@phdthesis{Afify2007, author = {Afify, Samar}, title = {Drug targeting delivery systems for treatment of Raf-1 induced lung tumors in mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22249}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The aim of the present study was to design different dosage forms as carrier systems to deliver sorafenib to the lung of BXB-23 transgenic mice using different routes of administration. Three dosage forms were used one of them was an oil-in-water emulsion and the oral route was chosen for this experiment. The other delivery system was a liposome preparation for intratracheal instillation. In this case the oral route was considered as a control experiment. The last dosage form was PLGA microspheres. Before sorafenib administration it was important to develop a HPLC method to assess sorafenib absorption after its administration and to determine its concentrations in mouse serum. The HPLC method allowed sorafenib quantification in small volumes (30 µl) of mouse serum and tissues. The developed HPLC method was validated resulting in satisfactory selectivity, good linearity, good accuracy and precision over the concentration range examined. Sorafenib was successfully incorporated in a fat emulsion (o/w) using a traditional method resulting in a white homogenous emulsion and no particle aggregation was observed. Sorafenib exhibited antitumor activity on the lung adenoma in BXB-23 transgenic mice when administered orally (2 mg sorafenib per mouse) in the emulsion preparation. The determined effect was an approximately 29 \% reduction in the tumor area of the adenoma foci and a proliferation reduction. In order to improve the pharmacological effects of sorafenib on the lung adenoma in BXB-23 mice, the targeting of sorafenib directly to the site of action (the lung) was an attractive concept. For this purpose the intratracheal route was used. Since sorafenib administration by instillation required incorporation of sorafenib in a dosage form suitable for its lipophilic nature, a liposome suspension was the second dosage form used. A lyophilization method was employed for sorafenib liposome preparation utilizing dilauroylphosphatidylcholine (DLPC) which is safe and tolerable for the lung. Incorporation of sorafenib in the liposomes did not influence the particle size and its distribution. The sorafenib liposomes showed high encapsulation efficiency, good stability at 4 °C for one month and satisfactory in vitro release properties and inhibited Raf-1 mediated activation of ERK in cell culture assay. In a pharmacokinetic experiment sorafenib loaded liposomes were instilled directly into the lung. The results revealed that a significant level of sorafenib was achieved in the lung tissues after 2 hours and then reduced after 48 h and remained nearly constant for one week. On the other hand, only traces of sorafenib were found in the mice serum up to 48 h. Subsequently, the pharmacological activity of sorafenib (1 mg per mouse) was studied when delivered in a liposomal suspension intratracheally to treat the lung adenoma of BXB-23 mice. The data of this experiment demonstrated that sorafenib intratracheal instillation resulted in a reduction of tumor area of adenoma foci (67 \%) and an elevation of the percent of apoptotic cells. In contrast, prolongation of the treatment period did not further enhance sorafenib activity on the lung adenoma. This previous finding suggested a development of multidrug resistance (MDR) by the adenoma foci cells against sorafenib instillation, which was examined by immunohistochemistry staining. The percent of MDR positive cells was higher after two and three weeks sorafenib liposome instillation treatment than that after one week treatment. The last dosage form used for sorafenib was microspheres, which were prepared by emulsion-diffusion-evaporation method using biodegradable PLGA 50:50 resulting in a white lyophilized powder. The system was characterized physicochemically and revealed a good microspheres yield, high encapsulation efficiency, a homogenous particle size distribution and slow in vitro release of sorafenib. The other strategy studied in the present research project was gene delivery to target the lung bearing tumor of BXB-23 mice using a non-viral vector (polyethylenimine). Polyethylenimine (PEI) was used to investigate its efficiency in transfecting lung bearing tumor of BXB-23 mice model and its ability to transfect the adenoma foci cells. LacZ, which encodes Beta-galactosidase was used in the present study as a reporter gene and was complexed with PEI before delivered intravenously. A high LacZ expression in the alveolar region with some expression in the adenoma foci was observed. On contrary, a low LacZ expression in the alveoli and in the adenoma foci was achieved after instillation of the same polyplex intratracheally.}, subject = {Maus}, language = {en} } @phdthesis{Alboteanu2007, author = {Alboteanu, Ana Maria}, title = {The Noncommutative Standard Model : Construction Beyond Leading Order in Theta and Collider Phenomenology}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24334}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Trotz seiner pr{\"a}zisen {\"U}bereinstimmung mit dem Experiment ist die G{\"u}ltigkeit des Standardmodells (SM) der Elementarteilchenphysik bislang nur bis zu einer Energieskala von einigen hundert GeV gesichert. Abgesehen davon erweist sich schon das Einbinden der Gravitation in einer einheitlichen Beschreibung aller fundamentalen Wechselwirkungen als ein durch gew{\"o}hnliche Quantenfeldtheorie nicht zu l{\"o}sendes Problem. Das Interesse an Quantenfeldtheorien auf einer nichtkommutativen Raumzeit wurde durch deren Vorhersage als niederenergetischer Limes von Stringtheorien erweckt. Unabh{\"a}ngig davon, kann die Nichtlokalit{\"a}t einer solchen Theorie den Rahmen zur Einbeziehung der Gravitation in eine vereinheitlichende Theorie liefern. Die Hoffnung besteht, dass die Energieskala Lambda_NC, ab der solche Effekte sichtbar werden k{\"o}nnen und f{\"u}r die es einerlei theoretischen Vorhersagen gibt, schon bei der n{\"a}chsten Generation von Beschleunigern erreicht wird. Auf dieser Annahme beruht auch die vorliegende Arbeit, im Rahmen deren eine m{\"o}gliche Realisierung von Quantenfeldtheorien auf nichtkommutativer Raumzeit auf ihre ph{\"a}nomenologischen Konsequenzen hin untersucht wurde. Diese Arbeit ist durch fehlende LHC (Large Hadron Collider) Studien f{\"u}r nichkommutative Quantenfeldtheorien motiviert. Im ersten Teil des Vorhabens wurde der hadronische Prozess pp-> Z gamma -> l+l- gamma am LHC sowie die Elektron-Positron Paarvernichtung in ein Z-Boson und ein Photon am ILC (International Linear Collider) auf nichtkommutative Signale hin untersucht. Die ph{\"a}nomenlogischen Untersuchungen wurden im Rahmen dieses Modells in erster Ordnung des nichtkommutativen Parameters Theta durchgef{\"u}hrt. Eine nichtkommutative Raumzeit f{\"u}hrt zur Brechung der Rotationsinvarianz bez{\"u}glich der Strahlrichtung der einlaufenden Teilchen. Im differentiellen Wirkungsquerschnitt f{\"u}r Streuprozesse {\"a}ussert sich dieses als eine azimuthale Abh{\"a}ngigkeit, die weder im SM noch in anderen Modellen jenseits des SM auftritt. Diese klare, f\"ur nichtkommutative Theorien typische Signatur kann benutzt werden, um nichtkommutative Modelle von anderen Modellen, die neue Physik beschreiben, zu unterscheiden. Auch hat es sich erwiesen, dass die azimuthale Abh{\"a}ngigkeit des Wirkungsquerschnittes am besten daf\"ur geeignet ist, um die Sensitivit{\"a}t des LHC und des ILC auf der nichtkommutativen Skala \$\Lnc\$ zu bestimmen. Im ph{\"a}nomenologischen Teil der Arbeit wurde herausgefunden, dass Messungen am LHC f{\"u}r den Prozess pp-> Z gamma-> l+l- gamma nur in bestimmten F{\"a}llen auf nichtkommutative Effekte sensitiv sind. F{\"u}r diese F{\"a}lle wurde f{\"u}r die nichtkommutative Energieskala Lambda_NC eine Grenze von Lambda_NC > 1.2 TeV bestimmt. Diese ist um eine Gr{\"o}ßenordnung h{\"o}her als die Grenzen, die von bisherigen Beschleunigerexperimenten hergeleitet wurden. Bei einem zuk{\"u}nftigen Linearbeschleuniger, dem ILC, wird die Grenze auf Lambda_NC im Prozess e^+e^- -> Z gamma -> l^+ l^- gamma wesentlich erh{\"o}ht (bis zu 6 TeV). Abgesehen davon ist dem ILC gerade der f{\"u}r den LHC kaum zug{\"a}ngliche Parameterbereich der nichtkommutativen Theorie erschlossen, was die Komplementarit{\"a}t der beiden Beschleunigerexperimente hinsichtlich der nichtkommutativen Parameter zeigt. Der zweite Teil der Arbeit entwickelte sich aus der Notwendigkeit heraus, den G{\"u}ltigkeitsbereich der Theorie zu h{\"o}heren Energien hin zu erweitern. Daf{\"u}r haben wir den neutralen Sektor des nichtkommutativen SM um die n{\"a}chste Ordnung in Theta erg{\"a}nzt. Es stellte sich wider Erwarten heraus, dass die Theorie dabei um einige freie Parameter erweitert werden muss. Die zus{\"a}tzlichen Parameter sind durch die homogenen L{\"o}sungen der Eich{\"a}quivalenzbedingungen gegeben, welche Ambiguit\"aten der Seiberg-Witten Abbildungen darstellen. Die allgemeine Erwartung war, dass die Ambiguit{\"a}ten Feldredefinitionen entsprechen und daher in den Streumatrixelementen verschwinden m\"ussen. In dieser Arbeit wurde jedoch gezeigt, dass dies ab der zweiten Ordnung in Theta nicht der Fall ist und dass die Nichteindeutigkeit der Seiberg-Witten Abbildungen sich durchaus in Observablen niederschl{\"a}gt. Die Vermutung besteht, dass jede neue Ordnung in Theta neue Parameter in die Theorie einf{\"u}hrt. Wie weit und in welche Richtung die Theorie auf nichtkommutativer Raumzeit entwickelt werden muss, kann jedoch nur das Experiment entscheiden.}, subject = {Feldtheorie}, language = {en} } @phdthesis{Ali2007, author = {Ali, Walid Wahid}, title = {Screening of plant suspension cultures for antimicrobial activities and characterization of antimicrobial proteins from Arabidopsis thaliana}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24358}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Die zunehmende Resistenz humanpathogener Mikroorganismen gegen bekannte Antibiotika bedingt die Notwendigkeit, nach neuen Quellen f{\"u}r die Produktion antimikrobieller Stoffe zu suchen. Als eine solche Quelle gelten besonders Pflanzen, da viele antimikrobielle Stoffe bei der Abwehr gegen invasierende Mikroorganismen bilden. Das Ziel der vorliegenden Arbeit besteht in der Charakterisierung von pflanzlichen Zellkulturen im Hinblick auf ihre F{\"a}higkeit, anitimkrobielle Aktivit{\"a}t gegen humanpathogene Mikroorganismen zu entwickeln. Dabei sollen aktive Proteine aufgereinigt und die kodierenden Gene isoliert werden. Dazu wurden zehn verschiede pflanzliche Suspensionskulturen in Anwesenheit von neun Elicitoren auf ihre antimikrobielle Aktivit{\"a}t gegen f{\"u}nf humanpathogene Mikroorganismen getestet. Dabei erwiesen sich die heterotrophen Kulturen im Vergleich zu den autotrophen als aktiver. Die h{\"o}chste antimikrobielle Aktivit{\"a}t wurde bei der intrazellul{\"a}ren Fraktion der mixotrophen Kultur von Arabidopsis thaliana nach Elicitierung mit Salicyls{\"a}ure nachgewiesen. Da in einem Pr{\"a}zipitat mit Ammoniumsulfat Aktivit{\"a}t gegen Candida maltosa nachgewiesen wurde, konnte angenommen werden, dass es sich bei der aktiven Komponente um ein Protein handelt. Durch Hochgeschwindigkeitszentrifugation wurde eine partielle Aufreinigung dieser aktiven Komponente erreicht. Die proteinoide Natur wurde durch Bioautographie best{\"a}tigt und das Molekulargewicht auf ca. 26kDa gesch{\"a}tzt. Mittels Gelfiltration und Massenspektrometrie wurde das Protein aufgereinigt. Die Mikrosequenzierung ergab ein Protein mit bisher unbekannter Funktion, das eine pflanzliche Stressdom{\"a}ne (PLAT) enth{\"a}lt. Das Protein wurde daraufhin als AtPDP1 (Arabidopsis thaliana Plat-Domain Protein 1) bezeichnet. Das Gen und ein zweites mit hochgradiger Homologie (AtPDP2) wurden in E. coli kloniert. Der Digital Northern zeigt an, das beide Gene durch verschiedene Pathogene induziert werden, sowie von Chemikalien, die pflanzliche Abwehr hervorrufen und weiterhin von Phytohormonen. Der Versuch, AtPDP1 unter die Kontrolle eines Promors einer Proteinase zu stellen, der Induzierbarkeit durch Elicitoren vermittelt, blieb erfolglos. Weiterhin wurden 13 Thaumatingene aus Arabidopsis thaliana in E. coli kloniert, da ihre antimikrobielle Aktivit{\"a}t bekannt ist, und ihre Expression durch verschiedene Stimuli induziert wird. Von diesen Genen zeigt der Digital Northern bei allen Stimuli eine maximale Expression f{\"u}r At1g75800, w{\"a}hrend At1g75050 minimal induziert ist. Diese Gene stehen f{\"u}r zuk{\"u}nftige Studien zur Verf{\"u}gung.}, subject = {-}, language = {en} } @phdthesis{Andrei2007, author = {Andrei, Horia-Sorin}, title = {Infrared photodissociation spectroscopy of ionic hydrocarbons : microsolvation and protonation sites}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24652}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {This work has presented a spectroscopic analysis of three types of hydrocarbon cations: two ionized aromatic hydrocarbons, two protonated aromatic hydrocarbons and the cation of a fundamental radical hydrocarbon. The experiments were centered on the proton stretch vibrations of mass-selected complexes of these systems and polar (H2O) and non polar (Ar, N2, CO2) ligands. The experiments have been done in a tandem mass spectrometer coupled with an electron impact ionization ion source; an OPO laser system was used as tunable IR light source. All the proposed dimer structures have been also modeled using quantum chemical calculations (QCC). These calculations have consistently been matched with the experimental results and have enabled clear identification of the spectral features observed. This has enabled the evaluation of thermochemical properties which could not be extracted directly from experiment. The experiments done on complexes of 1-Np+ and Im+ have allowed for the acidity of their various groups to be probed: the shifts in the frequency as well as the enhancement in the intensity of the OH and NH stretch vibrations resulting from the complexation have yielded dependences on both the species (L) and the number (n) of the ligands. OH bound 1-Np+···Ar has been detected for the first time, showing that the REMPI-IRPD method is severely limited with respect to the production of the most stable isomer of a given cationic complex. The detection of c-1-Np+···(N2)n corresponds to the first observation of c-1-Np+ complexes and enables thus direct comparison of both 1-Np+ rotamers. The shift of the NH vibration of Im+···N2(H) yielded the first experimental estimate for the PA of the imidazyl radical. It was also found that the most stable 1-Np+···Ar and Im+···Ar structures differ qualitatively from that of the corresponding neutral dimers (H-bound vs pi-bound), emphasizing the large impact of ionization on the interaction potential and the preferred recognition motif between acidic aromatic molecules (A) and nonpolar ligands. The IRPD spectra of 1-Np+···Ln and Im+···Ln yielded spectroscopic information about the CH, NH and OH stretch vibrations of bare 1-Np+ and Im+. The dependence of the shifts in the frequency of the OH and NH stretch vibrations allows for creating microsolvation models. The spectroscopic results obtained on size-selected 1-NpH+···Ln show that, in the output of the presently used ion source, three classes of 1-NpH+ isomers can be identified: oxonium ions (1-Np protonated at the O atom); carbenium ions obtained by protonation in the para and ortho positions with respect to the OH functional group; carbenium ions obtained by the addition of a proton to well-defined sites on the second naphthalene ring. The spectral identification of these three classes of protonation sites is supported by their different photofragmentation patterns. It was demonstrated that the spectroscopic monitoring of the microsolvation of ImH+ in Ar and N2 together with the QCCs paint a very detailed picture of the microsolvation process, evidencing clear differences between the microsolvation models as function of the PA of the ligands. Important differences have also been identified between the various binding sites, enabling the creation of a clear scale of priorities for occupation of the binding sites during microsolvation. The application of IRPD to the study of microhydrated ImH+ provided for the first time direct spectroscopic information on the properties of the N-H bonds of this biomolecular building block under controlled microhydration. It was demonstrated that, as protonation enhances the acidity of the NH groups, the ability for proton conductivity of ImH+ increases. A very important result is derived from the IRPD spectroscopy of C2H5+···L (L = Ar, N2, CO2, CH4) dimers. The equilibrium geometry of the C2H5+ has long been debated. Now, IRPD spectra were recorded over the range of the CH stretch fundamentals (covering possible sp3 and sp2 hybridization of C). Depending on the ligand species, the spectra are found to be dominated by the fingerprint of two largely different dimer geometries. Using the experimental C2H5+···Ar spectrum and the corresponding QCCs, the structure of the (weakly perturbed) C2H5+ was found to be the nonclassical one, with one proton straddling across the C=C bond of the H2C=CH2. On the other hand, ligands like N2 and CH4 are strongly influencing the geometry, as seen in the spectral signatures of the C2H5+···N2 and C2H5+···CH4, which correspond to the classical [H2CCH3]+. It was thus demonstrated that while the nonclassical C2H5+ is the global minimum on the PES of the free [C2,H5]+, the structure of the C2H5+ can be strongly influenced by the chemical properties of the environment.}, subject = {Infrarot}, language = {en} } @phdthesis{Arnone2007, author = {Arnone, Mario}, title = {Theoretical Characterization and Optimization of Photochemical Alkoxyl Radical Precursors}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23815}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Oxygen-centered radicals are important intermediates in photobiological, mechanistic and synthetic studies. The majority of precursors of reactive oxyl radicals are labile and thus delicate to handle. Therefore N-(alkoxy)-pyridinethiones and N-(Alkoxy)-thiazolethiones have attracted attention as "mild'' photochemical source of alkoxyl radicals, in the last few years. A disadvantage of the pyridine compounds, is their sensibility to daylight. Despite of their similarities, both molecules behave surprisingly different, if photolyzed in the absence of trapping reagents. The pyridinethione compounds undergo highly efficient radical chain reactions under such conditions while the corresponding thiazolethiones react surprisingly sluggish and give rise to several unwanted side products. The properties of both compounds should be understood and optimized in the frame of this work. Additionally new compounds should be suggested that can also be applied in the photochemical alkoxyl radical generation. Some background information about the generation and application of alkoxyl radicals is provided in chapter 2. Electronic excitations and UV/vis spectroscopy together with a description of quantum chemical approaches that are able to calculate such phenomena are outlined in chapter 3. Chapter 4 deals with the description of the vertical excitation spectra. During the validation CASSCF, CASPT2, TD-DFT and RI-CC2 were tested with respect to their ability to describe the vertical excitations in both compounds. The CASPT2 approach gives accurate descriptions of the electronic excitation spectra of all compounds. The time-dependent DFT results are very sensitive on the choice of the functional and a validation of the results should be always done. On the basis of these computations the spectroscopic visible absorption bands of both compounds were assigned to a pi-->pi* transition in the thiohydroxamic acid functionality. In chapter 5 the mechanism of the thermally and the photochemically induced N,O homolysis in both compounds is unveiled. The near UV-induced N,O homolysis will start from the S2 state. The expected relaxation from the S2- to the S1-state and the dissociation process is expected to be very fast in the case of the thiazolethione compound. The potential surfaces of the pyridine compound in contrast point to a slower N,O bond dissociation. Due to the resulting faster dissociation process the excess energy which results from the photochemical activation is quenched only to small amounts. The maximal possible excess energy of the fragments is lower and a quenching is much more likely in the case of the pyridinethione compounds. This explaines the different reactivities of both compounds. For the also already successfully applied precursor system N-(alkoxy)-pyridineones the computed dissociation paths show courses that clearly predict a slow bond dissociation process. Chapter 6 deals with the tuning of the initial excitation wave length of the known pyridinethiones und thiazolethiones. In the first part the effects of substituents on the thiazolethione heterocycle was examined. The UV/vis spectra of 4 and 5 substituted thiazolethiones can be interpreted like the spectrum of the parent compound. The second part of chapter 6 deals with the identification of a substitution pattern on the pyridine heterocycle which induces a blue shift of the photo active band. The computations showed that electron rich and electron poor substituents result the same effects on the electronic excitation spectra. These substituent effects are additive, but the steric orientation of the substituents has to be taken into account. Chapter 7 describes a computer aided design of new alkoxyl radical precursors. Combining the advantages of both compounds the radical formation should be initiated by an irradiation with light at about 350 nm, and the amount of side products during the radical formation process should be small. To achieve this 18 test candidates were obtained by a systematic variation of the parent compound of the thiazolethione precursor. To identify the promising new precursor systems a screening of the lower electronic excitations of all resulting 18 systems was performed with TD-DFT. For promising systems the N,O or P,O dissociation paths, respectively, were analyzed according to the developed model. N-(methoxy)-azaphospholethione and N-(methoxy)-pyrrolethione seem to be the most promising candidates. The computations predict a strong absorption at about 350 nm respectively 320 nm. Due to the amounts of maximal excess energy and the shapes of the potential surfaces of the N,O bond dissociation paths their reactivity should resemble more the behavior of the pyridinethiones.