Since cardiovascular disease is one of the leading causes of mortality all over the world, it is becoming increasingly important and relevant to develop new analytical techniques for the analysis of the mechanisms of this complex disease as well as for clinical applications. The overall objective of this research was to develop an array of methods for the analysis of triglyceride rich lipoproteins (TRL) in human serum and to apply these methods to clinical samples. TRL particles are mainly derived from dietary fats, which are positively correlated with cardiovascular disease. The mechanism behind which triglycerides cause cardiovascular disease is not well understood. The analysis of TRL by novel methods including density gradient ultracentrifugation and density profiling, gel electrophoresis, in vitro enzymatic assays, and capillary zone electrophoresis are presented here. The development of a novel density profiling method for the remnant lipoproteins class of TRL and its application to clinical samples was successful. In addition, TRL were successfully evaluated for their composition by gel electrophoresis, in vitro enzymatic assays and capillary zone electrophoresis. The results of these analyses demonstrate great potential for the use of these new methods as analytical tools for researchers in understanding the mechanism behind the onset of cardiovascular disease by TRL and their triglycerides as well as diagnostic tools for clinicians.

Wuppertal, Universiẗat, Diss., 1999.

Bochum, Universiẗat, Diss., 1999.

Note:

No description available.

No description available.

Plants are exposed to high temperature, especially during hot summer days. Temperatures are typically lowest in the morning and reach a maximum in the afternoon. Plants can tolerate and survive short-term heat stress even on hot summer days. A. thaliana seedlings have been reported to tolerate higher temperatures for different time periods, a phenomenon that has been termed basal thermotolerance. In addition, plants have the inherent capacity to acclimate to otherwise lethal temperatures. Arabidopsis thaliana seedlings acclimate at moderately elevated temperatures between 32–38° C. During heat acclimation, a genetically programmed heat shock response (HSR) is triggered that is characterized by a rapid activation of heat shock transcription factors (HSFs), which trigger a massive accumulation of heat shock proteins that are chiefly involved in protein folding and protection. Although the HSF-triggered heat-shock response is well characterized, little is known about the metabolic adjustments during heat stress. The aim of this work was to get more insight into heat-responsive metabolism and its importance for thermotolerance. In order to identify the response of metabolites to elevated temperatures, global metabolite profiles of heat-acclimated and control seedlings were compared. Untargeted metabolite analyses revealed that levels of polyunsaturated triacylglycerols (TG) rapidly increase during heat acclimation. TG accumulation was found to be temperature-dependent in a temperature range from 32–50° C (optimum at 42° C). Heat-induced TG accumulation was localized in extra-chloroplastic compartments by chloroplast isolation as well as by fluorescence microscopy of A. thaliana cell cultures. Analysis of mutants deficient in all four HSFA1 master regulator genes or the HSFA2 gene revealed that TG accumulation occurred independently to HSF. Moreover, the TG response was not limited to heat stress since drought and salt stress (but not short-term osmotic, cold and high light stress) also triggered an accumulation of TGs. In order to reveal the origin of TG synthesis, lipid analysis was carried out. Heat-induced accumulation of TGs does not derive from massive de novo fatty acid (FA) synthesis. On the other hand, lipidomic analyses of A. thaliana seedlings indicated that polyunsaturated FA from thylakoid galactolipids are incorporated into cytosolic TGs during heat stress. This was verified by lipidomic analyses of A. thaliana fad7/8 transgenic seedlings, which displayed altered FA compositions of plastidic lipids. In addition, wild type A. thaliana seedlings displayed a rapid conversion of plastidic monogalactosyldiacylglycerols (MGDGs) into oligogalactolipids, acylated MGDGs and diacylglycerols (DGs). For TG synthesis, DG requires a FA from the acyl CoA pool or phosphatidylcholine (PC). Seedlings deficient in phospholipid:diacylglycerol acyltransferase1 (PDAT1) were unable to accumulate TGs following heat stress; thus PC appears to be the major FA donor for TGs during heat treatment. These results suggest that TG and oligogalactolipid accumulation during heat stress is driven by post-translationally regulated plastid lipid metabolism. TG accumulation following heat stress was found to increase basal