TY - JOUR A1 - Eulalio, Ana A1 - Fröhlich, Kathrin S. A1 - Mano, Miguel A1 - Giacca, Mauro A1 - Vogel, Jörg T1 - A Candidate Approach Implicates the Secreted Salmonella Effector Protein SpvB in P-Body Disassembly N2 - P-bodies are dynamic aggregates of RNA and proteins involved in several post-transcriptional regulation processes. Pbodies have been shown to play important roles in regulating viral infection, whereas their interplay with bacterial pathogens, specifically intracellular bacteria that extensively manipulate host cell pathways, remains unknown. Here, we report that Salmonella infection induces P-body disassembly in a cell type-specific manner, and independently of previously characterized pathways such as inhibition of host cell RNA synthesis or microRNA-mediated gene silencing. We show that the Salmonella-induced P-body disassembly depends on the activation of the SPI-2 encoded type 3 secretion system, and that the secreted effector protein SpvB plays a major role in this process. P-body disruption is also induced by the related pathogen, Shigella flexneri, arguing that this might be a new mechanism by which intracellular bacterial pathogens subvert host cell function. KW - Salmonella KW - RNS Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68928 ER - TY - JOUR A1 - Niewalda, Thomas A1 - Völler, Thomas A1 - Eschbach, Claire A1 - Ehmer, Julia A1 - Wen-Chuang, Chou A1 - Timme, Marc A1 - Fiala, André A1 - Gerber, Bertram T1 - A Combined Perceptual, Physico-Chemical, and Imaging Approach to 'Odour-Distances' Suggests a Categorizing Function of the Drosophila Antennal Lobe JF - PLoS One N2 - How do physico-chemical stimulus features, perception, and physiology relate? Given the multi-layered and parallel architecture of brains, the question specifically is where physiological activity patterns correspond to stimulus features and/or perception. Perceived distances between six odour pairs are defined behaviourally from four independent odour recognition tasks. We find that, in register with the physico-chemical distances of these odours, perceived distances for 3octanol and n-amylacetate are consistently smallest in all four tasks, while the other five odour pairs are about equally distinct. Optical imaging in the antennal lobe, using a calcium sensor transgenically expressed in only first-order sensory or only second-order olfactory projection neurons, reveals that 3-octanol and n-amylacetate are distinctly represented in sensory neurons, but appear merged in projection neurons. These results may suggest that within-antennal lobe processing funnels sensory signals into behaviourally meaningful categories, in register with the physico-chemical relatedness of the odours. KW - organization KW - cameleon KW - honeybee KW - map KW - neurons KW - reveals KW - melanogaster KW - mushroom body KW - spatial representation KW - olfactory information Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133510 VL - 6 IS - 9 ER - TY - JOUR A1 - Niewalda, Thomas A1 - Völler, Thomas A1 - Eschbach, Claire A1 - Ehmer, Julia A1 - Chou, Wen-Chuang A1 - Timme, Marc A1 - Fiala, André A1 - Gerber, Bertram T1 - A Combined Perceptual, Physico-Chemical, and ImagingApproach to ‘Odour-Distances’ Suggests a CategorizingFunction of the Drosophila Antennal Lobe N2 - How do physico-chemical stimulus features, perception, and physiology relate? Given the multi-layered and parallel architecture of brains, the question specifically is where physiological activity patterns correspond to stimulus features and/ or perception. Perceived distances between six odour pairs are defined behaviourally from four independent odour recognition tasks. We find that, in register with the physico-chemical distances of these odours, perceived distances for 3-octanol and n-amylacetate are consistently smallest in all four tasks, while the other five odour pairs are about equally distinct. Optical imaging in the antennal lobe, using a calcium sensor transgenically expressed in only first-order sensory or only second-order olfactory projection neurons, reveals that 3-octanol and n-amylacetate are distinctly represented in sensory neurons, but appear merged in projection neurons. These results may suggest that within-antennal lobe processing funnels sensory signals into behaviourally meaningful categories, in register with the physico-chemical relatedness of the odours. KW - Drosophila Antennal Lobe Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-74769 ER - TY - THES A1 - Rüth, Michael T1 - A Comprehensive Study of Dilute Magnetic Semiconductor Resonant Tunneling Diodes T1 - Umfassende Untersuchung von resonanten Tunneldioden aus verdünnt-magnetischen Halbleitern N2 - We investigate transport measurements on all II-VI semiconductor resonant tunneling diodes (RTDs). Being very versatile, the dilute magnetic semiconductor (DMS) system (Zn,Be,Mn,Cd)Se is a perfect testbed for various spintronic device designs, as it allows for separate control of electrical and magnetic properties. In contrast to the ferromagnetic semiconductor (Ga,Mn)As, doping ZnSe with Mn impurities does not alter the electrical properties of the semiconductor, as the magnetic dopant is isoelectric in the ZnSe host. N2 - Diese Doktorarbeit befasst sich mit Transportmessungen an resonanten Tunneldioden (engl. resonant tunneling diode, RTD), welche vollst� andig aus II-VI Halbleitermaterial bestehen. Das verd� unnt magnetische (engl. dilute magnetic semiconductor, DMS) Halbleitermaterialsystem (Zn,Be,Mn,Cd)Se ist sehr vielseitig und eignet sich hervorragend als Testsystem f� ur diverse Spintronik Bauelemente, denn magnetische und elektrische Eigenschaften lassen sich getrennt voneinander einstellen. Im Gegensatz zum ferromagnetischen Halbleiter (Ga,Mn)As ver� andert das Dotieren von ZnSe mit Mn nicht die elektrischen Eigenschaften des Halbleiters. KW - Semimagnetischer Halbleiter KW - Resonanz-Tunneleffekt KW - Halbleiter KW - Resonante Tunneldioden KW - Spintronik KW - dilute magnetic semiconductors KW - spintronics KW - resonant tunneling diodes Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-71472 ER - TY - JOUR A1 - Kistler, Andreas D. A1 - Siwy, Justyna A1 - Frank, Breunig A1 - Jeevaratnam, Praveen A1 - Scherl, Alexander A1 - Mullen, William A1 - Warnock, David G. A1 - Wanner, Christoph A1 - Hughes, Derralynn A. A1 - Mischak, Harald A1 - Wüthrich, Rudolf P. A1 - Serra, Andreas L. T1 - A Distinct Urinary Biomarker Pattern Characteristic of Female Fabry Patients That Mirrors Response to Enzyme Replacement Therapy JF - PLoS ONE N2 - Female patients affected by Fabry disease, an X-linked lysosomal storage disorder, exhibit a wide spectrum of symptoms, which renders diagnosis, and treatment decisions challenging. No diagnostic test, other than sequencing of the alpha-galactosidase A gene, is available and no biomarker has been proven useful to screen for the disease, predict disease course and monitor response to enzyme replacement therapy. Here, we used urine proteomic analysis based on capillary electrophoresis coupled to mass spectrometry and identified a biomarker profile in adult female Fabry patients. Urine samples were taken from 35 treatment-naive female Fabry patients and were compared to 89 age-matched healthy controls. We found a diagnostic biomarker pattern that exhibited 88.2% sensitivity and 97.8% specificity when tested in an independent validation cohort consisting of 17 treatment-naive Fabry patients and 45 controls. The model remained highly specific when applied to additional control patients with a variety of other renal, metabolic and cardiovascular diseases. Several of the 64 identified diagnostic biomarkers showed correlations with measures of disease severity. Notably, most biomarkers responded to enzyme replacement therapy, and 8 of 11 treated patients scored negative for Fabry disease in the diagnostic model. In conclusion, we defined a urinary biomarker model that seems to be of diagnostic use for Fabry disease in female patients and may be used to monitor response to enzyme replacement therapy. KW - Chronic kidney-disease KW - Onset hypertrophic cardiomyopathy KW - Mass-spectrometry KW - Alpha-galactosidase KW - Hemodialysis-patients KW - Clinical proteomics KW - Young-patients KW - Discovery KW - Globotriaosylceramide KW - Prevalence Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133526 VL - 6 IS - 6 ER - TY - BOOK A1 - Falk, Michael A1 - Marohn, Frank A1 - Michel, René A1 - Hofmann, Daniel A1 - Macke, Maria A1 - Tewes, Bernward A1 - Dinges, Peter A1 - Spachmann, Christoph A1 - Englert, Stefan T1 - A First Course on Time Series Analysis : Examples with SAS N2 - The analysis of real data by means of statistical methods with the aid of a software package common in industry and administration usually is not an integral part of mathematics studies, but it will certainly be part of a future professional work. The present book links up elements from time series analysis with a selection of statistical procedures used in general practice including the statistical software package SAS. Consequently this book addresses students of statistics as well as students of other branches such as economics, demography and engineering, where lectures on statistics belong to their academic training. But it is also intended for the practician who, beyond the use of statistical tools, is interested in their mathematical background. Numerous problems illustrate the applicability of the presented statistical procedures, where SAS gives the solutions. The programs used are explicitly listed and explained. No previous experience is expected neither in SAS nor in a special computer system so that a short training period is guaranteed. This book is meant for a two semester course (lecture, seminar or practical training) where the first three chapters can be dealt within the first semester. They provide the principal components of the analysis of a time series in the time domain. Chapters 4, 5 and 6 deal with its analysis in the frequency domain and can be worked through in the second term. In order to understand the mathematical background some terms are useful such as convergence in distribution, stochastic convergence, maximum likelihood estimator as well as a basic knowledge of the test theory, so that work on the book can start after an introductory lecture on stochastics. Each chapter includes exercises. An exhaustive treatment is recommended. Chapter 7 (case study) deals with a practical case and demonstrates the presented methods. It is possible to use this chapter independent in a seminar or practical training course, if the concepts of time series analysis are already well understood. This book is consecutively subdivided in a statistical part and an SAS-specific part. For better clearness the SAS-specific parts are highlighted. This book is an open source project under the GNU Free Documentation License. KW - Zeitreihenanalyse KW - Box-Jenkins-Verfahren KW - SAS KW - Zustandsraummodelle KW - Time Series Analysis KW - State-Space Models KW - Frequency Domain KW - Box–Jenkins Program Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-56489 N1 - Version: 2011-March-01 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - A Knowledge-based Hybrid Statistical Classifier for Reconstructing the Chronology of the Quran N2 - Computationally categorizing Quran’s chapters has been mainly confined to the determination of chapters’ revelation places. However this broad classification is not sufficient to effectively and thoroughly understand and interpret the Quran. The chronology of revelation would not only improve comprehending the philosophy of Islam, but also the easiness of implementing and memorizing its laws and recommendations. This paper attempts estimating possible chapters’ dates of revelation through their lexical frequency profiles. A hybrid statistical classifier consisting of stemming and clustering algorithms for comparing lexical frequency profiles of chapters, and deriving dates of revelation has been developed. The classifier is trained using some chapters with known dates of revelation. Then it classifies chapters with uncertain dates of revelation by computing their proximity to the training ones. The results reported here indicate that the proposed methodology yields usable results in estimating dates of revelation of the Quran’s chapters based on their lexical contents. KW - Text Mining KW - Maschinelles Lernen KW - text categorization KW - Bayesian classifier KW - distance-based classifier KW - Quran Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-54712 ER - TY - THES A1 - Mark, Stefan T1 - A Magnetic Semiconductor based Non-Volatile Memory and Logic Element T1 - Ein auf magnetischen Halbleiter basierendes nicht-flüchtiges Speicher- und Logik-Element N2 - For the realization of a programmable logic device, or indeed any nanoscale device, we need a reliable method to probe the magnetization direction of local domains. For this purpose we extend investigations on the previously discovered tunneling anisotropic magneto resistance effect (TAMR) by scaling the pillar size from 100 µm down to 260 nm. We start in chapter 4 with a theoretical description of the TAMR effect and show experimental data of miniaturized pillars in chapter 5. With such small TAMR probes we are able to locally sense the magnetization on the 100 nm scale. Sub-micron TAMR and anisotropic magneto resistance (AMR) measurements of sub-millimeter areas show that the behavior of macroscopic (Ga,Mn)As regions is not that of a true macrospin, but rather an ensemble average of the behavior of many nearly identical macrospins. This shows that the magnetic anisotropies of the local regions are consistent with the behavior extracted from macroscopic characterization. A fully electrically controllable read-write memory device out the ferromagnetic semiconductor (Ga,Mn)As is presented in chapter 6. The structure consists of four nanobars which are connected to a circular center region. The first part of the chapter describes the lithography realization of the device. We make use of the sub-micron TAMR probes to read-out the magnetization state of a 650 nm central disk. Four 200 nm wide nanobars are connected to the central disk and serve as source and drain of a spin-polarized current. With the spin-polarized current we are able to switch the magnetization of the central disk by means of current induced switching. Injecting polarized holes with a spin angular momentum into a magnetic region changes the magnetization direction of the region due to the p-d exchange interaction between localized Mn spins and itinerant holes. The magnetization of the central disk can be controlled fully electrically and it can serve as one bit memory element as part of a logic device. In chapter 7 we discuss the domain wall resistance in (Ga,Mn)As. At the transition from nanobars to central disk we are able to generate 90° and 180° domain walls and measure their resistance. The results presented from chapter 5 to 7 combined with the preexisting ultracompact (Ga,Mn)As-based memory cell of ref. [Papp 07c] are the building blocks needed to realize a fully functioning programmable logic device. The work of ref. [Papp 07c] makes use of lithographically engineered strain relaxation to produce a structure comprised of two nanobars with mutually orthogonal uniaxial easy axes, connected by a narrow constriction. Measurements showed that the resistance of the constriction depends on the relative orientation of the magnetization in the two bars. The programmable logic device consists of two central disks connected by a small constriction. The magnetization of the two central disks are used as the input bits and the constriction serves as the output during the logic operation. The concept is introduced in the end of chapter 6 and as an example for a logic operation an XOR gate is presented. The functionality of the programmable logic scheme presented here can be straightforwardly extended to produce multipurpose functional elements, where the given geometry can be used as various different computational elements depending on the number of input bits and the chosen electrical addressing. The realization of such a programmable logic device is shown in chapter 8, where we see that the constriction indeed can serve as a output of the logic operation because its resistance is dependent on the relative magnetization state of both disks. Contrary to ref. [Papp 07c], where the individual magnetic elements connected to the constriction only have two non-volatile magnetic states, each disk in our scheme connected to the constriction has four non-volatile magnetic states. Switching the magnetization of a central disk with an electrical current does not only change the TAMR read-out of the respective disk, it also changes the resistance of the constriction. The resistance polar plot of the constriction maps the relative magnetization states of the individual disks. The presented device design serves as an all-electrical, all-semiconductor logic element. It combines a memory cell and data processing in a single monolithic paradigm. N2 - Für die Realisierung eines programmierbaren Logikelements oder beliebiger nanometer großer Bauteile, brauchen wir eine verlässlige Methode, um die Magnetisierungsrichtung lokaler Domänen auzulesen. Dafür erweitern wir die Untersuchungen an TAMR (tunneling magneto resistance) Strukturen und skalieren die Fläche des Tunnelkontakts von 100 µm auf 260 nm. In Kapitel 4 geben wir zunächst eine theoretische Beschreibung des TAMR Effekts und zeigen darauf im folgenden Kapitel 5 experimentelle Daten der miniaturisierten Tunnelkontakte. Mit diesen TAMR-Kontakten ist es möglich die Magnetisierung lokal in einer Grössenordnung von 100 nm zu detektieren. Sub-micron TAMR-Messungen und anisotrope Magnetowiderstandmessungen (AMR) an sub-millimeter Gebieten zeigen, dass das Verhalten von makrokopischen (Ga,Mn)As nicht das eines Makrospins ist, sondern ein Ensembledurchschnitt von vielen fast identischen Makrospins. Dieses Ergebnis ist mit der makroskopischen Beschreibung der lokalen magnetischen Aniotropien konform.\\ Ein rein elektrisch kontrollierbares Read-Write Speicherelement aus dem ferromagnetischen Halbleiter (Ga,Mn)As wird in Kapitel 6 gezeigt. Das Element besteht aus vier 200 nm breiten Streifen, die mit einer kreisförmigen zentralen Disc verbunden sind. Der erste Teil des Kapitels beschreibt die einzelnen Lithographieschritte zur Herstellung des Elements. Zum Auslesen der Magnetisierungsrichtung der zentralen Disc mit einem Durchmesser von 650 nm verwenden wir einen miniaturisierten TAMR-Kontakt. Die 200 nm breiten Streifen dienen als Quelle eines spinpolarisierten Stromes in die zentrale Disc. Das Injezieren von polarisierten Löchern mit einem Spin-Drehimpuls in eine magnetische Region verändert die Magnetisierung der Region durch p-d Austauschwechselwirkung zwischen lokalisierten Mn-Spins und den Löchern. Die Magnetisierung der zentralen Disc kann rein elektrisch kontrolliert werden and als Bit eines Logikelementes verwendet werden. In Kapitel 7 untersuchen wir den Domänenwiderstand in (Ga,Mn)As. Am Übergang von den Streifen zur zentralen Disc ist es möglich 90°- und 180° Domänenwände zu erzeugen und deren Widerstand zu messen.