}, language = {en} } @phdthesis{Bach2007, author = {Bach, Patricia}, title = {Immunogenicity of antigen-displaying virus-like particles and their use as a potential vaccine against prion diseases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25889}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Transmissible spongiform encephalopathies (TSEs) or prion diseases are a group of infectious neurodegenerative diseases that are associated with misfolding of the cellular form of the cellular prion protein (PrPC) into a disease associated conformer (PrPSc). No therapy for prion diseases is available at present. So far, anti-PrPC vaccination is hampered by immunological tolerance of the mammalian immune system to endogenous PrPC. The aim of this thesis was to set up a new vaccination strategy based on virus-like particles (VLP) to induce anti-PrPC antibody responses in PrPC-competent mice. In a first step it was assessed whether VLP have the capacity to induce antibody responses that are protective against conventional pathogens. For this purpose, VLP displaying the vesicular stomatitis virus-gylcoprotein (VLP-VSV) were generated and tested for their immunogenicity. Similarly to live vesicular stomatitis virus (VSV), replication deficient VLP-VSV induced T help-independent VSV neutralizing IgM responses that switched to the IgG subclass in a T help-dependent manner. Furthermore, type I IFN receptor (IFNAR) triggering only marginally affected VLP-VSV induced neutralizing IgM responses, whereas it was critically required to promote the IgG switch. The analysis of conditional knockout mice with a lymphocyte-specific IFNAR deletion revealed that IFNAR triggering of lymphocytes did not play a crucial role, neither upon VLP-VSV nor VSV immunization. Collectively, these data verified the high immunogenicity of VLP. Therefore, in a next step VLP were generated displaying the C-terminal half of PrP (residues 121-231aa) fused to the platelet derived growth factor receptor (PDGFR) transmembrane region (VLP-PrPD111) for anti-PrPC immunization. On the surface of such retroparticles, PrPC was expressed at high levels as determined by electron microscopy. VLP-PrPD111 immunization of Prnp-deficient (Prnp0/0) mice resulted in antibody response specifically binding the cellular form of PrPC. Upon intravenous injection of wild-type mice, high PrPC-specific IgM responses were induced, whereas the T cell-dependent switch from the IgM to the IgG subclass was less pronounced. As a consequence, anti-PrPC titers were rather short-lived. The impaired subclass switch was probably related with host T cell tolerance to endogenous PrPC. Attempts to increase anti-PrPC IgG responses in wild-type mice via administration of VLP-PrPD111 emulsified in various different adjuvants failed. Nevertheless, in single individuals low IgG antibodies were induced after immunization of VLP-PrPD111 emulsified in CFA. To circumvent T cell tolerance in wild-type mice, a multitude of different immunization strategies was tested, including priming and boosting protocols with different types of VLP or VLP expressing PrPC together with foreign T helper epitopes. Overall, those efforts did not improve anti-PrPC IgG responses in wild-type mice. Interestingly, anti-PrPC antibodies induced in Prnp0/0 mice reduced PrPSc levels in prion infected cell cultures, whereas serum of vaccinated wild-type mice did not. To assess the protective capacity of VLP-PrPD111 induced immune responses, vaccinated wild-type mice were infected with scrapie (RML 5.0). Unfortunately, vaccinated mice did not show a significant delay in the onset of scrapie. In a last part of the thesis it was studied whether in the absence of T cell help activated "memory" B cells were able to produce anti-PrPC specific antibodies. To address this question, PrPC-specific memory B cells were sorted from vaccinated Prnp0/0 mice and adoptively transferred into wild-type recipient mice. Upon VLP-PrPD111 challenge, no PrPC-specific IgG titers were induced in the recipients. Nevertheless, several VLP-PrPD111 challenged recipient mice were protected against scrapie infection. In conclusion, VLP were characterized as highly immunogenic vaccines that were used to elucidate various questions concerning adaptive immune response and basic mechanisms of PrPC-specific tolerance vs. immunity. Remarkably, VLP-PrPD111 was able to induce native PrPC-specific antibodies in wild-type mice but major difficulties associated with PrPC-specific tolerance made efficacious scrapie vaccination impossible. New vaccination approaches are being tested to overcome these limitations.}, subject = {Prion}, language = {en} } @phdthesis{Benz2007, author = {Benz, Peter Michael}, title = {Cytoskeleton assembly at endothelial cell-cell contacts is regulated by Alpha-II-spectrin/vasp complexes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23802}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Directed cortical actin assembly is the driving force for intercellular adhesion. Vasodilator-stimulated phosphoprotein (VASP) participates in actin-fiber formation and VASP activity is regulated by phosphorylations. We screened for endothelial cell proteins, which bind to VASP dependent on its phosphorylation status. Differential proteomics identified \&\#945;II-spectrin as novel VASP-interacting protein. \&\#945;II-spectrin binds to the triple GP5-motif in VASP via its SH3 domain. cAMP-dependent protein kinase-mediated VASP phosphorylation at Ser157 inhibits \&\#945;II-spectrin/VASP complex formation. VASP becomes dephosphorylated upon formation of cell-cell contacts and in confluent but not in sparse endothelial cells \&\#945;II-spectrin colocalizes with non-phosphorylated VASP at cell-cell junctions. Ectopic expression of the \&\#945;II-spectrin SH3 domain fused to claudin-5 translocates VASP to cell-cell contacts and is sufficient to initiate the formation of cortical actin cytoskeletons. \&\#945;II-spectrin SH3 domain overexpression stabilizes cell-cell contacts and decreases endothelial permeability. Conversely, permeability of VASP-deficient endothelial cells is elevated. In a skin edema model, microvascular leakage is increased in VASP-deficient over wild-type mice. We propose that \&\#945;II-spectrin/VASP complexes regulate cortical actin cytoskeleton assembly with implications for formation of endothelial cell-cell contacts and regulation of vascular permeability.}, language = {en} } @phdthesis{Berner2007, author = {Berner, Michael P.}, title = {Sensory and motor components of highly skilled action sequences}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23324}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {A series of experiments was conducted in order to investigate motor contributions to learning highly skilled action sequences in contrast to sensory contributions. Experiments 1-4 made use of a bimanual-bisequential variant of the serial reaction time task: Presentation of imperative stimuli was arranged such that participants' left-hand and right-hand responses followed different sequences independently of one another, thus establishing a compound sequence spanning both hands. At least partly independent learning of the two concurrently implemented hand-related sequences was demonstrated after extensive practice under condi-tions of both simultaneous (Experiments 1 \& 2) and alternating (Experiments 3 \& 4) stimulus presentation and responding. It persisted when there was only one imperative stimulus for presenting both hand-related sequences (Experiments 2-4) instead of two separate imperative stimuli (Experiments 1 \& 2), one for each sequence, even when the hand-related sequences were correlated and massive integrated learning of the compound sequence occurred (Ex-periment 4). As for the nature of the independently acquired sequence representations, trans-ferable sequence knowledge was acquired only when there was a separate imperative stimulus for each sequence (Experiments 1 \& 2) but not otherwise (Experiments 2-4). The most likely stimulus-based representations which allow for intermanual transfer can be regarded as sen-sory components of highly skilled action sequences, whereas motor components can be con-sidered as being reflected in effector-specific, non-transferable sequence knowledge. The same decomposition logic applies to transferable and non-transferable sequence knowledge observed under conditions of unimanual practice of a single sequence (Experiments 6 \& 7). The advantage of practicing a key press sequence with fingers of one hand as opposed to practicing it with fingers of both hands (Experiment 5) also implicates a motor component as the two assignments were equivalent in all other respects. Moreover, Experiments 6 and 7 showed that hand-specific sequence knowledge can develop after relatively little practice (as little as approximately 120 sequence repetitions). Presumably, this occurs especially in tasks with particularly pronounced requirements for coarticulation between consecutive finger movements. In sum, the present series of experiments provides compelling evidence for an effector-specific component of sequence learning. Albeit relatively small in size, it emerged consistently under various conditions. By contributing to the refinement of sequential action execution it can play a role in attaining high levels of performance.}, language = {en} } @phdthesis{Binzenhoefer2007, author = {Binzenh{\"o}fer, Andreas}, title = {Performance Analysis of Structured Overlay Networks}, doi = {10.25972/OPUS-2250}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26291}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Overlay networks establish logical connections between users on top of the physical network. While randomly connected overlay networks provide only a best effort service, a new generation of structured overlay systems based on Distributed Hash Tables (DHTs) was proposed by the research community. However, there is still a lack of understanding the performance of such DHTs. Additionally, those architectures are highly distributed and therefore appear as a black box to the operator. Yet an operator does not want to lose control over his system and needs to be able to continuously observe and examine its current state at runtime. This work addresses both problems and shows how the solutions can be combined into a more self-organizing overlay concept. At first, we evaluate the performance of structured overlay networks under different aspects and thereby illuminate in how far such architectures are able to support carrier-grade applications. Secondly, to enable operators to monitor and understand their deployed system in more detail, we introduce both active as well as passive methods to gather information about the current state of the overlay network.}, subject = {Overlay-Netz}, language = {en} } @phdthesis{Blenk2007, author = {Blenk, Steffen}, title = {Bioinformatical analysis of B-cell lymphomas}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-27421}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Background: The frequency of the most observed cancer, Non Hodgkin Lymphoma (NHL), is further rising. Diffuse large B-cell lymphoma (DLBCL) is the most common of the NHLs. There are two subgroups of DLBCL with different gene expression patterns: ABC ("Activated B-like DLBCL") and GCB ("Germinal Center B-like DLBCL"). Without therapy the patients often die within a few months, the ABC type exhibits the more aggressive behaviour. A further B-cell lymphoma is the Mantle cell lymphoma (MCL). It is rare and shows very poor prognosis. There is no cure yet. Methods: In this project these B-cell lymphomas were examined with methods from bioinformatics, to find new characteristics or undiscovered events on the molecular level. This would improve understanding and therapy of lymphomas. For this purpose we used survival, gene expression and comparative genomic hybridization (CGH) data. In some clinical studies, you get large data sets, from which one can reveal yet unknown trends. Results (MCL): The published proliferation signature correlates directly with survival. Exploratory analyses of gene expression and CGH data of MCL samples (n=71) revealed a valid grouping according to the median of the proliferation signature values. The second axis of correspondence analysis distinguishes between good and bad prognosis. Statistical testing (moderate t-test, Wilcoxon rank-sum test) showed differences in the cell cycle and delivered a network of kinases, which are responsible for the difference between good and bad prognosis. A set of seven genes (CENPE, CDC20, HPRT1, CDC2, BIRC5, ASPM, IGF2BP3) predicted, similarly well, survival patterns as proliferation signature with 20 genes. Furthermore, some bands could be associated with prognosis in the explorative analysis (chromosome 9: 9p24, 9p23, 9p22, 9p21, 9q33 and 9q34). Results (DLBCL): New normalization of gene expression data of DLBCL patients revealed better separation of risk groups by the 2002 published signature based predictor. We could achieve, similarly well, a separation with six genes. Exploratory analysis of gene expression data could confirm the subgroups ABC and GCB. We recognized a clear difference in early and late cell cycle stages of cell cycle genes, which can separate ABC and GCB. Classical lymphoma and best separating genes form a network, which can classify and explain the ABC and GCB groups. Together with gene sets which identify ABC and GCB we get a network, which can classify and explain the ABC and GCB groups (ASB13, BCL2, BCL6, BCL7A, CCND2, COL3A1, CTGF, FN1, FOXP1, IGHM, IRF4, LMO2, LRMP, MAPK10, MME, MYBL1, NEIL1 and SH3BP5; Altogether these findings are useful for diagnosis, prognosis and therapy (cytostatic drugs).}, subject = {Bioinformatik}, language = {en} } @phdthesis{Bockmeyer2007, author = {Bockmeyer, Matthias}, title = {Structure and Densification of Thin Films Prepared From Soluble Precursor Powders by Sol-Gel Processing}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24577}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The main focus of this work was to get a deeper understanding of the relationship between the structure of sol-gel films, their densification and their macroscopic cracking. First of all titania was chosen as model system. Therefore a synthesis route starting from the preparation of long-term stable amorphous redissoluble precursor powders based on acetylacetone as chelate ligand was utilized. The solubility and stability of the powders in various solvents can be determined by chemical synthesis and technological parameters. When dissolved in a solvent mixture of ethanol and 1,5-pentanediol, thin films can be easily prepared by dip-coating technique. Thereby the quality of the titania films enormously depends on the calcinations temperature and the solvent mixture is used. In order to investigate the influence of different solvents and solvent mixtures on the microstructure and densification of the precursors, the coating solutions were stripped off (sol powder) and analyzed as function of annealing temperature. It was pointed out that a high densification rate caused by the addition of 1,5-pentanediol, results in dense microstructure with trapped residual carbon. These impurities can retard the phase transformation of anatase to rutile. The analysis of so-called "film powders" scraped off multiple dip-coated substrates provides valuable information on the effect of air moisture and unidirectional densification during drying and aging on the structure of thin films. The high surface-to-volume ratio and access to air moisture determine the chemical composition of the as-prepared film, which controls shrinkage, crystallization and defect structure of the coatings. Further it was shown, that drying as a thin film results in the formation of closed pores and much denser microstructure than the respective sol powder. Without the addition of 1,5-pentanediol all -OEt moieties undergo hydrolysis reactions, which causes the formation of a rigid network. The presence of 1,5-pentanediol retards this hydrolysis reactions and provides some network plasticity. Generally the microstructure of thin films is comparatively close to the microstructure of the film powders. The addition of 1,5-pentandiol prevents hydrolysis and condensation reactions as like in the film powders. However even at 700 °C, thin films never transform to rutile, which was attributed to the tensile stresses in thin films. In thin films and in film powders as well a comparable amount of closed pores are formed during annealing. Further it was shown that most of the thin sol-gel films investigated form a dense crust on their tops during annealing. This explains why crack free films exhibit only closed pores. However, when cracks appear during thin film shrinkage in the coating, this crust is burst, which generates open porosity. The defect density in the coatings was determined by an automated analysis of surface images. The crack formation and quantity can be directly referred to tensile stresses in the coatings, which arise from hydrolysis and condensation during thin film drying and aging. Therefore when 1,5-pentanediol is added to the sol, thin film cracking was avoided, because hydrolysis and condensation reactions are retarded, which preserves a higher network flexibility. Furthermore the crack formation was significantly influenced by the atmospheric humidity that was used during the coating process, which was explained by different drying and condensation rates. Under certain chemical starting conditions water soluble precursor powders can be also obtained. In general the observations made with the water based coating solutions are mostly in agreement with the former results based on ethanol based coating solutions. For example the high surface-to-volume ratio of film powders compared to sol powders also significantly enhances film drying and densification. The addition of 1,5-pentanediol also clearly contributes to their densification behavior and phase evolution. As seen before in the case of ethanol based coatings, 1,5-pentanediol enhances the stability towards hydrolysis and condensation reactions and preserves some network plasticity. Therefore coatings prepared without the addition of 1,5-pentanediol already form cracks during film drying and aging because of tensile stresses. Thus, the addition of 1,5-pentanediol results in a reduction/prevention of crack formation. Nevertheless some differences were observed, i.e. the critical single coating film thickness of ethanol based coatings is nearly twice that of water based coatings. This was explained by the different surface tensions of the basis solvents, which during thin film drying causes significantly higher capillary forces and tensile stresses in water based coatings. When acetylacetone is replaced by triethanolamine as chelating ligand for titanium also re-dissolvable precursor powders can be synthesized. The film powders combine a high hydrolytic stability of the precursor with sufficient intermediate network flexibility. The different type of organics changes the drying and densification behavior: i.e. in contrast to film powders obtained from acetylacetone based precursor powders the structure of triethanolamine based film powders is unaffected by the thin film drying process. This high hydrolytic stability and plasticity of this precursor allows the preparation of defect free coatings up to single film thickness of 300 nm. However triethanolamine based thin films present at intermediary annealing temperatures a distinctively different microstructure compared to acetylacetone based films. The general validity of the conclusions was proved on the basis of zirconia coatings that were also prepared by the use of re-dissolvable precursor powders. In principle all conclusions concerning the interconnection of precursor chemistry, film formation, densification and structure were transferable to the respective zirconia coatings. Differences mainly arise only from differential material properties i.e. bulk density. Finally, it has been pointed out that the findings obtained on the densification behavior of thinsol-gel films are also a valuable tool for improved explanations of other important scientific questions concerning sol-gel films, i.e. scratch resistance of sol-gel coatings, fiber -bridging and - degradation of sol-gel coated fibers.