TY - THES A1 - Schlereth, Florian T1 - Expression of the DHEA/DHEAS-Shuttle in cell lines and foetal tissue of human liver, adrenal and cartilage T1 - Expression des DHEA/DHEAS-Shuttles in Zelllinien und fötalem Gewebe der menschlichen Leber, Nebenniere und Knorpel N2 - DHEA is a precursor for the male and female sex hormones testosterone and estradiol, which are mainly secreted from the testes and the ovary, respectively. In addition, epidemiological studies showed that low serum levels of DHEA and DHEAS correlate with the incidence of autoimmune disease, cancer and cardiovascular disease. In vitro, DHEA and DHEAS influenced glucose metabolism in a favourable manner. However, positive effects of DHEA substitution were only significant adrenal insufficiency in women. Steroid sulphotransferase 2A1 (SULT2A1) is the responsible enzyme for sulphonation of DHEA to DHEAS which is thought to be the inactive form of DHEA. In this role, SULT2A1 acts as a central regulator of steroid synthesis because sulphonation of DHEA withdraws the substrate for further downstream conversion. Another essential cofactor for sulphonation is PAPS, which is produced by the enzyme PAPS synthase (PAPSS) from ATP and anorganic sulphate. PAPSS exists in the different isoforms PAPSS1 and PAPSS2 and splice variants PAPSS2a and PAPSS2b. Changes in PAPSS activity are thought to influence sulphonation of DHEA significantly. However, neither regulation of PAPSS nor its influence on SULT2A1 have been investigated in human cell lines or humans. The main goal of this thesis was to analyze the enzyme expression of the DHEA/DHEA shuttle, i.e. mRNA and protein of SULT2A1, PAPSS1 and PAPSS2, in various human cell lines. Furthermore, I investigated which cell line could serve as a suitable model for further research regarding regulation of SULT2A1, PAPSS1 and PAPSS2. Here, I could show that the enzymes of the DHEA/DHEAS shuttle were expressed in the human adrenal cell line NCI-h295R as both mRNA and protein. In enzyme assays, I was able to prove conversion of DHEA to DHEAS as well as to different other steroids. However, applying Trilostane, a potent inhibitor of CYP3B, effectively directed conversion of DHEA to DHEAS. Using these findings, future experiments can investigate for example the influence of certain cytokines or endocrine disruptors on expression and activity of PAPSS1/2 and on sulphonation of DHEA. In particular, the relatively equal expression of PAPSS1 and PAPSS2 will enable us to do knock down experiments with siRNA to elucidate how the activity of one enzyme changes when the other one fails. Sulphonation of DHEA by SULT2A1 is thought to happen in the cytoplasm or more precisely in the Golgi apparatus. However, experiments in transfected cells have shown both a cytoplasmatic and a nuclear localisation when both enzymes were expressed at the same time. Immunocytochemistry revealed the same results in the adrenal cell line NCI-h295R, where both enzymes were expressed strongly in the nucleus. The physiological role is not clear and requires further research. Presumably, sulphate is activated in the nucleus. However, one could also speculate that a shift of PAPSS to the nucleus could generate a reservoir, which can be activated by re-localisation to the cytoplasm when more PAPS is needed. Expression of SULT2A1 in some foetal tissues has been investigated earlier. Whilst in adult human cartilage PAPSS1 is predominant, in newly born hamsters PAPSS2 is more abundantly expressed. The expression of PAPSS isoforms in highly sulphonating tissue has not been investigated in humans, so far. This work demonstrated a differential expression of SULT2A1, PAPSS1 and PAPSS2 in adult and foetal liver, adrenal and foetal cartilage tissue. In adult and foetal adrenal expression was similar. However, foetal and adult liver differed in the expression of SULT2A1, which was expressed much more in adult tissue. Most importantly, in foetal cartilage there was only a low expression of SULT2A1 and PAPS seems to mostly provided by PAPSS1, which was considerably higher expressed in cartilage than in other tissues. In contrast, PAPSS2 was mainly expressed in adult and foetal adrenal. Additionally, we reported a case of a female patient who had been investigated for hyperandrogenism. Two mutations in the PAPSS2 gene had led to massively reduced serum levels of DHEAS. One heterozygous mutation in the domain of the APS kinase of the PAPSS2 protein leads to substitution of one amino acid at position 48 (T48R). In vitro experiments showed a residual activity of 6% for this mutation. A second mutation in the ATP sulphurylase domain of PAPSS2 was found. The introduction of thymidine instead of cytidine leads to a stop codon, which is presumed to truncate the protein at position 329 (R329X). In vitro, no residual activity was seen for this mutation. The lack of PAPS reduces sulphonation of DHEA but also sulphonation of proteoglycanes, which leads to skeletal abnormalities. The abundance of DHEA enables massive downstream conversion to androgens leading to clinical features of hyperandrogenism. Regarding the bone abnormalities, it is interesting and surprising that activity of PAPSS1 compensated to a great extent in cartilage but was not able to keep up a more considerable sulphonation of DHEA. Possibly, the subcellular localisation might play a role in this scenario. N2 - DHEA ist eine Vorstufe der männlichen und weiblichen Sexualhormone Testosteron bzw. Oestradiol, welche hauptsächlich in den Testes bzw. Ovarien gebildet werden, aber auch in der Körperperipherie aus DHEA gebildet werden können. Desweiteren konnte in epidemiologischen Studien gezeigt werden, dass niedrige Spiegel von DHEA und DHEAS mit dem Auftreten von Autoimmunerkrankungen, Tumorerkrankungen und Herz-Kreislauf-Erkrankungen korrelieren. In vitro konnten beispielsweise günstige Effekte auf den Glukose-Stoffwechsel nachgewiesen werden. Allerdings konnte eine klinisch sinnvolle Gabe von DHEA nur im Rahmen einer Substitution bei Nebenniereninsuffizienz bei Frauen nachgewiesen werden. Verantwortlich für die Sulfonierung von DHEA ist vor allem die Steroid Sulfotransferase 2A1 (SULT2A1). DHEAS wird als inaktivierte Form von DHEA angesehen. SULT2A1 fungiert als zentraler Regulator der Steroid-Synthese, da durch Sulfonierung von DHEA zu DHEAS der weiteren Konversion das Substrat entzogen wird. Für diese Sulfonierung ist PAPS ein essentieller Kofaktor. Das Enzym PAPS-Synthase, von welchem unterschiedliche Splice-Varianten und Isoformen (PAPSS1 und PAPSS2a/b) vorliegen, stellen PAPS aus ATP und anorganischem Sulfat her. Eine Änderung der Aktivität der PAPS-Synthase kann vermutlich die Aktivität der DHEA Sulfotransferase maßgeblich beeinflussen. Weder die Regulation der PAPS Synthase noch deren Wirkung auf SULT2A1 wurden bisher in menschlichen Zelllinien oder beim Menschen untersucht. Hauptziel dieser Arbeit war die Analyse der Enzymexpression des DHEA/DHEAS Shuttles (mRNA und Protein von SULT2A1, PAPSS1, PAPSS2) in verschiedenen humanen Zelllinien. Ferner wurde untersucht, ob eine der Zelllinien als Modell geeignet ist, die Regulation von SULT2A1 sowie insbesondere PAPSS1 und PAPSS2 in bestimmten pathophysiologischen Situationen zu untersuchen. Hier konnte gezeigt werden, dass insbesondere die adrenale Zelllinie NCI-h295R die Enzyme des DHEA/DHEAS Shuttles sowohl als mRNA als auch als Protein exprimiert. Mittels Enzym-Assay konnte eine Konversion von DHEA zu DHEAS und verschiedenen weiteren Steroiden nachgewiesen werden. Eine Hemmung der CYP3B-abhängigen Konversion mittels Trilostane unterdrückt die Bildung von weiteren Androgenen in NCI-h295R Zellen allerdings effektiv, sodass DHEA größtenteils zu DHEAS konvertiert wurde. Hieraus ergeben sich vielfältige Möglichkeiten, z.B. den Einfluss von Zytokinen oder von endokrinen Disruptoren auf die Sulfonierung von DHEA und auf die Expression von PAPSS1/2 zu untersuchen. Insbesondere kann aufgrund der ähnlichen Expression von PAPSS1 und PAPSS2 in dieser Zelllinie untersucht werden, welche Auswirkung ein Ausschalten eines Enzyms mittels siRNA auf das jeweils andere hat. Die Sulfonierung von DHEA durch SULT2A1 geschieht im Zytoplasma bzw. im Golgi Apparat. Allerdings haben Untersuchungen an transfizierten Zelllinien gezeigt, dass PAPSS1 bzw. PAPSS2 sowohl im Plasma als auch nukleär vorliegen können, wenn beide gleichzeitig exprimiert waren. Mittels Immunzytochemie konnten diese Ergebnisse auch in der Zelllinie NCI-h295R nachgewiesen werden. Beide Enzyme sind auch hier vor allem nukleär exprimiert. Der physiologische Hintergrund dieser Lokalisierung ist nicht geklärt und erfordert weitere Erforschung. Vermutlich erfolgt die Sulfat-Aktivierung also im Nukleus. Möglicherweise stellt die Verlagerung der Enzyme in den Nukleus aber auch eine Reserve der PAPS Synthese dar, die durch Rückverlagerung ins Zytoplasma dort rasch zusätzliches PAPS zur Verfügung stellen kann. Die Expression der DHEA Sulfotransferase wurde bereits in einigen fötalen Geweben untersucht. Während in adultem Knorpel beim Menschen die Expression von PAPSS1 dominiert, wird z.B. im Knorpel von neugeborenen Hamstern vor allem PAPSS2 gebildet. Welche Isoform von PAPSS in welchen fötalen Geweben beim Menschen dominiert, wurde bislang nicht untersucht. In dieser Arbeit konnte mittels Realtime PCR eine differenzierte Expression von SULT2A1, PAPSS1 und PAPSS2 in fötalen Geweben nachgewiesen werden. In adultem und fötalem Gewebe der Nebennieren zeigte sich ein ähnliches Expressionsmuster. Während allerdings in der adulten Leber viel SULT2A1 vorhanden ist, konnte nur eine deutlich niedrigere Expression in fötalem Gewebe gezeigt werden. In fötalem Knorpel findet sich kaum SULT2A1. Dagegen wird in fötalem Knorpel deutlich mehr PAPSS1 gebildet als in adultem und fötalem Leber- bzw. Nebennieren-Gewebe. PAPSS2 ist sowohl beim Erwachsenen als auch beim Fötus hauptsächlich in der Nebenniere exprimiert. Auffällig ist eine relativ geringe Expression in der fötalen Leber. Ergänzend wird in dieser Arbeit