Sample records for platelet thrombus formation

  1. Platelet size and density affect shear-induced thrombus formation in tortuous arterioles (United States)

    Chesnutt, Jennifer K. W.; Han, Hai-Chao


    Thrombosis accounts for 80% of deaths in patients with diabetes mellitus. Diabetic patients demonstrate tortuous microvessels and larger than normal platelets. Large platelets are associated with increased platelet activation and thrombosis, but the physical effects of large platelets in the microscale processes of thrombus formation are not clear. Therefore, the objective of this study was to determine the physical effects of mean platelet volume (MPV), mean platelet density (MPD) and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A computational model of the transport, shear-induced activation, collision, adhesion and aggregation of individual platelets was used to simulate platelet interactions and thrombus formation in tortuous arterioles. Our results showed that an increase in MPV resulted in a larger number of activated platelets, though MPD and level of tortuosity made little difference on platelet activation. Platelets with normal MPD yielded the lowest amount of mural thrombus. With platelets of normal MPD, the amount of mural thrombus decreased with increasing level of tortuosity but did not have a simple monotonic relationship with MPV. The physical mechanisms associated with MPV, MPD and arteriole tortuosity play important roles in platelet activation and thrombus formation.

  2. Effect of red blood cells on platelet activation and thrombus formation in tortuous arterioles

    Directory of Open Access Journals (Sweden)

    Jennifer K. W. Chesnutt


    Full Text Available Thrombosis is a major contributor to cardiovascular disease, which can lead to myocardial infarction and stroke. Thrombosis may form in tortuous microvessels, which are often seen throughout the human body, but the microscale mechanisms and processes are not well understood. In straight vessels, the presence of red blood cells (RBCs is known to push platelets toward walls, which may affect platelet aggregation and thrombus formation. However in tortuous vessels, the effects of RBC interactions with platelets in thrombosis are largely unknown. Accordingly, the objective of this work was to determine the physical effects of RBCs, platelet size, and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A discrete element computational model was used to simulate the transport, collision, adhesion, aggregation, and shear-induced platelet activation of hundreds of individual platelets and RBCs in thrombus formation in tortuous arterioles. Results showed that high shear stress near the inner sides of curved arteriole walls activated platelets to initiate thrombosis. RBCs initially promoted platelet activation, but then collisions of RBCs with mural thrombi reduced the amount of mural thrombus and the size of emboli. In the absence of RBCs, mural thrombus mass was smaller in a highly tortuous arteriole compared to a less tortuous arteriole. In the presence of RBCs however, mural thrombus mass was larger in the highly tortuous arteriole compared to the less tortuous arteriole. As well, smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. This study shed light on microscopic interactions of RBCs and platelets in tortuous microvessels, which have implications in various pathologies associated with thrombosis and bleeding.

  3. Effect of Red Blood Cells on Platelet Activation and Thrombus Formation in Tortuous Arterioles. (United States)

    Chesnutt, Jennifer K W; Han, Hai-Chao


    Thrombosis is a major contributor to cardiovascular disease, which can lead to myocardial infarction and stroke. Thrombosis may form in tortuous microvessels, which are often seen throughout the human body, but the microscale mechanisms and processes are not well understood. In straight vessels, the presence of red blood cells (RBCs) is known to push platelets toward walls, which may affect platelet aggregation and thrombus formation. However in tortuous vessels, the effects of RBC interactions with platelets in thrombosis are largely unknown. Accordingly, the objective of this work was to determine the physical effects of RBCs, platelet size, and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A discrete element computational model was used to simulate the transport, collision, adhesion, aggregation, and shear-induced platelet activation of hundreds of individual platelets and RBCs in thrombus formation in tortuous arterioles. Results showed that high shear stress near the inner sides of curved arteriole walls activated platelets to initiate thrombosis. RBCs initially promoted platelet activation, but then collisions of RBCs with mural thrombi reduced the amount of mural thrombus and the size of emboli. In the absence of RBCs, mural thrombus mass was smaller in a highly tortuous arteriole compared to a less tortuous arteriole. In the presence of RBCs however, mural thrombus mass was larger in the highly tortuous arteriole compared to the less tortuous arteriole. As well, smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. This study shed light on microscopic interactions of RBCs and platelets in tortuous microvessels, which have implications in various pathologies associated with thrombosis and bleeding.

  4. Defective PDI release from platelets and endothelial cells impairs thrombus formation in Hermansky-Pudlak syndrome. (United States)

    Sharda, Anish; Kim, Sarah H; Jasuja, Reema; Gopal, Srila; Flaumenhaft, Robert; Furie, Barbara C; Furie, Bruce


    Protein disulfide isomerase (PDI), secreted from platelets and endothelial cells after injury, is required for thrombus formation. The effect of platelet and endothelial cell granule contents on PDI-mediated thrombus formation was studied by intravital microscopy using a mouse model of Hermansky-Pudlak syndrome in which platelet dense granules are absent. Platelet deposition and fibrin generation were nearly absent, and extracellular PDI was significantly reduced in HPS6(-/-) mice after vascular injury. HPS6(-/-) platelets displayed impaired PDI secretion and impaired exocytosis of α granules, lysosomes, and T granules due to decreased sensitivity to thrombin, but these defects could be corrected by addition of subthreshold amounts of adenosine 5'-diphosphate (ADP). Human Hermansky-Pudlak syndrome platelets demonstrated similar characteristics. Infusion of wild-type platelets rescued thrombus formation in HPS6(-/-) mice. Human umbilical vein endothelial cells in which the HPS6 gene was silenced displayed impaired PDI secretion and exocytosis of Weibel-Palade bodies. Defective thrombus formation in Hermansky-Pudlak syndrome, associated with impaired exocytosis of residual granules in endothelial cells and platelets, the latter due to deficiency of ADP, is characterized by a defect in T granule secretion, a deficiency in extracellular PDI secretion, and impaired fibrin generation and platelet aggregation. Hermansky-Pudlak syndrome is an example of a hereditary disease whereby impaired PDI secretion contributes to a bleeding phenotype.

  5. SIRT1 prevents pulmonary thrombus formation induced by arachidonic acid via downregulation of PAF receptor expression in platelets. (United States)

    Kim, Yun Hak; Bae, Jin Ung; Kim, In Suk; Chang, Chulhun L; Oh, Sae Ock; Kim, Chi Dae


    SIRT1, a class III histone deacetylase, is critically involved in cellular response to stress and modulates cardiovascular risk factors. However, its role in thrombus formation is largely unknown. Thus, this study investigated the effect of SIRT1 on pulmonary thrombus formation, and then identified its role in the modulation of platelet aggregation. In isolated human platelets, cell aggregation was increased by various platelet activators, such as platelet activating factor (PAF), arachidonic acid (AA), ADP, and thrombin. AA- and PAF-mediated platelet aggregations were suppressed by WEB2086, a PAF receptor (PAFR) antagonist. Pulmonary thrombus formation induced by PAF or AA was also attenuated by WEB2086, suggesting that PAFR plays a key role in AA-induced platelet aggregation. In platelets isolated from SIRT1-TG mice as well as in platelets treated with resveratrol or reSIRT1, PAFR expression was decreased, whereas this expressional downregulation by SIRT1 activators was inhibited in platelets treated with MG132 (a proteasome inhibitor) or NH4Cl (a lysosome inhibitor). Furthermore, platelet aggregation induced by AA was markedly attenuated by resveratrol and reSIRT1. Likewise, the increased pulmonary thrombus formation in mice treated with AA was also attenuated by SIRT1 activators. In line with these results, pulmonary thrombus formation was markedly attenuated in SIRT1-TG mice. Taken together, this study showed that SIRT1 downregulates PAFR expression on platelets via proteasomal and lysosomal pathways, and that this downregulation inhibits platelet aggregation in vitro and pulmonary thrombus formation in vivo.

  6. Cathepsin G-dependent modulation of platelet thrombus formation in vivo by blood neutrophils.

    Directory of Open Access Journals (Sweden)

    Nauder Faraday

    Full Text Available Neutrophils are consistently associated with arterial thrombotic morbidity in human clinical studies but the causal basis for this association is unclear. We tested the hypothesis that neutrophils modulate platelet activation and thrombus formation in vivo in a cathepsin G-dependent manner. Neutrophils enhanced aggregation of human platelets in vitro in dose-dependent fashion and this effect was diminished by pharmacologic inhibition of cathepsin G activity and knockdown of cathepsin G expression. Tail bleeding time in the mouse was prolonged by a cathepsin G inhibitor and in cathepsin G knockout mice, and formation of neutrophil-platelet conjugates in blood that was shed from transected tails was reduced in the absence of cathepsin G. Bleeding time was highly correlated with blood neutrophil count in wildtype but not cathepsin G deficient mice. In the presence of elevated blood neutrophil counts, the anti-thrombotic effect of cathepsin G inhibition was greater than that of aspirin and additive to it when administered in combination. Both pharmacologic inhibition of cathepsin G and its congenital absence prolonged the time for platelet thrombus to form in ferric chloride-injured mouse mesenteric arterioles. In a vaso-occlusive model of ischemic stroke, inhibition of cathepsin G and its congenital absence improved cerebral blood flow, reduced histologic brain injury, and improved neurobehavioral outcome. These experiments demonstrate that neutrophil cathepsin G is a physiologic modulator of platelet thrombus formation in vivo and has potential as a target for novel anti-thrombotic therapies.

  7. Thioredoxin Inhibitors Attenuate Platelet Function and Thrombus Formation (United States)

    Metcalfe, Clive; Ramasubramoni, Anjana; Pula, Giordano; Harper, Matthew T.; Mundell, Stuart J.; Coxon, Carmen H.


    Thioredoxin (Trx) is an oxidoreductase with important physiological function. Imbalances in the NADPH/thioredoxin reductase/thioredoxin system are associated with a number of pathologies, particularly cancer, and a number of clinical trials for thioredoxin and thioredoxin reductase inhibitors have been carried out or are underway. Due to the emerging role and importance of oxidoreductases for haemostasis and the current interest in developing inhibitors for clinical use, we thought it pertinent to assess whether inhibition of the NADPH/thioredoxin reductase/thioredoxin system affects platelet function and thrombosis. We used small molecule inhibitors of Trx (PMX 464 and PX-12) to determine whether Trx activity influences platelet function, as well as an unbiased proteomics approach to identify potential Trx substrates on the surface of platelets that might contribute to platelet reactivity and function. Using LC-MS/MS we found that PMX 464 and PX-12 affected the oxidation state of thiols in a number of cell surface proteins. Key surface receptors for platelet adhesion and activation were affected, including the collagen receptor GPVI and the von Willebrand factor receptor, GPIb. To experimentally validate these findings we assessed platelet function in the presence of PMX 464, PX-12, and rutin (a selective inhibitor of the related protein disulphide isomerase). In agreement with the proteomics data, small molecule inhibitors of thioredoxin selectively inhibited GPVI-mediated platelet activation, and attenuated ristocetin-induced GPIb-vWF-mediated platelet agglutination, thus validating the findings of the proteomics study. These data reveal a novel role for thioredoxin in regulating platelet reactivity via proteins required for early platelet responses at sites of vessel injury (GPVI and GPIb). This work also highlights a potential opportunity for repurposing of PMX 464 and PX-12 as antiplatelet agents. PMID:27716777

  8. Glaucocalyxin A inhibits platelet activation and thrombus formation preferentially via GPVI signaling pathway.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available Platelets play a pivotal role in atherothrombosis and the antiplatelet agents have been proved to be useful in preventing onset of acute clinical events including myocardial infarction and stroke. Increasing number of natural compounds has been identified to be potential antiplatelet agents. Here we report the antiplatelet effect of glaucocalyxin A (GLA, an ent-diterpenoid that we isolated and purified from the aerial parts of Rabdosia japonica (Burm. f. var. glaucocalyx (Maxim. Hara, and investigate the molecular mechanisms by which GLA inhibits platelet activation and thrombus formation. The effect of GLA on platelet activation was measured using platelets freshly isolated from peripheral blood of healthy donors. Results showed that pretreatment of human platelets with lower concentrations of GLA (0.01 μg/ml, 0.1 μg/ml significantly inhibited platelet aggregation induced by collagen (P<0.001 and CRP (P<0.01, a synthetic GPVI ligand, but not by ADP and U46619. Accordingly, GLA inhibited collagen-stimulated tyrosine phosphorylation of Syk, LAT, and phospholipase Cγ2, the signaling events in collagen receptor GPⅥ pathway. GLA also inhibited platelet p-selectin secretion and integrin activation by convulxin, a GPVI selective ligand. Additionally, GLA was found to inhibit low-dose thrombin-induced platelet activation. Using a flow chamber device, GLA was found to attenuate platelet adhesion on collagen surfaces in high shear condition. In vivo studies showed that GLA administration increased the time for complete occlusion upon vascular injury in mice, but did not extend tail-bleeding time when mice were administered with relatively lower doses of GLA. Therefore, the present results provide the molecular basis for the inhibition effect of GLA on platelet activation and its in vivo effect on thrombus formation, suggesting that GLA could potentially be developed as an antiplatelet and antithrombotic agent.

  9. Mesoscopic Modeling of Thrombus Formation and Growth: Platelet Deposition in Complex Geometries (United States)

    Yazdani, Alireza; Karniadakis, George


    Haemodynamics and blood rheology are important contributing factors to thrombus formation at a vulnerable vessel wall, and adhesion of platelets to a vascular surface, particularly in regions of flow stagnation, recirculation and reattachment is significantly important in formation of thrombi. For example, haemodynamic micro-environment can have effects on thrombosis inside the atherosclerotic plaques and aneurysms. To study these effects, we have developed and validated a model for platelet aggregation in blood flow using Dissipative Particle Dynamics (DPD) method. In this model platelets are considered as single DPD particles interacting with each other via Morse potential once activated. We assign an activation delay time to each platelet such that they remain passive during that time. We investigate the effect of different geometries on platelet aggregation by considering arterial stenosis at different levels of occlusion, and aneurysms of different shapes and sizes. The results show a marked increase in platelet aggregation within the boundaries of deceleration zone by increasing the degree of stenosis. Further, we observe enhanced platelet margination and wall deposition in the presence of red blood cells.

  10. Tripeptide SQL Inhibits Platelet Aggregation and Thrombus Formation by Affecting PI3K/Akt Signaling. (United States)

    Su, Xing-li; Su, Wen; He, Zhi-long; Ming, Xin; Kong, Yi


    Centipede has been prescribed for the treatment of cardiovascular diseases in Asian countries for several hundred years. Previously, a new antiplatelet tripeptide SQL (H-Ser-Gln-Leu-OH) was isolated and characterized from centipede. In this study, we investigated its antithrombotic activities in vivo and underlying mechanism. It was found that SQL inhibited platelet aggregation induced by adenosine diphosphate, thrombin, epinephrine, and collagen and attenuated thrombus formation in both the ferric chloride-induced arterial thrombosis model and arteriovenous shunt thrombosis model in rats. It did not prolong the bleeding time in mice even at the dose of 10 mg/kg that showed potent antithrombosis effects. Molecular docking revealed that SQL binds PI3Kβ with the binding free energy of -24.341 kcal/mol, which is close to that of cocrystallized ligand (-24.220 kcal/mol). Additionally, SQL displayed inhibition on the late (180 seconds) but did not influence the early (60 seconds) Akt Ser473 phosphorylation in the immunoblot assay. These results suggest that SQL inhibits thrombus formation in vivo and that SQL inhibits PI3K-mediated signaling or even the PI3K itself in platelets. This study may help elucidate the mechanism for centipede treating cardiovascular diseases.

  11. Platelet activation and thrombus formation relates to the presence of myocardial inflammation in patients with cardiomyopathy. (United States)

    Bobbert, Peter; Weikert, Ulf; Schmidt-Lucke, Caroline; Skurk, Carsten; Meyer, Alexander; Steffens, Daniel; Schultheiss, Heinz Peter; Rauch, Ursula


    Patients with cardiomyopathy show a significantly increased risk for thromboembolic events due to a hypercoagulable state and platelet dysfunction. The pathophysiologic mechanism underlying the increasing platelet activity in patients with cardiomyopathy remains unclear. We performed a clinical study to elucidate the link between myocardial tissue alterations and platelet activation in patients with cardiomyopathy. A total of 30 patients with suspected cardiomyopathy and 10 healthy control patients were included in our study. Hemodynamic parameters were measured by catheterization and echocardiography. Endomyocardial biopsies were taken to determine myocardial inflammation. Flow cytometry was performed to examine the platelet activation by quantification of p-selectin and thrombospondin expression on platelets. The p-selectin (8.46 ± 3.67 AU) and thrombospondin (26.56 ± 23.21 AU) expression was significantly correlated with the amount of CD3+ T cells (p-selectin: r=0.573, p<0.05; thrombospondin: r=0.488, p<0.05) and the endothelial/interstitial activation (p-selectin: r=0.521, p<0.05; thrombospondin: r=0.39, p<0.05). This was found to be independent of hemodynamic parameters, age, and gender. The platelet activation of patients (n=3) with echocardiographically documented ventricular thrombi was significantly increased (p-selectin: 12.57 ± 5.5 AU vs. 8.1 ± 3.2 AU, p<0.05) and this was associated with elevated myocardial inflammation scores. Myocardial inflammation is associated with a significant increase in platelet activation and ventricular thrombus formation independently of the hemodynamic conditions. Copyright © 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  12. Role of newly formed platelets in thrombus formation in rat after clopidogrel treatment

    DEFF Research Database (Denmark)

    Kuijpers, Marijke J E; Megens, Remco T A; Nikookhesal, Elham


    Platelet P2Y₁₂ receptors play an important role in arterial thrombosis by stimulating thrombus growth. Both irreversibly (clopidogrel) and reversibly binding (ticagrelor, AZD6140) P2Y₁₂ antagonists are clinically used for restricted periods, but possible differences in platelet function recovery...... after drug cessation have not been investigated. We treated WKY rats with a single, high dose of 200 mg/kg clopidogrel or 40 mg/kg ticagrelor. Blood was collected at different time points after treatment. Flow cytometry confirmed full platelet protection against ADP-induced αIIbβ₃ activation shortly...... after clopidogrel or ticagrelor treatment. At later time points after clopidogrel treatment, a subpopulation of juvenile platelets appeared that was fully responsive to ADP. Addition of ticagrelor to clopidogrel-treated blood reduced αIIbβ₃ activation of the unprotected platelets. In contrast, at later...

  13. The NLRP3 inflammasome and bruton's tyrosine kinase in platelets co-regulate platelet activation, aggregation, and in vitro thrombus formation. (United States)

    Murthy, Pranav; Durco, Filip; Miller-Ocuin, Jennifer L; Takedai, Teiko; Shankar, Shruthi; Liang, Xiaoyan; Liu, Xiao; Cui, Xiangdong; Sachdev, Ulka; Rath, Dominik; Lotze, Michael T; Zeh, Herbert J; Gawaz, Meinrad; Weber, Alexander N; Vogel, Sebastian


    Cleavage of interleukin-1β (IL-1β) is a key inflammatory event in immune cells and platelets, which is mediated by nucleotide-binding domain leucine rich repeat containing protein (NLRP3)-dependent activation of caspase-1. In immune cells, NLRP3 and caspase-1 form inflammasome complexes with the adaptor proteins apoptosis-associated speck-like protein containing a CARD (ASC) and bruton's tyrosine kinase (BTK). In platelets, however, the regulatory triggers and the functional effects of the NLRP3 inflammasome are unknown. Here, we show in vitro that the platelet NLRP3 inflammasome contributes to platelet activation, aggregation, and thrombus formation. NLRP3 activity, as monitored by caspase-1 activation and cleavage and secretion of IL-1β, was upregulated in activated platelets, which was dependent on platelet BTK. Pharmacological inhibition or genetic ablation of BTK in platelets led to decreased platelet activation, aggregation, and in vitro thrombus formation. We identify a functionally relevant link between BTK and NLRP3 in platelets, with potential implications in disease states associated with abnormal coagulation and inflammation. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Iliac artery mural thrombus formation. Effect of antiplatelet therapy on 111In-platelet deposition in baboons

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, S.R.; Paxton, L.D.; Harker, L.A.


    To measure the rate, extent, and time course of arterial mural thrombus formation in vivo and to assess the effects of antiplatelet therapy in that setting, we have studied autologous /sup 111/In-platelet deposition induced by experimental iliac artery aneurysms in baboons. Scintillation camera imaging analyses were performed at 1, 24, 48, and 72 hours after implantation of the device. Correction for tissue attenuation was determined by using a small, comparably located /sup 111/In source implanted at the time of surgery. In five animals, /sup 111/In-platelet activity accumulated progressively after device implantation, reaching a maximum after the third day. Repeat image analysis carried out 2 weeks after the surgical procedure also showed progressive accumulation of /sup 111/In-platelets over 3 days but at markedly reduced amounts as compared with the initial study. In five additional animals, treatment with a combination of aspirin and dipyridamole begun 1 hour after surgical implantation reduced /sup 111/In-platelet deposition to negligible levels by the third day. Although platelet survival time was shortened and platelet turnover was reciprocally increased in all operated animals, platelet survival and turnover were not affected by antiplatelet therapy. We conclude that, in contrast to platelet survival and turnover measurements, /sup 111/In-platelet imaging is a reliable and sensitive method for localizing and quantifying focal arterial thrombi and for assessing the effects of antiplatelet therapy.

  15. Snake venom proteins and platelet thrombus formation%蛇毒蛋白与血小板血栓形成

    Institute of Scientific and Technical Information of China (English)

    李灵欣; 刘欣; 宁淑香; 李庆伟; 王继红


    多种蛇毒蛋白具有与血小板表面整合素、膜糖蛋白I b(GP I b)或血管性血友病因子(VWF)相互作用而影响血栓形成的功能.影响血小板血栓形成的蛇毒蛋白目前分为3类:去整合素、VWF调节蛇毒蛋白及GPI b结合蛋白.其中,去整合素具有高效抑制血小板聚集的功能;VWF调节蛇毒蛋白具有体外介导VWF依赖型血小板聚集的功能;而GPI b结合蛇毒蛋白又分为2组:GPI b激动剂和GPI b拮抗剂,分别起诱导血小板聚集与抑制VWF介导的血小板聚集的功能.本文将对上述影响血小板血栓形成的蛇毒蛋白的结构、功能及其在临床上的研究与应用进行综述.%Various snake venom proteins interact with platelet surface integrins, membrane glycoprotein GP I b or von Willebrand factor (VWF) to affect thrombus formation. These snake venom proteins affecting platelet thrombus formation have been classified as: disintegrins, VWF-modulating venom proteins and GP I b-binding proteins. Among them, disintegrins are strong inhibitors of platelet aggregation. VWF-modulating venom proteins can induce VWF-dependent platelet aggregation in vitro, and GP I b-binding proteins include GP I b-agonists and GP I b-antagonists, which can induce platelet aggregation and inhibit VWF-in-duced platelet aggregation, respectively. This review will focus on the structure and function of snake venom proteins that affect platelet thrombus formation in order to find value of which in sub-diagnosis of platelet disorder or von Willebrand disease, as well as for clinical and basic research of thrombosis and hemostasis.

  16. Schisandra chinensis and Morus alba Synergistically Inhibit In Vivo Thrombus Formation and Platelet Aggregation by Impairing the Glycoprotein VI Pathway

    Directory of Open Access Journals (Sweden)

    Dong-Seon Kim


    Full Text Available Morus alba L. (MAL extract has been used in traditional medicine for its cardioprotective and antiplatelet effects, while another herbal remedy, Schisandra chinensis (SCC, has been reported to have anti-inflammatory and antioxidant properties. We evaluated underlying cellular changes exerted by extracts of these plants on platelet function and effects of SCC + MAL on in vivo thrombus formation using AV shunt and tail thrombosis-length models in rats. In vitro platelet aggregation, granule secretion, and Ca2+i release assays were carried out. The activation of integrin αIIbβ3 and phosphorylation of downstream signaling molecules, including MAPK and Akt, were investigated using cytometry and immunoblotting, respectively. Scanning electron microscopy (SEM was used to evaluate changes in platelet shape and HPLC analysis was carried out to identify the marker compounds in SCC + MAL mixture. In vivo thrombus weight and average length of tail thrombosis were significantly decreased by SCC + MAL. In vitro platelet aggregation, granule secretion, Ca2+i release, and integrin αIIbβ3 activation were notably inhibited. SCC + MAL markedly reduced the phosphorylation of MAPK pathway factors along with Akt. HPLC analysis identified four marker compounds: isoquercitrin, astragalin, schizandrol A, and gomisin A. The extracts exerted remarkable synergistic effects as natural antithrombotic and antiplatelet agent and a potent drug candidate for treating cardiovascular diseases.

  17. Discrimination between platelet-mediated and coagulation-mediated mechanisms in a model of complex thrombus formation in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Cadroy, Y.; Horbett, T.A.; Hanson, S.R.


    To study mechanisms of complex thrombus formation in vivo, and to compare the relative antithrombotic effects of anticoagulants and antiplatelet agents, a model was developed in baboons. Segments of collagen-coated tubing followed by two sequentially placed expansion chambers exhibiting disturbed flow patterns were exposed to native blood under laminar flow conditions. The device was incorporated for 1 hour into an exteriorized arteriovenous shunt in baboons under controlled blood flow (20 ml/min). Morphologic evaluation by scanning electron microscopy showed that thrombi associated with collagen were relatively rich in platelets but thrombi in the chambers were rich in fibrin and red cells. Deposition of indium 111-labeled platelets was continuously measured with a scintillation camera. Platelet deposition increased in a linear (collagen-coated segment) or exponential (chambers 1 and 2) fashion over time, with values after 40 minutes averaging 24.1 +/- 3.3 x 10(8) platelets (collagen segment), 16.7 +/- 3.4 x 10(8) platelets (chamber 1), and 8.4 +/- 2.4 x 10(8) platelets (chamber 2). Total fibrinogen deposition after 40 minutes was determined by using iodine 125-labeled baboon fibrinogen and averaged 0.58 +/- 0.14 mg in the collagen segment, 1.51 +/- 0.27 mg in chamber 1, and 0.95 +/- 0.25 mg in chamber 2. Plasma levels of beta-thromboglobulin (beta TG), platelet-factor 4 (PF4), and fibrinopeptide A (FPA) increased fourfold to fivefold after 60 minutes of blood exposure to the thrombotic device. Platelet deposition onto the collagen segment, chamber 1, and chamber 2 was linearly dependent on the circulating platelet count. Platelet accumulation in chamber 1 and chamber 2 was also dependent on the presence of the proximal collagen segment.

  18. The pyrrolidinoindoline alkaloid Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling (United States)

    Su, Xing-li; Su, Wen; Wang, Ying; Wang, Yue-hu; Ming, Xin; Kong, Yi


    Aim: Psm2, one of the pyrrolidinoindoline alkaloids isolated from whole Selaginella moellendorffii plants, has shown a potent antiplatelet activity. In this study, we further evaluated the antiplatelet effects of Psm2, and elucidated the underlying mechanisms. Methods: Human platelet aggregation in vitro and rat platelet aggregation ex vivo were investigated. Agonist-induced platelet aggregation was measured using a light transmission aggregometer. The antithrombotic effects of Psm2 were evaluated in arteriovenous shunt thrombosis model in rats. To elucidate the mechanisms underlying the antiplatelet activity of Psm2, ELISAs, Western blotting and molecular docking were performed. The bleeding risk of Psm2 administration was assessed in a mouse tail cutting model, and the cytotoxicity of Psm2 was measured with MTT assay in EA.hy926 cells. Results: Psm2 dose-dependently inhibited human platelet aggregation induced by ADP, U4619, thrombin and collagen with IC50 values of 0.64, 0.37, 0.35 and 0.87 mg/mL, respectively. Psm2 (1, 3, 10 mg/kg) administered to rats significantly inhibited platelet aggregation ex vivo induced by ADP. Psm2 (1, 3, 10 mg/mL, iv) administered to rats with the A–V shunt dose-dependently decreased the thrombus formation. Psm2 inhibited platelet adhesion to fibrinogen and collagen with IC50 values of 84.5 and 96.5 mg/mL, respectively, but did not affect the binding of fibrinogen to GPIIb/IIIa. Furthermore, Psm2 inhibited AktSer473 phosphorylation, but did not affect MAPK signaling and Src kinase activation. Molecular docking showed that Psm2 bound to phosphatidylinositol 3-kinase β (PI3Kβ) with a binding free energy of −13.265 kcal/mol. In addition, Psm2 did not cause toxicity in EA.hy926 cells and produced only slight bleeding in a mouse tail cutting model. Conclusion: Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling. Psm2 may be a lead compound or drug candidate that could be developed for the

  19. An investigation on platelet transport during thrombus formation at micro-scale stenosis.

    Directory of Open Access Journals (Sweden)

    Francisco Javier Tovar-Lopez

    Full Text Available This paper reports on an investigation of mass transport of blood cells at micro-scale stenosis where local strain-rate micro-gradients trigger platelet aggregation. Using a microfluidic flow focusing platform we investigate the blood flow streams that principally contribute to platelet aggregation under shear micro-gradient conditions. We demonstrate that relatively thin surface streams located at the channel wall are the primary contributor of platelets to the developing aggregate under shear gradient conditions. Furthermore we delineate a role for red blood cell hydrodynamic lift forces in driving enhanced advection of platelets to the stenosis wall and surface of developing aggregates. We show that this novel microfluidic platform can be effectively used to study the role of mass transport phenomena driving platelet recruitment and aggregate formation and believe that this approach will lead to a greater understanding of the mechanisms underlying shear-gradient dependent discoid platelet aggregation in the context of cardiovascular diseases such as acute coronary syndromes and ischemic stroke.

  20. Skepinone-L, a Novel Potent and Highly Selective Inhibitor of p38 MAP Kinase, Effectively Impairs Platelet Activation and Thrombus Formation

    Directory of Open Access Journals (Sweden)

    Oliver Borst


    Full Text Available Background/Aims: Platelets are critically important for primary haemostasis and the major players in thrombotic vascular occlusion. Platelets are activated by agonists, such as thrombin and collagen-related peptide as well as second-wave mediators including thromboxane A2 via different intracellular signaling pathways resulting in degranulation, aggregation and thrombus formation. Platelet activation is paralleled by phosphorylation and activation of p38 MAPK. The limited specificity of hitherto known p38 MAPK inhibitors precluded safe conclusions on the precise role of p38 MAPK in the regulation of platelet function. The present study examined the impact of Skepinone-L, a novel and highly selective inhibitor of p38 mitogen-activated protein kinase (p38 MAPK, on platelet activation and thrombus formation. Methods: Experiments were performed in freshly isolated human platelets. Protein phosphorylation was quantified by Western blotting, thromboxane B2 synthesis by enzyme immunoassay, ATP release by ChronoLume luciferin assay, cytosolic Ca2+ concentration by Fura-2 fluorescence-measurements, platelet aggregation by a light transmissions measurement and in vitro thrombus formation by a flow chamber. Results: Skepinone-L (1 μM virtually abrogated the phosphorylation of platelet p38 MAPK substrate Hsp27 following stimulation with CRP (1 μg/ml, thrombin (5 mU/ml or thromboxane A2 analogue U-46619 (1 μM. Furthermore, Skepinone-L significantly blunted activation-dependent platelet secretion and aggregation following threshold concentrations of CRP, thrombin and thromboxane A2 analogue U-46619. Skepinone-L did not impair platelet Ca2+ signaling but prevented agonist-induced thromboxane A2 synthesis through abrogation of p38 MAPK-dependent phosphorylation of platelet cytosolic phospholipase A2 (cPLA2. Skepinone-L further markedly blunted thrombus formation under low (500-s and high (1700-s arterial shear rates. Conclusions: The present study discloses

  1. Thrombus Formation at High Shear Rates. (United States)

    Casa, Lauren D C; Ku, David N


    The final common pathway in myocardial infarction and ischemic stroke is occlusion of blood flow from a thrombus forming under high shear rates in arteries. A high-shear thrombus forms rapidly and is distinct from the slow formation of coagulation that occurs in stagnant blood. Thrombosis at high shear rates depends primarily on the long protein von Willebrand factor (vWF) and platelets, with hemodynamics playing an important role in each stage of thrombus formation, including vWF binding, platelet adhesion, platelet activation, and rapid thrombus growth. The prediction of high-shear thrombosis is a major area of biofluid mechanics in which point-of-care testing and computational modeling are promising future directions for clinically relevant research. Further research in this area will enable identification of patients at high risk for arterial thrombosis, improve prevention and treatment based on shear-dependent biological mechanisms, and improve blood-contacting device design to reduce thrombosis risk.

  2. A novel thromboxane receptor antagonist, nstpbp5185, inhibits platelet aggregation and thrombus formation in animal models. (United States)

    Huang, Shiu-Wen; Kuo, Heng-Lan; Hsu, Ming-Tsung; Tseng, Yufeng Jane; Lin, Shu-Wha; Kuo, Sheng-Chu; Peng, Hui-Chin; Lien, Jin-Cherng; Huang, Tur-Fu


    A novel benzimidazole derivative, nstpbp5185, was discovered through in vitro and in vivo evaluations for antiplatelet activity. Thromaboxane receptor (TP) is important in vascular physiology, haemostasis and pathophysiological thrombosis. Nstpbp5185 concentration-dependently inhibited human platelet aggregation caused by collagen, arachidonic acid and U46619. Nstpbp5185 caused a right-shift of the concentration-response curve of U46619 and competitively inhibited the binding of 3H-SQ-29548 to TP receptor expressed on HEK-293 cells, with an IC50 of 0.1 µM, indicating that nstpbp5185 is a TP antagonist. In murine thrombosis models, nstpbp5185 significantly prolonged the latent period in triggering platelet plug formation in mesenteric and FeCl3-induced thrombi formation, and increased the survival rate in pulmonary embolism model with less bleeding than aspirin. This study suggests nstpbp5185, an orally selective anti-thrombotic agent, acting through blockade of TXA2 receptor, may be efficacious for prevention or treatment of pathologic thrombosis.

  3. Platelet Activation and Thrombus Formation over IgG Immune Complexes Requires Integrin αIIbβ3 and Lyn Kinase. (United States)

    Zhi, Huiying; Dai, Jing; Liu, Junling; Zhu, Jieqing; Newman, Debra K; Gao, Cunji; Newman, Peter J


    IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.

  4. Platelet Activation and Thrombus Formation over IgG Immune Complexes Requires Integrin αIIbβ3 and Lyn Kinase.

    Directory of Open Access Journals (Sweden)

    Huiying Zhi

    Full Text Available IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.

  5. Methods to Determine the Lagrangian Shear Experienced by Platelets during Thrombus Growth.

    Directory of Open Access Journals (Sweden)

    Isaac P Pinar

    Full Text Available Platelets can become activated in response to changes in flow-induced shear; however, the underlying molecular mechanisms are not clearly understood. Here we present new techniques for experimentally measuring the flow-induced shear rate experienced by platelets prior to adhering to a thrombus. We examined the dynamics of blood flow around experimentally grown thrombus geometries using a novel combination of experimental (ex vivo and numerical (in silico methodologies. Using a microcapillary system, platelet aggregate formation was analysed at elevated shear rates in the presence of coagulation inhibitors, where thrombus formation is predominantly platelet-dependent. These approaches permit the resolution and quantification of thrombus parameters at the scale of individual platelets (2 μm in order to quantify real time thrombus development. Using our new techniques we can correlate the shear rate experienced by platelets with the extent of platelet adhesion and aggregation. The techniques presented offer the unique capacity to determine the flow properties for a temporally evolving thrombus field in real time.

  6. Simplagrin, a platelet aggregation inhibitor from Simulium nigrimanum salivary glands specifically binds to the Von Willebrand factor receptor in collagen and inhibits carotid thrombus formation in vivo.

    Directory of Open Access Journals (Sweden)

    Andrezza C Chagas


    Full Text Available Among the several challenges faced by bloodsucking arthropods, the vertebrate hemostatic response against blood loss represents an important barrier to efficient blood feeding. Here we report the first inhibitor of collagen-induced platelet aggregation derived from the salivary glands of a black fly (Simulium nigrimanum, named Simplagrin.Simplagrin was expressed in mammalian cells and purified by affinity-and size-exclusion chromatography. Light-scattering studies showed that Simplagrin has an elongated monomeric form with a hydrodynamic radius of 5.6 nm. Simplagrin binds to collagen (type I-VI with high affinity (2-15 nM, and this interaction does not involve any significant conformational change as determined by circular dichroism spectroscopy. Simplagrin-collagen interaction is both entropically and enthalpically driven with a large negative ΔG, indicating that this interaction is favorable and occurs spontaneously. Simplagrin specifically inhibits von Willebrand factor interaction with collagen type III and completely blocks platelet adhesion to collagen under flow conditions at high shear rates; however, Simplagrin failed to block glycoprotein VI and Iα2β1 interaction to collagen. Simplagrin binds to RGQOGVMGF peptide with an affinity (K(D 11 nM similar to that of Simplagrin for collagen. Furthermore, Simplagrin prevents laser-induced carotid thrombus formation in vivo without significant bleeding in mice and could be useful as an antithrombotic agent in thrombosis related disease.Our results support the orthology of the Aegyptin clade in bloodsucking Nematocera and the hypothesis of a faster evolutionary rate of salivary function of proteins from blood feeding arthropods.

  7. Protective Mechanisms of S. lycopersicum Aqueous Fraction (Nucleosides and Flavonoids on Platelet Activation and Thrombus Formation: In Vitro, Ex Vivo and In Vivo Studies

    Directory of Open Access Journals (Sweden)

    Eduardo Fuentes


    Full Text Available The purpose of this research was to investigate mechanisms of antiplatelet action of bioactive principle from S. lycopersicum. Aqueous fraction had a high content of nucleosides (adenosine, guanosine, and adenosine 5′-monophosphate by HPLC analysis. Also aqueous fraction presented flavonoids content. Aqueous fraction inhibited platelet activation by 15 ± 6% (P<0.05. Fully spread of human platelets on collagen in the presence of aqueous fraction was inhibited from 15 ± 1 to 9 ± 1 μm2 (P<0.001. After incubation of whole blood with aqueous fraction, the platelet coverage was inhibited by 55 ± 12% (P<0.001. Platelet ATP secretion and aggregation were significantly inhibited by the aqueous fraction. At the same concentrations that aqueous fraction inhibits platelet aggregation, levels of sCD40L significantly decreased and the intraplatelet cAMP levels increased. In addition, SQ22536, an adenylate cyclase inhibitor, attenuated the effect of aqueous fraction toward ADP-induced platelet aggregation and intraplatelet level of cAMP. Platelet aggregation ex vivo (human study and thrombosis formation in vivo (murine model were inhibited by aqueous fraction. Finally, aqueous fraction may be used as a functional ingredient adding antiplatelet activities (nucleosides and flavonoids to processed foods.

  8. Endobrevin/VAMP-8-dependent dense granule release mediates thrombus formation in vivo. (United States)

    Graham, Gwenda J; Ren, Qiansheng; Dilks, James R; Blair, Price; Whiteheart, Sidney W; Flaumenhaft, Robert


    Individuals whose platelets lack dense or alpha-granules suffer various degrees of abnormal bleeding, implying that granule cargo contributes to hemostasis. Despite these clinical observations, little is known regarding the effects of impaired platelet granule secretion on thrombus formation in vivo. In platelets, SNARE proteins mediate the membrane fusion events required for granule cargo release. Endobrevin/VAMP-8 is the primary vesicle-SNARE (v-SNARE) responsible for efficient release of dense and alpha-granule contents; thus, VAMP-8(-/-) mice are a useful model to evaluate the importance of platelet granule secretion in thrombus formation. Thrombus formation, after laser-induced vascular injury, in these mice is delayed and decreased, but not absent. In contrast, thrombus formation is almost completely abolished in the mouse model of Hermansky-Pudlak syndrome, ruby-eye, which lacks dense granules. Evaluation of aggregation of VAMP-8(-/-) and ruby-eye platelets indicates that defective ADP release is the primary abnormality leading to impaired aggregation. These results demonstrate the importance of dense granule release even in the earliest phases of thrombus formation and validate the distal platelet secretory machinery as a potential target for antiplatelet therapies.

  9. Endobrevin/VAMP-8–dependent dense granule release mediates thrombus formation in vivo (United States)

    Graham, Gwenda J.; Ren, Qiansheng; Dilks, James R.; Blair, Price; Flaumenhaft, Robert


    Individuals whose platelets lack dense or α-granules suffer various degrees of abnormal bleeding, implying that granule cargo contributes to hemostasis. Despite these clinical observations, little is known regarding the effects of impaired platelet granule secretion on thrombus formation in vivo. In platelets, SNARE proteins mediate the membrane fusion events required for granule cargo release. Endobrevin/VAMP-8 is the primary vesicle-SNARE (v-SNARE) responsible for efficient release of dense and α-granule contents; thus, VAMP-8−/− mice are a useful model to evaluate the importance of platelet granule secretion in thrombus formation. Thrombus formation, after laser-induced vascular injury, in these mice is delayed and decreased, but not absent. In contrast, thrombus formation is almost completely abolished in the mouse model of Hermansky-Pudlak syndrome, ruby-eye, which lacks dense granules. Evaluation of aggregation of VAMP-8−/− and ruby-eye platelets indicates that defective ADP release is the primary abnormality leading to impaired aggregation. These results demonstrate the importance of dense granule release even in the earliest phases of thrombus formation and validate the distal platelet secretory machinery as a potential target for antiplatelet therapies. PMID:19395672

  10. Methylglyoxal induces platelet hyperaggregation and reduces thrombus stability by activating PKC and inhibiting PI3K/Akt pathway.

    Directory of Open Access Journals (Sweden)

    Karin Hadas

    Full Text Available Diabetes is characterized by a dysregulation of glucose homeostasis and platelets from patients with diabetes are known to be hyper-reactive and contribute to the accelerated development of vascular diseases. Since many of the deleterious effects of glucose have been attributed to its metabolite methylgyloxal (MG rather than to hyperglycemia itself, the aim of the present study was to characterize the effects of MG on platelet function. Washed human platelets were pre-incubated for 15 min with MG and platelet aggregation, adhesion on matrix-coated slides and signaling (Western blot were assessed ex vivo. In vivo, the effect of MG on thrombus formation was determined using the FeCl3-induced carotid artery injury model. MG potentiated thrombin-induced platelet aggregation and dense granule release, but inhibited platelet spreading on fibronectin and collagen. In vivo, MG accelerated thrombus formation but decreased thrombus stability. At the molecular level, MG increased intracellular Ca(2+ and activated classical PKCs at the same time as inhibiting PI3K/Akt and the β3-integrin outside-in signaling. In conclusion, these findings indicate that the enhanced MG concentration measured in diabetic patients can directly contribute to the platelet dysfunction associated with diabetes characterized by hyperaggregability and reduced thrombus stability.

  11. Methylglyoxal induces platelet hyperaggregation and reduces thrombus stability by activating PKC and inhibiting PI3K/Akt pathway. (United States)

    Hadas, Karin; Randriamboavonjy, Voahanginirina; Elgheznawy, Amro; Mann, Alexander; Fleming, Ingrid


    Diabetes is characterized by a dysregulation of glucose homeostasis and platelets from patients with diabetes are known to be hyper-reactive and contribute to the accelerated development of vascular diseases. Since many of the deleterious effects of glucose have been attributed to its metabolite methylgyloxal (MG) rather than to hyperglycemia itself, the aim of the present study was to characterize the effects of MG on platelet function. Washed human platelets were pre-incubated for 15 min with MG and platelet aggregation, adhesion on matrix-coated slides and signaling (Western blot) were assessed ex vivo. In vivo, the effect of MG on thrombus formation was determined using the FeCl3-induced carotid artery injury model. MG potentiated thrombin-induced platelet aggregation and dense granule release, but inhibited platelet spreading on fibronectin and collagen. In vivo, MG accelerated thrombus formation but decreased thrombus stability. At the molecular level, MG increased intracellular Ca(2+) and activated classical PKCs at the same time as inhibiting PI3K/Akt and the β3-integrin outside-in signaling. In conclusion, these findings indicate that the enhanced MG concentration measured in diabetic patients can directly contribute to the platelet dysfunction associated with diabetes characterized by hyperaggregability and reduced thrombus stability.

  12. Soft thrombus formation in radiofrequency catheter ablation

    NARCIS (Netherlands)

    Demolin, JM; Eick, OJ; Munch, K; Koullick, E; Nakagawa, H; Wittkampf, FHM


    During RF catheter ablation, local temperature elevation can result in coagulum formation on the ablation electrode, resulting in impedance rise. A recent study has also demonstrated the formation of a so-called soft thrombus during experimental ablations. This deposit poorly adhered to the catheter

  13. Plasminogen associates with phosphatidylserine-exposing platelets and contributes to thrombus lysis under flow. (United States)

    Whyte, Claire S; Swieringa, Frauke; Mastenbroek, Tom G; Lionikiene, Ausra S; Lancé, Marcus D; van der Meijden, Paola E J; Heemskerk, Johan W M; Mutch, Nicola J


    The interaction of plasminogen with platelets and their localization during thrombus formation and fibrinolysis under flow are not defined. Using a novel model of whole blood thrombi, formed under flow, we examine dose-dependent fibrinolysis using fluorescence microscopy. Fibrinolysis was dependent upon flow and the balance between fibrin formation and plasminogen activation, with tissue plasminogen activator-mediated lysis being more efficient than urokinase plasminogen activator-mediated lysis. Fluorescently labeled plasminogen radiates from platelet aggregates at the base of thrombi, primarily in association with fibrin. Hirudin attenuates, but does not abolish plasminogen binding, denoting the importance of fibrin. Flow cytometry revealed that stimulation of platelets with thrombin/convulxin significantly increased the plasminogen signal associated with phosphatidylserine (PS)-exposing platelets. Binding was attenuated by tirofiban and Gly-Pro-Arg-Pro amide, confirming a role for fibrin in amplifying plasminogen binding to PS-exposing platelets. Confocal microscopy revealed direct binding of plasminogen and fibrinogen to different platelet subpopulations. Binding of plasminogen and fibrinogen co-localized with PAC-1 in the center of spread platelets. In contrast, PS-exposing platelets were PAC-1 negative, and bound plasminogen and fibrinogen in a protruding "cap." These data show that different subpopulations of platelets harbor plasminogen by diverse mechanisms and provide an essential scaffold for the accumulation of fibrinolytic proteins that mediate fibrinolysis under flow.

  14. A General Shear-Dependent Model for Thrombus Formation. (United States)

    Yazdani, Alireza; Li, He; Humphrey, Jay D; Karniadakis, George Em


    Modeling the transport, activation, and adhesion of platelets is crucial in predicting thrombus formation and growth following a thrombotic event in normal or pathological conditions. We propose a shear-dependent platelet adhesive model based on the Morse potential that is calibrated by existing in vivo and in vitro experimental data and can be used over a wide range of flow shear rates ([Formula: see text]). We introduce an Eulerian-Lagrangian model where hemodynamics is solved on a fixed Eulerian grid, while platelets are tracked using a Lagrangian framework. A force coupling method is introduced for bidirectional coupling of platelet motion with blood flow. Further, we couple the calibrated platelet aggregation model with a tissue-factor/contact pathway coagulation cascade, representing the relevant biology of thrombin generation and the subsequent fibrin deposition. The range of shear rates covered by the proposed model encompass venous and arterial thrombosis, ranging from low-shear-rate conditions in abdominal aortic aneurysms and thoracic aortic dissections to thrombosis in stenotic arteries following plaque rupture, where local shear rates are extremely high.

  15. Multi-parameter assessment of thrombus formation on microspotted arrays of thrombogenic surfaces




    Authors: Susanne de Witt, Frauke Swieringa, Judith Cosemans & Johan Heemskerk ### Abstract Thrombus formation by adhering and aggregating blood platelets is fundamental to hemostasis and is a prerequisite for vascular occlusion in pathological thrombosis. The parallel-plate flow chamber technique has been extensively used to measure platelet adhesion and activation in vitro at arterial or venous flow conditions. Here, we describe the use of brightfield and confocal fluorescence mi...

  16. Fluid Characteristics in Abdominal Aortic Aneurysms (AAAs) and Its Correlation to Thrombus Formation (United States)

    Tang, Rubing; Bar-Yoseph, Pinhas Z.; Lasheras, Juan


    It has been observed that most large Abdominal Aortic Aneurysms (AAAs) develop an intraluminal thrombus as they progressively enlarge. Previous studies have suggested that the build up of the thrombus may be associated with the altered hemodynamic patterns that arise inside the AAA. We have performed a parametrical computational study of the flow patterns inside enlarging AAA to investigate the possible mechanism controlling the thrombus formation. Pulsatile blood flows were simulated in idealized models of fusiform aneurysms with different dilatation ratios and the effects of shear-activated platelet accumulation and platelet/wall interaction were evaluated based on the calculated flow fields. The platelet activation level (PAL) was determined by computing the integral over time of flow shear stresses exerted over the platelets as they are transported throughout the aneurysm. Our results have shown that the values of PAL in AAAs are in fact smaller than the maximum value obtained in a healthy abdominal aorta. However, we show that the transportation of blood cells towards the wall and the formation of stagnation points on the aneurysm's wall play more significant roles in thrombus formation than PAL.

  17. Thrombus imaging in a primate model with antibodies specific for an external membrane protein of activated platelets

    Energy Technology Data Exchange (ETDEWEB)

    Palabrica, T.M.; Furie, B.C.; Konstam, M.A.; Aronovitz, M.J.; Connolly, R.; Brockway, B.A.; Ramberg, K.L.; Furie, B.


    The activated platelet is a potential target for the localization of thrombi in vivo since, after stimulation and secretion of granule contents, activated platelets are concentrated at sites of blood clot formation. In this study, we used antibodies specific for a membrane protein of activated platelets to detect experimental thrombi in an animal model. PADGEM (platelet activation-dependent granule-external membrane protein), a platelet alpha-granule membrane protein, is translocated to the plasma membrane during platelet activation and granule secretion. Since PADGEM is internal in unstimulated platelets, polyclonal anti-PADGEM and monoclonal KC4 antibodies do not bind to circulating resting platelets but do interact with activated platelets. Dacron graft material incubated with radiolabeled KC4 or anti-PADGEM antibodies in the presence of thrombin-activated platelet-rich plasma bound most of the antibody. Imaging experiments with 123I-labeled anti-PADGEM in baboons with an external arterial-venous Dacron shunt revealed rapid uptake in the thrombus induced by the Dacron graft; control experiments with 123I-labeled nonimmune IgG exhibited minimal uptake. Deep venous thrombi, formed by using percutaneous balloon catheters to stop blood flow in the femoral vein of baboons, were visualized with 123I-labeled anti-PADGEM. Thrombi were discernible against blood pool background activity without subtraction techniques within 1 hr. No target enhancement was seen with 123I-labeled nonimmune IgG. 123I-labeled anti-PADGEM cleared the blood pool with an initial half-disappearance time of 6 min and did not interfere with hemostasis. These results indicate that radioimmunoscintigraphy with anti-PADGEM antibodies can visualize thrombi in baboon models and is a promising technique for clinical thrombus detection in humans.

  18. The effect of taurolidine on experimental thrombus formation. (United States)

    Kaptanoglu, Levent; Kucuk, Hasan Fehmi; Colak, Elif; Kurt, Necmi; Bingul, Sadik Mehmet; Akyol, Huseyin; Torlak, Oguzhan Aziz; Yazici, Fatma


    Venous thrombosis can be the source of emboli, a significant health risk encountered throughout surgical and medical clinics. Taurolidine is an antimicrobial agent used to prevent intraabdominal adhesion formation and sepsis in experimental and clinical trials. The aim of this study is to evaluate effect of taurolidine on experimental thrombus formation and make a comparison with low-molecular weight heparin. Four groups of ten Wistar-Albino rats (300-350 g) were used; with the first and second groups each being administered 10 and 20 mg of taurolidine, the third group low-molecular weight heparin and the fourth group saline solution (control group) respectively. Experimental thrombus formation was performed in rats in the area of the abdominal inferior vena cava by using a combination of stasis and hypercoagulability described by Wessler et al. [Wessler, S., Reimer, S.M., Sheps, M.C., 1959. Biologic assay of a thrombosis inducing activity in human serum. J. Appl. Physiol. 14:943-946.]. Thrombocyte count, the weight of thrombus, prothrombin time and activated partial thromboplastin time and activities of coagulation factors were measured and compared across groups. Thrombus weights in the taurolidine treated groups were lower than the control group and greater than the low-molecular weight heparin treated group. Taurolidine was found to decrease activities of coagulation factors V, VIII, IX, XI and XII. Taurolidine showed no effect on activated partial thromboplastin time and prothrombin time values; however, it decreased thrombus weight, but not as much as low-molecular weight heparin. The cause of these findings in our study may be related to the minimized effect of taurolidine on factor II, VII, and X activities. These effects likely render the agent ineffective in the prevention of venous thrombosis. Taurolidine was found to be less effective than low-molecular weight heparin in prevention of thrombus formation.

  19. Acidosis induced by carbon dioxide insufflation decreases heparin potency: a risk factor for thrombus formation. (United States)

    Gorter, Karin A M; Stehouwer, Marco C; Van Putte, Bart P; Vlot, Eline A; Urbanus, Rolf T


    Since the introduction of CO2 insufflation during open heart surgery in our hospital, we incidentally observed thrombus formation in the dissected heart, in the pericardium and in the cardiotomy reservoir of the cardiopulmonary bypass system. Furthermore, we measured very high levels of pCO2, causing severe acidosis, in stagnant blood in the pericardium and cardiotomy reservoir. In this in vitro study, we assessed the influence of acidosis and hypothermia on heparin potency and thrombin formation. We assessed heparin potency in function of pH (pH 5.0-7.4) and temperature (24-37°C) by comparing the activated partial thromboplastin time in platelet-poor plasma between samples with and without unfractionated heparin. We measured thrombin formation in platelet-poor plasma by means of fluorescent, calibrated, automated thrombography in function of pH (pH 5.0-7.4) and temperature (24-37°C). The parameters of interest were the endogenous thrombin potential and the peak amount of thrombin generation. The major finding of this study is the significant decrease in the efficiency of unfractionated heparin in delaying thrombus formation at acidotic (pH 5.0-7.0) conditions (p=0.034-0.05). Furthermore, we found that thrombin formation is significantly increased at hypothermic (24-34°C) conditions (p=acidosis may lead to a decreased heparin potency. Acidosis, as induced by CO2 insufflation, may predispose patients to incidental thrombus formation in stagnant blood in the open thorax and in the cardiotomy reservoir. Hypothermia might further increase this risk. Therefore, we recommend reconsidering the potential advantages and disadvantages of using CO2 insufflation during cardiopulmonary bypass.

  20. Simulation of platelet, thrombus and erythrocyte hydrodynamic interactions in a 3D arteriole with in vivo comparison.

    Directory of Open Access Journals (Sweden)

    Weiwei Wang

    Full Text Available Cylindrical blood vessels, ellipsoid platelets and biconcave-shaped deformable erythrocytes (RBCs are important participants in hemostasis and thrombosis. However, due to the challenge of combining these components in simulation tools, few simulation studies have included all of them in realistic three-dimensional models. In the present study, we apply a recently developed simulation model to incorporate these components and analyze the flow in a thrombotic tubular arteriole, particularly the detailed hydrodynamic interactions between the thrombus shape, RBCs and platelets. It was found that at certain azimuth positions, the velocity drops in the proximity of both the upstream and downstream edge of the thrombus, which is accompanied by a rapid velocity increase in the narrowed region. The RBCs alter the flow profiles significantly from the typical low Reynolds (Re number flow, and also enhance the deposition of free flowing platelets onto the thrombus. By evaluating the platelet-thrombus interaction and platelet-RBC interaction together, several mechanisms of platelet deposition augmentation are identified. With in vivo data comparison, our model illustrates the potential of future thrombosis studies that incorporate detailed receptor-ligand adhesion modules.

  1. Quantification of volume, mass, and density of thrombus formation using brightfield and differential interference contrast microscopy (United States)

    Baker-Groberg, Sandra M.; Phillips, Kevin G.; McCarty, Owen J. T.


    Flow chamber assays, in which blood is perfused over surfaces of immobilized extracellular matrix proteins, are used to investigate the formation of platelet thrombi and aggregates under shear flow conditions. Elucidating the dynamic response of thrombi/aggregate formation to different coagulation pathway perturbations in vitro has been used to develop an understanding of normal and pathological cardiovascular states. Current microscopy techniques, such as differential interference contrast (DIC) or fluorescent confocal imaging, respectively, do not provide a simple, quantitative understanding of the basic physical features (volume, mass, and density) of platelet thrombi/aggregate structures. The use of two label-free imaging techniques applied, for the first time, to platelet aggregate and thrombus formation are introduced: noninterferometric quantitative phase microscopy, to determine mass, and Hilbert transform DIC microscopy, to perform volume measurements. Together these techniques enable a quantitative biophysical characterization of platelet aggregates and thrombi formed on three surfaces: fibrillar collagen, fibrillar collagen +0.1 nM tissue factor (TF), and fibrillar collagen +1 nM TF. It is demonstrated that label-free imaging techniques provide quantitative insight into the mechanisms by which thrombi and aggregates are formed in response to exposure to different combinations of procoagulant agonists under shear flow.

  2. Prevention of occlusive arterial thrombus formation by a single loading dose of prasugrel suppresses neointimal hyperplasia in mice. (United States)

    Ohno, Kousaku; Tomizawa, Atsuyuki; Jakubowski, Joseph A; Mizuno, Makoto; Sugidachi, Atsuhiro


    The present study examined the effects of prasugrel in a mouse model of thrombosis-induced neointimal hyperplasia. Following carotid artery injury by application of ferric chloride solution, thrombus formation was assessed on Day 1 and neointimal thickening was assessed on Day 21. Single administrations of prasugrel at 0.3-3mg/kg (p.o.) resulted in a dose-related and sustained inhibition of ADP-induced platelet aggregation through 24h. Single and multiple (1 and 3 weeks) administration of prasugrel (3mg/kg loading and 1mg/kg/day maintenance doses) resulted in a marked inhibition of neointimal thickening in the injured artery. In the dose-response study, a single administration of prasugrel at 0.3-3mg/kg (p.o.) dose-relatedly inhibited thrombus formation and neointimal thickening on Days 1 and 21, respectively. The degree of neointimal hyperplasia in the injured artery correlated significantly with the thrombus indices, time to occlusion and patency rate. To explore possible mechanisms of inhibition of neointimal hyperplasia by prasugrel, mRNA expression levels of inflammatory and fibrosis markers were determined in injured arteries. Prasugrel treatment resulted in reduced MCP-1, ICAM-1 and TGF-β mRNA levels on Day 2 (24h after the injury) and Day 8 (1 week after the injury) in the target arteries. In conclusion, we found that a single oral loading dose of prasugrel markedly prevented neointimal hyperplasia by inhibiting platelet activation and thrombus formation and was associated with inhibition of the expression of inflammatory and fibrosis markers, including MCP-1, ICAM-1 and TGF-β, in the injured arteries.

  3. Complementary roles of glycoprotein VI and alpha2beta1 integrin in collagen-induced thrombus formation in flowing whole blood ex vivo

    DEFF Research Database (Denmark)

    Kuijpers, Marijke J E; Schulte, Valerie; Bergmeier, Wolfgang


    Platelets interact vigorously with subendothelial collagens that are exposed by injury or pathological damage of a vessel wall. The collagen-bound platelets trap other platelets to form aggregates, and they expose phosphatidylserine (PS) required for coagulation. Both processes are implicated...... in the formation of vaso-occlusive thrombi. We previously demonstrated that the immunoglobulin receptor glycoprotein VI (GPVI), but not integrin alpha2beta1, is essential in priming platelet-collagen interaction and subsequent aggregation. Here, we report that these receptors have yet a complementary function...... in ex vivo thrombus formation during perfusion of whole blood over collagen. With mice deficient in GPVI or blocking antibodies, we found that GPVI was indispensable for collagen-dependent Ca2+ mobilization, exposure of PS, and aggregation of platelets. Deficiency of integrin beta1 reduces the GPVI...

  4. Left ventricular thrombus formation after repair of anomalous left coronary artery from the pulmonary artery. (United States)

    Freud, Lindsay R; Koenig, Peter R; Russell, Hyde M; Patel, Angira


    Although thrombus formation following myocardial infarction in adults is well known, intracardiac thrombosis in children is uncommon. We report the case of a large left ventricular thrombus in an infant with ischemic cardiomyopathy secondary to anomalous origin of the left coronary artery from the pulmonary artery. Given its mobility and protrusion across the aortic valve, the patient underwent urgent thrombus removal through a transaortic approach. There were no embolic or neurologic complications. This case highlights that thrombectomy may be performed safely and successfully in critically ill pediatric patients.

  5. Left Ventricular Thrombus Formation After Repair of Anomalous Left Coronary Artery From the Pulmonary Artery (United States)

    Freud, Lindsay R.; Koenig, Peter R.; Russell, Hyde M.; Patel, Angira


    Although thrombus formation following myocardial infarction in adults is well known, intracardiac thrombosis in children is uncommon. We report the case of a large left ventricular thrombus in an infant with ischemic cardiomyopathy secondary to anomalous origin of the left coronary artery from the pulmonary artery. Given its mobility and protrusion across the aortic valve, the patient underwent urgent thrombus removal through a transaortic approach. There were no embolic or neurologic complications. This case highlights that thrombectomy may be performed safely and successfully in critically ill pediatric patients. PMID:24668990

  6. Left ventricular thrombus formation after acute myocardial infarction as assessed by cardiovascular magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Delewi, Ronak [Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Interuniversity Cardiology Institute of the Netherlands (Netherlands); Nijveldt, Robin [Department of Cardiology, VU University Medical Center, Amsterdam (Netherlands); Hirsch, Alexander [Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Marcu, Constantin B.; Robbers, Lourens [Department of Cardiology, VU University Medical Center, Amsterdam (Netherlands); Hassell, Marriela E.C.J.; Bruin, Rianne H.A. de; Vleugels, Jim; Laan, Anja M. van der; Bouma, Berto J. [Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Tio, René A. [Thorax Center, University Medical Center Groningen, Groningen (Netherlands); Tijssen, Jan G.P. [Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Rossum, Albert C. van [Department of Cardiology, VU University Medical Center, Amsterdam (Netherlands); Zijlstra, Felix [Thorax Center, Department of Cardiology, Erasmus University Medical Center, Rotterdam (Netherlands); Piek, Jan J., E-mail: [Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands)


    Introduction: Left ventricular (LV) thrombus formation is a feared complication of myocardial infarction (MI). We assessed the prevalence of LV thrombus in ST-segment elevated MI patients treated with percutaneous coronary intervention (PCI) and compared the diagnostic accuracy of transthoracic echocardiography (TTE) to cardiovascular magnetic resonance imaging (CMR). Also, we evaluated the course of LV thrombi in the modern era of primary PCI. Methods: 200 patients with primary PCI underwent TTE and CMR, at baseline and at 4 months follow-up. Studies were analyzed by two blinded examiners. Patients were seen at 1, 4, 12, and 24 months for assessment of clinical status and adverse events. Results: On CMR at baseline, a thrombus was found in 17 of 194 (8.8%) patients. LV thrombus resolution occurred in 15 patients. Two patients had persistence of LV thrombus on follow-up CMR. On CMR at four months, a thrombus was found in an additional 12 patients. In multivariate analysis, thrombus formation on baseline CMR was independently associated with, baseline infarct size (g) (B = 0.02, SE = 0.02, p < 0.001). Routine TTE had a sensitivity of 21–24% and a specificity of 95–98% compared to CMR for the detection of LV thrombi. Intra- and interobserver variation for detection of LV thrombus were lower for CMR (κ = 0.91 and κ = 0.96) compared to TTE (κ = 0.74 and κ = 0.53). Conclusion: LV thrombus still occurs in a substantial amount of patients after PCI-treated MI, especially in larger infarct sizes. Routine TTE had a low sensitivity for the detection of LV thrombi and the interobserver variation of TTE was large.

  7. The effect of factor VIII deficiencies and replacement and bypass therapies on thrombus formation under venous flow conditions in microfluidic and computational models.

    Directory of Open Access Journals (Sweden)

    Abimbola A Onasoga-Jarvis

    Full Text Available Clinical evidence suggests that individuals with factor VIII (FVIII deficiency (hemophilia A are protected against venous thrombosis, but treatment with recombinant proteins can increase their risk for thrombosis. In this study we examined the dynamics of thrombus formation in individuals with hemophilia A and their response to replacement and bypass therapies under venous flow conditions. Fibrin and platelet accumulation were measured in microfluidic flow assays on a TF-rich surface at a shear rate of 100 s⁻¹. Thrombin generation was calculated with a computational spatial-temporal model of thrombus formation. Mild FVIII deficiencies (5-30% normal levels could support fibrin fiber formation, while severe (1 nM, but too low to support fibrin formation (<10 nM. In the absence of platelets, fibrin formation was not supported even at normal FVIII levels, suggesting platelet adhesion is necessary for fibrin formation. Individuals treated by replacement therapy, recombinant FVIII, showed normalized fibrin formation. Individuals treated with bypass therapy, recombinant FVIIa, had a reduced lag time in fibrin formation, as well as elevated fibrin accumulation compared to healthy controls. Treatment of rFVIIa, but not rFVIII, resulted in significant changes in fibrin dynamics that could lead to a prothrombotic state.

  8. Visualization and analysis of biomaterial-centered thrombus formation within a defined crevice under flow. (United States)

    Jamiolkowski, Megan A; Pedersen, Drake D; Wu, Wei-Tao; Antaki, James F; Wagner, William R


    The blood flow pathway within a device, together with the biomaterial surfaces and status of the patient's blood, are well-recognized factors in the development of thrombotic deposition and subsequent embolization. Blood flow patterns are of particular concern for devices such as blood pumps (i.e. ventricular assist devices, VADs) where shearing forces can be high, volumes are relatively large, and the flow fields can be complex. However, few studies have examined the effect of geometric irregularities on thrombus formation on clinically relevant opaque materials under flow. The objective of this study was to quantify human platelet deposition onto Ti6Al4V alloys, as well as positive and negative control surfaces, in the region of defined crevices (∼50-150 μm in width) that might be encountered in many VADs or other cardiovascular devices. To achieve this, reconstituted fresh human blood with hemoglobin-depleted red blood cells (to achieve optical clarity while maintaining relevant rheology), long working optics, and a custom designed parallel plate flow chamber were employed. The results showed that the least amount of platelet deposition occurred in the largest crevice size examined, which was counterintuitive. The greatest levels of deposition occurred in the 90 μm and 53 μm crevices at the lower wall shear rate. The results suggest that while crevices may be unavoidable in device manufacturing, the crevice size might be tailored, depending on the flow conditions, to reduce the risk of thromboembolic events. Further, these data might be used to improve the accuracy of predictive models of thrombotic deposition in cardiovascular devices to help optimize the blood flow path and reduce device thrombogenicity.

  9. A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms. (United States)

    Malaspinas, O; Turjman, A; Ribeiro de Sousa, D; Garcia-Cardena, G; Raes, M; Nguyen, P-T T; Zhang, Y; Courbebaisse, G; Lelubre, C; Zouaoui Boudjeltia, K; Chopard, B


    We propose a new numerical model to describe thrombus formation in cerebral aneurysms. This model combines CFD simulations with a set of bio-mechanical processes identified as being the most important to describe the phenomena at a large space and time scales. The hypotheses of the model are based on in vitro experiments and clinical observations. We document that we can reproduce very well the shape and volume of patient specific thrombus segmented in giant aneurysms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near-infrared light. (United States)

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu


    Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near-infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750 nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200 s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750 nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780 rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump.

  11. Early Heparin Administration Reduces Risk for Left Atrial Thrombus Formation during Atrial Fibrillation Ablation Procedures

    Directory of Open Access Journals (Sweden)

    Stefan Asbach


    Full Text Available Objective. Despite the use of anticoagulation during left atrial (LA ablation procedures, ischemic cerebrovascular accidents (CVAs are recognized as a serious complication. Heparin is usually given after safe transseptal access has been obtained, resulting in a short unprotected dwell time of catheters within the LA, which may account for CVAs. We investigated the frequency of CVAs and LA thrombus formation as detected by intracardiac ultrasound (ICE depending on the timing of heparin administration. Methods and Results. Sixty LA ablation procedures with the use of ICE were performed in 55 patients. Patients were grouped by heparin administration after (Group I, =13 and before (Group II, =47 transseptal access. Group I patients were younger (56.6±13.7 versus 65.9±9.9 years, =.01; other clinical and echocardiographic characteristics did not differ between groups. Early thrombus formation was observed in 2 (15.4% of group I patients as compared to 0% of group II patients (=.04. One CVA (2.1% occurred in one group II patient without prior thrombus detection, and none occurred in group I patients (=ns. Conclusion. Early administration of heparin reduces the risk of early intracardiac thrombus formation during LA ablation procedures. This did not result in reduced rate of CVAs.

  12. Endogenous Fibrinolysis: An Important Mediator of Thrombus Formation and Cardiovascular Risk. (United States)

    Okafor, Osita N; Gorog, Diana A


    Most acute cardiovascular events are attributable to arterial thrombosis. Plaque rupture or erosion stimulates platelet activation, aggregation, and thrombosis, whilst simultaneously activating enzymatic processes that mediate endogenous fibrinolysis to physiologically maintain vessel patency. Interplay between these pathways determines clinical outcome. If proaggregatory factors predominate, the thrombus may propagate, leading to vessel occlusion. However, if balanced by a healthy fibrinolytic system, thrombosis may not occur or cause lasting occlusion. Despite abundant evidence for the fibrinolytic system regulating thrombosis, it has been overlooked compared with platelet reactivity, partly due to a lack of techniques to measure it. We evaluate evidence for endogenous fibrinolysis in arterial thrombosis and review techniques to assess it, including biomarkers and global assays, such as thromboelastography and the Global Thrombosis Test. Global assays, simultaneously assessing proaggregatory and fibrinolytic pathways, could play a role in risk stratification and in identifying impaired fibrinolysis as a potential target for pharmacological modulation.

