layer. These findings were explained by a model consisting of structural and potential barriers. The second part of the PTCDA study reveals a variety of phases that appears only if at least two layers are deposited. Besides the six known rotational domains of the interface system PTCDA/Ag(111) [5], a further manifold of structures was discovered. It does not only show a surprising striped image contrast, but the 2nd layer also grows in an elongated way along these so-called 'ripples'. The latter show a rather large period and were found in a wide temperature range. Additionally the μ-LEED pattern of such a domain shows a new super-superstructure as well. This phase is explained by a structural model that introduces a rotated, more relaxed domain in the 2nd layer that does not exist in the first layer. Its structural parameters are similar to those of the bulk unitcells of PTCDA. The model is confirmed by the observation of two different rotational domains that grow on top of one single 'substrate' domain in the 1st layer. The orientations of the ripple phases fit as well to the predictions of the model. The growth direction along the ripples corresponds to the short diagonal of the super-superstructure unitcell with diamond-like shape. CdSe/ZnSe - Inverse structuring by sublimation of an α-Te cap With the second model system the formation of CdSe quantum dots (QD) from strained epi-layers was investigated. In this case the structures do not form during deposition, but rather during sublimation of the so-called 'ignition cap'. For these pilot experiments not only the process of QD formation itself was of interest, but also the portability of the preparation and the prevention of contaminations. It was found that the α-Se is well suited for capping and the last step of the QD preparation, the sublimation of the α-Te cap, needs a sufficiently high rate in rise of temperature. Subsequently the cap, the process of desorption and the final surface with the quantum structures were investigated in detail. The cap was deposited by the MBE-group in W{\"u}rzburg as an amorphous Te layer but was found to contain a variety of structures. Holes, cracks, and micro-crystallites within an α-Te matrix were identified. Sublimation of the "ignition cap" was observed in real-time. Thus the discovered cap-structures could be correlated with the newly formed features as, e.g., QDs on the bare CdSe surface. Since CdSe/ZnSe QDs prefer to form in the neighbourhood of the Te μ-crystallites, Te was found to play a major role in their formation process. Different explanations as the impact of Te as a surfactant, an enhanced mobility of adatoms or as stressor nuclei are discussed. The spectromicroscopic characterisation of the CdSe surface with QDs revealed the crystallographic directions. An increased Cd signal of the film was found at positions of former holes. Several possibilities as segregation or surface termination are reviewed, that might explain this slight Cd variation. Therewith, an important step to a detailed understanding of the complex reorganisation process in coating systems could be achieved.}, subject = {Halbleiterschicht}, language = {en} } @article{SchneiderPliushchElHajjetal.2010, author = {Schneider, Eberhard and Pliushch, Galyna and El Hajj, Nady and Galetzka, Danuta and Puhl, Alexander and Schorsch, Martin and Frauenknecht, Katrin and Riepert, Thomas and Tresch, Achim and Mueller, Annette M. and Coerdt, Wiltrud and Zechner, Ulrich and Haaf, Thomas}, title = {Spatial, temporal and interindividual epigenetic variation of functionally important DNA methylation patterns}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68371}, year = {2010}, abstract = {DNA methylation is an epigenetic modification that plays an important role in gene regulation. It can be influenced by stochastic events, environmental factors and developmental programs. However, little is known about the natural variation of genespecific methylation patterns. In this study, we performed quantitative methylation analyses of six differentially methylated imprinted genes (H19, MEG3, LIT1, NESP55, PEG3 and SNRPN), one hypermethylated pluripotency gene (OCT4) and one hypomethylated tumor suppressor gene (APC) in chorionic villus, fetal and adult cortex, and adult blood samples. Both average methylation level and range of methylation variation depended on the gene locus, tissue type and/or developmental stage. We found considerable variability of functionally important methylation patterns among unrelated healthy individuals and a trend toward more similar methylation levels in monozygotic twins than in dizygotic twins. Imprinted genes showed relatively little methylation changes associated with aging in individuals who are >25 years. The relative differences in methylation among neighboring CpGs in the generally hypomethylated APC promoter may not only reflect stochastic fluctuations but also depend on the tissue type. Our results are consistent with the view that most methylation variation may arise after fertilization, leading to epigenetic mosaicism.}, subject = {Medizin}, language = {en} } @article{DrescherBluethgenSchmittetal.2010, author = {Drescher, Jochen and Bluethgen, Nico and Schmitt, Thomas and Buehler, Jana and Feldhaar, Heike}, title = {Societies Drifting Apart? Behavioural, Genetic and Chemical Differentiation between Supercolonies in the Yellow Crazy Ant Anoplolepis gracilipes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68573}, year = {2010}, abstract = {Background: In populations of most social insects, gene flow is maintained through mating between reproductive individuals from different colonies in periodic nuptial flights followed by dispersal of the fertilized foundresses. Some ant species, however, form large polygynous supercolonies, in which mating takes place within the maternal nest (intranidal mating) and fertilized queens disperse within or along the boundary of the supercolony, leading to supercolony growth (colony budding). As a consequence, gene flow is largely confined within supercolonies. Over time, such supercolonies may diverge genetically and, thus, also in recognition cues (cuticular hydrocarbons, CHC's) by a combination of genetic drift and accumulation of colony-specific, neutral mutations. Methodology/Principal Findings: We tested this hypothesis for six supercolonies of the invasive ant Anoplolepis gracilipes in north-east Borneo. Within supercolonies, workers from different nests tolerated each other, were closely related and showed highly similar CHC profiles. Between supercolonies, aggression ranged from tolerance to mortal encounters and was negatively correlated with relatedness and CHC profile similarity. Supercolonies were genetically and chemically distinct, with mutually aggressive supercolony pairs sharing only 33.1\%617.5\% (mean 6 SD) of their alleles across six microsatellite loci and 73.8\%611.6\% of the compounds in their CHC profile. Moreover, the proportion of alleles that differed between supercolony pairs was positively correlated to the proportion of qualitatively different CHC compounds. These qualitatively differing CHC compounds were found across various substance classes including alkanes, alkenes and mono-, di- and trimethyl-branched alkanes. Conclusions: We conclude that positive feedback between genetic, chemical and behavioural traits may further enhance supercolony differentiation through genetic drift and neutral evolution, and may drive colonies towards different evolutionary pathways, possibly including speciation.}, subject = {Ameisen}, language = {en} } @phdthesis{Burkard2010, author = {Burkard, Natalie}, title = {Signal{\"u}bertragungswege und Pr{\"a}ventionsm{\"o}glichkeiten der kardialen Hypertrophie : conditional overexpression of neuronal nitric oxide synthase is cardioprotective in ischemia-reperfusion}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51832}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Zusammenfassung: Wie fr{\"u}her schon gezeigt, wird der L-Typ Ca2+-Kanal durch eine induzierbare, myokardspezifische {\"U}berexpression der neuronalen Stickstoffmonoxidsynthase (nNOS) inhibiert. Gleichzeitig bewirkt diese {\"U}berexpression eine verminderte kardiale Kontraktilit{\"a}t1 (Burkard N. et al. (2007). Circ Res 100, 32-44). nNOS interagiert mit vielen verschiedenen Kompartimenten und Kan{\"a}len innerhalb der Zelle. In dieser Arbeit wurde gezeigt, dass eine nNOS {\"U}berexpression nach Isch{\"a}mie-Reperfusion kardioprotektiv wirkt. Dieses wird durch eine Inhibition der Mitochondrienfunktion und durch eine Verminderung der reaktiven Sauerstoffspezies (ROS) erm{\"o}glicht. In einer fr{\"u}heren Arbeit wurde der Effekt der induzierbaren und myokardspezifischen {\"U}berexpression von nNOS unter physiologischen Bedingungen am transgenen Tiermodell untersucht. Diese Arbeit besch{\"a}ftigt sich nun mit der {\"U}berexpression von nNOS unter pathophysiologischen (Isch{\"a}mie-Reperfusion) Bedingungen. Ein Isch{\"a}mie-Reperfusions-Schaden bewirkt bei Wildtyp-M{\"a}usen, sowie bei transgener nNOS {\"U}berexpression eine Anreicherung von nNOS in den Mitochondrien. Elektronenmikroskopische Aufnahmen von Mausmyokard haben gezeigt, dass bei {\"U}berexpression nNOS zus{\"a}tzlich in den Mitochondrien lokalisiert ist. Diese Translokation von nNOS in die Mitochondrien ist abh{\"a}ngig von HSP90. Isch{\"a}mie- Reperfusionsexperimente an isolierten M{\"a}useherzen zeigten einen kardioprotektiven Effekt der nNOS {\"U}berexpression (30min post ischemia, LVDP 27.0±2.5mmHg vs. 45.2±1.9mmHg, n=12, p<0.05). Dieser positive Effekt konnte bei der Bestimmung der Infarktgr{\"o}ße best{\"a}tigt werden. nNOS {\"u}berexprimierende M{\"a}use hatten eine kleinere Infarktgr{\"o}ße nach Isch{\"a}mie-Reperfusion (36.6±8.4 relative \% vs. 61.1±2.9 relative \%, n=8, p<0.05). Die {\"U}berexpression von nNOS bewirkte ebenfalls einen signifikanten Anstieg des mitochondrialen Nitrit-Levels, begleitet von einer Verminderung der Cytochrom C Oxidase Aktivit{\"a}t (72.0±8.9units/ml in nNOS overexpressing mice vs. 113.2±17.1units/ml in non-induced mice, n=12, p<0.01), was zu einer Hemmung der Mitochondrienfunktion f{\"u}hrt. Dementsprechend war der Sauerstoffverbrauch (gemessen an isolierten Herzmuskelstreifen) schon unter basalen Bedingungen beinNOS {\"U}berexpression vermindert (0.016±0.0015 vs. 0.024±0.006ml[O2] x mm-3 x min-1, n=13, p<0.05). Außerdem war die ROS Konzentration in Herzen von nNOS {\"u}berexprimierenden M{\"a}usen signifikant vermindert (6.14±0.685 vs. 14.53±1.7μM, n=8, p<0.01). Die Zugabe von verschiedenen Inhibitoren, Western Blot- und Aktivit{\"a}tsuntersuchungen zeigten schließlich, dass diese niedrigere ROS Konzentration durch eine verminderte Xanthin Oxidoreduktase Aktivit{\"a}t hervorgerufen wurde. Zusammenfassend hat diese Arbeit gezeigt, dass eine induzierbare und myokardspezifische {\"U}berexpression von nNOS unter pathophysiologischen Bedingungen (Isch{\"a}mie-Reperfusion) kardioprotektiv wirkt. Zus{\"a}tzlich zu der Verminderung des myokardialen Ca2+-{\"U}berschusses nach Reperfusion k{\"o}nnte dieser protektive Effekt durch eine Hemmung der Mitochondrienfunktion bedingt sein, schließlich wird der Sauerstoffverbrauch schon unter basalen Bedingungen reduziert}, subject = {Herzhypertrophie}, language = {en} } @phdthesis{Fazeli2010, author = {Fazeli, Gholamreza}, title = {Signaling in the induction of genomic damage by endogenous compounds}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55634}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Reactive oxygen species (ROS) are continuously generated in cells and are involved in physiological processes including signal transduction but also their damaging effects on biological molecules have been well described. A number of reports in the literature implicate excessive oxidative stress and/or inadequate antioxidant defense in the pathogenesis of cancer, atherosclerosis, chronic and age related disorders. Several studies have indicated that activation of the renin-angiotensin-aldosterone-system can lead to the formation of ROS. Epidemiological studies have revealed higher renal cell cancer incidences and also higher cancer mortalities in hypertensive individuals. Recently, our group has shown that perfusion of the isolated mouse kidney with Ang II or treatment of several cell lines with Ang II leads to formation of DNA damage and oxidative base modifications. Here, we tried to scrutinize the pathway involved in genotoxicity of Ang II. We confirmed the genotoxicity of Ang II in two kidney cell lines of human origin. Ang II treatment led to the production of superoxide anions which we could hinder when we used the membrane permeable superoxide dismutase (SOD) mimetic TEMPOL. One of the enzymes which is activated in the cells after Ang II treatment and is able to produce ROS is NADPH oxidase. We demonstrated the activation of NADPH oxidase in response to Ang II by upregulation of its p47 subunit using RT-PCR. Also, pPhosphorylation of p47 subunit of NADPH oxidase after Ang II treatment was enhanced. Using two inhibitors we showed that NADPH oxidase inhibition completely prevents DNA damage by Ang II treatment. To differentiate between Nox2 and Nox4 isoforms of NADPH oxidase subunits in the genotoxicity of Ang II, we performed siRNA inhibition and found a role only for Nox4, while Nox2 was not involved. Next, we investigated PKC as a potential activator of NADPH oxidase. We showed that PKC becomes phosphorylated after Ang II treatment and also that inhibition of PKC hinders Ang II from damaging the cells. Our results from using several inhibitors of different parts of the pathway revealed that PKC activation in this pathway is dependent on the action of PLC on membrane phospholipids and production of IP3. IP3 binds to its receptor at endoplasmic reticulum (ER), opening a channel which allows calcium efflux into the cytoplasm. In this manner, both ER calcium stores and extracellular calcium cooperate so that Ang II can exert its genotoxic effect. PLC is activated by AT1R stimulation. We could also show that the genotoxicity of Ang II is mediated via AT1R signaling using the AT1R antagonist candesartan. In conclusion, here we have shown that Ang II is able to damage genomic damage in cell lines of kidney origin. The observed damage is associated with production of ROS. A decrease in Ang II-induced DNA damage was observed after inhibition of G-proteins, PLC, PKC and NADPH oxidase and interfering with intra- as well as extracellular calcium signaling. This leads to the following preliminary model of signaling in Ang II-induced DNA damage: binding of Ang II to the AT1 receptor activates PLC via stimulation of G-proteins, resulting in the activation of PKC in a calcium dependent manner which in turn, activates NADPH oxidase. NADPH oxidase with involvement of its Nox4 subunit then produces reactive oxygen species which cause DNA damage. Dopamine content and metabolism in the peripheral lymphocytes of PD patients are influenced by L-Dopa administration. The PD patients receiving a high dose of L-Dopa show a significantly higher content of dopamine in their lymphocytes compared to PD patients who received a low dose of L-Dopa or the healthy control. Central to many of the processes involved in oxidative stress and oxidative damage in PD are the actions of monoamine oxidase (MAO), the enzyme which is responsible for the enzymatic oxidation of dopamine which leadsing to production of H2O2 as a by-product. We investigated whether dopamine oxidation can cause genotoxicity in lymphocytes of PD patents who were under high dose L-Dopa therapy and afterward questioned the occurrence of DNA damage after dopamine treatment in vitro and tried to reveal the mechanism by which dopamine exerts its genotoxic effect. The frequency of micronuclei in peripheral blood lymphocytes of the PD patients was not elevated compared to healthy age-matched individuals, although the formation of micronuclei revealed a positive correlation with the daily dose of L-Dopa administration in patients who received L-Dopa therapy together with dopamine receptor agonists. In vitro, we describe an induction of genomic damage detected as micronucleus formation by low micromolar concentrations in cell lines with of different tissue origins. The genotoxic effect of dopamine was reduced by addition of the antioxidants TEMPOL and dimethylthiourea which proved the involvement of ROS production in dopamine-induced DNA damage. To determine whether oxidation of dopamine by MAO is relevant in its genotoxicity, we inhibited MAO with two inhibitors, trans-2-phenylcyclopropylamine hydrochloride (PCPA) and Ro 16-6491 which both reduced the formation of micronuclei in PC-12 cells. We also studied the role of the dopamine transporter (DAT) and dopamine type 2 receptor (D2R) signaling in the genotoxicity of dopamine. Inhibitors of the DAT, GBR-12909 and nomifensine, hindered dopamine-induced genotoxicity. These results were confirmed by treatment of MDCK and MDCK-DAT cells, the latter containing the human DAT gene, with dopamine. Only MDCK-DAT cells showed elevated chromosomal damage and dopamine uptake. Although stimulation of D2R with quinpirole in the absence of dopamine did not induce genotoxicity in PC-12 cells, interference with D2R signaling using D2R antagonist and inhibition of G-proteins, phosphoinositide 3 kinase and extracellular signal-regulated kinases reduced dopamine-induced genotoxicity and affected the ability of DAT to take up dopamine. Furthermore, the D2R antagonist sulpiride inhibited the dopamine-induced migration of DAT from cytosol to cell membrane. Overall, the neurotransmitter dopamine causes DNA damage and oxidative stress in vitro. There are also indications that high dose L-Dopa therapy might lead to oxidative stress. Dopamine exerts its genotoxicity in vitro upon transport into the cells and oxidization oxidation by MAO. Transport of dopamine by DAT has the central role in this process. D2R signaling is involved in the genotoxicity of dopamine by affecting activation and cell surface expression of DAT and hence modulating dopamine uptake. We provided evidences for receptor-mediated genotoxicity of two compounds with different mechanism of actions. The involvement of these receptors in many human complications urges more investigations to reveal whether abnormalities in the endogenous compounds-mediated signaling can play a role in the initiation of new conditions like carcinogenesis.}, subject = {Angiotensin II}, language = {en} } @phdthesis{Ruchty2010, author = {Ruchty, Markus}, title = {Sensory basis of thermal orientation in leaf-cutting ants}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48906}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Leaf-cutting ants have a highly developed thermal sense which the insects use to regulate the own body temperature and also to optimize brood and fungus development. Apart from the already described temperature guided behaviors inside the nest it is unknown to what extent the ants may use their thermal sense outside the nest. As part of the present thesis, the question was addressed whether leaf-cutting ants (Atta vollenweideri) are able to learn the position of a warm object as landmark for orientation during foraging. Using absolute conditioning, it was shown that ten training trials are sufficient to elicit the association be-tween food reward and the temperature stimulus. In the test situation (without reward) a significantly higher amount of ants preferred the heated site compared to the unheated con-trol. Importantly, thermal radiation alone was sufficient to establish the learned association and served as orientation cue during the test situation (chapter IV). Based on the experi-mental design used in the previous chapter, the localization of thermosensitive neurons, which detect the underlying thermal stimuli, is restricted to the head or the antennae of the ants. The antennal sensillum coeloconicum is a potential candidate to detect the thermal stimuli during the orientation behavior. In chapter V the sensillum coeloconicum of Atta vollenweideri was investigated concerning its gross morphology, fine-structure and the phy-siology of the associated thermosensitive neuron. The sensillum is predominantly located on the apical antennal segment (antennal tip) where around 12 sensilla are clustered, and it has a peg-in-pit morphology with a double walled, multiporous peg. The sensory peg is deeply embedded in a cuticular pit, connected to the environment only by a tiny aperture. The sen-sillum houses three receptor neurons of which one is thermosensitive whereas the sensory modality of the other two neurons remains to be shown. Upon stimulation with a drop in temperature, the thermosensitve neuron responds with a phasic-tonic increase in neuronal activity (cold-sensitive neuron) and shows rapid adaptation to prolonged stimulation. In ad-dition, it is shown that thermal radiation is an effective stimulus for the thermosensitive neuron. This is the first evidence that sensilla coeloconica play an important role during the thermal orientation behavior described in chapter IV. During the test situation of the classic-al conditioning paradigm, the ants showed rapid antennal movements, indicating that they scan their environment in order to detect the heated object. Rapid antennal movements will result in rapid discontinuities of thermal radiation that re-quire thermosensitive neurons with outstanding sensitivity and high temporal resolution. In Chapter VI the question was addressed whether the thermosensitive neuron of the sensilla coeloconica fulfils these preconditions. Extracellular recordings revealed that the neuron is extremely sensitive to temperature transients and that, due to the response dynamics, an estimated stimulus frequency of up to 5 Hz can be resolved by the neuron. Already a tem-perature increase of only 0.005 °C leads to a pronounced response of the thermosensitive neuron. Through sensory adaptation, the sensitivity to temperature transients is maintained over a wide range of ambient temperatures. The discovered extreme sensitivity, the high temporal resolution and the pronounced adaptation abilities are further evidence support-ing the idea that sensilla coeloconica receive information of the thermal environment, which the ants may use for orientation. In order to understand how the ants use their thermal environment for orientation, it is ne-cessary to know where and how thermal information is processed in their central nervous system. In Chapter VII the question is addressed where in the brain the thermal information, specifically received by the thermosensitive neuron of sensilla coeloconica, is represented. By selectively staining single sensilla coeloconica, the axons of the receptor neurons could be tracked into the antennal lobe of Atta vollenweideri workers. Each of the three axons termi-nated in a single functional unit (glomerulus) of the antennal lobe. Two of the innervated glomeruli were adjacent to each other and are located lateral, while the third one was clear-ly separate and located medial in the antennal lobe. Using two-photon Ca2+ imaging of an-tennal lobe projection neurons, the general representation of thermal information in the antennal lobe was studied. In 11 investigated antennal lobes up to six different glomeruli responded to temperature stimulation in a single specimen. Both, warm- and cold-sensitive glomeruli could be identified. All thermosensitive glomeruli were located in the medial half of the antennal lobe. Based on the correlative evidence of the general representation of thermal information and the results from the single sensilla stainings, it is assumed that thermal information received by sensilla coeloconica is processed in the medial of the three target glomeruli. This part of the thesis shows the important role of the antennal lobe in temperature processing and links one specific thermosensitive neuron to its target region (a single glomerulus). In chapter V it was shown that the sensilla coeloconica are clustered at the antennal tip and have an extraordinary peg-in-pit morphology. In the last chapter of this thesis (Chapter VIII) the question is addressed whether the morphology of the sensilla coeloconica predicts the receptive field of the thermosensitive neuron during the detection of thermal radiation. The sensory pegs of all sensilla coeloconica in the apical cluster have a similar orientation, which was not constraint by the shape of the antennal tip where the cluster is located. This finding indicates that the sensilla coeloconica function as a single unit. Finally the hypothesis was tested whether a single sensillum could be direction sensitive to thermal radiation based on its eye-catching morphology. By stimulating the thermosensitive neuron from various angles around the sensillum this indeed could be shown. This is the last and most significant evi-dence that the sensilla coeloconica may be adapted to detect spatially distributed heated objects in the environment during the thermal landmark orientation of ants.