thermotolerance. Pdat1 mutant seedlings were more sensitive to severe heat stress without prior acclimatization, as revealed by a more dramatic decline of the maximum efficiency of PSII and lower survival rate compared to wild type seedlings. In contrast, tgd1 mutants over-accumulating TGs and oligogalactolipids displayed a higher basal thermotolerance compared to wild type seedlings. These results therefore suggest that accumulation of TGs increases thermotolerance in addition to the genetically encoded heat shock response. / Pflanzen sind besonders während der Sommerzeit hohen Temperaturschwankungen ausgesetzt. Temperaturen sind am Morgen meist niedrig und erreichen ihr Maximum während des Nachmittags. Pflanzen können Hitzestress im Sommer jedoch für eine kurze Zeit tolerieren. Arabidopsis thaliana Keimlinge können höhere Temperaturen für verschiedene Zeitspannen tolerieren, was als Basale Thermotoleranz beschrieben wird. Zusätzlich können Pflanzen durch Akklimatisierung eine Toleranz zu andernfalls letalen Temperaturen erwerben. A. thaliana Keimlinge beginnen sich bereits bei moderat erhöhten Temperaturen zwischen 32–38° C zu akklimatisieren. Während der Hitzeakklimatisierung wird eine genetisch programmierte Hitzeschockantwort (HSR) ausgelöst, welche durch eine rasche Aktivierung von Hitzeschock-Transkriptionsfaktoren (HSF) eingeleitet wird. Dies führt wiederum zu einem enormen Anstieg von einer Reihe von Hitzeschockproteinen (HSP), welche an der Faltung und dem Schutz der Proteine beteiligt sind. Obwohl die HSF-induzierte Hitzeschockantwort bereits gut charakterisiert ist, ist über die metabolomische Anpassung während des Hitzestress nur wenig bekannt. Das Ziel dieser Arbeit war es mehr Kenntnisse von hitze-respondierenden Metaboliten zu erhalten sowie deren Bedeutung für die Thermotoleranz. Zur Identifizierung von thermosensitiven Metaboliten, wurden die Metabolitprofile von Hitze akklimatisierten und Kontrollkeimlingen miteinander verglichen. Mittels ungerichteter Metabolit Analyse wurde ein rascher Anstieg von vielfach ungesättigten Triacylglycerolen (TG) während der Hitzeakklimatisierung nachgewiesen. Der TG Anstieg ist temperaturabhängig in einem Bereich von 32–50° C (Optimum bei 42° C). Der hitzeinduzierte TG Anstieg konnte mittels Chloroplastenisolierung sowie der separaten Analyse von Wurzel und Spross in den extrachloroplastidären Kompartimenten lokalisiert werden. Dies konnte durch Fluoreszenz Mikroskopie in Zellkulturen von A. thaliana bestätigt werden. Die Analyse von Mutanten, die einen Defekt in allen vier HSFA1 Masterregulatoren oder in dem HSFA2 Gen besitzen, zeigte, dass der Anstieg der TGs keine Abhängigkeit von den HSFs aufweist. Zudem ist der TG Anstieg nicht nur auf die Hitzestressantwort begrenzt, sondern auch durch Trockenheit und Salzstress induzierbar, jedoch nicht durch kurzzeitigen osmotischen-, Kälte- und Hochlichtstress. Zur Aufklärung des Ursprungs der TG Synthese wurde eine Lipidanalyse durchgeführt. Die hitzeinduzierte TG Akkumulation durch eine massive De Novo Fettsäuresynthese konnte ausgeschlossen werden. Die Untersuchung des Lipidoms von A. thaliana Keimlingen nach Hitze bot jedoch Hinweise auf einen Einbau von vielfach ungesättigten Fettsäuren aus thylakoiden Galaktolipiden in zytosolische TGs. Dies konnte durch die Untersuchung des Lipidoms von fad7/8 transgenen A. thaliana Keimlingen mit veränderter Fettsäure Komposition der plastidären Lipide bestätigt werden. Der Wildtyp von A. thaliana wies zudem eine rasche Umwandlung von plastidärem Monogalactosyldiacylglycerolen (MGDGs) zu Oligogalaktolipiden, acylierten MGDGs und Diacylglycerolen (DGs) auf. Für die TG Biosynthese wird eine Fettsäure aus dem Acyl-CoA Pool oder von Phosphatidylcholin (PC) auf ein DG übertragen. Keimlinge, die einen Defekt in der Phosolipid:Diacylglycerol Acyltransferase (PDAT1) aufweisen, waren nicht in der Lage TGs nach Hitzestress zu akkumulieren, auf PC als der wesentliche Fettsäure-Donor für TGs nach Hitzestress hinweist. Die Ergebnisse deuten auf einen TG und Oligogalaktolipid Anstieg durch einen posttranskriptionell regulierten Lipidumbau während des Hitzestress hin. Es konnte gezeigt werden, dass der TG Anstieg nach Hitzestress zu einer erhöhten Thermotoleranz führt. Keimlinge der pdat1 Mutanten waren ohne Akklimatisierung empfindlicher gegenüber massiven Hitzestress, da sowohl ein dramatischer Abfall der maximalen Effizienz des Photosystems II und eine niedrigere Überlebensrate im Vergleich zu Keimlingen des Wildtyps nachgewiesen wurden. Im Gegensatz dazu zeigten tgd1 Mutanten, welche eine Überakkumulation von TGs und Oligogalaktolipiden aufweisen, eine höhere Thermotoleranz auf als Keimlinge des Wildtyps. Diese Ergebnisse weisen darauf hin, dass die TG Akkumulation die Thermotoleranz zusätzlich zu der genetisch kodierten Hitzeschockantwort erhöht.