  13. The Use of Fluid Mechanics to Predict Regions of Microscopic Thrombus Formation in Pulsatile VADs. (United States)

    Topper, Stephen R; Navitsky, Michael A; Medvitz, Richard B; Paterson, Eric G; Siedlecki, Christopher A; Slattery, Margaret J; Deutsch, Steven; Rosenberg, Gerson; Manning, Keefe B


    We compare the velocity and shear obtained from particle image velocimetry (PIV) and computational fluid dynamics (CFD) in a pulsatile ventricular assist device (VAD) to further test our thrombus predictive methodology using microscopy data from an explanted VAD. To mimic physiological conditions in vitro, a mock circulatory loop is used with a blood analog that matched blood's viscoelastic behavior at 40% hematocrit. Under normal physiologic pressures and for a heart rate of 75 bpm, PIV data is acquired and wall shear maps are produced. The resolution of the PIV shear rate calculations are tested using the CFD and found to be in the same range. A bovine study, using a model of the 50 cc Penn State V-2 VAD, for 30 days at a constant beat rate of 75 beats per minute (bpm) provides the microscopic data whereby after the 30 days, the device is explanted and the sac surface analyzed using scanning electron microscopy (SEM) and, after immunofluorescent labeling for platelets and fibrin, confocal microscopy. Areas are examined based on PIV measurements and CFD, with special attention to low shear regions where platelet and fibrin deposition are most likely to occur. Data collected within the outlet port in a direction normal to the front wall of the VAD shows that some regions experience wall shear rates less than 500 s(-1), which increases the likelihood of platelet and fibrin deposition. Despite only one animal study, correlations between PIV, CFD, and in vivo data show promise. Deposition probability is quantified by the thrombus susceptibility potential, a calculation to correlate low shear and time of shear with deposition.

  14. Rare occurrence of simultaneous coronary artery perforation and intracoronary thrombus formation following angioplasty

    Institute of Scientific and Technical Information of China (English)

    Su-Yan Bian; Liu-Fa Duan


    Both coronary artery perforation and intracoronary thrombus formation are life-threatening complications of percutaneous coronary interventions, which rarely occur simultaneously during angioplasty. We herein report a case of stent-related, left circumflex artery perforation, and subsequently acute left main artery thrombosis after the leakage was embolized with 7 microcoils. Intracoronary thromboectomy and systemic anticoagulant therapy were carefully used with good results. This case also represents some of our uncertainties regarding the best management of the patient.

  15. Formation of a Tunnel under the Major Hepatic Vein Mouths during Removal of IVC Tumor Thrombus

    Directory of Open Access Journals (Sweden)

    Dmytro Shchukin


    Full Text Available This study describes a clinical observation of successful implementation of a new surgical maneuver: formation of a cross tunnel under the mouths of the major hepatic veins during removal of a tumor thrombus of the inferior vena cava. This surgical technique helps avoid the usage of   “piggyback” mobilization of the liver and the complications associated with it. However, for objective evaluation of this approach, a further clinical study is required.

  16. Nicorandil prevents sirolimus-induced production of reactive oxygen species, endothelial dysfunction, and thrombus formation

    Directory of Open Access Journals (Sweden)

    Ken Aizawa


    Full Text Available Sirolimus (SRL is widely used to prevent restenosis after percutaneous coronary intervention. However, its beneficial effect is hampered by complications of thrombosis. Several studies imply that reactive oxygen species (ROS play a critical role in endothelial dysfunction and thrombus formation. The present study investigated the protective effect of nicorandil (NIC, an anti-angina agent, on SRL-associated thrombosis. In human coronary artery endothelial cells (HCAECs, SRL stimulated ROS production, which was prevented by co-treatment with NIC. The preventive effect of NIC on ROS was abolished by 5-hydroxydecanoate but not by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. NIC also inhibited SRL-induced up-regulation of NADPH oxidase subunit p22phox mRNA. Co-treatment with NIC and SRL significantly up-regulated superoxide dismutase 2. NIC treatment significantly improved SRL-induced decrease in viability of HCAECs. The functional relevance of the preventive effects of NIC on SRL-induced ROS production and impairment of endothelial viability was investigated in a mouse model of thrombosis. Pretreatment with NIC inhibited the SRL-induced acceleration of FeCl3-initiated thrombus formation and ROS production in the testicular arteries of mice. In conclusion, NIC prevented SRL-induced thrombus formation, presumably due to the reduction of ROS and to endothelial protection. The therapeutic efficacy of NIC could represent an additional option in the prevention of SRL-related thrombosis.

  17. Platelet thrombosis in cardiac-valve prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Dewanjee, M.K.


    The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs.

  18. Association between inflammatory mediators and angiographic morphologic features indicating thrombus formation in patients with acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    LI Dong-bao; HUA Qi; LIU Zhi; LI Jing; XU Li-qing; WANG Shan; JIN Wei-ying


    Background Inflammatory mechanisms had played an important role in the occurrence and prognosis of acute myocardial infarction,inflammatory mediators was associated with adverse outcomes of acute myocardial infarction.This study tested the hypothesis that in the acute phase of myocardial infarction with ST-segment elevation,neutrophil count and high-sensitivity C-reactive protein are predictive of angiographic morphologic features that indicate thrombus formation in the infarct-related artery.Methods This retrospective study included 182 consecutive patients with acute myocardial infarction and ST-segment elevation.Patients were assigned to a thrombus-formation group(n=77)and a non-thrombus-formation group(n=106).All patients had a Killip's classification≤3 and onset<12 hours prior to presentation.All the cases were going to undergo coronary angiography,including primary percutaneous coronary intervention,simple coronary angiography,or thrombolysis in a coronary artery(or arteries)or coronary artery bypass graft(s).Blood samples for measurement of high-sensitivity C-reactive protein and for routine blood laboratory studies were collected prior to coronary angiography.Results The levels of high-sensitivity C-reactive protein,total leukocyte counts,neutrophil counts,and neutrophil/lymphocyte ratios were substantially higher in the thrombus-formation group than in the non-thrombus-formation group patients(for each,P<0.05).Stepwise Logistic regression analyses identified high-sensitivity C-reactive protein,neutrophil count,and neutrophil/lymphocyte ratio as independent predictors of thrombus formation in the infarct-related artery(for each,P<0.05).Conclusions In patients with acute myocardial infarction,higher neutrophil counts,neutrophil/lymphocyte ratio,and levels of high-sensitivity C-reactive protein are predictors to indicate thrombus formation.

  19. Investigation of the thrombin-generating capacity, evaluated by thrombogram, and clot formation evaluated by thrombelastography of platelets stored in the blood bank for up to 7 days

    DEFF Research Database (Denmark)

    Johansson, Per Ingemar; Svendsen, M.S.; Salado, J.


    thrombin) and endogenous thrombin potential (ETP; nm thrombin*min) were registered. Clot formation was evaluated by TEG and the R time (min), maxial amplitude (MA; mm), time to maximum thrombus generation (TMG; min) and maximum thrombus generation (MTG; dynes cm(-2) s(-1)) and total thrombus generation...... (TTG; dyne cm(-2)) were registered. RESULTS: Platelets become more procoagulant, evaluated both by TEG and CAT during storage. The reduction in CAT lag time and the ttPeak correlated with a decrease in the TEG R time and TMG (P ....0035). No correlation between ETP and TTG was found (P = 0.65). CONCLUSION: The kinetics of thrombin generation, as evaluated by CAT, correlates with the thrombus generation, as evaluated by thrombelastography and this may in part explain the clinical utility of the TEG in identifying clinically relevant coagulopathies...

  20. Mice lacking the SLAM family member CD84 display unaltered platelet function in hemostasis and thrombosis.

    Directory of Open Access Journals (Sweden)

    Sebastian Hofmann

    Full Text Available BACKGROUND: Platelets are anuclear cell fragments derived from bone marrow megakaryocytes that safeguard vascular integrity by forming thrombi at sites of vascular injury. Although the early events of thrombus formation--platelet adhesion and aggregation--have been intensively studied, less is known about the mechanisms and receptors that stabilize platelet-platelet interactions once a thrombus has formed. One receptor that has been implicated in this process is the signaling lymphocyte activation molecule (SLAM family member CD84, which can undergo homophilic interactions and becomes phosphorylated upon platelet aggregation. OBJECTIVE: The role of CD84 in platelet physiology and thrombus formation was investigated in CD84-deficient mice. METHODS AND RESULTS: We generated CD84-deficient mice and analyzed their platelets in vitro and in vivo. Cd84(-/- platelets exhibited normal activation and aggregation responses to classical platelet agonists. Furthermore, CD84 deficiency did not affect integrin-mediated clot retraction and spreading of activated platelets on fibrinogen. Notably, also the formation of stable three-dimensional thrombi on collagen-coated surfaces under flow ex vivo was unaltered in the blood of Cd84(-/- mice. In vivo, Cd84(-/- mice exhibited unaltered hemostatic function and arterial thrombus formation. CONCLUSION: These results show that CD84 is dispensable for thrombus formation and stabilization, indicating that its deficiency may be functionally compensated by other receptors or that it may be important for platelet functions different from platelet-platelet interactions.

  1. Does ultrasound influence experimentally induced thrombus formation in the central artery of the rabbit ear? (United States)

    Nordquist, J; Carlson, J; Dougan, P; Olsson, S B; Salemark, L


    Thrombosis is one of the most important causes of morbidity in the medical field. Several independent in vitro studies have shown that the fibrinolytic process may be enhanced by ultrasound, but the effect of ultrasound on thrombus formation in vivo is unexplored. The present study was designed to investigate this matter. In a blind randomized study, standardized arteriotomies and intimectomies were performed on the central arteries of the ears of 25 rabbits. The rabbits were allocated to two groups, an untreated control group and a group treated with ultrasound (10 pulses of frequency 1 MHz and intensity 1 W/cm(2) per millisecond giving an averaged intensity of 0.01 W/cm(2)). Immediately after reperfusion, patency was confirmed by a manual empty/refill test, after which blood-flow was monitored using ultrasonic flow-probes twice a minute for two hours. At two hours, patency was rechecked. All vessels were patent at reperfusion, but only seven vessels (three control, four treated) were patent when flow-rate measurements started. At 2 h, patency-frequencies were 12/23 in the control group and 11/22 in the treated group. Flow-rate curves in patent vessels in both groups were similar. Microscopic investigation at one week showed no difference in thrombus accumulation. Ultrasound with the above characteristics does not significantly improve patency in vivo.

  2. Image-based characterization of thrombus formation in time-lapse DIC microscopy. (United States)

    Brieu, Nicolas; Navab, Nassir; Serbanovic-Canic, Jovana; Ouwehand, Willem H; Stemple, Derek L; Cvejic, Ana; Groher, Martin


    The characterization of thrombus formation in time-lapse DIC microscopy is of increased interest for identifying genes which account for atherothrombosis and coronary artery diseases (CADs). In particular, we are interested in large-scale studies on zebrafish, which result in large amount of data, and require automatic processing. In this work, we present an image-based solution for the automatized extraction of parameters quantifying the temporal development of thrombotic plugs. Our system is based on the joint segmentation of thrombotic and aortic regions over time. This task is made difficult by the low contrast and the high dynamic conditions observed in vivo DIC microscopic scenes. Our key idea is to perform this segmentation by distinguishing the different motion patterns in image time series rather than by solving standard image segmentation tasks in each image frame. Thus, we are able to compensate for the poor imaging conditions. We model motion patterns by energies based on the idea of dynamic textures, and regularize the model by two prior energies on the shape of the aortic region and on the topological relationship between the thrombus and the aorta. We demonstrate the performance of our segmentation algorithm by qualitative and quantitative experiments on synthetic examples as well as on real in vivo microscopic sequences.

  3. Complement-induced thrombus formation on the surface of poly(N-vinylpyrrolidone)-grafted polyethylene. (United States)

    Fukumura, H; Hayashi, K; Yoshikawa, S; Miya, M; Yamamoto, N; Yamashita, I


    The role of complement activation in thrombogenesis was investigated on the surface of hydrophilic monomer-graft copolymerized polyethylene (PE) tubes. N-vinylpyrrolidone (NVP)-grafted tubes activated in an in vitro complement system of canine serum; but no activation occurred in 2-hydroxyethyl methacrylate (HEMA)-grafted tubes. The relative patent time for NVP-grafted tubes implanted in canine peripheral veins was shorter than that for HEMA-grafted tubes and adhesion of numerous leucocytes was observed on the luminal surfaces of the NVP-grafted tubes. Decomplementation by prior administration of cobra venom factor elongated the relative patent time for NVP-grafted tubes only and also inhibited the adhesion of leucocytes onto them. These results suggest that the complement activation participates in thrombus formation on the polymer surfaces in canine veins.

  4. Physiopathology of blood platelets and development of platelets substitutes. Progress report, August 1, 1976--October 31, 1977. [/sup 51/Cr

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, M G


    Progress is reported on the following research projects: the effect of estrogen on platelet aggregability and thrombus formation; the antithrombotic effect of platelet inhibiting agents in a bench model of artificial kidney; the arrest of hemorrhage in severely alloimmunized thrombocytopenic patients; and in vivo elution of /sup 51/Cr from labeled platelets induced by antibody. (HLW)

  5. Takotsubo cardiomyopathy complicated with apical thrombus formation on first day of the illness: a case report and literature review. (United States)

    Herath, H M M T B; Pahalagamage, S P; Lindsay, Laura C; Vinothan, S; Withanawasam, Sampath; Senarathne, Vajira; Withana, Milinda


    Takotsubo cardiomyopathy is characterized by transient systolic dysfunction of the apical and mid segments of the left ventricle in the absence of obstructive coronary artery disease. Intraventricular thrombus formation is a rare complication of Takotsubo cardiomyopathy and current data almost exclusively consists of isolated case reports and a few case series. Here we describe a case of Takotsubo cardiomyopathy with formation of an apical thrombus within 24 h of symptom onset, which has been reported in the literature only once previously, to the best of our knowledge. We have reviewed the available literature that may aid clinicians in their approach to the condition, since no published guidelines are available. A 68-year-old Sri Lankan female presented to a local hospital with chest pain. Electrocardiogram (ECG) showed ST elevation, and antiplatelets, intravenous streptokinase and a high dose statin were administered. Despite this ST elevation persisted; however the coronary angiogram was negative for obstructive coronary artery disease. Echocardiogram revealed hypokinesia of the mid and apical segments of the left ventricle with typical apical ballooning and a sizable apical thrombus. She had recently had a viral infection and was also emotionally distressed as her sister was recently diagnosed with a terminal cancer. A diagnosis of Takotsubo cardiomyopathy was made and anticoagulation was started with heparin and warfarin. The follow up echocardiogram performed 1 week later revealed a small persistent thrombus, which had completely resolved at 3 weeks. Though severe systolic dysfunction is observed in almost all the patients with Takotsubo cardiomyopathy, intraventricular thrombus formation on the first day of the illness is rare. The possibility of underdiagnosis of thrombus can be prevented by early echocardiogram in Takotsubo cardiomyopathy. The majority of reports found in the literature review were of cases that had formed an intraventriclar thrombus

  6. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev


    Full Text Available Platelets are anuclear cell fragments playing important role in hemostasis, termination of bleeding after damage, as well as in pathological thrombus formation. The main action of platelets is the formation of aggregates, overlapping the injury. They obtained the ability to aggregate by the transition process called activation. Despite the relatively simple and definite function platelet structure is very difficult: they have almost a full set of organelles, including the endoplasmic reticulum, mitochondria and other entities. When activated platelets secrete various granules interact with plasma proteins and red blood cells and other tissues. Their activation is controlled by multiple receptors and complex signaling cascades. In this review platelet structure, mechanisms of its functioning in health and disease, diagnostic methods of platelet function and approaches to their correction were considered. Particular attention will be given to those areas of the science of platelets, which still lay hidden mysteries.

  7. Intracoronary thrombus. (United States)

    Achenbach, Stephan; Marwan, Mohamed


    We present the case of a 62 year old patient admitted with acute chest pain. Coronary CT angiography demonstrated presence of a high grade lesion with pronounced remodeling and the impression of an intracoronary thrombus in the proximal left circumflex coronary artery. Invasive angiography confirmed the presence of a thrombus; thrombus fragments were removed using an extraction device.

  8. Congestive cardiomyopathy and left ventricular thrombus. (United States)

    Gould, L; Gopalaswamy, C; Chandy, F; Kim, B S


    A left ventricular thrombus was detected by echocardiography in a 54-year-old man with congestive cardiomyopathy. With the use of anticoagulants, the thrombus completely disappeared. Patients with congestive cardiomyopathy who are at high risk for thrombus formation should be screened with two-dimensional echocardiography. If a thrombus is recognized, anticoagulation therapy can then be instituted.

  9. Evaluation of triple anti-platelet therapy by modified thrombelastography in patients with acute coronary syndrome

    Institute of Scientific and Technical Information of China (English)

    REN Yi-hong; JIN Jing; XIN You-hong; LI Rong-bin; LI Hai-yan; LIN Lin; LIU Chun-xue; YANG Ting-shu; WANG Yu; GAI Lu-yue; LIU Hong-bin; CHEN Lian; WANG Hong-ye; WANG Chun-ya; XU Xiu-li


    @@ Most cases of acute coronary syndrome (ACS) involve coronary atherosclerosis and plaque rupture,as well as subsequent thrombosis. The initial thrombotic events leading to red thrombus formation are platelet adherence and aggregation.

  10. Computational analysis on the mechanical interaction between a thrombus and red blood cells: possible causes of membrane damage of red blood cells at microvessels. (United States)

    Kamada, Hiroki; Imai, Yohsuke; Nakamura, Masanori; Ishikawa, Takuji; Yamaguchi, Takami


    Previous studies investigating thrombus formation have not focused on the physical interaction between red blood cells (RBCs) and thrombus, although they have been speculated that some pathological conditions such as microangiopathic hemolytic anemia (MAHA) stem from interactions between RBCs and thrombi. In this study, we investigated the mechanical influence of RBCs on primary thrombi during hemostasis. We also explored the mechanics and aggravating factors of intravascular hemolysis. Computer simulations of primary thrombogenesis in the presence and the absence of RBCs demonstrated that RBCs are unlikely to affect the thrombus height and coverage, although their presence may change microvessel hemodynamics and platelet transportation to the injured wall. Our results suggest that intravascular hemolysis owing to RBC membrane damage would be promoted by three hemodynamic factors: (1) dispersibility of platelet thrombi, because more frequent spatial thrombus formation decreases the time available for an RBC to recover its shape and enforces more severe deformation; (2) platelet thrombus stiffness, because a stiffer thrombus increases the degree of RBC deformation upon collision; and (3) vessel size and hemocyte density, because a smaller vessel diameter and higher hemocyte density decrease the room for RBCs to escape as they come closer to a thrombus, thereby enhancing thrombus-RBC interactions.

  11. Diagnosis and treatment of early bioprosthetic malfunction in the mitral valve position due to thrombus formation. (United States)

    Butnaru, Adi; Shaheen, Joseph; Tzivoni, Dan; Tauber, Rachel; Bitran, Daniel; Silberman, Shuli


    Bioprosthetic valve thrombosis is uncommon and the diagnosis is often elusive and may be confused with valve degeneration. We report our experience with mitral bioprosthetic valve thrombosis and suggest a therapeutic approach. From 2002 to 2011, 149 consecutive patients who underwent mitral valve replacement with a bioprosthesis at a single center were retrospectively screened for clinical or echocardiographic evidence of valve malfunction. Nine were found to have valve thrombus. All 9 patients had their native valve preserved, representing 24% of those with preserved native valves. Five patients (group 1) presented with symptoms of congestive heart failure at 16.4 ± 12.4 months after surgery. Echocardiogram revealed homogenous echo-dense film on the ventricular surface of the bioprosthesis with elevated transvalvular gradient, resembling early degeneration. The first 2 patients underwent reoperation: valve thrombus was found and confirmed by histologic examination. Based on these, the subsequent 3 patients received anticoagulation treatment with complete thrombus resolution: mean mitral gradient decreased from 23 ± 4 to 6 ± 1 mm Hg and tricuspid regurgitation gradient decreased from 83 ± 20 to 49 ± 5 mm Hg. Four patients (group 2) were asymptomatic, but routine echocardiogram showed a discrete mass on the ventricular aspect of the valve: 1 underwent reoperation to replace the valve and 3 received anticoagulation with complete resolution of the echocardiographic findings. In conclusion, bioprosthetic mitral thrombosis occurs in about 6% of cases. In our experience, onset is early, before anticipated valve degeneration. Clinical awareness followed by an initial trial with anticoagulation is warranted. Surgery should be reserved for those who are not responsive or patients in whom the hemodynamic status does not allow delay. Nonresection of the native valve at the initial operation may play a role in the origin of this entity.

  12. Segmentation, Reconstruction, and Analysis of Blood Thrombus Formation in 3D 2-Photon Microscopy Images

    Directory of Open Access Journals (Sweden)

    Xu Zhiliang


    Full Text Available We study the problem of segmenting, reconstructing, and analyzing the structure growth of thrombi (clots in blood vessels in vivo based on 2-photon microscopic image data. First, we develop an algorithm for segmenting clots in 3D microscopic images based on density-based clustering and methods for dealing with imaging artifacts. Next, we apply the union-of-balls (or alpha-shape algorithm to reconstruct the boundary of clots in 3D. Finally, we perform experimental studies and analysis on the reconstructed clots and obtain quantitative data of thrombus growth and structures. We conduct experiments on laser-induced injuries in vessels of two types of mice (the wild type and the type with low levels of coagulation factor VII and analyze and compare the developing clot structures based on their reconstructed clots from image data. The results we obtain are of biomedical significance. Our quantitative analysis of the clot composition leads to better understanding of the thrombus development, and is valuable to the modeling and verification of computational simulation of thrombogenesis.

  13. An integrated fluid-chemical model towards modeling the formation of intra-luminal thrombus in abdominal aortic aneurysms

    Directory of Open Access Journals (Sweden)

    Jacopo eBiasetti


    Full Text Available Abdominal Aortic Aneurysms (AAAs are frequently characterized by the presenceof an Intra-Luminal Thrombus (ILT known to influence biochemically and biomechanicallytheir evolution. ILT progression mechanism is still unclear and little is known regardingthe impact on this mechanism of the chemical species transported by blood flow.Chemical agonists and antagonists of platelets activation, aggregation, and adhesion andthe proteins involved in the coagulation cascade (CC may play an important role in ILTdevelopment. Starting from this assumption, the evolution of chemical species involvedin the CC, their relation to coherent vortical structures (VSs and their possible effect onILT evolution have been studied. To this end a fluido-chemical model that simulates theCC through a series of convection-diffusion-reaction (CDR equations has been developed.The model involves plasma-phase and surface bound enzymes and zymogens, and includesboth plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonianincompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinicalobservations showing that the thickest ILT is usually seen in the distal AAA region. Theproposed model, due to its ability to couple the fluid and chemical domains, provides anintegrated mechanochemical picture that potentially could help unveil mechanisms of ILTformation and development.

  14. Effect of Metabolic Syndrome on Risk Stratification for Left Atrial or Left Atrial Appendage Thrombus Formation in Patients with Nonvalvular Atrial Fibrillation (United States)

    Chen, Yu-Yang; Liu, Qi; Liu, Li; Shu, Xiao-Rong; Su, Zi-Zhuo; Zhang, Hai-Feng; Nie, Ru-Qiong; Wang, Jing-Feng; Xie, Shuang-Lun


    Background: Metabolic syndrome (MS) is a risk factor for stroke and thromboembolism event. Left atrial or LA appendage (LA/LAA) thrombus is a surrogate of potential stroke. The relationship between MS and atrial thrombus remains unclear. In this study, we sought to investigate the effect of MS on risk stratification of LA/LAA thrombus formation in patients with nonvalvular atrial fibrillation (NVAF). Methods: This cross-sectional study enrolled 294 consecutive NVAF patients without prior anticoagulant and lipid-lowering therapies. LA/LAA thrombus was determined by transesophageal echocardiography. Risk assessment of LA/LAA thrombus was performed using the CHADS2, CHA2DS2-VASc, MS, CHADS2-MS, and CHA2DS2-VASc-MS scores. Logistic regression analyses were performed to determine which factors were significantly related to LA/LAA thrombus. Odds ratio (OR) including 95% confidence interval was also calculated. The predictive powers of different scores for the risk of LA/LAA thrombus were represented by C-statistics and compared by receiver operating characteristic (ROC) analysis. Results: LA/LAA thrombi were identified in 56 patients (19.0%). Logistic analysis showed that MS was the strongest risk factor for LA/LAA thrombus in NVAF patients (OR = 14.698, P < 0.001). ROC curve analyses revealed that the C-statistics of CHADS2-MS and CHA2DS2-VASc-MS was significantly higher than those of CHADS2 and CHA2DS2-VASc scores (CHADS2-MS vs. CHADS2, 0.807 vs. 0.726, P = 0.0019). Furthermore, MS was helpful for identifying individuals with a high risk of LA/LAA thrombus in the population with a low risk of stroke (CHADS2 or CHA2DS2-VASc score = 0). Conclusions: MS is associated with LA/LAA thrombus risk in patients with NVAF. In addition to the CHADS2 and CHA2DS2-VASc scores, the CHADS2-MS and CHA2DS2-VASc-MS scores provide additional information on stroke risk assessment. PMID:27748329

  15. Motion of left atrial appendage as a determinant of thrombus formation in patients with a low CHADS2 score receiving warfarin for persistent nonvalvular atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Ono Koji


    Full Text Available Abstract Background The aim of this study was to define the independent determinants of left atrial appendage (LAA thrombus among various echocardiographic parameters measured by Velocity Vector Imaging (VVI in patients with nonvalvular atrial fibrillation (AF receiving warfarin, particularly in patients with a low CHADS2 score. Methods LAA emptying fraction (EF and LAA peak longitudinal strain were measured by VVI using transesophageal echocardiography in 260 consecutive patients with nonvalvular persistent AF receiving warfarin. The patients were divided into two groups according to the presence (n=43 or absence (n=217 of LAA thrombus. Moreover, the patients within each group were further divided into subgroups according to a CHADS2 score ≤1. Results Multivariate logistic regression analysis showed that LAAEF was an independent determinant of LAA thrombus in the subgroup of 140 with a low CHADS2 score. Receiver operating characteristics curve analysis showed that an LAAEF of 21% was the optimal cutoff value for predicting LAA thrombus. Conclusions LAA thrombus formation depended on LAA contractility. AF patients with reduced LAA contractile fraction (LAAEF ≤21% require strong anticoagulant therapy to avoid thromboembolic events regardless of a low CHADS2 score (≤1.

  16. New gene functions in megakaryopoiesis and platelet formation (United States)

    Gieger, Christian; Radhakrishnan, Aparna; Cvejic, Ana; Tang, Weihong; Porcu, Eleonora; Pistis, Giorgio; Serbanovic-Canic, Jovana; Elling, Ulrich; Goodall, Alison H.; Labrune, Yann; Lopez, Lorna M.; Mägi, Reedik; Meacham, Stuart; Okada, Yukinori; Pirastu, Nicola; Sorice, Rossella; Teumer, Alexander; Voss, Katrin; Zhang, Weihua; Ramirez-Solis, Ramiro; Bis, Joshua C.; Ellinghaus, David; Gögele, Martin; Hottenga, Jouke-Jan; Langenberg, Claudia; Kovacs, Peter; O’Reilly, Paul F.; Shin, So-Youn; Esko, Tõnu; Hartiala, Jaana; Kanoni, Stavroula; Murgia, Federico; Parsa, Afshin; Stephens, Jonathan; van der Harst, Pim; van der Schoot, C. Ellen; Allayee, Hooman; Attwood, Antony; Balkau, Beverley; Bastardot, François; Basu, Saonli; Baumeister, Sebastian E.; Biino, Ginevra; Bomba, Lorenzo; Bonnefond, Amélie; Cambien, François; Chambers, John C.; Cucca, Francesco; D’Adamo, Pio; Davies, Gail; de Boer, Rudolf A.; de Geus, Eco J. C.; Döring, Angela; Elliott, Paul; Erdmann, Jeanette; Evans, David M.; Falchi, Mario; Feng, Wei; Folsom, Aaron R.; Frazer, Ian H.; Gibson, Quince D.; Glazer, Nicole L.; Hammond, Chris; Hartikainen, Anna-Liisa; Heckbert, Susan R.; Hengstenberg, Christian; Hersch, Micha; Illig, Thomas; Loos, Ruth J. F.; Jolley, Jennifer; Khaw, Kay Tee; Kühnel, Brigitte; Kyrtsonis, Marie-Christine; Lagou, Vasiliki; Lloyd-Jones, Heather; Lumley, Thomas; Mangino, Massimo; Maschio, Andrea; Leach, Irene Mateo; McKnight, Barbara; Memari, Yasin; Mitchell, Braxton D.; Montgomery, Grant W.; Nakamura, Yusuke; Nauck, Matthias; Navis, Gerjan; Nöthlings, Ute; Nolte, Ilja M.; Porteous, David J.; Pouta, Anneli; Pramstaller, Peter P.; Pullat, Janne; Ring, Susan M.; Rotter, Jerome I.; Ruggiero, Daniela; Ruokonen, Aimo; Sala, Cinzia; Samani, Nilesh J.; Sambrook, Jennifer; Schlessinger, David; Schreiber, Stefan; Schunkert, Heribert; Scott, James; Smith, Nicholas L.; Snieder, Harold; Starr, John M.; Stumvoll, Michael; Takahashi, Atsushi; Tang, W. H. Wilson; Taylor, Kent; Tenesa, Albert; Thein, Swee Lay; Tönjes, Anke; Uda, Manuela; Ulivi, Sheila; van Veldhuisen, Dirk J.; Visscher, Peter M.; Völker, Uwe; Wichmann, H.-Erich; Wiggins, Kerri L.; Willemsen, Gonneke; Yang, Tsun-Po; Zhao, Jing Hua; Zitting, Paavo; Bradley, John R.; Dedoussis, George V.; Gasparini, Paolo; Hazen, Stanley L.; Metspalu, Andres; Pirastu, Mario; Shuldiner, Alan R.; van Pelt, L. Joost; Zwaginga, Jaap-Jan; Boomsma, Dorret I.; Deary, Ian J.; Franke, Andre; Froguel, Philippe; Ganesh, Santhi K.; Jarvelin, Marjo-Riitta; Martin, Nicholas G.; Meisinger, Christa; Psaty, Bruce M.; Spector, Timothy D.; Wareham, Nicholas J.; Akkerman, Jan-Willem N.; Ciullo, Marina; Deloukas, Panos; Greinacher, Andreas; Jupe, Steve; Kamatani, Naoyuki; Khadake, Jyoti; Kooner, Jaspal S.; Penninger, Josef; Prokopenko, Inga; Stemple, Derek; Toniolo, Daniela; Wernisch, Lorenz; Sanna, Serena; Hicks, Andrew A.; Rendon, Augusto; Ferreira, Manuel A.; Ouwehand, Willem H.; Soranzo, Nicole


    Platelets are the second most abundant cell type in blood and are essential for maintaining haemostasis. Their count and volume are tightly controlled within narrow physiological ranges, but there is only limited understanding of the molecular processes controlling both traits. Here we carried out a high-powered meta-analysis of genome-wide association studies (GWAS) in up to 66,867 individuals of European ancestry, followed by extensive biological and functional assessment. We identified 68 genomic loci reliably associated with platelet count and volume mapping to established and putative novel regulators of megakaryopoiesis and platelet formation. These genes show megakaryocyte-specific gene expression patterns and extensive network connectivity. Using gene silencing in Danio rerio and Drosophila melanogaster, we identified 11 of the genes as novel regulators of blood cell formation. Taken together, our findings advance understanding of novel gene functions controlling fate-determining events during megakaryopoiesis and platelet formation, providing a new example of successful translation of GWAS to function. PMID:22139419

  17. Where do the platelets go? A simulation study of fully resolved blood flow through aneurysmal vessels

    NARCIS (Netherlands)

    Mountrakis, L.; Lorenz, E.; Hoekstra, A.G.


    Despite the importance of platelets in the formation of a thrombus, their transport in complex flows has not yet been studied in detail. In this paper we simulated red blood cells and platelets to explore their transport behaviour in aneurysmal geometries. We considered two aneurysms with different

  18. Coated platelets function in platelet-dependent fibrin formation via integrin αIIbβ3 and transglutaminase factor XIII. (United States)

    Mattheij, Nadine J A; Swieringa, Frauke; Mastenbroek, Tom G; Berny-Lang, Michelle A; May, Frauke; Baaten, Constance C F M J; van der Meijden, Paola E J; Henskens, Yvonne M C; Beckers, Erik A M; Suylen, Dennis P L; Nolte, Marc W; Hackeng, Tilman M; McCarty, Owen J T; Heemskerk, Johan W M; Cosemans, Judith M E M


    Coated platelets, formed by collagen and thrombin activation, have been characterized in different ways: i) by the formation of a protein coat of α-granular proteins; ii) by exposure of procoagulant phosphatidylserine; or iii) by high fibrinogen binding. Yet, their functional role has remained unclear. Here we used a novel transglutaminase probe, Rhod-A14, to identify a subpopulation of platelets with a cross-linked protein coat, and compared this with other platelet subpopulations using a panel of functional assays. Platelet stimulation with convulxin/thrombin resulted in initial integrin α(IIb)β3 activation, the appearance of a platelet population with high fibrinogen binding, (independently of active integrins, but dependent on the presence of thrombin) followed by phosphatidylserine exposure and binding of coagulation factors Va and Xa. A subpopulation of phosphatidylserine-exposing platelets bound Rhod-A14 both in suspension and in thrombi generated on a collagen surface. In suspension, high fibrinogen and Rhod-A14 binding were antagonized by combined inhibition of transglutaminase activity and integrin α(IIb)β3 Markedly, in thrombi from mice deficient in transglutaminase factor XIII, platelet-driven fibrin formation and Rhod-A14 binding were abolished by blockage of integrin α(IIb)β3. Vice versa, star-like fibrin formation from platelets of a patient with deficiency in α(IIb)β3(Glanzmann thrombasthenia) was abolished upon blockage of transglutaminase activity. We conclude that coated platelets, with initial α(IIb)β3 activation and high fibrinogen binding, form a subpopulation of phosphatidylserine-exposing platelets, and function in platelet-dependent star-like fibrin fiber formation via transglutaminase factor XIII and integrin α(IIb)β3.

  19. In-vitro model for the ultrastructural study of the formation of thrombi in human platelets. (United States)

    Cerecedo, Doris; González, Sirenia; Mondragón, Mónica; Reyes, Elba; Mondragón, Ricardo


    Platelets are cell fragments with dynamic properties involved in clot formation after tissue damage. Platelet activation causes a change in shape, secretion of intracellular granules and aggregation with each other through the cytoskeleton components and biochemical changes. Platelet adhesion, considered as the major event in haemostasis, has been studied in several in-vitro and in-vivo models to evaluate the feasible thrombogenicity of some materials, the dynamics of specific receptors, as well as the effect of different buffers and inhibitors in this process. In spite of the numerous reports about platelet activation, to date there is no information available about the fine structure of the platelet-platelet and platelet-substrate interactions. In the present report we describe an in-vitro system that allows the visualization of these interactions: platelets are adhered to an inert substrate, and interactions with suspended platelets as a process to initiate the formation of thrombi was followed by ultramicrotomy and transmission electron microscopy.

  20. Rho GTPases in platelet function. (United States)

    Aslan, J E; McCarty, O J T


    The Rho family of GTP binding proteins, also commonly referred to as the Rho GTPases, are master regulators of the platelet cytoskeleton and platelet function. These low-molecular-weight or 'small' GTPases act as signaling switches in the spatial and temporal transduction, and amplification of signals from platelet cell surface receptors to the intracellular signaling pathways that drive platelet function. The Rho GTPase family members RhoA, Cdc42 and Rac1 have emerged as key regulators in the dynamics of the actin cytoskeleton in platelets and play key roles in platelet aggregation, secretion, spreading and thrombus formation. Rho GTPase regulators, including GEFs and GAPs and downstream effectors, such as the WASPs, formins and PAKs, may also regulate platelet activation and function. In this review, we provide an overview of Rho GTPase signaling in platelet physiology. Previous studies of Rho GTPases and platelets have had a shared history, as platelets have served as an ideal, non-transformed cellular model to characterize Rho function. Likewise, recent studies of the cell biology of Rho GTPase family members have helped to build an understanding of the molecular regulation of platelet function and will continue to do so through the further characterization of Rho GTPases as well as Rho GAPs, GEFs, RhoGDIs and Rho effectors in actin reorganization and other Rho-driven cellular processes. © 2012 International Society on Thrombosis and Haemostasis.

  1. Blood platelets in the progression of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Nina S Gowert

    Full Text Available Alzheimer's disease (AD is characterized by neurotoxic amyloid-ß plaque formation in brain parenchyma and cerebral blood vessels known as cerebral amyloid angiopathy (CAA. Besides CAA, AD is strongly related to vascular diseases such as stroke and atherosclerosis. Cerebrovascular dysfunction occurs in AD patients leading to alterations in blood flow that might play an important role in AD pathology with neuronal loss and memory deficits. Platelets are the major players in hemostasis and thrombosis, but are also involved in neuroinflammatory diseases like AD. For many years, platelets were accepted as peripheral model to study the pathophysiology of AD because platelets display the enzymatic activities to generate amyloid-ß (Aß peptides. In addition, platelets are considered to be a biomarker for early diagnosis of AD. Effects of Aß peptides on platelets and the impact of platelets in the progression of AD remained, however, ill-defined. The present study explored the cellular mechanisms triggered by Aß in platelets. Treatment of platelets with Aß led to platelet activation and enhanced generation of reactive oxygen species (ROS and membrane scrambling, suggesting enhanced platelet apoptosis. More important, platelets modulate soluble Aß into fibrillar structures that were absorbed by apoptotic but not vital platelets. This together with enhanced platelet adhesion under flow ex vivo and in vivo and platelet accumulation at amyloid deposits of cerebral vessels of AD transgenic mice suggested that platelets are major contributors of CAA inducing platelet thrombus formation at vascular amyloid plaques leading to vessel occlusion critical for cerebrovascular events like stroke.

  2. Platelets (United States)

    ... tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding. Red blood cells are ... forming a long string. This illustrates the basic function of platelets, to stick to any foreign surface and then ...

  3. Current Role of Platelet Glycoprotein Ⅱ b/Ⅲ a Receptor Inhibitors in Clinic-al Trials of Cardiovascular Diseases

    Institute of Scientific and Technical Information of China (English)

    SHEN Di


    @@Thrombosis formation on disrupted atherosclerotic plaque is the most common acuse of cardiovascular dis eases, in the pathophysiology, increased platelet reactiv ity is a descriptor of the risk of cardiovascular events in healthy persons and in patients with overt coronary artery disease. Regardless of the stimulus for activation platelet-platelet interation and thrombus formation is ul timately regulated through the GP Ⅱ b/Ⅲ a receptor complex

  4. Vascular endothelium and platelet preparations for the prediction of xenobiotic effects on the vascular system. (United States)

    Togna, G; Togna, A R; Caprino, L


    Platelets and vascular cells play a fundamental role in the pathogenesis of cardiovascular diseases including thrombus formation and atherosclerotic phenomena. Preparations of platelets and aortic rings have been developed to study the potential of xenobiotics to produce evidence of vascular toxicity in vitro. The xenobiotics cadmium and mercury which exert vascular toxicity in vivo, modify platelet and endothelial-cell reactivity in these in vitro systems.

  5. Gray platelet syndrome and defective thrombo-inflammation in Nbeal2-deficient mice


    Deppermann, Carsten; Cherpokova, Deya; Nurden, Paquita; Schulz, Jan-Niklas; Thielmann, Ina; Kraft, Peter; Vögtle, Timo; Kleinschnitz, Christoph; Dütting, Sebastian; Krohne, Georg; Eming, Sabine A.; Nurden, Alan T; Eckes, Beate; Stoll, Guido; Stegner, David


    Platelets are anuclear organelle-rich cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity. The major platelet organelles, α-granules, release proteins that participate in thrombus formation and hemostasis. Proteins stored in α-granules are also thought to play a role in inflammation and wound healing, but their functional significance in vivo is unknown. Mutations in NBEAL2 have been linked to gray platelet syndrome (GPS), a rare bleeding disorder ch...

  6. Iron-Deficiency Anemia Leading to Transient Ischemic Attacks due to Intraluminal Carotid Artery Thrombus

    Directory of Open Access Journals (Sweden)

    H. Z. Batur Caglayan


    Full Text Available Reactive thrombocytosis secondary to iron-deficiency anemia (IDA is a rare but recognized cause of stroke. We report the case of a patient with iron-deficiency anemia presenting with multiple transient ischemic attacks (TIA due to intraluminal thrombus of an internal carotid artery. The putative mechanisms underlying anemia and stroke syndromes are not completely understood, and it is believed that iron deficiency may cause ischemic stroke by several potential mechanisms. Thrombocytosis is often associated with iron deficiency, and microcytosis produces a reduction in the red cell deformability and could produce a hypercoagulable state. The platelet count and function observed in iron-deficiency anemia could act synergistically to promote thrombus formation, especially in the setting of an underlying atherosclerotic disease. The presence of floating thrombus in a patient with clinical and MRI evidence of stroke represents a significant therapeutic dilemma and requires immediate decision about treatment.

  7. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes. (United States)

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan


    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood.

  8. Incomplete left atrial appendage occlusion and thrombus formation after Watchman implantation treated with anticoagulation followed by further transcatheter closure with a second-generation Amplatzer Cardiac Plug (Amulet device). (United States)

    Lam, Simon Cheung Chi; Bertog, Stefan; Sievert, Horst


    We report a case of incomplete left atrial appendage (LAA) closure after Watchman device (Atritech, Boston Scientific, Natrick, MA) implantation which subsequently developed a thrombus 3 years after the initial procedure. The thrombus resolved after a short period of anticoagulation with warfarin, and the LAA was successfully occluded with a second-generation Amplatzer Cardiac Plug (Amulet device, AGA, St Jude Medical, Minneapolis, MN). Incomplete LAA closure may be associated with increased risk of thrombus formation and further closure with a second device after a course of anticoagulation may be a reasonable and feasible strategy. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

  9. Platelet aggregation secondary to coronary obstruction. (United States)

    Moore, S


    From many observations made at autopsy it is apparent that thrombosis in a coronary artery is usually, if not always, associated with rupture of an atheromatous plaque. The sequelae of such rupture include hemorrhage into the plaque with further narrowing of the lumen, formation of an occlusive thrombus or of a non-occlusive thrombus. A developing thrombus in an artery undergoes fragmentation with showering of the distal microcirculation by aggregates of platelets possibly with some admixture of fibrin. In many cases of sudden cardiac death associated with severe atherosclerotic stenosis of the coronary vessels, an occlusive thrombus is not found and the myocardium shows no morphological lesion or else focal patchy early damage in the subendocardial region. One possible mechanism that might explain these findings is microembolism from mural nonobstructing coronary thrombus. Such a mechanism is well established in transient ischemia of the brain and retina related to ulcerated atheroma of the internal carotid artery. Experimental observations indicate that platelet aggregates in the myocardial circulation cause arrhythmias, sudden death, vasculitis, and myocardial ischemic damage. Induction of an occlusive coronary artery thrombus is associated with development of an infarct involving the full thickness of the myocardium. A nonocclusive thrombus is associated with either no myocardial damage or focal subendocardial ischemic injury. It is possible that further aggregation of platelets may facilitate the extension of infarction subsequent to an occlusive event, although there is little evidence on this point. A number of clinical studies show increased platelet reactivity to agents causing aggregation, such as norepinephrine or collagen, in subjects experiencing thromboembolic episodes. It seems unlikely, however, that in vitro tests of platelet function can identify or predict clinical arterial thrombotic disease, although studies of platelet survival and turnover

  10. A model of thrombin inactivation in heparinized and nonheparinized tubes with consequences for thrombus formation. (United States)

    Basmadjian, D; Sefton, M V


    The role of flow and mass transport in determining procoagulant concentration at the wall of synthetic and natural cylindrical blood vessels is analyzed theoretically. The model assumes steady laminar flow and considers, in addition to the fluid dynamic parameters, three rate-determining steps: production of procoagulant (thrombin) and its inactivation at the wall, as well as inactivation in the fluid bulk. The ratio of thrombin wall concentration to production rate Cw/N emerges as a critical parameter in characterizing the behavior of the tube wall. With a wall-inactivation rate typical of heparinized materials, Cw/N = 11.1 s/cm, independent of flow (shear rate) and axial position. This is significantly less than the range of Cw/N (50-500 s/cm) for which the thrombin concentration is high enough to result in significant fibrin formation and thrombosis. Hence little fibrin formation and a high degree of thromboresistance is expected for heparinized materials. Nonheparinized materials have Cw/N values above this range, which are only weakly dependent on shear rate and diameter, suggesting that flow-induced dispersion of thrombin (or other procoagulants) has limited impact on the thrombin wall concentration. These latter results appear to refute the conventional wisdom that attributes the relative patency of large-diameter vessels and differences between venous and arterial thrombi to such flow effects. It is likely that additional factors such as flow pulsatility and wall geometry must be considered to account for these observations.

  11. Platelet-derived growth factor B-chain of hematopoietic origin is not necessary for granulation tissue formation and its absence enhances vascularization. (United States)

    Buetow, B S; Crosby, J R; Kaminski, W E; Ramachandran, R K; Lindahl, P; Martin, P; Betsholtz, C; Seifert, R A; Raines, E W; Bowen-Pope, D F


    The hypothesis that wound repair is augmented by delivery of platelet-derived growth factor (PDGF) from platelets and macrophages is an attractive extrapolation from the known activities of PDGF in cell culture and in vivo. To test this hypothesis in mice, we prepared hematopoietic chimeras, in which the hematopoietic system of a normal adult mouse was replaced by the hematopoietic system of a PDGF B-chain -/- or +/+ donor. We initiated local granulation tissue formation either by implanting small surgical sponges to elicit a foreign body granulation tissue response, or by ligating the left common carotid to form an organized thrombus. We found that the absence of hematopoietic PDGF B-chain did not decrease the extent of granulation tissue or vascular lesion formation, and that the vascularization of both lesions increased by approximately 100%. We conclude that PDGF B-chain from cells of hematopoietic origin, including platelets and macrophages, is not important for granulation tissue formation, and that it reduces vascularization of granulation issue, probably through disabling of the short-range chemotactic gradients of PDGF that are important for recruiting pericytes/smooth muscle cells to the endothelium of new vessels.

  12. 2-Arachidonoylglycerol enhances platelet formation from human megakaryoblasts. (United States)

    Gasperi, Valeria; Avigliano, Luciana; Evangelista, Daniela; Oddi, Sergio; Chiurchiù, Valerio; Lanuti, Mirko; Maccarrone, Mauro; Valeria Catani, Maria


    Platelets modulate vascular system integrity, and their loss is critical in haematological pathologies and after chemotherapy. Therefore, identification of molecules enhancing platelet production would be useful to counteract thrombocytopenia. We have previously shown that 2-arachidonoylglycerol (2-AG) acts as a true agonist of platelets, as well as it commits erythroid precursors toward the megakaryocytic lineage. Against this background, we sought to further interrogate the role of 2-AG in megakaryocyte/platelet physiology by investigating terminal differentiation, and subsequent thrombopoiesis. To this end, we used MEG-01 cells, a human megakaryoblastic cell line able to produce in vitro platelet-like particles. 2-AG increased the number of cells showing ruffled surface and enhanced surface expression of specific megakaryocyte/platelet surface antigens, typical hallmarks of terminal megakaryocytic differentiation and platelet production. Changes in cytoskeleton modeling also occurred in differentiated megakaryocytes and blebbing platelets. 2-AG acted by binding to CB1 and CB2 receptors, because specific antagonists reverted its effect. Platelets were split off from megakaryocytes and were functional: they contained the platelet-specific surface markers CD61 and CD49, whose levels increased following stimulation with a natural agonist like collagen. Given the importance of 2-AG for driving megakaryopoiesis and thrombopoiesis, not surprisingly we found that its hydrolytic enzymes were tightly controlled by classical inducers of megakaryocyte differentiation. In conclusion 2-AG, by triggering megakaryocyte maturation and platelet release, may have clinical efficacy to counteract thrombocytopenia-related diseases.

  13. Review of Mechanical Testing and Modelling of Thrombus Material for Vascular Implant and Device Design. (United States)

    Johnson, S; Duffy, S; Gunning, G; Gilvarry, M; McGarry, J P; McHugh, P E


    A thrombus or blood clot is a solid mass, made up of a network of fibrin, platelets and other blood components. Blood clots can form through various pathways, for example as a result of exposed tissue factor from vascular injury, as a result of low flow/stasis, or in very high shear flow conditions. Embolization of cardiac or vascular originating blood clots, causing an occlusion of the neurovasculature, is the major cause of stroke and accounts for 85% of all stroke. With mechanical thrombectomy emerging as the new standard of care in the treatment of acute ischemic stroke (AIS), the need to generate a better understanding of the biomechanical properties and material behaviour of thrombus material has never been greater, as it could have many potential benefits for the analysis and performance of these treatment devices. Defining the material properties of a thrombus has obvious implications for the development of these treatment devices. However, to-date this definition has not been adequately established. While some experimentation has been performed, model development has been extremely limited. This paper reviews the previous literature on mechanical testing of thrombus material. It also explores the use of various constitutive and computational models to model thrombus formation and material behaviour.

  14. Computational simulation of platelet interactions in the initiation of stent thrombosis due to stent malapposition (United States)

    Chesnutt, Jennifer K W; Han, Hai-Chao


    Coronary stenting is one of the most commonly used approaches to open coronary arteries blocked due to atherosclerosis. Stent malapposition can induce thrombosis but the microscopic process is poorly understood. The objective of this study was to determine the platelet-level process by which different extents of stent malapposition affect the initiation of stent thrombosis. We utilized a discrete element model to computationally simulate the transport, adhesion, and activation of thousands of individual platelets and red blood cells during thrombus initiation in stented coronary arteries. Simulated arteries contained a malapposed stent with a specified gap distance (0, 10, 25, 50, or 200 μm) between the struts and endothelium. Platelet-level details of thrombus formation near the proximal-most strut were measured during the simulations. The relationship between gap distance and amount of thrombus in the artery varied depending on different conditions (e.g., amount of dysfunctional endothelium, shear-induced activation of platelets, and thrombogenicity of the strut). Without considering shear-induced platelet activation, the largest gap distance (200 μm) produced no recirculation and less thrombus than the smallest two gap distances (0 and 10 μm) that created recirculation downstream of the strut. However, with the occurrence of shear-induced platelet activation, the largest gap distance produced more thrombus than the two smallest gap distances, but less thrombus than an intermediate gap distance (25 μm). A large gap distance was not necessarily the most thrombogenic, in contrast to implications of some computational fluid dynamics studies. The severity of stent malapposition affected initial stent thrombosis differently depending on various factors related to fluid recirculation, platelet trajectories, shear stress, and endothelial condition. PMID:26790093

  15. Computational simulation of platelet interactions in the initiation of stent thrombosis due to stent malapposition (United States)

    Chesnutt, Jennifer K. W.; Han, Hai-Chao


    Coronary stenting is one of the most commonly used approaches to open coronary arteries blocked due to atherosclerosis. Stent malapposition can induce thrombosis but the microscopic process is poorly understood. The objective of this study was to determine the platelet-level process by which different extents of stent malapposition affect the initiation of stent thrombosis. We utilized a discrete element model to computationally simulate the transport, adhesion, and activation of thousands of individual platelets and red blood cells during thrombus initiation in stented coronary arteries. Simulated arteries contained a malapposed stent with a specified gap distance (0, 10, 25, 50, or 200 μm) between the struts and endothelium. Platelet-level details of thrombus formation near the proximal-most strut were measured during the simulations. The relationship between gap distance and amount of thrombus in the artery varied depending on different conditions (e.g., amount of dysfunctional endothelium, shear-induced activation of platelets, and thrombogenicity of the strut). Without considering shear-induced platelet activation, the largest gap distance (200 μm) produced no recirculation and less thrombus than the smallest two gap distances (0 and 10 μm) that created recirculation downstream of the strut. However, with the occurrence of shear-induced platelet activation, the largest gap distance produced more thrombus than the two smallest gap distances, but less thrombus than an intermediate gap distance (25 μm). A large gap distance was not necessarily the most thrombogenic, in contrast to implications of some computational fluid dynamics studies. The severity of stent malapposition affected initial stent thrombosis differently depending on various factors related to fluid recirculation, platelet trajectories, shear stress, and endothelial condition.


    Navitsky, Michael A.; Taylor, Joshua O.; Smith, Alexander B.; Slattery, Margaret J.; Deutsch, Steven; Siedlecki, Christopher A.; Manning, Keefe B.


    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s−1. The aim of the current work is to determine platelet adhesion properties to the polyurethane urea surface as a function of time varying shear exposure. A rotating disk system is used to study the influence of steady and pulsatile flow conditions (e.g. cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments retain the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk is rotated in platelet rich bovine plasma for two hours with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow is found to exponentially decay with increasing shear rate. Adhesion levels are found to depend upon peak platelet flux and shear rate regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

  17. Platelet adhesion to polyurethane urea under pulsatile flow conditions. (United States)

    Navitsky, Michael A; Taylor, Joshua O; Smith, Alexander B; Slattery, Margaret J; Deutsch, Steven; Siedlecki, Christopher A; Manning, Keefe B


    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s(-1). The aim of the current work is to determine the properties of platelet adhesion to the polyurethane urea surface as a function of time-varying shear exposure. A rotating disk system was used to study the influence of steady and pulsatile flow conditions (e.g., cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments were conducted with the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk was rotated in platelet-rich bovine plasma for 2 h, with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow was found to decay exponentially with increasing shear rate. Adhesion levels were found to depend upon peak platelet flux and shear rate, regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices.

  18. Comparison of coronary artery specific leukocyte-platelet conjugate formation in unstable versus stable angina pectoris. (United States)

    Patel, Parag B; Pfau, Steven E; Cleman, Michael W; Brennan, Joseph J; Howes, Christopher; Remetz, Michael; Cabin, Henry S; Setaro, John F; Rinder, Henry M


    This study evaluates transcoronary changes in neutrophil and platelet activation and conjugate formation in patients with angina pectoris secondary to coronary artery disease. We examined parameters of neutrophil and platelet activation as well as the neutrophil-platelet conjugate formation in patients who underwent diagnostic coronary angiography. Thirty-nine patients with chest pain referred for cardiac catheterization were studied (23 patients with unstable angina pectoris [UAP] and 16 with stable angina pectoris [SAP]). Before coronary angiography, blood samples were obtained simultaneously from the aortic root and coronary sinus to assess leukocyte (CD11b) and platelet (CD62P) activation and leukocyte-platelet conjugates. There was a 94% increase in CD62-expressing platelets from the aorta to the coronary sinus in patients with UAP compared with a 49% increase in patients with SAP. The percentage of neutrophil-platelet conjugates increased by 22% in patients with UAP compared with a 16% decrease in those with SAP (p <0.01). In contrast, monocyte-platelet binding across the coronary bed increased to a similar degree in both groups. This study demonstrates an increase in neutrophil-platelet conjugates across the coronary circulation in UAP, compatible with a higher activation state in both cell types.

  19. Understanding platelet function through signal transduction. (United States)

    Lazarus, Alan H; Song, Seng; Crow, Andrew R


    Platelets are activated by a number of stimuli resulting in the expression and/or activation of surface receptors, secretion of vasoactive substances, adhesion, aggregation, and finally thrombus formation. These events are propagated by a process known as transmembrane signaling, which relays the activating signal from the platelet membrane (eg, von Willebrand Factor binding to glycoprotein Ib) to the inside of the platelet which then serves to activate the platelet via a cascade of biochemical interactions. Inhibition of these transmembrane signaling molecules with a variety of available inhibitors or antagonists can in many cases prevent the platelet from becoming activated. An awareness of the mechanisms involved in platelet transmembrane signaling and the recent availability of new reagents to inhibit signaling may provide us with additional means to prevent platelet activation and perhaps even ameliorate the platelet storage lesion. This review will provide an introduction to the field of platelet transmembrane signaling and give an overview of some of the platelet signaling mechanisms that are relevant to transfusion medicine. Copyright 2003, Elsevier Science (USA). All rights reserved.


    Directory of Open Access Journals (Sweden)

    Chiara Cerletti


    Full Text Available The aim of this review is to summarize the contribution of platelets and leukocytes and their interactions in inflammation and blood coagulation and its possible relevance in the pathogenesis of  thrombosis. There is some evidence of an association between infection/inflammation and thrombosis. This is likely a bidirectional relationship. The presence of a thrombus may serve as a nidus of infection. Vascular injury indeed promotes platelet and leukocyte activation and thrombus formation and the thrombus and its components facilitate adherence of bacteria to the vessel wall. Alternatively, an infection and the associated inflammation can trigger platelet and leukocyte activation and thrombus formation. In either case platelets and leukocytes co-localize and interact in the area of vascular injury, at sites of inflammation and/or at sites of thrombosis. Following vascular injury, the subendothelial tissue, a thrombogenic surface, becomes available for interaction with these blood cells. Tissue factor, found not only in media and adventitia of the vascular wall, but also on activated platelets and leukocytes, triggers blood coagulation. Vascular-blood cell interactions, mediated by the release of preformed components of the endothelium, is modulated by both cell adhesion and production of soluble stimulatory or inhibitory molecules that alter cell function: adhesion molecules regulate cell-cell contact and facilitate the modulation of biochemical pathways relevant to inflammatory and/or thrombotic processes.

  1. Platelet Inhibition by Insulin Is Absent in Type 2 Diabetes Mellitus

    NARCIS (Netherlands)

    Haeften, T.W. van; Akkerman, Jan Willem N.; Heemskerk, J.W.; Gorter, G.; Feijge, M.A.; Mocking, A.I.M.; Ferreira, I.A.


    Objective—ADP-induced P2y12 signaling is crucial for formation and stabilization of an arterial thrombus. We demonstrated recently in platelets from healthy subjects that insulin interferes with Ca2+ increases induced by ADP-P2y1 contact through blockade of the G-protein Gi, and thereby with P2y12-m

  2. Germline variants in ETV6 underlie reduced platelet formation, platelet dysfunction and increased levels of circulating CD34+ progenitors (United States)

    Poggi, Marjorie; Canault, Matthias; Favier, Marie; Turro, Ernest; Saultier, Paul; Ghalloussi, Dorsaf; Baccini, Veronique; Vidal, Lea; Mezzapesa, Anna; Chelghoum, Nadjim; Mohand-Oumoussa, Badreddine; Falaise, Céline; Favier, Rémi; Ouwehand, Willem H.; Fiore, Mathieu; Peiretti, Franck; Morange, Pierre Emmanuel; Saut, Noémie; Bernot, Denis; Greinacher, Andreas; BioResource, NIHR; Nurden, Alan T.; Nurden, Paquita; Freson, Kathleen; Trégouët, David-Alexandre; Raslova, Hana; Alessi, Marie-Christine


    Variants in ETV6, which encodes a transcription repressor of the E26 transformation-specific family, have recently been reported to be responsible for inherited thrombocytopenia and hematologic malignancy. We sequenced the DNA from cases with unexplained dominant thrombocytopenia and identified six likely pathogenic variants in ETV6, of which five are novel. We observed low repressive activity of all tested ETV6 variants, and variants located in the E26 transformation-specific binding domain (encoding p.A377T, p.Y401N) led to reduced binding to corepressors. We also observed a large expansion of megakaryocyte colony-forming units derived from variant carriers and reduced proplatelet formation with abnormal cytoskeletal organization. The defect in proplatelet formation was also observed in control CD34+ cell-derived megakaryocytes transduced with lentiviral particles encoding mutant ETV6. Reduced expression levels of key regulators of the actin cytoskeleton CDC42 and RHOA were measured. Moreover, changes in the actin structures are typically accompanied by a rounder platelet shape with a highly heterogeneous size, decreased platelet arachidonic response, and spreading and retarded clot retraction in ETV6 deficient platelets. Elevated numbers of circulating CD34+ cells were found in p.P214L and p.Y401N carriers, and two patients from different families suffered from refractory anemia with excess blasts, while one patient from a third family was successfully treated for acute myeloid leukemia. Overall, our study provides novel insights into the role of ETV6 as a driver of cytoskeletal regulatory gene expression during platelet production, and the impact of variants resulting in platelets with altered size, shape and function and potentially also in changes in circulating progenitor levels. PMID:27663637

  3. Histopathological evaluation of thrombus in patients presenting with stent thrombosis. A multicenter European study: a report of the prevention of late stent thrombosis by an interdisciplinary global European effort consortium† (United States)

    Riegger, Julia; Byrne, Robert A.; Joner, Michael; Chandraratne, Sue; Gershlick, Anthony H.; ten Berg, Jurrien M.; Adriaenssens, Tom; Guagliumi, Giulio; Godschalk, Thea C.; Neumann, Franz-Josef; Trenk, Dietmar; Feldman, Laurent J.; Steg, Philippe Gabriel; Desmet, Walter; Alfonso, Fernando; Goodall, Alison H.; Wojdyla, Roman; Dudek, Dariusz; Philippi, Vanessa; Opinaldo, Sheryl; Titova, Anna; Malik, Nikesh; Cotton, James; Jhagroe, Darshni A.; Heestermans, Antonius A.C.M.; Sinnaeve, Peter; Vermeersch, Paul; Valina, Christian; Schulz, Christian; Kastrati, Adnan; Massberg, Steffen


    Background Stent thrombosis (ST) is a rare but serious complication following percutaneous coronary intervention. Analysis of thrombus composition from patients undergoing catheter thrombectomy may provide important insights into the pathological processes leading to thrombus formation. We performed a large-scale multicentre study to evaluate thrombus specimens in patients with ST across Europe. Methods Patients presenting with ST and undergoing thrombus aspiration were eligible for inclusion. Thrombus collection was performed according to a standardized protocol and specimens were analysed histologically at a core laboratory. Serial tissue cross sections were stained with haematoxylin–eosin (H&E), Carstairs and Luna. Immunohistochemistry was performed to identify leukocyte subsets, prothrombotic neutrophil extracellular traps (NETs), erythrocytes, platelets, and fibrinogen. Results Overall 253 thrombus specimens were analysed; 79 (31.2%) from patients presenting with early ST, 174 (68.8%) from late ST; 79 (31.2%) were from bare metal stents, 166 (65.6%) from drug-eluting stents, 8 (3.2%) were from stents of unknown type. Thrombus specimens displayed heterogeneous morphology with platelet-rich thrombus and fibrin/fibrinogen fragments most abundant; mean platelet coverage was 57% of thrombus area. Leukocyte infiltrations were hallmarks of both early and late ST (early: 2260 ± 1550 per mm2 vs. late: 2485 ± 1778 per mm2; P = 0.44); neutrophils represented the most prominent subset (early: 1364 ± 923 per mm2 vs. late: 1428 ± 1023 per mm2; P = 0.81). Leukocyte counts were significantly higher compared with a control group of patients with thrombus aspiration in spontaneous myocardial infarction. Neutrophil extracellular traps were observed in 23% of samples. Eosinophils were present in all stent types, with higher numbers in patients with late ST in sirolimus-and everolimus-eluting stents. Conclusion In a large-scale study of histological thrombus analysis from


    Directory of Open Access Journals (Sweden)

    Prasantha Kumar Thankappan


    Full Text Available BACKGROUND Stroke is a major cause of long term morbidity and mortality. Several factors are known to increase the liability to stroke. Platelets play a crucial role in the pathogenesis of atherosclerotic complications, contributing to thrombus formation. Platelet size (mean platelet volume, MPV is a marker and possible determinant of platelet function, large platelets being potentially more reactive. Hence an attempt has-been made to study the association if any between mean platelet volume and thrombotic stroke. The aim of this study was to determine whether an association exists between Mean Platelet Volume (MPV and thrombotic stroke. MATERIALS AND METHODS The study is a case control study and data was collected at Government Medical College Hospital, Kottayam, Kerala a tertiary care referral centre. The study was carried out among fifty patients diagnosed with thrombotic stroke and presenting to the hospital within forty eight hours of onset of symptoms. Fifty age group and sex matched controls were also recruited. Mean platelet volume was obtained using a SYSMEX automated analyser. RESULTS This study has shown a statistically significant relation between mean platelet volume and risk of thrombotic stroke but no statistically significant correlation between clinical severity of stroke and mean platelet volume. CONCLUSION This study has shown an elevation of MPV in acute phase of thrombotic stroke. Platelet mass was found to be more or less a constant. This study did not find a statistically significant correlation between clinical severity of stroke and mean platelet volume.

  5. Effects of Total Flavone of Abelmoschl Manihot L. Medic on the Function of Platelets and Its Mechanism

    Institute of Scientific and Technical Information of China (English)

    GUO Yan; FAN Li; DONG Liu-yi; CHEN Zhi-wu


    Objective:To study the effects of total flavone of Abelmoschl Manihot L. Medic (TFA) on the function of platelets and to explore its mechanism. Methods: Rat models of artery-veins bypassing thrombus formation were used. The platelets of rabbits were collected. Platelet aggregation was induced by collagen and intracellular calcium ion concentration ([Ca2+ ]i) was assayed by Fura-2 method. Results: TFA (25, 50,100 mg/kg) significantly and dose-dependently reduced the weight of thrombus. TFA (0. 025, 0.05, 0.1 mg/mi) possessed dose-dependant inhibitory effects on rabbits' platelet aggregation induced by collagen. TFA significantly reduced the resting and CaCl2-induced increase of free intracellular calcium concentration ([Ca2+ ]i) in rabbit platelet in vitro. Conclusion: TFA has an antiplatelet effect via the inhibition on the influx of Ca2+ .

  6. Repeated renal infarction in native and transplanted kidneys due to left ventricular thrombus formation caused by antiphospholipid antibody syndrome. (United States)

    Scully, Paul; Leckstroem, Daniel C; McGrath, Andrew; Chambers, John; Goldsmith, David J


    Antiphospholipid syndrome can be a feature of several underlying conditions, such as lupus, but it can also occur idiopathically. Diagnosis usually comes after investigation of recurrent venous or arterial thromboses, emboli, or hypertension/proteinuria where the kidney is involved and is usually confirmed by laboratory testing. We describe a case of a man with a myocardial infarction who developed mural thrombus in an akinetic left ventricular segment but then who recurrently embolized first to one of his native kidneys and then later to a transplanted kidney. Although the clinical behavior was typical of antiphospholipid syndrome, it took numerous laboratory assays over many years until finally the problem was confirmed and life-long warfarin therapy instituted.

  7. The expression levels of platelet adhesive receptors in PRP derived platelet concentrates during storage

    Directory of Open Access Journals (Sweden)

    Fatemeh Nassaji


    Full Text Available Background: Major platelet adhesive receptors that contribute significantly to thrombus formation include platelet receptor glycoprotein Ibα (GPIbα of the GPIb-IX-V complex and platelet glycoprotein VI (GPVI. GPIbα plays a crucial role in platelet tethering to sub-endothelial matrix, which initiates thrombus formation at arterial shear rates, whereas GPVI is critically involved in platelets firm adhesion to the site of injury regardless of shear condition. During storage, platelets experience some changes that deleteriously affect the expression levels of platelet receptors, which in turn can alter platelet functional behaviors. Considering the important roles of GPIbα and GPVI in platelet adhesion, it seems that any dramatic changes in the expression levels of these receptors can influence adhesive function of transfused platelets. Thereby examining GPIbα and GPVI expression during the storage of platelet concentrates may provide some useful information about the functional quality of these products after transfusion. Methods: In our experimental study, 5 PRP-platelet concentrates were randomly obtained from Iranian Blood Transfusion Organization (IBTO. All the platelet products met the standard quality assessment based on AABB (American Association of Blood Banks guidelines. Washed platelets were subjected to flowcytometry analysis for the evaluation of GPIbα and GPVI receptor expression in day 1, 3 and 5 after storage. Data were presented as mean fluorescence intensity (MFI and analyzed by Kruskal-Wallis test with Dunn’s multiple comparison test. Results: The GPIbα expression on first day (MFI=86±5.9 was reduced three days after storage (MFI= 69±6.9. The expression levels continued to reduce until day 5 in which GPIbα expression was markedly decreased to (MFI= 61±7.7 (P= 0.0094. GPVI expression on the days 1, 3 and 5 after storage were 20.6±3.3, 24±2.5 and 14±4.9, respectively. The results showed a significant decrease of

  8. Saphenous vein graft thrombus findings by scanning electron microscopy in a patient with acute myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Marcela Dias; Aguillera, André Haraguti [Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Brilhante, José Joaquim; Caixeta, Adriano [Hospital Israelita Albert Einstein, São Paulo, SP (Brazil)


    An eighty-year-old male patient with a history of prior (19 years) coronary artery bypass graft surgery was admitted to the hospital with non ST-segment elevation myocardial infarction (NSTEMI). During the hospital stay he was taking acetylsalicylic acid 100mg per day, a loading dose of 600mg clopidogrel, and low molecular weight heparin 1mg/kg twice a day. Twenty-four hours later the patient underwent coronary angiography, which showed a 90% obstruction in the mid portion of the saphenous vein graft to obtuse marginal with signs of degeneration and local thrombus (Figure 1). Thrombus aspiration was performed with a 6-Fr Export{sup ™} catheter (Medtronic, Santa Rosa, CA, USA), which removed small reddish colored fragments. They were fixed in 2,5% glutaraldehyde in a 0.1M sodium cacodilate buffer. The material was processed following the GOTO protocol in which the fragments were washed with osmium tetroxide and titanic acid, after which they were dried in a critical-point device and a golden bath. Scanning electron microscopy and high definition photos (3,000 to 27,221x magnification) were obtained by the FEI Quanta{sup ™} FEG SEM device (FEI Company, Hillsboro, OR, USA). The images showed that the thrombus was rich in activated platelets, with few erythrocytes or inflammatory cells. Many cholesterol crystals were observed (Figures 2 to). The fibrin networks were sparse and thin, which is compatible with a short ischemic time and recent thrombus formation.

