81 research outputs found

    The Bologna agreement is not suitable for medical education : a German view

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    Central elements of the Bologna declaration have been implemented in a huge variety of curricula in humanities, social sciences, natural sciences and engineering sciences at German universities. Overall the results have been nothing less than disastrous. Surprisingly, this seems to be the perfect time for German universities to talk about introducing a curriculum that is fully compatible with the Bologna declaration for medical education as well. However, German medical education does not have problems the Bologna declaration is intended to solve, such as quality, mobility, internationalization and employability. It is already in the Post-Bologna age

    Sphingosine 1-phosphate in renal diseases

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    Because of its highly bioactive properties sphingosine 1-phosphate (S1P) is an attractive target for the treatment of several diseases. Since the expression of sphingosine kinases as well as S1P receptors was demonstrated in the kidney, questions about the physiological and pathophysiological functions of S1P in this organ have been raised. In this review, we summarize the current state of knowledge about S1P-mediated functions in the kidney. A special focus is put on S1P modulated signal transduction in renal glomerular and tubular cells and consequences for the development and treatment of several kidney diseases, diabetic nephropathy, glomerulonephritis, ischemia-reperfusion injury, as well as for Wilms tumor progression

    Molecular mechanisms of IL-18BP regulation in DLD-1 cells: pivotal direct action of the STAT1/GAS axis on the promoter level

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    Interleukin (IL)-18, formerly known as interferon (IFN)-γ-inducing factor, is a crucial mediator of host defence and inflammation. Control of IL-18 bioactivity by its endogenous antagonist IL-18 binding protein (IL-18BP) is a major objective of immunoregulation. IL-18BP is strongly up-regulated by IFN-γ, thereby establishing a negative feedback mechanism detectable in cell culture and in vivo. Here we sought to investigate in D.L. Dexter (DLD) colon carcinoma cells molecular mechanisms of IL-18BP induction under the influence of IFN-γ. Mutational analysis revealed that a proximal γ-activated sequence (GAS) at the IL-18BP promoter is of pivotal importance for expression by IFN-γ-activated cells. Use of siRNA underscored the essential role of the signal transducer and activator of transcription (STAT)-1 in this process. Indeed, electrophoretic mobility shift assay and chromatin immunoprecipitation analysis proved STAT1 binding to this particular GAS site. Maximal expression of IL-18BP was dependent on de novo protein synthesis but unaffected by silencing of interferon regulatory factor-1. Altogether, data presented herein indicate that direct action of STAT1 on the IL-18BP promoter at the proximal GAS element is key to IL-18BP expression by IFN-γ-stimulated DLD-1 colon carcinoma cells

    RNA-dependent association with myosin IIA promotes F-actin-guided trafficking of the ELAV-like protein HuR to polysomes

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    The role of the mRNA-binding protein human antigen R (HuR) in stabilization and translation of AU-rich elements (ARE) containing mRNAs is well established. However, the trafficking of HuR and bound mRNA cargo, which comprises a fundamental requirement for the aforementioned HuR functions is only poorly understood. By administering different cytoskeletal inhibitors, we found that the protein kinase Cδ (PKCδ)-triggered accumulation of cytoplasmic HuR by Angiotensin II (AngII) is an actin-myosin driven process functionally relevant for stabilization of ARE-bearing mRNAs. Furthermore, we show that the AngII-induced recruitment of HuR and its bound mRNA from ribonucleoprotein particles to free and cytoskeleton bound polysomes strongly depended on an intact actomyosin cytoskeleton. In addition, HuR allocation to free and cytoskeletal bound polysomes is highly sensitive toward RNase and PPtase and structurally depends on serine 318 (S318) located within the C-terminal RNA recognition motif (RRM3). Conversely, the trafficking of the phosphomimetic HuRS318D, mimicking HuR phosphorylation at S318 by the PKCδ remained PPtase resistant. Co-immunoprecipitation experiments with truncated HuR proteins revealed that the stimulus-induced association of HuR with myosin IIA is strictly RNA dependent and mediated via the RRM3. Our data implicate a microfilament dependent transport of HuR, which is relevant for stimulus-induced targeting of ARE-bearing mRNAs from translational inactive ribonucleoprotein particles to polysomes

