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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Rational Structure-Based Rescaffolding Approach to De Novo Design of Interleukin 10 (IL-10) Receptor-1 Mimetics

Ruiz-Gómez, Gloria, Hawkins, John C., Philipp, Jenny, Künze, Georg, Wodtke, Robert, Löser, Reik, Fahmy, Karim, Pisabarro, M. Teresa 06 January 2017 (has links)
Tackling protein interfaces with small molecules capable of modulating protein-protein interactions remains a challenge in structure-based ligand design. Particularly arduous are cases in which the epitopes involved in molecular recognition have a non-structured and discontinuous nature. Here, the basic strategy of translating continuous binding epitopes into mimetic scaffolds cannot be applied, and other innovative approaches are therefore required. We present a structure-based rational approach involving the use of a regular expression syntax inspired in the well established PROSITE to define minimal descriptors of geometric and functional constraints signifying relevant functionalities for recognition in protein interfaces of non-continuous and unstructured nature. These descriptors feed a search engine that explores the currently available three-dimensional chemical space of the Protein Data Bank (PDB) in order to identify in a straightforward manner regular architectures containing the desired functionalities, which could be used as templates to guide the rational design of small natural-like scaffolds mimicking the targeted recognition site. The application of this rescaffolding strategy to the discovery of natural scaffolds incorporating a selection of functionalities of interleukin-10 receptor-1 (IL-10R1), which are relevant for its interaction with interleukin-10 (IL-10) has resulted in the de novo design of a new class of potent IL-10 peptidomimetic ligands.
52

Zone line formation on artificial media and in hardwoods by basidiomycetes for production of spalted wood

Gantz, Stephanie, Steudler, Susanne, Delenk, Hubertus, Wagenführ, André, Bley, Thomas 23 June 2020 (has links)
One of the visual modification of wood is the formation of dark zone lines (ZLs) via interaction of fungi. The result is called spalted wood, which has hitherto been produced mainly in small batches. The main goal of the present study is to further develop techniques for rapid formation of ZLs in hardwoods. Various white rot and brown rot fungi were tested to this purpose. Initially, interactions of 148 combinations of 17 basidiomycetes in malt extract agar were evaluated and their antagonistic interactions were characterised in order to identify fungal pairs capable of rapidly forming high-quality ZLs. Six types of interactions were observed, among others; antibiosis and inhibition in contact, which differ in terms of variables including mycelial overgrowth and zone line formation. Furthermore, 23 pairs of ZL forming fungi on malt extract agar were identified. Then the interactions of five selected pairs of fungi grown on the hardwood species Acer pseudoplatanus L., Betula pendula Roth. and Populus nigra L. were examined to assess their utility for controlled mycological wood modification, also in terms of a possible substrate dependency of their interactions. The results indicate that Lentinus tigrinus fungus is one of the best and quickest producer of ZLs in mycological wood modification.
53

Analyzing pathways from childhood maltreatment to internalizing symptoms and disorders in children and adolescents (AMIS): a study protocol

White, Lars O., Klein, Annette M., Kirschbaum, Clemens, Kurz-Adam, Maria, Uhr, Manfred, Müller-Myhsok, Bertram, Hoffmann, Katrin, Sierau, Susan, Michel, Andrea, Stalder, Tobias, Horlich, Jenny, Keil, Jan, Andreas, Anna, Resch, Leonhard, Binser, Martin J., Costa, Anna, Giourges, Elena, Neudecker, Eva, Wolf, Christiane, Scheuer, Sandra, Ising, Marcus, Klitzing, Kai von January 2015 (has links)
Background: Effective interventions for maltreated children are impeded by gaps in our knowledge of the etiopathogenic mechanisms leading from maltreatment to mental disorders. Although some studies have already identified individual risk factors, there is a lack of large-scale multilevel research on how psychosocial, neurobiological, and genetic factors act in concert to modulate risk of internalizing psychopathology in childhood following maltreatment. To help close this gap, we aim to delineate gender-specific pathways from maltreatment to psychological disorder/resilience. To this end, we examine the interplay of specific maltreatment characteristics and psychological, endocrine, metabolomic, and (epi-)genomic stress response patterns as well as cognitive-emotional/social processes as determinants of developmental outcome. Specifically, we will explore endocrine, metabolomic, and epigenetic mechanisms leading from maltreatment to a higher risk of depression and anxiety disorders.
54

