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Sample records for acid-induced platelet aggregation

  1. The effect of the menstrual cycle and of decompression stress on arachidonic acid-induced platelet aggregation and on intrinsic platelet thromboxane production in women compared with men.

    PubMed

    Markham, S M; Dubin, N H; Rock, J A

    1991-12-01

    Menstrual cycle variations in platelet aggregation and thromboxane production in association with sex steroids have been reported. External stimuli such as decompression sickness have been associated with clotting activity changes, specifically, increased platelet aggregation. Differences in response of platelets from women and men, when subjected to such a stress, have been observed. This study evaluated the ability of washed platelets from women in the proliferative and secretory phases of the menstrual cycle to aggregate in response to arachidonic acid and the aggregation difference between washed platelets from women and men in response to decompression stress and arachidonic acid. Additionally, platelet thromboxane production differences between the assessed platelet populations were compared. Our results indicate no difference in platelet aggregability between phases of the menstrual cycle. A significant aggregation difference between platelets from women and men was noted. Platelets from women were more sensitive to arachidonic acid aggregation. These differences were not affected by decompression stress. No difference in thromboxane B2 production was noted between the platelet populations evaluated.

  2. Acetal phosphatidic acids: novel platelet aggregating agents.

    PubMed

    Brammer, J P; Maguire, M H; Walaszek, E J; Wiley, R A

    1983-05-01

    1 Palmitaldehyde, olealdehyde and linolealdehyde acetal phosphatidic acids induced rapid shape change and dose-dependent biphasic aggregation of human platelets in platelet-rich plasma; aggregation was reversible at low doses and irreversible at high doses of the acetal phosphatidic acids. The palmitaldehyde congener elicited monophasic dose-dependent aggregation of sheep platelets in platelet-rich plasma.2 The threshold concentration for palmitaldehyde acetal phosphatidic acid (PGAP)-induced platelet aggregation was 2.5-5 muM for human platelets and 0.25-0.5 muM for sheep platelets. PGAP was 4-5 times as potent versus human platelets as the olealdehyde and linolealdehyde acetal phosphatidic acids, which were equipotent.3 PGAP-induced irreversible aggregation of [(14)C]-5-hydroxytryptamine ([(14)C]-5-HT)-labelled human platelets in platelet-rich plasma was accompanied by release of 44.0+/-2.4% (s.e.) of the platelet [(14)C]-5-HT; reversible aggregation was not associated with release. In contrast, PGAP-induced release of [(14)C]-5-HT-labelled sheep platelets was dose-dependent.4 The adenosine diphosphate (ADP) antagonist, 2-methylthio-AMP, and the cyclo-oxygenase inhibitor, aspirin, abolished PGAP-induced second phase aggregation and release in human platelets but did not affect the first, reversible, phase of aggregation. Both the first and second phases of PGAP-induced aggregation were abolished by chlorpromazine, by the phospholipase A(2) inhibitor, mepacrine, and by nmolar concentrations of prostaglandin E(1) (PGE(1)); these agents abolished the second, but not the first phase of ADP-induced aggregation.5 The related phospholipids, lecithin, lysolecithin and phosphatidic acid, at <100 muM, neither induced aggregation of human platelets in platelet-rich plasma, nor modified PGAP-induced aggregation; 1-palmityl lysophosphatidic acid elicited aggregation of human platelets at a threshold concentration of 100 muM.6 It is concluded that the acetal phosphatidic acids

  3. Taurine and platelet aggregation

    SciTech Connect

    Nauss-Karol, C.; VanderWende, C.; Gaut, Z.N.

    1986-03-01

    Taurine is a putative neurotransmitter or neuromodulator. The endogenous taurine concentration in human platelets, determined by amino acid analysis, is 15 ..mu..M/g. In spite of this high level, taurine is actively accumulated. Uptake is saturable, Na/sup +/ and temperature dependent, and suppressed by metabolic inhibitors, structural analogues, and several classes of centrally active substances. High, medium and low affinity transport processes have been characterized, and the platelet may represent a model system for taurine transport in the CNS. When platelets were incubated with /sup 14/C-taurine for 30 minutes, then resuspended in fresh medium and reincubated for one hour, essentially all of the taurine was retained within the cells. Taurine, at concentrations ranging from 10-1000 ..mu..M, had no effect on platelet aggregation induced by ADP or epinephrine. However, taurine may have a role in platelet aggregation since 35-39% of the taurine taken up by human platelets appears to be secreted during the release reaction induced by low concentrations of either epinephrine or ADP, respectively. This release phenomenon would imply that part of the taurine taken up is stored directly in the dense bodies of the platelet.

  4. Cyclosporine A enhances platelet aggregation.

    PubMed

    Grace, A A; Barradas, M A; Mikhailidis, D P; Jeremy, J Y; Moorhead, J F; Sweny, P; Dandona, P

    1987-12-01

    In view of the reported increase in thromboembolic episodes following cyclosporine A (CyA) therapy, the effect of this drug on platelet aggregation and thromboxane A2 release was investigated. The addition of CyA, at therapeutic concentrations to platelet rich plasma from normal subjects in vitro was found to increase aggregation in response to adrenaline, collagen and ADP. Ingestion of CyA by healthy volunteers was also associated with enhanced platelet aggregation. The CyA-mediated enhancement of aggregation was further enhanced by the addition in vitro of therapeutic concentrations of heparin. Platelets from renal allograft recipients treated with CyA also showed hyperaggregability and increased thromboxane A2 release, which were most marked at "peak" plasma CyA concentration and less so at "trough" concentrations. Platelet hyperaggregability in renal allograft patients on long-term CyA therapy tended to revert towards normal following the replacement of CyA with azathioprine. Hypertensive patients with renal allografts on nifedipine therapy had normal platelet function and thromboxane release in spite of CyA therapy. These observations suggest that CyA-mediated platelet activation may contribute to the pathogenesis of the thromboembolic phenomena associated with the use of this drug. The increased release of thromboxane A2 (a vasoconstrictor) may also play a role in mediating CyA-related nephrotoxicity.

  5. Individual dosing of ASA prophylaxis by controlling platelet aggregation.

    PubMed

    Syrbe, G; Redlich, H; Weidlich, B; Ludwig, J; Kopitzsch, S; Göckefitz, A; Herzog, T

    2001-07-01

    Acetylsalicylic acid is widely used in the primary and secondary prevention of cardiovascular diseases. In the current study, we used platelet aggregation ex vivo in platelet-rich plasma induced with arachidonic acid as a routine method for the determination of the individual dose of acetylsalicylic acid necessary to inhibit platelet aggregation in 108 patients with cardiovascular diseases. In 40% of all patients studied, a dose of 30 mg/day was sufficient to block the arachidonic acid-induced platelet aggregation nearly completely. In 50% of all patients, a dose of 100 mg/day was necessary. In 10% of all patients, the dose had to be further increased to 300 mg/day or even to 500 mg/day to inhibit platelet aggregation nearly completely. These results demonstrate that platelet aggregation can be used as a simple routine laboratory method to control acetylsalicylic acid treatment in patients with cardiovascular diseases and to determine individual doses of acetylsalicylic acid for a nearly complete inhibition of platelet aggregation. With a standard dose of 100 mg/day, 10% of the patients were nonresponders. PMID:11441981

  6. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

    SciTech Connect

    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. State Univ. of New York, Buffalo )

    1987-11-01

    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.

  7. Anger expression correlates with platelet aggregation.

    PubMed

    Wenneberg, S R; Schneider, R H; Walton, K G; MacLean, C R; Levitsky, D K; Mandarino, J V; Waziri, R; Wallace, R K

    1997-01-01

    Potential relationships between increased platelet aggregability and such psychological characteristics as hostility and anger were investigated as part of a larger intervention study investigating the potential efficacy of stress-reduction treatments. Participants performed 6-minute mental arithmetic tests under time pressure. Blood was sampled during the first minute of the task and whole blood platelet aggregation was measured in an aggregometer, using collagen and ADP. To assess anger and hostility, the authors used Spielberger's State-Trait Anger and Anger Expression scales together with the Cook-Medley Hostility Scale. The authors found positive correlations between collagen-induced platelet aggregation and outwardly expressed anger, as measured by the Anger Expression Scale. The findings suggested that modes of anger expression may be associated with increased platelet aggregation. If confirmed by future studies, this finding could provide a mechanism for the putative connection between anger/hostility and coronary heart disease.

  8. Acid soluble, pepsin resistant platelet aggregating material

    SciTech Connect

    Schneider, M.D.

    1982-08-31

    Disclosed is an acid soluble, pepsin resistant, platelet aggregating material isolated from equine arterial tissue by extraction with dilute aqueous acid. The method of isolation and use to control bleeding are described. 4 figs.

  9. Increasing platelet aggregability after venepuncture is platelet, not plasma derived.

    PubMed

    Terres, W; Becker, B F; Kratzer, M A; Gerlach, E

    1986-05-15

    The time course of ADP induced aggregation of human platelets was determined in aliquots of stored platelet rich plasma 3.5, 10, 30 and 100 minutes after venepuncture. The maximal rate of aggregation was found to increase throughout this entire period, even though pH (7.4), CO2 (7 volume per cent) and temperature (35 degrees C) of the samples were kept constant. The mean acceleration (+/- SEM) between 3.5 and 100 minutes was 41.7 +/- 6.9 per cent (n = 67) at an ADP-concentration of 1 mumol/l and 18.3 +/- 6.2 per cent (n = 23) at 2 mumol/l ADP. The effect did not result from changes of any platelet regulatory factors putatively present alone in the plasma. Acceleration of aggregability was only found when the platelets themselves underwent storage, but not when freshly prepared plasma was given to prestored platelets. The change in aggregability was not diminished after inhibition of platelet cyclooxygenase by oral administration of acetylsalicylic acid. PMID:3715816

  10. Analysis of aggregation of platelets in thrombosis

    NASA Astrophysics Data System (ADS)

    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.

  11. Effects of tetrandrine and fangchinoline on human platelet aggregation and thromboxane B2 formation.

    PubMed

    Kim, H S; Zhang, Y H; Fang, L H; Yun, Y P; Lee, H K

    1999-08-01

    Tetrandrine (TET) and fangchinoline (FAN) are two major components of the radix of Stephania tetrandra. The effects of TET and FAN on human platelet aggregation and formation of thromboxane (TX) B2, a stable metabolite of TXA2, were examined in the aspect of platelet aggregation. TET and FAN inhibited platelet-activating factor (PAF)-induced human platelet aggregation. IC50 values for TET and FAN were 28.6+/-3.24 microM and 21.7+/-2.61 microM, respectively. In the PAF-receptor binding assay, neither TET nor FAN showed any inhibitory effects on the specific bindings of PAF to its receptor. TET and FAN also inhibited PAF-, thrombin- and arachidonic acid-induced thromboxane B2 formation in human washed platelet. These results indicate that TET and FAN inhibit the platelet aggregation by interfering with the intracellular messengers system, but not by inhibiting the binding of PAF to PAF-receptor on the platelet membrane directly, and the suppression of TXA2 formation by TET and FAN may be responsible for their inhibitory activities on the platelet aggregation and further on the thrombosis. PMID:10433485

  12. Platelet aggregating material from equine arterial tissue

    SciTech Connect

    Schneider, M.D.

    1983-02-22

    Novel hemostatic agent comprises equine arterial fibrillar collagen in a carrier. The agent is useful for the aggregation of platelets for clinical diagnostic tests and for the clotting of blood, such as for controlling bleeding in warm blooded species. The fibrillar collagen is obtained by extracting homogenized equine arterial tissue with aqueous solutions followed by extensive dialysis. No Drawings

  13. Platelet aggregating material from equine arterial tissue

    DOEpatents

    Schneider, Morris D.

    1983-02-22

    Novel hemostatic agent comprises equine arterial fibrillar collagen in a carrier. The agent is useful for the aggregation of platelets for clinical diagnostic tests and for the clotting of blood, such as for controlling bleeding in warm blooded species. The fibrillar collagen is obtained by extracting homogenized equine arterial tissue with aqueous solutions followed by extensive dialysis.

  14. [A method for studying intravascular platelet aggregation in vitro].

    PubMed

    Ikonnikova, E I; Chernousova, L A; Moshkina, I R

    1999-06-01

    A simple available method for evaluating intravascular platelet aggregation is proposed. It consists in graphic recording of disaggregation of platelet-rich citrate plasma, which indicates the degree of intravascular aggregation. Intravascular aggregation is notably increased in coronary patients and negligible in normal subjects. The method may be used for the diagnosis of diseases with a high thrombogenic risk.

  15. Acid-induced aggregation propensity of nivolumab is dependent on the Fc.

    PubMed

    Liu, Boning; Guo, Huaizu; Xu, Jin; Qin, Ting; Xu, Lu; Zhang, Junjie; Guo, Qingcheng; Zhang, Dapeng; Qian, Weizhu; Li, Bohua; Dai, Jianxin; Hou, Sheng; Guo, Yajun; Wang, Hao

    2016-01-01

    Nivolumab, an anti-programmed death (PD)1 IgG4 antibody, has shown notable success as a cancer treatment. Here, we report that nivolumab was susceptible to aggregation during manufacturing, particularly in routine purification steps. Our experimental results showed that exposure to low pH caused aggregation of nivolumab, and the Fc was primarily responsible for an acid-induced unfolding phenomenon. To compare the intrinsic propensity of acid-induced aggregation for other IgGs subclasses, tocilizumab (IgG1), panitumumab (IgG2) and atezolizumab (aglyco-IgG1) were also investigated. The accurate pH threshold of acid-induced aggregation for individual IgG Fc subclasses was identified and ranked as: IgG1 < aglyco-IgG1 < IgG2 < IgG4. This result was cross-validated by thermostability and conformation analysis. We also assessed the effect of several protein stabilizers on nivolumab, and found mannitol ameliorated the acid-induced aggregation of the molecule. Our results provide valuable insight into downstream manufacturing process development, especially for immune checkpoint modulating molecules with a human IgG4 backbone. PMID:27310175

  16. Platelet aggregation associated with ethanol intoxication

    SciTech Connect

    Volk, S.; Walenga, J.; Fareed, J.; Schumacher, H. )

    1989-02-09

    Alcohol is known to produce profound effects on blood; during chronic intoxication, prolongation of bleeding time has been reported. Utilizing human platelet rich plasma, we have studied the effect of alcohol on epinephrine, arachidonic acid and ADP induced aggregation. Control responses were obtained with saline from which the relative inhibition by alcohol was calculated. These studies were carried out at a concentration of 1.25-5.0 mg/ml which represents 0.125-0.5% alcohol blood levels. From 25 normal male and female volunteers, without prior hemostatic defects or drug ingestion, a dose-dependent inhibition by alcohol of all three agonist induced aggregations was noted. Alcohol itself did not produce any aggregation response. These studies demonstrate that alcohol at levels which are reached during intoxication is capable of impairing platelet function. The implication of this finding on the bleeding complications in healthy intoxicated patients may be significant during traumatic events, and individuals taking antiplatelet drugs may present a more serious hemostatic deficit during alcohol intoxication.

  17. [Mechanism of cooked blanched garlic leaves against platelet aggregation].

    PubMed

    Wang, Xin-Hua; Di, Yan-Hui

    2014-06-01

    This study was purposed to explore the mechanism of cooked blanched garlic leave juice against platelet aggregation. The juice of blanched garlic leaves was mixed with platelet rich plasma (PRP), the human platelet aggregation, the activation of human platelets induced by adenosine diphosphate (ADP) and collagen were observed; the expression levels of the activated platelets (Fib-R) and P-selectin (CD62P), and the amount of platelet fibrinogen binding were detected by flow cytometry; 10 rabbits were randomly divided into two groups, in addition to the normal diet, they were fed with physiologic saline and cooked blanched garlic leave juice respectively. After 1, 3, 5 , 8 weeks, the maximum ratio of rabbit platelet aggregation induced by ADP and collagen were observed . The results showed that the cooked blanched garlic leave juice could significantly inhibit human platelet aggregation induced by ADP and collagen (P < 0.05), the inhibitory ratio were 87.37% and 86.24% respectively; the juice could not inhibit activated platelets Fib-R and CD62P expression levels (P > 0.05), but was able to inhibit platelet fibrinogen binding capacity (P < 0.05); the rabbit platelet aggregation rate in the group given cooked blanched garlic leave juice was significantly lower than that in control group (P < 0.05). It is concluded that the cooked blanched garlic leave juice can inhibit platelet aggregation in vitro and in vivo, the inhibition of aggregation pathway mainly is blocking the combination of fibrinogen with Fib-R, which finally results in the inhibition of platelet aggregation. Therefore, regular consumption of cooked blanched garlic leaves may prevent cardiovascular thrombotic diseases. PMID:24989289

  18. [Mechanism of cooked blanched garlic leaves against platelet aggregation].

    PubMed

    Wang, Xin-Hua; Di, Yan-Hui

    2014-06-01

    This study was purposed to explore the mechanism of cooked blanched garlic leave juice against platelet aggregation. The juice of blanched garlic leaves was mixed with platelet rich plasma (PRP), the human platelet aggregation, the activation of human platelets induced by adenosine diphosphate (ADP) and collagen were observed; the expression levels of the activated platelets (Fib-R) and P-selectin (CD62P), and the amount of platelet fibrinogen binding were detected by flow cytometry; 10 rabbits were randomly divided into two groups, in addition to the normal diet, they were fed with physiologic saline and cooked blanched garlic leave juice respectively. After 1, 3, 5 , 8 weeks, the maximum ratio of rabbit platelet aggregation induced by ADP and collagen were observed . The results showed that the cooked blanched garlic leave juice could significantly inhibit human platelet aggregation induced by ADP and collagen (P < 0.05), the inhibitory ratio were 87.37% and 86.24% respectively; the juice could not inhibit activated platelets Fib-R and CD62P expression levels (P > 0.05), but was able to inhibit platelet fibrinogen binding capacity (P < 0.05); the rabbit platelet aggregation rate in the group given cooked blanched garlic leave juice was significantly lower than that in control group (P < 0.05). It is concluded that the cooked blanched garlic leave juice can inhibit platelet aggregation in vitro and in vivo, the inhibition of aggregation pathway mainly is blocking the combination of fibrinogen with Fib-R, which finally results in the inhibition of platelet aggregation. Therefore, regular consumption of cooked blanched garlic leaves may prevent cardiovascular thrombotic diseases.

  19. Effects of hormones on platelet aggregation.

    PubMed

    Farré, Antonio López; Modrego, Javier; Zamorano-León, José J

    2014-04-01

    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.

  20. Endocannabinoids Control Platelet Activation and Limit Aggregate Formation under Flow

    PubMed Central

    De Angelis, Valentina; Koekman, Arnold C.; Weeterings, Cees; Roest, Mark; de Groot, Philip G.; Herczenik, Eszter; Maas, Coen

    2014-01-01

    Background The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function. Objectives Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo. Methods and Results We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa. Conclusions Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function

  1. Effects of Suilysin on Streptococcus suis-Induced Platelet Aggregation

    PubMed Central

    Zhang, Shengwei; Wang, Junping; Chen, Shaolong; Yin, Jiye; Pan, Zhiyuan; Liu, Keke; Li, Lin; Zheng, Yuling; Yuan, Yuan; Jiang, Yongqiang

    2016-01-01

    Blood platelets play important roles during pathological thrombocytopenia in streptococcal toxic shock syndrome (STSS). Streptococcus suis (S. suis) an emerging human pathogen, can cause STSS similarly to S. pyogenes. However, S. suis interactions with platelets are poorly understood. Here, we found that suilysin (SLY), different from other bacterial cholesterol-dependent cytolysins (CDCs), was the sole stimulus that induced platelet aggregation. Furthermore, the inside-out activation of GPIIb/IIIa of platelets mediated SLY-induced platelet aggregation. This process was triggered by Ca2+ influx that depend on the pore forming on platelets by SLY. Additionally, although SLY induced α-granule release occurred via the MLCK-dependent pathway, PLC-β-IP3/DAG-MLCK and Rho-ROCK-MLCK signaling were not involved in SLY-induced platelet aggregation. Interestingly, the pore dependent Ca2+ influx was also found to participate in the induction of platelet aggregation with pneumolysin (PLY) and streptolysin O (SLO), two other CDCs. It is possible that the CDC-mediated platelet aggregation we observed in S. suis is a similar response mechanism to that used by a wide range of bacteria. These findings might lead to the discovery of potential therapeutic targets for S. suis-associated STSS. PMID:27800304

  2. Platelet aggregability and in vivo platelet deposition in patients with ischemic cerebrovascular disease--evaluation by indium-111-platelet scintigraphy

    SciTech Connect

    Isaka, Y.; Kimura, K.; Uehara, A.; Hashikawa, K.; Mieno, M.; Matsumoto, M.; Handa, N.; Nakabayashi, S.; Imaizumi, M.; Kamada, T. )

    1989-12-15

    In ischemic cerebrovascular disease, it is not clear whether platelet function in vitro actually reflects the situation in vivo. Using indium-111 platelet scintigraphy as a method for detecting platelet activation in vivo, we tried to elucidate this problem. Twenty eight patients with chronic stage of ischemic cerebrovascular disease (CVD) and 17 control subjects were examined. Platelet scintigrams were positive in 9 of 28 patients in CVD, while all were negative in control. A comparison of the results obtained from qualitative platelet imaging and platelet aggregability was performed to evaluate whether threshold aggregation concentration (TAC) grade differed across the three groups (control, CVD patients without platelet deposition and CVD patients with platelet deposition). CVD patients with platelet deposition showed a higher TAC than those patients who did not show platelet deposition (P less than 0.05) or control subjects without platelet deposition (P less than 0.05). These results suggest that some patients in chronic stages of CVD may have active platelet deposition on carotid atheromatous lesions, and presence of platelet deposition in vivo could contribute to reduce platelet reactivity in peripheral blood.

  3. Lonomia obliqua venomous secretion induces human platelet adhesion and aggregation.

    PubMed

    Berger, Markus; Reck, José; Terra, Renata M S; Beys da Silva, Walter O; Santi, Lucélia; Pinto, Antônio F M; Vainstein, Marilene H; Termignoni, Carlos; Guimarães, Jorge A

    2010-10-01

    The caterpillar Lonomia obliqua is a venomous animal that causes numerous accidents, especially in southern Brazil, where it is considered a public health problem. The clinical manifestations include several haemostatic disturbances that lead to a hemorrhagic syndrome. Considering that platelets play a central role in hemostasis, in this work we investigate the effects of L. obliqua venomous secretion upon blood platelets responses in vitro. Results obtained shows that L. obliqua venom directly induces aggregation and ATP secretion in human washed platelets in a dose-dependent manner. Electron microscopy studies clearly showed that the venomous bristle extract was also able to produce direct platelets shape change and adhesion as well as activation and formation of platelet aggregates. Differently from other enzyme inhibitors, the venom-induced platelet aggregation was significatively inhibited by p-bromophenacyl bromide, a specific inhibitor of phospholipases A2. Additional experiments with different pharmacological antagonists indicate that the aggregation response triggered by the venom active components occurs through a calcium-dependent mechanism involving arachidonic acid metabolite(s) of the cyclooxygenase pathway and activation of phosphodiesterase 3A, an enzyme that leads to the consumption of intracellular cAMP content. It was additionally found that L. obliqua-induced platelet aggregation was independent of ADP release. Altogether, these findings are in line with the need for a better understanding of the complex hemorrhagic syndrome resulting from the envenomation caused by L. obliqua caterpillars, and can also give new insights into the management of its clinical profile.

  4. Acidic-store depletion is required for human platelet aggregation.

    PubMed

    Amor, Nidhal Ben; Zbidi, Hanene; Bouaziz, Aicha; Jardin, Isaac; Isaac, Jardin; Hernández-Cruz, Juan M; Salido, Ginés M; Rosado, Juan A; Bartegi, Aghleb

    2009-10-01

    Platelet stimulation with thrombin induces an elevation in cytoplasmic free Ca(2+) concentration ([Ca(2+)]c) due to Ca(2+) release from intracellular stores and entry from the extracellular medium. Two different intracellular Ca(2+) stores have been described in human platelets: the dense tubular system and the lysosomal-like acidic stores. In the present study, we investigated the contribution of the acidic stores in thrombin-induced platelet aggregation. We have found that platelet aggregation induced by thrombin is reduced in a Ca(2+)-free medium. Discharge of the acidic Ca(2+) stores by treatment with the sarcoendoplasmic Ca(2+)-ATPase (SERCA)3 selective inhibitor 2,5-di-(tert-butyl)-1,4-hydroquinone reduced thrombin-evoked platelet aggregation. In the presence of 2,5-di-(tert-butyl)-1,4-hydroquinone, platelet aggregation induced by the protease-activated receptor (PAR)-1 and PAR-4 agonist peptides, SFLLRN and AYPGKF, respectively, was significantly reduced. In cells with depleted acidic stores, activation of GPIb-IX-V by thrombin resulted in reduced or no platelet aggregation in a medium containing 1 mmol/l Caor in a Ca(2+)-free medium, respectively. This finding suggests that Ca(2+) accumulation in the acidic Ca(2+) compartments is required for platelet aggregation induced by activation of the G-coupled PAR-1 and PAR-4 thrombin receptors and, by the occupation of the leucine-rich glycoprotein GPIb-IX-V and provide evidence supporting a functional role of the lysosomal-like acidic Ca(2+) stores in human platelets. PMID:19587585

  5. Platelet-cytokine Complex Suppresses Tumour Growth by Exploiting Intratumoural Thrombin-dependent Platelet Aggregation

    PubMed Central

    Li, Yu-Tung; Nishikawa, Tomoyuki; Kaneda, Yasufumi

    2016-01-01

    Tumours constitute unique microenvironments where various blood cells and factors are exposed as a result of leaky vasculature. In the present study, we report that thrombin enrichment in B16F10 melanoma led to platelet aggregation, and this property was exploited to administer an anticancer cytokine, interferon-gamma induced protein 10 (IP10), through the formation of a platelet-IP10 complex. When intravenously infused, the complex reached platelet microaggregates in the tumour. The responses induced by the complex were solely immune-mediated, and tumour cytotoxicity was not observed. The complex suppressed the growth of mouse melanoma in vivo, while both platelets and the complex suppressed the accumulation of FoxP3+ regulatory T cells in the tumour. These results demonstrated that thrombin-dependent platelet aggregation in B16F10 tumours defines platelets as a vector to deliver anticancer cytokines and provide specific treatment benefits. PMID:27117228

  6. Inhibition of rat platelet aggregation by Urtica dioica leaves extracts.

    PubMed

    El Haouari, Mohammed; Bnouham, Mohamed; Bendahou, Mourad; Aziz, Mohammed; Ziyyat, Abderrahim; Legssyer, Abdelkhaleq; Mekhfi, Hassane

    2006-07-01

    Platelet hyperactivity plays an important role in arterial thrombosis and atherosclerosis. The present study was undertaken to investigate the effects of different extracts of Urtica dioica leaves on platelet aggregation. Rat platelets were prepared and incubated in vitro with different concentrations of the tested extracts and aggregation was induced by different agonists including thrombin (0.5 U/mL), ADP (10 microm), epinephrine (100 microm) and collagen (5 mg/mL). The crude aqueous extract inhibited thrombin-induced platelet aggregation in a dose-dependent manner. At 1 mg/mL, the percent inhibition was 17.1 +/- 4.2%. Soxhlet extraction of the plant leaves with different successive solvents showed that the ethyl acetate extract exhibited the most antiaggregant effect with an inhibition of 76.8 +/- 6.1% at 1 mg/mL. Flavonoids isolated from the plant leaves, produced a strong inhibitory effect on thrombin-induced platelet aggregation with an IC(50) of 0.25 +/- 0.05 and 0.40 +/- 0.04 mg/mL for genins and heterosidic flavonoids, respectively. Flavonoids also markedly inhibited platelet aggregation induced by ADP, collagen and epinephrine. It is concluded that Urtica dioica has an antiplatelet action in which flavonoids are mainly implicated. These results support the traditional use of Urtica dioica in the treatment and/or prevention of cardiovascular disease. PMID:16619332

  7. Enhancement of Platelet Aggregation by Ursolic Acid and Oleanolic Acid

    PubMed Central

    Kim, Mikyung; Han, Chang-ho; Lee, Moo-Yeol

    2014-01-01

    The pentacyclic triterpenoid ursolic acid (UA) and its isomer oleanolic acid (OA) are ubiquitous in food and plant medicine, and thus are easily exposed to the population through natural contact or intentional use. Although they have diverse health benefits, reported cardiovascular protective activity is contentious. In this study, the effect of UA and OA on platelet aggregation was examined on the basis that alteration of platelet activity is a potential process contributing to cardiovascular events. Treatment of UA enhanced platelet aggregation induced by thrombin or ADP, which was concentration-dependent in a range of 5–50 μM. Quite comparable results were obtained with OA, in which OA-treated platelets also exhibited an exaggerated response to either thrombin or ADP. UA treatment potentiated aggregation of whole blood, while OA failed to increase aggregation by thrombin. UA and OA did not affect plasma coagulation assessed by measuring prothrombin time and activated partial thromboplastin time. These results indicate that both UA and OA are capable of making platelets susceptible to aggregatory stimuli, and platelets rather than clotting factors are the primary target of them in proaggregatory activity. These compounds need to be used with caution, especially in the population with a predisposition to cardiovascular events. PMID:25009707

  8. Development of a method to quantify platelet adhesion and aggregation under static conditions

    PubMed Central

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

    2014-01-01

    Platelets are important players in hemostasis and thrombosis. Thus, accurate assessment of platelet function is crucial for identifying platelet function disorders and measuring the efficacy of antiplatelet therapies. We have developed a novel platelet aggregation technique that utilizes the physical parameter of platelet concentration in conjunction with volume and mass measurements to evaluate platelet adhesion and aggregation. Platelet aggregates were formed by incubating purified platelets on fibrinogen- or fibrillar collagen-coated surfaces at platelet concentrations ranging from 20,000 to 500,000 platelets/ L. Platelets formed aggregates under static conditions in a platelet concentration-dependent manner, with significantly greater mean volume and mass at higher platelet concentrations ( 400,000 platelets/ L). We show that a platelet glycoprotein IIb/IIIa inhibitor abrogated platelet-platelet aggregation, which significantly reduced the volume and mass of the platelets on the collagen surface. This static platelet aggregation technique is amenable to standardization and represents a useful tool to investigate the mechanism of platelet activation and aggregation under static conditions. PMID:24883127

  9. Platelets and atherogenesis: Platelet anti-aggregation activity and endothelial protection from tomatoes (Solanum lycopersicum L.)

    PubMed Central

    PALOMO, IVÁN; FUENTES, EDUARDO; PADRÓ, TERESA; BADIMON, LINA

    2012-01-01

    In recent years, it has been shown that platelets are not only involved in the arterial thrombotic process, but also that they play an active role in the inflammatory process of atherogenesis from the beginning. The interaction between platelets and endothelial cells occurs in two manners: activated platelets unite with intact endothelial cells, or platelets in resting adhere to activated endothelium. In this context, inhibition of the platelet function (adhesion/aggregation) could contribute to the prevention of atherothrombosis, the leading cause of cardiovascular morbidity. This can be achieved with antiplatelet agents. However, at the public health level, the level of primary prevention, a healthy diet has also been shown to exert beneficial effects. Among those elements of a healthy diet, the consumption of tomatoes (Solanum lycopersicum L.) stands out for its effect on platelet anti-aggregation activity and endothelial protection, which may be beneficial for cardiovascular health. This article briefly discusses the involvement of platelets in atherogenesis and the possible mechanisms of action provided by tomatoes for platelet anti-aggregation activity and endothelial protection. PMID:22969932

  10. Ajoene inhibition of platelet aggregation: possible mediation by a hemoprotein.

    PubMed

    Jamaluddin, M P; Krishnan, L K; Thomas, A

    1988-05-31

    Ajoene, an organosulfur compound derived from garlic, was found by spectral measurements, to interact, cooperatively, with a purified hemoprotein implicated, previously, in platelet activation. It modified the binding interactions of the protein with ligands, deemed to be physiologically relevant as effectors. The characteristics of the modifications were found to parallel those of ajoene induced modifications of agonist-induced aggregation kinetics of gel-filtered calf platelets.

  11. Cardamom extract as inhibitor of human platelet aggregation.

    PubMed

    Suneetha, W Jessie; Krishnakantha, T P

    2005-05-01

    The inhibitory activity of cardamom extract was studied on human platelets. Platelet aggregation and lipid peroxidation were evaluated with platelet rich plasma (PRP) and platelet membranes, respectively, obtained from blood of healthy volunteers. Human platelets were subjected to stimulation with a variety of agonists including ADP (2.5 mM), epinephrine (2.5 mM), collagen (10 mM), calcium ionophore A 23187 (6 microM) and ristocetin (1.25 microg/mL). The IC50 were 0.49, 0.21, 0.55 and 0.59 mg with ADP, epinephrine, collagen and calcium ionophore A 23187, respectively, and no inhibition with ristocetin. The inhibitory effect was dose dependent with concentrations varying between 0.14 and 0.70 mg and time dependent at IC50. Lipid peroxidation induced by iron--ascorbic acid system in platelet membranes was analysed with malondialdehyde (MDA) as an index. An increase in concentration of cardamom has decreased the MDA formation significantly. Hence, it may be said that aqueous extract of cardamom may have component(s), which protect platelets from aggregation and lipid peroxidation.

  12. Sustained increase in platelet aggregation after the cessation of clopidogrel.

    PubMed

    Djukanovic, Nina; Todorovic, Zoran; Zamaklar-Trifunovic, Danijela; Protic, Dragana; Dzudovic, Boris; Ostojic, Miodrag; Obradovic, Slobodan

    2016-02-01

    This study shows that the abrupt cessation of one-year clopidogrel treatment was not associated with thrombotic events in a prospective, multicentre study that enrolled 200 patients subjected to coronary stent implantation and treated with aspirin + clopidogrel 1 year after the stent placement. The aim of the study was to investigate the causes of a sustained increase of platelet aggregability, considering that the values of platelet aggregation stimulated with ADP + PGE1 (ADPHS values) significantly increased 10-90 days after the cessation of clopidogrel. Values of platelet aggregation induced by thrombin receptor activating peptide (TRAP values) and arachidonic acid (ASPI values) were divided into quartiles on the basis of ADPHS values 10 days after stopping clopidogrel (ADPHS10 ). There was a significant difference between TRAP values divided into quartiles according to ADPHS10 , 10, 45 and 90 days after stopping clopidogrel (P < 0.001, all), and ASPI values across the same quartiles 10 and 45 days after the cessation of clopidogrel (P = 0.028 and 0.003). The results of the study indicate that patients with early pronounced rebound phenomena to clopidogrel termination have a long-term (at least 90 days) increased platelet aggregation to other agonists such as thrombin-related activated protein and arachidonic acid, suggesting the complex mutual relationship of various factors/agonists influencing the function of platelets. PMID:26515635

  13. Platelet leukocyte aggregates and markers of platelet aggregation, immune activation and disease progression in HIV infected treatment naive asymptomatic individuals.

    PubMed

    Nkambule, Bongani B; Davison, Glenda; Ipp, Hayley

    2015-11-01

    Platelet aggregates play a crucial role in the immune defence mechanism against viruses. Increased levels of lipopolysaccharide have been reported in human immunodeficiency virus (HIV) infected individuals. Platelets are capable of interacting with bacterial LPS and subsequently forming platelet leukocyte aggregates (PLAs). This study aimed at determining the levels of circulating PLAs in treatment naïve HIV infected individuals and correlating them, with markers of immune activation, disease progression and platelet aggregation. Thirty-two HIV negative and 35 HIV positive individuals were recruited from a clinic in the Western Cape. Platelet monocyte and platelet neutrophil aggregates were measured using flow cytometry at baseline and were correlated with markers of platelet activation (CD62P); aggregation (CD36); monocyte and neutrophil activation (CD69); monocyte tissue factor expression (CD142); immune activation (CD38 on T+ cells); D-dimers (a marker of active coagulation); CD4 count and viral load. Platelet monocyte aggregates were also measured post stimulation with lipopolysaccharide. PMA levels were higher in HIV 25.26 (16.16-32.28) versus control 14.12 (8.36-18.83), p = 0.0001. PMAs correlated with %CD38/8 expression (r = 0.54624, p = 0.0155); CD4 count (r = -0.6964, p = 0.0039) viral load (r = 0.633, p < 0.009) and monocyte %CD69 expression (r = 0.757, p = 0.030). In addition the %PMAs correlated with platelet %CD36 (r = 0.606, p = 0.017). The HIV group showed increased levels of %CD62P 5.44 (2.72-11.87) versus control 1.15 (0.19-3.59), p < 0.0001; %CD36 22.53 (10.59-55.15) versus 11.01 (3.69-26.98), p = 0.0312 and tissue factor (CD142) MFI 4.84 (4.01-8.17) versus 1.74 (1.07-9.3), p = 0.0240. We describe increased levels of circulating PMAs which directly correlates with markers of immune activation, disease progression and platelet aggregation in HIV treatment naïve individuals.

  14. Platelet activation and platelet-monocyte aggregate formation contribute to decreased platelet count during acute simian immunodeficiency virus infection in pig-tailed macaques.

    PubMed

    Metcalf Pate, Kelly A; Lyons, Claire E; Dorsey, Jamie L; Shirk, Erin N; Queen, Suzanne E; Adams, Robert J; Gama, Lucio; Morrell, Craig N; Mankowski, Joseph L

    2013-09-01

    Platelets are key participants in innate immune responses to pathogens. As a decrease in circulating platelet count is one of the initial hematologic indicators of human immunodeficiency virus (HIV) infection, we sought to determine whether decline in platelet number during acute infection results from decreased production, increased antibody-mediated destruction, or increased platelet activation in a simian immunodeficiency virus (SIV)/macaque model. During acute SIV infection, circulating platelets were activated with increased surface expression of P-selection, CD40L and major histocompatibility complex class I. Platelet production was maintained and platelet autoantibodies were not detected during acute infection. Concurrent with a decrease in platelet numbers and an increase in circulating monocytes, platelets were found sequestered in platelet-monocyte aggregates, thereby contributing to the decline in platelet counts. Because the majority of circulating CD16(+) monocytes formed complexes with platelets during acute SIV infection, a decreased platelet count may represent platelet participation in the innate immune response to HIV.

  15. 21 CFR 864.5700 - Automated platelet aggregation system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Automated platelet aggregation system. 864.5700 Section 864.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  16. 21 CFR 864.5700 - Automated platelet aggregation system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Automated platelet aggregation system. 864.5700 Section 864.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  17. 21 CFR 864.5700 - Automated platelet aggregation system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Automated platelet aggregation system. 864.5700 Section 864.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  18. 21 CFR 864.5700 - Automated platelet aggregation system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Automated platelet aggregation system. 864.5700 Section 864.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  19. 21 CFR 864.5700 - Automated platelet aggregation system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Automated platelet aggregation system. 864.5700 Section 864.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  20. Hemostatic Mechanisms, Independent of Platelet Aggregation, Arrest Gastric Mucosal Bleeding

    NASA Astrophysics Data System (ADS)

    Whittle, Brendan J. R.; Kauffman, Gordon L.; Moncada, Salvador

    1986-08-01

    Platelet adhesion, aggregation, and subsequent plug formation play a major role in the control of cutaneous and vascular hemostasis. Little is known, however, about the hemostatic processes in gastric mucosal tissue. A method for evaluating bleeding from a standard incision in the gastric mucosa of the rat, rabbit, and dog has therefore been developed. By using pharmacological agents that interfere with platelet aggregation and blood coagulation, the mechanism of gastric hemostasis has been compared to that in the vasculature, using the rat mesenteric artery. Intravenous infusion of prostacyclin (0.5 μ g\\cdot kg-1\\cdot min-1), which inhibits platelet aggregation directly, or administration of the thromboxane synthase inhibitor 1-benzylimidazole (50 mg\\cdot kg-1) significantly prolonged bleeding in the mesenteric artery yet failed to alter gastric mucosal bleeding. In contrast, a low dose of heparin (100 units\\cdot kg-1), which interferes with the clotting process, had no effect on mesenteric bleeding but substantially prolonged bleeding from the gastric mucosa. These findings suggest that, unlike in the skin or vasculature, platelet aggregation plays a minimal role in the initial hemostatic events in the gastric mucosa and that the arrest of gastric hemorrhage is brought about largely by processes primarily involving the coagulation system.