eine Patientin mit Hyperandrogenismus vorgestellt, bei der zwei Mutationen im PAPSS2 Gen zu einem massiv erniedrigten DHEAS Spiegel geführt hatten. Eine heterozygote Mutation liegt im Bereich der APS-Kinase von PAPSS2 und führt zum Austausch einer Aminosäure an Position 48 im PAPSS2a Protein (T48R). In vitro konnte für diese Mutation eine Reduktion der Aktivität auf 6% nachgewiesen werden. Eine zweite Mutation fand sich in der ATP Sulfurylase Domäne von PAPSS2. Durch einen Nukleosid-Austausch (Thymidin statt Cytidin) entsteht ein Stop-Codon, was vermutlich an Position 329 zum Abbruch des Proteins führt (R329X). In vitro konnte für diese Mutation (R329X) keine Aktivität nachgewiesen werden. Durch das Fehlen von PAPS ist die Sulfonierung von Proteoglykanen im Knorpel gestört, was zu Skelettveränderungen führt. Vor allem aber kommt es durch das Fehlen der Inaktivierung von DHEA zu DHEAS zu einem Überangebot an DHEA. Dieses wird zu aktiven Androgenen konvertiert und verursacht klinisch einen Hyperandrogenismus. Interessant und überraschend ist, dass die PAPSS1-Aktivität im Knorpel eine gewisse Sulfonierung der Proteoglykane ermöglicht. Im Gegensatz dazu trägt PAPSS1 offensichtlich kaum zur Sulfonierung von DHEA bei, da der DHEAS Spiegel extrem niedrig ist. Möglicherweise spielt hier auch die subzelluläre Lokalisation der PAPS Synthase eine entscheidende Rolle. KW - Dehydroepiandrosteron KW - Zelllinie KW - Phosphoadenosinphosphosulfat KW - DHEA KW - PAPSS2 KW - adrenal KW - cell lines KW - DHEA-Sulfotransferase Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-102068 ER - TY - THES A1 - Michalska, Marta T1 - Molecular Imaging of atherosclerosis T1 - Molekulare Bildgebung der Atherosklerose N2 - Atherosklerose ist eine aktive und progressive Erkrankung, bei der vaskuläre Adhäsionsmoleküle wie VCAM-1 eine entscheidende Rolle durch Steuerung der Rekrutierung von Immunzellen in den frühen und fortgeschrittenen Plaques spielen. Ein zielgerichteter Einsatz von VCAM-1-Molekülen mit spezifischen Kontrastmitteln ist daher eine Möglichkeit, die VCAM-1-Expression zu kontrollieren, Plaquewachstum ab einem frühen Zeitpunkt zu visualisieren und eine frühe Prävention von Atherosklerose vor Beginn der Thrombusbildung zu etablieren. Des Weiteren bietet die nichtinvasive Magnetresonanz (MR)-Bildgebung den Vorteil der Kombination molekularer und morphologischer Daten. Sie ermöglicht, mithilfe von entwickelten VCAM-1-markierten Eisenoxidpartikeln, den spezifischen Nachweis entzündlicher Prozesse während der Atherosklerose. Diese Arbeit belegt, dass mit dem VCAM-1-Konzept eine vielversprechende Herangehensweise gefunden wurde und dass das, mit spezifischen superparamagnetischen Eisenoxid (USPIO) konjugierte VCAM-1-Peptid, gegenüber unspezifischer USPIOs ein erhöhtes Potenzial bei der Untersuchung der Atherosklerose in sich trägt. Im ersten Teil der Arbeit konnte im Mausmodell gezeigt werden, dass gerade das VCAM-1-Molekül ein sinnvoller Ansatzpunkt zur Darstellung und Bildgebung von Atherosklerose ist, da in der frühen Phase der Entzündung die vaskulären Zelladhäsionsmoleküle überexprimiert und auch kontinuierlich, während der fortschreitenden Plaquebildung, hochreguliert werden. Weiterhin beschreibt diese Arbeit die Funktionstüchtigkeit und das Vermögen des neu gestalteten USPIO Kontrastmittels mit dem zyklischen Peptid, in seiner Spezialisierung auf die VCAM-1 Erkennung. Experimentelle Studien mit ultra-Hochfeld-MRT ermöglichten weitere ex vivo und in vivo Nachweise der eingesetzten USPIO-VCAM-1-Partikel innerhalb der Region um die Aortenwurzel in frühen und fortgeschrittenen atherosklerotischen Plaques von 12 und 30 Wochen alten Apolipoprotein E-defizienten (ApoE-/-) Mäusen. Mit ihrer Kombination aus Histologie und Elektronenmikroskopie zeigt diese Studie zum ersten Mal die Verteilung von VCAM-1-markierten USPIO Partikeln nicht nur in luminalem Bereich der Plaques, sondern auch in tieferen Bereichen der medialen Muskelzellen. Dieser spezifische und sensitive Nachweis der frühen und fortgeschrittenen Stadien der Plaquebildung bringt auf molekularer Ebene neue Möglichkeiten zur Früherkennung von atherosklerotischen Plaques vor dem Entstehen von 8 Rupturen. Im Gegensatz zum USPIO-VCAM-1-Kontrastmittel scheiterten unspezifische USPIO Partikel an der Identifikation früher Plaqueformen und begrenzten die Visualisierung von Atherosklerose auf fortgeschrittene Stadien in ApoE-/- Mäusen. N2 - Atherosclerosis is an active and progressive condition where the vascular cell adhesion molecules as VCAM-1 play a vital role controlling the recruitment of immune cells within the early and advanced plaques. Therefore targeting of VCAM-1 molecules with specific contrast agent bears the possibility to monitor the VCAM-1 expression, visualize the plaque progression starting at the early alterations, and help to establish early prevention of atherosclerosis before the origin of the thrombus formation, of which late recognition leads to myocardial infarction. Furthermore noninvasive magnetic resonance imaging (MRI) offers the benefit of combining the molecular and anatomic data and would thus enable specific detection of VCAM-1 targeted iron oxide contrast agent within inflammatory process of atherosclerosis. This thesis exactly presents the VCAM-1 concept as a suitable molecular approach and the potential of specific ultrasmall superparamagnetic iron oxide (USPIO) conjugated to the VCAM-1 binding peptide over unspecific non-targeted USPIO particles for evaluation of atherosclerosis. This work firstly demonstrated that selection of VCAM-1 molecules offers a good and potential strategy for imaging of atherosclerosis, as these vascular cell adhesion molecules are highly expressed in the early phase of inflammation and also continuously up-regulated within the advanced plaques. Secondly, this thesis showed the proof of principle and capability of the newly designed USPIO contrast agent conjugated to the specific cyclic peptide for VCAM-1 recognition. The experimental studies including ultra-high field MRI enabled further ex vivo and in vivo detection of applied USPIO-VCAM-1 particles within the aortic root region of early and advanced atherosclerotic plaques of 12 and 30 week old apolipoprotein E deficient (ApoE-/-) mice. Using a combination of histology and electron microscopy, this study for the first time pointed to distribution of targeted USPIO-VCAM-1 particles within plaque cells expressing VCAM-1 not only in luminal regions but also in deeper medial smooth muscle cell areas. Hence functionalized USPIO particles targeting VCAM-1 molecules allow specific and sensitive detection of early and advanced plaques at the molecular level, giving the new possibilities for early recognition of atherosclerotic plaques before the appearance of advanced and prone to rupture lesions. In contrast to the functionalized USPIO-VCAM-1, utilized non-targeted USPIO particles did not succeed in early plaque 6 identification limiting visualization of atherosclerosis to advanced forms in atherosclerotic ApoE-/- mice. KW - VCAM KW - Arteriosklerose KW - Superparamagnetische Eisenoxid Kontrastmittel KW - vaskuläre Adhäsionsmoleküle KW - Atherosklerose KW - superparamagnetische Eisenoxid Kontrastmittel KW - vascular cell adhesion molecules KW - atherosclerosis KW - iron oxide contrast agent KW - Kontrastmittel Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-73243 ER - TY - JOUR A1 - Johanssen, Sarah A1 - Hahner, Stefanie A1 - Saeger, Wolfgang A1 - Quinkler, Marcus A1 - Beuschlein, Felix A1 - Dralle, Henning A1 - Haaf, Michaela A1 - Kroiss, Matthias A1 - Jurowich, Christian A1 - Langer, Peter A1 - Oelkers, Wolfgang A1 - Spahn, Martin A1 - Willenberg, Holger S. A1 - Maeder, Uwe A1 - Allolio, Bruno A1 - Fassnacht, Martin T1 - Deficits in the Management of Patients With Adrenocortical Carcinoma in Germany N2 - Background: Adrenocortical carcinoma (ACC) is a rare tumor with a poor prognosis. Often, the physicians who first treat patients with ACC have no prior experience with the disease. The aim of our study was to evaluate the quality of medical care for patients with ACC in Germany. Methods: Data from the German ACC registry were analyzed with regard to the patients’ preoperative diagnostic evaluation, histopathological reporting, and clinical followup. The findings were compared with the recommendations of the European Network for the Study of Adrenal Tumors (ENSAT). Results: Data were analyzed from 387 patients who had been given an initial diagnosis of ACC in the years 1998 to 2009. 21% of them underwent no hormonal evaluation before surgery, and 59% underwent an inadequate hormonal evaluation. This exposed the patients to unnecessary perioperative risks and impaired their follow-up. 48% did not undergo CT scanning of the chest, even though the lungs are the most frequent site of metastases of ACC. For 13% of the patients, the diagnosis of ACC was later revised by a reference pathologist. For 11% of the patients, the histopathology report contained no information about resection status, even though this is an important determinant of further treatment and prognosis. Optimal management requires re-staging at three-month intervals, yet some patients underwent re-staging only after a longer delay, or not at all. Conclusion: We have identified significant deficits in the care of patients with ACC in Germany. We suspect that the situation is similar for other rare diseases. The prerequisite to better care is close and early cooperation of the treating physicians with specialized centers. