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Greifswald, Germany

Arman M.,University of Birmingham | Krauel K.,Universitatsmedizin Greifswald
Journal of Thrombosis and Haemostasis | Year: 2015

Beyond their prominent role in hemostasis and thrombosis, platelets are increasingly recognized as having immunologic functions. Supporting this, human platelets express FcγRIIA (CD32a), a low-affinity Fc receptor (FcR) for the constant region of IgG that recognizes immune complexes (ICs) and IgG-opsonized cells with high avidity. In leukocytes, FcγRIIA engagement initiates strong effector functions that are key for immune and inflammatory responses, including cytokine release, antibody-dependent cell-mediated killing of pathogens, and internalization of ICs. However, the physiologic relevance of platelet-expressed FcγRIIA has received little attention in previous reviews on FcRs. This article summarizes and discusses the available information on human platelet FcγRIIA. The importance of this receptor in heparin-induced thrombocytopenia, a prothrombotic adverse drug effect, is well documented. However, studies demonstrating platelet activation by IgG-opsonized bacteria point to the physiologic relevance of platelet FcγRIIA in immunity. In this context, platelet activation and secretion may facilitate both a direct antimicrobial function of platelets and crosstalk with other immune cells. Additionally, a role for platelet FcγRIIA in IgG-independent hemostasis and physiologic thrombosis, by means of amplifying integrin αIIbβ3 outside-in signaling, has also been proposed. Nonetheless, the thrombotic complications found in some infective and autoimmune diseases may result from unbalanced FcγRIIA-mediated platelet aggregation. Moreover, FcγRIIA is not expressed in mice, and thrombocytopenia and/or thrombotic events found after drug administration can only be recapitulated by the use of human FcγRIIA-transgenic mice. Altogether, the available data support a functional role for platelet FcγRIIA in health and disease, and emphasize the need for further investigation of this receptor. © 2015 International Society on Thrombosis and Haemostasis. Source

Greinacher A.,Universitatsmedizin Greifswald
New England Journal of Medicine | Year: 2015

A 64-year-old woman who is hospitalized with endocarditis and whose condition is clinically stable while she is receiving intravenous antibiotic agents has had a decrease in platelet count from 161,000 per cubic millimeter on day 7 of hospitalization to 60,000 per cubic millimeter on day 9. She has been receiving low-molecular-weight heparin at a dose of 40 mg per day since admission. How should her case be further evaluated and treated? Copyright © 2015 Massachusetts Medical Society. All rights reserved. Source

Greinacher A.,Universitatsmedizin Greifswald
Blood | Year: 2014

In this issue of Blood, Warkentin et al provide insight into certain rare but often catastrophic cases of thrombotic complications, termed "spontaneous" (or "autoimmune") heparin-induced thrombocytopenia (HIT). © 2014 by The American Society of Hematology. Source

Von Der Heyden M.,Universitatsmedizin Greifswald | Meissner K.,Universitatsmedizin Greifswald
Best Practice and Research: Clinical Anaesthesiology | Year: 2015

Emergency medicine has been a stronghold of simulation-based training ever since high-fidelity simulators became available. The preclinical setting differs remarkably from any in-hospital environment in both available technology and resources, and thus stress levels of the health-care professionals involved in patient care - ideal factors for the simulation-based teaching approach. This review reports on the current status of the method for teaching preclinical scenarios from an educational and practical perspective. Particular attention is given to contents, formats, and evaluation of success. © 2015 Published by Elsevier Ltd. Source

Freund M.,Universitatsmedizin Greifswald | Walther T.,University College Cork | Walther T.,University of Leipzig | Von Bohlen und Halbach O.,Universitatsmedizin Greifswald
European Neuropsychopharmacology | Year: 2014

Aside from the well-known biologically active angiotensin II, other biologically active angiotensins have been discovered, including angiotensin IV and angiotensin-(1-7). Some years ago, we and others discovered that the Mas proto-oncogene encodes a G protein-coupled receptor being essential for angiotensin-(1-7) signaling. Mas is not only expressed in the periphery but also within the brain, e.g. in the dentate gyrus (DG) and the piriform cortex (PC). Since the DG is capable of adult neurogenesis, we examined the impact of a deletion of Mas upon adult neurogenesis. Deletion of Mas did not alter cell proliferation in the adult DG (as monitored with phosphohistone H3) and did not alter cell death (as monitored with activated Caspase 3). However, Mas deficiency resulted in an increase in the number of doublecortin (DCX) positive cells, indicating that lack of Mas increases the number of this cell population. Concerning the PC, it is discussed whether adult neurogenesis occurs under physiological conditions in this area. We could demonstrate that Mas deficiency has an impact on cell division and on the population of DCX-positive cells within the PC. Since Mas is not expressed before birth within the brain, our data may suggest that adult hippocampal neurogenesis and neurogenesis occurring during prenatal development share several common mechanisms, but are, at least in part, differentially regulated. Moreover, since deficiency for Mas increases the numbers of DCX-positive young neurons, blockage of Mas might be beneficial in stimulating neurogenesis in adults. © 2013 Elsevier B.V. and ECNP. Source

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