In Silico Identification of Novel Cancer Drugs with 3D Interaction Profiling

Salentin, Sebastian 06 February 2017 (has links)
Cancer is a leading cause of death worldwide. Development of new cancer drugs is increasingly costly and time-consuming. By exploiting massive amounts of biological data, computational repositioning proposes new uses for old drugs to reduce these development hurdles. A promising approach is the systematic analysis of structural data for identification of shared binding pockets and modes of action. In this thesis, I developed the Protein-Ligand Interaction Profiler (PLIP), which characterizes and indexes protein-ligand interactions to enable comparative analyses and searching in all available structures. Following, I applied PLIP to identify new treatment options in cancer: the heat shock protein Hsp27 confers resistance to drugs in cancer cells and is therefore an attractive target with a postulated drug binding site. Starting from Hsp27, I used PLIP to define an interaction profile to screen all structures from the Protein Data Bank (PDB). The top prediction was experimentally validated in vitro. It inhibits Hsp27 and significantly reduces resistance of multiple myeloma cells against the chemotherapeutic agent bortezomib. Besides computational repositioning, PLIP is used in docking, binding mode analysis, quantification of interactions and many other applications as evidenced by over 12,000 users so far. PLIP is provided to the community online and as open source.
55

Functional Investigations into the Recognition Memory Network, its Association with Genetic Polymorphisms and Implications for Disorders of Emotional Memory

Dörfel, Denise 22 January 2010 (has links)
Recent research, that has been focused on recognition memory, has revealed that two processes contribute to recognition of previously encountered items: recollection and familiarity (Aggleton & Brown, 1999; Eichenbaum, 2006; Eichenbaum, Yonelinas, & Ranganath, 2007; Rugg & Yonelinas, 2003; Skinner & Fernandes, 2007; Squire, Stark, & Clark, 2004; Wixted, 2007a; Yonelinas, 2001a; Yonelinas, 2002). The findings of neural correlates of recollection and familiarity lead to the assumption that there are different brain regions activated in either process, but there are, to the best of my knowledge, no studies assessing how these brain regions are working together in a recollection or a familiarity network, respectively. Additionally, there are almost no studies to date, which directly searched for overlapping regions. Therefore, in study I of the current thesis, brain regions associated to both recognition processes are searched investigated. Additionally, a connectivity analysis will search for functional correlated brain activations that either build a recollection or a familiarity network. It is undoubtable that the Brain Derived Neurotrophic Factor (BDNF) is strongly involved in synaptic plasticity in the hippocampus (Bramham & Messaoudi, 2005) and there is evidence that a genetic variant of this neurotrophin (BDNF 66Met) is related to poorer memory performance (Egan, et al., 2003). Therefore, in study II of the current thesis, the effect of BDNF Val66Met on recollection and familiarity performance and related brain activations is investigated. Finally, one could summarize, that serotonin, like BDNF, is strongly involved in brain development and plasticity as well as in learning and memory processes (Vizi, 2008). More precisely, there is evidence for alterations in the structure of brain regions, which are known to be involved in emotional memory formation and retrieval, like amygdala and hippocampus (Frodl, et al., 2008; Munafo, Brown, & Hariri, 2008; Pezawas, et al., 2005). One study found an slight epistatic effect of BDNF and 5-HTTLPR on the grey matter volume of the amygdala (Pezawas, et al., 2008). Therefore, in study III, it is investigated if such an interaction effect could be substantiated for the amygdala and additionally revealed for the hippocampus. The results of the current thesis allow further comprehension of recollection, hence episodic memory, and point to a special role of the BDNF in temporal and prefrontal brain regions. Additionally, the finding of an epistatic effect between BDNF and serotonin transporter function point to the need of analyzing interactions between genes and also between genes and environmental factors which reveals more information than the study of main effects alone. In conclusion, analyzing behavioral and neural correlates of episodic memory reveal allowed insights in brain functions that may serve as guideline for future studies in clinical populations with memory deficits, including susceptibility factors such as good or bad environment, as well as promising gene variants that influence episodic memory.
56