}, subject = {Sol-Gel-Verfahren}, language = {en} } @phdthesis{Brink2007, author = {Brink, Andreas}, title = {The biological significance of chemically-induced DNA adducts in relation to background DNA damage}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23850}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {No abstract available}, subject = {DNS-Sch{\"a}digung}, language = {en} } @phdthesis{Bruenger2007, author = {Br{\"u}nger, Christian}, title = {Numerical Studies of Quantum Spin Systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26439}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Der erste Teil der Arbeit widmet sich der Untersuchung des Bilayer-Heisenberg-Modells und des zweidimensionalen Kondo-Necklace-Modells. Beide Modelle weisen einen Quantenphasen{\"u}bergang zwischen einer geordneten und einer ungeordneten Phase auf. In dieser Arbeit richtet sich das Interesse insbesondere auf die Kopplung der kritischen Fluktuationen an ein in das System eingebundenes Loch. Mittels eines selbstkonsistenten Born'schen N{\"a}herungsverfahrens wird gezeigt, dass das Loch mit den Magnonen derart wechselwirkt, dass dessen Quasiteilchengewicht am quantenkritischen Punkt verschwindet. Um diesen Aspekt weiter zu untersuchen, wird das Verhalten des Quasiteilchengewichts im Bereich der kritischen Kopplung auch mit Quanten-Monte-Carlo-Methoden analysiert. Desweiteren werden die dynamischen Eigenschaften des Loches im magnetischen Hintergrund untersucht. Im zweiten Teil dieser Arbeit gilt das Interesse der Untersuchung des Spiral-Staircase-Heisenberg-Modells. Dieses besteht aus zwei, zu einer Spinleiter ferromagnetisch gekopplten Spin-1/2-Ketten, wobei die antiferromagnetische Kopplung innerhalb der zweiten Kette durch Windung der Leiter variiert werden kann. Dieses Model eignet sich, den {\"U}bergang zwischen einer Spin-1/2-Kette ohne Spinl{\"u}cke und einer Spin-1-Kette mit Spinl{\"u}cke zu studieren. Besondere Beachtung ist dem {\"O}ffnen der Spinl{\"u}cke in Abh{\"a}ngigkeit der ferromagnetischen Kopplung zwischen den Leiterbeinen geboten. Es stellt sich heraus, dass das System, abh{\"a}ngig von der Leiterwindung, wesentliche Unterschiede im Skalierungsverhalten der Spinl{\"u}cke aufweist. Desweiteren wird mittels der String-Order-Parameter gezeigt, dass das Spiral-Staircase-Heisenberg-Modell trotz des unterschiedlichen Skalierungsverhaltens der Spinl{\"u}cke und unabh{\"a}ngig von der Wahl der Parameter sich stets in der Haldane-Phase befindet. Die Analyse der Modelle bedient sich haupts{\"a}chlich Quanten-Monte-Carlo-Methoden, aber auch exakter Diagonalisierungstechniken, sowie auf Molekularfeldn{\"a}herungen gest{\"u}tzten Rechnungen.}, subject = {Spinsystem}, language = {en} } @phdthesis{Chen2007, author = {Chen, Wen}, title = {Functional Role of NFATc1 in the Control of Life and Death of Lymphocytes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26675}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {In this study, murine ES cells and DT40 B cells were used in parallel to disrupt the Nfatc1 gene and to study the function of individual 6 Nfatc1 isoforms, especially the function of highly inducible NFATc1/aA.We found that the short isoform NFATc1/aA protects DT40 B cells against apoptosis while the long isoform NFATc1/aC appears to enforce apoptosis. DNA microarray studies have shown that in NFATc1" DT40 B cells expressing ectopically human NFATc1/aA, the pkc-theta gene is several fold stronger expressed as in wild type cells. Our results of EMSA (Electrophoretic Mobility Shift Assays) and ChIP (chromatin immuno-precipitation) experiments demonstrated the binding of NFATc1/aA to the pkc-theta promoter in vitro and in vivo. NF-kappa B was also found to bind to the NFATc1 P1-promoter in vitro and in vivo. These data suggest and further prove that NF-kappa B contributes to the induction of the NFATc1 P1 promoter upon activation of T cells. So, NFATc1/aA and NF-kappa B were found to cross-talk in the transcriptional upregulation of their target genes, such as the IL-2 gene and the Nfatc1 gene itself, at multiple steps upon induction of apoptosis. While the pro-apoptotic mechanism of NFATc1s long isoform(s) remains unclear, its corresponding "death partners" are worth further studies. The elucidation of functional roles of NFATc1s short or long isoforms in the control of apoptosis of lymphocytes helps to understand apoptosis regulation, and thereby, the fate of lymphocytes.}, subject = {Lymphozyten}, language = {en} } @phdthesis{Colditz2007, author = {Colditz, Rene Roland}, title = {Time Series Generation and Classification of MODIS Data for Land Cover Mapping}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25908}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Processes of the Earth's surface occur at different scales of time and intensity. Climate in particular determines the activity and seasonal development of vegetation. These dynamics are predominantly driven by temperature in the humid mid-latitudes and by the availability of water in semi-arid regions. Human activities are a modifying parameter for many ecosystems and can become the prime force in well-developed regions with an intensively managed environment. Accounting for these dynamics, i.e. seasonal dynamics of ecosystems and short- to long-term changes in land-cover composition, requires multiple measurements in time. With respect to the characterization of the Earth surface and its transformation due to global warming and human-induced global change, there is a need for appropriate data and methods to determine the activity of vegetation and the change of land cover. Space-borne remote sensing is capable of monitoring the activity and development of vegetation as well as changes of the land surface. In many instances, satellite images are the only means to comprehensively assess the surface characteristics of large areas. A high temporal frequency of image acquisition, forming a time series of satellite data, can be employed for mapping the development of vegetation in space and time. Time series allow for detecting and assessing changes and multi-year transformation processes of high and low intensity, or even abrupt events such as fire and flooding. The operational processing of satellite data and automated information-extraction techniques are the basis for consistent and continuous long-term product generation. This provides the potential for directly using remote-sensing data and products for analyzing the land surface in relation to global warming and global change, including deforestation and land transformation. This study aims at the development of an advanced approach to time-series generation using data-quality indicators. A second goal focuses on the application of time series for automated land-cover classification and update, using fractional cover estimates to accommodate for the comparatively coarse spatial resolution. Requirements of this study are the robustness and high accuracy of the approaches as well as the full transferability to other regions and datasets. In this respect, the developments of this study form a methodological framework, which can be filled with appropriate modules for a specific sensor and application. In order to attain the first goal, time-series compilation, a stand-alone software application called TiSeG (Time Series Generator) has been developed. TiSeG evaluates the pixel-level quality indicators provided with each MODIS land product. It computes two important data-availability indicators, the number of invalid pixels and the maximum gap length. Both indices are visualized in time and space, indicating the feasibility of temporal interpolation. The level of desired data quality can be modified spatially and temporally to account for distinct environments in a larger study area and for seasonal differences. Pixels regarded as invalid are either masked or interpolated with spatial or temporal techniques.}, subject = {Zeitreihe}, language = {en} } @unpublished{Dandekar2007, author = {Dandekar, Thomas}, title = {Some general system properties of a living observer and the environment he explores}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33537}, year = {2007}, abstract = {In a nice assay published in Nature in 1993 the physicist Richard God III started from a human observer and made a number of witty conclusions about our future prospects giving estimates for the existence of the Berlin Wall, the human race and all the rest of the universe. In the same spirit, we derive implications for "the meaning of life, the universe and all the rest" from few principles. Adams´ absurd answer "42" tells the lesson "garbage in / garbage out" - or suggests that the question is non calculable. We show that experience of "meaning" and to decide fundamental questions which can not be decided by formal systems imply central properties of life: Ever higher levels of internal representation of the world and an escalating tendency to become more complex. An observer, "collecting observations" and three measures for complexity are examined. A theory on living systems is derived focussing on their internal representation of information. Living systems are more complex than Kolmogorov complexity ("life is NOT simple") and overcome decision limits (G{\"o}del theorem) for formal systems as illustrated for cell cycle. Only a world with very fine tuned environments allows life. Such a world is itself rather complex and hence excessive large in its space of different states - a living observer has thus a high probability to reside in a complex and fine tuned universe.}, subject = {Komplex }, language = {en} } @phdthesis{Faber2007, author = {Faber, Johan Henrik}, title = {Naphthylisoquinoline Alkaloids : Structural Elucidation, Metabolism and Functional Analysis of their Bioactivities}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22789}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {This thesis deals with the isolation and structural elucidation of bioactive naphthylisoquinoline alkaloids and related analogs. The mode of action of the antiplasmodial activity exhibited by the naphthylisoquinoline alkaloids was explored and compared to that of the antimalarial drug chloroquine. Furthermore, the phase 1 and 2 metabolism of dioncophyllines A and C and dioncopeltine A were investigated. In detail the following results have been obtained: • From the leaves of the recently discovered East African liana A. tanzaniensis six naphthylisoquinoline alkaloids were isolated. • The leaves of a botanical yet undescribed Ancistrocladus species, collected by Prof. Dr. V. Mudogo in the Democratic Republic of Congo in the habitat Yeteto near the town Ikela, were analyzed for naphthylisoquinoline alkaloids for the first time. The isolation work led to the first identification of an N,C-coupled naphthyldihydroisoquinoline alkaloid; ancistrocladinium B. Phytochemical investigation of the roots of the Congolese Ancistrocladus species (habitat Yeteto), , afforded five new derivatives of known naphthylisoquinoline alkaloids, namely 5'-O-demethylhamatine, 5'-O-demethylhamatinine, 6-O-demethylancistroealaine A, 6,5'-O,O-didemethylancistroealaine A, and 5-epi-6-O-methylancistrobertsonine A, along with six known naphthylisoquinoline alkaloids. • The antiplasmodial activity guided purification of 60Co irradiated samples containing commercially available naphthylisoquinoline related substances, afforded the isolation of the irradiation products 3,4-dihydro-1-isoquinolinone, 3,4-dihydro-1-isoquinolineamine, and 1,2,3,4-tetrahydro-1,2-diazirino-isoquinoline. The compounds were found to be more active than the starting material, although only exhibiting weak antiplasmodial activity against P. falciparum. • The effect on the absorption spectrum of FPIX due to complex formation with the naphthylisoquinoline alkaloids dioncophyllines A and C, dioncopeltine A korupensamine A, and ancistrocladine was examined by a titration study. Job's plot analyses by UV-spectroscopy determined the stoichiometry for the complex formation of FPIX and naphthylisoquinoline alkaloids to be 2:1. Furthermore, the dissociation constants for the complexation with FPIX were determined for each of the naphthylisoquinoline alkaloids investigated. Dioncophylline C and dioncopeltine A were found to possess dissociation constants, which are comparable to the one reported for the antimalarial drug chloroquine. The ability of ESI to transfer noncovalent solution-phase assemblies intact into the gas phase, was conducted on solution mixtures of naphthylisoquinoline alkaloid and FPIX, as well as on mixtures of chloroquine and FPIX. The mass spectrometry analyses revealed several peaks, which corresponded to the complex formation of FPIX to the respective ligands investigated. The most interesting results obtained were the detection of peaks corresponding to the complex formation between a chelated dimer of FPIX and dioncophylline Cand of peaks corresponding to a double protonated tetramer of FPIX - consisting of two chelated \&\#61549;-oxo dimers of FPIX - in complex formation with two molecules of chloroquine. • Two phase 1 metabolism products of dioncophylline A were identified. Coelution in combination with HPLC-MS/MS, NMR, and CD investigations assigned the major metabolic product as 5'-O-demethyldioncophylline A. The minor metabolic product was only present in small amounts, which disabled an unambiguous structural characterization of the compound. However, as deduced from the mass spectrometry analyses and exclusion of a possible metabolic oxidation product by coelution with authentic reference material, the metabolite should possess a 4-hydroxylated isoquinoline portion and is assumed to be represented by structure. Dioncophylline C and dioncopeltine A were found to be stable to phase 1 metabolism reactions caused by rat liver microsomes.}, subject = {Naphthylisochinolinalkaloide}, language = {en} } @phdthesis{Gromova2007, author = {Gromova, Kira V.}, title = {Visualization of the Smad direct signaling response to Bone Morphogenetic Protein 4 activation with FRET-based biosensors}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25855}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The Transforming Growth Factor (TGF) superfamily of cytokines and their serine/threonine kinase receptors play an important role in the regulation of cell division, differentiation, adhesion, migration, organization, and death. Smad proteins are the major intracellular signal transducers for the TGF receptor superfamily that mediate the signal from the membrane into the nucleus. Bone Morphogenetic Protein-4 (BMP-4) is a representative of the TGF superfamily, which regulates the formation of teeth, limbs and bone, and also plays a role in fracture repair. Binding of BMP-4 to its receptor stimulates phosphorylation of Smad1, which subsequently recruits Smad4. A hetero-oligomeric complex consisting of Smad1 and Smad4 then translocates into the nucleus and regulates transcription of target genes by interacting with transcription factors. Although the individual steps of the signaling cascade from the receptor to the nucleus have been identified, the exact kinetics and the rate limiting step(s) have remained elusive. Standard biochemical techniques are not suitable for resolving these issues, as they do not offer sufficiently high sensitivity and temporal resolution. In this study, advanced optical techniques were used for direct visualization of Smad signaling in live mammalian cells. Novel fluorescent biosensors were developed by fusing cyan and yellow fluorescent proteins to the signaling molecules Smad1 and Smad4. By measuring Fluorescence Resonance Energy Transfer (FRET) between the two fluorescent proteins, the kinetics of BMP/Smad signaling was unraveled. A rate-limiting delay of 2 - 5 minutes occurred between BMP receptor stimulation and Smad1 activation. A similar delay was observed in the complex formation between Smad1 and Smad4. Further experimentation indicated that the delay is dependent on the Mad homology 1 (MH1) domain of Smad1. These results give new insights into the dynamics of the BMP receptor - Smad1/4 signaling process and provide a new tool for studying Smads and for testing inhibitory drugs.}, subject = {FRET}, language = {en} } @phdthesis{Gupta2007, author = {Gupta, Kapuganti Jagadis}, title = {Nitric oxide in plants: Investigation of synthesispathways and role in defense against avirulent Pseudomonas}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25545}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Die Zahl der physiologischen Prozesse in Pflanzen, die scheinbar durch NO reguliert werden, hat in den letzten Jahren stark zugenommen. NO {\"u}bernimmt wichtige Rollen f{\"u}r die Steuerung von Wachstum und Entwicklung, f{\"u}r die Pathogenresistenz und bei abiotischem Stress, sowohl in unterirdischen als auch in oberirdischen Organen. In Pflanzen wurden bisher eine Reihe verschiedener enzymatischer und einige wenige nichtenzymatische Synthesewege f{\"u}r NO vorgeschlagen. Das Hauptziel dieser Arbeit bestand nun darin, die NO Produktion von Pflanzen und speziell von Wurzeln m{\"o}glichst quantitativ zu erfassen und die beteiligten Enzyme zu identifizieren. Dieses Ziel sollte vor allem durch Chemilumineszenz-Messung von NO in der Gasphase (= direkte Chemilumineszenz) erreicht werden, aber auch durch die indirekte Chemilumineszenz, bei welcher Spuren von NO-Oxidationsprodukten wie Nitrat und Nitrit erfasst werden. Als Versuchspflanzen wurden verwendet: Wildtypen von Nicotiana tabacum cv. Xanthi oder cv. Gatersleben; Nitratreduktase-freie, auf Ammonium-N angezogene Mutanten, die keine Nitratreduktase (NR) induzieren; WT Pflanzen, die auf Wolframat angezogen wurden um die Synthese funktionaler MoCo-Enzyme zu unterbinden; eine NO-{\"u}berproduzierende, Nitritreduktase (NiR)-freie Transformante, sowie gelegentlich Gerste, Reis und Erbsen. Eine hypersensitive Reaktion (HR) von Tabak wurde erzeugt durch Druckinfiltration von avirulenten Bakterien des Stammes Pseudomonas syringae pv. phaseolicola. Bei Sauerstoffkonzentrationen \&\#8804;1\% wurde exogenes Nitrit auch von v{\"o}llig NR-freien Wurzeln zu NO reduziert. Folglich war NR nicht die einzige NO-Quelle von Wurzeln. Im Gegensatz dazu waren NR-freie Blattstreifen nicht in der Lage, Nitrit zu NO umzusetzen. Die NO-Bildung von Wurzeln wurde außerdem durch Hemmstoffe des mitochondrialen Elektronentransportes, Myxothiazol und Salicylhydroxams{\"a}ure (SHAM) gehemmt, w{\"a}hrend die NO-Produktion von NR-exprimierenden Blattstreifen gegen diese Inhibitoren unempfindlich war. Damit stimmte auch {\"u}berein, dass gereinigte Mitochondrien aus Wurzeln, aber nicht die aus Bl{\"a}ttern Nitrit mit Hilfe von NADH zu NO reduzieren konnten. Die Inhibitor-Wirkung l{\"a}sst darauf schließen, dass in Wurzelmitochondrien beide terminalen Oxidasen and der NO-Bildung beteiligt sind, und dass selbst in NR-haltigen Wurzeln ein großer Teil der Reduktion von Nitrit zu NO durch die Mitochondrien bewerkstelligt wird, und weniger durch NR selbst. Die Unterschiedliche F{\"a}higkeit von Blatt-und Wurzelmitochondrien zur anaeroben Nitrit:NO-Reduktion wurde nicht nur bei Tabak, sondern auch bei Arabidopsis, Gerste und Erbse gefunden. Sie scheint also eine generelle Eigenschaft h{\"o}herer Pflanzen zu sein. Die Nitrit:NO Reduktion wurden auch direkt als Nitrit- bzw. NADH-Verbrauch gemessen. Die Reaktion war außerdem exklusiv mit der Membranfraktion der Mitochondrien assoziert, ohne jede Beteiligung von Matrixkomponenten. Es wurde auch gepr{\"u}ft, ob Wurzelmitochondrien und- gereinigte Membranen NO ausschließlich aus Nitrit produzierten, oder eventuell auch {\"u}ber eine NO-Synthase (NOS). Außerdem wurde untersucht, ob und in welchem Umfang die NO-Messungen durch eine NO-Oxidation verf{\"a}lscht werden konnten. Zus{\"a}tzlich zur Chemilumineszenz wurden Fluoreszenzmessungen mit Diaminofluoreszeinen (DAF) zum Vergleich herangezogen. In Luft produzierten Mitochondrien ja kein Nitrit-abh{\"a}ngiges NO, und eine NOS-Aktivit{\"a}t konnte weder durch direkte noch durch indirekte Chemilumineszenz nachgewiesen werden. Mit DAF-2 oder DAR-4M wurde jedoch eine L-Arginin-abh{\"a}ngige Fluoreszenzerh{\"o}hung beobachtet. Diese scheinbare NOS-Aktivit{\"a}t wurde mit kommerzieller iNOS verglichen und zeigte dabei sehr untypische Antworten auf NOS-Inhibitoren, Substrate und Kofaktoren. Sie wird deshalb als Artefakt beurteilt. Bei Verwendung von iNOS wurden ca. 2/3 des insgesamt produzierten NO zu (Nitrit+Nitrat) oxidiert. Mitochondrien scheinen NO zu verbrauchen, ohne jedoch die Oxidation von NO zu (Nitrit+Nitrat) zu erh{\"o}hen. Vermutlich wird dabei ein fl{\"u}chtiges Intermediat gebildet (eventuell N2O3). In unserer Gruppe wurde k{\"u}rzlich gezeigt, dass der pilzliche Elicitor Cryptogein eine hypersensitive Reaktion (HR) bei Tabak hervorrief, die v{\"o}llig unabh{\"a}ngig von der Gegenwart oder Abwesenheit von NR war. Eine Schlussfolgerung daraus war, dass die NR-abh{\"a}ngige NO-Bildung f{\"u}r die HR keine Rolle spielte. Hier pr{\"a}sentieren wir Hinweise darauf, dass dieses Szenario Cryptogein-spezifisch sein k{\"o}nnte. Pseudomonas syringae pv phaseolicola wurde in Tabakbl{\"a}tter des Wildtyps und derNiR-defizienten, NO-{\"u}berproduzierenden Mutante (clone 271) infiltriert, die entweder auf Ammonium oder auf Nitrat angezogen waren. Es wurde die Entwicklung der L{\"a}sionen, das Bakterienwachstum und die Zuckerkonzentrationen in den Bl{\"a}ttern und im Blattapoplasten verfolgt. Die L{\"a}sionen-Entwicklung war positiv, und das Bakterienwachstum negativ korreliert mit der Nitrat-Ern{\"a}hrung und einer eventuellen NO-Produktion. Das Bakterienwachstum war positiv korreliert mit einer Ammonium-Ern{\"a}hrung und mit apoplastischen Zuckerkonzentrationen. Der Gesamtgehalt an freier + konjugierter Salicyls{\"a}ure (SA) war durch bakterielle Infektion immer drastisch gesteigert, aber ohne klare Korrelation mit einer NO-Produktion. In Gegenwart von Cryptogein war das Wachstum von Pseudomonas fast v{\"o}llig gehemmt. Diese Beobachtungen deuten darauf hin, dass die vermutete gegenseitige Abh{\"a}ngigkeit von Bakterienwachstum, NO-Produktion und der HR sehr komplex ist und nicht auf einfache unifaktorielle Beziehungen reduziert werden kann.