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-85897 ER - TY - JOUR A1 - Chopra, Martin A1 - Lang, Isabell A1 - Salzmann, Steffen A1 - Pachel, Christina A1 - Kraus, Sabrina A1 - Bäuerlein, Carina A. A1 - Brede, Christian A1 - Jordán Garrote, Ana-Laura A1 - Mattenheimer, Katharina A1 - Ritz, Miriam A1 - Schwinn, Stefanie A1 - Graf, Carolin A1 - Schäfer, Viktoria A1 - Frantz, Stefan A1 - Einsele, Hermann A1 - Wajant, Harald A1 - Beilhack, Andreas T1 - Tumor Necrosis Factor Induces Tumor Promoting and Anti-Tumoral Effects on Pancreatic Cancer via TNFR1 JF - PLoS ONE N2 - Multiple activities are ascribed to the cytokine tumor necrosis factor (TNF) in health and disease. In particular, TNF was shown to affect carcinogenesis in multiple ways. This cytokine acts via the activation of two cell surface receptors, TNFR1, which is associated with inflammation, and TNFR2, which was shown to cause anti-inflammatory signaling. We assessed the effects of TNF and its two receptors on the progression of pancreatic cancer by in vivo bioluminescence imaging in a syngeneic orthotopic tumor mouse model with Panc02 cells. Mice deficient for TNFR1 were unable to spontaneously reject Panc02 tumors and furthermore displayed enhanced tumor progression. In contrast, a fraction of wild type (37.5%), TNF deficient (12.5%), and TNFR2 deficient mice (22.2%) were able to fully reject the tumor within two weeks. Pancreatic tumors in TNFR1 deficient mice displayed increased vascular density, enhanced infiltration of CD4+ T cells and CD4+ forkhead box P3 (FoxP3)+ regulatory T cells (Treg) but reduced numbers of CD8+ T cells. These alterations were further accompanied by transcriptional upregulation of IL4. Thus, TNF and TNFR1 are required in pancreatic ductal carcinoma to ensure optimal CD8+ T cell-mediated immunosurveillance and tumor rejection. Exogenous systemic administration of human TNF, however, which only interacts with murine TNFR1, accelerated tumor progression. This suggests that TNFR1 has basically the capability in the Panc02 model to trigger pro-and anti-tumoral effects but the spatiotemporal availability of TNF seems to determine finally the overall outcome. KW - Bioluminescence KW - cancer treatment KW - cell staining KW - cytokines KW - immune cells KW - metastasis KW - regulatory T cells KW - T cells Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-97246 ER - TY - JOUR A1 - Sbiera, Silviu A1 - Ronchi, Cristina L. A1 - Leich, Ellen A1 - Henzel, Katharina A1 - Rosenwald, Andreas A1 - Allolio, Bruno A1 - Fassnacht, Martin T1 - Single Nucleotide Polymorphism Array Profiling of Adrenocortical Tumors - Evidence for an Adenoma Carcinoma Sequence? JF - PLoS ONE N2 - Adrenocortical tumors consist of benign adenomas and highly malignant carcinomas with a still incompletely understood pathogenesis. A total of 46 adrenocortical tumors (24 adenomas and 22 carcinomas) were investigated aiming to identify novel genes involved in adrenocortical tumorigenesis. High-resolution single nucleotide polymorphism arrays (Affymetrix) were used to detect copy number alterations (CNAs) and copy neutral losses of heterozygosity (cnLOH). Genomic clustering showed good separation between adenomas and carcinomas, with best partition including only chromosome 5, which was highly amplified in 17/22 malignant tumors. The malignant tumors had more relevant genomic aberrations than benign tumors, such as a higher median number of recurrent CNA (2631 vs 94), CNAs >100 Kb (62.5 vs 7) and CN losses (72.5 vs 5.5), and a higher percentage of samples with cnLOH (91% vs 29%). Within the carcinoma cohort, a precise genetic pattern (i.e. large gains at chr 5, 7, 12, and 19, and losses at chr 1, 2, 13, 17, and 22) was associated with a better prognosis (overall survival: 72.2 vs 35.4 months, P=0.063). Interestingly, >70% of gains frequent in beningn were also present in malignant tumors. Notch signaling was the most frequently involved pathway in both tumor entities. Finally, a CN gain at imprinted “IGF2” locus chr 11p15.5 appeared to be an early alteration in a multi-step tumor progression, followed by the loss of one or two alleles, associated with increased IGF2 expression, only in carcinomas. Our study serves as database for the identification of genes and pathways, such as Notch signaling, which could be involved in the pathogenesis of adrenocortical tumors. Using these data, we postulate an adenoma-carcinoma sequence for these tumors. KW - adenomas KW - cancer diagnosis KW - cancer detection KW - carcinogenesis KW - carcinomas KW - chromosomes KW - genetic loci KW - malignant tumors KW - notch signaling Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-97218 ER - TY - JOUR A1 - Winter, Patrick A1 - Kampf, Thomas A1 - Helluy, Xavier A1 - Gutjahr, Fabian T. A1 - Meyer, Cord B. A1 - Rommel, Eberhard A1 - Bauer, Wolfgang R. A1 - Jakob, Peter M. A1 - Herold, Volker T1 - Fast retrospectively triggered local pulse-wave velocity measurements in mice with CMR-microscopy using a radial trajectory JF - Journal of Cardiovascular Magnetic Resonance N2 - Background The aortic pulse-wave velocity (PWV) is an important indicator of cardiovascular risk. In recent studies MRI methods have been developed to measure this parameter noninvasively in mice. Present techniques require additional hardware for cardiac and respiratory gating. In this work a robust self-gated measurement of the local PWV in mice without the need of triggering probes is proposed. Methods The local PWV of 6-months-old wild-type C57BL/6J mice (n=6) was measured in the abdominal aorta with a retrospectively triggered radial Phase Contrast (PC) MR sequence using the flow-area (QA) method. A navigator signal was extracted from the CMR data of highly asymmetric radial projections with short repetition time (TR=3 ms) and post-processed with high-pass and low-pass filters for retrospective cardiac and respiratory gating. The self-gating signal was used for a reconstruction of high-resolution Cine frames of the aortic motion. To assess the local PWV the volume flow Q and the cross-sectional area A of the aorta were determined. The results were compared with the values measured with a triggered Cartesian and an undersampled triggered radial PC-Cine sequence. Results In all examined animals a self-gating signal could be extracted and used for retrospective breath-gating and PC-Cine reconstruction. With the non-triggered measurement PWV values of 2.3±0.2 m/s were determined. These values are in agreement with those measured with the triggered Cartesian (2.4±0.2 m/s) and the triggered radial (2.3±0.2 m/s) measurement. Due to the strong robustness of the radial trajectory against undersampling an acceleration of more than two relative to the prospectively triggered Cartesian sampling could be achieved with the retrospective method. Conclusion With the radial flow-encoding sequence the extraction of a self-gating signal is feasible. The retrospective method enables a robust and fast measurement of the local PWV without the need of additional trigger hardware. KW - pulse-wave velocity KW - mouse KW - self-gating KW - phase-contrast CMR KW - non-triggered KW - retrospective KW - radial KW - aorta Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96602 UR - http://jcmr-online.com/content/15/1/88 ER - TY - JOUR A1 - Gassenmaier, Tobias A1 - Gorski, Armin A1 - Aleksic, Ivan A1 - Deubner, Nikolas A1 - Weidemann, Frank A1 - Beer, Meinrad T1 - Impact of cardiac magnet resonance imaging on management of ventricular septal rupture after acute myocardial infarction JF - World Journal of Cardiology N2 - A 74-year-old man was admitted to the cardiac catheterization laboratory with acute myocardial infarction. After successful angioplasty and stent implantation into the right coronary artery, he developed cardiogenic shock the following day. Echocardiography showed ventricular septal rupture. Cardiac magnet resonance imaging (MRI) was performed on the critically ill patient and provided detailed information on size and localization of the ruptured septum by the use of fast MRI sequences. Moreover, the MRI revealed that the ventricular septal rupture was within the myocardial infarction area, which was substantially larger than the rupture. As the patient’s condition worsened, he was intubated and had intra-aortic balloon pump implanted, and extracorporeal membrane oxygenation was initiated. During the following days, the patient’s situation improved, and surgical correction of the ventricular septal defect could successfully be performed. To the best of our knowledge, this case report is the first description of postinfarction ventricular septal rupture by the use of cardiac MRI in an intensive care patient with cardiogenic shock and subsequent successful surgical repair. KW - Cardiac magnetic resonance imaging KW - Ventricular septal rupture KW - Myocardial infarction KW - surgical repair KW - Extracorporeal membrane oxygenation Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96562 ER - TY - JOUR A1 - Üçeyler, Nurcan A1 - Kahn, Ann-Kathrin A1 - Kramer, Daniela A1 - Zeller, Daniel A1 - Casanova-Molla, Jordi A1 - Wanner, Christoph A1 - Weidemann, Frank A1 - Katsarava, Zaza A1 - Sommer, Claudia T1 - Impaired small fiber conduction in patients with Fabry disease: a neurophysiological case–control study JF - BMC Neurology N2 - Background Fabry disease is an inborn lysosomal storage disorder which is associated with small fiber neuropathy. We set out to investigate small fiber conduction in Fabry patients using pain-related evoked potentials (PREP). Methods In this case–control study we prospectively studied 76 consecutive Fabry patients for electrical small fiber conduction in correlation with small fiber function and morphology. Data were compared with healthy controls using non-parametric statistical tests. All patients underwent neurological examination and were investigated with pain and depression questionnaires. Small fiber function (quantitative sensory testing, QST), morphology (skin punch biopsy), and electrical conduction (PREP) were assessed and correlated. Patients were stratified for gender and disease severity as reflected by renal function. Results All Fabry patients (31 men, 45 women) had small fiber neuropathy. Men with Fabry disease showed impaired cold (p < 0.01) and warm perception (p < 0.05), while women did not differ from controls. Intraepidermal nerve fiber density (IENFD) was reduced at the lower leg (p < 0.001) and