Size Spectra as a tool to understand structures and processes of aquatic communities

Braun, Lisa-Marie 12 September 2023 (has links)
Aquatische Gemeinschaften sind stark körpergrößenstrukturiert mit einer exponentiellen Abnahme der Häufigkeit der Individuen mit zunehmender Körpergröße, die als Größenspektrum (SS) bezeichnet wird. Körpergrößenbasierte Ansätze bieten eine einfache und kostengünstige Methode zur Beantwortung komplexer ökologischer Fragestellungen in aquatischer Forschung. Widersprüchliche Ergebnisse zu den wichtigsten Faktoren, die Größenspektren beeinflussen unterstreichen jedoch die Notwendigkeit weiterer Studien. Um einige dieser widersprüchlichen Schlussfolgerungen anzugehen, habe ich eine Reihe von Fragen in den Bereichen Limnologie und Korallenriffökologie untersucht. In dieser Dissertation wurden größenbasierte Ansätze wie SS verwendet, um zu untersuchen, (i) was die Größenverteilung von Zooplankton beeinflusst und ob Zooplankton-fressende Fische (topdown) oder Ressourcenverfügbarkeit und Umweltbedingungen (bottom-up) die SS der Zooplanktongemeinschaft bestimmen, (ii) ob traditionelle Schleppnetze oder moderne hydroakustische Methoden Fisch-SS zuverlässiger darstellen, und (iii) ob SS von Korallenriff- Fischgemeinschaften und die strukturelle Komplexität der Korallen bzw. deren Beziehung zueinander sich unter verschiedenen anthropogenen Stressoren verändert. Zuallererst konnte ich zeigen, dass weder Top-down- noch Bottom-up-Kräfte stark die Größenverteilung der Zooplanktongemeinschaft beeinflussten. Zooplankton SS scheinen robust gegenüber Prädationseffekten zu sein, aber ein empfindlicher Indikator für die Energieverfügbarkeit und Transfereffizienz im Nahrungsnetz des untersuchten Sees. Des Weiteren konnten meine Studien bestätigen, dass hydroakustische Methoden die SS von pelagischen Fischgemeinschaften zuverlässig darstellen, was sie zu einer kostengünstigen und minimalinvasiven Alternative zu traditionellen Fischentnahmemethoden macht. Ich konnte jedoch kein allgemeingültiges Muster hinsichtlich der Größenverteilung von Korallenrifffischen und der strukturellen Komplexität der Korallen in Beziehung zu unterschiedlichen anthropogenen Stressoren finden. Insgesamt zeigt die Dissertation das weite Anwendungsspektrum von SS, um Strukturen und Prozesse in aquatischen Gemeinschaften und Fischfangmethoden zu untersuchen. Die hohe Variabilität von Größenspektren und der Einfluss von Umweltbedingungen unterstreicht weiter die Wichtigkeit, Daten über einen langen Zeitraum einzubeziehen. Darüber hinaus unterstreichen die Ergebnisse dieser Arbeit auch die Grenzen der Anwendung von SS, da für die Beantwortung mancher ökologischer Fragestellungen artenspezifische Informationen, wie Lebensraum- und Nahrungspräferenzen benötigt werden. / Aquatic communities are highly body-size structured with an exponential decline of abundance with increasing body size, which is referred to as the size spectrum (SS). The importance of body size as a principal and simplifying framework within aquatic communities, has led to a high number of theoretical and empirical studies on energy fluxes in food webs and predatorprey interactions using Size Spectra. These size-based approaches offer a rather simple and inexpensive method to answer complex ecological questions. However, conflicting findings on the key drivers of SS highlight the need for further studies. To address some of these conflicting conclusions, I investigated a range of questions within the fields of limnology and coral reef ecology. In this thesis size-based approaches such as SS were employed to explore (i) what drives zooplankton size distribution and whether zooplanktivorous fish (top-down) or resource availability and environmental condition (bottom-up) determine zooplankton community SS, (ii) whether traditional midwater trawling or modern hydroacoustic methods more reliably represent fish SS, and (iii) coral reef fish community SS and habitat structural complexity and their relationship across site-specific anthropogenic stressors. By analysing long term data, I first found that neither top-down or bottom-up forces drove the zooplankton community size distribution. Zooplankton SS seem robust against predation effects but a sensitive indicator for lake-wide energy availability and transfer efficiency in the food web. Then I found that hydroacoustic methods reliably represent pelagic fish community SS, making it a great alternative to traditional and more invasive fish removal sampling methods. Finally, I discovered that coral reef fish SS slope and structural complexity of the reef exhibited a significant negative relationship on two of the examined reef sites which are least exposed to anthropogenic disturbances. A consistent pattern of fish SS and reef complexity was missing, indicating that other environmental factors may also impact the assessed parameters. Overall, my studies show the range of applications of SS to effectively answer universal questions from trophic interactions and the importance of habitat characteristics in a community to a methodological comparison of fish sampling methods. The high variability of SS behaviour and the influence of environmental conditions further underlines the importance to include data on a large temporal scale. Community information, such as taxonomic identity and consideration of species-specific feeding and habitats preferences, for example, are still beneficial in some cases to answer ecologically questions extensively.
57

