Das Krankheitsbild der Sepsis, definiert als eine lebensbedrohliche Organdysfunktion, verursacht durch eine dysregulierte Immunantwort auf eine Infektion, stellt weltweit die häufigste Komplikation auf Intensivstationen dar. Der septische Schock, ein dem komplexen Krankheitssyndrom unterliegendes Ereignis, welches sich durch besonders schwere zirkulatorische, zelluläre und metabolische Abnormalitäten auszeichnet, ist zudem mit einer Mortalität von bis zu 40 % assoziiert. Eine sensitivere Diagnostik, das steigende Alter sowie häufig auftretende Komorbiditäten der Patienten führen zu einer steigenden Inzidenz der Erkrankung. Weiterhin zieht die Sepsis auch in erfolgreich therapierten Patienten schwerwiegende gesundheitliche Probleme nach sich. Unabhängig von der öffentlichen Meinung, welche die Sepsis zuweilen unterschätzt, rückt das Krankheitsbild durch einen Mangel an adäquaten Therapieoptionen in den Fokus der Wissenschaft. Trotz intensiver Forschung besteht ein beständiges Interesse an neuen Erkenntnissen, welche die vielfältige und komplizierte Pathogenese der Sepsis erklären könnten. In dieser Studie soll durch ein murines Infektionsmodell die Pathogenese der Sepsis, induziert durch eine Peritonitis, in Bezug auf die immunologisch relevante Sonderform des Proteasoms betrachtet werden. Das Proteasom, der wichtigste proteolytische Enzymkomplex des nicht lysosomalen Proteinabbaus eukaryotischer Zellen, ist unter Einfluss von Interferon γ und Lipopolysaccharid, einem Zellwandbestandteil Gram-negativer Bakterien, befähigt, proteolytisch aktivere Immunountereinheiten einzubauen. Welche immunmodulatorischen Funktionen das neu gebildete Immunoproteasom (IProteasom) besitzt, wurde in dieser Studie durch Escherichia coli-infizierte I-Proteasomdefiziente Mäuse für die Gram-negative Sepsis beschrieben. Die zentrale Rolle des IProteasoms wurde durch eine verstärkte Symptomatik und Organpathologie in I-Proteasom-Knock-Out-Mäusen, welche letztlich in einem forcierten Multi-Organ-Dysfunktions-Syndrom und einer erhöhten Letalität gipfelten, deutlich. Eine verminderte Eradikation der Erreger und die erhöhte bakterielle Last im gesamten Organismus konnte jedoch nicht mit einer eingeschränkten Funktionalität von Zellen des angeborenen Immunsystems am Infektionsort erklärt werden. Neben der uneingeschränkten Produktion systemisch wirkender pro- und antiinflammatorischer Mediatoren wurde in I -Proteasom-Knock-Out-Tieren jedoch eine verminderte lymphozytäre Abwehr detektiert, welche sich in einer ausgeprägteren Lymphopenie und einer eingeschränkten Expression von MHC-II-Molekülen auf B-Zellen der Knock-Out- Tiere manifestierte. Desweiteren ergaben Analysen der Genexpression von Lebergewebe septischer Tiere Unterschiede im Transkriptomprofil zwischen Wildtyp- und IProteasom-Knock-Out-Mäusen. Der Einfluss des I-Proteasoms auf die Regulation von Genkomplexen unter anderem die Angiogenese, Wundheilung und Apoptose betreffend, ermöglicht eine neue Sicht auf die Rolle des I-Proteasoms in Immunreaktionen und gibt Hinweise auf eine zell- und gewebsspezifische Funktionalität. Durch die Versuche dieser Studie wurde ein umfassendes Bild des protektiven Charakters des I-Proteasoms und im Besonderen der Immunountereinheit Multicatalytic Endopeptidase Complex-1 (MECL-1) in der Escherichia coli-induzierten Sepsis dargestellt. Somit stellt die selektive Hemmung des IProteasoms in der Behandlungsstrategie der Gram-negativen Sepsis höchstwahrscheinlich kein klinisch relevantes pharmakologisches Ziel dar.Weniger anzeigen
A major issue of conventional chemotherapy is the lack of selective delivery which results in high systemic exposure and severe side effects. The limitations of small molecular weight drugs for cancer therapy prompted the development of diverse nanocarrier systems for targeted drug delivery. The impressive progress in nanomaterial science and increased understanding of the nano-bio interface allowed the progression of these systems. However, the targeted delivery remains challenging due to obstacles that are encountered during the drug delivery process, particularly, in the tumor microenvironment (TME). (Multi)stimuliresponsive nanocarriers have the potential to overcome the faced barriers by taking advantage of altered pathological characteristics in the TME and/or intracellular signals. The motivation of the presented work was to incorporate rational design features into novel responsive nanomedicines to address the limitations of conventional chemotherapeutic drugs and tackle issues of current drug delivery systems (DDS). For this purpose, prodrugs of the chemotherapeutic agent doxorubicin (Dox) were combined with three nanocarrier designs including polymer-drug conjugates, a nanoemulsion (NE), and nanogels (NGs). The Dox prodrugs comprised cleavable motifs which introduce a responsiveness towards endogenous stimuli into the nanocarriers. The nanocarrier architectures with different sizes and compositions were evaluated in terms of controlled drug release, drug-carrier compatibility, carrier degradability, and transport restrictions in the TME, all of which are important aspects for an efficient delivery process. The choice of the cleavable linkage strongly affects the specificity of the desired responsive behavior. To address this aspect, Dox prodrugs with pH- or protease-cleavable bonds were evaluated regarding their impact on the intracellular drug release. Activatable fluorescence probes were utilized to follow the drug release from polymer-drug conjugates in real-time. This assessment of the linker formed the basis for the rational design of two prodrug-based nanomedicines with adjusted cleavage properties. First, a pH-sensitive Dox prodrug was entrapped in a NE to form a DDS with explicit intracellular drug release. The second design was based on dual-responsive nanogels as multistage delivery systems with specific extracellular response to protease and acid-mediated intracellular payload release. Initially, we evaluated the impact of the cleavable linkage on the drug release using theranostic polymer conjugates (TPC) with activatable fluorescence probes. The TPC represent model DDS that consist of dendritic polyglycerol (dPG) as polymeric carrier labeled with an indodicarbocyanine (IDCC) dye that quenches the fluorescence of Dox, conjugated through a cleavable linker. Cleavage of the conjugates was mediated either by acidic pH or protease activity. By tracking the fluorescence recovery in a cell-based microplate assay, we were able to obtain characteristic release profiles of Dox for different cell lines. Here, the pH-cleavable linker was found to be cleaved mainly intracellularly, whereas the protease-sensitive system suffered from extracellular drug release. The intracellular release was crucial to treat multidrug-resistant cells and overcome their resistance mechanisms. It can be highlighted that the modular synthetic approach, combined with the cell-based assay, has potential to extend the common in vitro methods to evaluate DDS performance. The results of this study motivated us to develop a pH-sensitive Dox prodrug (C16-Dox) to efficiently dissolve the drug in the nanodroplets of an oil/water NE. By attaching a hydrophobic alkyl chain (C16), Dox was provided with an amphiphilic character for increased drug-carrier compatibility. pH-sensitive properties of the prodrug allowed the intracellular release of the drug from the NE by recovering the hydrophilic parent drug. The new formulation of Dox (NE-C16-Dox) was compared with free Dox in a murine breast cancer model. Enhanced delivery to tumor tissue and reduction of systemic toxicity allowed the administration of a higher Dox dose in the NE formulation as compared to the free drug. The high dosage significantly inhibited the primary tumor growth and prevented the formation of distant lung metastasis without signs of side effects. The improved chemotherapeutic index compared to free Dox indicates that NE-C16-Dox is a promising formulation for breast cancer treatment At last, we combined protease- and pH-sensitive moieties into a multistage nanocarrier to enhance drug transport in tumor tissue. Matrix metalloproteinase (MMP)-sensitive NGs (pNGs) were developed which consists of a dPG scaffold crosslinked with a fluorogenic peptide. The crosslinker integrates biodegradability to the nanocarrier mediated by proteases in the TME. The intrinsic reporter moiety of the crosslinker allowed us to study the influence of different pNG compositions on the degradation profile in detail. One pNG candidate was chosen to conjugate the therapeutic drug Dox through a pH-sensitive linkage to dPG. The degradable multistage pNGs demonstrated deeper penetration into multicellular tumor spheroids (MCTS) as compared to their non-degradable counterparts. Hence, the triggered size reduction of the pNGs by enzymatic degradation facilitated the infiltration of the nanocarrier into dense tissue and thereby promoted the delivery of the therapeutic cargo.Weniger anzeigen
