125 research outputs found
Biomarkers of arachidonic acid metabolism as predictors for presence of cardiovascular disease
Eicosanoids are important lipid mediators primarily generated from arachidonic acid (AA) which is liberated out of membrane phospholipids by phospholipase A2 (PLA2). AA is metabolized by cyclooxygenase (COX) and lipoxygenase (LOX) pathways to a number of different metabolites such as thromboxanes, prostaglandins, hydroxyeicosatetraenoic acids (HETE) or leukotrienes. Several lines of evidence implicate an important role of eicosanoids in central processes of inflammation and due to their widespread synthesis in blood and vascular cells these metabolites may play a central role in atherogenesis. On account of this, the analysis of the AA metabolism in whole blood might provide a new marker of atherosclerotic burden and is predestinated as biomarker for diagnosis and prediction of coronary artery disease (CAD).
In previous work, we developed an in vitro assay where whole blood from patients was stimulated with 1 ”g/mL lipopolysaccharide (LPS) for 24 hours. Samples were centrifuged and AA metabolites such as AA, 5-HETE, 11-HETE, 12-HETE, prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) were analyzed out of supernatant by liquid chromatography tandem mass spectrometry. Furthermore, messenger ribonucleic acid for quantitative gene expression analysis of COX-2 and prostaglandin E synthase (PGES) was isolated out of cellular components.
In the current thesis, we improved the in vitro whole blood activation model and established additional quantitative real time polymerase chain reaction assays for PLA2,
COX-1, thromboxane synthase (TXAS), prostaglandin F synthase (PGFS), 5-LOX, 5-LOX activating protein (FLAP) and 12-LOX gene expression analysis to cover major routes of AA metabolism and investigate the discriminatory potential of these eicosanoid pathways for inflammatory diseases.
Furthermore, different stimuli (LPS, tumor necrosis factor alpha and oxidized low-density-lipoprotein) for whole blood activation have been evaluated. Our data revealed most significant effects for LPS which were time- but not dose-dependent.
Since we observed a rapid eicosanoid response upon stimulation we asked whether eicosanoid response on gene expression and metabolite level is preformed or underlies de novo synthesis. To this end, transcriptional and translational inhibition experiments were performed to characterize these regulatory mechanisms. Data suggested that the production of metabolites underlies de novo synthesis upon stimulation, which is controlled both, at the level of transcription and translation.
We then applied the new in vitro whole blood assay to test the variability of the LPS-induced AA metabolism in healthy subjects. We showed major inter-individual differences for all investigated target genes as well as metabolites, suggesting that varying eicosanoid response might be predisposing towards different susceptibility to inflammatory diseases.
The predictive potential of the individual eicosanoid response for the presence of atherosclerosis was examined in 92 patients with or without CAD using the newly developed whole-blood assay. We found that the eicosanoid response on gene expression (COX-1,
COX-2, PGES and FLAP) and metabolite level (AA, 5-, 11- and 12-HETE) was significantly (P<0.05) different in patients with or without CAD. These data allowed developing a score consisting of three biomarkers of AA metabolism with an area under the curve (AUC) of 83.6, which is superior to currently available scores of blood markers of CAD.
Taken together, this work established an in vitro activation assay for the metabolites of AA metabolism, characterized its regulating mechanism and showed its potential for diagnostic testing of patients to the presence of CAD.Eicosanoide sind bedeutende Lipidmediatoren, welche aus ArachidonsĂ€ure (AA) nach deren Freisetzung aus Membranphospholipiden durch die Phospholipase A2 (PLA2) gebildet werden können. AA wird anschlieĂend ĂŒber den Cyclooxygenase (COX-) und Lipoxygenase (LOX-) Stoffwechselweg metabolisiert, wobei eine Reihe von verschiedenen Metaboliten wie Thromboxane, Prostaglandine, HydroxyeicosatetraensĂ€uren (HETE) sowie Leukotriene entstehen. Eicosanoide haben Einfluss auf die zentralen Prozesse von EntzĂŒndungsreaktionen und aufgrund ihrer weit verbreiteten Bildung in Zellen des Blutes sowie des GefĂ€Ăsystems spielen diese Metabolite ebenfalls eine Rolle in der Entstehung der Atherosklerose. Die Untersuchung des AA Metabolismus in Vollblut könnte einen neuen Parameter fĂŒr atherosklerotische VerĂ€nderungen darstellen und ist somit prĂ€destiniert als Biomarker fĂŒr die Diagnostik und PrĂ€diktion einer Koronaren Herzerkrankung (KHK).