  9. Differential inhibitory action of apixaban on platelet and fibrin components of forming thrombi: Studies with circulating blood and in a platelet-based model of thrombin generation. (United States)

    Pujadas-Mestres, Lluis; Lopez-Vilchez, Irene; Arellano-Rodrigo, Eduardo; Reverter, Joan Carles; Lopez-Farre, Antonio; Diaz-Ricart, Maribel; Badimon, Juan Jose; Escolar, Gines


    Mechanisms of action of direct oral anticoagulants (DOAC) suggest a potential therapeutic use in the prevention of thrombotic complications in arterial territories. However, effects of DOACs on platelet activation and aggregation have not been explored in detail. We have investigated the effects of apixaban on platelet and fibrin components of thrombus formation under static and flow conditions. We assessed the effects of apixaban (10, 40 and 160 ng/mL) on: 1) platelet deposition and fibrin formation onto a thrombogenic surface, with blood circulating at arterial shear-rates; 2) viscoelastic properties of forming clots, and 3) thrombin generation in a cell-model of coagulation primed by platelets. In studies with flowing blood, only the highest concentration of apixaban, equivalent to the therapeutic Cmax, was capable to significantly reduce thrombus formation, fibrin association and platelet-aggregate formation. Apixaban significantly prolonged thromboelastometry parameters, but did not affect clot firmness. Interestingly, results in a platelet-based model of thrombin generation under more static conditions, revealed a dose dependent persistent inhibitory action by apixaban, with concentrations 4 to 16 times below the therapeutic Cmax significantly prolonging kinetic parameters and reducing the total amount of thrombin generated. Our studies demonstrate the critical impact of rheological conditions on the antithrombotic effects of apixaban. Studies under flow conditions combined with modified thrombin generation assays could help discriminating concentrations of apixaban that prevent excessive platelet accumulation, from those that deeply impair fibrin formation and may unnecessarily compromise hemostasis.

  10. Collagen can selectively trigger a platelet secretory phenotype via glycoprotein VI.

    Directory of Open Access Journals (Sweden)

    Véronique Ollivier

    Full Text Available Platelets are not only central actors of hemostasis and thrombosis but also of other processes including inflammation, angiogenesis, and tissue regeneration. Accumulating evidence indicates that these "non classical" functions of platelets do not necessarily rely on their well-known ability to form thrombi upon activation. This suggests the existence of non-thrombotic alternative states of platelets activation. We investigated this possibility through dose-response analysis of thrombin- and collagen-induced changes in platelet phenotype, with regards to morphological and functional markers of platelet activation including shape change, aggregation, P-selectin and phosphatidylserine surface expression, integrin activation, and release of soluble factors. We show that collagen at low dose (0.25 µg/mL selectively triggers a platelet secretory phenotype characterized by the release of dense- and alpha granule-derived soluble factors without causing any of the other major platelet changes that usually accompany thrombus formation. Using a blocking antibody to glycoprotein VI (GPVI, we further show that this response is mediated by GPVI. Taken together, our results show that platelet activation goes beyond the mechanisms leading to platelet aggregation and also includes alternative platelet phenotypes that might contribute to their thrombus-independent functions.

  11. New gene functions in megakaryopoiesis and platelet formation

    NARCIS (Netherlands)

    Gieger, Christian; Radhakrishnan, Aparna; Cvejic, Ana; Tang, Weihong; Porcu, Eleonora; Pistis, Giorgio; Serbanovic-Canic, Jovana; Elling, Ulrich; Goodall, Alison H.; Labrune, Yann; Lopez, Lorna M.; Maegi, Reedik; Meacham, Stuart; Okada, Yukinori; Pirastu, Nicola; Sorice, Rossella; Teumer, Alexander; Voss, Katrin; Zhang, Weihua; Ramirez-Solis, Ramiro; Bis, Joshua C.; Ellinghaus, David; Goegele, Martin; Hottenga, Jouke-Jan; Langenberg, Claudia; Kovacs, Peter; O'Reilly, Paul F.; Shin, So-Youn; Esko, Toenu; Hartiala, Jaana; Kanoni, Stavroula; Murgia, Federico; Parsa, Afshin; Stephens, Jonathan; van der Harst, Pim; van der Schoot, C. Ellen; Allayee, Hooman; Attwood, Antony; Balkau, Beverley; Bastardot, Francois; Basu, Saonli; Baumeister, Sebastian E.; Biino, Ginevra; Bomba, Lorenzo; Bonnefond, Amelie; Cambien, Francois; Chambers, John C.; Cucca, Francesco; D'Adamo, Pio; Davies, Gail; de Boer, Rudolf A.; de Geus, Eco J. C.; Doering, Angela; Elliott, Paul; Erdmann, Jeanette; Evans, David M.; Falchi, Mario; Feng, Wei; Folsom, Aaron R.; Frazer, Ian H.; Gibson, Quince D.; Glazer, Nicole L.; Hammond, Chris; Hartikainen, Anna-Liisa; Heckbert, Susan R.; Hengstenberg, Christian; Hersch, Micha; Illig, Thomas; Loos, Ruth J. F.; Jolley, Jennifer; Khaw, Kay Tee; Kuehnel, Brigitte; Kyrtsonis, Marie-Christine; Lagou, Vasiliki; Lloyd-Jones, Heather; Lumley, Thomas; Mangino, Massimo; Maschio, Andrea; Mateo Leach, Irene; McKnight, Barbara; Memari, Yasin; Mitchell, Braxton D.; Montgomery, Grant W.; Nakamura, Yusuke; Nauck, Matthias; Navis, Gerjan; Noethlings, Ute; Nolte, Ilja M.; Porteous, David J.; Pouta, Anneli; Pramstaller, Peter P.; Pullat, Janne; Ring, Susan M.; Rotter, Jerome I.; Ruggiero, Daniela; Ruokonen, Aimo; Sala, Cinzia; Samani, Nilesh J.; Sambrook, Jennifer; Schlessinger, David; Schreiber, Stefan; Schunkert, Heribert; Scott, James; Smith, Nicholas L.; Snieder, Harold; Starr, John M.; Stumvoll, Michael; Takahashi, Atsushi; Tang, W. H. Wilson; Taylor, Kent; Tenesa, Albert; Thein, Swee Lay; Toenjes, Anke; Uda, Manuela; Ulivi, Sheila; van Veldhuisen, Dirk J.; Visscher, Peter M.; Voelker, Uwe; Wichmann, H-Erich; Wiggins, Kerri L.; Willemsen, Gonneke; Yang, Tsun-Po; Zhao, Jing Hua; Zitting, Paavo; Bradley, John R.; Dedoussis, George V.; Gasparini, Paolo; Hazen, Stanley L.; Metspalu, Andres; Pirastu, Mario; Shuldiner, Alan R.; van Pelt, L. Joost; Zwaginga, Jaap-Jan; Boomsma, Dorret I.; Deary, Ian J.; Franke, Andre; Froguel, Philippe; Ganesh, Santhi K.; Jarvelin, Marjo-Riitta; Martin, Nicholas G.; Meisinger, Christa; Psaty, Bruce M.; Spector, Timothy D.; Wareham, Nicholas J.; Akkerman, Jan-Willem N.; Ciullo, Marina; Deloukas, Panos; Greinacher, Andreas; Jupe, Steve; Kamatani, Naoyuki; Khadake, Jyoti; Kooner, Jaspal S.; Penninger, Josef; Prokopenko, Inga; Stemple, Derek; Toniolo, Daniela; Wernisch, Lorenz; Sanna, Serena; Hicks, Andrew A.; Rendon, Augusto; Ferreira, Manuel A.; Ouwehand, Willem H.; Soranzo, Nicole


    Platelets are the second most abundant cell type in blood and are essential for maintaining haemostasis. Their count and volume are tightly controlled within narrow physiological ranges, but there is only limited understanding of the molecular processes controlling both traits. Here we carried out a

  12. Repeated renal infarction in native and transplanted kidneys due to left ventricular thrombus formation caused by antiphospholipid antibody syndrome

    Directory of Open Access Journals (Sweden)

    Scully P


    Full Text Available Paul Scully,1 Daniel C Leckstroem,1 Andrew McGrath,2 John Chambers,3 David J Goldsmith11Nephrology Department, 2Radiology Department, 3Cardiology Department, King's Health Partners, Academic Health Sciences Centre, London, United KingdomAbstract: Antiphospholipid syndrome can be a feature of several underlying conditions, such as lupus, but it can also occur idiopathically. Diagnosis usually comes after investigation of recurrent venous or arterial thromboses, emboli, or hypertension/proteinuria where the kidney is involved and is usually confirmed by laboratory testing. We describe a case of a man with a myocardial infarction who developed mural thrombus in an akinetic left ventricular segment but then who recurrently embolized first to one of his native kidneys and then later to a transplanted kidney. Although the clinical behavior was typical of antiphospholipid syndrome, it took numerous laboratory assays over many years until finally the problem was confirmed and life-long warfarin therapy instituted.Keywords: antiphospholipid therapy, emboli, infarction, kidney, kidney transplant

  13. Gray platelet syndrome and defective thrombo-inflammation in Nbeal2-deficient mice. (United States)

    Deppermann, Carsten; Cherpokova, Deya; Nurden, Paquita; Schulz, Jan-Niklas; Thielmann, Ina; Kraft, Peter; Vögtle, Timo; Kleinschnitz, Christoph; Dütting, Sebastian; Krohne, Georg; Eming, Sabine A; Nurden, Alan T; Eckes, Beate; Stoll, Guido; Stegner, David; Nieswandt, Bernhard


    Platelets are anuclear organelle-rich cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity. The major platelet organelles, α-granules, release proteins that participate in thrombus formation and hemostasis. Proteins stored in α-granules are also thought to play a role in inflammation and wound healing, but their functional significance in vivo is unknown. Mutations in NBEAL2 have been linked to gray platelet syndrome (GPS), a rare bleeding disorder characterized by macrothrombocytopenia, with platelets lacking α-granules. Here we show that Nbeal2-knockout mice display the characteristics of human GPS, with defective α-granule biogenesis in MKs and their absence from platelets. Nbeal2 deficiency did not affect MK differentiation and proplatelet formation in vitro or platelet life span in vivo. Nbeal2-deficient platelets displayed impaired adhesion, aggregation, and coagulant activity ex vivo that translated into defective arterial thrombus formation and protection from thrombo-inflammatory brain infarction following focal cerebral ischemia. In a model of excisional skin wound repair, Nbeal2-deficient mice exhibited impaired development of functional granulation tissue due to severely reduced differentiation of myofibroblasts in the absence of α-granule secretion. This study demonstrates that platelet α-granule constituents are critically required not only for hemostasis but also thrombosis, acute thrombo-inflammatory disease states, and tissue reconstitution after injury.

  14. Multi-Constituent Simulation of Thrombus Deposition (United States)

    Wu, Wei-Tao; Jamiolkowski, Megan A.; Wagner, William R.; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.


    In this paper, we present a spatio-temporal mathematical model for simulating the formation and growth of a thrombus. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus (solid) phase. The transport and reactions of 10 chemical and biological species are incorporated using a system of coupled convection-reaction-diffusion (CRD) equations to represent three processes in thrombus formation: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: in vivo thrombus growth in an injured blood vessel and in vitro thrombus deposition in micro-channels (1.5 mm × 1.6 mm × 0.1 mm) with small crevices (125 μm × 75 μm and 125 μm × 137 μm). For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. Based on the success with these two benchmark problems, which have very different flow conditions and biological environments, we believe that the current model will provide useful insight into the genesis of thrombosis in blood-wetted devices, and provide a tool for the design of less thrombogenic devices. PMID:28218279

  15. Platelet-neutrophil complex formation-a detailed in vitro analysis of murine and human blood samples. (United States)

    Mauler, Maximilian; Seyfert, Julia; Haenel, David; Seeba, Hannah; Guenther, Janine; Stallmann, Daniela; Schoenichen, Claudia; Hilgendorf, Ingo; Bode, Christoph; Ahrens, Ingo; Duerschmied, Daniel


    Platelets form complexes with neutrophils during inflammatory processes. These aggregates migrate into affected tissues and also circulate within the organism. Several studies have evaluated platelet-neutrophil complexes as a marker of cardiovascular diseases in human and mouse. Although multiple publications have reported platelet-neutrophil complex counts, we noticed that different methods were used to analyze platelet-neutrophil complex formation, resulting in significant differences, even in baseline values. We established a protocol for platelet-neutrophil complex measurement with flow cytometry in murine and human whole blood samples. In vitro platelet-neutrophil complex formation was stimulated with ADP or PMA. We tested the effect of different sample preparation steps and cytometer settings on platelet-neutrophil complex detection and noticed false-positive counts with increasing acquisition speed. Platelet-neutrophil complex formation depends on platelet P-selectin expression, and antibody blocking of P-selectin consequently prevented ADP-induced platelet-neutrophil complex formation. These findings may help generating more comparable data among different research groups that examine platelet-neutrophil complexes as a marker for cardiovascular disease and novel therapeutic interventions.

  16. Platelet-derived HMGB1 is a critical mediator of thrombosis. (United States)

    Vogel, Sebastian; Bodenstein, Rebecca; Chen, Qiwei; Feil, Susanne; Feil, Robert; Rheinlaender, Johannes; Schäffer, Tilman E; Bohn, Erwin; Frick, Julia-Stefanie; Borst, Oliver; Münzer, Patrick; Walker, Britta; Markel, Justin; Csanyi, Gabor; Pagano, Patrick J; Loughran, Patricia; Jessup, Morgan E; Watkins, Simon C; Bullock, Grant C; Sperry, Jason L; Zuckerbraun, Brian S; Billiar, Timothy R; Lotze, Michael T; Gawaz, Meinrad; Neal, Matthew D


    Thrombosis and inflammation are intricately linked in several major clinical disorders, including disseminated intravascular coagulation and acute ischemic events. The damage-associated molecular pattern molecule high-mobility group box 1 (HMGB1) is upregulated by activated platelets in multiple inflammatory diseases; however, the contribution of platelet-derived HMGB1 in thrombosis remains unexplored. Here, we generated transgenic mice with platelet-specific ablation of HMGB1 and determined that platelet-derived HMGB1 is a critical mediator of thrombosis. Mice lacking HMGB1 in platelets exhibited increased bleeding times as well as reduced thrombus formation, platelet aggregation, inflammation, and organ damage during experimental trauma/hemorrhagic shock. Platelets were the major source of HMGB1 within thrombi. In trauma patients, HMGB1 expression on the surface of circulating platelets was markedly upregulated. Moreover, evaluation of isolated platelets revealed that HMGB1 is critical for regulating platelet activation, granule secretion, adhesion, and spreading. These effects were mediated via TLR4- and MyD88-dependent recruitment of platelet guanylyl cyclase (GC) toward the plasma membrane, followed by MyD88/GC complex formation and activation of the cGMP-dependent protein kinase I (cGKI). Thus, we establish platelet-derived HMGB1 as an important mediator of thrombosis and identify a HMGB1-driven link between MyD88 and GC/cGKI in platelets. Additionally, these findings suggest a potential therapeutic target for patients sustaining trauma and other inflammatory disorders associated with abnormal coagulation.

  17. Modelling of platelet-fibrin clot formation in flow with a DPD-PDE method. (United States)

    Tosenberger, A; Ataullakhanov, F; Bessonov, N; Panteleev, M; Tokarev, A; Volpert, V


    The paper is devoted to mathematical modelling of clot growth in blood flow. Great complexity of the hemostatic system dictates the need of usage of the mathematical models to understand its functioning in the normal and especially in pathological situations. In this work we investigate the interaction of blood flow, platelet aggregation and plasma coagulation. We develop a hybrid DPD-PDE model where dissipative particle dynamics (DPD) is used to model plasma flow and platelets, while the regulatory network of plasma coagulation is described by a system of partial differential equations. Modelling results confirm the potency of the scenario of clot growth where at the first stage of clot formation platelets form an aggregate due to weak inter-platelet connections and then due to their activation. This enables the formation of the fibrin net in the centre of the platelet aggregate where the flow velocity is significantly reduced. The fibrin net reinforces the clot and allows its further growth. When the clot becomes sufficiently large, it stops growing due to the narrowed vessel and the increase of flow shear rate at the surface of the clot. Its outer part is detached by the flow revealing the inner part covered by fibrin. This fibrin cap does not allow new platelets to attach at the high shear rate, and the clot stops growing. Dependence of the final clot size on wall shear rate and on other parameters is studied.

  18. Time-dependent inhibitory effects of cGMP-analogues on thrombin-induced platelet-derived microparticles formation, platelet aggregation, and P-selectin expression. (United States)

    Nygaard, Gyrid; Herfindal, Lars; Kopperud, Reidun; Aragay, Anna M; Holmsen, Holm; Døskeland, Stein Ove; Kleppe, Rune; Selheim, Frode


    In platelets, nitric oxide (NO) activates cGMP/PKG signalling, whereas prostaglandins and adenosine signal through cAMP/PKA. Cyclic nucleotide signalling has been considered to play an inhibitory role in platelets. However, an early stimulatory effect of NO and cGMP-PKG signalling in low dose agonist-induced platelet activation have recently been suggested. Here, we investigated whether different experimental conditions could explain some of the discrepancy reported for platelet cGMP-PKG-signalling. We treated gel-filtered human platelets with cGMP and cAMP analogues, and used flow cytometric assays to detect low dose thrombin-induced formation of small platelet aggregates, single platelet disappearance (SPD), platelet-derived microparticles (PMP) and thrombin receptor agonist peptide (TRAP)-induced P-selectin expression. All four agonist-induced platelet activation phases were blocked when platelets were costimulated with the PKG activators 8-Br-PET-cGMP or 8-pCPT-cGMP and low-doses of thrombin or TRAP. However, extended incubation with 8-Br-PET-cGMP decreased its inhibition of TRAP-induced P-selectin expression in a time-dependent manner. This effect did not involve desensitisation of PKG or PKA activity, measured as site-specific VASP phosphorylation. Moreover, PKG activators in combination with the PKA activator Sp-5,6-DCL-cBIMPS revealed additive inhibitory effect on TRAP-induced P-selectin expression. Taken together, we found no evidence for a stimulatory role of cGMP/PKG in platelets activation and conclude rather that cGMP/PKG signalling has an important inhibitory function in human platelet activation.

  19. Binding of thrombin-activated platelets to a fibrin scaffold through α(IIbβ₃ evokes phosphatidylserine exposure on their cell surface.

    Directory of Open Access Journals (Sweden)

    Tomasz Brzoska

    Full Text Available Recently, by employing intra-vital confocal microscopy, we demonstrated that platelets expose phosphatidylserine (PS and fibrin accumulate only in the center of the thrombus but not in its periphery. To address the question how exposure of platelet anionic phospholipids is regulated within the thrombus, an in-vitro experiment using diluted platelet-rich plasma was employed, in which the fibrin network was formed in the presence of platelets, and PS exposure on the platelet surface was analyzed using Confocal Laser Scanning Microscopy. Almost all platelets exposed PS after treatment with tissue factor, thrombin or ionomycin. Argatroban abrogated fibrin network formation in all samples, however, platelet PS exposure was inhibited only in tissue factor- and thrombin-treated samples but not in ionomycin-treated samples. FK633, an α(IIbβ₃ antagonist, and cytochalasin B impaired platelet binding to the fibrin scaffold and significantly reduced PS exposure evoked by thrombin. Gly-Pro-Arg-Pro amide abrogated not only fibrin network formation, but also PS exposure on platelets without suppressing platelet binding to fibrin/fibrinogen. These results suggest that outside-in signals in platelets generated by their binding to the rigid fibrin network are essential for PS exposure after thrombin treatment.

  20. Systemic platelet dysfunction is the result of local dysregulated coagulation and platelet activation in the brain in a rat model of isolated traumatic brain injury. (United States)

    Ploplis, Victoria A; Donahue, Deborah L; Sandoval-Cooper, Mayra J; MorenoCaffaro, Maria; Sheets, Patrick; Thomas, Scott G; Walsh, Mark; Castellino, Francis J


    Coagulopathy after severe traumatic brain injury (TBI) has been extensively reported. Clinical studies have identified a strong relationship between diminished platelet-rich thrombus formation, responsiveness to adenosine diphosphate agonism, and severity of TBI. The mechanisms that lead to platelet dysfunction in the acute response to TBI are poorly understood. The development of a rodent model of TBI that mimics the coagulopathy observed clinically has recently been reported. Using immunohistochemical techniques and thromboelastography platelet mapping, the current study demonstrated that the expression of coagulation (tissue factor and fibrin) and platelet activation (P-selectin) markers in the injured brain paralleled the alteration in systemic platelet responsiveness to the agonists, adenosine diphosphate and arachodonic acid. Results of this study demonstrate that local procoagulant changes in the injured brain have profound effects on systemic platelet function.

  1. Blood platelet-derived microparticles release and bubble formation after an open-sea air dive. (United States)

    Pontier, Jean-Michel; Gempp, Emmanuel; Ignatescu, Mihaela


    Bubble-induced platelet aggregation offers an index for evaluating decompression severity in humans and in a rat model of decompression sickness. Endothelial cells, blood platelets, or leukocytes shed microparticles (MP) upon activation and during cell apoptosis. The aim was to study blood platelet MP (PMP) release and bubble formation after a scuba-air dive in field conditions. Healthy, experienced divers were assigned to 1 experimental group (n = 10) with an open-sea air dive to 30 msw for 30 min and 1 control group (n = 5) during head-out water immersion for the same period. Bubble grades were monitored with a pulsed doppler according to Kissman Integrated Severity Score (KISS). Blood samples for platelet count (PC) and PMP (annexin V and CD41) were taken 1 h before and after exposure in both groups. The result showed a decrease in post-dive PC compared with pre-dive values in experimental group with no significant change in the control group. We observed a significant increase in PMP values after the dive while no change was revealed in the control group. There was a significant positive correlation between the PMP values after the dive and the KISS bubble score. The present study highlighted a relationship between the post-dive decrease in PC, platelet MP release, and bubble formation. Release of platelet MPs could reflect bubble-induced platelet aggregation and could play a key role in alteration of the coagulation. Further studies must investigate endothelial and leukocyte MP release in the same field conditions.

  2. Heat shock protein 70 regulates platelet integrin activation, granule secretion and aggregation. (United States)

    Rigg, Rachel A; Healy, Laura D; Nowak, Marie S; Mallet, Jérémy; Thierheimer, Marisa L D; Pang, Jiaqing; McCarty, Owen J T; Aslan, Joseph E


    Molecular chaperones that support protein quality control, including heat shock protein 70 (Hsp70), participate in diverse aspects of cellular and physiological function. Recent studies have reported roles for specific chaperone activities in blood platelets in maintaining hemostasis; however, the functions of Hsp70 in platelet physiology remain uninvestigated. Here we characterize roles for Hsp70 activity in platelet activation and function. In vitro biochemical, microscopy, flow cytometry, and aggregometry assays of platelet function, as well as ex vivo analyses of platelet aggregate formation in whole blood under shear, were carried out under Hsp70-inhibited conditions. Inhibition of platelet Hsp70 blocked platelet aggregation and granule secretion in response to collagen-related peptide (CRP), which engages the immunoreceptor tyrosine-based activation motif-bearing collagen receptor glycoprotein VI (GPVI)-Fc receptor-γ chain complex. Hsp70 inhibition also reduced platelet integrin-αIIbβ3 activation downstream of GPVI, as Hsp70-inhibited platelets showed reduced PAC-1 and fibrinogen binding. Ex vivo, pharmacological inhibition of Hsp70 in human whole blood prevented the formation of platelet aggregates on collagen under shear. Biochemical studies supported a role for Hsp70 in maintaining the assembly of the linker for activation of T cells signalosome, which couples GPVI-initiated signaling to integrin activation, secretion, and platelet function. Together, our results suggest that Hsp70 regulates platelet activation and function by supporting linker for activation of T cells-associated signaling events downstream of platelet GPVI engagement, suggesting a role for Hsp70 in the intracellular organization of signaling systems that mediate platelet secretion, "inside-out" activation of platelet integrin-αIIbβ3, platelet-platelet aggregation, and, ultimately, hemostatic plug and thrombus formation.

  3. Time-dependent inhibitory effects of cGMP-analogues on thrombin-induced platelet-derived microparticles formation, platelet aggregation, and P-selectin expression

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Gyrid [Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen (Norway); Department of Biomedicine, University of Bergen, Bergen (Norway); Herfindal, Lars; Kopperud, Reidun [Department of Biomedicine, University of Bergen, Bergen (Norway); Aragay, Anna M. [Department of Biomedicine, University of Bergen, Bergen (Norway); Molecular Biology Institute of Barcelona (IBMB, CSIC), Barcelona (Spain); Holmsen, Holm; Døskeland, Stein Ove; Kleppe, Rune [Department of Biomedicine, University of Bergen, Bergen (Norway); Selheim, Frode, E-mail: [Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen (Norway); Department of Biomedicine, University of Bergen, Bergen (Norway)


    Highlights: • We investigated the impact of cyclic nucleotide analogues on platelet activation. • Different time dependence were found for inhibition of platelet activation. • Additive effect was found using PKA- and PKG-activating analogues. • Our results may explain some of the discrepancies reported for cNMP signalling. - Abstract: In platelets, nitric oxide (NO) activates cGMP/PKG signalling, whereas prostaglandins and adenosine signal through cAMP/PKA. Cyclic nucleotide signalling has been considered to play an inhibitory role in platelets. However, an early stimulatory effect of NO and cGMP-PKG signalling in low dose agonist-induced platelet activation have recently been suggested. Here, we investigated whether different experimental conditions could explain some of the discrepancy reported for platelet cGMP-PKG-signalling. We treated gel-filtered human platelets with cGMP and cAMP analogues, and used flow cytometric assays to detect low dose thrombin-induced formation of small platelet aggregates, single platelet disappearance (SPD), platelet-derived microparticles (PMP) and thrombin receptor agonist peptide (TRAP)-induced P-selectin expression. All four agonist-induced platelet activation phases were blocked when platelets were costimulated with the PKG activators 8-Br-PET-cGMP or 8-pCPT-cGMP and low-doses of thrombin or TRAP. However, extended incubation with 8-Br-PET-cGMP decreased its inhibition of TRAP-induced P-selectin expression in a time-dependent manner. This effect did not involve desensitisation of PKG or PKA activity, measured as site-specific VASP phosphorylation. Moreover, PKG activators in combination with the PKA activator Sp-5,6-DCL-cBIMPS revealed additive inhibitory effect on TRAP-induced P-selectin expression. Taken together, we found no evidence for a stimulatory role of cGMP/PKG in platelets activation and conclude rather that cGMP/PKG signalling has an important inhibitory function in human platelet activation.

  4. Suilysin-induced Platelet-Neutrophil Complexes Formation is Triggered by Pore Formation-dependent Calcium Influx (United States)

    Zhang, Shengwei; Zheng, Yuling; Chen, Shaolong; Huang, Shujing; Liu, Keke; Lv, Qingyu; Jiang, Yongqiang; Yuan, Yuan


    Platelet activation and platelet–neutrophil interactions have been found to be involved in inflammation, organ failure and soft-tissue necrosis in bacterial infections. Streptococcus suis, an emerging human pathogen, can cause streptococcal toxic-shock syndrome (STSS) similarly to Streptococcus pyogenes. Currently, S. suis–platelet interactions are poorly understood. Here, we found that suilysin (SLY), the S. suis cholesterol-dependent cytolysin (CDC), was the sole stimulus of S. suis that induced platelet-neutrophil complexes (PNC) formation. Furthermore, P-selectin released in α-granules mediated PNC formation. This process was triggered by the SLY-induced pore forming-dependent Ca2+ influx. Moreover, we demonstrated that the Ca2+ influx triggered an MLCK-dependent pathway playing critical roles in P-selectin activation and PNC formation, however, PLC-β-IP3/DAG-MLCK and Rho-ROCK-MLCK signalling were not involved. Additionally, the “outside-in” signalling had a smaller effect on the SLY-induced P-selectin release and PNC formation. Interestingly, other CDCs including pneumolysin and streptolysin O have also been found to induce PNC formation in a pore forming-dependent Ca2+ influx manner. It is possible that the bacterial CDC-mediated PNC formation is a similar response mechanism used by a wide range of bacteria. These findings may provide useful insight for discovering potential therapeutic targets for S. suis-associated STSS. PMID:27830834

  5. In vitro model of platelet aggregation in stenotic arteries

    Energy Technology Data Exchange (ETDEWEB)

    Morley, D.; Santamore, W.P.


    Clinical and experimental evidence suggest a strong relationship between arterial stenosis, platelet aggregation, and subsequent thrombus formation. To facilitate the study of platelet accumulation in stenotic arteries, we developed an in vitro preparation. Arterial segments were perfused with whole citrated blood. A stenosis was created by applying an external plastic constrictor to the artery. Platelet accumulation within the stenosis was assessed by scanning electron microscopy and by radioactive counts from Indium-111 labeled platelets. Utilizing this preparation, 30 carotid arterial segments from 10 mongrel dogs were perfused at 100 mmHg for 15 min. In 10 arteries without a stenosis, scanning electron microscopy and radioactive counts demonstrated little platelet accumulation. In contrast, extensive platelet aggregation was observed in 10 arteries with stenoses. Moreover, in 10 stenotic arteries exposed to the thromboxane mimetic, U46619 (Upjohn Diagnostic Group), scanning electron microscopy and radioactive counts demonstrated a significant increase in platelet deposition. Conversely, we demonstrated a dimunition of platelet accumulation in stenosed arterial segments exposed to the prostacyclin analogue platelet inhibitor, Iloprost. The in vitro preparation allows precise control of hemodynamic variables and makes it possible to perform multiple tests on segments of the same vessel from the same animal.

  6. Thrombosis is reduced by inhibition of COX-1, but unaffected by inhibition of COX-2, in an acute model of platelet activation in the mouse.

    Directory of Open Access Journals (Sweden)

    Paul C Armstrong

    Full Text Available BACKGROUND: Clinical use of selective inhibitors of cyclooxygenase (COX-2 appears associated with increased risk of thrombotic events. This is often hypothesised to reflect reduction in anti-thrombotic prostanoids, notably PGI(2, formed by COX-2 present within endothelial cells. However, whether COX-2 is actually expressed to any significant extent within endothelial cells is controversial. Here we have tested the effects of acute inhibition of COX on platelet reactivity using a functional in vivo approach in mice. METHODOLOGY/PRINCIPAL FINDINGS: A non-lethal model of platelet-driven thromboembolism in the mouse was used to assess the effects of aspirin (7 days orally as control diclofenac (1, i.v. and parecoxib (0.5, i.v. on thrombus formation induced by collagen or the thromboxane (TX A(2-mimetic, U46619. The COX inhibitory profiles of the drugs were confirmed in mouse tissues ex vivo. Collagen and U46619 caused in vivo thrombus formation with the former, but not latter, sensitive to oral dosing with aspirin. Diclofenac inhibited COX-1 and COX-2 ex vivo and reduced thrombus formation in response to collagen, but not U46619. Parecoxib inhibited only COX-2 and had no effect upon thrombus formation caused by either agonist. CONCLUSIONS/SIGNIFICANCE: Inhibition of COX-1 by diclofenac or aspirin reduced thrombus formation induced by collagen, which is partly dependent upon platelet-derived TXA(2, but not that induced by U46619, which is independent of platelet TXA(2. These results are consistent with the model demonstrating the effects of COX-1 inhibition in platelets, but provide no support for the hypothesis that acute inhibition of COX-2 in the circulation increases thrombosis.

  7. Analysis of aggregation of platelets in thrombosis (United States)

    Ahuja, Suresh

    Platelets are key players in thrombus formation by first rolling over collagen bound von Willebrand factor followed by formation of a stable interaction with collagen. The first adhered platelets bind additional platelets until the whole injury is sealed off by a platelet aggregate. The coagulation system stabilizes the formed platelet plug by creating a tight fibrin network, and then wound contraction takes place because of morphological changes in platelets. Coagulation takes place by platelet activation and aggregation mainly through fibrinogen polymerization into fibrin fibers. The process includes multiple factors, such as thrombin, plasmin, and local shear-rate which regulate and control the process. Coagulation can be divided into two pathways: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway is initiated by the exposure of a negatively charged. It is able to activate factor XII, using a complex reaction that includes prekallikrein and high-molecular-weight kininogen as cofactors.. Thrombin is the final enzyme that is needed to convert fibrinogen into fibrin. The extrinsic pathway starts with the exposure of tissue factor to the circulating blood, which is the major initiator of coagulation. There are several feedback loops that reinforce the coagulation cascade, resulting in large amounts of thrombin. It is dependent on the presence of pro-coagulant surfaces of cells expressing negatively charged phospholipids--which include phosphatidylserine (PS)--on their outer membrane. PS-bearing surfaces are able to increase the efficiency of the reactions by concentrating and co-localizing coagulation factors.. Aggregation of platelets are analyzed and compared to adhesion of platelet to erythrocyte and to endothelial cells. This abstract is replacing MAR16-2015-020003.

  8. Macroscopic domain formation in the platelet plasma membrane

    DEFF Research Database (Denmark)

    Bali, Rachna; Savino, Laura; Ramirez, Diego A.;


    There has been ample debate on whether cell membranes can present macroscopic lipid domains as predicted by three-component phase diagrams obtained by fluorescence microscopy. Several groups have argued that membrane proteins and interactions with the cytoskeleton inhibit the formation of large d...

  9. Matrix metalloproteinase-2 enhances platelet deposition on collagen under flow conditions. (United States)

    Guglielmini, Giuseppe; Appolloni, Viviana; Momi, Stefania; De Groot, Philip G; Battiston, Monica; De Marco, Luigi; Falcinelli, Emanuela; Gresele, Paolo


    Platelets contain and release matrix metalloproteinase-2 (MMP-2) that in turn potentiates platelet aggregation. Platelet deposition on a damaged vascular wall is the first, crucial, step leading to thrombosis. Little is known about the effects of MMP-2 on platelet activation and adhesion under flow conditions. We studied the effect of MMP-2 on shear-dependent platelet activation using the O'Brien filtration system, and on platelet deposition using a parallel-plate perfusion chamber. Preincubation of human whole blood with active MMP-2 (50 ng/ml, i.e. 0.78 nM) shortened filter closure time (from 51.8 ± 3.6 sec to 40 ± 2.7 sec, pMMP-2 inhibitor. High shear stress induced the release of MMP-2 from platelets, while TIMP-2 levels were not significantly reduced, therefore, the MMP-2/TIMP-2 ratio increased significantly showing enhanced MMP-2 activity. Preincubation of whole blood with active MMP-2 (0.5 to 50 ng/ml, i.e 0.0078 to 0.78 nM) increased dose-dependently human platelet deposition on collagen under high shear-rate flow conditions (3000 sec⁻¹) (maximum +47.0 ± 11.9%, pMMP-2 inhibitor reduced platelet deposition. In real-time microscopy studies, increased deposition of platelets on collagen induced by MMP-2 started 85 sec from the beginning of perfusion, and was abolished by a GPIIb/IIIa antagonist, while MMP-2 had no effect on platelet deposition on fibrinogen or VWF. Confocal microscopy showed that MMP-2 enhances thrombus volume (+20.0 ± 3.0% vs control) rather than adhesion. In conclusion, we show that MMP-2 potentiates shear-induced platelet activation by enhancing thrombus formation.

  10. Drug effects on platelet adherence to collagen and damaged vessel walls. (United States)

    Packham, M A; Cazenave, J P; Kinlough-Rathbone, R L; Mustard, J F


    The interaction of platelets with damaged vessel walls leads to the formation of platelet-fibrin thrombi and may also contribute to the development of atherosclerotic lesions because platelets adherent to exposed collagen release a mitogen that stimulates smooth muscle cell proliferation. The first step in thrombus formation, platelet adherence to an injured vessel wall, can be studied quantitatively by the use of platelets labeled with 51chromium. In these investigations, rabbit aortas were damaged by passage of a balloon catheter and segments of the aortas were everted on probes that were rotated in platelet suspensions. Collagen-coated glass cylinders were also used. Adherence was measured in a medium containing approximately physiologic concentrations of calcium, magnesium, protein and red blood cells. Conditions of testing influence the effect of non-steroidal anti-inflammatory drugs, sulfinpyrazone, and dipyridamole on platelet adherence. Aspirin and sulfinpyrazone were not inhibitory when tested in a medium with a 40% hematocrit; this indicates that products formed by platelets from arachidonate probably do not play a major part in the adherence of the first layer of platelets to the surface, although they may be involved in thrombus formation. Indomethacin, dipyridamole, prostaglandin E1, methylprednisolone and penicillin G and related antibiotics did inhibit platelet adherence although the concentrations required were higher than would likely be achieved in vivo upon administration to human patients. None of the non-steroidal anti-inflammatory drugs inhibited the release of granule contents from adherent platelets. Pretreatment of the damaged vessel wall with aspirin increased platelet adherence, presumably because it prevented the formation of PGI2 by the vessel wall. Platelet adherence to undamaged or damaged vessel walls was enhanced by prior exposure of the wall to thrombin. Platelet reactions with aggregating agents and platelet survival can be

  11. Platelet lysate gel and endothelial progenitors stimulate microvascular network formation in vitro: tissue engineering implications. (United States)

    Fortunato, Tiago M; Beltrami, Cristina; Emanueli, Costanza; De Bank, Paul A; Pula, Giordano


    Revascularisation is a key step for tissue regeneration and complete organ engineering. We describe the generation of human platelet lysate gel (hPLG), an extracellular matrix preparation from human platelets able to support the proliferation of endothelial colony forming cells (ECFCs) in 2D cultures and the formation of a complete microvascular network in vitro in 3D cultures. Existing extracellular matrix preparations require addition of high concentrations of recombinant growth factors and allow only limited formation of capillary-like structures. Additional advantages of our approach over existing extracellular matrices are the absence of any animal product in the composition hPLG and the possibility of obtaining hPLG from patients to generate homologous scaffolds for re-implantation. This discovery has the potential to accelerate the development of regenerative medicine applications based on implantation of microvascular networks expanded ex vivo or the generation of fully vascularised organs.

  12. Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles (United States)

    Schmiele, Martin; Gehrer, Simone; Westermann, Martin; Steiniger, Frank; Unruh, Tobias


    Suspensions of platelet-like shaped tripalmitin nanocrystals stabilized by the pure lecithin DLPC and the lecithin blend S100, respectively, have been studied by small-angle x-ray scattering (SAXS) and optical observation of their birefringence at different tripalmitin (PPP) concentrations φPPP. It could be demonstrated that the platelets of these potential drug delivery systems start to form a liquid crystalline phase already at pharmaceutically relevant concentrations φPPP of less than 10 wt. %. The details of this liquid crystalline phase are described here for the first time. As in a previous study [A. Illing et al., Pharm. Res. 21, 592 (2004)] some platelets are found to self-assemble into lamellar stacks above a critical tripalmitin concentration \\varphi _{PPP}^{st} of 4 wt. %. In this study another critical concentration \\varphi _{PPP}^{lc}≈ 7 wt. % for DLPC and \\varphi _{PPP}^{lc}≈ 9 wt. % for S100 stabilized dispersions, respectively, has been observed. \\varphi _{PPP}^{lc} describes the transition from a phase of randomly oriented stacked lamellae and remaining non-assembled individual platelets to a phase in which the stacks and non-assembled platelets exhibit an overall preferred orientation. A careful analysis of the experimental data indicates that for concentrations above \\varphi _{PPP}^{lc} the stacked lamellae start to coalesce to rather small liquid crystalline domains of nematically ordered stacks. These liquid crystalline domains can be individually very differently oriented but possess an overall preferred orientation over macroscopic length scales which becomes successively more expressed when further increasing φPPP. The lower critical concentration for the formation of liquid crystalline domains of the DLPC-stabilized suspension compared to \\varphi _{PPP}^{lc} of the S100-stabilized suspension can be explained by a larger aspect ratio of the corresponding tripalmitin platelets. A geometrical model based on the excluded volumes of

  13. Amarogentin, a Secoiridoid Glycoside, Abrogates Platelet Activation through PLCγ2-PKC and MAPK Pathways

    Directory of Open Access Journals (Sweden)

    Ting-Lin Yen


    Full Text Available Amarogentin, an active principle of Gentiana lutea, possess antitumorigenic, antidiabetic, and antioxidative properties. Activation of platelets is associated with intravascular thrombosis and cardiovascular diseases. The present study examined the effects of amarogentin on platelet activation. Amarogentin treatment (15~60 μM inhibited platelet aggregation induced by collagen, but not thrombin, arachidonic acid, and U46619. Amarogentin inhibited collagen-induced phosphorylation of phospholipase C (PLCγ2, protein kinase C (PKC, and mitogen-activated protein kinases (MAPKs. It also inhibits in vivo thrombus formation in mice. In addition, neither the guanylate cyclase inhibitor ODQ nor the adenylate cyclase inhibitor SQ22536 affected the amarogentin-mediated inhibition of platelet aggregation, which suggests that amarogentin does not regulate the levels of cyclic AMP and cyclic GMP. In conclusion, amarogentin prevents platelet activation through the inhibition of PLCγ2-PKC cascade and MAPK pathway. Our findings suggest that amarogentin may offer therapeutic potential for preventing or treating thromboembolic disorders.

  14. Diagnostic usefulness of thrombus imaging scintigraphy for blood coagulopathy in the patients with aortic aneurysm. The comparison of /sup 111/In-oxine labelled platelet and sup(99m)Tc-fibrinogen scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Sakakibara, Yuzuru; Takeda, Toru; Ijima, Hiroshi; Nose, Tadao; Ishikawa, Nobuyoshi; Hori, Motokazu


    Eighteen patients with aortic aneurysm were studied to identify intraluminal thrombi using /sup 111/In-oxine labelled platelet and /sup 99m/Tc-fibrinogen scintigraphy. Reliability in the detection of thrombi with /sup 111/In-oxine labelled platelet scintigraphy was higher than that with /sup 99m/Tc-fibrinogen scintigraphy (94.1% vs 76.9%, respectively). Measurement of mean platelet survival time with /sup 111/In-oxine labelled autologous platelets were carried out in eight patients. Seven of them showed focal accumulation of the labelled platelets at the site of aortic aneurysm and mean platelet survival time (6.64 + 1.46 days) was shorter than normal. In the case of abdominal aneurysm, thrombocytopenia was present, his mean platelet survival time was 4.01 days and RI was accumulated at the site of aneurysm. His hematological pathophysiology could be explained as consumption coagulopathy in the abdominal aneurysm. Using scanning electron-microscopy, we found entrapped platelets with fine fibrin network were found indicating platelet consumption at the site of intraluminal thrombi. It was concluded that these imaging techniques using radioisotopes were very useful not only for detecting intraluminal thrombi but for diagnosing consumption coagulopathy and disseminated intravascular coagulation even where there is no clinical manifestation.

  15. Analysis on risk factors of high thrombus formation burden in patients with acute myocardial infartion%急性心肌梗死高血栓负荷的危险因素分析

    Institute of Scientific and Technical Information of China (English)

    高海; 金彦彦; 叶明


    目的 探讨急性心肌梗死患者梗死相关动脉高血栓负荷的危险因素.方法 按照冠脉造影结果将236例急性心肌梗死患者分为高血栓负荷组175例、低血栓负荷组61例.通过观察患者的一般临床情况,检测生化指标、CRP及血浆脑钠肽,将可能的相关因素进行Logistic多因素回归分析.结果 2组患者在性别构成、年龄、高血压、陈旧性心肌梗死、既往血运重建病史、基础心率、血压等方面具有可比性.高血栓负荷组中吸烟患者比例明显高于低血栓负荷组(69.7% vs 45.9% P=0.018),CRP水平(mg/L)显著高于低血栓负荷组(9.31±2.35 vs 7.37±3.89,P=0.038).将糖尿病、吸烟、白细胞、CRP、D-二聚体(D-dimer)等可能的危险因素进行Logistic回归分析,发现吸烟(OR=2.056,95%CI 1.435~5.160,P=0.024)、CRP(OR=1.379,95%CI 1.048~4.306,P=0.015)是AMI患者高血栓负荷的独立危险因素.结论 吸烟、CRP是AMI患者高血栓负荷的独立危险因素.%Objective To explore related factors for high thrombus formation burden of infarct related arteries ( IRA ) in the acute phase of ST segment elevated myocardial infarction ( STEMI ) . Methods 236 acute myocardial infarction ( AMI ) patients treated with primary percutaneous coronary intervention ( PCI ) were divided into two groups by angiography results obtained during PCI: High thrombus formation burden group( n = 175 ) and low thrombus formation burden group( n =61 ). Blood samples were collected before PCI for measuring circulating levels of C reactive protein( CRP ), brain natriuretic peptide ( BNP ). Logistic analysis was performed. Results Patients in high thrombus formation burden group were significant different from patients in low thrombus formation burden group with smoking (69.5% vs. 45.9%, P =0.018), CRP(9.31 mg/L ± 2.35 mg/L vs. 7.37 mg/L ±3. 89 mg/ L,P =0.038). The results of Logistic regression analysis showed that smoking (OR =2.056, 95% CI 1.435-5.160, P =0

  16. Statins improve the resolution of established murine venous thrombosis: reductions in thrombus burden and vein wall scarring.

    Directory of Open Access Journals (Sweden)

    Chase W Kessinger

    Full Text Available Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT will develop the post-thrombotic syndrome (PTS. Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins--lipid-lowering agents with anti-thrombotic and anti-inflammatory properties--in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice. Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1, tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs, and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy.

  17. Increased platelet count and leucocyte-platelet complex formation in acute symptomatic compared with asymptomatic severe carotid stenosis.

    LENUS (Irish Health Repository)

    McCabe, D J H


    The risk of stroke in patients with recently symptomatic carotid stenosis is considerably higher than in patients with asymptomatic stenosis. In the present study it was hypothesised that excessive platelet activation might partly contribute to this difference.

  18. Extracellular Fibrinogen-binding Protein (Efb) from Staphylococcus aureus Inhibits the Formation of Platelet-Leukocyte Complexes. (United States)

    Posner, Mareike G; Upadhyay, Abhishek; Abubaker, Aisha Alsheikh; Fortunato, Tiago M; Vara, Dina; Canobbio, Ilaria; Bagby, Stefan; Pula, Giordano


    Extracellular fibrinogen-binding protein (Efb) from Staphylococcus aureus inhibits platelet activation, although its mechanism of action has not been established. In this study, we discovered that the N-terminal region of Efb (Efb-N) promotes platelet binding of fibrinogen and that Efb-N binding to platelets proceeds via two independent mechanisms: fibrinogen-mediated and fibrinogen-independent. By proteomic analysis of Efb-interacting proteins within platelets and confirmation by pulldown assays followed by immunoblotting, we identified P-selectin and multimerin-1 as novel Efb interaction partners. The interaction of both P-selectin and multimerin-1 with Efb is independent of fibrinogen. We focused on Efb interaction with P-selectin. Excess of P-selectin extracellular domain significantly impaired Efb binding by activated platelets, suggesting that P-selectin is the main receptor for Efb on the surface of activated platelets. Efb-N interaction with P-selectin inhibited P-selectin binding to its physiological ligand, P-selectin glycoprotein ligand-1 (PSGL-1), both in cell lysates and in cell-free assays. Because of the importance of P-selectin-PSGL-1 binding in the interaction between platelets and leukocytes, we tested human whole blood and found that Efb abolishes the formation of platelet-monocyte and platelet-granulocyte complexes. In summary, we present evidence that in addition to its documented antithrombotic activity, Efb can play an immunoregulatory role via inhibition of P-selectin-PSGL-1-dependent formation of platelet-leukocyte complexes.

  19. Abnormal whole blood thrombi in humans with inherited platelet receptor defects.

    Directory of Open Access Journals (Sweden)

    Francis J Castellino

    Full Text Available To delineate the critical features of platelets required for formation and stability of thrombi, thromboelastography and platelet aggregation measurements were employed on whole blood of normal patients and of those with Bernard-Soulier Syndrome (BSS and Glanzmann's Thrombasthenia (GT. We found that separation of platelet activation, as assessed by platelet aggregation, from that needed to form viscoelastic stable whole blood thrombi, occurred. In normal human blood, ristocetin and collagen aggregated platelets, but did not induce strong viscoelastic thrombi. However, ADP, arachidonic acid, thrombin, and protease-activated-receptor-1 and -4 agonists, stimulated both processes. During this study, we identified the genetic basis of a very rare double heterozygous GP1b deficiency in a BSS patient, along with a new homozygous GP1b inactivating mutation in another BSS patient. In BSS whole blood, ADP responsiveness, as measured by thrombus strength, was diminished, while ADP-induced platelet aggregation was normal. Further, the platelets of 3 additional GT patients showed very weak whole blood platelet aggregation toward the above agonists and provided whole blood thrombi of very low viscoelastic strength. These results indicate that measurements of platelet counts and platelet aggregability do not necessarily correlate with generation of stable thrombi, a potentially significant feature in patient clinical outcomes.

  20. Abnormal whole blood thrombi in humans with inherited platelet receptor defects. (United States)

    Castellino, Francis J; Liang, Zhong; Davis, Patrick K; Balsara, Rashna D; Musunuru, Harsha; Donahue, Deborah L; Smith, Denise L; Sandoval-Cooper, Mayra J; Ploplis, Victoria A; Walsh, Mark


    To delineate the critical features of platelets required for formation and stability of thrombi, thromboelastography and platelet aggregation measurements were employed on whole blood of normal patients and of those with Bernard-Soulier Syndrome (BSS) and Glanzmann's Thrombasthenia (GT). We found that separation of platelet activation, as assessed by platelet aggregation, from that needed to form viscoelastic stable whole blood thrombi, occurred. In normal human blood, ristocetin and collagen aggregated platelets, but did not induce strong viscoelastic thrombi. However, ADP, arachidonic acid, thrombin, and protease-activated-receptor-1 and -4 agonists, stimulated both processes. During this study, we identified the genetic basis of a very rare double heterozygous GP1b deficiency in a BSS patient, along with a new homozygous GP1b inactivating mutation in another BSS patient. In BSS whole blood, ADP responsiveness, as measured by thrombus strength, was diminished, while ADP-induced platelet aggregation was normal. Further, the platelets of 3 additional GT patients showed very weak whole blood platelet aggregation toward the above agonists and provided whole blood thrombi of very low viscoelastic strength. These results indicate that measurements of platelet counts and platelet aggregability do not necessarily correlate with generation of stable thrombi, a potentially significant feature in patient clinical outcomes.

  1. Equid herpesvirus type 1 activates platelets.

    Directory of Open Access Journals (Sweden)

    Tracy Stokol

    Full Text Available Equid herpesvirus type 1 (EHV-1 causes outbreaks of abortion and neurological disease in horses. One of the main causes of these clinical syndromes is thrombosis in placental and spinal cord vessels, however the mechanism for thrombus formation is unknown. Platelets form part of the thrombus and amplify and propagate thrombin generation. Here, we tested the hypothesis that EHV-1 activates platelets. We found that two EHV-1 strains, RacL11 and Ab4 at 0.5 or higher plaque forming unit/cell, activate platelets within 10 minutes, causing α-granule secretion (surface P-selectin expression and platelet microvesiculation (increased small events double positive for CD41 and Annexin V. Microvesiculation was more pronounced with the RacL11 strain. Virus-induced P-selectin expression required plasma and 1.0 mM exogenous calcium. P-selectin expression was abolished and microvesiculation was significantly reduced in factor VII- or X-deficient human plasma. Both P-selectin expression and microvesiculation were re-established in factor VII-deficient human plasma with added purified human factor VIIa (1 nM. A glycoprotein C-deficient mutant of the Ab4 strain activated platelets as effectively as non-mutated Ab4. P-selectin expression was abolished and microvesiculation was significantly reduced by preincubation of virus with a goat polyclonal anti-rabbit tissue factor antibody. Infectious virus could be retrieved from washed EHV-1-exposed platelets, suggesting a direct platelet-virus interaction. Our results indicate that EHV-1 activates equine platelets and that α-granule secretion is a consequence of virus-associated tissue factor triggering factor X activation and thrombin generation. Microvesiculation was only partly tissue factor and thrombin-dependent, suggesting the virus causes microvesiculation through other mechanisms, potentially through direct binding. These findings suggest that EHV-1-induced platelet activation could contribute to the thrombosis

  2. The role of platelets in hemostasis and the effects of snake venom toxins on platelet function. (United States)

    de Queiroz, Mayara Ribeiro; de Sousa, Bruna Barbosa; da Cunha Pereira, Déborah Fernanda; Mamede, Carla Cristine Neves; Matias, Mariana Santos; de Morais, Nadia Cristina Gomes; de Oliveira Costa, Júnia; de Oliveira, Fábio


    The human body has a set of physiological processes, known as hemostasis, which keeps the blood fluid and free of clots in normal vessels; in the case of vascular injury, this process induces the local formation of a hemostatic plug, preventing hemorrhage. The hemostatic system in humans presents complex physiological interactions that involve platelets, plasma proteins, endothelial and subendothelial structures. Disequilibrium in the regulatory mechanisms that control the growth and the size of the thrombus is one of the factors that favors the development of diseases related to vascular disorders such as myocardial infarction and stroke, which are among the leading causes of death in the western world. Interfering with platelet function is a strategy for the treatment of thrombotic diseases. Antiplatelet drugs are used mainly in cases related to arterial thrombosis and interfere in the formation of the platelet plug by different mechanisms. Aspirin (acetylsalicylic acid) is the oldest and most widely used antithrombotic drug. Although highly effective in most cases, aspirin has limitations compared to other drugs used in the treatment of homeostatic disorders. For this reason, research related to molecules that interfere with platelet aggregation are of great relevance. In this regard, snake venoms are known to contain a number of molecules that interfere with hemostasis, including platelet function. The mechanisms by which snake venom components inhibit or activate platelet aggregation are varied and can be used as tools for the diagnosis and the treatment of several hemostatic disorders. The aim of this review is to present the role of platelets in hemostasis and the mechanisms by which snake venom toxins interfere with platelet function. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Lysyl oxidase is associated with increased thrombosis and platelet reactivity. (United States)

    Matsuura, Shinobu; Mi, Rongjuan; Koupenova, Milka; Eliades, Alexia; Patterson, Shenia; Toselli, Paul; Thon, Jonathan; Italiano, Joseph E; Trackman, Philip C; Papadantonakis, Nikolaos; Ravid, Katya


    Lysyl oxidase (LOX) is overexpressed in various pathologies associated with thrombosis, such as arterial stenosis and myeloproliferative neoplasms (MPNs). LOX is elevated in the megakaryocytic lineage of mouse models of MPNs and in patients with MPNs. To gain insight into the role of LOX in thrombosis and platelet function without compounding the influences of other pathologies, transgenic mice expressing LOX in wild-type megakaryocytes and platelets (Pf4-Lox(tg/tg)) were generated. Pf4-Lox(tg/tg) mice had a normal number of platelets; however, time to vessel occlusion after endothelial injury was significantly shorter in Pf4-Lox(tg/tg) mice, indicating a higher propensity for thrombus formation in vivo. Exploring underlying mechanisms, we found that Pf4-Lox(tg/tg) platelets adhere better to collagen and have greater aggregation response to lower doses of collagen compared with controls. Platelet activation in response to the ligand for collagen receptor glycoprotein VI (cross-linked collagen-related peptide) was unaffected. However, the higher affinity of Pf4-Lox(tg/tg) platelets to the collagen sequence GFOGER implies that the collagen receptor integrin α2β1 is affected by LOX. Taken together, our findings demonstrate that LOX enhances platelet activation and thrombosis.


    Directory of Open Access Journals (Sweden)

    Prashanth Kumar


    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  5. Roles of Mac-1 and glycoprotein IIb/IIIa integrins in leukocyte-platelet aggregate formation: stabilization by Mac-1 and inhibition by GpIIb/IIIa blockers. (United States)

    Patko, Zsofia; Csaszar, Albert; Acsady, Gyorgy; Peter, Karlheinz; Schwarz, Meike


    Circulating platelet-leukocyte hetero-aggregates play an important role in acute cardiovascular events and hypersensitivity reactions. The association involves the receptor families of selectins and integrin. The objective of this study was to investigate the role of CD11b/CD18 integrin (Mac-1) in hetero-aggregate formation and search for a counter-receptor on platelets ready to interact with Mac-1. As a model of leukocytes, Mac-1 presenting Chinese hamster ovary (CHO) cells were used to evaluate the role of Mac-1 in hetero-aggregate formation. The amount of CHO cell-bound active and inactive platelets was measured by flow cytometry, while the counter-receptors on platelets were identified via using blocking antibodies. We observed significant platelet adhesion on Mac-1-bearing cells when platelet-rich plasma or activated platelets were present. Inactive platelets did not adhere to Mac-1-bearing cells. Addition of fibrinogen, a ligand of Mac-1 significantly increased platelet binding. CD40L was demonstrated to act similarly on Mac-1. Inhibition of platelet GpIIb/IIIa completely abolished CHO cell-platelet aggregation. In our study, we have shown for the first time that Mac-1 mediates the formation of hetero-aggregates without selectin tethering when Mac-1 ligands such as fibrinogen or CD40L are present and blockers of platelet GpIIb/IIIa are able to diminish this interaction.

  6. The GPVI-Fc fusion protein Revacept reduces thrombus formation and improves vascular dysfunction in atherosclerosis without any impact on bleeding times.

    Directory of Open Access Journals (Sweden)

    Martin Ungerer

    Full Text Available AIMS: Glycoprotein VI (GPVI is a key platelet receptor which mediates plaque-induced platelet activation and consecutive atherothrombosis, but GPVI is also involved in platelet-mediated atheroprogression. Therefore, interference in GPVI-mediated platelet activation has the potential to combine short-term and long-term beneficial effects, specificity and safety especially regarding bleeding complications. METHODS AND RESULTS: We investigated the effects of the soluble dimeric GPVI receptor fusion protein, Revacept, an antagonist of collagen-mediated platelet activation, in an animal model of atherosclerosis: twenty week old rabbits, which had been fed on a cholesterol-rich diet for 8 weeks, received Revacept (8 mg/kg or control twice weekly for 4 weeks. Pharmacokinetics indicated a slight accumulation of the drug in the serum after repeated dosing of Revacept for 3 weeks. A significant improvement of endothelial dysfunction after 0.06 and 0.6 µg/min acetylcholine and a significant decrease of vessel wall thickening were found after Revacept treatment. Accordingly, aortic vessel weight was reduced, and plaque sizes, macrophage and T-cell invasion tended to be reduced in histological evaluations. Bleeding time was determined after tail clipping in mice. Revacept alone or in combination with widely used anti-platelet drugs revealed a high safety margin with no prolongation of bleeding times. CONCLUSION: Repeated doses of Revacept led to a significant improvement of endothelial dysfunction and vascular morphology in atherosclerotic rabbits. Furthermore, no influence of Revacept on bleeding time alone or in combinations with various anti-platelet drugs was found in mice. Thus, the inhibition of collagen-mediated platelet interaction with the atherosclerotic endothelium by Revacept exerts beneficial effects on morphology and vascular function in vivo and seems to have a wide therapeutic window without influencing the bleeding time.

  7. HPA-1 polymorphism of αIIbβ3 modulates platelet adhesion onto immobilized fibrinogen in an in-vitro flow system

    Directory of Open Access Journals (Sweden)

    Mihalj Mario


    Full Text Available Abstract Background Platelet adhesion and subsequent thrombus formation on a subendothelial matrix at the site of vascular damage play a crucial role in the arrest of posttraumatic bleeding but also in different pathological thrombotic events, such as acute coronary syndrome and stroke. Recently published studies have clearly demonstrated that platelet integri αIIbβ3 is intimately involved in the occlusive thrombus formation at the site of endothelial damage. Therefore, any genetic variation in the expression of this receptor may lead to an excessive bleeding or excessive thrombus formation. In this study, we evaluated the influence of HPA-1 polymorphism of integrin αIIbβ3 on platelet adhesion onto immobilized fibrinogen using an in vitro system simulating blood flow. Methods Platelets in anticoagulated whole blood [49 healthy previously genotyped blood donors were labelled with fluorescence dye and perfused through a rectangular flow chamber (shear rates of 50 s-1, 500 s-1 and 1500 s-1. A fluorescence laser-scan microscope was used for visualisation and quantification of platelet adhesion at 15 sec, 1 and 5 minutes after start of perfusion. Results During perfusion, the platelet adhesion linearly increased with regard to exposition time and shear rate. Perfusion of blood preincubated with Abciximab over fibrinogen-coated cover-slips showed reduced platelet adherence (absolute fluorescence: 168 ± 35 U vs. 53000 ± 19000 at control experiments, p Conclusion Our data support the contention that genetically determined variants of platelet integrins αIIbβ3 could play a role in arterial thrombogenesis and thus confirm the hypothesis derived from epidemiological studies.

  8. Improved Human Erythropoiesis and Platelet Formation in Humanized NSGW41 Mice

    Directory of Open Access Journals (Sweden)

    Susann Rahmig


    Full Text Available Human erythro-megakaryopoiesis does not occur in humanized mouse models, preventing the in vivo analysis of human hematopoietic stem cell (HSC differentiation into these lineages in a surrogate host. Here we show that stably engrafted KIT-deficient NOD/SCID Il2rg−/− KitW41/W41 (NSGW41 mice support much improved human erythropoiesis and platelet formation compared with irradiated NSG recipients. Considerable numbers of human erythroblasts and mature thrombocytes are present in the bone marrow and blood, respectively. Morphology, composition, and enucleation capacity of de novo generated human erythroblasts in NSGW41 mice are comparable with those in human bone marrow. Overexpression of human erythropoietin showed no further improvement in human erythrocyte output, but depletion of macrophages led to the appearance of human erythrocytes in the blood. Human erythropoiesis up to normoblasts and platelet formation is fully supported in NSGW41 mice, allowing the analysis of human HSC differentiation into these lineages, the exploration of certain pathophysiologies, and the evaluation of gene therapeutic approaches.

  9. SDF-1α is a novel autocrine activator of platelets operating through its receptor CXCR4. (United States)

    Walsh, Tony G; Harper, Matthew T; Poole, Alastair W


    Platelets store and secrete the chemokine stromal cell-derived factor (SDF)-1α upon platelet activation, but the ability of platelet-derived SDF-1α to signal in an autocrine/paracrine manner mediating functional platelet responses relevant to thrombosis and haemostasis is unknown. We sought to explore the role of platelet-derived SDF-1α and its receptors, CXCR4 and CXCR7 in facilitating platelet activation and determine the mechanism facilitating SDF-1α-mediated regulation of platelet function. Using human washed platelets, CXCR4 inhibition, but not CXCR7 blockade significantly abrogated collagen-mediated platelet aggregation, dense granule secretion and thromboxane (Tx) A2 production. Time-dependent release of SDF-1α from collagen-activated platelets supports a functional role for SDF-1α in this regard. Using an in vitro whole blood perfusion assay, collagen-induced thrombus formation was substantially reduced with CXCR4 inhibition. In washed platelets, recombinant SDF-1α in the range of 20-100 ng/mL(-1) could significantly enhance platelet aggregation responses to a threshold concentration of collagen. These enhancements were completely dependent on CXCR4, but not CXCR7, which triggered TxA2 production and dense granule secretion. Rises in cAMP were significantly blunted by SDF-1α, which could also enhance collagen-mediated Ca2+ mobilisation, both of which were mediated by CXCR4. This potentiating effect of SDF-1α primarily required TxA2 signalling acting upstream of dense granule secretion, whereas blockade of ADP signalling could only partially attenuate SDF-1α-induced platelet activation. Therefore, this study supports a potentially novel autocrine/paracrine role for platelet-derived SDF-1α during thrombosis and haemostasis, through a predominantly TxA2-dependent and ADP-independent pathway.

  10. VAMP-7 links granule exocytosis to actin reorganization during platelet activation. (United States)

    Koseoglu, Secil; Peters, Christian G; Fitch-Tewfik, Jennifer L; Aisiku, Omozuanvbo; Danglot, Lydia; Galli, Thierry; Flaumenhaft, Robert


    Platelet activation results in profound morphologic changes accompanied by release of granule contents. Recent evidence indicates that fusion of granules with the plasma membrane during activation provides auxiliary membrane to cover growing actin structures. Yet little is known about how membrane fusion is coupled with actin reorganization. Vesicle-associated membrane protein (VAMP)-7 is found on platelet vesicles and possesses an N-terminal longin domain capable of linking exocytosis to cytoskeletal remodeling. We have evaluated platelets from VAMP-7(-/-) mice to determine whether this VAMP isoform contributes to granule release and platelet spreading. VAMP-7(-/-) platelets demonstrated a partial defect in dense granule exocytosis and impaired aggregation. α Granule exocytosis from VAMP-7(-/-) platelets was diminished both in vitro and in vivo during thrombus formation. Consistent with a role of VAMP-7 in cytoskeletal remodeling, spreading on matrices was decreased in VAMP-7(-/-) platelets compared to wild-type controls. Immunoprecipitation of VAMP-7 revealed an association with VPS9-domain ankyrin repeat protein (VARP), an adaptor protein that interacts with both membrane-bound and cytoskeleton proteins and with Arp2/3. VAMP-7, VARP, and Arp2/3 localized to the platelet periphery during spreading. These studies demonstrate that VAMP-7 participates in both platelet granule secretion and spreading and suggest a mechanism whereby VAMP-7 links granule exocytosis with actin reorganization.

  11. Platelet Hyperactivity in TNFSF14/LIGHT Knockout Mouse Model of Impaired Healing. (United States)

    Dhall, Sandeep; Karim, Zubair A; Khasawneh, Fadi T; Martins-Green, Manuela


    Objective: Impaired and chronic wounds occur due to defects in one or more of the overlapping stages of healing. However, problems related to the vascular system are critical for nonhealing, and chronic wounds in humans often show the presence of fibrin cuffs/clots. We hypothesized that these clots are due to alterations in platelet function; hence, we have investigated whether alterations in platelet function are present during impaired healing. Approach: Platelets were subjected to different agonists to determine the rate of aggregation and evaluate the molecules involved in adhesion and aggregation that could lead to faster thrombosis and potentially contribute to impaired wound healing. Results: We show that wounding of TNFSF14/LIGHT(-/-) mice, which have impaired healing, leads to an enhanced response in platelet aggregation and a faster time to blood vessel occlusion (thrombosis). In addition, after wounding, platelets from these mice have increased levels of P-selectin, integrin αIIbβ3, and phosphatidylserine, molecules that contribute to platelet adhesion. They also have more extensive open canalicular system than platelets of control mice, suggesting increased surface area for interactions upon activation. Innovation: These results show a novel function for TNFSF14/LIGHT during wound healing. Conclusion: The absence of TNFSF14/LIGHT from the cell surface of platelets causes rapid platelet aggregation and thrombus formation that may contribute to impaired healing by reducing the ability of the blood vessels to transport nutrients and oxygen and other molecules needed for proper healing.

  12. The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors

    Directory of Open Access Journals (Sweden)

    Gianni Francesco Guidetti


    Full Text Available Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.

  13. Rac1 is essential for phospholipase C-gamma2 activation in platelets

    DEFF Research Database (Denmark)

    Pleines, Irina; Elvers, Margitta; Strehl, Amrei


    Platelet activation at sites of vascular injury is triggered through different signaling pathways leading to activation of phospholipase (PL) Cbeta or PLCgamma2. Active PLCs trigger Ca(2+) mobilization and entry, which is a prerequisite for adhesion, secretion, and thrombus formation. PLCbeta...... isoenzymes are activated downstream of G protein-coupled receptors (GPCRs), whereas PLCgamma2 is activated downstream of immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptors, such as the major platelet collagen receptor glycoprotein (GP) VI or CLEC-2. The mechanisms underlying PLC...... regulation are not fully understood. An involvement of small GTPases of the Rho family (Rho, Rac, Cdc42) in PLC activation has been proposed but this has not been investigated in platelets. We here show that murine platelets lacking Rac1 display severely impaired GPVI- or CLEC-2-dependent activation...

  14. Treatment of portal vein tumor thrombus using ~(125)Iodine seed implantation brachytherapy

    Institute of Scientific and Technical Information of China (English)


    We reported two cases of liver metastasis with portal vein tumor thrombus that developed after liver transplantation for hepato cellular carcinoma (HCC). Both the patients were women aged 43 and 55 years, who had liver metastasis and portal vein tumor thrombus formation after liver transplantations for HCC. For the treatment of portal vein tumor thrombus, 125I seeds were implanted into the hepatic tissue under the guidance of preoperative computed tomography (CT) images with a total radiation dose of 130 Gy...

  15. Platelet proteomics. (United States)

    Zufferey, Anne; Fontana, Pierre; Reny, Jean-Luc; Nolli, Severine; Sanchez, Jean-Charles


    Platelets are small cell fragments, produced by megakaryocytes, in the bone marrow. They play an important role in hemostasis and diverse thrombotic disorders. They are therefore primary targets of antithrombotic therapies. They are implicated in several pathophysiological pathways, such as inflammation or wound repair. In blood circulation, platelets are activated by several pathways including subendothelial matrix and thrombin, triggering the formation of the platelet plug. Studying their proteome is a powerful approach to understand their biology and function. However, particular attention must be paid to different experimental parameters, such as platelet quality and purity. Several technologies are involved during the platelet proteome processing, yielding information on protein identification, characterization, localization, and quantification. Recent technical improvements in proteomics combined with inter-disciplinary strategies, such as metabolomic, transcriptomics, and bioinformatics, will help to understand platelets biological mechanisms. Therefore, a comprehensive analysis of the platelet proteome under different environmental conditions may contribute to elucidate complex processes relevant to platelet function regarding bleeding disorders or platelet hyperreactivity and identify new targets for antiplatelet therapy.