  1. Antithrombotic activity of Vitis labrusca extract on rat platelet aggregation.

    PubMed

    Kwon, Se-Uk; Lee, Hoon-Yeon; Xin, Mingjie; Ji, Su-Jeong; Cho, Hyoung-Kwon; Kim, Dae-Sung; Kim, Dae-Ki; Lee, Young-Mi

    2016-03-01

    Vitis labrusca is a grapevine that has antioxidant, neuroprotective, hepatoprotective, and anticarcinogenic activity. However, the antithrombotic effect of Vitis labrusca leaves on platelets is yet to be ascertained. We investigated the inhibitory effect of V. labrusca leaf extract (VLE) on platelet aggregation in vitro and ex vivo. The thromboxane B2 (TXB2) and serotonin concentrations were measured by ELISA. The flavonoids content was measured by ultraperformance liquid chromatography (UPLC). The antithrombotic activity of VLE was evaluated using various agonists in vitro. VLE strongly inhibited adenosine diphosphate (ADP)-induced platelet aggregation. In rats, VLE treatment (100 mg/kg) reduced ADP-stimulated platelet aggregation, without affecting tail bleeding and coagulation time. Moreover, VLE significantly suppressed TXB2 and serotonin secretion. UPLC analysis indicated that VLE contains quercetin, isorhamnetin, and rutin. Our results indicate that VLE possesses antiplatelet activity via the suppression of TXB2 and serotonin, without affecting bleeding. Further, we identified the flavonoids present in VLE. Thus, VLE may be a potential agent for the prevention of cardiovascular diseases. PMID:26340455

  2. Reduced platelet aggregation in a boy with scurvy.

    PubMed

    Dey, F; Möller, A; Kemkes-Matthes, B; Wilbrand, J-F; Krombach, G A; Neubauer, B; Hahn, A

    2012-11-01

    Pediatric scurvy is a rare condition characterized by perifollicular petechiae and bruising, hemorrhagic gingivitis and musculoskeletal symptoms, all assumed to be predominantly related to abnormal collagen structure. We report on a 9-year-old autistic boy with vitamin C deficiency due to a highly limited food range presenting with multiple petechiae, gum bleeding and debilitating bone pain, in whom platelet aggregometry revealed a distinctly reduced thrombocyte aggregation, normalizing after vitamin C supplementation. This observation indicates that platelet dysfunction may additionally contribute to the hemorrhagic diathesis in scurvy, and demonstrates that ascorbic acid deficiency should be considered in children with an otherwise unexplained acquired thrombocytopathy. PMID:23070864

  3. Reduced platelet aggregation in a boy with scurvy.

    PubMed

    Dey, F; Möller, A; Kemkes-Matthes, B; Wilbrand, J-F; Krombach, G A; Neubauer, B; Hahn, A

    2012-11-01

    Pediatric scurvy is a rare condition characterized by perifollicular petechiae and bruising, hemorrhagic gingivitis and musculoskeletal symptoms, all assumed to be predominantly related to abnormal collagen structure. We report on a 9-year-old autistic boy with vitamin C deficiency due to a highly limited food range presenting with multiple petechiae, gum bleeding and debilitating bone pain, in whom platelet aggregometry revealed a distinctly reduced thrombocyte aggregation, normalizing after vitamin C supplementation. This observation indicates that platelet dysfunction may additionally contribute to the hemorrhagic diathesis in scurvy, and demonstrates that ascorbic acid deficiency should be considered in children with an otherwise unexplained acquired thrombocytopathy.

  4. Aspirin sensitivity of platelet aggregation in diabetes mellitus.

    PubMed

    Albert, Stewart G; Hasnain, Bibi I; Ritter, Detlef G; Joist, J Heinrich; Mooradian, Arshag D

    2005-11-01

    Although aspirin is cardioprotective in high-risk populations, many with diabetes mellitus (DM) are unresponsive to these benefits. We questioned whether cardiovascular unresponsiveness might be demonstrated by lack of aspirin sensitivity to in vitro platelet functions especially in subjects with poorly controlled diabetes. Six women and 4 men (48+/-8 years [mean+/-S.D.]), selected for poor control (glycohemoglobin 11.9+/-2.2%) and 10 sex-age (+/-5 years) matched controls received 81 mg aspirin daily. There was a 2-week washout from aspirin and related drugs. After the aspirin dose on day-7, blood for platelet aggregation assays, and 24-h urine for 2,3 dinor thromboxane B2 (TxB2) and 2,3 dinor 6-keto (PGF1alpha) were obtained. Aspirin sensitivity was defined as inhibition (i.e., lower than expected) platelet aggregation after exposure to an agonist. Those with diabetes and controls were sensitive to aspirin inhibition of platelet aggregation induced by 1.6 mM arachidonic acid (9.5+/-3.9% versus 9.1+/-3.1%, normal range 40-100%) and by 0.83 microg/mL collagen (17.4+/-13.9% versus 13.2+/-9.3%, normal range 60-93%), respectively. Aspirin sensitivity to 2 microM ADP was present in five with diabetes and five controls. Urinary prostaglandin metabolites were suppressed below reference ranges, without differences between those with DM or controls for TxB2 (350+/-149 pg/mg versus 348+/-93 pg/mg creatinine) and PGF1alpha (255+/-104 pg/mg versus 222+/-88 pg/mg creatinine). In conclusion, in poorly controlled diabetes, there was no differential lack of aspirin sensitivity to platelet aggregation, or lack of aspirin suppression of urinary TxB2 or PGF1alpha, compared with controls on aspirin. Despite suppression of urinary prostaglandin metabolites, aspirin resistance was most apparent to ADP-mediated platelet aggregation. It is not known what level of inhibition of in vitro tests is necessary for the cardioprotective benefits of aspirin in diabetes mellitus. Thus, the lack of

  5. Scalable evaluation of platelet aggregation by the degree of blood migration

    NASA Astrophysics Data System (ADS)

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-12-01

    Platelet aggregation plays a key role in vascular thrombosis. Antiplatelet drug therapy is commonly used for the prevention of abnormal platelet aggregation. So, measuring platelet aggregation function is critically important in clinical field. Here, we introduce a scalable evaluation method of platelet aggregation measured with the degree of blood migration through microchannel in a microfluidic chip. Unlike conventional methods that require expertise with system physics to operate devices, our approach is using microfluidics system, which requires only a syringe vacuum. The scalable migration factors, migration distance and touchdown time, are capable of distinguishing various antiplatelet drug effects under microfluidics and would be effective for the quick and easy evaluation of quantitative platelet aggregation.

  6. Effects of argon laser on in vitro aggregation of platelets in platelet rich plasma and whole blood

    SciTech Connect

    Doerger, P.T.; Glueck, H.I.; McGill, M.

    1988-06-01

    The effects of an Argon laser on platelet aggregation were studied, since platelets may be exposed to laser energy when used intravascularly. Various preparations of platelets in platelet rich plasma (PRP) and whole blood, with or without aspirin, were tested with the aggregating agents ADP, collagen, thrombin, and epinephrine. Simultaneous release of ATP was also measured in PRP. At relatively low levels of irradiation, platelet aggregation was potentiated. Enhancement was evidenced by an increase in percent aggregation, earlier onset of the reaction, and reduction in the amount of aggregating agent required. In PRP, the mechanism of laser potentiation appeared to be the release of endogenous ATP from platelets. At relatively high levels of irradiation, platelets were destroyed and aggregation abolished. In whole blood, the mechanism was somewhat more complicated since release of ATP occurred from RBCs as well as platelets. Spontaneous aggregation following laser treatment occurred in isolated instances in PRP and in every trial in whole blood preparations. Aspirin ingestion inhibited the laser's effects in PRP but not in whole blood. These results may have important clinical implications for laser angioplasty, and the potentiated aggregation response may prove useful in laboratory studies of platelet function.

  7. von Willebrand factor binds to platelets and induces aggregation in platelet-type but not type IIB von Willebrand disease.

    PubMed Central

    Miller, J L; Kupinski, J M; Castella, A; Ruggeri, Z M

    1983-01-01

    Platelet-type von Willebrand disease (vWD) and pseudo-vWD are two recently described intrinsic platelet defects characterized by enhanced ristocetin-induced agglutination in platelet-rich plasma. A similar finding is also typical of type IIB vWD, where it has been related to a von Willebrand factor (vWF) rather than a platelet abnormality. Platelet aggregation induced by unmodified human vWF in the absence of other stimuli has been reported in pseudo-vWD. In this study we demonstrate that vWF induces aggregation in platelet-type but not type IIB vWD. Aggregation is observed when normal plasma cryoprecipitate or purified vWF are added to platelet-rich plasma. Cryoprecipitate also aggregates washed platelets, although at higher concentrations than required for platelet-rich plasma. Purified vWF, however, induces significant aggregation of washed platelets only when plasma is added. EDTA inhibits vWF-induced aggregation. Its effect can be overcome by calcium but much less effectively by magnesium ions. Unstimulated platelets in platelet-rich plasma from patients with platelet-type but not type IIB vWD bind 125I-vWF in a specific and saturable manner. All different sized multimers of vWF become associated with platelets. Both aggregation and binding exhibit a similar vWF concentration dependence, suggesting that a correlation exists between these two events. Removal of ADP by appropriate consuming systems is without effect upon such binding or upon vWF-induced aggregation. Thrombin-induced 125I-vWF binding to washed platelets is normal in platelet-type as well as type IIB vWD. These results demonstrate that a specific binding site for unmodified human vWF is exposed on unstimulated platelets in platelet-type vWD. The relatively high vWF concentrations required for aggregation and binding may explain the lack of significant in vivo aggregation and thrombocytopenia in these patients. Moreover, these studies provide additional evidence that platelet-type and type IIB v

  8. Platelet anti-aggregant property of some Moroccan medicinal plants.

    PubMed

    Mekhfi, Hassane; El Haouari, Mohammed; Legssyer, Abdelkhaleq; Bnouham, Mohammed; Aziz, Mohammed; Atmani, Fouad; Remmal, Adnane; Ziyyat, Abderrahim

    2004-10-01

    It is known that blood platelets may present some dysfunction linked to cardiovascular pathologies such as arterial hypertension. The aim of this work is to examine the in vitro anti-aggregant effect of five medicinal plants among which three were reported as antihypertensive in oriental Morocco: Arbutus unedo (Ericaceae), Urtica dioïca (Urticaceae), and Petroselinum crispum (Apiaceae). The two other plants were Cistus ladaniferus (Cistaceae) and Equisetum arvense (Equisetaceae). The results obtained showed that all extracts produced a dose-dependent inhibition of thrombin and ADP-induced aggregation. The calculated IC50 (half-maximal inhibition of thrombin and ADP-induced aggregation) was found to be identical in all plant extracts while Urtica dioïca had a higher IC50 value. The effect of plants could be related in part to the polyphenolic compounds present in their extracts suggesting their involvement in the treatment or prevention of platelet aggregation complications linked to cardiovascular diseases. Phytochemical separation must be carried out to identify the active principles responsible for the anti-aggregant effect and elucidate their mechanisms of action. PMID:15325737

  9. Increased platelet aggregation and in vivo platelet activation after granulocyte colony-stimulating factor administration. A randomised controlled trial.

    PubMed

    Spiel, Alexander O; Bartko, Johann; Schwameis, Michael; Firbas, Christa; Siller-Matula, Jolanta; Schuetz, Matthias; Weigl, Manuela; Jilma, Bernd

    2011-04-01

    Granulocyte colony-stimulating factor (G-CSF) stimulates the bone marrow to produce granulocytes and stem cells and is widely used to accelerate neutrophil recovery after chemotherapy. Interestingly, specific G-CSF receptors have been demonstrated not only on myeloid cells, but also on platelets. Data on the effects of G-CSF on platelet function are limited and partly conflicting. The objective of this study was to determine the effect of G-CSF on platelet aggregation and in vivo platelet activation. Seventy-eight, healthy volunteers were enrolled into this randomised, placebo-controlled trial. Subjects received 5 μg/kg methionyl human granulocyte colony-stimulating factor (r-metHuG-CSF, filgrastim) or placebo subcutaneously for four days. We determined platelet aggregation with a whole blood impedance aggregometer with various, clinically relevant platelet agonists (adenosine diphosphate [ADP], collagen, arachidonic acid [AA], ristocetin and thrombin receptor activating peptide 6 [TRAP]). Filgrastim injection significantly enhanced ADP (+40%), collagen (+60%) and AA (+75%)-induced platelet aggregation (all p<0.01 as compared to placebo and p<0.001 as compared to baseline). In addition, G-CSF enhanced ristocetin-induced platelet aggregation (+18%) whereas TRAP-induced platelet aggregation decreased slightly (-14%) in response to filgrastim. While baseline aggregation with all agonists was only slightly but insignificantly higher in women than in men, this sex difference was enhanced by G-CSF treatment, and became most pronounced for ADP after five days (p<0.001). Enhanced platelet aggregation translated into a 75% increase in platelet activation as measured by circulating soluble P-selectin. G-CSF enhances platelet aggregation and activation in humans. This may put patients suffering from cardiovascular disease and cancer at risk for thrombotic events. PMID:21301783

  10. In vitro effects of ethanol on the pathways of platelet aggregation

    SciTech Connect

    Rand, M.L.; Kinlough-Rathbone, R.L.; Packham, M.A.; Mustard, J.F.

    1986-03-01

    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 ..mu..M) was not affected by ethanol, at concentrations up to 5 mg/ml (lethal). Primary ADP-induced (5 ..mu..M) 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 ..mu..M) 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 ..mu.. 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.

  11. Intravascular filarial parasites inhibit platelet aggregation. Role of parasite-derived prostanoids.

    PubMed Central

    Liu, L X; Weller, P F

    1992-01-01

    The nematode parasites that cause human lymphatic filariasis survive for long periods in their vascular habitats despite continual exposure to host cells. Platelets do not adhere to blood-borne microfilariae, and thrombo-occlusive phenomena are not observed in patients with circulating microfilariae. We studied the ability of microfilariae to inhibit human platelet aggregation in vitro. Brugia malayi microfilariae incubated with human platelets caused dose-dependent inhibition of agonist-induced platelet aggregation, thromboxane generation, and serotonin release. As few as one microfilaria per 10(4) platelets completely inhibited aggregation of platelets induced by thrombin, collagen, arachidonic acid, or ionophore A23187. Microfilariae also inhibited aggregation of platelets in platelet-rich plasma stimulated by ADP, compound U46619, or platelet-activating factor. The inhibition required intimate proximity but not direct contact between parasites and platelets, and was mediated by parasite-derived soluble factors of low (less than 1,000 Mr) molecular weight that were labile in aqueous media and caused an elevation of platelet cAMP. Prior treatment of microfilariae with pharmacologic inhibitors of cyclooxygenase decreased both parasite release of prostacyclin and PGE2 and microfilarial inhibition of platelet aggregation. These results indicate that microfilariae inhibit platelet aggregation, via mechanisms that may include the elaboration of anti-aggregatory eicosanoids. Images PMID:1313445

  12. Platelets aggregation in pathological conditions: role of local shear rates and platelet activation delay time.

    NASA Astrophysics Data System (ADS)

    Li, He; Zarif Khalili Yazdani, Alireza; Karniadakis, George

    2015-11-01

    Platelets play an essential role in the initiation and formation of a thrombus, however their detailed motion in blood vessels with complex geometries, such as in the aneurysmal vessel or stenotic vessel in atherosclerosis, has not been studied systematically. Here, we perform spectral element simulations (NEKTAR code) to obtain the 3D flow field in blood vessel with cavities, and we apply the force coupling method (FCM) to simulate the motion of platelets in blood flow. Specifically, simulations of platelets are performed in a 0.25 mm diameter circular blood vessel with 1 mm length. Corresponding coarse-grained molecular dynamics simulations are employed to provide input to the NEKTAR-FCM code. Simulations are conducted at several different Reynolds numbers (Re). An ellipsoid-shaped cavity is selected to intersect with the middle part of the circular vessel to represent the aneurysmal part of the blood vessel. Based on the simulation results, we quantify how the platelets motion and aggregation in the blood vessel cavities depend on Re, platelet activation delay time, and the geometry of the cavities.

  13. Effect of supine exercise on platelet aggregation and fibrinolytic activity.

    PubMed

    Dag, B; Gleerup, G; Bak, A M; Hindberg, I; Mehlsen, J; Winther, K

    1994-03-01

    In 12 healthy young men, strenuous cycling exercise in the supine position, caused platelet aggregability to decrease and the ADP threshold to rise from 7.0 microM resting, to 9.5 exercising (P < 0.01). At the same time, fibrinolytic activity increased markedly: euglobulin clot lysis time shortened from 178 to 68 min, PAI-1 fell from 8.91 to 5.16 IU ml-1, and t-PA rose from 0.56 to 3.95 IU ml-1, all three values were significant to P < 0.01. When the erect posture was assumed after lying at ease for 1 h after exercise, it did not increase platelet activity as expected, but caused a modest increase of fibrinolytic activity. These results suggest that supine exercise will not affect the haemostatic system adversely.

  14. Amorphous silica nanoparticles aggregate human platelets: potential implications for vascular homeostasis

    PubMed Central

    Corbalan, J Jose; Medina, Carlos; Jacoby, Adam; Malinski, Tadeusz; Radomski, Marek W

    2012-01-01

    Background Amorphous silica nanoparticles (SiNP) can be used in medical technologies and other industries leading to human exposure. However, an increased number of studies indicate that this exposure may result in cardiovascular inflammation and damage. A high ratio of nitric oxide to peroxynitrite concentrations ([NO]/[ONOO−]) is crucial for cardiovascular homeostasis and platelet hemostasis. Therefore, we studied the influence of SiNP on the platelet [NO]/[ONOO−] balance and platelet aggregation. Methods Nanoparticle–platelet interaction was examined using transmission electron microscopy. Electrochemical nanosensors were used to measure the levels of NO and ONOO− released by platelets upon nanoparticle stimulation. Platelet aggregation was studied using light aggregometry, flow cytometry, and phase contrast microscopy. Results Amorphous SiNP induced NO release from platelets followed by a massive stimulation of ONOO− leading to an unfavorably low [NO]/[ONOO−] ratio. In addition, SiNP induced an upregulation of selectin P expression and glycoprotein IIb/IIIa activation on the platelet surface membrane, and led to platelet aggregation via adenosine diphosphate and matrix metalloproteinase 2-dependent mechanisms. Importantly, all the effects on platelet aggregation were inversely proportional to nanoparticle size. Conclusions The exposure of platelets to amorphous SiNP induces a critically low [NO]/[ONOO−] ratio leading to platelet aggregation. These findings provide new insights into the pharmacological profile of SiNP in platelets. PMID:22334785

  15. Multiple electrode aggregometry: a new device to measure platelet aggregation in whole blood.

    PubMed

    Tóth, Orsolya; Calatzis, Andreas; Penz, Sandra; Losonczy, Hajna; Siess, Wolfgang

    2006-12-01

    Several methods are used to analyse platelet function in whole blood. A new device to measure whole blood platelet aggregation has been developed, called multiple electrode platelet aggregometry (MEA). Our aim was to evaluate MEA in comparison with the single platelet counting (SPC) method for the measurement of platelet aggregation and platelet inhibition by aspirin or apyrase in diluted whole blood. Platelet aggregation induced by different concentrations of ADP, collagen and TRAP-6 and platelet inhibition by apyrase or aspirin were determined in citrateor hirudin-anticoagulated blood by MEA and SPC. MEA indicated that spontaneous platelet aggregation was lower, and stimulated platelet aggregation was higher in hirudin- than citrate-anticoagulated blood. In hirudin-anticoagulated, but not citrate-anticoagulated blood, spontaneous platelet aggregation measured by MEA was inhibited by apyrase. For MEA compared with SPC the dose response-curves of agonist-induced platelet aggregation in citrate- and hirudin-blood showed similar EC50 values for TRAP, and higher EC50 values for ADP (non-significant) and collagen (p < 0.05). MEA and the SPC method gave similar results concerning platelet-inhibition by apyrase and aspirin. MEA was more sensitive than SPC to the inhibitory effect of aspirin in collagen-induced aggregation. In conclusion, MEA is an easy, reproducible and sensitive method for measuring spontaneous and stimulated platelet aggregation, and evaluating antiplatelet drugs in diluted whole blood. The use of hirudin as an anticoagulant is preferable to the use of citrate. MEA is a promising technique for experimental and clinical applications. PMID:17139373

  16. Platelet aggregation monitoring with a newly developed quartz crystal microbalance system as an alternative to optical platelet aggregometry.

    PubMed

    Sinn, Stefan; Müller, Lothar; Drechsel, Hartmut; Wandel, Michael; Northoff, Hinnak; Ziemer, Gerhard; Wendel, Hans P; Gehring, Frank K

    2010-11-01

    The objective of this study was to establish a new test system for the monitoring of platelet aggregation during extracorporeal circulation (ECC) procedures. Even though extensive progress has been made in improving the haemocompatibility of extracorporeal circulation devices, activation of blood coagulation, blood platelets and inflammatory responses are still undesired outcomes of cardiopulmonary bypass. This study deals with an approach towards a platelet aggregation measuring system using a newly developed quartz crystal microbalance (QCM) system. Since QCM is a rarely used technique in the field of blood analytics, the challenge was to transfer the well established methods of aggregometry to the new test system. In a QCM system, either bare gold or fibrinogen-coated sensors were incubated with ADP or arachidonic acid (AA) stimulated platelet rich plasma. For negative controls the GPIIb/IIIa inhibitory antibody abciximab (Reopro®) was used as an inhibitor of platelet aggregation. During incubation, the frequency shifts of the sensors were recorded. The results gained from the QCM system were compared to results gained by optical platelet aggregometry (born aggregometry). For additional visualization of platelet adhesion to the sensor surfaces, fluorescent microscopy and scanning electron microscopy were used. The QCM sensor was able to detect platelet aggregation in both uncoated and fibrinogen coated sensors. The measuring curves of aggregation measurements and controls were clearly distinguishable from each other in terms of frequency shifts and kinetics. For aggregation measurements and inhibited controls the therapeutic diagnosis of platelet function is identical between aggregometer and QCM data. In future, QCM based measuring devices may become an alternative to established point of care methods for rapid bedside testing of platelet aggregation.

  17. [Effect of troxerutin and cerebroproptein hydrolysate injection on platelet aggregation and thrombosis].

    PubMed

    Chen, Qiu-Chen; Yu, Zhao-Jin; Sun, Hai-Gang; Yu, Jian-Kun; Wei, Min-Jie

    2011-02-01

    This study was purposed to explore the effect of troxerotin and cerebroproptein hydrolysate injection (TCHI) on platelet aggregation in vitro and thrombosis in vivo. The inhibitory rate of TCHI at different concentrations on platelet aggregation was determined by platelet aggregometer. The relationship between dose and effect was established. The effect of troxerutin and cerebroproptein hydrolysate injection on thrombosis was determined by the carotid thrombosis model of rats. The results showed that the TCHI could inhibit thrombosis and platelet aggregation in a concentration-dependent way. When the concentration of TCHI total nitrogen was 5 µg/ml, the inhibition rate of platelet aggregation reached to the highest value of 28.61 ± 22.07%, which is 2.5 times as much as that with 100 µg/ml aspirin. It is concluded that the TCHI has antiaggregative and antithrombotic activity effects against platelet aggregation and thrombosis.

  18. Involvement of Nitric Oxide on Calcium Mobilization and Arachidonic Acid Pathway Activation during Platelet Aggregation with different aggregating agonists

    PubMed Central

    Banerjee, Debipriya; Mazumder, Sahana; Kumar Sinha, Asru

    2016-01-01

    Platelet aggregation by different aggregating agonists is essential in the normal blood coagulation process, the excess of which caused acute coronary syndrome (ACS). In all cases, the activation of arachidonic acid by cycloxygenase was needed for the synthesis of thromboxane A2 (TXA2) but the mechanism of arachidonic acid release in platelets remains obscure. Studies were conducted to determine the role of nitric oxide (NO), if any, on the release of arachidonic acid in platelets. The cytosolic Ca2+ was visualized and quantitated by fluorescent spectroscopy by using QUIN-2. NO was measured by methemoglobin method. Arachidonic acid was determined by HPLC. TXA2 was measured as ThromboxaneB2 (TXB2) by ELISA. Treatment of platelets in platelet-rich plasma (PRP) with different aggregating agents resulted in the inhibition of nitric oxide synthase (NOS) which inhibited the production of NO synthesis and increased TXA2 synthesis. Furthermore, the treatment of washed PRP with different platelet aggregating agents resulted in the increase of [Ca2+] in nM ranges. In contrast, the pre-treatment of washed PRP with aspirin increased platelet NO level and inhibited the Ca2+ mobilization and TXA2 synthesis. These results indicated that the aggregation of platelets by different aggregating agonists was caused by the cytosolic Ca2+ mobilization due to the inhibition of NOS. PMID:27127451

  19. Platelet-Rich Plasma in Treatment of Zoledronic Acid-Induced Bisphosphonate-related Osteonecrosis of the Jaws

    PubMed Central

    Sarkarat, Farzin; Kalantar Motamedi, Mohammad Hosein; Jahanbani, Jahanfar; Sepehri, Dena; Kahali, Roozbeh; Nematollahi, Zahra

    2014-01-01

    Background: Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a well-known challenging entity warranting management. Platelet-Rich Plasma (PRP) plays an important role in bone biology by enhancing bone repair and regeneration. Objectives: The aim of this animal study was to evaluate the effects of PRP on zoledronic acid-induced BRONJ. Materials and Methods: Seven rats were given 0.04 mg Zoledronic acid intravenously once a week for five weeks. Two weeks later, the animals underwent extraction of their first lower molars, bilaterally. After clinical confirmation of the osteonecrosis, PRP was injected randomly into one of the extraction sockets of each rat. Three weeks later, all rats were sacrificed in order to obtain histological sections. The analysis of epithelialization was performed by McNamar’s test, and the analysis of osteogenesis and angiogenesis was performed by the Wilcoxon Sign Rank test. P value was set at 0.05. Results: We found no significant differences between the two groups regarding the amount of epithelialization, angiogenesis or sequestrum formation (P > 0.05), but a significant difference was seen between the two groups regarding the amount of existing vital bone (P < 0.05). Conclusions: Our study demonstrates positive results (preservation or regeneration of bone) using PRP in treatment of BRONJ. Although PRP may enhance osseous regeneration, long-term follow-ups are required to confirm its benefits. PMID:25032151

  20. Heat shock protein 70 regulates platelet integrin activation, granule secretion and aggregation.

    PubMed

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

    2016-04-01

    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.

  1. Mediterranean wild plants reduce postprandial platelet aggregation in patients with metabolic syndrome.

    PubMed

    Fragopoulou, Elizabeth; Detopoulou, Paraskevi; Nomikos, Tzortzis; Pliakis, Emmanuel; Panagiotakos, Demosthenes B; Antonopoulou, Smaragdi

    2012-03-01

    Postprandial platelet hyperactivity and aggregation play a crucial role in the pathogenesis of metabolic syndrome. The purpose of the present study was to evaluate the effect of boiled wild plants consumption on the postprandial platelet aggregation in metabolic syndrome patients. Patients consumed 5 meals in a random order (ie, 4 wild plant meals, namely, Reichardia picroides [RP], Cynara cardunculus, Urospermum picroides [UP], and Chrysanthemum coronarium, and a control meal, which contained no wild plants). Several biochemical indices as well as platelet activating factor (PAF)- and adenosine diphosphate-induced ex vivo platelet aggregation were measured postprandially. Moreover, the ability of plants extract to inhibit rabbit platelet aggregation was tested in vitro. The consumption of RP and UP meals significantly reduced ex vivo adenosine diphosphate-induced postprandial platelet aggregation compared with the control meal. The consumption of UP meals significantly reduced the ex vivo PAF-induced platelet aggregation postprandially. Both UP and RP extracts significantly inhibited PAF-induced rabbit platelet aggregation in vitro. Wild plants consumption reduced postprandial platelet hyperaggregability of metabolic syndrome patients, which may account for their healthy effects. PMID:21944262

  2. Inhibiting platelets aggregation could aggravate the acute infection caused by Staphylococcus aureus.

    PubMed

    Zhang, Xin; Liu, Yu; Gao, Yaping; Dong, Jie; Mu, Chunhua; Lu, Qiang; Shao, Ningsheng; Yang, Guang

    2011-01-01

    Several fibrinogen binding proteins (Fibs) play important roles in the pathogenesis of Staphylococcus aureus (S. aureus). Most Fibs can promote the aggregation of platelets during infection, but the extracellular fibrinogen-binding protein (Efb) is an exception. It is reported that Efb can specifically bind fibrinogen and inhibit the aggregation of platelet with its N terminal. However, the biological significance of platelet aggregation inhibition in the infection caused by S. aureus is unclear until now. Here, we demonstrated that the persistence and aggregation of platelets were important for killing S. aureus in whole blood. It was found that the N terminal of Efb (EfbN) and platelets inhibitors could increase the survival of S. aureus in whole blood. The study in vivo also showed that EfbN and platelets inhibitors could reduce the killing of S. aureus and increase the lethality rate of S. aureus in the acute infection mouse model.

  3. Platelet–cancer interactions: mechanisms and pharmacology of tumour cell-induced platelet aggregation

    PubMed Central

    Jurasz, Paul; Alonso-Escolano, David; Radomski, Marek W

    2004-01-01

    During haematogenous metastasis, cancer cells migrate to the vasculature and interact with platelets resulting in tumour cell-induced platelet aggregation (TCIPA). We review: The biological and clinical significance of TCIPA; Molecular mechanisms involved in platelet aggregation by cancer cells; Strategies for pharmacological regulation of these interactions. We conclude that pharmacological regulation of platelet–cancer cell interactions may reduce the impact of TCIPA on cancer biology. PMID:15492016

  4. Inhalation of Whole Diesel Exhaust but not Gas-Phase Components Affects In Vitro Platelet Aggregation in Hypertensive Rats

    EPA Science Inventory

    Rationale: Intravascular thrombosis and platelet aggregation are enhanced following exposure to diesel exhaust (DE) and other respirable particulate matter; however, the roles of endothelial and circulating mediators on platelet aggregation remain unclear. We hypothesized that ad...

  5. Parsley extract inhibits in vitro and ex vivo platelet aggregation and prolongs bleeding time in rats.

    PubMed

    Gadi, Dounia; Bnouham, Mohamed; Aziz, Mohammed; Ziyyat, Abderrahim; Legssyer, Abdelkhaleq; Legrand, Chantal; Lafeve, Françoise Fauvel; Mekhfi, Hassane

    2009-08-17

    Many cardiovascular diseases are associated with an increase in blood platelet activity. In Morocco, parsley (Petroselinum crispum, Apiaceae) is one of the medicinal herbs used to treat cardiovascular diseases such as arterial hypertension. In this study, crude aqueous extract (CAE) of parsley was evaluated for its anti-platelet activity in experimental animals on platelet aggregation in vitro and ex vivo; and on bleeding time in vivo. The in vitro aggregation was monitored after pre-incubation of platelets with CAE. The bleeding time and ex vivo aggregation were performed after oral treatment. CAE inhibited dose dependently platelet aggregation in vitro induced by thrombin, ADP, collagen and epinephrine. The oral administration of CAE (3g/kg) inhibited significantly (p<0.001) platelet aggregation ex vivo and prolonged bleeding time (p<0.001) without changes in the platelet amount. The prolongation of bleeding time by CAE may be attributed to the observed inhibition of platelet aggregation. These effects could be related in part to the polyphenolic compounds present in the extract. These results support the hypothesis that the dietary intake of parsley may be benefit in the normalization of platelet hyperactivation, in the nutritional prevention of cardiovascular diseases and are potentially interesting in the development of new prevention strategies.

  6. Effects of acute and chronic psychological stress on platelet aggregation in mice.

    PubMed

    Matsuhisa, Fumikazu; Kitamura, Nobuo; Satoh, Eiki

    2014-03-01

    Although psychological stress has long been known to alter cardiovascular function, there have been few studies on the effect of psychological stress on platelets, which play a pivotal role in cardiovascular disease. In the present study, we investigated the effects of acute and chronic psychological stress on the aggregation of platelets and platelet cytosolic free calcium concentration ([Ca(2+)]i). Mice were subjected to both transportation stress (exposure to novel environment, psychological stress) and restraint stress (psychological stress) for 2 h (acute stress) or 3 weeks (2 h/day) (chronic stress). In addition, adrenalectomized mice were subjected to similar chronic stress (both transportation and restraint stress for 3 weeks). The aggregation of platelets from mice and [Ca(2+)]i was determined by light transmission assay and fura-2 fluorescence assay, respectively. Although acute stress had no effect on agonist-induced platelet aggregation, chronic stress enhanced the ability of the platelet agonists thrombin and ADP to stimulate platelet aggregation. However, chronic stress failed to enhance agonist-induced increase in [Ca(2+)]i. Adrenalectomy blocked chronic stress-induced enhancement of platelet aggregation. These results suggest that chronic, but not acute, psychological stress enhances agonist-stimulated platelet aggregation independently of [Ca(2+)]i increase, and the enhancement may be mediated by stress hormones secreted from the adrenal glands.

  7. A serotonin-induced N-glycan switch regulates platelet aggregation

    PubMed Central

    Mercado, Charles P.; Quintero, Maritza V.; Li, Yicong; Singh, Preeti; Byrd, Alicia K.; Talabnin, Krajang; Ishihara, Mayumi; Azadi, Parastoo; Rusch, Nancy J.; Kuberan, Balagurunathan; Maroteaux, Luc; Kilic, Fusun

    2013-01-01

    Serotonin (5-HT) is a multifunctional signaling molecule that plays different roles in a concentration-dependent manner. We demonstrated that elevated levels of plasma 5-HT accelerate platelet aggregation resulting in a hypercoagulable state in which the platelet surface becomes occupied by several glycoproteins. Here we study the novel hypothesis that an elevated level of plasma 5-HT results in modification of the content of N-glycans on the platelet surface and this abnormality is associated with platelet aggregation. Mass spectrometry of total surface glycoproteins on platelets isolated from wild-type mice infused for 24 hours with saline or 5-HT revealed that the content of glycoproteins on platelets from 5-HT-infused mice switched from predominantly N-acetyl-neuraminic acid (Neu5Ac) to N-glycolyl-neuraminic acid (Neu5Gc). Cytidine monophosphate-N-acetylneuraminate hydroxylase (CMAH) synthesizes Neu5Gc from Neu5Ac. Up-regulation of Neu5Gc content on the platelet surface resulted from an increase in the catalytic function, not expression, of CMAH in platelets of 5-HT-infused mice. The highest level of Neu5Gc was observed in platelets of 5-HT-infused, 5-HT transporter-knock out mice, suggesting that the surface delineated 5-HT receptor on platelets may promote CMAH catalytic activity. These new findings link elevated levels of plasma 5-HT to altered platelet N-glycan content, a previously unrecognized abnormality that may favor platelet aggregation. PMID:24077408

  8. COX, LOX and platelet aggregation inhibitory properties of Lauraceae neolignans.

    PubMed

    Coy, Ericsson David; Cuca, Luis Enrique; Sefkow, Michael

    2009-12-15

    The anti-inflammatory potential of 26 neolignans (14 of the bicyclooctane-type and 12 of the benzofuran-type), isolated from three Lauraceae species (Pleurothyrium cinereum, Ocotea macrophylla and Nectandra amazonum), was evaluated in vitro through inhibition of COX-1, COX-2, 5-LOX and agonist-induced aggregation of rabbit platelets. Benzofuran neolignans were found to be selective COX-2 inhibitors, whereas bicyclooctane neolignans inhibit selectively the PAF-action as well as COX-1 and 5-LOX. The neolignan 9-nor-7,8-dehydro-isolicarin B 15 and cinerin C 7 were found to be the most potent COX-2 inhibitor and PAF-antagonist, respectively. Nectamazin C 10 exhibited dual 5-LOX/COX-2 inhibition. PMID:19880317

  9. Small molecule- and amino acid-induced aggregation of gold nanoparticles.

    PubMed

    Zakaria, Hesham M; Shah, Akash; Konieczny, Michael; Hoffmann, Joan A; Nijdam, A Jasper; Reeves, M E

    2013-06-25

    To understand which organic molecules are capable of binding to gold nanoparticles and/or inducing nanoparticle aggregation, we investigate the interaction of gold nanoparticles with small molecules and amino acids at variable pH. Dynamic Light Scattering (DLS) and ultraviolet-visible (UV-vis) spectra were measured on mixtures of colloidal gold with small molecules to track the progression of the aggregation of gold nanoparticles. We introduce the 522 to 435 nm UV-vis absorbance ratio as a sensitive method for the detection of colloidal gold aggregation, whereby we delineate the ability of thiol, amine, and carboxylic acid functional groups to bind to the surfaces of gold nanoparticles and investigate how combinations of these functional groups affect colloidal stability. We present models for mechanisms of aggregation of colloidal gold, including surface charge reduction and bridging linkers. For all molecules whose addition leads to the aggregation of gold nanoparticles, the aggregation kinetics were accelerated at acidic pH values. Colloidal gold is maintained only in the presence of anionic carboxyl groups, which are neutralized by protonation at lower pH. The overall reduced charge on the stabilizing carboxyl groups accounts for the accelerated aggregation at lower pH values. PMID:23718319

  10. Fibrin formation by staphylothrombin facilitates Staphylococcus aureus-induced platelet aggregation.

    PubMed

    Vanassche, Thomas; Kauskot, Alexandre; Verhaegen, Jan; Peetermans, Willy E; van Ryn, Joanne; Schneewind, Olaf; Hoylaerts, Marc F; Verhamme, Peter

    2012-06-01

    Interactions of Staphylococcus aureus (S. aureus) and platelets play an important role in the pathogenesis of intravascular infections such as infective endocarditis (IE). A typical feature of S. aureus is the ability to generate thrombin activity through the secretion of two prothrombin activating molecules, staphylocoagulase and von Willebrand factor-binding protein (vWbp), which bind to human prothrombin to form the enzymatically active staphylothrombin complex. The role of staphylothrombin in the interaction between S. aureus and platelets has not yet been studied. We found that in contrast with thrombin, staphylothrombin did not directly activate human platelets. However, the staphylothrombin-mediated conversion of fibrinogen to fibrin initiated platelet aggregation and secondary activation and facilitated S. aureus-platelet interactions. Both the genetic absence of staphylocoagulase and vWbp and pharmacological inhibition of staphylothrombin increased the lag time to aggregation, and reduced platelet trapping by S. aureus in high shear stress conditions. The combined inhibition of staphylothrombin and immunoglobulin binding to platelets completely abolished the ability of S. aureus to aggregate platelets in vitro. In conclusion, although staphylothrombin did not directly activate platelets, the formation of a fibrin scaffold facilitated bacteria-platelet interaction, and the inhibition of staphylothrombin resulted in a reduced activation of platelets by S. aureus. PMID:22437005

  11. Lack of association between serum paraoxonase-1 activity and residual platelet aggregation during dual anti-platelet therapy.

    PubMed

    Ohmori, Tsukasa; Yano, Yuichiro; Sakata, Asuka; Ikemoto, Tomokazu; Shimpo, Masahisa; Madoiwa, Seiji; Katsuki, Takaaki; Mimuro, Jun; Shimada, Kazuyuki; Kario, Kazuomi; Sakata, Yoichi

    2012-04-01

    High residual platelet aggregability during thienopyridine treatment occurs because of low levels of the active drug metabolite, and is associated with an increased rate of major adverse cardiovascular events. Recent findings suggest that paraoxonase-1 (PON1) is a major determinant for clopidogrel efficacy. The aim of this study was to assess the impact of serum PON1 activity on platelet aggregability in thienopyridine-treated patients. In 72 patients receiving treatment with aspirin and ticlopidine after acute coronary syndrome, various laboratory data including the formation of platelet aggregations induced by agonists were compared with serum PON1 activities, measured as paraoxonase and homocysteine thiolactone hydrolase (HTLase). Serum paraoxonase activity was significantly associated with HTLase activity (R=0.4487, P<0.0001). These PON1 activities were not correlated with any parameters for platelet aggregation, hypertension, sleep apnea, and diabetes mellitus. In contrast, serum PON1 activities seemed to be involved in cardiac function, with brain natriuretic peptide and ejection fraction being significantly correlated with serum HTLase activity (R=-0.2767, P=0.0214) and paraoxonase activity (R=0.2558, P=0.0339), respectively. Paraoxonase activity also demonstrated a significant association with increased levels of ankle-brachial index (R=0.267, P=0.0255). Serum PON1 activities did not influence platelet aggregability during treatment with thienopyridine. However, they might modulate cardiac function after acute coronary syndrome and progression of atherosclerosis. PMID:22115701

  12. Platelet protective efficacy of 3,4,5 trisubstituted isoxazole analogue by inhibiting ROS-mediated apoptosis and platelet aggregation.