In Vorarbeiten unserer Gruppe entwickelten wir einen in vitro Assay, bei dem Vollblut von Patienten mit 1 ”g/ml Lipopolysaccharid (LPS) fĂŒr 24 Stunden stimuliert wurde. Die Proben wurden anschlieĂend zentrifugiert und die Metabolite des AA Metabolismus (AA, 5-HETE,
11-HETE, 12-HETE, Prostaglandin F2α (PGF2α), Prostaglandin E2 (PGE2) und Thromboxan B2 (TxB2)) in den ĂberstĂ€nden mittels FlĂŒssigchromatografie und Tandem-Massenspektrometrie analysiert sowie quantifiziert. Des Weiteren wurde mRNA (messenger RNA) fĂŒr quantitative Genexpressionsanalysen der COX-2 sowie Prostaglandin E-Synthase (PGES) aus den zellulĂ€ren Bestandteilen des Ansatzes isoliert.
Im Rahmen der vorliegenden Promotionsarbeit entwickelten wir das in vitro Vollblutmodel weiter und etablierten zusĂ€tzliche Assays fĂŒr PLA2, COX-1, Prostaglandin F-Synthase (PGFS), Thromboxansynthase (TXAS), 5-LOX, 5-LOX aktivierendes Protein (FLAP) und 12-LOX Genexpressionsanalysen, um so alle Hauptwege des AA Metabolismus abzudecken und das diskriminierende Potential dieser Stoffwechselwege fĂŒr entzĂŒndliche Erkrankungen zu untersuchen.
Des Weiteren wurden verschiedene Stimulanzien (LPS, Tumornekrosefaktor Alpha und oxidiertes Low-Density-Lipoprotein) fĂŒr die Vollblutaktivierung ausgetestet. Unsere Ergebnisse zeigten, dass die stĂ€rksten Effekte LPS-vermittelt waren und eine ausgeprĂ€gte Zeit- jedoch keine DosisabhĂ€ngigkeit aufwiesen.
Da wir eine sehr schnelle Eicosanoidantwort auf den inflammatorischen Stimulus beobachten konnten, fragten wir uns, ob die Eicosanoidantwort auf Genexpressions- und Metabolitenebene bereits vorhanden ist oder einer de novo Synthese unterliegt. Um die regulatorischen Mechanismen besser zu charakterisieren, fĂŒhrten wir Experimente zur Transkriptions- und Translationshemmung durch. Die Daten suggerierten, dass die Produktion der Metabolite einer de novo Synthese nach Stimulation unterliegen, welche sowohl auf der Ebene der Transkription als auch Translation kontrolliert wird.
Wir verwendeten nun das neue in vitro Vollblutmodel an, um zu testen, wie hoch die VariabilitĂ€t des LPS-abhĂ€ngigen AA Metabolismus in gesunden Individuen ist. Wir konnten groĂe interindividuelle Unterschiede fĂŒr alle von uns untersuchten Zielgene sowie
-metaboliten aufzeigen und nahmen an, dass diese variierende Eicosanoidantwort prĂ€disponierend fĂŒr die SuszeptibilitĂ€t fĂŒr entzĂŒndliche Erkrankungen sein könnte.
Das prĂ€diktive Potential der individuellen Eicosanoidantwort fĂŒr das Vorhandensein von Atherosklerose wurde in 92 Probanden mit und ohne KHK mittels des neu entwickelten Vollblutassays geprĂŒft. Wir fanden signifikante Unterschiede (P<0.05) in der Eicosanoidanwort sowohl auf Genexpressions- (COX-1, COX-2, PGES und FLAP) als auch auf Metabolitenebene (AA, 5-, 11- and 12-HETE) zwischen Patienten mit und ohne KHK. Diese Daten erlaubten die Entwicklung eine Scores, welcher aus 3 Biomarkern des AA Metabolismus besteht, eine AUC von 83.6 aufweist und bereits publizierten Scores mit Blutbiomarkern fĂŒr die PrĂ€diktion einer KHK ĂŒberlegen ist.