Anthelmintic resistance is an accompaniment to modern livestock industry, which heavily relies on chemotherapy and chemoprophylaxis for maintaining animal health and productivity. While anthelmintic resistance is already established in horses and is a growing issue in cattle, it is, by far, the most severe and most prevalent in the sheep industry. To combat the spread of resistance, researchers are investigating alternative ways of nematode control and formulate recommendations to move towards more sustainable patterns of chemotherapeutic control. A further pillar in the management of nematodes is the understanding of the mechanisms underlying anthelmintic resistance. This knowledge is necessary to implement resistance diagnosis tests and might offer potential new drug targets. Macrocyclic lactones (MLs) and benzimidazoles (BZs) are the most frequently used anthelmintics in the sheep industry and resistance against them has been reported worldwide. Target-site related mechanisms usually are investigated first. For BZs, mutations in the ß-tubulin isotype 1 gene leading to amino acid changes at the drug target site have been found to confer resistance in trichostrongyloid nematodes, which are among the most pathogenic parasites of small ruminants. These mutations have been exploited to set up several tests capable of diagnosing BZ resistance even at very low frequencies of resistance alleles in nematode populations. So far, no target-site related mechanisms have been identified in case of MLs and diagnosis of ML resistance is limited to in vivo and in vitro tests. Drug efflux by P-glycoproteins is a non-target-site related mechanism that has been proposed to play a role in ML resistance particularly. A third possibility that has come to receive more attention in recent years is bioinactivation of MLs and BZs by cytochrome P450 monooxygenases (CYPs). In cancer drug resistance research as well as in the field of insecticide and acaricide resistance CYPs and their contribution to drug resistance are well established concepts. Reasons to assume that CYPs might also be involved in anthelmintic resistance include, for instance, the metabolism of thiabendazole, a BZ representative, by CYP35D1 in the free-living nematode Caenorhabditis elegans and the detection of BZ metabolites, consistent with CYP activity in the parasitic nematode Haemonchus contortus. Despite these and many other indications, the role of CYPs in anthelmintic resistance is not fully clear. The present cumulative doctoral thesis elaborates on the likelihood of an involvement of CYPs in ML metabolism in C. elegans and BZ metabolism in H. contortus. The first part was primarily processed by an in vitro approach whereby the larval development of mutant strains was compared to that of the wild-type N2 strain under different ML exposures. In particular, a strain with a temperature-sensitive mutation in the cytochrome reductase gene emb-8 was compared at a non-permissive temperature to the wild-type regarding ivermectin (IVM) and moxidectin (MOX) susceptibility. The second part focused on expression patterns of CYPs in in vitro cultured fourth larvae of H. contortus. Here, constitutive and TBZ-inducible expression was investigated in five different H. contortus isolates with varying levels of phenotypic BZ resistance. Essentially, the ablation of CYP enzymatic activity by use of an inhibitor and a genetic approach was found to minimally alter the susceptibility to IVM in C. elegans, but not to MOX, both of which are MLs but belong to different groups. CYP14-A5, initially suspected to be involved in ML resistance in C. elegans, is most likely not involved, as its loss of activity was not shown to modulate IVM susceptibility and inducibility of gene expression by IVM or MOX was not observed. Therefore, CYPs can be expected to play no major role in ML resistance in C. elegans. As for BZ resistance in H. contortus, exposure to TBZ did not induce expression of selected CYPs in any of the isolates. However, the highly resistant WR isolate showed a 2.4- 3.7- fold higher constitutive expression of CYP HCOI100383400 in comparison to BZ susceptible isolates. In a previously published study, this CYP has been shown to have elevated transcript levels in the gut – the hypothesized major site of detoxification in nematodes. This is a first hint towards a possible involvement of CYPs in BZ resistance in a parasitic nematode. The WR isolate was also shown to be considerably more resistant than known resistant field isolates while having similar frequencies of the F200Y single nucleotide polymorphism (SNP) in the β-tubulin isotype 1 gene which along with E198A and F167Y is the primary cause for BZ resistance. The comparison of the frequency of F200Y and phenotypic resistance levels corroborates the long-held assumption of a multi-genic context for BZ resistance. Whether a co-governance of BZ resistance by several mechanisms in general and by the involvement of CYPs in particular is true, cannot be guaranteed with absolute certainty at the present state of research. However, the possibility of such should not be thoughtlessly abandoned, particularly in case of high resistance phenotypes as suggested by the present thesis. There is no question that further experimental investigations are necessary to improve our understanding of metabolism-based detoxification in nematodes.Weniger anzeigen
Increasing global energy demand drives the development of clean energy sources that will help reduce the consumption of fossil fuels. Solar energy can be converted to chemical energy via artificial photosynthesis but this requires photocatalytic material with low cost and high efficiency. Carbon nanomaterials that can be used either as photocatalysts or as photoabsorbers, have attracted attention as cheap and stable nonmetal nanomaterials with tunable electronic properties. In this dissertation, two typies of carbon nanomaterials, carbon dots and polymeric carbon nitride have been studied with a strong focus on the influences of surface chemistry and heteroatom dopants on their electronic and chemical properties. To this aim, a variety of spectroscopic techniques, with incident energies ranging from soft X-ray, ultraviolet to infrared, have been employed. The first experimental report on electronic structure of carbon dots studied by synchrotronbased X-ray absorption and emission spectroscopies is presented in this work. The chargetransfer between carbon dots and water has been further studied using in-situ X-ray spectroscopy. The modification on the surface chemistry induced by water and the hydrogen bonding environment of carbon dots dispersion have been also probed by in-situ infrared spectroscopy. The influence on their fluorescence and photocatalytic applications are then analyzed on the basis of experimental results. For polymeric carbon nitride photocatalyst, particular attention was given to the influence of heteroatoms doping on their electronic structure. Using advanced characterization techniques, the dopant species, and changes of band-gap structure are revealed. Finally, an example of the structure-performance relationship study was presented on highly efficient polymeric carbon nitride photocatalysts. This research highlights how advanced spectroscopy techniques may open new perspective for deeper understanding of carbon nanomaterials, especially carbon dots and polymeric carbon nitride. Furthermore, promising pathways to achieve more effective carbon nanomaterials for energy applications are also provided.Weniger anzeigen
