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Platelet Aggregation

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https://www.readbyqxmd.com/read/28727479/extracellular-chloride-is-required-for-efficient-platelet-aggregation
#1
Kirk A Taylor, Darren G S Wilson, Matthew T Harper, Nicholas Pugh
Anion channels perform a diverse range of functions and have been implicated in ATP release, volume regulation, and phosphatidylserine exposure. Platelets have been shown to express several anion channels but their function is incompletely understood. Due to a paucity of specific pharmacological blockers, we investigated the effect of extracellular chloride substitution on platelet activation using aggregometry and flow cytometry. In the absence of extracellular chloride, we observed a modest reduction of the maximum aggregation response to thrombin or collagen-related peptide...
July 20, 2017: Platelets
https://www.readbyqxmd.com/read/28726976/absence-of-transforming-growth-factor-beta-1-in-murine-platelets-reduces-neointima-formation-without-affecting-arterial-thrombosis
#2
Katrin Schaefer, Eva Schütz, Magdalena L Bochenek, Dennis R Riehl, Markus Bosmann, Thomas Münzel, Stavros Konstantinides, Katrin Schäfer
Platelet degranulation at the site of vascular injury prevents bleeding and may affect the chronic vascular wound healing response. Transforming Growth Factor (TGF)-β1 is a major component of platelet α-granules known to accumulating in thrombi. It was our aim to determine the role of TGFβ1 released from activated platelets for neointima formation following arterial injury and thrombosis. Mice with platelet-specific deletion of TGFβ1 (Plt.TGFβ-KO) underwent carotid artery injury. Immunoassays confirmed the absence of active TGFβ1 in platelet releasates and plasma of Plt...
July 20, 2017: Thrombosis and Haemostasis
https://www.readbyqxmd.com/read/28726538/marked-bleeding-diathesis-in-patients-with-platelet-dysfunction-due-to-a-novel-mutation-in-rasgrp2-encoding-caldag-gefi-p-gly305asp
#3
Emilse Bermejo, Maria F Alberto, David S Paul, Aaron A Cook, Paquita Nurden, Analia Sanchez Luceros, Alan T Nurden, Wolfgang Bergmeier
Congenital platelet function disorders are often the result of defects in critical signal transduction pathways required for platelet adhesion and clot formation. Mutations affecting RASGRP2, the gene encoding the Rap GTPase activator, CalDAG-GEFI, give rise to a novel, and rare, group of platelet signal transduction abnormalities. We here report platelet function studies for two brothers (P1 and P2) expressing a novel variant of RASGRP2, CalDAG-GEFI(p.Gly305Asp). P1 and P2 have a lifelong history of bleeding with severe epistaxis successfully treated with platelet transfusions or rFVIIa...
July 20, 2017: Platelets
https://www.readbyqxmd.com/read/28720200/influence-of-erythrocyte-aggregation-on-radial-migration-of-platelet-sized-spherical-particles-in-shear-flow
#4
Cyrille Guilbert, Boris Chayer, Louise Allard, François T H Yu, Guy Cloutier
Blood platelets when activated are involved in the mechanisms of hemostasis and thrombosis, and their migration toward injured vascular endothelium necessitates interaction with red blood cells (RBCs). Rheology co-factors such as a high hematocrit and a high shear rate are known to promote platelet mass transport toward the vessel wall. Hemodynamic conditions promoting RBC aggregation may also favor platelet migration, particularly in the venous system at low shear rates. The aim of this study was to confirm experimentally the impact of RBC aggregation on platelet-sized micro particle migration in a Couette flow apparatus...
July 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28717586/evaluating-platelet-aggregation-dynamics-from-laser-speckle-fluctuations
#5
Zeinab Hajjarian, Diane M Tshikudi, Seemantini K Nadkarni
Platelets are key to maintaining hemostasis and impaired platelet aggregation could lead to hemorrhage or thrombosis. We report a new approach that exploits laser speckle intensity fluctuations, emanated from a drop of platelet-rich-plasma (PRP), to profile aggregation. Speckle fluctuation rate is quantified by the speckle intensity autocorrelation, g2(t), from which the aggregate size is deduced. We first apply this approach to evaluate polystyrene bead aggregation, triggered by salt. Next, we assess dose-dependent platelet aggregation and inhibition in human PRP spiked with adenosine diphosphate and clopidogrel...