Zusammenfassend wurde in dieser Arbeit ein in vitro Aktivierungsassay fĂŒr die Metabolite des ArachidonsĂ€uremetabolismus entwickelt, es wurden die zugrundeliegenden regulatorischen Mechanismen charakterisiert sowie das Potential dieses Stoffwechselweges zur diagnostischen Testung von Patienten hinsichtlich dem Vorliegen einer KHK aufgezeigt
Biomarkers of arachidonic acid metabolism as predictors for presence of cardiovascular disease
Eicosanoids are important lipid mediators primarily generated from arachidonic acid (AA) which is liberated out of membrane phospholipids by phospholipase A2 (PLA2). AA is metabolized by cyclooxygenase (COX) and lipoxygenase (LOX) pathways to a number of different metabolites such as thromboxanes, prostaglandins, hydroxyeicosatetraenoic acids (HETE) or leukotrienes. Several lines of evidence implicate an important role of eicosanoids in central processes of inflammation and due to their widespread synthesis in blood and vascular cells these metabolites may play a central role in atherogenesis. On account of this, the analysis of the AA metabolism in whole blood might provide a new marker of atherosclerotic burden and is predestinated as biomarker for diagnosis and prediction of coronary artery disease (CAD).
In previous work, we developed an in vitro assay where whole blood from patients was stimulated with 1 ”g/mL lipopolysaccharide (LPS) for 24 hours. Samples were centrifuged and AA metabolites such as AA, 5-HETE, 11-HETE, 12-HETE, prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) were analyzed out of supernatant by liquid chromatography tandem mass spectrometry. Furthermore, messenger ribonucleic acid for quantitative gene expression analysis of COX-2 and prostaglandin E synthase (PGES) was isolated out of cellular components.
In the current thesis, we improved the in vitro whole blood activation model and established additional quantitative real time polymerase chain reaction assays for PLA2,
COX-1, thromboxane synthase (TXAS), prostaglandin F synthase (PGFS), 5-LOX, 5-LOX activating protein (FLAP) and 12-LOX gene expression analysis to cover major routes of AA metabolism and investigate the discriminatory potential of these eicosanoid pathways for inflammatory diseases.
Furthermore, different stimuli (LPS, tumor necrosis factor alpha and oxidized low-density-lipoprotein) for whole blood activation have been evaluated. Our data revealed most significant effects for LPS which were time- but not dose-dependent.
Since we observed a rapid eicosanoid response upon stimulation we asked whether eicosanoid response on gene expression and metabolite level is preformed or underlies de novo synthesis. To this end, transcriptional and translational inhibition experiments were performed to characterize these regulatory mechanisms. Data suggested that the production of metabolites underlies de novo synthesis upon stimulation, which is controlled both, at the level of transcription and translation.
We then applied the new in vitro whole blood assay to test the variability of the LPS-induced AA metabolism in healthy subjects. We showed major inter-individual differences for all investigated target genes as well as metabolites, suggesting that varying eicosanoid response might be predisposing towards different susceptibility to inflammatory diseases.
The predictive potential of the individual eicosanoid response for the presence of atherosclerosis was examined in 92 patients with or without CAD using the newly developed whole-blood assay. We found that the eicosanoid response on gene expression (COX-1,
COX-2, PGES and FLAP) and metabolite level (AA, 5-, 11- and 12-HETE) was significantly (P<0.05) different in patients with or without CAD. These data allowed developing a score consisting of three biomarkers of AA metabolism with an area under the curve (AUC) of 83.6, which is superior to currently available scores of blood markers of CAD.
Taken together, this work established an in vitro activation assay for the metabolites of AA metabolism, characterized its regulating mechanism and showed its potential for diagnostic testing of patients to the presence of CAD.Eicosanoide sind bedeutende Lipidmediatoren, welche aus ArachidonsĂ€ure (AA) nach deren Freisetzung aus Membranphospholipiden durch die Phospholipase A2 (PLA2) gebildet werden können. AA wird anschlieĂend ĂŒber den Cyclooxygenase (COX-) und Lipoxygenase (LOX-) Stoffwechselweg metabolisiert, wobei eine Reihe von verschiedenen Metaboliten wie Thromboxane, Prostaglandine, HydroxyeicosatetraensĂ€uren (HETE) sowie Leukotriene entstehen. Eicosanoide haben Einfluss auf die zentralen Prozesse von EntzĂŒndungsreaktionen und aufgrund ihrer weit verbreiteten Bildung in Zellen des Blutes sowie des GefĂ€Ăsystems spielen diese Metabolite ebenfalls eine Rolle in der Entstehung der Atherosklerose. Die Untersuchung des AA Metabolismus in Vollblut könnte einen neuen Parameter fĂŒr atherosklerotische VerĂ€nderungen darstellen und ist somit prĂ€destiniert als Biomarker fĂŒr die Diagnostik und PrĂ€diktion einer Koronaren Herzerkrankung (KHK).