}, subject = {Pflanzen}, language = {en} } @phdthesis{Hallhuber2007, author = {Hallhuber, Matthias}, title = {Inhibition of Nuclear Import of Calcineurin Prevents the Development of Myocardial Hypertrophy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23536}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The Calcineurin/NFAT signaling cascade is a crucial transducer of cellular function. It has recently been emerged that in addition to the transcription factor NFAT, the phosphatase Calcineurin is also translocated to the nucleus. Our traditional understanding of Calcineurin activation via sustained high Ca2+-levels was also advanced by recent findings from this working group (AG Ritter), which showed that Calcineurin is activated by proteolysis of the C-terminal autoinhibitory domain. This leads to the constitutive activation and nuclear translocation of Calcineurin. Therefore, Calcineurin is not only responsible for dephosphorylating of NFAT in the cytosol thus enabling its nuclear import, its presence in the nucleus is also significant in ensuring the full transcriptional activity of NFAT. Formation of complexes between transcription factors and DNA regulates the transcriptional process. Therefore, the time that transcription factors remain nuclear is a major determinant of transcriptional activity. The movement of proteins over ~40 kDa into and out of the nucleus is governed by the nuclear pore complex (NPC). Transcription factors and enzymes that regulate the activity of these proteins are shuttled across the nuclear envelope by proteins that recognize nuclear localization signals (NLS) and nuclear export signals (NES) within the amino acid sequence of these transcription factors. In this study, the precise mechanisms of Calcineurin nuclear import and export were identified. Additionally to the nuclear localization sequence (NLS) and the nuclear export sequence (NES) within the sequence of Calcineurin, the respective nuclear cargo proteins, responsible for nuclear import, Importin\&\#946;1, and for nuclear export, CRM1, were identified. Inhibition of the Calcineurin/importin interaction by a competitive peptide, called Import Blocking Peptide (IBP), which mimicked the Calcineurin NLS, prevented nuclear entry of Calcineurin. A non-inhibitory control peptide showed no effect. Using this approach, it was able to prevent the development of myocardial hypertrophy. In Angiotensin II stimulated cardiomyocytes, both the transcriptional and the translational level was suppressed. Additionally, cell size and expression of Brain natriuretic peptide (as molecular marker for hypertrophy) were significantly reduced compared untreated controls. IBP worked dose-dependent, but did not affect the Calcineurin phosphatase activity. In conclusion, Calcineurin is not only capable of dephosphorylating NFAT, thus enabling its nuclear import, its presence in the nucleus is also important for full NFAT transcriptional activity. Using IBP to prevent the nuclear import of Calcineurin is a completely new approach to prevent the development of myocardial hypertrophy.}, language = {en} } @phdthesis{Handoko2007, author = {Handoko, Lusy Lusiana}, title = {Functional Characterization of IGHMBP2, the Disease Gene Product of Spinal Muscular Atrophy with Respiratory Distress Type 1 (SMARD1)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24984}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Spinale Muskelatrophie mit Atemnot Type 1 (SMARD1) ist eine autosomal rezessive, neurodegenerative Erkrankung, die sich h{\"a}ufig schon im S{\"a}uglings- und Kleinkindalter manifestiert. Pathologisches Merkmal von SMARD1 ist eine fr{\"u}he und akut einsetzende Atemnot und eine progrediente, zun{\"a}chst distal betonte Muskelschw{\"a}che, die durch eine L{\"a}hmung des Zwerchfells und der Skelettmuskulatur aufgrund des Absterbens der motorischen Vordernhornzellen des R{\"u}ckenmarks eintritt. SMARD1 ist eine monogene Krankheit, die durch Mutationen im Gen f{\"u}r das Immunoglobulin µ-bindende Protein 2" (IGHMBP2) hervorgerufen wird. Obwohl Mutationen in IGHMBP2 ausschließlich die Degeneration von Motoneuronen ausl{\"o}sen, ist das Gen bei Menschen und M{\"a}usen ubiquit{\"a}r exprimiert. Deshalb scheint SMARD1 durch den Defekt eines „Haushaltsproteins" statt eines Neuron-spezifischen Faktors verursacht zu werden. IGHMBP2 verf{\"u}gt {\"u}ber eine N-terminale DEXDc-Helicase/ATPase-Dom{\"a}ne und geh{\"o}rt zur Superfamily 1 Helicase. Bislang war lediglich bekannt, dass das Protein in verschiedenen zellul{\"a}ren Aktivit{\"a}ten wie DNA Replikation, Transkription und pr{\"a}-mRNA Splicing zugewiesen wurde. Die pr{\"a}zise Funktion von IGHMBP2 in den obengenannten Prozessen, und damit auch die molekulare Ursache von SMARD1 sind jedoch noch v{\"o}llig unklar. Das Ziel der vorliegenden Arbeit war es daher, das IGHMBP2 Protein sowohl enzymatisch zu charakterisieren als auch den Prozess zu identifizieren, in dem dieses Protein in vivo agiert. Mit diesem Wissen sollten dann pathogene Mutanten von IGHMBP2 auf Defekte hin untersucht werden. Ein Schl{\"u}ssel f{\"u}r diese Arbeit war die Gewinnung von rekombinantem, biologisch aktivem IGHMBP2 durch eine zweistufige Aufreinigungsstrategie. Dieses hochreine Enzym zeigte eine ATP-abh{\"a}ngige Helikaseaktivit{\"a}t, die sowohl doppelstr{\"a}ngige DNA als auch RNA mit einer 5'\&\#8594;3' Direktionalit{\"a}t entwindet. Interessanterweise zeigte sich, dass dieses Enzym -im Gegensatz zu fr{\"u}heren Befunden- nahezu ausschließlich im Zytoplasma von Zellen lokalisiert ist. Dar{\"u}ber hinaus wiesen die Affinit{\"a}tsaufreinigungsexperimente und Grossenfraktionierungsuntersuchungen daraufhin, dass IGHMBP2 ein Bestandteil des RNase-empfindlichen Komplexes ist, der als Ribosomen identifiziert wurde. IGHMBP2 interagiert prim{\"a}r mit 80S Monosomen, wobei das Protein mit beiden Untereinheiten in Kontakt steht. Hingegen ist IGHMBP2 an Polysomen nur in geringen Mengen zu finden. Diese Befunde deuten stark auf eine Rolle von IGHMBP2 bei der mRNA Verarbeitung am Ribosom hin, wobei noch unklar ist, ob es sich um translationsrelevante Prozesse handelt oder die mRNA-Stabilit{\"a}t beeinflusst. Die biochemische und enzymatische Charakterisierung von IGHMBP2 erlaubte erstmals Einblicke in den Pathomechanismus von SMARD1. In den folgenden Untersuchungen wurden die enzymatischen Aktivit{\"a}ten der SMARD1-erregenden Ighmbp2 Mutante und ihre Assoziation mit ribosomalen Untereinheiten nachgeforscht. Interessanterweise konnten pathogene Missense-Mutanten von IGHMBP2 noch genauso gut wie das Wildtyp-Protein mit ribosomalen Untereinheiten wechselwirken. Jedoch inhibierten alle bisher getesteten Mutanten die RNA Helikaseaktivit{\"a}t, allerdings {\"u}ber unterschiedliche Mechanismen. Diese Daten weisen darauf hin, dass ein Defekt in den enzymatischen Aktivit{\"a}ten des IGHMBP2 direkt mit der Pathogenese der SMARD1 korreliert. Des Weiteren lassen die im Rahmen dieser Arbeit erhaltenen Ergebnisse vermuten, dass SMARD1 durch Defekte in der zellularen Translationsmaschinerie entsteht.}, subject = {IGHMBP2}, language = {en} } @article{HeisswolfGablerObermaieretal.2007, author = {Heisswolf, Annette and Gabler, Dirk and Obermaier, Elisabeth and M{\"u}ller, Caroline}, title = {Olfactory versus contact cues in host plant recognition of a monophagous chrysomelid beetle}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49475}, year = {2007}, abstract = {The importance of olfactory versus contact cues for host plant recognition was investigated in the tortoise beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae), which is strictly monophagous on meadow sage. The reaction of adult beetles to olfactory and contact host cues was tested using three bioassays (locomotion compensator, six-chamber-olfactometer, stem arena') to account for different behavioral contexts. Bioassay-guided fractionation of plant extracts was elaborated to characterize the nature of contact stimuli. The beetles were only slightly attracted to odors from small amounts of leaf material. However, when contact cues were provided additionally, the beetles showed strong preferences for samples of their host plant over controls. Bioassay-guided fractionation led to isolation of at least two non-polar contact stimuli acting in concert that are sufficient for host plant identification in C. canaliculata.}, subject = {Insekt}, language = {en} } @article{HeisswolfUlmannObermaieretal.2007, author = {Heisswolf, Annette and Ulmann, Sandra and Obermaier, Elisabeth and Mitesser, Oliver and Poethke, Hans J.}, title = {Host plant finding in the specialised leaf beetle Cassida canaliculata: an analysis of small-scale movement behaviour}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49485}, year = {2007}, abstract = {1. Host plant finding in walking herbivorous beetles is still poorly understood. Analysis of small-scale movement patterns under semi-natural conditions can be a useful tool to detect behavioural responses towards host plant cues. 2. In this study, the small-scale movement behaviour of the monophagous leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) was studied in a semi-natural arena (r = 1 m). In three different settings, a host (Salvia pratensis L., Lamiales: Lamiaceae), a non-host (Rumex conglomeratus Murr., Caryophyllales: Polygonaceae), or no plant was presented in the centre of the arena. 3. The beetles showed no differences in the absolute movement variables, straightness and mean walking speed, between the three settings. However, the relative movement variables, mean distance to the centre and mean angular deviation from walking straight to the centre, were significantly smaller when a host plant was offered. Likewise, the angular deviation from walking straight to the centre tended to decline with decreasing distance from the centre. Finally, significantly more beetles were found on the host than on the non-host at the end of all the trials. 4. It is concluded that C. canaliculata is able to recognise its host plant from a distance. Whether olfactory or visual cues (or a combination of both) are used to find the host plant remains to be elucidated by further studies.}, subject = {K{\"a}fer}, language = {en} } @phdthesis{HerreroGonzalez2007, author = {Herrero-Gonz{\´a}lez, Josep E.}, title = {Pathogenic relevance of autoantibodies to type XVII collagen from pemphigoid gestationis patients}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22329}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Pemphigoid gestationis (PG) and bullous pemphigoid (BP) are subepidermal autoimmune blistering diseases characterized by self-reactive T and B cells specific for the transmembrane hemidesmosomal protein type XVII collagen/BP180. Major T and B cell epitopes are located within the immunodominant 16th non-collagenous domain A (NC16A) of type XVII collagen. It has been suggested that pathogenically relevant autoantibodies also bind to this immunodominant region. The aim of this study was to map the epitopes targeted by blister-inducing human autoantibodies. For this purpose, we used an in vitro model of autoantibody-induced leucocyte-dependent dermal-epidermal separation. In contrast to the majority of patients with BP (7 of 10), preadsorption against a recombinant form of the NC16A region abolished the blister-inducing potential of autoantibodies from all PG patients tested (n=5). Using overlapping synthetic peptides, we demonstrate that PG autoantibodies bind to 2 defined epitopes within the NC16A region (aa 500-514 and aa 511-523). Preadsorption using an affinity matrix containing these two epitopes completely abolished dermal-epidermal separation induced by PG autoantibodies (in 8 of 9 patients). These findings provide new insights into the pathogenesis of pemphigoid diseases and should prove helpful for the development of an antigen-specific immunoadsorption therapy in PG.}, language = {en} } @phdthesis{Hippius2007, author = {Hippius, Catharina}, title = {Multichromophoric Arrays of Perylene Bisimide Dyes - Synthesis and Optical Properties}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24767}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The present work deals with the synthesis and the investigation of the photophysical properties of covalently constructed calix[4]arene-perylene bisimide dye arrays containing various PBI units. The obtained conjugates are characterized with respect towards their application in a new, zigzag-type architecture of artificial light-harvesting systems. For this purpose, orange (core-unsubstituted), red (6,7,11,12-tert-butylphenoxy-functionalized) and green (1,7-pyrrolidino-substituted) perylene bisimide building blocks have been attached to the calix[4]arene scaffold. First, the monochromophoric reference systems have been studied, and second, the photophysical properties of a comprehensive series of newly synthesized, multichromophoric calix[4]arene-perylene bisimide conjugates showing efficient energy transfer processes between the individual dye subunits have been investigated. Furthermore, a series of bichromophoric compounds containing identical chromophoric units has been obtained. Towards this goal, a variety of spectroscopic techniques such as UV/vis absorption, steady state and time-resolved fluorescence emission, and femtosecond transient absorption spectroscopy as well as a spectrotemporal analysis of the obtained data has been applied. This work presents a new concept for an artificial light-harvesting system positioning the dye units by means of calix[4]arene spacers along a zigzag chain. The investigations start with the syntheses and optical properties of the monochromophoric building blocks and result in an elaborate study on the energy and electron transfer processes occurring after photoexcitation in a comprehensive series of multichromophoric calix[4]arene-perylene bisimide conjugates. Finally, the photophysical properties of a series of compounds containing each two identical PBI units are discussed.}, subject = {Fluoreszenz-Resonanz-Energie-Transfer}, language = {en} } @phdthesis{Holzapfel2007, author = {Holzapfel, Marco}, title = {Photoinduced Charge Transfer Processes in Triarylamine Based Redox Cascades}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25276}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {In the first part of this work a new approach to measure transient absorption spectra of fluorescent compounds by means of laser flash photolysis technique was presented. Generally, the recorded transient absorption signal consists of transient absorption, fluorescence and ground state bleaching. Thus, for fluorescent chromophores a fluorescence correction is indispensable in order to obtain undisturbed absorption decay curves as well as accurate transient absorption spectra. Due to time response characteristics of the PMT detector the fluorescence contribution cannot be corrected by recording the fluorescence separately. Measuring two transient absorption signals with probe light differing in intensity, compounds with quantum yields up to ~ 35 \% can be investigated. This is a major improvement because transient absorption spectroscopy is a powerful method to gain insight into the kinetics and the energy of excited states and information in the time domain of fluorescence are no longer lost. In the second part the synthesis and the photophysical characterisation of redox cascades were reported. These cascades consist of an acridine acceptor and up to three triarylamine donor subunits. The redox potentials of the triarylamines were tuned by adequate substituents in the para-position of the phenyl ring to ensure a directed redox gradient. Upon photoexcitation a locally excited state or a CT state is populated which then injects a hole onto the adjacent donor and consequently results in a CS state. Fluorescence and transient absorption measurements revealed that HT depends strongly on donor strength and solvent polarity. Formation of a CS state was only observed in case of strong terminal donors or polar solvents. A low lying localised triplet state acts as an energy trap and quenches all CS states even in case of the cascade with the strongest terminal donor in very polar solvents. Furthermore, population of a CS state catalyses the formation of this triplet states which results in a shorter lifetime of the CS state compared to the lifetime of the CT state of the corresponding reference compound. Compared to redox cascades already reported in literature, the electronic coupling between the redox centres was decreased by sterical as well as electronic effects. To prolong the lifetime of the CS state saturated spacers on the one hand and a perpendicular orientation of the acceptor and the adjacent donor on the other hand were selected. The twisting of the subunits forming the CT state results in a higher degree of charge separation but its contribution to increase the lifetimes of the CS states is of minor importance. The longer lifetime of the CS states can be ascribed to the saturated spacers. Experimental data in combination with calculated values indicate that charge recombination takes place in the Marcus normal region by a superexchange mechanisms. Although charge recombination of the known cascades is located in the Marcus inverted region, these CS states decay faster than the CS states of the compounds investigated in this work.}, subject = {Ladungstransfer}, language = {en} } @article{HovestadtMitesserElmesetal.2007, author = {Hovestadt, Thomas and Mitesser, Oliver and Elmes, Graham and Thomas, Jeremy A. and Hochberg, Michael E.}, title = {An Evolutionarily Stable Strategy model for the evolution of dimorphic development in the butterfly Maculinea rebeli, a social parasite of Myrmica Ant Colonies}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48165}, year = {2007}, abstract = {Caterpillars of the butterfly Maculinea rebeli develop as parasites inside ant colonies. In intensively studied French populations, about 25\% of caterpillars mature within 1 year (fast-developing larvae [FDL]) and the others after 2 years (slow-developing larvae [SDL]); all available evidence indicates that this ratio is under the control of egg-laying females. We present an analytical model to predict the evolutionarily stable fraction of FDL (pESS). The model accounts for added winter mortality of SDL, general and kin competition among caterpillars, a competitive advantage of SDL over newly entering FDL (priority effect), and the avoidance of renewed infection of ant nests by butterflies in the coming season (segregation). We come to the following conclusions: (1) all factors listed above can promote the evolution of delayed development; (2) kin competition and segregation stabilize pESS near 0.5; and (3) a priority effect is the only mechanism potentially selecting for. However, given the empirical data, pESS is predicted to fall closer to 0.5 than to the 0.25 that has been observed. In this particular system, bet hedging cannot explain why more than 50\% of larvae postpone growth. Presumably, other fitness benefits for SDL, for example, higher fertility or longevity, also contribute to the evolution of delayed development. The model presented here may be of general applicability for systems where maturing individuals compete in small subgroups.}, language = {en} } @phdthesis{Hoyer2007, author = {Hoyer, Susanne Christine}, title = {Neuronal Correlates of Aggression in Drosophila melanogaster}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25871}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Aggression ist ein facettenreiches Ph{\"a}nomen, das sowohl in Vertebraten als auch in Invertebraten auftritt. Trotz der weiten Verbreitung dieses Verhaltens sind die neuronalen Netzwerke, die der Aggression zugrunde liegen, noch kaum bekannt. Zahlreiche Studien weisen den biogenen Aminen eine prominente Rolle in der Modulation von Aggression zu. Das Ziel dieser Doktorarbeit war mit Hilfe des Modellorganismus Drosophila melanogaster zu der Aufschl{\"u}sselung der neuronalen Korrelate von Aggression beizutragen, insbesondere im Hinblick auf das biogene Amin Oktopamin. In Drosophila sind aggressive Interaktionen aus einer Vielzahl von offensiven und defensiven Verhaltensweisen zusammengesetzt, von denen einige bez{\"u}glich der H{\"a}ufigkeit ihres Auftretens geschlechtsspezifisch sind. Um die Auswertung dieser vielseitigen Verhaltensweisen zu vereinfachen, wurde die Analyse auf einen einzigen Indikator f{\"u}r Aggression beschr{\"a}nkt: den „lunge". Diese bemerkenswerte Verhaltensweise tritt nur im Kontext der Aggression auf und ist charakteristisch f{\"u}r M{\"a}nnchen. In Kooperation mit Andreas Eckart habe ich ein Computerprogramm entwickelt, das eine automatische Ausz{\"a}hlung der lunges in einem vom Forscher gew{\"a}hlten Zeitraum durchf{\"u}hrt. Zus{\"a}tzlich erh{\"a}lt man u.a. Informationen {\"u}ber die Laufstrecke der einzelnen Tiere wie auch {\"u}ber ihre Gr{\"o}ße. Dank eines weiteren von uns entwickelten Programms ist es m{\"o}glich, K{\"a}mpfe zweier Drosophila M{\"a}nnchen unabh{\"a}ngig von deren Genotyp wahlweise automatisch oder halb-automatisch auszuwerten. Mit Hilfe dieser Programme wurde gezeigt, dass (1) die gemeinsame Laufaktivit{\"a}t der beiden M{\"a}nnchen mit der Anzahl aller aufgetretenen lunges korreliert und, dass (2) ein Gr{\"o}ßenunterschied von 8\% ausreichend ist, um zu beeinflussen, welches Tier mehr lunges durchf{\"u}hrt. Ebenfalls konnte festgestellt werden, dass (3) eine Nullmutation im ‚white' Gen, welches einen ABC-Transporter kodiert, aggressives Verhalten fast vollst{\"a}ndig unterdr{\"u}ckt, was teilweise auf eine visuelle Beeintr{\"a}chtigung zur{\"u}ckzuf{\"u}hren ist. Außerdem f{\"u}hrt (4) das Absenken des White-Levels in verschiedenen Bereichen des Zentralgehirns zu reduzierter Aggression; ein Effekt, der auch durch die chemische Entfernung der Pilzk{\"o}rper, einer Struktur des zentralen Gehirns, hervorgerufen werden kann. Dies weist darauf hin, dass die Integrit{\"a}t verschiedener neuronaler Netzwerke/Gehirnbereiche erforderlich ist, um wildtypische Aggression zu erm{\"o}glichen. Zus{\"a}tzlich konnte (5) anhand von Mutationen in zwei Genen der Oktopaminsynthese, die beide die Oktopamin-Konzentration zwar erniedrigen, die Tyramin-Konzentration jedoch heben bzw. senken, demonstriert werden, dass Oktopaminmangel Aggression fast vollst{\"a}ndig zum Erliegen bringt. Wird ein lunge durchgef{\"u}hrt, so ist dessen Ausf{\"u}hrung fast wildtypisch. Rettungsversuche, in denen Oktopamin- und/oder Tyramin-Konzentrationen wiederhergestellt werden, legen nahe, dass ein sehr spezifisches Muster von Oktopamin r{\"a}umlich und zeitlich gew{\"a}hrleistet sein muss, um ein so komplexes und faszinierendes Verhalten wie die Aggression in Drosophila hervorzurufen.