    PubMed

    Jagadish, Swamy; Rajeev, Narasimhamurthy; NaveenKumar, Somanathapura K; Sharath Kumar, Kothanahally S; Paul, Manoj; Hegde, Mahesh; Basappa; Sadashiva, Marilinganadoddi P; Girish, Kesturu S; Rangappa, Kanchugarakoppal S

    2016-03-01

    Thrombocytopenia is a major hematological concern in oxidative stress-associated pathologies and chronic clinical disorders, where premature platelet destruction severely affects the normal functioning of thrombosis and hemostasis. In addition, frequent exposure of platelets to chemical entities and therapeutic drugs immensely contributes in the development of thrombocytopenia leading to huge platelet loss, which might be fatal sometimes. Till date, there are only few platelet protective molecules known to combat thrombocytopenia. Hence, small molecule therapeutics are extremely in need to relieve the burden on limited treatment strategies of thrombocytopenia. In this study, we have synthesized a series of novel 3,4,5 trisubstituted isoxazole derivatives, among which compound 4a [4-methoxy-N'-(5-methyl-3-phenylisoxazole-4-carbonyl) benzenesulfonohydrazide] was found to significantly ameliorate the oxidative stress-induced platelet apoptosis by restoring various apoptotic markers such as ROS content, cytosolic Ca(2+) levels, eIF2-α phosphorylation, mitochondrial membrane depolarization, cytochrome c release, caspase activation, PS externalization, and cytotoxicity markers. Additionally, compound 4a dose dependently inhibits collagen-induced platelet aggregation. Hence, compound 4a can be considered as a prospective molecule in the treatment regime of platelet activation and apoptosis and other clinical conditions of thrombocytopenia. Further studies might ensure the use of compound 4a as a supplementary therapeutic agent to treat, thrombosis and CVD-associated complications. Over all, the study reveals a platelet protective efficacy of novel isoxazole derivative 4a with a potential to combat oxidative stress-induced platelet apoptosis.

  13. Potassium 2-(1-hydroxypentyl)-benzoate inhibits ADP-induced rat platelet aggregation through P2Y1-PLC signaling pathways.

    PubMed

    Yang, Hongyan; Xu, Shaofeng; Li, Jiang; Wang, Ling; Wang, Xiaoliang

    2015-09-01

    Potassium 2-(1-hydroxypenty1)-benzoate (dl-PHPB) is a new drug candidate for treatment of ischemic stroke with antiplatelet effect. In this study, we investigated the mechanisms of dl-PHPB in inhibiting platelet aggregation. The ADP-activated P2Y1-Gq-PLC and P2Y12-Gi-AC pathways were observed, respectively. Intravenous injection of dl-PHPB (1.3, 3.9, 12.9 mg/kg) significantly inhibited ADP-, collagen-, and arachidonic acid-induced rat platelet aggregation in a dose-dependent manner, and dl-PHPB had a relatively more potent inhibitory effect on ADP-induced rat platelet aggregation than other agonists. Dl-PHPB also showed a decreased expression of CD62P (a marker for platelet activation) mediated by ADP. Both dl-PHPB and ticlopidine (P2Y12 receptor antagonist) decreased cytoplasmic Ca(2+) concentration. But, dl-PHPB did not reverse the inhibition of PGE1-induced platelet cAMP formation by ADP, which was different from ticlopidine. Further, dl-PHPB instead of ticlopidine showed increasing phospholipase C-β phosphorylation (ser(1105)). The m-3M3FBS, a phospholipase C activator, attenuated the inhibitory effect of dl-PHPB on ADP-induced platelet aggregation and enhanced IP1 accumulation in rat platelets. Dl-PHPB decreased IP1 accumulation induced by ADP but had no effect on IP1 level enhanced by m-3M3FBS. Our results suggest that dl-PHPB has a potent antiplatelet effect, which is mainly through blockade of P2Y1 receptor-PLC-IP3 pathway and decreasing cytoplasmic calcium.

  14. The effects of vincristine on platelet aggregation studied by a filter loop technique in the rat.

    PubMed Central

    Bee, D.; Leach, E.; Martin, J. F.; Suggett, A. J.

    1980-01-01

    1 A method for measuring aggregation of platelets of adenosine diphosphate (ADP) is described using a filter inserted into the flowing aortic blood in the rat. 2 Repeated infusions of ADP resulted in a fall in the calculated aggregation index without significant changes in the platelet count. 3 Vincristine (0.05 mg/kg) intravenously caused significant inhibition of ADP-induced platelet aggregation. 4 Infusion of ADP caused some peripheral vasodilatation though it is unlikely that this contributed to the effects seen to any great extent. PMID:7437636

  15. The role of platelet aggregation and release in fragment D-induced pulmonary dysfunction.

    PubMed Central

    Manwaring, D; Curreri, P W

    1980-01-01

    The plasma concentration of fibrinogen degradation product D (fragmentt D) is markedly incrased following major burn or traumatic injury. Purified human fragment D infused into awake, restrained, nontraumatized rabbits (100 micrograms/ml blood) causes progressive thrombocytopenia, pulmonary dysfunction, vascular leak, and interstitial neutrophilia. Rabbits treated with the antihistamine diphenhydramine (Benadryl) prior to fragment D infusion fail to develop these symptoms. This study examined platelet aggregation, platelet ATP secretion, and platelet malondialdehyde release in rabbits which received fragmen D alone or fragment D following diphenhydramine pretreatment. Platelet-rich plasma was prepared from citrated blood drawn from femoral arterial catheters at 0, 2 1/2, and 4 hours postinfusion. Platelet aggregation was stimulated with either collagen or ADP. Malondialdehyde, a byproduct of thromboxane synthesis, was measured by colorimetry. Platelet aggregation and function (stimulated with collagen) were enhanced in fragment D platelet-rich plasma, since all response times decreased. Total ATP and MDA release incresed. Diphenhydramine pretreatment inhibited fragment D-enhanced aggregation, ATP release and prostaglandin (thromboxane) synthesis. No animal pretreated with diphenhydramine exhibited thrombocytopenia or respiratory dysfunction. Stimulation of platelet aggregation and release may represent one mechanism by which fragment D induces pulmonary dysfunction. Diphenhydramine inhibits these responses and may prove therapeutic in posttraumtic pulmonary complications. PMID:7406554

  16. In vitro platelet aggregation and oxidative stress caused by amorphous silica nanoparticles

    PubMed Central

    Nemmar, Abderrahim; Yuvaraju, Priya; Beegam, Sumaya; Yasin, Javed; Dhaheri, Rauda Al; Fahim, Mohamed A; Ali, Badreldin H

    2015-01-01

    Amorphous silica nanoparticles (SiNP) are being investigated for their potential use in various industrial and medical fields. Therefore, the assessment of their possible pathophysiological effect on circulating cells such as platelets is essential. We recently showed that intraperitoneal administration of SiNP causes proinflammatory and prothrombotic responses in vivo. However, little is known about the interaction of amorphous SiNP with platelets in vitro. Presently, we investigated the in vitro effects of SiNP (1, 5 and 25 μg/ml) on platelet aggregation, oxidative stress and intracellular calcium in mouse platelets. Incubation of platelets with SiNP caused a significant and dose-dependent platelet aggregation. Similarly, the activity of lactate dehydrogenase (as a marker of cell membrane integrity) was significantly increased by SiNP. Total antioxidant activity and lipid platelets vulnerability to in vitro peroxidation (measured by malondialdehyde production) were significantly increased after SiNP exposure. Additionally, SiNP exposure significantly increased the cytosolic calcium concentration. In conclusion, our in vitro data show that incubation of platelets with SiNP caused platelet aggregation, oxidative stress and increased intracellular calcium. This finding provides evidence on the toxicity of SiNP on platelet physiology. PMID:26069526

  17. A critical role for the regulation of Syk from agglutination to aggregation in human platelets.

    PubMed

    Shih, Chun-Ho; Chiang, Tin-Bin; Wang, Wen-Jeng

    2014-01-10

    Agglucetin, a tetrameric glycoprotein (GP) Ibα agonist from Formosan Agkistrodon acutus venom, has been characterized as an agglutination inducer in human washed platelets (WPs). In platelet-rich plasma (PRP), agglucetin dramatically elicits a biphasic response of agglutination and subsequent aggregation. For clarifying the intracellular signaling events from agglutination to aggregation in human platelets, we examined the essential signaling molecules involved through the detection of protein tyrosine phosphorylation (PTP). In WPs, an anti-GPIbα monoclonal antibody (mAb) AP1, but not a Src kinase inhibitor PP1, completely inhibited agglucetin-induced agglutination. However, PP1 but not AP1 had a potent suppression on platelet aggregation by a GPVI activator convulxin. The PTP analyses showed agglucetin alone can cause a weak pattern involving sequential phosphorylation of Lyn/Fyn, Syk, SLP-76 and phospholipase Cγ2 (PLCγ2). Furthermore, a Syk-selective kinase inhibitor, piceatannol, significantly suppressed the aggregating response in agglucetin-activated PRP. Analyzed by flow cytometry, the binding capacity of fluorophore-conjugated PAC-1, a mAb recognizing activated integrin αIIbβ3, was shown to increase in agglucetin-stimulated platelets. Again, piceatannol but not PP1 had a concentration-dependent suppression on agglucetin-induced αIIbβ3 exposure. Moreover, the formation of signalosome, including Syk, SLP-76, VAV, adhesion and degranulation promoting adapter protein (ADAP) and PLCγ2, are required for platelet aggregation in agglucetin/fibrinogen-activated platelets. In addition, GPIbα-ligation via agglucetin can substantially promote the interactions between αIIbβ3 and fibrinogen. Therefore, the signal pathway of Lyn/Fyn/Syk/SLP-76/ADAP/VAV/PLCγ2/PKC is sufficient to trigger platelet aggregation in agglucetin/fibrinogen-pretreated platelets. Importantly, Syk may function as a major regulator for the response from GPIbα-initiated agglutination to

  18. A critical role for the regulation of Syk from agglutination to aggregation in human platelets.

    PubMed

    Shih, Chun-Ho; Chiang, Tin-Bin; Wang, Wen-Jeng

    2014-01-10

    Agglucetin, a tetrameric glycoprotein (GP) Ibα agonist from Formosan Agkistrodon acutus venom, has been characterized as an agglutination inducer in human washed platelets (WPs). In platelet-rich plasma (PRP), agglucetin dramatically elicits a biphasic response of agglutination and subsequent aggregation. For clarifying the intracellular signaling events from agglutination to aggregation in human platelets, we examined the essential signaling molecules involved through the detection of protein tyrosine phosphorylation (PTP). In WPs, an anti-GPIbα monoclonal antibody (mAb) AP1, but not a Src kinase inhibitor PP1, completely inhibited agglucetin-induced agglutination. However, PP1 but not AP1 had a potent suppression on platelet aggregation by a GPVI activator convulxin. The PTP analyses showed agglucetin alone can cause a weak pattern involving sequential phosphorylation of Lyn/Fyn, Syk, SLP-76 and phospholipase Cγ2 (PLCγ2). Furthermore, a Syk-selective kinase inhibitor, piceatannol, significantly suppressed the aggregating response in agglucetin-activated PRP. Analyzed by flow cytometry, the binding capacity of fluorophore-conjugated PAC-1, a mAb recognizing activated integrin αIIbβ3, was shown to increase in agglucetin-stimulated platelets. Again, piceatannol but not PP1 had a concentration-dependent suppression on agglucetin-induced αIIbβ3 exposure. Moreover, the formation of signalosome, including Syk, SLP-76, VAV, adhesion and degranulation promoting adapter protein (ADAP) and PLCγ2, are required for platelet aggregation in agglucetin/fibrinogen-activated platelets. In addition, GPIbα-ligation via agglucetin can substantially promote the interactions between αIIbβ3 and fibrinogen. Therefore, the signal pathway of Lyn/Fyn/Syk/SLP-76/ADAP/VAV/PLCγ2/PKC is sufficient to trigger platelet aggregation in agglucetin/fibrinogen-pretreated platelets. Importantly, Syk may function as a major regulator for the response from GPIbα-initiated agglutination to

  19. Inhibition of platelet aggregation and reduced formation of thromboxane and lipoxygenase products in platelets by oil of cloves.

    PubMed

    Srivastava, K C; Justesen, U

    1987-09-01

    Oil of cloves (OC) was found to be a potent inhibitor of platelet aggregation induced by arachidonic acid (AA), collagen and epinephrine; in this respect it was most effective against AA-induced aggregation. Inhibition of aggregation by OC seems to be mediated through a reduced formation of thromboxane as indicated by the following experimental evidence. (i) OC inhibited TxB2 formation in intact as well as lysed platelet preparations from added arachidonate, and (ii) it inhibited the formation of TxB2 from AA-labelled platelets after activation with Ca2+-ionophore A23187. The formation of lipoxygenase derived products was dependent on the concentration of OC used; at its lower concentration their amounts increased but this was found to be reversed at higher concentrations. At all concentrations thromboxane was decreased with a concomitant increase in unused AA. PMID:3118394

  20. An atypical IgM class platelet cold agglutinin induces GPVI-dependent aggregation of human platelets.

    PubMed

    Sánchez Guiu, I M; Martínez-Martinez, I; Martínez, C; Navarro-Fernandez, J; García-Candel, F; Ferrer-Marín, F; Vicente, V; Watson, S P; Andrews, R K; Gardiner, E E; Lozano, M L; Rivera, J

    2015-08-01

    Platelet cold agglutinins (PCA) cause pseudothrombocytopenia, spurious thrombocytopenia due to ex vivo platelet clumping, complicating clinical diagnosis, but mechanisms and consequences of PCA are not well defined. Here, we characterised an atypical immunoglobulin (Ig)M PCA in a 37-year-old woman with lifelong bleeding and chronic moderate thrombocytopenia, that induces activation and aggregation of autologous or allogeneic platelets via interaction with platelet glycoprotein (GP)VI. Patient temperature-dependent pseudothrombocytopenia was EDTA-independent, but was prevented by integrin αIIbβ3 blockade. Unstimulated patient platelets revealed elevated levels of bound IgM, increased expression of activation markers (P-selectin and CD63), low GPVI levels and abnormally high thromboxane (TX)A2 production. Patient serum induced temperature- and αIIbβ3-dependent decrease of platelet count in allogeneic donor citrated platelet-rich plasma (PRP), but not in PRP from Glanzmann's thrombasthenia or afibrinogenaemia patients. In allogeneic platelets, patient plasma induced shape change, P-selectin and CD63 expression, (14)C-serotonin release, and TXA2 production. Activation was not inhibited by aspirin, cangrelor or blocking anti-Fc receptor (FcγRIIA) antibody, but was abrogated by inhibitors of Src and Syk, and by a soluble GPVI-Fc fusion protein. GPVI-deficient platelets were not activated by patient plasma. These data provide the first evidence for an IgM PCA causing platelet activation/aggregation via GPVI. The PCA activity persisted over a five-year follow-up period, supporting a causative role in patient chronic thrombocytopenia and bleeding. PMID:25994029

  1. An atypical IgM class platelet cold agglutinin induces GPVI-dependent aggregation of human platelets.

    PubMed

    Sánchez Guiu, I M; Martínez-Martinez, I; Martínez, C; Navarro-Fernandez, J; García-Candel, F; Ferrer-Marín, F; Vicente, V; Watson, S P; Andrews, R K; Gardiner, E E; Lozano, M L; Rivera, J

    2015-08-01

    Platelet cold agglutinins (PCA) cause pseudothrombocytopenia, spurious thrombocytopenia due to ex vivo platelet clumping, complicating clinical diagnosis, but mechanisms and consequences of PCA are not well defined. Here, we characterised an atypical immunoglobulin (Ig)M PCA in a 37-year-old woman with lifelong bleeding and chronic moderate thrombocytopenia, that induces activation and aggregation of autologous or allogeneic platelets via interaction with platelet glycoprotein (GP)VI. Patient temperature-dependent pseudothrombocytopenia was EDTA-independent, but was prevented by integrin αIIbβ3 blockade. Unstimulated patient platelets revealed elevated levels of bound IgM, increased expression of activation markers (P-selectin and CD63), low GPVI levels and abnormally high thromboxane (TX)A2 production. Patient serum induced temperature- and αIIbβ3-dependent decrease of platelet count in allogeneic donor citrated platelet-rich plasma (PRP), but not in PRP from Glanzmann's thrombasthenia or afibrinogenaemia patients. In allogeneic platelets, patient plasma induced shape change, P-selectin and CD63 expression, (14)C-serotonin release, and TXA2 production. Activation was not inhibited by aspirin, cangrelor or blocking anti-Fc receptor (FcγRIIA) antibody, but was abrogated by inhibitors of Src and Syk, and by a soluble GPVI-Fc fusion protein. GPVI-deficient platelets were not activated by patient plasma. These data provide the first evidence for an IgM PCA causing platelet activation/aggregation via GPVI. The PCA activity persisted over a five-year follow-up period, supporting a causative role in patient chronic thrombocytopenia and bleeding.

  2. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    PubMed

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

    2015-08-01

    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.

  3. An ethanol extract of Ramulus mori improves blood circulation by inhibiting platelet aggregation.

    PubMed

    Lee, Jiyun; Kwon, Gayeung; Park, Jieun; Kim, Jeong-Keun; Choe, Soo Young; Seo, Yoonhee; Lim, Young-Hee

    2016-07-01

    Inappropriate platelet aggregation can cause blood coagulation and thrombosis. In this study, the effect of an ethanol extract of Ramulus mori (ERM) on blood circulation was investigated. The antithrombotic activity of ERM on rat carotid arterial thrombosis was evaluated in vivo, and the effect of ERM on platelet aggregation and blood coagulation time was evaluated ex vivo. To evaluate the safety of ERM, its cytotoxicity to platelets and its effect on tail bleeding time were assessed; ERM was not toxic to rat platelets and did not prolong bleeding time. Moreover, administering ERM to rats had a significant preventive effect on carotid arterial thrombosis in vivo, and significantly inhibited adenosine diphosphate- and collagen-induced platelet aggregation ex vivo, whereas it did not prolong coagulation periods, such as prothrombin time and activated partial thromboplastin time. The results suggest that ERM is effective in improving blood circulation via antiplatelet activity rather than anticoagulation activity.

  4. Platelet aggregation responses vary over a period of time in healthy controls.

    PubMed

    Refaai, Majed A; Frenkel, Eugene; Sarode, Ravi

    2010-01-01

    Platelet aggregation study is performed to investigate platelet function abnormality. A normal healthy control sample is usually run with the patient sample as a quality control measure. At our institution, we observed variations in platelet aggregation responses in our normal repeat controls. Therefore, we analysed aggregation parameters in these controls. Whole blood aggregation studies were performed with adenosine diphosphate (ADP), arachidonic acid (AA), collagen and ristocetin. Adenosine triphosphate (ATP) secretion was also measured simultaneously by leuciferin-leuciferase reaction. During a 5-year period, a total of 86 studies were performed on seven controls. Aggregations were within the acceptable range in 67% of the time. Collagen was the most affected agonist in our study. On five occasions, four controls had subnormal aggregations with two agonists. All abnormal responses were hypoaggregation except for two who had hyperaggregation with collagen and AA. Only one out of seven controls was always normal. In the presence of a subnormal control result, a new control was run before releasing the patient's platelet aggregation results. These findings suggest that many physiological factors, other than medications, may affect platelet function even in normal individuals. Therefore, a repeat study at a later date to demonstrate a reproducible abnormality would be prudent before labeling a patient's platelets abnormal.

  5. Amino acid induced fractal aggregation of gold nanoparticles: Why and how.

    PubMed

    Doyen, Matthieu; Goole, Jonathan; Bartik, Kristin; Bruylants, Gilles

    2016-02-15

    Gold colloids are the object of many studies as they are reported to have potential biological sensing, imaging and drug delivery applications. In the presence of certain amino acids the aggregation of the gold nanoparticles into linear structures is observed, as highlighted by the appearance of a second plasmon band in the UV-Vis spectra of the colloid. The mechanism behind this phenomenon is still under debate. In order to help elucidate this issue, the interaction between gold colloids and different amino acids, modified amino acids and molecules mimicking their side-chain was monitored by UV-Vis absorption, DLS and TEM. The results show that phenomenon can be rationalized in terms of the Diffusion Limited Colloid Aggregation (DLCA) model which gives rise to the fractal aggregation colloids. The global charge of the compound, which influences the ionic strength of the solution, and the ease with which the compound can interact with the GNPs and affect their surface potential, are, the two parameters which control the DLCA regime. Calculations based on the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory confirm all the experimental observations. PMID:26613335

  6. Amino acid induced fractal aggregation of gold nanoparticles: Why and how.

    PubMed

    Doyen, Matthieu; Goole, Jonathan; Bartik, Kristin; Bruylants, Gilles

    2016-02-15

    Gold colloids are the object of many studies as they are reported to have potential biological sensing, imaging and drug delivery applications. In the presence of certain amino acids the aggregation of the gold nanoparticles into linear structures is observed, as highlighted by the appearance of a second plasmon band in the UV-Vis spectra of the colloid. The mechanism behind this phenomenon is still under debate. In order to help elucidate this issue, the interaction between gold colloids and different amino acids, modified amino acids and molecules mimicking their side-chain was monitored by UV-Vis absorption, DLS and TEM. The results show that phenomenon can be rationalized in terms of the Diffusion Limited Colloid Aggregation (DLCA) model which gives rise to the fractal aggregation colloids. The global charge of the compound, which influences the ionic strength of the solution, and the ease with which the compound can interact with the GNPs and affect their surface potential, are, the two parameters which control the DLCA regime. Calculations based on the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory confirm all the experimental observations.

  7. On-chip evaluation of platelet adhesion and aggregation upon exposure to mesoporous silica nanoparticles.

    PubMed

    Kim, Donghyuk; Finkenstaedt-Quinn, Solaire; Hurley, Katie R; Buchman, Joseph T; Haynes, Christy L

    2014-03-01

    Mesoporous silica nanoparticles are promising drug delivery agents; however, their interaction with various in vivo biological components is still under investigation. In this work, the impact of sub-50 nm diameter mesoporous silica nanoparticles on platelet function is investigated using a microfluidic platform to model blood vessel characteristics. Platelet adhesion and aggregation in the presence of mesoporous silica nanoparticles is investigated, controlling whether or not platelets are activated ahead of nanoparticle exposure. The results indicate that nanoparticles slightly compromise platelet adhesion to endothelial cells at low nanoparticle doses, but that high nanoparticle doses significantly increase the number of platelet adhesion events, leading to higher probability for uncontrolled platelet actions (e.g. clot formation in vivo). High nanoparticle doses also induced platelet aggregation. While platelet activation and aggregation occurred, in no case did nanoparticle exposure result in significant loss of platelet viability; as such, this work clearly demonstrates that aspects besides viability, such as cellular adhesion and interaction with other cell types, have to be considered in the context of nanotoxicology. This simple and highly adaptable analytical platform will be useful for further nanotoxicity studies involving other nanoparticle and cell types.

  8. A note on the use of Quin2 in studying shear-induced platelet aggregation.

    PubMed

    Giorgio, T D; Hellums, J D

    1986-02-01

    Quin2, a calcium ion chelator which can penetrate plasma membranes, was used to study the role of intracellular calcium ion concentration in mediating shear-induced platelet activation. Washed platelet suspensions were subjected to various levels of uniform, known shear stress in a cone and plate viscometer in the absence of added agonists. Additional samples were aggregated in response to chemical platelet agonists in a conventional aggregometer. The aggregometer response of Quin2-containing platelets to collagen, thrombin and ADP exhibited increased lag time and reduced maximum rate of aggregation in comparison to controls. However, the extent of aggregation of the Quin2-containing platelets eventually reached the same level as that of the controls. Very different results were obtained for aggregation by shear stress in the viscometer. Shear-induced aggregation was significantly suppressed by Quin2 treatment at both short (30 seconds) and long (300 seconds) times of exposure to the shear field. Shear-induced dense granular release and cellular lysis were unaltered by Quin2 treatment at 30 second exposure times, but both were significantly increased by Quin2 treatment at 300 second exposure times. These results suggest that intracellular calcium ion mobilization is an important early step in shear-induced platelet activation. Additionally, Quin2 appears to have effects resulting in increased platelet fragility. Thus, the findings raise questions on the suitability of Quin2 as an intracellular calcium ion probe in studies in shear fields. PMID:3705013

  9. gammaA/gamma' fibrinogen inhibits thrombin-induced platelet aggregation.

    PubMed

    Lovely, Rehana S; Rein, Chantelle M; White, Tara C; Jouihan, Sari A; Boshkov, Lynn K; Bakke, Antony C; McCarty, Owen J; Farrell, David H

    2008-11-01

    The minor gammaA/gamma' fibrinogen isoform contains a high affinity binding site for thrombin exosite II that is lacking in the major gammaA/gammaA fibrinogen isoform. We therefore investigated the biological consequences of the gamma' chain binding to thrombin. Thrombin-induced platelet aggregation was inhibited by gammaA/gamma' fibrinogen. Carboxyl terminal peptide fragment gamma'410-427 from the gamma' chain was also inhibitory, with an IC(50) of approximately 200 microM in whole plasma. Deletion of the peptide from either the amino or carboxyl end significantly decreased inhibition. In contrast to thrombin-induced platelet aggregation, aggregation induced by epinephrine, ADP, arachidonic acid, or SFLLRN peptide showed little inhibition by the gamma' peptide. The inhibition of thrombin-induced platelet aggregation was not due to direct inhibition of the thrombin active site, since cleavage of a small peptidyl substrate was 91% of normal even in the presence of 1 mM gamma'410-427. The gamma'410-427 peptide blocked platelet adhesion to immobilized thrombin under both static and flow conditions, blocked soluble thrombin binding to platelet GPIbalpha, and inhibited PAR1 cleavage by thrombin. These results suggest that the gamma' chain of fibrinogen inhibits thrombin-induced platelet aggregation by binding to thrombin exosite II. Thrombin that is bound to the gamma' chain is thereby prevented from activating platelets, while retaining its amidolytic activity. PMID:18989528

  10. Cilostazol Inhibits Accumulation of Triglyceride in Aorta and Platelet Aggregation in Cholesterol-Fed Rabbits

    PubMed Central

    Ito, Hideki; Uehara, Kenji; Matsumoto, Yutaka; Hashimoto, Ayako; Nagano, Chifumi; Niimi, Manabu; Miyakoda, Goro; Nagano, Keisuke

    2012-01-01

    Cilostazol is clinically used for the treatment of ischemic symptoms in patients with chronic peripheral arterial obstruction and for the secondary prevention of brain infarction. Recently, it has been reported that cilostazol has preventive effects on atherogenesis and decreased serum triglyceride in rodent models. There are, however, few reports on the evaluation of cilostazol using atherosclerotic rabbits, which have similar lipid metabolism to humans, and are used for investigating the lipid content in aorta and platelet aggregation under conditions of hyperlipidemia. Therefore, we evaluated the effect of cilostazol on the atherosclerosis and platelet aggregation in rabbits fed a normal diet or a cholesterol-containing diet supplemented with or without cilostazol. We evaluated the effects of cilostazol on the atherogenesis by measuring serum and aortic lipid content, and the lesion area after a 10-week treatment and the effect on platelet aggregation after 1- and 10-week treatment. From the lipid analyses, cilostazol significantly reduced the total cholesterol, triglyceride and phospholipids in serum, and moreover, the triglyceride content in the atherosclerotic aorta. Cilostazol significantly reduced the intimal atherosclerotic area. Platelet aggregation was enhanced in cholesterol-fed rabbits. Cilostazol significantly inhibited the platelet aggregation in rabbits fed both a normal diet and a high cholesterol diet. Cilostazol showed anti-atherosclerotic and anti-platelet effects in cholesterol-fed rabbits possibly due to the improvement of lipid metabolism and the attenuation of platelet activation. The results suggest that cilostazol is useful for prevention and treatment of atherothrombotic diseases with the lipid abnormalities. PMID:22761774

  11. Binding of Folic Acid Induces Specific Self-Aggregation of Lactoferrin: Thermodynamic Characterization.

    PubMed

    Tavares, Guilherme M; Croguennec, Thomas; Lê, Sébastien; Lerideau, Olivia; Hamon, Pascaline; Carvalho, Antônio F; Bouhallab, Saïd

    2015-11-17

    In the study presented here, we investigated the interaction at pH 5.5 between folic acid (FA) and lactoferrin (LF), a positively charged protein. We found a binding constant Ka of 10(5) M(-1) and a high stoichiometry of 10 mol of FA/mol of LF. The size and charge of the complexes formed evolved during titration experiments. Increasing the ionic strength to 50 mM completely abolished the isothermal titration calorimetry (ITC) signal, suggesting the predominance of electrostatic interactions in the exothermic binding obtained. We developed a theoretical model that explains the complex triphasic ITC profile. Our results revealed a two-step mechanism: FA/LF interaction followed by self-association of the complexes thus formed. We suggest that 10 FA molecules bind to LF to form saturated reactive complexes (FA10/LF) that further self-associate into aggregates with a finite size of around 15 nm. There is thus a critical saturation degree of the protein, above which the self-association can take place. We present here the first results that provide comprehensive details of the thermodynamics of FA/LF complexation-association. Given the high stoichiometry, allowing a load of 55 mg of FA/g of LF, we suggest that FA/LF aggregates would be an effective vehicle for FA in fortified drinks. PMID:26488446

  12. Phase analysis of platelet aggregation in acute disturbances of cerebral circulation.

    PubMed

    Petrova, T R; Pavlishchuk, S A; Grigoriev, G I

    1975-01-01

    In 120 patients with atherosclerosis, complicated in 43 patients by a haemorrhagic, in 47 patients by an ischaemic, and in 30 patients by a transient cerebral insult, phase analysis of platelet aggregation was performed by the turbidimetric method according to Born with graphic recording according to O'Brien. An increase in the platelet activity was found in ischaemic insult, manifesting itself by the occurrence of spontaneous aggregationin 60% of the cases, an acceleration of ADP-induced aggregation, and the second aggregation phase in all patients examined. A direct correlation was revealed between the secondary aggregation and the intensity of spontaneous and of ADP-induced aggregation, and the possibility of a transformation of the spontaneous into the secondary aggregation of platelets was demonstrated. Haemorrhagic insults were characterized by the absence of spontaneous and secondary aggregation and by the suppression of ADP-induced aggregation. In a transient insult, the mean values of the aggregatogram items did differ from normal. In vitro, the role of increased permeability of platelet membranes in the mechanism triggering off spontaneous aggregation and the second phase of ADP-induced aggregation was documented.

  13. [THE INFLUENCE OF HYDROGEN SULFIDE ON COLLAGEN-INDUCED AGGREGATION OF HUMAN PLATELETS].

    PubMed

    Petrova, I V; Trubacheva, O A; Mangataeva, O S; Suslova, T E; Kovalev, I V; Gusakova, S V

    2015-10-01

    Study the impact of hydrogen sulfide on collagen-induced platelet aggregation from healthy donors and patients with type 2 diabetes. In healthy individuals, in contrast to patients with type 2 diabetes, NaHS significantly inhibited platelet aggregation. Activators of cAMP signaling (forskolin and phosphodiesterase inhibitor) significantly reduced platelet aggregation in both groups of examinees. NO-synthase inhibitors increased platelet aggregation in healthy volunteers, but not in patients with type 2 diabetes. The presence of H2S donor did not alter the extent of platelet aggregation at high concentrations of cAMP or decreased production of nitric oxide. It is assumed that the antiplatelet effect of H2S is not associated with the effect on the signal system, mediated cAMP or nitric oxide. Change H2S-dependent regulation of platelet aggregation in patients with type 2 diabetes is caused by disorders have been reported with this disease: the increase of intracellular calcium ion concentration, oxidative damage to proteins, hyperhomocysteinemia, glycosylation of key proteins involved in this process.

  14. Platelet aggregation in Finnish men and its relation to fatty acids in platelets, plasma and adipose tissue.

    PubMed

    Salo, M K; Vartiainen, E; Puska, P; Nikkari, T

    1985-10-30

    Platelet aggregation and its relation to fatty acid composition of platelets, plasma and adipose tissue was determined in 196 randomly selected, free-living, 40-49-year-old men in two regions of Finland (east and southwest) with a nearly twofold difference in the IHD rate. There were no significant east-southwest differences in platelet aggregation induced with ADP, thrombin or epinephrine. ADP-induced platelet secondary aggregation showed significant negative associations with all C20-C22 omega 3-fatty acids in platelets (r = -0.26- -0.40) and with the platelet 20: 5 omega 3/20: 4 omega 6 and omega 3/omega 6 ratios, but significant positive correlations with the contents of 18:2 in adipose tissue (r = 0.20) and plasma triglycerides (TG) (r = 0.29). Epinephrine-induced aggregation correlated negatively with 20: 5 omega 3 in plasma cholesteryl esters (CE) (r = -0.23) and TG (r = -0.29), and positively with the total percentage of saturated fatty acids in platelets (r = 0.33), but had no significant correlations with any of the omega 6-fatty acids. Thrombin-induced aggregation correlated negatively with the omega 3/6 omega ratio in adipose tissue (r = -0.25) and the 20: 3 omega 6/20: 4 omega 6 ratio in plasma CE (r = -0.27) and free fatty acids (FFA) (r = -0.23), and positively with adipose tissue 18:2 (r = 0.23) and 20:4 omega 6 (r = 0.22) in plasma phospholipids (PL). The percentages of prostanoid precursors in platelet lipids, i.e. 20:3 omega 6, 20:4 omega 6 and 20:5 omega 3, correlated best with the same fatty acids in plasma CE (r = 0.32 - 0.77) and PL (r = 0.28 - 0.74). Platelet 20:5 omega 3 had highly significant negative correlations with the percentage of 18:2 in adipose tissue and all plasma lipid fractions (r = -0.35 - -0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Inhibitors of ex vivo aggregation of human platelets induced by decompression, during reduced barometric pressure.

    PubMed

    Murayama, M; Kumaroo, K K

    1986-05-15

    It has been shown experimentally ex vivo that human platelet aggregation is induced by decompression (reduced pressure) produced by various means, i.e., reduced barometric pressure, reduced hydrostatic pressure, and reduced hydrodynamic pressure due to Bernoulli's principle. We report here that the spontaneous platelet aggregation induced by reduced barometric pressure (253 torr for three hours) is inhibited by 1:10(7) diluted Japanese herbal plant oil (JHP) and also by two of its major constituents, menthone and menthol with the median inhibitory concentration (IC50) in the millimolar range. These drugs gave essentially similar results when collagen and ADP were used as aggregating agents. Inhibitor concentrations were determined by microscopic examination of platelets in wet preparations when the aggregating stimulus was reduced pressure and by optical aggregometry when collagen and ADP were the aggregating agents. Potential usefulness of these compounds in the prevention of decompression syndrome (DCS) and acute mountain sickness (AMS) are discussed.

  16. [Effect of soluble fibrin on the blood coagulation process and platelets aggregation].

    PubMed

    Zaichko, N V; Chernyshenko, T M; Platonova, T M; Volkov, H L

    2006-01-01

    The accumulation of soluble fibrin (SF) in the blood plasma causes acceleration of the final stage of blood coagulation. It increases functional activity of a hemostasis system platelet link, that is the precondition of thrombotic complication. Accumulation of SF in the blood plasma is accompanied by proportional reduction of coagulation time in ancistron and thrombin time tests, and also the intensification of platelets aggregation process. A conclusion was drawn that for early diagnostics of the DIC-syndrom it is expedient to carry out complex estimation of the hemostasis system with obligatory definition of the blood SF content, performance of ancistron and thrombin time tests, and also study of platelets aggregation.

  17. Mechanism for release of arachidonic acid during guinea pig platelet aggregation: a role for the diacylglycerol lipase inhibitor RHC 80267

    SciTech Connect

    Amin, D.

    1986-01-01

    The mechanism of the release of arachidonic acid from phospholipids after the stimulation of guinea pig platelets with collagen, thrombin and platelet activating factor (PAF) was studied. RHC 80267, a diacylglycerol lipase inhibitor, and indomethacin, a cyclooxygenase inhibitor, were used. Various in vitro assays for enzymes involved in arachidonic acid release and metabolism were conducted. Platelet aggregation and simultaneous release of ADP from platelets were monitored using a Chrono-log Lumiaggregometer. Platelets were labeled with (/sup 14/C)arachidonic acid to facilitate sensitive determination of small changes in platelet phospholipids during platelet aggregation. In the present investigation it is shown that collagen, thrombin and PAF increased phospholipase C activity. It was also discovered that cyclooxygenase products were responsible for further stimulation (a positive feed-back) of phospholipase C activity, while diacylglycerol provided a negative feed-back control over receptor-stimulated phospholipase C activity and inhibited ADP release. The guinea pig platelet is an ideal model to study phospholipase C-diacylglycerol lipase pathway for the release of arachidonic acid from platelet phospholipids because it does not have any phospholipase A/sub 2/ activity. It was observed that cyclooxygenase products were responsible for collagen-induced guinea pig platelet aggregation. Indomethacin completely inhibited collagen-induced platelet aggregation, was less effective against thrombin, and had no effect on PAF-induced platelet aggregation. On the other hand, RHC 80267 was a powerful inhibitor of aggregation and ADP release induced by all three of these potent aggregating agents.

  18. Perilla oil improves blood flow through inhibition of platelet aggregation and thrombus formation

    PubMed Central

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang-Sei; Lee, Sung-Pyo; Kang, Myung-Hwa; Choi, Ehn-Kyoung

    2014-01-01

    The inhibitory effects of perilla oil on the platelet aggregation in vitro and thrombosis in vivo were investigated in comparison with aspirin, a well-known blood flow enhancer. Rabbit platelet-rich plasma was incubated with perilla oil and aggregation inducers collagen or thrombin, and the platelet aggregation rate was analyzed. Perilla oil significantly inhibited both the collagen- and thrombin-induced platelet aggregations, in which the thromboxane B2 formation from collagen-activated platelets were reduced in a concentration-dependent manner. Rats were administered once daily by gavage with perilla oil for 1 week, carotid arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Perilla oil delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 0.5 mL/kg. In addition, a high dose (2 mL/kg) of perilla oil greatly prevented the occlusion, comparable to the effect of aspirin (30 mg/kg). The results indicate that perilla oil inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is proposed that perilla oil could be a good candidate without adverse effects for the improvement of blood flow. PMID:24707301

  19. Nattokinase improves blood flow by inhibiting platelet aggregation and thrombus formation

    PubMed Central

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang Sei; Park, Sung Kyeong; Lee, Sung-Pyo; Choi, Ehn-Kyoung

    2013-01-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-dependent manner. Rats were orally administered with nattokinase for 1 week, and their carotid arteries were exposed. Arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Nattokinase delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 160 mg/kg. In addition, a high dose (500 mg/kg) of nattokinase fully prevented the occlusion, as achieved with aspirin (30 mg/kg). The results indicate that nattokinase extracted from fermented soybean inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is suggested that nattokinase could be a good candidate without adverse effects for the improvement of blood flow. PMID:24396387

  20. Nattokinase improves blood flow by inhibiting platelet aggregation and thrombus formation.

    PubMed

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang Sei; Park, Sung Kyeong; Lee, Sung-Pyo; Choi, Ehn-Kyoung; Rhee, Man Hee; Kim, Yun-Bae

    2013-12-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-dependent manner. Rats were orally administered with nattokinase for 1 week, and their carotid arteries were exposed. Arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Nattokinase delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 160 mg/kg. In addition, a high dose (500 mg/kg) of nattokinase fully prevented the occlusion, as achieved with aspirin (30 mg/kg). The results indicate that nattokinase extracted from fermented soybean inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is suggested that nattokinase could be a good candidate without adverse effects for the improvement of blood flow.

  1. Selective activation of the prostaglandin E2 receptor subtype EP2 or EP4 leads to inhibition of platelet aggregation.

    PubMed

    Kuriyama, Shuhko; Kashiwagi, Hitoshi; Yuhki, Koh-ichi; Kojima, Fumiaki; Yamada, Takehiro; Fujino, Takayuki; Hara, Akiyoshi; Takayama, Koji; Maruyama, Takayuki; Yoshida, Akitoshi; Narumiya, Shuh; Ushikubi, Fumitaka

    2010-10-01

    The effect of selective activation of platelet prostaglandin (PG) E2 receptor subtype EP2 or EP4 on platelet aggregation remains to be determined. In platelets prepared from wild-type mice (WT platelets), high concentrations of PGE2 inhibited platelet aggregation induced by U-46619, a thromboxane receptor agonist. However, there was no significant change in the inhibitory effect of PGE2 on platelets lacking EP2 (EP2-/- platelets) and EP4 (EP4-/- platelets) compared with the inhibitory effect on WT platelets. On the other hand, AE1-259 and AE1-329, agonists for EP2 and EP4, respectively, potently inhibited U-46619 -induced aggregation with respective IC50 values of 590 ± 14 and 100 ± 4.9 nM in WT platelets, while the inhibition was significantly blunted in EP2-/- and EP4-/- platelets. In human platelets, AE1-259 and AE1-329 inhibited U-46619-induced aggregation with respective IC50 values of 640 ± 16 and 2.3 ± 0.3 nM. Notably, the inhibitory potency of AE1-329 in human platelets was much higher than that in murine platelets, while such a difference was not observed in the inhibitory potency of AE1-259. AE1-329 also inhibited adenosine diphosphate-induced platelet aggregation, and the inhibition was almost completely blocked by AE3-208, an EP4 antagonist. In addition, AE1-329 increased intracellular cAMP concentrations in a concentration- and EP4-dependent manner in human platelets. These results indicate that selective activation of EP2 or EP4 can inhibit platelet aggregation and that EP4 agonists are particularly promising as novel anti-platelet agents.

