@phdthesis{Arquint2012, author = {Arquint, Flurina}, title = {Einfluss der kardialen Biomarker N-terminales pro Brain natriuretisches Peptid und kardiales Troponin T auf pl{\"o}tzlichen Herztod, Schlaganfall, Myokardinfarkt und Gesamtmortalit{\"a}t bei Patienten mit Diabetes mellitus Typ 2 an der H{\"a}modialyse}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75274}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {In dieser post-hoc Analyse der Deutschen Diabetes und Dialyse Studie wurde der Einfluss von NT-proBNP und Troponin T auf pl{\"o}tzlichen Herztod, Schlaganfall, Myokardinfarkt und die Gesamtmortalit{\"a}t w{\"a}hrend vierj{\"a}hriger Studiendauer bei 1255 Patienten mit Diabetes mellitus Typ 2 an der H{\"a}modialyse analysiert. Des Weiteren wurde die Bedeutung einer longitudinalen Messung der Biomarker nach 6 Monaten auf die Endpunkte untersucht. Patienten mit dem h{\"o}chsten NT-proBNP respektive Troponin T wiesen die gr{\"o}ßte Ereignisrate f{\"u}r pl{\"o}tzlichen Herztod, Schlaganfall und die Gesamtmortalit{\"a}t auf. In der multivariaten Regressionsanalyse waren sowohl NT-proBNP als auch Troponin T jeweils starke unabh{\"a}ngige Pr{\"a}diktoren f{\"u}r pl{\"o}tzlichen Herztod, Schlaganfall und die Gesamtmortalit{\"a}t. Eine Assoziation von NT-proBNP mit dem Auftreten von Myokardinfarkten wurde nicht gesehen. Nicht nur ein hoher Ausgangswert der Biomarker, sondern auch eine Zunahme von NT-proBNP und Troponin T nach 6 Monaten waren assoziiert mit einer schlechteren Langzeitprognose}, subject = {Brain natriuretic Peptide}, language = {de} } @phdthesis{Bartl2012, author = {Bartl, Jasmin}, title = {Impairment of insulin signaling pathway in Alzheimer's disease}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74197}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {The neurodegenerative disorder Alzheimer's disease (AD) is the cause of approximately 60\% of the world's 35 million patients suffering from dementia. Current research focuses here are on association with other diseases such as diabetes type 2 (T2DM), possible genetic markers, specific signal transduction pathways within the brain and potential protein modification, because the pathogenesis and etiology of AD are still not fully understood. Specifically association of T2DM with AD came to the focus with the so-called "Rotterdam study" in 1999, indicating that T2DM doubles the risk of developing AD. In the meantime, it is known that the prevalence rate in patients with T2DM is 30\%. Drugs commonly used in the treatment of T2DM such as peroxisome proliferator-activated receptors gamma (PPARγ) agonists show improvement of the cognitive abilities in patients with early stage of dementia, with potential therapeutically relevance. Therefore it is important not only to investigate a link between these diseases, but also to investigate the insulin signaling pathway in the brain of AD patients. In order to investigate this complex issue in more details and demonstrate additional links between T2DM and AD, the present study used several basic biological methods to clarify the question: "Is impaired insulin signaling pathway within the brain crucial for the development of AD?" from several points of view. The methods used in this work have been i) an analysis of single nucleotide (SNP) polymorphism of the insulin-degrading enzyme gene (IDE) in relation to risk of AD and / or of T2DM, ii) post-mortem histochemical studies of brain tissue of patients with only AD, with AD combined with T2DM and with only T2DM compared with an age-matched control group, and iii.) investigations of neurochemical pathways and gene/protein expression changes of a human cell culture as a consequences of amyloid β (Aβ) treatment. After analysis of the IDE SNP polymorphism in the selected VITA (Vienna Trans Danube Aging) cohort disease-specific effects were discovered. The upstream polymorphism (IDE2) was found to influence AD risk in a protective manner, while the downstream polymorphism (IDE7) modified the T2DM risk. Based on the SNP results, the presented study delineate the model that IDE promoter and 3‟ untranslated region/downstream variation can have different effects on IDE expression, maybe a relevant endophenotype with disorder-specific effects on AD and T2DM susceptibility. Furthermore, the human post-mortem studies could show that both AD as well as T2DM patients had a significantly lower density of the insulin receptor (IR) in the hippocampus, whereas a significantly increased density of inactive phosphorylated PPARγ has been found and this persisted even in patients with both diseases. Summarizing the histological study, it was possible to reveal common histological features of AD and T2DM, but no direct connection between the two diseases. Although AD is nowadays not only characterized by amyloid-containing plaque deposits and by the hyperphosphorylation of tau protein, the excessive Aβ42 presence in the brains of AD patients is still playing a key role. Up to date it is still not entirely clear which physical form of Aβ42 is responsible for the development of AD. The present work investigated, what impact has the state of aggregation of Aβ42 on genes and proteins of the insulin signaling pathway and the amyloid cascade. It could be shown that the oligomeric variant enhanced specifically the gene and protein expression of glycogen synthase kinase (GSK) 3β and also the enzyme activity was significantly