From curation to collaboration / a framework for interactions in cultural heritage information systems

Stiller, Juliane 22 April 2014 (has links)
Die Digitalisierung von kulturellen Gütern und der darausfolgende Online-Zugang zu ihnen hat dazu geführt, dass Gedächtnisinstitutionen wie Museen, Bibliotheken und Archive, neue Instrumente für Nutzer bereitstellen können mit denen das kulturelle Erbe erlebbar gemacht werden kann. Diese Dissertation beschreibt Interaktionen in kulturellen Informationssystemen und verbindet diese mit Zugangsmöglichkeiten zu digitalen Materialien. Basierend auf Fallstudien und dem Ansatz, Theorien aus empirischen Daten zu gewinnen (Grounded Theory), wurde ein theoretischer Rahmen entwickelt, mit dem man Interaktionen beschreiben und analysieren kann. Dieser Bewertungsrahmen für Interaktionen bietet einen ganzheitlichen Ansatz um Interaktionen und deren Zusammenspiel mit dem Informationszugang zu bestimmen. Dieser Zusammenhang hilft Gedächtnisinstitutionen zu verstehen, wie Entscheidungen im Design ihrer Informationsarchitektur den Umgang von Nutzern mit den präsentierten digitalen Artefakten beeinflussen. Der theoretische Rahmen wurde anschließend herangezogen um 72 kulturelle Informationssysteme in einer Inhaltsanalyse eingehender zu studieren. Die Systeme wurden nach ihren Charakteristika in verschiedenen Gruppen - Museen, Bibliotheken, Archive, Aggregatoren, Kollektionen und Gemeinschaften - eingeordnet, zwischen welchen Unterschiede und Gemeinsamkeiten aufgedeckt wurden, die es erlauben Zugang und Interaktionen in jedem einzelnen System besser zu verstehen. Weiterhin wurde der theoretische Rahmen für eine tiefergehende Bewertung eines Systems aus jeder Gruppe genutzt um Empfehlungen für ein effektives Systemdesign zu erarbeiten. Dabei wurde besonderes Augenmerk auf den Einfluss von Interaktionen auf die verschiedenen Zugangsformen gelegt, mit dem Ziel, zweckgerichtete Interaktionen in Systemen anzubieten. Die Dissertation leistet einen wichtigen Beitrag um nachhaltige Interaktionen in Informationssystemen des kulturellen Bereiches zu verstehen, zu bewerten und zu implementieren. / Through digitization of cultural heritage and online access to it, memory institutions such as museums, libraries and archives can provide new instruments for engaging users with cultural heritage. The thesis describes interactions in cultural heritage information systems and links them to access points of the digital material. Based on use cases and a grounded theory approach for data analysis, a framework for interactions was developed. This framework offers a holistic approach to understand interactions and their interplay with information access. The interrelatedness allows stakeholders in cultural heritage institutions to understand that each decision in the information design influences how users access and interact with digital material. The framework was then used in a content analysis of 72 cultural heritage systems that were clustered according to their characteristics. The outcomes reveal shortcomings and pinned down peculiarities between the groups Museums, Libraries, Archives, Aggregators, Collections and Communities. In a next step, the framework was applied as a tool for evaluation to help shape effective system design that guides the implementation of purposeful interactions. For that, one system per cultural heritage group was chosen as a use case for the evaluation. The results are recommendations for a more effective system design that acknowledges the impact of interactions on the access modes. This dissertation promotes a new perspective on interactions and derives strategies for effective system design.
58