  16. Circulating primers enhance platelet function and induce resistance to antiplatelet therapy (United States)

    Blair, T A; Moore, S F; Hers, I


    Background Aspirin and P2Y12 antagonists are antiplatelet compounds that are used clinically in patients with thrombosis. However, some patients are ‘resistant’ to antiplatelet therapy, which increases their risk of developing acute coronary syndromes. These patients often present with an underlying condition that is associated with altered levels of circulating platelet primers and platelet hyperactivity. Platelet primers cannot stimulate platelet activation, but, in combination with physiologic stimuli, significantly enhance platelet function. Objectives To explore the role of platelet primers in resistance to antiplatelet therapy, and to evaluate whether phosphoinositide 3-kinase (PI3K) contributes to this process. Methods and Results We used platelet aggregation, thromboxane A2 production and ex vivo thrombus formation as functional readouts of platelet activity. Platelets were treated with the potent P2Y12 inhibitor AR-C66096, aspirin, or a combination of both, in the presence or absence of the platelet primers insulin-like growth factor-1 (IGF-1) and thrombopoietin (TPO), or the Gz-coupled receptor ligand epinephrine. We found that platelet primers largely overcame the inhibitory effects of antiplatelet compounds on platelet functional responses. IGF-1-mediated and TPO-mediated, but not epinephrine-mediated, enhancements in the presence of antiplatelet drugs were blocked by the PI3K inhibitors wortmannin and LY294002. Conclusions These results demonstrate that platelet primers can contribute to antiplatelet resistance. Furthermore, our data demonstrate that there are PI3K-dependent and PI3K-independent mechanisms driving primer-mediated resistance to antiplatelet therapy. PMID:26039631

  17. Platelet activation through a Bi-leaflet mechanical heart valve (United States)

    Hedayat, Mohammadali; Borazjani, Iman


    Platelet activation is one of the major drawbacks of the Mechanical Heart Valves (MHVs) which can increase the risk of thrombus formation in patients. The platelet activation in MHVs can be due to the abnormal shear stress during the systole, the backward leakage flow during the diastole, and the flow through the hinge region. We investigate the contribution of each of the above mechanism to the activation of platelets in MHVs by performing simulations of the flow through the MHV and in the hinge region. The large scale heart valve simulations are performed in a straight aorta using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm under physiological flow conditions. In addition, in order to perform the simulation of hinge region the flow field boundary conditions are obtained from the largescale simulations during a whole cardiac cycle. In order to investigate the role of hinge flow on platelet activation in MHVs, a 23mm St. Jude Medical Regent valve hinge with three different gap sizes is tested along with different platelet activation models to ensure the consistency of our results with different activation models. We compare the platelet activation of the hinge region against the bulk of the flow during one cardiac cycle. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

  18. Identification of the platelet ADP receptor targeted by antithrombotic drugs. (United States)

    Hollopeter, G; Jantzen, H M; Vincent, D; Li, G; England, L; Ramakrishnan, V; Yang, R B; Nurden, P; Nurden, A; Julius, D; Conley, P B


    Platelets have a crucial role in the maintenance of normal haemostasis, and perturbations of this system can lead to pathological thrombus formation and vascular occlusion, resulting in stroke, myocardial infarction and unstable angina. ADP released from damaged vessels and red blood cells induces platelet aggregation through activation of the integrin GPIIb-IIIa and subsequent binding of fibrinogen. ADP is also secreted from platelets on activation, providing positive feedback that potentiates the actions of many platelet activators. ADP mediates platelet aggregation through its action on two G-protein-coupled receptor subtypes. The P2Y1 receptor couples to Gq and mobilizes intracellular calcium ions to mediate platelet shape change and aggregation. The second ADP receptor required for aggregation (variously called P2Y(ADP), P2Y(AC), P2Ycyc or P2T(AC)) is coupled to the inhibition of adenylyl cyclase through Gi. The molecular identity of the Gi-linked receptor is still elusive, even though it is the target of efficacious antithrombotic agents, such as ticlopidine and clopidogrel and AR-C66096 (ref. 9). Here we describe the cloning of this receptor, designated P2Y12, and provide evidence that a patient with a bleeding disorder has a defect in this gene. Cloning of the P2Y12 receptor should facilitate the development of better antiplatelet agents to treat cardiovascular diseases.

  19. Orthotopic bone formation in titanium fiber mesh loaded with platelet-rich plasma and placed in segmental defects.

    NARCIS (Netherlands)

    Kroese-Deutman, H.C.; Vehof, J.W.M.; Spauwen, P.H.M.; Stoelinga, P.J.W.; Jansen, Jarno


    The effect of platelet-rich plasma (PRP) on bone formation was investigated in a rabbit segmental radial defect model. The purpose of the study was to evaluate the bone inductive properties of PRP with titanium fiber mesh and autologous bone chips in a 15-mm rabbit radial defect model. Eighteen New

  20. The catalytic subunit of protein phosphatase 1 gamma regulates thrombin-induced murine platelet alpha(IIbbeta(3 function.

    Directory of Open Access Journals (Sweden)

    Francisca C Gushiken

    Full Text Available Hemostasis and thrombosis are regulated by agonist-induced activation of platelet integrin alpha(IIbbeta(3. Integrin activation, in turn is mediated by cellular signaling via protein kinases and protein phosphatases. Although the catalytic subunit of protein phosphatase 1 (PP1c interacts with alpha(IIbbeta(3, the role of PP1c in platelet reactivity is unclear.Using gamma isoform of PP1c deficient mice (PP1cgamma(-/-, we show that the platelets have moderately decreased soluble fibrinogen binding and aggregation to low concentrations of thrombin or protease-activated receptor 4 (PAR4-activating peptide but not to adenosine diphosphate (ADP, collagen or collagen-related peptide (CRP. Thrombin-stimulated PP1cgamma(-/- platelets showed decreased alpha(IIbbeta(3 activation despite comparable levels of alpha(IIbbeta(3, PAR3, PAR4 expression and normal granule secretion. Functions regulated by outside-in integrin alpha(IIbbeta(3 signaling like adhesion to immobilized fibrinogen and clot retraction were not altered in PP1cgamma(-/- platelets. Thrombus formation induced by a light/dye injury in the cremaster muscle venules was significantly delayed in PP1cgamma(-/- mice. Phosphorylation of glycogen synthase kinase (GSK3beta-serine 9 that promotes platelet function, was reduced in thrombin-stimulated PP1cgamma(-/- platelets by an AKT independent mechanism. Inhibition of GSK3beta partially abolished the difference in fibrinogen binding between thrombin-stimulated wild type and PP1cgamma(-/- platelets.These studies illustrate a role for PP1cgamma in maintaining GSK3beta-serine9 phosphorylation downstream of thrombin signaling and promoting thrombus formation via fibrinogen binding and platelet aggregation.

  1. JAM-A protects from thrombosis by suppressing integrin αIIbβ3-dependent outside-in signaling in platelets. (United States)

    Naik, Meghna U; Stalker, Timothy J; Brass, Lawrence F; Naik, Ulhas P


    Mounting evidence suggests that agonist-initiated signaling in platelets is closely regulated to avoid excessive responses to injury. A variety of physiologic agonists induce a cascade of signaling events termed as inside-out signaling that culminate in exposure of high-affinity binding sites on integrin α(IIb)β(3). Once platelet activation has occurred, integrin α(IIb)β(3) stabilizes thrombus formation by providing agonist-independent "outside-in" signals mediated in part by contractile signaling. Junctional adhesion molecule A (JAM-A), a member of the cortical thymocyte marker of the Xenopus (CTX) family, was initially identified as a receptor for a platelet stimulatory mAb. Here we show that JAM-A in resting platelets functions as an endogenous inhibitor of platelet function. Genetic ablation of Jam-A in mice enhances thrombotic function of platelets in vivo. The absence of Jam-A results in increase in platelet aggregation ex vivo. This gain of function is not because of enhanced inside-out signaling because granular secretion, Thromboxane A2 (TxA2) generation, as well as fibrinogen receptor activation, are normal in the absence of Jam-A. Interestingly, integrin outside-in signaling such as platelet spreading and clot retraction is augmented in Jam-A-deficient platelets. We conclude that JAM-A normally limits platelet accumulation by inhibiting integrin outside-in signaling thus preventing premature platelet activation.

  2. [Experimental research on the effects of different activators on the formation of platelet-rich gel and the release of bioactive substances in human platelet-rich plasma]. (United States)

    Yang, Y; Zhang, W; Cheng, B


    Objective: To explore the effects of calcium gluconate and thrombin on the formation of platelet-rich gel (PRG) and the release of bioactive substances in human platelet-rich plasma (PRP) and the clinical significance. Methods: Six healthy blood donors who met the inclusion criteria were recruited in our unit from May to August in 2016. Platelet samples of each donor were collected for preparation of PRP. (1) PRP in the volume of 10 mL was collected from each donor and divided into thrombin activation group (TA, added with 0.5 mL thrombin solution in dose of 100 U/mL) and calcium gluconate activation group (CGA, added with 0.5 mL calcium gluconate solution in dose of 100 g/L) according to the random number table, with 5 mL PRP in each group. Then the PRP of the two groups was activated in water bath at 37 ℃ for 1 h. The formation time of PRG was recorded, and the formation situation of PRG was observed within 1 hour of activation. After being activated for 1 h, one part of PRG was collected to observe the distribution of fibrous protein with HE staining, and another part of PRG was collected to observe platelet ultrastructure under transmission electron microscope (TEM). After being activated for 1 h, the supernatant was collected to determine the content of transforming growth factor β(1, )platelet-derived growth factor BB (PDGF-BB), vascular endothelial growth factor, basic fibroblast growth factor (bFGF), epidermal growth factor, and insulin-like growth factorⅠby enzyme-linked immunosorbent assay. (2) Another 10 mL PRP from each donor was collected and grouped as above, and the platelet suspension was obtained after two times of centrifugation and resuspension with phosphate buffered saline, respectively. And then they were treated with corresponding activator for 1 h as that in experiment (1). Nanoparticle tracking analyzer was used to detect the concentrations of microvesicles with different diameters and total microvesicles derived from platelet. Data

  3. Platelet-Derived CCL5 Regulates CXC Chemokine Formation and Neutrophil Recruitment in Acute Experimental Colitis. (United States)

    Yu, Changhui; Zhang, Songen; Wang, Yongzhi; Zhang, Su; Luo, Lingtao; Thorlacius, Henrik


    Accumulating data suggest that platelets not only regulate thrombosis and haemostasis but also inflammatory processes. Platelets contain numerous potent pro-inflammatory compounds, including the chemokines CCL5 and CXCL4, although their role in acute colitis remains elusive. The aim of this study is to examine the role of platelets and platelet-derived chemokines in acute colitis. Acute colitis is induced in female Balb/c mice by administration of 5% dextran sodium sulfate (DSS) for 5 days. Animals receive a platelet-depleting, anti-CCL5, anti-CXCL4, or a control antibody prior to DSS challenge. Colonic tissue is collected for quantification of myeloperoxidase (MPO) activity, CXCL5, CXCL2, interleukin-6 (IL-6), and CCL5 levels as well as morphological analyses. Platelet depletion reduce tissue damage and clinical disease activity index in DSS-exposed animals. Platelet depletion not only reduces levels of CXCL2 and CXCL5 but also levels of CCL5 in the inflamed colon. Immunoneutralization of CCL5 but not CXCL4 reduces tissue damage, CXC chemokine expression, and neutrophil recruitment in DSS-treated animals. These findings show that platelets play a key role in acute colitis by regulating CXC chemokine generation, neutrophil infiltration, and tissue damage in the colon. Moreover, our results suggest that platelet-derived CCL5 is an important link between platelet activation and neutrophil recruitment in acute colitis.

  4. Sulforaphane prevents human platelet aggregation through inhibiting the phosphatidylinositol 3-kinase/Akt pathway. (United States)

    Chuang, Wen-Ying; Kung, Po-Hsiung; Kuo, Chih-Yun; Wu, Chin-Chung


    Sulforaphane, a dietary isothiocyanate found in cruciferous vegetables, has been shown to exert beneficial effects in animal models of cardiovascular diseases. However, its effect on platelet aggregation, which is a critical factor in arterial thrombosis, is still unclear. In the present study, we show that sulforaphane inhibited human platelet aggregation caused by different receptor agonists, including collagen, U46619 (a thromboxane A2 mimic), protease-activated receptor 1 agonist peptide (PAR1-AP), and an ADP P2Y12 receptor agonist. Moreover, sulforaphane significantly reduced thrombus formation on a collagen-coated surface under whole blood flow conditions. In exploring the underlying mechanism, we found that sulforaphane specifically prevented phosphatidylinositol 3-kinase (PI3K)/Akt signalling, without markedly affecting other signlaling pathways involved in platelet aggregation, such as protein kinase C activation, calcium mobilisation, and protein tyrosine phosphorylation. Although sulforaphane did not directly inhibit the catalytic activity of PI3K, it caused ubiquitination of the regulatory p85 subunit of PI3K, and prevented PI3K translocation to membranes. In addition, sulforaphane caused ubiquitination and degradation of phosphoinositide-dependent kinase 1 (PDK1), which is required for Akt activation. Therefore, sulforaphane is able to inhibit the PI3K/Akt pathway at two distinct sites. In conclusion, we have demonstrated that sulforaphane prevented platelet aggregation and reduced thrombus formation in flow conditions; our data also support that the inhibition of the PI3K/Akt pathway by sulforaphane contributes it antiplatelet effects.

  5. Deposition of fibrinogen on the surface of in vitro thrombi prevents platelet adhesion. (United States)

    Owaynat, Hadil; Yermolenko, Ivan S; Turaga, Ramya; Lishko, Valeryi K; Sheller, Michael R; Ugarova, Tatiana P


    The initial accumulation of platelets after vessel injury is followed by thrombin-mediated generation of fibrin which is deposited around the plug. While numerous in vitro studies have shown that fibrin is highly adhesive for platelets, the surface of experimental thrombi in vivo contains very few platelets suggesting the existence of natural anti-adhesive mechanisms protecting stabilized thrombi from platelet accumulation and continuous thrombus propagation. We previously showed that adsorption of fibrinogen on pure fibrin clots results in the formation of a nonadhesive matrix, highlighting a possible role of this process in surface-mediated control of thrombus growth. However, the deposition of fibrinogen on the surface of blood clots has not been examined. In this study, we investigated the presence of intact fibrinogen on the surface of fibrin-rich thrombi generated from flowing blood and determined whether deposited fibrinogen is nonadhesive for platelets. Stabilized fibrin-rich thrombi were generated using a flow chamber and the time that platelets spend on the surface of thrombi was determined by video recording. The presence of fibrinogen and fibrin on the surface of thrombi was analyzed by confocal microscopy using specific antibodies. Examination of the spatial distribution of two proteins revealed the presence of intact fibrinogen on the surface of stabilized thrombi. By manipulating the surface of thrombi to display either fibrin or intact fibrinogen, we found that platelets adhere to fibrin- but not to fibrinogen-coated thrombi. These results indicate that the fibrinogen matrix assembled on the outer layer of stabilized in vitro thrombi protects them from platelet adhesion.

  6. Platelets can neutralize hydrogen peroxide in an acute toxicity model with cells involved in granulation tissue formation. (United States)

    Kandler, Barbara; Maitz, Philipp; Fischer, Michael B; Watzek, Georg; Gruber, Reinhard


    Platelets play a key role in the replacement of the blood clot with granulation tissue during the early steps of bone regeneration. We hypothesized that activated platelets can neutralize locally produced reactive oxygen species, thereby protecting cells involved in granulation tissue formation. The potential of platelet-released supernatant (PRS) to neutralize hydrogen peroxide (H(2)O(2)) was tested in an acute toxicity model with osteogenic, inflammatory, and endothelial cells. In the human fetal osteoblastic cell line 1.19 (hFOB), considerable morphological changes, cell shedding, and dysfunction of the respiratory chain were observed when cells were exposed to 3 mM H(2)O(2). Caspase-3 and poly-(ADP-ribose)-polymerase were not activated, suggesting that cell death occurred by necrosis. Preincubation of osteogenic cells, leukocytes, or endothelial cells with PRS decreased the acute toxicity of H(2)O(2). The capacity of platelets to release H(2)O(2)-detoxifying activity was retained for up to 72 h. Aminotriazole, an inhibitor of catalase, decreased the cytoprotective activity of PRS, whereas blocking of glutathione peroxidase by mercaptosuccinate had no effect. These results suggest that platelet-released catalase can rapidly neutralize cytotoxic amounts of H(2)O(2), a process that may play a role during the early stages of bone regeneration.

  7. Successful catheter directed thrombolysis of IVC and renal vein occlusive thrombus.

    LENUS (Irish Health Repository)

    McCarthy, E


    Thrombus formation is a recognised complication of IVC filter placement, however IVC and bilateral renal vein occlusion secondary to thrombus is much less common. We present a case of infrahepatic caval and bilateral renal vein occlusion secondary to thrombosis of a suprarenal IVC filter. With progressive clinical deterioration and failure of conservative medical management the patient underwent successful mechanical disruption and catheter directed thrombolysis.

  8. The P2Y(12 antagonists, 2MeSAMP and cangrelor, inhibit platelet activation through P2Y(12/G(i-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Binggang Xiang

    Full Text Available BACKGROUND: ADP is an important physiological agonist that induces integrin activation and platelet aggregation through its receptors P2Y(1 (Gα(q-coupled and P2Y(12 (Gα(i-coupled. P2Y(12 plays a critical role in platelet activation and thrombosis. Adenosine-based P2Y(12 antagonists, 2-methylthioadenosine 5'-monophosphate triethylammonium salt hydrate (2MeSAMP and Cangrelor (AR-C69931MX have been widely used to demonstrate the role of P2Y(12 in platelet function. Cangrelor is being evaluated in clinical trials of thrombotic diseases. However, a recent study reported that both 2MeSAMP and Cangrelor raise intra-platelet cAMP levels and inhibit platelet aggregation through a P2Y(12-independent mechanism. METHODOLOGY/PRINCIPAL FINDINGS: The present work, using P2Y(12 deficient mice, sought to clarify previous conflicting reports and to elucidate the mechanisms by which 2MeSAMP and Cangrelor inhibit platelet activation and thrombosis. 2MeSAMP and Cangrelor inhibited aggregation and ATP release of wild-type but not P2Y(12 deficient platelets. 2MeSAMP and Cangrelor neither raised intracellular cAMP concentrations nor induced phosphorylation of vasodilator-stimulated phosphoprotein (VASP in washed human or mouse platelets. Furthermore, unlike the activators (PGI(2 and forskolin of the cAMP pathway, 2MeSAMP and Cangrelor failed to inhibit Ca(2+ mobilization, Akt phosphorylation, and Rap1b activation in P2Y(12 deficient platelets. Importantly, while injection of Cangrelor inhibited thrombus formation in a FeCl(3-induced thrombosis model in wild-type mice, it failed to affect thrombus formation in P2Y(12 deficient mice. CONCLUSIONS: These data together demonstrate that 2MeSAMP and Cangrelor inhibit platelet function through the P2Y(12-dependent mechanism both in vitro and in vivo.

  9. Role of focal adhesion tyrosine kinases in GPVI-dependent platelet activation and reactive oxygen species formation.

    Directory of Open Access Journals (Sweden)

    Naadiya Carrim

    Full Text Available We have previously shown the presence of a TRAF4/p47phox/Hic5/Pyk2 complex associated with the platelet collagen receptor, GPVI, consistent with a potential role of this complex in GPVI-dependent ROS formation. In other cell systems, NOX-dependent ROS formation is facilitated by Pyk2, which along with its closely related homologue FAK are known to be activated and phosphorylated downstream of ligand binding to GPVI.To evaluate the relative roles of Pyk2 and FAK in GPVI-dependent ROS formation and to determine their location within the GPVI signaling pathway.Human and mouse washed platelets (from WT or Pyk2 KO mice were pre-treated with pharmacological inhibitors targeting FAK or Pyk2 (PF-228 and Tyrphostin A9, respectively and stimulated with the GPVI-specific agonist, CRP. FAK, but not Pyk2, was found to be essential for GPVI-dependent ROS production and aggregation. Subsequent human platelet studies with PF-228 confirmed FAK is essential for GPVI-mediated phosphatidylserine exposure, α-granule secretion (P-selectin (CD62P surface expression and integrin αIIbβ3 activation. To determine the precise location of FAK within the GPVI pathway, we analyzed the effect of PF-228 inhibition in CRP-stimulated platelets in conjunction with immunoprecipitation and pulldown analysis to show that FAK is downstream of Lyn, Spleen tyrosine kinase (Syk, PI3-K and Bruton's tyrosine kinase (Btk and upstream of Rac1, PLCγ2, Ca2+ release, PKC, Hic-5, NOX1 and αIIbβ3 activation.Overall, these data suggest a novel role for FAK in GPVI-dependent ROS formation and platelet activation and elucidate a proximal signaling role for FAK within the GPVI pathway.

  10. Protein disulfide isomerase inhibition blocks thrombin generation in humans by interfering with platelet factor V activation (United States)

    Stopa, Jack D.; Neuberg, Donna; Puligandla, Maneka; Furie, Bruce; Zwicker, Jeffrey I.


    BACKGROUND: Protein disulfide isomerase (PDI) is required for thrombus formation. We previously demonstrated that glycosylated quercetin flavonoids such as isoquercetin inhibit PDI activity and thrombus formation in animal models, but whether extracellular PDI represents a viable anticoagulant target in humans and how its inhibition affects blood coagulation remain unknown. METHODS: We evaluated effects of oral administration of isoquercetin on platelet-dependent thrombin generation in healthy subjects and patients with persistently elevated anti-phospholipid antibodies. RESULTS: Following oral administration of 1,000 mg isoquercetin to healthy adults, the measured peak plasma quercetin concentration (9.2 μM) exceeded its IC50 for inhibition of PDI by isoquercetin in vitro (2.5 ± 0.4 μM). Platelet-dependent thrombin generation decreased by 51% in the healthy volunteers compared with baseline (P = 0.0004) and by 64% in the anti-phospholipid antibody cohort (P = 0.015) following isoquercetin ingestion. To understand how PDI affects thrombin generation, we evaluated substrates of PDI identified using an unbiased mechanistic-based substrate trapping approach. These studies identified platelet factor V as a PDI substrate. Isoquercetin blocked both platelet factor Va and thrombin generation with an IC50 of ~5 μM. Inhibition of PDI by isoquercetin ingestion resulted in a 53% decrease in the generation of platelet factor Va (P = 0.001). Isoquercetin-mediated inhibition was reversed with addition of exogenous factor Va. CONCLUSION: These studies show that oral administration of isoquercetin inhibits PDI activity in plasma and diminishes platelet-dependent thrombin generation predominantly by blocking the generation of platelet factor Va. These pharmacodynamic and mechanistic observations represent an important step in the development of a novel class of antithrombotic agents targeting PDI. TRIAL REGISTRATION: (NCT01722669) FUNDING: National Heart

  11. Micro-array profiling exhibits remarkable intra-individual stability of human platelet micro-RNA. (United States)

    Stratz, C; Nührenberg, T G; Binder, H; Valina, C M; Trenk, D; Hochholzer, W; Neumann, F J; Fiebich, B L


    Platelets play an important role in haemostasis and thrombus formation. Latest research identified platelets harbouring so called microRNAs (miRNA). MiRNAs are short single-stranded RNAs modulating gene expression by targeting mRNAs. Limited data exist on inter-individual variability of platelet miRNA profile while no data are available on intra-individual variability. We assessed platelet miRNA profile in five volunteers at five time points over a time course of 10 days; 24 hours prior to the last blood sampling, subjects took 500 mg acetylsalicylic acid (ASA). Platelet miRNA was isolated from leucocyte-depleted platelet-rich plasma, and miRNA array-analysis was performed. Temporal patterns and ASA effect were explored by a linear mixed effects model for each miRNA. For the 20 most abundantly expressed platelet miRNAs, target gene search was performed and an annotation network was created. MiRNA expression profiling of 1,281 human miRNAs revealed relevant expression of 221 miRNAs consistently expressed in all samples at all time points. Correlation of platelet miRNA ranks was highly significant to other studies. Global distribution of miRNA expression was relatively similar in all subjects. No miRNA exhibited a significant effect of time at level 0.05. After 24 hours, no significant effect of ASA was found. Concerning functional implications of the 20 most abundantly expressed miRNAs, we found six functional themes. In conclusion, platelet miRNA profile is remarkably stable over the time period studied. Single-point analysis of platelet miRNA profile is reasonable when inter-individual differences are studied. The functional annotation network points toward extra-platelet effects of platelet miRNAs.

  12. Platelet P2Y12 is involved in murine pulmonary metastasis.

    Directory of Open Access Journals (Sweden)

    Yanhua Wang

    Full Text Available The involvement of platelets in tumor progression is well recognized. The depletion of circulating platelets or pharmacologic inhibitors of platelet activation decreases the metastatic potential of circulating tumor cells in metastasis mouse models. The platelet ADP receptor P2Y12 amplifies the initial hemostatic responses activated by a variety of platelet agonists and stabilizes platelet aggregation, playing a crucial role in granule secretion, integrin activation and thrombus formation. However, the relationship between P2Y12 and tumor progression is not clear. In our study, the Lewis Lung Carcinoma (LLC spontaneous metastatic mouse model was used to evaluate the role of P2Y12 in metastasis. The results demonstrated that P2Y12 deficiency significantly reduced pulmonary metastasis. Further studies indicated that P2Y12 deficiency diminished the ability of LLC cells to induce platelet shape change and release of active TGFβ1 by a non-contact dependent mechanism resulting in a diminished, platelet-induced EMT-like transformation of the LLC cells, and that transformation probably is a prerequisite of LLC cell metastasis. Immunohistochemical analyses indicated an obvious P2Y12 deficiency related attenuation of recruitment of VEGFR1+ bone marrow derived cell clusters, and extracellular matrix fibronectin deposition in lungs, which presumably are required for pre-metastatic niche formation. In contrast to the LLC cells, non-epithelial melanoma B16 cells induced platelet aggregation in a cell number and P2Y12-dependent manner. Also, a platelet induced EMT-like transformation of B16 cells is dependent on P2Y12. In agreement with the LLC cell model, platelet P2Y12 deficiency also results in significantly less lung metastasis in the B16 melanoma experimental metastasis model. These results demonstrate that P2Y12 is a safe drug target for anti-thrombotic therapy, and that P2Y12 may serve as a new target for inhibition of tumor metastasis.

  13. Single platelets seal neutrophil-induced vascular breaches via GPVI during immune-complex-mediated inflammation in mice. (United States)

    Gros, Angèle; Syvannarath, Varouna; Lamrani, Lamia; Ollivier, Véronique; Loyau, Stéphane; Goerge, Tobias; Nieswandt, Bernhard; Jandrot-Perrus, Martine; Ho-Tin-Noé, Benoît


    Platelets protect vascular integrity during inflammation. Recent evidence suggests that this action is independent of thrombus formation and requires the engagement of glycoprotein VI (GPVI), but it remains unclear how platelets prevent inflammatory bleeding. We investigated whether platelets and GPVI act primarily by preventing detrimental effects of neutrophils using models of immune complex (IC)-mediated inflammation in mice immunodepleted in platelets and/or neutrophils or deficient in GPVI. Depletion of neutrophils prevented bleeding in thrombocytopenic and GPVI(-/-) mice during IC-mediated dermatitis. GPVI deficiency did not modify neutrophil recruitment, which was reduced by thrombocytopenia. Neutrophil cytotoxic activities were reduced in thrombocytopenic and GPVI(-/-) mice during IC-mediated inflammation. Intravital microscopy revealed that in this setting, intravascular binding sites for platelets were exposed by neutrophils, and GPVI supported the recruitment of individual platelets to these spots. Furthermore, the platelet secretory response accompanying IC-mediated inflammation was partly mediated by GPVI, and blocking of GPVI signaling impaired the vasculoprotective action of platelets. Together, our results show that GPVI plays a dual role in inflammation by enhancing neutrophil-damaging activities while supporting the activation and hemostatic adhesion of single platelets to neutrophil-induced vascular breaches.

  14. Alterations in plasma membrane promote overexpression and increase of sodium influx through epithelial sodium channel in hypertensive platelets. (United States)

    Cerecedo, D; Martínez-Vieyra, Ivette; Sosa-Peinado, Alejandro; Cornejo-Garrido, Jorge; Ordaz-Pichardo, Cynthia; Benítez-Cardoza, Claudia


    Platelets are small, anucleated cell fragments that activate in response to a wide variety of stimuli, triggering a complex series of intracellular pathways leading to a hemostatic thrombus formation at vascular injury sites. However, in essential hypertension, platelet activation contributes to causing myocardial infarction and ischemic stroke. Reported abnormalities in platelet functions, such as platelet hyperactivity and hyperaggregability to several agonists, contribute to the pathogenesis and complications of thrombotic events associated with hypertension. Platelet membrane lipid composition and fluidity are determining for protein site accessibility, structural arrangement of platelet surface, and response to appropriate stimuli. The present study aimed to demonstrate whether structural and biochemical abnormalities in lipid membrane composition and fluidity characteristic of platelets from hypertensive patients influence the expression of the Epithelial Sodium Channel (ENaC), fundamental for sodium influx during collagen activation. Wb, cytometry and quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assays demonstrated ENaC overexpression in platelets from hypertensive subjects and in relation to control subjects. Additionally, our results strongly suggest a key role of β-dystroglycan as a scaffold for the organization of ENaC and associated proteins. Understanding of the mechanisms of platelet alterations in hypertension should provide valuable information for the pathophysiology of hypertension.

  15. Kaempferol inhibits thrombosis and platelet activation. (United States)

    Choi, Jun-Hui; Park, Se-Eun; Kim, Sung-Jun; Kim, Seung


    The objectives of the present study were to investigate whether kaempferol affects pro-coagulant proteinase activity, fibrin clot formation, blood clot and thrombin (or collagen/epinephrine)-stimulated platelet activation, thrombosis, and coagulation in ICR (Imprinting Control Region) mice and SD (Sprague-Dawley) rats. Kaempferol significantly inhibited the enzymatic activities of thrombin and FXa by 68 ± 1.6% and 52 ± 2.4%, respectively. Kaempferol also inhibited fibrin polymer formation in turbidity. Microscopic analysis was performed using a fluorescent conjugate. Kaempferol completely attenuated phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) 1/2, and phosphoinositide 3-kinase (PI3K)/PKB (AKT) in thrombin-stimulated platelets and delayed aggregation time (clotting) by 34.6% in an assay of collagen/epinephrine-stimulated platelet activation. Moreover, kaempferol protected against thrombosis development in 3 animal models, including collagen/epinephrine- and thrombin-induced acute thromboembolism models and an FeCl3-induced carotid arterial thrombus model. The ex vivo anticoagulant effect of kaempferol was further confirmed in ICR mice. This study demonstrated that kaempferol may be clinically useful due to its ability to reduce or prevent thrombotic challenge.

  16. Thrombus aspiration catheter is a Dottering balloon. (United States)

    Sheshagiri Rao, D; Barik, Ramachandra; Prasad, Akula Siva


    Coronary angiogram in a young man with history of STEMI with delayed presentation revealed subtotal occlusion of left anterior descending artery (LAD) with large thrombotic filling defect distal to the critical lesion. PCI was preferred without delay because of ongoing chest pain. Several runs of thrombus aspiration failed to detect any visible thrombus. However, the immediate angiogram after thrombus aspiration showed complete distal embolization of the thrombus which could have been achieved by Dottering or balloon dilatation. In contrary to the general perception, does thrombus aspiration push more thrombus than it can aspirate?

  17. Effects of calcium-modified titanium implant surfaces on platelet activation, clot formation, and osseointegration. (United States)

    Anitua, Eduardo; Prado, Roberto; Orive, Gorka; Tejero, Ricardo


    The clinical success of load bearing dental and orthopedic implants relies on adequate osseointegration. Because of its favorable properties, titanium is generally considered as the material of choice. Following implant placement, titanium surfaces establish an ionic equilibrium with the surrounding tissues in which calcium plays major roles. Calcium is a cofactor of the coagulation cascade that mediates plasma protein adsorption and intervenes in a number of other intra and extracellular processes relevant for bone regeneration. In this study, titanium surfaces were modified with calcium ions (Ca(2+) surfaces) and their responses to in vitro and in vivo models were analyzed. Unlike unmodified surfaces, Ca(2+) surfaces were superhydrophilic and induced surface clot formation, platelet adsorption and activation when exposed to blood plasma. Interestingly, in vivo osseointegration using a peri-implant gap model in rabbit demonstrated that Ca(2+) surfaces significantly improved peri-implant bone volume and density at 2 weeks and bone implant contact at 8 weeks as compared to the unmodified controls. The combination of Ca(2+) surfaces with plasma rich in growth factors produced significantly more bone contact already at 2 weeks of implantation. These findings suggest the importance of the provisional matrix formation on tissue integration and highlight the clinical potential of Ca(2+) titanium surfaces as efficient stimulators of implant osseointegration.

  18. P-selectin can promote thrombus propagation independently of both von Willebrand factor and thrombospondin-1 in mice. (United States)

    Prakash, P; Nayak, M K; Chauhan, A K


    Essentials The main receptor for platelet glycoprotein (GP) Ibα is von Willebrand factor (VWF). P-selectin and thrombospondin-1 (TSP1) have been suggested as counter receptors for GPIbα. In a laser injury model, P-selectin promotes thrombus propagation independently of VWF and TSP1. In a laser injury model, thrombus persists in interleukin-4 receptor α/GPIbα-transgenic mice.

  19. Formation of nematic liquid crystals of sterically stabilized layered double hydroxide platelets

    NARCIS (Netherlands)

    Mourad, M.C.D.; Devid, E.J.; van Schooneveld, M.M.; Vonk, Ch.; Lekkerkerker, H.N.W.


    Colloidal platelets of hydrotalcite, a layered double hydroxide, have been prepared by coprecipitation at pH 11−12 of magnesium nitrate and aluminum nitrate at two different magnesium to aluminum ratios. Changing the temperature and ionic strength during hydrothermal treatment, the platelets were ta

  20. Device-associated thrombus formation after left atrial appendage occlusion: A systematic review of events reported with the Watchman, the Amplatzer Cardiac Plug and the Amulet. (United States)

    Lempereur, Mathieu; Aminian, Adel; Freixa, Xavier; Gafoor, Sameer; Kefer, Joelle; Tzikas, Apostolos; Legrand, Victor; Saw, Jacqueline


    This study aimed to provide a systematic review of device-associated thrombosis (DAT) after left atrial appendage occlusion (LAAO) with the Watchman, Amplatzer Cardiac Plug, and Amulet devices. DAT is known as a complication of LAAO but data about its clinical impact is scarce. A systematic review of studies evaluating the incidence, treatment and clinical implications of DAT from January 2008 to September 2015 was conducted. A total of 30 studies describing DAT events were included in the analysis. The overall incidence of DAT was 3.9% (82 DAT for 2118 implanted devices). The median time from procedure to diagnosis of DAT was 1.5 months (IQR: 0-2.9). Most cases were diagnosed with transesophageal echocardiogram (TEE). The treatment consisted of low molecular weight heparin (LMWH) in 45.5% of cases, and oral anticoagulation (OAC) or other treatment modalities in 54.5%. Complete thrombus resolution was achieved in 95.0% of cases (100% with LMWH and 89.5% with OAC). Treatment duration varied greatly with a median treatment duration of 45 days (IQR: 14-135). Clinical events related to DAT consisted of neurologic events namely two transient ischemic attacks (2.4%) and four ischemic strokes (4.9%). DAT is an infrequent complication of percutaneous LAAO. It occurs mainly early after the procedure and is associated with a low rate of neurological complications. In the majority of cases, diagnosis is made during follow-up imaging with TEE. Anticoagulation treatment seems to be safe and highly effective. Further studies are needed to evaluate the optimal management of DAT. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Platelet scintigraphy in atherothrombotic disease

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Yoshinari (Osaka National Hospital (Japan))


    Indium-111 platelet scintigraphy for the measurement of in vivo thrombogenicity is a useful noninvasive technique with a number of applications. From 1982 to 1989, we explored clinical relevance of this method for 576 consecutive patients with atherothrombotic disease. There was a disease-related difference in the percentage of positive platelet accumulation; 85% in patients with Dacron bifurcation graft, 75% in abdominal or thoracic aneurysm, 40% in intra-cardiac thrombi, 33% in arteriosclerosis obliterans and 25% in ischemic cerebrovascular disease. Labelled platelets accumulated frequently in the lesion with severe arteriographic abnormality. Aspirin clearly inhibited platelet accumulation on carotid atheroma but the effect of ticlopidine has been less conclusive. Short-term orally active PGI[sub 2] analogue had inhibitory effects on platelet accumulation in carotid atheroma and platelet aggregability, but did not cause significant reduction in plaque size. The results suggest the usefulness of platelet scintigraphy for monitoring the thrombogenicity in various atherothrombotic diseases. It will be necessary, however, to simplify the labelling procedures and to develop a new [sup 99m]Tc-labelled thrombus imaging agent, if thrombus imaging is to be considered for more generall use for patients with atherosclerosis. (author).


    MARTINI, Rosiéli; HÖRNER, Rosmari; RAMPELOTTO, Roberta Filipini; GARZON, Litiérri Razia Litiérri; NUNES, Melise Silveira; TEIXEIRA, Mayza Dalcin; GRAICHEN, Daniel Ângelo Sganzerla


    Platelet Concentrates (PCs) are the blood components with the highest rate of bacterial contamination, and coagulase-negative staphylococci (CoNS) are the most frequently isolated contaminants. This study investigated the biofilm formation of 16 contaminated units out of 691 PCs tested by phenotypic and genotypic methods. Adhesion in Borosilicate Tube (ABT) and Congo Red Agar (CRA) tests were used to assess the presence of biofilm. The presence of icaADC genes was assessed by means of the Polymerase Chain Reaction (PCR) technique. With Vitek(r)2, Staphylococcus haemolyticus was considered the most prevalent CoNS (31.25%). The CRA characterized 43.8% as probable biofilm producers, and for the ABT test, 37.5%. The icaADC genes were identified in seven samples by the PCR. The ABT technique showed 85.7% sensitivity and 100% specificity when compared to the reference method (PCR), and presented strong agreement (k = 0.8). This study shows that species identified as PCs contaminants are considered inhabitants of the normal skin flora and they might become important pathogens. The results also lead to the recommendation of ABT use in laboratory routine for detecting biofilm in CoNS contaminants of PCs. PMID:26910444

  3. Restoration of responsiveness of phospholipase Cγ2-deficient platelets by enforced expression of phospholipase Cγ1.

    Directory of Open Access Journals (Sweden)

    Yongwei Zheng

    Full Text Available Receptor-mediated platelet activation requires phospholipase C (PLC activity to elevate intracellular calcium and induce actin cytoskeleton reorganization. PLCs are classified into structurally distinct β, γ, δ, ε, ζ, and η isoforms. There are two PLCγ isoforms (PLCγ1, PLCγ2, which are critical for activation by tyrosine kinase-dependent receptors. Platelets express both PLCγ1 and PLCγ2. Although PLCγ2 has been shown to play a dominant role in platelet activation, the extent to which PLCγ1 contributes has not been evaluated. To ascertain the relative contributions of PLCγ1 and PLCγ2 to platelet activation, we generated conditionally PLCγ1-deficient, wild-type (WT, PLCγ2-deficient, and PLCγ1/PLCγ2 double-deficient mice and measured the ability of platelets to respond to different agonists. We found that PLCγ2 deficiency abrogated αIIbβ3-dependent platelet spreading, GPVI-dependent platelet aggregation, and thrombus formation on collagen-coated surfaces under shear conditions, which is dependent on both GPVI and αIIbβ3. Addition of exogenous ADP overcame defective spreading of PLCγ2-deficient platelets on immobilized fibrinogen, suggesting that PLCγ2 is required for granule secretion in response to αIIbβ3 ligation. Consistently, αIIbβ3-mediated release of granule contents was impaired in the absence of PLCγ2. In contrast, PLCγ1-deficient platelets spread and released granule contents normally on fibrinogen, exhibited normal levels of GPVI-dependent aggregation, and formed thrombi normally on collagen-coated surfaces. Interestingly, enforced expression of PLCγ1 fully restored GPVI-dependent aggregation and αIIbβ3-dependent spreading of PLCγ2-deficient platelets. We conclude that platelet activation through GPVI and αIIbβ3 utilizes PLCγ2 because PLCγ1 levels are insufficient to support responsiveness, but that PLCγ1 can restore responsiveness if expressed at levels normally achieved by PLCγ2.

  4. Quantitative analysis of human platelet adhesions under a small-scale flow device. (United States)

    Furukawa, Katsuko S; Nakamura, Keigo; Onimura, Yuji; Uchida, Masaki; Ito, Atsuo; Yamane, Takashi; Tamaki, Tamotsu; Ushida, Takashi; Tateishi, Tetsuya


    To realize real-time evaluation of human platelet adhesions onto material surfaces with small volumes of human platelet suspensions, we developed an apparatus consisting of a modified cone and plate-type viscometer, combined with an upright epi-fluorescence microscope. The apparatus allowed real-time evaluation of platelet-material interactions and the initial event of thrombus formation, using small platelet suspension volumes (7.5 microL) under shear flow conditions. To study the dynamic behavior of platelet-material interaction, we chose five representative opaque and transparent materials: acrylate resin (AC), polytetrafluoroethylene (PTFE), polyvynylchrolide (PVC), glass, and a monolayer of human normal umbilical cord vein endothelial cells (EC) on glass under shear flow conditions. The values of adhesiveness of human platelets to the test materials in descending order were as follows: AC > PTFE > PVC > glass > human EC. Under this new small-scale flow system, we could obtain highly reproducible data, which were comparable with results from a previously developed large-scale flow system. Therefore, the newly developed cone and plate-type rheometer is a useful instrument for testing and screening materials, and allows precise quantitative evaluation of human platelet adhesion.

  5. Neonatal repair of left atrial diverticulum with gigantic thrombus without cardiopulmonary bypass. (United States)

    Higashida, Akihiko; Hoashi, Takaya; Sakaguchi, Heima; Ichikawa, Hajime


    A 5-day-old neonate with coarctation of the aorta, hypoplastic aortic arch, large apical muscular ventricular septal defect, and patent ductus arteriosus developed pulmonary over-circulation and systemic hypoperfusion underwent bilateral pulmonary artery banding through median sternotomy as a part of hybrid stage I palliation. At operation, left atrial diverticulum with gigantic thrombus formation at the base of the left atrial appendage was incidentally detected by intraoperative direct echocardiography, and therefore, was successfully resected with the whole thrombus inside it without use of cardiopulmonary bypass. Histopathological finding was compatible with diverticulum. The patient was free from atrial arrhythmia and recurrent thrombus formation.

  6. Cyclophilin A is an important mediator of platelet function by regulating integrin αIIbβ3 bidirectional signalling. (United States)

    Wang, Lian; Soe, Nwe Nwe; Sowden, Mark; Xu, Yingqian; Modjeski, Kristina; Baskaran, Padmamalini; Kim, Yeonghwan; Smolock, Elaine M; Morrell, Craig N; Berk, Bradford C


    Cyclophilin A (CyPA) is an important mediator in cardiovascular diseases. It possesses peptidyl-prolyl cis-trans isomerase activity (PPIase) and chaperone functions, which regulate protein folding, intracellular trafficking and reactive oxygen species (ROS) production. Platelet glycoprotein receptor αIIbβ3 integrin activation is the common pathway for platelet activation. It was our objective to understand the mechanism by which CyPA-regulates αIIbβ3 activation in platelets. Mice deficient for CyPA (CyPA-/-) had prolonged tail bleeding time compared to wild-type (WT) controls despite equivalent platelet numbers. In vitro studies revealed that CyPA-/- platelets exhibited dramatically decreased thrombin-induced platelet aggregation. In vivo, formation of occlusive thrombi following FeCl3 injury was also significantly impaired in CyPA-/- mice compared with WT-controls. Furthermore, CyPA deficiency inhibited flow-induced thrombus formation in vitro. Flow cytometry demonstrated that thrombin-induced ROS production and αIIbβ3 activation were reduced in CyPA-/- platelets. Coimmunoprecipitation studies showed ROS-dependent increased association of CyPA and αIIbβ3. This association was dependent upon the PPIase activity of CyPA. Significantly, fibrinogen-platelet binding, platelet spreading and cytoskeleton reorganisation were also altered in CyPA-/- platelets. Moreover, CyPA deficiency prevented thrombin-induced αIIbβ3 and cytoskeleton association. In conclusion, CyPA is an important mediator in platelet function by regulation of αIIbβ3 bidirectionalsignalling through increased ROS production and facilitating interaction between αIIbβ3 and the cell cytoskeleton.

  7. An Increase in Mean Platelet Volume/Platelet Count Ratio Is Associated with Vascular Access Failure in Hemodialysis Patients (United States)

    Shin, Dong Ho; Rhee, So Yon; Jeon, Hee Jung; Park, Ji-Young; Kang, Shin-Wook; Oh, Jieun


    After stenosis of arteriovenous vascular access in hemodialysis patients, platelets play a crucial role in subsequent thrombus formation, leading to access failure. In a previous study, the mean platelet volume (MPV)/platelet count ratio, but not MPV alone, was shown to be an independent predictor of 4-year mortality after myocardial infarction. However, little is known about the potential influence of MPV/platelet count ratio on vascular access patency in hemodialysis patients. A total of 143 patients undergoing routine hemodialysis were recruited between January 2013 and February 2016. Vascular access failure (VAF) was defined as thrombosis or a decrease of greater than 50% of normal vessel diameter, requiring either surgical revision or percutaneous transluminal angioplasty. Cox proportional hazards model analysis ascertained that the change of MPV/platelet count ratio between baseline and 3 months [Δ(MPV/platelet count ratio)3mo-baseline] had prognostic value for VAF. Additionally, the changes of MPV/platelet count ratio over time were compared in patients with and without VAF by using linear mixed model analysis. Of the 143 patients, 38 (26.6%) were diagnosed with VAF. During a median follow-up of 26.9 months (interquartile range 13.0–36.0 months), Δ(MPV/platelet count ratio)3mo-baseline significantly increased in patients with VAF compared to that in patients without VAF [11.6 (6.3–19.0) vs. 0.8 (-1.8–4.0), P< 0.001]. In multivariate analysis, Δ(MPV/platelet ratio count)3mo-baseline was an independent predictor of VAF, after adjusting for age, sex, diabetes, hypertension, coronary artery disease, cerebrovascular disease, vascular access type, the presence of previous VAF, and antiplatelet drug use (hazard ratio, 1.15; 95% confidence interval, 1.10–1.21; P< 0.001). Moreover, a liner mixed model revealed that there was a significant increase of MPV/platelet count ratio over time in patients with VAF compared to those without VAF (P< 0.001). An

  8. Novel anti-bacterial activities of β-defensin 1 in human platelets: suppression of pathogen growth and signaling of neutrophil extracellular trap formation.

    Directory of Open Access Journals (Sweden)

    Bjoern F Kraemer


    Full Text Available Human β-defensins (hBD are antimicrobial peptides that curb microbial activity. Although hBD's are primarily expressed by epithelial cells, we show that human platelets express hBD-1 that has both predicted and novel antibacterial activities. We observed that activated platelets surround Staphylococcus aureus (S. aureus, forcing the pathogens into clusters that have a reduced growth rate compared to S. aureus alone. Given the microbicidal activity of β-defensins, we determined whether hBD family members were present in platelets and found mRNA and protein for hBD-1. We also established that hBD-1 protein resided in extragranular cytoplasmic compartments of platelets. Consistent with this localization pattern, agonists that elicit granular secretion by platelets did not readily induce hBD-1 release. Nevertheless, platelets released hBD-1 when they were stimulated by α-toxin, a S. aureus product that permeabilizes target cells. Platelet-derived hBD-1 significantly impaired the growth of clinical strains of S. aureus. hBD-1 also induced robust neutrophil extracellular trap (NET formation by target polymorphonuclear leukocytes (PMNs, which is a novel antimicrobial function of β-defensins that was not previously identified. Taken together, these data demonstrate that hBD-1 is a previously-unrecognized component of platelets that displays classic antimicrobial activity and, in addition, signals PMNs to extrude DNA lattices that capture and kill bacteria.

  9. Alkali treatment of microrough titanium surfaces affects macrophage/monocyte adhesion, platelet activation and architecture of blood clot formation

    Directory of Open Access Journals (Sweden)

    V Milleret


    Full Text Available Titanium implants are most commonly used for bone augmentation and replacement due to their favorable osseointegration properties. Here, hyperhydrophilic sand-blasted and acid-etched (SBA titanium surfaces were produced by alkali treatment and their responses to partially heparinized whole human blood were analyzed. Blood clot formation, platelet activation and activation of the complement system was analyzed revealing that exposure time between blood and the material surface is crucial as increasing exposure time results in higher amount of activated platelets, more blood clots formed and stronger complement activation. In contrast, the number of macrophages/monocytes found on alkali-treated surfaces was significantly reduced as compared to untreated SBA Ti surfaces. Interestingly, when comparing untreated to modified SBA Ti surfaces very different blood clots formed on their surfaces. On untreated Ti surfaces blood clots remain thin (below 15 mm, patchy and non-structured lacking large fibrin fiber networks whereas blood clots on differentiated surfaces assemble in an organized and layered architecture of more than 30 mm thickness. Close to the material surface most nucleated cells adhere, above large amounts of non-nucleated platelets remain entrapped within a dense fibrin fiber network providing a continuous cover of the entire surface. These findings might indicate that, combined with findings of previous in vivo studies demonstrating that alkali-treated SBA Ti surfaces perform better in terms of osseointegration, a continuous and structured layer of blood components on the blood-facing surface supports later tissue integration of an endosseous implant.

  10. The modulation of platelet adhesion and activation by chitosan through plasma and extracellular matrix proteins. (United States)

    Lord, Megan S; Cheng, Bill; McCarthy, Simon J; Jung, MoonSun; Whitelock, John M


    Chitosan has been shown to promote initial wound closure events to prevent blood loss. Platelet adhesion and activation are crucial early events in these processes after traumatic bleeding leading to thrombus formation. Platelet adhesion to chitosan was found to be enhanced in the presence of adsorbed plasma and extracellular matrix proteins and was found to be primarily mediated by α(IIb)β(3) integrins, while α(2)β(1) integrins were found to be involved in platelet adhesion to collagen and perlecan. Platelets were found to be activated by chitosan, as shown by an increase in the expression of α(IIb)β(3) integrins and P-selectin, while the extent of activation was modulated by the presence of proteins including perlecan and fibrinogen. Collagen-coated chitosan was found to activate platelets to the same extent as either chitosan or collagen alone. These data support the role of plasma and extracellular matrix proteins in promoting chitosan mediated platelet adhesion and activation supporting the hypothesis that chitosan promotes wound healing via these interactions.

  11. Platelet-Derived Growth Factor B-Chain of Hematopoietic Origin Is Not Necessary for Granulation Tissue Formation and Its Absence Enhances Vascularization


    Buetow, Bernard S; Crosby, Jeffrey R.; Wolfgang E Kaminski; Ramachandran, Ravi K.; Lindahl, Per; Martin, Paul; Betsholtz, Christer; Seifert, Ronald A.; Raines, Elaine W.; Bowen-Pope, Daniel F.


    The hypothesis that wound repair is augmented by delivery of platelet-derived growth factor (PDGF) from platelets and macrophages is an attractive extrapolation from the known activities of PDGF in cell culture and in vivo. To test this hypothesis in mice, we prepared hematopoietic chimeras, in which the hematopoietic system of a normal adult mouse was replaced by the hematopoietic system of a PDGF B-chain −/− or +/+ donor. We initiated local granulation tissue formation either by implanting ...

  12. Platelet full length TFPI-α in healthy volunteers is not affected by sex or hormonal use (United States)

    Winckers, Kristien; Thomassen, Stella; ten Cate, Hugo; Hackeng, Tilman M.


    Background Only 10% of plasma TFPIα (TFPI) exists in the full length form, the rest circulates as a C-terminally truncated form. However, blood platelets exclusively contain full length TFPI, which is released at the site of injury upon platelet activation, and which could play an important local regulatory role in thrombin generation and prevention of thrombosis. Methods The anticoagulant activities of full length and truncated TFPI were investigated using thrombin generation assays. Blood samples were obtained from 30 healthy volunteers (10 male subjects, 10 female subjects, and 10 females using oral contraceptives). Platelet TFPI was released in platelet rich plasma and in platelet isolates using convulxin or thrombin, and measured by free TFPI ELISA and thrombin generation assays. Results Full length TFPI and platelet TFPI were much more potent inhibitors of thrombin generation than truncated TFPI, which was virtually inactive. Although mean plasma TFPI antigen levels decreased from men (0.30 nM) to women (0.20 nM) to women using oral contraceptives (0.11 nM), no relevant differences were found in platelet TFPI among those subgroups. Conclusions Platelets release similar amounts of TFPI regardless of plasma TFPI concentrations and is unaffected by sex or oral contraceptive use. We speculate that platelet TFPI is important to prevent systemic coagulation and thrombosis and restrict thrombus formation to the site of the growing platelet plug. The stable contribution of platelet TFPI to the anticoagulant potential in plasma is likely to become particularly relevant under conditions of low plasma TFPI levels in combination of oral contraceptives use. PMID:28158181

  13. Platelet degranulation and monocyte-platelet complex formation are increased in the acute and convalescent phases after ischaemic stroke or transient ischaemic attack.

    LENUS (Irish Health Repository)

    McCabe, Dominick J H


    Flow cytometric studies suggest that platelets are activated in ischaemic stroke or transient ischaemic attack (TIA). However, few studies have measured circulating leucocyte-platelet complexes in this patient population. Whole blood flow cytometry was used to quantify the expression of CD62P-, CD63-, and PAC1-binding, and the percentages of leucocyte-platelet complexes in acute (1-27 d, n = 79) and convalescent (79-725 d, n = 70) ischaemic cerebrovascular disease (CVD) patients compared with controls without CVD (n = 27). We performed a full blood count, and measured plasma levels of soluble P-selectin, soluble E-selectin, and von Willebrand factor antigen (VWF:Ag) as additional markers of platelet and\\/or endothelial cell activation. The median percentage CD62P expression and the median percentage monocyte-platelet complexes were higher in both acute and convalescent CVD patients than controls (P <\\/= 0.02). The mean white cell count and mean VWF:Ag levels were significantly elevated in the acute and convalescent phases after ischaemic stroke or TIA (P <\\/= 0.02). Otherwise, there was no significant increase in any other marker of platelet or endothelial activation in CVD patients. There was a positive correlation between the percentage expression of CD62P and the percentages of both neutrophil-platelet and monocyte-platelet complexes in the acute phase, and the percentages of all leucocyte-platelet complexes in the convalescent phase after ischaemic CVD. This study provides evidence for ongoing excessive platelet and\\/or endothelial activation in ischaemic CVD patients despite treatment with antithrombotic therapy.

  14. SLAP/SLAP2 prevent excessive platelet (hem)ITAM signaling in thrombosis and ischemic stroke in mice. (United States)

    Cherpokova, Deya; Bender, Markus; Morowski, Martina; Kraft, Peter; Schuhmann, Michael K; Akbar, Sarah M; Sultan, Cheryl S; Hughes, Craig E; Kleinschnitz, Christoph; Stoll, Guido; Dragone, Leonard L; Watson, Steve P; Tomlinson, Michael G; Nieswandt, Bernhard


    Glycoprotein VI and C-type lectin-like receptor 2 are essential platelet activating receptors in hemostasis and thrombo-inflammatory disease, which signal through a (hem)immunoreceptor tyrosine-based activation motif (ITAM)-dependent pathway. The adapter molecules Src-like adapter proteins (SLAP and SLAP2) are involved in the regulation of immune cell surface expression and signaling, but their function in platelets is unknown. In this study, we show that platelets expressed both SLAP isoforms and that overexpression of either protein in a heterologous cell line almost completely inhibited glycoprotein VI and C-type lectin-like receptor 2 signaling. In mice, single deficiency of SLAP or SLAP2 had only moderate effects on platelet function, whereas double deficiency of both adapters resulted in markedly increased signal transduction, integrin activation, granule release, aggregation, procoagulant activity, and thrombin generation in response to (hem)ITAM-coupled, but not G protein-coupled, receptor activation. In vivo, constitutive SLAP/SLAP2 knockout mice displayed accelerated occlusive arterial thrombus formation and a dramatically worsened outcome after focal cerebral ischemia. This was attributed to the absence of both adapter proteins in platelets, as demonstrated by adoptive transfer of Slap(-/-)/Slap2(-/-) platelets into wild-type mice. Our results establish SLAP and SLAP2 as critical inhibitors of platelet (hem)ITAM signaling in the setting of arterial thrombosis and ischemic stroke.

  15. Leukaemia-associated Rho guanine nucleotide exchange factor (LARG) plays an agonist specific role in platelet function through RhoA activation. (United States)

    Zou, Siying; Teixeira, Alexandra M; Yin, Mingzhu; Xiang, Yaozu; Xavier-Ferrucio, Juliana; Zhang, Ping-Xia; Hwa, John; Min, Wang; Krause, Diane S


    Leukemia-Associated RhoGEF (LARG) is highly expressed in platelets, which are essential for maintaining normal haemostasis. We studied the function of LARG in murine and human megakaryocytes and platelets with Larg knockout (KO), shRNA-mediated knockdown and small molecule-mediated inhibition. We found that LARG is important for human, but not murine, megakaryocyte maturation. Larg KO mice exhibit macrothrombocytopenia, internal bleeding in the ovaries and prolonged bleeding times. KO platelets have impaired aggregation, α-granule release and integrin α2bβ3 activation in response to thrombin and thromboxane, but not to ADP. The same agonist-specific reductions in platelet aggregation occur in human platelets treated with a LARG inhibitor. Larg KO platelets have reduced RhoA activation and myosin light chain phosphorylation, suggesting that Larg plays an agonist-specific role in platelet signal transduction. Using two different in vivo assays, Larg KO mice are protected from in vivo thrombus formation. Together, these results establish that LARG regulates human megakaryocyte maturation, and is critical for platelet function in both humans and mice.

  16. Takotsubo Cardiomyopathy With a Rapidly Resolved Left Ventricular Thrombus (United States)

    Anabtawi, Abdel; Roldan, Paola C.; Roldan, Carlos A.


    This article presents the case of a 53-year-old man who presented with acute right superficial femoral and popliteal arterial thrombosis for which he underwent an emergent uncomplicated thrombectomy. He denied preceding cardiovascular or neurologic symptomatology and had no history of coronary or peripheral arterial disease, trauma, hypercoagulability, or malignancy. However, he reported having several days of intense emotional stress prior to presentation. His cardiac exam was normal, his electrocardiogram showed normal sinus rhythm and nonspecific ST-T wave abnormalities, and his troponin levels were normal. Transthoracic echocardiography (TTE) revealed a large (2.4 × 2 cm) apical left ventricle (LV) thrombus, LV apical akinesis, and LV ejection fraction of 40% to 45%. Coronary angiography revealed only luminal irregularities. A repeat TTE performed 3 days after initiating unfractionated heparin revealed complete resolution of the LV thrombus. The patient had an uneventful clinical course and was discharged home in stable condition on oral anticoagulants. The lower incidence of LV thrombus in takotsubo cardiomyopathy (TC) of 1.3% in comparison to 4% to 8% in acute myocardial infarction due to coronary artery disease in the current era of early reperfusion may be explained by the lower extent of ischemic myocardial necrosis associated with TC. This case suggests that the lower extent of myocardial necrosis in TC may also lead to faster resolution of LV thrombus. Therefore, earlier follow-up with TTE (within 2 weeks) and shorter duration of anticoagulation (<3 months) may be considered in patients with TC complicated by LV thrombus formation with or without systemic embolism.

  17. Left atrial ball valve thrombus

    Directory of Open Access Journals (Sweden)

    R. Balaji


    Full Text Available "Ball valve thrombus" which is a spherical free floating clot in left atrium is an often quoted, but uncommonly encountered complication in patients with severe mitral stenosis of rheumatic origin, who are in atrial fibrillation. We describe the case of a 31-year-old lady with rheumatic heart disease, severe mitral stenosis and moderately severe aortic stenosis who had undergone closed mitral valvotomy 13 years ago. The patient presented with an episode of non-exertional syncope and breathlessness on exertion of 6 months duration and was in normal sinus rhythm. Echocardiography facilitated ante-mortem diagnosis and prompt institution of surgery was life saving.

  18. Mice Lacking the Inhibitory Collagen Receptor LAIR-1 Exhibit a Mild Thrombocytosis and Hyperactive Platelets. (United States)

    Smith, Christopher W; Thomas, Steven G; Raslan, Zaher; Patel, Pushpa; Byrne, Maxwell; Lordkipanidzé, Marie; Bem, Danai; Meyaard, Linde; Senis, Yotis A; Watson, Steve P; Mazharian, Alexandra


    Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is a collagen receptor that belongs to the inhibitory immunoreceptor tyrosine-based inhibition motif-containing receptor family. It is an inhibitor of signaling via the immunoreceptor tyrosine-based activation motif-containing collagen receptor complex, glycoprotein VI-FcRγ-chain. It is expressed on hematopoietic cells, including immature megakaryocytes, but is not detectable on platelets. Although the inhibitory function of LAIR-1 has been described in leukocytes, its physiological role in megakaryocytes and in particular in platelet formation has not been explored. In this study, we investigate the role of LAIR-1 in megakaryocyte development and platelet production by generating LAIR-1-deficient mice. Mice lacking LAIR-1 exhibit a significant increase in platelet counts, a prolonged platelet half-life in vivo, and increased proplatelet formation in vitro. Interestingly, platelets from LAIR-1-deficient mice exhibit an enhanced reactivity to collagen and the glycoprotein VI-specific agonist collagen-related peptide despite not expressing LAIR-1, and mice showed enhanced thrombus formation in the carotid artery after ferric chloride injury. Targeted deletion of LAIR-1 in mice results in an increase in signaling downstream of the glycoprotein VI-FcRγ-chain and integrin αIIbβ3 in megakaryocytes because of enhanced Src family kinase activity. Findings from this study demonstrate that ablation of LAIR-1 in megakaryocytes leads to increased Src family kinase activity and downstream signaling in response to collagen that is transmitted to platelets, rendering them hyper-reactive specifically to agonists that signal through Syk tyrosine kinases, but not to G-protein-coupled receptors. © 2017 American Heart Association, Inc.

  19. Multi-Constituent Simulation of Thrombus Deposition

    CERN Document Server

    Wu, Wei-Tao; Massoudi, Mehrdad; Wagner, William R; Antaki, James F


    Based on the transport model of Sorensen et al. (1999), an improved mathematical model describing the process of thrombus deposition and growth was developed. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus phase. The transport and reactions of 10 chemical and biological species are modeled using a system of coupled convection-reaction-diffusion (CRD) equations. These represent three main processes: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: mural thrombus growth in an injured blood vessel and thrombus deposition in a small (125 x 95 micros) crevice observed in vitro. For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. These promising results encourage further simulations to investigate clinical conditions and design factors that affect the risk of t...

  20. Molecular interplay between platelets and the vascular wall in thrombosis and hemostasis. (United States)

    Berna-Erro, Alejandro; Redondo, Pedro C; Lopez, Esther; Albarran, Letizia; Rosado, Juan A


    Hemostasis is an intrinsic property of the vascular system that prevents blood loss during accidental disruption of the vessel wall. Late mechanisms of hemostasis comprise vessel repair and wound healing. In contrast, the early mechanism of hemostasis comprises the quick formation of a blood cell plug, also known as thrombus, whose function is to seal the region of the vessel near the compromised surface or area. Despite the simplicity of the concept, the molecular mechanisms underlying early hemostasis are highly complex. The local rheological properties of the blood flow, the vascular region and the nature of the injury determine the mechanism of thrombogenesis. Components of the plasma, blood cells such as platelets and vascular endothelial cells are involved in thrombosis. This review focuses on platelet-vascular wall interactions during thrombosis and hemostasis and provides an overview of the main underlying molecular mechanisms.

  1. Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation. (United States)

    Bosco, Gerardo; Yang, Zhong-jin; Di Tano, Guglielmo; Camporesi, Enrico M; Faralli, Fabio; Savini, Fabio; Landolfi, Angelo; Doria, Christian; Fanò, Giorgio


    Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation in scuba divers was evaluated. Six volunteers participated in four diving protocols, with 2 wk of recovery between dives. On dive 1, before diving, all divers breathed normally for 20 min at the surface of the sea (Air). On dive 2, before diving, all divers breathed 100% oxygen for 20 min at the surface of the sea [normobaric oxygenation (NBO)]. On dive 3, before diving, all divers breathed 100% O2 for 20 min at 6 m of seawater [msw; hyperbaric oxygenation (HBO) 1.6 atmospheres absolute (ATA)]. On dive 4, before diving, all divers breathed 100% O2 for 20 min at 12 msw (HBO 2.2 ATA). Then they dove to 30 msw (4 ATA) for 20 min breathing air from scuba. After each dive, blood samples were collected as soon as the divers surfaced. Bubbles were measured at 20 and 50 min after decompression and converted to bubble count estimate (BCE) and numeric bubble grade (NBG). BCE and NBG were significantly lower in NBO than in Air [0.142+/-0.034 vs. 0.191+/-0.066 (Pbubbles and platelet activation and, therefore, may be beneficial in reducing the development of decompression sickness.

  2. Crosstalk between platelets and the complement system in immune protection and disease. (United States)

    Verschoor, A; Langer, H F


    Platelets have a central function in repairing vascular damage and stopping acute blood loss. They are equally central to thrombus formation in cardiovascular diseases such as myocardial infarction and ischaemic stroke. Beyond these classical prothrombotic diseases, immune mediated pathologies such as haemolytic uraemic syndrome (HUS) or paroxysmal nocturnal haemoglobinuria (PNH) also feature an increased tendency to form thrombi in various tissues. It has become increasingly clear that the complement system, part of the innate immune system, has an important role in the pathophysiology of these diseases. Not only does complement influence prothrombotic disease, it is equally involved in idiopathic thrombocytopenic purpura (ITP), an autoimmune disease characterised by thrombocytopenia. Thus, there are complex interrelationships between the haemostatic and immune systems, and platelets and complement in particular. Not only does complement influence platelet diseases such as ITP, HUS and PNH, it also mediates interaction between microbes and platelets during systemic infection, influencing the course of infection and development of protective immunity. This review aims to provide an integrative overview of the mechanisms underlying the interactions between complement and platelets in health and disease.

  3. Aortic thrombus formation during a Seldinger aortography

    Energy Technology Data Exchange (ETDEWEB)

    Kiermayer, H.


    Acute aortic thrombosis is a rarely described complication of angiography with the technique of arterial catheterization. In the presented case record, a sudden therapy-resistant rise in blood pressure was accompanied by paraplegia of the lower limbs. The activation of the coagulation system caused by the heterogeneous material brought into the aorta, combined with severe arteriosclerosis, is discussed as a possible cause.

  4. Exacerbation of Glycoprotein VI-Dependent Platelet Responses in a Rhesus Monkey Model of Type 1 Diabetes

    Directory of Open Access Journals (Sweden)

    J. F. Arthur


    Full Text Available Thrombosis is a life-threatening complication of diabetes. Platelet reactivity is crucial to thrombus formation, particularly in arterial vessels and in thrombotic complications causing myocardial infarction or ischaemic stroke, but diabetic patients often respond poorly to current antiplatelet medication. In this study, we used a nonhuman primate model of Type 1 diabetes to measure early downstream signalling events following engagement of the major platelet collagen receptor, glycoprotein (GPVI. Diabetic monkeys were given enough insulin to maintain their blood glucose levels either at ~8 mM (well-controlled diabetes or ~15 mM (poorly controlled diabetes. Flow cytometric analysis was used to measure platelet reactive oxygen species (ROS generation, calcium mobilisation, receptor surface expression, and immature platelet fraction. We observed exacerbated intracellular ROS and calcium flux associated with engagement of GPVI in monkeys with poorly controlled diabetes. GPVI surface levels did not differ between healthy monkeys or the two diabetic groups. Treatment of platelets with the specific Syk inhibitor BAY61-3606 inhibited GPVI-dependent ROS and, importantly, reduced ROS generation in the poorly controlled diabetes group to that observed in healthy monkeys. These data indicate that glycaemic control is important in reducing GPVI-dependent platelet hyperreactivity and point to a potential antithrombotic therapeutic benefit of Syk inhibition in hyperglycaemic diabetes.

  5. Role of G protein signaling in the formation of the fibrin(ogen)-integrin αIIbβ3-actin cytoskeleton complex in platelets. (United States)

    Budnik, Ivan; Shenkman, Boris; Savion, Naphtali


    Effective platelet function requires formation of a physical link between fibrin(ogen), integrin αIIbβ3, and cytoplasmic actin filaments. We investigated the role of the Gαq, Gαi, and Gα12/13 families of heterotrimeric GTP-binding proteins (G proteins) in the assembly of a ligand-αIIbβ3-actin cytoskeleton complex. Selective and combined activation of the G proteins was achieved by using combinations of various platelet agonists and inhibitors. Formation and stability of fibrinogen-αIIbβ3 interaction were evaluated by the extent of platelet aggregation and the rate of eptifibatide-induced platelet disaggregation; association of αIIbβ3 with the cytoskeleton was analyzed by western blot. Formation of the fibrin-αIIbβ3-actin cytoskeleton complex was evaluated by rotational thromboelastometry assay in which clot formation was induced by the mixture of reptilase and factor XIIIa. We demonstrated that involvement of heterotrimeric G proteins in the formation of the ligand-αIIbβ3-cytoskeleton complex depends on whether fibrinogen or fibrin serves as the integrin ligand. Formation of the fibrinogen-αIIbβ3-cytoskeleton complex requires combined activation of at least two G protein pathways while the maximal αIIbβ3-cytoskeleton association and the strongest αIIbβ3-fibrinogen binding supporting irreversible platelet aggregation require combined activation of all three-Gαq, Gαi, and Gα12/13-G protein families. In contrast, formation of the fibrin-αIIbβ3-cytoskeleton complex mediating clot retraction is critically dependent on the activation of the Gαi family, especially on the activation of Gαz.

  6. Hyperglycaemia-induced reciprocal changes in miR-30c and PAI-1 expression in platelets. (United States)

    Luo, Mao; Li, Rong; Ren, Meiping; Chen, Ni; Deng, Xin; Tan, Xiaoyong; Li, Yongjie; Zeng, Min; Yang, Yan; Wan, Qin; Wu, Jianbo


    Type 2 diabetic mellitus (DM2) is associated with accelerated thrombotic complications and is characterized by high levels of plasminogen activator inhibitor-1 (PAI-1). Recent studies show that human platelets have high levels of miR-30c and synthesize considerable active PAI-1. The underlying mechanism of how PAI-1 expression is upregulated in DM2 is poorly understood. We now report that hyperglycaemia-induced repression of miR-30c increases PAI-1 expression and thrombus formation in DM2. Bioinformatic analysis and identification of miRNA targets were assessed using luciferase assays, quantitative real-time PCR and western blots in vitro and in vivo. The changes in miR-30c and PAI-1 levels were identified in platelets from healthy and diabetic individuals. We found that miR-30c directly targeted the 3' UTR of PAI-1 and negatively regulated its expression. miR-30c was negatively correlated with glucose and HbA1c levels in DM2. In HFD-fed diabetic mice, increasing miR-30c expression by lenti-miR-30c significantly decreased the PAI-1 expression and prolonged the time to occlusion in an arterial thrombosis model. Platelet depletion/reinfusion experiments generating mice with selective ablation of PAI-1 demonstrate a major contribution by platelet-derived PAI-1 in the treatment of lenti-miR-30c to thrombus formation. These results provide important implications regarding the regulation of fibrinolysis by platelet miRNA under diabetic mellitus.