}, subject = {Neurobiologie}, language = {en} } @article{WilbertGuckenbergerPolatetal.2010, author = {Wilbert, Juergen and Guckenberger, Matthias and Polat, Buelent and Sauer, Otto and Vogele, Michael and Flentje, Michael and Sweeney, Reinhart A.}, title = {Semi-robotic 6 degree of freedom positioning for intracranial high precision radiotherapy; first phantom and clinical results}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68613}, year = {2010}, abstract = {Background: To introduce a novel method of patient positioning for high precision intracranial radiotherapy. Methods: An infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD™) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction. The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients. Results: Phantom and volunteer manual IR-based prepositioning to within ± 2 mm and ± 2° in 6DoF was possible within a mean(± SD) of 90 ± 31 and 56 ± 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 ± 0.2 mm and 0.7 ± 0.8° respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102) was 1.6 ± 0.8 mm while intra-fraction movement (n = 110) was 0.6 ± 0.4 mm. Conclusions: This novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intrafraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient comfort.}, subject = {Strahlentherapie}, language = {en} } @phdthesis{TranVan2010, author = {Tran-Van, Hieu}, title = {Semaphorin receptors in the immunological synapse: regulation and measles virus-driven modulation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53926}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {J{\"a}hrlich gehen ca. 164000 Todesf{\"a}lle (WHO, 2008) auf eine Infektion mit Masernviren (MV) zur{\"u}ck. Die Hauptursache f{\"u}r den t{\"o}dlichen Verlauf der Krankheit ist die MV-induzierte Immunsuppression, deren zugrunde liegende Mechanismen noch nicht v{\"o}llig aufgekl{\"a}rt sind. Es gibt Hinweise darauf, dass MV einerseits die Funktionalit{\"a}t von T-Zellen beeintr{\"a}chtigt, indem es die Aktindynamik behindert, und andererseits dendritische Zellen (DC) infiziert, was dazu f{\"u}hrt, dass sie T-Zellen nicht mehr vollst{\"a}ndig aktivieren k{\"o}nnen. W{\"a}hrend der Entwicklung bzw. des Wachstums von Neuronen kommt es zum Kollaps wachsender Dendriten, wenn Semaphorine (insbesondere SEMA3A) an den Rezeptor Plexin-A1 (plexA1) und seinem Korezeptor Neuropilin-1 (NP-1) binden. Dieser Kollaps wird durch interferenz mit der Aktindynamik verursacht. In dieser Studie wurde die Funktion dieser drei Molek{\"u}le in Immunzellen bzw. ihre Rolle in der MV-induzierten Immunsuppression untersucht. Es konnte gezeigt werden, dass plexA1 eine wichtige Komponente der humanen immunologischen Synapse (IS) ist. Nach CD3/CD28-Ligation kommt es zur transienten Translokation zur T-Zelloberfl{\"a}che und zur Akkumulation an der Kontaktfl{\"a}che zwischen T-Zelle und DC bzw. α-CD3/CD28 beschichteten Mikropartikeln. Wird die plexA1-Expression inhibiert (RNAi) oder die plexA1-Funktion gest{\"o}rt (exogenes Blockieren oder Expression einer dominant negativen Mutante), ist die T-Zellexpansion reduziert. Nach MV-Exposition ist die Translokation von plexA1 und NP-1, ebenfalls einem wichtigen Bestandteil der immunologischen Synapse, zur Kontaktfl{\"a}che auf T-Zellseite gest{\"o}rt. Des Weiteren behindert eine MV-Infektion den plexA1/NP-1-Metabolismus in reifenden DC und f{\"u}hrt zus{\"a}tzlich zu einer fr{\"u}hen und starken Aussch{\"u}ttung von SEMA3A durch DC, insbesondere in Gegenwart allogener T-Zellen. Durch rasterelektronenmikroskopische Aufnahmen wurde gezeigt, dass SEMA3A einen transienten Verlust aktinbasierter Zellforts{\"a}tze bei T-Zellen zur Folge hat. Zus{\"a}tzlich reduziert SEMA3A das chemotaktische Migrationsverhalten von DC und T Zell und die Frequenz ihrer Konjugat-Bildung. Zusammenfassend stellt sich die Situation so dar, dass MV die Semaphorinrezeptorfunktion zum einen dadurch beeintr{\"a}chtigt, dass es die Rekrutierung der Rezeptoren zur IS verhindert und zum anderen zur verfr{\"u}hten Aussch{\"u}ttung des kollapsinduzierenden Liganden SEMA3A f{\"u}hrt. Beide Ph{\"a}nomene k{\"o}nnten einen wichtigen Beitrag zur MV-induzierten Immunsuppression leisten.}, subject = {Masernvirus}, language = {en} } @article{PratiharGhoshStepanenkoetal.2010, author = {Pratihar, Pampa and Ghosh, Suhrit and Stepanenko, Vladimir and Patwardhan, Sameer and Grozema, Ferdinand C. and Siebbeles, Laurens D. A. and W{\"u}rthner, Frank}, title = {Self-assembly and semiconductivity of an oligothiophene supergelator}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67817}, year = {2010}, abstract = {A bis(trialkoxybenzamide)-functionalized quaterthiophene derivative was synthesized and its self-assembly properties in solution were studied. In non-polar solvents such as cyclohexane, this quaterthiophene π-system formed fibril aggregates with an H-type molecular arrangement due to synergistic effect of hydrogen bonding and π-stacking. The self-assembled fibres were found to gelate numerous organic solvents of diverse polarity. The charge transport ability of such elongated fibres of quaterthiophene π-system was explored by the pulse radiolysis time resolved microwave conductivity (PR-TRMC) technique and moderate mobility values were obtained. Furthermore, initial AFM and UV-vis spectroscopic studies of a mixture of our electron-rich quaterthiophene derivative with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) revealed a nanoscale segregated assembly of the individual building blocks in the blend.}, subject = {Organische Chemie}, language = {en} } @phdthesis{Keller2010, author = {Keller, Alexander}, title = {Secondary (and tertiary) structure of the ITS2 and its application for phylogenetic tree reconstructions and species identification}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56151}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Biodiversity may be investigated and explored by the means of genetic sequence information and molecular phylogenetics. Yet, with ribosomal genes, information for phylogenetic studies may not only be retained from the primary sequence, but also from the secondary structure. Software that is able to cope with two dimensional data and designed to answer taxonomic questions has been recently developed and published as a new scientific pipeline. This thesis is concerned with expanding this pipeline by a tool that facialiates the annotation of a ribosomal region, namely the ITS2. We were also able to show that this states a crucial step for secondary structure phylogenetics and for data allocation of the ITS2-database. This resulting freely available tool determines high quality annotations. In a further study, the complete phylogenetic pipeline has been evaluated on a theoretical basis in a comprehensive simulation study. We were able to show that both, the accuracy and the robustness of phylogenetic trees are largely improved by the approach. The second major part of this thesis concentrates on case studies that applied this pipeline to resolve questions in taxonomy and ecology. We were able to determine several independent phylogenies within the green algae that further corroborate the idea that secondary structures improve the obtainable phylogenetic signal, but now from a biological perspective. This approach was applicable in studies on the species and genus level, but due to the conservation of the secondary structure also for investigations on the deeper level of taxonomy. An additional case study with blue butterflies indicates that this approach is not restricted to plants, but may also be used for metazoan phylogenies. The importance of high quality phylogenetic trees is indicated by two ecological studies that have been conducted. By integrating secondary structure phylogenetics, we were able to answer questions about the evolution of ant-plant interactions and of communities of bacteria residing on different plant tissues. Finally, we speculate how phylogenetic methods with RNA may be further enhanced by integration of the third dimension. This has been a speculative idea that was supplemented with a small phylogenetic example, however it shows that the great potential of structural phylogenetics has not been fully exploited yet. Altogether, this thesis comprises aspects of several different biological disciplines, which are evolutionary biology and biodiversity research, community and invasion ecology as well as molecular and structural biology. Further, it is complemented by statistical approaches and development of informatical software. All these different research areas are combined by the means of bioinformatics as the central connective link into one comprehensive thesis.}, subject = {Phylogenie}, language = {en} } @phdthesis{Junker2010, author = {Junker, Robert R.}, title = {Scents as Floral Defence : Impact on Species and Communities, Mechanisms and Ecological Consequences}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51827}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Floral scents are compositions of diverse volatile substances. Despite the chemical complexity, the interpretation of their ecological relevance was mostly confined to the attractive function facilitating interactions with pollinators. However, the negative impact on plants' reproduction by non-pollinating flower visitors is pronounced and demands floral adaptations that exclude antagonists. The aim of this dissertation was to explore the defensive properties of floral odours and to imbed them into ecological contexts. The thesis covered four scopes: the scents' impact on individual species and on flower-visitor communities, the mechanisms that explain the dual function of floral volatiles (attraction and defence), and the ecological consequences of missing defences for plants and pollinators. The most important floral antagonists that are known to reduce the reproductive fitness of plants were identified and their responses towards floral scents were examined. We found that representatives of non-pollinating florivores (bush crickets), predators that lure for pollinators (spiders), and microorganisms that potentially colonize petals were repelled, deterred or inhibited in their growth by floral secondary metabolites. An earlier study revealed the same effect on nectar thieving ants. These experimental studies clearly demonstrate that scents universally serve as floral defences that have the potential to reduce or even prevent the visitation and exploitation of flowers by these antagonists. Within diverse communities, we tested whether species-specific responses to odours reflect the structure of naturally occurring flower-visitor interactions in order to examine the ecological importance of defensive floral scents. On three Hawaiian Islands, ant-flower interactions involving co-occurring native and introduced plants were observed. Ants were historically absent from the geographically isolated Hawaiian archipelago. Thus, we hypothesized that native Hawaiian plants lack floral features that exclude ants and therefore would be heavily exploited by introduced, invasive ants. We quantified the residual interaction strength of each pair of ant/plant species as the deviation of the observed interaction frequency from a null-model prediction based on available nectar sugar in a local plant community and local ant activity at sugar baits. As predicted, flowers of plants that are endemic or indigenous to Hawaii were stronger exploited by ants than flowers of co- occurring introduced plants, which share an evolutionary history with ants. We showed experimentally that the absence of ants on flowers of most introduced and few native plants species was due to morphological barriers and/or repellent floral scents, examined in a mobile olfactometer. Analysis of floral volatiles, however, revealed no consistent ant- repellent "syndrome", probably due to the high chemical variability within the floral scent bouquets. On a fallow land in Germany, we linked the responses of receivers (flower visitors) towards signals (flower scent) with the structure of a highly diverse natural flower-insect network. For each interaction, we defined link temperature - a newly developed metric - as the deviation of the observed interaction strength from neutrality, assuming that animals randomly interact with flowers. Link temperature was positively correlated to the specific visitors' responses to floral scents. Thus, communication between plants and consumers via phytochemical signals reflects a significant part of the microstructure in a complex network. Negative as well as positive responses towards floral scents contributed to these results, where individual experience was important, apart from innate behaviour. The demonstration of the contrasting functions of floral scents that control the visitor spectrum of flowers represents the first evidence that floral scents act as filters allowing access to some flower visitors but simultaneously exclude others. These findings raise the central question of this thesis: what evolutionary mechanism explains the dual function of floral scents? The view of flower visitors as mutualistic and antagonistic agents considers primarily the interest of plants. A classification emphasizing the consumer's point of view, however, may be more useful when considering adaptations of animals to flower visits. Therefore, we introduced a novel classification that acknowledges the consumers' interest in the interaction: some animals evolved an obligate dependence on floral resources, others use nectar and pollen as supplement to their diet and are thus regarded as facultative flower visitors. In a meta-analysis covering 18 studies on the responses of animals to floral scents, we assigned the animals to the categories of obligate or facultative flower visitors. Their responses to floral scents were compared. On average, obligate flower visitors, often corresponding to pollinators, were attracted to floral scent compounds. In contrast, facultative and mainly antagonistic visitors were strongly repelled by flower odours. The findings confirm that floral scents have a dual function both as attractive and defensive cues. Whether an animal depends on floral resources determines its response to these signals, suggesting that obligate flower visitors evolved a tolerance against primarily defensive compounds. These findings were confirmed in an experimental study. We conclude that floral scents protect flowers against visitors that would otherwise reduce the reproductive success of plants. In Hawaii, where flowers do not have defensive means against ants, we studied the impact of ants on the pollination effectiveness of endemic and introduced bees and on the fruit set of an endemic tree Metrosideros polymorpha (Myrtaceae). Ants were dominant nectar-consumers that mostly depleted the nectar of visited inflorescences. Accordingly, the visitation frequency, duration, and consequently the pollinator effectiveness of nectar-foraging bees strongly decreased on ant-visited flowers, whereas pollen-collecting bees remained largely unaffected by ants. Overall, endemic bees (Hylaeus spp.) were much poorer pollinators than introduced honeybees (Apis mellifera). The average net effect of ants on pollination of M. polymorpha was neutral, corresponding to a similar fruit set of ant-visited and ant-free inflorescences. A second Hawaiian plant species, Vaccinium reticulatum (Ericaceae), was visited by the caterpillars of an introduced plume moth (Stenoptilodes littoralis) that destroyed buds and flowers of this species. The ants' presence on flowers strongly reduced flower parasitism by the caterpillars and consequently decreased the loss of flowers and buds. This is, to our knowledge, the first documented mutualism between invasive ants and an endemic plant species in Hawaii. Thus, ants that have been shown to be detrimental flower visitors elsewhere, had neutral (M. polymorpha) or even positive (V. reticulatum) effects on endemic Hawaiian plants. However, their overall negative effect on the Hawaiian flora and fauna should not be disregarded.}, subject = {Bl{\"u}te}, language = {en} } @phdthesis{Heupel2010, author = {Heupel, Wolfgang-Moritz Felix}, title = {Role and modulation of cadherins in pathologic processes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52716}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Ca2+ dependent cell adhesion molecules (cadherins) are central for a variety of cell and tissue functions such as morphogenesis, epithelial and endothelial barrier formation, synaptic function and cellular signaling. Of paramount importance for cadherin function is their specific extracellular adhesive trans-interaction. Cadherins are embedded in a cellular environment of intracellular and extracellular regulators that modify cadherin binding in response to various physiological and pathological stimuli. Most experimental approaches used for studying cadherin interaction however lack a physiological proof of principle mostly by not investigating cadherins in their physiological environment. In the present cumulative dissertation, experimental approaches were applied to characterize and modulate vascular endothelial (VE)-cadherin and desmocadherin functions in the (patho-)physiological contexts of endothelial permeability regulation and disturbance of epidermal barrier function, which is typical to the blistering skin disease pemphigus, respectively. Whereas VE-cadherin is a key regulator of the endothelial barrier that separates the blood compartment from the interstitial space of tissues, desmosomal cadherins are crucial for maintenance of epidermal integrity and separation of the external environment from the body's internal milieu. Cadherin functions were both investigated in cell-free and cell-based conditions: by using biophysical single molecule techniques like atomic force microscopy (AFM), cadherin function could be investigated in conditions, where contributions of intracellular signaling were excluded. These experiments were, however, compared and combined with cell-based experiments in which cadherins of epidermal or endothelial cell cultures were probed by laser force microscopy (laser tweezers), fluorescence recovery after photobleaching (FRAP) and other techniques. The autoimmune blistering skin diseases pemphigus foliaceus (PF) and pemphigus vulgaris (PV) are caused by autoantibodies directed against the extracellular domains of the desmosomal cadherins desmoglein (Dsg) 1 and 3, which are important for epidermal adhesion. The mechanism of autoantibody-induced cell dissociation (acantholysis) in pemphigus, however, is still not fully understood. For the first time, it is shown by AFM force spectroscopy that pemphigus autoantibodies directly inhibit Dsg3 adhesion by steric hindrance but do not inhibit adhesion of Dsg1. However, the full pathogenicity of the autoantibodies depended on cellular signaling processes, since autoantibodies targeting Dsg1 also resulted in loss of cadherin-mediated adhesion in cell-based experiments. However, two other signaling pathways that have been reported to be involved in pemphigus pathogenesis, i.e. epidermal growth factor receptor (EGFR) and c-Src activation, were not found to be important in this context. Furthermore, peptide-based modulators of cadherin functions were generated for Dsg1/3 and VE-cadherin. By comparing Dsg1, Dsg3 and VE-cadherin sequences to published X-ray structures of cadherin trans-interactions, specific amino acid sequences of the binding pockets of these cadherins were identified. Peptide versions of these motifs were synthesized and the antagonistic functions of these "single peptides" were validated by AFM force spectroscopy as well as by cell-based assays. By linking two single peptides in tandem, stabilization of cadherin bonds because of by cross-bridge formation between trans-interacting cadherins was demonstrated. Protective effects of tandem peptides were shown by partly preventing pemphigus autoantibody-induced acantholysis, or in the case of VE-cadherin, by stabilizing endothelial barrier properties against barrier disrupting agents like the Ca2+ ionophore A23187 and an inhibitory VE-cadherin antibody. Most importantly, VE-cadherin tandem peptides abolished microvascular hyperpermeability induced by the physiologic inflammatory agent tumor necrosis factor-α in the rat mesentery in vivo. Both classes of tandem peptides therefore can be considered as a starting point for the generation of potential therapeutic agents that might prevent cell dissociation in pemphigus and breakdown of the endothelial barrier under inflammatory conditions.