Gegenwärtig ist Mazedonien – insbesondere aufgrund des sogenannten »Namensstreits« mit Griechenland – wieder verstärkt im deutschsprachigen Mediendiskurs präsent. Worum aber handelt es sich, wenn von Mazedonien die Rede ist? Die mediale Repräsentation der Region bleibt oft diffus und ist stark von Stereotypen geprägt. Benjamin Langer zeigt in seiner umfassenden Analyse erstmals auf, wie diese südosteuropäische Region in deutschsprachigen Texten aus einer terra incognita an der Peripherie Europas geformt und mit Zuschreibungen versehen wurde. In zehn thematischen Kapiteln weist er nach, wie wirkmächtig diese Bilder trotz ihrer Widersprüchlichkeit und wechselnden Instrumentalisierung bis heute sind.Weniger anzeigen
Organic and perovskite solar cells are promising candidates to produce a third generation of high performance, low cost photovoltaic devices. Higher power conversion efficiencies can be achieved, if the fundamental physics of charge transport processes under device operation is understood. In particular charge carrier interactions in their microscopic environment can influence transport and need to be investigated and identified. This thesis presents a study on paramagnetic states in organic and perovskite solar cells using Electron Paramagnetic Resonance (EPR) spectroscopy in combination with the Electrically Detected Magnetic Resonance (EDMR) technique. Firstly, a doping study on the organic small molecule spiro-OMeTAD, typically used as a hole transport material in perovskite solar cells, is presented. A detailed multi-frequency EPR analysis revealed that the origin of the EPR spectrum of doped spiro-OMeTAD is due to the hole introduced by doping. Doping efficiencies of the most commonly used p-dopants Li-TFSI and FK209 were determined as less than 2% and ~81%, respectively, indicating that FK209 is the main doping agent. A bias-dependent transient EPR and EDMR study on fully processed and encapsulated polymer/fullerene blend bulk heterojunction solar cells was conducted. The combined detection allowed the identification of light-induced spin-species and their involvement in photocurrent influencing processes. We found different spin-dependent processes that dominate at different time scales after optical excitation. Finally, paramagnetic states in perovskite materials and solar cells were investi- gated. Spin-dependent processes were detected in the organic transport layers of tin-based perovskite solar cells. Furthermore, from trEPR measurements signatures suggesting the existence of triplet excitons in a two-dimensional perovskite film were found.Weniger anzeigen
Low energy excitations (< 1eV) are of utmost importance for understanding the elec- tronic, magnetic, and thermodynamical properties of any material. The collective excita- tions of spin in this energy regime are magnons, which are quantized spin-waves. Recent developments in the field of spin-dynamics have opened up the world of femtomagnetism, whereby the spin degree-of-freedom is controlled using ultrafast laser pulses. Thus manipu- lating magnons using femtomagnetism holds great promise for future technological devices operating on ultrafast timescales. In order to reach this goal, it is vital that we are able to accurately describe these magnon excitations in order to understand, and ultimately control them. The objective of this thesis is to study magnetic excitations using an ab-initio approach, namely Time Dependent Density Functional Theory (TDDFT). These studies are divided into two sections. In the first part these excitations are studied in the linear regime where a new approximation is derived. In the second part these studies are extended into the real-time, non-equilibrium, regime where the response of magnons to ultrafast laser pulses is investigated. TDDFT encapsulates the electron-electron interactions of the many-body system in the exchange-correlation (XC) functional, which for practical applications must be approxi- mated. Despite the plethora of approximations for the XC energy functional only a few have been used for the XC kernel. Out of these, only the Adiabatic Local Density Approx- imation kernel has been implemented and applied to study the magnetic excitations. The work presented first focuses on deriving the Generalized Gradient Approximation (GGA) kernel by climbing up the Jacob’s ladder of functionals. Then the performance of the GGA kernel is studied by calculating the magnon spectra for ferromagnets and Heuslers. Results show that the GGA kernel generally worsens the spin-excitation spectra by overestimating the magnon energies. However, at the Brillouin Zone (BZ) boundary, suppression of the spin wave intensity is consistent with experimental findings. In the second part of this thesis the power of real-time TDDFT is demonstrated by simulating multiple magnon modes in multi-sublattice alloys, where these modes can be vi- sualized in real space and their response to external pulses can be investigated in real-time. The results in the case of two magnetic sublattice alloy suggests the existence of element specific decoupled magnon modes along with the coupled modes. These decoupled modes in- dicate that the constituent elements in the alloy respond at different timescales. Using these studies three distinct ways of ultrafast laser pulse control of magnon modes is demonstrated: (1) element selective destruction of magnon modes, (2) creation of a transient non-collinear state by destruction of specific magnon modes, (3) renormalization of the optical magnon frequency, where we found a linear dependence between the laser intensity and the decrease of the magnon frequency.Weniger anzeigen
Meteoritic breccias can contain material that is not yet available in current meteorite collections as individual rocks. These materials can significantly contribute to answering questions related to the formation, environment, and evolution history of planetary bodies. Volatile-rich clasts are a great example of material that occurs in brecciated meteorites and can be used to answer questions related to the above mentioned topics. Volatile-rich clasts in general are characterized by abundant volatile-bearing secondary formed minerals and can be subdivided into two main types: 1) The CM-like type, which contains chondrules with accretionary rims, tochilinite-cronstedtite intergrowths (TCI), carbonates, and Fe-Ni sulfides dispersed in a very fine phyllosilicate matrix. 