the back (p < 0.05) mainly of men with impaired renal function. When investigating A-delta fiber conduction with PREP, men but not women with Fabry disease had lower amplitudes upon stimulation at face (p < 0.01), hands (p < 0.05), and feet (p < 0.01) compared to controls. PREP amplitudes further decreased with advance in disease severity. PREP amplitudes and warm (p < 0.05) and cold detection thresholds (p < 0.01) at the feet correlated positively in male patients. Conclusion Small fiber conduction is impaired in men with Fabry disease and worsens with advanced disease severity. PREP are well-suited to measure A-delta fiber conduction. KW - Fabry disease KW - Pain-related evoked potentials KW - Small fiber neuropathy KW - A-delta fibers Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96527 UR - http://www.biomedcentral.com/1471-2377/13/47 ER - TY - JOUR A1 - Elias, Johannes A1 - Heuschmann, Peter U. A1 - Schmitt, Corinna A1 - Eckhardt, Frithjof A1 - Boehm, Hartmut A1 - Maier, Sebastian A1 - Kolb-Mäurer, Annette A1 - Riedmiller, Hubertus A1 - Müllges, Wolfgang A1 - Weisser, Christoph A1 - Wunder, Christian A1 - Frosch, Matthias A1 - Vogel, Ulrich T1 - Prevalence dependent calibration of a predictive model for nasal carriage of methicillin-resistant Staphylococcus aureus JF - BMC Infectious Diseases N2 - Background Published models predicting nasal colonization with Methicillin-resistant Staphylococcus aureus among hospital admissions predominantly focus on separation of carriers from non-carriers and are frequently evaluated using measures of discrimination. In contrast, accurate estimation of carriage probability, which may inform decisions regarding treatment and infection control, is rarely assessed. Furthermore, no published models adjust for MRSA prevalence. Methods Using logistic regression, a scoring system (values from 0 to 200) predicting nasal carriage of MRSA was created using a derivation cohort of 3091 individuals admitted to a European tertiary referral center between July 2007 and March 2008. The expected positive predictive value of a rapid diagnostic test (GeneOhm, Becton & Dickinson Co.) was modeled using non-linear regression according to score. Models were validated on a second cohort from the same hospital consisting of 2043 patients admitted between August 2008 and January 2012. Our suggested correction score for prevalence was proportional to the log-transformed odds ratio between cohorts. Calibration before and after correction, i.e. accurate classification into arbitrary strata, was assessed with the Hosmer-Lemeshow-Test. Results Treating culture as reference, the rapid diagnostic test had positive predictive values of 64.8% and 54.0% in derivation and internal validation corhorts with prevalences of 2.3% and 1.7%, respectively. In addition to low prevalence, low positive predictive values were due to high proportion (> 66%) of mecA-negative Staphylococcus aureus among false positive results. Age, nursing home residence, admission through the medical emergency department, and ICD-10-GM admission diagnoses starting with “A” or “J” were associated with MRSA carriage and were thus included in the scoring system, which showed good calibration in predicting probability of carriage and the rapid diagnostic test’s expected positive predictive value. Calibration for both probability of carriage and expected positive predictive value in the internal validation cohort was improved by applying the correction score. Conclusions Given a set of patient parameters, the presented models accurately predict a) probability of nasal carriage of MRSA and b) a rapid diagnostic test’s expected positive predictive value. While the former can inform decisions regarding empiric antibiotic treatment and infection control, the latter can influence choice of screening method. KW - Methicillin-resistant staphylococcus aureus KW - Infection control KW - Clinical prediction rule KW - Predictive value of tests KW - False positive reactions KW - Calibration Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96091 UR - http://www.biomedcentral.com/1471-2334/13/111 ER - TY - JOUR A1 - Haring, Bernhard A1 - Pettinger, Mary A1 - Bea, Jennifer W. A1 - Wactawski-Wende, Jean A1 - Carnahan, Ryan M. A1 - Ockene, Judith K. A1 - Wyler von Ballmoos, Moritz A1 - Wallace, Robert B. A1 - Wassertheil-Smoller, Sylvia T1 - Laxative use and incident falls, fractures and change in bone mineral density in postmenopausal women: results from the Women’s Health Initiative JF - BMC Geriatrics N2 - Background Laxatives are among the most widely used over-the-counter medications in the United States but studies examining their potential hazardous side effects are sparse. Associations between laxative use and risk for fractures and change in bone mineral density [BMD] have not previously been investigated. Methods This prospective analysis included 161,808 postmenopausal women (8907 users and 151,497 nonusers of laxatives) enrolled in the WHI Observational Study and Clinical Trials. Women were recruited from October 1, 1993, to December 31, 1998, at 40 clinical centers in the United States and were eligible if they were 50 to 79 years old and were postmenopausal at the time of enrollment. Medication inventories were obtained during in-person interviews at baseline and at the 3-year follow-up visit on everyone. Data on self-reported falls (≥2), fractures (hip and total fractures) were used. BMD was determined at baseline and year 3 at 3 of the 40 clinical centers of the WHI. Results Age-adjusted rates of hip fractures and total fractures, but not for falls were similar between laxative users and non-users regardless of duration of laxative use. The multivariate-adjusted hazard ratios for any laxative use were 1.06 (95% confidence interval [CI], 1.03-1.10) for falls, 1.02 (95% CI, 0.85-1.22) for hip fractures and 1.01 (95% CI, 0.96-1.07) for total fractures. The BMD levels did not statistically differ between laxative users and nonusers at any skeletal site after 3-years intake. Conclusion These findings support a modest association between laxative use and increase in the risk of falls but not for fractures. Its use did not decrease bone mineral density levels in postmenopausal women. Maintaining physical functioning, and providing adequate treatment of comorbidities that predispose individuals for falls should be considered as first measures to avoid potential negative consequences associated with laxative use. KW - laxative KW - use KW - fall KW - fracture KW - bone mineral density KW - aging Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-95960 UR - http://www.biomedcentral.com/1471-2318/13/38 ER - TY - THES A1 - Devine, Eric T1 - Increased removal of protein bound uremic toxins through reversible modification of the ionic strength during hemodiafiltration T1 - Erhöhte Elimination proteingebundener Urämietoxine durch reversible Modifikation der Ionenstärke während der Hämodiafiltration N2 - A large number of metabolic waste products accumulate in the blood of patients with renal failure. Since these solutes have deleterious effects on the biological functions, they are called uremic toxins and have been classified in three groups: 1) small water soluble solutes (MW < 500 Da), 2) small solutes with known protein binding (MW < 500 Da), and 3) middle molecules (500 Da < MW < 60 kDa). Protein bound uremic toxins are poorly removed by conventional hemodialysis treatments because of their high protein binding and high distribution volume. The prototypical protein bound uremic toxins indoxyl sulfate (IS) and p-cresyl sulfate (pCS) are associated with the progression of chronic kidney disease, cardiovascular outcomes, and mortality of patients on maintenance hemodialysis. Furthermore, these two compounds are bound to albumin, the main plasma protein, via electrostatic and/or Van-der-Waals forces. The aim of the present thesis was to develop a dialysis strategy, based on the reversible modification of the ionic strength in the blood stream by increasing the sodium chloride (NaCl) concentration, in order to enhance the removal of protein bound substances, such as IS and pCS, with the ultimate goal to improve clinical patient outcomes. Enhancing the NaCl concentration ([NaCl]) in both human normal and uremic plasma was efficient to reduce the protein bound fraction of both IS and pCS by reducing their binding affinity to albumin. Increasing the ionic strength was feasible during modified pre-dilution hemodiafiltration (HDF) by increasing the [NaCl] in the substitution fluid. The NaCl excess was adequately removed within the hemodialyzer. This method was effective to increase the removal rate of both protein bound uremic toxins. Its ex vivo hemocompatibility, however, was limited by the osmotic shock induced by the high [NaCl] in the substituate. Therefore, modified pre-dilution HDF was further iterated by introducing a second serial cartridge, named the serial dialyzers (SDial) setup. This setting was validated for feasibility, hemocompatibility, and toxin removal efficiency. A better hemocompatibility at similar efficacy was obtained with the SDial setup compared with the modified pre-dilution HDF. Both methods were finally tested in an animal sheep model of dialysis to verify biocompatibility. Low hemolysis and no activation of both the complement and the coagulation systems were observed when increasing the [NaCl] in blood up to 0.45 and 0.60 M with the modified pre-dilution HDF and the SDial setup, respectively. In conclusion, the two dialysis methods developed to transitory enhance the ionic strength in blood demonstrated adequate biocompatibility and improved the removal of protein bound uremic toxins by decreasing their protein bound fraction. The concepts require follow-on clinical trials to assess their in vivo efficacy and their impact on long-term clinical outcomes. N2 - Eine große Zahl von Stoffwechselprodukten akkumuliert im Blut urämischer Patienten mit Nierenversagen. Da diese Moleküle schädliche