Universitatsklinikum Eppendorf

Hamburg, Germany

Universitatsklinikum Eppendorf

Hamburg, Germany
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Lavialle M.,French National Institute for Agricultural Research | Aumann G.,TU Dresden | Anlauf E.,TU Dresden | Prols F.,Universitatsklinikum Eppendorf | And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011

The peripheral astrocyte process (PAP) preferentially associates with the synapse. The PAP, which is not found around every synapse, extends to or withdraws from it in an activity-dependent manner. Although the pre- and postsynaptic elements have been described in great molecular detail, relatively little is known about the PAP because of its difficult access for electrophysiology or light microscopy, as they are smaller than microscopic resolution. We investigated possible stimuli and mechanisms of PAP plasticity. Immunocytochemistry on rat brain sections demonstrates that the actin-binding protein ezrin and the metabotropic glutamate receptors (mGluRs) 3 and 5 are compartmentalized to the PAP but not to the GFAP-containing stem process. Further experiments applying ezrin siRNA or dominant-negative ezrin in primary astrocytes indicate that filopodia formation and motility require ezrin in the membrane/cytoskeleton bound (i.e., T567-phosphorylated) form. Glial processes around synapses in situ consistently display this ezrin form. Possible motility stimuli of perisynaptic glial processes were studied in culture, based on their similarity with filopodia. Glutamate and glutamate analogues reveal that rapid (5 min), glutamate-induced filopodia motility is mediated by mGluRs 3 and 5. Ultrastructurally, these mGluR subtypes were also localized in astrocytes in the rat hippocampus, preferentially in their fine PAPs. In vivo, changes in glutamatergic circadian activity in the hamster suprachiasmatic nucleus are accompanied by changes of ezrin immunoreactivity in the suprachiasmatic nucleus, in line with transmitter-induced perisynaptic glial motility. The data suggest that (i) ezrin is required for the structural plasticity of PAPs and (ii) mGluRs can stimulate PAP plasticity.

Muth K.N.,Friedrich - Alexander - University, Erlangen - Nuremberg | Piefke S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Weider M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Sock E.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 3 more authors.
GLIA | Year: 2016

Differentiation of oligodendrocytes and myelin production in the vertebrate central nervous system require highly concerted changes in gene expression. The transcription factors Sox10 and Myrf are both central to this process and jointly regulate expression of myelin genes. Here we show that Sox10 and Myrf also cooperate in the activation of the gene coding for the dual specificity protein phosphatase Dusp15 (also known as VHY) during this process. Activation is mediated by the Dusp15 promoter, which is also sufficient to drive oligodendroglial gene expression in vivo. It contains both a functional Sox10 and a functional Myrf binding site. Whereas Sox10 binds as a monomer, Myrf binds as a trimer. Available data furthermore indicate that cooperative activation is not a function of facilitated binding, but occurs at a later step of the activation process. shRNA-mediated knockdown of Dusp15 reduced expression of early and late differentiation markers in CG4 and primary oligodendroglial cells, whereas Dusp15 overexpression increased it transiently. This argues that Dusp15 is not only a joint target of Sox10 and Myrf in oligodendrocytes but may also mediate some of their effects during oligodendrocyte differentiation and myelin formation. GLIA 2016;64:2120–2132. © 2016 Wiley Periodicals, Inc.

Hornig J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Frob F.,Friedrich - Alexander - University, Erlangen - Nuremberg | Vogl M.R.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hermans-Borgmeyer I.,Universitatsklinikum Eppendorf | And 2 more authors.
PLoS Genetics | Year: 2013

Myelin is essential for rapid saltatory conduction and is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. In both cell types the transcription factor Sox10 is an essential component of the myelin-specific regulatory network. Here we identify Myrf as an oligodendrocyte-specific target of Sox10 and map a Sox10 responsive enhancer to an evolutionarily conserved element in intron 1 of the Myrf gene. Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes. This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination. Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented. © 2013 Hornig et al.

In order to identify requirements of quality assurance in this field, a general description of prevention, health promotion and education is outlined, based upon healthcare supply analyses and 158 interviews with experts. Prominent features are, among others, a distinctive heterogeneity and complexity of settings, suppliers, and interventions; supply of coverage is below public health criteria (needs); weak outcome evaluation; competition among suppliers, providers, and political agencies and decision makers; need for intra-and intersectoral coordination; the lack of evidence-based healthcare planning; and hurdles for quality assurance. A structural taxonomy of quality assurance systems is then developed, consisting of three dimensions: validity (quality of information), regularity, and degree of commitment and obligation. In terms of these dimensions, important systems of quality assurance in prevention, health promotion and education in Germany are analyzed. A number of different systems and approaches can be found. However, most of them share questionable validity, regularity, and degree of obligation. Increased commitment on behalf of providers, suppliers, and political institutions and decision makers for the quality of preventive interventions is inevitable in order to raise the performance of prevention and health promotion in Germany to their potential effectiveness. © Springer-Verlag 2011.