  2. The effect of ex vivo anticoagulants on whole blood platelet aggregation.

    PubMed

    Kalb, Madeleine L; Potura, Lukasz; Scharbert, Gisela; Kozek-Langenecker, Sibylle A

    2009-02-01

    Pre- and intraoperative platelet function monitoring is increasingly recommended in order to detect risk factors for bleeding and to target coagulation management. The ideal anticoagulant for accurate platelet aggregometry remains controversial. The aim of this experimental trial was to compare platelet aggregability in whole blood stored in citrate, heparin and direct thrombin inhibitors. Whole blood was drawn from 11 healthy adult volunteers who had not taken any medication in the previous 14 days. Blood was stored in trisodium citrate, unfractionated heparin, melagatran, lepirudin and argatroban. Platelet aggregation was performed using the impedance aggregometer Multiplate (Dynabyte, Munich, Germany) with adenosine diphosphate (ADP), thrombin receptor activating peptide (TRAP), collagen, arachidonic acid and ristocetin as agonists. Samples were analysed immediately after blood sampling (baseline), as well as 30 and 120 min afterwards. At baseline there were no significant differences in aggregability between samples containing direct thrombin inhibitors and heparin. In contrast, aggregation in response to all agonists except for ristocetin was significantly impaired in citrated blood. During storage the response to arachidonic acid and collagen was maintained by direct thrombin inhibitors and heparin, whereas ADP-, TRAP- and ristocetin-induced aggregation varied considerably over time in all ex vivo anticoagulants tested. Pre-analytical procedures should be standardized because storage duration and anticoagulants significantly affect platelet aggregability in whole blood. For point-of-care monitoring with immediate analysis after blood withdrawal all tested direct thrombin inhibitors as well as unfractionated heparin can be used as anticoagulants whereas citrate is not recommended. PMID:19172515

  3. Effect of selective inhibition of the p38 MAP kinase pathway on platelet aggregation.

    PubMed

    Kuliopulos, Athan; Mohanlal, Ramon; Covic, Lidija

    2004-12-01

    Systemic inflammation has been shown to be a contributing factor to the instability of atherosclerotic plaques in patients with acute coronary syndromes (ACS). VX-702, a novel p38 mitogen-activated protein kinase (MAPK) inhibitor, is currently under investigation in ACS patients with unstable angina to evaluate its safety and efficacy during percutaneous coronary intervention (PCI). The role of p38 MAPK in platelet aggregation of normal individuals was examined using the selective second generation p38 MAPK inhibitor VX-702. Treatment of platelets with thrombin (activates PAR1 and PAR4 thrombin receptors), SFLLRN (PAR1), AYPGKF (PAR4), collagen (alpha2beta1 and GPVI/FCgammaIIR receptors) and U46619 (TXA(2)) resulted in strong activation of p38 MAPK. Activation of the GPIb von Willebrand factor receptor with ristocetin did not stimulate p38 MAPK. Pre-treatment of platelets with 1 microM VX-702 completely inhibited activation of p38 MAPK by thrombin, SFLLRN, AYPGKF, U46619, and collagen. There was no effect of VX-702 on platelet aggregation induced by any of the agonists in the presence or absence of aspirin, heparin or apyrase. It has been postulated that a potential role of p38 MAPK is to activate phospholipase A(2) (cPLA(2)) which catalyses formation of arachidonic acid leading to production of thromboxane. Interestingly, we show contrasting effects of p38 MAPK inhibition as compared to aspirin inhibition on platelet aggregation in response to collagen. Blockade of TXA(2) production by aspirin results in significant inhibition of collagen activation. However,VX-702 has no effect on collagen-mediated platelet aggregation, suggesting that blocking p38 MAPK does not effect thromboxane production in human platelets. Therefore, unlike aspirin blockade of thromboxane production in platelets, p38 MAPK inhibitors such as VX-702 do not significantly affect platelet function and would not be expected to contribute to an elevated risk of bleeding side-effects in treated

  4. Acute effect of a high-carbohydrate low-fat meal on platelet aggregation.

    PubMed

    Ahuja, Kiran D K; Adams, Murray J; Robertson, Iain K; Ball, Madeleine J

    2009-12-01

    Conflicting information is available regarding patient preparation with respect to the fasting and feeding states prior to blood collection in order to conduct platelet aggregation tests. Some literature suggests avoidance of only high-fat foods and allowance of non-fat foods and clear liquids; others suggest a fast of 8-10 hours. We conducted a study in 16 healthy subjects aged 44.0 +/- 12.7 (mean +/- SD) years to investigate and compare the effects of fasting and a high-carbohydrate low-fat meal on measures of platelet aggregation. Blood samples collected after an overnight fast of 10-12 hours and those collected at 40 and 120 minute postprandially (post-high-carbohydrate low-fat meal; 1900 kJ energy; 69, 16 and 15% of energy from carbohydrate, protein and fat, respectively), were tested for platelet aggregation in response to adenosine diphosphate. There was a significant reduction in maximum aggregation and area under the aggregation curve from fasting to 120 minute post meal (overall p < 0.001). Serum triglyceride concentrations did not change significantly from fasting to postprandial state (p = 0.53). Although there was a significant association between serum insulin, plasma glucose and measures of platelet aggregation, correcting for the effects of these metabolic parameters did not alter the results, providing evidence that other, currently unknown, factors associated with food consumption affect postprandial platelet aggregation. We propose that protocols for control of pre-analytical variables in platelet aggregation studies should make a fasting sample mandatory rather than "preferable" unless the objective of the study is to measure acute effects in response to a medication or food. PMID:19929247

  5. Platelet Aggregation and Mental Stress Induced Myocardial Ischemia: Results from the REMIT Study

    PubMed Central

    Jiang, Wei; Boyle, Stephen H.; Ortel, Thomas L.; Samad, Zainab; Velazquez, Eric J.; Harrison, Robert W.; Wilson, Jennifer; Kuhn, Cynthia; Williams, Redford B.; O’Connor, Christopher M.; Becker, Richard C.

    2015-01-01

    BACKGROUND Mental stress-induced myocardial ischemia (MSIMI) is common in patients with ischemic heart disease (IHD) and associated with a poorer cardiovascular prognosis. Platelet hyperactivity is an important factor in acute coronary syndrome. This study examined associations between MSIMI and resting and mental stress-induced platelet activity. METHODS Eligible patients with clinically stable IHD underwent a battery of 3 mental stress tests during the recruitment phase of REMIT (Responses of Myocardial Ischemia to Escitalopram Treatment) study. MSIMI was assessed by echocardiography and electrocardiography. Ex vivo platelet aggregation in response to ADP, epinephrine, collagen, serotonin, and combinations of serotonin plus ADP, epinephrine, and collagen were evaluated as was platelet serotonin transporter expression. RESULTS Of the 270 participants who completed mental stress testing, and had both resting and post-stress platelet aggregation evaluation, 43.33% (N=117) met criteria for MSIMI and 18.15% (N=49) had normal left ventricular response to stress (NLVR). The MSIMI group, relative to the NLVR groups, demonstrated heightened mental stress-induced aggregation responses, as measured by area under the curve, to collagen 10 μM (6.95[5.54] vs. −14.23[8.75].; p=0.045), epinephrine 10 μM (12.84[4.84] vs. −6.40[7.61].; p=0.037) and to serotonin 10 μM plus ADP 1 μM (6.64[5.29] vs. −27.34[8.34]; p < .001). The resting platelet aggregation and serotonin transporter expression, however, were not different between the two groups. CONCLUSIONS These findings suggest that the dynamic change of platelet aggregation caused by mental stress may underlie MSIMI. While the importance of these findings requires additional investigation, they raise concern given the recognized relationship between mental stress-induced platelet hyperactivity and cardiovascular events in patients with IHD. PMID:25819856

  6. Palmitic acid-labeled lipids selectively incorporated into platelet cytoskeleton during aggregation

    SciTech Connect

    Packham, M.A.; Guccione, M.A.; Bryant, N.L.; Livne, A. )

    1990-07-01

    Previous experiments showed that during the early stages (20-30 seconds) of aggregation induced by adenosine diphosphate (ADP, 2 microM) or thrombin (0.1 U/mL) of rabbit or human platelets prelabeled with (3H)palmitic acid, labeled lipid became associated with the cytoskeleton isolated after lysis with 1% Triton X-100, 5 mM EGTA (ethylene glycol-bis-(beta-aminoethyl ether))-N,N,N',N'-tetra-acetic acid. The association appeared to be related to the number of sites of contact and was independent of the release of granule contents. We have now investigated the nature of the labeled lipids by thin-layer and column chromatography and found differences between the distribution of the label in intact platelets (both stimulated and unstimulated) and the isolated cytoskeletons. In both species, and with either ADP or thrombin as aggregating agent, 70-85% of the label in both intact platelets and in the cytoskeletons was in phospholipids. The distribution of label among the phospholipids in the cytoskeletons was similar to that in intact platelets except that the percentage of label in phosphatidylcholine was significantly higher in the cytoskeletons of human platelets than in the intact platelets, and the percentage of label in phosphatidylserine/phosphatidylinositol was significantly lower in the cytoskeletons of rabbit platelets and thrombin-aggregated human platelets than in intact platelets. The cytoskeletons contained a lower percentage of label in triacylglycerol, diacylglycerol, and cholesterol ester than the intact platelets. Contrary to a report in the literature, we found no evidence for the incorporation of diacylglycerol and palmitic acid into the cytoskeleton.

  7. [Cyclooxygenase inhibitors in some dietary vegetables inhibit platelet aggregation function induced by arachidonic acid].

    PubMed

    Wang, Xin-Hua; Shao, Dong-Hua; Liang, Guo-Wei; Zhang, Ru; Xin, Qin; Zhang, Tao; Cao, Qing-Yun

    2011-10-01

    The study was purposed to investigate whether the cyclooxygenase inhibitors from some dietary vegetables can inhibit platelet aggregation function by the arachidonic acid (AA). The vegetable juice was mixed with platelet rich plasma (PRP), and asprin was used as positive control. The maximum ratio of platelet aggregation induced by AA was measured on the aggregometer; heme and cyclooxygenase-1 (COX(1)) or cyclooxygenase-2 (COX(2)) were added to test tubes containing COX reaction buffer, the mixture was vortex-mixed and exposed to aspirin or vegetable juice, followed by addition of AA and then hydrochloric acid (1 mol/L) was added to stop the COX reaction, followed by chemical reduction with stannous chloride solution. The concentration of COX inhibitors was detected by the enzyme immunoassay kit; vegetable juice (aspirin as positive control) was mixed with whole blood, which was followed by the addition of AA, and then the reaction was stopped by adding indomethacin, centrifuged, then the supernatant was collected, and the plasma thromboxane B(2) (TXB(2)) was measured by radioimmunoassay. The results showed that spinach juice, garlic bolt juice, blanched garlic leave juice and Chinese leek juice could inhibit by 80% human platelet aggregation induced by AA. 4 kinds of vegetables were all found a certain amount of cyclooxygenase inhibitors, which COX(1) and COX(2) inhibitor concentrations of spinach were higher than that of aspirin; 4 vegetable juice could significantly reduce the human plasma concentrations of TXB(2) induced by AA (p < 0.05). It is concluded that 4 kinds of raw vegetables containing cyclooxygenase inhibitors inhibit the production of TXA(2) and thus hinder platelet aggregation. Raw spinach, garlic bolt, blanched garlic and chinese leek inhibit significantly AA-induced human platelet aggregation in vitro. 4 kinds of vegetables may have a good potential perspective of anti-platelet aggregation therapy or prevention of thrombosis.

  8. Mathematical model and numerical method for studying platelet adhesion and aggregation during blood clotting

    SciTech Connect

    Fogelson, A.L.

    1984-10-01

    The repair of small blood vessels and the pathological growth of internal blood clots involve the formation of platelet aggregates adhering to portions of the vessel wall. Our microscopic model represents blood by a suspension of discrete massless platelets in a viscous incompressible fluid. Platelets are initially noncohesive; however, if stimulated by an above-threshold concentration of the chemical ADP or by contact with the adhesive injured region of the vessel wall, they become cohesive and secrete more ADP into the fluid. Cohesion between platelets and adhesion of a platelet to the injured wall are modeled by creating elastic links. Repulsive forces prevent a platelet from coming too close to another platelet or to the wall. The forces affect the fluid motion in the neighborhood of an aggregate. The platelets and secreted ADP both move by fluid advection and diffusion. The equations of the model are studied numerically in two dimensions. The platelet forces are calculated implicitly by minimizing a nonlinear energy function. Our minimization scheme merges Gill and Murray's (Math. Programming 7 (1974), 311) modified Newton's method with elements of the Yale sparse matix package. The stream-function formulation of the Stokes' equations for the fluid motion under the influence of platelet forces is solved using Bjorstad's biharmonic solver (''Numerical Solution of the Biharmonic Equation,'' Ph.D. Thesis, Stanford University, 1980). The ADP transport equation is solved with an alternating-direction implicit scheme. A linked-list data structure is introduced to keep track of changing platelet states and changing configurations of interplatelet links.

  9. Echicetin Coated Polystyrene Beads: A Novel Tool to Investigate GPIb-Specific Platelet Activation and Aggregation

    PubMed Central

    Petunin, Alexey; Clemetson, Kenneth J.; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

    von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways. PMID:24705415

  10. Evaluation of Anti-Platelet Aggregation Effect of Some Allium Species

    PubMed Central

    Lorigooini, Zahra; Ayatollahi, Seyed Abdolmajid; Amidi, Salimeh; Kobarfard, Farzad

    2015-01-01

    Epidemiologic studies show that the cardiovascular diseases are associated with multiple factors such as raised serum total cholesterol, increased LDL, increased platelet aggregation, hypertension and smoking. In-vitro studies have confirmed the ability of some plants of Allium species to reduce these parameters. Therefore, we evaluated anti-platelet aggregation effect of some Allium species (Allium ampeloprasum, A. hirtifolium, A. haemanthoides, A. vavillovi, A. atroviolaceum, A. jesdianum, A. shelkovnikovii) using arachidonic acid (AA) and adenosine diphosphate (ADP) as platelet aggregation inducers. The screening results for methanolic extract of Allium species showed that the maximum effect of anti-platelet aggregation was related to A. atroviolaceum. This extract inhibited the in-vitro platelet aggregation induced by AA and ADP with IC50 values of 0.4881 (0.4826-0.4937) mg/ml and 0.4945 (0.4137-0.5911) mg/ml respectively. These results support the hypothesis that the dietary intake of Allium could be beneficial for prevention of cardiovascular diseases. PMID:26664390

  11. The Effect of Ginger (Zingiber officinale) on Platelet Aggregation: A Systematic Literature Review

    PubMed Central

    Marx, Wolfgang; McKavanagh, Daniel; McCarthy, Alexandra L.; Bird, Robert; Ried, Karin; Chan, Alexandre; Isenring, Liz

    2015-01-01

    Background The potential effect of ginger on platelet aggregation is a widely-cited concern both within the published literature and to clinicians; however, there has been no systematic appraisal of the evidence to date. Methods Using the PRISMA guidelines, we systematically reviewed the results of clinical and observational trials regarding the effect of ginger on platelet aggregation in adults compared to either placebo or baseline data. Studies included in this review stipulated the independent variable was a ginger preparation or isolated ginger compound, and used measures of platelet aggregation as the primary outcome. Results Ten studies were included, comprising eight clinical trials and two observational studies. Of the eight clinical trials, four reported that ginger reduced platelet aggregation, while the remaining four reported no effect. The two observational studies also reported mixed findings. Discussion Many of the studies appraised for this review had moderate risks of bias. Methodology varied considerably between studies, notably the timeframe studied, dose of ginger used, and the characteristics of subjects recruited (e.g. healthy vs. patients with chronic diseases). Conclusion The evidence that ginger affects platelet aggregation and coagulation is equivocal and further study is needed to definitively address this question. PMID:26488162

  12. Platelet aggregation and serum adenosine deaminase (ADA) activity in pregnancy associated with diabetes, hypertension and HIV.

    PubMed

    Leal, Claudio A M; Leal, Daniela B R; Adefegha, Stephen A; Morsch, Vera M; da Silva, José E P; Rezer, João F P; Schrekker, Clarissa M L; Abdalla, Faida H; Schetinger, Maria R C

    2016-07-01

    Platelet aggregation and adenosine deaminase (ADA) activity were evaluated in pregnant women living with some disease conditions including hypertension, diabetes mellitus and human immunodeficiency virus infection. The subject population is consisted of 15 non-pregnant healthy women [control group (CG)], 15 women with normal pregnancy (NP), 7 women with hypertensive pregnancy (HP), 10 women with gestational diabetes mellitus (GDM) and 12 women with human immunodeficiency virus-infected pregnancy (HIP) groups. The aggregation of platelets was checked using an optical aggregometer, and serum ADA activity was determined using the colorimetric method. After the addition of 5 µM of agonist adenosine diphosphate, the percentage of platelet aggregation was significantly (p < 0·05) increased in NP, HP, GDM and HIP groups when compared with the CG, while the addition of 10 µM of the same agonist caused significant (p < 0·05) elevations in HP, GDM and HIP groups when compared with CG. Furthermore, ADA activity was significantly (p < 0·05) enhanced in NP, HP, GDM and HIP groups when compared with CG. In this study, the increased platelet aggregation and ADA activity in pregnancy and pregnancy-associated diseases suggest that platelet aggregation and ADA activity could serve as peripheral markers for the development of effective therapy in the maintenance of homeostasis and some inflammatory process in these pathophysiological conditions. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27273565

  13. Effect of cocoa products and flavanols on platelet aggregation in humans: a systematic review.

    PubMed

    Peluso, Ilaria; Palmery, Maura; Serafini, Mauro

    2015-07-01

    Previous evidence suggested an active role of cocoa products and flavanols in modulating platelet aggregation. However, cocoa flavanols are characterized by a low bioavailability that can deeply affect their presence in biological fluids and raise questions on their biological effect in humans. We performed a systematic search on Medline, Embase, Cochrane and ProQuest databases, until April 2015, on the effect of cocoa products on platelet aggregation in human intervention studies. We identified 13 interventions, of which only five involved repeated administration. Different effects were observed on the basis of the platelet aggregation test used, whereas neither a longer duration of treatment nor a higher dose was associated with a higher inhibition of platelet aggregation. In conclusion, the reviewed results suggest that consumption of cocoa products in bolus administration positively affects platelet aggregation in both healthy subjects and diseased patients. On the other hand, more evidence is required in order to assess the effect of long-term cocoa product ingestion and to identify the bioactive components involved.

  14. The in vitro effect of aspirin on increased whole blood platelet aggregation in oral contraceptive users.

    PubMed

    Norris, L A; Bonnar, J

    1994-05-01

    The effects of triphasic oral contraceptives on whole blood platelet aggregation in 36 Italian women are reported here. Aspirin's effects on platelet aggregation were also studied. 18 women took a triphasic oral contraceptive; 10 women took Trinordiol, while 8 took Trinovum for at least 90 days. The remaining 18 women took nothing and served as controls. The study was aligned with each woman's birth control pill cycle. Blood was taken daily on days 15-21 of their cycle. Either saline solution or acetylsalicylic acid was added to the blood samples and compared. All data was statistically analyzed using unpaired student's t-test. Effects of 3 aggregating agents, ADP, PAF, and EDTA, on platelet aggregation were studied. Arachidonic acid and adrenalin bitartrate were also studied in this manner. An increase in platelet aggregation was observed in women taking oral contraceptives. No difference was found between patients taking Trinordiol and those taking Trinovum. The results of this study indicate an increase in whole blood platelet sensitivity to collagen, adrenalin, and arachidonic acid when using oral contraceptives. Aspirin, at low doses, may have a role in preventing early thrombus formation in women taking oral contraceptives. PMID:8042198

  15. Keishibukuryogan, a Traditional Japanese Medicine, Inhibits Platelet Aggregation in Guinea Pig Whole Blood

    PubMed Central

    Terawaki, Kiyoshi; Noguchi, Masamichi; Yuzurihara, Mitsutoshi; Omiya, Yuji; Ikarashi, Yasushi; Kase, Yoshio

    2015-01-01

    Effects of keishibukuryogan (KBG) on platelet aggregation were investigated. To ensure the specificity of KBG, tokishakuyakusan (TSS) and kamisyoyosan (KSS), which are known to have platelet aggregation-inhibiting effects, and rikkunshito (RKT) and shakuyakukanzoto (SKT), which are considered to be devoid of such effects, were used for comparison. The platelet aggregation of each test drug was measured by the screen filtration pressure method using whole blood of guinea pigs and expressed as a collagen-induced pressure rate (%) or a collagen concentration required for 50% increase in the pressure rate (PATI value). KBG suppressed the collagen-induced whole blood pressure rate increase and increased the PATI value, like TSS and KSS. Neither RKT nor SKT showed these effects. The Moutan cortex and Cinnamomi cortex, the constituent crude drugs of KBG, showed KBG-like pressure rate suppression and PATI-increasing effects. Furthermore, paeonol, a representative component of Moutan cortex, and aspirin which is known to have platelet aggregation-inhibiting activity (COX-1 inhibitor) also showed similar effects. These results suggest that the platelet aggregation-inhibiting activity of the constituent crude drugs Moutan cortex and Cinnamomi cortex is involved in the improving effects of KBG on impaired microcirculation and that paeonol plays a role in these effects. PMID:26379740

  16. Effects of Recombinant Human Megakaryocyte Growth and Development Factor (rHuMGDF) on Platelet Production, Platelet Aggregation, and Thrombosis.

    PubMed

    Lott; Nelson; Toombs

    1998-01-01

    Recombinant human megakaryocyte growth and development factor (rHuMGDF) is a c-mpl ligand that promotes the differentiation of CD34+ precursor cells into megakaryocyte, and then platelets. In experimental animals, injection of this and other c-mpl ligands leads to profound increases in the circulating platelet count in a matter of days. However, c-mpl ligands have also been shown to sensitize platelets to aggregating agents in vitro, raising the possibility that c-mpI ligands may have prothrombotic effects in vivo. Therefore, characterizing rHuMGDF in an in vivo model of thrombosis is a necessary and critical step in defining the in vivo pharmacology of this novel and important hernatopoietic factor, a pegylated form of which is currently in clinical trials. To determine the biologically effective doses in the rabbit, daily subcutaneous injections of rHuMGDF at 0.1, 1.0, or 10 µg/kg were administered ever 7 days. Daily injection of 10 µ/kg produced an approximate fourfold increase in platelet count and 1.0 µ/kg doubled platelet count over the injection period, both of which were statistically significant. The serum concentrations of rHuMGDF were determined 10 minutes following a single intravenous injection with 0.1, 1.0, and 10 µ/kg, and were 0.05 +/- 0.02, 0.98 +/- 0.07, and 21.32 +/- 21.35 ng/ml. To determine whether rHuMGDF can sensitize platelets in vivo, platelet aggregometry was performed on platelets isolated from animals immediately before and 10 minutes after they had been injected intravenously with rHuMGDF (0.1, 1.0, and 10 µ/kg). Intravenous injection of 10 µ/kg produced measurable changes in platelet aggregometry ex vivo, as evidenced by an increased sensitivity of platelets to adenosine diphosphate (ADP). To assess. the in vivo prothrombotic potential of rHuMGDF, a rabbit carotid artery model of cyclic flow reduction (CFR) was used to measure the effect of intravenous rHuMGDF administration on the rate of thrombus formation as assessed by CFR

  17. Effects of dihydropyridines and inorganic calcium blockers on aggregation and on intracellular free calcium in platelets.

    PubMed

    Palés, J; Palacios-Araus, L; López, A; Gual, A

    1991-05-01

    [Ca2+]i increase is necessary in physiological platelet activity, particularly aggregation and release. The increase of [Ca2+]i observed during platelet activation depends in part on Ca2+ influx from the extracellular medium. The participation of voltage-operated Ca2+ channels as a pathway for Ca2+ entry is controversial. In the present study we have attempted to reinvestigate this problem by measuring aggregation and [Ca2+]i changes in platelets activated by ADP or thrombin and incubated with organic or inorganic blockers of calcium channels. The main findings of the present paper can be summarized as follows: (i) Ni2+, Co2+ and Mn2+, well known inorganic blockers of Ca2+ channels, inhibited platelet aggregation induced by ADP or thrombin in a dose-dependent manner, Ni2+ being the most effective agent. (ii) Thrombin induced a rise in free [Ca2+]i in platelets incubated both in 1 mmol/l Ca(2+)-containing medium and in nominally Ca(2+)-free medium; the rise of free [Ca2+]i was in the first case up to 370 +/- 31 nmol/l and in the second case up to 242 +/- 26 nmol/l, indicating that this observed difference was due to Ca2+ entry from the extracellular medium. Co2+ and Ni2+ abolished that difference by inhibiting Ca2+ influx. (iii) Nisoldipine, nitrendipine and nimodipine (10-50 nmol/l) inhibited in a dose-dependent manner platelet aggregation induced by either ADP or thrombin in platelets incubated in normal-Ca2+ normal-K+ medium, also, aggregation was inhibited to a similar extent in platelets incubated in normal-Ca2+ high-K+ medium. (iv) Nisoldipine--the most effective dihydropyridine to inhibit platelet aggregation--also inhibited Ca2+ influx in platelets incubated in normal-Ca2+ medium, either in normal-K+ or high-K+ media. Our data support the existence of voltage-operated, dihydropyridine-sensitive calcium channels (L-type) and a physiological role for them in platelet function.

  18. Platelet hemostasis in patients with metabolic syndrome and type 2 diabetes mellitus: cGMP- and NO-dependent mechanisms in the insulin-mediated platelet aggregation

    PubMed Central

    Suslova, Tatiana E.; Sitozhevskii, Alexei V.; Ogurkova, Oksana N.; Kravchenko, Elena S.; Kologrivova, Irina V.; Anfinogenova, Yana; Karpov, Rostislav S.

    2015-01-01

    Patients with metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) have high risk of microcirculation complications and microangiopathies. An increase in thrombogenic risk is associated with platelet hyperaggregation, hypercoagulation, and hyperfibrinolysis. Factors leading to platelet activation in MetS and T2DM comprise insulin resistance, hyperglycemia, non-enzymatic glycosylation, oxidative stress, and inflammation. This review discusses the role of nitric oxide (NO) in the regulation of platelet adhesion and aggregation processes. NO is synthesized both in endotheliocytes, smooth muscle cells, macrophages, and platelets. Modification of platelet NO-synthase (NOS) activity in MetS patients can play a central role in the manifestation of platelet hyperactivation. Metabolic changes, accompanying T2DM, can lead to an abnormal NOS expression and activity in platelets. Hyperhomocysteinemia, often accompanying T2DM, is a risk factor for cardiovascular accidents. Homocysteine can reduce NO production by platelets. This review provides data on the insulin effects in platelets. Decrease in a number and sensitivity of the insulin receptors on platelets in T2DM can cause platelet hyperactivation. Various intracellular mechanisms of anti-aggregating insulin effects are discussed. Anti-aggregating effects of insulin are mediated by a NO-induced elevation of cGMP and upregulation of cAMP- and cGMP-dependent pathways. The review presents data suggesting an ability of platelets to synthesize humoral factors stimulating thrombogenesis and inflammation. Proinflammatory cytokines are considered as markers of T2DM and cardiovascular complications and are involved in the development of dyslipidemia and insulin resistance. The article provides an evaluation of NO-mediated signaling pathway in the effects of cytokines on platelet aggregation. The effects of the proinflammatory cytokines on functional activity of platelets are demonstrated. PMID:25601838

  19. Platelet hemostasis in patients with metabolic syndrome and type 2 diabetes mellitus: cGMP- and NO-dependent mechanisms in the insulin-mediated platelet aggregation.

    PubMed

    Suslova, Tatiana E; Sitozhevskii, Alexei V; Ogurkova, Oksana N; Kravchenko, Elena S; Kologrivova, Irina V; Anfinogenova, Yana; Karpov, Rostislav S

    2014-01-01

    Patients with metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) have high risk of microcirculation complications and microangiopathies. An increase in thrombogenic risk is associated with platelet hyperaggregation, hypercoagulation, and hyperfibrinolysis. Factors leading to platelet activation in MetS and T2DM comprise insulin resistance, hyperglycemia, non-enzymatic glycosylation, oxidative stress, and inflammation. This review discusses the role of nitric oxide (NO) in the regulation of platelet adhesion and aggregation processes. NO is synthesized both in endotheliocytes, smooth muscle cells, macrophages, and platelets. Modification of platelet NO-synthase (NOS) activity in MetS patients can play a central role in the manifestation of platelet hyperactivation. Metabolic changes, accompanying T2DM, can lead to an abnormal NOS expression and activity in platelets. Hyperhomocysteinemia, often accompanying T2DM, is a risk factor for cardiovascular accidents. Homocysteine can reduce NO production by platelets. This review provides data on the insulin effects in platelets. Decrease in a number and sensitivity of the insulin receptors on platelets in T2DM can cause platelet hyperactivation. Various intracellular mechanisms of anti-aggregating insulin effects are discussed. Anti-aggregating effects of insulin are mediated by a NO-induced elevation of cGMP and upregulation of cAMP- and cGMP-dependent pathways. The review presents data suggesting an ability of platelets to synthesize humoral factors stimulating thrombogenesis and inflammation. Proinflammatory cytokines are considered as markers of T2DM and cardiovascular complications and are involved in the development of dyslipidemia and insulin resistance. The article provides an evaluation of NO-mediated signaling pathway in the effects of cytokines on platelet aggregation. The effects of the proinflammatory cytokines on functional activity of platelets are demonstrated.

  20. Inhibitory effect of compounds from Zingiberaceae species on human platelet aggregation.

    PubMed

    Jantan, I; Raweh, S M; Sirat, H M; Jamil, S; Mohd Yasin, Y H; Jalil, J; Jamal, J A

    2008-04-01

    Twelve compounds isolated from Alpinia mutica Roxb., Kaempferia rotunda Linn., Curcuma xanthorhiza Roxb., Curcuma aromatica Valeton and Zingiber zerumbet Smith (Family: Zingiberaceae) and three synthesized derivatives of xanthorrhizol were evaluated for their ability to inhibit arachidonic acid- (AA), collagen- and ADP-induced platelet aggregation in human whole blood. Antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Among the compounds tested, curcumin from C. aromatica, cardamonin, pinocembrine and 5,6-dehydrokawain from A. mutica and 3-deacetylcrotepoxide from K. rotunda showed strong inhibition on platelet aggregation induced by AA with IC(50) values of less than 84 microM. Curcumin was the most effective antiplatelet compound as it inhibited AA-, collagen- and ADP-induced platelet aggregation with IC(50) values of 37.5, 60.9 and 45.7 microM, respectively.

  1. [Study on steroidal saponins from Dioscorea zingiberensis and their platelet aggregation activities].

    PubMed

    Wang, Jing-jing; Liu, Yi-xun; Wen, Di; Yu, He-shui; Kang, Li-ping; Pang, Xu; Zhao Yang; Ma, Bai-ping; Chen, Yun-dai

    2014-10-01

    Using the absorbent resin, silica gel and ODS column chromatography as well as semi-preparative HPLC, ten compounds were isolated from 70% ethanol extract of tubers of Dioscorea zingiberensis C. H. Wright, and their structures were elucidated as trigoneoside XIIIa (1), parvifloside (2), trigoneoside IVa (3), deltoside (4), protobioside (5), lilioglycoside k (6), zingiberensis newsaponin I (7), deltonin (8), prosapogenin A of dioscin (9), and trillin (10) on the basis of NMR and MS spectral data analysis. Among these compounds, 1, 3, 5 and 6 were isolated from this plant for the first time. In the screening test on platelet aggregation, compounds 7 and 8 exhibited induction effect on platelet aggregation, while compound 9 exhibited significant inhibitory effect on platelet aggregation in vitro.

  2. Platelet-activating factor: mediator of the third pathway of platelet aggregation? A study in three patients with deficient platelet-activating factor synthesis.

    PubMed Central

    Sturk, A; Schaap, M C; ten Cate, J W; Heymans, H S; Schutgens, R B; Przyrembel, H; Borst, P

    1987-01-01

    Thrombin, collagen, and Ca2+-ionophore A23187 aggregate platelets in the presence of inhibitors of the first (ADP-mediated) and second (cyclooxygenase-dependent) pathway of platelet activation. This aggregation, via a third pathway, was hypothesized to be mediated by the alkoxyether lipid platelet-activating factor (PAF). We recently demonstrated virtual absence of plasmalogen-type alkoxyether lipids and deficiency in key enzymes of their biosynthesis in Zellweger patients. We hypothesized that PAF synthesis might also be impaired. We report two Zellweger patients with an undetectable A23187-induced PAF synthesis of leukocytes (patients, less than 3 pmol PAF/10(8) granulocytes (PMN); four age-matched controls, 249-2,757 pmol PAF/10(8) PMN; five adult controls, 291-5,433 pmol PAF/10(8) PMN). In a third patient, residual PAF synthesis was detected. However in all patients the thrombin-induced third mechanism of platelet aggregation was present. We therefore conclude that PAF may not be the mediator of the third pathway. PMID:3805272

  3. Inhibitory Effects of Yuzu and Its Components on Human Platelet Aggregation

    PubMed Central

    Kim, Tae-Ho; Kim, Hye-Min; Park, Se Won; Jung, Yi-Sook

    2015-01-01

    Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, TXB2 formations, and PLCγ/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited TXB2 formation and ADP release. The phosphorylation of PLCγ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of PLCγ and Akt, leading to a decrease in TXB2 formation and granule secretion. PMID:25767683

  4. The Influence of Haemoglobin A1c Levels on Platelet Aggregation and Platelet Turnover in Patients with Coronary Artery Disease Treated with Aspirin

    PubMed Central

    Neergaard-Petersen, Søs; Hvas, Anne-Mette; Grove, Erik Lerkevang; Larsen, Sanne Bøjet; Gregersen, Søren; Kristensen, Steen Dalby

    2015-01-01

    Background Hyperglycaemia may attenuate the antiplatelet effect of aspirin and thereby increase the risk of cardiovascular events. We investigated the influence of increased haemoglobin A1c (HbA1c) levels on platelet aggregation and turnover in a large cohort of patients with coronary artery disease (CAD) with type 2 diabetes, prediabetes or no diabetes. Methods In this observational study, we included 865 stable CAD patients on 75 mg aspirin as mono-therapy of whom 242 patients had type 2 diabetes and were receiving antidiabetic drugs. Among 623 patients without diabetes, we classified 303 patients with prediabetes (HbA1c ≥5.7–6.4% [39–47 mmol/mol]) naive to antidiabetic drugs. Platelet aggregation was evaluated by the Multiplate Analyzer using arachidonic acid and collagen and by the VerifyNow Aspirin. Platelet turnover was evaluated by immature platelets using flow cytometry and platelet activation by soluble P-selectin. Results CAD patients with type 2 diabetes had higher platelet aggregation (all p-values <0.01), platelet turnover (immature platelet count, p<0.01) and platelet activation (p<0.001) than patients without diabetes. CAD patients with prediabetes had increased platelet aggregation (p = 0.02) and platelet count (p = 0.02) compared with patients without diabetes. Increased levels of HbA1c correlated positively with increased platelet aggregation using arachidonic acid (r = 0.19, p<0.0001), collagen (r = 0.10, p<0.01) and VerifyNow (r = 0.15, p<0.0001), and with platelet count (r = 0.08, p = 0.01), immature platelet count (r = 0.11, p<0.001) and soluble P-selectin (r = 0.15, p<0.0001). These associations were mainly evident in non-diabetic and prediabetic CAD patients. Conclusions CAD patients with prediabetes and diabetes may have attenuated antiplatelet effect of aspirin compared with CAD patients without diabetes. This may be related to increased platelet count in patients with prediabetes. Increased levels of HbA1c correlated positively

  5. Effects of high flavanol dark chocolate on cardiovascular function and platelet aggregation.

    PubMed

    Rull, Gurvinder; Mohd-Zain, Zetty N; Shiel, Julian; Lundberg, Martina H; Collier, David J; Johnston, Atholl; Warner, Timothy D; Corder, Roger

    2015-08-01

    Regular consumption of chocolate and cocoa products has been linked to reduced cardiovascular mortality. This study compared the effects of high flavanol dark chocolate (HFDC; 1064mg flavanols/day for 6weeks) and low flavanol dark chocolate (LFDC; 88mg flavanols/day for 6weeks) on blood pressure, heart rate, vascular function and platelet aggregation in men with pre-hypertension or mild hypertension. Vascular function was assessed by pulse wave analysis using radial artery applanation tonometry in combination with inhaled salbutamol (0.4mg) to assess changes due to endothelium-dependent vasodilatation. HFDC did not significantly reduce blood pressure compared to baseline or LFDC. Heart rate was increased by LFDC compared to baseline, but not by HFDC. Vascular responses to salbutamol tended to be greater after HFDC. Platelet aggregation induced by collagen or the thromboxane analogue U46619 was unchanged after LFDC or HFDC, whereas both chocolates reduced responses to ADP and the thrombin receptor activator peptide, SFLLRNamide (TRAP6), relative to baseline. Pre-incubation of platelets with theobromine also attenuated platelet aggregation induced by ADP or TRAP6. We conclude that consumption of HFDC confers modest improvements in cardiovascular function. Platelet aggregation is modulated by a flavanol-independent mechanism that is likely due to theobromine.

  6. Interference of IgG, IgG aggregates and immune complexes in tests for platelet autoantibodies.

    PubMed

    Helmerhorst, F M; Smeenk, R J; Hack, C E; Engelfriet, C P; von dem Borne, A E

    1983-11-01

    Three techniques, based on the antiglobulin principle, used for the detection of autoantibodies against platelets, were compared; the antiglobulin consumption assay (QACA), the platelet radioactive antiglobulin test (PRAT) and the platelet suspension immunofluorescence test (PSIFT). Upon incubation of normal donor platelets with purified IgG, in concentrations higher than that in serum, an increased amount of platelet-associated IgG was demonstrated only in the QACA. Upon incubation with aggregated IgG, all three tests became positive, but the PSIFT only with high concentrations of aggregates. Binding of soluble C1q-binding immune complexes (IC), which consisted of tetanus toxoid and IgG antitetanus antibodies (TaT) to normal donor platelets, was only detectable in the QACA. However, a positive result was obtained in all three tests with platelets incubated with soluble DNA-IgG-antiDNA antibodies (DaD) IC. Fixation of the platelets with paraformaldehyde prevented the binding and the detection of the DaD-IC, but not of IgG, aggregated IgG or TaT-IC. Eluates from platelets incubated with aggregated IgG, TaT- or DaD-IC did not react with normal donor platelets in the three techniques, in contrast to eluates from platelets sensitized with platelet antibodies.