}, subject = {Cadherine}, language = {en} } @phdthesis{Leonhardt2010, author = {Leonhardt, Sara Diana}, title = {Resin collection and use in stingless bees}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51588}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Harz ist ein klebriges Pflanzenprodukt mit einem oft intensiven aromatischen Geruch. Es wird von B{\"a}umen produziert, um Wunden zu verschließen und sch{\"a}dliche Besucher abzuwehren. Einige Insektenarten haben jedoch die erstaunliche F{\"a}higkeit entwickelt, mit der klebrigen Substanz umzugehen und sie sich gar zu Nutzen zu machen. So verwenden Bienen Harz beispielsweise zum Nestbau und zur Verteidigung ihrer Kolonien. W{\"a}hrend allgemein bekannt ist, dass Bienen Pollen und Nektar sammeln, wird der Tatsache, dass sie auch Harz sammlen, allerdings sehr viel weniger Beachtung geschenkt. Ziel meiner Dissertation war es daher, herauszufinden, warum, wie und wo stachellose Bienen in Borneo (sieben untersuchte Bienenarten), Australien (acht Arten) und Costa Rica (27 Arten) Pflanzenharze sammeln und verwerten. Diese Arbeit behandelt somit die enge Beziehung zwischen einer eusozialen Insektengattung und einem chemisch und physiologisch hoch komplexen Pflanzenprodukt, das Bienen nicht nur als Nestmaterial und zur Verteidigung dient, sondern auch eine wesentliche Bedeutung f{\"u}r deren chemische Diversit{\"a}t hat. Stachellose Bienen verhalten sich hochgradig opportunistisch, wenn sie Harz sammeln, d.h. verschiedene Bienenarten sammeln Harz von denselben Baumarten, wobei sie nahezu jede verf{\"u}gbare Harzquelle nutzen. Dabei finden und erkennen sie Harzquellen anhand einiger charakteristischer Mono- und Sesquiterpene, nutzen jedoch nicht das gesamte Harz-Bouquet. Die Menge an eingetragenem Harz unterscheidet sich zwischen verschiedenen Bienenarten und kolonien und varriert mit verschiedenen Umweltbedingungen. Insbesondere eine Bedrohung durch Fressfeinde (z. B. Ameisen) f{\"u}hrt zu einer massiven Steigerung des Harzeintrages; eine manuelle Zerst{\"o}rung des Nesteinganges hat dagegen relativ wenig Einfluss. Das eingetragene Harz wird zum Nestbau und zur Verteidigung gegen Fressfeinde und Mikroben genutzt. Dar{\"u}ber hinaus dient es als Quelle f{\"u}r Terpene, die von den Bienen in ihre chemischen Oberfl{\"a}chenprofile eingebaut werden (kutikul{\"a}re Terpene). Dabei {\"u}bertragen sie nur einen Bruchteil (8 \%) der gewaltigen Menge (>> 1000) an Terpenen, die man im Harz von B{\"a}umen findet, auf ihre Oberfl{\"a}che. Die {\"u}bertragenen Terpene bleiben in ihrer Struktur unver{\"a}ndert, allerdings unterscheiden sich die Bienenarten in der Zusammensetzung der Terpenprofile auf ihrer Oberfl{\"a}che, obwohl alle untersuchten Arten Harz von denselben B{\"a}umen sammeln. Die unterschiedlichen Terpenprofile sowie die Tatsache, dass nur wenige Terpene aus dem Harz aufgenommen werden, deuten auf einen artspezifischen und bisher unbekannten Filterungsmechanismus bei stachellosen Bienen hin. Auch {\"u}bersteigt durch die Aufnahme von Terpenen die chemische Diversit{\"a}t der Oberfl{\"a}chenprofile von stachellosen Bienen die zahlreicher anderer Hymenopteren. Da Bienen die Terpene aus dem Harz nur „filtern", sie dabei aber nicht ver{\"a}ndern, sind s{\"a}mtliche Bienenarten aus Borneo, Australien und Costa den charakteristischen Harzprofilen von B{\"a}umen aus ihren Ursprungsgebieten chemisch sehr {\"a}hnlich. Da in jeder tropischen Region andere Baumarten vorkommen, varriert die chemische Zusammensetzung der vorkommenden Harze und damit der kutikul{\"a}ren Terpene von dort vorkommenden Bienen. Die meisten Bienenarten mit kutikul{\"a}ren Terpenen findet man in Borneo, wo nahezu 100 \% der untersuchten Arten aus Baumharzen gewonnene Terpene in ihre chemischen Profilen einbauen. Im Gegensatz dazu sind es in Costa Rica nur 40 \% der untersuchten Arten. Auch sammeln in Borneo gelegentlich 9 von 10 Arbeiterinnen einer Tetragonilla collina Kolonie Harz, wohingegen in Australien maximal 10 \% und in Costa Rica maximal 40 \% der Arbeiterinnen einer Kolonie Harz sammeln. Das Vorherrschen von Harz und aus Harz gewonnenen Terpenen in der chemischen {\"O}kologie von Bienen auf Borneo spiegelt das Vorherrschen einer bestimmten s{\"u}dostasiatischen Baumfamilie wieder: der Dipterocarpaceen, deren Holz ungew{\"o}hnlich harzig ist. Ein solch enger Zusammenhang zwischen der Chemie von Bienen und der von Baumharzen verdeutlicht die enge Beziehung zwischen stachellosen Bienen und den B{\"a}umen in ihrem Habitat. Die kutikul{\"a}ren Terpene sch{\"u}tzen ihre Tr{\"a}ger vor Angreifern (z.B. Ameisen) und Mikrobenbefall. Dabei variiert eine bestimmte Gruppe - Sesquiterpene - am meisten zwischen den Arten. Diese Terpengruppe manipuliert die nat{\"u}rlichweise auftretende zwischen-artliche Aggression, indem sie letztere bei jenen Arten verringert, die selbst keine Sesquiterpene in ihrem Profil haben. Aggressionsminderung durch chemische Komponenten, welche aus der Umwelt aufgenommen werden, stellt somit einen bisher unbekannten Mechanismus dar, um Toleranz zwischen sonst aggressiven Arten zu erreichen. Eine derarte Herabsetzung von aggressiven Verhalten bei stachellosen Bienen kann dar{\"u}ber hinaus ein entscheidender Faktor f{\"u}r das Entstehen sogenannter Nestaggregationen sein. Dabei nisten Kolonien von Bienenarten mit und Bienenarten ohne Sesquiterpene in ihrem chemischen Profil in unmittelbarer Nachbarschaft, ohne gegeneinander aggressiv zu sein. Im Hinblick auf die zahlreichen Funktionen, die Harze und/oder aus dem Harz gewonnene Substanzen f{\"u}r stachellose Bienen haben, stellt Harz zweifelsohne eine bedeutende Ressource in der Welt der Bienen dar - eine Ressource, die einen direkten Einfluss auf deren chemische {\"O}kologie, Verteidigungsmechanismen und zwischen-artliche Kommunikation aus{\"u}bt. Wie genau die Bienen ihre artspezifischen Terpenprofile erzeugen, insbesondere, wie es ihnen gelingt, dabei ganze Terpengruppen auszuschließen, muss in zuk{\"u}nftigen Studien genauer untersucht werden. Auch stellt sich die Frage, wie wichtig eine hohe Diversit{\"a}t an Harzquellen und damit Baumarten f{\"u}r die Bienen ist! Es ist durchaus m{\"o}glich, dass neben einer Vielfalt an Bl{\"u}tenpflanzenarten auch der „Harzreichtum" f{\"u}r das Wohlergehen der Bienen eine entscheidende Rolle spielt.}, subject = {stachellose Biene}, language = {en} } @phdthesis{KordtsFreudinger2010, author = {Kordts-Freudinger, Robert}, title = {Relief: Approach Behavior and Avoidance Goals}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55366}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The thesis deals with the question which motivation direction—approach or avoidance—is connected to the emotion relief—a positive, low-arousal emotion, which is caused by an expected or nonexpected, motive-consistent change for the better, thus caused by the absence of an aversive stimulus. Based on the idea of postulating different levels of approach avoidance motivation, the Reflective-Impulsive Model of Behavior (RIM, Strack \& Deutsch, 2004) is applied to relief and approach avoidance. The RIM differentiates between an impulsive and a reflective system of information processing, with both systems working in relative independence from each other. Two central variables moderate the relation between relief and approach avoidance. The first is the psychological system in which approach avoidance is processed and assessed. Two levels of approach avoidance are distinguished: an impulsive distance orientation (distance change in relation to specific stimuli) and a reflective goal orientation (attainment of positive versus avoidance of negative end states). The second is the psychological system in which relief developed: In the impulsive system, relief develops as the affect that is conditioned to the absence of negative states; in the reflective system, relief develops as a result of goal-oriented behaviour of controlling or preventing of negative stimulation. The thesis looks at both moderators (level of approach avoidance and psychological system of development of relief) at once. The central prediction for the impulsive distance orientation is: Relief leads to an approach distance orientation (distance reduction), independent from the system in which relief develops. The central prediction for the reflective goal orientation is: Relief leads to an avoidance goal orientation (control of negative end states). This latter prediction is only made for the case when relief was caused by (develops in) the reflective system, that is by one's own, goal-directed behaviour; it is further necessary for an avoidance goal orientation that the relief state cannot certainly reached, instead there always has to uncertainty in the control of negative states. The methodology in the thesis is based on studies of aversive conditioning. In most studies, a differentiation paradigm is applied. The impulsive relief is operationalized via a classically conditioned relief (aversive CS-), whereas the reflective relief is operationalized via an active avoidance paradigm which ensures the methodological comparability of "reflective relief" to "impulsive relief". The predictions are as follows: Prediction A: Relief will elicit positive affective valence and an approach distance orientation. This should be true for both relief that is caused by the impulsive system and for relief that is caused by the reflective system (Experiments 2-3). Prediction B: More positive valence of relief—caused by a larger change of affective states—will elicit a stronger approach distance orientation (Experiment 4). Prediction C: Relief caused by the impulsive system will not elicit a specific goal orientation (Experiment 5). Prediction D: Uncertain self-induced relief—caused by the reflective system—will elicit an avoidance goal orientation (Experiments 6-7). In addition, Experiment 1 validated the conditioning paradigm used for the elicitation of relief. The experiments in the thesis support all predictions made in the theoretical part. The work has implications for the assumptions made in the RIM (Strack \& Deutsch, 2004). In the impulsive system, the affective valence determines approach avoidance orientation (e.g., R. Neumann \& Strack, 2000), the reflective goal not playing an important role. Relief elicits an approach orientation in the impulsive system. In the reflective system, the active goal is decisive for the approach avoidance orientation. Uncertain self-caused relief elicits an avoidance goal orientation in the reflective system. The studies of the thesis thus support and validate the assumptions made in the RIM (Strack \& Deutsch, 2004) in the specific field of motivational direction.}, subject = {Motivation}, language = {en} } @phdthesis{Attaran2010, author = {Attaran, Elham}, title = {Regulation of pathogen-inducible volatile compounds in Arabidopsis and their role in plant defense}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-46715}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Plants are constantly attacked by pathogenic microbes. As a result, they have evolved a plethora of constitutive and inducible defense responses to defend against attempted pathogen infection. Although volatile organic compounds have been implicated in plant defense, direct evidence of their function in plant resistance is still lacking. I have examined the role of VOCs in Arabidopsis defense against the hemibiotrophic bacterial pathogen Pseudomonas syringae pv. maculicola. The obtained results show that the vegetative parts of Arabidopsis produces and emits the volatile phenylpropanoid MeSA and three kinds of terpenoids, (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT), alpha-ionon and beta-farnesen, upon avirulent and virulent P. syringae inoculation. Whereas the most abundant volatiles, MeSA and TMTT, are already produced at early stages of infection in the compatible and incompatible interaction, enhanced emission of alpha-ionon and beta-farnesen can only be detected in later stages of the compatible interaction. It was revealed that pathogen-induced synthesis of TMTT in Arabidopsis requires the JA signaling pathway but occurs independently of SA defense signaling. Similarly, the production of MeSA is dependent on JA signaling but not on the SA defense signaling pathway. Furthermore, production of MeSA is dependent on the function of ISOCHORISMATE SYNTHASE1, which produces its precursor SA. Upon inoculation with avirulent P. syringae, endogenously produced JA activates the JA signalling pathway to mediate MeSA and TMTT synthesis. By contrast, in the compatible Arabidopsis-Psm interaction, production of MeSA predominantly depends on the P. syringea the virulence factor coronatine, which activates JA downstream signaling. To learn more about the role of inducible VOCs in plant defense responses, I have identified an Arabidopsis T-DNA insertions line with a defect in the TERPENE SYNTHASE4 (TPS4) gene. Emission profiles from this mutant revealed that the induced production of TMTT but not of alpha-ionone, beta-farnesene or MeSA are abolished, demonstrating that TPS4 specifically regulates the P. syringae-induced synthesis of TMTT in Arabidopsis. The lack of TMTT in tps4 mutants, however, does not affect plant defense responses and resistance induction against P. syringae. This excludes a role of the terpenoid as an effective phytoalexin in Arabidopsis leaves against the bacterial pathogen. Moreover, tps4 mutant plants are still able to mount a SAR response, excluding a signaling function of TMTT during SAR. An important aim of our studies was to address the defensive role of MeSA, the major VOC emitted from P. syringae-inoculated Arabidopsis leaves. MeSA has been recently proposed as a critical long distance signal in the development of SAR. I found that two independent T-DNA insertions lines with defects in expression of the pathogen-inducible SA methyl transferase gene BSMT1 are completely devoid of pathogen-induced production of MeSA. However, bsmt1 mutant plants are capable to increase the level of SA in systemic, non-infected leaves of Arabodopsis and develop SAR like wild-type plants upon local P. syringae-inoculation. Thus, MeSA does not function as a critical SAR signal in Arabidopsis. Further experiments showed that SA accumulation in distant leaves occurs due to de novo synthesis through isochorismate synthase. In addition, we also ruled out a critical defensive role of MeSA at inoculation sites, because bsmt1 mutants are able to build up SA-dependent defense responses and local resistance in a wild-type-like manner. The conversion of SA to MeSA and subsequently emission of MeSA from the plant might help the plant to detoxify an excess of SA. This process is regulated by the JA pathway and might be one means to mediate negative crosstalk between JA and SA signaling. Moreover, the COR-triggered conversion of SA to MeSA and emission of the volatile methyl ester could be a way by which virulent P. syringae is able to attenuate the SA-defense pathway.}, subject = {Ackerschmalwand}, language = {en} } @phdthesis{Sienerth2010, author = {Sienerth, Arnold R.}, title = {Regulation of anti-inflammatory cytokine IL-10 by the Polycomb Group Protein Bmi1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49990}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Macrophages are important effector cells of the innate and adaptive immune response and exert a wide variety of immunological functions which necessitates a high level of plasticity on the chromatin level. In response to pathogen-associated molecular patterns (PAMPs) or inflammatory signals macrophages undergo a process of cellular activation which is associated with morphologic, functional and biochemical changes. Toll-like receptors (TLR) are able to sense many different PAMPs. TLR4 is an important sensor for lipopolysaccharide (LPS) which elicits a major portion of the host's inflammatory response through the activation of many different signaling pathways such as the NF-\&\#954;B and the MAPK protein kinase pathways RASRAF- MEK-ERK, p38 and JNK. Polycomb group (PcG) proteins are well known chromatin modifiers which function in large complexes and are required to maintain chromatin structure in a transcriptionally repressed state. It has previously been shown that the PcG protein Bmi1 is phosphorylated by 3pK, a downstream effector kinase of the MAPK protein kinase pathways RAS-RAF-MEK-ERK, p38 and JNK. In this work I analyzed the role of Bmi1 as a downstream effector of MAPK signaling during macrophage activation. Unexpectedly a rapid up-regulation on the Bmi1 protein level was observed in bone marrow derived macrophages (BMDMs) after LPS treatment. The Bmi1 induction was associated with transient protein phosphorylation that occured downstream of MAPK signaling. LPS treatment of BMDMs in the absence of Bmi1 resulted in a pronounced increase of IL-10 secretion. This secretion of the anti-inflammatory cytokine IL-10 was associated with increased IL-10 mRNA levels. Furthermore, siRNA mediated knock down of Bmi1 in J774A.1 macrophages also resulted in elevated IL-10 mRNA levels in response to LPS. ChIP analysis revealed that Bmi1 binds to throughout the il-10 locus. Alternative activation of wild type BMDMs via concomitant TLR4 and Fc\&\#947;R activation which triggers high IL-10 expression is paralleled by an attenuated Bmi1 protein expression. These results identify Bmi1 as a repressor of IL-10 expression during activation of macrophages.}, subject = {Interleukin 10}, language = {en} } @article{ParczykHeroldKlugetal.2010, author = {Parczyk, Marco and Herold, Volker and Klug, Gert and Bauer, Wolfgang R. and Rommel, Eberhard and Jakob, Peter M.}, title = {Regional in vivo transit time measurements of aortic pulse wave velocity in mice with high-field CMR at 17.6 Tesla}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68219}, year = {2010}, abstract = {Background: Transgenic mouse models are increasingly used to study the pathophysiology of human cardiovascular diseases. The aortic pulse wave velocity (PWV) is an indirect measure for vascular stiffness and a marker for cardiovascular risk. Results: This study presents a cardiovascular magnetic resonance (CMR) transit time (TT) method that allows the determination of the PWV in the descending murine aorta by analyzing blood flow waveforms. Systolic flow pulses were recorded with a temporal resolution of 1 ms applying phase velocity encoding. In a first step, the CMR method was validated by pressure waveform measurements on a pulsatile elastic vessel phantom. In a second step, the CMR method was applied to measure PWVs in a group of five eight-month-old apolipoprotein E deficient (ApoE(-/-)) mice and an age matched group of four C57Bl/6J mice. The ApoE(-/-) group had a higher mean PWV (PWV = 3.0 ± 0.6 m/s) than the C57Bl/6J group (PWV = 2.4 ± 0.4 m/s). The difference was statistically significant (p = 0.014). Conclusions: The findings of this study demonstrate that high field CMR is applicable to non-invasively determine and distinguish PWVs in the arterial system of healthy and diseased groups of mice.}, subject = {Medizin}, language = {en} } @unpublished{Nassourou2010, author = {Nassourou, Mohamadou}, title = {Reference Architecture, Design of Cascading Style Sheets Processing Model}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51328}, year = {2010}, abstract = {The technique of using Cascading Style Sheets (CSS) to format and present structured data is called CSS processing model. For instance a CSS processing model for XML documents describes steps involved in formatting and presenting XML documents on screens or papers. Many software applications such as browsers and XML editors have their own CSS processing models which are part of their rendering engines. For instance each browser based on its CSS processing model renders CSS layout differently, as a result an inconsistency in the support of CSS features arises. Some browsers support more CSS features than others, and the rendering itself varies. Moreover the W3C standards are not even adhered by some browsers such as Internet Explorer. Test suites and other hacks and filters cannot definitely solve these problems, because these solutions are temporary and fragile. To palliate this inconsistency and browser compatibility issues with respect to CSS, a reference CSS processing model is needed. By extension it could even allow interoperability across CSS rendering engines. A reference architecture would provide common software architecture and interfaces, and facilitate refactoring, reuse, and automated unit testing. In [2] a reference architecture for browsers has been proposed. However this reference architecture is a macro reference model which does not consider separately individual components of rendering and layout engines. In this paper an attempt to develop a reference architecture for CSS processing models is discussed. In addition the Vex editor [3] rendering and layout engines, as well as an extended version of the editor used in TextGrid project [5] are also presented in order to validate the proposed reference architecture.}, subject = {Cascading Style Sheets}, language = {en} } @article{FerranteWimmer2010, author = {Ferrante, Augusto and Wimmer, Harald K.}, title = {Reachability matrices and cyclic matrices}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68074}, year = {2010}, abstract = {We study reachability matrices R(A, b) = [b,Ab, . . . ,An-1b], where A is an n × n matrix over a field K and b is in Kn. We characterize those matrices that are reachability matrices for some pair (A, b). In the case of a cyclic matrix A and an n-vector of indeterminates x, we derive a factorization of the polynomial det(R(A, x)).}, subject = {Mathematik}, language = {en} } @phdthesis{MonzonCasanova2010, author = {Monz{\´o}n Casanova, Elisa}, title = {Rat iNKT Cells: Phenotype and Function}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56526}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {iNKT cells are a population of T cells with unique characteristics. In contrast to most αβ T cells which recognize peptides presented by highly polymorphic MHC molecules, iNKT cells are reactive to glycolipids presented by CD1d, a non-polymorphic MHC-I like molecule. Moreover, whereas MHC-restricted αβ T cells bear highly variable receptors (TCRs) formed after somatic recombination of the V(D)J gene segments, the TCR of iNKT cells is formed by an invariant α chain, which always contains the same gene segments: AV14 and AJ18; and a β chain of limited BV gene usage: BV8S2, BV7 or BV2, in the mouse. This invariant α chain is the reason for which these cells are named "i" and the NK part of their name refers to the expression of receptors typical of natural killer (NK) cells. iNKT cells recognize glycolipids of endogenous and microbial origin. After activation they secrete large amounts of very different cytokines such as IFN-γ and IL-4 and thus influence immune responses and pathological conditions. One of the most potent iNKT cell agonists, recognized by the semi-invariant TCR, is the synthetic glycolipid α-Galactosylceramide (α-Gal). iNKT cells can be visualized using CD1d-multimeric complexes loaded with α-Gal and flow cytometry, since this reagent has enough avidity to stain these cells. Interestingly, mouse iNKT cells can be stained with human α-Gal-loaded CD1d oligomers and human iNKT cells can also be visualized with mouse α-Gal-loaded CD1d oligomers, indicating a high degree of conservation of the recognition of α-Gal presented by CD1d through evolution. Previous studies showed that rats have the genes necessary to build semi-invariant TCRs: They have a CD1d homologue; one or two BV8S2 homologues and interestingly, up to ten AV14 gene segments, which are highly conserved when compared to the mouse genes. Importantly, it has been shown at least for two of these AV14 gene segments that they can produce invariant TCRα chains which, when coexpressed with BV8-containing β chains, react to α-Gal presented by rat CD1d. Furthermore, ex vivo stimulation of primary splenocytes with α-Gal results in the secretion of IL-4 and IFN-γ. Surprisingly, rat semi-invariant TCRs do not recognize α-Gal presented by mouse CD1d and accordingly, mouse α-Gal-loaded CD1d tetramers failed to stain a discrete population of rat iNKT cells. Taking all together, despite that strong evidence suggested that iNKT cells are present in the rat, the direct identification of such population and the analysis of CD1d-restricted immune responses were still pending for this species. Hence the work presented in this doctoral thesis was aimed to identify iNKT cells, to analyze their phenotype and also to study the distribution and function of CD1d in the rat. For these purposes, we produced essential reagents which were still lacking such as rat specific anti-CD1d monoclonal antibodies and rat CD1d oligomers. Importantly, two of three anti-rat CD1d monoclonal antibodies (all of them generated in our laboratory before this thesis was initiated) also recognized mouse CD1d and therefore allowed a direct comparison of CD1d expression between rat and mouse. Whereas CD1d distribution in the hematopoietic system was found to be extremely similar between these two species; in non-lymphatic tissues important differences were observed. Interestingly, CD1d protein was detected at not yet described sites such as the rat exocrine pancreas and rat and mouse Paneth cells. These monoclonal antibodies did not only allowed the analysis of CD1d expression, but also the first demonstration of the function of rat CD1d as an antigen presenting molecule, since cytokine release in response to α-Gal was blocked when they were added to ex vivo cultures of rat primary cells. Staining of primary rat iNKT cells (possible now with the newly generated rat CD1d oligomers) revealed interesting similarities with human iNKT cells. First, we observed that rat iNKT cells are only a minority among all NKR-P1A/B positive T cells. Human iNKT cells constitute also a very small proportion of NKR-P1A (CD161) expressing T cells, whereas in mice inbred strains which express NKR-P1C (NK1.1), most of NKRP1C expressing T cells are iNKT cells. Second, the majority of rat iNKT cells are either CD4 or DN and only a small proportion expresses CD8β. These findings are similar to humans and different to mice which lack CD8+ iNKT cells. Third, analysis of various inbred rat strains demonstrated different iNKT cell frequencies which correlated with cytokine secretion after α-Gal stimulation of primary cells. In comparison to mice, iNKT cell numbers are markedly reduced in rats. In F344 rats, inbred rat strain which released the highest cytokine amounts after α-Gal stimulation, approximately 0.25\% and 0.1\% of total liver and spleen lymphocytes, respectively, are iNKT cells. In contrast, in LEW rats iNKT cells were practically absent and neither IL-4 nor IFN-γ were detected after stimulation of primary cells with α-Gal. Once more, these frequencies are very close to those observed in humans. Last, as reported for human peripheral blood cells, rat iNKT cells could be easily expanded in vitro by adding α-Gal to cultures of intrahepatic lymphocytes, whereas the expansion of mouse iNKT cells was not possible using the same protocol. The presence of a multimember AV14 gene segment family in the rat is an intriguing characteristic. These AV14 gene segments are extremely homologous except in the CDR2α region. Based on the amino acid sequence of this region they have been divided into two different types: Type I and II. A specific tissue distribution of the different types was proposed in the first study where the presence of several AV14 gene segments was described. We also analyzed the AV14 gene segment usage in F344 and LEW inbred rat strains. In F344 rats we found no preferential usage of either AV14 gene segment type in the spleen and the liver but type II AV14 gene segments appeared more frequently in the thymus. In contrast, LEW rats show a preferential usage of type I AV14 gene segments in all three compartments analyzed: Thymus, spleen and liver. Taken all together, the usage of newly generated reagents allowed to gain novel insights into CD1d expression in the rat and in the mouse and to directly identify rat iNKT cells for the first time. The phenotypic and functional analysis of rat iNKT cells revealed numerous similarities with human iNKT cells. These are of special interest, since rats serve to investigate several pathological conditions including models for autoimmune diseases. The possibility now to analyze iNKT cells and CD1d-restricted T cell responses in the rat might help to understand the pathogenesis of such diseases. In addition, the uncomplicated in vitro expansion and culture of rat iNKT cells should facilitate the analysis of the immunomoldulatory capacities of these cells.