2) The CI-like type clasts that contain a fine-grained phyllosilicate matrix with embedded magnetite, Fe-Ni sulfides, carbonates, accessory minerals, and very rarely chondrules or fragments of them. The mineralogy of the two types of clasts shows a strong association to the well-known CM and CI chondrites, respectively. However, it is unclear whether the volatile-rich clasts are actually similar to the analogue chondrites or whether they represent material that is not yet present in our meteorite collections. The goal of this thesis is to not only characterize the volatile-rich clasts and investigate the differences between the clasts and the chondrites, but also to obtain a better understanding of the associated parent body processes, such as; (i) the source and extent of the thermal histories (ii) the timing and source(s) of hydrothermal alteration (iii) the degree of equilibration and origin of sulphides within the parent bodies. To resolve these processes, we apply a variety of analytical methods. Raman carbon thermometry of organic matter dispersed in the matrix was used to resolve the thermal history in terms of heating source, peak temperatures, extent, and influence of heating on highly volatile element isotope compositions of the volatile-rich clasts and analogue meteorites. Additionally, the formation processes of sulfides were investigated using S isotope compositions of the abundant Fe-Ni sulfides in the CI- and CM-like clasts. Finally, the Mn-Cr ages of dolomite in CI-like clasts and calcite in CM-like clasts were ascertained to constrain the timing of hydrothermal alteration among the clasts and chondrites. The estimated peak temperature of the organic matter indicates that CI-like clasts experienced an average peak temperature of 65 ± 25 °C; very similar to the CM-like clasts with an average of 70 ± 25 °C. The CM and CI carbonaceous chondrites in this study experienced similar temperatures between 50 °C and 75 °C. The peak temperatures were most likely the result of 26Al decay that triggered hydrothermal alteration. No evidence was found, that indicates additional heating by impacts or interaction with the host rock leading to a higher peak temperature than during their formation. Considering the thermal histories and the mineralogy it seems that the clasts and chondrites represent similar material. The S isotope compositions of sulfides, however, show a completely different result. Although the S isotope compositions of Fe-Ni sulfides in CM chondrites and CM clasts are very similar, the S isotope compositions of sulfides in CI-like clasts and those in CI chondrites are considerably different. Moreover, CI-like clasts have negative δ34S values, whereas the CI chondrites have positive δ34S values. The difference between these two materials, although having a similar mineralogy and thermal history, is the first evidence that the parent bodies of the CI-like clasts sampled different (S) isotopic reservoirs. For this reason, CI-like clasts can better be referred to as C1 clasts. The observation of different parent bodies with similar mineral compositions and peak temperatures can be used to constrain a key process in the early solar system; hydrothermal alteration. To constrain whether hydrothermal alteration was a near-contemporaneous event among parent bodies in the outer solar system, or whether it consisted of multiple events, Mn/Cr ages of carbonates were determined. Additionally, Mn/Cr ages will also be used to determine if the isotopic differences between C1 clasts and CI chondrites are caused by a dissimilarity in hydrothermal processes and thus the formation of the secondary formed minerals. The formation age of carbonates in CM, CR, C2ung¬, and CI chondrites as well as those in C1 and CM clasts correspond adequately to heat produced during the 26Al decay. This indicates that the carbonates in the majority of the material precipitated 2-6 Ma after CAI (Calcium-aluminum-rich inclusion) formation from a hydrothermal fluid induced from ice that melted during the heat production of 26Al decay. Not all samples analyzed in this dissertation revealed an age due to the lack of 53Cr enrichments. This lack of 53Cr is most likely a result of small-scale localized differences of Mn/Cr concentrations in the fluid from which the carbonates precipitated. It is therefore plausible, that the small nature and the limited amount of available carbonates in the C1 clasts resulted in a sample bias where only carbonates that precipitated from low 53Cr/52Cr and 55Mn/52Cr fluid domains were analyzed. In summary, this dissertation shows that the mineralogy and thermal history of volatile-rich clasts and the CM and CI chondrites are similar and point toward a low-temperature (<100 °C) hydrothermal formation. Isotopic studies however, still show significant differences between C1 clasts and CI chondrites and suggest that C1 clasts originate from spatially separated parent bodies that sampled different isotopic reservoirs compared to CI chondrites. Additionally, Mn/Cr ages of carbonates in various chondrites and clasts suggest that hydrothermal alteration was a near-contemporaneous event among different parent bodies in the outer solar system induced by 26Al decay.Weniger anzeigen
Gegenstand der vorliegenden Arbeit sind die Möglichkeiten und Grenzen der Politik der Europäischen Kommission zur Beteiligung der Zivilgesellschaft. Es wird dargestellt, was in der Politikwissenschaft und seitens der Europäischen Kommission unter „europäischer Zivilgesellschaft“ und deren Partizipation im Kontext demokratischer Legitimation und einer transnationalen europäischen Öffentlichkeit verstanden wird. Dabei steht im Fokus, wie sich die politischen Strategien und Instrumente der Europäischen Kommission zur Einbindung der Zivilgesellschaft im Laufe der europäischen Integrationsgeschichte entwickelt und gewandelt haben. Die Relevanz der Arbeit basiert auf der Annahme, dass die Einbeziehung der Zivilgesellschaft eine mögliche Antwort auf ein konstatiertes Demokratiedefizit darstellen und zur Erhöhung der demokratischen Legitimation der EU beitragen könnte. Anhand eines Literaturstudiums erfolgt dazu eine Diskussion der politikwissenschaftlichen Standpunkte aus verschiedenen Demokratietheorien. Das Forschungsdesign beinhaltet eine Typologisierung der Beteiligungsinstrumente der Europäischen Kommission und die Entwicklung eines eigenen Analyserasters mit den Eignungsdimensionen Zugänglichkeit, Mehrwert und Inklusion zur Prüfung der Eignung politischer Beteiligungsinstrumente. Anhand dieses Analyserasters werden die europäischen Beteiligungsinstrumente in einer Fallstudie im sozioökonomischen Härtefallgebiet des Bezirks Neukölln von Berlin auf ihre Eignung zur Beteiligung der Zivilgesellschaft überprüft. Ergebnis der Untersuchung ist, dass die eingesetzten Partizipationsinstrumente der Europäischen Kommission nur bedingt geeignet sind, einen größeren und nicht nur elitären Teil der Zivilgesellschaft zu erreichen und damit das Demokratiedefizit der Europäischen Union zu vermindern. Beteiligung ist in hohem Maße abhängig vom Willen und den individuellen Fähigkeiten und Möglichkeiten von Bürgern und Organisationen der Zivilgesellschaft. Aus den Untersuchungsergebnissen werden Lösungs- und Gestaltungsansätze abgeleitet, um diese Komponenten in Zukunft stärker zu fördern und alternative, verständliche und konkrete Formen der Beteiligung der Zivilgesellschaft für eine bürgernahe und demokratisch legitimierte europäische Politik zu entwickeln.Weniger anzeigen
Na busca por dar visibilidade à contribuição dos povos africanos para a identidade linguística brasileira, esta pesquisa se propõe a descrever de forma detalhada os princípios entoacionais presentes nas declarativas informacionais e contrastivas produzidas por pessoas de comunidades remanescentes de quilombos no Rio Grande do Norte (RN). Assim, este estudo se configurou metodologicamente como uma pesquisa de campo na área da fonética acústica para coleta de dados de fala de três comunidades quilombolas do RN. Para fins de realização de análises estatísticas e classificação dos dados segundo notação ToBI para a língua portuguesa, delimitou-se previamente contextos pragmáticos específicos de informatividade e contrastividade. A descrição de forma detalhada dos princípios entoacionais presentes nas declarativas informacionais e contrastivas produzidas por pessoas de comunidades remanescentes de quilombos no Rio Grande do Norte permite afirmar que os correlatos acústicos de intensidade e duração sonoras, observados no grupo prosódico foco das declarativas, correlacionados à estruturação silábica, interferem distintivamente nos padrões entoacionais dos quilombolas. Assim, a configuração entoacional observada somente por meio da análise de aspectos tonais de frequência se revela incompleta para uma compreensão global da entoação. Desse modo, os efeitos da interação entre os correlatos acústicos de frequência, intensidade e duração na produção sonora evidenciam que o contorno tonal se associa a outros autossegmentos que orientam a configuração entoacional.Weniger anzeigen