July 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28717253/prostacyclin-reverses-platelet-stress-fibre-formation-causing-platelet-aggregate-instability
#6
M Z Yusuf, Z Raslan, L Atkinson, A Aburima, S G Thomas, K M Naseem, S D J Calaminus
Prostacyclin (PGI2) modulates platelet activation to regulate haemostasis. Evidence has emerged to suggest that thrombi are dynamic structures with distinct areas of differing platelet activation. It was hypothesised that PGI2 could reverse platelet spreading by actin cytoskeletal modulation, leading to reduced capability of platelet aggregates to withstand a high shear environment. Our data demonstrates that post-flow of PGI2 over activated and spread platelets on fibrinogen, identified a significant reduction in platelet surface area under high shear...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28717145/acetylsalicylic-acid-differentially-limits-the-activation-and-expression-of-cell-death-markers-in-human-platelets-exposed-to-staphylococcus-aureus-strains
#7
Adrien Chabert, Pauline Damien, Paul O Verhoeven, Florence Grattard, Philippe Berthelot, Fabrice Zeni, Laurence Panicot-Dubois, Stéphane Robert, Françoise Dignat-George, Marie-Ange Eyraud, Bruno Pozzetto, Bernard Payrastre, Fabrice Cognasse, Olivier Garraud, Hind Hamzeh-Cognasse
Beyond their hemostatic functions, platelets alter their inflammatory response according to the bacterial stimulus. Staphylococcus aureus is associated with exacerbated inflammation and thrombocytopenia, which is associated with poor prognosis during sepsis. Acetylsalicylic acid and statins prevent platelet aggregation and decrease the mortality rate during sepsis. Therefore, we assessed whether these two molecules could reduce in vitro platelet activation and the inflammatory response to S. aureus. Platelets were exposed to clinical strains of S...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28717113/add-on-antiplatelet-effects-of-eicosapentaenoic-acid-with-tailored-dose-setting-in-patients-on-dual-antiplatelet-therapy
#8
Naoyoshi Hosogoe, Shuichi Ishikawa, Naoyuki Yokoyama, Ken Kozuma, Takaaki Isshiki
The aim of this study was to investigate the antiplatelet effects of eicosapentaenoic acid (EPA) at a sufficient dose following coronary stent implantation. Thirty-one patients on dual antiplatelet therapy with aspirin and clopidogrel were treated with highly purified EPA-E (Epadel(®)) for 12 weeks. Based on our previous study, patients with a high baseline EPA/arachidonic acid (AA) ratio (≥ 0.37; n = 11) were given a standard dose (1800 mg daily) of EPA-E, whereas those with a low EPA/AA ratio (< 0.37; n = 20) were given a high dose (2700 mg daily) to reach the target value of > 0...
July 14, 2017: International Heart Journal
https://www.readbyqxmd.com/read/28716800/relationship-between-vascular-resistance-and-sympathetic-nerve-fiber-density-in-arterial-vessels-in-children-with-sleep-disordered-breathing
#9
Anna Kontos, Kurt Lushington, James Martin, Quenten Schwarz, Ryan Green, David Wabnitz, Xiangjun Xu, Elke M Sokoya, Scott Willoughby, Mathias Baumert, Antonio Ferrante, Melissa La Forgia, Declan Kennedy
BACKGROUND: Sleep disordered breathing in children is associated with increased blood flow velocity and sympathetic overactivity. Sympathetic overactivity results in peripheral vasoconstriction and reduced systemic vascular compliance, which increases blood flow velocity during systole. Augmented blood flow velocity is recognized to promote vascular remodeling. Importantly, increased vascular sympathetic nerve fiber density and innervation in early life plays a key role in the development of early-onset hypertension in animal models...
July 17, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28715503/effects-of-preoperative-aspirin-on-perioperative-platelet-activation-and-dysfunction-in-patients-undergoing-off-pump-coronary-artery-bypass-graft-surgery-a-prospective-randomized-study
#10
Jiwon Lee, Chul-Woo Jung, Yunseok Jeon, Tae Kyong Kim, Youn Joung Cho, Chang-Hoon Koo, Yoon Hyeong Choi, Ki-Bong Kim, Ho Young Hwang, Hang-Rae Kim, Ji-Young Park
The benefit of aspirin use after coronary artery bypass graft surgery has been well proven. However, the effect of preoperative aspirin use in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB) has not been evaluated sufficiently. To evaluate platelet function changes during OPCAB due to preoperative aspirin use, we conducted a randomized controlled trial using flow cytometry and the Multiplate® analyzer. Forty-eight patients scheduled for elective OPCAB were randomized to the aspirin continuation (100 mg/day until operative day) and discontinuation (4 days before the operative day) groups...