  7. Characterization of human platelet binding of recombinant T cell receptor ligand

    Directory of Open Access Journals (Sweden)

    Meza-Romero Roberto


    Full Text Available Abstract Background Recombinant T cell receptor ligands (RTLs are bio-engineered molecules that may serve as novel therapeutic agents for the treatment of neuroinflammatory conditions such as multiple sclerosis (MS. RTLs contain membrane distal α1 plus β1 domains of class II major histocompatibility complex linked covalently to specific peptides that can be used to regulate T cell responses and inhibit experimental autoimmune encephalomyelitis (EAE. The mechanisms by which RTLs impede local recruitment and retention of inflammatory cells in the CNS, however, are not completely understood. Methods We have recently shown that RTLs bind strongly to B cells, macrophages, and dendritic cells, but not to T cells, in an antigenic-independent manner, raising the question whether peripheral blood cells express a distinct RTL-receptor. Our study was designed to characterize the molecular mechanisms by which RTLs bind human blood platelets, and the ability of RTL to modulate platelet function. Results Our data demonstrate that human blood platelets support binding of RTL. Immobilized RTL initiated platelet intracellular calcium mobilization and lamellipodia formation through a pathway dependent upon Src and PI3 kinases signaling. The presence of RTL in solution reduced platelet aggregation by collagen, while treatment of whole blood with RTL prolonged occlusive thrombus formation on collagen. Conclusions Platelets, well-known regulators of hemostasis and thrombosis, have been implicated in playing a major role in inflammation and immunity. This study provides the first evidence that blood platelets express a functional RTL-receptor with a putative role in modulating pathways of neuroinflammation.

  8. Antiplatelet activity of L-sulforaphane by regulation of platelet activation factors, glycoprotein IIb/IIIa and thromboxane A2. (United States)

    Oh, Chung-Hun; Shin, Jang-In; Mo, Sang Joon; Yun, Sung-Jo; Kim, Sung-Hoon; Rhee, Yun-Hee


    L-sulforaphane was identified as an anticarcinogen that could produce quinine reductase and a phase II detoxification enzyme. In recent decades, multi-effects of L-sulforaphane may have been investigated, but, to the authors' knowledge, the antiplatelet activation of L-sulforaphane has not been studied yet.In this study, 2 μg/ml of collagen, 50 μg/ml of ADP and 5 μg/ml of thrombin were used for platelet aggregations with or without L-sulforaphane. L-sulforaphane inhibited the platelet aggregation dose-dependently. Among these platelet activators, collagen was most inhibited by L-sulforaphane, which markedly decreased collagen-induced glycoprotein IIb/IIIa activation and thromboxane A2 (TxA2) formation in vitro. L-sulforaphane also reduced the collagen and epinephrine-induced pulmonary embolism, but did not affect prothrombin time (PT) in vivo. This finding demonstrated that L-sulforaphane inhibited the platelet activation through an intrinsic pathway.L-sulforaphane had a beneficial effect on various pathophysiological pathways of the collagen-induced platelet aggregation and thrombus formation as a selective inhibition of cyclooxygenase and glycoprotein IIb/IIIa antagonist. Thus, we recommend L-sulforaphane as a potential antithrombotic drug.

  9. Platelet adhesion: structural and functional diversity of short dystrophin and utrophins in the formation of dystrophin-associated-protein complexes related to actin dynamics. (United States)

    Cerecedo, Doris; Martínez-Rojas, Dalila; Chávez, Oscar; Martínez-Pérez, Francisco; García-Sierra, Francisco; Rendon, Alvaro; Mornet, Dominique; Mondragón, Ricardo


    Platelets are dynamic cell fragments that modify their shape during activation. Utrophin and dystrophins are minor actin-binding proteins present in muscle and non-muscle cytoskeleton. In the present study, we characterised the pattern of Dp71 isoforms and utrophin gene products by immunoblot in human platelets. Two new dystrophin isoforms were found, Dp71f and Dp71 d, as well as the Up71 isoform and the dystrophin-associated proteins, alpha and beta -dystrobrevins. Distribution of Dp71d/Dp71delta110m, Up400/Up71 and dystrophin-associated proteins in relation to the actin cytoskeleton was evaluated by confocal microscopy in both resting and platelets adhered on glass. Formation of two dystrophin-associated protein complexes (Dp71d/Dp71delta110m approximately DAPC and Up400/Up71 approximately DAPC) was demonstrated by co-immunoprecipitation and their distribution in relation to the actin cytoskeleton was characterised during platelet adhesion. The Dp71d/Dp71delta100m approximately DAPC is maintained mainly at the granulomere and is associated with dynamic structures during activation by adhesion to thrombin-coated surfaces. Participation of both Dp71d/Dp71delta110m approximately DAPC and Up400/Up71 approximately DAPC in the biological roles of the platelets is discussed.

  10. Platelet-derived growth factor receptor beta is critical for zebrafish intersegmental vessel formation.

    Directory of Open Access Journals (Sweden)

    Katie M Wiens

    Full Text Available BACKGROUND: Platelet-derived growth factor receptor beta (PDGFRbeta is a tyrosine kinase receptor known to affect vascular development. The zebrafish is an excellent model to study specific regulators of vascular development, yet the role of PDGF signaling has not been determined in early zebrafish embryos. Furthermore, vascular mural cells, in which PDGFRbeta functions cell autonomously in other systems, have not been identified in zebrafish embryos younger than 72 hours post fertilization. METHODOLOGY/PRINCIPAL FINDINGS: In order to investigate the role of PDGFRbeta in zebrafish vascular development, we cloned the highly conserved zebrafish homolog of PDGFRbeta. We found that pdgfrbeta is expressed in the hypochord, a developmental structure that is immediately dorsal to the dorsal aorta and potentially regulates blood vessel development in the zebrafish. Using a PDGFR tyrosine kinase inhibitor, a morpholino oligonucleotide specific to PDGFRbeta, and a dominant negative PDGFRbeta transgenic line, we found that PDGFRbeta is necessary for angiogenesis of the intersegmental vessels. SIGNIFICANCE/CONCLUSION: Our data provide the first evidence that PDGFRbeta signaling is required for zebrafish angiogenesis. We propose a novel mechanism for zebrafish PDGFRbeta signaling that regulates vascular angiogenesis in the absence of mural cells.

  11. DMSO inhibits human platelet activation through cyclooxygenase-1 inhibition. A novel agent for drug eluting stents?

    Energy Technology Data Exchange (ETDEWEB)

    Asmis, Lars [Institute for Clinical Hematology, University Hospital Zuerich, Zuerich (Switzerland); Tanner, Felix C. [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland); Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Sudano, Isabella [Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Luescher, Thomas F. [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland); Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Camici, Giovanni G., E-mail: [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland)


    Background: DMSO is routinely infused together with hematopoietic cells in patients undergoing myeloablative therapy and was recently found to inhibit smooth muscle cells proliferation and arterial thrombus formation in the mouse by preventing tissue factor (TF), a key activator of the coagulation cascade. This study was designed to investigate whether DMSO prevents platelet activation and thus, whether it may represent an interesting agent to be used on drug eluting stents. Methods and results: Human venous blood from healthy volunteers was collected in citrated tubes and platelet activation was studied by cone and platelet analyzer (CPA) and rapid-platelet-function-assay (RPFA). CPA analysis showed that DMSO-treated platelets exhibit a lower adherence in response to shear stress (-15.54 {+-} 0.9427%, n = 5, P < 0.0001 versus control). Additionally, aggregometry studies revealed that DMSO-treated, arachidonate-stimulated platelets had an increased lag phase (18.0% {+-} 4.031, n = 9, P = 0.0004 versus control) as well as a decreased maximal aggregation (-6.388 {+-} 2.212%, n = 6, P = 0.0162 versus control). Inhibitory action of DMSO could be rescued by exogenous thromboxane A2 and was mediated, at least in part, by COX-1 inhibition. Conclusions: Clinically relevant concentrations of DMSO impair platelet activation by a thromboxane A2-dependent, COX-1-mediated effect. This finding may be crucial for the previously reported anti-thrombotic property displayed by DMSO. Our findings support a role for DMSO as a novel drug to prevent not only proliferation, but also thrombotic complications of drug eluting stents.

  12. A critical role for the transient receptor potential channel type 6 in human platelet activation.

    Directory of Open Access Journals (Sweden)

    Hari Priya Vemana

    Full Text Available While calcium signaling is known to play vital roles in platelet function, the mechanisms underlying its receptor-operated calcium entry component (ROCE remain poorly understood. It has been proposed, but never proven in platelets, that the canonical transient receptor potential channel-6 (TRPC6 mediates ROCE. Nonetheless, we have previously shown that the mouse TRPC6 regulates hemostasis, thrombogenesis by regulating platelet aggregation. In the present studies, we used a pharmacological approach to characterize the role of TRPC6 in human platelet biology. Thus, interestingly, we observed that a TRPC6 inhibitor exerted significant inhibitory effects on human platelet aggregation in a thromboxane receptor (TPR-selective manner; no additional inhibition was observed in the presence of the calcium chelator BAPTA. This inhibitor also significantly inhibited human platelet secretion (dense and alpha granules, integrin IIb-IIIa, Akt and ERK phosphorylation, again, in a TPR-selective manner; no effects were observed in response to ADP receptor stimulation. Furthermore, there was a causal relationship between these inhibitory effects, and the capacity of the TRPC6 inhibitor to abrogate elevation in intracellular calcium, that was again found to be TPR-specific. This effect was not found to be due to antagonism of TPR, as the TRPC6 inhibitor did not displace the radiolabeled antagonist [3H]SQ29,548 from its binding sites. Finally, our studies also revealed that TRPC6 regulates human clot retraction, as well as physiological hemostasis and thrombus formation, in mice. Taken together, our findings demonstrate, for the first time, that TRPC6 directly regulates TPR-dependent ROCE and platelet function. Moreover, these data highlight TRPC6 as a novel promising therapeutic strategy for managing thrombotic disorders.

  13. Influence of Interleukin-1 Beta on Platelet-Poor Plasma Clot Formation: A Potential Impact on Early Bone Healing.

    Directory of Open Access Journals (Sweden)

    Xin Wang

    Full Text Available Hematoma quality (especially the fibrin matrix plays an important role in the bone healing process. Here, we investigated the effect of interleukin-1 beta (IL-1β on fibrin clot formation from platelet-poor plasma (PPP.Five-milliliter of rat whole-blood samples were collected from the hepatic portal vein. All blood samples were firstly standardized via a thrombelastograph (TEG, blood cell count, and the measurement of fibrinogen concentration. PPP was prepared by collecting the top two-fifths of the plasma after centrifugation under 400 × g for 10 min at 20°C. The effects of IL-1β cytokines on artificial fibrin clot formation from PPP solutions were determined by scanning electronic microscopy (SEM, confocal microscopy (CM, turbidity, and clot lysis assays.The lag time for protofibril formation was markedly shortened in the IL-1β treatment groups (243.8 ± 76.85 in the 50 pg/mL of IL-1β and 97.5 ± 19.36 in the 500 pg/mL of IL-1β compared to the control group without IL-1β (543.8 ± 205.8. Maximal turbidity was observed in the control group. IL-1β (500 pg/mL treatment significantly decreased fiber diameters resulting in smaller pore sizes and increased density of the fibrin clot structure formed from PPP (P < 0.05. The clot lysis assay revealed that 500 pg/mL IL-1β induced a lower susceptibility to dissolution due to the formation of thinner and denser fibers.IL-1β can significantly influence PPP fibrin clot structure, which may affect the early bone healing process.

  14. Inhibition of Glycoprotein VI Clustering by Collagen as a Mechanism of Inhibiting Collagen-Induced Platelet Responses: The Example of Losartan.

    Directory of Open Access Journals (Sweden)

    Peng Jiang

    Full Text Available Exposure of platelets to collagen triggers the formation of a platelet clot. Pharmacological agents capable of inhibiting platelet activation by collagen are thus of potential therapeutic interest. Thrombus formation is initiated by the interaction of the GPIb-V-IX complex with collagen-bound vWF, while GPVI interaction with collagen triggers platelet activation that is reinforced by ADP and thromboxane A2. Losartan is an angiotensin II (Ang II type I receptor (AT1R antagonist proposed to have an antiplatelet activity via the inhibition of both the thromboxane A2 (TXA2 receptor (TP and the glycoprotein VI (GPVI. Here, we characterized in vitro the effects of losartan at different doses on platelet responses: losartan inhibited platelet aggregation and secretion induced by 1 μg . mL(-1 and 10 μg . mL(-1 of collagen with an IC50 of ~ 6 μM. Losartan inhibited platelet responses induced by the GPVI specific collagen related peptide but not by the α2β1 specific peptide. However, losartan did not inhibit the binding of recombinant GPVI to collagen, which is not in favor of a simple competition. Indeed, the clustering of GPVI observed in flow cytometry and using the Duolink methodology, was inhibited by losartan. The impact of a therapeutic dose of losartan (100 mg/day on platelet responses was analyzed ex vivo in a double blind study. No statistically significant differences were observed between losartan-treated (n=25 and non-treated (n=30 patients in terms of collagen and U46619-induced platelet activation. These data indicate that in treated patients, losartan does not achieve a measurable antiplatelet effect but provide the proof of concept that inhibiting collagen-induced GPVI clustering is of pharmacological interest to obtain an antithrombotic NCT00763893.

  15. A Case of Myopathy, Encephalopathy, Lactic Acidosis and Stroke-Like Episodes (MELAS) Syndrome with Intracardiac Thrombus [corrected]. (United States)

    Joo, Jung-Chul; Seol, Myung Do; Yoon, Jin Won; Lee, Young Soo; Kim, Dong-Keun; Choi, Yong Hoon; Ahn, Hyo Seong; Cho, Wook Hyun


    Myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystem clinical syndrome manifested by mitochondrial myopathy, encephalopathy, lactic acidosis and recurrent stroke-like episodes. A 27-year-old female with MELAS syndrome presented with cerebral infarction. Echocardiography revealed a thrombus attached to the apex of the hypertrophied left ventricle, with decreased systolic function. The embolism of the intracardiac thrombus might have been the cause of stroke. There should be more consideration given to the increased possibility of intracardiac thrombus formation when a MELAS patient with cardiac involvement is encountered.

  16. Bone marrow AT1 augments neointima formation by promoting mobilization of smooth muscle progenitors via platelet-derived SDF-1{alpha}. (United States)

    Yokoi, Hirokazu; Yamada, Hiroyuki; Tsubakimoto, Yoshinori; Takata, Hiroki; Kawahito, Hiroyuki; Kishida, Sou; Kato, Taku; Matsui, Akihiro; Hirai, Hideyo; Ashihara, Eishi; Maekawa, Taira; Iwai, Masaru; Horiuchi, Masatsugu; Ikeda, Kouji; Takahashi, Tomosaburo; Okigaki, Mitsuhiko; Matsubara, Hiroaki


    Bone marrow (BM)-derived endothelial progenitor cells (EPCs) and vascular smooth muscle progenitor cells (VPCs) contribute to neointima formation, whereas the angiotensin II (Ang II) type 1 receptor (AT(1))-mediated action on BM-derived progenitors remains undefined. A wire-induced vascular injury was performed in the femoral artery of BM-chimeric mice whose BM was repopulated with AT(1)-deficient (BM-Agtr1(-/-)) or wild-type (BM-Agtr1(+/+)) cells. Neointima formation was profoundly reduced by 38% in BM-Agtr1(-/-) mice. Although the number of circulating EPCs (Sca-1(+)Flk-1(+)) and extent of reendothelialization did not differ between the 2 groups, the numbers of both circulating VPCs (c-Kit(-)Sca-1(+)Lin(-)) and tissue VPCs (Sca-1(+)CD31(-)) incorporated into neointima were markedly decreased in BM-Agtr1(-/-) mice. The accumulation of aggregated platelets and their content of stromal cell-derived factor-1alpha (SDF-1alpha) were significantly reduced in BM-Agtr1(-/-) mice, accompanied by a decrease in the serum level of SDF-1alpha. Thrombin-induced platelets aggregation was dose-dependently inhibited (45% at 0.1 IU/mL, PAgtr1(-/-) platelets compared with Agtr1(+/+) platelets, accompanied by the reduced expression and release of SDF-1alpha. The BM-AT(1) receptor promotes neointima formation by regulating the mobilization and homing of BM-derived VPCs in a platelet-derived SDF-1alpha-dependent manner without affecting EPC-mediated reendothelialization.

  17. A Novel Model of Intravital Platelet Imaging Using CD41-ZsGreen1 Transgenic Rats.

    Directory of Open Access Journals (Sweden)

    Makoto Mizuno

    Full Text Available Platelets play pivotal roles in both hemostasis and thrombosis. Although models of intravital platelet imaging are available for thrombosis studies in mice, few are available for rat studies. The present effort aimed to generate fluorescent platelets in rats and assess their dynamics in a rat model of arterial injury. We generated CD41-ZsGreen1 transgenic rats, in which green fluorescence protein ZsGreen1 was expressed specifically in megakaryocytes and thus platelets. The transgenic rats exhibited normal hematological and biochemical values with the exception of body weight and erythroid parameters, which were slightly lower than those of wild-type rats. Platelet aggregation, induced by 20 μM ADP and 10 μg/ml collagen, and blood clotting times were not significantly different between transgenic and wild-type rats. Saphenous arteries of transgenic rats were injured with 10% FeCl3, and the formation of fluorescent thrombi was evaluated using confocal microscopy. FeCl3 caused time-dependent increases in the mean fluorescence intensity of injured arteries of vehicle-treated rats. Prasugrel (3 mg/kg, p.o., administered 2 h before FeCl3, significantly inhibited fluorescence compared with vehicle-treated rats (4.5 ± 0.4 vs. 14.9 ± 2.4 arbitrary fluorescence units at 30 min, respectively, n = 8, P = 0.0037. These data indicate that CD41-ZsGreen1 transgenic rats represent a useful model for intravital imaging of platelet-mediated thrombus formation and the evaluation of antithrombotic agents.

  18. In situ platelets formation into aqueous polymer colloids: The topochemical transformation from single to double layered hydroxide (LSH-LDH) uncovered. (United States)

    Stimpfling, Thomas; Langry, Arthur; Hintze-Bruening, Horst; Leroux, Fabrice


    Layered Single Hydroxide (LSH) of chemical composition Zn5(OH)8(acetate)2·nH2O is synthesized under in situ condition in an aqueous dispersion of an amphiphilic, carboxylate bearing polyester via a modified polyol route. The one-pot LSH generation yields agglomerates of well intercalated platelets, 9-10nm separated from each other. However the corresponding Layered Double Hydroxide (LDH) of formal composition Zn2Al(OH)6 (acetate)·nH2O is found to proceed via the formation of crystallized, similarly spaced LSH sheets in the neighborhood of amorphous Al rich domains as evidenced by X-ray diffraction and transmission electron micrographs. The initial phase segregation effaces over time while LSH platelets convert into the LDH phase. Fingerprinted by the change of in-plane cation accommodation, the associated topochemical reaction of the edge-sharing octahedral LSH platelets involves the transformation of metal lacunae, adjacently covered by one tetrahedral coordinated cation on each side to balance the negative surcharge, into fully occupied and monolayered platelets of edge-sharing octahedral LDH, the former voids being occupied by trivalent cations. This replenishing process of empty sites, coupled with the dissolution of tetrahedral sites is likely to be observed for the first time due to the presence of well separated, polymer intercalated platelets. TEM pictures vision crystal growth arising from the zone of the LSH edge-slab and by using solid state kinetics formalism the associated high activation energy of the first-order reaction agrees well with a plausible dissolution re-precipitation mechanism. The conversion of LSH into LDH platelets may be extended to others cations as Co(2+), Cu(2+), as well as the aluminum source (AlCl3) and the water-soluble polymer (NVP), thus indicating it is a new prevalent facet of LDH.

  19. A point mutation in the EGF-4 domain of β(3) integrin is responsible for the formation of the Sec(a) platelet alloantigen and affects receptor function. (United States)

    Sachs, Ulrich J; Bakchoul, Tamam; Eva, Olga; Giptner, Astrid; Bein, Gregor; Aster, Richard H; Gitter, Maria; Peterson, Julie; Santoso, Sentot


    Neonatal alloimmune thrombocytopenia (NAIT) is caused by fetomaternal platelet incompatibility with maternal antibodies crossing the placenta and destroying fetal platelets. Antibodies against human platelet antigen-1a (HPA-1a) and HPA-5b are responsible for the majority of NAIT cases. We observed a suspected NAIT in a newborn with a platelet count of 25 G/l and petechial haemorrhages. Serological analysis of maternal serum revealed an immunisation against αIIbβ3 on paternal platelets only, indicating the presence of an antibody against a new rare alloantigen (Sec(a)) residing on αIIbβ3. The location of Sec(a) on αIIbβ3 was confirmed by immunoprecipitation. Nucleotide sequence analysis of paternal β3 revealed a single nucleotide exchange (G(1818)T) in exon 11 of the β3 gene (ITGB3), changing Lys(580) (wild-type) to Asn(580) (Sec(a)). Two additional members of the family Sec were typed Sec(a) positive, but none of 300 blood donors. Chinese hamster ovary cells expressing Asn(580), but not Lys(580) αIIbβ3, bound anti-Sec(a), which was corroborated by immunoprecipitation. Adhesion of transfected cells onto immobilised fibrinogen showed reduced binding of the Asn(580) variant compared to wild-type αIIbβ3. Analysis of transfected cells with anti-LIBS and PAC-1 antibody showed reduced binding when compared to the wild-type. No such effects were observed with Sec(a) positive platelets, which, however, are heterozygous for the Lys(580)Asn mutation. In this study, we describe a NAIT case caused by maternal alloimmunisation against a new antigen on αIIbβ3. Analysis with mutant transfected cells showed that the Lys(580)Asn mutation responsible for the formation of the Sec(a) antigenic determinant affects αIIbβ3 receptor function.

  20. Platelet surface expression of SDF-1 is associated with clinical outcomes in the patients with cardiovascular disease. (United States)

    Rath, Dominik; Chatterjee, Madhumita; Bongartz, Angela; Müller, Karin; Droppa, Michal; Stimpfle, Fabian; Borst, Oliver; Zuern, Christine; Vogel, Sebastian; Gawaz, Meinrad; Geisler, Tobias


    Platelet surface expression levels of stromal cell derived factor 1 (SDF-1) are elevated in acute coronary syndrome and associated with LVEF% improvement after myocardial infarction (MI). Platelet SDF-1 might facilitate thrombus formation and endomyocardial expression of SDF-1 is enhanced in inflammatory cardiomyopathy and positively correlates with myocardial fibrosis. The influence of platelet SDF-1 on outcome in the patients with symptomatic coronary artery disease (CAD) is to the best of our knowledge unknown. Blood samples of 608 consecutive CAD patients were collected during the percutaneous coronary intervention and analyzed for surface expression of SDF-1 by flow cytometry. The primary combined endpoint was defined as the composite of either MI, or ischemic stroke, or all-cause death. Secondary endpoints were defined as the aforementioned single events. The patients with baseline platelet SDF-1 levels above the third quartile showed a significantly worse cumulative event-free survival when compared to the patients with lower baseline SDF-1 levels (first to third quartile) (log rank 0.009 for primary combined endpoint and log rank 0.016 for secondary endpoint all-cause death). Multivariate Cox regression analysis showed that SDF-1 levels above the third quartile were independently associated with the primary combined endpoint and the secondary endpoint all-cause death. We provide first clinical evidence that high platelet expression levels of SDF-1 influence clinical outcomes in CAD patients in a negative way.

  1. Effects of danshensu on platelet aggregation and thrombosis: in vivo arteriovenous shunt and venous thrombosis models in rats.

    Directory of Open Access Journals (Sweden)

    Chen Yu

    Full Text Available Danshensu, a type of dihydroxyphenyl lactic acid, is one of the most abundant active phenolic acids in the dried root of Salvia miltiorrhizae (Lamiaceae--widely used traditional Chinese medicine. The effects of danshensu on platelet aggregation and thrombus formation in rats were examined using various methods. It was found that danshensu significantly reduced thrombus weight in 2 experimental thrombosis models; dose-dependent inhibition of adenosine diphosphate (ADP and arachidonic acid (AA-induced platelet aggregation occurred in normal and blood stasis-induced rats; Danshensu also significantly mitigated blood viscosity, plasma viscosity and hematocrit levels. Moreover, danshensu significantly inhibited venous thrombosis-induced expression of cyclooxygenases-2 (COX-2 rather than cyclooxygenases-1(COX-1 in the venous walls, down regulated thromboxane B2 (TXB2 and up regulated 6-keto prostaglandin F1α (6-keto-PGF1α, normalizing the TXB2/6-keto-PGF1α ratio. In addition, danshensu did not induce gastric lesions and even had protective effects on aspirin-induced ulcer formation at doses as high as 60 mg/kg. These findings suggest that the antithrombotic and antiplatelet aggregation effects of danshensu are attributed to its highly selective inhibition of COX-2 and ability to normalize the thromboxane A2(TXA2/prostacyclin(PGI2 balance. These findings suggest that danshensu have great prospects in antithrombotic and antiplatelet therapy.

  2. Three-dimentional simulation of flow-induced platelet activation in artificial heart valves (United States)

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman


    Since the advent of heart valve, several valve types such as mechanical and bio-prosthetic valves have been designed. Mechanical Heart Valves (MHV) are durable but suffer from thromboembolic complications that caused by shear-induced platelet activation near the valve region. Bio-prosthetic Heart Valves (BHV) are known for better hemodynamics. However, they usually have a short average life time. Realistic simulations of heart valves in combination with platelet activation models can lead to a better understanding of the potential risk of thrombus formation in such devices. In this study, an Eulerian approach is developed to calculate the platelet activation in three-dimensional simulations of flow through MHV and BHV using a parallel overset-curvilinear immersed boundary technique. A curvilinear body-fitted grid is used for the flow simulation through the anatomic aorta, while the sharp-interface immersed boundary method is used for simulation of the Left Ventricle (LV) with prescribed motion. In addition, dynamics of valves were calculated numerically using under-relaxed strong-coupling algorithm. Finally, the platelet activation results for BMV and MHV are compared with each other.

  3. Inflammation drives thrombosis after Salmonella infection via CLEC-2 on platelets. (United States)

    Hitchcock, Jessica R; Cook, Charlotte N; Bobat, Saeeda; Ross, Ewan A; Flores-Langarica, Adriana; Lowe, Kate L; Khan, Mahmood; Dominguez-Medina, C Coral; Lax, Sian; Carvalho-Gaspar, Manuela; Hubscher, Stefan; Rainger, G Ed; Cobbold, Mark; Buckley, Christopher D; Mitchell, Tim J; Mitchell, Andrea; Jones, Nick D; Van Rooijen, N; Kirchhofer, Daniel; Henderson, Ian R; Adams, David H; Watson, Steve P; Cunningham, Adam F


    Thrombosis is a common, life-threatening consequence of systemic infection; however, the underlying mechanisms that drive the formation of infection-associated thrombi are poorly understood. Here, using a mouse model of systemic Salmonella Typhimurium infection, we determined that inflammation in tissues triggers thrombosis within vessels via ligation of C-type lectin-like receptor-2 (CLEC-2) on platelets by podoplanin exposed to the vasculature following breaching of the vessel wall. During infection, mice developed thrombi that persisted for weeks within the liver. Bacteria triggered but did not maintain this process, as thrombosis peaked at times when bacteremia was absent and bacteria in tissues were reduced by more than 90% from their peak levels. Thrombus development was triggered by an innate, TLR4-dependent inflammatory cascade that was independent of classical glycoprotein VI-mediated (GPVI-mediated) platelet activation. After infection, IFN-γ release enhanced the number of podoplanin-expressing monocytes and Kupffer cells in the hepatic parenchyma and perivascular sites and absence of TLR4, IFN-γ, or depletion of monocytic-lineage cells or CLEC-2 on platelets markedly inhibited the process. Together, our data indicate that infection-driven thrombosis follows local inflammation and upregulation of podoplanin and platelet activation. The identification of this pathway offers potential therapeutic opportunities to control the devastating consequences of infection-driven thrombosis without increasing the risk of bleeding.

  4. Optic chiasm compression from mass effect and thrombus formation following unsuccessful treatment of a giant supraclinoid ICA aneurysm with the Pipeline device: open surgical bailout with STA-MCA bypass and parent vessel occlusion. (United States)

    Abla, Adib A; Zaidi, Hasan A; Crowley, R Webster; Britz, Gavin W; McDougall, Cameron G; Albuquerque, Felipe C; Spetzler, Robert F


    Pipeline Embolization Devices (PEDs) have been shown to be effective for intracranial internal carotid artery (ICA) aneurysms, and are now approved by the FDA specifically for this use. Potential pitfalls, however, have not yet been described in the pediatric neurosurgical literature. The authors report on a 10-year-old boy who presented to the Barrow Neurological Institute after progressive visual decline. He had undergone placement of a total of 7 telescoping PEDs at another facility for a large ICA aneurysm. Residual filling of the aneurysm and significant expansion of intraaneurysmal thrombus with chiasmal compression on admission images were causes for concern. The patient underwent a surgical bailout with a superficial temporal artery-middle cerebral artery bypass, with parent artery occlusion. Postoperative vascular imaging was notable for successful occlusion of the parent vessel, with no evidence of filling of the aneurysm. Reports on the pitfalls of PEDs in the neurosurgical literature are scarce. To the authors' knowledge this represents the first paper describing a successful open surgical bailout for residual aneurysmal filling and expansion of thrombus after placement of a PED.

  5. ExoU-induced vascular hyperpermeability and platelet activation in the course of experimental Pseudomonas aeruginosa pneumosepsis. (United States)

    Machado, Gloria-Beatriz S; de Assis, Maria-Cristina; Leão, Robson; Saliba, Alessandra M; Silva, Mauricio C A; Suassuna, Jose H; de Oliveira, Albanita V; Plotkowski, Maria-Cristina


    To address the question whether ExoU, a Pseudomonas aeruginosa cytotoxin with phospholipase A2 activity, can induce hemostatic abnormalities during the course of pneumosepsis, mice were instilled i.t. with the ExoU-producing PA103 P. aeruginosa or with a mutant obtained by deletion of the exoU gene. Control animals were instilled with sterile vehicle. To assess the role of ExoU in animal survival, mice were evaluated for 72 h. In all the other experiments, animals were studied at 24 h after infection. PA103-infected mice showed significantly higher mortality rate, lower blood leukocyte concentration, and higher platelet concentration and hematocrit than animals infected with the bacterial mutant, as well as evidences of increased vascular permeability and plasma leakage, which were confirmed by our finding of higher protein concentration in bronchoalveolar lavage fluids and by the Evans blue dye assay. Platelets from PA103-infected mice demonstrated features of activation, assessed by the flow cytometric detection of higher percentage of P-selectin expression and of platelet-derived microparticles as well as by the enzyme immunoassay detection of increased thromboxane A2 concentration in animal plasma. Histopathology of lung and kidney sections from PA103-infected mice exhibited evidences of thrombus formation that were not detected in sections of animals from the other groups. Our results demonstrate the ability of ExoU to induce vascular hyperpermeability, platelet activation, and thrombus formation during P. aeruginosa pneumosepsis, and we speculate that this ability may contribute to the reported poor outcome of patients with severe infection by ExoU-producing P. aeruginosa.

  6. Modelling of thrombus growth in flow with a DPD-PDE method. (United States)

    Tosenberger, A; Ataullakhanov, F; Bessonov, N; Panteleev, M; Tokarev, A; Volpert, V


    Hemostatic plug covering the injury site (or a thrombus in the pathological case) is formed due to the complex interaction of aggregating platelets with biochemical reactions in plasma that participate in blood coagulation. The mechanisms that control clot growth and which lead to growth arrest are not yet completely understood. We model them with numerical simulations based on a hybrid DPD-PDE model. Dissipative particle dynamics (DPD) is used to model plasma flow with platelets while fibrin concentration is described by a simplified reaction-diffusion-advection equation. The model takes into account consecutive stages of clot growth. First, a platelet is weakly connected to the clot and after some time this connection becomes stronger due to other surface receptors involved in platelet adhesion. At the same time, the fibrin mesh is formed inside the clot. This becomes possible because flow does not penetrate the clot and cannot wash out the reactants participating in blood coagulation. Platelets covered by the fibrin mesh cannot attach new platelets. Modelling shows that the growth of a hemostatic plug can stop as a result of its exterior part being removed by the flow thus exposing its non-adhesive core to the flow.

  7. Flavanols and Platelet Reactivity

    Directory of Open Access Journals (Sweden)

    Debra A. Pearson


    Full Text Available Platelet activity and platelet-endothelial cell interactions are important in the acute development of thrombosis, as well as in the pathogenesis of cardiovascular disease. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of flavanol-rich foods, including, grape juice, cocoa and chocolate, suggests that these foods may provide some protection against thrombosis. In the present report, we review a series of in vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa inhibited several measures of platelet activity including, epinephrine- and ADP-induced glycoprotein (GP IIb/IIIa and P-Selectin expression, platelet microparticle formation, and epinephrine-collagen and ADP-collagen induced primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and primary hemostasis were similar to, though less robust than those associated with the use of low dose (81 mg aspirin. These data, coupled with information from other studies, support the concept that flavanols present in cocoa and chocolate can modulate platelet function through a multitude of pathways.

  8. Embolization: critical thrombus height, shear rates, and pulsatility. Patency of blood vessels. (United States)

    Basmadjian, D


    The present article builds on elementary fluid dynamics and previous analyses by the author to delineate approximate boundaries of mural thrombus height Hp, maximum shear rate gamma Max, and flow pulsatility beyond which thrombi are subject to either very high or very low probabilities of embolization. A thrombus height of approximately 0.1 mm emerges as a critical dividing line: Below it, the maximum embolizing shear stress tau s is independent of thrombus height and varies only linearly with shear rate. Above it, tau s quickly approaches a strong quadratic dependence on both thrombus height and shear rate: tau s approximately (Hp gamma)2, significantly increasing the likelihood of an embolizing event. By contrast, convective-diffusive removal of blood components during the initial stages of thrombus formation varies only weakly with gamma 1/3 in all but the smallest vessels. These maximum embolizing stresses are due principally to fluid drag. Acceleration (pulsatile) forces only begin to make their presence felt at gamma less than 500 s-1 and reach parity with fluid drag at gamma approximately 10 s-1, i.e., at a level where the presence of pulsatility is questionable. The results are used to provide maps of domains with high and low probabilities of an embolytic event and of vessel patency. The maps reveal that relatively modest changes in shear rate and/or vessel lumen can cause shifts from high to low likelihood of vessel patency, opening up possible ways of controlling blockage by manipulation of these variables.

  9. Combination of recombinant factor VIIa and fibrinogen corrects clot formation in primary immune thrombocytopenia at very low platelet counts

    DEFF Research Database (Denmark)

    Larsen, Ole H; Stentoft, Jesper; Radia, Deepti


    Haemostatic treatment modalities alternative to platelet transfusion are desirable to control serious acute bleeds in primary immune thrombocytopenia (ITP). This study challenged the hypothesis that recombinant activated factor VII (rFVIIa) combined with fibrinogen concentrate may correct whole b...

  10. Value Thrombus Disease Foundational Disease Preventing and Controlling

    Institute of Scientific and Technical Information of China (English)


    @@ Regardless of artery thrombus, vein thrombus, disseminated intravascular coagulation (DIC) and so on are many because of the natural disease. In it pathogenesis has many sick factors the participation. Moreover manydisease and many syndrome oneself obviousty to become the foundation dsease which the thrombus gets sick.

  11. Platelet mimicry

    DEFF Research Database (Denmark)

    Moghimi, Seyed Moein; Hunter, Alan Christy; Peer, Dan


    Here we critically examine whether coating of nanoparticles with platelet membranes can truly disguise them against recognition by elements of the innate immune system. We further assess whether the "cloaking technology" can sufficiently equip nanoparticles with platelet-mimicking functionalities...

  12. Platelet Count (United States)

    ... their spleen removed surgically Use of birth control pills (oral contraceptives) Some conditions may cause a temporary (transitory) increased ... increased platelet counts include estrogen and birth control pills (oral contraceptives). Mildly decreased platelet counts may be seen in ...

  13. Cardiac MRI documented left ventricular thrombus complicating acute Takotsubo syndrome: an uncommon dilemma. (United States)

    Singh, Veerpal; Mayer, Tom; Salanitri, John; Salinger, Michael H


    Transient left ventricular apical hypokinesis results in a typical ampullary shape and has been described as Takotsubo cardiomyopathy (TCM). We report a case of TCM with the rare complication of left ventricular thrombus formation. Cardiac magnetic resonance imaging aided the diagnosis by characterizing the non-enhancing mass and evaluating the surrounding myocardium for scarring.

  14. Automated entire thrombus density measurements for robust and comprehensive thrombus characterization in patients with acute ischemic stroke

    NARCIS (Netherlands)

    E.M.M. Santos (Emilie M.); W.J. Niessen (Wiro J.); A.J. Yoo (Albert J.); O.A. Berkhemer (Olvert); L.F.M. Beenen (Ludo); C.B. Majoie (Charles); H. Marquering (Henk); P.S.S. Fransen (Puck); D. Beumer (Debbie); L.A. Van Den Berg (Lucie A.); H.F. Lingsma (Hester); W.J. Schonewille (W.); J.A. Vos (Jan Albert); P.J. Nederkoorn (Paul); M.J.H. Wermer (Marieke); M.A. van Walderveen (M.); J. Staals (Julie); J. Hofmeijer; J.A. van Oostayen (Jacques); G.J. Lycklama à Nijeholt (Geert); J. Boiten (Jelis); P.A. Brouwer (Patrick A.); B.J. Emmer (Bart J.); S.F. de Bruijn (S.); L.C. van Dijk (Lukas); L.J. Kappelle; R.H. Lo (Rob H.); E.J. van Dijk (Ewoud); J. De Vries (Joost); P.L.M. de Kort (Paul); J.S.P. van den Berg (Jan); B.A.A.M. Van Hasselt (Boudewijn A. A. M.); L.A.M. Aerden (Leo A.M.); R.J. Dallinga (René J.); M.C. Visser (Marieke); J. Bot (Joseph); P.C. Vroomen (Patrick C.); O.S. Eshghi (Omid S.); T.H.C.M.L. Schreuder (Tobien H. C. M. L.); M.P. Heijboer (Rien); K. Keizer (Koos); A.V. Tielbeek (Alexander); H.M. den Hertog (Heleen); D.G. Gerrits (Dick G.); R.M. van den Berg-Vos (R.); G. Karas (Giorgos); E.W. Steyerberg (Ewout); H.Z. Flach (Zwenneke); M.E.S. Sprengers (Marieke E. S.); S. Jenniskens (Sjoerd); R. Van Den Berg; P.J. Koudstaal (Peter Jan); W.H. van Zwam (Wim); Y.B.W.E.M. Roos; A. van der Lugt (Aad); R.J. van Oostenbrugge (Robert Jan); D.W.J. Dippel (Diederik)


    textabstractBackground and Purpose: In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim

  15. Automated entire thrombus density measurements for robust and comprehensive thrombus characterization in patients with acute ischemic stroke

    NARCIS (Netherlands)

    E.M.M. Santos (Emilie M.); W.J. Niessen (Wiro J.); A.J. Yoo (Albert J.); O.A. Berkhemer (Olvert); L.F.M. Beenen (Ludo); C.B. Majoie (Charles); H. Marquering (Henk); P.S.S. Fransen (Puck); D. Beumer (Debbie); L.A. Van Den Berg (Lucie A.); H.F. Lingsma (Hester); W.J. Schonewille (W.); J.A. Vos (Jan Albert); P.J. Nederkoorn (Paul); M.J.H. Wermer (Marieke); M.A. van Walderveen (M.); J. Staals (Julie); J. Hofmeijer; J.A. van Oostayen (Jacques); G.J. Lycklama à Nijeholt (Geert); J. Boiten (Jelis); P.A. Brouwer (Patrick A.); B.J. Emmer (Bart J.); S.F. de Bruijn (S.); L.C. van Dijk (Lukas); L.J. Kappelle; R.H. Lo (Rob H.); E.J. van Dijk (Ewoud); J. De Vries (Joost); P.L.M. de Kort (Paul); J.S.P. van den Berg (Jan); B.A.A.M. Van Hasselt (Boudewijn A. A. M.); L.A.M. Aerden (Leo A.M.); R.J. Dallinga (René J.); M.C. Visser (Marieke); J. Bot (Joseph); P.C. Vroomen (Patrick C.); O.S. Eshghi (Omid S.); T.H.C.M.L. Schreuder (Tobien H. C. M. L.); M.P. Heijboer (Rien); K. Keizer (Koos); A.V. Tielbeek (Alexander); H.M. den Hertog (Heleen); D.G. Gerrits (Dick G.); R.M. van den Berg-Vos (R.); G. Karas (Giorgos); E.W. Steyerberg (Ewout); H.Z. Flach (Zwenneke); M.E.S. Sprengers (Marieke E. S.); S. Jenniskens (Sjoerd); R. Van Den Berg; P.J. Koudstaal (Peter Jan); W.H. van Zwam (Wim); Y.B.W.E.M. Roos; A. van der Lugt (Aad); R.J. van Oostenbrugge (Robert Jan); D.W.J. Dippel (Diederik)


    textabstractBackground and Purpose: In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim

  16. Automated Entire Thrombus Density Measurements for Robust and Comprehensive Thrombus Characterization in Patients with Acute Ischemic Stroke

    NARCIS (Netherlands)

    Santos, E.M.; Niessen, W.J.; Yoo, A.J.; Berkhemer, O.A.; Beenen, L.F.; Majoie, C.B.; Marquering, H.A.; Dijk, E.J. van


    BACKGROUND AND PURPOSE: In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim was first to

  17. Detection of intracardiac thrombi by scintiphotography with /sup 111/In-labeled autologous platelets

    Energy Technology Data Exchange (ETDEWEB)

    Yui, T.; Uchida, T.; Matsuda, S. (Fukushima Medical Coll. (Japan))


    Detection of intracardiac thrombi by scintigraphy with In-111-oxine labeled autologous platelets was studied in 14 patients with various heart diseases. The results of platelet scintigraphy were compared with those of two dimensional echocardiography. In 4 of the 14 patients, the findings on platelet scintigraphy and echocardiography were both positive. Left atrial thrombi were detected in 3 patients with mitral valve disease (MVD), and left ventricular thrombus in a patient with myocardial infarction with left ventricular aneurysm (MI). The scintigraphy after antiplatelet therapy in the patient with MI did not show any radioactivity on the thrombus. In one of the 14 patients with MVD, the finding on platelet scintigraphy was positive, on the other hand echocardiography was negative. In one of the 14 patients with MVD, the finding on platelet scintigraphy was negative, on the other hand that on echocardiography was positive. The thrombus in this case may be hematologically nonactive thrombus. In-111 platelet scintigraphy is considered to be an excellent method for the diagnosis and in vivo assessment of antithrombotic therapy on intracardiac thrombosis.

  18. Inherited platelet disorders and oral health. (United States)

    Valera, Marie-Cécile; Kemoun, Philippe; Cousty, Sarah; Sie, Pierre; Payrastre, Bernard


    Platelets play a key role in thrombosis and hemostasis. Accumulation of platelets at the site of vascular injury is the first step in the formation of hemostatic plugs, which play a pivotal role in preventing blood loss after injury. Platelet adhesion at sites of injury results in spreading, secretion, recruitment of additional platelets, and formation of platelet aggregates. Inherited platelet disorders are rare causes of bleeding syndromes, ranging from mild bruising to severe hemorrhage. The defects can reflect deficiency or dysfunction of platelet surface glycoproteins, granule contents, cytoskeletal proteins, platelet pro-coagulant function, and signaling pathways. For instance, Bernard-Soulier syndrome and Glanzmann thrombasthenia are attributed to deficiencies of glycoprotein Ib/IX/V and GPIIb/IIIa, respectively, and are rare but severe platelet disorders. Inherited defects that impair platelet secretion and/or signal transduction are among the most common forms of mild platelet disorders and include gray platelet syndrome, Hermansky-Pudlak syndrome, and Chediak-Higashi syndrome. When necessary, desmopressin, antifibrinolytic agents, and transfusion of platelets remain the most common treatment of inherited platelet disorders. Alternative therapies such as recombinant activated factor VII are also available for a limited number of situations. In this review, we will discuss the management of patients with inherited platelet disorders in various clinical situations related to dental cares, including surgical intervention. © 2012 John Wiley & Sons A/S.

  19. Detection of intracardiac thrombi and evaluation of antithrombotic therapy using /sup 111/In-oxine labelled autologous platelets

    Energy Technology Data Exchange (ETDEWEB)

    Yui, Tokuo; Uchida, Tatsumi; Muroi, Shuichi; Matsuda, Shin; Kariyone, Shigeo (Fukushima Medical Coll. (Japan))


    Detection of intracardiac thrombi by scintiphotography using In-111-oxine labelled autologous platelets was done in patients with various heart diseases. Their results were compared with those of two dimensional echocardiography. 1) Left atrial thrombi in 3 patients with mitral valve disease and left ventricular thrombus in a patient with myocardial infarction could be detected by the both methods. In 2 out of above 3 patients with mitral valve disease, 30 and 21 g of left atrial thrombus were certified at surgery. In the patient with myocardial infarction, no radioactivity on the thrombus was shown in the second scintiphotogram during antiplatelet therapy. 2) In a case with mitral stenosis, the image of thrombus by scintiphotography was observed, while none of abnormal echo by two dimensional echocardiography was detected. In this case, only 0.3 g of left atrial thrombus was confirmed at surgery. 3) In an another case of mitral stenosis, the image of thrombus by scintiphotography was not observed, while abnormal echo by two dimensional echocardiography was detected. The thrombus in this case may be hamatologicaly nonactive thrombus. Scintiphotography with In-111-oxine labelled platelets is considered to be an excellent method for the detection of intracardiac thrombi and for the evaluation of antithrombotic therapy in vivo.


    Ponomareva, A A; Nevzorova, T A; Mordakhanova, E R; Andrianova, I A; Litvinov, R I


    Platelets are the anucleated blood cells, wich together with the fibrin stop bleeding (hemostasis). Cellular microvesicles are membrane-surrounded microparticles released into extracellular space upon activation and/or apoptosis of various cells. Platelet-derived macrovesicles from the major population of circulating blood microparticles that play an important role in hemostasis and thrombosis. Despite numerous studies on the pathophysiology of platelet-derived macrovesicles, mechanisms of their formation and structural details remain poorly understood. Here we investigated the ultrastructure of parental platelets and platelet-derived microvesicles formed in vitro by quiescent cells as well as by cells stimulated with one of the following activators: arachidonic acid, ADP, thrombin, calcium ionophore A23187. Using transmission electron microscopy of human platelets and isolated microvesicles, we analyzed the intracellular origin, steps of formation, structural diversity, and size distributions of the subcellular particles. We have revealed that thrombin, unlike other stimuli, not only induced vesiculation of the plasma membrane but also caused break-up of the cells followed by formation of microparticles that are comparable with microvesicles by size. A fraction of these microparticles contained cellular organelles surrounded by a thin membrane. The size of platelet-derived macrovesicles varied from 30 nm to 500 nm, however, the size distributions depended on the nature of a cell-activating stimulus. The results obtained provide new information about the formation of platelet-derived macrovesicles and their structural diversity, wich is important to understand their multiple functions in normal and disease states.

  1. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.


    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  2. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong


    Full Text Available Sudden cardiac death remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g. serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products.

  3. Platelet lipidomic. (United States)

    Dolegowska, B; Lubkowska, A; De Girolamo, L


    Lipids account for 16-19 percent dry platelet matter and includes 65 percent phospholipids, 25 percent neutral lipids and about 8 percent glycosphingolipids. The cell membrane that surrounds platelets is a bilayer that contains different types phospholipids symmetrically distributed in resting platelets, such as phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine, and sphingomyelin. The collapse of lipid asymmetry is exposure of phosphatidylserine in the external leaflet of the plasma bilayer, where it is known to serve at least two major functions: providing a platform for development of the blood coagulation cascade and presenting the signal that induces phagocytosis of apoptotic cells. During activation, this asymmetrical distribution becomes disrupted, and PS and PE become exposed on the cell surface. The transbilayer movement of phosphatidylserine is responsible for the platelet procoagulant activity. Exposure of phosphatidylserine is a flag for macrophage recognition and clearance from the circulation. Platelets, stored at room temperature for transfusion for more than 5 days, undergo changes collectively known as platelet storage lesions. Thus, the platelet lipid composition and its possible modifications over time are crucial for efficacy of platelet rich plasma therapy. Moreover, a number of substances derived from lipids are contained into platelets. Eicosanoids are lipid signaling mediators generated by the action of lipoxygenase and include prostaglandins, thromboxane A2, 12-hydroxyeicosatetraenoic acid. Isoprostanes have a chemical structure similar to this of prostanoids, but are differently produced into the particle, and are ligands for prostaglandins receptors, exhibiting biological activity like thromboxane A2. Endocannabinoids are derivatives from arachidonic acid which could reduce local pain. Phospholipids growth factors (sphingolipids, lysophosphatidic acid, platelet-activating factor) are involved in tissue

  4. Histopathological examination of specimens removed during directional coronary atherectomy in patients presenting with crescendo angina show mural thrombus. (United States)

    Bellamy, C M; Grech, E D; Ashworth, M T; Ramsdale, D R


    Thrombus formation over a fissured coronary atheromatous plaque has been shown by post mortem histological examination to be the pathophysiological mechanism responsible for myocardial ischaemia in those patients who died following a crescendo pattern of angina. Histological examination of plaques responsible for a crescendo pattern of angina in patients who do not die has not been available until recently. We describe two patients who presented with a crescendo pattern of angina. A new technique of coronary revascularization, directional coronary atherectomy, produced symptomatic relief and resolution of myocardial ischaemia. Histological examination of material from the stenosis responsible for their myocardial ischaemia, obtained using this technique, confirmed thrombus formation overlying a fissured atheromatous plaque.

  5. The functional role of platelets in the regulation of angiogenesis. (United States)

    Walsh, Tony G; Metharom, Pat; Berndt, Michael C


    Functionally, platelets are primarily recognized as key regulators of thrombosis and hemostasis. Upon vessel injury, the typically quiescent platelet interacts with subendothelial matrix to regulate platelet adhesion, activation and aggregation, with subsequent induction of the coagulation cascade forming a thrombus. Recently, however, newly described roles for platelets in the regulation of angiogenesis have emerged. Platelets possess an armory of pro- and anti-angiogenic proteins, which are actively sequestered and highly organized in α-granule populations. Platelet activation facilitates their release, eliciting potent angiogenic responses through mechanisms that appear to be tightly regulated. In conjunction, the release of platelet-derived phospholipids and microparticles has also earned merit as synergistic regulators of angiogenesis. Consequently, platelets have been functionally implicated in a range of angiogenesis-dependent processes, including physiological roles in wound healing, vascular development and blood/lymphatic vessel separation, whilst facilitating aberrant angiogenesis in a range of diseases including cancer, atherosclerosis and diabetic retinopathy. Whilst the underlying mechanisms are only starting to be elucidated, significant insights have been established, suggesting that platelets represent a promising therapeutic strategy in diseases requiring angiogenic modulation. Moreover, anti-platelet therapies targeting thrombotic complications also exert protective effects in disorders characterized by persistent angiogenesis.

  6. Antibody formation in pregnant women with maternal-neonatal human platelet antigen mismatch from a hospital in northern Taiwan. (United States)

    Yang, Wan-Hua; Cheng, Chuen-Sheng; Chang, Jin-Biou; Liu, Kuang-Ting; Chang, Junn-Liang


    Neonatal alloimmune thrombocytopenia (NAIT) is a clinical syndrome that resembles hemolytic disease of the newborn, affecting the platelets only. The thrombocytopenia results from the maternal alloantibodies reacting with specific human platelet antigens (HPAs) on the fetal platelets. Forty-four maternal plasma samples were screened for platelet alloantibodies using qualitative solid phase enzyme-linked immunosorbent assay (ELISA) commercial kit (LIFECODES Pakplus, Hologic Gen-Probe GTI Diagnostics, Waukesha, WI, USA), and both the maternal and the corresponding cord blood samples were genotyped (LIFECODES ThromboType, Hologic Gen-Probe GTI Diagnostics, Waukesha, WI, USA). HPA genotyping results correlated with the genetic frequencies in the Taiwan population. A total of 34 newborns (77.3%) had partial HPA genotyping mismatches with the corresponding mothers. The most common partial mismatches between mothers and neonates in HPA genotypes were 13 (29.5%) in both HPA-3b and HPA-15a, followed by 12 (27.3%) in HPA-15b, and 8 (18.2%) in HPA-3a. The frequencies of homozygotic mother with heterozygotic neonate were 15.9% in both HPA-3a and HPA-15b, 9.1% in HPA-15a, 6.8% in HPA-3b, and 2.3% in both HPA-2a and HPA-6a. In this study, maternal HPA antibodies were found in five samples, whereas HLA class I antibodies were found in seven maternal plasma samples from the antibody screen. The results from this study have demonstrated that HPA mismatch is not the main cause for the production of HPA alloantibodies.

  7. Balloon dilatation and thrombus extraction for the treatment of cerebral venous sinus thrombosis

    Directory of Open Access Journals (Sweden)

    Shao-Feng Shui


    Full Text Available Background and Purpose: This study aimed to investigate the efficacy and safety of balloon dilatation and thrombus extraction for the treatment of cerebral venous sinus thrombosis (CVST. Materials and Methods: Twenty-six cases of digital subtraction angiography-confirmed CVST were treated with balloon dilatation and thrombus extraction. Active treatment of primary disease was carried out after cerebral venous sinus recanalization, and the subsequent anticoagulant therapy lasted for 6 months. Results: Recanalization of the cerebral venous sinus was achieved in all 26 patients, and no endovascular treatment-related complications occurred during or after the procedure. At discharge, the Glasgow Coma Scale (GCS of the patients had improved from an average of 12.3 points to 15 points, and clinical symptoms were improved in 100% of the patients. Follow-up times ranged from 12-62 months (mean follow-up time of 42.3 months and no thrombus re-formation or new neurological deficits occurred during that time. Conclusion: Based on our small study population, balloon dilatation and thrombus extraction appears to be a safe and effective treatment for cerebral venous sinus thrombosis. However, further research is needed to confirm this.

  8. Thrombus entrapped in patent foramen ovale: a rare form of thrombus in transit

    Directory of Open Access Journals (Sweden)

    Hooman Bakhshi


    Full Text Available In rare cases, thrombus in transit can be entrapped in a patent foramen ovale (PFO. A patient with this condition is at high risk of embolic stroke and death. Early diagnosis and treatment is essential to help prevent stroke and death in these cases. There is no universal management guideline for this rare condition. The decision between medical versus surgical treatment should be made individually for each patient. We present a case of thrombus in transit entrapped in a PFO that was treated medically by lifelong anticoagulation.

  9. Detection of extracellular genomic DNA scaffold in human thrombus

    DEFF Research Database (Denmark)

    Oklu, Rahmi; Albadawi, Hassan; Watkins, Michael T


    PURPOSE: Mechanisms underlying transition of a thrombus susceptible to tissue plasminogen activator (TPA) fibrinolysis to one that is resistant is unclear. Demonstration of a new possible thrombus scaffold may open new avenues of research in thrombolysis and may provide mechanistic insight...... thrombi. CONCLUSIONS: Extensive detection of genomic DNA associated with histones in the extracellular matrix of human and mouse thrombi suggest the presence of a new thrombus-associated scaffold....

  10. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb. (United States)

    Walkowiak-Przybyło, M; Klimek, L; Okrój, W; Jakubowski, W; Chwiłka, M; Czajka, A; Walkowiak, B


    Titanium alloys are still on the top list of fundamental materials intended for dental, orthopedics, neurological, and cardiovascular implantations. Recently, a special attention has been paid to vanadium-free titanium alloy, Ti6Al7Nb, that seems to represent higher biocompatibility than traditional Ti6Al4V alloy. Surprisingly, these data are not thoroughly elaborated in the literature; particularly there is a lack of comparative experiments conducted simultaneously and at the same conditions. Our study fills these shortcomings in the field of blood contact and microbiological colonization. To observe platelets adhesion and biofilm formation on the surfaces of compared titanium alloys, fluorescence microscope Olympus GX71 and scanning electron microscope HITACHI S-3000N were used. Additionally, flow cytometry analysis of platelets aggregation and activation in the whole blood after contact with sample surface, as an essential tool for biomaterial thrombocompatibility assessment, was proposed. As a result of our study it was demonstrated that polished surfaces of Ti6Al7Nb and Ti6Al4V alloys after contact with whole citrated blood and E. coli bacterial cells exhibit a considerable difference. Overall, it was established that Ti6Al4V has distinct tendency to higher thrombogenicity, more excessive bacterial biofilm formation and notable cytotoxic properties in comparison to Ti6Al7Nb. However, we suggest these studies should be extended for other types of cells and biological objects.

  11. Balancing Potency of Platelet Inhibition with Bleeding Risk in the Early Treatment of Acute Coronary Syndrome

    Directory of Open Access Journals (Sweden)

    Slattery, David E


    Full Text Available Objective: To review available evidence and examine issues surrounding the use of advanced antiplatelet therapy in an effort to provide a practical guide for emergency physicians caring for patients with acute coronary syndromes (ACS.Data Sources: American College of Cardiology/American Heart Association (ACC/AHA 2007 guidelines for the management of patients with unstable angina (UA and non-ST-segment elevation myocardial infarction (NSTEMI, AHA/ACC 2007 focused update for the management of patients with STEMI, selected clinical articles identified through the PubMed database (1965-February 2008, and manual searches for relevant articles identified from those retrieved.Study Selection: English-language controlled studies and randomized clinical trials that assessed the efficacy and safety of antiplatelet therapy in treating patients with all ACS manifestations.Data Extraction and Synthesis: Clinical data, including treatment regimens and patient demographics and outcomes, were extracted and critically analyzed from the selected studies and clinical trials. Pertinent data from relevant patient registries were also evaluated to assess current clinical practice.Conclusions: As platelet activation and aggregation are central to ACS pathology, antiplatelet agents are critical to early treatment. A widely accepted first-line treatment is aspirin, which acts to decrease platelet activation via inhibition of thromboxane A2 synthesis. Thienopyridines, which inhibit ADP-induced platelet activation, and glycoprotein (GP receptor antagonists, which bind to platelet GP IIb/IIIa receptors and hinder their role in platelet aggregation and thrombus formation, provide complementary mechanisms of platelet inhibition and are often employed in combination with aspirin. While the higher levels of platelet inhibition that accompany combination therapy improve protection against ischemic and peri-procedural events, the risk of bleeding is also increased. Thus, the

  12. Thrombus imaging in acute stroke: correlation of thrombus length on susceptibility-weighted imaging with endovascular reperfusion success

    Energy Technology Data Exchange (ETDEWEB)

    Weisstanner, Christian; Gratz, Pascal P.; Schroth, Gerhard; Verma, Rajeev K.; Koechl, Arnold; Gralla, Jan; Zubler, Christoph; Hsieh, Kety; Mordasini, Pasquale; El-Koussy, Marwan [Bern University Hospital and University of Bern, Department of Diagnostic and Interventional Neuroradiology, Inselspital, Bern (Switzerland); Jung, Simon [Bern University Hospital and University of Bern, Department of Diagnostic and Interventional Neuroradiology, Inselspital, Bern (Switzerland); Bern University Hospital and University of Bern, Department of Neurology, Inselspital, Bern (Switzerland); Arnold, Marcel [Bern University Hospital and University of Bern, Department of Neurology, Inselspital, Bern (Switzerland)


    Susceptibility-weighted imaging (SWI) enables visualization of thrombotic material in acute ischemic stroke. We aimed to validate the accuracy of thrombus depiction on SWI compared to time-of-flight MRA (TOF-MRA), first-pass gadolinium-enhanced MRA (GE-MRA) and digital subtraction angiography (DSA). Furthermore, we analysed the impact of thrombus length on reperfusion success with endovascular therapy. Consecutive patients with acute ischemic stroke due to middle cerebral artery (MCA) occlusions undergoing endovascular recanalization were screened. Only patients with a pretreatment SWI were included. Thrombus visibility and location on SWI were compared to those on TOF-MRA, GE-MRA and DSA. The association between thrombus length on SWI and reperfusion success was studied. Eighty-four of the 88 patients included (95.5 %) showed an MCA thrombus on SWI. Strong correlations between thrombus location on SWI and that on TOF-MRA (Pearson's correlation coefficient 0.918, P < 0.001), GE-MRA (0.887, P < 0.001) and DSA (0.841, P < 0.001) were observed. Successful reperfusion was not significantly related to thrombus length on SWI (P = 0.153; binary logistic regression). In MCA occlusion thrombus location as seen on SWI correlates well with angiographic findings. In contrast to intravenous thrombolysis, thrombus length appears to have no impact on reperfusion success of endovascular therapy. (orig.)

  13. Junín virus infection of human hematopoietic progenitors impairs in vitro proplatelet formation and platelet release via a bystander effect involving type I IFN signaling. (United States)

    Pozner, Roberto G; Ure, Agustín E; Jaquenod de Giusti, Carolina; D'Atri, Lina P; Italiano, Joseph E; Torres, Oscar; Romanowski, Victor; Schattner, Mirta; Gómez, Ricardo M


    Argentine hemorrhagic fever (AHF) is an endemo-epidemic disease caused by Junín virus (JUNV), a member of the arenaviridae family. Although a recently introduced live attenuated vaccine has proven to be effective, AHF remains a potentially lethal infection. Like in other viral hemorrhagic fevers (VHF), AHF patients present with fever and hemorrhagic complications. Although the causes of the bleeding are poorly understood, impaired hemostasis, endothelial cell dysfunction and low platelet counts have been described. Thrombocytopenia is a common feature in VHF syndromes, and it is a major sign for its diagnosis. However, the underlying pathogenic mechanism has not yet been elucidated. We hypothesized that thrombocytopenia results from a viral-triggered alteration of the megakaryo/thrombopoiesis process. Therefore, we evaluated the impact of JUNV on megakaryopoiesis using an in vitro model of human CD34+ cells stimulated with thrombopoietin. Our results showed that CD34+ cells are infected with JUNV in a restricted fashion. Infection was transferrin receptor 1 (TfR1)-dependent and the surface expression of TfR1 was higher in infected cultures, suggesting a novel arenaviral dissemination strategy in hematopoietic progenitor cells. Although proliferation, survival, and commitment in JUNV-infected cultures were normal, viral infection impaired thrombopoiesis by decreasing in vitro proplatelet formation, platelet release, and P-selectin externalization via a bystander effect. The decrease in platelet release was also TfR1-dependent, mimicked by poly(I:C), and type I interferon (IFN alpha/beta) was implicated as a key paracrine mediator. Among the relevant molecules studied, only the transcription factor NF-E2 showed a moderate decrease in expression in megakaryocytes from either infected cultures or after type I IFN treatment. Moreover, type I IFN-treated megakaryocytes presented ultrastructural abnormalities resembling the reported thrombocytopenic NF-E2(-/-) mouse

  14. Measurement and determinants of infrarenal aortic thrombus volume

    Energy Technology Data Exchange (ETDEWEB)

    Golledge, Jonathan; Wolanski, Philippe [James Cook University, The Vascular Biology Unit, Townsville, Queensland (Australia); Townsville Hospital, Townsville, Queensland (Australia); Parr, Adam [James Cook University, The Vascular Biology Unit, Townsville, Queensland (Australia); Buttner, Petra [James Cook University, School of Public Health and Tropical Medicine, Townsville, Queensland (Australia)


    Intra-luminal thrombus has been suggested to play a role in the progression of abdominal aortic aneurysm (AAA). The aims of this study were twofold. Firstly, to assess the reproducibility of a computer tomography (CT)-based technique for measurement of aortic thrombus volume. Secondly, to examine the determinants of infrarenal aortic thrombus volume in a cohort of patients with aortic dilatation. A consecutive series of 75 patients assessed by CT angiography with maximum aortic diameter {>=}25 mm were recruited. Intra-luminal thrombus volume was measured by a semi-automated workstation protocol based on a previously defined technique to quantitate aortic calcification. Intra- and inter-observer reproducibility were assessed using correlation coefficients, coefficient of variation and Bland-Altman plots. Infrarenal aortic thrombus volume percentage was related to clinical, anatomical and blood characteristics of the patients using univariate and multivariate tests. Infrarenal aortic thrombus volume was related to the severity of aortic dilatation assessed by total aortic volume (r=0.87, P<0.0001) or maximum aortic diameter (r=0.74, P< 0.0001). We therefore examined the clinical determinates of aortic thrombus expressed as a percentage of total aortic volume. Aortic thrombus percentage was negatively correlated with serum high density lipoprotein (HDL, r=-0.31). By ordinal multiple logistic regression analysis serum HDL below median ({<=}1.2 mM) was associated with aortic thrombus percentage in the upper quartile adjusting for other risk factors (odds ratio 5.3, 95% CI 1.1-25.0). Infrarenal aortic thrombus volume can be measured reproducibly on CT. Serum HDL, which can be therapeutically raised, may play a role in discouraging aortic thrombus accumulation with implications in terms of delaying progression of AAA. (orig.)

  15. Incidence of thromboembolism following detection by trans-oesophageal echocardiography of left atrial thrombus

    Directory of Open Access Journals (Sweden)

    Ciara Mahon


    Conclusion: This is the only study to date that has looked at the incidence of ischemic stroke following a confirmed LAA thrombus, LA thrombus or pre-thrombus state. This single centre study found low stroke rates over a six month follow-up period in patients with a confirmed LAA thrombus, LA thrombus or pre-thrombus state and optimization of OAC. Larger studies would be required to confirm these findings.

  16. The effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative peritoneal adhesion formation in rats. (United States)

    Makarchian, Hamid Reza; Kasraianfard, Amir; Ghaderzadeh, Pezhman; Javadi, Seyed Mohammad Reza; Ghorbanpoor, Manoochehr


    To assess the effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative adhesion in animal models. Sixty males Albino Wistar rats aged 5 to 6 weeks were classified into five groups receiving none, heparin, PRP, silver nanoparticles, PRP plus silver nanoparticles intraperitoneally. After 2 weeks, the animals underwent laparotomy and the damaged site was assessed for peritoneal adhesions severity. The mean severity scores were 2.5 ± 0.9, 2.16 ± 0.7, 1.5 ± 0.5, 2.66 ± 0.88, and 2.25 ± 0.62 in the control, heparin, PRP, silver and PRP plus silver groups, respectively with significant intergroup difference (p = 0.004). The highest effective material for preventing adhesion formation was PRP followed by heparin and PRP plus silver. Moreover, compared to the controls, only use of PRP was significantly effective, in terms of adhesion severity (p = 0.01) . Platelet-rich plasma alone may have the highest efficacy for preventing postoperative peritoneal adhesions in comparison with heparin, silver nanoparticles and PRP plus silver nanoparticles.

  17. Acquired platelet function defect (United States)

    Acquired qualitative platelet disorders; Acquired disorders of platelet function ... blood clotting. Disorders that can cause problems in platelet function include: Idiopathic thrombocytopenic purpura Chronic myelogenous leukemia Multiple ...

  18. Platelet Donation (United States)

    ... of gratitude that washed over me when I saw those platelets going into my husband’s body. I ... Needles LGBTQ+ Donors Blood Donor Community SleevesUp Games Facebook Avatars and Badges Banners eCards Red Cross Information ...

  19. An Evaluation of the Accuracy of the Subtraction Method Used for Determining Platelet Counts in Advanced Platelet-Rich Fibrin and Concentrated Growth Factor Preparations

    Directory of Open Access Journals (Sweden)

    Taisuke Watanabe


    Full Text Available Platelet concentrates should be quality-assured of purity and identity prior to clinical use. Unlike for the liquid form of platelet-rich plasma, platelet counts cannot be directly determined in solid fibrin clots and are instead calculated by subtracting the counts in other liquid or semi-clotted fractions from those in whole blood samples. Having long suspected the validity of this method, we herein examined the possible loss of platelets in the preparation process. Blood samples collected from healthy male donors were immediately centrifuged for advanced platelet-rich fibrin (A-PRF and concentrated growth factors (CGF according to recommended centrifugal protocols. Blood cells in liquid and semi-clotted fractions were directly counted. Platelets aggregated on clot surfaces were observed by scanning electron microscopy. A higher centrifugal force increased the numbers of platelets and platelet aggregates in the liquid red blood cell fraction and the semi-clotted red thrombus in the presence and absence of the anticoagulant, respectively. Nevertheless, the calculated platelet counts in A-PRF/CGF preparations were much higher than expected, rendering the currently accepted subtraction method inaccurate for determining platelet counts in fibrin clots. To ensure the quality of solid types of platelet concentrates chairside in a timely manner, a simple and accurate platelet-counting method should be developed immediately.

  20. Platelets, inflammation and tissue regeneration. (United States)

    Nurden, Alan T


    Blood platelets have long been recognised to bring about primary haemostasis with deficiencies in platelet production and function manifesting in bleeding while upregulated function favourises arterial thrombosis. Yet increasing evidence indicates that platelets fulfil a much wider role in health and disease. First, they store and release a wide range of biologically active substances including the panoply of growth factors, chemokines and cytokines released from a-granules. Membrane budding gives rise to microparticles (MPs), another active participant within the blood stream. Platelets are essential for the innate immune response and combat infection (viruses, bacteria, micro-organisms). They help maintain and modulate inflammation and are a major source of pro-inflammatory molecules (e.g. P-selectin, tissue factor, CD40L, metalloproteinases). As well as promoting coagulation, they are active in fibrinolysis; wound healing, angiogenesis and bone formation as well as in maternal tissue and foetal vascular remodelling. Activated platelets and MPs intervene in the propagation of major diseases. They are major players in atherosclerosis and related diseases, pathologies of the central nervous system (Alzheimers disease, multiple sclerosis), cancer and tumour growth. They participate in other tissue-related acquired pathologies such as skin diseases and allergy, rheumatoid arthritis, liver disease; while, paradoxically, autologous platelet-rich plasma and platelet releasate are being used as an aid to promote tissue repair and cellular growth. The above mentioned roles of platelets are now discussed.