Soziale Einbindung älterer Menschen in gemeinschaftlichen Wohnformen: Eine empirische Untersuchung zu ambulant betreuten Wohngemeinschaften und stationären Hausgemeinschaften

Dorschky, Lilo, Horváth, Irén, Schneider-Andrich, Petra 23 November 2023 (has links)
Angesichts der derzeitigen Altersstruktur und demographischen Entwicklung in Deutschland ergibt sich ein erheblicher Bedarf an Wohn- und Versorgungsangeboten für ältere Menschen mit Pflegebedarf. In diesem Zusammenhang gewinnen sog. neue Wohnformen, zu denen auch gemeinschaftliche Wohnformen wie ambulant betreute Wohngemeinschaften (WGen) und stationäre Hausgemeinschaften (HGen) zählen, an gesellschaftlicher und gesundheitspolitischer Relevanz. WGen und HGen basieren auf dem Prinzip „Leben in Gemeinschaft“, das in Publikationen des Kuratoriums Deutsche Altershilfe explizit genannt wird (https://kda.de), und auf das sich auch viele WGen/HGen konzeptionell beziehen. Mit ‚Leben in Gemeinschaft‘ ist häufig die Vorstellung verbunden, dass damit die Bewohner_innen nicht einsam sein müssen. Wissenschaftliche Studien, in denen systematisch erforscht wird, was gemeinschaftliches Leben und soziale Einbindung in WGen und HGen bedeuten (können), fehlen allerdings bisher fast vollständig. Mit dem Forschungsprojekt ‚Soziale Einbindung älterer Menschen in gemeinschaftlichen Wohnformen‘, welches vom Sächsischen Staatsministerium für Wissenschaft, Kultur und Tourismus (SMWK) im Jahr 2019 mit einer Laufzeit von zwei Jahren in Auftrag gegeben wurde, sollte ein Beitrag zu dieser wenig erforschten Thematik mit Blick auf den sächsischen Kontext geleistet werden. Die COVID-19-Pandemie, welche genau in den Projektzeitraum fiel, verhinderte jedoch diverse Zugänge zum Feld. Es konnten aber Expert_inneninterviews mit signifikanten Akteur_innen des Feldes sowie ethnografische Beobachtungen in zwei (anbieterverantworteten) ambulant betreuten WGen durchgeführt werden. Die Beobachtungen dienten dazu, das alltägliche soziale Miteinander der Bewohner_innen in gemeinschaftlichen Wohnformen zumindest explorativ zu rekonstruieren.
59

Charakterisierung eines neuen Proteins, Mapl-1 und seine Rolle in der Regulation der Pax-6 Funktion. / Characterization of a novel protein and its role in the regulation of Pax-6 function.