}, subject = {Ratte}, language = {en} } @phdthesis{Lang2010, author = {Lang, Thomas C.}, title = {Quantum Monte Carlo methods and strongly correlated electrons on honeycomb structures}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53506}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In this thesis we apply recently developed, as well as sophisticated quantum Monte Carlo methods to numerically investigate models of strongly correlated electron systems on honeycomb structures. The latter are of particular interest owing to their unique properties when simulating electrons on them, like the relativistic dispersion, strong quantum fluctuations and their resistance against instabilities. This work covers several projects including the advancement of the weak-coupling continuous time quantum Monte Carlo and its application to zero temperature and phonons, quantum phase transitions of valence bond solids in spin-1/2 Heisenberg systems using projector quantum Monte Carlo in the valence bond basis, and the magnetic field induced transition to a canted antiferromagnet of the Hubbard model on the honeycomb lattice. The emphasis lies on two projects investigating the phase diagram of the SU(2) and the SU(N)-symmetric Hubbard model on the hexagonal lattice. At sufficiently low temperatures, condensed-matter systems tend to develop order. An exception are quantum spin-liquids, where fluctuations prevent a transition to an ordered state down to the lowest temperatures. Previously elusive in experimentally relevant microscopic two-dimensional models, we show by means of large-scale quantum Monte Carlo simulations of the SU(2) Hubbard model on the honeycomb lattice, that a quantum spin-liquid emerges between the state described by massless Dirac fermions and an antiferromagnetically ordered Mott insulator. This unexpected quantum-disordered state is found to be a short-range resonating valence bond liquid, akin to the one proposed for high temperature superconductors. Inspired by the rich phase diagrams of SU(N) models we study the SU(N)-symmetric Hubbard Heisenberg quantum antiferromagnet on the honeycomb lattice to investigate the reliability of 1/N corrections to large-N results by means of numerically exact QMC simulations. We study the melting of phases as correlations increase with decreasing N and determine whether the quantum spin liquid found in the SU(2) Hubbard model at intermediate coupling is a specific feature, or also exists in the unconstrained t-J model and higher symmetries.}, subject = {Monte-Carlo-Simulation}, language = {en} } @phdthesis{Vershenya2010, author = {Vershenya, Stanislav}, title = {Quantitative and qualitative analyses of in-paralogs}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51358}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In our analysis I was interested in the gene duplications, with focus on in-paralogs. In-paralogs are gene duplicates which arose after species split. Here I analysed the in-paralogs quantitatively, as well as qualitatively. For quantitative analysis genomes of 21 species were taken. Most of them have vastly different lifestyles with maximum evolutionary distance between them 1100 million years. Species included mammals, fish, insects and worm, plus some other chordates. All the species were pairwised analysed by the Inparanoid software, and in-paralogs matrix were built representing number of in-paralogs in all vs. all manner. Based on the in-paralogs matrix I tried to reconstruct the evolutionary tree using in-paralog numbers as evolutionary distance. If all 21 species were used the resulting tree was very far from real one: a lot of species were misplaced. However if the number was reduced to 12, all of the species were placed correctly with only difference being wrong insect and fish clusters switched. Then to in-paralogs matrix the neighbour-net algorithm was applied. The resulting "net" tree showed the species with fast or slow duplications rates compared to the others. We could identify species with very high or very low duplications frequencies and it correlates with known occurrences of the whole genome duplications. As the next step I built the graphs for every single species showing the correlation between their in-paralogs number and evolutionary distance. As we have 21 species, graph for every species is built using 20 points. Coordinates of the points are set using the evolutionary distance to that particular species and in-paralogs number. In mammals with increasing the distance from speciation the in-paralogs number also increased, however not in linear fashion. In fish and insects the graph close to zero is just the same in mammals' case. However, after reaching the evolutionary distances more than 800 million years the number of inparalogs is beginning to decrease. We also made a simulation of gene duplications for all 21 species and all the splits according to the fossil and molecular clock data from literature. In our simulation duplication frequency was minimal closer to the past and maximum in the near-present time. Resulting curves had the same shape the experimental data ones. In case of fish and insect for simulation the duplication rate coefficient even had to be set negative in order to repeat experimental curve shape. To the duplication rate coefficient in our simulation contribute 2 criteria: gene duplications and gene losses. As gene duplication is stochastical process it should always be a constant. So the changing in the coefficient should be solely explained by the increasing gene loss of old genes. The processes are explained by the evolution model with high gene duplication and loss ratio. The drop in number of in-paralogs is probably due to the BLAST algorithm. It is observed in comparing highly divergent species and BLAST cannot find the orthologs so precisely anymore. In the second part of my work I concentrated more on the specific function of inparalogs. Because such analysis is time-consuming it could be done on the limited number species. Here I used three insects: Drosophila melanogaster (fruit y), Anopheles gambiae (mosquito) and Apis mellifera (honeybee). After Inparnoid analyses and I listed the cluster of orthologs. Functional analyses of all listed genes were done using GO annotations and also KEGG PATHWAY database. We found, that the gene duplication pattern is unique for each species and that this uniqueness is rejected through the differences in functional classes of duplicated genes. The preferences for some classes reject the evolutionary trends of the last 350 million years and allow assumptions on the role of those genes duplications in the lifestyle of species. Furthermore, the observed gene duplications allowed me to find connections between genomic changes and their phenotypic manifestations. For example I found duplications within carbohydrate metabolism rejecting feed pattern adaptation, within photo- and olfactory-receptors indicating sensing adaptation and within troponin indicating adaptations in the development. Despite these species specific differences, found high correlations between the independently duplicated genes between the species. This might hint for a "pool" of genes preferentially duplicated. Taken together, the observed duplication patterns reject the adaptational process and provide us another link to the field of genomic zoology.}, subject = {Duplikation}, language = {en} } @misc{Gogolin2010, type = {Master Thesis}, author = {Gogolin, Christian}, title = {Pure State Quantum Statistical Mechanics}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-106065}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The capabilities of a new approach towards the foundations of Statistical Mechanics are explored. The approach is genuine quantum in the sense that statistical behavior is a consequence of objective quantum uncertainties due to entanglement and uncertainty relations. No additional randomness is added by hand and no assumptions about a priori probabilities are made, instead measure concentration results are used to justify the methods of Statistical Physics. The approach explains the applicability of the microcanonical and canonical ensemble and the tendency to equilibrate in a natural way. This work contains a pedagogical review of the existing literature and some new results. The most important of which are: i) A measure theoretic justification for the microcanonical ensemble. ii) Bounds on the subsystem equilibration time. iii) A proof that a generic weak interaction causes decoherence in the energy eigenbasis. iv) A proof of a quantum H-Theorem. v) New estimates of the average effective dimension for initial product states and states from the mean energy ensemble. vi) A proof that time and ensemble averages of observables are typically close to each other. vii) A bound on the fluctuations of the purity of a system coupled to a bath.}, subject = {Quantenstatistik}, language = {en} } @article{PinkertSchultzReichardt2010, author = {Pinkert, Stefan and Schultz, Joerg and Reichardt, Joerg}, title = {Protein Interaction Networks-More Than Mere Modules}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68426}, year = {2010}, abstract = {It is widely believed that the modular organization of cellular function is reflected in a modular structure of molecular networks. A common view is that a ''module'' in a network is a cohesively linked group of nodes, densely connected internally and sparsely interacting with the rest of the network. Many algorithms try to identify functional modules in protein-interaction networks (PIN) by searching for such cohesive groups of proteins. Here, we present an alternative approach independent of any prior definition of what actually constitutes a ''module''. In a self-consistent manner, proteins are grouped into ''functional roles'' if they interact in similar ways with other proteins according to their functional roles. Such grouping may well result in cohesive modules again, but only if the network structure actually supports this. We applied our method to the PIN from the Human Protein Reference Database (HPRD) and found that a representation of the network in terms of cohesive modules, at least on a global scale, does not optimally represent the network's structure because it focuses on finding independent groups of proteins. In contrast, a decomposition into functional roles is able to depict the structure much better as it also takes into account the interdependencies between roles and even allows groupings based on the absence of interactions between proteins in the same functional role. This, for example, is the case for transmembrane proteins, which could never be recognized as a cohesive group of nodes in a PIN. When mapping experimental methods onto the groups, we identified profound differences in the coverage suggesting that our method is able to capture experimental bias in the data, too. For example yeast-two-hybrid data were highly overrepresented in one particular group. Thus, there is more structure in protein-interaction networks than cohesive modules alone and we believe this finding can significantly improve automated function prediction algorithms.}, subject = {Netzwerk}, language = {en} } @article{SieversBilligGottschalketal.2010, author = {Sievers, Claudia and Billig, Gwendolyn and Gottschalk, Kathleen and Rudel, Thomas}, title = {Prohibitins Are Required for Cancer Cell Proliferation and Adhesion}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68548}, year = {2010}, abstract = {Prohibitin 1 (PHB1) is a highly conserved protein that together with its homologue prohibitin 2 (PHB2) mainly localizes to the inner mitochondrial membrane. Although it was originally identified by its ability to inhibit G1/S progression in human fibroblasts, its role as tumor suppressor is debated. To determine the function of prohibitins in maintaining cell homeostasis, we generated cancer cell lines expressing prohibitin-directed shRNAs. We show that prohibitin proteins are necessary for the proliferation of cancer cells. Down-regulation of prohibitin expression drastically reduced the rate of cell division. Furthermore, mitochondrial morphology was not affected, but loss of prohibitins did lead to the degradation of the fusion protein OPA1 and, in certain cancer cell lines, to a reduced capability to exhibit anchorage-independent growth. These cancer cells also exhibited reduced adhesion to the extracellular matrix. Taken together, these observations suggest prohibitins play a crucial role in adhesion processes in the cell and thereby sustaining cancer cell propagation and survival.}, subject = {Krebs }, language = {en} } @article{RothMauerObingeretal.2010, author = {Roth, Kristina and Mauer, Sonja and Obinger, Matthias and Ruf, Katharina C. and Graf, Christine and Kriemler, Susi and Lenz, Dorothea and Lehmacher, Walter and Hebestreit, Helge}, title = {Prevention through Activity in Kindergarten Trial (PAKT): A cluster randomised controlled trial to assess the effects of an activity intervention in preschool children}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67972}, year = {2010}, abstract = {Background: Physical activity and motor skills acquisition are of high importance for health-related prevention and a normal development in childhood. However, few intervention studies exist in preschool children focussing on an increase in physical activity and motor skills. Proof of positive effects is available but not consistent. Methods/Design: The design, curriculum, and evaluation strategy of a cluster randomised intervention study in preschool children are described in this manuscript. In the Prevention through Activity in Kindergarten Trial (PAKT), 41 of 131 kindergartens of Wuerzburg and Kitzingen, Germany, were randomised into an intervention and a control group by a random number table stratified for the location of the kindergarten in an urban (more than 20.000 inhabitants) or rural area. The aims of the intervention were to increase physical activity and motor skills in the participating children, and to reduce health risk factors as well as media use. The intervention was designed to involve children, parents and teachers, and lasted one academic year. It contained daily 30-min sessions of physical education in kindergarten based on a holistic pedagogic approach termed the "early psychomotor education". The sessions were instructed by kindergarten teachers under regular supervision by the research team. Parents were actively involved by physical activity homework cards. The kindergarten teachers were trained in workshops and during the supervision. Assessments were performed at baseline, 3-5 months into the intervention, at the end of the intervention and 2-4 months after the intervention. The primary outcomes of the study are increases in physical activity (accelerometry) and in motor skills performance (composite score of obstacle course, standing long jump, balancing on one foot, jumping sidewise to and fro) between baseline and the two assessments during the intervention. Secondary outcomes include decreases in body adiposity (BMI, skin folds), media use (questionnaire), blood pressure, number of accidents and infections (questionnaire), increases in specific motor skills (throwing, balancing, complex motor performance, jumping) and in flexibility. Discussion: If this trial proofs the effectiveness of the multilevel kindergarten based physical activity intervention on preschooler's activity levels and motor skills, the programme will be distributed nationwide in Germany. Trial Registration: ClinicalTrials.gov Identifier: NCT00623844}, subject = {Vorschulkind}, language = {en} } @article{KleinschnitzGrundWingleretal.2010, author = {Kleinschnitz, Christoph and Grund, Henrike and Wingler, Kirstin and Armitage, Melanie E. and Jones, Emma and Mittal, Manish and Barit, David and Schwarz, Tobias and Geis, Christian and Kraft, Peter and Barthel, Konstanze and Schuhmann, Michael K. and Herrmann, Alexander M. and Meuth, Sven G. and Stoll, Guido and Meurer, Sabine and Schrewe, Anja and Becker, Lore and Gailus-Durner, Valerie and Fuchs, Helmut and Klopstock, Thomas and de Angelis, Martin Hrabe and Jandeleit-Dahm, Karin and Shah, Ajay M. and Weissmann, Norbert and Schmidt, Harald H. H. W.}, title = {Post-Stroke Inhibition of Induced NADPH Oxidase Type 4 Prevents Oxidative Stress and Neurodegeneration}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68416}, year = {2010}, abstract = {Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90\% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox42/2) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox42/2 mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.}, subject = {Schlaganfall}, language = {en} } @phdthesis{BarcenaUribarri2010, author = {Barcena Uribarri, Ivan}, title = {Porins in the genus Borrelia : Characterization of P66 and P13}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55339}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Die Gattung Borrelia geh{\"o}rt zur Familie der Spirochaetes, welche sich den Gram-negativen Bakterien zuordnen lassen. F{\"u}r diese Familie charakteristisch ist eine l{\"a}ngliche, helikale Form, die L{\"a}ngen von 5 - 250 µm erreichen kann. Den Spirochaeten geh{\"o}ren diverse Pathogene an wie Treponema und Leptospira, die Erreger der Syphillis und der Leptospirose. Borrelien verursachen beim Menschen zwei schwere Krankheiten: Die Lyme-Borreliose (LB) und das R{\"u}ckfallfieber (RF). Als Pathogen besitzen Borrelien einen Lebenszyclus, in dem sie zwischen Gliederf{\"u}ßern als Vektoren und S{\"a}ugetieren (oft kleinen Nagetieren) als Wirt wechseln. Um das {\"U}berleben in derart unterschiedlichen Organismen zu sichern und die Immunantwort des Wirtes zu unterdr{\"u}cken, ben{\"o}tigt ein Organismus mit einem solch komplexen Lebenszyklus eine außergew{\"o}hnliche Regulierung der Proteinexpression. Die Lyme-Borelliose stellt eine multisystemische Krankheit dar, die verschiedene Organe, wie Haut, Gelenke und das Nervensystem betreffen kann. H{\"a}ufig kommt es zu einer sich kreisf{\"o}rmig ausbreitenden R{\"o}tung, die erythema migrans genannt wird, die zur klinischen Diagnose genutzt wird. Sie erscheint nach einem Zeckenbiss und kann einen Durchmesser von bis zu 15 cm weit erreichen. R{\"u}ckfallfieber erkennt man an pl{\"o}tzlich auftretenden Fiebersch{\"u}ben, die von weiteren Symptomen wie Sch{\"u}ttelfrost, Kopfschmerzen, Muskel und Gelenkschmerzen oder {\"U}belkeit begleitet werden. Beide Krankheiten k{\"o}nnen in fr{\"u}hen Stadien der Infektion leicht mit der Gabe von Antibiotika behandelt werden. Die verschiedenen Arten der Gattung Borrelia besitzen ein relativ kleines Genom. Da außerdem viele der vorhandenen Gene f{\"u}r Virulenzfaktoren und wirtsspezifische Anpassungen codieren, fehlen den Borrelien wichtige Genen f{\"u}r die Biosynthese von Aminos{\"a}uren, Fetts{\"a}uren oder Nukleotiden. Diese metabolischen Defizite werden durch die Aufnahme von durch den Wirt produzierten N{\"a}hrstoffen ausgeglichen. Den ersten Schritt der N{\"a}hrstoffaufnahme {\"u}bernehmen Porine. Dies sind wassergef{\"u}llte Kan{\"a}le, die die Aufnahme und den Transport von essentiellen Molek{\"u}len {\"u}ber die {\"a}ußere Membran erm{\"o}glichen. P66, P13 und Oms28 wurden bei Borrelia burgdorferi, Oms38 bei R{\"u}ckfallfieber verursachenden Spirochaeten gefunden. P66 ist ein einzelnes Porin mit einer extrem hohen Leitf{\"a}higkeit von 11 nS. P13 ist ein kleines Protein (13kDa) mit einer α helikalen Sekund{\"a}rstruktur, die keinerlei {\"A}hnlichkeit zu den bisherigen Modellen von bekannten Porinen aufweist. Aufgrund seiner Assoziation mit der periplasmatischen Seite der Membran wurde die Funktion als Porin f{\"u}r Oms28 in letzter Zeit stark angezweifelt. Oms38 ist ein Dicarboxylat-spezifisches Porin mit Homologen bei Lyme-Borreliose verursachenden Arten. Das Ziel der vorliegenden Arbeit war das vorhandene Wissen {\"u}ber P66 und P13 als Porine der Gattung Borrelia zu erweitern. Die beiden Proteine unterscheiden sich strukturell stark von den bisher bekannten Porine Gram-negativer Bakterien und sind daher geeignete Forschungsobjekte, um die speziellen Anforderungen an Borrelienporinen zu erforschen. Das Ziel dieser Arbeit war die Erforschung der beiden in Borrelien beschriebenen Proteine P66 und P13. Gerade weil sich beide in Aufbau und Gr{\"o}ße von bekannten Porinen Gram-negativer Bakterien unterscheiden und somit in spezifische Prozesse bei der Gattung Borrelia involviert sein k{\"o}nnten, ist die Forschung auf diesem Gebiet auch weiterhin von h{\"o}chstem Interesse. Im ersten Projekt dieser Arbeit wurden das Vorkommen und die porenformende Aktivit{\"a}t von P66 in verschiedenen Borrelia-Arten (Lyme-Borreliose