The dry-zone water-harvesting and management system in Sri Lanka is one of the oldest historically recorded systems in the world. A substantial number of ancient sources mention the management and governance structure of this system suggesting it was initiated in the 4th century BCE (Before Common Era) and abandoned in the middle of the 13th century CE (Common Era). In the 19th century CE, it was reused under the British colonial government. This doctoral thesis predominantly aims at identifying the temporal development and socio-economic meaning of the water harvesting and management system through a systematic analysis of the written and epigraphic sources. Consequently, a critical analysis was conducted to examine the present day management system and the preservation of indigenous characteristics for a sustainable utilization of the resource in future. Finally, the preservation and continuation of the indigenous landscape system for the future was assessed in a heritage management perspective. This research study was conducted using an interdisciplinary research approach combining different research methods. In general, two major approaches were taken to analyse the socio-economic conditions and implications of past cultures: a) Analysis of epigraphical sources, primary and secondary literature, historical maps and archaeological findings were combined to identify and reconstruct the socio-economic conditions of the ancient Rajarata kingdom during Anuradhapura and Polonnaruwa periods. b) Standardized qualitative interviews and workshops with the main stakeholders involved with the management of the Dry Zone hydraulic landscape were conducted, for the documentation of the present governance structure, land use practices, and existing indigenous knowledge. In first case study, 255 text passages containing 837 different records on ancient irrigation were compiled as a database for the period from the 5th century BCE to the 10th century CE to reconstruct the diachronic developmet of the system. The second case study aims to identify the ancient water management and governance structure in the Dry Zone of Sri Lanka through a systematic analysis of ancient sources. Furthermore, colonial politics and interventions during reclamation have been critically analyzed. Basis for this was the already existing database from which 222 text passages containing 560 different records contained relevant information. 201 of these text passages were captured from lithic inscriptions and 21 text passages originate from the chronicles. The spatial distribution of records in general largely corresponds to the extent of the Dry Zone and northern intermediate zone. The analyzed data are not equally distributed throughout the investigated period and show a distinct peak in the 2nd century CE. In conclusion, the conducted analysis documents the potential of the analyzed source genres for the derivation of information on different aspects related to the spatial, temporal and administrative development of the ancient water management system in Sri Lanka. The third case study aimed to analyze the current management practices and existing indigenous aspects of the Dry Zone irrigated agricultural system from the viewpoint of farmers who are the main stakeholders of the system. Altogether 49 semi-structured interviews were conducted in seven villages in the Anuradhapura district and a detailed survey was conducted in the village of Manewa with a mixed research approach. The basic elements of the indigenous landscape, agricultural practices and management structures based on Farmer Organizations were mapped and examined in detail. The analysis of results shows that the sustainability of the indigenous agricultural system is vulnerable to rapid changes due to modernization, market changes, education levels, and inconsistent management decisions. This doctoral thesis contributes to the knowledge base of water resource management by addressing policy dimensions, with a special reference to traditional and indigenous knowledge base. Socio-economic implications on the development of the water harvesting systems were systematically compiled and serve to interprete the evolution of the water harvesting systems in a broder contextWeniger anzeigen
Vorangegangene Pilotstudien konnten die Anwendbarkeit und Wertigkeit des LiMAx ® für eine postoperative Funktionsüberwachung nach Leberresektion und Lebertransplantation zeigen. In der hier präsentierten Arbeit sollte nun das klinische Potential des LiMAx ® funktionelle Lebergewebsveränderung zu detektieren und hieraus Implikationen für die Patientenbehandlung vor der Durchführung operativer Konzepte evaluiert werden. Zudem erscheint die Erweiterung des Einsatzes des LiMAx ® auf Fragestellungen der Hepatologie und Transplantationsmedizin sinnvoll.Weniger anzeigen
Classical immunological research investigates immune defense mechanisms in a controlled environment with a narrow genetic diversity and high reproducibility. Aiming the understanding of host immune variations and disease susceptibility in the broad framework of evolution, ecology and life-history, the field of eco-immunology is expanding the focus under the influence of high genetic diversity and abiotic and biotic factors in wild animals. Moreover, immunological research in non-model species is facing methodological challenges by lack of reagents and annotated genomes. Limited by experimental approaches that can easily be used under field conditions eco-immunological research focus mainly on innate and only partially on adaptive immunity. Despite the recent availability of high-throughput technologies, little is known about the development and processes of acquired immunity and how interactions with innate immune cells affect systemic immune responses. In my thesis I focused these issues using chiropteran species which represent an ideal model for eco-immunology due to their high diversity, physiological peculiarities and their prominent role as natural reservoir for pathological viruses.Weniger anzeigen
In this thesis, a polymeric interphase was developed in order to improve the mechanical properties of glass/polyepoxide model system. The polymeric interphase was composed of sol-gel active hybrid inorganic/organic diblock and gradient copolymers between the glass and polyepoxide interface was introduced in order to enhance the interfacial adhesion between both phases. The design principle of the polymeric interphase was inspired by the tendon-to-bone insertion site, which links to mechanically different tissues. The mechanism of the enhancement of the interfacial adhesion relies on to chemical and physical attachment of the polymeric precursor to both phases. For this purpose, a series of hybrid inorganic/organic copolymers with block and gradient microstructures were synthesized by employing CDTSPA mediated RAFT polymerizations in 1,4-dioxane. The hybrid inorganic/organic copolymers were composed of masked HEMA (THP–HEMA) as epoxy compatible and TESPMA as glass surface compatible component. The synthesis of P(THP–HEMA)-PTESPMA diblock copolymers was accomplished by using a THP–HEMA based MacroCTA approach. This two-step MacroCTA approach yielded well-defined diblock copolymers with narrow MWD and three different TESPMA block lengths. To synthesize well-defined gradient copolymers composed of THP¬–HEMA/TESPMA, the copolymerization kinetics of the given comonomer system was investigated in detail in order to gain detailed information over copolymerization kinetics in batch. In addition, the reactivity ratios were estimated by using a LSNF as well as KTM and EKTM, giving reactivity ratios for both monomers close to one. According