Wirkungen auf die biologischen Funktionen haben, werden sie als Urämietoxine bezeichnet. Man teilt sie in drei Gruppen ein: 1) kleine wasserlösliche Substanzen (MG < 500 Da), 2) kleine, proteingebundene Substanzen (MG < 500 Da), 3) Mittelmoleküle (500 Da < MG < 60 kDa). Proteingebundene Urämietoxine werden wegen ihrer starken Proteinbindung und ihres Verteilungsvolumen durch klassische Hämodialyseverfahrens nur schlecht entfernt. Die prototypischen proteingebundenen Urämietoxine Indoxylsulfat (IS) und p-Cresylsulfat (pCS) sind bei chronischen niereninsuffizienten Patienten mit dem Fortschreiten der Niereninsuffizienz, Herz-Kreislauf-Erkrankungen und der Mortalität verbunden. Außerdem sind diese beiden Toxine an Albumin, dem wichtigsten Plasmaprotein, durch elektrostatische und/oder Van-der-Waals-Kräfte gebunden. Das Ziel der vorliegenden Arbeit war es, ein Dialyseverfahren basierend auf einer reversiblen Modifikation der Ionenstärke im Blut durch Erhöhung der Natriumchlorid (NaCl)-Konzentration zu entwickeln, um die Entfernung von proteingebundenen Molekülen wie IS und pCS zu erhöhen und dadurch eine Verbesserung des klinischen Verlauf der Patienten zu erreichen. Die Erhöhung der NaCl-Konzentration ([NaCl]) sowohl in normalem als auch in urämischem menschlichem Plasma war geeignet, um den proteingebundenen Anteil von IS und pCS durch Schwächung ihrer Bindungsaffinität zu Albumin zu verringern. Die Erhöhung der Ionenstärke während einer modifizierten Prädilutions-Hämodiafiltration (HDF) konnte durch eine Erhöhung der [NaCl] in der Substitutionslösung umgesetzt werden; dabei wurde der NaCl-Überschuss innerhalb des Dialysators vollständig entfernt. Dieses Verfahren war effektiv, um die Entfernungsrate beider proteingebundenen Urämietoxine zu steigern; seine Ex-vivo-Hämokompatibilität war allerdings aufgrund des osmotischen Schocks infolge der hohen [NaCl] im Substituat begrenzt. Deshalb wurde eine Iteration der modifizierten Prädilutions-HDF durch Einbau eines zweiten, seriellen Dialysators vorgenommen, bezeichnet als serielles Dialysator System (SDial). Diese letzte Methode wurde dann bezüglich der Durchführbarkeit, der Hämokompatibilität und Toxinentfernung validiert. Durch das SDial-System konnte, verglichen mit der modifizierten Prädilutions-HDF, eine bessere Hämokompatibilität bei ähnlicher Wirksamkeit erzielt werden. Beide Methoden, modifizierte Prädilutions-HDF und SDial System, wurden abschließend in ein Tierdialysemodell mit Schafen transferiert, wobei eine zufriedenstellende Biokompatibilität demonstriert werden konnte. Beide, zur vorübergehenden Erhöhung der Ionenstärke im Blut entwickelten Dialyseverfahren zeigten bei zufriedenstellender Biokompatibilität eine verbesserte Entfernung proteingebundener Urämietoxine durch Reduktion ihrer proteingebundenen Fraktion. In einem nächsten Schritt sind klinische Studien erforderlich, die diese Konzepte bezüglich ihrer In-vivo-Wirksamkeit und ihrer langfristigen Wirkung auf den Krankheitsverlauf untersuchen. KW - Hämodiafiltration KW - Ionenstärke KW - Proteinbindung KW - Urämietoxine KW - Hämodialyse KW - Biokompatibilität KW - Ionic strength KW - protein binding KW - uremic toxin KW - hemodialysis KW - biocompatibility KW - Urämie KW - Toxin KW - Ionenstärke KW - Blut Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-83583 ER - TY - JOUR A1 - Güder, Gülmisal A1 - Brenner, Susanne A1 - Angermann, Christiane E. A1 - Ertl, Georg A1 - Held, Matthias A1 - Sachs, Alfred P. A1 - Lammers, Jan Willem A1 - Zanen, Peter A1 - Hoes, Arno W. A1 - Störk, Stefan A1 - Rutten, Frans H. T1 - "GOLD or lower limit of normal definition? a comparison with expert-based diagnosis of chronic obstructive pulmonary disease in a prospective cohort-study" N2 - Background: The Global initiative for chronic Obstructive Lung Disease (GOLD) defines COPD as a fixed postbronchodilator ratio of forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) below 0.7. Agedependent cut-off values below the lower fifth percentile (LLN) of this ratio derived from the general population have been proposed as an alternative. We wanted to assess the diagnostic accuracy and prognostic capability of the GOLD and LLN definition when compared to an expert-based diagnosis. Methods: In a prospective cohort study, 405 patients aged ≥ 65 years with a general practitioner’s diagnosis of COPD were recruited and followed up for 4.5 (median; quartiles 3.9; 5.1) years. Prevalence rates of COPD according to GOLD and three LLN definitions and diagnostic performance measurements were calculated. The reference standard was the diagnosis of COPD of an expert panel that used all available diagnostic information, including spirometry and bodyplethysmography. Results: Compared to the expert panel diagnosis, ‘GOLD-COPD’ misclassified 69 (28%) patients, and the three LLNs misclassified 114 (46%), 96 (39%), and 98 (40%) patients, respectively. The GOLD classification led to more false positives, the LLNs to more false negative diagnoses. The main predictors beyond the FEV1/FVC ratio for an expert diagnosis of COPD were the FEV1 % predicted, and the residual volume/total lung capacity ratio (RV/TLC). Adding FEV1 and RV/TLC to GOLD or LLN improved the diagnostic accuracy, resulting in a significant reduction of up to 50% of the number of misdiagnoses. The expert diagnosis of COPD better predicts exacerbations, hospitalizations and mortality than GOLD or LLN. Conclusions: GOLD criteria over-diagnose COPD, while LLN definitions under-diagnose COPD in elderly patients as compared to an expert panel diagnosis. Incorporating FEV1 and RV/TLC into the GOLD-COPD or LLN-based definition brings both definitions closer to expert panel diagnosis of COPD, and to daily clinical practice. KW - Medizin KW - COPD diagnosis KW - lower limit of normal KW - GOLD KW - validation Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75193 ER - TY - JOUR A1 - Reiter, Theresa A1 - Ritter, Oliver A1 - Prince, Martin R. A1 - Nordbeck, Peter A1 - Wanner, Christoph A1 - Nagel, Eike A1 - Bauer, Wolfgang R. T1 - Minimizing Risk of Nephrogenic systemic fibrosis in Cardiovascular Magnetic Resonance N2 - Nephrogenic Systemic Fibrosis is a rare condition appearing only in patients with severe renal impairment or failure and presents with dermal lesions and involvement of internal organs. Although many cases are mild, an estimated 5 % have a progressive debilitating course. To date, there is no known effective treatment thus stressing the necessity of ample prevention measures. An association with the use of Gadolinium based contrast agents (GBCA) makes Nephrogenic Systemic Fibrosis a potential side effect of contrast enhanced magnetic resonance imaging and offers the opportunity for prevention by limiting use of gadolinium based contrast agents in renal failure patients. In itself toxic, Gadolinium is embedded into chelates that allow its safe use as a contrast agent. One NSF theory is that Gadolinium chelates distribute into the extracellular fluid compartment and set Gadolinium ions free, depending on multiple factors among which the duration of chelates exposure is directly related to the renal function. Major medical societies both in Europe and in North America have developed guidelines for the usage of GBCA. Since the establishment of these guidelines and the increased general awareness of this condition, the occurrence of NSF has been nearly eliminated. Giving an overview over the current knowledge of NSF pathobiochemistry, pathogenesis and treatment options this review focuses on the guidelines of the European Medicines Agency, the European Society of Urogenital Radiology, the FDA and the American College of Radiology from 2008 up to 2011 and the transfer of this knowledge into every day practice. KW - CMR Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75068 ER - TY - JOUR A1 - Fassnacht, Martin A1 - Sbiera, Silviu A1 - Dexneit, Thomas A1 - Reichardt, Sybille D. A1 - Michel, Kai D. A1 - van den Brandt, Jens A1 - Schmull, Sebastian A1 - Kraus, Luitgard A1 - Beyer, Melanie A1 - Mlynski, Robert A1 - Wortmann, Sebastian A1 - Allolio, Bruno A1 - Reichardt, Holger M. T1 - Influence of Short-Term Glucocorticoid Therapy on Regulatory T Cells In Vivo N2 - Background: Pre- and early clinical studies on patients with autoimmune diseases suggested that induction of regulatory T(Treg) cells may contribute to the immunosuppressive effects of glucocorticoids(GCs). Objective: We readdressed the influence of GC therapy on Treg cells in immunocompetent human subjects and naı¨ve mice. Methods: Mice were treated with increasing doses of intravenous dexamethasone followed by oral taper, and Treg cells in spleen and blood were analyzed by FACS. Sixteen patients with sudden hearing loss but without an inflammatory disease received high-dose intravenous prednisolone followed by stepwise dose reduction to low oral prednisolone. Peripheral blood Treg cells were analyzed prior and after a 14 day GC therapy based on different markers. Results: Repeated GC administration to mice for three days dose-dependently decreased the absolute numbers of Treg cells in blood (100 mg dexamethasone/kg body weight: 2.861.86104 cells/ml vs. 336116104 in control mice) and spleen (dexamethasone: 2.861.96105/spleen vs. 956226105/spleen in control mice), which slowly recovered after 14 days taper in spleen but not in blood. The relative frequency of FOXP3+ Treg cells amongst the CD4+ T cells also decreased in a dose dependent manner with the effect being more pronounced in blood than in spleen. The suppressive capacity of Treg cells was unaltered by GC treatment in vitro. In immunocompetent humans, GCs induced mild T cell lymphocytosis. However, it did not change the relative frequency of circulating Treg cells in a relevant manner, although there was some variation depending on the definition of the Treg cells (FOXP3+: 4.061.5% vs 3.461.5%*; AITR+: 0.660.4 vs 0.560.3%, CD127low: 4.061.3 vs 5.063.0%* and CTLA4+: 13.8611.5 vs 15.6612.5%; * p,0.05). Conclusion: