Regulation of lipid metabolism in macrophages by long-chain metabolites of α-tocopherol

With only two years away from the 100th anniversary of the discovery of vitamin E as an essential nutrient in 1922, we have still more questions than answers concerning its significance for human health. During the past hundred years, vitamin E research was characterized by great hopes but also bitter disappointments, which finally led to a strong decline of interest in this research area. However, vitamin E research is currently experiencing a scientific renaissance, which is among others attributed to the unrevealing of vitamin E metabolism in humans and to the elucidation of biological functions of the newly formed metabolites. Since their initial determination in human serum, especially the long-chain metabolites (LCMs), i.e. the first metabolites formed during the hepatic degradation of vitamin E, appeared as a class of molecules with putative relevance in the human body. Driven by a small community of ambitious scientist, research on these compounds has made great progress over the last decade, leading to the establishment of the LCMs as an acknowledged area of vitamin E research. As one of the founding members of the LCM community, the work of our group is predominantly focused on the advance of this new and promising field of vitamin E research. Hence, the ten manuscripts included in this thesis also contribute to the progress of key areas in the field of LCM research, i.e. elucidation of biological functions, identification of signaling pathways and the comparison of LCM functionality with their vitamin precursors. Despite of this great progress on fundamental areas of LCM functionality, their exact modes of action as well as their significance for human health are still a puzzle waiting to be solved. Especially the lack of data on LCM physiology in a living organism represent a great limitation of current and the major challenge of future investigations

Modellierung sequentieller Metalloenzyme auf Magnesiumbasis

Die vorliegende Dissertation beschäftigt sich mit der Modellierung quantenchemischer Modelle für die Beschreibung von sequentiellen Enzymen an den ausgewählten Beispielen Inositol Monophosphatase und Yeast Enolase. Zunächst wurde ein Templat-Modell für IMP entwickelt, an dem gezeigt wurde, dass diese metallozentrierten Modelle grunsätzlich nicht in der Lage sind Metalloenzyme zu beschreiben, wenn das Metallion am katalytischen Zyklus aktiv teilnimmt. Des Weiteren wurde ein ungewöhnliches Koordinationsverhalten von Magnesium aufgedeckt. Die normalerweise beobachtete oktaedrische Koordinationsgeometrie des Mg2+-Ions wird nicht nur in der Gasphase, sondern auch in biologischen Systemen zu Gunsten einer trigonal-bipyramidalen (pentakoordinierten) Anordnung aufgegeben. Durch die Modifikation einer QM/MM-Strategie gelang es ein quantenchemisches Modell für die Beschreibung sequentieller Enzyme zu entwickeln. Dieses Modell basiert auf einer Hohlraum-Strategie und bedient sich eines kugelförmigen Ausschnitts des Aktivzentrums, auf den ein Strukturgradient (sukzessive Fixierung von Diederwinkeln, Bindungswinkeln und -längen von innen nach außen) angewendet wird. Diese Hohlraum-Strategie wurde erfolgreich in gängige quantenchemische Programme (GAUSSIAN, TURBOMOLE und ORCA) implementiert und im Anschluss erfolgreich bei der Untersuchung der Hefe-Enolase angewendet

The Hepatic Fate of Vitamin E

Vitamin E is a lipophilic vitamin and thus is naturally occurring mainly in high-fat plant products such as oils, nuts, germs, seeds, and in lower amounts in vegetables and some fruits. The term “vitamin E” comprises different structures that are classified as tocopherols, tocotrienols, and “vitamin E-related structures.” Vitamin E follows the same route in the body like other lipophilic substances. In brief, vitamin E is absorbed in the intestine, packaged into chylomicrons together with other lipophilic molecules, and distributed via lymph and blood in the body. As the liver is the central organ in lipoprotein metabolism, it is also essential for the uptake, distribution, metabolism, and storage of vitamin E. Based on the current knowledge on that field, the physiological, nonphysiological, and pathophysiological factors influencing the hepatic handling of vitamin E, verifying the crucial role of the liver in vitamin E homeostasis, are described