\\ Die Ergebnisse von Kapitel 5 bis 7, kombiniert mit dem bereits existierenden Ergebnissen einer ultrakompakten (Ga,Mn)As-basierenden Speicherzelle von Ref. [Papp 07c], sind die Schlüsselelemente die man zur Realisierung eines programmierbaren Logikelements benötigt. Die Arbeit von Referenz [Papp 07c] nutzt Lithographie induzierte Deformationsrelaxation, um eine Struktur zu erzeugen, die aus zwei senkrechten Streifen besteht und durch eine Verengung verbunden sind. Der Widerstand dieser Verengung ist von der relativen Magnetisierungsorientierung der beiden Streifen abhängig. Das programmierbare Logikelement besteht aus zwei zentralen Discs, die mittels einer schmalen Verengung verbunden sind. Die Magnetisierung der beiden zentralen Discs dienen als Eingänge und die Verengung als Ausgang während der Logikoperation. Das Konzept wird am Ende des sechsten Kapitels eingeführt und als Beispiel für eine Logikoperation wird ein XOR-Gate präsentiert. Die Funktionalität des hier gezeigten programmierbaren Logikschemas kann Problemlos auf ein multifunktionales Element erweitert werden. Diese Geometrie kann abhängig von der Anzahl der Eingänge und der gewählten Adressierung für verschiedene Rechenelemente genutzt werden. \\ Die Realisierung eines programmierbaren Logikelements ist in Kapitel 8 gezeigt. Der Widerstand der Verengung hängt von der relativen Magnetisierungsrichtung der beiden zentralen Discs ab und wird als Ausgang während der Logikoperation verwendet. Im Gegensatz zu Referenz [Papp 07c], indem die einzelnen über die Verengung verbundenen magnetischen Elemente jeweils nur zwei nicht-flüchtige magnetische Zustände besitzen, hat jede zentrale Disc in unserem Schema vier nicht-flüchtige magnetische Zustände. Das Verändern der Magnetisierungsrichtung einer zentralen Disc durch einen elektrischen Strom kann durch den jeweiligen TAMR-Kontakt und durch die Widerstandänderung der Verengung gemessen werden. Der Widerstands-Fingerabdruck (resistance polar plot) der Verengung zeigt die verschiedenen relativen Magnetisierungszutände der zentralen Discs.\\ Das hier präsentierte Konzept dient als reines Halbleiter und rein-elektrisches Logikelement. Es kombiniert eine Speicherzelle und Datenverarbeitung in einem neuartigen monolithischen Bauelement. KW - Magnetischer Halbleiter KW - Magnetische Halbleiter KW - Magnetische Anisotropien KW - Spinelektronik KW - magnetic semiconductors KW - magnetic anisotropy KW - Magnetic properties of thin films interfaces KW - Spinelectronic KW - Magnetische Anisotropie KW - Spintronik Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-71223 ER - TY - JOUR A1 - Lin, Hang T1 - A Mixed Bag of Results: Village Elections in Contemporary China N2 - While there is only little transformation to the absolute power of the party-state to be detected, some grassroots democratic experiments, however, are receiving enormous attention of the world, especially village elections. Nevertheless, this preliminary exercise of democracy is widely characterized as a mixed bag of results. Since its first conduction, it has experienced immense development and bought great impact not only on different rural political institutions, but also on common mass villagers, as well as changes to the local governance. But at the same time, the limitations of the factual effectiveness of these elections can hardly be underestimated and such aspects as the standardization of electoral procedures are still to be further improved. Moreover, given the wide variations across Chinese countryside and the strong oppositions from all levels, the future of China’s village elections remain hard to gauge. KW - China KW - Politik KW - Chinese politics KW - Village election KW - Local governance KW - Rural politics Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68684 ER - TY - JOUR A1 - Sommer, Claudia A1 - Richter, Helmut A1 - Rogausch, Jan P. A1 - Frettloh, Jule A1 - Lungenhausen, Margitta A1 - Maier, Christoph T1 - A modified score to identify and discriminate neuropathic pain: a study on the German version of the neuropathic pain symptom inventory (NPSI) N2 - Background: Neuropathic pain must be correctly diagnosed for optimal treatment. The questionnaire named Neuropathic Pain Symptom Inventory (NPSI) was developed in its original French version to evaluate the different symptoms of neuropathic pain. We hypothesized that the NPSI might also be used to differentiate neuropathic from non-neuropathic pain. Methods: We translated the NPSI into German using a standard forward-backward translation and administered it in a case-control design to patients with neuropathic (n = 68) and non-neuropathic pain (headache and osteoarthritis, n = 169) to validate it and to analyze its discriminant properties, its sensitivity to change, and to detect neuropathic pain subgroups with distinct profiles. Results: Using a sum score (the NPSI-G score), we found sensitivity to change (r between 0.37 and 0.5 for pain items of the graded chronic pain scale) and could distinguish between neuropathic and other pain on a group basis, but not for individual patients. Post hoc development of a discriminant score with optimized diagnostic properties to distinguish neuropathic pain from non-neuropathic pain resulted in an instrument with high sensitivity (91%) and acceptable specificity (70%). We detected six different pain profiles in the patient group with neuropathic pain; three profiles were found to be distinct. Conclusions: The NPSI-G potentially combines the properties of a diagnostic tool and an instrument to identify subtypes of neuropathic pain. KW - Neuralgie KW - NPSI Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68716 ER - TY - JOUR A1 - Schramm, Sabine A1 - Fraune, Johanna A1 - Naumann, Ronald A1 - Hernandez-Hernandez, Abrahan A1 - Höög, Christer A1 - Cooke, Howard J. A1 - Alsheimer, Manfred A1 - Benavente, Ricardo T1 - A Novel Mouse Synaptonemal Complex Protein Is Essential for Loading of Central Element Proteins, Recombination, and Fertility N2 - The synaptonemal complex (SC) is a proteinaceous, meiosis-specific structure that is highly conserved in evolution. During meiosis, the SC mediates synapsis of homologous chromosomes. It is essential for proper recombination and segregation of homologous chromosomes, and therefore for genome haploidization. Mutations in human SC genes can cause infertility. In order to gain a better understanding of the process of SC assembly in a model system that would be relevant for humans, we are investigating meiosis in mice. Here, we report on a newly identified component of the murine SC, which we named SYCE3. SYCE3 is strongly conserved among mammals and localizes to the central element (CE) of the SC. By generating a Syce3 knockout mouse, we found that SYCE3 is required for fertility in both sexes. Loss of SYCE3 blocks synapsis initiation and results in meiotic arrest. In the absence of SYCE3, initiation of meiotic recombination appears to be normal, but its progression is severely impaired resulting in complete absence of MLH1 foci, which are presumed markers of crossovers in wild-type meiocytes. In the process of SC assembly, SYCE3 is required downstream of transverse filament protein SYCP1, but upstream of the other previously described CE–specific proteins. We conclude that SYCE3 enables chromosome loading of the other CE–specific proteins, which in turn would promote synapsis between homologous chromosomes. KW - Maus KW - Genetik KW - Cytologie Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68895 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - A Rule-based Statistical Classifier for Determining a Base Text and Ranking Witnesses In Textual Documents Collation Process N2 - Given a collection of diverging documents about some lost original text, any person interested in the text would try reconstructing it from the diverging documents. Whether it is eclecticism, stemmatics, or copy-text, one is expected to explicitly or indirectly select one of the documents as a starting point or as a base text, which could be emended through comparison with remaining documents, so that a text that could be designated as the original document is generated. Unfortunately the process of giving priority to one of the documents also known as witnesses is a subjective approach. In fact even Cladistics, which could be considered as a computer-based approach of implementing stemmatics, does not present or recommend users to select a certain witness as a starting point for the process of reconstructing the original document. In this study, a computational method using a rule-based Bayesian classifier is used, to assist text scholars in their attempts of reconstructing a non-existing document from some available witnesses. The method developed in this study consists of selecting a base text successively and collating it with remaining documents. Each completed collation cycle stores the selected base text and its closest witness, along with a weighted score of their similarities and differences. At the end of the collation process, a witness selected more often by majority of base texts is considered as the probable base text of the collection. Witnesses’ scores are weighted using a weighting system, based on effects of types of textual modifications on the process of reconstructing original documents. Users have the possibility to select between baseless and base text collation. If a base text is selected, the task is reduced to ranking the witnesses with respect to the base text, otherwise a base text as well as ranking of the witnesses with respect to the base text are computed and displayed on a histogram. KW - Textvergleich KW - Text Mining KW - Gothenburg Modell KW - Bayes-Klassifikator KW - Textual document collation KW - Base text KW - Gothenburg model KW - Bayesian classifier KW - Textual alterations weighting system Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57465 ER - TY - JOUR A1 - Katja, Schulze A1 - López, Diana A. A1 - Tillich, Ulrich M. A1 - Frohme, Marcus T1 - A simple viability analysis for unicellular cyanobacteria using a new autofluorescence assay, automated microscopy, and ImageJ JF - BMC Biotechnology N2 - Background Currently established methods to identify viable and non-viable cells of cyanobacteria are either time-consuming (eg. plating) or preparation-intensive (eg. fluorescent staining). In this paper we present a new and fast viability assay for unicellular cyanobacteria, which uses red chlorophyll fluorescence and an unspecific green autofluorescence for the differentiation of viable and non-viable cells without the need of sample preparation. Results The viability assay for unicellular cyanobacteria using red and green autofluorescence was established and validated for the model organism Synechocystis sp. PCC 6803. Both autofluorescence signals could be observed simultaneously allowing a direct classification of viable and non-viable cells. The results were confirmed by plating/colony count, absorption spectra and chlorophyll measurements. The use of an automated fluorescence microscope and a novel ImageJ based image analysis plugin allow a semi-automated analysis. Conclusions The new method simplifies the process of viability analysis and allows a quick and accurate analysis. Furthermore results indicate that a combination of the new assay with absorption spectra or chlorophyll concentration measurements allows the estimation of the vitality of cells. KW - variability analysis KW - unicellular cyanobacteria KW - autofluorescence Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-137735 VL - 11 IS - 118 ER - TY - JOUR A1 - Eckhardt, Manon A1 - Anders, Maria A1 - Muranyi, Walter A1 - Heilemann, Mike A1 - Krijnse-Locker, Jacomine A1 - Müller, Barbara T1 - A SNAP-Tagged Derivative of HIV-1-A Versatile Tool to Study Virus-Cell Interactions JF - PLoS ONE N2 - Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and their maturation kinetics. Furthermore, several independent FP-tagged constructs have to be cloned and characterized in order to obtain spectral variations suitable for multi-color imaging setups. In contrast, the so-called SNAP-tag represents a genetically encoded non-fluorescent tag which mediates specific covalent coupling to fluorescent substrate molecules in a self-labeling reaction. Fusion of the SNAP-tag to the protein of interest allows specific labeling of the fusion protein with a variety of synthetic dyes, thereby offering enhanced flexibility for fluorescence imaging approaches. Here we describe the construction and characterization of the HIV derivative HIV(SNAP), which carries the SNAP-tag as an additional domain within the viral structural polyprotein Gag. Introduction of the tag close to the C-terminus of the matrix domain of Gag did not interfere with particle assembly, release or proteolytic virus maturation. The modified virions were infectious and could be propagated in tissue culture, albeit with reduced replication capacity. Insertion of the SNAP domain within Gag allowed specific staining of the viral polyprotein in the context of virus producing cells using a SNAP reactive dye as well as the visualization of individual virions and viral budding sites by stochastic optical reconstruction microscopy. Thus, HIV(SNAP) represents a versatile tool which expands the possibilities for the analysis of HIV-cell interactions using live cell imaging and sub-diffraction fluorescence microscopy. KW - Human-immunodeficiency-virus KW - Fusion proteins KW - Live cells KW - Fluorescence microscopy KW - Stimulated-emission KW - Plasma-membrane KW - Living cells KW - Real-time KW - TYPE-1 KW - GAG Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133534 VL - 6 IS - 7 ER - TY - JOUR A1 - Fischer, Roman A1 - Maier, Olaf A1 - Siegemund, Martin A1 - Wajant, Harald A1 - Scheurich, Peter A1 - Pfizenmaier, Klaus T1 - A TNF Receptor 2 Selective Agonist Rescues Human Neurons from Oxidative Stress-Induced Cell Death JF - PLoS ONE N2 - Tumor necrosis factor (TNF) plays a dual role in neurodegenerative diseases. Whereas TNF receptor (TNFR) 1 is predominantly associated with neurodegeneration, TNFR2 is involved in tissue regeneration and neuroprotection. Accordingly, the availability of TNFR2-selective agonists could allow the development of new therapeutic treatments of neurodegenerative diseases. We constructed a soluble, human TNFR2 agonist (TNC-scTNF(R2)) by genetic fusion of the trimerization domain of tenascin C to a TNFR2-selective single-chain TNF molecule, which is comprised of three TNF domains connected by short peptide linkers. TNC-scTNFR2 specifically activated TNFR2 and possessed membrane-TNF mimetic activity, resulting in TNFR2 signaling complex formation and activation of downstream signaling pathways. Protection from neurodegeneration was assessed using the human dopaminergic neuronal cell line LUHMES. First we show that TNC-scTNF(R2) interfered with cell death pathways subsequent to H(2)O(2) exposure. Protection from cell death was dependent on TNFR2 activation of the PI3K-PKB/Akt pathway, evident from restoration of H(2)O(2) sensitivity in the presence of PI3K inhibitor LY294002. Second, in an in vitro model of Parkinson disease, TNC-scTNFR(2) rescues neurons after induction of cell death by 6-OHDA. Since TNFR2 is not only promoting anti-apoptotic responses but also plays an important role in tissue regeneration, activation of TNFR2 signaling by TNC-scTNF(R2) appears a promising strategy to ameliorate neurodegenerative processes. KW - Tumor-necrosis-factor KW - Glutamate-induced excitotoxicity KW - Single-chain TNF KW - Kappa-B pathway KW - Parkinsons-disease KW - Signaling complex KW - Activation KW - Apoptosis KW - Dopamine KW - Ligand Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133552 VL - 6 IS - 11 ER - TY - JOUR A1 - Rieber, Nikolaus A1 - Graf, Anna A1 - Hartl, Dominik A1 - Urschel, Simon A1 - Belohradsky, Bernd H. A1 - Liese, Johannes T1 - Acellular Pertussis Booster in Adolescents Induces Th1 and Memory CD8+ T Cell Immune Response N2 - In a number of countries, whole cell pertussis vaccines (wcP) were replaced by acellular vaccines (aP) due to an improved reactogenicity profile. Pertussis immunization leads to specific antibody production with the help of CD4+ T cells. In earlier studies in infants and young children, wcP vaccines selectively induced a Th1 dominated immune response, whereas aP vaccines led to a Th2 biased response. To obtain data on Th1 or Th2 dominance of the immune response in adolescents receiving an aP booster immunization after a wcP or aP primary immunization, we analyzed the concentration of Th1 (IL-2, TNF-a, INF-c) and Th2 (IL-4, IL-5, IL-10) cytokines in supernatants of lymphocyte cultures specifically stimulated with pertussis antigens. We also investigated the presence of cytotoxic T cell responses against the facultative intracellular bacterium Bordetella pertussis by quantifying pertussis-specific CD8+ T cell activation following the aP booster immunization. Here we show that the adolescent aP booster vaccination predominantly leads to a Th1 immune response based on IFNgamma secretion upon stimulation with pertussis antigen, irrespective of a prior whole cell or acellular primary vaccination. The vaccination also induces an increase in peripheral CD8+CD69+ activated pertussis-specific memory T cells four weeks after vaccination. The Th1 bias of this immune response could play a role for the decreased local reactogenicity of this adolescent aP booster immunization when compared to the preceding childhood acellular pertussis booster. Pertussis-specific CD8+ memory T cells may contribute to protection against clinical pertussis. KW - Jugend KW - Keuchhusten Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68960 ER - TY - JOUR A1 - Rudert, Maximilian A1 - Holzapfel, Boris Michael A1 - Jakubietz, Michael T1 - Adjuvant Radiotherapy JF - Deutsches Ärzteblatt International N2 - No abstract available. KW - Soft-tissue sarcoma Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133571 VL - 108 IS - 33 ER - TY - JOUR A1 - Song, Ning-Ning A1 - Xiu, Jian-Bo A1 - Huang, Ying A1 - Chen, Jia-Yin A1 - Zhang, Lei A1 - Gutknecht, Lise A1 - Lesch, Klaus Peter A1 - Li, He A1 - Ding, Yu-Qiang T1 - Adult Raphe-Specific Deletion of Lmx1b Leads to Central Serotonin Deficiency JF - PLoS ONE N2 - The transcription factor Lmx1b is essential for the differentiation and survival of central serotonergic (5-HTergic) neurons during embryonic development. However, the role of Lmx1b in adult 5-HTergic neurons is unknown. We used an inducible Cre-LoxP system to selectively inactivate Lmx1b expression in the raphe nuclei of adult mice. Pet1-CreER(T2) mice were generated and crossed with Lmx1b(flox/flox) mice to obtain Pet1-CreER(T2); Lmx1b(flox/flox) mice (which termed as Lmx1b iCKO). After administration of tamoxifen, the level of 5-HT in the brain of Lmx1b iCKO mice was reduced to 60% of that in control mice, and the expression of tryptophan hydroxylase 2 (Tph2), serotonin transporter (Sert) and vesicular monoamine transporter 2 (Vmat2) was greatly down-regulated. On the other hand, the expression of dopamine and norepinephrine as well as aromatic L-amino acid decarboxylase (Aadc) and Pet1 was unchanged. Our results reveal that Lmx1b is required for the biosynthesis of 5-HT in adult mouse brain, and it may be involved in maintaining normal functions of central 5-HTergic neurons by regulating the expression of Tph2, Sert and Vmat2. KW - Molecular-genetics KW - Sonic hedgehog KW - Neurons KW - Mice KW - Brain KW - Expression KW - System KW - PET-1 KW - Transporter KW - Disorders Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133581 VL - 6 IS - 1 ER - TY - THES A1 - Schnabel, Eva T1 - Alcohol and driving-related performance - A comprehensive meta-analysis focusing the significance of the non-significant T1 - Alkohol und fahrrelevante Leistungen - Eine umfassende Metaanalyse N2 - The present work reviews the experimental literature on the acute effects of alcohol on human behaviour related to driving performance. A meta-analysis was conducted which includes studies published between 1954 and 2007 in order to provide a comprehensive knowledge of the substance alcohol. 