}, subject = {Biogene Amine}, language = {en} } @phdthesis{Iuga2007, author = {Iuga, Maria}, title = {Ab Initio and Finite Element Simulations of Material Properties in Multiphase Ceramics}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26246}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {In the present study numerical methods are employed within the framework of multiscale modeling. Quantum mechanics and finite element method simulations have been used in order to calculate thermoelastic properties of ceramics. At the atomic scale, elastic constants of ten different ceramics (Al2O3, alpha- and beta-SiC, TiO2-rutile and anatase, AlN, BN, CaF2, TiB2, ZrO2) were calculated from the first principles (ab-initio) using the density functional theory with the general gradient approximation. The simulated elastic moduli were compared with measured values. These results have shown that the ab-initio computations can be used independently from experiment to predict elastic behavior and can provide a basis for the modeling of structural and elastic properties of more complex composite ceramics. In order to simulate macroscopic material properties of composite ceramics from the material properties of the constituting phases, 3D finite element models were used. The influence of microstructural features such as pores and grain boundaries on the effective thermoelastic properties is studied through a diversity of geometries like truncated spheres in cubic and random arrangement, modified Voronoi polyhedra, etc. A 3D model is used for modeling the microstructure of the ceramic samples. The measured parameters, like volume fractions of the two phases, grain size ratios and grain boundary areas are calculated for each structure. The theoretical model is then varied to fit the geometrical data derived from experimental samples. The model considerations are illustrated on two types of bi-continuous materials, a porous ceramic, alumina (Al2O3) and a dense ceramic, zirconia-alumina composite (ZA). For the present study, alumina samples partially sintered at temperatures between 800 and 1320 C, with fractional densities between 58.4\% and 97\% have been used. For ZA ceramic the zirconia powder was partially stabilized and the ratio between alumina and zirconia was varied. For these two examples of ceramics, Young's modulus and thermal conductivity were calculated and compared to experimental data of samples of the respective microstructure. Comparing the experimental and simulated values of Young's modulus for Al2O3 ceramic a good agreement was obtained. For the thermal conductivity the consideration of thermal boundary resistance (TBR) was necessary. It was shown that for different values of TBR the experimental data lie within the simulated thermal conductivities. In the case of ZA ceramic also a good agreement between simulated and experimental values was observed. For smaller ZrO2 fractions, a larger Young's modulus and thermal conductivity was observed in the experimental samples. The discrepancies have been discussed by taking into account the effect of pressure. Considering the dependence of the thermoelastic properties on the pressure, it has been shown that the thermal stresses resulting from the cooling process were insufficient to explain the discrepancies between experimental and simulated thermoelastic properties.}, subject = {Finite-Elemente-Methode}, language = {en} } @phdthesis{Jazbutyte2007, author = {Jazbutyte, Virginija}, title = {Differential role of estrogen receptor isoforms in the cardiovascular system of young and senescent rats}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24247}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Cardiovascular disease is the major cause of mortality morbidity in both men and women in industrialized countries. The incidence of cardiovascular diseases in pre-menopausal women is lower compared to age-matched men but the risk of heart diseases increases dramatically after the onset of menopause.Therefore, it has been postulated that female sex hormones play an important role in cardiovascular health in pre-menopausal women. In contrast to clinical data, which failed to show positive estrogen effects on cardiovascular system of post- menopausal women, extensive experimental studies indicated cardioprotective effects of estrogens in laboratory animals. The majority of experimental estrogen substitution studies were performed with young individuals, thus the effects of ageing remain neglected and are poorly understood. The present project is the first attempt to study the cardiac effects of each estrogen receptor isoform (estrogen receptor alpha (ERa) and estrogen receptor beta (ERb)) in adult ("menopausal") and senescent ("post- menopausal") hypertensive rats. The female senescent spontaneously hypertensive rats (SHR) served as a model system for age- associated hypertension in females whereas young individuals were used for control experiments. Young and senescent SHR rats were treated with 17b- estradiol as well as new estrogen receptor isoform selective ligands 16a-LE2 (ERa agonist) and 8b-VE2 (ERb agonist). The results showed different functions of both estrogen receptor isoforms in cardiovascular system: ERa attenuated cardiac hypertrophy but not hypertension whereas ERb could significantly reduce both, blood pressure and cardiac hypertrophy. Surprisingly, both agonists and 17b- estradiol were effective in young animals but not in senescent SHR rats. These findings match with the clinical data and could be related to altered estrogen metabolism in senescent rats, since estrogen plasma levels did not increase to measurable extent in senescent animals receiving estrogen. Estrogen is metabolized by several 17b- hydroxysteroid dehydrogenase isoforms. In the current study, 17b- hydroxysteroid dehydrogenase type 10 (17b- HSD10) was identified as a novel protein- protein interaction partner of estrogen receptor alpha ligand binding domain (ERaLBD) in human heart. Cellular localization experiments of ERa in the cardiac myocytes showed nuclear and cytosolic localization pattern which overlapped partially with that of cardiac mitochondria. 17b-HSD10 is localized only in mitochondria. Direct interaction of both proteins was confirmed by pull- down experiments where 17b-HSD10 could be co-precipitated with ERa. Interestingly, protein interaction could be detected only under estrogen- free conditions whereas the presence of estrogen in the system blocked this interaction. Enzymatic assay which was developed in our laboratory, helped to define functional relevance of this interaction. The data obtained from enzymatic assays and protein- protein interaction studies strongly suggest that estrogen receptor could play an important role in the control of intracellular (or mitochondrial) estogen metabolism. The second potential ERa interaction partner in the heart- bladder cancer associated protein 10 (BLCAP10) - was initially identified in non- invasive bladder cancer cell lines. BLCAP10 protein expression in the heart as well as its localization pattern in cardiac myocytes is shown in the last part of the theses. Due to perinuclear localization similarity with ERb, we conclude that BLCAP10 could interact with ERb rather than with ERa. Poor BLCAP10 protein overexpression and toxicity in both, bacteria and eukaryotic cells, suggested that BLCAP10 could be involved in cell- cycle and/ or protein expression control. In summary, the results showed that isoform selective activation of estrogen receptors exert divergent effects in the cardiovascular system both by upregulation of aMHC expression or by lowering blood pressure. Hormones were effective in young animals but had only minor effects in senescent rats. The new ERa protein- protein interaction partners identified during the project provide new information about estrogen receptor function in the heart and its possible role in the regulation of estrogen homeostasis.}, subject = {{\"O}strogene}, language = {en} } @phdthesis{Jenett2007, author = {Jenett, Arnim}, title = {The Virtual Insect Brain Protocol : development and application of software for the standardization of neuroanatomy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22297}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Since the fruit fly Drosophila melanogaster entered the laboratories as a model organism, new genetic, physiological, molecular and behavioral techniques for the functional analysis of the brain rapidly accumulated. Nowadays this concerted assault obtains its main thrust form Gal4 expression patterns that can be visualized and provide the means for manipulating -in unrestrained animals- groups of neurons of the brain. To take advantage of these patterns one needs to know their anatomy. This thesis describes the Virtual Insect Brain (VIB) protocol, a software package for the quantitative assessment, comparison, and presentation of neuroanatomical data. It is based on the 3D-reconstruction and visualization software Amira (Mercury Inc.). Its main part is a standardization procedure which aligns individual 3D images (series of virtual sections obtained by confocal microscopy) to a common coordinate system and computes average intensities for each voxel (volume pixel). The VIB protocol facilitates direct comparison of gene expression patterns and describes their interindividual variability. It provides volumetry of brain regions and helps to characterize the phenotypes of brain structure mutants. Using the VIB protocol does not require any programming skills since all operations are carried out at a (near to) self-explanatory graphical user interface. Although the VIB protocol has been developed for the standardization of Drosophila neuroanatomy, the program structure can be used for the standardization of other 3D structures as well. Standardizing brains and gene expression patterns is a new approach to biological shape and its variability. Using the VIB protocol consequently may help to integrate knowledge on the correlation of form and function of the insect brain. The VIB protocol provides a first set of tools supporting this endeavor in Drosophila. The software is freely available at http://www.neurofly.de.}, subject = {Taufliege}, language = {en} } @phdthesis{JurakBegonja2007, author = {Jurak Begonja, Antonija}, title = {NO/cGMP and ROS Pathways in Regulation of Platelet Function and Megakaryocyte Maturation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-21954}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Blutpl{\"a}ttchen spielen unter physiologischen Bedingungen eine wichtige Rolle bei der Erhaltung der H{\"a}mostase. So verhindern sie ein andauerndes Bluten von Wunden, indem sie in Blutgef{\"a}ssen zwischen normalen Zellen des Endothels und besch{\"a}digten Bereichen unterscheiden und sich dort gezielt anheften k{\"o}nnen. Das Zusammenspiel der Pl{\"a}ttchenagonisten und den dazugeh{\"o}rigen Rezeptoren wird durch intrazellul{\"a}re Signalmolek{\"u}le kontrolliert, die die Aktivierung der Blutpl{\"a}ttchen regulieren. {\"A}usserst wichtige intrazellulare Signalmolek{\"u}le stellen dabei die zyklischen Nukleotide cGMP und cAMP dar, die bei der Hemmung der Pl{\"a}ttchen beteiligt sind. Die Bildung von cGMP und cAMP in den Blutpl{\"a}ttchen wird durch die aus dem Endothel freigesetzten Molek{\"u}le NO und Prostacyclin (PGI2) stimuliert, die ihrerseits Blutpl{\"a}ttchen hemmen, indem sie Proteinkinase G (PKG) und Proteinkinase A (PKA) aktivieren. Neuerdings wird vorgeschlagen, dass es sich bei ROS („reactive oxygen species") um einen neuen Modulator bei der Signaltransduktion zwischen verschiedenen Zelltypen handelt. Die hier zusammengefasste Arbeit beschreibt die Rolle der ROS-Produktion bei der Aktivierung von Blutpl{\"a}ttchen, die Beziehung zwischen dem NO/cGMP/PKG I Signalweg und der ROS bzw. MAP-Kinase Signaltransduktion, und die Rolle von zyklischen Nukleotiden bei der Entwicklung von Megakaryozyten und Blutpl{\"a}ttchen. Werden Blutpl{\"a}ttchen durch unterschiedliche Einfl{\"u}sse aktiviert, so produzieren sie {\"u}ber die Aktivierung von NAD(P)H-Oxidase nur intrazellul{\"a}res aber nicht extrazellul{\"a}res ROS. Dabei beinflusst das in den Blutpl{\"a}ttchen produzierte ROS signifikant die Aktivierung von \&\#945;IIb\&\#946;3 Integrin, nicht jedoch die Sekretion von alpha- bzw. dichten Granula oder die Gestalt der Blutpl{\"a}ttchen. Die Thrombin-induzierte Integrin \&\#945;IIb\&\#946;3-Aktivierung ist nach Behandlung der Blutpl{\"a}ttchen mit Hemmstoffen der NAD(P)H-Oxidase oder Superoxid-F{\"a}ngern signifikant reduziert. Diese Inhibitoren reduzieren auch die Aggregation der Blutpl{\"a}ttchen bzw. die Thrombusbildung auf Kollagen, wobei diese Effekte unabh{\"a}ngig vom NO/cGMP Signalweg vermittelt werden. Sowohl ADP, das von dichten Granula der Blutpl{\"a}ttchen sezerniert wird und zur Aktivierung von P2Y12-Rezeptoren f{\"u}hrt, als auch die Freigabe von Thromboxan A2 stellen wichtige, vorgeschaltete Vermittler bei der p38 MAP Kinase-Aktivierung durch Thrombin dar. Jedoch spielt die p38 MAP-Kinase-Aktivierung keine signifikante Rolle bei der Thrombin-induzierten Kalzium-Mobilisierung, P-Selektin Exprimierung, \&\#945;IIb\&\#946;3 Integrin Aktivierung oder Aggregation der Blutpl{\"a}ttchen. Abschliessend kann festgestellt werden, dass sich die Aktivierung der PKG insgesamt klar hemmend auf die p38 and ERK MAP-Kinasen in menschlichen Blutpl{\"a}ttchen auswirkt. Desweiteren zeigt diese Studie, dass zyklische Nukleotide nicht nur die Blutpl{\"a}ttchen hemmen, sondern auch einen Einfluss auf die Entwicklung der Megakaryozyten und Blutpl{\"a}ttchen haben, aber auf unterschiedliche Weise. cAMP ist an der Differenzierung von embryonalen h{\"a}matopoietischen Zellen zu Megakaryozyten beteiligt, wobei cGMP keine Rolle bei diesem Prozess spielt. W{\"a}hrend PKA in embryonalen Zellen schon vertreten ist, steigt beim Reifungsprozess der Megakaryozyten die Expression von Proteinen, die bei der cGMP Signalverbreitung („soluble guanylyl cyclase", sGC; PKG) mitwirken, stetig an. In der letzten Phase der Reifung von Megakaryozyten, die durch die Freisetzung der Blutpl{\"a}ttchen charakterisiert ist, zeigen cGMP und cAMP leicht divergierende Effekte: cGMP verst{\"a}rkt die Bildung von Blutpl{\"a}ttchen, w{\"a}hrend cAMP dieselbe reduziert. Dies deutet auf einen fein abgestimmten Prozess hin, abh{\"a}ngig von einem Stimulus, der von den benachbarten Zellen des Sinusoid-Endothels stammen k{\"o}nnte. Die Ergebnisse dieser Dissertation tragen zu einen besseren Verst{\"a}ndnis der Regulation von Blutpl{\"a}ttchen sowie der m{\"o}glichen molekularen Mechanismen bei, die eine Rolle bei der Reifung von Megakaryozyten im vaskularen Mikroumfeld des Knochenmarks innehaben.}, subject = {Thrombozyt}, language = {en} } @phdthesis{Karg2007, author = {Karg, Stefan}, title = {Calculations of multi-particle processes at the one-loop level: precise predictions for the LHC}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-27505}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The Standard Model (SM) of elementary particle physics provides a uniform framework for the description of three fundamental forces, the electromagnetic and weak forces, describing interactions between quarks and leptons, and the strong force, describing a much stronger interaction between the coloured quarks. Numerous experimental tests have been performed in the last thirty years, showing a spectacular agreement with the theoretical predictions of the Standard Model, even at the per mille level, therefore validating the model at the quantum level. An important cornerstone of the Standard Model is the Higgs mechanism, which provides a possible explanation of electroweak symmetry breaking, responsible for the masses of elementary fermions and the W and Z bosons, the carriers of the weak force. This mechanism predicts a scalar boson, the Higgs boson, which has escaped its discovery so far. If the Higgs mechanism is indeed realised in nature, the upcoming Large Hadron Collider (LHC) at CERN will be able to find the associated Higgs boson. The discovery of a Higgs boson by itself is not sufficient to establish the Higgs mechanism, the basic ingredient being the Higgs potential which predicts trilinear and quartic couplings. These have to be confirmed experimentally by the study of multi-Higgs production. We therefore present a calculation of the loop-induced processes gg to HH and gg to HHH, and investigate the observability of multi-Higgs boson production at the LHC in the Standard Model and beyond. While the SM cross sections are too small to allow observation at the LHC, we demonstrate that physics beyond the SM can lead to amplified, observable cross sections. Furthermore, the applicability of the heavy top quark approximation in two- and three-Higgs boson production is investigated. We conclude that multi-Higgs boson production at the SuperLHC is an interesting probe of Higgs sectors beyond the SM and warrants further study. Despite the great success of the SM, it is widely believed that this model cannot be valid for arbitrarily high energies. The LHC will probe the TeV scale and theoretical arguments indicate the appearance of physics beyond the SM at this scale. The search for new physics requires a precise understanding of the SM. Precise theoretical predictions are needed which match the accuracy of the experiments. For the LHC, most analyses require next-to-leading order (NLO) precision. Only then will we be able to reliably verify or falsify different models. At the LHC, many interesting signatures involve more than two particles in the final state. Precise theoretical predictions for such multi-leg processes are a highly nontrivial task and new efficient methods have to be applied. The calculation of the process PP to VV+jet at NLO is an important background process to Higgs production in association with a jet at the LHC. We compute the virtual corrections to this process which form the "bottleneck" for obtaining a complete NLO prediction. The resulting analytic expressions are generated with highly automated computer routines and translated into a flexible Fortran code, which can be employed in the computation of differential cross sections of phenomenological interest. The obtained results for the virtual corrections indicate that the QCD corrections are sizable and should be taken into account in experimental studies for the LHC.}, subject = {Higgs-Teilchen}, language = {en} } @phdthesis{Karickal2007, author = {Karickal, Jose Thomas}, title = {FROM PROFESSIONAL FUNCTIONING TO PERSONAL CONFESSION - Henri J.M. Nouwen's contribution to the contemporary spirituality of pastoral care}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26305}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Henri J.M. Nouwen (1932-1996), a renowned pastoral theologian, has written more than 40 books among which several are about pastoral care and the spirituality of pastoral care. It was interesting for me to notice the parallel between his life and the contents of his books. He has undergone a tremendous personal development and spiritual maturity. His books invite all the christians and pastors to grow in the spiritual life. The spirituality is the underlying principle of creative ministry. Nouwen moves away from the traditional approach and concepts and develops his own concept of spiritual growth and pastoral care. Rooted in tradition and trained as a pastoral psychologist Nouwen is very appealing to the modern generation. This dissertation takes the reader through the life and writings of Nouwen to come to his original and new understanding of the spirituality of the pastoral care.