These studies determined the role of carbohydrate deficit from acute exercise on postprandial triglyceride elevation (PPTG). In Study 1, when energy expenditure was held constant in the exercise trials, both acute moderate (~50% VO₂ peak; MIE) and high intensity endurance exercise (90% VO₂ peak intervals; HIE) were effective to lower PPTG compared to a non-exercise control [CON; 54.9 (13.5) % and 75.2 (15.5) %, respectively, relative to CON, p<0.05], with HIE significantly lower than MIE (p=0.03). Total postprandial fat oxidation was increased in both MIE [83.3 (10.6) %] and HIE [89.1 (9.8) %] compared to CON [69.0 (16.1) %, p<0.05), with HIE significantly greater then MIE (p=0.012). These effects occurred in the absence of any change in glucose tolerance. In Study 2, when an isoenergetic meal was provided immediately after an acute exercise session (80 min; 60 min at ~65% VO₂peak and 10, 2 min intervals) consisting of either low carbohydrate (EX+LCHO) or high carbohydrate content (EX+HCHO), PPTG was siginificantly higher in EX+HCHO compared to EX+LCHO [449 (118) mg/dL/4h and 325 (63) mg/dL/4h, respectively, p=0.03], despite similar energy balance. Furthermore, postprandial fat oxidation was higher in EX+LCHO compared to EX+HCHO [256.7 (57.6) kcal/4h and 209.4 (56) kcal/4h, respectively, p=0.002]. PPTG was significantly related to fat oxidation (r=-0.61), fasting plasma [beta]-hydroxybutyrate (r=-0.62) and carbohydrate deficit (r=0.51), but not energy deficit (r=0.25). In summary, these data suggest that post-exercise carbohydrate balance from both increasing carbohydrate oxidation during exercise (i.e., exercise intensity) or by reducing post-exercise carbohydrate intake, is an important determinant of PPTG-lowering effects of exercise and that this may result from changes in fat oxidation. / text

Thesis (doctoral)--Kiel, 1983.

This study tested the ability of a novel adipose tissue derived cytokine, C1q TNF Related Protein 3 (CTRP3), to prevent alcohol-induced hepatic lipid accumulation, or alcoholic fatty liver disease (ALD). Previous work has demonstrated that CTRP3 is effective at preventing high fat diet-induced fatty liver, however, the potential of CTRP3 to inhibit ALD has not been explored. To test the potential protective effects of CTRP3, transgenic mice overexpressing CTRP3 (Tg) or wildtype littermates (WT) were subjected to one of two different models of ALD. In the first model, known as the NIAAA model, mice were fed control or alcohol-containing liquid diets (5% v/v) for 10 days followed by a single gavage of ethanol (5 g/kg). In the second model, the chronic model, mice were fed control or alcohol-containing diets for 6 weeks with no gavage. This study found that CTRP3 reduced triglyceride accumulation in the chronic model of alcohol consumption by ~50%, whereas no reduction was observed in the NIAAA model. Further analysis of isolated primary hepatocytes from WT and Tg mice demonstrated that CTRP3 increased oxygen consumption in the presence of fatty acids, indicating that CTRP3 increases hepatic fatty acid utilization. In conclusion, this study indicates that CTRP3 attenuates hepatic triglyceride accumulation in response to long-term chronic but not short-term alcohol consumption.