und R{\"u}ckfallfieber) untersucht. Bei P66 handelt es sich um das am besten untersuchte Porin der Borrelien, das eine Doppelfunktion als Porin und als Adhesin besitzt. Da sich alle bisherigen Ergebnisse auf B. burgdorferi beziehen, ist wenig bis gar nichts {\"u}ber homologe Proteine in anderen Borrelien-Arten bekannt. Deswegen wurden jeweils drei Arten, die Lyme-Borreliose und R{\"u}ckfallfieber verursachen, ausgew{\"a}hlt und an deren P66-Homologe die porenformende Aktivit{\"a}t {\"u}berpr{\"u}ft. F{\"u}nf von sechs zeigten dabei eine {\"a}hnliche Einzelkanalleitf{\"a}higkeit wie P66, die im Bereich von 9 - 11 nS lagen, bei gleichzeitig kaum vorhandener Selektivit{\"a}t f{\"u}r eine bestimmte Ionensorte. Auch eine Spannungsabh{\"a}ngigkeit, die bei 30 - 70 mV begann, war messbar. Nur im Fall von B. hermsii konnten keine Poren gefunden werden. Dabei ist noch nicht gekl{\"a}rt, ob das Fehlen der porenbildenden Aktivit{\"a}t einem evolution{\"a}ren Verlust der Funktion als Pore oder einer h{\"o}heren Anf{\"a}lligkeit gegen{\"u}ber den verwendeten Detergenzien geschuldet ist. In einem weiteren Projekt wurde der kontrovers diskutierte Porendurchmesser von P66 aus B.burgdorferi mit empirischen Mitteln analysiert. In fr{\"u}heren theoretischen Studien wurde der Kanaldurchmesser auf 2,6 nm gesch{\"a}tzt. Dieser sehr große Durchmesser w{\"u}rde allerdings die Schutzfunktion der Außenmembran verhindern. Mit Hilfe von ungeladenen Substanzen gelang eine Bestimmung des Innendurchmessers von P66 auf 1,8 nm am Eingang und 0,8 nm an der Engstelle der Pore. Zus{\"a}tzlich f{\"u}hrte eine unerwartete Blockierung der Pore durch einige dieser Substanzen zu der Erkenntnis, dass P66 einen oligomeren (wahrscheinlich oktameren) Aufbau besitzt. Ein solcher Aufbau konnte bisher noch nie nachgewiesen werden und k{\"o}nnte von daher ein einzigartiges Merkmal von Borrelien oder Spirochaeten sein. Das dritte Projekt besch{\"a}ftigte sich mit der rekombinanten Produktion eines Proteins von B. burgdorferi mit immunogenen Eigenschaften. Dieses k{\"o}nnte dazu verwendet werden, neue Diagnose Tests und Therapien zu entwickeln. P13 kommt in verschiedenen LB- und RF-Arten vor und besitzt kein bekanntes bakterielles Homolog. Diese Fakten machen aus P13 einen geeigneten Kandidaten als therapeutisches Ziel. Aus diesem Grund wurde das P13-Gen in zwei unterschiedliche Organismen kloniert. Zum einen in E. coli, wo zwei verschiedene Konstrukte zur Kl{\"a}rung der Rolle des periplasmatisch verdauten C-Terminus dienen sollten. Zum anderen in Tabakpflanzen {\"u}ber Agrobacterium tumefaciens, mittels eines Virus. Dabei vermehrt sich der Vektor in den Zellen der Pflanze, breitet sich aus und produziert gleichzeitig das gew{\"u}nschte Protein. Mit Hilfe dieser zweiten Expressionsmethode sollte es m{\"o}glich sein, große Mengen des rekombinanten Proteins zu erzeugen und gleichzeitig die Kosten und den Zeitbedarf zu senken. Das letzte Projekt besch{\"a}ftigte sich mit dem Außenmembran-Komplexom von B. burgdorferi und konzentrierte sich dabei auf die Komplexe von P13 und P66. Blue Native PAGE und 2D-SDS PAGE wurden als Techniken ausgew{\"a}hlt. Es konnte gezeigt werden, dass P66 das einzige Protein ist, das am vermutlich oktameren Aufbau der 11 nS Pore beteiligt ist. Zus{\"a}tzlich gelang es, den Komplex in zwei H{\"a}lften zu spalten, die ungef{\"a}hr das halbe Molekulargewicht bei einer Leif{\"a}higkeit von 5,5 nS zeigten. Im Fall des P13-Komplexes konnte eine m{\"o}gliche Verkn{\"u}pfung mit OspC entdeckt werden. Die Gelelution des Komplexes und anschließende Tests mit Hilfe der Black-Lipid-Bilayer-Methode ergaben eine Aktivit{\"a}t von 0,6 nS. Dies steht im starken Gegensatz zu der vorher f{\"u}r P13beschriebenen Gr{\"o}ße von 3,5 nS. Zusammenfassend l{\"a}sst sich sagen, dass P66 ein in vielen Borrelienarten vorkommendes und damit weit verbreitetes Porin mit Homologen in LB- und RF-Spezies ist, die {\"a}hnliche Charakteristika besitzen. Der Durchmesser dieser Pore konnte unter Ber{\"u}cksichtigung der Eigenschaften eines molekularen Siebes genauer bestimmt werden. Im Fall von P13 k{\"o}nnte dessen rekombinante Produktion es erlauben, dieses Protein als Hilfsmittel zur Diagnose und zur medizinischen Therapie einzusetzen. Zus{\"a}tzlich k{\"o}nnte der gefundene Bezug zu OspC dazu beitragen, in Zukunft mehr {\"u}ber die Funktion dieses interessanten Proteins herauszufinden.}, subject = {Porins}, language = {en} } @phdthesis{EscalantePerez2010, author = {Escalante Perez, Maria}, title = {Poplar responses to biotic and abiotic stress}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-46893}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In this study poplar trees have been examined under different stress conditions. Apart from the detailed descriptions above two main conclusions might be drawn: i) A small plant like Arabidopsis thaliana is highly susceptible to stress situations that might become life-threatening compared to a tree that has extremely more biomass at its disposal. Such an organism might be able to compensate severe stress much longer than a smaller one. It seems therefore reasonable that a crop like Arabidopsis reacts earlier and faster to a massive threat. ii) In poplar both tested stress responses seemed to be regulated by hormones. The reactions to abiotic salt stress are mainly controlled by ABA, which also has a strong impact upon cold and drought stress situations. The term commonly used for ABA is "stress hormone" and is at least applicable to all abiotic stresses. In case of herbivory (biotic stress), jasmonic acid appears to be the key-player that coordinates the defence mechanism underlying extrafloral nectary and nectar production. Thus the presented work has gained a few more insights into the complex network of general stress induced processes of poplar trees. Future studies will help to understand the particular role of the intriguing indirect defence system of the extrafloral nectaries in more detail.}, subject = {abiotic stress}, language = {en} } @article{FreyHoubenBroecker2010, author = {Frey, Li­dia M. and Houben, Roland and Br{\"o}cker, Eva-B.}, title = {Pigmentation, Melanocyte Colonization, and p53 Status in Basal Cell Carcinoma}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68283}, year = {2010}, abstract = {Basal cell carcinoma (BCC) is the most common neoplasm in the Caucasian population. Only a fraction of BCC exhibits pigmentation. Lack of melanocyte colonization has been suggested to be due to p53-inactivating mutations in the BCC cells interfering with the p53-proopiomelanocortin pathway and the production of alpha melanocyte-stimulating hormone in the tumor. To evaluate this, we determined tumor pigmentation as well as expression of melan-A and of p53 in 49 BCC tissues bymeans of immunohistochemistry. As expected, we observed a positive relation between tumor pigmentation and melan-A positive intratumoral melanocytes.Melanocyte colonization and, to a lesser extent, p53 overexpression showed intraindividual heterogeneity in larger tumors. p53 overexpression, which is indicative of p53 mutations, was not correlated to melanocyte colonization of BCC. Sequencing of exon 5-8 of the p53 gene in selected BCC cases revealed that colonization by melanocytes and BCC pigmentation is neither ablated by p53 mutations nor generally present in BCCs with wild-type p53.}, subject = {Medizin}, language = {en} } @phdthesis{Nazeer2010, author = {Nazeer, Ahmed}, title = {Physiological and molecular basis of Azospirillum-Arabidopsis Interaction}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51673}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The present study was aimed at revealing the early signalling events during the interaction of the diazotrophic soil bacterium Azospirillum brasilense with its host plant Arabidopsis thaliana. Furthermore, taking advantage of the micro array technique, a comprehensive overview of Arabidopsis genes has been undertaken which are affected upon association with A. brasilense The characterization of the early responses of Arabidopsis plants upon inoculation with Azospirillum brasilense strain Sp7 clearly indicated parallels with the initial events in plant pathogen interaction. For instance, not only bacterial preprations (lysates) form Azospirillum elicited an apoplastic alkalinization of the culture medium, but also the live bacteria, which were even more effective. Besides, in a luminol based assay, the bacterial lysates triggered production of the reactive oxygen species (ROS) in the Arabidopsis leaf discs. Interestingly, the elongation factor receptor mutants (efr) were completely insensitive to Azospirillum, suggesting elongation factor Tu (EF-TU) recognition as elicitor by Arabidopsis. This hypothesis was further validated with a bioinformatic approach. The N terminus initial 26 amino acids from Azospirillum EF-TU gene (elf26) showed more similarity to the elf26 sequences of bacteria like Agrobacterium tumefaciens which elicit responses in the plants through EF-TU rather than Pseudomonas syringae where the potent elicitor is flagellin 22. Universal transcriptome profiling of Arabidopsis thaliana seedlings upon inoculation with Azospirillum brasilense over a time course of six, twenty four and ninty six hours revealed very little genetic responses in the early time points. However, a bulk of genes was differentially regulated in 96 hours post inoculation (96hpi). The nature of these genes indicated that the bacterial treatment, among others, greatly affect the processes like cell wall modification, hormone metabolism, stress and secondary metabolism. Additionally expression levels of a numer of transcription factors (TFs) related to basic helix loop helix (BHLH) and MYB domain containing TF families were altered with Azospirillum inoculation. Particularly the BHLH TFs were among the most highly regulated genes. The array results from Azospirillum treated plants were further compared with the already available data emnating from treatment with flagellin 22 (flg22), oligogalacturonides (OGs) and Agrobacterium tumefaciens. Noteworthy, very different set of genes were affected upon inoculation with Azospirillum in relation to other treatments. Secondly a cluster of proteins involved in the biosynthesis of aliphatic glucosinolates (GSL) were uniquely induced upon Sp7 exposure. Genes operating in flavonoid biosynthesis also showed a distinct regulation trend in the comparative analysis. Taken together, the study in question provides insights into the early signalling events in the context of Azospirillum-Arabidopsis association and the bacterial signals recognized by the plants. The array data, at the same time, elucidates the genetic factors of Arabidopsis triggered upon association with Azospirillum brasilense.}, subject = {Azospirillum brasilense}, language = {en} } @phdthesis{Gnadt2010, author = {Gnadt, Mirjam}, title = {Pharmacokinetic and pharmacodynamic characterization of inhaled β2 - agonists using the isolated human lung perfusion model}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53910}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The inhaled pharmacotherapy is fundamental in the management of obstructive lung diseases such as asthma bronchiale or chronic obstructive pulmonary disease. In this context short- and long-acting β2-agonists play a prominent role as relieve and control medication. Regarding the risk-benefit profile of an inhaled drug, the pattern of pulmonary deposition and the rate and extent of absorption into systemic circulation are essential parameters. New developments of drugs are characterized by high lung retention and improved efficacy. The aim of the present thesis was the parallel evaluation the pharmacokinetic (PK) and -dynamic (PD) properties of inhaled β2-agonists employing an isolated human lung perfusion model (IPL). The short-acting β2-agonist salbutamol and the newly developed ultra long-acting β2-agonist GW597901 were chosen for the analysis of pulmonary drug absorption and bronchodilation. In a pharmacokinetic enabling study an established human IPL setting was modified to monitor the pharmacokinetics of the β2-agonists by measuring the concentrations in perfusion fluid, lung tissue and BAL samples obtained during and after the experiments. The IPL model revealed differences in the pulmonary absorption behaviour of GW597901 and salbutamol. The lipophilic compound GW597901 was distributed to a lower extent into the perfusion fluid compared to the more hydrophilic compound salbutamol. The analyzed time profiles of nebulized salbutamol in the perfusate were consistent to with a clinical study if considering experimental conditions as the actual deposited doses and the differing volume of distribution. Thus, the suitability of the IPL model for the PK analysis of inhaled β2-agonists was confirmed. In a PK/PD study the human ex vivo model was employed for the first time for the evaluation of the clinical relevant bronchodilating effect induced by inhaled β2-agonists in addition to the analysis of their pharmacokinetics. Thereby the focus was to determine the onset and extent of bronchodilation. A new method was established to monitor changes in lung function parameters due to pharmacodynamic interventions over the duration of the experiment that allowed permanent online recording of the ventilation volume and lung mechanic parameters. Bronchial challenges with aerolised MCh were performed successfully in isolated ventilated human lung lobes, even though the responder rate was lower than expected despite high administered doses. The administration of the short acting agent salbutamol led to an immediate onset of action recognized as a sudden increase of the ventilation volumes. The bronchodilation following the application of GW597901 was observed delayed after about 6 min. Monitored lung function parameters considerably improved by both β2 - agonists in the IPL setting but not significantly different. Thus, in regard of the different applied doses GW597901 had a higher intrinsic activity and bronchodilating potency than salbutamol. The concentrations of salbutamol and GW597901 in the perfusate determined in the PK/PD study were significantly lower than those observed in the pharmacokinetic enabling study, while the tmax values and the course of the distribution profiles remained similar. Most likely, the application of nebulized MCh prior to the administration of the β2 - agonists had a substantial influence on their pharmacokinetic behaviour. It is yet not clear whether pharmacodynamic effects or molecular competition processes for the passage to the systemic circulation or both influenced the redistribution of the β2 - agonists as seen in the PK/PD study. The potential clinical relevance of this observation has to be further investigated. The development of pulmonary edema during the experiment was one limitation of the IPL model. For the determination of the onset of edema formation four potential biochemical markers, specifically surfactant-protein A (SP-A), angiotensin-converting enzyme (ACE), urea and lactate dehydrogenase, were measured in perfusion fluids. In this context, an ELISA method for the quantification of human SP-A in biological matrices was successfully established. The investigations showed that the concentrations of SP-A and ACE in the perfusate increased over time as a sign for lung tissue damage and correlated with the degree of edema formation. For the first time the IPL model was used for the evaluation of potential pulmonary edema marker and the results have shown that it is valuable tool for further investigations in this field. In conclusion, the pharmacokinetic and pharmacodynamic characterization of GW597901 and salbutamol was successfully achieved using the IPL model. This ex vivo methodology may contribute to further insights and understanding of the complex pharmacokinetic processes of inhaled β2 - agonists in the lung.}, subject = {Beta-2-Rezeptor}, language = {en} } @article{ZollnerRehnDietl2010, author = {Zollner, Ursula and Rehn, Monika and Dietl, Johannes}, title = {Perinatal Problems in Multiple Births Inconsistent Terminology}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85850}, year = {2010}, language = {en} } @phdthesis{Pries2010, author = {Pries, Jan Rastin}, title = {Performance Optimization of Wireless Infrastructure and Mesh Networks}, doi = {10.25972/OPUS-3723}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-46097}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Future broadband wireless networks should be able to support not only best effort traffic but also real-time traffic with strict Quality of Service (QoS) constraints. In addition, their available resources are scare and limit the number of users. To facilitate QoS guarantees and increase the maximum number of concurrent users, wireless networks require careful planning and optimization. In this monograph, we studied three aspects of performance optimization in wireless networks: resource optimization in WLAN infrastructure networks, quality of experience control in wireless mesh networks, and planning and optimization of wireless mesh networks. An adaptive resource management system is required to effectively utilize the limited resources on the air interface and to guarantee QoS for real-time applications. Thereby, both WLAN infrastructure and WLAN mesh networks have to be considered. An a-priori setting of the access parameters is not meaningful due to the contention-based medium access and the high dynamics of the system. Thus, a management system is required which dynamically adjusts the channel access parameters based on the network load. While this is sufficient for wireless infrastructure networks, interferences on neighboring paths and self-interferences have to be considered for wireless mesh networks. In addition, a careful channel allocation and route assignment is needed. Due to the large parameter space, standard optimization techniques fail for optimizing large wireless mesh networks. In this monograph, we reveal that biology-inspired optimization techniques, namely genetic algorithms, are well-suitable for the planning and optimization of wireless mesh networks. Although genetic algorithms generally do not always find the optimal solution, we show that with a good parameter set for the genetic algorithm, the overall throughput of the wireless mesh network can be significantly improved while still sharing the resources fairly among the users.}, subject = {IEEE 802.11}, language = {en} } @phdthesis{Klein2010, author = {Klein, Alexander}, title = {Performance Issues of MAC and Routing Protocols in Wireless Sensor Networks}, doi = {10.25972/OPUS-4465}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52870}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The focus of this work lies on the communication issues of Medium Access Control (MAC) and routing protocols in the context of WSNs. The communication challenges in these networks mainly result from high node density, low bandwidth, low energy constraints and the hardware limitations in terms of memory, computational power and sensing capabilities of low-power transceivers. For this reason, the structure of WSNs is always kept as simple as possible to minimize the impact of communication issues. Thus, the majority of WSNs apply a simple one hop star topology since multi-hop communication has high demands on the routing protocol since it increases the bandwidth requirements of the network. Moreover, medium access becomes a challenging problem due to the fact that low-power transceivers are very limited in their sensing capabilities. The first contribution is represented by the Backoff Preamble-based MAC Protocol with Sequential Contention Resolution (BPS-MAC) which is designed to overcome the limitations of low-power transceivers. Two communication issues, namely the Clear Channel Assessment (CCA) delay and the turnaround time, are directly addressed by the protocol. The CCA delay represents the period of time which is required by the transceiver to detect a busy radio channel while the turnaround time specifies the period of time which is required to switch between receive and transmit mode. Standard Carrier Sense Multiple Access (CSMA) protocols do not achieve high performance in terms of packet loss if the traffic is highly correlated due to the fact that the transceiver is not able to sense the medium during the switching phase. Therefore, a node may start to transmit data while another node is already transmitting since it has sensed an idle medium right before it started to switch its transceiver from receive to transmit mode. The BPS-MAC protocol uses a new sequential preamble-based medium access strategy which can be adapted to the hardware capabilities of the transceivers. The protocol achieves a very low packet loss rate even in wireless networks with high node density and event-driven traffic without the need of synchronization. This makes the protocol attractive to applications such as structural health monitoring, where event suppression is not an option. Moreover, acknowledgments or complex retransmission strategies become almost unnecessary since the sequential preamble-based contention resolution mechanism minimizes the collision probability. However, packets can still be lost as a consequence of interference or other issues which affect signal propagation. The second contribution consists of a new routing protocol which is able to quickly detect topology changes without generating a large amount of overhead. The key characteristics of the Statistic-Based Routing (SBR) protocol are high end-to-end reliability (in fixed and mobile networks), load balancing capabilities, a smooth continuous routing metric, quick adaptation to changing network conditions, low processing and memory requirements, low overhead, support of unidirectional links and simplicity. The protocol can establish routes in a hybrid or a proactive mode and uses an adaptive continuous routing metric which makes it very flexible in terms of scalability while maintaining stable routes. The hybrid mode is optimized for low-power WSNs since routes are only established on demand. The difference of the hybrid mode to reactive routing strategies is that routing messages are periodically transmitted to maintain already established routes. However, the protocol stops the transmission of routing messages if no data packets are transmitted for a certain time period in order to minimize the routing overhead and the energy consumption. The proactive mode is designed for high data rate networks which have less energy constraints. In this mode, the protocol periodically transmits routing messages to establish routes in a proactive way even in the absence of data traffic. Thus, nodes in the network can immediately transmit data since the route to the destination is already established in advance. In addition, a new delay-based routing message forwarding strategy is introduced. The forwarding strategy is part of SBR but can also be applied to many routing protocols in order to modify the established topology. The strategy can be used, e.g. in mobile networks, to decrease the packet loss by deferring routing messages with respect to the neighbor change rate. Thus, nodes with a stable neighborhood forward messages faster than nodes within a fast changing neighborhood. As a result, routes are established through nodes with correlated movement which results in fewer topology changes due to higher link durations.