Short-term GC therapy does not induce the hitherto supposed increase in circulating Treg cell frequency, neither in immunocompetent humans nor in mice. Thus, it is questionable that the clinical efficacy of GCs is achieved by modulating Treg cell numbers. KW - Medizin Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-74749 ER - TY - JOUR A1 - Bauer, Wolfgang R. A1 - Nadler, Walter T1 - Thermodynamics of Competitive Molecular Channel Transport: Application to Artificial Nuclear Pores N2 - In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species’ translocation probablity when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules. KW - Thermodynamik KW - Transport KW - Molekül KW - Molecular Channel Transport KW - Artificial Nuclear Pores KW - Thermodynamics Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68484 ER - TY - THES A1 - Fiedler, Jan T1 - Endothelial microRNA-24 contributes to capillary density in the infarcted heart N2 - Cardiovascular disease is the most common mortality risk in the industrialized world. Myocardial infarction (MI) results in the irreversible loss of cardiac muscle, triggering pathophysiological remodelling of the ventricle and development of heart failure. Insufficient myocardial capillary density within the surviving myocardium after MI has been identified as a critical event in this process, although the underlying molecular signalling pathways of cardiac angiogenesis are mechanistically not well understood. The discovery of microRNAs (miRNAs, miRs), small non-coding RNAs with 19-25 nucleotides in length, has introduced a new level of the regulation of cardiac signalling pathways. MiRNAs regulate gene expression post-transcriptionally by binding to their complementary target messenger RNAs (mRNAs) and represent promising therapeutic targets for gene therapy. Here, it is shown that cardiac miR-24 is primarily expressed in cardiac endothelial cells and upregulated following MI in mice and hypoxic conditions in vitro. Enhanced miR-24 expression induces endothelial cell apoptosis and impairs endothelial capillary network formation. These effects on endothelial cell biology are at least in part mediated through targeting of transcription factor GATA2, histone deacetylase H2A.X, p21-activated kinase PAK4 and Ras p21 protein activator RASA1. Mechanistically, target repression abolishes respective and secondary downstream signalling cascades. Here it is shown that endothelial GATA2 is an important mediator of cell cycle, apoptosis and angiogenesis at least in part by regulation of cytoprotective heme oxygenase 1 (HMOX1). Moreover, additional control of endothelial apoptosis is achieved by the direct miR-24 target PAK4. Its kinase function is essential for anti-apoptotic Bad phosphorylation in endothelial cells. In a mouse model of MI, blocking of endothelial miR-24 by systemic administration of a specific antagonist (antagomir) enhances capillary density in the infarcted heart and preserves cardiac function. The current findings indicate miR-24 to act as a critical regulator of endothelial cell apoptosis and angiogenesis. Modulation of miR-24 may be potentially a suitable strategy for therapeutic intervention in the setting of ischemic heart diseases. N2 - Kardiovaskuläre Erkrankungen sind die häufigste Todesursache in der industrialisierten Welt. Nach Myokardinfarkt (MI) kommt es zum Verlust kardialen Gewebes und zu pathologischen Umbauprozessen im Herzen, die oftmals in einer Herzinsuffizienz münden. Dabei spielt eine insuffiziente Gefäßversorgung im überlebenden Myokard eine wichtige Rolle. Zugrunde liegende molekulare Mechanismen oder gentherapeutische Strategien zur Verbesserung der Angiogenese nach MI sind jedoch nur unzureichend verstanden und etabliert. Die Entdeckung sogenannter microRNAs (miRNAs, miRs), kleiner nicht-kodierender RNAs mit einer Länge von 19-25 Nukleotiden, zeigt eine neue Ebene der Komplexität bei der Regulation kardiovaskulärer Signalwege auf. So regulieren miRNAs die Genexpression posttranskriptional durch inhibitorische Bindung an komplementäre messenger RNAs. Die Modulation von miRNAs und damit nachfolgenden Gen-Netzwerken könnte daher ein wichtiger Baustein bei der Entwicklung neuer Therapiestrategien in der kardiovaskulären Medizin werden. In dieser Arbeit wird gezeigt, dass kardiale miR-24 überwiegend in kardialen Endothelzellen exprimiert ist und nach Myokardinfarkt im Mausmodell sowie nach Hypoxie in vitro hochreguliert wird. Die verstärkte miR-24-Expression induziert endotheliale Apoptose und vermindert die Kapillarbildungsfähigkeit endothelialer Zellen in einem Angiogeneseassay. Diese funktionalen Defekte werden über die Repression des Transkriptionsfaktors GATA2, der Histon-Deacetylase H2A.X, der p21-aktivierten Kinase PAK4 und dem p21 Protein-Aktivator RASA1 vermittelt. GATA2 wird in dieser Arbeit als wichtiger Faktor für die Zellzykluskontrolle, Apoptose und Angiogenese beschrieben, wobei die Regulation direkter Effektoren wie Hämoxygenase 1 (HMOX1) essentiell ist. Weiterhin wird über die miR-24-abhängige Modulation von PAK4 endotheliale Apoptose kontrolliert. PAK4 weist eine anti-apoptotische Funktion auf, indem es zu einer Phosphorylierung des Proteins Bad führt. Die spezifische Repression endogener miR-24 durch einen Antagonisten (Antagomir) in einem murinen MI-Modell erhöht die Kapillardichte im infarzierten Gewebe und verbessert die kardiale Funktion. Zusammenfassend zeigen die Erkenntnisse dieser Arbeit eine wichtige Funktion für miR-24 bei der Regulation endothelialer Apoptose und Angiogenese. Die Modulation von miR-24 könnte ein interessantes neues therapeutisches Konzept zur Verbesserung der Angiogenese nach MI darstellen. KW - Herzinfarkt KW - miRNS KW - Angiogenese KW - miRNA infarcted heart Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-49809 ER - TY - THES A1 - Liu, Dan T1 - Regional Myocardial Deformation in Adult Patients with Isolated Left Ventricular Non-compaction Cardiomyopathy T1 - Regionale Myokardfunktion bei erwachsenen Patienten mit isolierter ventrikulärer Non-Compaction-Kardiomyopathie N2 - Isolated left ventricular non-compaction cardiomyopathy (LVNC) is a congenital myocardial disease characterized by excessive and prominent trabeculations in the left ventricle with deep intertrabecular recesses. Trabeculation is, however, a non specific finding which is present not only in LVNC but also in other cardiomyopathies like dilated cardiomyopathy (DCM) and even in healthy controls, therefore, differential diagnosis keeps puzzling clinicians. Therefore the present study aimed to comprehensively explore regional myocardial deformation properties in adult patients with isolated LVNC using strain and strain rate imaging derived from tissue Doppler imaging and 2D speckle tracking. It was proposed that the knowledge of deformation properties in LVNC would help to differentiate patients with LVNC and DCM. A total of 14 patients with LVNC, 15 patients with DCM, and 15 healthy controls were included in this study. The groups were matched for age and gender. Standard 2D echocardiography was performed in all subjects, and tissue Doppler imaging (TDI) of all ventricular walls was acquired using parasternal long axis, apical 4-chamber, 2-chamber, and apical long axis views. Deformation imaging data derived from both TDI and grey scale images were analyzed. Clinical and standard echocardiographic findings in patients with LVNC and DCM were similar. In patients with LVNC, hypertrabeculation was mostly located in the apical and mid segments of the left ventricle and strikingly more than in patients with DCM. The extent of non-compaction was poorly related to global left ventricular systolic function (LVEF) as well as regional myocardial function assessed by strain rate imaging. Regional myocardial systolic deformation in patients with LVNC was significantly impaired in the left and right ventricles in both longitudinal and radial direction. There was a striking difference on longitudinal myocardial systolic function between LVNC and DCM patients, i.e., an increasing strain and strain rate gradient from apex to base in patients with LVNC, whereas patients with DCM displayed a homogeneously decreased strain and strain rate in all segments. Results derived from 2D speckle tracking method were consistent with those from TDI method. Analysis of myocardial mechanical asynchrony revealed a lack of myocardial contraction synchrony in the LVNC and DCM patients. The time to systolic peak velocity was obviously delayed in these two patient groups. However, the mechanical asynchrony features were similar in patients with LVNC and DCM and could not serve for differential diagnosis. In conclusion, LVNC and DCM are both cardiomyopathies presenting reduced regional myocardial function and mechanical asynchrony. Nevertheless differential diagnosis can be made by analysis of hypertrabeculation as well as analysis of regional myocardial deformation pattern. N2 - Isolierte ventrikuläre Non-Compaction-Kardiomyopathie (IVNM) ist eine angeborene myokardiale Erkrankung, gekennzeichnet durch Hypertrabekularisierung mit tiefen intertrabekulären Recessus des linken Ventrikels. Da ausgeprägte Trabekularisierung auch in anderen Kardiomyopathien wie der DCM oder sogar beim Gesunden vorkommt, gibt dieser unspezifische Befund dem Kliniker oft Rätsel auf. Ziel der vorliegenden Studie ist eine umfassende Untersuchung der regionalen myokardialen Wanddeformierungseigenschaften bei erwachsenen Patienten mit isolierter IVNM mittels Strain Rate Imaging und 2D Speckle Tracking. Die Annahme war, dass das Wissen um die Deformationseigenschaften bei IVNM helfen würde, diese von der DCM abzugrenzen. In die Studie wurden 14 Patienten mit IVNM, 15 mit DCM und 15 Gesunde als Kontrollgruppe eingeschlossen. Die jeweiligen Gruppen wurden nach Alter und Geschlecht angeglichen. Alle Patienten erhielten eine Standard 2D Echokardiographie. Gewebedoppler (TDI) wurde im apikalen Vier- und Zweikammerblick sowie in der apikalen langen Achse an