450 studies reporting 5,300 findings were selected from over 12,000 references after applying certain in- and exclusion criteria. Thus, the present meta-analysis comprises far more studies than reviews on alcohol up to now. In the selected studies, different performance tests were conducted which were relevant for driving. The classification system used in this work assigns these tests to eight categories. The main categories consist of several sub categories classifying the tasks more precisely. The main categories were: (1) visual functions, (2) attention (including vigilance), (3) divided attention, (4) en-/decoding (including information processing and memory), (5) reaction time (including simple reaction time and choice reaction time), (6) psychomotor skills, (7) tracking and (8) driving. In addition to the performance aspect, the classification system takes into account mood and social behaviour variables related to driving safety like tiredness or aggression. Following the evaluation method of vote-counting, the number of significant findings and the number of non-significant findings were summarised per blood alcohol concentration (BAC) group. Thereby, a quantitative estimation of the effects of alcohol depending on the BAC was established, the so-called impairment function, which shows the percentage of significantly impaired findings. In order to provide a general overview of alcohol effects on driving-related performance, a global impairment function was established by aggregating all performance findings. The function is nearly linear with about 30% significant findings at a BAC of 0.05% and 50% significant findings at a BAC of 0.08%. In addition, more specific impairment functions considering only the findings of the single behavioural categories were calculated. The results revealed that impairment depends not only on the BAC, but also clearly differs between most of the performance categories. Tracking and driving performance were most affected by alcohol with impairment beginning at very low BACs of 0.02%. Also psychomotor skills were considerably affected by rather low BACs. Impairment of visual functions and information processing occurred at BACs of 0.04% and increased substantially with higher BACs. Impairment in memory tests could be found with very low BACs of 0.02%, but varied depending on the kind of memory. Performance decrements in divided attention tests could also be found with very low BACs in some studies. Attention started to be impaired at 0.04% BAC, but – as in vigilance tasks – considerable impairment only occurred at higher BACs. Choice reaction time was affected at lower BACs than simple reaction time, which was – together with the critical flicker fusion frequency – the least sensitive parameter to the effects of alcohol. To conclude, most skills which are relevant for the safe operation of a vehicle are clearly impaired by BACs of 0.05%, with motor functions being more affected than cognitive functions and complex tasks more than simple tasks. Generally, the results provided no evidence of a threshold effect for alcohol. There was no driving-related performance category for which a sudden transition from unimpaired to impaired occurred at a particular BAC level. In addition, a comparison was made between the present meta-analysis and two reviews of Moskowitz (Moskowitz & Fiorentino, 2000; Moskowitz & Robinson, 1988). Moskowitz reported much lower BACs at which performance was impaired. The reasons for this discrepancy lies in a different way to review scientific findings. On the one hand, Moskowitz focused on significant findings when selecting studies and findings for his reviews. On the other hand, the evaluation method used by Moskowitz ignored non-significant findings and counted each study once at the lowest BAC for which impairment was found. Those non-significant findings are as important as the significant ones in order to determine thresholds of impairment. Therefore, in contrast to Moskowitz, the present work describes the effects of alcohol with functions considering also the non-significant findings. The significance of the non-significant is emphasized with respect to the selection procedure as well as to the evaluation method. N2 - Die vorliegende Arbeit gibt einen umfassenden Überblick experimenteller Studien, die die akute Wirkung von Alkohol auf fahrrelevante Leistungen untersuchen. Hierzu wurde eine Metaanalyse durchgeführt, in der Studien von 1954 bis 2007 berücksichtigt wurden. Aus über 12.000 Referenzen wurden 450 Studien mit insgesamt 5.300 Befunden nach vorher festgelegten Ein- und Ausschlusskriterien ausgewählt. So umfasst die vorliegende Metaanalyse weit mehr Studien als die bisherigen veröffentlichten Literaturüberlicke. In den ausgewählten Studien kamen verschiedene Leistungstests zur Anwendung, um die Effekte von Alkohol auf fahrrelevante Leistungen zu überprüfen. Diese Tests wurden in acht Kategorien klassifiziert: (1) visuelle Funktionen, (2) Aufmerksamkeit (einschließlich Vigilanz), (3) geteilte Aufmerksamkeit, (4) En-/ Dekodierung (einschließlich Informationsverarbeitung und Gedächtnis), (5) Reaktionszeit (einschließlich Einfachreaktionszeit und Wahlreaktionszeit), (6) psychomotorische Fähigkeiten, (7) Tracking und (8) Fahren. Neben den Leistungsaspekten berücksichtigt das in der vorliegenden Arbeit verwendete Klassifikationssystem auch andere für die Fahrleistung relevante Aspekte der beiden Bereiche subjektives Befinden und soziales Verhalten, wie beispielsweise Müdigkeit oder Aggressivität. Gemäß der Vote-counting-Methode wurde die Anzahl der signifikanten und nicht-signifikanten Befunde für verschiedene Blutalkoholkonzentrationsgruppen zusammengezählt. Daraus ergab sich eine quantitative Schätzung der Effekte von Alkohol in Abhängigkeit der Blutalkoholkonzentration (BAK), die sogenannte Beeinträchtigungsfunktion. Diese stellt den Prozentsatz an signifikanten Befunden, die eine Beeinträchtigung berichteten, dar. Um einen allgemeinen Überblick über Alkohol und die Effekte auf die Fahrleistung zu geben, wurde eine globale Beeinträchtigungsfunktion aufgestellt, in die alle Leistungsbefunde eingegangen sind. Diese Funktion ist nahezu linear mit etwa 30% signifikanten Befunden bei einer BAK von 0,05% und 50% signifikanten Befunde bei einer BAK von 0,08%. Darüber hinaus wurden spezifische Beeinträchtigungsfunktionen berechnet, in denen die jeweiligen Befunde der einzelnen Kategorien berücksichtigt wurden. Die Ergebnisse zeigten, dass die Beeinträchtigung nicht nur von der BAK abhängt, sondern auch von der geforderten Leistung. Tracking- und Fahrleistung waren dabei am stärksten betroffen. Hier zeigten sich bereits bei sehr geringen BAK von 0,02% Beeinträchtigungen. Auch psychomotorische Fähigkeiten wurden beträchtlich durch geringe BAK beeinträchtigt. Eine Beeinträchtigung der visuellen Funktionen und Informationsverarbeitung trat bei einer BAK von 0,04% auf und verstärkte sich deutlich mit höheren BAK. Eine Beeinträchtigung in Gedächtnistests konnte bei sehr geringen BAK von 0,02% gefunden werden, wobei diese in Abhängigkeit von der Art der Gedächtnistests variierte. Eine Abnahme der Leistung in Tests zu geteilter Aufmerksamkeit konnte in einigen Studien ebenfalls bei sehr geringen BAK gefunden werden. Eine Beeinträchtigung der Aufmerksamkeit trat bei einer BAK von 0,04% auf, aber erst bei höheren BAK kam es – wie bei Vigilanzaufgaben – zu erheblichen Beeinträchtigungen. Die Einfachreaktionszeit war zusammen mit der Flicker-Verschmelzungsfrequenz der am wenigsten sensitive Parameter für Alkoholeffekte. Zusammenfassend lässt sich sagen, dass die meisten Fertigkeiten, die für das sichere Führen eines Fahrzeugs relevant sind, ab einer BAK von 0,05% deutlich beeinträchtigt sind. Die motorischen Fertigkeiten sind dabei stärker betroffen als die kognitiven Funktionen, und komplexe Aufgaben stärker als einfache Aufgaben. Generell lieferten die Ergebnisse keinen Hinweis für einen Schwelleneffekt von Alkohol. Das heißt es gab keine fahrrelevante Leistungskategorie, bei der bei einer bestimmten BAK-Stufe ein plötzlicher Übergang von unbeeinträchtigt zu beeinträchtigt auftrat. Um Schwellen für ein Auftreten der Beeinträchtigung zu bestimmen, sind nicht-signifikante Befunde genauso wichtig wie signifikante. Die vorliegende Arbeit hebt die Bedeutung der Nichtsignifikanz sowohl für das Auswahlverfahren der Studien als auch für die Auswertungsmethode explizit hervor und beschreibt die Effekte von Alkohol durch Funktionen, die auch nicht-signifikante Befunde berücksichtigen. KW - Trunkenheit im Verkehr KW - Alkohol KW - Fahrerverhalten KW - Fahren KW - Leistung KW - Review KW - experimentelle Studien KW - Leistungstests KW - Metaanalyse KW - Alcohol KW - performance KW - driving KW - meta-analysis KW - review Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69959 ER - TY - JOUR A1 - Holzapfel, Boris Michael A1 - Rechl, Hans A1 - Lehner, Stefan A1 - Pilge, Hakan A1 - Gollwitzer, Hans A1 - Steinhauser, Erwin T1 - Alloplastic Reconstruction of the Extensor Mechanism after Resection of Tibial Sarcoma [Research Article] N2 - Reconstruction of the extensor mechanism is essential for good extremity function after endoprosthetic knee replacement following tumor resection. Only a few biological methods have been able to reliably restore a functional extensor mechanism, but they are often associated with significant complication rates. Reattachment of the patellar tendon to the prosthesis using an alloplastic patellar ligament (Trevira cord) can be an appropriate alternative. In vivo and in vitro studies have already shown that complete fibrous ingrowth in polyethylene chords can be seen after a period of six months. However, until now, no biomechanical study has shown the efficacy of an alloplastic cord and its fixation device in providing sufficient stability and endurance in daily life-activity until newly formed scar tissue can take over this function. In a special test bench developed for this study, different loading regimes were applied to simulate loads during everyday life. Failure loads and failuremodes were evaluated. The properties of the cord were compared before and after physiological conditioning. It was shown that rubbing was the mode of failure under dynamic loading. Tensile forces up to 2558N did not result in material failure. Thus, using an artificial cord together with this fixation device, temporary sufficient stable fixation can be expected. KW - Medizin Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69072 ER - TY - JOUR A1 - Chipperfield, Joseph D. A1 - Dytham, Calvin A1 - Hovestadt, Thomas T1 - An Updated Algorithm for the Generation of Neutral Landscapes by Spectral Synthesis N2 - Background: Patterns that arise from an ecological process can be driven as much from the landscape over which the process is run as it is by some intrinsic properties of the process itself. The disentanglement of these effects is aided if it possible to run models of the process over artificial landscapes with controllable spatial properties. A number of different methods for the generation of so-called ‘neutral landscapes’ have been developed to provide just such a tool. Of these methods, a particular class that simulate fractional Brownian motion have shown particular promise. The existing methods of simulating fractional Brownian motion suffer from a number of problems however: they are often not easily generalisable to an arbitrary number of dimensions and produce outputs that can exhibit some undesirable artefacts. Methodology: We describe here an updated algorithm for the generation of neutral landscapes by fractional Brownian motion that do not display such undesirable properties. Using Monte Carlo simulation we assess the anisotropic properties of landscapes generated using the new algorithm described in this paper and compare it against a popular benchmark algorithm. Conclusion/Significance: The results show that the existing algorithm creates landscapes with values strongly correlated in the diagonal direction and that the new algorithm presented here corrects this artefact. A number of extensions of the algorithm described here are also highlighted: we describe how the algorithm can be employed to generate landscapes that display different properties in different dimensions and how they can be combined with an environmental gradient to produce landscapes that combine environmental variation at the local and macro scales. KW - Landschaft KW - Monte-Carlo-Simulation KW - Brownsche Bewegung Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68938 ER - TY - THES A1 - Baß, Utz T1 - Analysis of MBE-grown II-VI Hetero-Interfaces and Quantum-Dots by Raman Spectroscopy T1 - Analyse von MBE-gewachsenen II-VI Heterogrenzschichten und Quantenpunkten mittels Ramanspektroskopie N2 - The material system of interest in this thesis are II-VI-semiconductors. The first part of this thesis focuses on the formation of self-assembled CdSe-based quantum dots (QD) on ZnSe. The lattice constants of ZnSe and CdSe differ as much as about 7\% and therefore a CdSe layer grown on top of ZnSe experiences a huge strain. The aspired strain relief constitutes in the self-assembly of QDs (i.e. a roughened layer structure). Additionally, this QD layer is intermixed with Zn as this is also a possibility to decrease the strain in the layer. For CdSe on ZnSe, in Molecular Beam Epitaxy (MBE), various QD growth procedures were analysed with respect to the resulting Cd-content of the non-stoichiometric ternary (Zn,Cd)Se. The evaluation was performed by Raman Spectroscopy as the phonon frequency depends on the Cd-content. The second part of the thesis emphasis on the interface properties of n-ZnSe on n-GaAs. Different growth start procedures of the ZnSe epilayer may lead to different interface configurations with characteristic band-offsets and carrier depletion layer widths. The analysis is mainly focused on the individual depletion layer widths in the GaAs and ZnSe. This non-destructive analysis is performed by evaluating the Raman signal which comprises of phonon scattering from the depleted regions and coupled plasmon-phonon scattering from regions with free carriers. N2 - Im Rahmen dieser Dissertation wurden II-VI Halbleiter untersucht. Der erste Teil behandelt die Selbstorganisation von CdSe basierten Quantenpunkten auf ZnSe. Die Gitterkonstante von ZnSe und CdSe differieren um ca. 7% und daher erfährt eine CdSe Schicht auf ZnSe eine riesige Verspannung. Der angestrebte Abbau dieser Verspannung resultiert in der Selbstorganisation von Quantenpunkten (bzw. einer rauen CdSe-Oberfläche). Zusätzlich bietet die Durchmischung mit Zn eine weitere Möglichkeit die Verspannung zu senken. In der Arbeit wurde mittels Raman Spektroskopie der Einfluss von verschiedenen MBE-Wachstumsmethoden auf den resultierenden Cd-Gehalt der Quantenpunktschicht untersucht. Im zweiten Teil standen die Grenzflächeneigenschaften von n-ZnSe auf n-GaAs im Fokus. Unterschiedliche Wachstumsmethoden dieser Grenzflächen können sich auf verschiedene Eigenschaften auswirken. Insbesondere in der Ausbildung von Verarmungszonen innerhalb der beiden Materialien an der Grenzfläche. Hierzu kam auch Raman Spektroskopie zum Einsatz da sich das Raman Signal aus Streubeiträgen von Phononen aus den verarmten Zonen und aus gekoppelten Plasmon-Phonon Moden aus den Schichten mit freien Ladungsträgern zusammensetzt. KW - Zwei-Sechs-Halbleiter KW - Molekularstrahlepitaxie KW - self-assembly KW - quantum-dots KW - Raman KW - plasmon KW - phonon KW - Wide-gap-Halbleiter KW - n-Halbleiter Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-73413 ER - TY - THES A1 - Kräußling, Michael T1 - Analysis on division patterns and transcriptional activity in embryos from medaka "Oryzias latipes" before the midblastula transition T1 - Analysen zu Teilungsmustern und transkriptioneller Aktivität in Embryonen von Medaka "Oryzias latipes" vor der Midblastula-Transition N2 - Das Studium der Entwicklung von Tieren ist eine der ältesten Disziplinen in der Biologie. Die gesammelten Daten von unzähligen Untersuchungen an den verschiedensten Spezies wurden dazu benutzt, um ein generelles Verständnis des tierischen Lebenszykluses zu formulieren. Ein wichtiges Ergebnis der intensiven Untersuchungen war vor etwa einem Jahrhundert die Entdeckung spezifischer morphologischer Veränderungen, die sich während der Teilungsphase, der Zeitperiode die der Befruchtung und Aktivierung des Eies am Anfang der Embryogenese folgt, vollziehen. Diese Befunde führten schlussendlich zur Formulierung des Konzepts einer „Mid-Blastula Transition“ (MBT). Bisher gibt es nur eine Theorie die die Regulierung der MBT in befriedigender Weise erklärt. Dies ist das Model des Kern/Plasma-Verhältnis, welches sich aus dem Verhältnis DNA-Menge zu Zytoplasmavolumen ableitet. Es erklärt die MBT-Aktivierung durch bisher unbekannte, maternal deponierte Faktoren im Ei, welche die MBT Aktivierung kontrollieren, deren Konzentration allerdings mit jeder Zellteilung verdünnt wird, bis sie schließlich ihre blockierende Funktion verloren haben. Zwar wurde die Existenz dieses Mechanismuses schon in zahlreichen Spezies experimentell bewiesen, allerdings bleibt er nur eine ungenaue Beschreibung der ablaufenden Prozesse und lässt weiterhin viele Fragen unbeantwortet. Vor diesem Hintergrund hat diese Arbeit gezeigt, dass die Zellzyklen in Embryonen von Medaka (Oryzias latipes) ihre Synchronität schon nach dem vierten oder fünften Teilung verlieren, und diese durch ein Teilungsmuster ersetzt wird, das als „metasynchron“ bezeichnet wird. In diesem Teilungsmuster verlaufen die Zellteilungen in Wellen, die im Zentrum des Embryos beginnen und sich von dort nach außen hin radial ausbreiten. Noch ist der Sinn einer auf diese Art verlaufenden Zellteilung unbekannt, auch wenn es verschiedene Theorien gibt die versuchen den zugrunde liegenden Mechanismus zu erklären. Allen voran steht die Theorie eines unterschiedlichen Zugangs zu Faktoren innerhalb des Dotters. Allerdings wird diese Theorie durch die Beobachtungen in verformten Embryonen wiederlegt, in denen sich die Teilungswellen von einer Seite des Embryos zur gegenüberliegenden Seite ausgebreitet haben. Somit bleibt der Mechanismus für diese Art der Zellteilung weiterhin unklar. Nicht zu vergessen ist, dass diese deformierten Embryonen eine der möglichen Konsequenzen asymmetrischer Furchung während einer frühen Zellteilung sind. Asymmetrische Teilungen treten in Medaka in einer erheblichen Anzahl von Embryonen auf und haben einen direkten Einfluss auf die gleichmäßige Verteilung des Zytoplasma. Leider war es nicht möglich die Auswirkungen einer solchen ungleichmäßigen Verteilung aufzudecken, auch wenn man davon ausgehen kann, dass ein ausreichend großes Ungleichgewicht zu unterschiedlichen Zeitpunkten der MBT-Aktivierung in verschiedenen Zellgruppen führen müsste. Ähnliche