  7. Inhibition of collagen-induced platelet aggregation by antibodies to distinct types of collagens.

    PubMed Central

    Balleisen, L; Nowack, H; Gay, S; Timpl, R

    1979-01-01

    Aggregation of platelets by fibrils formed from collagens type I, II and III could be inhibited by coating the fibrils with anti-collagen antibodies or Fab fragments. Similar results were obtained in a clot-retraction assay. Inhibition was achieved with stoichiometric amounts of antibodies and was specific for each type of collagen. Aggregation caused by a mixture of type-I and -III collagens could only be inhibited by a mixture of antibodies against both collagens. The data show that each interstitial collagen is capable of interacting with platelets and do not support the concept of an outstanding activity of type-III collagen. Images PLATE 1 PMID:395952

  8. Effect of diabetic duration on hemorheological properties and platelet aggregation in streptozotocin-induced diabetic rats

    PubMed Central

    Yeom, Eunseop; Byeon, Hyeokjun; Lee, Sang Joon

    2016-01-01

    Diabetes mellitus with abnormal glucose concentration is associated with changes in hemorheological properties, endothelial function, and platelets hyperactivity. Disturbances may significantly be responsible for diabetes-related vascular complications. In this study, hemorheological and hemodynamic properties were measured according to diabetic duration after streptozotocin treatment in rats. For ex vivo measurements, an extracorporeal model was adopted. Flow rate and blood viscosity were measured using a microfluidic device. Erythrocyte aggregation and morphological parameters of erythrocytes were measured by modified erythrocyte sedimentation rate and the phase-contrast holography under in vitro conditions. The platelet aggregation and mean pressure in the femoral artery were estimated under ex vivo conditions. Hemorheological properties including blood viscosity, erythrocyte aggregation and shape parameters for the control group are significantly different with those for diabetic groups. The changes with respect to diabetic duration were relatively unnoticeable. However, the platelet aggregation is strongly dependent on the diabetic duration. Based on these results, hyperglycemia exposure may induce hemorheological variations in early stages of diabetes mellitus. High platelet aggregation may become more pronounced according to the diabetic duration caused by variations in hemorheological properties resulting in endothelial dysfunction. This study would be helpful in understanding the effects of diabetic duration on biophysical properties. PMID:26898237

  9. Plasma L5 levels are elevated in ischemic stroke patients and enhance platelet aggregation.

    PubMed

    Shen, Ming-Yi; Chen, Fang-Yu; Hsu, Jing-Fang; Fu, Ru-Huei; Chang, Chia-Ming; Chang, Chiz-Tzung; Liu, Chung-Hsiang; Wu, Jia-Rong; Lee, An-Sheng; Chan, Hua-Chen; Sheu, Joen-Rong; Lin, Shinn-Zong; Shyu, Woei-Cherng; Sawamura, Tatsuya; Chang, Kuan-Cheng; Hsu, Chung Y; Chen, Chu-Huang

    2016-03-10

    L5, the most electronegative and atherogenic subfraction of low-density lipoprotein (LDL), induces platelet activation. We hypothesized that plasma L5 levels are increased in acute ischemic stroke patients and examined whether lectin-like oxidized LDL receptor-1 (LOX-1), the receptor for L5 on endothelial cells and platelets, plays a critical role in stroke. Because amyloid β (Aβ) stimulates platelet aggregation, we studied whether L5 and Aβ function synergistically to induce prothrombotic pathways leading to stroke. Levels of plasma L5, serum Aβ, and platelet LOX-1 expression were significantly higher in acute ischemic stroke patients than in controls without metabolic syndrome (P < .01). In mice subjected to focal cerebral ischemia, L5 treatment resulted in larger infarction volumes than did phosphate-buffered saline treatment. Deficiency or neutralizing of LOX-1 reduced infarct volume up to threefold after focal cerebral ischemia in mice, illustrating the importance of LOX-1 in stroke injury. In human platelets, L5 but not L1 (the least electronegative LDL subfraction) induced Aβ release via IκB kinase 2 (IKK2). Furthermore, L5+Aβ synergistically induced glycoprotein IIb/IIIa receptor activation; phosphorylation of IKK2, IκBα, p65, and c-Jun N-terminal kinase 1; and platelet aggregation. These effects were blocked by inhibiting IKK2, LOX-1, or nuclear factor-κB (NF-κB). Injecting L5+Aβ shortened tail-bleeding time by 50% (n = 12; P < .05 vs L1-injected mice), which was prevented by the IKK2 inhibitor. Our findings suggest that, through LOX-1, atherogenic L5 potentiates Aβ-mediated platelet activation, platelet aggregation, and hemostasis via IKK2/NF-κB signaling. L5 elevation may be a risk factor for cerebral atherothrombosis, and downregulating LOX-1 and inhibiting IKK2 may be novel antithrombotic strategies. PMID:26679863

  10. Plasma L5 levels are elevated in ischemic stroke patients and enhance platelet aggregation

    PubMed Central

    Shen, Ming-Yi; Chen, Fang-Yu; Hsu, Jing-Fang; Fu, Ru-Huei; Chang, Chia-Ming; Chang, Chiz-Tzung; Liu, Chung-Hsiang; Wu, Jia-Rong; Lee, An-Sheng; Chan, Hua-Chen; Sheu, Joen-Rong; Lin, Shinn-Zong; Shyu, Woei-Cherng; Sawamura, Tatsuya; Chang, Kuan-Cheng; Hsu, Chung Y.

    2016-01-01

    L5, the most electronegative and atherogenic subfraction of low-density lipoprotein (LDL), induces platelet activation. We hypothesized that plasma L5 levels are increased in acute ischemic stroke patients and examined whether lectin-like oxidized LDL receptor-1 (LOX-1), the receptor for L5 on endothelial cells and platelets, plays a critical role in stroke. Because amyloid β (Aβ) stimulates platelet aggregation, we studied whether L5 and Aβ function synergistically to induce prothrombotic pathways leading to stroke. Levels of plasma L5, serum Aβ, and platelet LOX-1 expression were significantly higher in acute ischemic stroke patients than in controls without metabolic syndrome (P < .01). In mice subjected to focal cerebral ischemia, L5 treatment resulted in larger infarction volumes than did phosphate-buffered saline treatment. Deficiency or neutralizing of LOX-1 reduced infarct volume up to threefold after focal cerebral ischemia in mice, illustrating the importance of LOX-1 in stroke injury. In human platelets, L5 but not L1 (the least electronegative LDL subfraction) induced Aβ release via IκB kinase 2 (IKK2). Furthermore, L5+Aβ synergistically induced glycoprotein IIb/IIIa receptor activation; phosphorylation of IKK2, IκBα, p65, and c-Jun N-terminal kinase 1; and platelet aggregation. These effects were blocked by inhibiting IKK2, LOX-1, or nuclear factor–κB (NF-κB). Injecting L5+Aβ shortened tail-bleeding time by 50% (n = 12; P < .05 vs L1-injected mice), which was prevented by the IKK2 inhibitor. Our findings suggest that, through LOX-1, atherogenic L5 potentiates Aβ-mediated platelet activation, platelet aggregation, and hemostasis via IKK2/NF-κB signaling. L5 elevation may be a risk factor for cerebral atherothrombosis, and downregulating LOX-1 and inhibiting IKK2 may be novel antithrombotic strategies. PMID:26679863

  11. Inhibitory effects of kiwifruit extract on human platelet aggregation and plasma angiotensin-converting enzyme activity.

    PubMed

    Dizdarevic, Lili L; Biswas, Dipankar; Uddin, M D Main; Jørgenesen, Aud; Falch, Eva; Bastani, Nasser E; Duttaroy, Asim K

    2014-01-01

    Previous human studies suggest that supplementation with kiwifruits lowers several cardiovascular risk factors such as platelet hyperactivity, blood pressure and plasma lipids. The cardiovascular health benefit of fruit and vegetables is usually attributed to the complex mixture of phytochemicals therein; however, kiwifruit's cardioprotective factors are not well studied. In this study, we investigated the effects of kiwifruit extract on human blood platelet aggregation and plasma angiotensin-converting enzyme (ACE) activity. A sugar-free, heat-stable aqueous extract with molecular mass less than 1000 Da was prepared from kiwifruits. Typically, 100 g kiwifruits produced 66.3 ± 5.8 mg (1.2 ± 0.1 mg CE) of sugar-free kiwifruit extract (KFE). KFE inhibited both human platelet aggregation and plasma ACE activity in a dose-dependent manner. KFE inhibited platelet aggregation in response to ADP, collagen and arachidonic acid, and inhibitory action was mediated in part by reducing TxA2 synthesis. The IC50 for ADP-induced platelet aggregation was 1.6 ± 0.2 mg/ml (29.0 ± 3.0 μg CE/ml), whereas IC50 for serum ACE was 0.6 ± 0.1 mg/ml (11.0 ± 1.2 μg CE/ml). Consuming 500 mg of KFE (9.0 mg CE) in 10 g margarine inhibited ex vivo platelet aggregation by 12.7%, 2 h after consumption by healthy volunteers (n = 9). All these data indicate that kiwifruit contains very potent antiplatelet and anti-ACE components. Consuming kiwifruits might be beneficial as both preventive and therapeutic regime in cardiovascular disease. PMID:24219176

  12. Acetaminophen and meloxicam inhibit platelet aggregation and coagulation in blood samples from humans.

    PubMed

    Martini, Angela K; Rodriguez, Cassandra M; Cap, Andrew P; Martini, Wenjun Z; Dubick, Michael A

    2014-12-01

    Acetaminophen (Ace) and meloxicam (Mel) are the two types of analgesic and antipyretic medications. This study investigated the dose responses of acetaminophen and meloxicam on platelet aggregation and coagulation function in human blood samples. Blood samples were collected from six healthy humans and processed to make platelet-adjusted (100 × 10 cells/μl) blood samples. Acetaminophen (Tylenol, Q-PAP, 100 mg/ml) was added at the doses of 0 μg/ml (control), 214 μg/ml (the standard dose, 1 ×), 4 ×, 8 ×, 10 ×, 12 ×, 16 ×, and 20 ×. Similarly, meloxicam (Metacam, 5 mg/ml) was added at doses of 0 μg/ml (control), 2.85 μg/ml (the standard dose, 1 ×), 4 ×, 8 ×, 10 ×, 12 ×, 16 ×, and 20 ×. Fifteen minutes after the addition of acetaminophen and/or meloxicam, platelet aggregation was stimulated with collagen (2 μg/ml) or arachidonic acid (0.5 mmol/l) and assessed using a Chrono-Log 700 aggregometer. Coagulation function was assessed by prothrombin time (PT), activated partial thromboplastin time (aPTT), and using Rotem thrombelastogram. A robust inhibition by acetaminophen and/or meloxicam was observed in arachidonic acid-stimulated platelet aggregation starting at 1 × dose. Collagen-stimulated platelet aggregation was inhibited by ACE starting at 1 × (78 ± 10% of control), and by meloxicam starting at 4 × (72 ± 5% of control, both P < 0.05). The inhibitions by acetaminophen and meloxicam combined were similar to those by acetaminophen or meloxicam. aPTT was prolonged by meloxicam starting at 4 ×. No changes were observed in PT or any of Rotem measurements by acetaminophen and/or meloxicam. Acetaminophen and meloxicam compromised platelet aggregation and aPTT. Further effort is warranted to characterize the effects of acetaminophen and meloxicam on bleeding in vivo.

  13. Inhibitory effects of kiwifruit extract on human platelet aggregation and plasma angiotensin-converting enzyme activity.

    PubMed

    Dizdarevic, Lili L; Biswas, Dipankar; Uddin, M D Main; Jørgenesen, Aud; Falch, Eva; Bastani, Nasser E; Duttaroy, Asim K

    2014-01-01

    Previous human studies suggest that supplementation with kiwifruits lowers several cardiovascular risk factors such as platelet hyperactivity, blood pressure and plasma lipids. The cardiovascular health benefit of fruit and vegetables is usually attributed to the complex mixture of phytochemicals therein; however, kiwifruit's cardioprotective factors are not well studied. In this study, we investigated the effects of kiwifruit extract on human blood platelet aggregation and plasma angiotensin-converting enzyme (ACE) activity. A sugar-free, heat-stable aqueous extract with molecular mass less than 1000 Da was prepared from kiwifruits. Typically, 100 g kiwifruits produced 66.3 ± 5.8 mg (1.2 ± 0.1 mg CE) of sugar-free kiwifruit extract (KFE). KFE inhibited both human platelet aggregation and plasma ACE activity in a dose-dependent manner. KFE inhibited platelet aggregation in response to ADP, collagen and arachidonic acid, and inhibitory action was mediated in part by reducing TxA2 synthesis. The IC50 for ADP-induced platelet aggregation was 1.6 ± 0.2 mg/ml (29.0 ± 3.0 μg CE/ml), whereas IC50 for serum ACE was 0.6 ± 0.1 mg/ml (11.0 ± 1.2 μg CE/ml). Consuming 500 mg of KFE (9.0 mg CE) in 10 g margarine inhibited ex vivo platelet aggregation by 12.7%, 2 h after consumption by healthy volunteers (n = 9). All these data indicate that kiwifruit contains very potent antiplatelet and anti-ACE components. Consuming kiwifruits might be beneficial as both preventive and therapeutic regime in cardiovascular disease.

  14. The effects of aspirin and fish oil consumption on lysophosphatidylcholines and lysophosphatidic acids and their correlates with platelet aggregation in adults with diabetes mellitus.

    PubMed

    Abdolahi, Amir; Georas, Steve N; Brenna, J Thomas; Cai, Xueya; Thevenet-Morrison, Kelly; Phipps, Richard P; Lawrence, Peter; Mousa, Shaker A; Block, Robert C

    2014-01-01

    Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The influence of co-administration of aspirin and fish oil (FO) on plasma lysophospholipids in subjects with diabetes is poorly characterized. Thirty adults with type 2 diabetes mellitus were treated with aspirin (81mg/day) for seven days, then with FO (4g/day) for 28 days, then in combination for another seven days. Lysophospholipids and platelet measures were determined after acute (4h) and chronic (7 days) ingestion of aspirin, FO, or both in combination. FO ingestion reduced all lysophosphatidic acid (LPA) concentrations, while EPA (20:5n-3) and DHA (22:6n-3) lysophosphatidylcholine (LPC) concentrations significantly increased after FO alone and in combination with aspirin. In vitro arachidonic acid-induced platelet aggregation was most strongly correlated with palmitoleic (16:1) and oleic (18:1) LPA and LPC concentrations at all time points. The ingestion of these agents may reduce cardiovascular disease risk in diabetic adults, with a disrupted lipid milieu, via lysolipid mediated mechanisms.

  15. Ex vivo human platelet aggregation induced by decompression during reduced barometric pressure, hydrostatic, and hydrodynamic (Bernoulli) effect.

    PubMed

    Murayama, M

    1984-03-01

    Decompression of human platelet-rich plasma (PRP) in siliconized glass or plastic to 380 mm Hg for 3 hours at 38 degrees C produced platelet aggregation independent of pO2. Aggregation also took place when PRP was compressed to 8,000 PSI and then decompressed slowly to one atmosphere (14.7 PSI) without gas bubble formation. Platelets also aggregated when plasma was decompressed hydrodynamically (Bernoulli effect) at room temperature. It was also found that the drugs piracetam (2-oxypyrolidine acetamide) and pentoxifylline (1-(5-oxohexyl)-theobromine) at 0.5 and 1.0 mM prevent thrombocyte aggregation. Implications for mountain sickness are discussed.

  16. Validity of Particle-Counting Method Using Laser-Light Scattering for Detecting Platelet Aggregation in Diabetic Patients

    NASA Astrophysics Data System (ADS)

    Nakadate, Hiromichi; Sekizuka, Eiichi; Minamitani, Haruyuki

    We aimed to study the validity of a new analytical approach that reflected the phase from platelet activation to the formation of small platelet aggregates. We hoped that this new approach would enable us to use the particle-counting method with laser-light scattering to measure platelet aggregation in healthy controls and in diabetic patients without complications. We measured agonist-induced platelet aggregation for 10 min. Agonist was added to the platelet-rich plasma 1 min after measurement started. We compared the total scattered light intensity from small aggregates over a 10-min period (established analytical approach) and that over a 2-min period from 1 to 3 min after measurement started (new analytical approach). Consequently platelet aggregation in diabetics with HbA1c ≥ 6.5% was significantly greater than in healthy controls by both analytical approaches. However, platelet aggregation in diabetics with HbA1c < 6.5%, i.e. patients in the early stages of diabetes, was significantly greater than in healthy controls only by the new analytical approach, not by the established analytical approach. These results suggest that platelet aggregation as detected by the particle-counting method using laser-light scattering could be applied in clinical examinations by our new analytical approach.

  17. Nutmeg oil: identification and quantitation of its most active constituents as inhibitors of platelet aggregation.

    PubMed

    Janssens, J; Laekeman, G M; Pieters, L A; Totte, J; Herman, A G; Vlietinck, A J

    1990-05-01

    Three distilled or commercially available nutmeg oils were analysed and their chemical composition compared with their capacity to inhibit platelet aggregation in vitro. It could be clearly shown that eugenol and isoeugenol play the major role in the detected activity of nutmeg. Medicinally, it appears that nutmeg oil and nutmeg powder can be replaced by eugenol and/or isoeugenol. PMID:2115612

  18. New urushiols with platelet aggregation inhibitory activities from resin of Toxicodendron vernicifluum.

    PubMed

    Xie, Ya; Zhang, Jie; Liu, Wenyuan; Xie, Ning; Feng, Feng; Qu, Wei

    2016-07-01

    Eight new urushiol-type compounds (1-7b), along with seven known compounds were isolated from the resin of Toxicodendron vernicifluum Stokes. Their structures were determined by extensive spectroscopic methods, included (1)H NMR, (13)C NMR, HMQC, HMBC, HRESIMS, EI-MS in combination with CD methods. All the compounds except 7a and 7b were evaluated for their anti-platelet aggregation activities in vitro. Among them, compound 5 (IC50=5.12±0.85μmol/L), with a vic-diol moiety in the long alkyl chain showed the most potent inhibitory of platelet aggregation activity induced by ADP. In addition, compound 6 showed the effect of anti-platelet aggregation induced by AA with the IC50 value of 3.09±0.70μmol/L. Thus, these compounds might be the active components to the traditional use of Resina Toxicodendri for breaking up blood stasis, which could be related to the anti-platelet aggregation. PMID:27156871

  19. Echistatin. A potent platelet aggregation inhibitor from the venom of the viper, Echis carinatus.

    PubMed

    Gan, Z R; Gould, R J; Jacobs, J W; Friedman, P A; Polokoff, M A

    1988-12-25

    A 49-residue protein, echistatin, which inhibits platelet aggregation, was purified from the venom of the saw-scaled viper Echis carinatus. The purification procedure included gel filtration on Sephadex G-50, cation-exchange chromatography on Mono S, and C18 reverse-phase high pressure liquid chromatography. The purified protein was homogeneous as judged by polyacrylamide gel electrophoresis, isoelectric focusing, reverse-phase high pressure liquid chromatography, and NH2-terminal sequence analysis. Echistatin is a single-chain polypeptide with a molecular weight of 5400 and a native isoelectric point of 8.3. The most abundant amino acid, cysteine, accounts for 8 of the 49 residues in the protein. A 10-residue segment of echistatin shows 90% identity to a portion of the sequence of trigramin, a platelet aggregation inhibitor from the green tree viper Trimereserus gramineus (Huang, T.-F., Holt, J. C., Lukasiewicz, H., and Niewiarowski, S. (1987) J. Biol. Chem. 262, 16157-16163). Echistatin contains the sequence arginine-glycine-aspartic acid, which is common to proteins which bind to the glycoprotein IIb/IIIa complex. It also contains the sequence proline-arginine-asparagine-proline, which is found in the A alpha chain of human fibrinogen at position 267-270. The purified protein inhibits fibrinogen-dependent platelet aggregation initiated by ADP with an IC50 of 3 x 10(-8) M and also prevents aggregation initiated by thrombin, epinephrine, collagen, or platelet-activating factor. Reduction of echistatin abolished its inhibitory activity. PMID:3198653

  20. The effect of naloxone and cyproheptadine on pulmonary platelet trapping, hypotension, and platelet aggregability in traumatized dogs

    SciTech Connect

    Almqvist, P.; Kuenzig, M.; Schwartz, S.I.

    1983-05-01

    Adult respiratory distress syndrome (ARDS) is a serious complication of trauma and sepsis. We have earlier shown naloxone, an opiate antagonist, and cyproheptadine, an antiserotonin drug, to be effective in reducing pulmonary platelet trapping (PPT), which is thought to play an important role in the evolution of ARDS in endotoxin-shocked dogs. Endorphins are implicated as pathophysiologic factors in shock, and serotonin is a possible mediator of their action. The present study shows naloxone and cyproheptadine to be equally effective in protecting against PPT in dogs subjected to trauma, and when naloxone is given before the trauma it also obviates the hypotension associated with trauma. In addition, the naloxone- and cyproheptadine-treated animals did not show the increased platelet aggregability usually seen in traumatized dogs.

  1. Inhibitory effect of sulfur-containing compounds in Scorodocarpus borneensis Becc. on the aggregation of rabbit platelets.

    PubMed

    Lim, H; Kubota, K; Kobayashi, A; Seki, T; Ariga, T

    1999-02-01

    The inhibitory effects of three pure compounds isolated from wood garlic, 2,4,5-trithiahexane (I), 2,4,5,7-tetrathiaoctane (II), and 2,4,5,7-tetrathiaoctane 2,2-dioxide (III), on rabbit platelet aggregation induced by collagen, arachidonic acid, U46619, ADP (adenosine 5'-diphosphate), PAF (platelet aggregating factor), and thrombin were studied in vitro. The anti-aggregating activity of 2,4,5,7-tetrathiaoctane 4,4-dioxide (IV) was also measured with collagen and arachidonic acid. I, II, III, and IV inhibited the platelet aggregation induced by all tested agonists. I, II, and III exhibited a stronger inhibitory effect against the thrombin-induced aggregation of GFP (gel-filtered platelets) than against the aggregation induced by the other agonists. Notably, the IC50 value for III was 4 microM, which is approximately 2.5 times stronger than MATS (methyl allyl trisulfide), a major anti-platelet compound isolated from garlic. In inhibiting collagen-induced aggregation, II was as potent as MATS and aspirin, with a marked disaggregation effect on the secondary aggregation by arachidonic acid, at the rate of 47.05%/min at a concentration of 10(-4) M. I, II, and III also suppressed U46619-induced aggregation. These results suggest that sulfur-containing compounds in wood garlic not only inhibit arachidonic acid metabolism but also suppress aggregation in association with the function of the platelet plasma membrane. PMID:10192909

  2. Platelets

    MedlinePlus

    ... are related to immunity and fighting infection. Platelet Production Platelets are produced in the bone marrow, the ... platelet destruction and also decreased bone marrow platelet production. These problems are caused by autoantibodies. Antibodies are ...

  3. Platelet factor XIIIa release during platelet aggregation and plasma clot strength measured by thrombelastography in patients with coronary artery disease treated with clopidogrel.

    PubMed

    Kreutz, Rolf P; Owens, Janelle; Lu, Deshun; Nystrom, Perry; Jin, Yan; Kreutz, Yvonne; Desta, Zeruesenay; Flockhart, David A

    2015-01-01

    It has been estimated that up to half of circulating factor XIIIa (FXIIIa) is stored in platelets. The release of FXIIIa from platelets upon stimulation with adenosine diphosphate (ADP) in patients with coronary artery disease treated with dual antiplatelet therapy has not been previously examined. Samples from 96 patients with established coronary artery disease treated with aspirin and clopidogrel were examined. Platelet aggregation was performed by light transmittance aggregometry in platelet-rich plasma (PRP), with platelet-poor plasma (PPP) as reference, and ADP 5 µM as agonist. Kaolin-activated thrombelastography (TEG) was performed in citrate PPP. PRP after aggregation was centrifuged and plasma supernatant (PSN) collected. FXIIIa was measured in PPP and PSN. Platelet aggregation after stimulation with ADP 5 µM resulted in 24% additional FXIIIa release in PSN as compared to PPP (99.3 ± 27 vs. 80.3 ± 24%, p < 0.0001). FXIIIa concentration in PSN correlated with maximal plasma clot strength (TEG-G) (r = 0.48, p < 0.0001), but not in PPP (r = 0.15, p = 0.14). Increasing quartiles of platelet-derived FXIIIa were associated with incrementally higher TEG-G (p = 0.012). FXIIIa release was similar between clopidogrel responders and non-responders (p = 0.18). In summary, platelets treated with aspirin and clopidogrel release a significant amount of FXIIIa upon aggregation by ADP. Platelet-derived FXIIIa may contribute to differences in plasma TEG-G, and thus, in part, provide a mechanistic explanation for high clot strength observed as a consequence of platelet activation. Variability in clopidogrel response does not significantly influence FXIIIa release from platelets. PMID:24833046

  4. Effects of garlic extract and of three pure components isolated from it on human platelet aggregation, arachidonate metabolism, release reaction and platelet ultrastructure.

    PubMed

    Apitz-Castro, R; Cabrera, S; Cruz, M R; Ledezma, E; Jain, M K

    1983-10-15

    We studied the effect of the methanol extract of garlic bulbs (EOG) and of three pure components isolated from it (F1, F2, F3), on human platelet aggregation induced by ADP, epinephrine, collagen, thrombin, arachidonate, PAF, and the ionophore A-23187. Incubation of PRP with EOG, either in methanol or in homologous PPP, inhibits platelet aggregation induced by all of the above mentioned agonists. F1, F2, and F3 also inhibit platelet aggregation, however, F3 was about four times more potent. Addition of EOG or F3 to platelets that have already been irreversibly aggregated by 10 microM ADP, induces rapid deaggregation. Inhibition of aggregation was still present after three hours. The inhibitory effect persisted even after the treated platelets were Gel-Filtered (GFP) or separated from plasma through a metrizamide gradient and resuspended in new homologous PPP. Thrombin-induced release of ATP from GFP was inhibited by 75-80% after EOG or F3 treatment. Incorporation of [3-H]-arachidonate by intact platelets was decreased by 50-60% in treated platelets. However, platelets incubated with the inhibitors after incorporation of radiolabeled arachidonate, although did not aggregate, produced, after thrombin activation similar amounts of radiolabeled TXB2 and lipoxygenase products as the controls. Electron microscopy of inhibited platelets, in the presence of thrombin, showed no degranulation but an increase of spherical forms. Our results suggest that the effects described might be mediate by a perturbation of the physicochemical properties of the plasma membrane rather than by affecting arachidonate or calcium metabolism in the cells. Chemical structures of F1, F2 and F3 have been provisionally assigned: F1 is diallytrisulfide, F2 is 2-vinyl-1,3-dithiene, and F3 is most probably allyl 1,5-hexadienyltrisulfide. PMID:6419374

  5. [Anti-platelet aggregation bioassay based quality control for XST capsules].

    PubMed

    Han, Bing; Mao, Xin; Han, Shu-xian; Chen, Ying; Xiang, Yan-hua; Ge, Yi-meng; Liao, Fu-long; You, Yun

    2015-12-01

    A in vitro platelet aggregation bioassay was developed for the quality control of XST capsules. The in vitro anti-platelet aggregation effect in rats was observed to detect the bioactivity of XST capsules. Panax notoginseng saponins and Xuesaitong lyophilizedpowder for injection were taken as standard control substances to determine the potency. According to the results, XST capsules showeda significant inhibitory effect on thrombin-induced platelet aggregation in a dose-dependent manner. The in vitro anti-platelet activity oflyophilized powder for injection was stabler than that of Panax notoginseng saponins, and so suitable to serve as a standard control substance. The biological potency of XST capsules compared with standard control substance was detected by using parallel line assay. According to the results, the established bioassay method had a good repeatability (RSD 2.92%). The sample test results could pass thereliability test(linear deviation P > 0.05, parallel deviation P > 0.05). This bioassay method could be used as one of the complementary quality control methods for XST capsules.

  6. Elucidation of Acid-induced Unfolding and Aggregation of Human Immunoglobulin IgG1 and IgG2 Fc

    PubMed Central

    Latypov, Ramil F.; Hogan, Sabine; Lau, Hollis; Gadgil, Himanshu; Liu, Dingjiang

    2012-01-01

    Understanding the underlying mechanisms of Fc aggregation is an important prerequisite for developing stable and efficacious antibody-based therapeutics. In our study, high resolution two-dimensional nuclear magnetic resonance (NMR) was employed to probe structural changes in the IgG1 Fc. A series of 1H-15N heteronuclear single-quantum correlation NMR spectra were collected between pH 2.5 and 4.7 to assess whether unfolding of CH2 domains precedes that of CH3 domains. The same pH range was subsequently screened in Fc aggregation experiments that utilized molecules of IgG1 and IgG2 subclasses with varying levels of CH2 glycosylation. In addition, differential scanning calorimetry data were collected over a pH range of 3–7 to assess changes in CH2 and CH3 thermostability. As a result, compelling evidence was gathered that emphasizes the importance of CH2 stability in determining the rate and extent of Fc aggregation. In particular, we found that Fc domains of the IgG1 subclass have a lower propensity to aggregate compared with those of the IgG2 subclass. Our data for glycosylated, partially deglycosylated, and fully deglycosylated molecules further revealed the criticality of CH2 glycans in modulating Fc aggregation. These findings provide important insights into the stability of Fc-based therapeutics and promote better understanding of their acid-induced aggregation process. PMID:22084250

  7. Lipoteichoic Acid-Induced Nitric Oxide Production Depends on the Activation of Platelet-Activating Factor Receptor and Jak21

    PubMed Central

    Han, Seung Hyun; Kim, Je Hak; Seo, Ho Seong; Martin, Michael H.; Chung, Gook-Hyun; Michalek, Suzanne M.; Nahm, Moon H.

    2006-01-01

    NO production by macrophages in response to lipoteichoic acid (LTA) and a synthetic lipopeptide (Pam3CSK4) was investigated. LTA and Pam3CSK4 induced the production of both TNF-α and NO. Inhibitors of platelet-activating factor receptor (PAFR) blocked LTA- or Pam3CSK4-induced production of NO but not TNF-α. Jak2 tyrosine kinase blocked LTA-induced production of NO but not TNF-α. PAFR inhibition blocked phosphorylation of Jak2 and STAT1, a key factor for expressing inducible NO synthase. In addition, LTA did not induce IFN-β expression, and p38 mitogen-activated protein serine kinase was necessary for LTA-induced NO production but not for TNF-α production. These findings suggest that Gram-positive bacteria induce NO production using a PAFR signaling pathway to activate STAT1 via Jak2. This PAFR/Jak2/STAT1 signaling pathway resembles the IFN-β, type I IFNR/Jak/STAT1 pathway described for LPS. Consequently, Gram-positive and Gram-negative bacteria appear to have different but analogous mechanisms for NO production. PMID:16365452

  8. Inhibition of Platelet Aggregation by the Leaf Extract of Carica papaya During Dengue Infection: An In Vitro Study.

    PubMed

    Chinnappan, Shobia; Ramachandrappa, Vijayakumar Shettikothanuru; Tamilarasu, Kadhiravan; Krishnan, Uma Maheswari; Pillai, Agiesh Kumar Balakrishna; Rajendiran, Soundravally

    2016-04-01

    Dengue cases were reported to undergo platelet activation and thrombocytopenia by a poorly understood mechanism. Recent studies suggested that Carica papaya leaf extract could recover the platelet count in dengue cases. However, no studies have attempted to unravel the mechanism of the plant extract in platelet recovery. Since there are no available drugs to treat dengue and considering the significance of C. papaya in dengue treatment, the current study aimed to evaluate two research questions: First one is to study if the C. papaya leaf extract exerts its action directly on platelets and second one is to understand if the extract can specifically inhibit the platelet aggregation during dengue viral infection. Sixty subjects with dengue positive and 60 healthy subjects were recruited in the study. Platelet-rich plasma (PRP) and platelet-poor plasma were prepared from both the dengue-infected and healthy control blood samples. Effect of the leaf extract obtained from C. papaya leaves was assessed on plasma obtained as well as platelets collected from both healthy and dengue-infected individuals. Platelet aggregation was significantly reduced when leaf extract preincubated with dengue plasma was added into control PRP, whereas no change in aggregation when leaf extract incubated-control plasma was added into control PRP. Upon direct addition of C. papaya leaf extract, both dengue PRP and control PRP showed a significant reduction in platelet aggregation. Within the dengue group, PRP from severe and nonsevere cases showed a significant decrease in aggregation without any difference between them. From the study, it is evident that C. papaya leaf extract can directly act on platelet. The present study, the first of its kind, found that the leaf extract possesses a dengue-specific neutralizing effect on dengue viral-infected plasma that may exert a protective role on platelets.

  9. Inhibition of Platelet Aggregation by the Leaf Extract of Carica papaya During Dengue Infection: An In Vitro Study.

    PubMed

    Chinnappan, Shobia; Ramachandrappa, Vijayakumar Shettikothanuru; Tamilarasu, Kadhiravan; Krishnan, Uma Maheswari; Pillai, Agiesh Kumar Balakrishna; Rajendiran, Soundravally

    2016-04-01

    Dengue cases were reported to undergo platelet activation and thrombocytopenia by a poorly understood mechanism. Recent studies suggested that Carica papaya leaf extract could recover the platelet count in dengue cases. However, no studies have attempted to unravel the mechanism of the plant extract in platelet recovery. Since there are no available drugs to treat dengue and considering the significance of C. papaya in dengue treatment, the current study aimed to evaluate two research questions: First one is to study if the C. papaya leaf extract exerts its action directly on platelets and second one is to understand if the extract can specifically inhibit the platelet aggregation during dengue viral infection. Sixty subjects with dengue positive and 60 healthy subjects were recruited in the study. Platelet-rich plasma (PRP) and platelet-poor plasma were prepared from both the dengue-infected and healthy control blood samples. Effect of the leaf extract obtained from C. papaya leaves was assessed on plasma obtained as well as platelets collected from both healthy and dengue-infected individuals. Platelet aggregation was significantly reduced when leaf extract preincubated with dengue plasma was added into control PRP, whereas no change in aggregation when leaf extract incubated-control plasma was added into control PRP. Upon direct addition of C. papaya leaf extract, both dengue PRP and control PRP showed a significant reduction in platelet aggregation. Within the dengue group, PRP from severe and nonsevere cases showed a significant decrease in aggregation without any difference between them. From the study, it is evident that C. papaya leaf extract can directly act on platelet. The present study, the first of its kind, found that the leaf extract possesses a dengue-specific neutralizing effect on dengue viral-infected plasma that may exert a protective role on platelets. PMID:26910599

  10. Mild and moderate hypothermia increases platelet aggregation induced by various agonists: a whole blood in vitro study.

    PubMed

    Scharbert, G; Kalb, M L; Essmeister, R; Kozek-Langenecker, S A

    2010-01-01

    The mechanisms causing temperature-dependent bleeding, especially in hypothermic patients, warrant clarification. Therefore the aim of this study was to investigate platelet aggregation at the clinically important temperature range of 30-34 degrees C. After obtaining informed consent citrated whole blood was drawn from 12 healthy adult male volunteers, who had not taken any medication in the previous 14 days. After venipuncture blood samples were incubated at 37 degrees C until platelet testing. Platelet aggregation was performed in whole blood using the impedance aggregometer Multiplate at five different test temperatures between 30 degrees C and 34 degrees C. Aggregation responses at 37 degrees C served as controls. At temperatures of mild and moderate hypothermia (30-34 degrees C), overall platelet aggregation was increased compared to 37 degrees C. Increases were recorded in response to collagen, thrombin receptor activating peptide and ristocetin between 31 degrees C and 34 degrees C and in response to adenosine diphosphate between 30 degrees C and 34 degrees C. Overall platelet aggregation is increased at mild and moderate hypothermia down to 30 degrees C. These results indicate that bleeding complications reported in mildly hypothermic patients are not due to hypothermia-induced platelet inhibition. The pathomechanism of the overall increased platelet aggregation between 30 degrees C and 34 degrees C requires further detailed study. PMID:19954411

  11. Dietary calcium attenuates platelet aggregation and intracellular Ca2+ mobilization in spontaneously hypertensive rats

    NASA Technical Reports Server (NTRS)

    Otsuka, K.; Watanabe, M.; Yue, Q.; McCarron, D. A.; Hatton, D.

    1997-01-01

    Spontaneously hypertensive rats (SHR) are known to be blood pressure sensitive to dietary calcium. The effects of dietary calcium on platelet aggregation and intracellular Ca2+ mobilization were assessed by turbidimetric methods and fura-2 methods, respectively, in washed platelets of SHR. Ca2+ ATPase activity was examined in aortic membrane fractions. Six weeks of dietary calcium supplementation attenuated the increase of systolic blood pressure (SBP 199 +/- 16 v 170 +/- 9 mm Hg, P < .001) and thrombin-induced platelet aggregation (84.5 +/- 3.7 v 73.7 +/- 7.4%, P < .004) at 9 weeks of age. The ionomycin-induced intracellular calcium ([Ca2+]i) peak in the absence of external Ca2+, which reflects [Ca2+]i storage size, and thrombin-evoked [Ca2+]i release from [Ca2+]i storage were decreased by 2.0% Ca diet (472 +/- 55 v 370 +/- 23 nmol/L, P < .001, 339 +/- 29 v 278 +/- 33 nmol/L, P < .002). In addition, SBP was positively correlated with platelet aggregation (r = 0.703, P = .0088), thrombin-evoked [Ca2+]i (r = 0.739, P = .0044), and ionomycin-induced [Ca2+]i (r = 0.591, P = .0415), respectively. However, there was no significant effect of dietary calcium on Ca2+-ATPase activity in aortic membranes. These results suggest that dietary calcium supplementation had a beneficial effect on platelets of SHR by attenuating [Ca2+]i mobilization from [Ca2+]i storage. The hypotensive effect of dietary calcium might be associated with attenuated [Ca2+]i mobilization in SHR.

  12. Upright posture and maximal exercise increase platelet aggregability and prostacyclin production in healthy male subjects

    PubMed Central

    Feng, D. L.; Murillo, J.; Jadhav, P.; McKenna, C.; Gebara, O. C.; Lipinska, I.; Muller, J. E.; Tofler, G. H.

    1999-01-01

    BACKGROUND: It is well accepted that heavy physical exertion can trigger the onset of myocardial infarction, but the mechanism is uncertain. As platelet and endothelial function play an important role in thrombotic events, platelet and prostacyclin responses to maximal treadmill exercise were studied. METHODS/RESULTS: The study subjects were 40 healthy men, mean (SEM) age 29 (5) years. Platelet aggregation was measured on a four channel aggregometer. Plasma 6-keto- prostaglandin F1alpha was analysed using an enzyme immunoassay technique. Upright posture and exercise produced an increase in platelet aggregability, as indicated by a fall in the threshold concentration of adrenaline (epinephrine) from 7.6 (1.5) microM at rest to 4.3 (1.0) microM after exercise (p = 0.002). The collagen lag time became significantly shorter with exercise (from 79.1 (3.1) seconds at rest to 71.9 (2.6) seconds after exercise, p = 0.003). Exercise was also associated with a 55% increase in plasma 6-keto-prostaglandin F1alpha (from 38.1 (75%CI 29.0 to 46.5) pg/ml at rest to 59.2 (47.3 to 66.8) pg/ml after exercise, p<0.001). CONCLUSIONS: In healthy male subjects, upright posture and maximal exercise increased platelet aggregability but this increase was counteracted by an increase in prostacyclin production. In patients with endothelial dysfunction, a reduced prostacyclin response to exercise may promote a transient prothrombotic imbalance that may trigger cardiovascular disease onset. 


 PMID:10597849

  13. The influence of Rubus idaeus and Rubus caesius leaf extracts on platelet aggregation in whole blood. Cross-talk of platelets and neutrophils.

    PubMed

    Dudzinska, Dominika; Bednarska, Katarzyna; Boncler, Magdalena; Luzak, Boguslawa; Watala, Cezary

    2016-07-01

    Recently, polyphenols have gained attention as potential natural cardioprotective therapeutics, due to their antiplatelet, anti-inflammatory and anticoagulant activity. Species belonging to the genus Rubus sp. have been reported to be a source of polyphenolic compounds with antioxidative proprieties and beneficial biological activities. This study investigates the effects of leaf extracts obtained from red raspberry (Rubus idaeus L.) and European dewberry (Rubus caesius L.) on the reactivity of blood platelets. In ADP-stimulated blood, raspberry and dewberry extracts (15 µg/ml) markedly decreased platelet surface membrane expression of activated GPIIbIIIa receptor by 16% and 21%, respectively (P < 0.01) and significantly inhibited platelet aggregation (by 31-41% for raspberry and by 38-55% for dewberry, P < 0.01). In platelet-rich plasma (PRP), the extracts had no effect on ADP-induced platelet aggregation. The effectiveness of the extracts in whole blood and the lack of their activity in PRP indicate that leukocytes are likely to participate in the platelet response to the extracts. Our experiments show that the extracts significantly reduced the amount of free radicals released by activated neutrophils in whole blood (P < 0.001), as well as in suspensions of isolated neutrophils (P < 0.05). Moreover, the reduced number of neutrophils leads to the decreased efficiency of the extracts in the inhibition of platelet aggregation. In summary, our findings show that the raspberry and dewberry leaf extracts considerably modulated blood platelet reactivity in whole blood: they influenced blood platelet aggregation, possibly via the modulation of the redox status dependent on the oxidative activity of neutrophils.

  14. The influence of Rubus idaeus and Rubus caesius leaf extracts on platelet aggregation in whole blood. Cross-talk of platelets and neutrophils.