In Vorarbeiten unserer Gruppe entwickelten wir einen in vitro Assay, bei dem Vollblut von Patienten mit 1 ”g/ml Lipopolysaccharid (LPS) fĂŒr 24 Stunden stimuliert wurde. Die Proben wurden anschlieĂend zentrifugiert und die Metabolite des AA Metabolismus (AA, 5-HETE,
11-HETE, 12-HETE, Prostaglandin F2α (PGF2α), Prostaglandin E2 (PGE2) und Thromboxan B2 (TxB2)) in den ĂberstĂ€nden mittels FlĂŒssigchromatografie und Tandem-Massenspektrometrie analysiert sowie quantifiziert. Des Weiteren wurde mRNA (messenger RNA) fĂŒr quantitative Genexpressionsanalysen der COX-2 sowie Prostaglandin E-Synthase (PGES) aus den zellulĂ€ren Bestandteilen des Ansatzes isoliert.
Im Rahmen der vorliegenden Promotionsarbeit entwickelten wir das in vitro Vollblutmodel weiter und etablierten zusĂ€tzliche Assays fĂŒr PLA2, COX-1, Prostaglandin F-Synthase (PGFS), Thromboxansynthase (TXAS), 5-LOX, 5-LOX aktivierendes Protein (FLAP) und 12-LOX Genexpressionsanalysen, um so alle Hauptwege des AA Metabolismus abzudecken und das diskriminierende Potential dieser Stoffwechselwege fĂŒr entzĂŒndliche Erkrankungen zu untersuchen.
Des Weiteren wurden verschiedene Stimulanzien (LPS, Tumornekrosefaktor Alpha und oxidiertes Low-Density-Lipoprotein) fĂŒr die Vollblutaktivierung ausgetestet. Unsere Ergebnisse zeigten, dass die stĂ€rksten Effekte LPS-vermittelt waren und eine ausgeprĂ€gte Zeit- jedoch keine DosisabhĂ€ngigkeit aufwiesen.
Da wir eine sehr schnelle Eicosanoidantwort auf den inflammatorischen Stimulus beobachten konnten, fragten wir uns, ob die Eicosanoidantwort auf Genexpressions- und Metabolitenebene bereits vorhanden ist oder einer de novo Synthese unterliegt. Um die regulatorischen Mechanismen besser zu charakterisieren, fĂŒhrten wir Experimente zur Transkriptions- und Translationshemmung durch. Die Daten suggerierten, dass die Produktion der Metabolite einer de novo Synthese nach Stimulation unterliegen, welche sowohl auf der Ebene der Transkription als auch Translation kontrolliert wird.
Wir verwendeten nun das neue in vitro Vollblutmodel an, um zu testen, wie hoch die VariabilitĂ€t des LPS-abhĂ€ngigen AA Metabolismus in gesunden Individuen ist. Wir konnten groĂe interindividuelle Unterschiede fĂŒr alle von uns untersuchten Zielgene sowie
-metaboliten aufzeigen und nahmen an, dass diese variierende Eicosanoidantwort prĂ€disponierend fĂŒr die SuszeptibilitĂ€t fĂŒr entzĂŒndliche Erkrankungen sein könnte.
Das prĂ€diktive Potential der individuellen Eicosanoidantwort fĂŒr das Vorhandensein von Atherosklerose wurde in 92 Probanden mit und ohne KHK mittels des neu entwickelten Vollblutassays geprĂŒft. Wir fanden signifikante Unterschiede (P<0.05) in der Eicosanoidanwort sowohl auf Genexpressions- (COX-1, COX-2, PGES und FLAP) als auch auf Metabolitenebene (AA, 5-, 11- and 12-HETE) zwischen Patienten mit und ohne KHK. Diese Daten erlaubten die Entwicklung eine Scores, welcher aus 3 Biomarkern des AA Metabolismus besteht, eine AUC von 83.6 aufweist und bereits publizierten Scores mit Blutbiomarkern fĂŒr die PrĂ€diktion einer KHK ĂŒberlegen ist.