  1. Takotsubo cardiomyopathy with left ventricular thrombus presenting as critical limb ischaemia (United States)

    Gulsin, Gaurav; Serna, Solange; Morris, Clare; Taher, Abutariq; Loke, Ian


    Takotsubo cardiomyopathy (TC) is a rare condition, characterized by acute left ventricular (LV) dysfunction in the absence of flow-limiting coronary artery disease, usually provoked by a physical or emotional stressor. The condition is far more common in women. The commonest presenting symptoms in patients with TC are chest pain and shortness of breath, often mimicking an acute coronary syndrome. A number of complications of TC are recognized, and very rarely patients experience cardioembolic phenomena secondary to LV thrombus formation in TC. We present the case of a 48-year-old lady presenting with peripheral limb ischaemia, subsequently found to have an LV thrombus secondary to TC. Diagnosis of TC was made challenging by the absence of chest pain. She required urgent arterial embolectomy and was treated with 6-month oral anticoagulation therapy. She was also commenced on beta-blocker and angiotensin-converting enzyme inhibitor treatment for the management of LV dysfunction. PMID:27679725

  2. Scavenger receptor A index and coronary thrombus in patients with acute ST elevation myocardial infarction. (United States)

    Emura, Iwao; Usuda, Hiroyuki; Fujita, Toshio; Ebe, Katsuya; Nagai, Tsuneo


    To examine the relationship between the scavenger receptor A (SRA) index (the number of SRA+ cells observed in 10 high power fields of peripheral blood (PB) smear samples; normal upper limit <30) and coronary thrombus, 389 thrombi obtained from 393 patients with acute ST elevation myocardial infarction were examined. Thrombi were classified into platelets (PT), mixed (MT), fibrin-rich (FT) and organizing thrombi (OT); 387, 269, 57 and 29 cases were detected, respectively. Patients were divided into group A (PT only, 89 cases), B (containing MT and PT but not FT, 243 cases), and C (containing FT, 57 cases). SRA+ cells had infiltrated into all FT cases and 147 of the 269 MT, but no PT. At hospitalization, the SRA index exceeded 30 in 276 patients. PT was observed in 274 cases, and MT and FT (residual mural thrombus; RMT) observed in 230. Infarct-related coronary artery was thought to be totally and rapidly occluded by PT that had formed as a result of severe stenosis due to extrusion of plaque content or growth of RMT. An abnormal increase of SRA+ cells is considered to be a useful finding to detecting the presence of PT and, probably, RMT.

  3. Abundant neutrophil extracellular traps in thrombus of patient with microscopic polyangiitis

    Directory of Open Access Journals (Sweden)

    Daigo eNakazawa


    Full Text Available This is a case study of a patient diagnosed with microscopic polyangiitis (MPA and complicated with deep vein thrombosis (DVT, who died of respiratory failure despite treatment. Autopsy revealed severe crescentic glomerulonephritis and massive alveolar hemorrhage. The thrombus contained abundant neutrophils. Although it is reported that patients with ANCA-associated vasculitis (AAV have an increased risk of DVT, it remains elusive why they are prone to thrombosis. A recent study has demonstrated the presence of neutrophil extracellular traps (NETs, a newly recognized mode of neutrophil cell-death, in glomerular crescents of MPA patients. Interestingly, NETs were identified in the thrombus as well as in the glomerular crescents in the present case. When compared to other thrombi unrelated to MPA, the amount of NETs was significantly greater in the MPA patient. On the other hand, NETs are critically involved in thrombogenesis because histones within NETs can bind platelets and blood coagulants. Although this is important in regard to containment of microbes within NETs, excessive NETs could cause thrombosis. The collective findings suggest the possibility that thrombosis could be critically associated with MPA via NETs, and that NETs could be a therapeutic target in MPA patients.

  4. Platelet rich plasma promotes skeletal muscle cell migration in association with up-regulation of FAK, paxillin, and F-Actin formation. (United States)

    Tsai, Wen-Chung; Yu, Tung-Yang; Lin, Li-Ping; Lin, Mioa-Sui; Tsai, Ting-Ta; Pang, Jong-Hwei S


    Platelet rich plasma (PRP) contains various cytokines and growth factors which may be beneficial to the healing process of injured muscle. The aim of this study was to investigate the effect and molecular mechanism of PRP on migration of skeletal muscle cells. Skeletal muscle cells intrinsic to Sprague-Dawley rats were treated with PRP. The cell migration was evaluated by transwell filter migration assay and electric cell-substrate impedance sensing. The spreading of cells was evaluated microscopically. The formation of filamentous actin (F-actin) cytoskeleton was assessed by immunofluorescence staining. The protein expressions of paxillin and focal adhesion kinase (FAK) were assessed by Western blot analysis. Transfection of paxillin small-interfering RNA (siRNAs) to muscle cells was performed to validate the role of paxillin in PRP-mediated promotion of cell migration. Dose-dependently PRP promotes migration of and spreading and muscle cells. Protein expressions of paxillin and FAK were up-regulated dose-dependently. F-actin formation was also enhanced by PRP treatment. Furthermore, the knockdown of paxillin expression impaired the effect of PRP to promote cell migration. It was concluded that PRP promoting migration of muscle cells is associated with up-regulation of proteins expression of paxillin and FAK as well as increasing F-actin formation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  5. Availability of /sup 111/In-labeled platelet scintigraphy in patients with postinfarction left ventricular aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Tsuda, Takatoshi; Kubota, Masahiro; Iwakubo, Akifumi and others


    Eighteen patients with postinfarction left ventricular aneurysm (LVA) were examined with indium-111-labeled autologous platelet scintigraphy to identify intracardiac thrombi and to investigate the effect of antithrombotic agents on thrombogenesitiy within the LVA. Indium-111-platelet scintigraphy had a sensitivity of 60% and a specificity of 100% in detecting LVA mural thrombi. Among 6 patients showing false-negative scintigraphic studies, 4 was managed on antiplatelet therapy. Of 9 patients showing active platelet deposition on initial study, including 8 not receiving antiplatelet therapy, 5 were treated with tichlopidine (300 mg/day) for 29.8+-5.0 days. For the 5 patients, 2 had resolution and the 3 others had interruption of intraaneurysmal deposition in the second platelet study. For one patient receiving the third platelet study after warfarin therapy, it took two weeks to completely interrupt platelet deposition within the LVA. ECG gated radionuclide ventriculography and thallium-201 myocardial SPECT were also performed to assess left ventricular wall motion of left ventricular ejection fraction (LVEF) and myocardial blood perfusion. Thallium-201 SPECT showed apical or anteroapical perfusion defects. Radionuclide ventriculography pinpointed all 18 apical and anteroseptal aneurysms. A comparison between the thrombus positive group and the thrombus negative group revealed no statistical differences in LVEF and the period from the last myocardial infarction to the initial platelet scanning. These results suggest that indium-111 labeled platelet scintigraphy may be useful for identifying active left ventricular mural thrombi and for judging antiplatelet and anticoagulant therapy. (Namekawa, K).

  6. Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets (United States)

    Palabrica, Theresa; Lobb, Roy; Furie, Barbara C.; Aronovitz, Mark; Benjamin, Christopher; Hsu, Yen-Ming; Sajer, Susan A.; Furie, Bruce


    THE glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes1,2. It is a membrane component of cell storage granules3-6, and is a member of the selectin family which includes E-selectin and L-selectin7,8. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component9-12. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium1,2. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons13. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin14. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.

  7. Platelet function in brown bear (Ursus arctos compared to man

    Directory of Open Access Journals (Sweden)

    Särndahl Eva


    Full Text Available Abstract Background Information on hemostasis and platelet function in brown bear (Ursus arctos is of importance for understanding the physiological, protective changes during hibernation. Objective The study objective was to document platelet activity values in brown bears shortly after leaving the den and compare them to platelet function in healthy humans. Methods Blood was drawn from immobilized wild brown bears 7-10 days after leaving the den in mid April. Blood samples from healthy human adults before and after clopidogrel and acetylsalicylic acid administration served as control. We analyzed blood samples by standard blood testing and platelet aggregation was quantified after stimulation with various agonists using multiple electrode aggregometry within 3 hours of sampling. Results Blood samples were collected from 6 bears (3 females between 1 and 16 years old and from 10 healthy humans. Results of adenosine diphosphate, aspirin, and thrombin receptor activating peptide tests in bears were all half or less of those in humans. Platelet and white blood cell counts did not differ between species but brown bears had more and smaller red blood cells compared with humans. Conclusion Using three different tests, we conclude that platelet function is lower in brown bears compared to humans. Our findings represent the first descriptive study on platelet function in brown bears and may contribute to explain how bears can endure denning without obvious thrombus building. However, the possibility that our findings reflect test-dependent and not true biological variations in platelet reactivity needs further studies.

  8. Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Motte, Louise de la, E-mail: [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen (Denmark); Pedersen, Mads Møller, E-mail: [Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Thomsen, Carsten, E-mail: [Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Vogt, Katja, E-mail: [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Schroeder, Torben V., E-mail: [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Lonn, Lars, E-mail: [Department of Vascular Surgery and Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark)


    Background: Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics of intraluminal thrombus specimens to the appearance on magnetic resonance imaging. Methods: Thirty-four patients undergoing open surgery for abdominal aortic aneurysm had a preoperative MRI obtained with a 1.5 T magnet. Qualitative categorization was performed (blinded and in consensus) and correlated to intraluminal thrombus to muscle signal-intensity ratios. Morphology of intraluminal thrombus specimens collected during surgery were compared to the magnetic resonance imaging categories and specimen weight was correlated to thrombus volume measured on preoperative computer tomography angiography. Results: Blinded MRI categorization resulted in agreement in 22 out of 34 intraluminal thrombi (Kappa value 0.3, p = 0.006). Medians (p = 0.004) and distribution (p = 0.002) of signal-intensity ratios varied significantly across the three MRI categories obtained by consensus. Heterogeneous and homogenous specimen appearance corresponded to similar appearances on MRI in 78% and 55% respectively, resulting in an overall Kappa = 0.4 (p = 0.04). Intraluminal thrombus volume and weight correlated well (r{sub s} 0.831, p < 0.001) with a mean difference of 60 g (95% CI 38–80 g), without proportional bias. Conclusion: Qualitative evaluation of intraluminal thrombus morphology based on MRI can be quantified by measuring signal-intensity ratios. Concurrently a fair agreement to blinded qualitative evaluation of thrombus specimens can be obtained. However, the evaluation is impaired by loss of a large proportion of thrombus during sampling.

  9. Platelets promote bacterial dissemination in a mouse model of streptococcal sepsis. (United States)

    Kahn, Fredrik; Hurley, Sinead; Shannon, Oonagh


    Platelets have been reported to contribute to inflammation and inflammatory disorders. In the present study, we demonstrate that platelets contribute to the acute response to bacterial infection in a mouse model of invasive Streptococcus pyogenes infection. Thrombocytopenia occurred rapidly in infected animals and this was associated with platelet activation, formation of platelet-neutrophil complexes and neutrophil activation. In order to assess the role of platelets during infection, platelets were depleted prior to infection. Platelet-depleted animals had significantly decreased platelet-neutrophil complex formation and neutrophil activation in response to infection. Importantly, significantly fewer bacteria disseminated to the blood, lungs, and spleen of platelet-depleted animals. Platelet-depleted animals did not decrease as significantly in weight as the infected control animals. The results demonstrate a previously unappreciated role for platelets during the pathophysiological response to infection, whereby S. pyogenes bacteria bind to platelets and platelets facilitate bacterial dissemination.

  10. Renal cell carcinoma with vena caval tumor thrombus extending into the right atrium

    Institute of Scientific and Technical Information of China (English)

    JIANG Hai; ZHANG Zhi-gen; CHEN Zhao-dian; SHI Shi-fang; CAI Song-liang; WANG Shuo


    @@ The incidence of the inferior vena cava (IVC)tumor thrombus is reported to be 4%-10% in patients with renal cell carcinoma (RCC). Tumor thrombus may extend through to the right atrium.Management of patients with level Ⅲ/Ⅳ tumor thrombus is usually difficult. We report two cases of level Ⅳ thrombus in our hospital in 2002 and 2004.

  11. Unfractionated and low-molecular-weight heparin and the phosphodiesterase inhibitors, IBMX and cilostazol, block ex vivo Equid Herpesvirus type-1-induced platelet activation

    Directory of Open Access Journals (Sweden)

    Tracy Stokol


    Full Text Available Equid herpes virus type-1 (EHV-1 is a major pathogen of horses, causing abortion storms and outbreaks of herpes virus myeloencephalopathy. These clinical syndromes are partly attributed to ischemic injury from thrombosis in placental and spinal vessels. The mechanism of thrombosis in affected horses is unknown. We have previously shown that EHV-1 activates platelets through virus-associated tissue factor-initiated thrombin generation. Activated platelets participate in thrombus formation by providing a surface to localize coagulation factor complexes that amplify and propagate thrombin generation. We hypothesized that coagulation inhibitors that suppress thrombin generation (heparins or platelet inhibitors that impede post-receptor thrombin signaling (phosphodiesterase [PDE] antagonists would inhibit EHV-1-induced platelet activation ex vivo. We exposed platelet-rich plasma collected from healthy horses to the RacL11 abortigenic and Ab4 neuropathogenic strains of EHV-1 at 1 plaque forming unit/cell in the presence or absence of unfractionated heparin (UFH, low-molecular-weight (LMWH heparin or the PDE inhibitors, 3-isobutyl-1methylxanthine (IBMX and cilostazol. We assessed platelet activation status in flow cytometric assays by measuring P-selectin expression. We found that all of the inhibitors blocked EHV-1- and thrombin-induced platelet activation in a dose-dependent manner. Platelet activation in PRP was maximally inhibited at concentrations of 0.05 U/mL UFH and 2.5 μg/mL LMWH. These concentrations represented 0.1 to 0.2 U/mL anti-Factor Xa activity measured in chromogenic assays. Both IBMX and cilostazol showed maximal inhibition of platelet activation at the highest tested concentration of 50 μM but inhibition was lower than that seen with UFH and LMWH. Our results indicate that heparin anticoagulants and strong non-selective (IBMX or isoenzyme-3 selective (cilostazol PDE antagonists inhibit ex vivo EHV-1-induced platelet activation

  12. A General Aspect of Platelet Rich Plasma

    Directory of Open Access Journals (Sweden)

    Onur ORAL


    Full Text Available The aim of this scientific paper is to introduce Platelet Rich Plasma (PRP cure method by people who never heard about it. People can hurt their selves, thus they can have damaged tissue; for instance broken bone, a scar or a wounded area. Furthe rmore damaged tissue can be a cartilage tissue, which takes very long time to heal. Platelets, those exist in the veins as thrombus, come up to repair those damaged tissues. However, platelets would be insufficient to cure damaged area in a short time. At this point PRP cure method give a hand to the healing process. By centrifuging people’s own blood via special kits, platelets can be separated from blood cells as plasma. That plasma’s platelet density is 3 - 5 times greater than that blood’s platelet densit y. Afterwards PRP method is implemented by injection of plasma to the damaged area or tissue. After implementation of 2 - 4 sessions per week, damaged tissue can be regenerated. It is fast healing method because densified platelet plasma is used; and it is s afe because that plasma is obtained from people’s own blood. PRP can be implemented on many areas; for instance on dentistry, sports medicine, different kind of surgeries such as plastic, vascular or orthopedic and so on. When soccer players brake their le gs, their sports life come to the end, but what if their broken legs was healed better and faster than general healing process? To sum up, PRP is very safe and the future of healing process.

  13. Development of thrombus-resistant and cell compatible crimped polyethylene terephthalate cardiovascular grafts using surface co-immobilized heparin and collagen

    Energy Technology Data Exchange (ETDEWEB)

    Al Meslmani, Bassam, E-mail: [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Mahmoud, Gihan, E-mail: [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Department of Pharmaceutics and Industrial Pharmacy, Helwan University, Ain Helwan, 11795 Cairo (Egypt); Strehlow, Boris, E-mail: [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Mohr, Eva, E-mail: [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Leichtweiß, Thomas, E-mail: [Institute of Physical Chemistry, Justus-Liebig-University, Heinrich-Buff-Ring 58, 35392 Giessen (Germany); Bakowsky, Udo, E-mail: [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany)


    Short-term patency of polyethylene terephthalate (PET) cardiovascular grafts is determined mainly by the inherent thrombogenicity and improper endothelialization following grafts implantation. The aim of the present study was to immobilize heparin to develop thrombus resistant grafts. Additionally, collagen was co-immobilized to enhance the host cell compatibility. The synthetic woven and knitted forms of crimped PET grafts were surface modified by Denier reduction to produce functional carboxyl groups. The produced groups were used as anchor sites for covalent immobilization of heparin or co-immobilization of heparin/collagen by the end-point method. The modified surface was characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The biological activity of immobilized molecules was investigated in vitro using direct blood coagulation test, and “platelet deposition under flow condition. Furthermore, the biocompatibility of modified grafts with host cells was assessed using L929 cell as model. All modified grafts showed significant resistance against fibrin and clot formation. The number of deposited platelets on heparin-immobilized woven and knitted grafts obviously decreased by 3 fold and 2.8 fold per unit surface area respectively, while the heparin/collagen co-immobilized grafts showed only a decrease by 1.7 and 1.8 fold compared to unmodified PET. Heparin-immobilized grafts reported no significant effect on L929 cells adhesion and growth (P > 0.05), conversely, collagen co-immobilization considerably increased cell adhesion almost ∼ 1.3 fold and 2 fold per unit surface area for woven and knitted grafts respectively. Our results emphasize that immobilization of heparin minimized the inherent thrombogenicity of the PET grafts. The simultaneous co-immobilization of collagen supported host cell adhesion and growth required for the grafts biocompatibility. - Highlight: • Heparin and collagen were co-immobilized on

  14. LDL oxidation by platelets propagates platelet activation via an oxidative stress-mediated mechanism. (United States)

    Carnevale, Roberto; Bartimoccia, Simona; Nocella, Cristina; Di Santo, Serena; Loffredo, Lorenzo; Illuminati, Giulio; Lombardi, Elisabetta; Boz, Valentina; Del Ben, Maria; De Marco, Luigi; Pignatelli, Pasquale; Violi, Francesco


    Platelets generate oxidized LDL (ox-LDL) via NOX2-derived oxidative stress. We investigated if once generated by activated platelets ox-LDL can propagate platelet activation. Experiments were performed in platelets from healthy subjects (HS), hyper-cholesterolemic patients and patients with NOX2 hereditary deficiency. Agonist-stimulated platelets from HS added with LDL were associated with a dose-dependent increase of reactive oxidant species and ox-LDL. Agonist-stimulated platelets from HS added with a fixed dose of LDL (57.14 μmol/L) or added with homogenized human atherosclerotic plaque showed enhanced ox-LDL formation (approximately +50% and +30% respectively), which was lowered by a NOX2 inhibitor (approximately -35% and -25% respectively). Compared to HS, ox-LDL production was more pronounced in agonist-stimulated platelet rich plasma (PRP) from hyper-cholesterolemic patients but was almost absent in PRP from NOX2-deficient patients. Platelet aggregation and 8-iso-PGF2α-ΙΙΙ formation increased in LDL-treated washed platelets (+42% and +53% respectively) and PRP (+31% and +53% respectively). Also, LDL enhanced platelet-dependent thrombosis at arterial shear rate (+33%) but did not affect platelet activation in NOX2-deficient patients. Platelet activation by LDL was significantly inhibited by CD36 or LOX1 blocking peptides, two ox-LDL receptor antagonists, or by a NOX2 inhibitor. LDL-added platelets showed increased p38MAPK (+59%) and PKC (+51%) phosphorylation, p47(phox) translocation to platelet membrane (+34%) and NOX2 activation (+30%), which were inhibited by ox-LDL receptor antagonists. Platelets oxidize LDL, which in turn amplify platelet activation via specific ox-LDL receptors; both effects are mediated by NOX2 activation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. Efficacy of platelet-rich plasma gel and hyaluronan hydrogel as carriers of electrically polarized hydroxyapatite microgranules for accelerating bone formation. (United States)

    Ohba, Seiko; Wang, Wei; Itoh, Soichiro; Takagi, Yuzo; Nagai, Akiko; Yamashita, Kimihiro


    The technology for electrical polarization and characterization of hydroxyapatite (HA) microgranules has been developed. This study aimed to examine and compare the efficacy of composites comprising electrically polarized HA (pHA) microgranules and platelet-rich plasma (PRP) or hyaluronan (HAN) in osteoconductivity. Composites of HA microgranules with or without electrical polarization and either PRP or HAN (PRP+pHA, PRP+HA, HAN+pHA, and HAN+HA, respectively), as well as pHA and HA microgranules were implanted randomly into holes created in the medial femoral condyle or tibial tuberosity of rabbits. As a control, PRP or HAN gel alone was implanted, or the bone holes were left empty. Each group included six animals. After 6 weeks, histological examination was performed, and osteoclastic and osteoblastic cell activities were assessed by cell counting. Although PRP alone could not induce bone formation, PRP+pHA and PRP+HA composites, especially the former, activated osteogenic cells and enhanced bone formation. This effect was not prominent in the HAN+pHA and HAN+HA composites. PRP+HA composites formed a gel in which the ceramic particles were dispersed and entrapped in the fibrin network of PRP. It is assumed that these particles provide scaffolds for osteogenic cells, and when electrically polarized, can activate the cells in co-operation with the positive effects of the PRP, resulting in enhanced bone formation. Conversely, it is conceivable that this composite gel cannot act as an accelerator for woven bone formation, because HAN with low viscoelasticity is absorbed rapidly after implantation, the hydrated network containing HA microgranules is destroyed, and the HA microgranules effuse with HAN from the bone hole.

  16. Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

    DEFF Research Database (Denmark)

    de la Motte, Louise; Pedersen, Mads Møller; Thomsen, Carsten


    Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics...

  17. A case of chronic left ventricular thrombus with ischemic cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Vikram Bhausaheb Vikhe


    Full Text Available Left ventricular (LV thrombus is a serious complication of anterior wall myocardial infarction (MI, especially in patients with severe LV dysfunction. LV thrombus carries a high risk of causing stroke and other thromboembolic complications despite adequate anticoagulation therapy. There is a benefit of anticoagulation in patients with ischemic cardiomyopathy to reduce thromboembolic events or in resolution of LV thrombus. Two-dimensional (2D echocardiography is the most commonly used technique for the diagnosis and follow-up of such cases. Our patient developed a chronic LV thrombus with ischemic cardiomyopathy post anterior wall MI and was managed well on anticoagulants to prevent the thromboembolic events under strict vigilance and follow-up.

  18. Right Ventricular Thrombus in a 36-Year-Old Man with Factor V Leiden. (United States)

    Hajsadeghi, Shokoufeh; Naghshin, Roozbeh; Hejrati, Maral; Kerman, Scott Reza Jafarian


    Factor V Leiden deficiency is the most common hereditary hypercoagulable disease in the United States and involves 5% of the Caucasian population. Up to 30% of patients who present with deep vein thrombosis (DVT) or pulmonary thromboembolism present with this condition. This is a case report of a 36-year-old man who experienced one episode of DVT within the previous year and was admitted to our hospital due to productive coughs and hemoptysis. Paraclinical studies demonstrated a right ventricular thrombus. Additional investigation was done to find the underlying cause. Laboratory tests were positive for Factor V Leiden mutation. Other factors for hypercoagulability states were normal. Given that Factor V Leiden mutation is a life-threatening condition with a relatively high prevalence and considering its thrombogenesis, screening tests are necessary in young patients without obvious reasons for recurrent thrombus formation. It seems that medical noninvasive treatments can be an alternative therapy to surgery when a ventricular thrombus is suspected in these patients.

  19. How do the full-generation poly(amido)amine (PAMAM) dendrimers activate blood platelets? Activation of circulating platelets and formation of "fibrinogen aggregates" in the presence of polycations. (United States)

    Watala, Cezary; Karolczak, Kamil; Kassassir, Hassan; Talar, Marcin; Przygodzki, Tomasz; Maczynska, Katarzyna; Labieniec-Watala, Magdalena


    Direct use of poly(amido)amine (PAMAM) dendrimers as drugs may be limited, due to uncertain (cyto)toxicity. Peripheral blood components, which constitute the first line of a contact with administered pharmaceuticals, may become vastly affected by PAMAM dendrimers. The aim of this study was to explore how PAMAMs' polycationicity might affect blood platelet activation and reactivity, and thus trigger various haemostatic events. We monitored blood platelet reactivity in rats with experimental diabetes upon a long-term administration of the unmodified PAMAM dendrimers. In parallel, the effects on blood flow in a systemic circulation was recorded intravitally in mice administered with PAMAM G2, G3 or G4. Compounding was the in vitro approach to monitor the impact of PAMAM dendrimers on blood platelet activation and reactivity and on selected haemostatic and protein conformation parameters. We demonstrated the activating effects of polycations on blood platelets. Some diversity of the revealed outcomes considerably depended on the used approach and the particular technique employed to monitor blood platelet function. We discovered undesirable impact of plain PAMAM dendrimers on primary haemostasis and their prothrombotic influence. We emphasize the need of a more profound verifying of all the promising findings collected for PAMAMs with the use of well-designed in vivo preclinical studies.

  20. Xanthogranulomatous Pyelonephritis in a male child with renal vein thrombus extending into the inferior vena cava: a Case Report

    Directory of Open Access Journals (Sweden)

    Kotasthane Vaishali D


    Full Text Available Abstract Background We present a case of Xanthogranulomatous pyelonephritis (XGPN in a male child with renal vein thrombus extending into the inferior vena cava. This is a rare presentation. XGPN is a rare type of renal infection characterised by granulomatous inflammation with giant cells and foamy histiocytes. The peak incidence is in the sixth to seventh decade with a female predominance. XGPN is rare in children. Case presentation An 11 year old male child presented with a history of high grade fever and chills, right flank pain and progressive pyuria for two months. He had a history of vesical calculus for which he was operated four years back. In our case, a subcapsular right nephrectomy was performed. The surgical specimens were formalin fixed and paraffin embedded. The sections were stained with routine Hematoxylin & Eosin stain. Grossly; the kidney was enlarged with adherent capsule and thickening of the perinephric tissue. The pelvicalyceal system was dilated and was filled with a cast of pus. Histological evaluation revealed diffuse necrosis of the renal parenchyma and perinephric fat. Neutrophils, plasma cells, sheets of foamy macrophages and occasional multinucleate giant cells were seen. The renal vein was partially occluded by an inflammatory thrombus with fibrin, platelets and mixed inflammatory cells. The thrombus was focally adherent to the vein wall with organization. Conclusions The clinical presentation and the macroscopic aspect, together with the histological pattern, the cytological characteristics addressed the diagnosis towards XGPN with a vena caval thrombus. Our case illustrates that the diagnosis of XGPN should be considered even in paediatric age group when renal vein and vena caval thrombi are present.

  1. Iodine-125 metaraminol: A new platelet specific labeling agent

    Energy Technology Data Exchange (ETDEWEB)

    Ohmomo, Y.; Yokoyama, A.; Kawaii, K.; Horiuchi, K.; Saji, H.; Torizuka, K.


    In the search for a platelet specific labeling agent, Metaraminol (MA), which is a sympatomimetic amine used for the treatment of hypotension, cardiogenic shock and well recognized as a drug actively incorporated and accumulated in platelet, attracted the authors' attention. Using the classical chloramine-T iodination method, a high labeling efficiency near 98%, reaching a specific activity up to about 1000 Ci/mmole was obtained. Upon the harvest of platelet, only as platelet rich plasma (PRP), the labeling with this radiopharmaceutical was easily performed by incubation at 37/sup 0/C for 10 min. Labeling efficiency as high as 63.0 +- 3.1% at 24 x 10/sup 8/ cells/ml was obtained. In in-vitro studies, the unaltered state of I-125 MA labeled platelet, with their cellular functions fully retained was demonstrated. Pharmacological study indicated a specific incorporation of I-125 MA by active transport system similar to that of 5-HT, along with passive diffusion. Then the in-vivo study carried out in rabbits with induced thrombi on the femoral artery, showed rather rapid disappearance of the I-125 MA labeled autologous platelet radioactivity, from circulating blood reaching as high thrombus-to-blood activity ratio as 19.8+-4.3 within 30 min post-administration. This new platelet labeling agent, I-125 MA, has many advantages over the use of IN-111 oxine and holds considerable promise for thrombus imaging with single photon emission CT upon the availability of I-123 MA.

  2. Platelet lipidomics: a modern day perspective on lipid discovery and characterization in platelets


    O’Donnell, Valerie B.; Murphy, Robert C.; Watson, Steve P.


    Lipids are diverse families of biomolecules that perform essential structural and signaling roles in platelets. Their formation and metabolism is tightly controlled by enzymes and signal transduction pathways, and their dysregulation leads to significant defects in platelet function and disease. Platelet activation is associated with significant changes to membrane lipids, and formation of diverse bioactive lipids that play essential roles in hemostasis. In recent years, new generation mass s...

  3. Aggregation of Red Blood Cells: From Rouleaux to Clot Formation

    CERN Document Server

    Wagner, C; Svetina, S


    Red blood cells are known to form aggregates in the form of rouleaux. This aggregation process is believed to be reversible, but there is still no full understanding on the binding mechanism. There are at least two competing models, based either on bridging or on depletion. We review recent experimental results on the single cell level and theoretical analyses of the depletion model and of the influence of the cell shape on the binding strength. Another important aggregation mechanism is caused by activation of platelets. This leads to clot formation which is life saving in the case of wound healing but also a major cause of death in the case of a thrombus induced stroke. We review historical and recent results on the participation of red blood cells in clot formation.

  4. Multiple alterations of platelet functions dominated by increased secretion in mice lacking Cdc42 in platelets

    DEFF Research Database (Denmark)

    Pleines, Irina; Eckly, Anita; Elvers, Margitta;


    formation and exocytosis in various cell types, but its exact function in platelets is not established. Here, we show that the megakaryocyte/platelet-specific loss of Cdc42 leads to mild thrombocytopenia and a small increase in platelet size in mice. Unexpectedly, Cdc42-deficient platelets were able to form...... reduced, suggesting increased clearing of the cells under physiologic conditions. These data point to novel multiple functions of Cdc42 in the regulation of platelet activation, granule organization, degranulation, and a specific role in GPIb signaling....

  5. Platelet-rich plasma improves expansion of human mesenchymal stem cells and retains differentiation capacity and in vivo bone formation in calcium phosphate ceramics. (United States)

    Vogel, Julia P; Szalay, Krisztian; Geiger, Florian; Kramer, Martin; Richter, Wiltrud; Kasten, Philip


    Mesenchymal stem cells (MSC) applied to bone substitution materials can improve bone healing. Bone formation in biocomposites is highly dependent on the kind of biomaterial, its pre-treatment and the applied cells. Potentially immunogenic or infectious supplements such as fetal calf serum (FCS) should be avoided in cell expansion media. Therefore, we developed an expansion protocol free of xenogenic supplements. Cells expanded with two different media were tested on distinct biomaterials for their bone formation capacity after ectopic implantation in vivo, as well as for their growth rate and differentiation capacity in vitro. MSC of six donors were expanded with cell expansion medium containing FCS (2%) or platelet-rich plasma (PRP, 3%). Their growth rate and osteogenic, adipogenic and chondrogenic differentiation capacity were compared in vitro. For the in vivo bone formation assay, expanded cells (2 x 105 or 2 x 106) were seeded on calcium-deficient hydroxyapatite (CDHA; n = 12) and on beta-tricalcium phosphate (beta-TCP; n = 12) blocks, which had been coated with either fibronectin or human serum. They were then implanted subcutaneously in severe combined immunodeficient mice (SCID), harvested after 8 weeks and analysed by histology. Bone formation was assessed by a semi-quantitative bone score, after toluidine blue and alizarin red staining. Human cells were detected by an in situ hybridisation for human-specific alu sequences. PRP-supplemented expansion medium yielded two-fold higher cell numbers compared to medium with FCS (P = 0.046) after 3 weeks (four passages) and retained a similar capacity to differentiate towards the osteogenic, chondrogenic and adipogenic lineage. In vivo bone formation was equal for cells expanded with PRP and FCS and depended on the specific surface area of the carrier. CDHA (specific surface area (SSA) 48 m2/g) showed a significantly better bone formation in deep layers (P = 0.005) than beta-TCP (SSA 0.5 m2/g). Fibronectin


    Directory of Open Access Journals (Sweden)

    E. V. Lugovskoi


    Full Text Available It was shown by monoclonal antibodies that B?N-region of fibrin desA molecule (B?1-53 comprises the polymerization site including the peptide bond B?14-15. This site participates in the second stage of fibrin polymerization — lateral association of protofibrils. In the B?15-53 fragment was also found the site called «C», which together with the site «A» participate in the first stage of polymerization — the protofibrils formation. The model of the primary intermolecular interaction of fibrin was designed. It was found by monoclonal antibodies II-4d the site («c» in the N-terminal half of ? chain of the fibrin D-region. This site participates in the protofibrils formation and is complement to site «C» as we assume. We have discovered two neoantigenic determinants. One of these determinants exposes within the coiledcoil fragment B?126-135 of fibrin as a result of fibrinopeptide A splitting off from fibrinogen by thrombin. The structural rearrangements discovered in this site of the fibrin molecule are necessary for the following protofibrils lateral association. The second neoantigenic determinant is localized in the fragment B?134-190 of D-dimer formed after plasmin degradation of fibrin stabilized by FXIIIa. We have obtained the fibrin-specific monoclonal antibodie FnI-3C to the first determinant and D-dimer-specific mAb III-3b to the second one. Three monoclonal antibodies were obtained against the ?C-region of fibrin(ogen molecule. It has been experimentally shown by of one of them that ?C-domains is connected with the fibrinopeptides B in fibrinogen and fibrin desA molecules, but removes from the core of the molecules after fibrinopeptides B splitting off by thrombin. Two other monoclonal antibodies specifically inhibit the fibrin polymerization by blocking two unknown polymerization sites within the ?C-region. The test-systems for the soluble fibrin and D-dimer quantification in human blood plasma were designed on the basis of

  7. Platelet function tests: a comparative review

    Directory of Open Access Journals (Sweden)

    Paniccia R


    Full Text Available Rita Paniccia,1,2 Raffaella Priora,1,2 Agatina Alessandrello Liotta,2 Rosanna Abbate1,2 1Department of Experimental and Clinical Medicine, Thrombosis Center, University of Florence, Florence, Italy; 2Department of Heart and Vessels, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy Abstract: In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation – adhesion, shape change, release reaction, and aggregation – have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]. POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well

  8. Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis. (United States)

    Koupenova, Milka; Vitseva, Olga; MacKay, Christopher R; Beaulieu, Lea M; Benjamin, Emelia J; Mick, Eric; Kurt-Jones, Evelyn A; Ravid, Katya; Freedman, Jane E


    Viral infections have been associated with reduced platelet counts, the biological significance of which has remained elusive. Here, we show that infection with encephalomyocarditis virus (EMCV) rapidly reduces platelet count, and this response is attributed to platelet Toll-like receptor 7 (TLR7). Platelet-TLR7 stimulation mediates formation of large platelet-neutrophil aggregates, both in mouse and human blood. Intriguingly, this process results in internalization of platelet CD41-fragments by neutrophils, as assessed biochemically and visualized by microscopy, with no influence on platelet prothrombotic properties. The mechanism includes TLR7-mediated platelet granule release, translocation of P-selectin to the cell surface, and a consequent increase in platelet-neutrophil adhesion. Viral infection of platelet-depleted mice also led to increased mortality. Transfusion of wild-type, TLR7-expressing platelets into TLR7-deficient mice caused a drop in platelet count and increased survival post EMCV infection. Thus, this study identifies a new link between platelets and their response to single-stranded RNA viruses that involves activation of TLR7. Finally, platelet-TLR7 stimulation is independent of thrombosis and has implications to the host immune response and survival.

  9. Effect of osteogenic periosteal distraction by a modified Hyrax device with and without platelet-rich fibrin on bone formation in a rabbit model: a pilot study. (United States)

    Pripatnanont, P; Balabid, F; Pongpanich, S; Vongvatcharanon, S


    This study evaluated the effect of a modified Hyrax device and platelet-rich fibrin (PRF) on osteogenic periosteal distraction (OPD). Twelve adult male New Zealand white rabbits were separated into two main groups (six in each) according to the duration of the consolidation period (4 or 8 weeks). In each main group, the animals underwent OPD of the left and right sides of the mandible and were divided into four subgroups (three animals per group): device vs. device+PRF, and PRF vs. sham. Radiographic, histological, histomorphometric, and micro-computed tomography (micro-CT) analyses were performed. New bone formation was observed on the lateral and vertical sides of the mandible of all groups. Micro-CT and histomorphometry showed that the device+PRF group presented the highest percentages of bone volume and bone area at 4 weeks (56.67 ± 12.67%, 41.37 ± 7.57%) and at 8 weeks (49.67 ± 8.33%, 55.46 ± 10.67%; significantly higher than the other groups, P<0.001), followed by the device group at 4 weeks (33.00 ± 1.73%, 33.21 ± 11.00%) and at 8 weeks (30.00 ± 3.00%, 23.25 ± 5.46%). In conclusion, the modified Hyrax device was used successfully for OPD in a rabbit model to gain vertical ridge augmentation, and greater bone maturation was achieved with the addition of PRF.

  10. Single-step separation of platelets from whole blood coupled with digital quantification by interfacial platelet cytometry (iPC). (United States)

    Basabe-Desmonts, L; Ramstrom, S; Meade, G; O'Neill, S; Riaz, A; Lee, L P; Ricco, A J; Kenny, D


    IIbβ3) and, relevant to diagnostic applications, platelet adhesion correlates strongly with normal versus abnormal platelet function. A critical function of platelets is to adhere to regions of damage on blood vessel walls; in contrast to conventional flow cytometry, where platelets are suspended in solution, iPC enables physiologically relevant platelet bioassays based on platelet/protein-matrix interactions on surfaces. This technology should be inexpensive to implement in clinical assay format, is readily integrable into fluidic microdevices, and paves the way for high-throughput platelet assays from microliter volumes of whole blood.

  11. Ultrastructural studies of the gray platelet syndrome. (United States)

    White, J G


    The gray platelet syndrome (GPS) is a rare inherited disorder in which peripheral blood platelets are relatively large, vacuolated, and almost devoid of cytoplasmic granulation. In the present study we have evaluated the ultrastructure and cytochemistry of platelets from 2 patients with the GPS to determine precisely which organelles are missing from their cells. The findings indicate that gray platelets contain normal numbers of mitochondria, dense bodies, peroxisomes, and lysosomes but specifically lack alpha-granules. Preliminary studies of megakaryocytes from 1 of the 2 patients suggest that the defect in granule formation may lie at the level of the Golgi zone.

  12. Platelet Function Tests (United States)

    ... be limited. Home Visit Global Sites Search Help? Platelet Function Tests Share this page: Was this page helpful? ... their patients by ordering one or more platelet function tests. Platelet function testing may include one or more of ...

  13. Congenital platelet function defects (United States)

    ... storage pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... Congenital platelet function defects are bleeding disorders that ... function, even though there are normal platelet numbers. Most ...

  14. Expression and clinical significance of platelet activating factor (PAC-1), CD629P and thrombus precursor protein (TpP) in severe sepsis%血小板活化相关因子和血栓前体蛋白在严重脓毒症中的表达

    Institute of Scientific and Technical Information of China (English)

    耿平; 马爱闻; 张劲松; 夏仲芳; 顾健; 徐敏; 徐继扬; 谈定玉; 解松刚; 沈连军


    Objective To investigate the expression and clinical significance of platelet activating factor [PAC]-1, CD62P and TPP hi severe sepsis. Method Patients with severe sepsis who were admitted into the EICU of Subei People's Hospital from April 2007 to March 2008 were included. Patients with severe sepsis (Group Ⅲ)were treated according to the treatment guidelines for severe sepsis, and were divided, according to their clinical records, into those who survived and those who died within 28 days of admission. Patients admitted during the same period with symptoms of infection but without severe sepsis were included as the General Infected Group (Group Ⅱ). A Control Group (Group Ⅰ) comprised patients who visited the hospital over the same period for physical examination or the healthy volunteers. The group members were all included randomly, and the gender and sex of patients in all three groups were similar. Patients with acute brain infarction, acute coronary syndrome,serious diabetes, hyperlipidemia, malignant tumor, leukemia, primary liver, renal and hematopoietic system dis-eases,long-term bedridden patients, pregnant women, and patients taking hormone treatment or hranunosuppres-sants were excluded from the study. Morning venous blood was collected and ELISA and Flow Cytometry performed on the fwst day of admission for Groups Ⅰ- and Ⅱ, and on the first, third and fifth day after admission for Group Ⅲ, to determine the TpP,PAC-1 and CD62P respectively; and the Marshall score was determined. Data were ana-lyzed by SPSS 12.0 software. For continuous variables, comparisons among groups were analyzed by ANOVA.Levene's and LSD test were applied to assess homogeneity. Bivariate test is applied to Correlation Analysis. P0.05); however, Group Ⅲ was significantly different compared with both Group Ⅰ and Group Ⅱ (both:P0.05); on the third day,however, a significant difference appeared with values of (2.89±1.48) % vs. (5.04±2.57) % (P0.05),但Ⅰ组与Ⅲ

  15. Usefulness of contrast computed tomography to detect left ventricular apical thrombus associated with takotsubo cardiomyopathy. (United States)

    Ouchi, Kotaro; Nakamura, Fumitaka; Ikutomi, Masayasu; Oshima, Tsukasa; Ishiwata, Jumpei; Shinohara, Hiroki; Kouzaki, Tsunashi; Amaki, Toshihiro


    Left ventricular (LV) apical thrombus can rarely occur during the early phase of takotsubo cardiomyopathy. We report such a case that was depicted clearly in contrast computed tomography (CT) but not in initial echocardiography. Because LV thrombus may lead to thromboembolic events, we should evaluate all patients with takotsubo cardiomyopathy for the presence of a LV thrombus. LV thrombus is generally recognized with echocardiography in the course of follow-up, but limited depiction of the LV apex with echocardiography can make evaluation of LV thrombus difficult. Contrast CT is useful to detect LV apical thrombus associated with takotsubo cardiomyopathy.

  16. On the formation of narrowly polydispersed PMMA by surface initiated polymerization (SIP) from AIBN-coated/intercalated clay nanoparticle platelets. (United States)

    Fan, Xiaowu; Xia, Chuanjun; Advincula, Rigoberto C


    Various free radical surface initiated polymerization (SIP) conditions were investigated on clay nanoparticles coated with monocationic 2,2'-azobisisobutyronitrile (AIBN) type free radical initiators. Interesting differences in the mechanism of polymer nanocomposite product formation and the role of nanoparticle surface bound AIBN initiators were observed on three types of poly(methyl methacrylate) (PMMA) polymerization conditions: bulk, suspension, and solution. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements confirmed the attachment of the initiator on the clay particles without decomposition of the azo group. XRD and transmission electron microscopy (TEM) showed that a well-dispersed structure was accomplished only by bulk and solution SIP. The suspension SIP product consisted of a partially exfoliated structure as shown by XRD and clay particle aggregate formation as shown by TEM. In general, the molecular weights (MWs) of the surface bound polymers were found to be lower than those of the free polymer. Using the same clay loading and initiator concentrations, we observed that relatively higher MW polymers were obtained from suspension and bulk polymerizations in contrast to solution method. However, the most interesting observation is that the surface bound polymers (on all three conditions) showed much narrower polydispersity compared to that of a typical AIBN type free radical polymerization.

  17. Effect of platelet-derived growth factor-BB on bone formation in calvarial defects: an experimental study in rabbits

    DEFF Research Database (Denmark)

    Vikjaer, D; Blom, S; Hjørting-Hansen, E


    with expanded polytetrafluoroethylene membranes to prevent interference with osteogenesis within the defect by the surrounding tissue and to keep the growth factor in place. A single dose of methylcellulose gel (4.4%) with (n = 8) or without rhPDGF-BB (50 micrograms/ml) (n = 8) was applied to the defects......, and the bone formation was evaluated after 8 weeks. Healing of defects in both groups was characterized by the presence of newly formed bone along the edges of the original defect and by a central area of fibrous connective tissue. The newly formed bone in the rhPDGF-BB treated defects had a trabecular...... of bone marrow was increased 75% in the rhPDGF-BB-treated defect. The porosity of cortical lamella in the newly formed bone was 84% higher in the rhPDGF-BB-treated defects compared to the control. These results show that administration of a single dose of rhPDGF-BB stimulates bone formation in critical...

  18. Glycoprotein Ibα clustering in platelet storage and function

    NARCIS (Netherlands)

    Gitz, E.


    Platelets are anucleated, discoid-shaped cells that play an essential role in the formation of a hemostatic plug to prevent blood loss from injured vessels. Initial platelet arrest at the damaged arterial vessel wall is mediated through the interaction between the platelet receptor glycoprotein (GP)

  19. Glycoprotein Ibα clustering in platelet storage and function

    NARCIS (Netherlands)

    Gitz, E.


    Platelets are anucleated, discoid-shaped cells that play an essential role in the formation of a hemostatic plug to prevent blood loss from injured vessels. Initial platelet arrest at the damaged arterial vessel wall is mediated through the interaction between the platelet receptor glycoprotein (GP)

  20. Behcet’s Disease with Intracardiac Thrombus Presenting with Fever of Unknown Etiology

    Directory of Open Access Journals (Sweden)

    Sajal Ajmani


    Full Text Available A young male was referred to us for evaluation of fever of unknown origin (FUO. He had history of recurrent painful oral ulcers for one year and moderate to high grade fever, pustulopapular rash, and recurrent genital ulcers for 6 months and hemoptysis for 3 days. He was detected to have intracardiac thrombi and pulmonary arterial thrombosis along with underlying Behcet’s disease (BD. Patient responded to high dose prednisolone (1 mg/Kg/day along with monthly parenteral cyclophosphamide therapy. This case highlights the fact that BD is an important cause for pulmonary artery vasculitis with intracardiac thrombus formation, and such patients can present with FUO.

  1. Thrombus Aspirated from Patients with ST-Elevation Myocardial Infarction: Association between 3-Nitrotyrosine and Inflammatory Markers - Insights from ARTERIA Study (United States)

    Dominguez-Rodriguez, Alberto; Abreu-Gonzalez, Pedro; Consuegra-Sanchez, Luciano; Avanzas, Pablo; Sanchez-Grande, Alejandro; Conesa-Zamora, Pablo


    Recent studies have demonstrated that inflammatory cells are a component that plays a role in thrombus formation in ST-elevation myocardial infarction (STEMI). 3-nitrotyrosine (3-NO2-Tyr), a specific marker for protein modification by nitric oxide-derived oxidants, is increased in human atherosclerotic lesions. The purpose of this study was to determine the possible association of inflammatory markers of coronary thrombi with nitroxidative stress. Intracoronary thrombus (n=51) and blood from the systemic circulation were obtained by thromboaspiration in 138 consecutive STEMI patients presenting for primary percutaneous coronary intervention (PCI). Each blood and intracoronary thrombus were measured simultaneously the following biomarkers: C-reactive protein (CRP), 3-NO2-Tyr, soluble CD 40 ligand (sCD40L), vascular cellular adhesion molecule-1 (VCAM-1) and haemoglobin content (only in coronary thrombus). Time delay in minutes from symptom onset to PCI was 244 ± 324. Serum CRP was positively correlated to CRP content in the thrombus (r= 0.395; p = 0.02) and serum sCD40L was negatively correlated to sCD40L in the thrombus (r= -0.394; p = 0.02). Patients were divided into tertiles according to thrombi 3-NO2-Tyr concentration: 1sttertile (0.485ng/mg). Thus, thrombus in the highest tertile had significantly higher levels of CRP (p=0.002), VCAM-1 (p=0.003) and haemoglobin (p=0.002). In conclusion, the present study demonstrated that coronary thrombi with higher levels of 3-NO2-Tyr content often contain more inflammatory markers which could have a direct impact on the efficacy of drugs or devices used for coronary reperfusion. PMID:27429583

  2. Platelet dynamics in three-dimensional simulation of whole blood. (United States)

    Vahidkhah, Koohyar; Diamond, Scott L; Bagchi, Prosenjit


    A high-fidelity computational model using a 3D immersed boundary method is used to study platelet dynamics in whole blood. We focus on the 3D effects of the platelet-red blood cell (RBC) interaction on platelet margination and near-wall dynamics in a shear flow. We find that the RBC distribution in whole blood becomes naturally anisotropic and creates local clusters and cavities. A platelet can enter a cavity and use it as an express lane for a fast margination toward the wall. Once near the wall, the 3D nature of the platelet-RBC interaction results in a significant platelet movement in the transverse (vorticity) direction and leads to anisotropic platelet diffusion within the RBC-depleted zone or cell-free layer (CFL). We find that the anisotropy in platelet motion further leads to the formation of platelet clusters, even in the absence of any platelet-platelet adhesion. The transverse motion, and the size and number of the platelet clusters are observed to increase with decreasing CFL thickness. The 3D nature of the platelet-RBC collision also induces fluctuations in off-shear plane orientation and, hence, a rotational diffusion of the platelets. Although most marginated platelets are observed to tumble just outside the RBC-rich zone, platelets further inside the CFL are observed to flow with an intermittent dynamics that alters between sliding and tumbling, as a result of the off-shear plane rotational diffusion, bringing them even closer to the wall. To our knowledge, these new findings are based on the fundamentally 3D nature of the platelet-RBC interaction, and they underscore the importance of using cellular-scale 3D models of whole blood to understand platelet margination and near-wall platelet dynamics.

  3. Platelet activation determines the severity of thrombocytopenia in dengue infection (United States)

    Ojha, Amrita; Nandi, Dipika; Batra, Harish; Singhal, Rashi; Annarapu, Gowtham K.; Bhattacharyya, Sankar; Seth, Tulika; Dar, Lalit; Medigeshi, Guruprasad R.; Vrati, Sudhanshu; Vikram, Naval K.; Guchhait, Prasenjit


    Thrombocytopenia is common in patients with dengue virus (DENV) infections. With a focus on understanding the possible mechanism of thrombocytopenia in DENV infections we described a direct correlation between activation and depletion of platelets in patients. Our data showed a sharp decrease in platelet counts at day 4 of fever in patients. The high DENV genome copies in platelets correlated directly with the elevated platelet activation along with increased binding of complement factor C3 and IgG on their surface at day 4. Recovery in platelet count was observed on day 10 through day 6 and 8 with simultaneous decrease in platelet activation markers. Further, our in vitro data supported the above observations describing a concentration-dependent increase in platelet activation by DENV serotype-2. The high copy number of DENV2 genome in the platelet pellet correlated directly with platelet activation, microparticle generation and clot formation. Furthermore the DENV2-activated platelets were phagocytosed in large numbers by the monocytes. The DENV2-mediated lysis and clearance of platelets were abrogated in presence of platelet activation inhibitor, prostacyclin. These observations collectively suggest that platelet activation status is an important determinant of thrombocytopenia in dengue infections. A careful strategy of inactivation of platelets may rescue them from rapid destruction during DENV infections. PMID:28139770

  4. Development and Validation of Intracranial Thrombus Segmentation on CT Angiography in Patients with Acute Ischemic Stroke

    NARCIS (Netherlands)

    Santos, E.M.M.; Marquering, H.A.; Berkhemer, O.A.; Van Zwam, W.H.; Van der Lugt, A.; Majoie, C.B.; Niessen, W.J.


    Background and Purpose: Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and time consuming

  5. Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke

    NARCIS (Netherlands)

    Santos, E.M.; Marquering, H.A.; Berkhemer, O.A.; Zwam, W.H. van; Lugt, A. van der; Majoie, C.B.; Niessen, W.J.; Dijk, E.J. van


    BACKGROUND AND PURPOSE: Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and time consuming

  6. Function of eltrombopag-induced platelets compared to platelets from control patients with immune thrombocytopenia. (United States)

    Haselboeck, Johanna; Kaider, Alexandra; Pabinger, Ingrid; Panzer, Simon


    Data on the in vivo function of platelets induced by the thrombopoietin receptor agonist eltrombopag are scarce. To assess a possible influence of eltrombopag we compared platelet function of eltrombopag-treated immune thrombocytopenia (ITP) patients (group 1; n=10) after treatment response to that from control ITP patients (group 2; n=12). We further analysed platelet function at baseline and after one, three, and four weeks of eltrombopag treatment and estimated daily changes of platelet function during the eltrombopag-induced platelet rise. The formation of platelet-monocyte aggregates (PMA), P-selectin expression [MFI], and platelet adhesion under high shear conditions (surface coverage, SC) in vivo and after in vitro addition of agonists (ADP, TRAP-6, Collagen) were similar between both groups after response to eltrombopag treatment. Only TRAP-6 induced a lower SC in the eltrombopag group (p=0.03). All platelet function parameters except for Collagen-induced P-selectin expression changed significantly during treatment with eltrombopag. PMA, naïve and after addition of ADP or TRAP-6 increased with increasing platelet counts. P-selectin expression decreased, when measured without and upon addition of ADP, increased in the presence of TRAP-6, and remained unchanged after addition of Collagen. SC increased during the eltrombopag-induced platelet rise. All significant changes of platelet function correlated to changes in platelet counts. Two patients developed venous thromboses during eltrombopag treatment, but no association with any distinct single platelet function parameter or combinations thereof was identifiable. Thus, eltrombopag-induced platelets function similar to those from control ITP patients without discernible increased hyper-reactivity.

  7. A platelet monoclonal antibody inhibition assay for detection of glycoprotein IIb/IIIa-related platelet alloantibodies. (United States)

    Reiner, A P; Teramura, G; Nelson, K A; Slichter, S J


    Post-transfusion purpura (PTP) and neonatal alloimmune thrombocytopenia (NAT) result from formation of alloantibodies to platelet membrane glycoprotein-associated antigens. The detection and identification of platelet-specific alloantibodies in patient sera is often complicated by the presence of co-existing HLA antibodies and/or more than one platelet specificity in the same serum. We describe a solid phase assay that specifically detects antibodies to platelet membrane associated alloantigens by measuring the ability of patient antisera to inhibit the binding of glycoprotein GPIIb or GPIIIa monoclonal antibodies to intact platelets. When tested in the GPIIIa assay against a panel of random platelet donors, the reactivities of two known PLAI antisera that also contained different HLA antibodies were highly correlated (r = 0.99) and allowed PLA phenotyping of the population. A standard direct binding platelet ELISA, on the other hand, was unable to accurately PLA phenotype the same population. The reactivities of two known Baka antisera (one containing additional anti-PLA2 and the other anti-Brb specificities) were highly correlated (r = 0.95) in the GPIIb assay, and Bak phenotype determination was similarly accomplished for a random platelet panel. Furthermore, a comparison of platelet phenotype results (using the monoclonal inhibition assay) and genotype results (using DNA analysis) for the PLA and Bak systems showed a concordance of 98% for 146 alleles tested. In conclusion, the platelet monoclonal antibody inhibition assay: (1) allows determination of platelet-specific alloantibodies in the presence of contaminating HLA antibodies and/or in sera containing multiple platelet alloantibodies; (2) allows accurate platelet phenotyping for the GPIIIa-associated PLA and GPIIb-associated Bak antigen systems; and (3) may be applicable to the detection of other known or even novel platelet glycoprotein-associated antigens.

  8. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

    NARCIS (Netherlands)

    Santos, E.M.; Yoo, A.J.; Beenen, L.F.; Berkhemer, O.A.; Blanken, M.D. den; Wismans, C.; Niessen, W.J.; Majoie, C.B.; Marquering, H.A.; Dijk, E.J. van


    INTRODUCTION: Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and

  9. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

    NARCIS (Netherlands)

    E.M.M. Santos (Emilie M.); A.J. Yoo (Albert J.); L.F.M. Beenen (Ludo); O.A. Berkhemer (Olvert); M.D. Den Blanken (Mark D.); C. Wismans (Carrie); W.J. Niessen (Wiro); C.B. Majoie (Charles); H. Marquering (Henk)


    textabstractIntroduction: Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by

  10. Long-term survival of patients with hepatocellular carcinoma with inferior vena cava tumor thrombus treated with sorafenib combined with transarterial chemoembolization:report of two cases and literature review

    Institute of Scientific and Technical Information of China (English)

    Heng-Jun Gao; Li Xu; Yao-Jun Zhang; Min-Shan Chen


    The prognosis of hepatocellular carcinoma (HCC) with tumor thrombus formation in the main vasculature is extremely poor. Sorafenib combined with transarterial chemoembolization is a novel treatment approach for advanced HCC. In this study, we report two HCC patients with inferior vena cava tumor thrombus who underwent the combination treatment. The overall survival times for these two patients were 44 months and 35 months, respectively. Our report suggests that sorafenib combined with transarterial chemoembolization may be a viable choice for patients with advanced HCC even with inferior vena cava tumor thrombus. Further studies are required to verify the efficacy and safety of this combination therapy for patients with advanced HCC with inferior vena cava tumor thrombus.

  11. Pneumococcal association to platelets is mediated by soluble fibrin and supported by thrombospondin-1. (United States)

    Niemann, Silke; Kehrel, Beate E; Heilmann, Christine; Rennemeier, Claudia; Peters, Georg; Hammerschmidt, Sven


    Platelets and coagulation are involved in bacterial colonisation of the host. Streptocococcus pneumoniae (pneumococcus) are important etiologic agents of respiratory tract infections in humans. The formation of pneumococci-platelet associations may facilitate haematogenous dissemination of pneumococci by providing an adhesive surface on damaged endothelium. However, the formation of platelet-pneumococci associations and the factors involved in this process have not been described so far. The formation of platelet-pneumococci associates was analysed and quantified using flow cytometry. Binding of pneumococci to platelets was significantly increased after activation of platelets with thrombin, while platelet activation by ADP or collagen did not promote formation of platelet-pneumococci associates. In addition to be a platelet agonist, thrombin cleaves fibrinogen, which results in the generation of fibrin. The simultaneous formation of fibrin and activation of platelets was shown to be a prerequisite for a high number of platelet-pneumococci associates. Moreover, exogenously added human thrombospondin-1 (TSP-1) significantly enhanced the association of pneumococci with activated platelets. Soluble fibrin and TSP-1 are key co-factors of platelet-pneumococci-association. Similar results were recently demonstrated for S. aureus-platelet adhesion. Consequently, we hypothesise that the described mechanism of platelet-bacteria-association might represent a general and important strategy of Gram-positive bacteria during development of invasive diseases.

  12. Platelet matching for alloimmunized patients

    Institute of Scientific and Technical Information of China (English)

    S H.Hsu


    @@ Platelets play an essential role in blood coagulation,hemostasis and maintenance of vascular integrity.Platelets are utilized primarily to prevent or treat bleeding in thrombocytopenic patients and patients with impaired platelet production in the bone marrow and/or with dysfunctional platelets.In current practice,platelet transfusion begins with randomly selected platelet products:either pooled platelets prepared from whole blood derived platelets; or single donor platelets prepared by apheresis procedures.

  13. Roll, adhere, spread and contract: structural mechanics of platelet function. (United States)

    Sorrentino, Simona; Studt, Jan-Dirk; Medalia, Ohad; Tanuj Sapra, K


    Platelets are involved in life-sustaining processes such as hemostasis, wound healing, atherothrombosis and angiogenesis. Mechanical trauma to blood vessels causes platelet activation resulting in their adherence and clot formation at the damaged site, culminating in clot retraction and tissue repair. Two of the major players underlying this process are the cytoskeleton, i.e., actin and microtubules, and the membrane integrin receptors. Rare congenital bleeding disorders such as Glanzmann thrombasthenia and Bernard-Soulier syndrome are associated with genetic alterations of platelet surface receptors, also affecting the platelet cytoskeletal structure. In this review, we summarize the current knowledge about platelet structure and adhesion, and delve into the mechanical aspects of platelet function. Platelets lack a nucleus, and can thus provide a minimal model of a biological cell. New biophysical tools may help to scrutinize platelets anew and to extend the existing knowledge on cell biology.

  14. Unaltered Angiogenesis-Regulating Activities of Platelets in Mild Type 2 Diabetes Mellitus despite a Marked Platelet Hyperreactivity (United States)

    Miao, Xinyan; Zhang, Wei; Huang, Zhangsen


    Type 2 diabetes mellitus (T2DM) is associated with platelet dysfunction and impaired angiogenesis. Aim of the study is to investigate if platelet dysfunction might hamper platelet angiogenic activities in T2DM patients. Sixteen T2DM patients and gender/age-matched non-diabetic controls were studied. Flow cytometry and endothelial colony forming cell (ECFC) tube formation on matrigel were used to assess platelet reactivity and angiogenic activity, respectively. Thrombin receptor PAR1-activating peptide (PAR1-AP) induced higher platelet P-selectin expression, and evoked more rapid and intense platelet annexin V binding in T2DM patients, seen as a more rapid increase of annexin V+ platelets (24.3±6.4% vs 12.6±3.8% in control at 2 min) and a higher elevation (30.9±5.1% vs 24.3±3.0% at 8 min). However, PAR1-AP and PAR4-AP induced similar releases of angiogenic regulators from platelets, and both stimuli evoked platelet release of platelet angiogenic regulators to similar extents in T2DM and control subjects. Thus, PAR1-stimulated platelet releasate (PAR1-PR) and PAR4-PR similarly enhanced capillary-like network/tube formation of ECFCs, and the enhancements did not differ between T2DM and control subjects. Direct supplementation of platelets to ECFCs at the ratio of 1:200 enhanced ECFC tube formation even more markedly, leading to approximately 100% increases of the total branch points of ECFC tube formation, for which the enhancements were also similar between patients and controls. In conclusion, platelets from T2DM subjects are hyperreactive. Platelet activation induced by high doses of PAR1-AP, however, results in similar releases of angiogenic regulators in mild T2DM and control subjects. Platelets from T2DM and control subjects also demonstrate similar enhancements on ECFC angiogenic activities. PMID:27612088

  15. A Predictive Model of High Shear Thrombus Growth. (United States)

    Mehrabadi, Marmar; Casa, Lauren D C; Aidun, Cyrus K; Ku, David N


    The ability to predict the timescale of thrombotic occlusion in stenotic vessels may improve patient risk assessment for thrombotic events. In blood contacting devices, thrombosis predictions can lead to improved designs to minimize thrombotic risks. We have developed and validated a model of high shear thrombosis based on empirical correlations between thrombus growth and shear rate. A mathematical model was developed to predict the growth of thrombus based on the hemodynamic shear rate. The model predicts thrombus deposition based on initial geometric and fluid mechanic conditions, which are updated throughout the simulation to reflect the changing lumen dimensions. The model was validated by comparing predictions against actual thrombus growth in six separate in vitro experiments: stenotic glass capillary tubes (diameter = 345 µm) at three shear rates, the PFA-100(®) system, two microfluidic channel dimensions (heights = 300 and 82 µm), and a stenotic aortic graft (diameter = 5.5 mm). Comparison of the predicted occlusion times to experimental results shows excellent agreement. The model is also applied to a clinical angiography image to illustrate the time course of thrombosis in a stenotic carotid artery after plaque cap rupture. Our model can accurately predict thrombotic occlusion time over a wide range of hemodynamic conditions.

  16. Fibrolamellar hepatocellular carcinoma with biliary tumor thrombus: an unreported association. (United States)

    De Gaetano, Anna Maria; Nure, Erida; Grossi, Ugo; Frongillo, Francesco; Russo, Rosellina; Vecchio, Fabio Maria; Lirosi, Maria Carmen; Sganga, Gabriele; Felice, Carla; Bonomo, Lorenzo; Agnes, Salvatore


    Fibrolamellar hepatocellular carcinoma (FHCC) is a rare malignant tumor of hepatocyte origin occurring earlier in life than typical hepatocellular carcinoma (HCC). We describe a distinctive case of FHCC with biliary tumor thrombus (BTT) in a 25-year-old Caucasian patient, pointing out the imaging features supported by histopathology.

  17. Anatomic Characteristics and Clinical Implications of Angiographic Coronary Thrombus

    NARCIS (Netherlands)

    C.A.M. Campos (Carlos); F. Costa (Francesco); H.M. Garcia-Garcia (Hector); C.V. Bourantas (Christos); P. Suwannasom (Pannipa); M. Valgimigli (Marco); M-A.M. Morel (Marie-Angèle); S. Windecker (Stephan); P.W.J.C. Serruys (Patrick)


    textabstractBackground - The distribution of thrombus-containing lesions (TCLs) in an all-comer population admitted with a heterogeneous clinical presentation (stable, ustable angina, or an acute coronary syndrome) and treated with percutaneous coronary intervention is yet unclear, and the long-term

  18. Platelet satellitism in infectious disease? (United States)

    Laskaj, Renata; Sikiric, Dubravka; Skerk, Visnja


    Background Platelet satellitism is a phenomenon of unknown etiology of aggregating platelets around polymorphonuclear neutrophils and other blood cells which causes pseudothrombocytopenia, visible by microscopic examination of blood smears. It has been observed so far in about a hundred cases in the world. Case subject and methods Our case involves a 73-year-old female patient with a urinary infection. Biochemical serum analysis (CRP, glucose, AST, ALT, ALP, GGT, bilirubin, sodium, potassium, chloride, urea, creatinine) and blood cell count were performed with standard methods on autoanalyzers. Serum protein fractions were examined by electrophoresis and urinalysis with standard methods on autoanalyzer together with microscopic examination of urine sediment. Erythrocyte sedimentation rate, blood culture and urine culture tests were performed with standard methods. Results Due to typical pathological values for bacterial urinary infection, the patient was admitted to the hospital. Blood smear examination revealed phenomenon, which has persisted for three weeks after the disease has been cured. Blood smears with EDTA as an anticoagulant had platelet satellitism whereas the phenomenon was not observed in tubes with different anticoagulants (Na, Li-heparin) and capillary blood. Discussion We hypothesize that satellitism was induced by some immunological mechanism through formation of antibodies which have mediated platelets binding to neutrophil membranes and vice versa. Unfortunately we were unable to determine the putative trigger for this phenomenon. To our knowledge this is the second case of platelet satellitism ever described in Croatia. PMID:26110042

  19. Left atrial appendage thrombus with resulting stroke post-RF ablation for atrial fibrillation in a patient on dabigatran.

    LENUS (Irish Health Repository)

    Lobo, R


    Dabigatran etexilate is licensed for use in prevention of deep venous thromboembolism and in prevention of stroke and systemic embolism in nonvalvular atrial fibrillation (AF). It has also been used in patients for other indications as a substitute for warfarin therapy because it requires no monitoring; one group being patients undergoing radiofrequency (RF), ablation for AF, although there have been no consensus guidelines with regards to dosage and timing of dose. We report the case of a patient with documentary evidence of left atrial appendage (LAA) thrombus formation and neurological sequelae post-RF ablation despite being on dabigatran. This case highlights the concern that periprocedural dabigatran may not provide adequate protection from development of LAA thrombus and that a standardised protocol will need to be developed and undergo large multicentre trials before dabigatran can be safely used for patients undergoing RF-ablation.

  20. Space maintenance in autogenous fresh demineralized tooth blocks with platelet-rich plasma for maxillary sinus bone formation: a prospective study. (United States)

    Kim, Eun-Suk; Kang, Ji-Yeon; Kim, Jae-Jin; Kim, Kyoung-Won; Lee, Eun-Young


    This prospective study evaluated the effectiveness of autogenous fresh demineralized tooth block (Auto-FDT block) with platelet-rich plasma (PRP) for maxillary sinus augmentation with simultaneous implant installation. Auto-FDT block with PRP was used in Group 1 (n = 15) and combined graft (allograft and xenograft) powder with PRP was used in Group 2 (n = 15). For up to 2 years after the final prosthesis was installed, clinical and radiographic examinations were performed to evaluate the amount of graft materials, residual alveolar height (RAH), sinus height (SH) after grafting, augmented graft height (AGH) and resorption height (RH). In ten cases, biopsies were harvested for histological and histomorphometric analyses. A total of 59 implants were placed in a severe atrophic posterior maxilla with less than 5 mm of RAH and sinus augmentation. None of the patients developed sinusitis or other complications, such as implant loss. The graft material extracted included one molar (or 2 premolars) in Group 1 and 1.8 cc in Group 2. The radiologic examination revealed the following average between-group difference SH (Group 1, 14.12 ± 1.63 mm vs Group 2, 16.51 ± 1.29 mm) and AGH (Group 1, 11.62 ± 2.22 mm vs Group 2, 13.65 ± 1.35 mm). However, sufficient SH and AGH were observed for the implants in the Auto-FDT block group. Two years after final prosthesis was installed, no between-group difference in the RH was observed (Group 1, 1.23 ± 0.73 mm vs Group 2, 1.77 ± 0.54 mm, P = 0.021). The histomorphometric analysis revealed no between-group difference in the new bone volume (Group 1, 23.13 ± 1.42 % vs Group 2, 24.18 ± 2.19 %, P = 0.548). The results showed that Auto-FDT block with PRP can be used in grafted sinuses for implants with only one extracted molar (or two premolars). Auto-FDT block with PRP promotes new bone formation that is comparable with combined grafts. Auto-FDT block with PRP is as an alternative to bone grafting

  1. Case-control study of platelet glycoprotein receptor Ib and IIb/IIIa expression in patients with acute and chronic cerebrovascular disease.

    Directory of Open Access Journals (Sweden)

    Peter Kraft

    Full Text Available Animal models have been instrumental in defining thrombus formation, including the role of platelet surface glycoprotein (GP receptors, in acute ischemic stroke (AIS. However, the involvement of GP receptors in human ischemic stroke pathophysiology and their utility as biomarkers for ischemic stroke risk and severity requires elucidation.To determine whether platelet GPIb and GPIIb/IIIa receptors are differentially expressed in patients with AIS and chronic cerebrovascular disease (CCD compared with healthy volunteers (HV and to identify predictors of GPIb and GPIIb/IIIa expression.This was a case-control study of 116 patients with AIS or transient ischemic attack (TIA, 117 patients with CCD, and 104 HV who were enrolled at our University hospital from 2010 to 2013. Blood sampling was performed once in the CCD and HV groups, and at several time points in patients with AIS or TIA. Linear regression and analysis of variance were used to analyze correlations between platelet GPIb and GPIIb/IIIa receptor numbers and demographic and clinical parameters.GPIb and GPIIb/IIIa receptor numbers did not significantly differ between the AIS, CCD, and HV groups. GPIb receptor expression level correlated significantly with the magnitude of GPIIb/IIIa receptor expression and the neutrophil count. In contrast, GPIIb/IIIa receptor numbers were not associated with peripheral immune-cell sub-population counts. C-reactive protein was an independent predictor of GPIIb/IIIa (not GPIb receptor numbers.Platelet GPIb and GPIIb/IIIa receptor numbers did not distinguish between patient or control groups in this study, negating their potential use as a biomarker for predicting stroke risk.