    PubMed

    Dudzinska, Dominika; Bednarska, Katarzyna; Boncler, Magdalena; Luzak, Boguslawa; Watala, Cezary

    2016-07-01

    Recently, polyphenols have gained attention as potential natural cardioprotective therapeutics, due to their antiplatelet, anti-inflammatory and anticoagulant activity. Species belonging to the genus Rubus sp. have been reported to be a source of polyphenolic compounds with antioxidative proprieties and beneficial biological activities. This study investigates the effects of leaf extracts obtained from red raspberry (Rubus idaeus L.) and European dewberry (Rubus caesius L.) on the reactivity of blood platelets. In ADP-stimulated blood, raspberry and dewberry extracts (15 µg/ml) markedly decreased platelet surface membrane expression of activated GPIIbIIIa receptor by 16% and 21%, respectively (P < 0.01) and significantly inhibited platelet aggregation (by 31-41% for raspberry and by 38-55% for dewberry, P < 0.01). In platelet-rich plasma (PRP), the extracts had no effect on ADP-induced platelet aggregation. The effectiveness of the extracts in whole blood and the lack of their activity in PRP indicate that leukocytes are likely to participate in the platelet response to the extracts. Our experiments show that the extracts significantly reduced the amount of free radicals released by activated neutrophils in whole blood (P < 0.001), as well as in suspensions of isolated neutrophils (P < 0.05). Moreover, the reduced number of neutrophils leads to the decreased efficiency of the extracts in the inhibition of platelet aggregation. In summary, our findings show that the raspberry and dewberry leaf extracts considerably modulated blood platelet reactivity in whole blood: they influenced blood platelet aggregation, possibly via the modulation of the redox status dependent on the oxidative activity of neutrophils. PMID:26836594

  15. Obstruction of the lung capillaries by blood platelet aggregates and leucocytes in sudden infant death syndrome.

    PubMed

    Hanssen, Tor-Arne; Jørgensen, Leif

    2010-12-01

    Altogether 34 cases of sudden infant death were studied postmortem with particular emphasis on the pathological changes in the lungs. Light microscopy, including application of immunohistochemical methods, and transmission electron microscopy were used for the identification of blood platelets and white blood cell types in alveolar capillaries. The main findings were platelet aggregates and a varying number of neutrophil polymorphonuclear granulocytes in the lung capillaries, mixed with a smaller number of lymphocytes. The findings may be interpreted as an early sign of inflammation with capillary thrombosis, resulting in ischaemia, i.e. arrest of flow. In 21% of the cases, inflammatory cells had also expanded focally into alveolar spaces, creating the picture of localized areas of bronchopneumonia. An infant dying suddenly of a traumatic head injury served as a control. Neither platelets nor leucocytes were observed in the alveolar capillaries of this infant. In conclusion, in lungs from cases of sudden infant death syndrome, the alveolar capillaries are obstructed by platelet aggregates and leucocytes, interpreted as signs of an initial stage of lung inflammation with ischaemia. PMID:21091777

  16. Glyoxylate lowers metabolic ATP in human platelets without altering adenylate energy charge or aggregation.

    PubMed

    Dangelmaier, Carol A; Holmsen, Holm

    2014-01-01

    Human blood platelets adhere to exposed collagen at the site of vascular injury, initiating a signaling cascade leading to fibrinogen activation, secretion of granules and aggregation, thus producing a stable thrombus. All these steps require metabolic ATP. In this study we have labeled the metabolic pool of ATP with nucleotides, treated platelets with various inhibitors and have monitored their ability to be activated. Incubating platelets with glyoxylate dramatically reduced the ATP level without a change in the adenylate energy charge (AEC). This reduction of ATP did not affect ADP-induced primary or secondary aggregation, whereas glyoxal, methyl glyoxal, or the combination of antimycin plus deoxyglucose reduced both ATP and AEC and inhibited aggregation. The reduction of ATP by glyoxylate was almost quantitatively matched by an increase in hypoxanthine without elevation of ADP. AMP, IMP or inosine, acetoacetate, aspartate, or glutamate had no effect on glyoxylate-induced breakdown of ATP, while pyruvate stopped the ATP reduction fast and efficiently. Glyoxylate also lowered the citrate content. The glyoxylate-induced breakdown of ATP coincided with an increase in fructose-1,6-bisphosphate, indicating that the phosphofructokinase reaction was the main ATP-consuming step. Glyoxylate was a substrate for lactate dehydrogenase although with a Km almost 100 times higher than pyruvate. We suggest that glyoxylate primarily competes with pyruvate in the pyruvate dehydrogenase reaction, thus lowering the citrate concentration, which in turn activates phosphofructokinase. Clearly, lowering of ATP in the cytosol by more than 50% does not affect platelet aggregation provided that the AEC is not reduced.

  17. The Constituents of Roots and Stems of Illigera luzonensis and Their Anti-Platelet Aggregation Effects

    PubMed Central

    Huang, Chieh-Hung; Chan, Yu-Yi; Kuo, Ping-Chung; Chen, Yu-Fon; Chang, Ren-Jie; Chen, Ih-Sheng; Wu, Shwu-Jen; Wu, Tian-Shung

    2014-01-01

    Phytochemical investigation of the roots and stems of Illigera luzonensis afforded two new aporphine alkaloids (1) and (2), one new bisdehydroaporphine alkaloid (3), and one new benzenoid (4), along with 28 known structures. The structures of new compounds were elucidated by spectral and MS analysis. Among the isolated compounds, (1) and (4–13) were subjected into the examination for their inhibitory effects on the aggregation of washed rabbit platelets. PMID:25089876

  18. Bis-spirolabdane diterpenoids from Leonurus japonicus and their anti-platelet aggregative activity.

    PubMed

    Xiong, Liang; Zhou, Qin-Mei; Peng, Cheng; Xie, Xiao-Fang; Liu, Lu-Si; Guo, Li; He, Ya-Cong; Yang, Lian; Liu, Zhao-Hua

    2015-01-01

    Six bis-spirolabdane diterpenoids along with four known analogues were isolated from the aerial parts of Leonurus japonicus. Their structures and absolute configurations were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, and a modified Mosher's method. The inhibitory activity of the compounds against the abnormal increase in platelet aggregation induced by adenosine diphosphate was investigated. Only the (13R)-bis-spirolabdane diterpenoids exhibited a significant effect.

  19. Luminal platelet aggregates in functional deficits in parenchymal vessels after subarachnoid hemorrhage

    PubMed Central

    Friedrich, Victor; Flores, Rowena; Muller, Artur; Sehba, Fatima A.

    2010-01-01

    The pathophysiology of early ischemic injury after aneurysmal subarachnoid hemorrhage (SAH) is not understood. This study examined the acute effect of endovascular puncture-induced SAH on parenchymal vessel function in rat, using intravascular fluorescent tracers to assess flow and vascular permeability and immunostaining to assess structural integrity and to visualize platelet aggregates. In sham-operated animals, vessels were well filled with tracer administered 10 seconds before sacrifice, and parenchymal escape of tracer was rare. At ten minutes and 3 hours after hemorrhage, patches of poor vascular filling were distributed throughout the forebrain. Close examination of these regions revealed short segments of narrowed diameter along many profiles. Most vascular profiles with reduced perfusion contained platelet aggregates and in addition showed focal loss of collagen IV, a principal component of basal lamina. In contrast, vessels were well filled at 24 hours post-hemorrhage, indicating that vascular perfusion had recovered. Parenchymal escape of intravascular tracer was detected at 10 minutes post-hemorrhage and later as plumes of fluorescence emanating into parenchyma from restricted microvascular foci. These data demonstrate that parenchymal microvessels are compromised in function by 10 minutes after SAH and identify focal microvascular constriction and local accumulation of luminal platelet aggregates as potential initiators of that compromise. PMID:20654597

  20. Orally given gastroprotective capsaicin does not modify aspirin-induced platelet aggregation in healthy male volunteers (human phase I examination).

    PubMed

    Sandor, B; Papp, J; Mozsik, Gy; Szolcsanyi, J; Keszthelyi, Zs; Juricskay, I; Toth, K; Habon, Tamas

    2014-12-01

    Capsaicin is a well-known component of red pepper. Recent studies have shown that capsaicin could prevent gastric ulcer provoked by various NSAID-s like acetylsalicylic acid (ASA). Primary objective of this human clinical phase I trial was to investigate whether two different doses of capsaicin co-administered with ASA could alter the inhibitory effect of ASA on platelet aggregation. 15 healthy male subjects were involved in the study and treated orally with 400 μg capsaicin, 800 μg capsaicin, 500 mg ASA, 400 μg capsaicin+500 mg ASA and 800 μg capsaicin+500 mg ASA. Blood was drawn before and 1, 2, 6 and 24 hours after the drug administration. After that epinephrine induced platelet aggregation was measured by optical aggregometry. Between treatments, volunteers had a 6-day wash-out period. Our results showed that capsaicin had no effect on platelet aggregation, while as expected, ASA monotherapy resulted in a significant and clinically effective platelet aggregation inhibition (p ≤ 0.001). The combined ASA-capsaicin therapies reached equivalent effectiveness in platelet aggregation inhibition as ASA monotherapy. Our investigation proved that capsaicin did not influence the inhibitory effect of ASA on platelet aggregation, thus the capsaicin-ASA treatment would combine the antiplatelet effect of ASA with the possible gastroprotection of capsaicin.

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

    PubMed

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

    2014-07-01

    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.

  2. Treatment of experimental furcation perforations with mineral trioxide aggregate, platelet rich plasma or platelet rich fibrin in dogs' teeth.

    PubMed

    Tawfik, Hosam E; Abu-Seida, Ashraf M; Hashem, Ahmed A; El-Khawlani, Mohammed M

    2016-06-01

    This work evaluates the effect of mineral trioxide aggregate (MTA), platelet rich plasma (PRP) or platelet rich fibrin (PRF) on healing of non-contaminated and contaminated furcation perforations. A total of 192 teeth of 12 dogs was divided into three equal groups according to evaluation period. Each group was further subdivided into MTA, PRP, PRF, negative and positive control subgroups. Each experimental subgroup was further subdivided according to perforation status into non-contaminated and contaminated subdivisions. Root canal therapy was carried out and furcation perforation was made in all teeth except in negative control subgroup. The furcation perforation was repaired immediately in subdivision (1) and after 4 weeks in subdivision (2). The change in vertical bone loss was measured by radiography. Inflammatory cell count, cemental deposition, new bone formation, bone resorption and epithelial proliferation were assessed. Both PRP and PRF demonstrated statistically significant reduction in vertical bone loss and inflammatory cell count than MTA. No significant difference was found between MTA, PRP and PRF in cemental deposition, new bone formation, bone resorption and epithelial proliferation. The non-contaminated teeth demonstrated better treatment outcomes than the contaminated teeth. In conclusion, PRP and PRF are successful treatment options for repairing of furcation perforation in both non-contaminated and contaminated teeth in dogs with superior outcomes in non contaminated teeth. PMID:27033179

  3. Treatment of experimental furcation perforations with mineral trioxide aggregate, platelet rich plasma or platelet rich fibrin in dogs' teeth.

    PubMed

    Tawfik, Hosam E; Abu-Seida, Ashraf M; Hashem, Ahmed A; El-Khawlani, Mohammed M

    2016-06-01

    This work evaluates the effect of mineral trioxide aggregate (MTA), platelet rich plasma (PRP) or platelet rich fibrin (PRF) on healing of non-contaminated and contaminated furcation perforations. A total of 192 teeth of 12 dogs was divided into three equal groups according to evaluation period. Each group was further subdivided into MTA, PRP, PRF, negative and positive control subgroups. Each experimental subgroup was further subdivided according to perforation status into non-contaminated and contaminated subdivisions. Root canal therapy was carried out and furcation perforation was made in all teeth except in negative control subgroup. The furcation perforation was repaired immediately in subdivision (1) and after 4 weeks in subdivision (2). The change in vertical bone loss was measured by radiography. Inflammatory cell count, cemental deposition, new bone formation, bone resorption and epithelial proliferation were assessed. Both PRP and PRF demonstrated statistically significant reduction in vertical bone loss and inflammatory cell count than MTA. No significant difference was found between MTA, PRP and PRF in cemental deposition, new bone formation, bone resorption and epithelial proliferation. The non-contaminated teeth demonstrated better treatment outcomes than the contaminated teeth. In conclusion, PRP and PRF are successful treatment options for repairing of furcation perforation in both non-contaminated and contaminated teeth in dogs with superior outcomes in non contaminated teeth.

  4. Identification of a novel platelet antagonist that binds to CLEC-2 and suppresses podoplanin-induced platelet aggregation and cancer metastasis.

    PubMed

    Chang, Yao-Wen; Hsieh, Pei-Wen; Chang, Yu-Tsui; Lu, Meng-Hong; Huang, Tur-Fu; Chong, Kowit-Yu; Liao, Hsiang-Ruei; Cheng, Ju-Chien; Tseng, Ching-Ping

    2015-12-15

    Podoplanin (PDPN) enhances tumor metastases by eliciting tumor cell-induced platelet aggregation (TCIPA) through activation of platelet C-type lectin-like receptor 2 (CLEC-2). A novel and non-cytotoxic 5-nitrobenzoate compound 2CP was synthesized that specifically inhibited the PDPN/CLEC-2 interaction and TCIPA with no effect on platelet aggregation stimulated by other platelet agonists. 2CP possessed anti-cancer metastatic activity in vivo and augmented the therapeutic efficacy of cisplatin in the experimental animal model without causing a bleeding risk. Analysis of the molecular action of 2CP further revealed that Akt1/PDK1 and PKCμ were two alternative CLEC-2 signaling pathways mediating PDPN-induced platelet activation. 2CP directly bound to CLEC-2 and, by competing with the same binding pocket of PDPN in CLEC-2, inhibited PDPN-mediated platelet activation. This study provides evidence that 2CP is the first defined platelet antagonist with CLEC-2 binding activity. The augmentation in the therapeutic efficacy of cisplatin by 2CP suggests that a combination of a chemotherapeutic agent and a drug with anti-TCIPA activity such as 2CP may prove clinically effective. PMID:26528756

  5. Identification of a novel platelet antagonist that binds to CLEC-2 and suppresses podoplanin-induced platelet aggregation and cancer metastasis

    PubMed Central

    Chang, Yu-Tsui; Lu, Meng-Hong; Huang, Tur-Fu; Chong, Kowit-Yu; Liao, Hsiang-Ruei; Cheng, Ju-Chien; Tseng, Ching-Ping

    2015-01-01

    Podoplanin (PDPN) enhances tumor metastases by eliciting tumor cell-induced platelet aggregation (TCIPA) through activation of platelet C-type lectin-like receptor 2 (CLEC-2). A novel and non-cytotoxic 5-nitrobenzoate compound 2CP was synthesized that specifically inhibited the PDPN/CLEC-2 interaction and TCIPA with no effect on platelet aggregation stimulated by other platelet agonists. 2CP possessed anti-cancer metastatic activity in vivo and augmented the therapeutic efficacy of cisplatin in the experimental animal model without causing a bleeding risk. Analysis of the molecular action of 2CP further revealed that Akt1/PDK1 and PKCμ were two alternative CLEC-2 signaling pathways mediating PDPN-induced platelet activation. 2CP directly bound to CLEC-2 and, by competing with the same binding pocket of PDPN in CLEC-2, inhibited PDPN-mediated platelet activation. This study provides evidence that 2CP is the first defined platelet antagonist with CLEC-2 binding activity. The augmentation in the therapeutic efficacy of cisplatin by 2CP suggests that a combination of a chemotherapeutic agent and a drug with anti-TCIPA activity such as 2CP may prove clinically effective. PMID:26528756

  6. Dermcidin isoform-2 induced nullification of the effect of acetyl salicylic acid in platelet aggregation in acute myocardial infarction.

    PubMed

    Bank, Sarbashri; Jana, Pradipta; Maiti, Smarajit; Guha, Santanu; Sinha, A K

    2014-07-24

    The aggregation of platelets on the plaque rupture site on the coronary artery is reported to cause both acute coronary syndromes (ACS) and acute myocardial infarction (AMI). While the inhibition of platelet aggregation by acetyl salicylic acid was reported to produce beneficial effects in ACS, it failed to do in AMI. The concentration of a stress induced protein (dermcidin isoform-2) was much higher in AMI than that in ACS. Incubation of normal platelet rich plasma (PRP) with dermcidin showed one high affinity (Kd = 40 nM) and one low affinity binding sites (Kd = 333 nM). When normal PRP was incubated with 0.4 μM dermcidin, the platelets became resistant to the inhibitory effect of aspirin similar to that in the case of AMI. Incubation of PRP from AMI with dermcidin antibody restored the sensitivity of the platelets to the aspirin effect. Incubation of AMI PRP pretreated with 15 μM aspirin, a stimulator of the NO synthesis, resulted in the increased production of NO in the platelets that removed the bound dermcidin by 40% from the high affinity binding sites of AMI platelets. When the same AMI PRP was retreated with 10 μM aspirin, the aggregation of platelets was completely inhibited by NO synthesis.

  7. The use of quartz crystal microbalance with dissipation (QCM-D) for studying nanoparticle-induced platelet aggregation

    PubMed Central

    Santos-Martinez, Maria Jose; Inkielewicz-Stepniak, Iwona; Medina, Carlos; Rahme, Kamil; D’Arcy, Deirdre M; Fox, Daniel; Holmes, Justin D; Zhang, Hongzhou; Radomski, Marek Witold

    2012-01-01

    Interactions between blood platelets and nanoparticles have both pharmacological and toxicological significance and may lead to platelet activation and aggregation. Platelet aggregation is usually studied using light aggregometer that neither mimics the conditions found in human microvasculature nor detects microaggregates. A new method for the measurement of platelet microaggregation under flow conditions using a commercially available quartz crystal microbalance with dissipation (QCM-D) has recently been developed. The aim of the current study was to investigate if QCM-D could be used for the measurement of nanoparticle-platelet interactions. Silica, polystyrene, and gold nanoparticles were tested. The interactions were also studied using light aggregometry and flow cytometry, which measured surface abundance of platelet receptors. Platelet activation was imaged using phase contrast and scanning helium ion microscopy. QCM-D was able to measure nanoparticle-induced platelet microaggregation for all nanoparticles tested at concentrations that were undetectable by light aggregometry and flow cytometry. Microaggregates were measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast and scanning helium ion microscopy. PMID:22275839

  8. Red Wine Inhibits Aggregation and Increases ATP-diphosphohydrolase (CD39) Activity of Rat Platelets in Vitro.

    PubMed

    Caiazzo, Elisabetta; Tedesco, Idolo; Spagnuolo, Carmela; Russo, Gian Luigi; Ialenti, Armando; Cicala, Carla

    2016-06-01

    Moderate consumption of red wine has been shown to exert a peculiar cardioprotective effect compared with other alcoholic beverages; inhibition of platelet aggregation seems to be one of the mechanisms underlying this beneficial effect. CD39/ATP-diphosphohydrolase is an integral membrane glycoprotein metabolizing ATP and ADP to AMP; in concert with CD73/ecto-5'-nucleotidase, it contributes to extracellular adenosine accumulation. CD39 is considered a key modulator of thrombus formation; it inhibits platelet aggregation by promoting ADP hydrolysis. There is evidence that red wine consumption increases CD39 activity in platelets from streptozotocin-induced diabetic rats. Here we show that two kinds of Aglianico red wines inhibit aggregation and increase ATP--and ADPase activity in rat platelets. PMID:27534113

  9. The effects of 7.5% NaCl/6% dextran 70 on coagulation and platelet aggregation in humans

    NASA Technical Reports Server (NTRS)

    Hess, J. R.; Dubick, M. A.; Summary, J. J.; Bangal, N. R.; Wade, C. E.

    1992-01-01

    The combination solution of 7.5% NaCl/6% dextran 70 (HSD) administered IV gives hemodynamic improvement in the treatment of hemorrhagic hypotension. Since earlier dextran solutions were reported to interfere with blood coagulation, the effects of HSD on the prothrombin time (PT), the activated partial thromboplastin time (APTT), platelet aggregation, and platelet concentration were studied. The HSD mixed with human plasma (1:5 and 1:10) slightly prolonged PT, but had no effect on the APTT, compared with saline controls. The HSD also decreased human platelet aggregation at the 1:5 dilution. In separate mixing studies, the hypertonic saline component of HSD was associated with the prolongation of PT and decreased platelet aggregation. The data from these studies indicate that at its proposed therapeutic dose, HSD is expected to have minimal effect on blood coagulation.

  10. Effects of extracts and tannins from Arbutus unedo leaves on rat platelet aggregation.

    PubMed

    Mekhfi, Hassane; ElHaouari, Mohammed; Bnouham, Mohamed; Aziz, Mohammed; Ziyyat, Abderrahim; Legssyer, Abdelkhaleq

    2006-02-01

    Many cardiovascular diseases such as arterial hypertension are associated with an increase in blood platelet activity. Arbutus unedo (Ericaceae) is a medicinal plant reputed to treat arterial hypertension, so the present study was undertaken in order to determine the antiaggregant effect. The crude aqueous extract showed an inhibition of thrombin-induced platelet aggregation (IC50 = 1.8 +/- 0.09 g/L, n = 10). The subsequent extraction of Arbutus unedo leaves by successive solvents showed that the methanol and ethyl acetate extracts accounted for most of the antiaggregant activity (IC50 = 0.7 +/- 0.08, n = 9; 0.6 +/- 0.05; n = 9, respectively). The tannins isolated from the methanol extract exhibited a strong antiplatelet effect (% of inhibition = 75.3 +/- 1.4, n = 8) and may be the major chemical compounds responsible for this action. Our results support the traditional use of this plant in the preventive or therapeutic treatment of platelet aggregation linked to arterial hypertension. PMID:16444667

  11. Elucidation of flow-mediated tumour cell-induced platelet aggregation using an ultrasound standing wave trap

    PubMed Central

    Bazou, D; Santos-Martinez, MJ; Medina, C; Radomski, MW

    2011-01-01

    BACKGROUND AND PURPOSE Tumour cells activate and aggregate platelets [tumour cell-induced platelet aggregation (TCIPA)] and this process plays an important role in the successful metastasis of cancer cells. To date, most studies on TCIPA have been conducted under no-flow conditions. In this study, we have investigated TCIPA in real time under flow conditions, using an ultrasound standing wave trap that allows formation and levitation of cancer cell clusters in suspension, thus mimicking the conditions generated by flowing blood. EXPERIMENTAL APPROACH Using 59M adenocarcinoma and HT1080 fibrosarcoma cells and human platelets, cancer cell cluster–platelet aggregates were imaged in real time using epi-fluorescence microscopy (F-actin) and investigated in detail using confocal microscopy (matrix metalloproteinase-2-GPIIb/IIIa co-localization) and scanning electron and helium-ion microscopy (<1 nm resolution). The release of gelatinases from aggregates was studied using zymography. KEY RESULTS We found that platelet activation and aggregation takes place on the surface of cancer cells (TCIPA), leading to time-dependent disruption of cancer cell clusters. Pharmacological modulation of TCIPA revealed that EDTA, prostacyclin, o-phenanthroline and apyrase significantly down-regulated TCIPA and, in turn, delayed cell cluster disruption, However, EGTA and aspirin were ineffective. Pharmacological inhibition of TCIPA correlated with the down-regulation of platelet activation as shown by flow-cytometry assay of platelet P-selectin. CONCLUSION AND IMPLICATIONS Our results show for the first time, that during TCIPA, platelet activation disrupts cancer cell clusters and this can contribute to metastasis. Thus, selective targeting of platelet aggregate–cancer cell clusters may be an important strategy to control metastasis. PMID:21182493

  12. Effects of oral contraceptives, or lanosterol, on ADP-induced aggregation and binding of /sup 125/I-fibrinogen to rat platelets

    SciTech Connect

    McGregor, L.; Toor, B.; McGregor, J.L.; Renaud, S.; Clemetson, K.J.

    1984-03-01

    The aggregation to ADP and the binding of /sup 125/I-fibrinogen to platelets from rats treated with oral contraceptives or normal platelets treated in vitro with lanosterol were compared to their respective controls. Both types of platelets showed a significant increase in ADP-induced aggregation and in binding of fibrinogen, indicating that the effect of oral contraceptives could be partly due to increased levels of lanosterol in platelet membrane.

  13. Effects of tetrandrine and fangchinoline on experimental thrombosis in mice and human platelet aggregation.

    PubMed

    Kim, H S; Zhang, Y H; Yun, Y P

    1999-03-01

    Tetrandrine (TET) and fangchinoline (FAN) are two naturally occurring analogues with a bisbenzylisoquinoline structure. The present study was undertaken to investigate the effects of TET and FAN on the experimental thrombosis induced by collagen plus epinephrine (EP) in mice, and platelet aggregation and blood coagulation in vitro. In the in vivo study, the administration (50 mg/kg, i.p.) of TET and FAN in mice showed the inhibition of thrombosis by 55% and 35%, respectively, while acetylsalicylic acid (ASA, 50 mg/kg, i.p.), a positive control, showed only 30% inhibition. In the vitro human platelet aggregations induced by the agonists used in tests, TET and FAN showed the inhibitions dose dependently. In addition, neither TET nor FAN showed any anticoagulation activities in the measurement of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using human-citrated plasma. These results suggest that antithrombosis of TET and FAN in mice may be mainly related to the antiplatelet aggregation activities. PMID:10193204

  14. Serotonin-induced platelet aggregation predicts the antihypertensive response to serotonin receptor antagonists.

    PubMed

    Gleerup, G; Persson, B; Hedner, T; Winther, K

    1993-01-01

    The 5-HT2-receptor antagonist ketanserin (20-40 mg b.i.d.) was administered to 62 patients of both sexes with uncomplicated primary hypertension. After 4 weeks of treatment about 50% of the patients had reached the target diastolic blood pressure of 90 mm Hg or below. Interindividual variability was large. In a retrospective analysis the variability could not be explained by sex or the dose of ketanserin. There was a weak association between age and systolic blood pressure response (r = 0.24; P = 0.06), which could be entirely accounted for by the higher base line blood pressure in the elderly patients. In one group of patients (n = 12), the ex vivo aggregation to serotonin (10(-6) M) was studied during treatment with placebo and ketanserin. Ketanserin completely inhibited 5-HT-induced aggregation in all patients. There was a close correlation between the area under the 5-HT-induced platelet aggregation curve during placebo and the subsequent reduction in diastolic blood pressure after 4 weeks of treatment with ketanserin. The present data suggest that the blood pressure response to ketanserin can be predicted from the ex vivo sensitivity of platelets to serotonin. By implication, they also support a role for serotonergic mechanisms in hypertension.

  15. Anti-CD31 delays platelet adhesion/aggregation at sites of endothelial injury in mouse cerebral arterioles.

    PubMed

    Rosenblum, W I; Murata, S; Nelson, G H; Werner, P K; Ranken, R; Harmon, R C

    1994-07-01

    The arterioles on the surface of the mouse brain (pial arterioles) were observed by in vivo microscopy. A focus of minor endothelial damage was produced in a single pial arteriole in each mouse by briefly exposing the site to a helium neon laser after an intravenous injection of Evans blue. Mice were injected 10 minutes before injury with a monoclonal antibody (MAb) to mouse CD31, also known as platelet endothelial cell adhesion molecule. This treatment doubled (P < .01) the time required for the laser to produce a recognizable platelet aggregate. In additional experiments, an MAb to mouse CD61 and an MAb to mouse intercellular adhesion molecule 1 had no effect. The data support previous observations indicating that platelet adhesion/aggregation in this model is induced by endothelial injury without exposure of basal lamina. The data are consistent with the hypothesis that the endothelial injury exposes or activates a platelet endothelial cell adhesion molecule on the endothelium which is blocked by the MAb directed against CD31. This may be the first demonstration of an effect of an anti-platelet endothelial cell adhesion molecule on platelet endothelial cell adhesion molecule on platelet adhesion/aggregation in vivo. PMID:8030753

  16. The impaired synthesis of insulin and its inability to inhibit platelet aggregation in cerebrovascular accident.

    PubMed

    Bank, Sarbashri; Bhattacharya, Suman; Maiti, Smarajit; Bhattacharya, Raja; Chakraborty, Debajyoti; Sinha, Asru K

    2015-10-01

    Both ischemic stroke (IS) and hemorrhagic stroke (HS) are reported to occur due to thrombosis on the arteries of the brain. As diabetes mellitus is a risk factor for strokes and insulin is reported to prevent thrombosis, the role of insulin in IS and HS was investigated. Forty eight stroke victims (IS = 22, HS = 26) and equal number of aged and sex matched normal volunteers participated in the study. Nitric oxide was determined by methemoglobin method. Insulin and Dermcidin isoform-2 (DCN2) level was determined by ELISA by using insulin and dermcidin antibody. Insulin binding to the platelet membrane was analyzed by scat chard plot. Treatment of normal platelet rich plasma (10(8)platelets/ml) with 15μUnits insulin/ml produced 1.41 nmol NO. The PRP from the IS and HS victims produced 0.38 nmol NO and 0.08 nmol NO respectively. Pretreatment of PRP from IS or HS subjects with 15 μM aspirin followed by 15μUnits of insulin/ml resensitized the platelets to the inhibitory effect of insulin. Mice hepatocytes treated with 0.14 μM DCN2 abolished the glucose induced insulin synthesis by NO that can be reversed by using 15 μM aspirin. It can be concluded that presence of DCN2 in stroke causes a condition similar to type I diabetes and nullified the effect of insulin in the inhibition of platelet aggregation in both IS and HS. The effect was reversed by 15 μM aspirin.

  17. Staphylococcal enterotoxin B initiates protein kinase C translocation and eicosanoid metabolism while inhibiting thrombin-induced aggregation in human platelets.

    PubMed

    Tran, Uyen; Boyle, Thomas; Shupp, Jeffrey W; Hammamieh, Rasha; Jett, Marti

    2006-08-01

    Staphylococcal enterotoxin (SE) B, a heat-stable toxin secreted by Staphylococcus aureus, has been implicated in the pathogenesis and exacerbation of several critical illnesses. It has been hypothesized that enterotoxins may interact with blood products such as platelets, in addition to T-lymphocytes and renal proximal tubule cells. The aim of this present study was to elucidate whether SEB directly alters human platelet function. Human platelet rich plasma (PRP) was pre-incubated with SEA, SEB, SEC or TSST-1, (at various concentrations and incubation times). After incubation, PRP was exposed to thrombin and aggregation was assessed. Incubation with all toxins tested resulted in decreased aggregation, specifically; exposure to 10mu g/ml of SEB for 30 min caused a 20% decrease and a 49% decrease at 90 min. A similar reduction in aggregation was seen in samples incubated with phorbol myristate acetate, a known stimulator of protein kinase C (PKC). Further, platelets exposed to SEB exhibited an increased plasma membrane PKC activity. Sphingosine, an inhibitor of PKC proved to block the SEB-induced reduction in aggregation. SEB effects on platelet metabolism were investigated using high performance liquid chromatography showing up to a 2-fold increase of active metabolites lipoxin A4 and 12-HETE, as compared to control. These data indicate that SEB is able to induce platelet dysfunction, and these effects may be mediated through activation of PKC.

  18. Differential inhibition of tumour cell-induced platelet aggregation by the nicotinate aspirin prodrug (ST0702) and aspirin

    PubMed Central

    Medina, Carlos; Harmon, Shona; Inkielewicz, Iwona; Santos-Martinez, Maria Jose; Jones, Michael; Cantwell, Paula; Bazou, Despina; Ledwidge, Mark; Radomski, Marek W; Gilmer, John F

    2012-01-01

    BACKGROUND AND PURPOSE Tumour cell-induced platelet aggregation (TCIPA) facilitates cancer cell invasion, angiogenesis and the formation of metastatic foci. TCIPA can be modulated by pharmacological inhibitors of MMP-2 and ADP; however, the COX inhibitor aspirin did not prevent TCIPA. In this study, we have tested the pharmacological effects of a new group of isosorbide-based aspirin prodrugs on TCIPA. EXPERIMENTAL APPROACH TCIPA was induced in human platelets by mixing with human adenocarcinoma or fibrosarcoma cells under no flow and flow conditions. The release of gelatinases and P-selectin expression during TCIPA were studied by zymography and flow cytometry respectively. KEY RESULTS Tumour cells caused platelet aggregation. This aggregation resulted in the release of MMP-2 and a significant up-regulation of P-selectin on platelets, indicative of platelet activation. Pharmacological modulation of TCIPA revealed that ST0702, one of the aspirin prodrugs, down-regulated TCIPA while aspirin was ineffective. The deacetylated metabolite of ST0702, 5-nicotinate salicylate (ST0702 salicylate), down-regulated both ADP-stimulated platelet aggregation and TCIPA. CONCLUSIONS AND IMPLICATIONS Our results show that ST0702 was an effective inhibitor of TCIPA in vitro. Its deacetylated metabolite may contribute to the effects of ST0702 by inhibiting ADP-mediated TCIPA. PMID:22122360

  19. Staphylococcal enterotoxin B initiates protein kinase C translocation and eicosanoid metabolism while inhibiting thrombin-induced aggregation in human platelets.

    PubMed

    Tran, Uyen; Boyle, Thomas; Shupp, Jeffrey W; Hammamieh, Rasha; Jett, Marti

    2006-08-01

    Staphylococcal enterotoxin (SE) B, a heat-stable toxin secreted by Staphylococcus aureus, has been implicated in the pathogenesis and exacerbation of several critical illnesses. It has been hypothesized that enterotoxins may interact with blood products such as platelets, in addition to T-lymphocytes and renal proximal tubule cells. The aim of this present study was to elucidate whether SEB directly alters human platelet function. Human platelet rich plasma (PRP) was pre-incubated with SEA, SEB, SEC or TSST-1, (at various concentrations and incubation times). After incubation, PRP was exposed to thrombin and aggregation was assessed. Incubation with all toxins tested resulted in decreased aggregation, specifically; exposure to 10mu g/ml of SEB for 30 min caused a 20% decrease and a 49% decrease at 90 min. A similar reduction in aggregation was seen in samples incubated with phorbol myristate acetate, a known stimulator of protein kinase C (PKC). Further, platelets exposed to SEB exhibited an increased plasma membrane PKC activity. Sphingosine, an inhibitor of PKC proved to block the SEB-induced reduction in aggregation. SEB effects on platelet metabolism were investigated using high performance liquid chromatography showing up to a 2-fold increase of active metabolites lipoxin A4 and 12-HETE, as compared to control. These data indicate that SEB is able to induce platelet dysfunction, and these effects may be mediated through activation of PKC. PMID:16550298

  20. Study of platelet aggregation in acute coronary syndrome with special reference to metabolic syndrome

    PubMed Central

    Paul, Rudrajit; Banerjee, Amit K; Guha, Shantanu; Chaudhuri, Utpal; Ghosh, Srabani; Mondal, Jayati; Bandyopadhyay, Ramtanu

    2013-01-01

    Background/Context: Antiplatelet drug resistance increases the risk of adverse events like stent thrombosis in acute coronary syndrome (ACS). Metabolic syndrome (MS) is a prothrombotic state and presence of MS further increases the risk of antiplatelet drug resistance. Aims and Objectives: We studied platelet aggregation characteristics in patients of ACS for aspirin or clopidogrel resistance. We studied the relation of drug resistance with blood markers like high sensitivity C-reactive protein (hsCRP). We also studied for any relation of drug resistance with presence of MS. Materials and Methods: We studied platelet aggregation characteristics by optical aggregometry using platelet-rich plasma (PRP) of patients. Collagen (2 μg/mL) and adenosine diphosphate (ADP; 10 μmol) were used. Greater than 50% aggregation in PRP of patients was taken as an evidence of drug resistance. Suitable blood tests were done including newer risk markers like hsCRP, apolipoprotein B, and fibrinogen. Statistical test: Statistical tests included Student's t-test and Kendall's rank correlation coefficient. Results: We had a total of 94 patients of ACS with 47 (50%) having MS. MS patients showed higher blood levels of hsCRP and fibrinogen. Twenty-eight (59.5%) patients with MS showed antiplatelet drug resistance compared to 12 patients without MS. Serum fibrinogen showed strongest correlation with drug resistance. HsCRP levels showed correlation with aspirin resistance (r = 0.53) only in the MS group. Discussion and Conclusion: We found significantly high prevalence of antiplatelet drug resistance. Aspirin and clopidogrel resistance was comparable. MS was a significant risk factor for drug resistance. The prothrombotic and proinflammatory markers showed strong correlation with drug resistance. A larger randomized trial is needed to better characterize this clinical problem. PMID:24083147

  1. Circulating platelet-leukocyte aggregates: a marker of microvascular injury in diabetic patients.

    PubMed

    Elalamy, I; Chakroun, T; Gerotziafas, G T; Petropoulou, A; Robert, F; Karroum, A; Elgrably, F; Samama, M-M; Hatmi, M

    2008-01-01

    Diabetes is associated with multiple disorders including metabolic, cellular and blood disturbances leading to vascular complications. Increased circulating levels of platelet-leukocyte aggregates (PLA) have been described in several thrombotic diseases. In this study, we have evaluated circulating PLA in diabetic patients and we have investigated whether they may be a marker of vascular complications. Using flow cytometry assay, we have quantified PLA percentages in 65 diabetics including 20 patients with type I and 45 with type II diabetes, and 25 healthy subjects. Specific labelling identified platelet-polymorphonuclear aggregates (PPA) and platelet-monocyte aggregates (PMA). We have observed a significant increase of PPA and PMA levels in diabetics (22+/-12% and 45+/-18%, respectively) compared to controls (7+/-4% and 19+/-10%, respectively) (p<0.01). However, both PPA and PMA values were similar in the two diabetes types. Circulating PPA and PMA were significantly enhanced in diabetics with vascular lesions (PPA: 24+/-13%; PMA: 50+/-18%) than in diabetics without vascular lesions (PPA: 18+/-8%; PMA: 38+/-15%) (p<0.05 and p<0.01). Patients with PPA>18% and/or PMA>38% showed a more important vascular injury (OR: 6; 95% CI: 1.6-23). Increased PMA circulating rate is particularly correlated to retinopathic injury (OR: 19; 95% CI: 2.3-154). Our findings established a relationship between increased circulating PLA levels, particularly PMA, and the incidence of microvascular complications in diabetes. They reinforce the concept of pro-inflammatory cells involvement in diabetic retinopathy pathogenesis and their link with thrombotic process. PMID:17825880

  2. Recombinant albumins containing additional peptide sequences smaller than barbourin retain the ability of barbourin-albumin to inhibit platelet aggregation.

    PubMed

    Sheffield, William P; Wilson, Brianna; Eltringham-Smith, Louise J; Gataiance, Sharon; Bhakta, Varsha

    2005-05-01

    The previously described fusion protein BLAH(6) (Marques JA et al.,Thromb Haemost 2001; 86: 902-8) is a recombinant protein that combines the small disintegrin barbourin with hexahistidine-tagged rabbit serumalbumin (RSA) produced in Pichia pastoris yeast. We sought to determine: (1) if BLAH(6) was immunogenic; and (2) if its barbourin domain could be productively replaced with smaller peptides. Purified BLAH(6) was injected into rabbits, and anti-barbourin antibodies were universally detected in plasma 28 days later; BLAH(6) was, however, equally effective in reducing platelet aggregation in both naive and pre-treated rabbits. Thrombocytopenia was not observed, and complexing BLAH(6) to alpha(IIb)beta(3) had no effect on antibody detection. The barbourin moiety of BLAH(6) was replaced with each of four sequences: Pep I (VCKGDWPC); PepII (VCRGDWPC); PepIII (bar-bourin 41-54); and PepIV (LPSPGDWR). The corresponding fusion proteins were tested for their ability to inhibit ADP-induced platelet aggregation. PepIII-LAH(6) inhibited neither rabbit nor human platelets. PepI-LAH(6) and PepIV-LAH(6) inhibited rabbit platelet aggregation as effectively as BLAH(6), but PepIV-LAH(6) did not inhibit human platelet aggregation. PepI-LAH(6) and PepIILAH(6) inhibited human platelet aggregation with IC(50)s 10- and 20-fold higher than BLAH(6). Cross-immunoprecipitation assays with human platelet lysates confirmed that all proteins and peptides interacted with the platelet integrin alpha(IIb)beta(3), but with greatly varying affinities. Our results suggest that the antiplatelet activity of BLAH(6) can be retained in albumin fusion proteins in which smaller peptides replace the barbourin domain; these proteins may be less immunogenic than BLAH(6).

  3. Platelet Inhibitors.

    PubMed

    Shifrin, Megan M; Widmar, S Brian

    2016-03-01

    Antithrombotic medications have become standard of care for management of acute coronary syndrome. Platelet adhesion, activation, and aggregation are essential components of platelet function; platelet-inhibiting medications interfere with these components and reduce incidence of thrombosis. Active bleeding is a contraindication for administration of platelet inhibitors. There is currently no reversal agent for platelet inhibitors, although platelet transfusion may be used to correct active bleeding after administration of platelet inhibitors. PMID:26897422

  4. [Coumarins from Leonurus japonicus and their anti-platelet aggregative activity].

    PubMed

    Yang, Huai; Zhou, Qin-mei; Peng, Cheng; Liu, Lu-si; Xie, Xiao-fang; Xiong, Liang; Liu, Zhao-hua

    2014-11-01

    Chemical constituents of Leonurus japonicus were isolated and purified by a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, MCI, and Rp C18. Structures of the isolates were determined by spectroscopic analysis as 10 coumarins: bergapten (1), xanthotoxin (2), isopimpinellin (3), isogosferal (4), imperatorin (5), meransin hydrate(6), isomeranzin(7), murrayone(8) , auraptenol(9), and osthol(10). In addition to compound 9, the others were isolated from the genus Leonurus for the first time. In the in vitro assay, compounds 4 and 8 significantly inhibited the abnormal increase of platelet aggregation induced by ADP.

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

    SciTech Connect

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

    2014-07-04

    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.

  6. Roles of Mac-1 and glycoprotein IIb/IIIa integrins in leukocyte-platelet aggregate formation: stabilization by Mac-1 and inhibition by GpIIb/IIIa blockers.

    PubMed

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

    2012-01-01

    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.

  7. Aspirin decreases platelet uptake on Dacron vascular grafts in baboons

    SciTech Connect

    Mackey, W.C.; Connolly, R.J.; Callow, A.D.; Keough, E.M.; Ramberg-Laskaris, K.; McCullough, J.L.; O'Donnell, T.F. Jr.; Melaragno, A.; Valeri, C.R.; Weiblen, B.