}, subject = {Karickal}, language = {en} } @phdthesis{Keller2007, author = {Keller, Christian}, title = {The role of dendritic cells in the immunoregulation of leishmaniasis - transfection of dendritic cells with mRNA encoding a molecularly defined parasitic antigen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26208}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Die kutane Leishmaniose ist eine Infektionskrankheit, die besonders in tropischen und W{\"u}stenregionen endemisch ist, mit einer Inzidenz von 1,5 Millionen F{\"a}llen im Jahr und einer Pr{\"a}valenz von 12 Millionen Infizierten weltweit. Die Infektion kann durch den intrazellul{\"a}ren Parasiten Leishmania major hervorgerufen werden. Am Mausmodell ist die Krankheit ausf{\"u}hrlich untersucht. Wie dabei deutlich wurde, ist f{\"u}r die Immunit{\"a}t gegen den Erreger die Induktion einer Klasse von Interferon (IFN)-\&\#61543;-produzierenden CD4+ T-Helfer-Zellen (TH1-Zellen) entscheidend, welche Makrophagen dazu aktivieren, die von ihnen beherbergten Parasiten abzut{\"o}ten. Die Umlenkung der Immunantwort in Richtung einer sch{\"u}tzenden TH1-Antwort wird auch der Schl{\"u}ssel zu einem effektiven Impfstoff sein. Ex vivo mit Leishmanienantigenen beladene dendritische Zellen sind vor einiger Zeit als Vakzine gegen L. major-Infektionen beschrieben worden. Ein einzelnes rekombinantes Antigen, LeIF (Leishmania homologue of eukaryotic ribosomal initiation factor 4a), ein parasit{\"a}res Protein, das die IL-12-Produktion durch dendritische Zellen stimuliert und das als mikrobiell konserviertes Strukturmolek{\"u}l (pattern-associated molecular pattern; PAMP) diskutiert wird, vermittelte dabei, zum Pulsen von dendritischen Zellen verwendet, einen sch{\"u}tzenden TH1-abh{\"a}ngigen Effekt. Der Einsatz rekombinanter Proteine ist jedoch mit etlichen Nachteilen verbunden, weshalb andere Methoden zur Verabreichung von Antigenen entwickelt wurden. Aus der Tumorforschung ist unl{\"a}ngst die RNA-Elektroporation dendritischer Zellen als eine sichere und vielseitige Methode hervorgegangen, bei der eine große Anzahl von RNA-Molek{\"u}len, die f{\"u}r ein bestimmtes Antigen kodieren, durch einen elektrischen Impuls in das Cytosol dendritischer Zellen gelangt. Die vorliegende Arbeit beschreibt zum ersten Mal die Transfektion dendritischer Zellen mit RNA eines molekular definierten Parasitenantigens. Zun{\"a}chst erfolgte die Etablierung eines standardisierten Protokolls f{\"u}r die RNA-Transfektion mit dem enhanced green fluorescent protein (EGFP) als Reporterantigen. EGFP-RNA war gut translatierbar in einem In-vitro-Translationssystem, und es konnten sowohl eine Zellinie (fetal skin-derived dendritic cells; FSDC) als auch prim{\"a}re, aus Knochenmarkkulturen der Maus gewonnene dendritische Zellen (bone marrow-derived dendritic cells; BMDC) mit einem Anteil von bis zu 90\% bzw. 75\% effizient EGFP-transfiziert werden. In beiden Zelltypen wurde die maximale Transfektionseffizienz mit 20 µg RNA erreicht, die mit gr{\"o}ßeren Mengen an RNA nicht weiter zu steigern war. Die H{\"o}he der Antigenexpression, gemessen als mittlere Fluoreszenzintensit{\"a}t (MFI) in der Durchflußzytometrie, war direkt proportional zur verwendeten RNA-Menge. In FSDC waren die Transfektionseffizienz und die MFI generell h{\"o}her als in BMDC bei gleicher RNA-Menge. Zudem konnte gezeigt werden, daß eine Behandlung mit LPS die Kinetik beeinflußt: Die maximale Expression war h{\"o}her und wurde auch eher erreicht, worauf zudem ein schnellerer Abfall folgte. In den Transfektionsexperimenten mit LeIF wurden zwei Varianten von LeIF-RNA verwendet: eine f{\"u}r die gesamte LeIF-Sequenz kodierende LeIF(fl)-RNA, und eine nur f{\"u}r die aminoterminale H{\"a}lfte der LeIF-Sequenz (226 Aminos{\"a}uren), dem immunogenen Teil des LeIF-Molek{\"u}ls, kodierende LeIF(226)-RNA. Im Western Blot von Ganzzellysaten dendritischer Zellen war nur LeIF(fl) nach Transfektion nachzuweisen, wohingegen LeIF(226) in LeIF(226)-transfizierten BMDC nie nachzuweisen war. Da beide Konstrukte aber gut im zellfreien System translatierbar waren, stellte der fehlgeschlagene Nachweis von LeIF(226) kein Fehlschlagen der RNA-Translation, sondern vielmehr einen raschen Antigenabbau dar. Es bestand daher die Erwartung, daß LeIF(226)-transfizierte BMDC trotzdem in der Lage sein m{\"u}ßten, von LeIF(226) abgeleitete antigene Peptide an T-Zellen von mit rekombinantem LeIF (rLeIF) immunisierten BALB/c-M{\"a}usen zu pr{\"a}sentieren. Diese Vermutung wurde durch Messung von IFN-\&\#61543; in Stimulationsversuchen mit BMDC und T-Zellen best{\"a}tigt, die zeigten, daß am Tag 7 der Kultur mit rLeIF gepulste, LeIF(226)- und LeIF(fl)-transfizierte BMDC in der Tat antigenspezifisch T-Zellen aus LeIF-immunisierten M{\"a}usen aktivierten. IL-4 hingegen wurde nicht produziert, was mit der Tatsache vereinbar ist, daß in Lymphknoten LeIF-vakzinierter M{\"a}usen haupts{\"a}chlich T-Zellen vom TH1-Typ zu finden sind. In den {\"U}berst{\"a}nden LeIF-transfizierter BMDC-Kulturen, im Gegensatz zu rLeIF-gepulsten BMDC, waren die proinflammatorischen Zytokine IL-1\&\#946;, IL-6, IL-10 und IL-12 nicht nachzuweisen. Dieser Effekt lag nicht am Elektroporationsvorgang, da die Zytokinproduktion von mit rekombinantem LeIF elektroporierten BMDC nur teilweise beeintr{\"a}chtigt war. Die Expression von CD86 war nach LeIF-Transfektion zudem geringer als nach Pulsen mit rLeIF. LeIF-Transfektion f{\"u}hrte mithin nicht zur Reifung dendritischer Zellen. LeIF-transfizierte BMDC k{\"o}nnten im Ergebnis als antigenspezifische Toleranzinduktoren fungiert haben, mit regulatorischen T-Zellen als Respondern. Der Effekt der Transfektion mit LeIF-RNA auf die immunstimulatorische Wirkung von BMDC war nicht signifikant erh{\"o}ht, wenn BMDC am Tag 8 oder 9 der Kultur verwendet wurden. BMDC, die am Tag 8, und mehr noch am Tag 9 mit rLeIF gepulst wurden, induzierten hingegen eine energische T-Zell-Antwort. BMDC vom Tag 9 waren sogar in der Lage, naive T-Zellen zu aktivieren. Bevor eine starke, gegen LeIF gerichtete T-Zell-Antwort eingeleitet werden kann, m{\"u}ssen dendritische Zellen also letztlich - neben Pr{\"a}sentation des Antigens und Expression kostimulatorischer Molek{\"u}le - eine gewisse „Empfindlichkeit" gegen{\"u}ber dem Strukturmolek{\"u}l LeIF besitzen, die mit ihrem Reifungsalter in Zusammenhang steht. Dieses dritte Signal wird nicht durch intrazellul{\"a}res LeIF nach Transfektion mit LeIF-RNA {\"u}bermittelt, oder es wird unterdr{\"u}ckt. Dar{\"u}ber hinaus war nach Elektroporation von rLeIF die IL-12-Produktion von BMDC g{\"a}nzlich aufgehoben, die Produktion von IL-1\&\#61538; bei h{\"o}heren Antigendosen reduziert und die Produktion von IL-10 teilweise erh{\"o}ht. Die Produktion von IL-6 war unbeeinflußt. Dieses ver{\"a}nderte Zytokinprofil legt eine Doppelnatur von LeIF als PAMP nahe: Neben der bei extrazellul{\"a}rem Vorliegen von LeIF erwiesenen Eigenschaft, die Produktion von IL-12 zu stimulieren, welches die Resistenz des Wirtes gegen L. major steigert, k{\"o}nnte LeIF bei intrazellul{\"a}rem Vorliegen auch zu Evasionsmechanismen des Parasiten vor dem Immunsystem des Wirtes beitragen, m{\"o}glicherweise durch Wechselwirkung mit MAP (mitogen-activated protein)-Kinase-Signalwegen. Die Eigenschaften von LeIF als Adjuvans h{\"a}ngen also sowohl von der Verabreichungsmethode (Transfektion mit RNA bzw. Pulsen mit dem rekombinanten Protein) als auch vom Zielkompartiment (extra- bzw. intrazellul{\"a}r) ab. Zusammenfassend konnte also in dieser Arbeit gezeigt werden, daß BMDC mit einem Parasitenantigen transfizierbar sind. Das Antigen wird dabei prozessiert und pr{\"a}sentiert, aber von dendritischen Zellen nicht als PAMP erkannt. Durch Transfektion mit antigenkodierender mRNA alleine werden mithin nicht alle notwendigen Signale f{\"u}r die Induktion einer potenten Immunantwort {\"u}bermittelt.}, subject = {Elektroporation}, language = {en} } @phdthesis{Kluever2007, author = {Kl{\"u}ver, Nils}, title = {Molecular analysis of gonad development in medaka (Oryzias latipes) and Oryzias celebensis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25105}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The process of sex-determination can be better understood through examinations of developing organs and cells, which are involved in the formation of undifferentiated gonad. This mechanisms show in fish a broad variety, ranging from hermaphroditism to gonochorism and environmental to genetic sex determination. Hormones and abiotic factors such as temperature and pH can influence teleost development and reproductive traits. These factors are vulnerable to pollutants and climate changes. Therefore, it is important to examine gonad development and sex-determination/differentiation in teleost fish. Teleost fish are the largest known group of vertebrates with approximately 25,000 species and are used for such kind of examinations as model organisms. Recently, in Oryzias latipes (medaka), dmrt1bY (or dmy), a member of the Dmrt gene family, has been described as testis-determining gene. However, this gene is not the universal master sex-determining gene in teleost fish. Although dmrt1bY is present in the most closely related species of the genus, namely Oryzias curvinotous, it is absent from other Oryzias species, like Oryzias celebensis, and other fish. During my thesis, I studied gonad development in medaka and in the closely related species Oryzias celebensis. Germ cell specification in medaka seems to be dependent on maternally provided cytoplasmatic determinants, so called germ plasm. Nanos and vasa are such germ cell specific genes. In zebrafish they are asymmetrically localized in the early embryo. I have shown that nanos mRNA is evenly distributed in the early embryo of medaka. A similar pattern has been already described for the medaka vasa homolog, olvas. This suggests differences in PGC specification in zebrafish and medaka. Further, the vasa homolog was isolated and the expression pattern examined in O. celebensis. The results show that it can be used as a germ cell specific marker. Additionally, the primordial germ cell migration in O. celebensis was followed, which is similar to medaka PGC migration. Primordial germ cell migration in vertebrates is dependent on the chemokine stromal cell-derived factor 1 (Sdf-1). Medaka has two different sdf-1 genes, sdf-1a and sdf-1b. Both genes are expressed in the lateral plate mesoderm (LPM). During late embryonic development, I could show that sdf-1a is expressed in newly formed somites and not longer in the LPM. Sdf-1b expression persisted in the posterior part of the lateral plate mesoderm in the developing gonad. In terms of early and late functions, this suggests subfunctionalization of sdf-1a and sdf-1b. In "higher" vertebrates, genes that are involved in the process of gonad development have been studied in detail, e.g. Wt1, Sox9, and Amh. I have analyzed the expression pattern of wt1 and sox9 co-orthologs and amh. In both, the medaka and O. celebensis, wt1a transcripts were localized in the LPM and its expression was similar to sdf-1a gene expression in medaka. Wt1b expression was restricted to the developing pronephric region. During later embryonic development, wt1a is specifically expressed in the somatic cells of the gonad primordium in both sexes. This is the first time that in fish wt1 gene expression in developing gonads has been described. Therefore, this result suggests that wt1a is involved in the formation of the bipotential gonad. Furthermore, I have analyzed the gonad specific function of the wt1 co-orthologs in medaka. I could show that a conditional co-regulation mechanism between Wt1a and Wt1b ensures PGC maintenance and/or survival. The expression of sox9 genes in medaka and sox9b in O. celebensis were detected in the somatic cells of the gonad primordium of both sexes. Additionally, I have shown that amh and amhrII in medaka are expressed in somatic cells of the gonad primordium of both sexes. This suggests that sox9b, amh and amhrII are involved in gonad development and have specific functions in the adult gonad. In O. celebensis I could detect an expression of dmrt1 already six days after fertilization in half of the embryos, which is similar to the dmrt1bY expression in medaka. Whether the expression of dmrt1 is male specific in O. celebensis is currently under investigation. Altogether, the obtained results provide new insights into gene expression patterns during the processes of gonad development. Furthermore, no differences in the expression pattern of wt1a and sox9b during gonad development between the medaka and O. celebensis could be detected. This might indicate that the genetic mechanisms during gonad development are similar in both species.}, subject = {Japank{\"a}rpfling}, language = {en} } @phdthesis{Knaus2007, author = {Knaus, Anne Elizabeth}, title = {Pharmacological target proteins of alpha2-agonists in alpha2ABC-deficient mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23752}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Clonidine is an agonist at alpha2-adrenergic receptors that mediate a wide variety of the physiological responses to epinephrine and norepinephrine, such as inhibition of neurotransmitter release as well as sedation and analgesia. As with other therapeutically used alpha2-agonists such as moxonidine and rilmenidine, clonidine possesses an imidazoline structure and is believed to lower blood pressure not only via central and peripheral alpha2-receptors, but perhaps even more so by acting on central "imidazoline I1 receptors" in the brain stem. The molecular structure of these hypothetical "imidazoline I1 receptors" has not yet been identified. In order to test whether ligands with an imidazoline structure elicit pharmacological effects via alpha2-adrenergic receptors or via "imidazoline receptors", mice were generated with a targeted deletion of all three alpha2-adrenergic receptor subtypes (alpha2ABC-KO). These alpha2ABC-KO mice were an ideal model in which to examine the pharmacological effects of the centrally acting antihypertensives clonidine, moxonidine and rilmenidine in the absence of alpha2-adrenergic receptors. As expected, sedative and analgesic actions of clonidine were completely absent in alpha2ABC-KO mice, confirming the sole role of alpha2-receptors in these properties of clonidine. Clonidine significantly lowered heart rate in anesthetized alpha2ABC-KO and wild-type mice by up to 150 beats/min. A similar bradycardic effect of clonidine was observed in isolated spontaneously beating right atria from alpha2ABC-KO mice. After treatment with the specific If inhibitor ZD 7288, clonidine was no longer able to lower spontaneous beating frequency, suggesting a common site of action. Furthermore, in HEK293 cells stably transfected with HCN2 and HCN4, it could be shown that clonidine inhibits the If current via blockade of pacemaker channels with similar affinity as in isolated alpha2ABC-KO and wild-type atria. This inhibition was demonstrated again in isolated sinoatrial node (SAN) cells from alpha2ABC-KO mice and was identical in potency and efficacy to clonidine inhibition observed in isolated wild-type SAN cells, confirming that inhibition of atrial HCN channels constitutes the alpha2-independent bradycardic action of clonidine. Direct inhibition of cardiac HCN pacemaker channels contributes to the bradycardic effects of clonidine in gene-targeted mice. Thus clonidine-like drugs represent novel structures for future HCN channel inhibitors.}, language = {en} } @phdthesis{Konrad2007, author = {Konrad, Christian}, title = {Molecular analysis of insulin signaling mechanisms in Echinococcus multilocularis and their role in the host-parasite interaction in the alveolar echinococcosis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-22636}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The insulin receptor ortholog EmIR of the fox-tapeworm Echinococcus multilocularis displays significant structural homology to the human insulin receptor (HIR) and has been suggested to be involved in insulin sensing mechanisms of the parasite's metacestode larval stage. In the present work, the effects of host insulin on Echinococcus metacestode vesicles and the proposed interaction between EmIR and mammalian insulin have been studied using biochemical and cell-biological approaches. Human insulin, exogenously added to in vitro cultivated parasite larvae, (i) significantly stimulated parasite survival and growth, (ii) induced DNA de novo synthesis in Echinococcus, (iii) affected overall protein phosphorylation in the parasite, and (iv) specifically induced the phosphorylation of the parasite's Erk-like MAP kinase orthologue EmMPK1. These results clearly indicated that Echinococcus metacestode vesicles are able to sense exogenous host insulin which induces a mitogenic response. To investigate whether EmIR mediates these effects, anti-EmIR antibodies were produced and utilized in biochemical assays and immunohistochemical analyses. EmIR was shown to be expressed in the germinal layer of the parasite both on the surface of glycogen storing cells and undifferentiated germinal cells. Upon addition of exogenous insulin to metacestode vesicles, the phosphorylation of EmIR was significantly induced, an effect which was suppressed in the presence of specific inhibitors of insulin receptor-like tyrosine kinases. Furthermore, upon expression of EmIR/HIR receptor chimera containing the extracellular ligand binding domain of EmIR in HEK 293 cells, a specific autophosphorylation of the chimera could be induced through the addition of exogenous insulin. These results indicated the capability of EmIR to sense and to transmit host insulin signals to the Echinococcus signaling machinery. The importance of insulin signaling mechanisms for parasite survival and growth were underscored by in vitro cultivation experiments in which the addition of an inhibitor of insulin receptor tyrosine kinases led to vesicle degradation and death. Based on the above outlined molecular data on the interaction between EmIR and mammalian insulin, the parasite's insulin receptor orthologue most probably mediates the insulin effects on parasite growth and is, therefore, a potential candidate factor for host-parasite communication via evolutionary conserved pathways. In a final set of experiments, signaling mechanisms that act downstream of EmIR have been analyzed. These studies revealed significant differences between insulin signaling in Echinococcus and the related cestode parasite Taenia solium. These differences could be associated with differences in the organo-tropism of both species.}, subject = {Fuchsbandwurm}, language = {en} } @phdthesis{Krieglmeyer2007, author = {Krieglmeyer, Regina}, title = {How to Overcome Frustration? The Influence of Frustration on Motivational Orientation and Motivational Intensity}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-27841}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Frustration has been investigated since the early beginnings of psychological research. Yet, it is still unclear how frustration influences the two main parameters of motivation, i.e., orientation (approach-avoidance) and intensity. Some theories propose that controllable frustration increases approach motivation, thereby maintaining motivational intensity. In contrast, other theories propose that the perception of obstacles immediately elicits an avoidance orientation because of the negative valence of the perceptual input. Yet, the latter theories can not explain how motivational intensity is maintained upon encountering obstacles. The aim of the present thesis is to integrate previous contradicting assumptions by describing the influence of frustration on motivational orientation and motivational intensity on the basis of a two-system model of behavior. The definition of frustration as an unexpected obstacle blocking the attainment of an anticipated gratification implies that the obstacle is immediately perceived, whereas the goal is only represented in working memory. According to two-system models, these two types of representations influence different levels of behavior regulation. Whereas spontaneous approach-avoidance tendencies are mainly determined by the valence of the perceptual input, decisions to engage effort to reach the goal are based on knowledge about goals and appraisals of controllability of obstacles. Supporting this theorizing, six experiments demonstrated that frustration immediately activates avoidance tendencies. This was true for frustration of approach goals as well as for frustration of avoidance goals. Furthermore, this effect did not depend on the type of frustration feedback, and was found when approach-avoidance tendencies were measured after completion of goal pursuit as well as while overcoming frustration. In addition, approaching obstacles impaired performance in a subsequent task, suggesting that approaching obstacles consumed cognitive resources. This further supports the assumption that obstacles immediately activate avoidance tendencies. Furthermore, dispositional action-state orientation, which has been previously shown to moderate automatic affective reactions, influenced approach-avoidance tendencies, indicating that affect mediates the impact of frustration on behavioral tendencies. Finally, manipulations of controllability of frustration did not influence spontaneous approach-avoidance tendencies, but measures of motivational intensity such as decisions to engage more effort as well as activation of goal-relevant behavioral schemata. In sum, these findings support the assumptions that immediately elicited motivational orientations are mainly a function of the valence of perceptual input, whereas behavior to reach the goal (i.e. motivational intensity) is regulated by working memory representations such as appraisals of goal expectancy. Motivational orientations may serve to prepare organisms for quick reactions to sudden, unexpected occurrences, whereas behavior regulation based on goal appraisals may provide stability and flexibility in long-term goal pursuit.