Petrou, Petros 01 November 2001 (has links)
No description available.
60

Analysis of global gene expression profiles and invasion related genes of colorectal liver metastasis

Bandapalli, Obul Reddy 19 December 2007 (has links)
Die Leber ist das am häufigsten von Metastasen betroffene Organ und kann daher als Modellorgan für metastatische Invasion dienen. Aus diesem Grund war es das Ziel dieser Dissertation Genexpressionsprofile zu verstehen und metastasierungs- sowie invasionsassoziierte Gene zu identifizieren. Differentielle Genexpression wurde in drei Systemen überprüft: Einem syngenen Mausmodell, einem Xenograftmodell sowie in fünf Gewebeproben von Patienten. Genexpressionprofile des syngenen Mausmodells und der Patientenproben zeigten, dass man die Invasionsfront als Ganzes betrachten, um möglichst viele über-lappende Gene zu finden. Globale Genexpressionstudien, die auf den Wirtsteil der Invasionsfront zeigten bemerkenswerte Überrepräsentation z. B. der „GO-terms“ „extrazelluläre Matrix“, Zellkommunikation“, „Antwort auf biotischen Stimulus“, Strukturmolekülaktivität“ und „Zellwachstum“. Marker der Aktivierung hepatischer Sternzellen überrepräsentiert in der invasionsfront, was die Durchführbarkeit einer Analyse differentieller Genexpression im genomweiten Rahmen anzeigt. Globale Genexpressionsstudien, auf den Tumorzellen in der in vitro Situation, in vivo und in der Invasionsfront zeigten insgesamt einen Anstieg zellulärer Spezialisierung von der in vitro zur Invasionsfront. Sezernierte proangiogenetische Chemokine zeigten eine Hochregulation in der Invasionsfront. Das beta catenin Gen war in der Invasionsfront 9.6 fach erhöht im Vergleich zur in vitro Situation. Die Überprüfung der transkriptionellen Aktivierung von beta catenin über die Prüfung der Promotoraktivität zeigte einen 18.4 fachen Anstieg in den Tumorzellen der Invasionsfront. Weiterhin war die Promotoraktivität (an Hand der Aktivität der mRNA des Alkalischen Phosphatase Reportergens) im Tumorinneren 3.5 fach höher als in der Zellkultur, was für einen transkriptionellen Mechanismus der beta catenin Regulation zusätzlich zu den posttranslationalen Mechanismen spricht. / Liver is most frequently populated by metastases and may therefore serve as a model organ for metastatic invasion. So the aim of this thesis is to understand the gene expression profiles and identify metastasis and invasion related genes. Differential gene expression was examined in three systems: A syngeneic mouse model, a xenograft model and five clinical specimens. Gene expression profiles of a syngenic mouse model and human clinical specimen revealed that the invasion front should be considered as a whole to find more overlapping potential target genes. Global gene expression studies on the host part of the invasion front, revealed a pronounced overrepresentation of GO-terms (e.g. “extracellular matrix”, “cell communication”, “response to biotic stimulus”, “structural molecule activity” and “cell growth”). Hepatic stellate cell activation markers were over-represented in the invasion front demonstrating the feasibility of a differential gene expression approach on a genome wide scale. Global gene expression studies of the tumor cells in vitro, in vivo and tumor part of the invasion front revealed an overall increase of cellular specialization from in vitro to the invasion front. Secreted angiogenic cytokines were found to be up regulated in the invasion front. Beta catenin gene of “cell adhesion” GO term was elevated 9.6 fold in invasion front compared to in vitro. Evaluation of transcriptional up-regulation of beta catenin by promoter activity showed an 18.4 fold increase in the tumor cells of the invasion front as compared to those from the faraway tumor. Promoter activity assessed by soluble human placental alkaline phosphatase reporter gene mRNA was 3.5 fold higher in the inner parts of the tumor than in vitro cells indicating a transcriptional mechanism of beta catenin regulation in addition to the posttranslational regulatory mechanisms.

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