Demografiegerechtes Verbraucherrecht? Die Verbraucherstellung im Spiegel sozialer, wirtschaftlicher und technologischer Transformationsprozesse

Während das Verbraucherprivatrecht an sich recht dicht reguliert ist, hat es demografische Entwicklungen und Kenngrößen bislang noch nicht gezielt aufgegriffen. Doch altersbedingte Einschränkungen oder Sprach- und Technikbarrieren können die praktische Wirksamkeit des Verbraucherrechts in "demografisch geprägten" Sachverhalten in Frage stellen. Der vorliegende Beitrag möchte den Stand des Verbraucherrechts daraufhin untersuchen, ob das Recht demografieblind ist oder ob Anknüpfungspunkte bestehen, welche die Aufnahme individueller Alters-, Migrations- und Kulturerfahrungen bei der Ausformung des Verbraucherrechts gestatten

The Influence of Climatic Seasonality on the Diversity of Different Tropical Pollinator Groups

Tropical South America is rich in different groups of pollinators, but the biotic and abiotic factors determining the geographical distribution of their species richness are poorly understood. We analyzed the species richness of three groups of pollinators (bees and wasps, butterflies, hummingbirds) in six tropical forests in the Bolivian lowlands along a gradient of climatic seasonality and precipitation ranging from 410 mm to 6250 mm. At each site, we sampled the three pollinator groups and their food plants twice for 16 days in both the dry and rainy seasons. The richness of the pollinator groups was related to climatic factors by linear regressions. Differences in species numbers between pollinator groups were analyzed by Wilcoxon tests for matched pairs and the proportion in species numbers between pollinator groups by correlation analyses. Species richness of hummingbirds was most closely correlated to the continuous availability of food, that of bees and wasps to the number of food plant species and flowers, and that of butterflies to air temperature. Only the species number of butterflies differed significantly between seasons. We were not able to find shifts in the proportion of species numbers of the different groups of pollinators along the study gradient. Thus, we conclude that the diversity of pollinator guilds is determined by group-specific factors and that the constant proportions in species numbers of the different pollinator groups constitute a general pattern

Digitised and Traceable Testing for Gas Turbine Components and Materials

The Institute of Test and Simulation for Gas Turbines develops digital twins and simulation models to calculate the aerodynamic loads and to assess the damage mechanisms in engine parts and materials resulting from simultaneous mechanical, thermal and chemical-corrosive loads. Multiscale methods are used to quantify the long-term behaviour of objects, from the microstructure of materials to engine parts and components, and the characteristics of engine subsystems. Additionally, scale-resolving simulations are developed and applied to obtain high-fidelity CFD solutions. In order to validate the digital models experimentally, unique test stands and rigs are developed which provide engine-relevant operating conditions, dimensions, and loads. There are multiple test rigs in development for experimental testing of materials under engine-relevant conditions. The test rigs may be grouped in two major categories: materials testing and rotative engine subsystem testing. Materials testing is performed at mechanical, thermal, and chemical loads representative of real engine conditions. Rotative subsystem testing includes innovative seals, gears and secondary air systems. The subsystem tests are also performed under engine relevant conditions and used to validate pertinent design models. These test rigs are presented and their research objectives are specified. The presentation outlines how operating conditions for tests are combined in a number of ways to allow research under real engine conditions. Additionally, this setup allows testing under a combination of mechanical, thermal and chemical loads simultaneously, thereby going beyond the current state of the art. To achieve the best possible integration of simulation and experiments, both areas will be fully digitised. A tool is developed to establish comprehensive data provenance for all steps of research projects. The presentation details how process steps report data to be included in a graph database where connections are created based on ontologies specifically designed for this purpose. Ontology allow exchanging data between software and processes without loss of semantics. The graph database will represent processes performed and ensure that quality managed processes are adhered to. Furthermore, such a digitised system does not just allow insight into single research steps but allows a unique overview over all performed tasks