to these investigations, the batch copolymerization of THP-HEMA/TESPMA yields exclusively ideal random copolymers. To overcome this limitation, the synthesis of gradient copolymers was accomplished by using a semi-batch forced gradient approach, in which a mixture of THP–HEMA was continuously feeded with 1M TESPMA solution. Due to the inherent reactivity of the comonomers, the steepness of the gradient microstructure could be altered by changing the TESPMA feeding to higher feeding rates. The semi-batch forced gradient approach enabled the preparation of well-defined gradient copolymers with reasonable narrow MWDs. In addition, the semi-batch forced gradient approach give rise to a greater variety of gradient compositions profiles as well as is not limited to a specific comonomer pair with appropriated reactivity ratio as compared to a spontaneous gradient approach. Due to the sol-gel active Si-OCH2CH3 motifs, the spontaneous formation of silica networks was observed in bulk. Thus, the polymeric precursors were stored in anhydrous THF in order to inhibit the spontaneous gelation of the Si-OCH2CH3 motifs. Next, the synthesized block copolymers with three different TESPMA block lengths and two gradient copolymers with diverse gradient microstructures were employed as polymeric precursor to fabricate sol-gel derived hybrid films on glass substrates. The formation of hybrid films on the glass substrates was accomplished by using a base and acid mediated sol-gel grafting-onto spin-coating approach. The former base catalyzed process yielded hybrid films with film thicknesses from 100 to 300 nm. Notably, the hybrid film thicknesses decreased upon treatment with methanolic 0.1M PTSA solution in order to cleave the THP groups from the hybrid film surface. These observations are attributed to shrinkage of the hybrid films upon post-crosslinking of non-reacted Si-OH motifs as well as evaporation of residual solvent. In general, the film thickness could be altered by using precursor with a higher incorporated TESPMA fraction or longer TESPMA block length. To further prove the structural identity of the hybrid films, IRRAS and XPS spectra were recorded. These studies revealed that pedant THP groups were successfully cleaved upon treatment with methanolic PTSA solution. Lastly, a custom-built glass slide-model system was developed, wherein two coated glass slides were stitched with a bisphenol A glycidyl ether-based epoxy resin together. To prove the micromechanical properties of such a model system, mode I tensile tests were conducted and compared with a reference test sample. Based on the experimental data of this tests, the interfacial adhesion strength was relatively increased between 11.9% and 51.1%. The relative increase of the adhesion strength was mainly governed by the hybrid films thicknesses and grafting densities. Thus, hybrid films with a film thickness of ≤ 100 nm and a rather low grafting density result in a stronger interfacial adhesion as compared to thicker hybrid films with a high grafting density. These observations are presumably attributed to an insufficient interpenetration of the PHEMA chains into epoxy resin due to a high chain density. Interestingly, the composition of the polymeric precursor as well as film composition had no crucial impact on the strengthening mechanisms on the nanometer-scale. Following these findings, the hypothesis that a gradient-like macromolecular interphase on a nanometer-scale is highly desirable in order to maximize the interfacial adhesion is not valid. However, these observations might alter by approaching thick hybrid films of ≥ 1000 nm, in which the structural differences of the individual hybrid films are more pronounced. Thus, further experiments should focus on the thicker films with a higher level of film inhomogeneity and spatial resolution. Most likely, such micrometer thick films reveal different film characteristics as compared to the nanometer thick films and the strengthening mechanism is more dominated by structural factors as well as by the inherent mechanical properties of the polymeric interphase. In conclusion, the introduction of macromolecular interphase in a composite-like glass-polyepoxide system has an immanent impact on the mechanical properties. According to the mode I tensile tests, a nanometer thick polymeric interphase composed of block and gradient inorganic/organic copolymers results in an increased interfacial adhesion, due to physical and chemical attachment of tethered polymer chains to both phases. The adhesion between both phases is directly related to the interpenetration of the PHEMA chains into the epoxy resin and thus, a high interfacial adhesion is accomplished by a high level of interpenetrated PHEMA chains. To achieve this, it is advantageous to fabricate thin hybrid films of ≤100 nm and rather low grafting densities of 0.11 chains nm–2. These requirements are sufficiently accomplished by using diblock inorganic/organic copolymers as precursors.Weniger anzeigen
This dissertation consists of four self-contained chapters, each making an independent contribution to the economic literature on child care, social norms, and women's labor supply.
Social norms have been put forward as prominent explanations for the changing labor supply of women. Chapter 1 studies the intergenerational formation of these norms, examining how they affect subsequent female labor supply decisions, taking into account not only early socialization of women but also of their partner. Using large representative panel data sets from Germany, results suggest that women with partners who grew up with a working mother are more likely to participate in the labor force, work longer hours, and earn higher labor income. This intergenerational link cannot be explained by other confounding patterns. The chapter finds no evidence that this finding reflects assortative mating; rather, analysis suggests that the partner's preferences play a decisive role for the labor supply decision of partnered women. Overall the results of this chapter suggest that policy measures supporting the labor force participation of today's mothers will increase the female labor force participation of the next generation.
Chapter 3 exploits a unique natural experiment to study the local evolution of social norms and behaviour. It makes use of the fact that after the sudden collapse of the Wall separating East and West Germany, many people who were socialized under the former GDR regime moved to the western part of Germany. These immigrants hold very different beliefs about how maternal employment affects children and the family due to the politico-economic system in the GDR, which focused on policies that favoured female qualified employment and put in place an extensive child care system. We examine social learning and spillover effects on West German families that, up to this point, were mainly characterized by the traditional breadwinner-housewife model. For identification, this chapter exploits the quasi-random geographical pattern of the first-wave of East-to-West migration after the fall of the wall that was mainly determined by distance to the boarder. Using data from the German Microcensus and various other data sets from the statistical offices, the chapter finds positive and statistically significant effects on the labor supply decision of women at the intensive margin. In addition, there is suggestive evidence that West Germans adjust their beliefs about how women's employment affects children and the family. The chapter carefully examines the dynamic evolution of these local effects in the short-, medium- and long-term, finding these best accommodated by models of local social learning and endogenous child care infrastructure. The chapter supports this interpretation by providing direct evidence on the evolution of East-West German intermarriage, local friendship-ties, and the local expansion of publicly funded child care.