  2. Erythrocyte-platelet interaction in uncomplicated pregnancy. (United States)

    Swanepoel, Albe C; Pretorius, Etheresia


    Maternal and fetal requirements during uncomplicated pregnancy are associated with changes in the hematopoietic system. Platelets and erythrocytes [red blood cells (RBCs)], and especially their membranes, are involved in coagulation, and their interactions may provide reasons for the changed hematopoietic system during uncomplicated pregnancy. We review literature regarding RBC and platelet membrane structure and interactions during hypercoagulability and hormonal changes. We then study interactions between RBCs and platelets in uncomplicated pregnancy, as their interactions may be one of the reasons for increased hypercoagulability during uncomplicated pregnancy. Scanning electron microscopy was used to study whole blood smears from 90 pregnant females in different phases of pregnancy. Pregnancy-specific interaction was seen between RBCs and platelets. Typically, one or more platelets interacted through platelet spreading and pseudopodia formation with a single RBC. However, multiple interactions with RBCs were also shown for a single platelet. Specific RBC-platelet interaction seen during uncomplicated pregnancy may be caused by increased estrogen and/or increased fibrinogen concentrations. This interaction may contribute to the hypercoagulable state associated with healthy and uncomplicated pregnancy and may also play a fundamental role in gestational thrombocytopenia.

  3. Incidence and management of inferior vena cava filter thrombus detected at time of filter retrieval. (United States)

    Teo, Terence K B; Angle, John F; Shipp, John I; Bluett, Michael K; Gilliland, Charles A; Turba, Ulku C; Matsumoto, Alan H


    To evaluate inferior vena cava (IVC) venograms (ie, cavograms) before filter retrieval to determine the incidence and volume of filter thrombus relative to filter dwell time and evaluate subsequent changes in thrombus volume with additional anticoagulation. IVC filter retrieval attempts between December 2002 and June 2010 were retrospectively reviewed to determine the incidence of filter thrombus and estimate thrombus volume on a preretrieval cavogram. Correlation between filter dwell times (assessed at 30-d intervals) and incidence and volume of thrombus was assessed. Follow-up images and management of filters with thrombus that were not initially removed were analyzed. A total of 463 retrieval attempts were performed in 440 patients, with a mean filter dwell time of 95 days ± 145 (SD; range, 0-1,762 d). Thirty (6.5%) had filter thrombus on initial cavograms, with a mean thrombus volume of 2.8 cm(3) ± 7.3 (range, 0.04-40.02 cm(3)). Incidence rate and estimated thrombus volume were highest in the 0-30-day dwell interval (8.0% and 6.3 cm(3), respectively) and decreased at subsequent time intervals. On linear regression analysis, incidence of filter thrombus was inversely related to dwell time (P mean of 48 days ± 25 (range, 14-90 d); thrombus resolved completely in five (71%) and partially in one (14%), and increased in one (14%). The incidence of filter thrombus at the time of filter retrieval appears to decrease with dwell time. If thrombus is detected, an additional period of anticoagulation is likely to reduce the thrombus burden and facilitate later retrieval. Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.

  4. [Changes in platelet function in children with acute or chronic tonsillitis]. (United States)

    Kirichuk, V F; Mareev, O V; Diudina, O Iu


    Children with a compensated or uncompensated form of acute or chronic tonsillitis demonstrate high platelet aggregation resultant in faster formation of platelet aggregates, an increased maximum size of these aggregates, faster achievement of the maximum platelet aggregation. Local drug therapy, combined drug + ultrasound and laser therapy failed to normalize platelet aggregation. The best effect on platelet aggregation was obtained in combined treatment with ultrasound and laser.

  5. Real-Time Observation of Thrombus Growth Process in an Impeller of a Hydrodynamically Levitated Centrifugal Blood Pump by Near-Infrared Hyperspectral Imaging. (United States)

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Fujiwara, Tatsuki; Nishida, Masahiro; Maruyama, Osamu


    Understanding the thrombus formation in cardiovascular devices such as rotary blood pumps is the most important issue in developing more hemocompatible devices. The objective of this study was to develop a hyperspectral imaging (HSI) method to visualize the thrombus growth process within a rotary blood pump and investigate the optical properties of the thrombus. An in vitro thrombogenic test was conducted using fresh porcine blood and a specially designed hydrodynamically levitated centrifugal blood pump with a transparent bottom. The pump rotating at 3000 rpm circulated the blood at 1.0 L/min. The bottom surface of the pump was illuminated with white light pulsed at the same frequency as the pump rotation, and the backward-scattered light was imaged using the HSI system. Using stroboscopic HSI and an image construction algorithm, dynamic spectral imaging at wavelengths ranging from 608 to 752 nm within the rotating pump was achieved. After completing the experiment, we collected the red thrombus formed in the pump impeller and quantified the thrombus hemoglobin concentration (Hbthrombus ). The spectrum changed around the center of the impeller, and the area of change expanded toward the impeller flow path. The shape corresponded approximately to the shape of the thrombus. The spectrum change indicated that the light scattering derived from red blood cells decreased. The Hbthrombus was 4.7 ± 1.3 g/dL versus a total hemoglobin of 13 ± 0.87 g/dL. The study revealed that Hbthrombus was reduced by the surrounding blood flow.

  6. Small-size platelet microparticles trigger platelet and monocyte functionality and modulate thrombogenesis via P-selectin. (United States)

    Montoro-García, Silvia; Shantsila, Eduard; Hernández-Romero, Diana; Jover, Eva; Valdés, Mariano; Marín, Francisco; Lip, Gregory Y H


    This study aimed to examine the mechanisms of cellular activation by small-size platelet microparticles (sPMP) and to present the performance of high-resolution flow cytometry for the analysis of subcellular entities from different origins. Plasma counts of sPMP were analysed in coronary artery disease patients (n = 40) and healthy controls (n = 40). The effect of sPMP and platelet debris (PD) in pathophysiologically relevant doses on platelet and monocyte activation parameters and thrombogenesis was investigated via flow cytometry and thromboelastometry. New generation flow cytometry identifies differences in size, levels and surface molecules of sPMP derived in the absence of stimulus, thrombin activation and platelet disruption. Addition of sPMP resulted in platelet degranulation and P-selectin redistribution to the membrane (P = 0·019) in a dose and time-dependent manner. Blood clotting time decreased after addition of sPMP (P = 0·005), but was not affected by PD. Blocking P-selectin (CD62P) in sPMP markedly reverted the effect on thrombus kinetics (P = 0·035). Exposure to sPMP stimulated monocyte expression of intercellular adhesion molecule-1 (P P-selectin expression.

  7. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical Univ. Lubeck, Lubeck (DE))


    This book presents papers on the clinical applications of radiolabelled platelets. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection.

  8. Platelets Express Activated P2Y12 Receptor in Patients With Diabetes Mellitus. (United States)

    Hu, Liang; Chang, Lin; Zhang, Yan; Zhai, Lili; Zhang, Shenghui; Qi, Zhiyong; Yan, Hongmei; Yan, Yan; Luo, Xinping; Zhang, Si; Wang, Yiping; Kunapuli, Satya P; Ye, Hongying; Ding, Zhongren


    Platelets from patients with diabetes mellitus are hyperactive. Hyperactivated platelets may contribute to cardiovascular complications and inadequate responses to antiplatelet agents in the setting of diabetes mellitus. However, the underlying mechanism of hyperactivated platelets is not completely understood. We measured P2Y12 expression on platelets from patients with type 2 diabetes mellitus and on platelets from rats with diabetes mellitus. We also assayed platelet P2Y12 activation by measuring cAMP and VASP phosphorylation. The antiplatelet and antithrombotic effects of AR-C78511 and cangrelor were compared in rats. Finally, we explored the role of the nuclear factor-κB pathway in regulating P2Y12 receptor expression in megakaryocytes. Platelet P2Y12 levels are 4-fold higher in patients with type 2 diabetes mellitus compared with healthy subjects. P2Y12 expression correlates with ADP-induced platelet aggregation (r=0.89, Pdiabetes mellitus is constitutively activated. Although both AR-C78511, a potent P2Y12 inverse agonist, and cangrelor have similar antiplatelet efficacy on platelets from healthy subjects, AR-C78511 exhibits more powerful antiplatelet effects on diabetic platelets than cangrelor (aggregation ratio 36±3% versus 49±5%, respectively, Pdiabetes mellitus than cangrelor (thrombus weight 4.9±0.3 mg versus 8.3±0.4 mg, respectively, Pdiabetes mellitus. Platelet P2Y12 receptor expression is significantly increased and the receptor is constitutively activated in patients with type 2 diabetes mellitus, which contributes to platelet hyperactivity and limits antiplatelet drug efficacy in type 2 diabetes mellitus. © 2017 American Heart Association, Inc.

  9. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets. (United States)

    Lee, Ye-Ming; Hsieh, Kuo-Hsien; Lu, Wan-Jung; Chou, Hsiu-Chu; Chou, Duen-Suey; Lien, Li-Ming; Sheu, Joen-Rong; Lin, Kuan-Hung


    Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.). Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca(2+)](i) mobilization, thromboxane A(2) formation, hydroxyl radical (OH(●)) formation, and phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinase (MAPK), and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A(2) formation, thereby leading to inhibition of [Ca(2+)](i) and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  10. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus, Prevents Platelet Activation in Human Platelets

    Directory of Open Access Journals (Sweden)

    Ye-Ming Lee


    Full Text Available Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.. Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca2+]i mobilization, thromboxane A2 formation, hydroxyl radical (OH● formation, and phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinase (MAPK, and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A2 formation, thereby leading to inhibition of [Ca2+]i and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  11. Evaluation of the thrombus of abdominal aortic aneurysms using contrast enhanced ultrasound - preliminary results (United States)

    Łukasiewicz, Adam; Garkowski, Adam; Rutka, Katarzyna; Janica, Jacek; Łebkowska, Urszula


    It is hypothesized that the degree of vascularization of the thrombus may have a significant impact on the rupture of aortic aneurysms. The presence of neovascularization of the vessel wall and mural thrombus has been confirmed only in histopathological studies. However, no non-invasive imaging technique of qualitative assessment of thrombus and neovascularization has been implemented so far. Contrast-enhanced ultrasound (CEUS) has been proposed as a feasible and minimally invasive technique for in vivo visualization of neovascularization in the evaluation of tumors and atherosclerotic plaques. The aim of this study was the evaluation of mural thrombus and AAAs wall with CEUS. CEUS was performed in a group of seventeen patients with AAAs. The mural thrombus enhancement was recognized in 12 cases, yet no significant correlation between the degree of contrast enhancement and AAAs diameter, thrombus width, and thrombus echogenicity was found. We observed a rise in AAAs thrombus heterogeneity with the increase in the aneurysm diameter (r = 0.62, p = 0.017). In conclusion CEUS can visualize small channels within AAAs thrombus, which could be a result of an ongoing angiogenesis. There is a need for further research to find out whether the degree of vascularization of the thrombus may have a significant impact on the rupture of aneurysms.

  12. Thrombus Volume Change Visualization after Endovascular Abdominal Aortic Aneurysm Repair (United States)

    Maiora, Josu; García, Guillermo; Macía, Iván; Legarreta, Jon Haitz; Boto, Fernando; Paloc, Céline; Graña, Manuel; Abuín, Javier Sanchez

    A surgical technique currently used in the treatment of Abdominal Aortic Aneurysms (AAA) is the Endovascular Aneurysm Repair (EVAR). This minimally invasive procedure involves inserting a prosthesis in the aortic vessel that excludes the aneurysm from the bloodstream. The stent, once in place acts as a false lumen for the blood current to travel down, and not into the surrounding aneurysm sac. This procedure, therefore, immediately takes the pressure off the aneurysm, which thromboses itself after some time. Nevertheless, in a long term perspective, different complications such as prosthesis displacement or bloodstream leaks into or from the aneurysmatic bulge (endoleaks) could appear causing a pressure elevation and, as a result, increasing the danger of rupture. The purpose of this work is to explore the application of image registration techniques to the visual detection of changes in the thrombus in order to assess the evolution of the aneurysm. Prior to registration, both the lumen and the thrombus are segmented

  13. Bone Formation with Deproteinized Bovine Bone Mineral or Biphasic Calcium Phosphate in the Presence of Autologous Platelet Lysate: Comparative Investigation in Rabbit

    Directory of Open Access Journals (Sweden)

    Carole Chakar


    Full Text Available Bone substitutes alone or supplemented with platelet-derived concentrates are widely used to promote bone regeneration but their potency remains controversial. The aim of this study was, therefore, to compare the regenerative potential of preparations containing autologous platelet lysate (APL and particles of either deproteinized bovine bone mineral (DBBM or biphasic calcium phosphate (BCP, two bone substitutes with different resorption patterns. Rabbit APL was prepared by freeze-thawing a platelet suspension. Critical-size defects in rabbit femoral condyle were filled with DBBM or DBBM+APL and BCP or BCP+APL. Rabbits were sacrificed after six weeks and newly formed bone and residual implanted material were evaluated using nondemineralized histology and histomorphometry. New bone was observed around particles of all fillers tested. In the defects filled with BCP, the newly formed bone area was greater (70%; P<0.001 while the residual material area was lower (60%; P<0.001 than that observed in those filled with DBBM. New bone and residual material area of defects filled with either APL+DBBM or APL+BCP were similar to those observed in those filled with the material alone. In summary, osteoconductivity and resorption of BCP were greater than those of DBBM, while APL associated with either DBBM or BCP did not have an additional benefit.

  14. A big floating thrombus in the common carotid artery. (United States)

    La Spada, Michele; Stilo, Francesco; Barillà, David; Spinelli, Francesco


    The management of the free-floating thrombus (FFT) is difficult, and it is unclear whether surgical or medical treatment is superior. The common carotid artery is rarely involved. An 80-year-old woman presented with right hand weakness and syncope. Ultrasound showed the presence of FFT in the left common carotid artery. A carotid endarterectomy with Dacron patch angioplasty was immediately performed without complications. In the presence of symptoms, the interventional management of FFT is advised.

  15. Gallbladder cancer with tumor thrombus in the superior vena cava

    Institute of Scientific and Technical Information of China (English)

    Sandeep Batra; Dinesh Chandra Doval; Ullas Batra; Pandalanghat Suresh; Amit Dhiman; Vineet Talwar


    BACKGROUND: Gastrointestinal cancers, especially pancreato-biliary cancers, are frequently associated with or are complicated by thromboembolic phenomena due to hypercoagulability and/or altered venous drainage, especially of the abdomen and lower limbs. This report describes an unusual and interesting case of gallbladder carcinoma developing a viable tumor thrombus in the superior vena cava (SVC) with resultant SVC obstruction, while on geiftinib-based anti-epidermal growth factor receptor (EGFR) therapy. METHODS: A 60-year-old woman was incidentally diagnosed to have gallbladder cancer on cholecystectomy. She had disease recurrence and received systemic chemotherapy followed by geiftinib-based anti-EGFR therapy. Subsequently, while on geiftinib-based therapy, she presented with clinical signs and symptoms suggestive of SVC thrombosis. RESULTS: A whole body PET scan revealed a metabolically active tumor thrombus in the SVC, besides other sites of metabolically active disease inclusive of the lung parenchyma, lymph nodes and abdomen. She was treated with anti-thrombotics and external beam radiotherapy directed to the SVC thrombus leading to symptomatic relief. She continues to survive on the day of writing this report. CONCLUSIONS: This rare complication, though theoretically possible, is unreported because of the short overall survival of advanced gallbladder cancer patients. This highlights that with the availability of better chemotherapeutic/biotherapeutic agents for increasing in the lifespan of cancer patients, we may come across such cases more frequently in the future.

  16. Indium-111 platelet scintigraphy in carotid disease

    Energy Technology Data Exchange (ETDEWEB)

    Branchereau, A.; Bernard, P.J.; Ciosi, G.; Bazan, M.; de Laforte, C.; Elias, A.; Bouvier, J.L.


    Forty-five patients (35 men, 10 women) undergoing carotid surgery had Indium-111 platelet scintigraphy as part of their preoperative work-up. Imaging was performed within three hours after injection of the Indium-111. A second series of views was obtained 24 hours later and repeated at 24 hour intervals for two days. Of 54 scintigrams, 22 were positive and 32 negative. Positive results were defined as a twofold or more increase in local activity on a visualized carotid after 24 hours. The sensitivity of the method was 41%, intraoperatively, and the specificity, 100%. The low sensitivity places this method behind sonography and duplex-scanning for screening patients for surgery. We believe that indications for platelet scintigraphy are limited to: 1. Repeated transient ischemic attacks in the same territory with minimal lesions on arteriography and non-homogeneous plaque on duplex scan; 2. Symptomatic patients being treated medically as a possible argument for surgery; 3. Determining therapeutic policy for patients having experienced a transient ischemic attack with a coexisting intracardiac thrombus.

  17. Quantifying platelet gel coagulation using Sonoclot and Thrombelastograph hemostasis analyzer. (United States)

    Cassidy, Lynsay K; Finney, Angela S; Ellis, William Cory; Spiwak, Allison J; Riley, Jeffrey B


    Little in vitro research exists discussing platelet gel composition and the resulting strength and degradation characteristics using point-of-care technologies. There must be a quantifiable way of determining the structural integrity of the resulting formed platelet gel thrombus. The Thrombelastograph Hemostasis Analyzer (TEG) and Sonoclot measure the elasticity of a clot as it forms and subsequently degrades naturally. The objective of this study was to determine the application of TEG and Sonoclot technologies as point-of-care devices for technicians using platelet gel therapy. The collected bovine blood was anticoagulated with CPD and processed using a previously published plasma sequestration protocol, using normal saline as a wash solution. The resulting platelet-rich plasma was stored in a sequestration bag in a water bath to maintain the blood temperature at 37 degrees C. Sequestered bovine platelet-rich plasma was made into platelet gel using three different thrombin concentrations. A total of 30 experiments were performed on the platelet gel product using both the TEG and the Sonoclot. We discovered that 6 of the Sonoclot tests and 15 of the TEG tests were valid. None of the TEG clot signatures and nine of the Sonoclot signatures were discovered to be invalid. A chi2 test was performed on the resultant data. The value of the chi2 test was calculated to be 12.86, which translated into a p value of less than 0.001. Despite the vast use and growing popularity of platelet gels, a method in which to quantify platelet gels has yet to be reported. There remains a possibility that gels formed with different concentrations of components may prove useful in different areas of surgery or their uses may expand to a broader spectrum of medicine. However, technology to quantify platelet gels must first be standardized. On the basis of the data collected in this study, it was determined that the TEG and the Sonoclot are not equally capable of analyzing platelet gel clots

  18. The thermodynamics and kinetics of phosphoester bond formation, use, and dissociation in biology, with the example of polyphosphate in platelet activation, trasience, and mineralization. (United States)

    Omelon, S. J.


    Mitochondria condense orthophosphates (Pi), forming phosphoester bonds for ATP production that is important to life. This represents an exchange of energy from dissociated carbohydrate bonds to phosophoester bonds. These bonds are available to phosphorylate organic compounds or hydrolyze to Pi, driving many biochemical processes. The benthic bacteria T. namibiensis 1 and Beggiatoa 2 condense Pi into phosphate polymers in oxygenated environments. These polyphosphates (polyPs) are stored until the environment becomes anoxic, when these bacteria retrieve the energy from polyP dissociation into Pi3. Dissociated Pi is released outside of the bacteria, where it precipitates as apatite.The Gibbs free energy of polyP phosphoester bond hydrolysis is negative, however, the kinetics are slow4. Diatoms contain a polyP pool that is stable until after death, after which the polyPs hydrolyze and form apatite5. The roles of polyP in eukaryotic organism biochemistry continue to be discovered. PolyPs have a range of biochemical roles, such as bioavailable P-storage, stress adaptation, and blood clotting6. PolyP-containing granules are released from anuclear platelets to activate factor V7 and factor XII in the blood clotting process due to their polyanionic charge8. Platelets have a lifespan of approximately 8 days, after which they undergo apoptosis9. Data will be presented that demonstrate the bioactive, thermodynamically unstable polyP pool within older platelets in vitro can spontaneously hydrolyze and form phosphate minerals. This process is likely avoided by platelet digestion in the spleen and liver, possibly recycling platelet polyPs with their phosphoester bond energy for other biochemical roles. 1 Schulz HN et al. Science (2005) 307: 416-4182 Brüchert V et al. Geochim Cosmochim Acta (2003) 67: 4505-45183 Goldhammer T et al. Nat Geosci (2010) 3: 557-5614 de Jager H-J et al. J Phys Chem A (1988) 102: 2838-28415 Diaz, J et al. Science (2008) 320: 652-6556 Mason KD et al

  19. Factor XIII A-Subunit V34L Variant Affects Thrombus Cross-Linking in a Murine Model of Thrombosis. (United States)

    Duval, Cédric; Ali, Majid; Chaudhry, Waleed W; Ridger, Victoria C; Ariëns, Robert A S; Philippou, Helen


    Factor XIII (FXIII) cross-links fibrin upon activation by thrombin. Activation involves cleavage at residue 37 by thrombin, releasing an activation peptide. A common polymorphism (valine to leucine variant at residue 34, V34L), located in the activation peptide, has been associated with increased activation rates and paradoxically a protective effect in cardiovascular disease. There is, currently, no data available on the effects of V34L from in vivo models of thrombosis. We examined the effect of FXIII V34L on clot formation and cross-linking in vivo. We generated a panel of full-length recombinant human FXIII-A2 variants with amino acid substitutions in the activation peptide to investigate the effect of these variants on activation rate, and we used wild-type, V34L, and alanine to glycine variant at residue 33 variants to study the effects of varying FXIII activation rate on thrombus formation in a murine model of FeCl3 injury. FXIII activation assay showed that residues 29, 30, 33, and 34 play a critical role in thrombin interaction. Full-length recombinant human FXIII-A2 V34L has significant effects on clot formation, structure, and lysis in vitro, using turbidity assay. This variant influenced fibrin cross-linking but not size of the thrombus in vivo. Mutations in the activation peptide of full-length recombinant FXIII regulate activation rates by thrombin, and V34L influences in vivo thrombus formation by increased cross-linking of the clot. © 2016 American Heart Association, Inc.

  20. (/sup 125/I) radioiodinated metaraminol: A new platelet-specific labeling agent

    Energy Technology Data Exchange (ETDEWEB)

    Ohmomo, Y.; Yokoyama, A.; Kawai, K.; Arano, Y.; Horiuchi, K.; Tanaka, C.; Saji, H.; Torizuka, K.


    In our search for a platelet-specific labeling agent, metaraminol (MA), a low-toxic pharmaceutical for the treatment of hypotension and cardiogenic shock, attracted our attention. Its active incorporation and accumulation by platelets have been recognized. At first, the preparation of /sup 125/I radioiodinated metaraminol (/sup 125/I-MA) was carried out using the chloramine-T method. Then, upon the harvest of platelets as platelet-rich plasma (PRP), their labeling with this new radiopharmaceutical was easily performed by incubation for 10 min at 37/sup 0/C. The cell-labeling efficiency was dependent on cell density, reaching 63.0%+-3.1% at 2.4x10/sup 9/ cells/ml. The specific incorporation of /sup 125/I-MA by an active transport system similar to that of 5-hydroxytryptamine (5-HT) as well as by passive diffusion was demonstrated. In vitro studies, the unaltered state of /sup 125/I-MA-labeled platelets with their cellular functions fully retained was estimated. In vivo studies carried out in rabbits with induced thrombi in the femoral artery showed a rather rapid disappearance of the radioactivity from circulating blood, reaching a high thrombus-to-blood activity ratio of 19.8+-4.3 within 30 min of the administration of /sup 125/I-MA-labeled autologous platelets. Thus, with the potential availability of /sup 123/I, /sup 123/I-MA-labeled platelets appear to be a promising agent for thrombus imaging using single-emission computed tomography (CT) studies.

  1. Angioplasty of symptomatic high-grade internal carotid artery stenosis with intraluminal thrombus: therapeutic approach

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, A.; Mayol, A. [Seccion de Neurorradiologia Intervencionista, Servicio de Radiologia, Hospital Universitario Virgen del Rocio, Avenida Manuel Siurot s/n, Avenida Manuel Siurot s/n, 41013, Sevilla (Spain); Gil-Peralta, A.; Gonzalez-Marcos, J.R. [Servicio de Neurologia, Hospital Universitario Virgen del Rocio, Avenida Manuel Siurot s/n, 41013, Sevilla (Spain); Boza, F. [Servicio de Neurofisiologia, Hospital Universitario Virgen del Rocio, Avenida Manuel Siurot s/n, 41013, Sevilla (Spain); Ruano, J. [Unidad de Cuidados Intensivos, Hospital Universitario Virgen del Rocio, Avenida Manuel Siurot s/n, 41013, Sevilla (Spain)


    Intraluminal thrombus in the internal carotid artery (ICA) is usually found in patients with severe atheromatous stenosis. Having reviewed 300 carotid angioplasties for symptomatic >70% ICA stenosis, we found three patients (1%) with intraluminal thrombus. Conservative treatment with anticoagulants and double antiplatelet coverage can result in lysis of the thrombus without severe risks. Percutaneous transluminal angioplasty and stenting, preferably with distal protection, can be an excellent alternative to carotid endarterectomy. (orig.)

  2. Octadecyl Chains Immobilized onto Hyaluronic Acid Coatings by Thiol-ene "Click Chemistry" Increase the Surface Antimicrobial Properties and Prevent Platelet Adhesion and Activation to Polyurethane. (United States)

    Felgueiras, Helena P; Wang, L M; Ren, K F; Querido, M M; Jin, Q; Barbosa, M A; Ji, J; Martins, M C L


    Infection and thrombus formation are still the biggest challenges for the success of blood contact medical devices. This work aims the development of an antimicrobial and hemocompatible biomaterial coating through which selective binding of albumin (passivant protein) from the bloodstream is promoted and, thus, adsorption of other proteins responsible for bacterial adhesion and thrombus formation can be prevented. Polyurethane (PU) films were coated with hyaluronic acid, an antifouling agent, that was previously modified with thiol groups (HA-SH), using polydopamine as the binding agent. Octadecyl acrylate (C18) was used to attract albumin since it resembles the circulating free fatty acids and albumin is a fatty acid transporter. Thiol-ene "click chemistry" was explored for C18 immobilization on HA-SH through a covalent bond between the thiol groups from the HA and the alkene groups from the C18 chains. Surfaces were prepared with different C18 concentrations (0, 5, 10, and 20%) and successful immobilization was demonstrated by scanning electron microscopy (SEM), water contact angle determinations, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The ability of surfaces to bind albumin selectively was determined by quartz crystal microbalance with dissipation (QCM-D). Albumin adsorption increased in response to the hydrophobic nature of the surfaces, which augmented with C18 saturation. HA-SH coating reduced albumin adsorption to PU. C18 immobilized onto HA-SH at 5% promoted selective binding of albumin, decreased Staphylococcus aureus adhesion and prevented platelet adhesion and activation to PU in the presence of human plasma. C18/HA-SH coating was established as an innovative and promising strategy to improve the antimicrobial properties and hemocompatibility of any blood contact medical device.

  3. Ex vivo Time Evolution of Thrombus Growth through Optical and Electrical Impedance data fusion (United States)

    Affanni, A.; Specogna, R.; Trevisan, F.


    We designed a novel sensor specifically aimed at ex vivo measurements of white thrombus volume growth; a white thrombus is induced within an artificial micro-channel where hemostasis takes place starting from whole blood under flow conditions. The advantage of the proposed methodology is to identify the time evolution of the thrombus volume by means of an original data fusion methodology based on 2D optical and electrical impedance data simultaneously processed. On the contrary, the present state of the art optical imaging methodologies allow the thrombus volume estimation only at the end of the hemostatic process.

  4. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Emilie M.M. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, P.O. Box 2040, Rotterdam (Netherlands); Department of Radiology, AMC, Amsterdam (Netherlands); Yoo, Albert J. [Texas Stroke Institute, Plano, TX (United States); Beenen, Ludo F.; Majoie, Charles B. [Department of Radiology, AMC, Amsterdam (Netherlands); Berkhemer, Olvert A. [Department of Radiology, AMC, Amsterdam (Netherlands); Department of Neurology, Erasmus MC, Rotterdam (Netherlands); Blanken, Mark D. den; Wismans, Carrie [AMC, Department of Biomedical Engineering and Physics, Amsterdam (Netherlands); Niessen, Wiro J. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, P.O. Box 2040, Rotterdam (Netherlands); Delft University of Technology, Faculty of Applied Sciences, Delft (Netherlands); Marquering, Henk A. [Department of Radiology, AMC, Amsterdam (Netherlands); AMC, Department of Biomedical Engineering and Physics, Amsterdam (Netherlands); Collaboration: on behalf of the MR CLEAN investigators


    Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers. For 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland-Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis. The highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good. Absolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs. (orig.)

  5. Detection of Membrane Fluidity in Submitochondrial Particles of Platelets and Erythrocyte Membranes from Mexican Patients with Alzheimer Disease by Intramolecular Excimer Formation of 1,3 Dipyrenylpropane

    Directory of Open Access Journals (Sweden)

    G.G. Ortiz


    Full Text Available It has been suggested that mitochondrial dysfunction and defects in membrane structure could be implied in AD pathogenesis. The aim of the present work was the study of membrane fluidity in submitochondrial platelet particles and erythrocyte membranes from Mexican patients. Blood samples were obtained from 30 patients with Alzheimer disease and 30 aged-matched control subjects. Membrane fluidity determinations were done using a very low concentration of the fluorescent dipyrenylpropane probe incorporated in both types of membranes. This probe is able to give excimer and monomer fluorescence, therefore it can be used to monitor fluidity changes in biological membranes.

  6. Genetic variation responsible for mouse strain differences in integrin {alpha}{sub 2} expression is associated with altered platelet responses to collagen

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tong-Tong; Larrucea, Susana; Souza, Shiloe; Leal, Suzanne M.; Lopez, Jose A.; Rubin, Edward M.; Nieswandt, Bernhard; Bray, Paul F.


    Formation of a thrombus at the site of an injured vessel requires the coordinated action of critical platelet plasma membrane adhesion molecules. The most important initial contact of platelets with the exposed endothelial collagen and von Willebrand factor (VWF) involves the binding of glycoprotein (GP) Ib{alpha} to immobilized VWF. The VWF-GPIb{alpha} interaction is ''fast-on'' and relatively ''fast-off,'' and results in a rolling of platelets along the exposed subendothelium. This slowing of the platelets allows binding of the activating collagen-receptor, GPVI, to its ligand, resulting in activation of platelet integrins and subsequent firm adhesion, where the reactions between receptor and ligand are relatively ''slow-on'' but irreversible. The binding of integrin {alpha}{sub 2} {beta}{sub 1} underlying firm adhesion. Intracellular signaling between and through these adhesive receptors plays a crucial role in platelet adhesion and aggregation. The importance of the GPIb-IX-V and {alpha}{sub IIb} {beta}{sub 3} in normal hemostasis is under scored by the bleeding diatheses that have been reported in patients with quantitative or qualitative deficiencies of the genes that encode them. Mouse models are now commonplace for studying hemostasis and thrombosis, and important insights pertaining to the major platelet adhesive receptors have been gleaned from mouse studies involving targeted disruptions of the genes for GPIb{alpha}, GPVI, and integrin chains 2,9,10 1,4 IIb 11 and 3.12 A variety of different mouse strains have been used to assess hemostasis. For example, the FVB strain is typically used for transgenic experiments, the 129/Sv strain is used to derive embryonic stem (ES) cells, and the C57 strain is used for uniform background breeding studies. Different strains may exhibit different levels of gene expression, a feature that has been used to elucidate crucial gene regions regulating transcription

  7. ST Elevation Infarction after Heart Transplantation Induced by Coronary Spasms and Mural Thrombus Detected by Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Clemmensen, Tor Skibsted; Holm, Niels Ramsing; Eiskjær, Hans


    The case illustrates the possible link between coronary spasms, intraluminal thrombus formation, and widespread organized and layered thrombi in HTx patients. Furthermore, the case underlines the clinical value of OCT as a novel method for high-resolution vessel imaging in heart-transplanted (HTx...... due to acute myocardial infarction induced by severe coronary spasms. The patients remained unstable on conservative therapy. Therefore, an optical coherence tomography (OCT) was performed and revealed massive, organized thrombi in the left main coronary artery, the circumflex coronary artery...

  8. Fluoroscopy-Guided Resolution of Ingested Thrombus Leading to Functional Disturbance of a Continuous-Flow Left Ventricular Assist Device

    Directory of Open Access Journals (Sweden)

    Jens Garbade


    Full Text Available The third generation of left ventricular assist devices (LVADs has been shown to improve outcome and quality of life in patients suffering from acute and chronic heart failure. However, VAD-associated complications are still a challenge in the clinical practice. Here we report the resolution of a mobile thrombus formation in the proximity of the inflow cannula of a third generation of LVADs (HVAD Pump, HeartWare, Inc. in a patient with chronic heart failure 4 months after implantation.

  9. Retrievable Inferior Vena Cava Filters in Trauma Patients: Prevalence and Management of Thrombus Within the Filter. (United States)

    Pan, Y; Zhao, J; Mei, J; Shao, M; Zhang, J; Wu, H


    The incidence of thrombus was investigated within retrievable filters placed in trauma patients with confirmed DVT at the time of retrieval and the optimal treatment for this clinical scenario was assessed. A technique called "filter retrieval with manual negative pressure aspiration thrombectomy" for management of filter thrombus was introduced and assessed. The retrievable filters referred for retrieval between January 2008 and December 2015 were retrospectively reviewed to determine the incidence of filter thrombus on a pre-retrieval cavogram. The clinical outcomes of different managements for thrombus within filters were recorded and analyzed. During the study 764 patients having Aegisy Filters implanted were referred for filter removal, from which 236 cases (134 male patients, mean age 50.2 years) of thrombus within the filter were observed on initial pre-retrieval IVC venogram 12-39 days after insertion (average 16.9 days). The incidence of infra-filter thrombus was 30.9%, and complete occlusion of the filter bearing IVC was seen in 2.4% (18) of cases. Retrieval was attempted in all 121 cases with small clots using a regular snare and sheath technique, and was successful in 120. A total of 116 cases with massive thrombus and IVC occlusion by thrombus were treated by CDT and/or the new retrieval technique. Overall, 213 cases (90.3%) of thrombus in the filter were removed successfully without PE. A small thrombus within the filter can be safely removed without additional management. CDT for reduction of the clot burden in filters was effective and safe. Filter retrieval with manual negative pressure aspiration thrombectomy seemed reasonable and valuable for management of massive thrombus within filters in some patients. Full assessment of the value and safety of this technique requires additional studies. Copyright © 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  10. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress (United States)

    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  11. Regulation of the genetic code in megakaryocytes and platelets. (United States)

    Rondina, M T; Weyrich, A S


    Platelets are generated from nucleated precursors referred to as megakaryocytes. The formation of platelets is one of the most elegant and unique developmental processes in eukaryotes. Because they enter the circulation without nuclei, platelets are often considered simple, non-complex cells that have limited functions beyond halting blood flow. However, emerging evidence over the past decade demonstrates that platelets are more sophisticated than previously considered. Platelets carry a rich repertoire of messenger RNAs (mRNAs), microRNAs (miRNAs), and proteins that contribute to primary (adhesion, aggregation, secretion) and alternative (immune regulation, RNA transfer, translation) functions. It is also becoming increasingly clear that the 'genetic code' of platelets changes with race, genetic disorders, or disease. Changes in the 'genetic code' can occur at multiple points including megakaryocyte development, platelet formation, or in circulating platelets. This review focuses on regulation of the 'genetic code' in megakaryocytes and platelets and its potential contribution to health and disease. © 2015 International Society on Thrombosis and Haemostasis.

  12. Clinical outcome and morphologic determinants of mural thrombus in abdominal aortic endografts

    NARCIS (Netherlands)

    N.F. Oliveira (N.); F.M.V. Bastos Gonçalves (Frederico); S.E. Hoeks (Sanne); S. ten Raa (Sander); K.H.J. Ultee (Klaas); E.V. Rouwet (Ellen); J.M. Hendriks (Joke); H.J.M. Verhagen (Hence)


    textabstractObjective Endograft mural thrombus has been associated with stent graft or limb thrombosis after endovascular aneurysm repair (EVAR). This study aimed to identify clinical and morphologic determinants of endograft mural thrombus accumulation and its influence on thromboembolic events aft

  13. Tumour thrombus consistency has no impact on survival in patients with renal cell carcinoma. (United States)

    Gołąbek, T; Przydacz, M; Okoń, K; Kopczyński, J; Bukowczan, J; Sobczyński, R; Curyło, Ł; Gołąbek, K; Curyło, Ł; Chłosta, P


    The prognosis of renal cell carcinoma (RCC) with venous tumour thrombus (VTT) is variable and not always possible to predict. The prognostic impact and independence of tumour thrombus-related factors including the recently introduced tumour thrombus consistency (TTC) on overall survival remain controversial. The aim of this study was to investigate the prognostic role of TTC in patients' survival. We determined the tumour thrombus consistency (solid vs. friable) in a cohort of 84 patients with RCC and VTT who underwent nephrectomy with thrombectomy, and performed a retrospective evaluation of the patients' data from the prospectively maintained database. A total of 45% of patients had solid thrombus (sTT) and 55% had friable thrombus (fTT). The venous tumour thrombus consistency was not predictive of overall survival. Further studies, preferably prospective and with a larger number of patients, are needed to validate the obtained results, as well as to evaluate the usefulness of tumour thrombus consistency in clinical practice for stratifying the risk of recurrence and planning further follow-up.

  14. Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke

    NARCIS (Netherlands)

    E.M.M. Santos (Emilie M.); H. Marquering (Henk); O.A. Berkhemer (Olvert); W.H. van Zwam (Wim); A. van der Lugt (Aad); C.B. Majoie (Charles); W.J. Niessen (Wiro)


    textabstractBackground and Purpose: Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and tim

  15. AngioVac extraction of intra-atrial hepatoma masquerading as PICC-associated thrombus (United States)

    Abboud, Samir; Raparia, Kirtee; Ubago, Julianne M.; Resnick, Scott


    Thrombus associated with peripherally inserted central catheterization is not uncommon. Treatment is typically conservative; however, more aggressive therapies can be considered in patients with tenuous medical condition. The authors present a patient with metastatic hepatocellular carcinoma masquerading as peripherally inserted central catheter-associated intra-atrial thrombus, subsequently removed via vacuum-assisted mechanical thrombectomy. PMID:26509915

  16. Left Atrial Thrombus in a Neonate with Normal Heart after Sustained Supraventricular Tachycardia



    Left Atrial Thrombus is uncommon in neonates. We present a neonate who had Paroxysmal Supraventricular Tachycardia (PSVT), whose echocardiography revealed a large left atrial thrombus which resolved later with treatment. Supra Ventricular Tachycardia (SVT) is not an uncommon event in infants with an incidence of 1:2500.

  17. Free-floating left atrial ball thrombus early after mitral valve replacement. (United States)

    Sanae, T; Kazama, S; Nie, M; Miyoshi, Y; Machii, M; Ohara, K; Yoshimura, H


    A 61-year-old woman was found to have a free-floating ball, thrombus in the left atrium on echocardiographic examination 2 weeks after mitral valve replacement and tricuspid, annuloplasty. The free-floating thrombus was successfully, removed by an open-heart procedure without clinical sequelae. The diagnostic value of routine echocardiography on follow-up of valve surgery is emphasized.

  18. Thrombus aspiration in acute myocardial infarction:Rationale and indication

    Institute of Scientific and Technical Information of China (English)

    Gennaro; Sardella; Rocco; Edoardo; Stio


    Reperfusion of myocardial tissue is the main goal of primary percutaneous coronary intervention(PPCI) with stent implantation in the treatment of acute ST-segment elevation myocardial infarction(STEMI). Although PPCI has contributed to a dramatic reduction in cardiovascular mortality over three decades, normal myocardial perfusion is not restored in approximately one-third of these patients. Several mechanisms may contribute to myocardial reperfusion failure, in particular distal embolization of the thrombus and plaque fragments. In fact, this is a possible complication during PPCI, resulting in microvascular obstruction and no-reflow phenomenon. The presence of a visible thrombus at the time of PPCI in patients with STEMI is associated with poor procedural and clinical outcomes. Aspiration thrombectomy during PPCI has been proposed to prevent embolization in order to improve these outcomes. In fact, the most recent guidelines suggest the routine use of manual aspiration thrombectomy during PPCI(class Ⅱa) to reduce the risk of distal embolization. Even though numerous international studies have been reported, there are conflicting results on the clinical impact of aspiration thrombectomy during PPCI. In particular, data on long-term clinical outcomes are still inconsistent. In this review, we have carefully analyzed literature data on thrombectomy during PPCI, taking into account the most recent studies and meta-analyses.

  19. Novel risk predictor for thrombus deposition in abdominal aortic aneurysms (United States)

    Nestola, M. G. C.; Gizzi, A.; Cherubini, C.; Filippi, S.; Succi, S.


    The identification of the basic mechanisms responsible for cardiovascular diseases stands as one of the most challenging problems in modern medical research including various mechanisms which encompass a broad spectrum of space and time scales. Major implications for clinical practice and pre-emptive medicine rely on the onset and development of intraluminal thrombus in which effective clinical therapies require synthetic risk predictors/indicators capable of informing real-time decision-making protocols. In the present contribution, two novel hemodynamics synthetic indicators, based on a three-band decomposition (TBD) of the shear stress signal, are introduced. Extensive fluid-structure computer simulations of patient-specific scenarios confirm the enhanced risk-prediction capabilities of the TBD indicators. In particular, they permit a quantitative and accurate localization of the most likely thrombus deposition in realistic aortic geometries, where previous indicators would predict healthy operation. The proposed methodology is also shown to provide additional information and discrimination criteria on other factors of major clinical relevance, such as the size of the aneurysm.

  20. Biological evaluation of thrombus imaging agents utilizing water soluble phosphines and tricine as coligands when used to label a hydrazinonicotinamide-modified cyclic glycoprotein IIb/IIIa receptor antagonist with 99mTc. (United States)

    Barrett, J A; Crocker, A C; Damphousse, D J; Heminway, S J; Liu, S; Edwards, D S; Lazewatsky, J L; Kagan, M; Mazaika, T J; Carroll, T R


    A hydrazinonicotinamide-functionalized cyclic glycoprotein IIb/IIIa (GPIIb/IIIa) receptor antagonist [cyclo(D-Val-NMeArg-Gly-Asp-Mamb(5-(6-(6-hydrazinonicotin amido)hexanamide))) (HYNICtide)] was labeled with 99mTc using tricine and a water soluble phosphine [trisodium triphenylphosphine-3,3',3"-trisulfonate (TPPTS); disodium triphenylphosphine-3,3'-disulfonate (TPPDS); or sodium triphenylphosphine-3-monosulfonate (TPPMS)] as coligands. Three complexes, [99mTc(HYNICtide)(L)(tricine)] (1, L = TPPTS; 2, L = TPPDS; 3, L = TPPMS), were evaluated in the canine arteriovenous shunt (AV shunt) model and canine deep vein thrombosis imaging (DVT) model. All three agents were adequately incorporated into the arterial and venous portions of the growing thrombus (7.8-9.9 and 0.2-3.7% ID/g, respectively) in the canine AV shunt model. In the canine DVT model all three complexes had thrombus uptake that far exceeded the negative control, [99mTc]albumin. The findings indicate similar incorporation into a venous thrombus (% ID/g = 2.86 +/- 0.4, 3.4 +/- 0.9, and 3.38 +/- 1.1 for complexes 1, 2, and 3, respectively) and similar blood clearance with a t1/2 of approximately 90 min. Gamma camera scintigraphy allowed visualization of deep vein thrombosis in as little as 15 min with the thrombus/muscle ratios being 3.8 +/- 0.8, 2.8 +/- 0.4, and 3.0 +/- 0.8 for complexes 1, 2, and 3, respectively. The visualization of the thrombus improved over time, and the thrombus/muscle ratios were 9.7 +/- 1.9, 13.8 +/- 3.6, and 9.4 +/- 2 for complexes 1, 2, and 3, respectively, at 120 min postinjection. The administration of complexes 1-3 did not alter platelet function, hemodynamics, or the coagulation cascade. Furthermore, complexes 1-3 did not significantly differ in their uptake into the growing thrombus, blood clearance, and target to background ratios. Therefore, all three complexes have the capability to detect rapidly growing venous and arterial thrombi.

  1. Platelet reactions to modified surfaces under dynamic conditions. (United States)

    Rhodes, N P; Shortland, A P; Rattray, A; Williams, D F


    The influence of surfaces on the reactions of platelets in whole blood under laminar flow was investigated in a cone and plate viscometer. Citrated whole blood was exposed to steel, PMMA and PMMA modified with PEO at low (500 s(-1)) and high (4000 s(-1)) wall shear rates at room temperature for a period of 100 s. Treated blood samples were fixed with paraformaldehyde, stained with a monoclonal antibody for CD41 (platelet GPIIb/IIIa) conjugated with phycoerythrin and analyzed by flow cytometry. The reactions of platelets (microparticle generation and formation of platelet-platelet, platelet-red blood cell and red blood cell-microparticle aggregates) to these environments were quantified. Additionally, the size of platelet-platelet aggregates was assessed. The percentage platelet aggregation and numbers of microparticles generated were independent of surface type at any shear rate. The composition of the aggregates formed was influenced by the surface: at low and high shear rates PMMA caused the generation of platelet-platelet aggregates of the greatest size. The numbers of red blood cell-platelet and red blood cell-microparticle aggregates also varied depending on the surface. Fewer red blood cell-platelet aggregates were formed at higher shear rates, whereas the reverse was true for red blood cell-microparticle aggregates. It is concluded that these variations may help to explain the differential effects of surfaces to the induction of distant thrombotic events: microparticles may be protected from loss from the blood stream by their association with red blood cells at high shear rates.

  2. Platelet alloimmunization after transfusion

    DEFF Research Database (Denmark)

    Taaning, E; Simonsen, A C; Hjelms, E;


    BACKGROUND AND OBJECTIVES: The frequency of platelet-specific antibodies after one series of blood transfusions has not been reported, and in multiply transfused patients is controversial. MATERIALS AND METHODS: We studied the frequency of alloimmunization against platelet antigens in 117 patient...

  3. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten


    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  4. Gasotransmitters and platelets. (United States)

    Truss, Nicola J; Warner, Timothy D


    Platelets are essential to prevent blood loss and promote wound healing. Their activation comprises of several complex steps which are regulated by a range of mediators. Over the last few decades there has been intense interest in a group of gaseous mediators known as gasotransmitters; currently comprising nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S). Here we consider the action of gasotransmitters on platelet activity. NO is a well established platelet inhibitor which mediates its effects predominantly through activation of soluble guanylyl cyclase leading to a decrease in intraplatelet calcium. More recently CO has been identified as a gasotransmitter with inhibitory actions on platelets; CO acts through the same mechanism as NO but is less potent. The in vivo and platelet functions of the most recently identified gasotransmitter, H(2)S, are still the subject of investigations, but they appear generally inhibitory. Whilst there is evidence for the individual action of these mediators, it is also likely that combinations of these mediators are more relevant regulators of platelets. Furthermore, current evidence suggests that these mediators in combination alter the production of each other, and so modify the circulating levels of gasotransmitters. The use of gasotransmitters as therapeutic agents is also being explored for a range of indications. In conclusion, the importance of NO in the regulation of vascular tone and platelet activity has long been understood. Other gasotransmitters are now establishing themselves as mediators of vascular tone, and recent evidence suggests that these other gasotransmitters may also modulate platelet function.

  5. Monocyte-Platelet Interaction Induces a Pro-Inflammatory Phenotype in Circulating Monocytes



    BACKGROUND: Activated platelets exert a pro-inflammatory action that can be largely ascribed to their ability to interact with leukocytes and modulate their activity. We hypothesized that platelet activation and consequent formation of monocyte-platelet aggregates (MPA) induces a pro-inflammatory phenotype in circulating monocytes. METHODOLOGY/PRINCIPAL FINDINGS: CD62P(+) platelets and MPA were measured, and monocytes characterized, by whole blood flow cytometry in healthy subjects, before an...

  6. Influence of Cardiopulmonary Bypass on the Interaction of Recombinant Factor VIIa with Activated Platelets


    Kjalke, Marianne; Runge, Marx; Rojkjaer, Rasmus; Steinbruchel, Daniel; Johansson, Pär I


    Recombinant factor VIIa (rFVIIa) interacts preferentially with coated platelets characterized by a high exposure of phosphatidyl serine (PS), FV, FVIII, FIX, and FX binding, and fibrinogen. Cardiopulmonary bypass (CPB) is known to impair platelet function. In this study, the influence of CPB on formation of coated platelets and the interaction of rFVIIa with the platelets were studied. Blood was either exposed to a closed CPB circuit or obtained from patients undergoing CPB-assisted cardiac s...

  7. Detection of Platelet-Monocyte Aggregates by the ADAM® Image Cytometer


    Jung, Bo Kyeung; Cho, Chi Hyun; Moon, Kyung Chul; sung Hur, Dae; YOON, Jeong-Ah; Yoon, Soo-Young


    Background: Inappropriate platelet activation is known to be associated with various thrombotic disorders. Platelet-monocyte aggregates (PMAs), whose formation is mediated by platelet surface P-selectin (CD62P), can be used as a reliable marker to detect platelet activation. Previous studies have generally detected PMAs through flow cytometry-based approaches. Recently, the ADAM® image cytometer (Nanoentek Inc., Seoul, Korea) was developed for image-based cellular analysis. In this study, we ...

  8. The relationship between fractional flow reserve, platelet reactivity and platelet leukocyte complexes in stable coronary artery disease.

    Directory of Open Access Journals (Sweden)

    Jan-Willem E M Sels

    Full Text Available BACKGROUND: The presence of stenoses that significantly impair blood flow and cause myocardial ischemia negatively affects prognosis of patients with stable coronary artery disease. Altered platelet reactivity has been associated with impaired prognosis of stable coronary artery disease. Platelets are activated and form complexes with leukocytes in response to microshear gradients caused by friction forces on the arterial wall or flow separation. We hypothesized that the presence of significantly flow-limiting stenoses is associated with altered platelet reactivity and formation of platelet-leukocyte complexes. METHODS: One hundred patients with stable angina were studied. Hemodynamic significance of all coronary stenoses was assessed with Fractional Flow Reserve (FFR. Patients were classified FFR-positive (at least one lesion with FFR≤0.75 or FFR-negative (all lesions FFR>0.80. Whole blood samples were stimulated with increasing concentrations of ADP, TRAP, CRP and Iloprost with substimulatory ADP. Expression of P-selectin as platelet activation marker and platelet-leukocyte complexes were measured by flowcytometry. Patients were stratified on clopidogrel use. FFR positive and negative patient groups were compared on platelet reactivity and platelet-leukocyte complexes. RESULTS: Platelet reactivity between FFR-positive patients and FFR-negative patients did not differ. A significantly lower percentage of circulating platelet-neutrophil complexes in FFR-positive patients and a similar non-significant decrease in percentage of circulating platelet-monocyte complexes in FFR-positive patients was observed. CONCLUSION: The presence of hemodynamically significant coronary stenoses does not alter platelet reactivity but is associated with reduced platelet-neutrophil complexes in peripheral blood of patients with stable coronary artery disease.

  9. Alloimmune refractoriness to platelet transfusions. (United States)

    Sandler, S G


    Patients who are transfused on multiple occasions with red cells or platelets may develop platelet-reactive alloantibodies and experience decreased clinical responsiveness to platelet transfusion. This situation, conventionally described as "refractoriness to platelet transfusions," is defined by an unsatisfactory low post-transfusion platelet count increment. If antibodies to HLAs are detected, improved clinical outcomes may result from transfusions of HLA-matched or donor-recipient cross-matched platelets. Because refractoriness is an expected, frequently occurring phenomenon, prevention of HLA alloimmunization is an important management strategy. Prevention strategies include efforts to decrease the number of transfusions, filtration of cellular components to reduce the number of HLA-bearing leukocytes, or pretransfusion ultraviolet B irradiation of cellular components to decrease their immunogenicity. Other investigational approaches include reducing the expression of HLAs on transfused platelets, inducing a transient reticuloendothelial system blockade by infusions of specialized immunoglobulin products, or transfusing semisynthetic platelet substitutes (thromboerythrocytes, thrombospheres) or modified platelets (infusible platelet membranes, lyophilized platelets).

  10. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.


    Cairn Terriers, 10 Boxers, and 11 Labrador Retrievers) were included in the study. Platelet function was assessed by whole-blood aggregation with ADP (1, 5, 10, and 20 µM) as agonist and by PFA-100 using collagen and epinephrine (Col + Epi) and Cpæ + ADP as agonists. Plasma thromboxane B2 concentration......Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...

  11. Cisplatin triggers platelet activation. (United States)

    Togna, G I; Togna, A R; Franconi, M; Caprino, L


    Clinical observations suggest that anticancer drugs could contribute to the thrombotic complications of malignancy in treated patients. Thrombotic microangiopathy, myocardial infarction, and cerebrovascular thrombotic events have been reported for cisplatin, a drug widely used in the treatment of many solid tumours. The aim of this study is to explore in vitro cisplatin effect on human platelet reactivity in order to define the potentially active role of platelets in the pathogenesis of cisplatin-induced thrombotic complications. Our results demonstrate that cisplatin increases human platelet reactivity (onset of platelet aggregation wave and thromboxane production) to non-aggregating concentrations of the agonists involving arachidonic acid metabolism. Direct or indirect activation of platelet phospholipase A(2) appears to be implicated. This finding contributes to a better understanding of the pathogenesis of thrombotic complications occurring during cisplatin-based chemotherapy.

  12. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.


    Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...... applied. However, the importance of these breed differences remains to be investigated. The PFA-100 method with Col + Epi as agonists, and ADP-induced platelet aggregation appear to be sensitive to ASA in dogs....

  13. Measurement of platelet aggregation, independently of patient platelet count

    DEFF Research Database (Denmark)

    Vinholt, P. J.; Frederiksen, H.; Hvas, A.M.


    platelet aggregation ruled out bleeding tendency in thrombocytopenic patients. Summary: Background: Methods for testing platelet aggregation in thrombocytopenia are lacking. Objective: To establish a flow-cytometric test of in vitro platelet aggregation independently of the patient's platelet count......, and examine the association of aggregation with a bleeding history in thrombocytopenic patients. Patients/methods: We established a flow-cytometric assay of platelet aggregation, and measured samples from healthy individuals preincubated with antiplatelet drugs, and samples from two patients with inherited...... platelets at platelet counts of > 10 × 109 L-1; otherwise, platelet isolation was required. The platelet aggregation percentage decreased with increasing antiplatelet drug concentration. Platelet aggregation in patients was reduced as compared with healthy individuals: 42% (interquartile range [IQR] 27...

  14. Lyotropic hexagonal columnar liquid crystals of large colloidal gibbsite platelets

    NARCIS (Netherlands)

    Mourad, M.C.D.; Petukhov, A.V.; Vroege, G.J.; Lekkerkerker, H.N.W.


    We report the formation of hexagonal columnar liquid crystal phases in suspensions of large (570 nm diameter), sterically stabilized, colloidal gibbsite platelets in organic solvent. In thin cells these systems display strong iridescence originating from hexagonally arranged columns that are

  15. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

    Energy Technology Data Exchange (ETDEWEB)

    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA) State Univ. of New York, Buffalo (USA))


    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of ({sup 3}H)serotonin, or alter the dose-responsive binding of {sup 125}I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF.

  16. Split-bolus single-phase cardiac multidetector computed tomography for reliable detection of left atrial thrombus. Comparison to transesophageal echocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Staab, W.; Zwaka, P.A.; Sohns, J.M.; Schwarz, A.; Lotz, J. [University Medical Center Goettingen Univ. (Germany). Inst. for Diagnostic and Interventional Radiology; Sohns, C.; Vollmann, D.; Zabel, M.; Hasenfuss, G. [Goettingen Univ. (Germany). Dept. of Cardiology and Pneumology; Schneider, S. [Goettingen Univ. (Germany). Dept. of Medical Statistics


    Evaluation of a new cardiac MDCT protocol using a split-bolus contrast injection protocol and single MDCT scan for reliable diagnosis of LA/LAA thrombi in comparison to TEE, optimizing radiation exposure and use of contrast agent. A total of 182 consecutive patients with drug refractory AF scheduled for PVI (62.6% male, mean age: 64.1 ± 10.2 years) underwent routine diagnostic work including TEE and cardiac MDCT for the evaluation of LA/LAA anatomy and thrombus formation between November 2010 and March 2012. Contrast media injection was split into a pre-bolus of 30 ml and main bolus of 70 ml iodinated contrast agent separated by a short time delay. In this study, split-bolus cardiac MDCT identified 14 of 182 patients with filling defects of the LA/LAA. In all of these 14 patients, abnormalities were found in TEE. All 5 of the 14 patients with thrombus formation in cardiac MDCT were confirmed by TEE. MDCT was 100% accurate for thrombus, with strong but not perfect overall results for SEC equivalent on MDCT.

  17. Generation of functional platelets from canine induced pluripotent stem cells. (United States)

    Nishimura, Toshiya; Hatoya, Shingo; Kanegi, Ryoji; Sugiura, Kikuya; Wijewardana, Viskam; Kuwamura, Mitsuru; Tanaka, Miyuu; Yamate, Jyoji; Izawa, Takeshi; Takahashi, Masahiro; Kawate, Noritoshi; Tamada, Hiromichi; Imai, Hiroshi; Inaba, Toshio


    Thrombocytopenia (TTP) is a blood disease common to canines and human beings. Currently, there is no valid therapy for this disease except blood transfusion. In this study, we report the generation of canine induced pluripotent stem cells (ciPSCs) from canine embryonic fibroblasts, and a novel protocol for creating mature megakaryocytes (MKs) and functional platelets from ciPSCs. The ciPSCs were generated using lentiviral vectors, and differentiated into MKs and platelets on OP9 stromal cells supplemented with growth factors. Our ciPSCs presented in a tightly domed shape and showed expression of a critical pluripotency marker, REX1, and normal karyotype. Additionally, ciPSCs differentiated into cells derived from three germ layers via the formation of an embryoid body. The MKs derived from ciPSCs had hyperploidy and transformed into proplatelets. The proplatelets released platelets early on that expressed specific MK and platelet marker CD41/61. Interestingly, these platelets, when activated with adenosine diphosphate or thrombin, bind to fibrinogen. Moreover, electron microscopy showed that the platelets had the same ultrastructure as peripheral platelets. Thus, we have demonstrated for the first time the generation of ciPSCs that are capable of differentiating into MKs and release functional platelets in vitro. Our system for differentiating ciPSCs into MKs and platelets promises a critical therapy for canine TTP and appears to be extensible in principle to resolve human TTP.

  18. Stimulation of Platelet Death by Vancomycin

    Directory of Open Access Journals (Sweden)

    Syeda T. Towhid


    Full Text Available Background/Aims: Side effects of vancomycin, a widely used antibiotic, include thrombocytopenia. The vancomycin-induced thrombocytopenia has been attributed to immune reactions. At least in theory, thrombocytopenia could result in part from the triggering of apoptosis, which results in cell shrinkage and cell membrane scrambling with subsequent phosphatidylserine exposure at the cell surface. The cell membrane scrambling could be initiated by a signaling involving increase of cytosolic Ca2+ activity, ceramide formation, mitochondrial depolarization and/or caspase activation. Vancomycin has indeed been shown to trigger neutrophil apoptosis. An effect of vancomycin on platelet apoptosis has, however, never been tested. The present study thus explored the effect of vancomycin on platelet activation and apoptosis. Methods: Human blood platelets were exposed to vancomycin and forward scatter was utilized to estimate cell volume, annexin V-binding to quantify phosphatidylserine (PS exposure, Fluo-3 AM fluorescence to estimate cytosolic Ca2+ activity ([Ca2+]i, antibodies to quantify ceramide formation and immunofluorescence to quantify protein abundance of active caspase-3. Results: A 30 minutes exposure to vancomycin (≥1 µg/ ml decreased cell volume, triggered annexin V-binding, increased [Ca2+]i, activated caspase 3, stimulated ceramide formation, triggered release of thromboxane B2, and upregulated surface expression of CD62P (P-selectin as well as activated integrin αllbβ3. Annexin V-binding and upregulation of CD62P (P-selectin and integrin αllbβ3 was significantly blunted by removal of extracellular Ca2+. Annexin V-binding was not significantly blunted by pan-caspase inhibitor zVAD-FMK (1 µM. In conclusion, vancomycin results in platelet activation and suicidal platelet death with increase of [Ca2+]i, caspase-3 activation, cell membrane scrambling and cell shrinkage. Activation and cell membrane scrambling required the presence of Ca2

  19. Possible roles of platelet-derived microparticles in atherosclerosis. (United States)

    Wang, Zhi-Ting; Wang, Zi; Hu, Yan-Wei


    Platelets and platelet-derived microparticles (PMPs) play important roles in cardiovascular diseases, especially atherosclerosis. Continued research has revealed that PMPs have numerous functions in atherosclerosis, not only in thrombosis formation, but also by induction of inflammation. PMPs also induce formation of foam cells. Recent evidence strongly indicates a significant role of PMPs in atherosclerosis. Here, current research on the function of PMPs in atherosclerosis is reviewed.

  20. In situ formation of CA[sub 6] platelets in Al[sub 2]O[sub 3] and Al[sub 2]O[sub 3]/ZrO[sub 2] matrices

    Energy Technology Data Exchange (ETDEWEB)

    Belmonte, M. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Sanchez-Herencia, A.J. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Moreno, R. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Miranzo, P. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Moya, J.S. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Tomsia, A.P. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain) Lawrence Berkeley Lab. and U.C. Berkeley, CA (United States))


    Al[sub 2]O[sub 3] and Al[sub 2]O[sub 3]/ZrO[sub 2] compacts containing CaO as a dopant have been sintered under different conditions and atmospheres: air, high vacuum (> 10[sup -6]torr). SEM observations have been made on the polished surfaces of sintered and also of annealed samples. Only after the annealing treatment in air at temperatures ranging from 1400 to 1500 C, a massive formation of CA[sub 6] platelets was detected in samples sintered in low oxygen partial pressure atmospheres. In order to clarify the mechanism of formation of this secondary phase at the grain boundaries, CaO has been introduced in the form of either plaster of Paris (to reproduce a possible contamination provided by the molds in slip casting) or CaCO[sub 3]. The obtained results indicate the important role of the firing atmosphere on the precipitation of secondary phases at grain boundary. (orig.).

  1. Association of the Monocyte to HDL Cholesterol Ratio With Thrombus Burden in Patients With ST-Segment Elevation Myocardial Infarction. (United States)

    Arısoy, Arif; Altunkaş, Fatih; Karaman, Kayıhan; Karayakalı, Metin; Çelik, Ataç; Ceyhan, Köksal; Zorlu, Çağrı


    Intracoronary thrombus burden is associated with some adverse events and poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI). Identifying predictors of the intracoronary thrombus burden may contribute to the management of STEMI. In this study, we evaluated whether monocyte count to high-density lipoprotein cholesterol ratio (MHR) is a predictor of intracoronary thrombus burden in patients with STEMI. The study population consisted of 414 patients with STEMI who underwent primary percutaneous coronary intervention (PCI). Angiographic thrombus burden was classified based on thrombolysis in myocardial infarction (TIMI) thrombus grades. The patients were grouped into 2 categories of low thrombus burden and high thrombus burden. The MHR was significantly higher in the high thrombus burden group compared with the low thrombus group (16.0 [9.2-22.1] vs 25.4 [13.5-44.6]; P MHR was an independent predictor of high thrombus burden (odds ratio: 1.067, 95% CI: 1.031-1.105; P MHR was 0.688 (0.641-0.733; P MHR was independent predictor of high thrombus burden in patients with STEMI who underwent primary PCI.

  2. Defining Platelet Function During Polytrauma (United States)


    using calibrated automated thrombography ( CAT ). 3. Platelet-induced clot contraction and using viscoelastic measures such as TEG with Platelet Mapping...using calibrated automated thrombography ( CAT ) in platelet-rich plasma. 3. Platelet-induced clot contraction and effect on clot structure by platelet...if injury with stable vital signs on initial evaluation.  Pregnancy (confirmed with urine pregnancy testing)  Documented do not resuscitate order

  3. Stentriever thrombectomy with distal protection device for carotid free floating thrombus: a technical case report. (United States)

    Giragani, Suresh; Balani, Ankit; Agrawal, Vikas


    We report the clinical details, imaging findings and management of a 45-year-old man who presented with recurrent transient ischemic attacks due to carotid free floating thrombus. Free floating thrombus of the carotid artery is a very rare condition with a high risk of distal embolic shower. The optimal treatment options are debatable and include medical management, surgical thrombectomy and endovascular thrombectomy. We describe the use of a stentriever with filter protection in the management of carotid free floating thrombus as a novel treatment option.

  4. Double-edged sword in the heart: trapped deep venous thrombus in a patent foramen ovale. (United States)

    Acikel, Sadik; Ertem, Ahmet G; Kiziltepe, Ugursay; Dogan, Mehmet; Kilic, Harun; Yeter, Ekrem


    Trapped thrombus in a patent foramen ovale is a rare condition. Echocardiography is the main tool for diagnosis and for determination of the treatment to choose. There are a number of treatment options for trapped deep venous thrombus in a patent foramen ovale, including surgical thrombectomy, thrombolytics, and anticoagulant therapy. All patients should be evaluated individually, because the systemic and pulmonary thromboembolism risk of all treatment options is like a 'double-edged sword'. Here, we report a case of a patient with trapped thrombus in the patent foramen ovale detected by echocardiography, and successfully treated with surgical thrombectomy under extracorporeal circulation.

  5. Renal angiomyolipoma with inferior vena caval thrombus in a 32-year-old male

    Directory of Open Access Journals (Sweden)

    Matthew W Christian


    Full Text Available Renal angiomyolipoma (AML rarely presents with evidence of extension into the renal vein, inferior vena cava (IVC or atrium. We report a case of a renal AML with a tumor thrombus to the IVC in a 32-year-old male. The patient subsequently underwent a right radical nephrectomy with IVC tumor thrombectomy. To our knowledge, there are four published cases of renal AML presenting with tumor thrombus in males. This case report describes the management of the youngest male ever to develop a renal AML with IVC tumor thrombus.

  6. RWR affects thrombosis by interaction with integrin αⅡbβ3 receptor on surface of platelet%RWR通过与血小板表面整合素α Ⅱb β3受体作用对血栓形成的影响

    Institute of Scientific and Technical Information of China (English)

    赵海霞; 杨涛; 杨利军


    Objective To investigate the effect of RWP peptide containing RGD (Arg-Gly-Asp) sequence,combined with integrin αⅡbβ3 (GP Ⅱb/ma) receptor on the surface of platelet,on the inhibitory rate of platelet aggregation,thrombus formation and vascular tissue structure.Methods Blood samples of ten healthy volunteers without cardiovascular and cerebrovascular diseases were collected,from which platelet-rich plasma(PRP) was separated.The effect of RWR at various concentrations (6.25,12.5,25,50,100 and 200 μmol/L) on the inhibitory rate of platelet aggregation induced by ADPNa2 was determined by platelet aggregation analyzer.Rabbits were treated with RWR at concentrations of 0.3,0.6and 1.2 mg / kg to establish a model of thrombosis with arteriovenous bypass loop,while rats with RWR at concentrations of 0.6,1.2 and 2.4 mg / kg to establish a model of ferric chloride thrombosis,of which the changes of thrombus weight and vascular tissue structure were observed.Results With the increasing RWR concentration,the maximum platelet aggregation rate increased,while the inhibitory rate of platelet aggregation increased,the thrombus weight decreased,the inhibitory rate of thrombus formation increased,the degree of vascular stenosis decreased,and the vascular lumen pore was enlarged.The IC50 of RWR to inhibitory rate of platelet aggregation was 16.0 μmol/L.Conclusion RWR inhibited platelet aggregation and play an antithrombotic role through binding to integrin α Ⅱbβ3 receptor on the surface of platelet.%目的 探讨含RGD (Arg-Gly-Asp)序列的RWR小肽通过与血小板表面整合素αⅡbβ3(GPⅡb/Ⅲa)结合,对血小板聚集抑制率、血栓重量、血管组织结构的影响.方法 取10名无心脑血管疾病的健康志愿者的全血,分离富含血小板的血浆(platelet-rich plasma,PRP),采用血小板聚集仪检测不同剂量(6.25、12.5、25、50、100、200μmol/L)RWR对二磷酸腺苷二钠(ADPNa2)诱导的血小板聚集抑制率的影响;分别用0

  7. Playing games with a thrombus: a dangerous match. Paradoxical embolism from a huge central venous cathether thrombus: a case report

    Directory of Open Access Journals (Sweden)

    Mariana Sylvie


    Full Text Available Abstract Thromboembolism is a major cause of death in cancer patients. The association between paraneoplastic hypercoagulability of oncological patients and long-term central venous catheters (CVC may result in CVC associated thrombosis. Patent Foramen Ovale (PFO, especially when associated with atrial septal aneurysm (ASA is a risk factor for paradoxical embolism. We report a case of paradoxical embolism with stroke in an oncological patient with a huge CVC thrombus playing "ping-pong" with an hypermobile ASA with a PFO. We review the management of hypercoagulability in oncologic patients and discuss the potential role of routine transthoracic echocardiography before the implantation of long term central venous catheters to identify predisposing conditions to paradoxical embolism and select patients for anticoagulant therapy.