Cervero P.,Universitatsklinikum Eppendorf | Himmel M.,Universitatsklinikum Eppendorf | Kruger M.,Max Planck Institute for Heart and Lung Research | Linder S.,Universitatsklinikum Eppendorf
European Journal of Cell Biology | Year: 2012

Podosomes are multifunctional organelles of invasive cells that combine several key abilities, including adhesion, matrix degradation and mechanosensing. The necessary spatiotemporal fine-tuning of podosome structure, turnover and function implies the existence of an intricate network of proteins, comparable to other integrin-based adhesions. However, no systematic effort has yet been made to map the podosome proteome. Here, we describe the purification of podosome-enriched fractions from primary human macrophages, labelled with isotopically stable amino acids, and the subsequent mass spectrometric analysis of these fractions. We present a consensus list of 203 proteins, comprising 33 known podosome proteins and 170 potential novel components. We also present second-level analyses of the podosome proteome, as well as proof-of-principle experiments by showing that the newly identified components WDR1/AIP-1 and hnRNP-K localise to the core structure of macrophage podosomes. Comparisons with other adhesion structure proteomes confirm that the podosome proteome shares components with focal adhesions and invadopodia, but also reveal an extensive overlap with spreading initiation centres (SICs). We suggest that the consensus list comprises a significant part of the podosome proteome and will be helpful for future studies on podosome structure, composition and function, and also for detailed classification of adhesion structure subtypes. © 2012 Elsevier GmbH.

Lymphocyte depletion with antithymocyte globulin (ATG) can be complicated by systemic coagulation activation. We found that ATG activated tissue factor procoagulant activity (TF PCA) on monocytic cells more potently than other stimuli that decrypt TF, including cell disruption, TF pathway inhibitor inhibition, and calcium ionophore treatment. Induction of TF PCA by ATG was dependent on lipid raft integrity and complement activation. We showed that ATG-mediated TF activation required complement activation until assembly of the C5b-7 membrane insertion complex, but not lytic pore formation by the membrane attack complex C5b-9. Consistently, induction of TF PCA by ATG did not require maximal phosphatidylserine membrane exposure and was not correlated with the magnitude of complement-induced lytic cell injury. Blockade of free thiols, an inhibitory monoclonal antibody to protein disulfide isomerase (PDI), and the small-molecule PDI antagonist quercetin-3-rutinoside prevented ATG-mediated TF activation, and C5 complement activation resulted in oxidation of cell surface PDI. This rapid and potent mechanism of cellular TF activation represents a novel connection between the complement system and cell surface PDI-mediated thiol-disulfide exchange. Delineation of this clinically relevant mechanism of activation of the extrinsic coagulation pathway during immunosuppressive therapy with ATG may have broader implications for vascular thrombosis associated with inflammatory disorders.

Stummer W.,University of Munster | Van Den Bent M.J.,Erasmus University Rotterdam | Westphal M.,Universitatsklinikum Eppendorf
Acta Neurochirurgica | Year: 2011

Background: This article discusses data from 3 randomized phase 3 trials, supporting a role for surgery in glioblastoma. Methods: Data were reviewed by extent of resection during primary surgery from the ALA-Glioma Study (fluorescence-guided versus conventional resection), the BCNU wafer study (BCNU wafer versus placebo), and the EORTC Study 26981-22981 (radiotherapy versus chemoradiotherapy with temozolomide). Results: For glioblastoma patients in the ALA study, median survival was 16.7 and 11.8 months for complete versus partial resection, respectively (P<0.0001). Survival effects were maintained after correction for differences in age and tumor location. For glioblastoma patients who received ≥90% resection in the BCNU wafer study, median survival increased for BCNU wafer versus placebo (14.5 versus 12.4 months, respectively; P=0.02), but no survival increase was found for <90% resection (11.7 versus 10.6 months, respectively; P=0.98). In the EORTC study, absolute median gain in survival with chemoradiotherapy versus radiotherapy was greatest for complete resections (+4.1 months; P=0.0001), compared with partial resections (+1.8 months; P=0.0001), or biopsies (+1.5 months; P=0.088), suggesting surgery enhanced adjuvant treatment. Conclusion: Complete resection appears to improve survival and may increase the efficacy of adjunct/adjuvant therapies. If safely achievable, complete resection should be the surgical goal for glioblastoma. © 2011 Springer-Verlag.