As more and more countries consider expanding public child care provision, it is important to have a comprehensive understanding of its implications for families. Chapter 4 adds to the existing literature by investigating the effect of publicly funded child care on parental subjective well-being. To establish causality, the chapter exploits cut-off rules introduced following the implementation of a legal claim to formal child care in Germany. The results suggest that child care provision strongly increases the life satisfaction of mothers who were previously constrained by the lack of formal child care supply. The effect is more pronounced for mothers with higher labor market attachment. The coefficients for fathers are smaller and not statistically significant. As potential mechanisms, a wide range of time-use and labor market outcomes are explored. This shows that mothers indeed shift time from non-market activities to formal work in response to child care eligibility, resulting in direct and indirect pecuniary and non-pecuniary returns to maternal life satisfaction. The findings of this chapter shed light on key issues of work-family reconciliation and stress the importance of considering subjective well-being measures in family policy evaluations.
Research suggests that children of less-educated or foreign-born parents are more likely to gain developmentally from day care, but are less likely to be enrolled in it. Chapter 5 shows that substantial enrolment gaps exist for children below the age of three in Germany, a country with a universal and highly-subsidised day care system. Using a large and unique data set that records both actual and preferred day care usage, this chapter examines different demand and supply side explanation for these enrollment gaps. In the empirical analysis of supply side factors, we exploit policy induced regional and time variation in the scarcity of places and the amount of parental fees using different quasi-experimental methods. The chapter demonstrates that differences in demand cannot fully explain enrolment gaps by family background. The findings indicate that both reducing fees and local day care shortages have the potential to reduce enrollment gaps by parental education substantially, while these factors play a minor role for enrollment gaps by parental country of birth.Weniger anzeigen
Am 01.10.1897 gründeten der Innenarchitekt Martin Keller und Carl R. Reiner in Berlin den gleichnamigen Kunstsalon Keller & Reiner. Der Kunstsalon war das erste Unternehmen in Berlin, das sich ab Gründung neben der freien Kunst auf die Ausstellung und den Verkauf moderner angewandter Kunst im Jugendstil spezialisierte. Das innovative Angebot des Salons belegt einen grundlegenden Wandel innerhalb des Berliner Kunstmarktes: Modernem Kunstgewerbe wurde erstmals der gleiche Stellenwert eingeräumt wie den freien Künsten und es etablierte sich für diese Erzeugnisse ein eigenständiges, neues Handelssegment. In den Folgejahren nach der Gründung von Keller & Reiner in 1897 entwickelte sich in Berlin innerhalb kürzester Zeit ein stark florierender Kunsthandel für moderne angewandte Kunst. Insbesondere während des ersten Jahrzehnts des 20. Jahrhunderts ist für Berlin ein prosperierender, vitaler und hochqualitativer Handel mit zeitgenössischem Kunstgewerbe festzustellen. Ein hochspezialisierter Fachhandel war entstanden. Aus ganz Deutschland eröffneten Unternehmen, die mit diesen Erzeugnissen handelten, Niederlassungen in der Reichshauptstadt. Bis zum Beginn des Ersten Weltkrieges in 1914 expandierte der Berliner Kunsthandel für moderne angewandte Kunst derart, dass die Stadt schließlich für ganz Deutschland eine dominierende Position für das Kunstgewerbe, insbesondere auch mit Produkten von deutschen Künstlern, einnahm. Der überwiegende Teil der Künstler, die auf dem Berliner Markt vertreten waren, stammten aus den Zentren der modernen kunstgewerblichen Reformbestrebungen München und Darmstadt. Die anhaltende Zuwanderung kreativer Kräfte führte dazu, dass Berlin in der Blütezeit über das vermutlich deutschlandweit größte Angebot an zeitgenössischem Kunstgewerbe verfügte und sich dank der exklusiven Geschäfte, die mit innovativen Methoden hochwertige kunstgewerbliche Erzeugnisse auf den Markt brachten, als wichtiges deutsches Präsentations- und Absatzzentrum für moderne angewandte Kunst profilierte.Weniger anzeigen
Alternative polyadenylation (APA), which is regulated by both cis-elements and trans-factors, is widespread across all eukaryotic species and is recognized as a major mechanism of gene regulation. It could change the 3'UTR of an mRNA transcript affecting its stability, translation efficiency, nuclear export and mRNA or translated protein localization, or, if an exonic/intronic polyadenylation site (PAS) upstream of the stop codon is used, it could affect a gene's coding region to produce different protein isoforms with distinct properties. Accumulating evidence suggests that global APA-mediated 3'UTR length change might play an important role in oncogenic transformation, pluripotency, lymphocyte activation, neuronal stimulation and in embryonic development and differentiation. However, recent studies found limited effects of 3'UTRs in most genes compared to other regulatory elements located in 5'UTRs or coding sequence. APA as a molecular trait is a low-level phenotype in the hierarchy of biological organization, and might only exert very limited effects on organismal fitness. Therefore, some researchers proposed the “error hypothesis”, stating that most observed APA is noise and that APA diversity within and between tissues is generally neutral or deleterious, and not functional. Similarly, it has been suggested that APA divergence between species is largely non-adaptive. This scenario would be consistent with the (nearly) neutral theory of molecular evolution, which predicts that genes under relaxed selective constraints accumulate neutral (or slightly deleterious) changes at a faster rate than those under stronger purifying selection. In order to clarify the general and tissue-dependent function and regulation of APA and its evolution in mammals, we applied 3'mRNA sequencing for multiple tissues of an F1 hybrid between the C57BL/6J (Mus musculus) and SPRET/EiJ (Mus spretus) mouse strains. We analyzed the factors regulating APA diversity and addressed the question whether APA is generally non-adaptive as proposed by the error hypothesis. In this study, we quantified all annotated PASs in nine tissues of the F1 hybrid mouse and comprehensively characterized different features of single-PAS genes and multi-PAS genes. Next, we checked the positional effects on PAS strength and discussed the functional difference between rank 1 and rank 2 PASs among distinct gene groups. By quantifying PAS usage in each allele, we studied the genes with divergent major PAS expression level and dN/dS ratio difference, and unveiled different evolutionary patterns between APA patterns and gene expression (mRNA levels). We found that in general APA of multi-PAS genes is consistent with the error hypothesis, and that most APA diversity within and between tissues appears to reflect noise, resulting from molecular error due to weak cis-regulation. However, we did not find different selective constraint in dN/dS between genes with high and with low APA diversity, but found strong correlation between mRNA abundance and APA accuracy. The minor and major relative PAS usage is also affected by PAS position. In addition to most major PAS, many minor PASs appear to have functional importance. They are highly conserved and can compete with the major PASs. Last, we found a small fraction of genes exhibits strongly tissue-regulated APA patterns. In these genes, PAS usage is under intensive trans-regulation between the C57BL/6J and SPRET/EiJ alleles in the F1 hybrid mouse. Whereas many divergent PASs exist between the two alleles in genes with low expression level and under relax selective constraints, comparing these with genes showing allelic mRNA transcript level differences, we unveiled different evolutionary patterns between APA and gene expression.Weniger anzeigen