}, subject = {Routing}, language = {en} } @phdthesis{Henjes2010, author = {Henjes, Robert}, title = {Performance Evaluation of Publish/Subscribe Middleware Architectures}, doi = {10.25972/OPUS-4536}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53388}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {While developing modern applications, it is necessary to ensure an efficient and performant communication between different applications. In current environments, a middleware software is used, which supports the publish/subscribe communication pattern. Using this communication pattern, a publisher sends information encapsulated in messages to the middleware. A subscriber registers its interests at the middleware. The monograph describes three different steps to determine the performance of such a system. In a first step, the message throughput performance of a publish/subscribe in different scenarios is measured using a Java Message Service (JMS) based implementation. In the second step the maximum achievable message throughput is described by adapted models depending on the filter complexity and the replication grade. Using the model, the performance characteristics of a specific system in a given scenario can be determined. These numbers are used for the queuing model described in the third part of the thesis, which supports the dimensioning of a system in realistic scenarios. Additionally, we introduce a method to approximate an M/G/1 system numerically in an efficient way, which can be used for real time analysis to predict the expected performance in a certain scenario. Finally, the analytical model is used to investigate different possibilities to ensure the scalability of the maximum achievable message throughput of the overall system.}, subject = {Middleware}, language = {en} } @phdthesis{Oechsner2010, author = {Oechsner, Simon}, title = {Performance Challenges and Optimization Potential of Peer-to-Peer Overlay Technologies}, doi = {10.25972/OPUS-4159}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50015}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In today's Internet, building overlay structures to provide a service is becoming more and more common. This approach allows for the utilization of client resources, thus being more scalable than a client-server model in this respect. However, in these architectures the quality of the provided service depends on the clients and is therefore more complex to manage. Resource utilization, both at the clients themselves and in the underlying network, determine the efficiency of the overlay application. Here, a trade-off exists between the resource providers and the end users that can be tuned via overlay mechanisms. Thus, resource management and traffic management is always quality-of-service management as well. In this monograph, the three currently significant and most widely used overlay types in the Internet are considered. These overlays are implemented in popular applications which only recently have gained importance. Thus, these overlay networks still face real-world technical challenges which are of high practical relevance. We identify the specific issues for each of the considered overlays, and show how their optimization affects the trade-offs between resource efficiency and service quality. Thus, we supply new insights and system knowledge that is not provided by previous work.}, subject = {Overlay-Netz}, language = {en} } @article{ConradFritschZeidleretal.2010, author = {Conrad, Christopher and Fritsch, Sebastian and Zeidler, Julian and R{\"u}cker, Gerd and Dech, Stefan}, title = {Per-Field Irrigated Crop Classification in Arid Central Asia Using SPOT and ASTER Data}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68630}, year = {2010}, abstract = {The overarching goal of this research was to explore accurate methods of mapping irrigated crops, where digital cadastre information is unavailable: (a) Boundary separation by object-oriented image segmentation using very high spatial resolution (2.5-5 m) data was followed by (b) identification of crops and crop rotations by means of phenology, tasselled cap, and rule-based classification using high resolution (15-30 m) bi-temporal data. The extensive irrigated cotton production system of the Khorezm province in Uzbekistan, Central Asia, was selected as a study region. Image segmentation was carried out on pan-sharpened SPOT data. Varying combinations of segmentation parameters (shape, compactness, and color) were tested for optimized boundary separation. The resulting geometry was validated against polygons digitized from the data and cadastre maps, analysing similarity (size, shape) and congruence. The parameters shape and compactness were decisive for segmentation accuracy. Differences between crop phenologies were analyzed at field level using bi-temporal ASTER data. A rule set based on the tasselled cap indices greenness and brightness allowed for classifying crop rotations of cotton, winter-wheat and rice, resulting in an overall accuracy of 80 \%. The proposed field-based crop classification method can be an important tool for use in water demand estimations, crop yield simulations, or economic models in agricultural systems similar to Khorezm.}, subject = {Geologie}, language = {en} } @phdthesis{Brandes2010, author = {Brandes, Nicolas}, title = {Oxidative Thiol Modifications in Pro- and Eukaryotic Organisms}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-46542}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Cystein spielt eine wichtige Rolle in der Biochemie vieler Proteine. Aufgrund der Redox-Eigenschaften und der hohen Reaktivit{\"a}t der freien Thiol-Gruppe sowie dessen F{\"a}higkeit Metallionen zu koordinieren, ist Cystein oft Bestandteil von katalytischen Zentren vieler Enzyme. Zudem lassen sich Cysteine durch reaktive Sauerstoff- und Stickstoffspezies leicht reversibel oxidativ modifizieren. In den letzten Jahren wurde gezeigt, dass Proteine redox-bedingte Thiol-Modifikationen nutzen, um Ver{\"a}nderungen ihrer Aktivit{\"a}t zu steuern. Diese redox-regulierten Proteine spielen eine zentrale Rolle in vielen physiologischen Prozessen. Das erste Ziel meiner Arbeit war die Identifizierung von Stickstoffmonoxid (NO)-sensitiven Proteinen in E. coli. Die redox-bedingten Funktions{\"a}nderungen solcher Proteine erkl{\"a}ren m{\"o}glicherweise die ver{\"a}nderte Physiologie von E. coli Zellen, die unter NO-Stress leiden. Um E. coli Proteine zu identifizieren, die unter Einwirkung von NO-Stress reversibel Thiol-modifiziert werden, wandte ich eine Kombination aus differentiellem Thiol-Trapping und 2D Gel-Elektrophorese an. Es wurden zehn Proteinen identifiziert, welche NO-sensitive Thiol-Gruppen enthalten. Genetische Studien ergaben, dass Modifikationen an AceF \& IlvC mitverantwortlich sind f{\"u}r die NO-induzierte Wachstumshemmung. Bemerkenswert ist es, dass die Mehrheit der identifizierten Proteine speziell nur gegen reaktive Stickstoffspezies empfindlich ist, welches an einem der identifizierten Stickstoffmonoxid-sensitiven Proteinen, der kleinen Untereinheit von Glutamate synthase, getestet wurde. In vivo und in vitro Aktivit{\"a}tsstudien zeigten, dass es zu einer schnellen Inaktivierung von Glutamate synthase nach NO-Behandlung kommt, das Protein aber resistent gegen{\"u}ber anderen Oxidationsmittel ist. Diese Resultate implizieren, dass reaktive Sauerstoff- und Stickstoffspezies unterschiedliche physiologische Vorg{\"a}nge in Bakterien beeinflussen. Das zweite Ziel meiner Arbeit war es, redox-sensitive Proteine in S. cerevisiae zu identifizieren und deren Redox-Zustand als in vivo Read-Out zu verwenden, um die Rolle von oxidativen Stress w{\"a}hrend des Alterungsprozess eukaryotischer Zellen zu analysieren. Zun{\"a}chst bestimmte ich in Hefezellen mit Hilfe von OxICAT, einer hochsensiblen quantitativen Methode, die Thiol-Trapping mit Massenspektrometrie verbindet, den exakten in vivo Thiol-Status von fast 300 Proteinen. Diese Proteine lassen sich in vier Gruppen einteilen: 1) Proteine, deren Cysteinreste resistent gegen Oxidation sind; 2) Proteine, in denen Cysteinmodifikationen strukturelle Aufgaben {\"u}bernehmen; 3) Proteine mit oxidationsempfindlichen Cysteinen, die bereits eine gewisse Oxidation in exponentiell wachsenden Hefezellen aufweisen; 4) Proteine, die reduziert sind, aber redox-sensitive Cysteinreste enthalten, die die Funktion der Proteine bei Vorhandensein von oxidativen Stress beeinflussen. Die Sensitivit{\"a}t dieser Proteine gegen{\"u}ber oxidativen Stress wurde durch Exposition subletaler Konzentrationen von H2O2 oder Superoxid auf Hefezellen nachgewiesen. Es wurde gezeigt, dass die wichtigsten zellul{\"a}ren Angriffspunkte von H2O2- und Superoxid-bedingtem Stress Proteine sind, die an Vorg{\"a}ngen der Translation, Glykolyse, des Citratzyklus und der Aminos{\"a}ure-Biosynthese beteiligt sind. Diese Zielproteine zeigen, dass Zellen f{\"u}r die Bek{\"a}mpfung von oxidativen Stress Metabolite schnell in Richtung des Pentosephosphatweges umleiten, um die Produktion des Reduktionsmittels NADPH sicherzustellen. Die hier pr{\"a}sentierten Ergebnisse belegen, dass die quantitative Bestimmung des Oxidationsstatus von Proteinen eine wertvolle Methode ist, um redox-sensitive Cysteinreste zu identifizieren. Die OxICAT Technologie wurde dann verwendet, um das genaue Ausmaß und die Entstehung von oxidativen Stress in chronologisch alternden S. cerevisiae Zellen zu bestimmen. F{\"u}r diese Bestimmung wurde der Oxidationsstatus von Proteinen in alternden Hefezellen als physiologischer Read-Out verwendet. Ich zeigte, dass die zellul{\"a}re Redox-Hom{\"o}ostase in chronologisch alternden Hefezellen global zusammenbricht, wobei es sich dabei um einen Prozess handelt, der dem Zelltod vorausgeht. Der Beginn dieses Zusammenbruchs scheint mit der Lebensdauer der Hefezellen zu korrelieren, da Kalorienrestriktion die Lebensdauer der Hefezellen erh{\"o}ht und den Zusammenbruch des Redox-Gleichgewichts verz{\"o}gert. Die Oxidation einer kleinen Anzahl an Proteinen (z.B. Thioredoxin reductase) geht dem Redox-Zusammenbruch deutlich voraus, was maßgeblich zum Verlust der Redox-Hom{\"o}ostase beitragen k{\"o}nnte. Diese Studien an alternden Hefezellen erweitern unser Verst{\"a}ndnis, wie sich Ver{\"a}nderungen in der Redox-Hom{\"o}ostase auf die Lebensdauer von Hefezellen auswirken. Zudem best{\"a}tigen die hier pr{\"a}sentierten Ergebnisse die Bedeutung von oxidativen Thiol-Modifikationen als eine der wichtigsten posttranslationalen Proteinmodifikationen in pro-und eukaryotischen Organismen}, subject = {Oxidativer Stress}, language = {en} } @phdthesis{Queisser2010, author = {Queisser, Nina}, title = {Oxidative and nitrosative stress induced by the mineralocorticoid aldosterone - Mechanism of induction and role of signal transduction pathways and transcription factors}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53566}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Several epidemiological studies found that hypertensive patients have an increased risk to develop kidney cancer. Hyperaldosteronism frequently results in arterial hypertension and contributes to the development and progression of kidney injury, with reactive oxygen species (ROS) playing an important role. ROS are thought to be associated with many pathological conditions such as cancer and other disorders, like cardiovascular complications , which often go along with hypertension. The aim of the present work was to investigate whether the effects of elevated aldosterone concentrations might be involved in the increased cancer incidence of hypertensive individuals. First, the potential capacity of aldosterone to induce oxidative stress and DNA damage was investigated in vitro and in vivo. In LLC-PK1 porcine kidney cells and MDCK canine kidney cells the significant formation of ROS, and especially of superoxide (O2˙ˉ) was assessed. With two genotoxicity tests, the comet assay and the micronucleus frequency test, the DNA damaging potential of aldosterone was quantified. In both genotoxicity tests a dose-dependent increase in aldosterone-induced structural DNA damage was observed. Oxidative stress and DNA damage were prevented by antioxidants, suggesting ROS as a major cause of DNA damage. Furthermore, the oxidatively modified DNA lesion 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG), was found to be significantly elevated. In kidneys of rats with desoxycorticosterone acetate (DOCA)/salt-induced hypertension, which is a model of severe mineralocorticoid-dependent hypertension, elevated levels of ROS and superoxide were found, compared to kidneys of sham rats. Also DNA strand breaks, measured with the comet assay and double strand breaks, visualized with antibodies against the double strand break-marker gamma-H2AX were significantly elevated in kidneys of DOCA/salt-treated rats. In addition, significantly increased amounts of 8-oxodG were detected. Proliferation of kidney cells was found to be increased, which theoretically enables the DNA damage to manifest itself as mutations, since the cells divide. Second, the effects of aldosterone on the activation of transcription factors and signaling pathways were investigated. A significant activation of the potentially protective transcription factor Nrf2 was observed in LLC-PK1 cells. This activation was triggered by an increase of ROS or reactive nitrogen species (RNS). In response to oxidative stress, glutathione synthesis and detoxifying enzymes, such as the subunits of the glutathione-cysteine-ligase or heme oxygenase 1 were rapidly induced after 4 h. Nevertheless, after 24 h a decrease of glutathione levels was observed. Since ROS levels were still high after 24 h, but Nrf2 activation decreased, this adaptive survival response seems to be transient and quickly saturated and overwhelmed by ROS/RNS. Furthermore, Nrf2 activation was not sufficient to protect cells against oxidative DNA damage, because the amounts of double strand breaks and 8-oxodG lesions steadily rose up to 48 h of aldosterone treatment. The second transcription factor that was time- and dose-dependently activated by aldosterone in LLC-PK1 and MDCK cells was NF-kappaB. Furthermore, a significant cytosolic and nuclear activation of ERK was detected. Aldosterone induced the phosphorylation of the transcription factors CREB, STAT1 and STAT3 through ERK. Third, the underlying mechanisms of oxidant production, DNA damage and activation of transcription factors and signaling pathways were studied. Aldosterone exclusively acted via the MR, which was proven by the MR antagonists eplerenone, spironolactone and BR-4628, whereas the glucocorticoid receptor (GR) antagonist mifepristone did not show any effect. Furthermore, aldosterone needed cytosolic calcium to exert its negative effects. Calcium from intracellular stores and the influx of calcium across the plasma membrane was involved in aldosterone signaling. The calcium signal activated on the one hand, the prooxidant enzyme complex NAD(P)H oxidase through PKC, which subsequently caused the generation of O2˙ˉ. On the other hand, nitric oxide synthase (NOS) was activated, which in turn produced NO. NO and O2˙ˉ can react to the highly reactive species ONOO- that can damage the DNA more severely than the less reactive O2˙ˉ. In the short term, the activation of transcription factors and signaling pathways could be a protective response against aldosterone-induced oxidative stress and DNA damage. However, a long-term NF-B and ERK/CREB/STAT activation by persistently high aldosterone levels could unfold the prosurvival activity of NF-kappaB and ERK/CREB/STAT in aldosterone-exposed cells. DNA damage caused by increased ROS might become persistent and could be inherited to daughter cells, probably initiating carcinogenesis. If these events also occur in patients with hyperaldosteronism, these results suggest that aldosterone could be involved in the increased cancer incidence of hypertensive individuals.}, subject = {Aldosteron}, language = {en} } @article{PhamHelluyBraeuningeretal.2010, author = {Pham, Mirko and Helluy, X. and Braeuninger, S. and Jakob, P. and Stoll, G. and Kleinschnitz, Christoph and Bendszus, M.}, title = {Outcome of experimental stroke in C57Bl/6 and Sv/129 mice assessed by multimodal ultra-high field MRI}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68115}, year = {2010}, abstract = {Transgenic mice bred on C57Bl/6 or Sv/129 genetic background are frequently used in stroke research. It is well established that variations in cerebrovascular anatomy and hemodynamics can influence stroke outcome in different inbred mouse lines. We compared stroke development in C57Bl/6 and Sv/129 mice in the widely used model of transient middle cerebral artery occlusion (tMCAO) by multimodal ultra-high field magnetic resonance imaging (MRI). C57Bl/6 and Sv/129 mice underwent 60 min of tMCAO and were analyzed by MRI 2 h and 24 h afterwards. Structural and functional images were registered to a standard anatomical template. Probability maps of infarction were rendered by automated segmentation from quantitative T2-relaxometric images. Whole-brain segmentation of infarction was accomplished manually on high-resolution T2-weighted (T2-w) RARE images. Cerebral perfusion (cerebral blood flow, CBF) was measured quantitatively by modified continuous arterial-spin-labeling (CASL) and apparent diffusion coefficients (ADC) by spin-echo diffusion-weighted imaging (DWI). Probabilities of cortical (95.1\% ± 3.1 vs. 92.1\% ± 2.5; p > 0.05) and subcortical (100\% vs. 100\%; p > 0.05) infarctions at 24 h were similar in both groups as was the whole-brain volumetric extent of cerebral infarction. In addition, CBF and ADC values did not differ between C57Bl/6 and Sv/129 mice at any time point or region of interest. The C57Bl/6 and Sv/129 genetic background is no major confounding factor of infarct size and cerebral perfusion in the tMCAO model.}, subject = {NMR-Tomographie}, language = {en} } @phdthesis{Nuwal2010, author = {Nuwal, Nidhi}, title = {Optogenetic investigation of nervous system functions using walking behavior and genome wide transcript analysis of Synapsin and Sap47 mutants of Drosophila}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51694}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {PART I Animals need to constantly evaluate their external environment in order to survive. In some cases the internal state of the animal changes to cope with it's surrounding. In our study we wanted to investigate the role of amines in modulating internal states of Drosophila. We have designed a behavioral paradigm where the flies are fixed in space but can walk on a small styrofoam ball suspended by a gentle stream of air. The walking activity of flies was used as behavioral readout. PART I Animals need to constantly evaluate their external environment in order to survive. In some cases the internal state of the animal changes to cope with it's surrounding. In our study we wanted to investigate the role of amines in modulating internal states of Drosophila. We have designed a behavioral paradigm where the flies are fixed in space but can walk on a small styrofoam ball suspended by a gentle stream of air. The walking activity of flies was used as behavioral readout. An operant training paradigm was established by coupling one of the walking directions to incidence of heat punishment. We observed that animals quickly realized the contingency of punishment with walking direction and avoided walking in the punished direction in the presence of punishment, but did not continue walking in the unpunished direction in the absence of the punishment. This would indicate that the flies do not form a memory for the punished direction or rapidly erase it under new conditions. On having established the paradigm with heat punishment we have attempted to activate selected subsets of neuronal populations of Drosophila while they were walking on the ball. The selective activation of neurons was achieved by expressing the light-activated ion channel channelrhodopsin-2 (ChR2) using the Gal4-UAS system and coupling the unidirectional walking of the animals on the ball with the incidence of blue light required to activate the channels and depolarize the neurons. The feasibility of this approach was tested by light-activating sugar sensitive gustatory receptor neurons expressing ChR2, we found that when the light was actuated the flies preferred to turn in one direction the optically "rewarded" direction. Next we similarly activated different subsets of aminergic neurons. We observed that in our setup animals avoided to turn in the direction which was coupled to activation of dopaminergic neurons indicating that release of dopamine is disliked by the animals. This is in accordance with associative learning experiments where dopamine is believed to underlie the formation of an association between a neutral conditioned stimulus with the aversive unconditioned stimulus. However, when we activated tyraminergic/octopaminergic neurons we did not observe any directional preference. The activation of dopaminergic and tyraminergic/octopaminergic neurons led to arousal of the animals indicating that we were indeed successful in activating those neurons. Also, the activation of serotonergic neurons did not have any effect on directional preference of the animals. With this newly established paradigm it will be interesting to find out if in insects like in mammals a reward mediating system exists and to test subsets of aminergic or peptidergic neurons that could possibly be involved in a reward signaling system which has not been detected in our study. Also, it would be interesting to localize neuropile regions that would be involved in mediating choice behavior in our paradigm. PART II In collaboration with S. Kneitz (IZKF Wuerzburg) and T. Nuwal we performed genome-wide expression analysis of two pre-synaptic mutants - Synapsin (Syn97) and Synapse associated protein of 47 kDa (Sap47156). The rationale behind these experiments was to identify genes that were up- or down-regulated due to these mutations. The microarray experiments provided us with several candidate genes some of which we have verified by qPCR. From our qPCR analysis we can conclude that out of the verified genes only Cirl transcripts seem to be reproducibly down regulated in Synapsin mutants. The Cirl gene codes for a calcium independent receptor for latrotoxin. Further qPCR experiments need to be performed to verify other candidate genes. The molecular interactions between CIRL and SYN or their genes should now be investigated in detail.}, subject = {Taufliege}, language = {en} } @phdthesis{Margapoti2010, author = {Margapoti, Emanuela}, title = {Optical properties of thermally annealed CdZnSe/ZnSe quantum dots}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52946}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {see: pdf-file}, subject = {Physik}, language = {en} } @phdthesis{Worschech2010, author = {Worschech, Andrea}, title = {Oncolytic Therapy with Vaccinia Virus GLV-1h68 - Comparative Microarray Analysis of Infected Xenografts and Human Tumor Cell Lines -}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-45338}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Aim of this thesis was to study the contribution of the hosts immune system during tumor regression. A wild-type rejection model was studied in which tumor regression is mediated through an adaptive, T cell host response (Research article 1). Additionally, the relationship between VACV infection and cancer rejection was assessed by applying organism-specific microarray platforms to infected and non-infected xenografts. It could be shown that tumor rejection in this nude mouse model was orchestrated solely by the hosts innate immune system without help of the adaptive immunity. In a third study the inflammatory baseline status of 75 human cancer cell lines was tested in vitro which was correlated with the susceptibility to VACV and Adenovirus 5 (Ad5) replication of the respective cell line (Manuscript for Research article 3). Although xenografts by themselves lack the ability to signal danger and do not provide sufficient proinflammatory signals to induce acute inflammation, the presence of viral replication in the oncolytic xenograft model provides the "tissue-specific trigger" that activates the immune response and in concordance with the hypothesis, the ICR is activated when chronic inflammation is switched into an acute one. Thus, in conditions in which a switch from a chronic to an acute inflammatory process can be induced by other factors like the immune-stimulation induced by the presence of a virus in the target tissue, adaptive immune responses may not be necessary and immune-mediated rejection can occur without the assistance of T or B cells. However, in the regression study using neu expressing MMC in absence of a stimulus such as a virus and infected cancer cells thereafter, adaptive immunity is needed to provoke the switch into an acute inflammation and initiate tissue rejection. Taken together, this work is supportive of the hypothesis that the mechanisms prompting TSD differ among immune pathologies but the effect phase converges and central molecules can be detected over and over every time TSD occurs. It could be shown that in presence of a trigger such as infection with VACV and functional danger signaling pathways of the infected tumor cells, innate immunity is sufficient to orchestrate rejection of manifested tumors.