}, subject = {Sozialpsychologie}, language = {en} } @phdthesis{Koenig2007, author = {K{\"o}nig, Markus}, title = {Spin-related transport phenomena in HgTe-based quantum well structures}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-27301}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/HgCdTe quantum well structures. This material exhibits peculiar band structure properties, which result in a strong spin-orbit interaction of the Rashba type. An inverted band structure, i.e., a reversed ordering of the energy states in comparison to common semiconductors, is obtained for quantum well layers above a critical thickness. Furthermore, the band structure properties can be controlled in the experiments by moderate gate voltages. Most prominently, the type of carriers in HgTe quantum wells can be changed from n to p due to the narrow energy gap. Along with the inverted band structure, this unique transition is the basis for the demonstration of the Quantum Spin Hall state, which is characterized by the existence of two one-dimensional spin-polarized edge states propagating in opposite directions, while the Fermi level in the bulk is in the energy gap. Since elastic scattering is suppressed by time reversal symmetry, a quantized conductance for charge and spin transport is predicted. Our experiments provide the first experimental demonstration of the QSH state. For samples with characteristic dimensions below the inelastic mean free path, charge conductance close to the expected value of 2e^2/h has been observed. Strong indication for the edge state transport was found in the experiments as well. For large samples, potential fluctuations lead to the appearance of local n-conducting regions which are considered to be the dominant source of backscattering. When time reversal symmetry is broken in a magnetic field, elastic scattering becomes possible and conductance is significantly suppressed. The suppression relies on a dominant orbital effect in a perpendicular field and a smaller Zeeman-like effect present for any field direction. For large perpendicular fields, a re-entrant quantum Hall state appears. This unique property is directly related to the non-trivial QSH insulator state. While clear evidence for the properties of charge transport was provided, the spin properties could not be addressed. This might be the goal of future experiments. In another set of experiments, the intrinsic spin Hall effect was studied. Its investigation was motivated by the possibility to create and to detect pure spin currents and spin accumulation. A non-local charging attributed to the SHE has been observed in a p-type H-shaped structure with large SO interaction, providing the first purely electrical demonstration of the SHE in a semiconductor system. A possibly more direct way to study the spin Hall effects opens up when the spin properties of the QSH edge states are taken into account. Then, the QSH edge states can be used either as an injector or a detector of spin polarization, depending on the actual configuration of the device. The experimental results indicate the existence of both intrinsic SHE and the inverse SHE independently of each other. If a spin-polarized current is injected from the QSH states into a region with Rashba SO interaction, the precession of the spin can been observed via the SHE. Both the spin injection and precession might be used for the realization of a spin-FET similar to the one proposed by Datta and Das. Another approach for the realization of a spin-based FET relies on a spin-interference device, in which the transmission is controlled via the Aharonov-Casher phase and the Berry phase, both due to the SO interaction. In the presented experiments, ring structures with tuneable SO coupling were studied. A complex interference pattern is observed as a function of external magnetic field and gate voltage. The dependence on the Rashba splitting is attributed to the Aharonov-Casher phase, whereas effects due to the Berry phase remain unresolved. This interpretation is confirmed by theoretical calculations, where multi-channel transport through the device has been assumed in agreement with the experimental results. Thus, our experiments provide the first direct observation of the AC effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSHE relies on the peculiar band structure of the material and the existence of both the SHE and the AC effect is a consequence of the substantial spin-orbit interaction. While convincing results have been obtained for the various effects, several questions can not be fully answered yet. Some of them may be addressed by more extensive studies on devices already available. Other issues, however, ask, e.g., for further advances in sample fabrication or new approaches by different measurements techniques. Thus, future experiments may provide new, compelling insights for both the effects discussed in this thesis and, more generally, other spin-orbit related transport properties.}, subject = {Spin-Bahn-Wechselwirkung}, language = {en} } @phdthesis{Lageman2007, author = {Lageman, Christian}, title = {Convergence of gradient-like dynamical systems and optimization algorithms}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23948}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {This work studies the convergence of trajectories of gradient-like systems. In the first part of this work continuous-time gradient-like systems are examined. Results on the convergence of integral curves of gradient systems to single points of Lojasiewicz and Kurdyka are extended to a class of gradient-like vector fields and gradient-like differential inclusions. In the second part of this work discrete-time gradient-like optimization methods on manifolds are studied. Methods for smooth and for nonsmooth optimization problems are considered. For these methods some convergence results are proven. Additionally the optimization methods for nonsmooth cost functions are applied to sphere packing problems on adjoint orbits.}, subject = {Dynamisches System}, language = {en} } @phdthesis{Liedtke2007, author = {Liedtke, Daniel}, title = {Functional divergence of Midkine growth factors : Non-redundant roles during neural crest induction, brain patterning and somitogenesis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-25707}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Neural crest cells and sensory neurons are two prominent cell populations which are induced at the border between neural and non-neural ectoderm during early vertebrate development. The neural crest cells are multipotent and highly migratory precursors that give rise to face cartilage, peripheral neurons, glia cells, pigment cells and many other cell types unique to vertebrates. Sensory neurons are located dorsally in the neural tube and are essential for sensing and converting environmental stimuli into electrical motor reflexes. In my PhD thesis, I obtained novel insights into the complex processes of cell induction at the neural plate border by investigating the regulation and function of mdkb in zebrafish. First, it was possible to demonstrate that mdkb expression is spatiotemporally correlated with the induction of neural crest cells and primary sensory neurons at the neural plate border. Second, it became evident that the expression of mdkb is activated by known neural crest cell inducing signals, like Wnts, FGFs and RA, but that it is independent of Delta-Notch signals essential for lateral inhibition. Knockdown experiments showed that mdkb function is necessary for induction of neural crest cells and sensory neurons at the neural plate border, probably through determination of a common pool of progenitor cells during gastrulation. The present study also used the advantages of the zebrafish model system to investigate the in vivo function of all midkine gene family members during early brain development. In contrast to the situation in mouse, all three zebrafish genes show distinct expression patterns throughout CNS development. mdka, mdkb and ptn expression is detected in mostly non-overlapping patterns during embryonic brain development in the telencephalon, the mid-hindbrain boundary and the rhombencephalon. The possibility of simultaneously knocking down two or even three mRNAs by injection of morpholino mixtures allowed the investigation of functional redundancy of midkine factors during brain formation. Knockdown of Midkine proteins revealed characteristic defects in brain patterning indicating their association with the establishment of prominent signaling centers such as the mid-hindbrain boundary and rhombomere 4. Interestingly, combined knockdown of mdka, mdkb and ptn or single knockdown of ptn alone prevented correct formation of somites, either by interfering with the shifting of the somite maturation front or interferance with cell adhesion in the PSM. Thus, Ptn was identified as a novel secreted regulator of segmentation in zebrafish.}, subject = {Zebrab{\"a}rbling}, language = {en} } @phdthesis{Lim2007, author = {Lim, Hee-Young}, title = {Functional studies of GR and MR function by RNA interference}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23646}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Die Steroidhormone Corticosteron/Cortisol und Aldosteron werden in Folge von Stress oder eines ver{\"a}nderten Salz-Wasser-Haushalt durch die Nebenniere synthetisiert und sezerniert. Dies wird durch negative R{\"u}ckkopplungsmechanismen kontrolliert, die als HPA-Achse und RAAS bezeichnet werden. Die Aktivit{\"a}t dieser Steroidhormone wird durch den Glukokortikoid Rezeptor (GR) und den Mineralokortikoid-Rezeptor (MR) vermittelt, die im Zytosol als Komplex mit Hitze-Schock-Proteinen vorliegen. Sowohl der GR als auch der MR geh{\"o}ren zur Kern-Rezeptor Superfamilie und besitzen eine gemeinsame Proteinstruktur die aus drei verschiedenen Dom{\"a}nen besteht. Trotzdem haben sie verschiedene Affinit{\"a}ten f{\"u}r ihre Liganden, ihre Aktivit{\"a}t h{\"a}ngt von der Hormonkonzentration ab, sie werden durch Pr{\"a}-Rezeptor-Mechansimen wie der 11b-HSD2 reguliert und ihre Gewebeverteilung ist unterschiedlich. Aldosteron wirkt in epithelialen und nicht-epithelialen Zellen {\"u}ber den MR und reguliert den Salz-Wasser-Haushalt, die Herzfunktion, die neuronale Erregbarkeit und die Adipozyten-Differenzierung. Bislang war die Analyse der Geninaktivierung in vivo auf M{\"a}use beschr{\"a}nkt, obwohl Krankheitsmodelle in der Ratte die Verh{\"a}ltnisse im Menschen manchmal besser widerspiegeln. Da embryonale Stammzellen und damit die gezielte Genmanipulation in Ratten nicht verf{\"u}gbar sind, haben wir MR knock-down Ratten mittels lentiviral eingef{\"u}hrter shRNAs hergestellt. Die F1 Nachkommen der Gr{\"u}nder-Ratten zeigten unterschiedlich stark reduzierte MR mRNA und Protein Niveaus in Niere und Hippocampus, den Hauptexpressions-Regionen des MR. Im Gegensatz dazu war die Expression des GR unver{\"a}ndert, was die Spezifit{\"a}t der Geninaktivierung belegt. Die zwei MR Zielgene Sgk1 und ENaC waren hochreguliert w{\"a}hrend die mRNA Spiegel anderer Gene wie IK1 und SCD2 erniedrigt waren. {\"A}hnlich wie in den knock-out M{\"a}usen und Patienten zeigten die knock-down Ratten die typischen Merkmale des Pseudohypoaldosteronismus Typ I wie erh{\"o}hte Serumspiegel von Aldosteron und Renin sowie Wachstumsretardation. Weiterhin fanden wir einen linearen Zusammenhang zwischen der MR Expression in der Niere, den Serum Aldosteron-Werten und dem K{\"o}rpergewicht. Zusammengefasst sind unsere MR knock-down Ratten unter den ersten Beispielen f{\"u}r RNAi in vivo und belegen, dass diese Technik es erlaubt, abgestufte Auspr{\"a}gugen der Geninktivierung wie in humanen genetischen Erkrankungen zu erreichen. Weiterhin haben wir die Rolle des GR und des MR f{\"u}r die immunmodulatorische Aktivit{\"a}t der Glukokortikoide in peritonealen Makrophagen untersucht. GCs sind an der Kontrolle der Makrophagenfunktion beteiligt und regulieren so die Reaktion gegen{\"u}ber Pathogenen. Aus diesem Grund werden GCs weitverbreitet zur Behandlung von Enz{\"u}ndungen und Autoimmunerkrankungen eingesetzt. Allerdings ist bez{\"u}glich dieser GC Aktivit{\"a}ten weder bekannt welche Kontrolle die Hormonkonzentration spielt noch kennt man den differentiellen Beitrag des GR und des MR. Zuerst best{\"a}tigten wir die Expression beider Rezeptoren in peritonealen Makrophagen w{\"a}hrend die 11b-HSD2 nicht exprimiert war. Anschließend zeigten wir, dass niedrigte Corticosteron-Level die NO Produktion sowie die mRNA Expression von pro-inflammatorischen Zytokinen, Chemokinen und Enzymen die f{\"u}r die Mediator-Synthesee ben{\"o}tigt werden erh{\"o}hen. Im Gegensatz dazu war die Makrophagen Funktion bei hohen Corticosteron-Konzentrationen stark reprimiert. Eine wichtige Beobachtung war, dass die Inaktivierung des GR durch lentiviral eingef{\"u}hrte siRNAs sowohl die immunstimulatorischen als auch die immunsuppressiven GR Aktivit{\"a}ten aufhob w{\"a}hrend die Inaktivierung des MR keine Konsequenzen hatte. Weiterhin f{\"u}hrte der Verlust endogenener GCs nach Adrenalektomie in vivo zu einem pr{\"a}-aktivierten Zustand der Makrophagen, welcher durch Corticosteron moduliert werden konnte. Wir schließen hieraus, dass GCs in Abh{\"a}ngigkeit von ihrer Konzentration unterschiedliche Effekte auf die Makrophagen Funktion haben und dass diese durch den GR vermittelt werden, obwohl der MR ebenfalls exprimiert ist. Zusammengefasst best{\"a}tigen unsere Ergebnisse dass die lenivirale Transduktion von shRNAs eine effiziente Methode zur Geninaktivierung in prim{\"a}ren Zellen und transgenen Ratten darstellt und es so erlaubt, funktionelle Studien durchzuf{\"u}hren die zuvor auf M{\"a}use beschr{\"a}nkt waren.}, language = {en} } @phdthesis{Liu2007, author = {Liu, Jiming}, title = {Transcription mechanisms and functions of NFATc1 in T lymphocytes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24270}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {The Nuclear Factors of Activated T cells (NFATs) are critical transcription factors that direct gene expression in immune and non-immune cells. Interaction of T cells with Ag-presenting cells results in the clustering of T-cell antigen receptor (TCR), co-receptors and integrins. Subsequent signal transduction resulting in NFAT activation leads to cytokine gene expression. Among the NFATs expressed in T cells, NFATc1 shows a unique induction property, which is essential for T cell differentiation and activation. It was revealed before that 3 major isoforms of NFATc1 are generated in activated T cells - the inducible short NFATc1/A, and the longer isoforms NFATc1/B and C. However, due to alternative splicing events and the existence of two different promoters and two alternative polyadenylation, we show here that 6 isoforms are synthesized in T cells which differ in their N-terminal and C-terminal peptides. In these experiments, we have identified these 6 isoforms by semi-quantitative long distance RT-PCR in several T cells subsets, and the inducible properties of 6 isoforms were investigated in those cells. The short NFATc1/\&\#61537;A which is under control of the P1 promoter and the proximal pA1 polyadenylation site was the most prominent and inducible isoform in T effector cells. The transcription of the longer NFATc1/\&\#61538;B and \&\#61538;C isoforms is constitutive and even reduced in activated T lymphocytes. In addition to NFATc1 autoregulation, we tried to understand the NFATc1 gene regulation under the control of PKC pathways by microarray analysis. Compared to treatment of T cells with ionomycin alone (which enhances Ca++ flux), treatment of cells with the phorbolester TPA (leading to PKC activation) enhanced the induction of NFATc1. Microarray analysis revealed that PKC activation increased the transcription of NF-\&\#61547;B1, Fos and JunB, which are important transcription factors binding to the regulatory regions of the NFATc1 gene. Besides the promoting effect of these transcription factors, we provided evidence that p53 and its targeting gene, Gadd45\&\#61537;, exerted a negative effect on NFATc1 gene transcription. Summarizing all these results, we drew novel conclusions on NFATc1 expression, which provide a more detailed view on the regulatory mechanisms of NFATc1 transcription. Considering the high transcription and strong expression of NFATc1 in various human lymphomas, we propose that similar to NF-\&\#61547;B, NFATc1/\&\#61537;A plays a pivotal role in lymphomagenesis.}, subject = {NFATs}, language = {en} } @phdthesis{Mahapatra2007, author = {Mahapatra, Suddhasatta}, title = {Formation and Properties of Epitaxial CdSe/ZnSe Quantum Dots : Conventional Molecular Beam Epitaxy and Related Techniques}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32831}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Albeit of high technological import, epitaxial self-assembly of CdSe/ZnSe QDs is non-trivial and still not clearly understood. The origin and attributes of these QDs are significantly different from those of their III-V and group-IV counterparts. For III-V and group-IV heterosystems, QD-formation is assigned to the Stranski Krastanow (SK) transition, wherein elastic relaxation of misfit strain leads to the formation of coherent three-dimensional (3D) islands, from a supercritically strained two-dimensional (2D) epilayer. Unfortunately, this phenomenon is inconspicuous for the CdSe/ZnSe heterosystem. Well-defined 3D islands are not readily formed in conventional molecular beam epitaxial (MBE) growth of CdSe on ZnSe. Consequently, several alternative approaches have been adopted to induce/enhance formation of QDs. This thesis systematically investigates three such alternative approaches, along with conventional MBE, with emphasis on the formation-mechanism of QDs, and optimization of their morphological and optical attributes. It is shown here that no distinct 3D islands are formed in MBE growth of CdSe on ZnSe. The surface of the CdSe layer represents a rough 2D layer, characterized by a dense array of shallow (<1nm) abutting mounds. In capped samples, the CdSe deposit forms an inhomogeneous CdZnSe quantum well (QW)-like structure. This ternary QW consists of local Cd-rich inclusions, which confine excitons three-dimensionally, and act as QDs. The density of such QDs is very high (~ 1012 cm-2). The QDs defined by the composition inhomogeneities of the CdZnSe QW presumably originate from the shallow mounds of the uncapped CdSe surface. By a technique wherein a CdSe layer is grown at a low temperature (TG = 230 °C) and subsequently annealed at a significantly higher temperature (TA =310 °C), tiny but distinct 3D islands are formed. In this work, the mechanism underlying the formation of these islands is reported. While the CdSe deposit forms a quasi-two-dimensional (quasi-2D) layer at TG = 230 °C, subsequent annealing at TA = 310 °C results in a thermally activated "up-climb" of adatoms onto two-dimensional clusters (or precursors) and concomitant nucleation of 3D islands. The areal density of QDs, achieved by this technique, is at least a decade lower than that typical for conventional MBE growth. It is demonstrated that further reduction is possible by delaying the temperature ramp-up to TA. In the second technique, formation of distinct islands is demonstrated by deposition of amorphous selenium (a-Se) onto a 2D CdSe epilayer at room temperature and its subsequent desorption at a higher temperature (TD = 230 °C). Albeit the self-assembled islands are large, they are severely truncated during subsequent capping with ZnSe, presumably due to segregation of Cd and Zn-alloying of the islands. The segregation phenomenon is analyzed in this work and correlated to the optical properties of the QDs. Additionally, very distinct vertical correlation of QDs in QD-superlattices, wherein the first QD-layer is grown by this technique and the subsequent ones by migration enhanced epitaxy (MEE), is reported. The process steps of the third variant technique, developed in course of this work, are very similar to those of the previous one-the only alteration being the substitution of selenium with tellurium as the cap-forming-material. This leads not only to large alteration of the morphological and optical attributes of the QDs, but also to formation of unique self-assembled island-patterns. Oriented dashes, straight and buckled chains of islands, and aligned island-pairs are formed, depending on the thickness of the Te-cap layer. The islands are partially alloyed with Te and emit luminescence at very low energies (down to 1.7 eV at room temperature). The Te cap layer undergoes (poly)crystallization during temperature ramp-up (from room temperature to TD) for desorption. Here, it is shown that the self-assembled patterns of the island-ensembles are determined by the pattern of the grain boundaries of the polycrystalline Te layer. Based on an understanding of the mechanism of pattern formation, a simple and "clean" method for controlled positioning of individual QDs and QD-based extended nanostructures, is proposed in this work. The studies carried out in the framework of this thesis provide not only a deeper insight into the microscopic processes governing the heteroepitaxial self-assembly of CdSe/ZnSe(001) QDs, but also concrete approaches to achieve, optimize, and control several technologically-important features of QD-ensembles. Reduction and control of QD-areal-density, pronounced vertical correlation of distinctly-defined QDs in QD-superlattices, and self-assembly of QD-based extended structures, as demonstrated in this work, might turn out to be beneficial for envisioned applications in information-, and communication-technologies.