This thesis studies the mathematical modeling, simulation, and optimization of an industrial process called steel ladle stirring. In this process, gas is injected continuously from the bottom of the bath and rises by buoyancy through the liquid steel, thereby causing a turbulent stirring, i.e., a mixing of the bath. The process has been extensively studied in the literature both experimentally and numerically in order to understand the influence of control parameters on the stirring and to improve the mixing conditions in the industrial practice. Nevertheless, optimal control problems in mathematical sense have still to be explored in this area. The main contributions of this thesis can be divided into three parts. First, multiphase modeling of ladle stirring can become computationally expensive, especially when used within optimal flow control problems. This is why this thesis focuses on simplified models based on the single-phase incompressible Navier–Stokes equations. Three variants are formulated: a 2d Cartesian model, where the effect of the gas is modeled as a vertical boundary velocity, a 2d axial-symmetrical one with a central nozzle where it is modeled as a buoyancy force, and a 3d model of a laboratory-scale real ladle with two excentric nozzles, where the gas also appears as a volume force. The main differences with existing models from the literature are highlighted, and numerical simulations are compared with experimental measurements. Second, optimal control problems are investigated. The main difficulties come, on the one hand, from the formulation of the actual industrial problem, and, on the other hand, on the mathematical formulation of the control and cost functionals. In practice, the main control parameter is the volumetric flow rate of the injected gas. In addition, process constraints have to be taken into account. Due to the complexity of the industrial problem, several overlapping objectives are involved, such as maximize homogenization, minimize treatment time, minimize concentrations of inclusions, etc. A mathematical translation of the practical control and constraints is given, leading to so-called box constraints, and several cost functionals are proposed to describe the stirring efficiency. Numerical simulations are performed and conclusions are drawn for the industrial practice. Finally, as part of the cooperation project with the industrial partner, the main technological solutions for ladle stirring control are reviewed, leading to the choice of vibrations sensors. Thus, an experimental investigation of the vibrations of ladle stirring is conducted. This allows to formulate some practical recommendations for the industrial practice and improves our understanding of vibration phenomena for future modeling work.Weniger anzeigen
Alzheimer’s disease (AD) is an age-related neurodegenerative disorder that affects millions of patients worldwide. The gene encoding various isoforms of the brain lipid carrier apolipoprotein (APO) E is the most important genetic risk factor for the sporadic form of AD suggesting an important contribution of brain lipid metabolism to neurodegenerative processes. However, the mechanism whereby brain lipid homeostasis may affect brain health and disease, and the isoform-specific role of APOE in this process remains highly controversial. In my thesis, I focused on the functional characterization of sortilin, a neuronal clearance receptor for APOE. Specifically, I hypothesized that sortilin may interact with apoE3 to safeguard a protective brain lipid metabolism, and that such neuroprotective lipid profile may be lost in the presence of apoE4, the AD risk bearing variant of the lipid carrier. To test my hypothesis, I performed comparative analyses of lipid profiles in the brain of mouse models with targeted replacement of murine Apoe with either human apoE3 or apoE4. In addition, these mice were either wildtype or genetically deficient for sortilin. In my studies, I identified perturbation in brain levels of docosahexaenoic acids (DHA), the most common polyunsaturated fatty acid (PUFA), as well as in endocannabinoids (eCBs), fatty acids-based neurotransmitters as a consequence of the APOE and sortilin genotypes. I identified the underlying molecular mechanism by showing that sortilin binds and stabilizes the fatty acid binding protein 7 (FABP7), an intracellular carrier for PUFA and eCBs. FABP7 facilitates the neuronal metabolism and activity of these lipids through their action on the PPAR family of nuclear hormone receptors. This functional interaction of sortilin and FABP7 in lipid metabolism requires the presence of apoE3. Loss of sortilin in apoE3 mice impairs sorting and stability of FABP7 and compromises its action in neuronal PUFA and eCB homeostasis, resulting in a pro-inflammatory state. Similar detrimental effects are seen in the presence of apoE4 that disrupts the ability of sortilin to direct intracellular sorting and proper activity of FABP7. Taken together, my investigations have identified a unique pathway involving sortilin as well as carriers for extracellular and intracellular transport of lipids, namely apoE3 and FABP7 that control the anti-inflammatory metabolism of PUFA and eCBs, and how this pathway may support the functional integrity of the brain through the action of PPARs. My findings emphasize the relevance of lipids for the functional integrity of the human brain, and why aberrant alterations in this biological system may contribute to the risk of AD in carriers of the apoE4 genotype.Weniger anzeigen
In rare genetic diseases, a single genetic alteration can be enough to cause a severe disorder. Recent advances in genetic research have introduced exome or genome sequencing into clinical care. However, each sequencing run delivers a myriad of candidate variants that have to be sifted through in the hunt for the causative mutation - a major data challenge, for which researchers and clinicians have to rely on computer tools. With MutationDistiller, we have developed a freely available online tool to analyse whole exome sequencing data in a user-driven fashion. The tool aims at clinicians and researchers without bioinformatic experience who are working with real patient data, and allows them to distil the most likely causative variants from the sea of candidates. By uploading the patient’s genetic information and adding information on the symptoms, they can combine genotype and phenotype to find the culprit. MutationDistiller allows a wide range of phenotype data, such as HPO, OMIM and Orphanet entries, gene panels, expression data, Gene Ontology terms, and affected pathways. In the output, the program provides an ordered list of candidate alterations matching the user-defined criteria. In addition, crucial data on the alteration and the affected gene can be reviewed at a glance. This thesis describes the program, its background and usage, and compares it to current state-of-the-art tools. When assessing the tool, we found that it matches or out-competes similar software and is able to find the causative variant in a majority of cases. Moreover, its user-friendliness makes it a handy tool for clinicians and researchers, as is reflected by its usage: MutationDistiller routinely sees over 1,000 cases per month and has been used in over 14,000 cases at the time of writing. Thus, MutationDistiller has already found its way into the clinic. The tool, comprehensive documentation and example cases are freely available at https://www.mutationdistiller.org/Weniger anzeigen