Beobachtungen wurden bereits in anderen Spezies gemacht, und es wurde vermutet, dass diese in ungleichmäßigen Zellteilungen begründet lagen. Weiterhin wurde bewiesen, dass die zygotische Transkription schon wesentlich vor dem bisher angenommenen frühesten Zeitpunkt aktiv ist. Darüber hinaus wurden Hinweise gefunden, die darauf hindeuten, dass die Transkription in Embryonen von Medaka in zwei Schritten einsetzt. Der erste Zeitpunkt ist das 16-Zellen-Stadium, in dem die ersten Zellen identifiziert wurden, die Phosphorylierung für RNAPII zeigten, und der zweite das64-Zellen Stadium, in dem der Anteil an p-RNAPII positiven Zellen signifikant anstieg. Ein schrittweiser Anstieg der Transkription wurde bereits in anderen Spezies beobachtet, auch wenn in diesen Fällen nur eine Erhöhung der mRNA-Menge festgestellt wurde, und nicht die unterschiedliche Anzahl an transkriptionell aktiven Zellen untersucht wurde.Zusammenfassend bestätigen und erweitern die hier gezeigten Daten die grundliegenden Kenntnisse über die Prozesse vor und währen der MBT, liefern darüber hinaus aber auch Anzeichen für viele Prozesse vor und während der MBT, die nur wenig oder gar nicht verstanden sind. N2 - The study of animal development is one of the oldest disciplines in the field of biology and the collected data from countless investigations on numerous species have formed a general understanding of the animal life-cycle. Almost one century ago, one consequence of these intense investigations was the discovery of specific morphological changes that occur during the cleavage phase, a period that follows fertilization and egg activation at the very beginning of animal embryogenesis. These observations resulted into the formulation of the concept of a midblastula transition (MBT). So far, the mechanism of the nucleo-cytoplasmic ratio model is the only one that explains MBT regulation in a satisfying way. It suggests that the MBT is controlled by several maternal repressive factors in the egg, which are titrated out by every cell division until they lose their repressing potential. Although this regulatory mechanism was proven for several species and in different approaches, it is still only a rudimentary model for MBT control and leaves numerous questions unanswered. On this conceptual background, this thesis has shown that embryos from the medaka fish (Oryzias latipes) lose their cell cycle synchrony already after the fourth or fifth round of cell divisions, and replace it by a metasynchronous divisions pattern, in which cell division occurs in clear waves beginning in the embryo's center. The reason for this change in division mode is still unknown, although several hypotheses were put forward, most notable a difference in yolk-access between cells. However, this theory was weakened by division waves that progressed from one embryonic pole to the opposing one, which were occasionally observed in deformed embryos, leaving the mechanism for this phenomenon furthermore unclear. Those deformed embryos were most likely the result of asymmetric cell divisions at very early stages, a phenomenon which occurred in a significant percentage of medaka embryos and which directly influenced the equal distribution of cytoplasmic material. It could not beuncovered what kind of effects this unequal distribution of cytoplasm exerted on the progression of embryonic development, but it can be argued that relevant differences in cell volumes could result in cell clusters that will enter MBT at different time points. Comparable observations were already made in other species and it was hypothesized that they were the direct results of early unequal cell cleavages. Finally, it was demonstrated that zygotic transcription in medaka embryos is activated prior to the hitherto assumed time of the first transcriptional initiation. Moreover, indications were found that strongly speak for a transcriptional activation that occurs in two steps; a first step at the 16-cell stage when first cells were identified positive for RNAPII phosphorylation, and a second step at the 64-cell stage, when the number of p-RNAPII positive cells significantly increased. A stepwise activation of zygotic transcription was already observed in other species, but only for the overall increasing amount of mRNAs and irrespective of the actual number of transcriptionally active cells within the embryos. .. Overall, these data confirm and expand the basic knowledge of pre-MBT embryos and about the MBT itself. Furthermore, they also suggest that many early processes in pre-MBT embryos are only rudimentarily understood or still totally unknown. KW - Japankärpfling KW - Genregulation KW - Transkription KW - Furchungsteilung KW - Zellvolumen KW - Zygote KW - Midblastula-transition MBT MZT KW - Midblastula-transition MBT MZT Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-66911 ER - TY - JOUR A1 - Baptistella Florence, Michelle Etienne A1 - Massuda, Juliana Yumi A1 - Bröcker, Eva-Bettina A1 - Metze, Konradin A1 - Cintra, Maria Leticia A1 - de Souza, Elemir Macedo T1 - Angiogenesis in the progression of cutaneous squamous cell carcinoma: an immunohistochemical study of endothelial markers JF - CLINICS N2 - OBJECTIVE: To demonstrate the role of angiogenesis in the progression of cutaneous squamous cell carcinoma. INTRODUCTION: Angiogenesis is a pivotal phenomenon in carcinogenesis. Its time course in cutaneous squamous cell carcinoma has not yet been fully established. METHODS: We studied the vascular bed in 29 solar keratoses, 30 superficially invasive squamous cell carcinomas and 30 invasive squamous cell carcinomas. The Chalkley method was used to quantify the microvascular area by comparing panendothelial (CD34) with neoangiogenesis (CD105) immunohistochemical markers. The vascular bed from non-neoplastic adjacent skin was evaluated in 8 solar keratoses, 10 superficially invasive squamous cell carcinomas and 10 invasive squamous cell carcinomas. RESULTS: The microvascular area in CD105-stained specimens significantly increased in parallel with cutaneous squamous cell carcinoma progression. However, no differences between groups were found in CD34 sections. Solar keratosis, superficially invasive squamous cell carcinoma and invasive squamous cell carcinoma samples showed significant increases in microvascular area for both CD34- and CD105-stained specimens compared with the respective adjacent skin. DISCUSSION: The angiogenic switch occurs early in the development of cutaneous squamous cell carcinoma, and the rate of neovascularization is parallel to tumor progression. In contrast to panendothelial markers, CD105 use allows a dynamic evaluation of tumor angiogenesis. CONCLUSION: This study demonstrated the dependence of skin carcinogenesis on angiogenesis. KW - Pathologic neovascularization KW - CD105 antigen KW - human KW - CD34 antigen KW - skin neoplasms KW - keratosis Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133650 VL - 66 IS - 3 ER - TY - JOUR A1 - Stieb, Sara Mae A1 - Kelber, Christina A1 - Wehner, Rüdiger A1 - Rössler, Wolfgang T1 - Antennal-Lobe Organization in Desert Ants of the Genus Cataglyphis JF - Brain, Behavior and Evolution N2 - Desert ants of the genus Cataglyphis possess remarkable visual navigation capabilities. Although Cataglyphis species lack a trail pheromone system, Cataglyphis fortis employs olfactory cues for detecting nest and food sites. To investigate potential adaptations in primary olfactory centers of the brain of C. fortis, we analyzed olfactory glomeruli (odor processing units) in their antennal lobes and compared them to glomeruli in different Cataglyphis species. Using confocal imaging and 3D reconstruction, we analyzed the number, size and spatial arrangement of olfactory glomeruli in C. fortis, C.albicans, C.bicolor, C.rubra, and C.noda. Workers of all Cataglyphis species have smaller numbers of glomeruli (198–249) compared to those previously found in olfactory-guided ants. Analyses in 2 species of Formica – a genus closely related to Cataglyphis – revealed substantially higher numbers of olfactory glomeruli (c. 370), which is likely to reflect the importance of olfaction in these wood ant species. Comparisons between Cataglyphis species revealed 2 special features in C. fortis. First, with c. 198 C. fortis has the lowest number of glomeruli compared to all other species. Second, a conspicuously enlarged glomerulus is located close to the antennal nerve entrance. Males of C. fortis possess a significantly smaller number of glomeruli (c. 150) compared to female workers and queens. A prominent male-specific macroglomerulus likely to be involved in sex pheromone communication occupies a position different from that of the enlarged glomerulus in females. The behavioral significance of the enlarged glomerulus in female workers remains elusive. The fact that C. fortis inhabits microhabitats (salt pans) that are avoided by all other Cataglyphis species suggests that extreme ecological conditions may not only have resulted in adaptations of visual capabilities, but also in specializations of the olfactory system. KW - olfactory glomeruli KW - plasticity KW - ant KW - antennal lobe KW - glomerulus KW - insects KW - interspecific comparison KW - macroglomerulus KW - olfaction Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196815 SN - 0006-8977 SN - 1421-9743 N1 - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. VL - 77 IS - 3 ER - TY - JOUR A1 - Rantamäki, Tomi A1 - Vesa, Liisa A1 - Antila, Hanna A1 - Di Lieto, Antonio A1 - Tammela, Päivi A1 - Schmitt, Angelika A1 - Lesch, Klaus-Peter A1 - Rios, Maribel A1 - Castrén, Eero T1 - Antidepressant Drugs Transactivate TrkB Neurotrophin Receptors in the Adult Rodent Brain Independently of BDNF and Monoamine Transporter Blockade JF - PLoS ONE N2 - Background: Antidepressant drugs (ADs) have been shown to activate BDNF (brain-derived neurotrophic factor) receptor TrkB in the rodent brain but the mechanism underlying this phenomenon remains unclear. ADs act as monoamine reuptake inhibitors and after prolonged treatments regulate brain bdnf mRNA levels indicating that monoamine-BDNF signaling regulate AD-induced TrkB activation in vivo. However, recent findings demonstrate that Trk receptors can be transactivated independently of their neurotrophin ligands. Methodology: In this study we examined the role of BDNF, TrkB kinase activity and monoamine reuptake in the AD-induced TrkB activation in vivo and in vitro by employing several transgenic mouse models, cultured neurons and TrkB-expressing cell lines. Principal Findings: Using a chemical-genetic TrkB(F616A) mutant and TrkB overexpressing mice, we demonstrate that ADs specifically activate both the maturely and immaturely glycosylated forms of TrkB receptors in the brain in a TrkB kinase dependent manner. However, the tricyclic AD imipramine readily induced the phosphorylation of TrkB receptors in conditional bdnf(-/-) knock-out mice (132.4+/-8.5% of control; P = 0.01), indicating that BDNF is not required for the TrkB activation. Moreover, using serotonin transporter (SERT) deficient mice and chemical lesions of monoaminergic neurons we show that neither a functional SERT nor monoamines are required for the TrkB phosphorylation response induced by the serotonin selective reuptake inhibitors fluoxetine or citalopram, or norepinephrine selective reuptake inhibitor reboxetine. However, neither ADs nor monoamine transmitters activated TrkB in cultured neurons or cell lines expressing TrkB receptors, arguing that ADs do not directly bind to TrkB. Conclusions: The present findings suggest that ADs transactivate brain TrkB receptors independently of BDNF and monoamine reuptake blockade and emphasize the need of an intact tissue context for the ability of ADs to induce TrkB activity in brain. KW - Serotonin transporter KW - Neuronal plasticity KW - Mood disorders KW - Messenger-RNA KW - Mouse-brain KW - Rat-brain KW - Activation KW - Depression KW - Mice KW - Insensitivity Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133746 VL - 6 IS - 6 ER - TY - THES A1 - Tabares, Paula T1 - Antimicrobial, anti-protease and immunomodulatory activities of secondary metabolites from Caribbean sponges and their associated bacteria T1 - Sekundärmetabolite mit antimikrobiellen, Protease-hemmenden und immunmodulatorischen Aktivitäten aus karibischen Schwämmen und assoziierten Bakterien N2 - Marine sponges and their associated bacteria have been proven to be a rich source of novel secondary metabolites with therapeutic usefulness in infection and autoimmunity. This Ph.D. project aimed to isolate bioactive secondary metabolites from the marine sponges Amphimedon compressa, Aiolochroia crassa and Theonella swinhoei as well as from bacteria associated with different Caribbean sponges, specifically actinomycetes and sphingomonads. In this study, amphitoxin was isolated from the crude methanol extract of the sponge A. compressa and it was found to have antibacterial and anti-parasitic activities. Amphitoxin showed protease inhibitory activity when tested against the mammalian protease cathepsin B and the parasitic proteases rhodesain and falcipain-2. Furthermore, miraziridine A was identified in the dichloromethane extract of the sponge T. swinhoei collected offshore Israel in the Red Sea. Miraziridine A, a natural peptide isolated previously from the marine sponge Theonella aff. mirabilis, is a potent cathepsin B inhibitor with an IC50 value of 1.4 g/mL (2.1 M). Secondary metabolites from sponge-derived bacteria were also isolated and identified. A total of 79 strains belonging to 20 genera of the order Actinomycetales and seven strains belonging to two genera of the order Sphingomonadales were cultivated from 18 different Caribbean sponges and identified by 16S rRNA gene sequencing. Seven of these strains are likely to represent novel species. Crude extracts from selected strains were found to exhibit protease inhibition against cathepsins B and L, rhodesain, and falcipain-2 as well as immunomodulatory activities such as induction of cytokine release by human peripheral blood mononuclear cells. The isolates Sphingobium sp. CO105 and Lapillicoccus sp. BA53 were selected for cultivation, extraction and purification of bioactive metabolites based on initial bioactive screening results. The isoalloxazine isolumichrome was isolated from the strain Sphingobium sp. CO105 which inhibited the protease rhodesain with an IC50 of 0.2 M. The strain Lapillicoccus sp. BA53 was found to produce p-aminosalicylic acid methyl ester, which showed activity against the proteases cathepsins B and L, falcipain-2 and rhodesain. These results highlight the significance of marine sponge-associated bacteria to produce bioactive secondary metabolites with therapeutic potential in the treatment of infectious diseases and disorders of the immune system. N2 - Marine Schwämme und damit assoziierte Bakterien stellen eine wertvolle Quelle für neuartige Sekundärmetabolite mit therapeutischer Bedeutung für Infektion und Autoimmunität dar. Ziel dieser Doktorarbeit war die Isolierung bioaktiver Sekundärmetabolite aus den marinen Schwämmen Amphimedon compressa, Ailochroia crassa und Theonella swinhoei sowie von Bakterien, die mit verschiedenen karibischen Schwämmen assoziiert sind, wie z. B. Actinomyceten und Sphingomonaden. Amphotoxin wurde in dieser Studie aus dem methanolhaltigen Rohextrakt des Schwammes A. compressa isoliert. Es konnte sowohl eine antibakterielle als auch antiparasitäre Aktivität nachgewiesen werden. Der Einfluss von Amphotoxin auf die humane Protease Cathepsin B und die parasitären Proteasen Rhodesain und Falcipain-2 wurde ebenfalls getestet und es zeigte sich eine inhibitorische Wirkung gegenüber diesen Proteasen. Darüber hinaus wurde aus dem Dichlormethanextrakt des Schwammes T. swinhoei, der aus dem Roten Meer in Israel gewonnen wurde, Miraziridin A isoliert. Dieses natürliche Peptid war bereits aus dem marinen Schwamm Theonella aff. mirabilis isoliert worden. Miraziridin A ist ein starker Cathepsin B Inhibitor, der IC50 Wert beträgt 1.4 mg/mL (2.1 M). Sekundärmetabolite von aus Schwämmen gewonnenen Bakterien wurden ebenfalls isoliert und identifiziert. Es konnten 79 Stämme, die zu 20 verschiedenen Gattungen der Ordnung Actinomycetales, sowie sieben Stämme, die zu zwei Gattungen der Ordnung Sphingomonadales gehören, isoliert werden. Diese Bakterienstämme wurden aus ingesamt 18 verschiedenen karibischen Schwämmen kultiviert und mit Hilfe der 16S rRNA Sequenzierung bestimmt. Sieben dieser Stämme stellen wahrscheinlich neue Arten dar. Rohextrakte ausgewählter Stämme zeigten eine Proteasehemmung gegen die Cathepsine B und L, Rhodesain, Falcipain-2 sowie immunmodulatorische Wirkungen wie z.B. die Induktion der Cytokinfreisetzung durch menschliche periphere mononukleäre Blutzellen. Die Isolate Sphingobium sp. CO105 und Lapillicoccus sp. BA53 wurden für die Kultivierung, Extraktion und Aufreinigung von bioaktiven Metaboliten aufgrund der ersten vielversprechenden bioaktiven Testergebnisse ausgewählt. Das Isoalloxazin Isolumichrom wurde aus dem Stamm Sphingobium sp. CO105 isoliert, welches die Protease Rhodesain mit einem IC50-Wert von 0.2 M inhibiert. Für den Stamm Lapillicoccus sp. BA53 konnte nachgewiesen werden, dass er p-Aminosalicylsäuremethylester produziert, der eine Aktivität gegen die Proteasen Cathepsin B und L, Falcipain-2 und Rhodesain zeigt. Diese Ergebnisse unterstreichen die Bedeutung mariner, Schwamm-assoziierter Bakterien, die bioaktive sekundäre Metabolite mit therapeutischem Potential für die Behandlung von Infektionskrankheiten und Funktionsstörungen des Immunsystems produzieren. KW - Schwämme KW - Bakterien KW - Karibisches Meer KW - Sekundärmetabolit KW - Actinomycetes KW - sphingomonads KW - marine sponge KW - anti-protease KW - immunomodulatory KW - phylogenetic analysis Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-67000 ER - TY - THES A1 - Gerdau, Ole T1 - Applicability of Intrinsic Value Models at the Segmented Chinese Stock Market T1 - Anwendbarkeit intrinsischer Wertmodelle am segmentierten chinesischen Kapitalmarkt N2 - Ziel dieser Arbeit ist es, die Anwendbarkeit intrinsischer Wertmodelle in dem nach inländischen und ausländischen Investoren segmentierten chinesischen Kapitalmarkt zu untersuchen. Innerhalb des Frameworks der internationalen Portfolio Investment Theorie werden segmentspezifische Preisunterschiede nicht irrationalem Verhalten zugeschrieben, sondern als in Übereinstimmung mit ökonomischer Theorie angesehen. Der theoretische Vergleich von Gleichgewichts- und intrinsischen Wertmodellen lässt letztere für das chinesische Marktumfeld geeigneter erscheinen. Vor diesem Hintergrund wird in dieser Arbeit die Relevanz intrinsischer Wertmodelle für chinesische Aktienpreise empirisch untersucht. Demnach sind Preisunterschiede auf ungleiche Investitionsmöglichkeiten und segmentspezifische Charakteristika zurückzuführen. Dennoch führen die Ergebnisse im Hinblick auf den inländischen und Hongkong-chinesischen risikolosen Zinsproxys zu dem Schluss, dass intrinsische Wertmodelle gegenüber linearen Faktormodellen nicht als geeigneter angesehen werden können. N2 - This thesis examines the application of intrinsic value models considering segmentation between foreign and domestic investors’ stock segments in China. Within the framework of international portfolio investment theory, segment-specific price differences are theorized to be not caused by irrational