    1984-07-01

    The influence of a single dose of aspirin (5.4-7.4 mg/kg) on platelet uptake on 4-mm Dacron interposition grafts was studied in a baboon model using gamma camera scanning for 111-Indium labeled platelets. In vitro assessment of platelet function after aspirin administration revealed that in the baboon, as in the human, aspirin abolished arachidonic acid-induced platelet aggregation, prolonged the lag time between exposure to collagen and aggregation, and decreased plasma thromboxane B2 levels. Aspirin also prolonged the template bleeding time. Scans for 111-Indium labeled platelets revealed that pretreatment with a single dose of aspirin decreased platelet uptake on 4-mm Dacron carotid interposition grafts. This decrease in platelet uptake was associated with a significant improvement in 2-hour graft patency and with a trend toward improved 2-week patency.

  8. The membrane potential modulates thrombin-stimulated Ca²⁺ mobilization and platelet aggregation.

    PubMed

    Albarrán, Letizia; Dionisio, Natalia; López, Esther; Salido, Ginés M; Rosado, Juan A

    2013-10-15

    G protein-coupled receptors can be directly modulated by changes in transmembrane voltage in a variety of cell types. Here we show that, while changes in the membrane voltage itself do not induce detectable modifications in the cytosolic Ca(2+) concentration, platelet stimulation with thrombin or the PAR-1 and PAR-4 agonist peptides SFLLRN and AYPGKF, respectively, results in Ca(2+) release from intracellular stores that is sensitive to the membrane depolarisation. Direct activation of G proteins or phospholipase C by AlF4(-) and m-3M3FBS, respectively, leads to Ca(2+) release that is insensitive to changes in the membrane potential. Thapsigargin-, as well as OAG-induced Ca(2+) entry are affected by the membrane voltage, probably as a result of the modification in the driving force for Ca(2+) influx; however, hyperpolarisation does not enhance thrombin- or OAG-evoked Ca(2+) entry probably revealing the presence of a voltage-sensitive regulatory mechanism. Transmembrane voltage also modulates the activity of the plasma membrane Ca(2+)-ATPase (PMCA) most likely due to a decrease in the phosphotyrosine content of the pump. Thrombin-stimulated platelet aggregation is modulated by membrane depolarisation by a mechanism that is, at least partially, independent of Ca(2+). These observations indicate that PAR-1 and PAR-4 receptors are modulated by the membrane voltage in human platelets. PMID:23988350

  9. [Platelet aggregation upon acetylsalicylic acid and clopidogrel treatment and glycoprotein IIb/IIIa content in patients with acute coronary syndrome].

    PubMed

    Khaspekova, S G; Ziuriaev, I T; Iakushkin, V V; Golubeva, N V; Ruda, M Ia; Mazurov, A V

    2011-01-01

    Interaction between aggregating activity of platelets and glycoprotein (GP) IIb/IIIa (fibrinogen receptor) content on their surface was investigated in patients with acute coronary syndrome (ACS). Eighty nine ACS patients were included into the study - 69 with and 20 without elevation of ST segment. Blood was collected within the first hour of admission to the clinic (1 day), and then at 3-5 and 8-12 days. All patients received standard antiaggregant therapy - acetylsalicylic acid - ASA (thromboxane A2 synthesis inhibitor) and clopidogrel (ADP receptor antagonist). Platelet aggregation was analyzed at the first time point when patients had already taken ASA but not clopidogrel, and then (3-5 and 8- 12 days) upon combined therapy with both preparations. Aggregation was induced by 5 and 20 uM ADP and measured by turbidimetric method. In comparison with the initial level (1 day, ASA) at days 3-5, i.e. after development of clopidogrel effect, platelet aggregation was decreased by 54 and 40% upon its stimulation with 5 and 20 uM ADP, and was not further changed at days 8-12. GP IIb/IIIa content on platelet surface was determined by binding of 125I-labelled monoclonal antibody CRC64. GP IIb/IIIa number varied from 31100 to 73000 per platelet with the mean level of 48500 +/- 8400 (mean +/- standard deviation). No differences were detected between mean GP IIb/IIIa number at 1, 3-5 and 8-12 days after ACS onset. Upon repeat GP IIb/IIIa measurement coefficient of variation was 6.1% demonstrating the stability of this parameter in each patient. Positive correlation between platelet aggregation and GP IIb/IIIa content was detected at the first day - correlation coefficients (r) 0.425 and 0.470 for 5 and 20 uM ADP (n=57, p<0.001). However positive association between these parameters was not revealed at 3-5 and 8-12 days, when patients received not only ASA but clopidogrel as well (r from -0.054 to -0.237, p>0.05). These results indicates that variations of GP IIb/IIIa content

  10. Inhibitory effects of total flavones of Hippophae Rhamnoides L on thrombosis in mouse femoral artery and in vitro platelet aggregation.

    PubMed

    Cheng, Jiayi; Kondo, Kazunao; Suzuki, Yasuhiro; Ikeda, Yasuhiko; Meng, Xiansheng; Umemura, Kazuo

    2003-04-01

    Total flavones of Hippophae Rhamnoides L (TFH) are extracted from Sea buckthorn, a Chinese herbal medicine. Sea buckthorn has antioxidant, anti-ulcerogenic and hepato-protective actions, and its berry oil is reported to suppress platelet aggregation. Though it is frequently used for patients with thrombosis, the likely mechanism(s) and effects of TFH on thrombogenesis remain unclear. Thus, we have investigated the effect in-vivo of TFH on thrombogenesis and in vitro on platelet aggregation, comparing them to those of aspirin. We measured thrombotic occlusion time in a mouse femoral artery thrombosis model by the photochemical reaction between intravenously injected rose bengal and green light irradiation. In vitro platelet aggregation in whole blood was measured by single platelet counting. Thrombotic occlusion time was 8.5 +/- 0.6 min in the control group. TFH at a dose of 300 micro g/kg, intravenously administered 15 min before the rose bengal injection, significantly prolonged it to 11.6 +/- 1.0 min (P < 0.05), a similar effect on in-vivo thrombogenesis to that of aspirin. TFH at a concentration of 3.0 micro g/ml significantly (P < 0.01) inhibited in vitro platelet aggregation induced by collagen (2 micro g/ml) in a concentration dependent manner, in contrast TFH did not affect aggregation induced by arachidonic acid (80 micro M) and ADP (0.3 micro M). The results of the present study, in which TFH prevented in-vivo thrombogenesis, probably due to inhibition of platelet aggregation, suggest a possible clinical approach for the prevention of thrombosis. PMID:12628446

  11. Purification and Characterization of BmooAi: A New Toxin from Bothrops moojeni Snake Venom That Inhibits Platelet Aggregation

    PubMed Central

    Ribeiro de Queiroz, Mayara; Mamede, Carla Cristine N.; de Morais, Nadia Cristina G.; Cortes Fonseca, Kelly; Barbosa de Sousa, Bruna; Migliorini, Thaís M.; Pereira, Déborah Fernanda C.; Stanziola, Leonilda; Calderon, Leonardo A.; Simões-Silva, Rodrigo; Martins Soares, Andreimar; de Oliveira, Fábio

    2014-01-01

    In this paper, we describe the purification/characterization of BmooAi, a new toxin from Bothrops moojeni that inhibits platelet aggregation. The purification of BmooAi was carried out through three chromatographic steps (ion-exchange on a DEAE-Sephacel column, molecular exclusion on a Sephadex G-75 column, and reverse-phase HPLC chromatography on a C2/C18 column). BmooAi was homogeneous by SDS-PAGE and shown to be a single-chain protein of 15,000 Da. BmooAi was analysed by MALDI-TOF Spectrometry and revealed two major components with molecular masses 7824.4 and 7409.2 as well as a trace of protein with a molecular mass of 15,237.4 Da. Sequencing of BmooAi by Edman degradation showed two amino acid sequences: IRDFDPLTNAPENTA and ETEEGAEEGTQ, which revealed no homology to any known toxin from snake venom. BmooAi showed a rather specific inhibitory effect on platelet aggregation induced by collagen, adenosine diphosphate, or epinephrine in human platelet-rich plasma in a dose-dependent manner, whereas it had little or no effect on platelet aggregation induced by ristocetin. The effect on platelet aggregation induced by BmooAi remained active even when heated to 100°C. BmooAi could be of medical interest as a new tool for the development of novel therapeutic agents for the prevention and treatment of thrombotic disorders. PMID:24971359

  12. Inhibitory effects and mechanisms of high molecular-weight phlorotannins from Sargassum thunbergii on ADP-induced platelet aggregation

    NASA Astrophysics Data System (ADS)

    Wei, Yuxi; Wang, Changyun; Li, Jing; Guo, Qi; Qi, Hongtao

    2009-09-01

    We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii (STP) on ADP-induced platelet aggregation and arachidonic acid (AA) metabolism in New Zealand white rabbits and Wistar rats. The inhibition of STP on platelet aggregation was investigated using a turbidimetric method, and the levels of the terminal products of AA metabolism were measured using the corresponding kits for maleic dialdehyde (MDA), thromboxane B2 (TXB2) and 6-keto-prostaglandin F1α (6-keto-PGF1α) by colorimetry and radioimmunoassay, as appropriate. We found that STP could inhibit ADP-induced platelet aggregation, and the inhibitory ratio was 91.50% at the STP concentration of 4.0 mg/mL. Furthermore, STP markedly affected AA metabolism by decreasing the synthesis of MDA ( P<0.01) and increasing the synthesis of 6-keto-PGF1α, thus changing the plasma TXB2/6-keto-PGF1α balance when the platelets were activated ( P<0.01). Therefore, STP altered AA metabolism and these findings partly revealed the molecular mechanism by which STP inhibits ADP-induced platelet aggregation.

  13. Platelet aggregation responses and virus isolation from platelets in calves experimentally infected with type I or type II bovine viral diarrhea virus.

    PubMed

    Walz, P H; Bell, T G; Grooms, D L; Kaiser, L; Maes, R K; Baker, J C

    2001-10-01

    Altered platelet function has been reported in calves experimentally infected with type II bovine viral diarrhea virus (BVDV). The purpose of the present study was to further evaluate the ability of BVDV isolates to alter platelet function and to examine for the presence of a virus-platelet interaction during BVDV infection. Colostrum-deprived Holstein calves were obtained immediately after birth, housed in isolation, and assigned to 1 of 4 groups (1 control and 3 treatment groups). Control calves (n = 4) were sham inoculated, while calves in the infected groups (n = 4 for each group) were inoculated by intranasal instillation with 10(7) TCID50 of either BVDV 890 (type II), BVDV 7937 (type II), or BVDV TGAN (type I). Whole blood was collected prior to inoculation (day 0) and on days 4, 6, 8, 10, and 12 after inoculation for platelet function testing by optical aggregometry by using adenosine diphosphate and platelet activating factor. The maximum percentage aggregation and the slope of the aggregation curve decreased over time in BVDV-infected calves; however, statistically significant differences (Freidman repeated measures ANOVA on ranks, P < 0.05) were only observed in calves infected with the type II BVDV isolates. Bovine viral diarrhea virus was not isolated from control calves, but was isolated from all calves infected with both type II BVDV isolates from days 4 through 12 after inoculation. In calves infected with type I BVDV, virus was isolated from 1 of 4 calves on days 4 and 12 after inoculation and from all calves on days 6 and 8 after inoculation. Altered platelet function was observed in calves infected with both type II BVDV isolates, but was not observed in calves infected with type I BVDV. Altered platelet function may be important as a difference in virulence between type I and type II BVDV infection.

  14. Effects of a garlic-derived principle (ajoene) on aggregation and arachidonic acid metabolism in human blood platelets.

    PubMed

    Srivastava, K C; Tyagi, O D

    1993-08-01

    When garlic cloves are chopped or crushed several dialkyl thiosulfinates are rapidly formed by the action of the enzyme alliin lyase or alliinase (EC 4.4.1.4) on S(+)-alkyl-L-cysteine sulfoxides. Allicin (diallyl thiosulfinate or allyl 2-propene thiosulfinate) is the dominant thiosulfinate released. A variety of sulfur containing compounds are formed from allicin and other thiosulfinates depending on the way in which garlic is handled. One such compound identified recently is ajoene which has been reported to possess antithrombotic properties. We present here data on the antiplatelet properties of ajoene together with its effects on the metabolism of arachidonic acid (AA) in intact platelets. Thus, ajoene was found to inhibit platelet aggregation induced by AA, adrenaline, collagen, adenosine diphosphate (ADP) and calcium ionophore A23187; the nature of the inhibition was irreversible. In washed platelets stimulated by labelled arachidonate, ajoene inhibited the formation of thromboxane A2; 12-lipoxygenase product(s) were reduced at higher ajoene concentrations. This garlic-derived substance inhibited the incorporation of labelled AA into platelet phospholipids at higher concentration. In labelled platelets, on stimulation with either calcium ionophore A23187 or collagen, reduced amounts of thromboxane and 12-HETE (12-hydroxyeicosatetraenoic acid) were produced in ajoene-treated platelets compared to control platelets. This substance had no effect on the deacylation of platelet phospholipids. The results suggest that at least one of the mechanisms by which ajoene shows antiplatelet effects could be related to altered metabolism of AA.

  15. Effect of prenylated flavonoids and chalcones isolated from Artocarpus species on platelet aggregation in human whole blood.

    PubMed

    Jantan, Ibrahim; Mohd Yasin, Yusyila H; Jamil, Shajarahtunnur; Sirat, Hasnah; Basar, Norazah

    2010-07-01

    Five prenylflavonoids and two prenylchalcones from Artocarpus lowii King, A. scortechinii King and A. teysmanii Miq., and acetylated derivatives of cycloheterophyllin and artonin E were investigated for their ability to inhibit arachidonic acid (AA), collagen and adenosine diphosphate (ADP)-induced platelet aggregation in human whole blood by using an electrical impedance method. Among the tested compounds, only cycloheterophyllin inhibited AA-induced platelet aggregation with an IC(50) value of 100.9 microM. It also showed strong inhibition against ADP-induced aggregation, with an IC(50) value of 57.1 microM. Isobavachalcone, 2',4'-dihydroxy-4-methoxy-3'-prenyldihydrochalcone, cycloartobiloxanthone, artonin E and artonin E triacetate showed selective inhibition against ADP-induced aggregation, with IC(50) values ranging from 55.3 to 192.0 microM, but did not show such effect against other inducers.

  16. Venous levels of shear support neutrophil-platelet adhesion and neutrophil aggregation in blood via P-selectin and beta2-integrin

    NASA Technical Reports Server (NTRS)

    Konstantopoulos, K.; Neelamegham, S.; Burns, A. R.; Hentzen, E.; Kansas, G. S.; Snapp, K. R.; Berg, E. L.; Hellums, J. D.; Smith, C. W.; McIntire, L. V.; Simon, S. I.

    1998-01-01

    BACKGROUND: After activation, platelets adhere to neutrophils via P-selectin and beta2-integrin. The molecular mechanisms and adhesion events in whole blood exposed to venous levels of hydrodynamic shear in the absence of exogenous activation remain unknown. METHODS AND RESULTS: Whole blood was sheared at approximately 100 s(-1). The kinetics of neutrophil-platelet adhesion and neutrophil aggregation were measured in real time by flow cytometry. P-selectin was upregulated to the platelet surface in response to shear and was the primary factor mediating neutrophil-platelet adhesion. The extent of neutrophil aggregation increased linearly with platelet adhesion to neutrophils. Blocking either P-selectin, its glycoprotein ligand PSGL-1, or both simultaneously by preincubation with a monoclonal antibody resulted in equivalent inhibition of neutrophil-platelet adhesion (approximately 30%) and neutrophil aggregation (approximately 70%). The residual amount of neutrophil adhesion was blocked with anti-CD11b/CD18. Treatment of blood with prostacyclin analogue ZK36374, which raises cAMP levels in platelets, blocked P-selectin upregulation and neutrophil aggregation to baseline. Complete abrogation of platelet-neutrophil adhesion required both ZK36374 and anti-CD18. Electron microscopic observations of fixed blood specimens revealed that platelets augmented neutrophil aggregation both by forming bridges between neutrophils and through contact-mediated activation. CONCLUSIONS: The results are consistent with a model in which venous levels of shear support platelet adherence to neutrophils via P-selectin binding PSGL-1. This interaction alone is sufficient to mediate neutrophil aggregation. Abrogation of platelet adhesion and aggregation requires blocking Mac-1 in addition to PSGL-1 or P-selectin. The described mechanisms are likely of key importance in the pathogenesis and progression of thrombotic disorders that are exacerbated by leukocyte-platelet aggregation.

  17. Vascular pentraxin 3 controls arterial thrombosis by targeting collagen and fibrinogen induced platelets aggregation

    PubMed Central

    Bonacina, F.; Barbieri, S.S.; Cutuli, L.; Amadio, P.; Doni, A.; Sironi, M.; Tartari, S.; Mantovani, A.; Bottazzi, B.; Garlanda, C.; Tremoli, E.; Catapano, A.L.; Norata, G.D.

    2016-01-01

    Aim The long pentraxin PTX3 plays a non-redundant role during acute myocardial infarction, atherosclerosis and in the orchestration of tissue repair and remodeling during vascular injury, clotting and fibrin deposition. The aim of this work is to investigate the molecular mechanisms underlying the protective role of PTX3 during arterial thrombosis. Methods and results PTX3 KO mice transplanted with bone marrow from WT or PTX3 KO mice presented a significant reduction in carotid artery blood flow following FeCl3 induced arterial thrombosis (− 80.36 ± 11.5% and − 95.53 ± 4.46%), while in WT mice transplanted with bone marrow from either WT or PTX3 KO mice, the reduction was less dramatic (− 45.55 ± 1.37% and − 53.39 ± 9.8%), thus pointing to a protective effect independent of a hematopoietic cell's derived PTX3. By using P-selectin/PTX3 double KO mice, we further excluded a role for P-selectin, a target of PTX3 released by neutrophils, in vascular protection played by PTX3. In agreement with a minor role for hematopoietic cell-derived PTX3, platelet activation (assessed by flow cytometric expression of markers of platelet activation) was similar in PTX3 KO and WT mice as were haemostatic properties. Histological analysis indicated that PTX3 localizes within the thrombus and the vessel wall, and specific experiments with the N-terminal and the C-terminal PTX3 domain showed the ability of PTX3 to selectively dampen either fibrinogen or collagen induced platelet adhesion and aggregation. Conclusion PTX3 interacts with fibrinogen and collagen and, by dampening their pro-thrombotic effects, plays a protective role during arterial thrombosis. PMID:26976330

  18. A novel thromboxane receptor antagonist, nstpbp5185, inhibits platelet aggregation and thrombus formation in animal models.

    PubMed

    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

    2016-08-01

    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.

  19. A novel thromboxane receptor antagonist, nstpbp5185, inhibits platelet aggregation and thrombus formation in animal models.

    PubMed

    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

    2016-08-01

    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. PMID:27173725

  20. Tripeptide SQL Inhibits Platelet Aggregation and Thrombus Formation by Affecting PI3K/Akt Signaling.

    PubMed

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

    2015-09-01

    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. PMID:25923322

  1. Tripeptide SQL Inhibits Platelet Aggregation and Thrombus Formation by Affecting PI3K/Akt Signaling.

    PubMed

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

    2015-09-01

    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.

  2. The Heparin-Induced Thrombocytopenia and Thrombosis Syndrome: Treatment with Intraarterial Urokinase and Systemic Platelet Aggregation Inhibitors

    SciTech Connect

    Murphy, Kenneth D.; McCrohan, Gerard; DeMarta, Deborah A.; Shirodkar, Nitin B.; Kwon, Oun J.; Chopra, Paramjit S.

    1996-03-15

    We report a case of the heparin-induced thrombocytopenia and thrombosis syndrome presenting with acute ischemia of a lower limb. The patient was successfully treated by withdrawal of heparin products, intraarterial urokinase, and platelet anti-aggregation therapy consisting of Dextran and aspirin.

  3. Platelet function: aggregation by PAF or sequestration in lung is not modified during immediate or late allergen-induced bronchospasm in man.

    PubMed

    Hemmendinger, S; Pauli, G; Tenabene, A; Pujol, J L; Bessot, J C; Eber, M; Cazenave, J P

    1989-05-01

    Among the mediators involved in the pathophysiologic mechanisms that underly the reactions of the acute and delayed phases of bronchospasm induced by allergens in man, platelet-activating factor (PAF) could play an important role, in particular by its effects on platelets. In animals, inhalation or injection of PAF causes a platelet-dependent bronchoconstriction that is blocked by prior administration of an antiplatelet antiserum and accompanied by platelet accumulation in the pulmonary vessels. In man, inhalation of PAF causes a bronchospasm and induces a bronchial hyperreactivity. Abnormalities of platelet aggregation and the secretion into plasma of platelet factor 4 and beta-thromboglobulin have been described in patients with asthma during induced bronchospasm. Platelet functions have been studied in 15 patients with asthma before and after allergen bronchial provocation tests. There was no difference between platelet counts, plasma concentrations of platelet factor 4 and beta-thromboglobulin, and platelet aggregation induced by several agonists (adrenaline, arachidonic acid, or PAF) before and immediately after the allergen bronchial provocation test. There was no platelet pulmonary sequestration as studied with 111Indium-labeled platelets during 24 hours after the antigen challenge, and the life span of circulating platelets was normal. Our results do not support an important direct role for PAF in the pathophysiology of asthma. It is still possible that the current methodology is too insensitive to detect amounts of PAF in the circulation or that PAF is acting locally. PMID:2523922

  4. Pharmacokinetics of puerarin and ginsenoside Rg1 of CBN injection and the relation with platelet aggregation in rats.

    PubMed

    Liu, Ruining; Xing, Dongming; Lu, Hong; Wu, Hao; Du, Lijun

    2006-01-01

    In order to study the pharmacokinetics of puerarin and ginsenoside Rg1 of cerebral blood nutrition (CBN) and its relationship with pharmacodynamics of platelet aggregation induced by ADP in rat, the blood samples after injection were collected. The concentrations of puerarin and ginsenoside Rg1 in plasma were determined by RP-HPLC, and the platelet aggregations were observed simultaneously. The data showed that there was distinct statistic significance (p < 0.01) for puerarin processing, which was a single compartment model with quick elimination rate (t(1/2beta) = 18 min) and MRT (26 min), while ginsenoside Rg1 processing was a double compartment model with rapid distribution rate (t(1/2alpha) = 8 min), slow elimination rate (t(1/2beta) = 11 hours) and MRT (3.3 hours). Effects of anti-platelet aggregation were presented at 5-10 min, 45-90 min and 6-8 hours after injection separately, and the corresponding concentrations of puerarin were 25-21 microg/ml, 4.5-0.8 microg/ml and 0 microg/ml, ginsenoside Rg1 were 7.6-6.7 microg/ml, 1.2-0.6 microg/ml and 1.8-0.5 microg/ml. The two components presented a positive correlation between their concentrations and the effect of anti-platelet aggregation in 5-10 min after CBN injection (coefficient of correlation were 0.999 and 0.995). However, it was noted that the effect was still stronger even when concentrations of puerarin and ginsenoside Rg1 in plasma decreased. Therefore, puerarin and ginsenoside Rg1 not only had different pharmacokinetics, but also had a positive correlation with platelet aggregation, just in 5-10 min after CBN injection.

  5. The pyrrolidinoindoline alkaloid Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling

    PubMed Central

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

    2016-01-01

    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

  6. Identification and characterization of a collagen-induced platelet aggregation inhibitor, triplatin, from salivary glands of the assassin bug, Triatoma infestans.

    PubMed

    Morita, Akihiro; Isawa, Haruhiko; Orito, Yuki; Iwanaga, Shiroh; Chinzei, Yasuo; Yuda, Masao

    2006-07-01

    To facilitate feeding, certain hematophagous invertebrates possess inhibitors of collagen-induced platelet aggregation in their saliva. However, their mechanisms of action have not been fully elucidated. Here, we describe two major salivary proteins, triplatin-1 and -2, from the assassin bug, Triatoma infestans, which inhibited platelet aggregation induced by collagen but not by other agents including ADP, arachidonic acid, U46619 and thrombin. Furthermore, these triplatins also inhibited platelet aggregation induced by collagen-related peptide, a specific agonist of the major collagen-signaling receptor glycoprotein (GP)VI. Moreover, triplatin-1 inhibited Fc receptor gamma-chain phosphorylation induced by collagen, which is the first step of GPVI-mediated signaling. These results strongly suggest that triplatins target GPVI and inhibit signal transduction necessary for platelet activation by collagen. This is the first report on the mechanism of action of collagen-induced platelet aggregation inhibitors from hematophagus invertebrates. PMID:16759235

  7. PGE(2) reverses G(s)-mediated inhibition of platelet aggregation by interaction with EP3 receptors, but adds to non-G(s)-mediated inhibition of platelet aggregation by interaction with EP4 receptors.

    PubMed

    Glenn, Jacqueline R; White, Ann E; Iyu, David; Heptinstall, Stan

    2012-01-01

    Prostaglandin E(2) (PGE(2)) has intriguing effects on platelet function in the presence of agents that raise cyclic adenosine 3'5'-monophosphate (cAMP). PGE(2) reverses inhibition of platelet aggregation by agents that stimulate cAMP production via a G(s)-linked receptor, but adds to the inhibition of platelet function brought about by agents that raise cAMP through other mechanisms. Here, we used the EP receptor antagonists DG-041 (which acts at the EP3 receptor) and ONO-AE3-208 (which acts at the EP4 receptor) to investigate the role of these receptors in mediating these effects of PGE(2). Platelet aggregation was measured in platelet-rich plasma obtained from healthy volunteers in response to adenosine diphosphate (ADP) using single platelet counting. The effects of a range of concentrations of PGE(2) were determined in the presence of (1) the prostacyclin mimetic iloprost, which operates through G(s)-linked IP receptors, (2) the cAMP PDE inhibitor DN9693 and (3) the direct-acting adenylate cyclase stimulator forskolin. Vasodilator-stimulated phosphoprotein (VASP) phosphorylation was also determined as a measure of cAMP. PGE(2) reversed the inhibition of aggregation brought about by iloprost; this was prevented in the presence of the EP3 antagonist DG-041, indicating that this effect of PGE(2) is mediated via the EP3 receptor. In contrast, PGE(2) added to the inhibition of aggregation brought about by DN9693 or forskolin; this was reversed by the EP4 antagonist ONO-AE3-208, indicating that this effect of PGE(2) is mediated via the EP4 receptor. Effects on aggregation were accompanied by corresponding changes in VASP phosphorylation. The dominant role of EP3 receptors circumstances where cAMP is increased through a Gs-linked mechanism may be relevant to the situation in vivo where platelets are maintained in an inactive state through constant exposure to prostacyclin, and thus the main effect of PGE(2) may be prothrombotic. If so, the results described here

  8. Platelet adhesiveness and aggregation in congenital afibrinogenemia. An investigation of three patients with post-transfusion, cross-correction studies between two of them.

    PubMed

    Girolami, A; De Marco, L; Virgolini, L; Peruffo, R; Fabris, F

    1975-02-01

    Platelet adhesiveness and aggregation were studied in three patients with congenital afibrinogenemia. The results obtained may be summarized as follows: The retention of platelets to a glass-bead filter determined with the Salzman method was significantly decreased; it was normal after fibrinogen infusion. With a modification of the Hellem test the values obtained were slightly decreased. Adrenalin-induced aggregation was absent whereas ADP-and collagen-induced aggregation was near normal or slightly decreased. Thrombofax aggregation was absent in citrated plasma. The abnormalities of platelet aggregation were corrected after fibrinogen infusion or after addition in vitro of fibrinogen, hemofilia A plasma and PPP obtained from an afibrinogenemic patient after fibrinogen infusion. The abnormalities of platelet aggregation were corrected well by ADP, collagen and Thrombofax in heparinized blood, but only a slight correction of adrenalin-induced aggregation was noted. Thrombin aggregation proved to be normal with the higher concentrations, whereas it was defective with the lower ones. Ristocetin aggregation was normal in citrated plasma at the concentration of 1.5 mg per ml but it was absent at the lower concentration (1.0 mg per ml). Ristocetin aggregation was, on the other hand absent in heparinized blood regardless of the concentration. These findings are in agreement with the presence of a prolonged bleeding time in congenital afibrinogenemia and suggest that fibrinogen plays an important role in platelet aggregation and adhesiveness.

  9. ADP-induced platelet aggregation after addition of tramadol in vitro in fed and fasted horses plasma.

    PubMed

    Casella, S; Giannetto, C; Giudice, E; Marafioti, S; Fazio, F; Assenza, A; Piccione, G

    2013-04-01

    Adenosine diphosphate (ADP)-induced platelet aggregation in fed and fasted horses after addition of tramadol hydrochloride was evaluated in vitro. On 10 horses citrated blood samples were collected 2h after feeding (fed animals) and 21 h after feeding (fasted animals). Final concentrations of ADP 1 and 0.5 μM, and tramadol hydrochloride (1, 15, 30, 45 and 60 min after the addition of tramadol) were used to determine the maximum degree and initial velocity of platelet aggregation. Repeated measures multifactor analysis of variance (MANOVA) was used to evaluate the effect of feeding/fasting condition, ADP concentration and addition of tramadol. Findings showed statistical differences (P≤0.05) on studied parameters after addition of tramadol to different ADP concentrations in fed and fasted horses. The clinical relevance of these results is that tramadol provides many advantages as a therapeutic option; in fact, it is an inexpensive and a relatively new analgesic in equine veterinary medicine. Further investigations would be appropriate to compare the effects of different opioids but also using different concentrations of tramadol associated with other drugs in order to have substances which can regulate the functional activity of the platelets and to extend the knowledges on equine platelet aggregation. PMID:23031839

  10. Investigation of cyclooxygenase and signaling pathways involved in human platelet aggregation mediated by synergistic interaction of various agonists

    PubMed Central

    Khan, Nadia; Farooq, Ahsana Dar; Sadek, Bassem

    2015-01-01

    In the present study, the mechanism(s) of synergistic interaction of various platelet mediators such as arachidonic acid (AA) when combined with 5-hydroxytryptamine (5-HT) or adenosine diphosphate (ADP) on human platelet aggregation were examined. The results demonstrated that 5-HT had no or negligible effect on aggregation but it did potentiate the aggregation response of AA. Similarly, the combination of subeffective concentrations of ADP and AA exhibited noticeable rise in platelet aggregation. Moreover, the observed synergistic effect of AA with 5-HT on platelets was inhibited by different cyclooxygenase (COX) inhibitors, namely ibuprofen and celecoxib, with half maximal inhibitory effect (IC50) values of 18.0±1.8 and 15.6±3.4 μmol/L, respectively. Interestingly, the synergistic effect observed for AA with 5-HT was, also, blocked by the 5-HT receptor blockers cyproheptadine (IC50=22.0±7 μmol/L), ketanserin (IC50=152±23 μmol/L), phospholipase C (PLC) inhibitor (U73122; IC50=6.1±0.8 μmol/L), and mitogen activated protein kinase (MAPK) inhibitor (PD98059; IC50=3.8±0.5 μmol/L). Likewise, the synergism of AA and ADP was, also, attenuated by COX inhibitors (ibuprofen; IC50=20±4 μmol/L and celecoxib; IC50=24±7 μmol/L), PLC inhibitor (U73122; IC50=3.7±0.3 μmol/L), and MAPK inhibitor (PD98059; IC50=2.8±1.1 μmol/L). Our observed data demonstrate that the combination of subthreshold concentrations of agonists amplifies platelet aggregation and that these synergistic effects largely depend on activation of COX/thromboxane A2, receptor-operated Ca2+ channels, Gq/PLC, and MAPK signaling pathways. Moreover, our data revealed that inhibition of COX pathways by using both selective and/or non-selective COX inhibitors blocks not only AA metabolism and thromboxane A2 formation, but also its binding to Gq receptors and activation of receptor-operated Ca2+ channels in platelets. Overall, our results show that PLC and MAPK inhibitors proved to inhibit the

  11. Genetic Variation in the Platelet Endothelial Aggregation Receptor 1 Gene Results in Endothelial Dysfunction.

    PubMed

    Fisch, Adam S; Yerges-Armstrong, Laura M; Backman, Joshua D; Wang, Hong; Donnelly, Patrick; Ryan, Kathleen A; Parihar, Ankita; Pavlovich, Mary A; Mitchell, Braxton D; O'Connell, Jeffrey R; Herzog, William; Harman, Christopher R; Wren, Jonathan D; Lewis, Joshua P

    2015-01-01

    Platelet Endothelial Aggregation Receptor 1 (PEAR1) is a newly identified membrane protein reported to be involved in multiple vascular and thrombotic processes. While most studies to date have focused on the effects of this receptor in platelets, PEAR1 is located in multiple tissues including the endothelium, where it is most highly expressed. Our first objective was to evaluate the role of PEAR1 in endothelial function by examining flow-mediated dilation of the brachial artery in 641 participants from the Heredity and Phenotype Intervention Heart Study. Our second objective was to further define the impact of PEAR1 on cardiovascular disease computationally through meta-analysis of 75,000 microarrays, yielding insights regarding PEAR1 function, and predictions of phenotypes and diseases affected by PEAR1 dysregulation. Based on the results of this meta-analysis we examined whether genetic variation in PEAR1 influences endothelial function using an ex vivo assay of endothelial cell migration. We observed a significant association between rs12041331 and flow-mediated dilation in participants of the Heredity and Phenotype Intervention Heart Study (P = 0.02). Meta-analysis results revealed that PEAR1 expression is highly correlated with several genes (e.g. ANG2, ACVRL1, ENG) and phenotypes (e.g. endothelial cell migration, angiogenesis) that are integral to endothelial function. Functional validation of these results revealed that PEAR1 rs12041331 is significantly associated with endothelial migration (P = 0.04). Our results suggest for the first time that genetic variation of PEAR1 is a significant determinant of endothelial function through pathways implicated in cardiovascular disease. PMID:26406321

  12. Comparative evaluation of antiplatelet effect of lycopene with aspirin and the effect of their combination on platelet aggregation: An in vitro study

    PubMed Central

    Sawardekar, Swapna B.; Patel, Tejal C.; Uchil, Dinesh

    2016-01-01

    Introduction: The objective was to compare antiplatelet effect of lycopene with aspirin and to study effect of combination of the two on platelet aggregation in vitro, using platelets from healthy volunteers. Materials and Methods: Platelets were harvested; platelet count of platelet-rich plasma adjusted to 2.5 Χ 105/μL. Aspirin (140 μmol/L) and lycopene (4, 6, 8, 10, and 12 μmol/L) were studied in vitro against adenosine-5’- diphosphate (ADP) (2.5 μM/L) and collagen Results: All the concentrations of lycopene (4–12 μmol/L) exhibited reduction in maximum platelet aggregation induced by aggregating agents ADP and collagen (P < 0.01 vs. vehicle) and were comparable with aspirin. Lycopene at concentration 10 μmol/L showed maximum platelet inhibition (47.05% ± 19.56%) against ADP, whereas lycopene at concentration 8 μmol/L showed maximum platelet inhibition (54.26% ± 30.71%) against collagen. Four μmol/L of lycopene combined with 140 μmol/L and 70 μmol/L aspirin showed greater inhibition of platelets as compared to aspirin 140 μmol/L alone, against both ADP and collagen. Conclusion: The study favorably compares lycopene and aspirin with respect to their antiplatelet activities against ADP and collagen. Lycopene can be considered as a potential target for modifying the thrombotic and pro-inflammatory events associated with platelet activation. PMID:26997718

  13. Platelet aggregation but not activation and degranulation during the acute post-ischemic reperfusion phase in livers with no underlying disease

    PubMed Central

    van Golen, Rowan F.; Stevens, Katarzyna M.; Colarusso, Pina; Jaeschke, Hartmut; Heger, Michal

    2016-01-01

    Background Platelets and P-selectin (CD62P) play an unequivocal role in the pathology of hepatic ischemia/reperfusion (I/R) injury. Inhibition or knock-out of P-selectin or immunodepletion of platelets results in amelioration of post-ischemic inflammation, reduced hepatocellular damage, and improved survival. However, P-selectin expression on platelets and endothelial cells, which concurs with platelet activation, has never been clearly demonstrated in I/R-subjected livers. Aims To determine whether platelets become activated and degranulate in the acute phase of liver I/R and whether the platelets interact with neutrophils. Methods Hepatic I/R was induced in male C57BL/6J mice (N = 12) using 37.5-min ischemia time. Platelets, endothelial cells, and neutrophils were fluorescently labeled by systemic administration of non-blocking antibodies. Cell kinetics were monitored by intravital spinning disk confocal microscopy during 90 min of reperfusion. Image analysis and quantification was performed with dedicated software. Results Platelets adhered to sinusoids more extensively in post-ischemic livers compared to livers not subjected to I/R and formed aggregates, which occurred directly after ischemia. Platelets and endothelial cells did not express P-selectin in post-ischemic livers. There was no interaction between platelets and neutrophils. Conclusions Platelets aggregate but do not become activated and do not degranulate in post-ischemic livers. There is no platelet-neutrophil interplay during the early reperfusion phase in a moderate model of hepatic I/R injury. The mechanisms underlying the biological effects of platelets and P-selectin in this setting warrant further investigation. Relevance for patients I/R in surgical liver patients may compromise outcome due to post-ischemic oxidative stress and sterile inflammation. Both processes are mediated in part by platelets. Understanding platelet function during I/R is key to developing effective interventions for I

  14. Adenosine diphosphate-induced aggregation of human platelets in flow through tubes: III. Shear and extrinsic fibrinogen-dependent effects.

    PubMed

    Goldsmith, H L; Frojmovic, M M; Braovac, S; McIntosh, F; Wong, T

    1994-01-01

    The effect of shear rate and fibrinogen concentration on adenosine diphosphate-induced aggregation of suspensions of washed human platelets in Poiseuille flow at 23 degrees C was studied using a previously described double infusion technique and resistive particle counter size analysis. Using suspensions of multiple-centrifuged and -washed cells in Tyrodes-albumin [3 x 10(5) microliters-1; (17)] with [fibrinogen] from 0 to 1.2 microM, the rate and extent of aggregation with 0.7 microM ADP in Tyrodes-albumin were measured over a range of mean transit times from 0.2 to 43 s, and at mean tube shear rates, G, = 41.9, 335 and 1,335 s-1. As measured by the decrease in singlet concentration, aggregation at 1.2 microM fibrinogen increased with increasing G up to 1,335 s-1, in contrast to that previously reported in citrated plasma, in which aggregation reached a maximum at G = 335 s-1. Without added fibrinogen, there was no aggregation at G = 41.9 s-1; at G = 335 s-1, there was significant aggregation but with an initial lag time, aggregation increasing further at G = 1,335 s-1. Without added fibrinogen, aggregation was abolished at all G upon incubation with the hexapeptide GRGDSP, but was almost unaffected by addition of an F(ab')2 fragment of an antibody to human fibrinogen. Aggregation in the absence of added fibrinogen was also observed at 37 degrees C. The activation of the multiple-washed platelets was tested using flow cytometry with the fluorescently labelled monoclonal antibodies FITC-PAC1 and FITC-9F9. It was shown that 57% of single cells in unactivated PRT expressed maximal GPIIb-IIIa fibrinogen receptors (MoAb PAC1) and 54% expressed pre-bound fibrinogen (MoAb 9F9), with further increases on ADP activation. However, incubation with GRGDSP and the F(ab')2 fragment did not inhibit the prebound fibrinogen. Moreover, relatively unactivated cells (8% expressing receptor, 14% prebound fibrinogen), prepared from acidified cPRP by single centrifugation with 50 nM of

  15. Metalloproteases Affecting Blood Coagulation, Fibrinolysis and Platelet Aggregation from Snake Venoms: Definition and Nomenclature of Interaction Sites

    PubMed Central

    Kini, R. Manjunatha; Koh, Cho Yeow

    2016-01-01

    Snake venom metalloproteases, in addition to their contribution to the digestion of the prey, affect various physiological functions by cleaving specific proteins. They exhibit their activities through activation of zymogens of coagulation factors, and precursors of integrins or receptors. Based on their structure–function relationships and mechanism of action, we have defined classification and nomenclature of functional sites of proteases. These metalloproteases are useful as research tools and in diagnosis and treatment of various thrombotic and hemostatic conditions. They also contribute to our understanding of molecular details in the activation of specific factors involved in coagulation, platelet aggregation and matrix biology. This review provides a ready reference for metalloproteases that interfere in blood coagulation, fibrinolysis and platelet aggregation. PMID:27690102

  16. Evening primrose oil ameliorates platelet aggregation and improves cardiac recovery in myocardial-infarct hypercholesterolemic rats.