2017: PloS One
https://www.readbyqxmd.com/read/28715386/live-cell-imaging-of-platelet-degranulation-and-secretion-under-flow
#11
Arjan D Barendrecht, Johan J F Verhoef, Silvia Pignatelli, Gerard Pasterkamp, Harry F G Heijnen, Coen Maas
Blood platelets are essential players in hemostasis, the formation of thrombi to seal vascular breaches. They are also involved in thrombosis, the formation of thrombi that occlude the vasculature and injure organs, with life-threatening consequences. This motivates scientific research on platelet function and the development of methods to track cell-biological processes as they occur under flow conditions. A variety of flow models are available for the study of platelet adhesion and aggregation, two key phenomena in platelet biology...
July 10, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28714577/direct-laser-interference-patterning-of-cocr-alloy-surfaces-to-control-endothelial-cell-and-platelet-response-for-cardiovascular-applications
#12
Romain Schieber, Federico Lasserre, Michael Hans, Marc Fernández-Yagüe, Maribel Díaz-Ricart, Ginés Escolar, Maria-Pau Ginebra, Frank Mücklich, Marta Pegueroles
The main drawbacks of cardiovascular bare-metal stents (BMS) are in-stent restenosis and stent thrombosis as a result of an incomplete endothelialization after stent implantation. Nano- and microscale modification of implant surfaces is a strategy to recover the functionality of the artery by stimulating and guiding molecular and biological processes at the implant/tissue interface. In this study, cobalt-chromium (CoCr) alloy surfaces are modified via direct laser interference patterning (DLIP) in order to create linear patterning onto CoCr surfaces with different periodicities (≈3, 10, 20, and 32 µm) and depths (≈20 and 800 nm)...
July 17, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28713010/hemolectin-expression-reveals-functional-heterogeneity-in-honey-bee-apis-mellifera-hemocytes
#13
Erika Gábor, Gyöngyi Cinege, Gábor Csordás, Tibor Török, Katalin Folkl-Medzihradszky, Zsuzsanna Darula, István Andó, Éva Kurucz
The identification of molecular markers considerably facilitated the classification and functional analysis of blood cell types. Apis mellifera hemocytes have been classified by morphological criteria and lectin binding properties; however, the use of molecular markers has been minimal. Here we describe a monoclonal antibody to a non-phagocytic subpopulation of A. mellifera hemocytes and to a constituent of the hemolymph clot. We demonstrate that the antibody identifies the A. mellifera hemolectin, a protein carrying human von Willebrand factor homology domains, characteristic of proteins involved in blood coagulation and platelet aggregation in mammals...
July 13, 2017: Developmental and Comparative Immunology
https://www.readbyqxmd.com/read/28712586/platelet-testing-to-guide-aspirin-dose-adjustment-in-pediatric-patients-after-cardiac-surgery
#14
Sirisha Emani, David Zurakowski, Michelle Mulone, James A DiNardo, Cameron C Trenor, Sitaram M Emani
OBJECTIVES: Thrombosis is associated with increased morbidity and mortality in pediatric patients undergoing cardiac surgery. Although aspirin commonly is used for thromboprophylaxis, the utility of laboratory-based tests that assess aspirin efficacy have not been evaluated. We sought to determine the relationship between platelet aggregation testing and aspirin dose adjustment on thrombosis rates in this population. METHODS: Pediatric patients undergoing cardiac surgery who received aspirin and underwent platelet testing were studied retrospectively...
June 20, 2017: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28712479/antiplatelet-aggregation-activity-of-walnut-hull-extract-via-suppression-of-reactive-oxygen-species-generation-and-caspase-activation
#15
Azadeh Meshkini, Masoumeh Tahmasbi
Walnut hull (wal hull) is an agricultural by-product that is widely used in traditional medicine for alleviating pain and treating skin diseases, however, recently it has gained much attention in modern pharmacology due to its antioxidant properties. The current study was aimed to determine the total phenolic, flavonoid, and tannin content of Persian wal hull extract and evaluate its biological effects on platelet function. Experimental data showed that acetone extract of wal hulls has a high content of polyphenolic compounds and antioxidant properties...
June 2017: Journal of Acupuncture and Meridian Studies
https://www.readbyqxmd.com/read/28712405/-changes-of-monocyte-and-monocyte-platelet-aggregates-in-different-subgroups-of-thrombotic-events-in-patients-with-acute-myocardial-infarction-during-pci
#16
Sheng Wang, Cuifang Sun, Wang Liao, Zhongwei Wu, Yudai Wang, Xiuxian Huang, Sijia Lu, Xiaoli Dong, Fujie Shuai, Bin Li
Objective To investigate the impact of thrombotic events on the alterations of monocyte and monocyte-platelet aggregates (MPAs) in patients with acute myocardial infarction (AMI) during percutaneous coronary intervention (PCI). Methods Blood was collected before PCI for flow cytometry. Monocyte subsets and MPAs were detected by four-color platform (CDl4-APC, CDl6-PE-Cy7, CD86-PE and CD41-Alexa Fluor(R)488). According to the expression of the platelet surface marker CD41, the number of monocyte subsets and MPAs was analyzed using the fluorescent microspheres of absolute counting tube...