behavior but consistent with economic theory. Theoretical comparison of equilibrium and intrinsic value models suggests the latter to be more suitable regarding the Chinese market environment. Correspondingly, in this thesis the relevance of intrinsic value models for Chinese stock prices is examined empirically. It is concluded that price differences can be ascribed to unequal investment opportunities and segment specific characteristics. Nevertheless, results from the domestic and Hong Kong risk-free rate proxy lead to the conclusion that intrinsic value models cannot be considered better suited than linear factor models. KW - China KW - Aktienmarkt KW - Preisbildung KW - Unternehmensbewertung KW - Marktsegmentierung KW - implizite Kapitalkosten KW - intrinsic value models KW - Chinese stock market KW - market segmentation KW - implied cost of capital Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-55652 ER - TY - THES A1 - Simon, Dennis T1 - Aspects in the fate of primordial vacuum bubbles N2 - At the present day the idea of cosmological inflation constitutes an important extension of Big Bang theory. Since its appearance in the early 1980’s many physical mechanisms have been worked out that put the inflationary expansion of space that proceeds the Hot Big Bang on a sound theoretical basis. Among the achievements of the theory of inflation are the explanaition of the almost Euclidean geometry of ‘visible’space, the homogeneity of the cosmic background radiation but, in particular, also the tiny inhomogeneity of a relative amplitude of 10−5. In many models of inflation the inflationary phase ends only locally. Hence, there exists the possibility that the inflationary process still goes on in regions beyond our visual horizon. This property is commonly termed ‘eternal inflation’. In the framework of a cosmological scalar fields, eternal inflation can manifest itself in a variety of ways. On the one hand fluctuations of the field, if sufficiently large, can work against the classical trajectory and therefore counteract the end of inflation. In regions where this is the case the accelerated expansion of space continues at a higher rate. In parts of this region the process may replicate itself again and in this way may continue throughout all of time. Space and field are said to reproduce themselves. On the other hand, a mechanism that can occur in addition or independent of the latter, is so called vacuum tunneling. If the potential of the scalar field has several local minima, a semi-classical calculation suggests that within a spherical region, a bubble, the field can tunnel to another state. The respective tunneling rates depend on the potential difference and the shape of the potential between the states. Generally, the tunneling rate is exponentially suppressed, which means that the inflation lasts for a long time before tunneling takes place. The ongoing inflationary process effectively reduces local curvature, anistotropy and inhomogeneity, so that this property is known as the ‘cosmic no-hair conjecture’. For this reason cosmological considerations of the evolution of bubbles thus far almost entirely involved vacuum (de Sitter) backgrounds. However, new insights in the framework of string theory suggest high tunneling rates which allow for the possibility of bubble nucleation in non-vacuum dominated backgrounds. In this case the evolution of the bubble depends on the properties of the background spacetime. A deeper introduction in chapter 4 is followed by the presentation of the Lemaître-Tolman spacetime in chapter 5 which constitutes the background spacetime in the study of the effect of matter and inhomogeneity on the evolution of vacuum bubbles. In chapter 6 we explicitly describe the application of the ‘thin-shell’ formalism and the resulting system of equations. This is succeeded in chapter 7 by the detailed analysis of bubble evolution in various limits of the Lemaître-Tolman spacetime and a Robertson-Walker spacetime with a rapid phase transition. The central observations are that the presence of dust, at a fixed surface energy density, goes along with a smaller nucleation volume and possibly leads to a a collapse of the bubble. In an expanding background, the radially inhomogeneous dust profile is efficiently diluted so that there is essentially no effect on the evolution of the domain wall. This changes in a radially inhomogeneous curvature profile, positive curvature decelerates the expansion of the bubble. Moreover, we point out that the adopted approach does not allow for a treatment of a, physically expected, matter transfer so that the results are to be understood as preliminary under this caveat. In the second part of this thesis we consider potential observable consequences of bubble collisions in the cosmic microwave background radiation. The topological nature of the signal suggests the use of statistics that are well suited to quantify the morphological properties of the temperature fluctuations. In chapter 10 we present Minkowski Functionals (MFs) that exactly provide such statistics. The presented error analysis allows for a higher precision of numerical MFs in comparison to earlier methods. In chapter 12 we present the application of our algorithm to a Gaussian and a collision map. We motivate the expected MFs and extract their numerical counterparts. We find that our least-squares fitting procedure accurately reproduces an underlying signal only when a large number of realizations of maps are averaged over, while for a single WMAP and PLANCK resolution map, only when a highly prominent disk, with |δT| = 2√σG and ϑd = 40◦, we are able to recover the result. This is unfortunate, as it means that MF are intrinsically too noisy to be able to distinguish cold and hot spots in the CMB for small sizes. N2 - Die Idee der kosmologischen Inflation stellt heute die wichtigste Erweiterung der klassischen Urknalltheorie dar. Seit ihrem Aufkommen in den frühen 80er Jahren sind zahlreiche physikalische Mechanismen bekannt und ausgearbeitet geworden, die die inflationäre Expansion des Raums vor der dem ‘heißen’ Urknall auf eine tragfähige, theoretische Basis stellen. Zu den Errungenschaften der Inflationstheorie zählen unter Anderem die Erklärung der nahezu Euklidischen Geometrie des sichtbaren Raums, die bemerkenswerte Homogenität der kosmischen Hintergrundstrahlung, im Besonderen aber auch die ihr innewohnenden winzigen Unregelmäßigkeiten mit einer relativen Amplitude der Größenordnung 10−5. In vielen Inflationsmodellen endet die Inflation allerdings nur lokal. Demzufolge besteht die Möglichkeit, dass es außerhalb des von uns sichtbaren Raums Gebiete geben kann, in denen der inflationäre Prozess weiterhin stattfindet. Dieser Eigenschaft wird durch den Begriff ‘Ewige Inflation’ Rechnung getragen. Ewige Inflation kann sich im Rahmen der Skalarfeld-Inflation in verschiedenen Formen manifestieren. Zum Einen können die Fluktuationen des Feldes so groß sein, dass sie der klassischen Trajektorie, und damit dem Ende der Inflation, entgegenwirken wirken. In Regionen, in denen das geschieht, setzt sich die beschleunigte Expansion des Raums mit einer höheren Rate weiter fort. In Teilen solcher Regionen mag sich dies wiederholen und der Vorgang auf diese Weise theoretisch bis ins Unendliche andauern. Raum und Feld reproduzieren sich selbst. Eine weitere Möglichkeit, die sowohl unabhängig als auch zusätzlich zur zuvor beschriebenen auftreten kann, ist die des sogenannten Vakuumtunnelns. Wenn das Potential des Skalarfelds mehrere lokale Minima aufweist, so legt eine semi-klassische Rechnung, dass das Feld innerhalb eines sphärischen Gebiets, einer Blase, in einen anderen Zustand tunneln kann. Fortwährende Inflation beseitigt großräumig, effektiv, jegliche Form der Unregelmäßigkeit, d. h. Raumkrümmung, Anisotropie und Inhomogenität, sodass dieser Sachverhalt unter dem Ausdruck ‘cosmic no-hair conjecture’ bekannt ist. Aus diesem Grund waren bisherige Betrachtungen fast aussschließlich der Entwicklung von Blasen in einem Vakuumhintergrund gewidmet. Neue Überlegungen im Rahmen der Stringtheorie erlauben allerdings auch hohe Tunnelraten, sodass die Möglichkeit der Nukleation von Blasen in nicht-vakuumdominierten Hintergründen besteht. Die weitere Entwicklung hängt in diesem Fall von den Eigenschaften des Hintergrunds ab. Nach der Ableitung der Vakuumlösung wird sukzessive auf die Blasenentwicklung in einem statischen Hintergrund, in einem dynamischen, aber homogenen Hintergrund, in einem flachen, inhomogenen Hintergrund, in einem gekrümmten, inhomogenen Hintergrund und in einem homogenen Hintergrund mit Phasenübergang eingegangen. Zu den zentralen Beobachtungen gehört, dass die Präsenz des Staubs, bei fixierter Oberflächendichte, eine Verringerung des Nukleationsvolumens mit sich bringt und dazu führen kann, dass die Blase einen Kollaps beginnt. Das ändert sich in einem radial inhomogenen Krümmungsprofil, positive Raumkrümmung hat einen abbremsenden Effekt auf die Expansion der Blase. Es wird herausgestellt, dass der verwendete Ansatz keine Möglichkeit zur Behandlung eines, physikalisch zu erwartenden, Materietransfers bietet und die damit erzielten Ergebnisse unter diesem Vorbehalt zu verstehen sind. Im zweiten Teil der vorliegenden Arbeit wird potentiell beobachtbaren Konsequenzen der Kollision zweier Blasen in der kosmischen Hintergrundstrahlung nachgegangen. Die topologische Natur des Signals in der letzten Streufläche legt die Verwendung von Statistiken nahe, die es erlauben, die morphologischen Eigenschaften der Temperaturfluktuationen zu quantifizieren. Diese Statistiken bieten die Minkowski Funktionale (MF), die in Kapitel 10 vorgestellt werden. Dieses wird benutzt um Karten eines Gaussschen Zufallsfeldes zu erzeugen und die entsprechenden MF zu berechnen. Die vorgestellte Fehleranalyse erlaubt eine höhere Präzision der numerischen MF im Vergleich zu bisherigen Methoden. Ein Fit der geringsten quadratischen Abweichung reproduziert die tatsächlichen Parameter nur dann, wenn über eine hohe Anzahl von Realisierungen gemittelt wird, wohingegen die Betrachtung einer einzigen Karte in WMAP bzw. Planck Auflösung nur für “auffällige” Scheiben mit Temperaturunterschied δT = 2√σG und Öffnungswinkel ϑd = 40◦ Übereinstimmung erreicht wird. Dies bedeutet, das MF ein schlechtes ‘Signal zu Rausch’Verhältnis besitzen um heiße oder kalte Scheiben in der kosmischen Hintergrundstrahlung zu erfassen. KW - Kosmologie KW - Kosmische Hintergrundstrahlung KW - Inflationäres Weltall KW - Bubble Universes KW - Israel Junction Conditions KW - Inhomogeneous Cosmological Models KW - Minkowski Functionals KW - HEALPix Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-67019 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - Assisting Analysis and Understanding of Quran Search Results with Interactive Scatter Plots and Tables N2 - The Quran is the holy book of Islam consisting of 6236 verses divided into 114 chapters called suras. Many verses are similar and even identical. Searching for similar texts (e.g verses) could return thousands of verses, that when displayed completely or partly as textual list would make analysis and understanding difficult and confusing. Moreover it would be visually impossible to instantly figure out the overall distribution of the retrieved verses in the Quran. As consequence reading and analyzing the verses would be tedious and unintuitive. In this study a combination of interactive scatter plots and tables has been developed to assist analysis and understanding of the search result. Retrieved verses are clustered by chapters, and a weight is assigned to each cluster according to number of verses it contains, so that users could visually identify most relevant areas, and figure out the places of revelation of the verses. Users visualize the complete result and can select a region of the plot to zoom in, click on a marker to display a table containing verses with English translation side by side. KW - Text Mining KW - Visualisierung KW - Koran KW - Information Visualization KW - Visual Text Mining KW - Scatter Plot KW - Quran Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-55840 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - Assisting Understanding, Retention, and Dissemination of Religious Texts Knowledge with Modeling, and Visualization Techniques: The Case of The Quran N2 - Learning a book in general involves reading it, underlining important words, adding comments, summarizing some passages, and marking up some text or concepts. Once deeper understanding is achieved, one would like to organize and manage her/his knowledge in such a way that, it could be easily remembered and efficiently transmitted to others. In this paper, books organized in terms of chapters consisting of verses, are considered as the source of knowledge to be modeled. The knowledge model consists of verses with their metadata and semantic annotations. The metadata represent the multiple perspectives of knowledge modeling. Verses with their metadata and annotations form a meta-model, which will be published on a web Mashup. The meta-model with linking between its elements constitute a knowledge base. An XML-based annotation system breaking down the learning process into specific tasks, helps constructing the desired meta-model. The system is made up of user interfaces for creating metadata, annotating chapters’ contents according to user selected semantics, and templates for publishing the generated knowledge on the Internet. The proposed software system improves comprehension and retention of knowledge contained in religious texts through modeling and visualization. The system has been applied to the Quran, and the result obtained shows that multiple perspectives of information modeling can be successfully applied to religious texts. It is expected that this short ongoing study would motivate others to engage in devising and offering software systems for cross-religions learning. KW - Wissensmanagement KW - Koran KW - Knowledge Modeling KW - Meta-model KW - Knowledge Management KW - Content Management KW - Quran Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-55927 ER - TY - JOUR A1 - Carsten A., Böger A1 - Gorski, Mathias A1 - Li, Man A1 - Hoffmann, Michael M. A1 - Huang, Chunmei A1 - Yang, Qiong A1 - Teumer, Alexander A1 - Krane, Vera A1 - O'Seaghdha, Conall M. A1 - Kutalik, Zoltán A1 - Wichmann, H.-Erich A1 - Haak, Thomas A1 - Boes, Eva A1 - Coassin, Stefan A1 - Coresh, Josef A1 - Kollerits, Barbara A1 - Haun, Margot A1 - Paulweber, Bernhard A1 - Köttgen, Anna A1 - Li, Guo A1 - Shlipak, Michael G. A1 - Powe, Neil A1 - Hwang, Shih-Jen A1 - Dehghan, Abbas A1 - Rivadeneira, Fernando A1 - Uitterlinden, André A1 - Hofman, Albert A1 - Beckmann, Jacques S. A1 - Krämer, Bernhard K. A1 - Witteman, Jacqueline A1 - Bochud, Murielle A1 - Siscovick, David A1 - Rettig, Rainer A1 - Kronenberg, Florian A1 - Wanner, Christoph A1 - Thadhani, Ravi I. A1 - Heid, Iris M. A1 - Fox, Caroline S. A1 - Kao, W.H. T1 - Association of eGFR-Related Loci Identified by GWAS with Incident CKD and ESRD JF - PLoS Genetics N2 - Family studies suggest a genetic component to the etiology of chronic kidney disease (CKD) and end stage renal disease (ESRD). Previously, we identified 16 loci for eGFR in genome-wide association studies, but the associations of these single nucleotide polymorphisms (SNPs) for incident CKD or ESRD are unknown. We thus investigated the association of these loci with incident CKD in 26,308 individuals of European ancestry free of CKD at baseline drawn from eight population-based cohorts followed for a median of 7.2 years (including 2,122 incident CKD cases defined as eGFR < 60ml/min/1.73m(2) at follow-up) and with ESRD in four case-control studies in subjects of European ancestry (3,775 cases, 4,577 controls). SNPs at 11 of the 16 loci (UMOD, PRKAG2, ANXA9, DAB2, SHROOM3, DACH1, STC1, SLC34A1, ALMS1/NAT8, UBE2Q2, and GCKR) were associated with incident CKD; p-values ranged from p = 4.1e-9 in UMOD to p = 0.03 in GCKR. After adjusting for baseline eGFR, six of these loci remained significantly associated with incident CKD (UMOD, PRKAG2, ANXA9, DAB2, DACH1, and STC1). SNPs in UMOD (OR = 0.92, p = 0.04) and GCKR (OR = 0.93, p = 0.03) were nominally associated with ESRD. In summary, the majority of eGFR-related loci are either associated or show a strong trend towards association with incident CKD, but have modest associations with ESRD in individuals of European descent. Additional work is required to characterize the association of genetic determinants of CKD and ESRD at different stages of disease progression. KW - Chronic Kidney-disease KW - Stage renal-disease KW - Glomerular-filtration-rate KW - Diabetic-nephropathy KW - General-population KW - African-americans KW - Risk KW - Progression KW - Mortality KW - Variants Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133758 VL - 7 IS - 9 ER - TY - JOUR A1 - Reinards, THCM A1 - Albers, HM A1 - Brinkman, DMC A1 - Kamphuis, SSM A1 - van Rossum, MAJ A1 - Hoppenreijs, EPAH A1 - Girschick, HJ A1 - Wouters, C A1 - Saurenmann, RK A1 - Houwing-Duistermaat, JJ A1 - Toes, REM A1 - Huizinga, TWJ A1 - ten Cate, R A1 - Schilham, MW T1 - Association of the CCR5Δ32 variant with juvenile idiopathic arthritis in a meta-analysis JF - Pediatric Rheumatology N2 - No abstract available. KW - Pädiatrie KW - Rheumatologie Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133763 VL - 9 IS - Suppl. 1 ER - TY - JOUR A1 - Reinards, THCM A1 - Albers, HM A1 - Brinkman, DMC A1 - Kamphuis, SSM A1 - van Rossum, MAJ A1 - Hoppenreijs, EPAH A1 - Girschick, HJ A1 - Wouters, C A1 - Saurenmann, RK A1 - Houwing-Duistermaat, JJ A1 - Toes, REM A1 - Huizinga, TWJ A1 - ten Cate, R A1 - Schilham, MW T1 - Association of the CD226 (DNAM-1) Gly307Ser polymorphism with juvenile idiopathic arthritis JF - Pediatric Rheumatology N2 - No abstract available. KW - Pädiatrie KW - Rheumatologie Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133773 VL - 9 IS - Suppl. 