Zusammenfassend wurde in dieser Arbeit ein in vitro Aktivierungsassay fĂŒr die Metabolite des ArachidonsĂ€uremetabolismus entwickelt, es wurden die zugrundeliegenden regulatorischen Mechanismen charakterisiert sowie das Potential dieses Stoffwechselweges zur diagnostischen Testung von Patienten hinsichtlich dem Vorliegen einer KHK aufgezeigt
Spiritual Experience in Orthodoxy and the Pentecostal Concept of the Works of the Holy Spirit : a Comparative Study = ExperienÈie spirituale Ăźn ortodoxie Ći concepÈia penticostalÄ despre lucrarea Duhului SfĂąnt : studiu comparat
Essays in Comparative International Entrepreneurship Research
There is a broad consensus among researchers, policymakers, and practitioners that socio-cultural conditions influence entrepreneurship profoundly. A rapidly growing, rich, and multidisciplinary literature in comparative international entrepreneurship research has highlighted the importance of socio-cultural conditions in explaining the substantial and persistent variation in entrepreneurship rates around the world. However, the underlying mechanisms through which socio-cultural conditions influence entrepreneurship have remained elusive because of analytical challenges and conflicting findings. To advance this ongoing discussion, this dissertation introduces fresh perspectives that guide theorizing and testing on how socio-cultural conditions influence entrepreneurship. First, the distinct literatures on entrepreneurial process and comparative entrepreneurship research are synthesized against a background of societal social capital theory. Conceptualizing entrepreneurship as a dynamic and regionally embedded multi-staged process, it is shown that regional social capital has a profound yet changing influence over the course of the new venture creation process. Second, combining insights from cross-cultural theory and cultural transmission theory, durability, portability, and intergenerational transmission are articulated as mechanisms that link past cultural conditions in one locality to current entrepreneurial activity in another locality. Studying second-generation immigrants of distinct ancestries, it is shown that (country-of-ancestry) cultural effects can be isolated and influence entrepreneurship in a likely causal way. Third, the conceptual differences are outlined between three perspectives that link culture and entrepreneurship: the aggregate traits, legitimacy, and social support perspectives. Isolating the aggregate traits perspective from the other two perspectives and contextual conditions, it is shown that culture influences entrepreneurship through its effect on individualsâ values
A COLLABORATIVE MODEL FOR VIRTUAL ENTERPRISE
Collaborative process characteristics have three dimensions: actors, activities and actionâs logic. The aim of this paper is to present a virtual portalâs model that helps managing consortiums. Our model based on dynamic e-collaboration and it has a modular structure, multilayer approach. Systemâs functionality of virtual enterprise is collaborative model is concern on usersâ login, based on role and access control, searching and providing distributed resources, accessibility, metadata management and improved informationâs management. Our proposal for developing solution offers a functional architecture of a virtual enterprise using dynamic e-collaboration and shared space.dynamic e-collaboration, multilayer solution, modular approach
Die SchĂ€ferkapelle in Rasch â ein Heiligtum des Wotan, der Gefjon und des Ing? : zu Ikonographie, Baugeschichte und Kulttradition eines heidnischen Tempels
The role of regional social capital changes over the course of the entrepreneurial process
The entrepreneurial process does not take place in a vacuum but is deeply embedded in its context, such as where a would-be entrepreneur lives. Johannes Kleinhempel, Sjoerd Beugelsdijk, and Mariko J. Klasing analyse how socio-cultural conditions shape entrepreneurship, emphasising the critical importance of regional social capital and the changing role of contextual conditions over the course of the entrepreneurial process
Cultural Roots of Entrepreneurship:Evidence from Second-Generation Immigrants
Does national culture influence entrepreneurship? Given that entrepreneurship and the economic, formal institutional, and cultural characteristics of nations are deeply intertwined and co-vary, it is difficult to isolate the effect of culture on entrepreneurship. In this study, we examine the self-employment choices of second-generation immigrants who were born, educated, and currently live in one country, but were raised by parents stemming from another country. We argue that entrepreneurship is influenced by durable, portable, and intergenerationally transmitted cultural imprints such that second-generation immigrants are more likely to become entrepreneurs if their parents originate from countries characterized by a strong entrepreneurial culture. Our multilevel analysis of two independent samplesâ65,323 second-generation immigrants of 52 different ancestries who were born, were raised, and live in the United States and 4,165 second-generation immigrants of 31 ancestries in Europeâshows that entrepreneurial culture is positively associated with the likelihood that individuals are entrepreneurs. Our results are robust to alternative non-cultural explanations, such as differences in resource holdings, labor market discrimination, and direct parent-child linkages. Overall, our study highlights the durability, portability, and intergenerational transmission of entrepreneurial culture as well as the profound impact of national culture on entrepreneurship
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