July 2017: Xi Bao Yu Fen Zi Mian Yi Xue za Zhi, Chinese Journal of Cellular and Molecular Immunology
https://www.readbyqxmd.com/read/28711718/phospholipase-d1-is-a-regulator-of-platelet-mediated-inflammation
#17
Meike Klier, Nina Sarah Gowert, Sven Jäckel, Christoph Reinhardt, Margitta Elvers
Glycoprotein (GP)Ib is not only required for stable thrombus formation but for platelet-mediated inflammatory responses. Phospholipase (PL)D1 is essential for GPIb-dependent aggregate formation under high shear conditions while nothing is known about PLD1-induced regulation of GPIb in platelet-mediated inflammation and the underlying mechanisms. This study aimed to investigate the relevance of PLD1 for platelet-mediated endothelial and leukocyte recruitment and activation in vitro and in vivo. Pld1(-/-) platelets showed strongly reduced adhesion to TNFα stimulated endothelial cells (ECs) under high shear conditions ex vivo...
July 12, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28709878/differential-tbxa2-receptor-transcript-stability-is-dependent-on-the-c924t-polymorphism
#18
Vincenzo De Iuliis, Sebastiano Ursi, Alfonso Pennelli, Marika Caruso, Angela Nunziata, Antonio Marino, Vincenzo Flati, Francesco Cipollone, Maria Adele Giamberardino, Gianfranco Vitullo, Elena Toniato, Pio Conti, Stefano Martinotti
BACKGROUND: In order to better characterize the molecular mechanisms involved in processing mutated transcripts, we investigated the post-transcriptional role of the C924T polymorphism (rs4523) located in the 3' region of the TBXA2R gene. METHODS: and RESULTS: Experiments of dose response with Actinomycin D on MEG-01 human cell line showed a significant decrease on cell viability that was more evident on cells treated for 24h. In addition, we showed that treatments with 5-10μM, 15μM and 20μM of actinomycin D reduced cell viability by 44%, 72% and 75%, respectively, compared to the control group...
July 11, 2017: Prostaglandins & Other Lipid Mediators
https://www.readbyqxmd.com/read/28709700/prasugrel-as-opposed-to-clopidogrel-improves-endothelial-nitric-oxide-bioavailability-and-reduces-platelet-leukocyte-interaction-in-patients-with-unstable-angina-pectoris-a-randomized-controlled-trial
#19
Tanja K Rudolph, Alexander Fuchs, Anna Klinke, Andrea Schlichting, Kai Friedrichs, Martin Hellmich, Martin Mollenhauer, Edzard Schwedhelm, Stephan Baldus, Volker Rudolph
BACKGROUND: Platelet inhibition has been linked to improved endothelial function, a prognostic factor in coronary artery disease. Whether prasugrel, a potent platelet inhibitor, affects endothelial function remains unknown. METHODS: This was a double-blind, randomized, active-controlled, parallel trial. Patients with unstable angina pectoris undergoing percutaneous coronary intervention (PCI) received either a daily dose of clopidogrel 75mg (n=23) or prasugrel 10mg (n=22)...
July 1, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28708713/platelet-aggregation-in-direct-oral-factor-xa-inhibitors-treated-patients-with-atrial-fibrillation-a-pilot-study
#20
Peter Bánovčin, Ingrid Škorňová, Matej Samoš, Martin Schnierer, Tomáš Bolek, František Kovář, Ján Staško, Peter Kubisz, Marián Mokáň
BACKGROUND: Activated factor X (factor Xa) plays an important role in regulation of platelets. The aim of this study was to test the effect of direct oral factor Xa inhibitors - rivaroxaban and apixaban - on platelet aggregation in patients with non-valvular atrial fibrillation (NV-AF). PATIENTS AND METHODS: This single-centre pilot study enrolled 21 factor Xa inhibitors-treated (9 rivaroxaban-treated and 12 apixaban-treated) patients with NV-AF. The trough and peak samples of these patients were tested for adenosinediphosphate-induced (ADP), epinephrine-induced, and collagen-induced platelet aggregation with light transmission aggregometry (LTA), and with factor Xa-calibrated anti-Xa chromogenic analysis...
July 13, 2017: Journal of Cardiovascular Pharmacology
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