1 ER - TY - JOUR A1 - Schmitt, Jana A1 - Keller, Andreas A1 - Nourkami-Tutdibi, Nasenien A1 - Heisel, Sabrina A1 - Habel, Nunja A1 - Leidinger, Petra A1 - Ludwig, Nicole A1 - Gessler, Manfred A1 - Graf, Norbert A1 - Berthold, Frank A1 - Lenhof, Hans-Peter A1 - Meese, Eckart T1 - Autoantibody Signature Differentiates Wilms Tumor Patients from Neuroblastoma Patients JF - PLoS ONE N2 - Several studies report autoantibody signatures in cancer. The majority of these studies analyzed adult tumors and compared the seroreactivity pattern of tumor patients with the pattern in healthy controls. Here, we compared the autoimmune response in patients with neuroblastoma and patients with Wilms tumor representing two different childhood tumors. We were able to differentiate untreated neuroblastoma patients from untreated Wilms tumor patients with an accuracy of 86.8%, a sensitivity of 87.0% and a specificity of 86.7%. The separation of treated neuroblastoma patients from treated Wilms tumor patients' yielded comparable results with an accuracy of 83.8%. We furthermore identified the antigens that contribute most to the differentiation between both tumor types. The analysis of these antigens revealed that neuroblastoma was considerably more immunogenic than Wilms tumor. The reported antigens have not been found to be relevant for comparative analyses between other tumors and controls. In summary, neuroblastoma appears as a highly immunogenic tumor as demonstrated by the extended number of antigens that separate this tumor from Wilms tumor. KW - Heparan-sulfate KW - N-Myc KW - Serum autoantibodies KW - Suppressors EXT1 KW - Neuro-blastoma KW - Allelic loss KW - Lung-cancer KW - Children KW - Amplification KW - Therapy Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133794 VL - 6 IS - 12 ER - TY - JOUR A1 - Camacho, J.P.M. A1 - Schmid, M. A1 - Cabrero, J. T1 - B Chromosomes and Sex in Animals JF - Sexual Development N2 - Supernumerary (B) chromosomes are dispensable elements found in many eukaryote genomes in addition to standard (A) chromosomes. In many respects, B chromosomes resemble sex chromosomes, so that a common ancestry for them has frequently been suggested. For instance, B chromosomes in grasshoppers, and other insects, show a pycnotic cycle of condensation-decondensation during meiosis remarkably similar to that of the X chromosome. In some cases, B chromosome size is even very similar to that of the X chromosome. These resemblances have led to suggest the X as the B ancestor in many cases. In addition, sex chromosome origin from B chromosomes has also been suggested. In this article, we review the existing evidence for both evolutionary pathways, as well as sex differences for B frequency at adult and embryo progeny levels, B chromosome effects or B chromosome transmission. In addition, we review cases found in the literature showing sex-ratio distortion associated with B chromosome presence, the most extreme case being the paternal sex ratio (PSR) chromosomes in some Hymenoptera. We finally analyse the possibility of B chromosome regularisation within the host genome and, as a consequence of it, whether B chromosomes can become regular members of the host genome. KW - A chromosomes KW - B chromosomes KW - sex ratio KW - X chromosome Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196321 SN - 1661-5425 SN - 1661-5433 N1 - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. VL - 5 IS - 3 ER - TY - JOUR A1 - Groß, Uwe A1 - Amuzu, Sylvarius K. A1 - de Ciman, Ring A1 - Kassimova, Iparkhan A1 - Groß, Lisa A1 - Rabsch, Wolfgang A1 - Rosenberg, Ulrike A1 - Schulze, Marco A1 - Stich, August A1 - Zimmermann, Ortrud T1 - Bacteremia and Antimicrobial Drug Resistance over Time, Ghana JF - Emerging Infectious Diseases N2 - Bacterial distribution and antimicrobial drug resistance were monitored in patients with bacterial bloodstream infections in rural hospitals in Ghana. In 2001-2002 and in 2009, Salmonella enterica serovar Typhi was the most prevalent pathogen. Although most S. enterica serovar Typhi isolates were chloramphenicol resistant, all isolates tested were susceptible to ciprofloxacin. KW - Typhoid-fever KW - Children KW - Surveillance KW - Kenya Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133805 N1 - All material published in Emerging Infectious Diseases is in the public domain and may be used and reprinted without special permission; proper citation, however, is required. VL - 17 IS - 10 ER - TY - JOUR A1 - Hess, Michael A1 - Stritzker, Jochen A1 - Härtl, Barbara A1 - Sturm, Julia A1 - Gentschev, Ivaylo A1 - Szalay, Aladar T1 - Bacterial glucuronidase as general marker for oncolytic virotherapy or other biological therapies N2 - Background: Oncolytic viral tumor therapy is an emerging field in the fight against cancer with rising numbers of clinical trials and the first clinically approved product (Adenovirus for the treatment of Head and Neck Cancer in China) in this field. Yet, until recently no general (bio)marker or reporter gene was described that could be used to evaluate successful tumor colonization and/or transgene expression in other biological therapies. Methods: Here, a bacterial glucuronidase (GusA) encoded by biological therapeutics (e.g. oncolytic viruses) was used as reporter system. Results: Using fluorogenic probes that were specifically activated by glucuronidase we could show 1) preferential activation in tumors, 2) rena l excretion of the activated fluorescent compounds and 3) reproducible detection of GusA in the serum of oncolytic vaccinia virus treated, tumor bearing mice in several tumor models. Time course studies revealed that reliable differentiation between tumor bearing and healthy mice can be done as early as 9 days post injection of the virus. Regarding the sensitivity of the newly developed assay system, we could show that a single infected tumor cell could be reliably detected in this assay. Conclusion: GusA therefore has the potential to be used as a general marker in the preclinical and clinical evaluation of (novel) biological therapies as well as being useful for the detection of rare cells such as circulating tumor cells KW - Virologie KW - beta-glucuronidase KW - oncolytic virus KW - cancer KW - reporter KW - fluorescent probe Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69163 ER - TY - THES A1 - Polzien, Lisa T1 - BAD Phosphorylation: A Novel Link between Apoptosis and Cancer T1 - BAD Phosphorylierung: Eine Neue Verbindung zwischen Apoptose und Krebs N2 - BAD (Bcl-2 antagonist of cell death, Bcl-2 associated death promoter) is a pro-apoptotic member of the Bcl-2 protein family that is regulated by phosphorylation in response to survival factors. Although much attention has been devoted to the identification of phosphorylation sites in murine BAD (mBAD), little data are available with respect to phosphorylation of human BAD (hBAD) protein. In this work, we investigated the quantitative contribution of BAD targeting kinases in phosphorylating serines 75, 99 and 118 of hBAD (Chapter 3.1). Our results indicate that RAF kinases phosphorylate hBAD in vivo at these established serine residues. RAF-induced phosphorylation of hBAD was not prevented by MEK inhibitors but could be reduced to control levels by use of the RAF inhibitor Sorafenib (BAY 43-9006). Consistently, expression of active RAF suppressed apoptosis induced by hBAD and the inhibition of colony formation caused by hBAD could be prevented by RAF. In addition, using surface plasmon resonance technique we analyzed the direct consequences of hBAD phosphorylation by RAF with respect to complex formation of BAD with 14-3-3 proteins and Bcl-XL. Phosphorylation of hBAD by active RAF promotes 14-3-3 protein association, whereby the phosphoserine 99 represents the major binding site. Furthermore, we demonstrate in this work that hBAD forms channels in planar bilayer membranes in vitro. This pore-forming capacity is dependent on phosphorylation status and interaction with 14-3-3 proteins. Additionally, we show that hBAD pores possess a funnel-shaped geometry that can be entered by ions and non-charged molecules up to 200 Da (Chapter 3.2). Since both lipid binding domains of hBAD (LBD1 and LBD2) are located within the C-terminal region, we investigated this part of the protein with respect to its structural properties (Chapter 3.3). Our results demonstrate that the C-terminus of hBAD possesses an ordered β-sheet structure in aqueous solution that adopts helical disposition upon interaction with lipid membranes. Additionally, we show that the interaction of the C-terminal segment of hBAD with the BH3 domain results in the formation of permanently open pores, whereby the phosphorylation of serine 118 proved to be necessary for effective pore-formation. In contrast, phosphorylation of serine 99 in combination with 14-3-3 association suppresses formation of channels. These results indicate that the C-terminal part of hBAD controls hBAD function by structural transitions, lipid binding and phosphorylation. Using mass spectrometry we identified in this work, besides the established in vivo phosphorylation sites at serines 75, 99 and 118, several novel hBAD phosphorylation sites (serines 25, 32/34, 97, 124 and 134, Chapter 3.1). To further analyze the regulation of hBAD function, we investigated the role of these newly identified phosphorylation sites on BAD-mediated apoptosis. We found that in contrast to the N-terminal phosphorylation sites, the C-terminal serines 124 and 134 act in an anti-apoptotic manner (Chapter 3.4). Our results further indicate that RAF kinases and PAK1 effectively phosphorylate BAD at serine 134. Notably, in the presence of wild type hBAD, co-expression of survival kinases, such as RAF and PAK1, leads to a strongly increased proliferation, whereas substitution of serine 134 by alanine abolishes this process. Furthermore, we identified hBAD serine 134 to be strongly involved in survival signaling in B-RAF-V600E containing tumor cells and found phosphorylation of this residue to be crucial for efficient proliferation in these cells. Collectively, our findings provide new insights into the regulation of hBAD function by phosphorylation and its role in cancer signaling. N2 - BAD (Bcl-2 antagonist of cell death, Bcl-2 associated death promoter) ist ein pro-apoptotisches Mitglied der Bcl-2 Proteinfamilie und wird in Abhängigkeit von Wachstumsfaktoren durch Phosphorylierung reguliert. Obwohl der Identifizierung von Phosphorylierungsstellen in murinem BAD (mBAD) in den vergangenen Jahren viel Aufmerksamkeit gewidmet wurde, ist die Phosphorylierung des humanen BAD (hBAD) Proteins kaum charakterisiert. In der vorliegenden Arbeit wird der quantitative Beitrag unterschiedlicher Kinasen in Bezug auf die Phosphorylierung der etablierten Phosphorylierungsstellen Serin 75, 99 und 118 von hBAD dargestellt (Kapitel 3.1). Unsere Ergebnisse deuten darauf hin, dass RAF-Kinasen hBAD in vivo an diesen etablierten Stellen phosphorylieren. Die RAF-bedingte Phosphorylierung konnte nicht durch MEK-Inhibitoren beeinflusst werden, dagegen bewirkte die Gabe des RAF-Inhibitors Sorafenib (BAY 43-9006) eine Reduktion der Phosphorylierung auf das Niveau der Kontrollproben. Übereinstimmend konnte durch die Expression von aktiven RAF-Kinasen die BAD-induzierte Apoptose sowie die BAD-bedingte Inhibierung der Koloniebildung unterdrückt werden. Zusätzlich verwendeten wir Oberflächen-Plasmon-Resonanz-Spektroskopie um die Auswirkungen der RAF-bedingten BAD-Phosphorylierung auf die Komplexbildung von hBAD mit 14-3-3-Proteinen und Bcl-XL zu analysieren. Dabei wurde festgestellt, dass die Phosphorylierung von hBAD durch aktive RAF-Kinasen die Assoziierung von 14-3-3 begünstigt, wobei Phosphoserin 99 die Hauptbindungsstelle darstellt. Weiterhin gelang der Nachweis, dass hBAD in vitro Poren in Lipid-Doppelschicht-Membranen bilden kann. Wir wiesen nach, dass die Fähigkeit von hBAD Poren zu bilden phosphorylierungsabhängig ist und durch die Interaktion mit 14-3-3-Proteinen beeinflusst wird. Außerdem demonstrieren wir in dieser Arbeit, dass die BAD-Poren eine zylinderförmige Geometrie aufweisen und sowohl für Ionen als auch für ungeladene Moleküle mit einer Größe von bis zu 200 Da zugänglich sind (Kapitel 3.2). Da beide Lipid-Bindungsstellen (LBD1 und LBD2) am C-Terminus des hBAD lokalisiert sind, charakterisierten wir des Weiteren diesen Teil des Proteins in Hinblick auf seinen strukturellen Aufbau (Kapitel 3.3). Unsere Ergebnisse demonstrieren, dass der hBAD-C-Terminus in wässriger Lösung eine geordnete β-Faltblattstruktur aufweist und bei Eintritt in eine Lipidumgebung helikale Elemente ausbildet. Zusätzlich zeigen wir in dieser Arbeit, dass die Interaktion des C-terminalen hBAD-Segments mit der BH3-Domäne zur Ausbildung von permanent offenen Poren führt, wobei die Phosphorylierung an Serin 118 eine Notwendigkeit für effektive Porenbildung darstellt. In Gegensatz dazu bewirkte die Phosphorylierung von Serin 99 in Kombination mit der Assoziierung von 14-3-3-Protein eine Inhibierung der Porenbildung. Diese Ergebnisse weisen darauf hin, dass der C-terminale Teil von hBAD durch strukturelle Veränderungen, Lipidbindung und Phosphorylierung entscheidend die Funktion von hBAD reguliert. Mit Hilfe von Massenspektroskopie konnten wir im Rahmen dieser Arbeit, zusätzlich zu den etablierten Phosphorylierungsstellen Serin 75, 99 und 118, einige neue in vivo Phosphorylierungsstellen von hBAD identifizieren (Serin 25, 32/34, 97, 124 und 134, Kapitel 3.1). Um die Regulierung der Funktion von hBAD weiter zu analysieren, untersuchten wir die Rolle dieser neu identifizierten Phosphorylierungsstellen in Bezug auf die BAD-induzierte Apoptose (Kapitel 3.4). Wir fanden heraus, dass im Gegensatz zu den N-terminalen Phosphorylierungsstellen, die Phosphorylierungsstellen am C-Terminus an der Apoptoseregulation mitwirken. Weiterhin weisen unsere Ergebnisse darauf hin, dass RAF-Kinasen, neben PAK1, an der Phosphorylierung von Serin 134 von hBAD beteiligt sind. Interessanterweise bewirkte die Co-Expression von RAF oder PAK1 mit dem wildtypischen hBAD eine erhebliche Verstärkung der Zellproliferation. Diese verstärkte Proliferation konnte durch einen Serin-zu-Alanin-Austausch in hBAD an der Stelle 134 vollständig verhindert werden. Weiterhin entdeckten wir, dass die Phosphorylierung dieser Stelle in B-RAF-V600E enthaltenden Tumorzellen bei der Regulation der Zellproliferation mitwirkt und für eine effiziente Proliferation entscheidend ist. Zusammenfassend gewähren unsere Ergebnisse neue Einblicke in die Regulierung der Funktion von hBAD durch Phosphorylierung sowie in die Rolle von hBAD bei der Krebsentwicklung. KW - Krebs KW - Apoptosis KW - Bcl-2-Proteinfamilie KW - Raf KW - BH3-only proteins KW - BAD KW - cancer Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-56919 ER - TY - THES A1 - Stock, Patrick Maria T1 - Binding site contribution in high resolution records of nicotinic receptor channel currents T1 - Beitrag der Bindungsstellen zum Öffnungsverhalten des nAChRs N2 - The nicotinic acetylcholine receptor of skeletal muscle is one of the best-investigated synaptic proteins and often serves as model for the entire family of pentameric ligand gated ion channels (pLGICs). Receptors of this superfamily share a common architecture. After binding the agonist the characteristic C-loop structure closes around the ligand-binding site and triggers a wave of conformational changes that spread through the protein and finally result in the opening of the channel gate. As shown before, high-resolution single channel data can hardly be described by simple kinetic mechanisms (Parzefall et al., 1998, Hallermann et al., 2005). Recent advances in the field of kinetic modelling on receptor currents demonstrate that the introduction of additional short lived shut states in kinetic schemes enhances the quality of estimates of reaction rates. The additional shut states that immediately follow ligand bound states in the mechanism are suggested to resemble the closing movement of the C-loop (Lape et al., 2008; Mukhtasimova et al., 2009). It has not been described yet whether and how the structural differences of the 2 binding sites of the receptor influence the opening behaviour. To address this question, high-resolution single channel recordings, in combination with agonists that are known to exhibit different binding site selectivity, were performed. Thereby, a detailed description of the binding site dependent generation of channel currents is possible. At the embryonic mouse-muscle receptor used in this study the ligand binding sites are located at the α-γ and α-δ subunit interfaces. By allocation of opening characteristics to the α-δ and α-γ sites it is possible to show the binding site dependent activation of distinct kinetic states. Furthermore, it will be shown that the recently introduced short-lived shut states are sufficient to describe high-resolution single channel data. Finally an enhanced kinetic mechanism based on the ‘primed states’ model, published in 2009 by Mukhtasimova et al., will be presented. In this model the structurally diverse α-δ and α-γ binding sites elicit different kinetic channel characteristics. Thus the complex high-resolution kinetic characteristics of the embryonic receptor can be described coherently. N2 - Der nicotinische Acetylcholin-Rezeptorkanal des Skelettmuskels zählt zu den bestuntersuchten synaptischen Proteinen und gilt als Modell für die Familie der Liganden gesteuerten pentameren Ionenkanäle. Rezeptoren dieser Großfamilie besitzen als charakteristisches strukturelles Merkmal ein Cystein-Schleifen-Motiv (C-loop), welches sich nach Bindung eines Agonisten um die Bindungstasche herum schließt und eine Kette weiterer Konformationsänderungen nach sich zieht. Wie in früheren Publikationen festgestellt wurde, ist es nur schwer möglich hochaufgelöste Messdaten mit konservativen kinetischen Modellen ausreichend zu beschreiben (Parzefall et al., 1998; Hallermann et al., 2005). Aktuelle Fortschritte auf dem Gebiet der kinetischen Modellierung von mechanistischen Rezeptormodellen auf Rezeptorströme, zeigen, dass die Einführung zusätzlicher kurzlebiger Geschlossenzustände in den kinetischen Mechanismen die Qualität der Voraussagen der Modelle verbessert. Diese zusätzlichen Geschlossenzustände, welche Zuständen mit gebundenen Agonisten des Rezeptormodells folgen, spiegeln höchstwahrscheinlich die Schließung des Cystein-Schleifen-Motivs wider (Lape et al., 2008; Mukhtasimova et al., 2009). Trotz der jüngsten Fortschritte wurde bisher nicht beschrieben, wie und ob die strukturellen Unterschiede der 2 vorhandenen Bindungsstellen sich auf die Charakteristika des Öffnungsverhaltens auswirken. Die Bindungsstellen für Agonisten befinden sich am embryonalen nicotinischen Acetylcholinrezeptor des Muskels der Maus an den Schnittstellen der α-δ und der α-γ Untereinheiten. Um der Frage des Einflusses der Bindungsstellendiversität auf den Grund zu gehen, wurden hochaufgelöste Einzelkanalmessungen unter der Verwendung von unterschiedlichen Agonisten, für die bekannt ist, dass sie unterschiedliche Selektivitäten zu den Bindungsstellen besitzen, durchgeführt. Hierdurch ist es möglich ein detailliertes Bild der bindungsstellenbedingten Auslösung definierter Öffnungscharakteristika zu beschreiben. Durch die Zuweisung der Öffnungscharakteristika zu den α-δ und α-γ Bindungsstellen gelingt es die bindungsstellenabhängige Aktivierung von einzelnen kinetischen Zuständen zu zeigen. Darüber hinaus werden direkte Anhaltspunkte dafür gezeigt, dass es möglich ist mit den angeführten kurzlebigen Geschlossenzuständen hochaufgelöste Einzelkanaldaten kinetisch hinreichend zu beschreiben. Schließlich wird ein erweiterter kinetischer Mechanismus vorgestellt, welcher auf dem ‚primed-states’ Modell, das 2009 von Mukhtasimova veröffentlicht wurde, basiert. Zusätzlich ist dieser in der Lage die komplexen kinetischen Charakteristika des embryonalen nicotinischen Rezeptorkanals, unter hoher zeitlicher Auflösung der Messdaten, zu beschreiben. KW - Nicotinischer Acetylcholinrezeptor KW - Bindestelle KW - Ionenkanal KW - Kinetik KW - Neurobiologie KW - nAChR KW - Kanalkinetik KW - Bindungsstellen KW - Rezeptor KW - neurobiology KW - nAChR KW - receptor channel KW - binding sites KW - kinetics Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-71769 ER - TY - THES A1 - Beitzinger, Christoph T1 - Binding-, Blocking- and Translocation-Processes Concerning Anthrax-Toxin and Related Bacterial Protein-Toxins of the AB7-Family T1 - Charakterisierung von Bindungs-, Blockierungs- und Translokationsprozessen am Anthrax-Toxin und verwanten Toxinen der AB7-Gruppe N2 - Bacterial protein toxins belong to the most potent toxins which are known. They exist in many different forms and are part of our every day live. Some of them are spread by the bacteria during infections and therefore play a crucial role in