allen ventrikulären Wänden durchgeführt. Analysiert wurden Daten aus Deformationsaufnahmen sowie TDI und Grey-scale-Bildern. Klinische und standard-echokardiographische Befunde bei IVNM und DCM waren vergleichbar. Bei Patienten mit IVNM war die Hypertrabekularisierung vor allem im apikalen und den mittleren Segmenten des linken Ventrikels lokalisiert, deutlich mehr als bei den Patienten des DCM-Kollektives. Das Non-Compaction Ausmaß korrelierte nur schwach mit der globalen linksventrikulären systolischen Funktion (LVEF). Ebenso verhielt es sich mit der mittels Strain Rate Imaging ermittelten regionalen linksventrikulären Funktion. Die regionale myokardiale systolische Deformation bei IVNM Patienten war links- und rechtsventrikulär sowohl longitudinal als auch radial signifikant vermindert. Auffällige Unterschiede zwischen den IVNM- und DCM-Kollektiven fanden sich in der longitudinalen myokardialen Funktion. Hier zeigten IVNM-Patienten vom Apex zur Basis zunehmende Strain- und Strain-Rate-Gradienten, wohingegen DCM-Patienten gleichmäßig über alle Segmente reduzierte Strain und Strain-Rate Werte aufwiesen. Die mittels 2D Speckle Tracking erhobenen Werte deckten sich mit den Ergebnissen aus den Gewebedoppler Aufnahmen. Die myokardiale kontraktions-Synchronie war bei beiden Patientenkollektiven gestört. Die Zeit bis zum Erreichen der systolischen Spitzengeschwindigkeit war bei beiden Gruppen verlängert. Die myokardialen Asynchronien waren in beiden Gruppen ähnlich und sind aus diesem Grund differentialdiagnostisch nicht hilfreich. Zusammenfassend lässt sich feststellen, dass IVNM und DCM Kardiomyopathien mit reduzierter regionaler myokardialer Funktion sind, die eine mechanische Asynchronie aufweisen. Nichtsdestotrotz kann man die Differentialdiagnose über eine Analyse der Hypertrabekularisierung sowie der regionalen myokardialen Deformierungsmuster stellen. KW - Ultraschallkardiographie KW - Gewebedoppler KW - Non-Compaction Kardiomyopathie KW - Speckle tracking KW - left ventricular non-compaction KW - speckle tracking Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-55838 ER - TY - THES A1 - Burkard, Natalie T1 - Signalübertragungswege und Präventionsmöglichkeiten der kardialen Hypertrophie : conditional overexpression of neuronal nitric oxide synthase is cardioprotective in ischemia-reperfusion T1 - Konditionale Überexpression der neuronalen NO-Synthase wirkt kardioprotektiv bei Ischämie-Reperfusion N2 - Zusammenfassung: Wie früher schon gezeigt, wird der L-Typ Ca2+-Kanal durch eine induzierbare, myokardspezifische Überexpression der neuronalen Stickstoffmonoxidsynthase (nNOS) inhibiert. Gleichzeitig bewirkt diese Überexpression eine verminderte kardiale Kontraktilität1 (Burkard N. et al. (2007). Circ Res 100, 32-44). nNOS interagiert mit vielen verschiedenen Kompartimenten und Kanälen innerhalb der Zelle. In dieser Arbeit wurde gezeigt, dass eine nNOS Überexpression nach Ischämie-Reperfusion kardioprotektiv wirkt. Dieses wird durch eine Inhibition der Mitochondrienfunktion und durch eine Verminderung der reaktiven Sauerstoffspezies (ROS) ermöglicht. In einer früheren Arbeit wurde der Effekt der induzierbaren und myokardspezifischen Überexpression von nNOS unter physiologischen Bedingungen am transgenen Tiermodell untersucht. Diese Arbeit beschäftigt sich nun mit der Überexpression von nNOS unter pathophysiologischen (Ischämie-Reperfusion) Bedingungen. Ein Ischämie-Reperfusions-Schaden bewirkt bei Wildtyp-Mäusen, sowie bei transgener nNOS Überexpression eine Anreicherung von nNOS in den Mitochondrien. Elektronenmikroskopische Aufnahmen von Mausmyokard haben gezeigt, dass bei Überexpression nNOS zusätzlich in den Mitochondrien lokalisiert ist. Diese Translokation von nNOS in die Mitochondrien ist abhängig von HSP90. Ischämie- Reperfusionsexperimente an isolierten Mäuseherzen zeigten einen kardioprotektiven Effekt der nNOS Überexpression (30min post ischemia, LVDP 27.0±2.5mmHg vs. 45.2±1.9mmHg, n=12, p<0.05). Dieser positive Effekt konnte bei der Bestimmung der Infarktgröße bestätigt werden. nNOS überexprimierende Mäuse hatten eine kleinere Infarktgröße nach Ischämie-Reperfusion (36.6±8.4 relative % vs. 61.1±2.9 relative %, n=8, p<0.05). Die Überexpression von nNOS bewirkte ebenfalls einen signifikanten Anstieg des mitochondrialen Nitrit-Levels, begleitet von einer Verminderung der Cytochrom C Oxidase Aktivität (72.0±8.9units/ml in nNOS overexpressing mice vs. 113.2±17.1units/ml in non-induced mice, n=12, p<0.01), was zu einer Hemmung der Mitochondrienfunktion führt. Dementsprechend war der Sauerstoffverbrauch (gemessen an isolierten Herzmuskelstreifen) schon unter basalen Bedingungen beinNOS Überexpression vermindert (0.016±0.0015 vs. 0.024±0.006ml[O2] x mm-3 x min-1, n=13, p<0.05). Außerdem war die ROS Konzentration in Herzen von nNOS überexprimierenden Mäusen signifikant vermindert (6.14±0.685 vs. 14.53±1.7μM, n=8, p<0.01). Die Zugabe von verschiedenen Inhibitoren, Western Blot- und Aktivitätsuntersuchungen zeigten schließlich, dass diese niedrigere ROS Konzentration durch eine verminderte Xanthin Oxidoreduktase Aktivität hervorgerufen wurde. Zusammenfassend hat diese Arbeit gezeigt, dass eine induzierbare und myokardspezifische Überexpression von nNOS unter pathophysiologischen Bedingungen (Ischämie-Reperfusion) kardioprotektiv wirkt. Zusätzlich zu der Verminderung des myokardialen Ca2+-Überschusses nach Reperfusion könnte dieser protektive Effekt durch eine Hemmung der Mitochondrienfunktion bedingt sein, schließlich wird der Sauerstoffverbrauch schon unter basalen Bedingungen reduziert N2 - Summary: I previously demonstrated that conditional overexpression of the neuronal nitric oxide synthase (nNOS) inhibited L-type Ca2+-channels and decreased myocardial contractility1 (Burkard N. et al. (2007). Circ Res 100, 32-44). However, nNOS has multiple targets within the cardiac myocyte and it is possible that interesting biological functions of this protein remain to be elucidated. In this study, I showed that nNOS overexpression has a cardioprotective effect after ischemia-reperfusion injury by inhibiting mitochondrial function and reducing the generation of reactive oxygen species (ROS). The effect of conditional nNOS overexpression in cardiac myocytes in ischemiareperfusion injury was assessed. Ischemia-reperfusion injury in WT mice resulted in nNOS accumulation in the mitochondria. Similary, transgenic nNOS overexpression caused nNOS abundance in mitochondria. Electron microscopy of mouse myocardium from nNOS overexpressing mice showed that after induction of its expression, nNOS is additionally localised in mitochondria. nNOS translocation into mitochondria was dependent on HSP90. Ischemia-reperfusion experiments in isolated hearts showed a cardioprotective effect of nNOS overexpression (30min post-ischemia, LVDP 27.0±2.5mmHg in non-induced animals vs. 45.2±1.9mmHg in nNOS overexpressing mice, n=12, p<0.05). Consistently with this finding, in vivo the infarct size within the area at risk was significantly decreased in nNOS overexpressing mice compared to non-induced animals (36.6±8.4 relative % vs. 61.1±2.9 relative %, n=12, p<0.05). nNOS overexpression also caused a significant increase in mitochondrial nitrite levels accompanied by a decrease of cytochrome c oxidase activity (72.0±8.9units/ml in nNOS overexpressing mice vs. 113.2±17.1units/ml in non-induced mice, n=12, p<0.01) resulting in an inhibition of mitochondrial function. Accordingly, O2-consumption (MVO2) in isolated heart muscle stripes was decreased in nNOS overexpressing mice, already under resting conditions (0.016±0.0015 vs. 0.024±0.006ml[O2] x mm-3 x min-1, n=13, p<0.05). Additionally, this study showed that the ROS concentration was significantlydecreased in hearts of nNOS overexpressing mice compared to non-induced animals (6.14±0.685 vs. 14.53±1.7μM, n=8, p<0.01). Application of different inhibitors, Western Blot analysis and activity assays showed that the lower ROS concentration in nNOS overexpressing mice was caused by inhibition of the xanthine oxidoreductase (XOR) activity by the increased abundance of nNOS expression. In summary, this study demonstrated that the conditional transgenic overexpression of nNOS resulted in myocardial protection after ischemia-reperfusion injury. Besides reduction of myocardial Ca2+-overload after reperfusion this might be caused by inhibition of mitochondrial function through nNOS, which reduced myocardial oxygen consumption already under baseline conditions (Burkard N. conditionally accepted by KW - Herzhypertrophie KW - Signaltransduktion KW - Prävention KW - kardioprotektiv KW - Ischämie-Reperfusion KW - nNOS KW - cardioprotection KW - ischemia-reperfusion KW - nNOS Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-51832 ER - TY - THES A1 - Kehlenbrink, Sylvia T1 - Inhibiting Gluconeogenesis (GNG) Prevents the Effects of Free Fatty Acids (FFA) on Hepatic Glucose Effectiveness (GE) T1 - Die Inhibierung der Glukoneogenese verhindert die Beeinträchtigung freier Fettsäuren auf die hepatische Glukoseeffektivität N2 - Free fatty acids (FFA) modulate the effectiveness of glucose to suppress endogenous glucose production (EGP), and increased FFA levels contribute importantly to the loss of glucose effectiveness in type 2 diabetes mellitus (T2DM). Elevating FFA levels in nondiabetic (ND) subjects for at least 6h both increases gluconeogenesis (GNG) and impairs glucose effectiveness. Therefore, we wished to define the extent to which an increase in GNG is responsible for the loss of glucose effectiveness and whether EGP can be inhibited in the presence of elevated plasma FFA by inhibiting GNG with ethanol. To determine the effect of inhibiting GNG on glucose effectiveness, EGP ([3-3H]-glucose) was measured during three separate 7h normoglycemic/hyperglycemic pancreatic clamp studies (somatostatin; basal glucagon/GH/insulin replacement) in n=7 ND subjects (1F/6M; age=45±5 yr; BMI=27.6±3.0 kg/m2). Following an initial 210 min interval of euglycemia (5 mmol/l), blood glucose