}, subject = {Tumorimmunologie}, language = {en} } @phdthesis{CardosoBarato2010, author = {Cardoso Barato, Andre}, title = {Nonequilibrium phase transitions and surface growth}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50122}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {This thesis is concerned with the statistical physics of various systems far from thermal equilibrium, focusing on universal critical properties, scaling laws and the role of fluctuations. To this end we study several models which serve as paradigmatic examples, such as surface growth and non-equilibrium wetting as well as phase transitions into absorbing states. As a particular interesting example of a model with a non-conventional scaling behavior, we study a simplified model for pulsed laser deposition by rate equations and Monte Carlo simulations. We consider a set of equations, where islands are assumed to be point-like, as well as an improved one that takes the size of the islands into account. The first set of equations is solved exactly but its predictive power is restricted to the first few pulses. The improved set of equations is integrated numerically, is in excellent agreement with simulations, and fully accounts for the crossover from continuous to pulsed deposition. Moreover, we analyze the scaling of the nucleation density and show numerical results indicating that a previously observed logarithmic scaling does not apply. In order to understand the impact of boundaries on critical phenomena, we introduce particle models displaying a boundary-induced absorbing state phase transition. These are one-dimensional systems consisting of a single site (the boundary) where creation and annihilation of particles occur, while particles move diffusively in the bulk. We study different versions of these models and confirm that, except for one exactly solvable bosonic variant exhibiting a discontinuous transition with trivial exponents, all the others display a non-trivial behavior, with critical exponents differing from their mean-field values, representing a universality class. We show that these systems are related to a \$(0+1)\$-dimensional non-Markovian model, meaning that in nonequilibrium a phase transition can take place even in zero dimensions, if time long-range interactions are considered. We argue that these models constitute the simplest universality class of phase transition into an absorbing state, because the transition is induced by the dynamics of a single site. Moreover, this universality class has a simple field theory, corresponding to a zero dimensional limit of direct percolation with L{\'e}vy flights in time. Another boundary phenomena occurs if a nonequilibrium growing interface is exposed to a substrate, in this case a nonequilibrium wetting transition may take place. This transition can be studied through Langevin equations or discrete growth models. In the first case, the Kardar-Parisi-Zhang equation, which defines a very robust universality class for nonequilibrium moving interfaces, is combined with a soft-wall potential. While in the second, microscopic models, in the corresponding universality class, with evaporation and deposition of particles in the presence of hard-wall are studied. Equilibrium wetting is related to a particular case of the problem, corresponding to the Edwards-Wilkinson equation with a potential in the continuum approach or to the fulfillment of detailed balance in the microscopic models. In this thesis we present the analytical and numerical methods used to investigate the problem and the very rich behavior that is observed with them. The entropy production for a Markov process with a nonequilibrium stationary state is expected to give a quantitative measure of the distance form equilibrium. In the final chapter of this thesis, we consider a Kardar-Parisi-Zhang interface and investigate how entropy production varies with the interface velocity and its dependence on the interface slope, which are quantities that characterize how far the stationary state of the interface is away from equilibrium. We obtain results in agreement with the idea that the entropy production gives a measure of the distance from equilibrium. Moreover we use the same model to study fluctuation relations. The fluctuation relation is a symmetry in the large deviation function associated to the probability of the variation of entropy during a fixed time interval. We argue that the entropy and height are similar quantities within the model we consider and we calculate the Legendre transform of the large deviation function associated to the height for small systems. We observe that there is no fluctuation relation for the height, nevertheless its large deviation function is still symmetric.}, subject = {Nichtgleichgewichtsstatistik}, language = {en} } @phdthesis{Sonder2010, author = {Sonder, Ingo}, title = {Non-Newtonian Properties of Magmatic Melts}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49762}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {This work presents a new method to measure model independent viscosities of inhomogeneous materials at high temperatures. Many mechanisms driving volcanic eruptions are strongly influenced by the viscous properties of the participating materials. Since an eruption takes place at temperatures at which these materials (predominantly silicate melts) are not completely molten, typically inhomogeneities, like e.g. equilibrium and non-equilibrium crystals, are present in the system. In order to incorporate such inhomogeneities into objective material parameters the viscosity measurement is based on a rotational viscometer in a wide gap Couette setup. The gap size between the two concentric cylinders was designed as large as possible in order to account for the inhomogeneities. The emerging difficulties concerning the model independent data reduction from measured values to viscosities are solved using an appropriate interpolation scheme. The method was applied to a material representative for the majority of volcanic eruptions on earth: a typical continental basaltic rock (Billstein/Rh{\"o}n/Germany). The measured viscosities show a strong shear rate dependency, which surprises, because basaltic melt has been, until now, assumed to behave as a Newtonian fluid. Since a non-Newtonian material shows a very different relaxation behavior in the Couette motion compared to a Newtonian one (which, ultimately, does not show any), and a strong relaxation signal was recorded during viscosity measurements, the equations of Couette motion were investigated. The time dependent stress distribution in a material due to a quasi step-like velocity change at the inner Couette radius (i.e. the spindle) was considered. The results show that a material combining a linear shear modulus and a Newtonian viscosity -- a Maxwell material -- cannot quantify the relaxation behavior. This could be considered as a hint, that the widely used Maxwell relaxation times cannot be applied as a 1:1 mapping from microscopic considerations to macroscopic situations.}, subject = {Viskosit{\"a}t}, language = {en} } @phdthesis{Hartmann2010, author = {Hartmann, Thomas}, title = {Nitrogen metabolism in Aspergillus fumigatus with emphasis on the oligopeptide transporter (OPT) gene family}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-54027}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The saprophytic filamentous fungus Aspergillus fumigatus has been gaining importance as an opportunistic human pathogen over the past decades. Advances in modern medicine have created a growing group of patients susceptible to infection with A. fumigatus, often contracting potentially deadly invasive aspergillosis. The virulence of this pathogen appears to be a multifactorial trait, a combination of physiological characteristics that enables the fungus to infect immunocompromised humans. This work concentrates on the nitrogen metabolism of A. fumigatus, which is essential for meeting the nutritional needs inside the human host. Using DNA microarrays, the transcriptional response during growth on three different secondary nitrogen sources was examined, which revealed the metabolic versatility of A. fumigatus, especially when challenged with proteins as the sole source of nitrogen. In-depth transcriptional profiling of the eight-member oligopeptide transporter (OPT) gene family underlined the importance of oligopeptide transport for growth on complex nitrogen sources like BSA or collagen. Heterologous expression of the opt genes in Saccharomyces cerevisiae showed their functionality as oligopeptide transporters, and characterized their substrate specificity. Using a Cre/loxP based genetic tool, a complete deletion of all opt genes in A. fumigatus was achieved. The resultant strain exhibited diminished growth on medium where the oligopeptide GPGG was the sole nitrogen source, but did not show any other in vitro phenotype. The opt deletion strain was not attenuated in virulence in a murine model of pulmonary aspergillosis, suggesting that the OPT gene family is not necessary for successful infection. The connection of oligopeptide transport and extracellular proteolytic activity was investigated by deleting the genes encoding Dpp4 and Dpp5, two dipeptidyl peptidases, or PrtT, the transcriptional regulator of major secreted proteases, in the complete opt deletion background. In contrast to the deletion of dpp4 and dpp5, which did not result in any additional phenotype, the absence of prtT led to a drastic growth defect on porcine lung agar. This suggests a synergistic action of extracellular proteolytic digest of proteins and transport of oligopeptide degradation products into the cell. Finally, this work established the bacterial β-Rec/six site-specific recombination system as a novel genetic tool for targeted gene deletion in A. fumigatus.}, subject = {Aspergillus fumigatus}, language = {en} } @article{ChenBoettgerReifetal.2010, author = {Chen, Yong and Boettger, Michael K. and Reif, Andreas and Schmitt, Angelika and Ueceyler, Nurcan and Sommer, Claudia}, title = {Nitric oxide synthase modulates CFA-induced thermal hyperalgesia through cytokine regulation in mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68349}, year = {2010}, abstract = {Background: Although it has been largely demonstrated that nitric oxide synthase (NOS), a key enzyme for nitric oxide (NO) production, modulates inflammatory pain, the molecular mechanisms underlying these effects remain to be clarified. Here we asked whether cytokines, which have well-described roles in inflammatory pain, are downstream targets of NO in inflammatory pain and which of the isoforms of NOS are involved in this process. Results: Intraperitoneal (i.p.) pretreatment with 7-nitroindazole sodium salt (7-NINA, a selective neuronal NOS inhibitor), aminoguanidine hydrochloride (AG, a selective inducible NOS inhibitor), L-N(G)-nitroarginine methyl ester (L-NAME, a non-selective NOS inhibitor), but not L-N(5)-(1-iminoethyl)-ornithine (L-NIO, a selective endothelial NOS inhibitor), significantly attenuated thermal hyperalgesia induced by intraplantar (i.pl.) injection of complete Freund's adjuvant (CFA). Real-time reverse transcription-polymerase chain reaction (RT-PCR) revealed a significant increase of nNOS, iNOS, and eNOS gene expression, as well as tumor necrosis factor-alpha (TNF), interleukin-1 beta (IL-1b), and interleukin-10 (IL-10) gene expression in plantar skin, following CFA. Pretreatment with the NOS inhibitors prevented the CFA-induced increase of the pro-inflammatory cytokines TNF and IL-1b. The increase of the antiinflammatory cytokine IL-10 was augmented in mice pretreated with 7-NINA or L-NAME, but reduced in mice receiving AG or L-NIO. NNOS-, iNOS- or eNOS-knockout (KO) mice had lower gene expression of TNF, IL-1b, and IL-10 following CFA, overall corroborating the inhibitor data. Conclusion: These findings lead us to propose that inhibition of NOS modulates inflammatory thermal hyperalgesia by regulating cytokine expression.}, subject = {Medizin}, language = {en} } @phdthesis{Brandstaetter2010, author = {Brandstaetter, Andreas Simon}, title = {Neuronal correlates of nestmate recognition in the carpenter ant, Camponotus floridanus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55963}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Cooperation is beneficial for social groups and is exemplified in its most sophisticated form in social insects. In particular, eusocial Hymenoptera, like ants and honey bees, exhibit a level of cooperation only rarely matched by other animals. To assure effective defense of group members, foes need to be recognized reliably. Ants use low-volatile, colony-specific profiles of cuticular hydrocarbons (colony odor) to discriminate colony members (nestmates) from foreign workers (non-nestmates). For colony recognition, it is assumed that multi-component colony odors are compared to a neuronal template, located in a so far unidentified part of the nervous system, where a mismatch results in aggression. Alternatively, a sensory filter in the periphery of the nervous system has been suggested to act as a template, causing specific anosmia to nestmate colony odor due to sensory adaptation and effectively blocking perception of nestmates. Colony odors are not stable, but change over time due to environmental influences. To adjust for this, the recognition system has to be constantly updated (template reformation). In this thesis, I provide evidence that template reformation can be induced artificially, by modifying the sensory experience of carpenter ants (Camponotus floridanus; Chapter 1). The results of the experiments showed that template reformation is a relatively slow process taking several hours and this contradicts the adaptation-based sensory filter hypothesis. This finding is supported by first in-vivo measurements describing the neuronal processes underlying template reformation (Chapter 5). Neurophysiological measurements were impeded at the beginning of this study by the lack of adequate technical means to present colony odors. In a behavioral assay, I showed that tactile interaction is not necessary for colony recognition, although colony odors are of very low volatility (Chapter 2). I developed a novel stimulation technique (dummy-delivered stimulation) and tested its suitability for neurophysiological experiments (Chapter 3). My experiments showed that dummy-delivered stimulation is especially advantageous for presentation of low-volatile odors. Colony odor concentration in headspace was further increased by moderately heating the dummies, and this allowed me to measure neuronal correlates of colony odors in the peripheral and the central nervous system using electroantennography and calcium imaging, respectively (Chapter 4). Nestmate and non-nestmate colony odor elicited strong neuronal responses in olfactory receptor neurons of the antenna and in the functional units of the first olfactory neuropile of the ant brain, the glomeruli of the antennal lobe (AL). My results show that ants are not anosmic to nestmate colony odor and this clearly invalidates the previously suggested sensory filter hypothesis. Advanced two-photon microscopy allowed me to investigate the neuronal representation of colony odors in different neuroanatomical compartments of the AL (Chapter 5). Although neuronal activity was distributed inhomogeneously, I did not find exclusive representation restricted to a single AL compartment. This result indicates that information about colony odors is processed in parallel, using the computational power of the whole AL network. In the AL, the patterns of glomerular activity (spatial activity patterns) were variable, even in response to repeated stimulation with the same colony odor (Chapter 4\&5). This finding is surprising, as earlier studies indicated that spatial activity patterns in the AL reflect how an odor is perceived by an animal (odor quality). Under natural conditions, multi-component odors constitute varying and fluctuating stimuli, and most probably animals are generally faced with the problem that these elicit variable neuronal responses. Two-photon microscopy revealed that variability was higher in response to nestmate than to non-nestmate colony odor (Chapter 5), possibly reflecting plasticity of the AL network, which allows template reformation. Due to their high variability, spatial activity patterns in response to different colony odors were not sufficiently distinct to allow attribution of odor qualities like 'friend' or 'foe'. This finding challenges our current notion of how odor quality of complex, multi-component odors is coded. Additional neuronal parameters, e.g. precise timing of neuronal activity, are most likely necessary to allow discrimination. The lower variability of activity patterns elicited by non-nestmate compared to nestmate colony odor might facilitate recognition of non-nestmates at the next level of the olfactory pathway. My research efforts made the colony recognition system accessible for direct neurophysiological investigations. My results show that ants can perceive their own nestmates. The neuronal representation of colony odors is distributed across AL compartments, indicating parallel processing. Surprisingly, the spatial activity patterns in response to colony are highly variable, raising the question how odor quality is coded in this system. The experimental advance presented in this thesis will be useful to gain further insights into how social insects discriminate friends and foes. Furthermore, my work will be beneficial for the research field of insect olfaction as colony recognition in social insects is an excellent model system to study the coding of odor quality and long-term memory mechanisms underlying recognition of complex, multi-component odors.}, subject = {Neuroethologie}, language = {en} } @phdthesis{Niewalda2010, author = {Niewalda, Thomas}, title = {Neurogenetic analyses of pain-relief learning in the fruit fly}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-65035}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {All animals learn in order to cope with challenges imposed on them by their environment. This is true also for both larval and adult fruit flies as exemplified in pavlovian conditioning. The focus of this Thesis is on various aspects of the fruit flies learning ability. My main project deals with two types of learning which we call punishment-learning and pain-relief learning. Punishment learning happens when fruit flies are exposed to an odour which is followed by electric shock. After such training, flies have learned that that odour signals pain and consequently will avoid it in the future. If the sequence of the two stimuli is reversed such that odour follows shock, flies learn the odour as a signal for relief and will later on approach it. I first report a series of experiments investigating qualitative and parametric features of relief-learning; I find that (i) relief learning does result from true associative conditioning, (ii) it requires a relatively high number of training trials, (iii) context-shock training is ineffective for subsequent shock-odour learning. A further question is whether punishment-learning and pain-relief learning share genetic determinants. In terms of genetics, I test a synapsin mutant strain, which lacks all Synapsin protein, in punishment and relief-learning. Punishment learning is significantly reduced, and relief-learning is abolished. Pan-neuronal RNAi-mediated knock-down of Synapsin results in mutant-like phenotypes, confirming the attribution of the phenotype to lack of Synapsin. Also, a rescue of Synapsin in the mushroom body of syn97 mutants restores both punishment- and relief-learning fully, suggesting the sufficiency of Synapsin in the mushroom body for both these kinds of learning. I also elucidate the relationship between perception and physiology in adult fruit flies. I use odour-shock conditioning experiments to identify degrees of similarity between odours; I find that those similarity measures are consistent across generalization and discrimination tasks of diverse difficulty. Then, as collaborator of T. V{\"o}ller and A. Fiala, I investigate how such behavioural similarity/dissimilarity is reflected at the physiological level. I combine the behaviour data with calcium imaging data obtained by measuring the activity patterns of those odours in either the sensory neurons or the projection neurons at the antennal lobe. Our interpretation of the results is that the odours perceptual similarity is organized by antennal lobe interneurons. In another project I investigate the effect of gustatory stimuli on reflexive behaviour as well as their role as reinforcer in larval learning. Drosophila larvae greatly alter their behaviour in presence of sodium chloride. Increasing salt concentration modulates choice behaviour from weakly appetitive to strongly aversive. A similar concentration-behaviour function is also found for feeding: larval feeding is slightly enhanced in presence of low salt concentrations, and strongly decreased in the presence of high salt concentrations. Regarding learning, relatively weak salt concentrations function as appetitive reinforcer, whereas high salt concentrations function as aversive reinforcer. Interestingly, the behaviour-concentration curves are shifted towards higher concentrations from reflexive behaviour (choice behaviour, feeding) as compared to associative learning. This dissociation may reflect a different sensitivity in the respective sensory-motor circuitry.