pathogenicity of these strains. Others are secreted as a defense mechanism and could be uptaken with spoiled food. Concerning toxicity, some of the binary toxins of the AB7-type belong to the most potent and dangerous toxins in the world. Even very small amounts of these proteins are able to cause severe symptoms during an infection with pathogen species of the genus Clostridium or Bacillus. Apart from the thread the toxins constitute, they exhibit a unique way of intoxication. Members of the AB7-toxin family consist of a pore-forming subunit B, that acts as a molecular syringe to translocate the enzymatic moieties A into the cytosol of target cells. This complex mechanism does not only kill cells with high efficiency and therefore should be studied for treatment, but also displays a possibility to address certain cells with a specific protein cargo if used as a molecular delivery tool. Concerning both issues, binding and translocation of the channel are the crucial steps to either block or modify the system in the desired way. To gain deeper insight into the transport of binary toxins the structure of the B subunit is of great importance, but being a membrane protein, no crystal could be obtained up to now for either protective antigen (PA) of Anthrax toxin or any other AB7-type binding domain. Therefore, the method of choice in this work is an electro-physical approach using the so-called black-lipid-bilayer system for determination of biophysical constants. Additionally, diverse cell based assays serve as a proving method for the data gained during in vitro measurements. Further information was gathered with specially designed mutants of the protein channel. The first part of this thesis focuses on the translocation process and its possible use as a molecular tool to deliver protein cargo into special cell types. The task was addressed by measuring the binding of different effector proteins related and unrelated to the AB7 toxin family. These proteins were tested in titration experiments for the blockage of the ion current through a membrane saturated with toxin channels. Especially the influence of positively charged His-tags has been determined in detail for PA and C2II. As described in chapter 2, a His-tag transferred the ability of being transported by PA, but not by C2II, to different proteins like EDIN (from S. aureus) in vitro and in cell-based experiments. This process was found to change the well-known voltage-dependency of PA to a huge extend and therefore is related to membrane potentials which play a crucial role in many processes in living cells. Chapter 3 sums up findings, which depict that binding partners of PA share certain common motives. These could be detected in a broad range of substrates, ranging from simple ions in an electrolyte over small molecules to complex protein effectors. The gathered information could be further used to design blocker-substrates for treatment of Anthrax infections or tags, which render PA possible as a molecular syringe for cargo proteins. The deeper insight to homologies and differences of binary toxin components is the core of chapter 4, in which the cross-reactivity of Anthrax and C2-toxin was analyzed. The presented results lead to a better understanding of different motives involved in binding and translocation to and via the B components PA and C2II, as well as the enzymatically active A moieties edema factor (EF), lethal factor (LF) and C2I. In the second part of the thesis, the blockage of intoxication is the center of interest. Therefore, chapter 5 focuses on the analysis of specially designed blocker-substrate molecules for PA. These molecules form a plug in the pore, abolishing translocation of the enzymatic units. Especially, if multi-resistant strains of Anthrax (said to be already produced in Russia as a biological weapon) are taken into consideration, these substrates could stop intoxication and buy time, to deal with the infection. Chapter 6 describes the blockage of PA-channels by anti-His antibody from the trans-side of the porin, an effect which was not described for any other antibody before. Interestingly, even mutation of the estimated target amino acid Histidine 310 to Glycine could not interfere with this ionic strength dependent binding. N2 - Bakterielle Protein-Toxine gehören zu den wirksamsten bekannten Toxinen. In vielfältigen Variationen findet man sie in allen Bereichen des Lebens. Einige werden von den Bakterien während einer Infektion freigesetzt und übernehmen einen wichtigen Part in der Pathogenität. Andere werden zu Verteidigungszwecken sekretiert und können in verdorbenen Lebensmitteln gefunden werden. Was die Wirkung binärer Toxine der AB7-Gruppe angeht, so gehören diese zu den potentesten und gefährlichsten Giften weltweit. Selbst kleine Mengen dieser Proteine können schwerste Symptome während einer Infektion mit Bakterien der Gattung Clostridium oder Bacillus verursachen. Abgesehen von der Bedrohung die durch die Toxine ausgeht, zeichnen sie sich durch einen einzigartigen Intoxikationsmechanismus aus. AB7-Toxine sind aus einer porenformenden Domäne B, die als eine Art molekulare Injektionskanüle fungiert, und enzymatisch aktiven Proteinen A zusammengesetzt. Der komplexe Wirkmechanismus ermöglicht es nicht nur Zellen in höchst effektiver Weise abzutöten und sollte deswegen zu Behandlungszwecken untersucht werden, sondern könnte auch als molekulares Werkzeug umfunktioniert werden, um spezielle Zellen mit gewünschten Proteinen zu beladen. Für beide Zwecke (Blockierung und gezielter Transport) ist die Bindung an, und der Transport durch die porenformende Domäne von größter Bedeutung. Die Struktur der B-Domäne ist wichtig um tiefere Einsicht in den Transportprozess der binären Toxine zu ermöglichen. Leider ist es bisher nicht gelungen die Kristallstruktur des Membranproteins protective antigen (PA) von Anthrax oder irgendeiner anderen Bindedomäne eines AB7-Toxins zu lösen. Deshalb wurde in dieser Arbeit ein elektrophysiologischer Ansatz zur Bestimmung der biophysikalischen Konstanten des Prozesses gewählt, die Black-lipid-Bilayer Methode. Zusätzliche Versuche an Zellen und mit Mutanten der Proteine dienen zur Absicherung der in vitro Ergebnisse. Im ersten Teil der Arbeit wird der Translokationsmechanismus, und die mögliche Nutzung dessen als molekulares Werkzeug näher behandelt. Dies erfolgte durch Bindungsstudien an PA und C2II mit Effektoren (sowohl aus der AB7-Familie, als auch nicht näher verwandt). In Kapitel 2 wird beschrieben, dass ein His-Tag es EDIN (von S. aureus) und anderen Effektoren ermöglicht, dass ein Transport durch PA-Poren in vitro und in vivo stattfindet (nicht aber durch C2II). Ebenfalls konnte eine starke Abweichung in der bekannten Spannungsabhängigkeit von PA festgestellt werden, die den Prozess eindeutig mit den Membranpotentialen in Verbindung bringt, die häufig eine wichtige Rolle im Metabolismus spielen. Kapitel 3 fasst zusammen, dass Bindungspartner von PA bestimmte Motive beinhalten, die von Substraten wie Ionen in Elektrolyten, über kleine Moleküle, bis hin zu komplexen Proteinen reichen. Diese Erkenntnisse könnten genutzt werden um Blockersubstanzen zur Behandlung von Anthrax, oder Tags zur Aufnahme durch Anthrax zu designen. Neueste Befunde zu Homologien und Unterschieden zwischen den Komponenten der binären Toxine sind der Kern von Kapitel 4, in dem die Kreuzreaktivität von Anthrax und C2-Toxin analysiert wurde. Die enthaltenen Daten ermöglichen einen tieferen Einblick in die verschiedenen Stufen der Bindung und Translokation des edema factor (EF), des lethal factor (LF) und von C2I an und durch PA und C2II. Im zweiten Teil rückt die Blockierung der Intoxikation in den Fokus. Die Analyse speziell designter Blockersubstanzen für PA wird in Kapitel 5 behandelt. Diese formen einen Porenverschluss, der weiteren Transport von Toxinkomponenten verhindert. Eine besondere Bedeutung könnten diese Substanzen im Zusammenhang mit Multiresitenz bei Anthrax Stämmen (vermutlich in Russland als biologische Waffe hergestellt) zur Verhinderung von Symptomen und der Verlängerung der Zeit spielen, die man hat um neue Antibiotika zu erzeugen. Kapitel 6 beschreibt zum ersten Mal die Blockierung von PA-Poren mittels eines Anti-His Antikörpers von der trans-Seite aus. Interessanterweise trat diese Ionenstärke abhängige Blockierung, auch bei einer Histidin zu Glycin Mutation an der Stelle 310 (vermutete Bindeposition) auf. KW - Bacillus anthracis KW - Translokation KW - Toxin KW - Protective antigen KW - Bindungsprozess KW - Black-lipid-bilayer KW - Bacillus anthracis KW - protective antigen KW - Anthrax Toxin KW - translocation Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-70052 ER - TY - THES A1 - Sengupta, Sanchita T1 - Bio-inspired Zinc Chlorin Dye Assemblies for Supramolecular Electronics T1 - Bio-adaptierte Zink-Chlorin Farbstoffverbände für supramolekulare Elektronik N2 - Chlorophylls are the most important pigments owing to their involvement in photosynthesis. They perform multiple functions that arise due to their optical and redox as well as packing properties. Semisynthetic zinc chlorins investigated in this thesis are the counterparts for the natural protein-free bacteriochlorophyll (BChl) c assemblies in light-harvesting (LH) systems in bacterial chlorosomes. The major advantage of the zinc chlorin model compounds over the native BChls lies in their facile semisynthetic accessibility from chlorophyll a (Chl a), their higher chemical stability and the possibility to influence their packing by suitable chemical modifications of peripheral side chains. Whilst the favorable excitonic properties and the suitability of ZnChl and natural BChl c dye aggregates for long distance exciton transport are well documented, charge transport properties of aggregates of semisynthetic ZnChls are hitherto unexplored. The present study involves structural elucidations of aggregates of a variety of semisynthetic zinc chlorin derivatives in solution, in solid state and on surfaces by combination of spectroscopic, crystallographic and microscopic techniques, followed by investigation of charge transport properties and conductivities of these aggregates. Chart 1 shows the different ZnChls synthesized in this work that are functionalized with hydroxy or methoxy substituents at 31 position and contain different substituents at the 172-position benzyl ester functional group. The self-assembly of these dyes is strongly dependent upon their chemical structures. While ZnChls 1a, 2a, 3, which are functionalized with 31-hydroxy group bearing dodecyl and oligoethylene glycol side chains form well-soluble rod aggregates, the corresponding 31-methoxy functionalized counterparts 1b, 2b form stacks in solution and on surfaces. These supramolecular polymers have been studied in detail in Chapter 3 by UV/Vis and circular dichroism (CD) spectroscopy and dynamic light scattering (DLS). These studies provided useful insights into the aggregation process of these two types of aggregates. Whereas 31-hydroxy functionalized ZnChl 1a self-assemble into rod aggregates via an isodesmic mechanism, corresponding stack aggregates of ZnChl 1b are formed by a cooperative nucleation-elongation pathway. Detailed electron microscopic studies such as transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) provided unequivocal evidence for hollow tubular nanostructures of water-soluble 31-hydroxy zinc chlorin 3 aggregates for the first time. The measured tube diameter of ~ 5-6 nm of these aggregates is in excellent agreement with electron microscopy data of BChl c rod aggregates in chlorosomes (Chloroflexus aurantiacus, diameter ~ 5-6 nm) and thus complied with the tubular model postulated by Holzwarth and Schaffner... In concord with their highly organized structures, micrometer-scale one dimensionality, robust nature and efficient charge transport capabilities, these self-assembled ZnChl nanotubular, stack and liquid crystalline assemblies are highly promising for supramolecular electronic applications. Research efforts in utilizing these assemblies for (opto)electronic device fabrication, for instance, in organic field effect transistors, should thus be rewarding in the future... N2 - Die Chlorophylle stellen in der Natur die wichtigsten Pigmente dar, weil sie verantwortlich für die Photosynthese sind und hierbei vielfältige Funktionen wahrnehmen, die sich aus ihrer Selbstassemblierung sowie den vorteilhaften optischen und Redox-Eigenschaften ergeben. Die in dieser Arbeit untersuchten semisynthetischen Zinkchlorine stellen Modellverbindungen des natürlichen Bacteriochlorophylls c (BChl c) der Lichtsammelsysteme (light-harvesting: LH) in Chlorosomen von Bakterien, jedoch ohne Proteingerüst, dar. Die entscheidenden Vorteile dieser Zinkchlorine (ZnChl) gegenüber den natürlichen BChls bestehen im einfachen semisynthetischen Zugang ausgehend von Chlorophyll a (Chl a), ihrer gesteigerten chemischen Stabilität sowie der Möglichkeit ihre Selbstassemblierung durch gezielte chemische Modifizierung der Seitenketten in der Peripherie zu steuern. Während bereits mehrfach über die vielversprechenden Redox- und excitonischen Eigenschaften von Aggregaten von ZnChl und natürlichem BChl c und den damit verbundene Voraussetzungen für Excitontransport über große Distanzen berichtet wurde, sind die Ladungstransporteigenschaften von Aggregaten der biomimetischen ZnChl bis heute unerforscht. Die vorliegende Arbeit beschäftigt sich mit der Aufklärung der Struktur von Aggregaten einer Vielzahl von semisynthetischen Zinkchlorophyllderivaten im Feststoff, in Lösung und auf Oberflächen durch die Kombination verschiedenster spektroskopischer, kristallographischer und mikroskopischer Techniken an die sich Untersuchungen zum Ladungstransport in den Aggregaten anschließen. Schema 1 zeigt die verschiedenen, in dieser Arbeit synthetisierten ZnChls, die entweder mit einer Hydroxy- oder Methoxygruppe in der 31-Position funktionalisiert sind sowie Substituenten unterschiedlicher Art, Länge und Verzweigung an der Benzylestergruppe in 172-Position tragen.Die Packung dieser Farbstoffe hängt entscheidend von ihrer chemischen Struktur ab. Während die ZnChls 1a, 2a, 3 mit 31-Hydroxygruppe und Alkylseitenketten (Dodecyl bzw. Oligoethylenglykol) gut lösliche stabförmige Aggregate bilden, lagern sich die analogen Verbindungen mit 31-Methoxygruppe (1b, 2b) zu Stapeln in Lösung und auf Oberflächen zusammen. Diese supramolekularen Polymere wurden im Detail in Kapitel 3 mit Hilfe von UV/Vis- und CD-Spektroskopie (circular dichroism: CD) sowie dynamische Lichtstreuung (dynamic light scattering: DLS) untersucht. Darüber hinaus lieferten temperaturabhängige UV/Vis- in Kombination mit DLS-Messungen wertvolle Informationen über die Aggregationsprozess dieser beiden Sorten von Aggregaten. Während sich die ZnChl 1a mit 31 Hydroxygruppe entsprechend dem isodesmischen Modell zu röhrenförmigen Aggregaten zusammenlagern, bilden sich die stapelförmigen Aggregate von 1b nach einem kooperativen Keimbildungs-Wachstums-Mechanismus (nucleation-elongation mechanism). Detaillierte elektronenmikroskopische Studien lieferten erstmals überzeugende Beweise für röhrenförmige Nanostrukturen der Aggregate des wasserlöslichen 31-Hydroxy Zinkchlorin 3. Die gemessenen Durchmesser der Röhren von ~ 5-6 nm dieser Aggregate liegen in hervorragender Übereinstimmung mit den Elektronenmikroskopie-Daten von BChl c Stabaggregaten in Chlorosomen (Chloroflexus aurantiacus, Durchmesser ~ 5-6 nm) und entsprechen damit dem von Holzwarth und Schaffner postulierten röhrenförmigen Modell... Im Einklang mit ihren hoch geordneten, robusten Strukturen, die sich eindimensional in einer Größenordnung von Mikrometeren erstrecken, sowie ihrer Fähigkeit zum effizienten Ladungs-trägertransport stellen diese selbstassemblierten Nanoröhren von ZnChls vielversprechende Ausgangsmaterialien für die Fertigung supramolekularer elektronischer Bauteile dar. Wissenschaftliche Bemühungen einige dieser Moleküle und ihre entsprechenden supramolekularen Polymere für die Fertigung von (opto-)elektronischen Bauteilen wie organischen Feldeffekttransistoren zu benutzten, stellen lohnende Aufgaben für die Zukunft dar... KW - Supramolekulare Chemie KW - Selbstorganisation KW - Chlorinderivate KW - Farbstoff KW - Selbstassemblierung KW - supramolekularen Elektronik KW - Zinkchlorine KW - Zinc Chlorin KW - Self-assembly KW - Supramolecular electronics Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-66935 ER - TY - JOUR A1 - Eberlein, Uta A1 - Bröer, Jörn Hendrik A1 - Vandevoorde, Charlot A1 - Santos, Paula A1 - Bardiès, Manuel A1 - Bacher, Klaus A1 - Nosske, Dietmar A1 - Lassmann, Michael T1 - Biokinetics and dosimetry of commonly used radiopharmaceuticals in diagnostic nuclear medicine – a review JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - Purpose The impact on patients’ health of radiopharmaceuticals in nuclear medicine diagnostics has not until now been evaluated systematically in a European context. Therefore, as part of the EU-funded Project PEDDOSE.NET (www.​peddose.​net), we review and summarize the current knowledge on biokinetics and dosimetry of commonly used diagnostic radiopharmaceuticals. Methods A detailed literature search on published biokinetic and dosimetric data was performed mostly via PubMed (www.​ncbi.​nlm.​nih.