Langer F.,Universitatsklinikum Eppendorf | Ruf W.,Scripps Research Institute | Ruf W.,Universitatsmedizin Mainz
Thrombosis and Haemostasis | Year: 2014

Tissue factor (TF), the cellular receptor and cofactor for factor VII/VIIa, initiates haemostasis and thrombosis. Initial tissue distribution studies suggested that TF was sequestered from the circulation and only present at perivascular sites. However, there is now clear evidence that TF also exists as a blood-borne form with critical contributions not only to arterial thrombosis following plaque rupture and to venous thrombosis following endothelial perturbation, but also to various other clotting abnormalities associated with trauma, infection, or cancer. Because thrombin generation, fibrin deposition, and platelet aggregation in the contexts of haemostasis, thrombosis, and pathogen defence frequently occur without TF de novo synthesis, considerable efforts are still directed to understanding the molecular events underlying the conversion of predominantly non-coagulant or cryptic TF on the surface of haematopoietic cells to a highly procoagulant molecule following cellular injury or stimulation. This article will review some of the still controversial mechanisms implicated in cellular TF activation or decryption with particular focus on the coordinated effects of outer leaflet phosphatidylserine exposure and thiol-disulfide exchange pathways involving protein disulfide isomerase (PDI). In this regard, our recent findings of ATP-triggered stimulation of the purinergic P2X7 receptor on myeloid and smooth muscle cells resulting in potent TF activation and shedding of procoagulant microparticles as well as of rapid monocyte TF decryption following antithymocyte globulin-dependent membrane complement fixation have delineated specific PDIdependent pathways of cellular TF activation and thus illustrated additional and novel links in the coupling of inflammation and coagulation. © Schattauer 2014.

Wiesner. C.,Universitatsklinikum Eppendorf | El Azzouzi K.,Universitatsklinikum Eppendorf | Linder S.,Universitatsklinikum Eppendorf
Journal of Cell Science | Year: 2013

The matrix metalloproteinase MT1-MMP has a major impact on invasive cell migration in both physiological and pathological settings such as immune cell extravasation or metastasis of cancer cells. Surface-associated MT1-MMP is able to cleave components of the extracellular matrix, which is a prerequisite for proteolytic invasive migration. However, current knowledge on the molecular mechanisms that regulate MT1-MMP trafficking to and from the cell surface is limited. We have identified three members of the RabGTPase family, Rab5a, Rab8a and Rab14, as crucial regulators of MT1-MMP trafficking and function in primary human macrophages. Both overexpressed and endogenous forms show prominent colocalisation with MT1-MMP-positive vesicles, whereas expression of mutant constructs, as well as siRNA-induced knockdown, reveal that these RabGTPases are crucial in the regulation of MT1-MMP surface exposure, contact of MT1-MMP-positive vesicles with podosomes, extracellular matrix degradation in two and three dimensions, as well as three-dimensional proteolytic invasion of macrophages. Collectively, our results identify Rab5a, Rab8a and Rab14 as major regulators of MT1-MMP trafficking and invasive migration of primary human macrophages, which could be promising potential targets for manipulation of immune cell invasion. © 2013 Published by The Company of Biologists Ltd.

Hummel F.C.,Universitatsklinikum Eppendorf
Nervenarzt | Year: 2014

Modern neuroimaging techniques, such as structural and functional magnetic resonance imaging (MRI) and non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) are increasingly used in the neuroscientific research of neurological disorders, such as stroke, tinnitus and movement disorders. These methods offer a non-invasive approach and especially in combination, not only the opportunity to add to the pathophysiological understanding of these disorders but also to provide information about the functional recovery and the natural course of the disease in a predictive way. Based on such knowledge therapeutic approaches can be adapted in a patient-tailored fashion to achieve the best therapeutic effects. Furthermore, these methods might provide additional non-invasive information for neurosurgical interventions reducing perioperative interventional risks.In the present article these aspects will be discussed with a focus on the combination of MRI and TMS especially addressed for the topic of recovery from stroke. © Springer-Verlag Berlin Heidelberg 2014.

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