}, subject = {Nanostruktur}, language = {en} } @phdthesis{Marquetand2007, author = {Marquetand, Philipp}, title = {Vectorial properties and laser control of molecular dynamics}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24697}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {In this work, the laser control of molecules was investigated theoretically. In doing so, emphasis was layed on entering vectorial properties and in particular the orientation in the laboratory frame. Therefore, the rotational degree of freedom had to be included in the quantum mechanical description. The coupled vibrational and rotational dynamics was examined, which is usually not done in coherent control theory. Local control theory was applied, where the field is determined from the dynamics of a system, which reacts with an instantaneous response to the perturbation and, in turn, determines the field again. Thus, the field is entangled with the quantum mechanical motion and the presented examples document, that this leads to an intuitive interpretation of the fields in terms of the underlying molecular dynamics. The limiting case of a classical treatment was shown to give similar results and hence, eases to understand the complicated structure of the control fields. In a different approach, the phase- and amplitude shaping of laser fields was systematically studied in the context of controlling population transfer in molecules.}, subject = {Laserchemie}, language = {en} } @phdthesis{Milbrandt2007, author = {Milbrandt, Jens}, title = {Performance Evaluation of Efficient Resource Management Concepts for Next Generation IP Networks}, doi = {10.25972/OPUS-1991}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23332}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Next generation networks (NGNs) must integrate the services of current circuit-switched telephone networks and packet-switched data networks. This convergence towards a unified communication infrastructure necessitates from the high capital expenditures (CAPEX) and operational expenditures (OPEX) due to the coexistence of separate networks for voice and data. In the end, NGNs must offer the same services as these legacy networks and, therefore, they must provide a low-cost packet-switched solution with real-time transport capabilities for telephony and multimedia applications. In addition, NGNs must be fault-tolerant to guarantee user satisfaction and to support business-critical processes also in case of network failures. A key technology for the operation of NGNs is the Internet Protocol (IP) which evolved to a common and well accepted standard for networking in the Internet during the last 25 years. There are two basically different approaches to achieve QoS in IP networks. With capacity overprovisioning (CO), an IP network is equipped with sufficient bandwidth such that network congestion becomes very unlikely and QoS is maintained most of the time. The second option to achieve QoS in IP networks is admission control (AC). AC represents a network-inherent intelligence that admits real-time traffic flows to a single link or an entire network only if enough resources are available such that the requirements on packet loss and delay can be met. Otherwise, the request of a new flow is blocked. This work focuses on resource management and control mechanisms for NGNs, in particular on AC and associated bandwidth allocation methods. The first contribution consists of a new link-oriented AC method called experience-based admission control (EBAC) which is a hybrid approach dealing with the problems inherent to conventional AC mechanisms like parameter-based or measurement-based AC (PBAC/MBAC). PBAC provides good QoS but suffers from poor resource utilization and, vice versa, MBAC uses resources efficiently but is susceptible to QoS violations. Hence, EBAC aims at increasing the resource efficiency while maintaining the QoS which increases the revenues of ISPs and postpones their CAPEX for infrastructure upgrades. To show the advantages of EBAC, we first review today's AC approaches and then develop the concept of EBAC. EBAC is a simple mechanism that safely overbooks the capacity of a single link to increase its resource utilization. We evaluate the performance of EBAC by its simulation under various traffic conditions. The second contribution concerns dynamic resource allocation in transport networks which implement a specific network admission control (NAC) architecture. In general, the performance of different NAC systems may be evaluated by conventional methods such as call blocking analysis which has often been applied in the context of multi-service asynchronous transfer mode (ATM) networks. However, to yield more practical results than abstract blocking probabilities, we propose a new method to compare different AC approaches by their respective bandwidth requirements. To present our new method for comparing different AC systems, we first give an overview of network resource management (NRM) in general. Then we present the concept of adaptive bandwidth allocation (ABA) in capacity tunnels and illustrate the analytical performance evaluation framework to compare different AC systems by their capacity requirements. Different network characteristics influence the performance of ABA. Therefore, the impact of various traffic demand models and tunnel implementations, and the influence of resilience requirements is investigated. In conclusion, the resources in NGNs must be exclusively dedicated to admitted traffic to guarantee QoS. For that purpose, robust and efficient concepts for NRM are required to control the requested bandwidth with regard to the available transmission capacity. Sophisticated AC will be a key function for NRM in NGNs and, therefore, efficient resource management concepts like experience-based admission control and adaptive bandwidth allocation for admission-controlled capacity tunnels, as presented in this work are appealing for NGN solutions.}, subject = {Ressourcenmanagement}, language = {en} } @phdthesis{Mishina2007, author = {Mishina, Tatiana E.}, title = {Mechanisms of local and systemic defences in Arabidopsis thaliana in response to host and non-host strains of Pseudomonas syringae}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23160}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Stickstoffmonooxid (NO) wird als wichtige Signalkomponente bei der Entwicklung der Hypersensitiven Reaktion beschrieben. Außerdem wird NO eine Rolle als Signalmolek{\"u}l bei der Expression von Abwehrgenen wie PR-1, PAL1 oder Chalkonsynthase (CHS) und bei der Akkumulation von Salicyls{\"a}ure zugeordnet (Durner et al., 1998). In der vorliegenden Arbeit wurden transgene Pflanzen mit ver{\"a}nderten endogenen NO-Spiegeln verwendet, um die Rolle von NO in Pflanze-Pathogen-Interaktionen zu untersuchen. Arabidopsis-Pflanzen, die aufgrund der Expression einer NO Dioxygenase erniedrigte NO-Gehalte aufweisen, zeigen nach einem Angriff avirulenter Pathogene einen abgeschw{\"a}chten oxidative burst und eine reduzierte Expression von Genen des Phenylpropanbiosyntheseweges. Weitere Experimente mit transgenen Pflanzen, die eine bakterielle NO-Synthase exprimieren, legen nahe, dass eine konstitutive Erh{\"o}hung der NO-Spiegel nicht zu einer konstitutiv verst{\"a}rkten Pathogenabwehr f{\"u}hrt. M{\"o}glicherweise ist eine graduelle Steigerung der NO-Gehalte nach Pathogenkontakt f{\"u}r die Induktion pflanzlicher Abwehrreaktionen erforderlich. Im Gegenteil, die NOS-exprimierenden Pflanzen waren anf{\"a}lliger gegen bakterielle Pathogene als Wildtyp-Pflanzen und zeigten eine abgeschw{\"a}chte SAR-Reaktion. Die Ergebnisse deuten auch darauf hin, dass NO eine wichtige Rolle bei der Regulation des Redoxstatus in der Pflanzenzelle spielt. Diese Funktion von NO ist wichtig beim Seneszenzvorgang. Entsprechend der Ergebnisse dieser Arbeit kann NO als negativer Regulator der Blattseneszenz angesehen werden. Die Wirkungsweise von NO auf molekularer Ebene und die Signalkaskaden, in die NO involviert ist, sind immer noch nicht ausreichend verstanden. In zuk{\"u}nftigen Experimenten wird es notwendig sein, die selektive Quantifizierung von NO in intaktem Pflanzengewebe zu gew{\"a}hrleisten, die Proteintargets von NO zu identifizieren und die Struktur und Funktion NO-modifizierter Biomolek{\"u}le zu entschl{\"u}sseln, um die Rolle von NO in Pflanze-Pathogen-Wechselwirkungen besser verstehen zu lernen. Die Nichtwirtsresistenz beruht auf mehreren Verteidigungsebenen, welche konstitutive und induzierte Komponenten beinhalten. Die Bedeutung induzierter Abwehrreaktionen f{\"u}r die Nichtwirtsresistenz gegen bakterielle Pathogene ist nicht vollst{\"a}ndig klar. Die Daten der vorliegenden Arbeit legen nahe, dass das Wachstum von Nichtwirtsbakterien in Arabidopsis-Bl{\"a}ttern durch vorgebildete toxische Substanzen und durch induzierte Zellwandverst{\"a}rkungen gehemmt wird. Nichtwirtsbakterien verursachen eine schnelle Induktion der Expression der Ligninbiosynthesegene PAL1 und BCB, die unabh{\"a}ngig vom Typ III-Sekretionssystem ist und m{\"o}glicherweise zur Papillenbildung beitr{\"a}gt. Dar{\"u}ber hinaus ist die {\"U}berlebensrate der Nichtwirtsbakterien in den extrazellul{\"a}ren R{\"a}umen der Arabidopsis pal1-Mutante h{\"o}her als in Wildtyp-Pflanzen, was die funktionelle Bedeutung der PAL1-Expression bei der Nichtwirtsresistenz verdeutlicht. Außerdem zeigen die Experimente, dass Nichtwirtsbakterien in {\"a}hnlicher Weise wie Wirtsbakterien die Akkumulation von Salicyls{\"a}ure und die Expression von PR-Genen induzieren. Die Induktion dieser Abwehrkomponenten ist abh{\"a}ngig von einem intakten Typ III-Sekretionssystem. Die Signalwege, auf denen nach Kontakt mit Nichtwirtsbakterien und Wirtsbakterien Abwehrreaktionen induziert werden, sind {\"a}hnlich. Es wurden jedoch zwischen zwei verschiedenen Nichtwirtsst{\"a}mmen auch unterschiedliche Signalwege aktiviert, was m{\"o}glicherweise auf ein unterschiedliches Repertoire von TypIII-Effektoren der beiden St{\"a}mme zur{\"u}ckgef{\"u}hrt werden kann. Trotz der Aktivierung dieser induzierten Abwehr zeigen Experimente mit klassischen Abwehrmutanten, dass SA- und JA-abh{\"a}ngige Abwehrreaktionen nicht direkt zur Nichtwirtsresistenz gegen P. syringae beitragen. Weiterhin zeigt diese Arbeit, dass die Nichtwirtsresistenz des Arabidopsis-{\"O}kotyps Col-0 effektiver ist als die des Ler-0-{\"O}kotyps, obwohl bei letzterem die Resistenz gegen virulente Bakterien h{\"o}her ist. Diese Unterschiede scheinen nicht mit der unterschiedlichen Glucosinolatzusammensetzung der beiden {\"O}kotypen im Zusammenhang zu stehen. Um das Verst{\"a}ndnis der Nichtwirtsresistenz von Arabidopsis gegen{\"u}ber P. syringae zu verbessern, k{\"o}nnen in zuk{\"u}nftigen Experimenten Doppel- und Triplemutanten hergestellt werden, die gleichzeitig Defekte in der zellwandabh{\"a}ngigen Abwehr (Lignin- und Callosebiosynthese) und in klassischen, SA-abh{\"a}ngigen Abwehrreaktionen aufweisen. Auch k{\"o}nnen Analysen des Genom-Polymorphismus und der Zusammensetzung von Sekund{\"a}rmetaboliten in den {\"O}kotypen Ler-0 und Col-0 zu einem besseren Verst{\"a}ndnis der Nichtwirtsresistenz f{\"u}hren. Die Resultate dieser Arbeit zeigen, dass ein lokaler, symptomfreier Kontakt von Arabidopsis-Bl{\"a}ttern mit Nichtwirtsbakterien, TTSS-defiziente Bakterien und allgemeine bakterielle Elicitoren (PAMPs) wie Flagellin und Lipopolysaccharide die systemisch erworbene Resistenz innerhalb der Gesamtpflanze hervorrufen. Die symptomlose systemische Resistenzreaktion findet in SAR-defizienten Mutanten nicht statt, wird jedoch in der Jasmonat-insensitiven jar1-Mutante, die keine ISR-Reaktion ausbilden kann, beobachtet. Durch Behandlung von Arabidopsis-Bl{\"a}ttern mit unterschiedlichen Inokuli von virulenten oder avirulenten P. syringae-St{\"a}mmen wurde auch eine deutliche Korrelation des Ausmaßes der SAR-Induktion mit der H{\"o}he der SA-Akkumulation oder der PR-Genexpression, aber nicht mit der Nekrosenbildung oder der JA-Produktion, am Infektionsort festgestellt. Diese Ergebnisse verdeutlichen, dass nicht die Hypersensitive Reaktion oder Gewebenekrosen, sondern m{\"o}glicherweise die St{\"a}rke bestimmter Abwehrreaktionen am Ort der Inokulation zur Ausl{\"o}sung der SAR beitragen. Die Befunde, dass die systemische Resistenz auch durch PAMPs und durch TTSS-defekte P. syringae-St{\"a}mme erh{\"o}ht wird, verdeutlicht die wichtige Rolle von allgemeinen Elicitoren bei der SAR-Induktion. In k{\"u}nftige Experimenten kann untersucht werden, ob verschiedene PAMPs die SAR in synergistischer Weise induzieren und ob allgemeine Elicitoren pilzlicher Herkunft SAR ausl{\"o}sen k{\"o}nnen. Weiterhin k{\"o}nnen die molekulare Prozesse spezifiziert werden, die stromabw{\"a}rts von PAMP-Erkennungsprozessen f{\"u}r die SAR-Ausbildung notwendig sind. In weiteren Experimenten k{\"o}nnte die Hypothese {\"u}berpr{\"u}ft werden, ob einzelner PAMPs als mobile SAR-Langstreckensignale fungieren k{\"o}nnen. Durch phytopathologische Charakterisierung von T-DNA-Knockout-Linien, die Defekte in Genen aufweisen, welche in Arabidopsis nach einer P. syringae-Infektion aufreguliert werden, konnte das FLAVIN-DEPENDENT MONOOXYGENASE1 (FMO1)-Gen als notwendige Komponente der SAR in Arabidopsis identifiziert werden. So bleiben die im Wildtyp induzierten systemischen Abwehrreaktionen und die Erh{\"o}hung der systemischen Resistenz nach lokaler Inokulation mit P. syringae in fmo1-Knockout-Pflanzen vollst{\"a}ndig aus. Weiterhin korreliert die systemische Expression des FMO1-Gens eng mit der SAR-Induktion. So gibt es bei allen Abwehrmutanten, die keine SAR nach Kontakt mit P. syringae ausbilden k{\"o}nnen, keine FMO1-Expression in distalen Bl{\"a}ttern inokulierter Pflanzen. Umgekehrt verh{\"a}lt es sich mit Arabidopsis-Linien, die die SAR ausbilden. Die erhaltenen Ergebnisse deuten darauf hin, dass FMO1 eine wichtige Komponente eines Signalverst{\"a}rkungszyklus darstellt, der in nichtinfizierten, systemischen Teilen der Pflanze wirkt, um die SAR zu erm{\"o}glichen. In k{\"u}nftigen Experimenten soll der postulierte Amplifizierungsmechanismus experimentell verifiziert werden. Die Konstruktion von transgenen Linien, die ein FMO1:GFP-Fusionsprodukt exprimieren, kann Informationen {\"u}ber die zellu{\"a}re Lokalisation des FMO1-Proteins liefern. Weiterhin k{\"o}nnen vergleichende Analysen der chemischen Zusammensetzung von Blattextrakten der fmo1 Knockout-Linien, von FMO1-{\"U}berexprimierern und von Wildtyp-Pflanzen zur Aufkl{\"a}rung der biochemischen Reaktion beitragen, die die FMO1-Monooxygenase katalysiert. In Anlehnung an die Funktion von yFMO, die die einzige Flavin-abh{\"a}ngige Monooxygenase der Hefe darstellt, kann {\"u}berpr{\"u}ft werden, ob FMO1 die korrekte Faltung von Proteinen am endoplasmatischen Retikulum vermittelt. Schließlich kann durch die Identifizierung weitere SAR-Gene nach der beschriebenen Strategie und durch funktionelle Charakterisierung der zugeh{\"o}rigen Proteine das Verst{\"a}ndnis der SAR-Reaktion auf molekularer Ebene weiter verbessert werden.}, subject = {Ackerschmalwand}, language = {en} } @article{MitesserWeisselStrohmetal.2007, author = {Mitesser, Oliver and Weissel, Norbert and Strohm, Erhard and Poethke, Hans-Joachim}, title = {Adaptive dynamic resource allocation in annual eusocial insects: Environmental variation will not necessarily promote graded control}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-45412}, year = {2007}, abstract = {Background: According to the classical model of Macevicz and Oster, annual eusocial insects should show a clear dichotomous "bang-bang" strategy of resource allocation; colony fitness is maximised when a period of pure colony growth (exclusive production of workers) is followed by a single reproductive period characterised by the exclusive production of sexuals. However, in several species graded investment strategies with a simultaneous production of workers and sexuals have been observed. Such deviations from the "bang-bang" strategy are usually interpreted as an adaptive (bet-hedging) response to environmental fluctuations such as variation in season length or food availability. To generate predictions about the optimal investment pattern of insect colonies in fluctuating environments, we slightly modified Macevicz and Oster's classical model of annual colony dynamics and used a dynamic programming approach nested into a recurrence procedure for the solution of the stochastic optimal control problem. Results: 1) The optimal switching time between pure colony growth and the exclusive production of sexuals decreases with increasing environmental variance. 2) Yet, for reasonable levels of environmental fluctuations no deviation from the typical bang-bang strategy is predicted. 3) Model calculations for the halictid bee Lasioglossum malachurum reveal that bet-hedging is not likely to be the reason for the graded allocation into sexuals versus workers observed in this species. 4) When environmental variance reaches a critical level our model predicts an abrupt change from dichotomous behaviour to graded allocation strategies, but the transition between colony growth and production of sexuals is not necessarily monotonic. Both, the critical level of environmental variance as well as the characteristic pattern of resource allocation strongly depend on the type of function used to describe environmental fluctuations. Conclusion: Up to now bet-hedging as an evolutionary response to variation in season length has been the main argument to explain field observations of graded resource allocation in annual eusocial insect species. However, our model shows that the effect of moderate fluctuations of environmental conditions does not select for deviation from the classical bang-bang strategy and that the evolution of graded allocation strategies can be triggered only by extreme fluctuations. Detailed quantitative observations on resource allocation in eusocial insects are needed to analyse the relevance of alternative explanations, e.g. logistic colony growth or reproductive conflict between queen and workers, for the evolution of graded allocation strategies.}, subject = {Insekten}, language = {en} } @phdthesis{Nayak2007, author = {Nayak, Arnab}, title = {Sumoylation Modulates NFATc1-mediated Lymphokine Gene Expression}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24722}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2007}, abstract = {Die Aktivit{\"a}t von Transkriptionsfaktoren kann durch die Modifikation mit SUMO positiv oder negativ beeinflusst werden, indem Protein-Protein-Interaktionen als auch die subzellul{\"a}re bzw. subnukle{\"a}re Lokalisation ver{\"a}ndert werden. In T-Zellen spielt die Familie der NFAT (Nuclear Factor of Activated T cells)-Transkriptionsfaktoren eine wichtige Rolle bei der Zytokingenregulation. NFATc1 wird durch die Verwendung zwei verschiedener Promotoren (P1 \& P2) bzw. Polyadenylierungsstellen (pA1 \& pA2) und alternativen Spleißens in sechs Isoformen exprimiert. Sie werden als NFATc1/alphaA, betaA, alphaB, betaB, alphaC und betaC bezeichnet, wobei alpha und beta sich auf die beiden unterschiedlichen 1. Exons und A, B, C sich auf die differentiell gespleißten und unterschiedlich langen C-Termini beziehen. Die NFATc1/A-Isoformen umfassen einen relativ kurzen C-Terminus, w{\"a}hrend die langen Isoformen B und C extra-C-terminale Peptide von 128 bzw. 246 Aminos{\"a}uren aufweisen. Um die spezifischen, biologischen Effekte der NFATc1-Isoformen zu untersuchen, wurde ein sog. ‚Yeast two Hybrid screen' mit einer humanen Milz-cDNA-Bibliothek und dem NFATc1/C-spezifischen C-Terminus durchgef{\"u}hrt. Am Ende wurden Ubc9 und PIAS1, Proteine, die an der Sumoylierung beteiligt sind, am h{\"a}ufigsten dedektiert. Anschließend konnte gezeigt werden, dass NFATc1 tats{\"a}chlich sumoyliert wird. Das Ausmaß an Sumoylierung ist Isoformen abh{\"a}ngig. W{\"a}hrend NFATc1/A, das eine einzige Sumoylierungsstelle besitzt, nur eine geringe Sumoylierung aufweist, f{\"u}hren die beiden zus{\"a}tzlichen Stellen in NFATc1/C zu einer effizienten Modifikation mit SUMO. Diese C-terminale Modifikation dirigiert NFATc1/C in SUMO-1-K{\"o}rperchen, die mit PML-nbs kolokalisieren. Dar{\"u}ber hinaus rekrutiert sumoyliertes NFATc1/C die transkriptionellen Korepressoren HDAC (sowohl Klasse I wie Klasse II HDACs), was zu einer signifikanten Verringerung der Histonazetylierung am IL-2-Promotor, eines wichtigen NFATc1-Zielgens, f{\"u}hrt. Konsequenterweise wurde eine Verminderung der IL-2-Produktion beobachtet, w{\"a}hrend NFATc1/C, das wegen Mutation der entscheidenden Lysine nicht mehr sumoyliert werden kann, ein dramatisch erh{\"o}htes Transaktivierungspotential am IL-2-Promotor aufwies. Das unterst{\"u}tzt unsere Daten, die mit einem IL-2-Promotor getriebenen Reporterassay gewonnen wurden und zeigen, dass das Transaktivierungspotential von NFATc1/C durch Sumoylierung herabgesetzt wird. Demzufolge {\"u}bt Sumoylierung einen negativen Effekt auf die transkriptionelle NFATc1-Aktivit{\"a}t aus. Immunfluoreszenzversuche zeigten, dass die Modifikation mit SUMO außerdem zur Relokalisation von NFATc1/C in transkriptionell inaktive, heterochromatische Regionen f{\"u}hrt, was durch die F{\"a}rbung von trimethyliertem Histon mit anti-H3K9 m3 nachgewiesen wurde. Interessanterweise war in Abwesenheit von Sumoylierung NFATc1 teilweise mit transkriptionellen Hotspots im Kern lokalisiert. Das mag zu dem h{\"o}heren Transkriptionspotential des nicht-sumoylierten NFATc1 beitragen. Es ist wichtig zu erw{\"a}hnen, dass die transkriptionelle Aktivit{\"a}t auf andere NFATc1-Zielgene durch die Sumoylierung von NFATc1 positiv verst{\"a}rkt war. Dies deutet auf einen nicht-universalen Effekt der Sumoylierung auf die NFATc1/C-Funktion hin. Demzufolge dirigiert Sumoylierung NFATc1 in Kernk{\"o}rperchen, wo es mit transkriptionellen Korepressoren interagiert und selbst ans Heterochromatin relokalisiert, was zu einer Repression der NFATc1/C vermittelten Transkription f{\"u}hrt. Als sehr wichtig erscheint, dass der Effekt der NFATc1/C-Sumoylierung Promotor spezifisch ist. Zusammengenommen ver{\"a}ndet die Modifikation mit SUMO die NFATc1-Funktion von einem Transaktivator zu einem DNA-Bindungsstellen spezifischen Repressor. Daher wird hier ein neuer regulatorischer Mechanismus aufgezeigt, der die Isoform spezifische NFAT-Funktion kontrolliert.}, language = {en} }