​gov/​pubmed). In principle the criteria for inclusion of data followed the EANM Dosimetry Committee guidance document on good clinical reporting. Results Data on dosimetry and biokinetics can be difficult to find, are scattered in various journals and, especially in paediatric nuclear medicine, are very scarce. The data collection and calculation methods vary with respect to the time-points, bladder voiding, dose assessment after the last data point and the way the effective dose was calculated. In many studies the number of subjects included for obtaining biokinetic and dosimetry data was fewer than ten, and some of the biokinetic data were acquired more than 20 years ago. Conclusion It would be of interest to generate new data on biokinetics and dosimetry in diagnostic nuclear medicine using state-of-the-art equipment and more uniform dosimetry protocols. For easier public access to dosimetry data for diagnostic radiopharmaceuticals, a database containing these data should be created and maintained. KW - Dosimetry KW - Biokinetics KW - Diagnostic radiopharmaceuticals KW - Effective dose Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133846 VL - 38 IS - 12 ER - TY - JOUR A1 - Gerlach, Manfred A1 - Maetzler, Walter A1 - Broich, Karl A1 - Hampel, Harald A1 - Rems, Lucas A1 - Reum, Torsten A1 - Riederer, Peter A1 - Stöffler, Albrecht A1 - Streffer, Johannes A1 - Berg, Daniela T1 - Biomarker candidates of neurodegeneration in Parkinson’s disease for the evaluation of disease-modifying therapeutics JF - Journal of Neural Transmission N2 - Reliable biomarkers that can be used for early diagnosis and tracking disease progression are the cornerstone of the development of disease-modifying treatments for Parkinson’s disease (PD). The German Society of Experimental and Clinical Neurotherapeutics (GESENT) has convened a Working Group to review the current status of proposed biomarkers of neurodegeneration according to the following criteria and to develop a consensus statement on biomarker candidates for evaluation of disease-modifying therapeutics in PD. The criteria proposed are that the biomarker should be linked to fundamental features of PD neuropathology and mechanisms underlying neurodegeneration in PD, should be correlated to disease progression assessed by clinical rating scales, should monitor the actual disease status, should be pre-clinically validated, and confirmed by at least two independent studies conducted by qualified investigators with the results published in peer-reviewed journals. To date, available data have not yet revealed one reliable biomarker to detect early neurodegeneration in PD and to detect and monitor effects of drug candidates on the disease process, but some promising biomarker candidates, such as antibodies against neuromelanin, pathological forms of α-synuclein, DJ-1, and patterns of gene expression, metabolomic and protein profiling exist. Almost all of the biomarker candidates were not investigated in relation to effects of treatment, validated in experimental models of PD and confirmed in independent studies. KW - Parkinson’s disease KW - Disease-modifying therapies KW - Neuroprotection KW - Biomarkers KW - Surrogate endpoints KW - Drug development KW - Disease progression Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133856 VL - 119 IS - 1 ER - TY - JOUR A1 - Ondrusch, Nicolai A1 - Kreft, Jürgen T1 - Blue and Red Light Modulates SigB-Dependent Gene Transcription, Swimming Motility and Invasiveness in \(Listeria\) \(monocytogenes\) JF - PLoS ONE N2 - Background: In a number of gram-positive bacteria, including Listeria, the general stress response is regulated by the alternative sigma factor B (SigB). Common stressors which lead to the activation of SigB and the SigB-dependent regulon are high osmolarity, acid and several more. Recently is has been shown that also blue and red light activates SigB in Bacillus subtilis. Methodology/Principal Findings: By qRT-PCR we analyzed the transcriptional response of the pathogen L. monocytogenes to blue and red light in wild type bacteria and in isogenic deletion mutants for the putative blue-light receptor Lmo0799 and the stress sigma factor SigB. It was found that both blue (455 nm) and red (625 nm) light induced the transcription of sigB and SigB-dependent genes, this induction was completely abolished in the SigB mutant. The blue-light effect was largely dependent on Lmo0799, proving that this protein is a genuine blue-light receptor. The deletion of lmo0799 enhanced the red-light effect, the underlying mechanism as well as that of SigB activation by red light remains unknown. Blue light led to an increased transcription of the internalin A/B genes and of bacterial invasiveness for Caco-2 enterocytes. Exposure to blue light also strongly inhibited swimming motility of the bacteria in a Lmo0799- and SigB-dependent manner, red light had no effect there. Conclusions/Significance: Our data established that visible, in particular blue light is an important environmental signal with an impact on gene expression and physiology of the non-phototrophic bacterium L. monocytogenes. In natural environments these effects will result in sometimes random but potentially also cyclic fluctuations of gene activity, depending on the light conditions prevailing in the respective habitat. KW - Gram-positive bacteria KW - Sigma(B)-dependent stress-response KW - Non-phototrophic bacteria KW - Prfa-mediated virulence KW - NTP-binding-properties KW - Bacillus-subtilis KW - Receptor ytva KW - Lov domain KW - Factor sigma(B) Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134050 VL - 6 IS - 1 ER - TY - JOUR A1 - Ondrusch, Nicolai A1 - Kreft, Jürgen T1 - Blue and Red Light Modulates SigB-Dependent Gene Transcription, Swimming Motility and Invasiveness in Listeria monocytogenes N2 - Background: In a number of gram-positive bacteria, including Listeria, the general stress response is regulated by the alternative sigma factor B (SigB). Common stressors which lead to the activation of SigB and the SigB-dependent regulon are high osmolarity, acid and several more. Recently is has been shown that also blue and red light activates SigB in Bacillus subtilis. Methodology/Principal Findings: By qRT-PCR we analyzed the transcriptional response of the pathogen L. monocytogenes to blue and red light in wild type bacteria and in isogenic deletion mutants for the putative blue-light receptor Lmo0799 and the stress sigma factor SigB. It was found that both blue (455 nm) and red (625 nm) light induced the transcription of sigB and SigB-dependent genes, this induction was completely abolished in the SigB mutant. The blue-light effect was largely dependent on Lmo0799, proving that this protein is a genuine blue-light receptor. The deletion of lmo0799 enhanced the red-light effect, the underlying mechanism as well as that of SigB activation by red light remains unknown. Blue light led to an increased transcription of the internalin A/B genes and of bacterial invasiveness for Caco-2 enterocytes. Exposure to blue light also strongly inhibited swimming motility of the bacteria in a Lmo0799- and SigB-dependent manner, red light had no effect there. Conclusions/Significance: Our data established that visible, in particular blue light is an important environmental signal with an impact on gene expression and physiology of the non-phototrophic bacterium L. monocytogenes. In natural environments these effects will result in sometimes random but potentially also cyclic fluctuations of gene activity, depending on the light conditions prevailing in the respective habitat. KW - Listeria monocytogenes Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75451 ER - TY - JOUR A1 - von Bueren, André O. A1 - Oehler, Christoph A1 - Shalaby, Tarek A1 - von Hoff, Katja A1 - Pruschy, Martin A1 - Seifert, Burkhardt A1 - Gerber, Nicolas U. A1 - Warmuth-Metz, Monika A1 - Stearns, Duncan A1 - Eberhart, Charles G. A1 - Kortmann, Rolf D. A1 - Rutkowski, Stefan A1 - Grotzer, Michael A. T1 - c-MYC expression sensitizes medulloblastoma cells to radio- and chemotherapy and has no impact on response in medulloblastoma patients JF - BMC Cancer N2 - Background: To study whether and how c-MYC expression determines response to radio-and chemotherapy in childhood medulloblastoma (MB). Methods: We used DAOY and UW228 human MB cells engineered to stably express different levels of c-MYC, and tested whether c-MYC expression has an effect on radio-and chemosensitivity using the colorimetric 3-(4,5-dimethylthiazol- 2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, clonogenic survival, apoptosis assays, cell cycle analysis, and western blot assessment. In an effort to validate our results, we analyzed c-MYC mRNA expression in formalin-fixed paraffin-embedded tumor samples from well-documented patients with postoperative residual tumor and compared c-MYC mRNA expression with response to radio-and chemotherapy as examined by neuroradiological imaging. Results: In DAOY -and to a lesser extent in UW228 -cells expressing high levels of c-MYC, the cytotoxicity of cisplatin, and etoposide was significantly higher when compared with DAOY/UW228 cells expressing low levels of c-MYC. Irradiation-and chemotherapy-induced apoptotic cell death was enhanced in DAOY cells expressing high levels of c-MYC. The response of 62 of 66 residual tumors was evaluable and response to postoperative radio-(14 responders (CR, PR) vs. 5 non-responders (SD, PD)) or chemotherapy (23 CR/PR vs. 20 SD/PD) was assessed. c-MYC mRNA expression was similar in primary MB samples of responders and non-responders (Mann-Whitney U test, p = 0.50, ratio 0.49, 95% CI 0.008-30.0 and p = 0.67, ratio 1.8, 95% CI 0.14-23.5, respectively). Conclusions: c-MYC sensitizes MB cells to some anti-cancer treatments in vitro. As we failed to show evidence for such an effect on postoperative residual tumors when analyzed by imaging, additional investigations in xenografts and larger MB cohorts may help to define the exact function of c-MYC in modulating response to treatment. KW - Induced apoptosis KW - Down-regulation KW - Childhood medulloblastoma KW - Melanoma-cells KW - Cisplatin KW - Lines KW - Gene KW - Radiotherapy KW - Fibroblasts KW - Activation Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134185 VL - 11 IS - 74 ER - TY - JOUR A1 - Förtsch, Christina A1 - Hupp, Sabrina A1 - Ma, Jiangtao A1 - Mitchell, Timothy J. A1 - Maier, Elke A1 - Benz, Roland A1 - Iliev, Asparouh I. T1 - Changes in Astrocyte Shape Induced by Sublytic Concentrations of the Cholesterol-Dependent Cytolysin Pneumolysin Still Require Pore-Forming Capacity N2 - Streptococcus pneumoniae is a common pathogen that causes various infections, such as sepsis and meningitis. A major pathogenic factor of S. pneumoniae is the cholesterol-dependent cytolysin, pneumolysin. It produces cell lysis at high concentrations and apoptosis at lower concentrations. We have shown that sublytic amounts of pneumolysin induce small GTPase-dependent actin cytoskeleton reorganization and microtubule stabilization in human neuroblastoma cells that are manifested by cell retraction and changes in cell shape. In this study, we utilized a live imaging approach to analyze the role of pneumolysin’s pore-forming capacity in the actin-dependent cell shape changes in primary astrocytes. After the initial challenge with the wild-type toxin, a permeabilized cell population was rapidly established within 20–40 minutes. After the initial rapid permeabilization, the size of the permeabilized population remained unchanged and reached a plateau. Thus, we analyzed the non-permeabilized (non-lytic) population, which demonstrated retraction and shape changes that were inhibited by actin depolymerization. Despite the non-lytic nature of pneumolysin treatment, the toxin’s lytic capacity remained critical for the initiation of cell shape changes. The non-lytic pneumolysin mutants W433F-pneumolysin and delta6-pneumolysin, which bind the cell membrane with affinities similar to that of the wild-type toxin, were not able to induce shape changes. The initiation of cell shape changes and cell retraction by the wild-type toxin were independent of calcium and sodium influx and membrane depolarization, which are known to occur following cellular challenge and suggested to result from the ion channel-like properties of the pneumolysin pores. Excluding the major pore-related phenomena as the initiation mechanism of cell shape changes, the existence of a more complex relationship between the pore-forming capacity of pneumolysin and the actin cytoskeleton reorganization is suggested. KW - Toxikologie KW - pneumolysin KW - pore formation KW - cytoskeleton Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69084 ER - TY - THES A1 - Merkel, Carla Jennifer T1 - Characterisation of Mena Promoter Activity and Protein Expression in Wild-type and Gene-trapped Mice T1 - Charakterisierung der Mena-Promotor-Aktivität und Protein-Expression in Wildtyp- und Gene-trap-Mäusen N2 - Proteins of the Ena/VASP protein family are important regulators of actin and participate in cell-cell and cell-matrix adhesions. To date, the physiological importance of Ena/VASP proteins for integrity of the cardiovascular system has remained unclear. To study cardiovascular functions of Mena and VASP, we used an established VASP knockout mouse in combination with a novel gene-trap-based model to ablate Mena function. In the mutated Mena mouse, the endogenous Mena gene is disrupted by the insertion of a β-galactosidase construct and β-galactosidase expression is under the control of the endogenous Mena promoter. X-gal staining of mouse organs revealed Mena promoter activity in smooth muscle layers of vessels, intestines and bronchioles, but also in cells of the brain, in cardiomyocytes and in the respiratory epithelium of bronchioles. In wild-type mice, Western blotting revealed differing protein expression patterns of VASP and Mena. Mena expression was observed in almost every tissue, predominantly in heart, lung, stomach, large intestine, testis, brain and eye. Additionally, the neuronalspecific Mena isoform was expressed in brain, eye, and slightly in heart and stomach. VASP protein, in contrast, was predominantly detected in spleen and thrombocytes. In gene-trapped mice, Mena expression was largely reduced in heart, lung and stomach but only slightly decreased in brain and testis. Immunofluorescence microscopy revealed colocalisation of Mena and F-actin at intercalated discs of cardiomyocytes and strong colocalisation of Mena and α- smooth-muscle-actin in vessels and bronchioles. Functional analysis of Mena/VASP-mutated and wild-type mice using electrocardiography suggested that the depletion of either Mena or VASP does not interfere with normal heart function. However, in double-deficient mice, the resting heart rate was significantly increased, probably reflecting a mechanism to compensate defects in ventricle contraction and to maintain a normal cardiac output. In agreement, cardiac catheter investigations suggested dilated cardiomyopathy in doubledeficient mice. Thus, although Western blot analysis showed differing protein expression patterns of Mena and VASP, these findings suggest that Mena and VASP mutually compensate for each other. Concerning Mena, we propose an important role of the protein in vessel walls, cardiomyocytes and bronchioles. N2 - Proteine der Ena/VASP-Familie sind wichtige Regulatoren der Aktin-Dynamik und sind Bestandteile von Zell-Zell- und Zell-Matrix-Kontakten. Bis heute ist die physiologische Bedeutung der Ena/VASP-Proteine speziell im kardiovaskulären System noch nicht geklärt. Um die kardiovaskuläre Funktion von Mena (mammalian Ena) und VASP zu untersuchen, nutzten wir eine etablierte VASP-Knockout-Maus in Kombination mit einem neuen Gene-trap-Maus-Modell, welches die Mena-Funktion ausschaltet. In der mutierten Mena-Maus wird das endogene Mena-Gen durch die Insertion eines β-Galaktosidase-Konstrukts gespalten, sodass die Mena-Funktion ausfällt und die β-Galaktosidase-Expression unter der Kontrolle des endogenen Mena-Promoters steht. X-Gal-Färbungen von Mausorganen ließen Mena-Promoter-Aktivität in glatter Muskulatur von Gefäßen, Darm und Bronchiolen, aber auch in Zellen des Gehirns, in Kardiomyozyten und im respiratorischen Flimmerepithel der Bronchiolen erkennen. In Wildtyp-Mäusen, zeigten Western-Blot-Untersuchungen unterschiedliche Protein-Expressionsmuster für VASP und Mena. Mena-Expression wurde in fast allen Geweben entdeckt, hauptsächlich in Herz, Lunge, Magen, Dickdarm, Hoden, Gehirn und in den Augen. Zusätzlich wurde die neuronale Mena-Isoform im Gehirn, in den Augen und ein wenig auch in Herz und im Magen exprimiert. Im Gegensatz dazu, wurde VASP hauptsächlich in Thrombozyten und in Milzgewebe gefunden. In den auf dem Gene-trap basierenden Mäusen war die Expression von Mena im Herz, in der Lunge und im Magen deutlich reduziert, während nur eine leichte Verringerung im Gehirn und im Hodengewebe festzustellen war. Immunfluoreszenz-Mikroskopie legten Kolokalisation von Mena und F-Aktin an Glanzstreifen von Kardiomyozyten und deutliche Kolokalisation von Mena und glattmuskulärem Aktin in Gefäßen und Bronchien dar. Funktionsanalysen von Mena/VASPmutierten und Wildtyp-Mäusen anhand von EKG-Aufzeichnungen, ließen vermuten, dass ein Verlust von entweder Mena oder VASP die normale Herzfunktion nicht negativ beeinträchtigt. Wohingegen die Ruheherzrate von doppeldefizienten Mäusen deutlich erhöht war, was möglicherweise auf einen Mechanismus zur Kompensation der defizienten Ventrikelkontraktion zurückzuführen ist, um ein normales Herz-Zeit-Volumen aufrecht zu erhalten. Dies stimmt mit Herzkatheter-Untersuchungen überein, die auf eine Dilatative Kardiomyopathie bei doppeldefizienten Mäusen hindeuteten. Folglich ist davon auszugehen, dass Mena- und VASP-Proteine füreinander kompensieren können, obwohl Western-Blot-analysen unterschiedliche Expressionsmuster gezeigt haben. Mena betreffend, vermuten wir eine wichtige Rolle des Proteins in Gefäßwänden, in Kardiomyozyten und in Bronchien. KW - Spectrin KW - Genfallen-Insertion KW - Vasodilatator-stimuliertes Phosphoprotein KW - Mena KW - Mena-Promotor-Aktivität KW - X-Gal-Färbung KW - Mena KW - VASP KW - Mena promoter ativity KW - gene-trap KW - X-Gal staining KW - Spectrin Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-70414 ER - TY - THES A1 - Schneider, Matthias T1 - Characterisation of Metalloprotease-mediated EGFR Signal Transactivation after GPCR Stimulation T1 - Charakterisierung der EGFR Signaltransaktivierung nach GPCR Stimulation N2 - In the context of metalloprotease-mediated transactivation of the epidermal growth factor receptor, different monoclonal antibodies against ADAM17 / TACE were characterized for their ability to block the sheddase. Activity of some of them was observed at doses between 2µg/mL and 10µg/mL. Kinetic analyses showed their activity starting at around 30 minutes. In cellular assays performed with the antibodies, especially upon treatment of cells with sphingosine-1-phosphate a reduction in proliferation was observed with some candidates. Moreover this study provides potential new roles for ß-Arrestins. Their involvement in the triple membrane-passing signal pathway of EGFR transactivation was shown. Furthermore, in overexpressing cellular model systems, an interaction between ADAM17 and ß-Arrestin1 could be observed. Detailed analysis discovered that phosphorylation of ß-Arrestin1 is crucial for this interaction. Additionally, the novel mechanism of UV-induced EGFR transactivation was extended to squamous cell carcinoma. The mechanism happens in a dose dependent manner and requires a metalloprotease to shed the proligand Amphiregulin. The involvement of both ADAM9 and ADAM17, being the metalloproteases responsible for this cleavage, was shown for SCC9 cells. N2 - Im Rahmen dieser Arbeit wurden verschiedene monoklonale Antikörper gegen ADAM17 / TACE im Kontext der Metalloprotease-vermittelten Transaktivierung des Epidermalen Wachstumsfaktors auf ihre Fähigkeit hin untersucht, die Proteaseaktivität zu unterdrücken. Einige von Ihnen zeigten inhibitorische Aktivität bei Konzentrationen zwischen 2µg/ml und 10µg/ml. Die Untersuchung der Zeitabhängigkeit ihrer Wirkungsweise ergab eine Aktivität ab 30 Minuten Vorinkubation. In zellulären Versuchen konnte eine Verminderung der Proliferation besonders nach Stimulation mit Sphingosin-1-Phosphat gezeigt werden. Darüber hinaus konnten möglich neue Funktionen von ß-Arrestinen gezeigt werden. Eine Beteiligung am „triple membrane-passing“ Signalwegs der Transaktivierung des Epidermalen Wachstumsfaktors wurde dargestellt. Zudem wurde eine Interaktion von ß-Arrestin1 und ADAM17 in überexprimierenden Zellsystemen gezeigt. Detaillierte Analysen belegten, dass die Phosphorylierung von ß-Arrestin1 eine notwendige Voraussetzung dafür ist. Weiterhin wurde der neue Mechanismus der UV-vermittelten Aktivierung des epidermalen Wachstumsfaktors auf Plattenephithelkarzinom-Zellen ausgeweitet. Er findet in einer dosisabhängigen Form statt und bedarf einer Metalloprotease zum Aktivieren des Liganden Amphiregulin. Sowohl ADAM9 als auch ADAM17 wurden als die verantwortlichen Metalloproteasen in den untersuchten SCC9 Zellen ermittelt. KW - Epidermaler Wachstumsfaktor-Rezeptor KW - G-Protein gekoppelte Rezeptoren KW - Metalloprotease KW - Krebs KW - EGF Rezeptor KW - Transaktivierung KW - GPCR KW - UV KW - EGFR Transactivation KW - Metalloprotease KW - GPCR KW - Cancer KW - UV Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-65105 ER -