    No influence of dabigatran anticoagulation on hemorrhagic transformation in an experimental model of ischemic stroke

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    Background: Dabigatran etexilate (DE) is a new oral direct thrombin inhibitor. Clinical trials point towards a favourable risk-to-benefit profile of DE compared to warfarin. In this study, we evaluated whether hemorrhagic transformation (HT) occurs after experimental stroke under DE treatment as we have shown for warfarin. Methods: 44 male C57BL/6 mice were pretreated orally with 37.5 mg/kg DE, 75 mg/kg DE or saline and diluted thrombin time (dTT) and DE plasma concentrations were monitored. Ischemic stroke was induced by transient middle cerebral artery occlusion (tMCAO) for 1 h or 3 h. We assessed functional outcome and HT blood volume 24 h and 72 h after tMCAO. Results: After 1 h tMCAO, HT blood volume did not differ significantly between mice pretreated with DE 37.5 mg/kg and controls (1.5±0.5 µl vs. 1.8±0.5 µl, p>0.05). After 3 h tMCAO, DE-anticoagulated mice did also not show an increase in HT, neither at the dose of 37.5 mg/kg equivalent to anticoagulant treatment in the therapeutic range (1.3±0.9 µl vs. control 2.3±0.5 µl, p>0.05) nor at 75 mg/kg, clearly representing supratherapeutic anticoagulation (1.8±0.8 µl, p>0.05). Furthermore, no significant increase in HT under continued anticoagulation with DE 75 mg/kg could be found at 72 h after tMCAO for 1 h (1.7±0.9 µl vs. control 1.6±0.4 µl, p>0.05). Conclusion: Our experimental data suggest that DE does not significantly increase hemorrhagic transformation after transient focal cerebral ischemia in mice. From a translational viewpoint, this indicates that a continuation of DE anticoagulation in case of an ischemic stroke might be safe, but clearly, clinical data on this question are warranted

    FTY720 treatment in the convalescence period improves functional recovery and reduces reactive astrogliosis in photothrombotic stroke

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    Background: The Sphingosine-1-phosphate (S1P) signaling pathway is known to influence pathophysiological processes within the brain and the synthetic S1P analog FTY720 has been shown to provide neuroprotection in experimental models of acute stroke. However, the effects of a manipulation of S1P signaling at later time points after experimental stroke have not yet been investigated. We examined whether a relatively late initiation of a FTY720 treatment has a positive effect on long-term neurological outcome with a focus on reactive astrogliosis, synapses and neurotrophic factors. Methods: We induced photothrombotic stroke (PT) in adult C57BL/6J mice and allowed them to recover for three days. Starting on post-stroke day 3, mice were treated with FTY720 (1 mg/kg b.i.d.) for 5 days. Behavioral outcome was observed until day 31 after photothrombosis and periinfarct cortical tissue was analyzed using tandem mass-spectrometry, TaqMan®analysis and immunofluorescence. Results: FTY720 treatment results in a significantly better functional outcome persisting up to day 31 after PT. This is accompanied by a significant decrease in reactive astrogliosis and larger post-synaptic densities as well as changes in the expression of vascular endothelial growth factor α (VEGF α). Within the periinfarct cortex, S1P is significantly increased compared to healthy brain tissue. Conclusion: Besides its known neuroprotective effects in the acute phase of experimental stroke, the initiation of FTY720 treatment in the convalescence period has a positive impact on long-term functional outcome, probably mediated through reduced astrogliosis, a modulation in synaptic morphology and an increased expression of neurotrophic factors