levels were raised to hyperglycemic levels (10 mmol/l) from t=210-420 min. The first pancreatic clamp study was a baseline study with saline infusions (Lip-/Et-). Lipid emulsion (Liposyn 20%) was infused throughout the second and third study types (Lip+ and Lip+/Et+) to increase FFA to T2DM levels (~ 500 mmol/l). In addition to Liposyn, ethanol (Et) was infused during hyperglycemia in the third study type (Lip+/Et+), using a pharmacokinetic algorithm to attain GNG-inhibiting ethanol levels of 80 mg/dl within 20 min. Under baseline conditions, hyperglycemia suppressed EGP by 61%. After raising plasma FFA to T2DM levels, suppression of EGP by hyperglycemia was impaired in Lip+ (34% decrease). During the Lip+/Et+ co-infusion studies the infusion of ethanol enhanced suppression of EGP by hyperglycemia (65.8% decrease, P=0.004 vs. Lip+) and thus restored glucose effectiveness (P=0.6 vs. Lip-/Et-). Thus, our results confirm the striking effects of elevated plasma FFA to impair glucose effectiveness and suggest that increased GNG contributes importantly to this loss of regulation. Inhibiting GNG could be an effective means of lowering EGP and improving glucose effectiveness in T2DM. N2 - Freie Fettsäuren (FFA) modulieren die Fähigkeit von Glukose die endogene Glukoseproduktion (EGP) zu unterdrücken und spielen eine wichtige Rolle bei dem Verlust der Glukoseeffektivität bei Typ-2-Diabetes mellitus (T2DM). Die Erhöhung freier Fettsäuren in Nicht-Diabetikern (ND) für mindestens 6 Stunden steigert die Glukoneogenese (GNG) und beeinträchtigt die Glukoseeffektivität. Ziel dieser Studien war es daher zu erkennen inwiefern die GNG für den Verlust der Glukoseeffektivität verantwortlich ist und ob die EGP in der Gegenwart von erhöhten FFA, durch die Inhibierung der GNG mit Ethanol, gehemmt werden kann. Um die Auswirkung der Hemmung der GNG auf die Glukoseeffektivität zu bestimmen haben wir die EGP ([3-3H]-glucose) während drei verschiedener normoglykämischen/ hyperglykämischen ‘Pancreatic Clamp’ Studien (Infusion von Somatostatin; Ersetzung basaler Konzentrationen von Glukagon, GH, und Insulin) von jeweils 7 Stunden Dauer in n=7 ND Probanden (1W/6M; Alter=45±5 Jahre; BMI=27.6±3.0 kg/m2) gemessen. Nach einer initialen Phase der Euglykämie (Blutglukosekonzentration bei 5 mmol/l; t=0-210 Minuten) wurde für den Zeitintervall t=210-420 Minuten die Blutglukosekonzentration auf 10 mmol/l erhöht. Die erste ‘Pancreatic Clamp’ Studie war eine Kontrollstudie mit Infusion einer NaCl-Lösung (Lip-/Et-). Eine Lipidemulsion (Liposyn 20%) wurde während der zweiten und dritten Studie (Lip+ und Lip+/Et-) infundiert, um die FFA Plasmaspiegel auf Konzentrationen zu erhöhen, die charakteristisch für den T2DM sind (~ 500 mmol/l). In Ergänzung zu Liposyn wurde Ethanol (Et) während der hyperglykämischen Phase der dritten Studie (Lip+/Et+) zugeführt. Mittels eines pharmakokinetischen Algorithmus wurden innerhalb von 20 Minuten Ethanolwerte erreicht die die GNG hemmen (~80 mg/dl). In den Kontrollstudien verminderte sich die EGP um 61% mit Einsetzen der Hyperglykämie. Nach Infusion von Liposyn in den Lip+ Studien verminderte sich die EGP in Folge der Hyperglykämie jedoch nur um 34%. Die GNG wurde rasch durch die Infusion von Ethanol in den Lip+/Et+ Studien gehemmt und verbesserte signifikant die hyperglykämie-induzierte Suppression der EGP (65% Verminderung der EGP, P=0.004 vs. Lip+). Dadurch wurde die normale Glukoseeffektivität wiederhergestellt (P=0.6 vs. Lip-/Et-). Diese Ergebnisse bestätigen die markante Rolle erhöhter Plasma FFA-Spiegel für die Beeinträchtigung der Glukoseeffektivität und deuten auf die Zentrale Rolle der GNG für den Verlust dieser Regulierung hin. Die Inhibierung der GNG könnte eine effektive Maßnahme sein, die EGP bei T2DM zu vermindern und die Glukoseeffektivität wiederherzustellen. KW - Gluconeogenese KW - Freie Fettsäuren KW - Diabetes mellitus KW - Glukoseeffektivität KW - Gluconeogenesis KW - free fatty acids KW - type 2 diabetes mellitus KW - glucose effectiveness Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48389 ER - TY - THES A1 - Padmapriya, Ponnuswamy T1 - Insight into oxidative stress mediated by nitric oxide synthase (NOS) isoforms in atherosclerosis N2 - The principle product of each NOS is nitric oxide. However, under conditions of substrate and cofactor deficiency the enzymes directly catalyze superoxide formation. Considering this alternative chemistry of each NOS, the effects of each single enzyme on key events of atherosclerosis are difficult to predict. Here, we evaluate nitric oxide and superoxide production by all three NOS isoforms in atherosclerosis. ESR measurements of circulating and vascular wall nitric oxide production showed significantly reduced nitric oxide levels in apoE/eNOS double knockout (dko) and apoE/iNOS dko animals but not in apoE/nNOS dko animals suggesting that eNOS and iNOS majorly contribute to vascular nitric oxide production in atherosclerosis. Pharmacological inhibition and genetic deletion of eNOS and iNOS reduced vascular superoxide production suggesting that eNOS and iNOS are uncoupled in atherosclerotic vessels. Though genetic deletion of nNOS did not alter superoxide production, acute inhibition of nNOS showed that nNOS contributes significantly to superoxide production. In conclusion, uncoupling of eNOS occurs in apoE ko atherosclerosis but eNOS mediated superoxide production does not outweigh the protective effects of eNOS mediated nitric oxide production. We show that although nNOS is not a major contributor of the vascular nitric oxide formation, it prevents atherosclerosis development. Acute inhibition of nNOS showed a significant reduction of superoxide formation suggesting that nNOS is uncoupled. The exact mechanism of action of nNOS in atheroprotection is yet to be elucidated. Genetic deletion of iNOS reduced NADPH oxidase activity. Thus, iNOS has both direct and indirect proatherosclerotic effects, as it directly generates both nitric oxide and superoxide simultaneously resulting in peroxynitrite formation and indirectly modulates NADPH oxidase activity. We hypothesize that eNOS is coupled in the disease free regions of the vessel and contributes to nitric oxide generation whereas in the diseased region of the vessel it is uncoupled to produce superoxide (Figure 16). nNOS expressed in the smooth muscle cells of the plaque contributes to the local superoxide generation. iNOS expressed in smooth muscle cells and leukocytes of the plaque generates superoxide and nitric oxide simultaneously to produce the strong oxidant peroxynitrite. N2 - Stickstoffmonoxid (NO) ist das prinzipielle Produkt aller Stickstoffmonoxid-Synthasen (NOS). Im Falle eines Mangels an Substrat (L-arginin) und Kofaktoren (Tetrahydrobiopterin, BH4) katalysieren die NOS-Enzyme direkt Superoxid (O2-). Diese Veränderung in der Radikalproduktion wird auch als Entkopplung der NOS bezeichnet. Die alternative Produktion von NO oder O2- durch die NOS bedingen, dass eine Voraussage über die Schlüsselfunktion der einzelnen Enzyme in der Entstehung der Atherosklerose schwierig ist. In unserer Studie evaluieren wir die Produktion von NO sowie O2- in atherosklerotischen Läsionen von apoE ko Mäusen und apoE/NOS doppel knockout (dko) Mäusen denen jeweils eine NOS-Isoform fehlt. Elektronen Spin Resonanz (ESR) Messungen konnten eine signifikante Reduktion sowohl des zirkulierenden, als auch der Gefäßwand eigenen Produktion von NO in apoE/eNOS dko und apoE/iNOS dko Mäusen zeigen, nicht jedoch in apoE/nNOS dko Mäusen. Dies lässt darauf schließen, dass eNOS und iNOS den hauptsächlichen Anteil der vaskulären NO-Produktion in atherosklerotischen Läsionen bewerkstelligen. Die pharmakologische Inhibierung wie auch die genetische Deletion von eNOS und iNOS führten ebenfalls zu einer reduzierten vaskulären O2- produktion, was die partielle Entkopplung beider Enzyme in atherosklerotisch veränderten Gefäßen nahe legt. Obwohl die chronische genetische Deletion von nNOS in apoE/nNOS dko die O2- Produktion nicht verändert, zeigte sich bei der akuten pharmakologischen Inhibierung von nNOS (durch L-NAANG) eine maßgebliche Beteiligung von nNOS an der O2- produktion in apoE ko Mäusen. Schlussfolgernd lässt sich sagen, dass in atherosklerotischen Gefäßen von apoE ko Tieren eine Entkopplung von eNOS statt findet, diese jedoch zu keinem Ausgleich der protektiven Effekte der eNOS vermittelten NO-Produktion führt. Unsere Ergebnisse in apoE/nNOS dko Mäusen zeigen eine atheroprotektive Rolle der nNOS, die sich nicht allein durch eine lokale, vaskuläre NO-Produktion durch das Enzym erklären lässt. Wir postulieren weitere systemisch atheroprotektive Eigenschaften der nNOS. Die signifikante Reduktion der Superoxidproduktion durch eine akute Inhibierung der nNOS weist auf eine Entkopplung der nNOS hin. Der exakte Wirkungsmechansimus von nNOS in der Atheroskleroseprävention ist weiterhin noch zu eruieren. Die genetische Deletion von iNOS führt zu einer reduzierten Aktivität der NADPH-Oxidase. Demnach sind für iNOS direkte sowie indirekte atherosklerosefördernde Effekte anzunehmen, da sie auf direktem Wege gleichzeitig NO und O2- produziert, was in einer Peroxynitritbildung resultiert. Wir stellen die Hypothese auf, dass eNOS in den läsionsfreien Gefäßregionen gekoppelt ist und dort seine atheroprotektiven Effekte durch die NO-Produktion vermittelt, während die eNOS in atherosklerotischen Läsionen entkoppelt vorliegt und hier O2- produziert (Fig. 16). iNOS, welches vor allem in den Plaques, in glatten Muskelzellen und Leukozyten zu finden ist, produziert gleichzeitig hohe Konzentrationen von O2- und NO, die als gemeinsames Endprodukt das stark oxidierende Peroxynitrit ergeben und die von uns dokumentierte proatherosklerotische Wirkung der iNOS vermittelt. KW - atherosclerosis KW - oxidative stress KW - Nitric oxide synthase KW - Atherosklerose KW - Stickstoffmonoxid Synthase KW - atherosclerosis KW - oxidative stress KW - Nitric oxide synthase Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30659 ER -