  8. Acromegaly With Cardiomyopathy, Cardiac Thrombus and Hemorrhagic Cerebral Infarct: A Case Report of Therapeutic Dilemma With Review of Literature (United States)

    Mendoza, Erick; Malong, Chandy Lou; Tanchee-Ngo, Mary Jane; Mercado-Asis, Leilani


    Introduction: Cardiomyopathy with congestive heart failure (CHF) is a rare complication of growth hormone (GH)-secreting pituitary adenoma occurring in 3% of cases. We report a case of acromegaly complicated not only by CHF but also by the presence of intracardiac thrombus and cardioembolic stroke with hemorrhagic formation. Case Presentation: A 46-year-old Filipino female presented with amenorrhea, progressive coarsening of facial features, deepening of voice and enlargement of digits. She experienced easy fatigability, orthopnea and bipedal edema. The cardiac apex beat was sustained and displaced. Growth hormone was nonsuppressible. Cranial magnetic resonance imaging showed pituitary macroadenoma with hemorrhage. Incidentally, there was a left frontal lobe cortical infarct with hemorrhagic component. The echocardiogram demonstrated cardiomyopathic changes with a left ventricular thrombus. Conclusions: The primary treatment for GH-producing adenoma is surgery; however, this patient has high surgical risk from her severe cardiomyopathy. Radiotherapy poses a greater risk because of increased cerebrovascular mortality. Somatostatin receptor ligands are significantly associated with improvement of cardiovascular and hemodynamic parameters. Dopamine agonists must be considered regardless of prolactin level and immunostaining. The risks and benefits of any treatment must be emphasized in the presence of conflicting clinical features such as in the case reported. PMID:25926851

  9. ST Elevation Infarction after Heart Transplantation Induced by Coronary Spasms and Mural Thrombus Detected by Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Tor Skibsted Clemmensen


    Full Text Available The case illustrates the possible link between coronary spasms, intraluminal thrombus formation, and widespread organized and layered thrombi in HTx patients. Furthermore, the case underlines the clinical value of OCT as a novel method for high-resolution vessel imaging in heart-transplanted (HTx patients with coronary spasms and suspected coronary artery disease. Coronary spasms and sudden death are frequent complications after HTx. The underlying mechanisms leading to these complications are unknown. The present case displays the clinical course of a 19-year-old HTx patient who was hospitalized due to acute myocardial infarction induced by severe coronary spasms. The patients remained unstable on conservative therapy. Therefore, an optical coherence tomography (OCT was performed and revealed massive, organized thrombi in the left main coronary artery, the circumflex coronary artery, and the left anterior descending coronary artery. The patient was stabilized after percutaneous coronary intervention. As a mural thrombus often goes undetected by coronary angiography, OCT may prove benefit in HTx patients with myocardial infarction or suspected coronary spasms.

  10. Acetic acid in aged vinegar affects molecular targets for thrombus disease management. (United States)

    Jing, Li; Yanyan, Zhang; Junfeng, Fan


    To elucidate the mechanism underlying the action of dietary vinegar on antithrombotic activity, acetic acid, the main acidic component of dietary vinegar, was used to determine antiplatelet and fibrinolytic activity. The results revealed that acetic acid significantly inhibits adenosine diphosphate (ADP)-, collagen-, thrombin-, and arachidonic acid (AA)-induced platelet aggregation. Acetic acid (2.00 mM) reduced AA-induced platelet aggregation to approximately 36.82 ± 1.31%, and vinegar (0.12 mL L(-1)) reduced the platelet aggregation induced by AA to 30.25 ± 1.34%. Further studies revealed that acetic acid exerts its effects by inhibiting cyclooxygenase-1 and the formation of thromboxane-A2. Organic acids including acetic acid, formic acid, lactic acid, citric acid, and malic acid also showed fibrinolytic activity; specifically, the fibrinolytic activity of acetic acid amounted to 1.866 IU urokinase per mL. Acetic acid exerted its fibrinolytic activity by activating plasminogen during fibrin crossing, thus leading to crosslinked fibrin degradation by the activated plasmin. These results suggest that organic acids in dietary vinegar play important roles in the prevention and cure of cardiovascular diseases.

  11. Efficacy comparison between direct stent implantation surgery and deferred stent implantation surgery for patients with ST-segment elevation myocardial infarction after PCT thrombus aspiration surgery

    Institute of Scientific and Technical Information of China (English)

    Xiao-Xia Han; Xiu-Hong Liu; Ping Zhou; Guo-Mei Dan


    Objective:To compare the efficacy of direct stent implantation surgery and deferred stent implantation surgery for patients with ST-segment elevation myocardial infarction after PCT thrombus aspiration surgery. Method:A total of 74 cases with STEMI were selected, who had been given PCT thrombus aspiration surgery treatment, and were randomly divided into direct group and deferred group (n=37). Patients in direct group were given direct stent implantation surgery after PCT thrombus aspiration surgery treatment. Patients in deferred group were given deferred stent implantation surgery 14 d later after anticoagulant and anti-platelet treatment. Heart structure and function, stent release characteristics and adverse reactions) were compared 6 months after the surgery. Results:Two hours after surgery, ST segment drop amplitude in deferred group was significantly higher than that in direct group (P<0.05);TIMI frame number was obvious and no reflow/slow blood flow occurrence ratio was significantly lower than that in direct group (P<0.05);implantation stent number and stent length in deferred group were significantly less than that in direct group (P<0.05);the release characteristic indexes of implantation stent in deferred group:stent diameter and stent expansion pressure were significantly higher than that in direct group (P<0.05);6 months after surgery, LVEF improvement in deferred group was significantly higher than that in direct group (P<0.05), while LVEDD、LVEDV ventricular remodeling was significantly lower than that in direct group (P<0.05);The total adverse event occurrence rate in deferred group was 5.4%, which was significantly lower than that in direct group (18.9%) (P<0.05). Conclusions:The deferred stent implantation surgery after PCI thrombus aspiration surgery could obviously reduce the occurrence rate of no reflow/slow blood flow, obviously improve the heart function and myocardial perfusion, reduce the usage amount of stent, reduce the occurrence of

  12. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical University Luebeck (Federal Republic of Germany). Department of Neurology); Hardeman, M.R. (Amsterdam Univ. (Netherlands). Academisch Ziekenhuis); Henningsen, H. (Heidelberg Univ. (Germany, F.R.). Neurologische Klinik); Petrovici, J.-N. (Cologne-Merheim Hospital (Federal Republic of Germany). Department of Neurology) (eds.)


    The increasing number of therapeutic modalities available for the management of patients with thromboembolic complications, such as fibrinolytic treatment or vascular surgery, require the development of new imaging techniques to provide more information on the xtent, age and activity of the thromboembolic material causing clinical symptoms. Since the introduction of radiolabelling of platelets with indium-111, platelet scintigraphy (PSC) has been used as a tool in the diagnosis of various thromboembolic diseases. During the International Symposium on Radiolabelled Platelets scientists from a variety of medical backgrounds presented their results on the clinical applictions of radiolabelled platelets. The papers presented there have been updated to take account of the latest results before publication in this volume. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection. refs.; figs.; tabs.

  13. Inhibitory Effect of ADP Receptor in Platelets on Clot Formation Assessed by Thromboelastography%血栓弹力图评价血小板ADP受体抑制率对血凝块形成的影响

    Institute of Scientific and Technical Information of China (English)

    黎金庆; 周合冰; 郭金成; 张娟; 曾惠


    目的 了解血小板ADP受体抑制率对血凝块形成的影响,及其与年龄、性别的关系.方法 联用氯吡格雷和阿司匹林的急性冠脉综合征80例,血栓弹力图测定血小板ADP受体抑制率和ADP通道的R时间、K时间、α角、MA值和TMA.结果 80例患者ADP受体抑制率为66.4±24.6%,R时间为0.7±0.4 mm,α角为54.8°±13.7°,MA值为27.1±15.0 mm,TMA为15.9±7.8 min,K时间为6.2±4.6 min(n=51).ADP受体抑制率对R时间无影响(P>0.05);随抑制率增高,a角缩小,MA值降低,TMA缩短,K时间延长并且无K时间病例增多(P<0.05).各年龄段之间、男女患者之间ADP受体抑制率比较均无差别(P>0.05).结论 抑制血小板ADP受体不利于血凝块形成,随抑制率增高,血凝块形成减慢、强度变小;抑制率大小与年龄性别无关.%Objective To study the inhibitory effect of ADP receplor in platelets on clot formation and its associalion with age and gender. Methods 80 patients with acute coronary syndrome were treated with clopidogrel (75 mg) in combination with aspirin ( 100 mg) daily. Inhibitory rate of ADP receptor in platelets were detected by thromboelastography. The following variables of ADP channel were also recorded : R time, K time ,a angle,maximum amplitude (MA) and time to MA ( TMA). Results The inhibitory rate of ADP receptor was 66. 4 ±24. 6% . The R time ,α angle , MA and TMA of ADP channel were 0. 7 ±0. 4 min ,54. 8° ± 13. 7°,27. I ± 15. 0 mm and 15. 9 ±7. 8 min , respectively. The K time was 6. 2 ±4. 6 min( n =51 ) ,with 29 cases having no K time because of MA < 20 mm. Inhibition of ADP receptor had no effect on R time( P > 0. 05).The α angle became smaller,the MA decreased .and the TMA became shorter with the increasing ADP receptor inhibition rate (P <0. 05) . The number of cases having no K time was increased when the K time became longer. Comparison of inhibition rate between different age group, between male and female was not significant

  14. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets. (United States)

    Etulain, Julia; Negrotto, Soledad; Carestia, Agostina; Pozner, Roberto Gabriel; Romaniuk, María Albertina; D'Atri, Lina Paola; Klement, Giannoula Lakka; Schattner, Mirta


    Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.

  15. Platelet preservation: agitation and containers. (United States)

    van der Meer, Pieter F; de Korte, Dirk


    For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted.

  16. Usefulness of Thrombus Aspiration for the Treatment of Coronary Stent Thrombosis

    NARCIS (Netherlands)

    Mahmoud, Karim D.; Vlaar, Pieter J.; van den Heuvel, Ad F. M.; Hillege, Hans L.; Zijlstra, Felix; de Smet, Bart J. G. L.


    Current treatment for coronary stent thrombosis (ST) often lacks satisfactory results and clinical outcome is poor. We investigated the impact of manual thrombus aspiration during percutaneous coronary intervention (PCI) on myocardial reperfusion and clinical outcome in patients with angiographicall

  17. The influence of neck thrombus on clinical outcome and aneurysm morphology after endovascular aneurysm repair

    NARCIS (Netherlands)

    Goncalves, Frederico Bastos; Verhagen, Hence J. M.; Chinsakchai, Khamin; van Keulen, Jasper W.; Voute, Michiel T.; Zandvoort, Herman J.; Moll, Frans L.; van Herwaarden, Joost A.


    Objective: This study investigated the influence of significant aneurysm neck thrombus in clinical and morphologic outcomes after endovascular aneurysm repair (EVAR). Methods: The patient population was derived from a prospective EVAR database from two university institutions in The Netherlands from

  18. Thrombus Size is Associated with Etiology of Deep Venous Thrombosis – A Cross-Sectional Study



    The aim of this study was to evaluate the impact of risk factors for deep vein thrombosis (DVT) on thrombus sizes in lower extremities. The size and extent of thrombus was scored according to International Consensus Committee for venous disease classification. After the diagnosis of DVT was established and its size scored, predominant risk factors for DVT in each patient were identified (malignant disease, thrombophilia, postoperative state, hormonal therapy, heredity, limb trauma, immobiliza...

  19. Huge ascending aortic aneurysm with an intraluminal thrombus in an embolic event-free patient. (United States)

    Parato, Vito Maurizio; Prifti, Edvin; Pezzuoli, Franco; Labanti, Benedetto; Baboci, Arben


    We present a case of an 87-year-old male patient with a huge ascending aortic aneurysm, filled by a huge thrombus most probably due to previous dissection. This finding was detected by two-dimensional transthoracic echocardiography and contrast-enhanced computed tomography (CT) angiography scan. The patient refused surgical treatment and was medically treated. Despite the huge and mobile intraluminal thrombus, the patient remained embolic event-free up to 6 years later, and this makes the case unique.

  20. A rare case of tricuspid valve thrombus with acute pulmonary embolism

    Institute of Scientific and Technical Information of China (English)

    GUO Chun-yan; TENG Ying-xing; YANG Chuan-rui; SHEN Lu-hua; GU Fu-sheng; LI Hong-wei


    The development of thrombus on the tricuspid valve is very rare.This report describes a case of acute pulmonary embolism (PE) with a mass on the tricuspid valve in a normal heart,detected by bedside transthoracic echocardiography (TTE).After successful surgical management,the histopathological examination revealed the mass from the tricuspid valve to be mixed thrombus.The early use of bedside TrE can facilitate the prompt diagnosis and aggressive therapy when PE is suspected.

  1. Role of reactive nitrogen species in blood platelet functions. (United States)

    Olas, Beata; Wachowicz, Barbara


    Blood platelets, in analogy to other circulating blood cells, can generate reactive oxygen/nitrogen species (ROS/RNS) that may behave as second messengers and may regulate platelet functions. Accumulating evidence suggest a role of ROS/RNS in platelet activation. On the other hand, an increased production of ROS/RNS causes oxidative stress, and thus, may contribute to the development of different diseases, including vascular complications, inflammatory and psychiatric illnesses. Oxidative stress in platelets leads to chemical changes in a wide range of their components, and platelet proteins may be initial targets of ROS/RNS action. It has been demonstrated that reaction of proteins with ROS/RNS results in the oxidation and nitration of some amino acid residues, formation of aggregates or fragmentation of proteins. In oxidized proteins new carbonyl groups and protein hydroperoxides are also formed. In platelets, low molecular weight thiols such as glutathione (GSH), cysteine and cysteinylglycine and protein thiols may be also target for ROS/RNS action. This review describes the chemical structure and biological activities of reactive nitrogen species, mainly nitric oxide ((*)NO) and peroxynitrite (ONOO(-)) and their effects on blood platelet functions, and the mechanisms involved in their action on platelets.

  2. Biochemical lesions of platelets stored as concentrates in PVC bags. (United States)

    Krishnan, L K; Mathai, J; Sulochana, P V; Jacob, J; Sivakumar, R


    Acid-base status of platelet suspension during storage is a measure of the gas permeability of the bag material. To assess the efficacy of the bags available in our market to store platelets, we compared biochemical lesions of platelets stored in an Indian polyvinyl chloride (PVC) triple bag against a Japanese PVC bag standardized for 5 days platelet storage. Platelet concentrates prepared in both control and test PVC bags were stored for 72 h. Two ml samples were drawn 1 h after preparation, and then at 24 h intervals, for analysis. Our data show that the mean pH value in the test bags was maintained above 6.5. However, the CO2 tension was high and O2 tension was low. We also analyzed malondialdehyde (MDA) formation which is a measure of arachidonic acid metabolism, and seemed to be unaffected in stored platelets. Lactate dehydrogenase (LDH) was not released into the plasma excessively and hence significant platelet lysis was absent during storage. Hypotonic shock response (HSR) of platelets stored in both test and control bags was comparable, indicating the possibility of satisfactory post-transfusion recovery.

  3. Optical coherence tomography assessment and quantification of intracoronary thrombus: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Italo, E-mail: [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy); Mattesini, Alessio; Valente, Serafina [Interventional Cardiology Unit, Careggi Hospital, Florence (Italy); Prati, Francesco [Interventional Cardiology San Giovanni Hospital, Rome (Italy); CLI foundation (Italy); Crea, Filippo [Department of Cardiovascular Sciences, Catholic University of the Sacred Heart, Rome (Italy); Bolognese, Leonardo [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy)


    Coronary angiography is the “golden standard” imaging technique in interventional cardiology and it is still widely used to guide interventions. A major drawback of this technique, however, is that it is inaccurate in the evaluation and quantification of intracoronary thrombus burden, a critical prognosticator and predictor of intraprocedural complications in acute coronary syndromes. The introduction of optical coherence tomography (OCT) holds the promise of overcoming this important limitation, as near-infrared light is uniquely sensitive to hemoglobin, the pigment of red blood cells trapped in the thrombus. This narrative review will focus on the use of OCT for the assessment, evaluation and quantification of intracoronary thrombosis. - Highlights: • Thrombotic burden in acute coronary syndromes Is not adequately evaluated by standard coronary angiography, whereas Optical Coherence Tomography is exquisitely sensitive to the hemoglobin contained in red blood cells and can be used to precisely quantify thrombus. • Both research and clinical applications have been developed using the OCT-based evaluation of thrombus. In particular, whereas precise quantification scores are useful for comparing antithrombotic therapies in randomized trials, both pharmacological and mechanical, the most important practical applications for OCT-based assessment of thrombus are the individuation of culprit lesions in the context of diffuse atheromata in acute coronary syndromes, and the so-called “delayed stenting” strategies. • Improvements in 3D rendering techniques are on the verge of revolutionizing OCT-based thrombus assessment, allowing extremely precise quantification of the thrombotic burden.

  4. Mechanobiology of Platelets: Techniques to Study the Role of Fluid Flow and Platelet Retraction Forces at the Micro- and Nano-Scale

    Directory of Open Access Journals (Sweden)

    Nathan J. Sniadecki


    Full Text Available Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.

  5. Mechanobiology of platelets: techniques to study the role of fluid flow and platelet retraction forces at the micro- and nano-scale. (United States)

    Feghhi, Shirin; Sniadecki, Nathan J


    Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.

  6. A case of atypical Kawasaki disease with giant coronary artery aneurysm containing thrombus. (United States)

    Micallef, Eynaud S; Attard, Montalto S; Grech, V


    Kawasaki disease (KD) is an acute febrile, systemic vasculitic syndrome of unknown etiology, occurring primarily in children younger than 5 years of age. Administration of IVIG within the first 10 days after onset of fever in combination with high dose aspirin reduces the risk of coronary artery damage in KD. Though rare, giant aneurysms of the coronary arteries may develop in untreated cases and prove extremely challenging to manage. A 9-month-old Caucasian boy presented to our paediatric emergency department with a 4-week history of intermittent pyrexia and irritability. Typical mucocutaneous signs of Kawasaki Disease were absent upon presentation. A trans-thoracic echocardiogram identified a giant aneurysm of the left anterior descending artery with thrombus formation in-situ and the child was managed with intravenous immunoglobulin, steroids, high dose aspirin therapy and later warfarinisation. Cardiovascular sequelae of Kawasaki disease include giant coronary artery aneurysms with thrombosis. Enlargement of a coronary aneurysm after the acute phase of Kawasaki disease is uncommon and the outcome of interventional approaches poorly studied.

  7. The Platelet and Platelet Function Testing in Liver Disease

    NARCIS (Netherlands)

    Hugenholtz, Greg G. C.; Porte, Robert J.; Lisman, Ton


    Patients who have liver disease commonly present with alterations in platelet number and function. Recent data have questioned the contribution of these changes to bleeding complications in these patients. Modern tests of platelet function revealed compensatory mechanisms for the decreased platelet

  8. Investigation of platelet function and platelet disorders using flow cytometry. (United States)

    Rubak, Peter; Nissen, Peter H; Kristensen, Steen D; Hvas, Anne-Mette


    Patients with thrombocytopenia or platelet disorders are at risk of severe bleeding. We report the development and validation of flow cytometry assays to diagnose platelet disorders and to assess platelet function independently of platelet count. The assays were developed to measure glycoprotein levels (panel 1) and platelet function (panel 2) in sodium citrated blood. Twenty healthy volunteers and five patients diagnosed with different platelet disorders were included. Glycoprotein expression levels of the receptors Ia, Ib, IIb, IIIa and IX were measured and normalised with forward scatter (FS) as a measurement of platelet size. Platelet function was assessed by CD63, P-selectin and bound fibrinogen in response to arachidonic acid, adenosine diphosphate (ADP), collagen-related peptide, ristocetin and thrombin receptor-activation peptide-6. All patients except one with suspected δ-granule defect showed aberrant levels of glycoproteins in panel 1. Glanzmann's thrombasthenia and genetically verified Bernard-Soulier syndrome could be diagnosed using panel 1. All patients showed reduced platelet function according to at least one agonist. Using panel 2 it was possible to diagnose Bernard-Soulier syndrome, δ-granule defect and GPVI disorder. By combining the two assays, we were able to diagnose different platelet disorders and investigate platelet function independent of platelet count.

  9. Reproducibility of Manual Platelet Estimation Following Automated Low Platelet Counts

    Directory of Open Access Journals (Sweden)

    Zainab S Al-Hosni


    Full Text Available Objectives: Manual platelet estimation is one of the methods used when automated platelet estimates are very low. However, the reproducibility of manual platelet estimation has not been adequately studied. We sought to assess the reproducibility of manual platelet estimation following automated low platelet counts and to evaluate the impact of the level of experience of the person counting on the reproducibility of manual platelet estimates. Methods: In this cross-sectional study, peripheral blood films of patients with platelet counts less than 100 × 109/L were retrieved and given to four raters to perform manual platelet estimation independently using a predefined method (average of platelet counts in 10 fields using 100× objective multiplied by 20. Data were analyzed using intraclass correlation coefficient (ICC as a method of reproducibility assessment. Results: The ICC across the four raters was 0.840, indicating excellent agreement. The median difference of the two most experienced raters was 0 (range: -64 to 78. The level of platelet estimate by the least-experienced rater predicted the disagreement (p = 0.037. When assessing the difference between pairs of raters, there was no significant difference in the ICC (p = 0.420. Conclusions: The agreement between different raters using manual platelet estimation was excellent. Further confirmation is necessary, with a prospective study using a gold standard method of platelet counts.

  10. Emerging Evidence for Platelets as Immune and Inflammatory Effector Cells

    Directory of Open Access Journals (Sweden)

    Matthew Thomas Rondina


    Full Text Available While traditionally recognized for their roles in hemostatic pathways, emerging evidence demonstrates that platelets have previously unrecognized, dynamic roles that span the immune continuum. These newly-recognized platelet functions, including the secretion of immune mediators, interactions with endothelial cells, monocytes, and neutrophils, toll-like receptor (TLR mediated responses, and induction of neutrophil extracellular trap (NET formation, bridge thrombotic and inflammatory pathways and contribute to host defense mechanisms against invading pathogens. In this focused review, we highlight several of these emerging aspects of platelet biology and their implications in clinical infectious syndromes.

  11. Platelet binding to monocytes increases the adhesive properties of monocytes by up-regulating the expression and functionality of beta(1) and B-2 integrins

    NARCIS (Netherlands)

    P.A.D.C. Martins; J.M. van Gils; A. Mol; P.L. Hordijk; J.J. Zwaginga


    Human monocytes adhere to activated platelets, resulting in the formation of platelet-monocyte complexes (PMC). Complex formation depends on the interaction between platelet-displayed P-selectin and the specific ligand for P-selectin on leukocytes, P-selectin glycoprotein ligand-1 (PSGL-1). We have

  12. Effects of local application of platelet-rich plasma and guided tissue regeneration on stability of implants


    Duka Miloš; Lazić Z.; Bubalo Marija; Tatić Z.; Đurđević D.; Matić Smiljana


    Osseointegration is a result of cellular migration, differentiation, bone formation, and bone remodelling on the surface of an implant. Each of these processes depends on platelets and blood coagulum. Platelet-rich plasma (PRP) is used to improve osseointegration and stability of implants. It is a blood fraction produced in a centrifuge which contains a high concentration of platelets. Platelets contain numerous growth factors which influence tissue reactions. The aim of the research is to te...

  13. Glycoprotein IIb/IIIa and P2Y12 Induction by Oligochitosan Accelerates Platelet Aggregation (United States)

    Halim, Ahmad Sukari; Hussein, Abdul Rahim; Ujang, Zanariah


    Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro. PMID:25247182

  14. Mean platelet volume and mean platelet volume/platelet count ratio ...

    African Journals Online (AJOL)

    Amira M. Elsayed


    Mar 30, 2016 ... Abstract The mean platelet volume (MPV) is a laboratory marker associated with platelet func- tion and activity. .... the first 24 h of presentation to the emergency department. Severity of ..... J Neurol Neurosurg Psychiatry.

  15. Glatiramer acetate (copaxone modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation.

    Directory of Open Access Journals (Sweden)

    Sarah C Starossom

    Full Text Available BACKGROUND: Glatiramer acetate (GA, Copaxone, Copolymer-1 is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE, an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets. CONCLUSIONS: GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.

  16. The biology of the platelet with special reference to inflammation, wound healing and immunity. (United States)

    Nurden, Alan T


    While platelets have long been known to be essential for maintaining hemostasis in the vasculature, their role in tissue repair, inflammation and innate and adaptive immunity is a more recent science. The ability of platelets to attach to the vessel wall, form aggregates and promote fibrin formation, key elements of blood clotting, has been said to both favor and dampen inflammation, to fight infection and to assure an adequate immune response. To fulfill their different roles platelets often synchronize with leukocytes and cells of the immune system. But just as the molecular pathways of platelets in preventing blood loss can lead to arterial thrombosis and stroke if occurring in an uncontrolled manner, the failure to control inflammation can lead to sepsis and inadequate platelet function and can aggravate many major illnesses. This review is aimed to present a global picture of multifaceted platelet biology and platelet involvement in selected non-hemostatic events.

  17. Detection of thrombus size and protein content by ex vivo magnetization transfer and diffusion weighted MRI

    Directory of Open Access Journals (Sweden)

    Phinikaridou Alkystis


    Full Text Available Abstract Background To utilize a rabbit model of plaque disruption to assess the accuracy of different magnetic resonance sequences [T1-weighted (T1W, T2-weighted (T2W, magnetization transfer (MT and diffusion weighting (DW] at 11.7 T for the ex vivo detection of size and composition of thrombus associated with disrupted plaques. Methods Atherosclerosis was induced in the aorta of male New Zealand White rabbits (n = 17 by endothelial denudation and high-cholesterol diet. Subsequently, plaque disruption was induced by pharmacological triggering. Segments of infra-renal aorta were excised fixed in formalin and examined by ex vivo magnetic resonance imaging (MRI at 11.7 T and histology. Results MRI at 11.7 T showed that: (i magnetization transfer contrast (MTC and diffusion weighted images (DWI detected thrombus with higher sensitivity compared to T1W and T2W images [sensitivity: MTC = 88.2%, DWI = 76.5%, T1W = 66.6% and T2W = 43.7%, P P (ii MTC and DWI provided a more accurate detection of thrombus area with histology as the gold-standard [underestimation of 6% (MTC and 17.6% (DWI compared to an overestimation of thrombus area of 53.7% and 46.4% on T1W and T2W images, respectively]; (iii the percent magnetization transfer rate (MTR correlated with the fibrin (r = 0.73, P = 0.003 and collagen (r = 0.9, P = 0.004 content of the thrombus. Conclusions The conspicuity of the thrombus was increased on MTC and DW compared to T1W and T2W images. Changes in the %MTR and apparent diffusion coefficient can be used to identify the organization stage of the thrombus.

  18. Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke.

    Directory of Open Access Journals (Sweden)

    Emilie M M Santos

    Full Text Available Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and time consuming task. Our aim was to develop an automated method for thrombus measurement on CT angiography and validate it against manual delineation.Automated thrombus segmentation was achieved using image intensity and a vascular shape prior derived from the segmentation of the contralateral artery. In 53 patients with acute ischemic stroke due to proximal intracranial arterial occlusion, automated length and volume measurements were performed. Accuracy was assessed by comparison with inter-observer variation of manual delineations using intraclass correlation coefficients and Bland-Altman analyses.The automated method successfully segmented the thrombus for all 53 patients. The intraclass correlation of automated and manual length and volume measurements were 0.89 and 0.84. Bland-Altman analyses yielded a bias (limits of agreement of -0.4 (-8.8, 7.7 mm and 8 (-126, 141 mm3 for length and volume, respectively. This was comparable to the best interobserver agreement, with an intraclass correlation coefficients of 0.90 and 0.85 and a bias (limits of agreement of -0.1 (-11.2, 10.9 mm and -17 (-216, 185 mm3.The method facilitates automated thrombus segmentation for accurate length and volume measurements, is relatively fast and requires minimal user input, while being insensitive to high hematocrit levels and vascular calcifications. Furthermore, it has the potential to assess thrombus characteristics of low-density thrombi.

  19. Surgical management of renal cell carcinoma with inferior vena caval thrombus: A teaching hospital experience

    Directory of Open Access Journals (Sweden)

    Kulkarni Jagdeesh


    Full Text Available Purpose: To evaluate the outcome of patients of renal cell carcinoma (RCC with inferior vena caval (IVC thrombus treated by radical nephrectomy and IVC thrombectomy in terms of clinical and pathological factors and prognosis. Materials and Methods: Sixty-three consecutive patients of RCC with IVC thrombus who underwent radical nephrectomy with IVC thrombectomy between June 1993 and May 2003 were included in this retrospective analysis. Data was analyzed in terms of clinical factors, such as level of thrombus, and pathological factors, such as grade, local invasion and N status. Results: Tumor thrombus level was infrahepatic in 35 patients, retrohepatic in 20 and suprahepatic in 8, including 5 with right atrial thrombus. The immediate post-operative mortality was 3%, and the incidence of major post-operative complications was 34%, but most of them improved after conservative management except one who needed surgery for burst abdomen. The disease free survival (DFS was 48.5%, 50.6%, 66.6% and 40% for infrahepatic, retrohepatic, suprahepatic and intra-atrial tumors, respectively. Of the histological types, patients with clear cell tumors had the best prognosis; those with granular cell had the worst prognosis (DFS of 53.5% vs 33.3%, though statistically not significant. Grade-2 tumors had better prognosis than grade-4 tumors (DFS 66.6% vs 0%, P < 0.001. Sixty-eight percent of patients without perinephric fat invasion were free of disease as compared to 31% of those with perinephric fat invasion (P < 0.01. Further, N status showed DFS of 60.9% in patients with negative nodes and 30% in patients with positive nodes (P < 0.05. Conclusion: Though surgery for RCC with IVC thrombus has high morbidity, it can give good results in terms of prolonged DFS in expert hands. Regarding long-term survival, pathological factors, such as local stage and grade, are more important than clinical factors, such as level of thrombus.

  20. Shock-wave thrombus ablation, a new method for noninvasive mechanical thrombolysis. (United States)

    Rosenschein, U; Yakubov, S J; Guberinich, D; Bach, D S; Sonda, P L; Abrams, G D; Topol, E J


    Successful experimental and clinical experience with thrombus ablation has been attained with high-power acoustic energy delivered in a catheter. The goal of this study was to investigate the feasibility of noninvasive thrombus ablation by focused high-power acoustic energy. The source for high-power acoustic energy was a shock-wave generator in a water tank equipped with an acoustic lens with a fixed focal point at 22.5 cm. Thrombus was prepared in vitro, weighed (0.24 +/- 0.08 g), and inserted in excised human femoral artery segments. The arterial segments wer ligated, positioned at the focal point and then randomized into either test (n = 8) or control (n = 7). An x-ray system verified the 3-dimensional positioning of the arterial segment at the focal point. A 5 MHz ultrasound imaging system continuously visualized the arterial segment at the focal point before, during and after each experiment. The test segments were exposed to shock waves (1,000 shocks/24 kv). The arterial segment content was then flushed and the residual thrombus weighed. The arterial segment and thrombus were fixed and submitted to histologic examination. The test group achieved a significant ablation of thrombus mass (0.25 +/- 0.15 vs 0.07 +/- 0.003 g; p = 0.0001) after application of shock waves. Arterial segments showed no gross or microscopic damage. Ultrasound imaging revealed a localized (1.9 +/- 0.5 cm2), transient (744 +/- 733 ms), cavitation field at the focal point at the time of application of focused shock waves. Thus, focused high-power acoustic energy can effect noninvasive thrombus ablation without apparent damage to the arterial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Actively induced platelet-bound IgG associated with thrombocytopenia in the marmoset

    Energy Technology Data Exchange (ETDEWEB)

    Gengozian, N.; McLaughlin, C.L.


    Interspecies platelet immunizations among marmosets lead to antibody formation to the donor platelets and a profound thrombocytopenia, which when associated with anemia may result in death of the animal. This actively induced immonologic thrombocytopenia closely resembles two clinical disease entities manifesting autoimmune thrombocytopenia, posttransfusion purpura and idiopathic thrombocytopenic purpura. Although antibody to donor-type platelets could be demonstrated readily, antihost activity was most often nondetectable or, when present, was in very low titer. A consistent finding was the appearance of IgG on the host's platelets shortly after immunization and concomitant with the appearance of antidonor platelet antibody. In 3 of 13 immunized animals thromoocytopenia did not occur even though antibody was formed and the host's platelets became IgG positive. In those animals that recovered from the induced thrombocytopenia IgG-positive platelets were found for periods ranging from 30 to greater than 100 days. Splenectomy before or after immunization did not alter the sequential development of antibody formation, appearance of IgG-positive platelets, and thrombocytopenia. Eluates prepared from IgG-positive platelets contained IgG and platelet antigens; the eluted IgG could attach nonspecifically to platelets of host or donor (immunizing) type, in contrast to the species specificity demonstrated for IgG eluted from platelets that had been reacted in vitro with specific antibody. Platelets in a few normal, nonimmunized marmosets were found to have signficant amounts of IgG on their surface, comparable to that observed in the immunized animal; interestingly, such IgG-positive platelets were found among imported but not laboratory-bred marmosets.


    Directory of Open Access Journals (Sweden)

    Aji Kristianto Wijaya


    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Stroke is one of the most common cause of death worldwide and the third leading cause of death in the United States. Stroke composed 90,000 deaths of women and 60,000 men each year. In Indonesia, 8 of 1000 people suffered a stroke. Stroke is divided into two, non-hemorrhagic stroke and hemorrhagic stroke. Most of them (80% is non-hemorrhagic stroke. Non-hemorrhagic stroke can be caused by thrombi or emboli. Understanding the pathophysiology of non-hemorrhagic stroke caused by a thrombus is very important in regard with providing appropriate patient management. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  3. Prophylactic platelets in dengue

    DEFF Research Database (Denmark)

    Whitehorn, James; Rodriguez Roche, Rosmari; Guzman, Maria G


    of platelets in dengue. Respondents were all physicians involved with the treatment of patients with dengue. Respondents were asked that their answers reflected what they would do if they were the treating physician. We received responses from 306 physicians from 20 different countries. The heterogeneity...

  4. Platelets in leucocyte recruitment and function. (United States)

    Rossaint, Jan; Zarbock, Alexander


    Platelets have a longstanding recognition as an essential cellular component of the coagulation system. However, substantial research over the last decade has added another important aspect to platelet function in that they are also an integral part of the innate immune system. Complex organisms are facing a constant threat of infections by invading pathogens, and they have developed a sophisticated and elegant measure to combat this threat, namely the immune system. Leucocyte recruitment to sites of infections is an essential step at the forefront of the immune response. Platelets have been shown to be involved in several steps of this process and they are an integrated connecting element among haemostasis, host defence, and additional immunological functions (e.g. neutrophil extracellular traps formation). However, the immune system also requires a tight regulation, as an overshooting immune response carries the risk of harming the host itself. This review aims at highlighting the unique features and molecular mechanisms that allow for the interactions of platelets and leucocytes and the regulation of this process. Furthermore, this article identifies the functional relevance of these events for the immune response.

  5. Resectable hepatoblastoma with tumor thrombus extending into the right atrium after chemotherapy: A case report

    Directory of Open Access Journals (Sweden)

    Kosuke Endo


    Full Text Available Hepatoblastoma with intraatrial tumor thrombus is relatively rare. We report a case of hepatoblastoma with tumor thrombus extending into the right atrium, which responded well to chemotherapy and was resected using extracorporeal circulation. A 4-year-old girl was referred to our hospital because of abdominal distention and tenderness. A computed tomography (CT scan showed a large tumor occupying the left 3 segments of the liver with tumor thrombus extending into the right atrium. There was also a small intrahepatic metastasis in the right lobe of the liver. She was diagnosed with hepatoblastoma on the basis of the results of open biopsy. Neoadjuvant chemotherapy with an intense CDDP-based regimen was performed. The tumor responded well to chemotherapy, and intrahepatic metastasis became undetectable on CT scan, although the tumor thrombus remained in the right atrium. After 7 courses of chemotherapy, we performed resection using extracorporeal circulation. The postoperative course was uneventful, and adjuvant chemotherapy was started 10 days after the operation. Her serum alpha-fetoprotein (AFP level decreased to the normal range, and she was free of disease for 1 year after the operation. Tumor resection using extracorporeal circulation can be performed safely and is justified in patients with intraatrial tumor thrombus.

  6. CT guided 125iodine seed implantation for portal vein tumor thrombus in primary hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fu-jun; LI Chuan-xing; JIAO De-chao; ZHANG Nian-hua; WU Pei-hong; DUAN Guang-feng; WU Yue-xia


    Background This study evaluated the clinical application of CT guided 125iodine implantation in patients with portal vein tumor thrombus in primary hepatocellular carcinoma.Methods The ten patients (9 males and 1 female,aged from 36 to 72 years) with portal vein tumor thrombus accompanying hepatocellular carcinoma had been treated with comprehensive therapy including surgery,transcatheter arterial chemoembolization,radiotherapy ablation,microwave ablation or percutaneous ethanol injection.The average diameter of each tumor thrombus was 21.5 mm×30.5 mm.Seeds of 30 MBq 125I were implanted 5 mm apart within the portal vein tumor thrombus.The follow-up after 4 months included enhanced spiral CT.Results CT screening of the tumours indicated that 4 out of 10 patients showed complete response to the therapy,5 partial response and 1 stable disease.Adverse effects included aggravated abdominal dropsy and temporarily increased transaminase,which were controlled by medical management.Severe complications such as haemorrhage,biliary fistula,hepatic abscess,pancreatic fistula and hepatic function failure were not observed.Implanted seeds migrated to lung and left hepatic lobe in 1 case.Conclusion CT guided implantation of 125iodine seeds,can effectively treat portal vein tumor thrombus accompanying hepatocellular carcinoma with minimal damage and few complications.

  7. Common Carotid Artery Stump Syndrome Due to Mobile Thrombus Detected by Carotid Duplex Ultrasonography. (United States)

    Omoto, Shusaku; Hasegawa, Yuki; Sakai, Kenichiro; Matsuno, Hiromasa; Arai, Ayumi; Terasawa, Yuka; Mitsumura, Hidetaka; Iguchi, Yasuyuki


    Carotid stump syndrome is a cause of recurrent embolic stroke following occlusion of the ipsilateral internal carotid artery. The present report describes a case of recurrent cerebral embolism ipsilateral to a chronically occluded left common carotid artery (CCA), i.e., "CCA stump syndrome." Doppler color flow imaging showed anterograde flow in the left internal and external carotid arteries, which were supplied by collateral flow from the superior thyroid artery inflowing just proximal to the left carotid bifurcation. According to carotid duplex ultrasonography (CDU), a low-echoic mobile thrombus was noted at the distal stump of the occluded CCA, which presumably caused distal embolism. The low-echoic mobile thrombus dramatically changed to a homogenously high-echoic thrombus, and there was no recurrence of stroke after antiplatelet and anticoagulant therapy. This is the first report to demonstrate a CDU-verified temporal change in the thrombus at the stump in CCA stump syndrome. CDU is a noninvasive and useful technique to characterize hemodynamics, thrombus morphology, and the response to therapy.

  8. Towards tailored antiplatelet therapy in vascular disease

    NARCIS (Netherlands)

    Leunissen, TC


    Inhibition of platelet activation, aggregation and consequent thrombus formation is an essential target in primary and secondary prevention for secondary cardiovascular events (CVE). Although stronger platelet inhibitory therapy has been developed, there are still individual patients who develop a

  9. IκB kinase phosphorylation of SNAP-23 controls platelet secretion. (United States)

    Karim, Zubair A; Zhang, Jinchao; Banerjee, Meenakshi; Chicka, Michael C; Al Hawas, Rania; Hamilton, Tara R; Roche, Paul A; Whiteheart, Sidney W


    Platelet secretion plays a key role in thrombosis, thus the platelet secretory machinery offers a unique target to modulate hemostasis. We report the regulation of platelet secretion via phosphorylation of SNAP-23 at Ser95. Phosphorylation of this t-soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) occurs upon activation of known elements of the platelet signaling cascades (ie, phospholipase C, [Ca(2+)]i, protein kinase C) and requires IκB kinase (IKK)-β. Other elements of the nuclear factor κB/IκB cascade (ie, IKK-α,-β,-γ/NEMO and CARMA/MALT1/Bcl10 complex) are present in anucleate platelets and IκB is phosphorylated upon activation, suggesting that this pathway is active in platelets and implying a nongenomic role for IKK. Inhibition of IKK-β, either pharmacologically (with BMS-345541, BAY11-7082, or TPCA-1) or by genetic manipulation (platelet factor 4 Cre:IKK-β(flox/flox)), blocked SNAP-23 phosphorylation, platelet secretion, and SNARE complex formation; but, had no effect on platelet morphology or other metrics of platelet activation. Consistently, SNAP-23 phosphorylation enhanced membrane fusion of SNARE-containing proteoliposomes. In vivo studies with IKK inhibitors or platelet-specific IKK-β knockout mice showed that blocking IKK-β activity significantly prolonged tail bleeding times, suggesting that currently available IKK inhibitors may affect hemostasis.

  10. Evaluation of electrical aggregometry: comparison with optical aggregometry, secretion of ATP, and accumulation of radiolabeled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Ingerman-Wojenski, C.; Smith, J.B.; Silver, M.J.


    Platelet aggregation has been most commonly studied in vitro by measuring increases in light transmission as platelets aggregate in PRP (platelet-rich plasma). Recently, an electrical impedance method for measuring platelet aggregation has been introduced. This method can be used with either PRP or whole blood and measures an increase in impedance across electrodes placed in the blood samples as platelets accumulate on them. Results obtained by the two methods were compared using ADP and collagen as aggregating agents, and also have measured the secretion of platelet ATP simultaneously. Although the aggregometry results were similar, recordings obtained by the electrical method did not distinguish two waves of platelet aggregation or correlate with secretion as well as recordings obtained by the optical method. When PGI/sub 2/ (prostacyclin) or PGE/sub 1/ (prostaglandin E/sub 1/) was added to the PRP, both the rate and extent of the increase in light transmittance were inhibited, but the main effect on the increase in impedance was a decrease in its rate and not in its extent. Increases in impedance and secretion of ATP were also measured in whole blood after the platelets had been labeled with a /sup 125/I-containing antibody specific for platelet surface glycoproteins. It appeared that the increases in impedance lagged several minutes behind the formation of platelet aggregates and the secretion of platelet ATP.

  11. In vitro effects of ethanol on the pathways of platelet aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Rand, M.L.; Kinlough-Rathbone, R.L.; Packham, M.A.; Mustard, J.F.


    Ethanol is reported to inhibit platelet aggregation in vivo and in vitro, but the mechanisms of its action on stimulus-response coupling in platelets is unknown. Platelet aggregation to thrombin occurs through at least three pathways: released ADP; thromboxane A/sub 2/ (TXA/sub 2/); and a third pathway(s). Aggregation of rabbit platelets in citrated platelet-rich plasma (PRP) or washed suspensions to ADP (0.5-10 was not affected by ethanol, at concentrations up to 5 mg/ml (lethal). Primary ADP-induced (5 aggregation of human platelets in PRP was also unaffected by ethanol, but secondary aggregation and release of /sup 14/C-serotonin, due to TXA/sub 2/ formation, was inhibited by ethanol (2 and 4 mg/ml). Since arachidonate (AA)-induced (25-250 aggregation and release by washed rabbit platelets was unaltered by ethanol, it may inhibit mobilization of AA from platelet membrane phospholipids. Ethanol (2-4 mg/ml) inhibited rabbit platelet aggregation and release to low concentrations of thrombin (< 10 mU/ml) or collagen, and also inhibited aggregation and release of aspirin-treated (500 M) rabbit platelets (that cannot form TXA/sub 2/) to low concentrations of thrombin (< 10 mU/ml). Thus, ethanol does not inhibit the mobilization of AA, and partially inhibits the third pathway(s) of platelet aggregation.

  12. A mathematical model for in vitro coagulation of blood: role of platelet count and inhibition

    Indian Academy of Sciences (India)



    A mechanistic model including the role of platelets is proposed for clot formation and growth in plasma in vitro. Initiation of clot formation is by the addition of tissue factor, and initiation via the intrinsic pathway is neglected. Activation of zymogens follows the extrinsic pathway cascade and reactions on platelet membranes are included. Platelet activation occurs due to thrombin and also due to other activated platelets.Inhibition of the active clotting factors is by ATIII and TFPI, whereas inhibition due to APC is not relevant in the conditions modeled. The model predictions matched existing data for thrombin production in synthetic plasma. The model predicts that inhibition of platelet-driven activation of platelets has a major effect on concentration of activated platelets in PRP, normal plasma and PPP. Inhibition of platelet activation by (other activated) platelets significantly delays thrombin production in PRP and normal plasma as compared to that by thrombin. Further, sensitivity analysis shows that the model is most sensitive to the activation of platelet membrane-bound factor X by the intrinsic tenase complex.

  13. Platelet immune complex interaction in pathogenesis of Kawasaki disease and childhood polyarteritis.


    Levin, M; Holland, P C; Nokes, T J; Novelli, V; Mola, M; Levinsky, R J; Dillon, M J; Barratt, T M; Marshall, W C


    The role of platelets in the pathogenesis of vasculitis and the formation of coronary artery aneurysms was studied in 19 children with Kawasaki disease and five with polyarteritis. All patients with Kawasaki disease developed thrombocytosis in the third week of illness. The peak platelet count was significantly correlated (p less than 0.005) with the subsequent development of coronary artery aneurysms. The rise in platelet count was associated with the appearance in the circulation of a facto...

  14. The effect of platelet releasate on wound healing in animal models. (United States)

    Ksander, G A; Sawamura, S J; Ogawa, Y; Sundsmo, J; McPherson, J M


    The alpha granules of platelets contain growth factors that are important in wound healing. We found that a major effect of thrombin-induced human platelet releasates in animal models of wound healing is to enhance the development of granulation tissue and new connective tissue matrix. These studies provide further evidence that platelet-derived protein factors may be useful in treating full-thickness dermal wounds by increasing the rate of granulation tissue formation.

  15. Expansion of the neonatal platelet mass is achieved via an extension of platelet lifespan


    Liu, Zhi-Jian; Hoffmeister, Karin M.; Hu, Zhongbo; Mager, Donald E.; Ait-Oudhia, Sihem; Debrincat, Marlyse A.; Pleines, Irina; Josefsson, Emma C.; Benjamin T Kile; Italiano, Joseph; Ramsey, Haley; Grozovsky, Renata; Veng-Pedersen, Peter; Chavda, Chaitanya; Sola-Visner, Martha


    Rapid growth and rising platelet counts result in a significant expansion of platelet mass during neonatal life.The rise in platelet counts is mediated by a prolongation in the neonatal platelet lifespan.

  16. Synthetic thrombus model for in-vitro studies of laser thrombolysis (United States)

    Hermes, Robert E.; Trajkovska, Keti


    Laser thrombolysis is the controlled ablation of a thrombus (blood clot) blockage in a living arterial system. Theoretical modeling of the interaction of laser light with thrombi relies on the ability to perform in vitro experiments with well characterized surrogate materials. A synthetic thrombus formulation may offer more accurate results when compared to in vivo clinical experiments. We describe here the development of new surrogate materials based on formulations incorporating chicken egg, guar gum, modified food starch, and a laser light absorbing dye. The sound speed and physical consistency of the materials were very close to porcine (arterial) and human (venous) thrombi. Photographic and videotape recordings of pulsed dye laser ablation experiments under various experimental conditions were used to evaluate the new material as compared to in vitro tests with human (venous) thrombus. The characteristics of ablation and mass removal were similar to that of real thrombi, and therefore provide a more realistic model for in vitro laser thrombolysis when compared to gelatin.

  17. Cardiac thrombus developing after an accidental high-voltage electric shock in a child. (United States)

    Akın, Alper; Bilici, Meki; Demir, Fikri; Gözü Pirinççioğlu, Ayfer; Yavuz, Celal


    Electric shock is a condition that may affect various organ systems and potentially cause death. Cardiac findings vary from asymptomatic mild injury to fatal myocardial involvement. Herein we present a five-year-old boy with a cardiac thrombus developing after an accidental electrical shock. Cardiac arrhythmias and evidence of ischemia have been reported after electric shock; we were, however, unable to identify an earlier case report of intracardiac thrombosis related to electric shock. Findings such as elevated cardiac enzymes and systolic dysfunction, which indicate myocardial damage following electric shock, were present in our patient. We think that the cardiac thrombus might have resulted from the myocardial damage and the slowed intracardiac blood flow related to systolic dysfunction. As the thrombus was thought to have been formed through known mechanisms, it was treated traditionally. However, further data regarding the etiology and management of such thrombi is needed.


    Directory of Open Access Journals (Sweden)

    Sheila K


    Full Text Available latelets play a vital role in haemostasis . Antenatal patients with platelet function disorders should be managed in tertiary care centres that are well equipped to tackle any obstetric haemorrhage that can ensue during labour and delivery . Primi gravida was admitted for safe confinement . She had been evaluated earlier for complaints of multiple episodes of mucosal bleeding . On evaluation she had nor mal platelet counts and coagulation factor assay was normal . Platelet aggregometry revealed mild disorder of platelet aggregation . She was planned for induction of labour after arranging enough blood and blood products . She got into active labour and was p ut on syntocinon augmentation . She had emergency Caesarean section for foetal distress . Oxytocics were given proactively . Intraoperatively platelet transfusions and tranexamic acid infusion were given . Complete haemostasis was achieved . She had an uneventf ul postoperative period . Patients with functional platelet disorders can be successfully managed with local application of antifibrinolytic agents like tranexamic acid , in case of minor bleeds . Platelet transfusions are very effective in tackling major ble eds , especially during surgeries and for obstetric indications . If a patient has the history of clinically significant bleeding suggestive of platelet dysfunction , appropriate platelet function tests should be obtained so that the risk of bleeding can be adequately assessed and therapy chosen more rationally . . In obstetric practice the response of such patients to platelet transfusions has been excellent

  19. Formats

    Directory of Open Access Journals (Sweden)

    Gehmann, Ulrich


    Full Text Available In the following, a new conceptual framework for investigating nowadays’ “technical” phenomena shall be introduced, that of formats. The thesis is that processes of formatting account for our recent conditions of life, and will do so in the very next future. It are processes whose foundations have been laid in modernity and which will further unfold for the time being. These processes are embedded in the format of the value chain, a circumstance making them resilient to change. In addition, they are resilient in themselves since forming interconnected systems of reciprocal causal circuits.Which leads to an overall situation that our entire “Lebenswelt” became formatted to an extent we don’t fully realize, even influencing our very percep-tion of it.

  20. Effects of hormones on platelet aggregation. (United States)

    Farré, Antonio López; Modrego, Javier; Zamorano-León, José J


    Platelets and their activation/inhibition mechanisms play a central role in haemostasis. It is well known agonists and antagonists of platelet activation; however, during the last years novel evidences of hormone effects on platelet activation have been reported. Platelet functionality may be modulated by the interaction between different hormones and their platelet receptors, contributing to sex differences in platelet function and even in platelet-mediated vascular damage. It has suggested aspects that apparently are well established should be reviewed. Hormones effects on platelet activity are included among them. This article tries to review knowledge about the involvement of hormones in platelet biology and activity.

  1. Application of cystoscope in surgical treatment of hepatocellular carcinoma with portal vein tumor thrombus. (United States)

    Li, Nan; Wei, Xu-Biao; Cheng, Shu-Qun


    Development of portal vein tumor thrombus deteriorates the prognosis of hepatocellular carcinoma, while surgical treatment can offer a promising prognosis for selected patients. However, the possibility of residual lesions in portal vein after conventional thrombectomy is a main risk factor leading to postoperative recurrence. Therefore, ensuring the complete removal of tumor thrombus during operation is critical to improve prognosis. For the first time, we report here one case of hepatocellular carcinoma with portal vein tumor thrombus in which cystoscope was successfully applied as a substitute of intravascular endoscope to visualize the cavity of the portal vein. The patient was a 61-year-old man with a 7-cm tumor in the right lobe of the liver, with tumor thrombus invading the right branch and adjacent to the conjunction of the portal vein. After removal of the tumor, the Olympus CYF-VA2 cystoscope was used to check the portal vein from the opening stump of the right branch of the portal vein. In this case, residual thrombus tissue was found near the opening stump and the conjunction of the portal vein. The residual lesion was carefully retrieved from the stump after retraction of the cystoscope. The procedure was repeated until no residual lesion was found. The whole duration time of thrombectomy was 22.5 (15 + 7.5) min. The patient was free from recurrence at 8 months after the procedure. Our work indicated that the cystoscope is a suitable substitute, with a proper size and function to check the portal vein system and ensure the curability of thrombectomy. Although well-designed clinic trails are still needed, this procedure may further improve the postoperative prognosis of hepatocellular carcinoma with portal vein tumor thrombus.

  2. Severe reversible dilated cardiomyopathy associated with a large left ventricular thrombus in a young child with middle aortic syndrome. (United States)

    Ponniah, U; Overholt, E


    We report a case of a seven-year girl who presented with severe dilated cardiomyopathy (DCM) associated with a large thrombus in the left ventricle (LV). She had a long segment stenosis of the lower thoracic descending aorta, possibly due to non-specific aortitis and underwent successful stent angioplasty. The LV thrombus resolved after heparin without sequelae.

  3. Severe reversible dilated cardiomyopathy associated with a large left ventricular thrombus in a young child with middle aortic syndrome


    Ponniah, U; Overholt, E


    this article reports a case of a seven-year girl who presented with severe dilated cardiomyopathy (DCM) associated with a large thrombus in the left ventricle (LV). She had a long segment stenosis of the lower thoracic descending aorta, possibly due to non-specific aortitis and underwent successful stent angioplasty. The LV thrombus resolved after heparin without sequelae.

  4. Severe reversible dilated cardiomyopathy associated with a large left ventricular thrombus in a young child with middle aortic syndrome


    Ponniah, U.; Overholt, E.


    this article reports a case of a seven-year girl who presented with severe dilated cardiomyopathy (DCM) associated with a large thrombus in the left ventricle (LV). She had a long segment stenosis of the lower thoracic descending aorta, possibly due to non-specific aortitis and underwent successful stent angioplasty. The LV thrombus resolved after heparin without sequelae.

  5. Surgical Treatment of Renal Cell Carcinoma with Inferior Vena Cava Thrombus: Using Liver Mobilization Technique to Avoid Cardiopulmonary Bypass

    Directory of Open Access Journals (Sweden)

    Tawatchai Taweemonkongsap


    CONCLUSION: These results support the aggressive surgical removal of RCC with IVC thrombus as the initial treatment. Most of the thrombi can be approached and safely controlled by a transabdominal approach without any form of bypass. Tumour thrombus removal provides a high survival chance and offers improvement in quality of life.

  6. Calcium Sulfate and Platelet-Rich Plasma make a novel osteoinductive biomaterial for bone regeneration

    Directory of Open Access Journals (Sweden)

    Intini Francesco E


    Full Text Available Abstract Background With the present study we introduce a novel and simple biomaterial able to induce regeneration of bone. We theorized that nourishing a bone defect with calcium and with a large amount of activated platelets may initiate a series of biological processes that culminate in bone regeneration. Thus, we engineered CS-Platelet, a biomaterial based on the combination of Calcium Sulfate and Platelet-Rich Plasma in which Calcium Sulfate also acts as an activator of the platelets, therefore avoiding the need to activate the platelets with an agonist. Methods First, we tested CS-Platelet in heterotopic (muscle and orthotopic (bone bone regeneration bioassays. We then utilized CS-Platelet in a variety of dental and craniofacial clinical cases, where regeneration of bone was needed. Results The heterotopic bioassay showed formation of bone within the muscular tissue at the site of the implantation of CS-Platelet. Results of a quantitative orthotopic bioassay based on the rat calvaria critical size defect showed that only CS-Platelet and recombinant human BMP2 were able to induce a significant regeneration of bone. A non-human primate orthotopic bioassay also showed that CS-Platelet is completely resorbable. In all human clinical cases where CS-Platelet was used, a complete bone repair was achieved. Conclusion This study showed that CS-Platelet is a novel biomaterial able to induce formation of bone in heterotopic and orthotopic sites, in orthotopic critical size bone defects, and in various clinical situations. The discovery of CS-Platelet may represent a cost-effective breakthrough in bone regenerative therapy and an alternative or an adjuvant to the current treatments.

  7. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders


    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  8. [Effectiveness of anticoagulant oral treatment in patients with thrombus in left ventricle after acute myocardial infarction]. (United States)

    Carrillo, A M; Valdespino, A; Solorio, S; Badui, E; Enciso, R; Lepe, L; Lara, A; Ocampo, S; Alonso, R; Romero, M A


    Left ventricular mural thrombi (LVMT) is a complication of acute myocardial infarction (AMI), that may produce peripheral embolism which could be fatal. In order to establish an adequate time of oral anticoagulant (OA) therapy, we undertook a prospective study that included 45 patients with AMI and left ventricular thrombi detected by echocardiographic study, in the first 5 to 10 days postinfarction, the study was repeated, in 3 and 6 months. Treatment with oral anticoagulant was initiated at the point of the detection of thrombi maintaining an INR of 1.5 to 2. Thirty nine patients (79%) were males and 6 (11%) were females, with an age of 29 to 85 years and a range of 62 +/- 11 years. Forty four patients (98%) presented anterior wall infarction and 1 (2%) posteroinferior infarction. In patients with anterior infarction, in 38 (85%) the thrombi was located at the apical wall (p < 0.05), 5 (11%) in the septal wall and other (2%) in anterior and apical walls. The patient with the posteroinferior infarction presented extension to the right ventricle, where the thrombus was located (2%). The contractility alterations related with thrombi were diskinesia, followed by hipokinesia and finally akinesia. The ejection fraction had not relationship with thrombi formation. LVMT dissolved in 32 patients (71%) at 3 months (p < 0.05), in 8 (18%) in 6 months and in 5 (11%) it was maintained for more than 6 months. None of the patients presented complications of OA. We conclude that the LVMT are more frequent in anterior infarctions, essentially in those that present diskinesia. The majority of LVMT are resolved in 6 months with OA therapy.

  9. Novel use of the AngioVac® system to remove thrombus during simultaneous extracorporeal membrane oxygenation life support. (United States)

    Griffith, Kevin E; Jenkins, Eric; Copenhaver, William; Williams, David M


    Extracorporeal membrane oxygenation (ECMO) was introduced to clinical medicine over 40 years ago. While initially used as a treatment for acute respiratory failure in infants, the use of ECMO has grown to include respiratory and circulatory failure in both children and adults, cardiogenic shock, pulmonary embolism, sepsis, trauma, malignancy, pulmonary hemorrhage and as a treatment for hypothermic drowning.(1) Recent technological improvements in ECMO circuitry make it possible to minimize anticoagulation of the ECMO patient, decreasing the incidence of bleeding. Thrombus deposition within the ECMO circuit can be a life-threating complication. ECMO circuit thrombus can be contained in the circuit, adherent to cannula and deposited within the patient. The ability to remove thrombus while the patient remains on ECMO support could be a life-saving measure for some patients. The present case report outlines use of the AngioVac(®) thrombus removal system in concert with ECMO to remove a large thrombus adherent to an ECMO cannula.

  10. Radiodiagnostic methods in determining the structure of tumor thrombus in the inferior vena cava in kidney cancer

    Directory of Open Access Journals (Sweden)

    N. B. Vikhrova


    Full Text Available Renal cell carcinoma (RCC is the most common primary tumor of the renal parenchyma. Venous involvement is one of the most important anatomic characteristics of tumor. It is known that venous spread influences the survival of patients with RCC. Tumor thrombosis of IVC in patients with renal cell carcinoma has been reported in 4–10 %. The reference standard for RCC with tumor thrombus remains surgical resection. The structure of thrombus determines some technical difficulties in the management of tumor. Spongeous thrombus correlate with higher risk of thrombus detachment during surgery resulting in PE. Therefore determination of IVC thrombus consistency is very important part of preoperative radiologic assessment of tumor in patients with RCC.

  11. Platelets in inflammation and immunity. (United States)

    Herter, J M; Rossaint, J; Zarbock, A


    The paradigm of platelets as mere mediators of hemostasis has long since been replaced by a dual role: hemostasis and inflammation. Now recognized as key players in innate and adaptive immune responses, platelets have the capacity to interact with almost all known immune cells. These platelet-immune cell interactions represent a hallmark of immunity, as they can potently enhance immune cell functions and, in some cases, even constitute a prerequisite for host defense mechanisms such as NETosis. In addition, recent studies have revealed a new role for platelets in immunity: They are ubiquitous sentinels and rapid first-line immune responders, as platelet-pathogen interactions within the vasculature appear to precede all other host defense mechanisms. Here, we discuss recent advances in our understanding of platelets as inflammatory cells, and provide an exemplary review of their role in acute inflammation.

  12. Estrogen, inflammation, and platelet phenotype. (United States)

    Miller, Virginia M; Jayachandran, Muthuvel; Hashimoto, Kazumori; Heit, John A; Owen, Whyte G


    Although exogenous estrogenic therapies increase the risk of thrombosis, the effects of estrogen on formed elements of blood are uncertain. This article examines the genomic and nongenomic actions of estrogen on platelet phenotype that may contribute to increased thrombotic risk. To determine aggregation, secretion, protein expression, and thrombin generation, platelets were collected from experimental animals of varying hormonal status and from women enrolled in the Kronos Early Estrogen Prevention Study. Estrogen receptor beta predominates in circulating platelets. Estrogenic treatment in ovariectomized animals decreased platelet aggregation and adenosine triphosphate (ATP) secretion. However, acute exposure to 17beta-estradiol did not reverse decreases in platelet ATP secretion invoked by lipopolysaccharide. Thrombin generation was positively correlated to the number of circulating microvesicles expressing phosphatidylserine. Assessing the effect of estrogen treatments on blood platelets may lead to new ways of identifying women at risk for adverse thrombotic events with such therapies.

  13. Effects of platelet-poor plasma, platelet-rich plasma, and platelet-rich fibrin on healing of extraction sockets with buccal dehiscence in dogs. (United States)

    Hatakeyama, Ichiro; Marukawa, Eriko; Takahashi, Yukinobu; Omura, Ken


    Alveolar bone resorption generally occurs during healing after tooth extraction. This study aimed to evaluate the effects of platelet-poor plasma (PPP), platelet-rich plasma (PRP), and platelet-rich fibrin (PRF) on healing in a ridge-augmentation model of the canine socket with dehiscence of the buccal wall. The third mandibular premolars of 12 beagle dogs were extracted and a 3 mm buccal dehiscence from the alveolar crest to the buccal wall of the extraction socket was created. These sockets were then divided into four groups on the basis of the material used to fill the sockets: PPP, PRP, PRF, and control (no graft material) groups. Results were evaluated at 4 and 8 weeks after surgery. The ultrastructural morphology and constructs of each blood product were studied by a scanning electron microscope (SEM) or calculating concentrations of platelets, fibrinogen, platelet-derived growth factor, and transforming growth factor-β. A total of five microcomputed tomography images of specimens were selected for measurement, and the area occupied by the newly formed bone as well as the horizontal bone width were measured. Moreover, decalcified tissue specimens from each defect were analyzed histologically. The median area of new bone at 4 and 8 weeks and median horizontal bone width at 8 weeks were the highest in the PPP group. However, bone maturation in the PRF and the PRP groups was more progressed than that in the PPP and control groups. By SEM findings, the PRF group showed a more highly condensed fibrin fiber network that was regularly arranged when compared with the PPP and PRP groups. The growth factors released from platelets in PRP indicated higher concentrations than that in PRF. Under more severe conditions for bone formation, as in this experiment, the growth factors released from platelets had a negative effect on bone formation. This study showed that PPP is an effective material for the preservation of sockets with buccal dehiscence.

  14. Incremental Value of Three-Dimensional Transesophageal Echocardiography over the Two-Dimensional Technique in the Assessment of a Thrombus in Transit through a Patent Foramen Ovale. (United States)

    Thind, Munveer; Ahmed, Mustafa I; Gok, Gulay; Joson, Marisa; Elsayed, Mahmoud; Tuck, Benjamin C; Townsley, Matthew M; Klas, Berthold; McGiffin, David C; Nanda, Navin C


    We report a case of a right atrial thrombus traversing a patent foramen ovale into the left atrium, where three-dimensional transesophageal echocardiography provided considerable incremental value over two-dimensional transesophageal echocardiography in its assessment. As well as allowing us to better spatially characterize the thrombus, three-dimensional transesophageal echocardiography provided a more quantitative assessment through estimation of total thrombus burden.

  15. Analysis of Reparative Activity of Platelet Lysate: Effect on Cell Monolayer Recovery In Vitro and Skin Wound Healing In Vivo. (United States)

    Sergeeva, N S; Shanskii, Ya D; Sviridova, I K; Karalkin, P A; Kirsanova, V A; Akhmedova, S A; Kaprin, A D


    Platelet lysate prepared from donor platelet concentrate and pooled according to a developed technique stimulates migration of multipotent mesenchymal stromal cells of the human adipose tissue and promotes healing of the monolayer defect in cultures of human fibroblasts and multipotent mesenchymal stromal cells in vitro in concentrations close those of fetal calf serum (5-10%). Lysate of platelets from platelet-rich rat blood plasma stimulated healing of the skin defect by promoting epithelialization and granulation tissue formation. The regenerative properties of platelet lysate in vivo increased with increasing its concentration.

  16. Complement Activation Alters Platelet Function (United States)


    Award Number: W81XWH-12-1-0523 TITLE: Complement Activation Alters Platelet Function PRINCIPAL INVESTIGATOR: George Tsokos, M.D. CONTRACTING...Activation Alters Platelet Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0523 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) George Tsokos, M.D...a decreased level of disease. Further studies will expand upon these observations better outlining the function of platelets in the injury associated

  17. Platelet effects on ovarian cancer (United States)

    Davis, Ashley; Afshar-Kharghan, Vahid; Sood, Anil K.


    Growing understanding of the role of thrombocytosis, high platelet turnover, and the presence of activated platelets in the circulation in cancer progression and metastasis has brought megakaryocytes into focus. Platelet biology is essential to hemostasis, vascular integrity, angiogenesis, inflammation, innate immunity, wound healing, and cancer biology. However, before megakaryocyte/platelet-directed therapies can be considered for clinical use, understanding of the mechanism and biology of paraneoplastic thrombocytosis in malignancy is required. Here, we provide an overview of the clinical implications, biological significance, and mechanisms of paraneoplastic thrombocytosis in the context of ovarian cancer. PMID:25023353

  18. Overview of platelet physiology and laboratory evaluation of platelet function. (United States)

    Rodgers, G M


    Appropriate laboratory testing for the platelet-type bleeding disorders hinges on an adequate assessment in the history and physical examination. Patients with histories and screening laboratory results consistent with coagulation disorders (hemophilia, disseminated intravascular coagulation) are not appropriate candidates for platelet function testing. In contrast, patients with a lifelong history of platelet-type bleeding symptoms and perhaps a positive family history of bleeding would be appropriate for testing. Figure 6 depicts one strategy to evaluate these patients. Platelet morphology can easily be evaluated to screen for two uncommon qualitative platelet disorders: Bernard-Soulier syndrome (associated with giant platelets) and gray platelet syndrome, a subtype of storage pool disorder in which platelet granulation is morphologically abnormal by light microscopy. If the bleeding disorder occurred later in life (no bleeding with surgery or trauma early in life), the focus should be on acquired disorders of platelet function. For those patients thought to have an inherited disorder, testing for vWD should be done initially because approximately 1% of the population has vWD. The complete vWD panel (factor VIII coagulant activity, vWf antigen, ristocetin cofactor activity) should be performed because many patients will have abnormalities of only one particular panel component. Patients diagnosed with vWD should be classified using multimeric analysis to identify the type 1 vWD patients likely to respond to DDAVP. If vWD studies are normal, platelet aggregation testing should be performed, ensuring that no antiplatelet medications have been ingested at least 1 week before testing. If platelet aggregation tests are normal and if suspicion for an inherited disorder remains high, vWD testing should be repeated. The evaluation of thrombocytopenia may require bone marrow examination to exclude primary hematologic disorders. If future studies with thrombopoietin assays

  19. Increased platelet activation in early symptomatic versus asymptomatic carotid stenosis and relationship with microembolic status: Results from the Platelets And Carotid Stenosis (PACS) Study.

    LENUS (Irish Health Repository)

    Kinsella, Ja


    -negative patients (2.8 vs. 2.3%; p=0.0085). DISCUSSION: Recently symptomatic carotid stenosis patients have higher platelet counts (potentially reflecting increased platelet production, mobilisation or reduced clearance) and platelet activation status than asymptomatic patients. MES were more frequently detected in early symptomatic than asymptomatic patients, but the differences between late symptomatic and asymptomatic groups were not significant. Increased lymphocyte-platelet complex formation in recently symptomatic vs. asymptomatic MES-negative patients indicates enhanced platelet activation in this early symptomatic subgroup. Platelet biomarkers, in combination with TCD, have the potential to aid risk-stratification in asymptomatic and symptomatic carotid stenosis patients. This article is protected by copyright. All rights reserved.

  20. Crosstalk between Platelets and the Immune System: Old Systems with New Discoveries

    Directory of Open Access Journals (Sweden)

    Conglei Li


    Full Text Available Platelets are small anucleate cells circulating in the blood. It has been recognized for more than 100 years that platelet adhesion and aggregation at the site of vascular injury are critical events in hemostasis and thrombosis; however, recent studies demonstrated that, in addition to these classic roles, platelets also have important functions in inflammation and the immune response. Platelets contain many proinflammatory molecules and cytokines (e.g., P-selectin, CD40L, IL-1β, etc., which support leukocyte trafficking, modulate immunoglobulin class switch, and germinal center formation. Platelets express several functional Toll-like receptors (TLRs, such as TLR-2, TLR-4, and TLR-9, which may potentially link innate immunity with thrombosis. Interestingly, platelets also contain multiple anti-inflammatory molecules and cytokines (e.g., transforming growth factor-β and thrombospondin-1. Emerging evidence also suggests that platelets are involved in lymphatic vessel development by directly interacting with lymphatic endothelial cells through C-type lectin-like receptor 2. Besides the active contributions of platelets to the immune system, platelets are passively targeted in several immune-mediated diseases, such as autoimmune thrombocytopenia, infection-associated thrombocytopenia, and fetal and neonatal alloimmune thrombocytopenia. These data suggest that platelets are important immune cells and may contribute to innate and adaptive immunity under both physiological and pat