increased, but has in turn strongly inhibited the IR gene and protein expression. Additionally, the effect of Aβ42 on monoamine oxidase B (MAO-B) was examined. An effect of both aggregated forms of Aβ42 had on enzyme activity was discovered. However, the fibrillar variants led to significantly increased activity of MAO-B while the oligomeric variants inhibited the enzyme activity. Several previous studies have demonstrated the involvement of increased MAO-B activity in AD, but the present work provides for the first time a direct link between the states of aggregation of Aβ42 to enzyme activity. Finally the results of the presented thesis can be summarized to following conclusion: Although AD and T2DM sharing some degrees of common features, still there is a lack of direct association, and therefore the diseases must be considered more independent rather than linked. But the impaired cerebral insulin signaling pathway seems to be another manifested hallmark of AD.}, subject = {Alzheimer-Krankheit}, language = {en} } @phdthesis{Menninger2012, author = {Menninger, Stefanie}, title = {Verbesserung der vaskul{\"a}ren Funktion und Reduzierung der Thrombozytenaktivierung durch Telmisartan bei Ratten mit Streptozotocin-induziertem Diabetes mellitus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-77292}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {Die vorliegende Arbeit untersucht die positiven Auswirkungen des Angiotensin-II-Rezeptor-Antagonisten Telmisartan auf die endotheliale Funktion und Thrombozytenaktivierung bei Ratten mit Streptozotocin-induziertem Diabetes mellitus. In Gef{\"a}ßreaktivit{\"a}tsstudien, Luminometer- und Fluoreszenzmessungen und mit Hilfe der Durchflusszytometrie wurden die Wirkungen des Medikamentes {\"u}berpr{\"u}ft. Es konnte gezeigt werden, dass sich durch Telmisartan die NO-Bioverf{\"u}gbarkeit verbessert, welche maßgeblich f{\"u}r die endotheliale Funktion verantwortlich ist und durch Ca2+-abh{\"a}ngige Aktivierung der eNOS und dehnungsinduzierte, Ca2+-unabh{\"a}ngigen NO-Bildung beeinflusst wird. Positiv wird des Weiteren die Sensitivit{\"a}t der glatten Gef{\"a}ßmuskelzellen gegen{\"u}ber NO beeinflusst, was zur Vasodilatation f{\"u}hrt. Die atherosklerosef{\"o}rdernde Superoxidbildung wird zus{\"a}tzlich reduziert. Es erfolgten außerdem Messungen von thrombozytengebundenem Fibrinogen, dementsprechend der GP IIb/IIIa-Aktivit{\"a}t, und der VASP-Phosphorylierung, demzufolge dem NO/cGMP-Signalweg, in Thrombozyten durch FITC-markierte Antik{\"o}rper mit Hilfe der Durchflusszytometrie. Es wurde gezeigt, dass die Thrombozytenaktivierung, die f{\"u}r den initialen Schritt der Atherosklerose verantwortlich gemacht wird, durch Telmisartan verringert wird. Alle Messungen wurden vergleichend in einer Kontroll-, Placebo- und Telmisartangruppe durchgef{\"u}hrt. Die beobachtete Blutdrucksenkung ist, nach fr{\"u}heren Betrachtungen, nicht alleine verantwortlich f{\"u}r die verbesserte endotheliale Funktion, welche bei dem Einsatz von AT-II-Antagonisten beobachtet wird. Telmisartan wirkt, laut einer Studie, als einziger AT-II-Antagonist als partieller PPAR-Rezeptor, so dass Insulinresistenz und metabolische Parameter verbessert werden. {\"U}ber diese Wirkungen beeinflusst Telmisartan auch die endotheliale Funktion und die Thrombozytenaktivierung. Zur Reduktion von vaskul{\"a}ren Komplikationen bei Diabetes mellitus erscheint Telmisartan aufgrund der vorliegenden Ergebnisse als sinnvolle medikament{\"o}se Therapie.}, subject = {Diabetes mellitus}, language = {de} } @phdthesis{Zheng2012, author = {Zheng, Peilin}, title = {Ptpn22 silencing in the NOD model of type 1 diabetes indicates the human susceptibility allele of PTPN22 is a gain-of-function variant}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-73869}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {PTPN22 encodes the lymphoid tyrosine phosphatase Lyp that can dephosphorylate Lck, ZAP-70 and Fyn to attenuate TCR signaling. A single-nucleotide polymorphism (C1858T) causes a substitution from arginine (R) to tryptophan (W) at 620 residue (R620W). Lyp-620W has been confirmed as a susceptible allele in multiple autoimmune diseases, including type 1 diabetes (T1D). Several independent studies proposed that the disease-associated allele is a gain-of-function variant. However, a recent report found that in human cells and a knockin mouse containing the R620W homolog that Ptpn22 protein degradation is accelerated, indicating Lyp-620W is a loss-of-function variant. Whether Lyp R620W is a gain- or loss-of-function variant remains controversial. To resolve this issue, we generated two lines (P2 and P4) of nonobese diabetic (NOD) mice in which Ptpn22 can be inducibly silenced by RNAi. We found long term silencing of Ptpn22 increased spleen cellularity and regulatory T (Treg) cell numbers, replicating the effect of gene deletion reported in the knockout (KO) B6 mice. Notably, Ptpn22 silencing also increased the reactivity and apoptotic behavior of B lymphocytes, which is consistent with the reduced reactivity and apoptosis of human B cells carrying the alleged gain-of-function PTPN22 allele. Furthermore, loss of Ptpn22 protected P2 KD mice from spontaneous and Cyclophosphamide (CY) induced diabetes. Our data support the notion that Lyp-620W is a gain-of-function variant. Moreover, Lyp may be a valuable target for the treatment of autoimmune diseases.}, subject = {Diabetes mellitus}, language = {en} }