}, subject = {Taufliege}, language = {en} } @article{SchubertUnkmeirKonradSlaninaetal.2010, author = {Schubert-Unkmeir, Alexandra and Konrad, Christian and Slanina, Heiko and Czapek, Florian and Hebling, Sabrina and Frosch, Matthias}, title = {Neisseria meningitidis Induces Brain Microvascular Endothelial Cell Detachment from the Matrix and Cleavage of Occludin: A Role for MMP-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68589}, year = {2010}, abstract = {Disruption of the blood-brain barrier (BBB) is a hallmark event in the pathophysiology of bacterial meningitis. Several inflammatory mediators, such as tumor necrosis factor alpha (TNF-a), nitric oxide and matrix metalloproteinases (MMPs), contribute to this disruption. Here we show that infection of human brain microvascular endothelial cells (HBMEC) with Neisseria meningitidis induced an increase of permeability at prolonged time of infection. This was paralleled by an increase in MMP-8 activity in supernatants collected from infected cells. A detailed analysis revealed that MMP-8 was involved in the proteolytic cleavage of the tight junction protein occludin, resulting in its disappearance from the cell periphery and cleavage to a lower-sized 50-kDa protein in infected HBMEC. Abrogation of MMP-8 activity by specific inhibitors as well as transfection with MMP-8 siRNA abolished production of the cleavage fragment and occludin remained attached to the cell periphery. In addition, MMP-8 affected cell adherence to the underlying matrix. A similar temporal relationship was observed for MMP activity and cell detachment. Injury of the HBMEC monolayer suggested the requirement of direct cell contact because no detachment was observed when bacteria were placed above a transwell membrane or when bacterial supernatant was directly added to cells. Inhibition of MMP-8 partially prevented detachment of infected HBMEC and restored BBB permeability. Together, we established that MMP-8 activity plays a crucial role in disassembly of cell junction components and cell adhesion during meningococcal infection.}, subject = {Neisseria meningitidis}, language = {en} } @article{RueschEberhartWallenbornetal.2010, author = {Ruesch, Dirk and Eberhart, Leopold H. J. and Wallenborn, Jan and Kranke, Peter}, title = {Nausea and Vomiting After Surgery Under General Anesthesia An Evidence-Based Review Concerning Risk Assessment, Prevention, and Treatment}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85847}, year = {2010}, abstract = {Background: The German-language recommendations for the management of postoperative nausea and vomiting(PONV) have been revised by an expert committee. Major aspects of this revision are presented here in the form of an evidence-based review article. Methods: The literature was systematically reviewed with the goal of revising the existing recommendations. New evidence-based recommendations for the management of PONV were developed, approved by consensus, and graded according to the scheme of the Scottish Intercollegiate Guidelines Network (SIGN). Results: The relevant risk factors for PONV include female sex, nonsmoker status, prior history of PONV, motion sickness, use of opioids during and after surgery, use of inhalational anesthetics and nitrous oxide, and the duration of anesthesia. PONV scoring systems provide a rough assessment of risk that can serve as the basis for a riskadapted approach. Risk-adapted prophylaxis, however, has not been shown to provide any greater benefit than fixed (combination) prophylaxis, and PONV risk scores have inherent limitations; thus, fixed prophylaxis may be advantageous. Whichever of these two approaches to manage PONV is chosen, high-risk patients must be given multimodal prophylaxis, involving both the avoidance of known risk factors and the application of multiple validated and effective antiemetic interventions. PONV should be treated as soon as it arises, to minimize patient discomfort, the risk of medical complications, and the costs involved. Conclusion: PONV lowers patient satisfaction but is treatable. The effective, evidence-based measures of preventing and treating it should be implemented in routine practice.}, language = {en} } @techreport{KneitzBroeckerBecker2010, author = {Kneitz, H. and Br{\"o}cker, Eva B. and Becker, JC}, title = {Mycosis fungoides bullosa: a case report and review of the literature}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68233}, year = {2010}, abstract = {Introduction: Mycosis fungoides, the most common type of cutaneous T-cell lymphoma, can manifest in a variety of clinical and histological forms. Bulla formation is an uncommon finding in mycosis fungoides and only approximately 20 cases have been reported in the literature. Case presentation: We present a case of rapidly progressive mycosis fungoides in a 68-year-old Caucasian man who initially presented with erythematous plaques characterised by blister formation. Conclusion: Although mycosis fungoides bullosa is extremely rare, it has to be regarded as an important clinical subtype of cutaneous T-cell lymphoma. Mycosis fungoides bullosa represents a particularly aggressive form of mycosis fungoides and is associated with a poor prognosis. The rapid disease progression in our patient confirms bulla formation as an adverse prognostic sign in cutaneous T-cell lymphoma.}, subject = {Mycosis fungoides bullosa}, language = {en} } @phdthesis{Geiger2010, author = {Geiger, Michael}, title = {Monetary Policy in China: Institutions, Targets, Instruments and Strategies}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69945}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {China's monetary policy aims to reach two final targets: a paramount economical target (i.e. price stability) and a less important political target (i.e. economic growth). The main actor of monetary policy is the central bank, the People's Bank of China (PBC). But the PBC is a non-independent central bank. The State Council approves the goals of monetary policy. Very limited instrument independence means that interest rates cannot be set at the PBC's discretion, and in-sufficient personal independence fails to insulate central bank officials from political influence. Monetary policy in China applies to two sets of monetary policy instruments: (i) instruments of the PBC; and (ii) non-central bank policy instruments. The instruments of the PBC include price-based indirect and quantity-based direct instruments. Non-central bank policy instruments include price and wage controls. The simultaneous usage of all these instruments leads to various distortions that ultimately prevent the interest rate channel of monetary transmission from functioning. Moreover, the strong influences of quantity-based direct instruments and non-central bank policy instruments bring into question the approach of indirect monetary policy in general. The PBC officially follows the monetary targeting approach with monetary aggregates as intermediate targets. Domestic loan growth and the exchange rate are defined as additional intermediate targets. In an in-depth analysis of the intermediate targets two main issues are primarily explored: (i) Are the intermediate targets of the Chinese monetary policy controllable? (ii) Is a sufficient relationship between these targets and the inflation rate observable? It is then shown that monetary aggregates are very difficult to control, but they have a satisfactory relationship with the inflation rate. Similarly, domestic loan growth is difficult to control - a fact largely attributed to the interest rate elasticity of loans - while there is a particularly close relationship between credit growth and the inflation rate. The exchange rate as an intermediate target can be controlled through foreign exchange market interventions; at the same time the exchange rate appears to have a significant relationship to the domestic inflation rate. Discussing the special issue of sterilizing foreign exchange inflows, the study concludes that between 2002 and 2008 not only no costs were incurred by sterilization operations, but that the central bank was actually able to realize a profit through foreign exchange market interventions. Based on this, it is concluded that the exchange rate target has not adversely affected the domestic orientation of monetary policy on the whole. The final part of the study examines whether there are any alternative monetary policy approaches that may be able to describe the policy approach in China; special focus is placed on nominal GDP targeting, the Taylor rule, and inflation targeting. A literature review reveals that the concept of nominal GDP targeting may be able to detect inflationary tendencies in the economy and, in combination with other indicators, it could be a suitable concept to assess the overall economic situation. The author calculates a Taylor rule for China from 1994 to 2008 and concludes that there is no close relationship between the PBC lending and the Taylor rate. The author then designs an augmented Taylor rule expanded to include a credit component (credit-augmented Taylor rule). The study shows that the augmented Taylor rule does not perform much better than the original one, but that it maps high inflationary periods relatively well. This is attributed to direct interventions into the credit markets, which have played a major role in combating inflationary cycles over the past decades. The analysis ends with an introduction of the concept of inflation targeting and an examination of whether this could describe monetary policy in China. It is clear that the PBC does not currently follow the inflation targeting approach, although the Chinese authorities could actually be able to influence inflation expectations effectively, not least through direct instruments such as price controls. The author notes that the PBC indeed had a good track record of fighting inflation between 1994 and 2008, and that this may now indicate a good time to think about introducing inflation targeting in China. The central conclusion of the study is that the proven gradual approach to economic and monetary reforms in China is reaching its limit. To break the vicious cycle that relies on the continuous use of quantity-based instruments to compensate for the ineffective price-based instruments - which in turn arises from the simultaneous use of both types of instruments - a complete shift away from quantity-based instruments is needed. Only then the approach of indirect monetary policy, which was officially introduced in 1998, could come into full play.}, subject = {Geldpolitik}, language = {en} } @phdthesis{Harth2010, author = {Harth, Stefan}, title = {Molecular Recognition in BMP Ligand-Receptor Interactions}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52797}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Bone Morphogenetic Proteins (BMPs) are secreted multifunctional signaling proteins that play an important role during development, maintenance and regeneration of tissues and organs in almost all vertebrates and invertebrates. BMPs transmit their signals by binding to two types of serine-/threonine-kinase receptors. BMPs bind first to their high affinity receptor, thereby recruiting their low affinity receptor into the complex. This receptor assembly starts a Smad (Small mothers against decapentaplegic) protein signaling cascade which regulates the transcription of responsive genes. Up to date, only seven type I and five type II receptors are known for more than 30 ligands. Therefore, many BMP ligands can recruit more than one receptor subtype. Vice versa, receptors can bind to several ligands, indicating a highly promiscuous ligand-receptor interaction. This raises the following questions: (i) How are BMPs able to induce ligand-specific signals, despite forming complexes with identical receptor composition and (ii) how are they able to recognize and bind various binding partners in a highly specific manner. From the ligand's point of view, heterodimeric BMPs are valuable tools for studying the interplay between different sets of receptors, thereby providing new insights into how the various BMP signals can be generated. This study describes the expression and purification of the heterodimers BMP-2/6 and -2/7 from E.coli cells. BIAcore interaction studies and various in vitro cell activity assays revealed that the generated heterodimers are biologically active. Furthermore, BMP-2/6 and -2/7 exhibit a higher biological activity in most of the cell assays compared to their homodimeric counterparts. In addition, the BMP type I receptor BMPR-IA is involved in heterodimeric BMP signaling. However, the usage of other type I receptor subtypes (e.g. ActR-I) building a heteromeric ligand-receptor type I complex as indicated in previous works could not be determined conclusively. Furthermore, BMP heterodimers seem to require only one type I receptor for signaling. From the receptors' point of view, the BMP type I receptor BMPR-IA is a prime example for its promiscuous binding to different BMP ligands. The extracellular binding interface of BMPR-IA is mainly unfolded in its unbound form, requiring a large induced fit to adopt the conformation when bound to its ligand BMP-2. In order to unravel whether the binding promiscuity of BMPR-IA is linked to structural plasticity of its binding interface, the interaction of BMPR-IA bound to an antibody Fab fragment was investigated. The Fab fragment was selected because of its ability to recognize the BMP-2 binding epitope on BMPR-IA, thus neutralizing the BMP-2 mediated receptor activation. This study describes the crystal structure of the complex of the extracellular domain of BMPR-IA bound to the antibody Fab fragment AbyD1556. The crystal structure revealed that the contact surface of BMPR-IA overlaps extensively with the contact surface of BMPR-IA for BMP-2 interaction. Although the contact epitopes of BMPR-IA to both binding partners coincide, the three-dimensional structures of BMPR-IA in both complexes differ significantly. In contrast to the structural differences, alanine-scanning mutagenesis of BMPR-IA showed that the functional determinants for binding to both the antibody and BMP-2 are almost identical. Comparing the structures of BMPR-IA bound to BMP-2 or to the Fab AbyD1556 with the structure of unbound BMPR-IA revealed that binding of BMPR-IA to its interaction partners follows a selection fit mechanism, possibly indicating that the ligand promiscuity of BMPR-IA is inherently encoded by structural adaptability.}, subject = {Knochen-Morphogenese-Proteine}, language = {en} } @phdthesis{Paul2010, author = {Paul, Markus Christian}, title = {Molecular beam epitaxy and properties of magnetite thin films on semiconducting substrates}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56044}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {The present thesis is concerned with molecular beam epitaxy of magnetite (Fe3O4) thin films on semiconducting substrates and the characterization of their structural, chemical, electronic, and magnetic properties. Magnetite films could successfully be grown on ZnO substrates with high structural quality and atomically abrupt interfaces. The films are structurally almost completely relaxed exhibiting nearly the same in-plane and out-of-plane lattice constants as in the bulk material. Films are phase-pure and show only small deviations from the ideal stoichiometry at the surface and in some cases at the interface. Growth proceeds via wetting layer plus island mode and results in a domain structure of the films. Upon coalescence of growing islands twin-boundaries (rotational twinning) and anti-phase boundaries are formed. The overall magnetization is nearly bulk-like, but shows a slower approach to saturation, which can be ascribed to the reduced magnetization at anti-phase boundaries. However, the surface magnetization which was probed by x-ray magnetic circular dichroism was significantly decreased and is ascribed to a magnetically inactive layer at the surface. Such a reduced surface magnetization was also observed for films grown on InAs and GaAs. Magnetite could also be grown with nearly ideal iron-oxygen stoichiometry on InAs substrates. However, interfacial reactions of InAs with oxygen occur and result in arsenic oxides and indium enrichment. The grown films are of polycrystalline nature. For the fabrication of Fe3O4/GaAs films, a postoxidation of epitaxial Fe films on GaAs was applied. Growth proceeds by a transformation of the topmost Fe layers into magnetite. Depending on specific growth conditions, an Fe layer of different thickness remains at the interface. The structural properties are improved in comparison with films on InAs, and the resulting films are well oriented along [001] in growth direction. The magnetic properties are influenced by the presence of the Fe interface layer as well. The saturation magnetization is increased and the approach to saturation is faster than for films on the other substrates. We argue that this is connected to a decreased density of anti-phase boundaries because of the special growth method. Interface phases, viz. arsenic and gallium oxides, are quantified and different growth conditions are compared with respect to the interface composition.}, subject = {Molekularstrahlepitaxie}, language = {en} } @phdthesis{Li2010, author = {Li, Jian-Qiang}, title = {Modulating the expression of enzymes of isoprenoid synthesis: effects on Vgamma9Vdelta2 T cell activation and tumor cell growth}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-46388}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {This study focuses on phosphoantigen specific Vg9Vd2 T cells which only exist in human and non-human primates. This population accounts for 1\%-5\% of peripheral blood T-lymphocytes but their frequency can rise to 50\% of total blood T cells upon infection. Vg9Vd2 T cells can be activated by nonpeptide compounds with critical phosphate moieties which are termed as phosphoantigens. These include isopentenyl pyrophosphate (IPP), a key compound of isoprenoid synthesis in all organisms, and (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), a direct precursor of IPP in DOXP pathway which only exist in eubacteria, plants, apicomplexaen parasites. Its activity as phosphoantigen is at least 1000 fold higher than that of IPP. However, direct structural evidence of phosphoantigen binding to the TCR is missing so far. Moreover, Vg9Vd2 T cells have potent anti-tumor activity e.g. against the B-cell lymphoma Daudi, whose Vg9Vd2 T cell activating properties have been suggested to result from sensing of abnormal intracellular IPP levels by the Vg9Vd2 TCR or Vg9Vd2 TCR binding to other postulated ligands such as an ectopically expressed F1-ATPase or UL-16 binding protein 4 (ULBP4). Aminobisphosphonates and alkymines were hypothesized to activate Vg9Vd2 T cells indirectly by inhibiting the IPP consuming enzyme farnysyl pyrophosphates synthesis (FPPS) although off target effects of these drugs or a direct interaction with the Vg9Vd2 TCR could not be excluded. This thesis presents new approaches for the mechanistic analysis of Vg9Vd2 T cell activation. By employing retroviral transduction of FPPS specific shRNA, it shows that specific shRNA reduces expression of FPPS and is sufficient to convert hematopoietic and non-hematopoietic tumor cell lines into Vg9Vd2 T cell activators. FPPS knockdown cells activated Vg9Vd2 T cells as measured by increased levels of CD69 and CD107a, kill of FPPS knockdown cells and induction of IFN-\&\#947; secretion. The IPP-synthesis-inhibiting drug mevastatin reduced Vg9Vd2 T cell activation by FPPS knockdown cells or aminobisphosphonate treated cells but not activation by the phosphoantigen bromohydrin pyrophosphate (BrHPP). A reduced growth of the FPPS knockdown cells has not been observed which is different to what has been reported for aminobisphosphonate treated cells. Finally, the human B-cell lymphoma RAJI has been transduced with Tetracyclin-inducible FPPS specific shRNA and proven to gain and loose the capacity to activate Vg9Vd2 TCR transductants upon doxycylin provision or removal. Another approach for the analysis of Vg9Vd2 T cell activation is Vg9Vd2 TCR transduced mouse cell lines with specificity for phosphoantigens. In contrast to the previously used Vg9Vd2 TCR transduced Jurkat cells, these cells do not present phosphoantigens, and are therefore specially suited for analysis of phosphoantigen presentation. The response of the new TCR transductants to presumed Vg9Vd2 TCR ligands/activators such as phosphoantigens, aminobisphosphonates or FPPS knockdown cells, depended strongly on the expression of a rat/mouse CD28 molecule by the transductants and its ligation by the (CD80) counter receptor on the ligand-presenting cell. The response is likely to reflect recognition of cognate Vg9Vd2 TCR antigens since mutations in the TCR-\&\#948; chain CDR2 and 3 abolished this response but activation by TCR or CD3 specific antibodies. A major difference between TCR transductants and primary gd T cells, was the lacking response of TCR transductants to Daudi or IPP. In addition their sensitivity to other soluble phosphoantigens was about 100 fold weaker than that of primary cells, stimulation of both cell type to CD80 expressing FPPS knock down or aminobisphosphonates was similar. Finally, the transductants have also been used to analyze effects of over-expression or knockdown of enzymes of isoprenoid synthesis such as 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase or HMGR), mevalonate-5-pyrophosphate decarboxylase (MVD), isopentenyl pyrophosphate isomerase (IDI), geranyl-geranyl pyrophosphate synthase (GGPPS) but no clear effects have been found. In conclusion, this thesis supports the concept of Vg9Vd2 T cells being sensors of a dysregulated isoprenoid metabolism and established new tools to study ligand recognition and TCR mediated activation of this T cell population. These tools will be most useful to address following questions: 1) How does the dysregulation of isoprenoid metabolism affect tumor growth? 2) What is the correlation between the modulation of IPP levels and the Vg9Vd2 TCR binding or expression of other postulated ligands? 3) Are there any mevalonate pathway enzymes other than FPPS and HMGR, which play an important role in Vg9Vd2 T cells activation? 4) What is/are the putative phosphoantigen-presenting molecule(s)?}, subject = {Primaten}, language = {en} } @article{MeierjohannHufnagelWendeetal.2010, author = {Meierjohann, Svenja and Hufnagel, Anita and Wende, Elisabeth and Kleinschmidt, Markus A. and Wolf, Katarina and Friedl, Peter and Gaubatz, Stefan and Schartl, Manfred}, title = {MMP13 mediates cell cycle progression in melanocytes and melanoma cells: in vitro studies of migration and proliferation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68335}, year = {2010}, abstract = {Background: Melanoma cells are usually characterized by a strong proliferative potential and efficient invasive migration. Among the multiple molecular changes that are recorded during progression of this disease, aberrant activation of receptor tyrosine kinases (RTK) is often observed. Activation of matrix metalloproteases goes along with RTK activation and usually enhances RTK-driven migration. The purpose of this study was to examine RTKdriven three-dimensional migration of melanocytes and the pro-tumorigenic role of matrix metalloproteases for melanocytes and melanoma cells. Results: Using experimental melanocyte dedifferentiation as a model for early melanomagenesis we show that an activated EGF receptor variant potentiates migration through three-dimensional fibrillar collagen. EGFR stimulation also resulted in a strong induction of matrix metalloproteases in a MAPK-dependent manner. However, neither MAPK nor MMP activity were required for migration, as the cells migrated in an entirely amoeboid mode. Instead, MMPs fulfilled a function in cell cycle regulation, as their inhibition resulted in strong growth inhibition of melanocytes. The same effect was observed in the human melanoma cell line A375 after stimulation with FCS. Using sh- and siRNA techniques, we could show that MMP13 is the protease responsible for this effect. Along with decreased proliferation, knockdown of MMP13 strongly enhanced pigmentation of melanocytes. Conclusions: Our data show for the first time that growth stimuli are mediated via MMP13 in melanocytes and melanoma, suggesting an autocrine MMP13-driven loop. Given that MMP13-specific inhibitors are already developed, these results support the evaluation of these inhibitors in the treatment of melanoma.}, subject = {Medizin}, language = {en} }