    PubMed

    Abo-Gresha, Noha M; Abel-Aziz, Eman Z; Greish, Sahar M

    2014-01-01

    Omega-6 polyunsaturated fatty acids (n-6 PUFA) are well known for their role in cardiovascular disease (CVD). We proposed that Evening prime rose oil (EPO) can improve the outcome of a heart with myocardial infarction (MI) in the presence of diet-induced hyperaggregability. This study was designed to examine its cholesterol lowering, antithrombotic and anti-inflammatory effects. High fat diet was administered for 4 weeks then MI was induced by isoproterenol (85 mg/kg/s.c./24 h). Treatment with EPO (5 or 10 gm/kg/day) for 6 weeks improved the electrocardiographic pattern, serum lipid profile, cardiac biomarkers as well as Platelet aggregation percent. We reported decreased serum level of TNF-α, IL-6 and COX-2 with attenuation of TNF-α and TGF-β in the cardiac homogenate. Moreover, histopathology revealed marked amelioration. Finally, we provide evidence that EPO improve cardiac recovery in hypercholesterolemic myocardial infarct rats. These effects are attributed to direct hypocholesterolemic effect and indirect effect on the synthesis of eicosanoids (prostaglandins, cytokines).

  17. [Palm oil derivatives with different concentration of palmitic acid and antioxidants. Effects upon plasmatic lipids and platelet aggregation].

    PubMed

    Scorza, T; Martucci, A; Torrealba de Ron, A T

    1999-03-01

    It was evaluated the effect of diet rich with cholesterol (0.1%) and different concentration of palmitic acid (16:0) and antioxidants (vitamin C, alpha tocopherol and retinol) upon plasmatic lipids and platelet aggregability in rabbits. The animals were distributed in three groups: I. Standard chow meal (Rp Conejarina) + cholesterol (chol) 0.1%; II. Standard chow meal + chol 0.1% + semipurified palm oil 10% (16:0 = 39.8%, oleic acid 48.7%, linoleic acid 11.4%, retinol 7.3 ug/dL, alpha tocopherol 157.6 ug/dL; III. Standard chow meal + chol 0.1% + crude palm oil 10% (16:0 = 45.3%, oleic acid 46.3%, linoleic acid 7.9%, retinol 96.4 ug/dL, alpha tocopherol 322.8 ug/dL). Monthly determination of plasmatic lipids were done (Enzymatic methods) and at ten months platelet aggregability with ADP, plasmatic vitamin C, retinol and, alpha tocopherol determination were done. Total plasmatic cholesterol (TC) and LDLc increased significantly in the three groups of animals. Significant differences between groups were not found. Platelet aggregability was lower in the animals fed with palmitic acid rich diet (groups II and III) (P = 0.002 and 0.001). Retinol, alpha tocopherol plasmatic concentrations revealed no significant differences. Vitamin C in the groups I was lower than groups II and III (P < 0.05 < 0.02). In this study hypercholesterolemic rabbits fed with rich diets (crude and semipurified) had lower platelet aggregability without changes in plasmatic lipids concentrations.

  18. ACE and platelet aggregation inhibitors from Tamarix hohenackeri Bunge (host plant of Herba Cistanches) growing in Xinjiang

    PubMed Central

    Xing, Yachao; Liao, Jing; Tang, Yingzhan; Zhang, Peng; Tan, Chengyu; Ni, Hui; Wu, Xueqin; Li, Ning; Jia, Xiaoguang

    2014-01-01

    Background: Tamarix hohenackeri Bunge is a salt cedar that grows widespread in the desert mountains in Xinjiang. T. hohenackeri has not been investigated earlier, although there are many reports of phytochemical work on other Tamarix species. Materials and Methods: To find out natural angiotensin-converting enzyme (ACE) inhibitor and platelet aggregation inhibitors, the bioactive extract (ethyl acetate [EtOAc] fraction) from the dried aerial parts of T. hohenackeri were investigated. The active fraction was purified by repeated column chromatography, including silica gel, Sephadex LH-20 column, medium-pressure liquid chromatography (MPLC) (polyamide column) and high-performance liquid chromatography (HPLC). The isolated major constituents were tested for their anti-platelet aggregation activity. Results: Bioassay-directed separation of the EtOAc fraction of the 70% ethanol extract from the air-dried aerial parts of T. hohenackeri led to the isolation of a new triterpenoid lactone (1), together with 13 known compounds (2-14). It was the first time to focus on screening bioactive constituents for this plant. The chemical structures were established on the basis of spectral data (ESI-MS and NMR). The results showed that the flavonoid compounds (7 and 8) and phenolic compounds (9, 10, 11, and 14) were potential ACE inhibitors. And the flavonoid compounds (5 and 7) showed significant anti-platelet aggregation activities. Conclusion: On the basis of the chemical and biological data, the material basis of ACE inhibitory activity for the active part was the phenolic constituents. However, the flavonoid compounds were responsible for the anti-platelet aggregation. The primary structure and activity relationship were also discussed respectively. PMID:24914275

  19. A noble function of BAY 11-7082: Inhibition of platelet aggregation mediated by an elevated cAMP-induced VASP, and decreased ERK2/JNK1 phosphorylations.

    PubMed

    Lee, Hyun-Sub; Kim, Sung Dae; Lee, Whi Min; Endale, Mehari; Kamruzzaman, S M; Oh, Won Jun; Cho, Jae Youl; Kim, Sang Keun; Cho, Hyun-Jeong; Park, Hwa-Jin; Rhee, Man Hee

    2010-02-10

    Platelets, though anucleated, possess several transcription factors, including NF-kappaB, that exert non-genomic functions regulating platelet activation. Since platelets have not only been recognized as central players of homeostasis, but also participated in pathological conditions such as thrombosis, atherosclerosis, and inflammation, we examined rat platelet NF-kappaB expression and evaluated the effects of anti-inflammatory drug BAY 11-7082, an inhibitor of NF-kappaB activation, in platelet physiology. Western blotting revealed that rat platelets express NF-kappaB. BAY 11-7082, dose dependently, inhibited collagen- or thrombin-induced-platelet aggregation. ATP release, TXB(2) formation, P-selectin expression, and intercellular Ca(2+) concentration activated by collagen were reduced in BAY 11-7082-treated platelets. BAY 11-7082 elevated intracellular levels of cAMP, but not cGMP, and its co-incubation with cAMP-activating agent (forskolin) or its hydrolyzing enzyme inhibitor (3-isobutyl-1-methylxanthine, IBMX), synergistically inhibited collagen-induced-platelet aggregation. In addition, vasodilator-stimulated-phosphoprotein (VASP) phosphorylation was enhanced in BAY 11-7082-treated platelets, which was partially inhibited by a protein kinase A (PKA) inhibitor, H-89. Moreover, while p38 mitogen-activated protein kinase (MAPK) was not affected, BAY 11-7082 attenuated c-Jun N-terminal kinase 1 (JNK1) and extracellular-signal-regulated protein kinase 2 (ERK2) phosphorylations. In conclusion, BAY 11-7082 inhibits platelet activation, granule secretion, and aggregation, and that this effect is mediated by inhibition of JNK1 and ERK2 phosphorylations, and partially by stimulation of cAMP-dependent PKA VASP phosphorylation. The ability of BAY 11-7082 to inhibit platelet function might be relevant in cases involving aberrant platelet activation where the drug is considered as anti-atherothrombosis, and anti-inflammatory therapy.

  20. A Novel Direct Factor Xa Inhibitory Peptide with Anti-Platelet Aggregation Activity from Agkistrodon acutus Venom Hydrolysates.

    PubMed

    Chen, Meimei; Ye, Xiaohui; Ming, Xin; Chen, Yahui; Wang, Ying; Su, Xingli; Su, Wen; Kong, Yi

    2015-01-01

    Snake venom is a natural substance that contains numerous bioactive proteins and peptides, nearly all of which have been identified over the last several decades. In this study, we subjected snake venom to enzymatic hydrolysis to identify previously unreported bioactive peptides. The novel peptide ACH-11 with the sequence LTFPRIVFVLG was identified with both FXa inhibition and anti-platelet aggregation activities. ACH-11 inhibited the catalytic function of FXa towards its substrate S-2222 via a mixed model with a Ki value of 9.02 μM and inhibited platelet aggregation induced by ADP and U46619 in a dose-dependent manner. Furthermore, ACH-11 exhibited potent antithrombotic activity in vivo. It reduced paralysis and death in an acute pulmonary thrombosis model by 90% and attenuated thrombosis weight in an arterio-venous shunt thrombosis model by 57.91%, both at a dose of 3 mg/kg. Additionally, a tail cutting bleeding time assay revealed that ACH-11 did not prolong bleeding time in mice at a dose of 3 mg/kg. Together, our results reveal that ACH-11 is a novel antithrombotic peptide exhibiting both FXa inhibition and anti-platelet aggregation activities, with a low bleeding risk. We believe that it could be a candidate or lead compound for new antithrombotic drug development. PMID:26035670

  1. The saliva proteome of the blood-feeding insect Triatoma infestans is rich in platelet-aggregation inhibitors

    NASA Astrophysics Data System (ADS)

    Charneau, Sébastien; Junqueira, Magno; Costa, Camila M.; Pires, Daniele L.; Fernandes, Ellen S.; Bussacos, Ana C.; Sousa, Marcelo V.; Ricart, Carlos André O.; Shevchenko, Andrej; Teixeira, Antonio R. L.

    2007-12-01

    The saliva of the bloodsucking bug Triatoma infestans vector of Chagas disease contains an anti-hemostatic molecular cocktail that prevents coagulation, vasoconstriction and platelet aggregation in a vertebrate prey. In order to characterize T. infestans saliva proteome, we separated the secreted saliva by two-dimensional gel electrophoresis (2-DE). More than 200 salivary proteins were detected on the 2-DE map, mainly in the alkaline region. By nanoLC-MS/MS analysis using a LTQ-Orbitrap equipment followed by a combination of conventional and sequence-similarity searches, we identified 58 main protein spots. Most of such proteins possess potential blood-feeding associated functions, particularly anti-platelet aggregation proteins belonging to lipocalin and apyrase families. The saliva protein composition indicates a highly specific molecular mechanism of early response to platelet aggregation. This first proteome analysis of the T. infestans secreted saliva provides a basis for a better understanding of this fluid protein composition highly directed to counterpart hemostasis of the prey, thus promoting the bug's blood-feeding.

  2. Acetyl eugenol, a component of oil of cloves (Syzygium aromaticum L.) inhibits aggregation and alters arachidonic acid metabolism in human blood platelets.

    PubMed

    Srivastava, K C; Malhotra, N

    1991-01-01

    In continuation of our studies with the oil of cloves--a common kitchen spice and a crude drug for home medicine--we have isolated yet another active component identified as acetyl eugenol (AE); the earlier reported active component being eugenol. The isolated material (IM) was found to be a potent platelet inhibitor; IM abolished arachidonate (AA)-induced aggregation at ca. 12 microM, a concentration needed to abolish the second phase of adrenaline-induced aggregation. Chemically synthesized acetyl eugenol showed similar effects on AA- and adrenaline-induced aggregation. A dose-dependent inhibition of collagen-induced aggregation was also observed. AE did not inhibit either calcium ionophore A23187- or thrombin-induced aggregation. Studies on aggregation and ATP release were done using whole blood (WB). AA-induced aggregation in WB was abolished at 3 micrograms/ml (14.6 microM) which persisted even after doubling the concentration of AA. ATP release was inhibited. Inhibition of aggregation appeared to be mediated by a combination of two effects: reduced formation of thromboxane and increased generation of 12-lipoxygenase product (12-HPETE). These effects were observed by exposing washed platelets to (14C)AA or by stimulating AA-labelled platelets with ionophore A23187. Acetyl eugenol inhibited (14C)TxB2 formation in AA-labelled platelets on stimulation with thrombin. AE showed no effect on the incorporation of AA into platelet phospholipids. PMID:2011614

  3. Effect of Vitamin C Supplementation on Platelet Aggregation and Serum Electrolytes Levels in Streptozotocin-Induced Diabetes Mellitus in Rats.

    PubMed

    Owu, Daniel U; Nwokocha, Chukwuemeka R; Ikpi, Daniel E; Ogar, Emmanuel I

    2016-01-01

    Diabetes mellitus (DM) is a disease condition characterised by hyperglycemia; free radical and abnormalhaematological indices. Vitamin C can reduce free radical generation and ameliorate adverse conditions of diabetes mellitus.The aim of the present study is to investigate the effect of vitamin C on platelet aggregation and electrolyte levels in Type 1DM. Male Wistar rats were divided into four groups namely control, DM, DM +Vitamin C and Vitamin C groups. Rats weremade diabetic with a single dose of streptozotocin (65 mg/kg) intraperitoneally. Vitamin C was administered orally todiabetic and normal rats at 200 mg/kg body weight for 28 days. Blood samples were analyzed for hematological parameters,platelet aggregation, and serum electrolyte levels. Blood glucose in DM+ Vitamin C group (9.9 ± 1.8 mmol/L) wassignificantly reduced (p<0.01) compared to DM group (32.2 ± 2.1 mmol/L) and significantly higher (p<0.05) than control(4.4 ± 0.8 mmol/L). Haemoglobin (Hb) concentration in DM group (12 ± 0.1 g/dL) was significantly reduced (p<0.01) whencompared with control groups (14 ± 0.24 g/dL) and significantly increased (p<0.05) in the DM+vitamin C group (13.5 ± 0.5g/dL) compared with the diabetic group. The mean corpuscular volume values in DM (68.66 ± 0.5 fL) and DM+vitamin Cgroups (68.11 ± 0.4 fL) were significantly higher (p<0.01) than the control (59.49 ± 0.5fL). Platelet count in DM group (523± 8.5 x109/L) was significantly raised (p<0.01) when compared to control (356 ± 6.2 x109/L) and significantly reduced(p<0.01) in DM+ vitamin C-treated group (385 ± 7.8 x109/L) compared with DM group. Platelet aggregation and serumsodium/potassium ratios was significantly reduced (p<0.01) in DM+vitamin C compared with DM group. These resultssuggest that oral vitamin C administration increases haemoglobin, reduced plasma glucose level, platelet count, serumsodium/potassium ion ratio and inhibits platelet aggregation in streptozotocin-induced DM in rats. PMID:27574765

  4. Parnaparin, a low-molecular-weight heparin, prevents P-selectin-dependent formation of platelet-leukocyte aggregates in human whole blood.

    PubMed

    Maugeri, Norma; Di Fabio, Giovannina; Barbanti, Miriam; de Gaetano, Giovanni; Donati, Maria Benedetta; Cerletti, Chiara

    2007-06-01

    Parnaparin, a low-molecular-weight heparin (LMWH), prevents platelet activation and interaction with polymorphonuclear leukocyte (PMN) in a washed cell system. The in-vitro effect of parnaparin was studied here on platelet-PMN aggregates formed with more physiologic approaches in whole blood, in parallel with unfractionated heparin and enoxaparin, another LMWH. Citrated blood from healthy subjects was stimulated: i) from passage through the "Platelet Function Analyzer" (PFA-100), a device that exposes blood to standardized high shear flow through collagen/ADP cartridges; ii) by collagen and ADP (2 and 50 mug/ml, respectively) added in combination under stirring in an aggregometer cuvette; iii) with recombinant Tissue Factor, to generate thrombin concentrations able to activate platelets without inducing blood clotting, or iv) the Thrombin Receptor Activating Peptide-6 (TRAP-6). Platelet P-selectin and platelet-PMN aggregates were measured by flow cytometry upon stimulation of blood. Fibrinogen binding to platelets and markers of PMN activation were also detected. Platelet P-selectin expression and platelet-PMN aggregate formation were induced in all four activation conditions tested. Parnaparin prevented in a concentration-dependent manner (0.3-0.8 IUaXa/ml) the expression of P-selectin and the formation of mixed aggregates, while the two reference heparin preparations had a much weaker effect. Platelet fibrinogen binding and PMN activation markers (fibrinogen binding, CD11b and CD40) were also prevented by parnaparin. These data extend in more physiological systems of platelet activation, the anti-inflammatory profile of parnaparin, previously reported in washed cells. The greater effect of parnaparin, as compared to the reference heparins, could be due to chemico-physical differences possibly unrelated to their anticoagulant effect. PMID:17549299

  5. Differences in Whole Blood Platelet Aggregation at Baseline and in Response to Aspirin and Aspirin Plus Clopidogrel in Patients With Versus Without Chronic Kidney Disease.

    PubMed

    Jain, Nishank; Li, Xilong; Adams-Huet, Beverley; Sarode, Ravi; Toto, Robert D; Banerjee, Subhash; Hedayati, S Susan

    2016-02-15

    Thrombotic events while receiving antiplatelet agents (APAs) are more common in subjects with versus without chronic kidney disease (CKD). Data on antiplatelet effects of APA in CKD are scarce and limited by lack of baseline platelet function before APA treatment. We hypothesized subjects with stages 4 to 5 CKD versus no CKD have greater baseline platelet aggregability and respond poorly to aspirin and clopidogrel. In a prospective controlled study, we measured whole blood platelet aggregation (WBPA) in 28 CKD and 16 non-CKD asymptomatic stable outpatients not on APA, frequency-matched for age, gender, obesity, and diabetes mellitus. WBPA was remeasured after 2 weeks of each aspirin and aspirin plus clopidogrel. The primary outcome was percent inhibition of platelet aggregation (IPA) from baseline. The secondary outcome was residual platelet aggregability (RPA; proportion with <50% IPA). Baseline platelet aggregability was similar between groups except adenosine diphosphate-induced WBPA, which was higher in CKD versus non-CKD; median (interquartile range) = 13.5 (9.5 to 16.0) versus 9.0 (6.0 to 12.0) Ω, p = 0.007. CKD versus non-CKD participants had lower clopidogrel-induced IPA, 38% versus 72%, p = 0.04. A greater proportion of CKD versus non-CKD participants had RPA after clopidogrel treatment (56% vs 8.3%, p = 0.01). There were no significant interactions between CKD and the presence of cytochrome P450 2C19 polymorphisms for platelet aggregability in clopidogrel-treated participants. In conclusion, CKD versus non-CKD subjects exhibited similar platelet aggregation at baseline, similar aspirin effects and greater RPA on clopidogrel, which was independent of cytochrome P450 2C19 polymorphisms. PMID:26725101

  6. Differences in Whole Blood Platelet Aggregation at Baseline and in Response to Aspirin and Aspirin Plus Clopidogrel in Patients With Versus Without Chronic Kidney Disease.

    PubMed

    Jain, Nishank; Li, Xilong; Adams-Huet, Beverley; Sarode, Ravi; Toto, Robert D; Banerjee, Subhash; Hedayati, S Susan

    2016-02-15

    Thrombotic events while receiving antiplatelet agents (APAs) are more common in subjects with versus without chronic kidney disease (CKD). Data on antiplatelet effects of APA in CKD are scarce and limited by lack of baseline platelet function before APA treatment. We hypothesized subjects with stages 4 to 5 CKD versus no CKD have greater baseline platelet aggregability and respond poorly to aspirin and clopidogrel. In a prospective controlled study, we measured whole blood platelet aggregation (WBPA) in 28 CKD and 16 non-CKD asymptomatic stable outpatients not on APA, frequency-matched for age, gender, obesity, and diabetes mellitus. WBPA was remeasured after 2 weeks of each aspirin and aspirin plus clopidogrel. The primary outcome was percent inhibition of platelet aggregation (IPA) from baseline. The secondary outcome was residual platelet aggregability (RPA; proportion with <50% IPA). Baseline platelet aggregability was similar between groups except adenosine diphosphate-induced WBPA, which was higher in CKD versus non-CKD; median (interquartile range) = 13.5 (9.5 to 16.0) versus 9.0 (6.0 to 12.0) Ω, p = 0.007. CKD versus non-CKD participants had lower clopidogrel-induced IPA, 38% versus 72%, p = 0.04. A greater proportion of CKD versus non-CKD participants had RPA after clopidogrel treatment (56% vs 8.3%, p = 0.01). There were no significant interactions between CKD and the presence of cytochrome P450 2C19 polymorphisms for platelet aggregability in clopidogrel-treated participants. In conclusion, CKD versus non-CKD subjects exhibited similar platelet aggregation at baseline, similar aspirin effects and greater RPA on clopidogrel, which was independent of cytochrome P450 2C19 polymorphisms.

  7. Chemical synthesis of echistatin, a potent inhibitor of platelet aggregation from Echis carinatus: synthesis and biological activity of selected analogs.

    PubMed

    Garsky, V M; Lumma, P K; Freidinger, R M; Pitzenberger, S M; Randall, W C; Veber, D F; Gould, R J; Friedman, P A

    1989-06-01

    Echistatin, a polypeptide from the venom of the saw-scaled viper, Echis carinatus, containing 49 amino acids and 4 cystine bridges was synthesized by solid-phase methodology in 4% yield. In the final step, air oxidation of the octahydroderivative was found to be optimal at pH 8. The synthetic product was shown to be physically and biologically indistinguishable from native material. It inhibits fibrinogen-dependent platelet aggregation stimulated by ADP with IC50 = 3.3 x 10(-8) M and also prevents aggregation initiated by thrombin, epinephrine, collagen, or platelet-activating factor. Reduction of purified synthetic echistatin to octahydroechistatin with dithiothreitol followed by air oxidation regenerated homogeneous echistatin in quantitative yield. This highly specific refolding strongly suggests that the linear sequence of octahydroechistatin contains all of the information that is required for the proper folding of the peptide. The sequence Arg24-Gly-Asp of echistatin occurs also in adhesive glycoproteins that bind to the platelet fibrinogen receptor--a heterodimeric complex composed of glycoproteins IIb and IIIa. In an effort to evaluate the role of this putative binding site we have synthesized analogs of echistatin with substitution of Arg-24. Replacement with ornithine-24 (Orn-24) resulted in an analog having a platelet aggregation inhibitory activity with IC50 = 1.05 x 10(-7) M. Substitution with Ala-24 gave IC50 = 6.1 x 10(-7) M. The inhibitory activity of the corresponding short sequence analogs Arg-Gly-Asp-Phe (IC50 = 6 x 10(-6) M), Orn-Gly-Asp-Phe (IC50 = 1.3 x 10(-4) M), and Ala-Gly-Asp-Phe (IC50 = 5.0 x 10(-4) M) was also determined. These results suggest that arginine plays a more important role in the binding of the tetrapeptide than in that of echistatin. PMID:2726764

  8. Synthesis of analogues of gingerol and shogaol, the active pungent principles from the rhizomes of Zingiber officinale and evaluation of their anti-platelet aggregation effects.

    PubMed

    Shih, Hung-Cheng; Chern, Ching-Yuh; Kuo, Ping-Chung; Wu, You-Cheng; Chan, Yu-Yi; Liao, Yu-Ren; Teng, Che-Ming; Wu, Tian-Shung

    2014-01-01

    The present study was aimed at discovering novel biologically active compounds based on the skeletons of gingerol and shogaol, the pungent principles from the rhizomes of Zingiber officinale. Therefore, eight groups of analogues were synthesized and examined for their inhibitory activities of platelet aggregation induced by arachidonic acid, collagen, platelet activating factor, and thrombin. Among the tested compounds, [6]-paradol (5b) exhibited the most significant anti-platelet aggregation activity. It was the most potent candidate, which could be used in further investigation to explore new drug leads.

  9. A monoclonal antibody directed against a granule membrane glycoprotein (GMP-140/PADGEM, P-selectin, CD62P) inhibits ristocetin-induced platelet aggregation.

    PubMed

    Boukerche, H; Ruchaud-Sparagano, M H; Rouen, C; Brochier, J; Kaplan, C; McGregor, J L

    1996-02-01

    P-selectin (also called CD62, GMP-140, PADGEM, CD62P) is a recently described member of a family of vascular adhesion receptors expressed by activated platelets and endothelial cells that are involved in leucocyte cell adhesion. The aim of this study was to characterize a new monoclonal antibody (LYP7) directed against activated human blood platelets that inhibits ristocetin-induced platelet aggregation. Immunoadsorbent affinity chromatography and immunoprecipitation studies showed that LYP7 (IgG1) bound a surface-labelled glycoprotein (GP) which changed its apparent molecular mass (M(r)) on reduction from 138 kD (situated below GPIIb) to 148 kD (above GPIIb alpha). LYP7 and S12, a monoclonal antibody directed against P-selectin immunoprecipitated the same band. Using ELISA assay, purified P-selectin was shown to bind LYP7 and S12 monoclonal antibodies. Binding sites of 125I-labelled LYP7, which was greatly increased on thrombin-stimulated (2 U/ml) washed platelets (10825 +/- 2886, mean +/- SD) Kd = 1.5 +/- 0.5 nM) compared to resting platelets (2801 +/- 1278, mean +/- SD) (Kd = 1.5 +/- 0.6 nM), was found to be normal on thrombin-stimulated platelets taken from a patient with grey platelet syndrome or a patient with Glanzmann thrombasthenia. LYP7 (IgG1, F(ab')2 or Fab fragments) inhibited ristocetin-induced platelet aggregation of platelets in a dose-dependent fashion without affecting the binding of von Willebrand (vWf) factor. However, agglutination of formaldehyde-fixed platelets induced by ristocetin was not affected by monoclonal antibody LYP7. In addition, the binding of thrombin-activated platelets to neutrophils was inhibited by monoclonal antibody LYP7. These results strongly suggest that P-selectin, by promoting cell-cell contact, may play an active role in platelet-platelet interactions. PMID:8603015

  10. CYP-independent inhibition of platelet aggregation in rabbits by a mixed disulfide conjugate of clopidogrel.

    PubMed

    Zhang, H; Lauver, D A; Hollenberg, P F

    2014-12-01

    Dual antiplatelet therapy with clopidogrel and aspirin has been the standard of care in the United States for patients with acute coronary syndromes (ACS) and/or undergoing percutaneous coronary interventions (PCI). However, the effectiveness of clopidogrel varies significantly among different sub-populations due to inter-individual variability. In this study we examined the antiplatelet potential of a novel mixed disulfide conjugate of clopidogrel with the aim to overcome the inter-individual variability. In the metabolic studies using human liver microsomes and cDNA-expressed P450s, we confirmed that multiple P450s are involved in the bioactivation of 2-oxoclopidogrel to H4, one of the diastereomers of the pharmacologically active metabolite (AM) possessing antiplatelet activity. Results from kinetic studies demonstrated that 2C19 is the most active in converting 2-oxoclopidogrel to H4 with a catalytic efficiency of 0.027 µM⁻¹min⁻¹ in the reconstituted system. On the basis of this finding, we were able to biosynthesise the conjugate of clopidogrel with 3-nitropyridine-2-thiol, referred to as clopNPT, and examined its antiplatelet activity in male New Zealand white rabbits. After administration as intravenous bolus at 2 mg/kg, the clopNPT conjugate was rapidly converted to the AM leading to the inhibition of platelet aggregation (IPA). Analyses of the blood samples drawn at various time points showed that intravenous administration of clopNPT led to ~70% IPA within 1 hour and the IPA persisted for more than 3 hours. Since the antiplatelet activity of clopNPT does not require bioactivation by P450s, the mixed disulfide conjugate of clopidogrel has the potential to overcome the inter-individual variability in clopidogrel therapy. PMID:25230737

  11. The effects of the decaffeination of coffee samples on platelet aggregation in hyperlipidemic rats.

    PubMed

    Silvério, Alessandra dos Santos Danziger; Pereira, Rosemary Gualberto Fonseca Alvarenga; Lima, Adriene Ribeiro; Paula, Fernanda Borges de Araújo; Rodrigues, Maria Rita; Baldissera, Lineu; Duarte, Stella Maris da Silveira

    2013-09-01

    The effect of coffee on cardiovascular diseases is still controversial. It is known that the process of decaffeination may influence the chemical constitution and, therefore, the biological effects of coffee. This study thus evaluated the effects of decaffeination on the levels of total phenols and chlorogenic acids in Coffea arabica L. samples, as well as the effects of ingesting both integral and decaffeinated coffee on the lipid profile and hemostatic and hematological parameters in normal and hyperlipidemic rats. Samples of integral and decaffeinated lyophilized coffee (Coffea arabica L., planted in Brazil) were used for chemical analysis (total phenols, chlorogenic acid and caffeine contents). For the bioassays, coffee beverages were prepared with non-lyophilized samples (10% w/v) and were filtered and administered to animals by gavage (7.2 mL/kg/day) over 30 days. On the 31st day after beginning the treatment with coffee beverages, hyperlipidemia was induced to the animals by administering Triton WR-1339 (300 mg/kg body weight). On day 32, blood was taken to determine the lipid profile, platelet aggregation, prothrombin time, partially activated thromboplastin time and hemogram. The contents of both phenolic compounds and chlorogenic acid in the integral coffee beverage were significantly lower than those in the decaffeinated coffee beverage. The animals treated with Triton WR-1339 presented a mixed hyperlipidemia. Although the decaffeination process caused a relative increase in total phenols and chlorogenic acids, the coffee drinks were unable to change the lipid profile or the hemostatic and hematological parameters in the studied animals. PMID:23780748

  12. The effects of the decaffeination of coffee samples on platelet aggregation in hyperlipidemic rats.

    PubMed

    Silvério, Alessandra dos Santos Danziger; Pereira, Rosemary Gualberto Fonseca Alvarenga; Lima, Adriene Ribeiro; Paula, Fernanda Borges de Araújo; Rodrigues, Maria Rita; Baldissera, Lineu; Duarte, Stella Maris da Silveira

    2013-09-01

    The effect of coffee on cardiovascular diseases is still controversial. It is known that the process of decaffeination may influence the chemical constitution and, therefore, the biological effects of coffee. This study thus evaluated the effects of decaffeination on the levels of total phenols and chlorogenic acids in Coffea arabica L. samples, as well as the effects of ingesting both integral and decaffeinated coffee on the lipid profile and hemostatic and hematological parameters in normal and hyperlipidemic rats. Samples of integral and decaffeinated lyophilized coffee (Coffea arabica L., planted in Brazil) were used for chemical analysis (total phenols, chlorogenic acid and caffeine contents). For the bioassays, coffee beverages were prepared with non-lyophilized samples (10% w/v) and were filtered and administered to animals by gavage (7.2 mL/kg/day) over 30 days. On the 31st day after beginning the treatment with coffee beverages, hyperlipidemia was induced to the animals by administering Triton WR-1339 (300 mg/kg body weight). On day 32, blood was taken to determine the lipid profile, platelet aggregation, prothrombin time, partially activated thromboplastin time and hemogram. The contents of both phenolic compounds and chlorogenic acid in the integral coffee beverage were significantly lower than those in the decaffeinated coffee beverage. The animals treated with Triton WR-1339 presented a mixed hyperlipidemia. Although the decaffeination process caused a relative increase in total phenols and chlorogenic acids, the coffee drinks were unable to change the lipid profile or the hemostatic and hematological parameters in the studied animals.

  13. Attenuation of Thrombosis by Crude Rice (Oryza sativa) Bran Policosanol Extract: Ex Vivo Platelet Aggregation and Serum Levels of Arachidonic Acid Metabolites

    PubMed Central

    Ismail, Maznah; Tohit, Eusni Rahayu Mohd; Abdullah, Rasedee; Zhang, Yi-Da

    2016-01-01

    Background. Vascular occlusion or thrombosis was often attributed to uncontrolled platelet activation. Influence of sugarcane policosanol extract on platelet was reported but little was known of rice bran policosanol, particularly its mechanisms of actions on platelet activities. Objective. Antiplatelet mechanisms of rice bran policosanol extract (RBE) were studied using hyperlipidemic Sprague Dawley rats. Ex vivo platelet aggregation, platelet count (PC), bleeding time (BT), and coagulation time were assayed. Serum eicosanoids and other aggregation-related metabolites levels were quantified. Design. Rats were divided into 6 groups for comparisons (vehicle control Tween 20/H2O, high dose policosanol 500 mg/kg, middle dose policosanol 250 mg/kg, low dose policosanol 100 mg/kg, and positive control aspirin 30 mg/kg). Results. Low dose 100 mg/kg of RBE inhibited aggregation by 42.32 ± 4.31% and this was comparable with the effect of 30 mg/kg aspirin, 43.91 ± 5.27%. Results showed that there were no significant differences in PC, BT, and coagulation time among various groups after RBE treatment. Serum thromboxane A2 was attenuated while prostacyclin level increased upon RBE treatment. Conclusions. RBE reduced ex vivo ADP-induced platelet aggregation without giving adverse effects. No changes in full blood count suggested that rice bran policosanol did not disturb biological blood cell production and destruction yet it reduced aggregation through different mechanisms. PMID:27800004

  14. Ezetimibe's effect on platelet aggregation and LDL tendency to peroxidation in hypercholesterolaemia as monotherapy or in addition to simvastatin

    PubMed Central

    Hussein, Osamah; Minasian, LiLia; Itzkovich, Yaroslav; Shestatski, Karina; Solomon, Lizora; Zidan, Jamal

    2008-01-01

    AIMS To investigate the effect of lowering low-density lipoprotein-cholesterol (LDL-C) on platelet aggregation and LDL tendency to peroxidation by ezetimibe alone or with simvastatin in hypercholesterolaemia. METHODS Sixteen patients with LDL-C >3.4 mmol l−1 received ezetimibe for 3 months (Part I). Twenty-two patients on fixed simvastatin dose with LDL-C >2.6 mmol l−1 were enrolled (Part II). Part II patients continued simvastatin treatment 20 mg day−1 for 6 weeks, then received 20 mg day−1 simvastatin combined with ezetimibe 10 mg day−1 for another 6 weeks. The tendency of LDL to peroxidation measured by lag time in minutes required for initiation of LDL oxidation and by LDL oxidation at maximal point (plateau) was measured before and after ezetimibe treatment. RESULTS Part I: Ezetimibe 10 mg daily for 3 months decreased plasma LDL-C level 16% (P = 0.002), prolonged lag time to LDL oxidation from 144 ± 18 min to 195 ± 16 min (P < 0.001), decreasing maximal aggregation from 83 ± 15% to 60 ± 36% (P = 0.04). Part II: Serum level LDL-C decreased 23% (P = 0.02) and lag time in minutes to LDL oxidation was prolonged from 55.9 ± 16.5 to 82.7 ± 11.6 (P < 0.0001) using combined simvastatin–ezetimibe therapy. There were no differences in platelet aggregation. CONCLUSIONS Ezetimibe was associated with decreased platelet aggregation and LDL tendency to peroxidation. Treatment with ezetimibe in addition to simvastatin has an additive antioxidative effect on LDL. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Statins demonstrate a pleiotropic effect which contributes beyond the hypocholesterolaemic effect to prevent atherosclerosis. WHAT THIS STUDY ADDS Ezetimibe has an antioxidative effect when given as monotherapy or as an add-on to the statin, simvastatin. PMID:18241285

  15. Metabolomic investigation of the anti-platelet aggregation activity of ginsenoside Rk₁ reveals attenuated 12-HETE production.

    PubMed

    Ju, Hyun Kyoung; Lee, Jin Gyun; Park, Mi Kyung; Park, So-Jung; Lee, Chang Hoon; Park, Jeong Hill; Kwon, Sung Won

    2012-10-01

    Comprehensive metabolomics analysis is an effective method of measuring metabolite levels in the body following administration of a pharmaceutical compound and can allow for monitoring of the effects of the compound or assessment of appropriate treatment options for individual patients. In the present metabolomics study, samples pretreated with antiplatelet compounds were extracted and subjected to ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry. The acquired data were processed using peak clustering and evaluated by partial least-squares (PLS) and orthogonal projections to latent structures discriminant analyses (OPLS-DA). As a result, meaningful endogenous metabolites, namely eicosanoids and thromboxane B(2) (TXB(2)), were identified. TXB(2), a key element in platelet aggregation, was decreased upon ginsenoside Rk(1) treatment via inhibition of cyclooxygenase (COX) activity. One of the arachidonic acid (AA) metabolites, 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), was decreased significantly in the ginsenoside Rk(1)-treated platelets compared to the AA-induced group. In the mechanism study of ginsenoside Rk(1), a strong linkage to intracellular calcium levels, which induce platelet activation, was found. Additionally, the translocation of 12-LOX from cytosol to membrane, which is related with the intracellular calcium levels, was determined. Therefore, a decreased 12-HETE level induced by ginsenoside Rk(1) on antiplatelet aggregation is related to 12-LOX translocation resulting from decreased Ca(2+) levels. This study shows that global metabolomic analysis has potential for use in understanding the biological behavior of antiplatelet drugs. PMID:22873173

  16. Platelet-Monocyte Aggregates and C-Reactive Protein are Associated with VTE in Older Surgical Patients.

    PubMed

    Shih, Lauren; Kaplan, David; Kraiss, Larry W; Casper, T Charles; Pendleton, Robert C; Peters, Christopher L; Supiano, Mark A; Zimmerman, Guy A; Weyrich, Andrew S; Rondina, Matthew T

    2016-06-07

    Emerging evidence implicates platelets as key mediators of venous thromboembolism (VTE). Nevertheless, the pathways by which platelets and circulating procoagulant proteins synergistically orchestrate VTE remain incompletely understood. We prospectively determined whether activated platelets and systemic procoagulant factors were associated with VTE in 32 older orthopedic surgery patients. Circulating platelet-monocyte aggregates (PMAs), p-selectin expression (P-SEL), and integrin αIIbβ3 activation (PAC-1 binding) were assessed pre-operatively and 24 hours post-operatively. The proinflammatory and procoagulant molecule C-reactive protein (CRP), which induces PMA formation in vitro, along with plasma d-dimer and fibrinogen levels were also measured. The primary outcome was VTE occurring within 30 days post-operatively. Overall, 40.6% of patients developed VTE. Patients with VTE had a significant increase in circulating PMAs and CRP post-operatively, compared to those without VTE. Changes in PMA and CRP in VTE patients were significantly correlated (r(2) = 0.536, p = 0.004). In contrast, P-SEL expression and PAC-1 binding, fibrinogen levels, and d-dimers were not associated with VTE. This is the first study to identify that increased circulating PMAs and CRP levels are early markers associated with post-surgical VTE. Our findings also provide new clinical evidence supporting the interplay between PMAs and CRP in patients with VTE.

  17. Lyn and PECAM-1 function as interdependent inhibitors of platelet aggregation.

    PubMed

    Ming, Zhangyin; Hu, Yu; Xiang, Jizhou; Polewski, Peter; Newman, Peter J; Newman, Debra K

    2011-04-01

    Inhibition of platelet responsiveness is important to control pathologic thrombus formation. Platelet-endothelial cell adhesion molecule-1 (PECAM-1) and the Src family kinase Lyn inhibit platelet activation by the glycoprotein VI (GPVI) collagen receptor; however, it is not known whether PECAM-1 and Lyn function in the same or different inhibitory pathways. In these studies, we found that, relative to wild-type platelets, platelets derived from PECAM-1-deficient, Lyn-deficient, or PECAM-1/Lyn double-deficient mice were equally hyperresponsive to stimulation with a GPVI-specific agonist, indicating that PECAM-1 and Lyn participate in the same inhibitory pathway. Lyn was required for PECAM-1 tyrosine phosphorylation and subsequent binding of the Src homology 2 domain-containing phosphatase-2, SHP-2. These results support a model in which PECAM-1/SHP-2 complexes, formed in a Lyn-dependent manner, suppress GPVI signaling. PMID:21297004

  18. Purification and characterization of L-amino acid oxidase from king cobra (Ophiophagus hannah) venom and its effects on human platelet aggregation.

    PubMed

    Li, Z Y; Yu, T F; Lian, E C

    1994-11-01

    Venoms of several snake species contain large amounts of L-amino acid oxidase but its effects on human plasma coagulation and platelet aggregation have not been explored. We have purified L-amino acid oxidase from king cobra venom through CM-Sephadex C-25, Sephadex G-100 and DEAE Sephadex A-50 chromatographies. The purified enzyme has a mol. wt of 135,000 as determined by gel filtration and 65,000 by SDS-PAGE under non-reducing and reducing conditions. Incubation of plasma with L-amino acid oxidase at 200 micrograms/ml did not affect prothrombin time, activated partial thromboplastin time, or thrombin time. Upon addition of L-amino acid oxidase, platelets in platelet-rich plasma were aggregated. The enzyme-induced aggregation was abolished by catalase. The aggregation was also inhibited by indomethacin, aspirin, ethylenediaminetetraacetate, sodium nitroprusside, prostaglandin E1, mepacrine and verapamil, but not by heparin, hirudin, creatine phosphate/creatine phosphokinase or antimycin/2-deoxy-D-glucose. These results suggest that L-amino acid oxidase induces human platelet aggregation through the formation of H2O2, and subsequent thromboxane A2 synthesis requiring Ca2+ but independent of ADP release. The platelet aggregation caused by L-amino acid oxidase is likely to contribute to toxicity inflicted by cobra venom.

  19. Relation between clopidogrel active metabolite levels and different platelet aggregation methods in patients receiving clopidogrel and aspirin.

    PubMed

    Liang, Yan; Johnston, Marilyn; Hirsh, Jack; Pare, Guillaume; Li, Chunjian; Mehta, Shamir; Teo, Koon K; Sloane, Debi; Yi, Qilong; Zhu, Jun; Eikelboom, John W

    2012-11-01

    Clopidogrel is a prodrug that undergoes bioconversion via cytochrome P450 system to form an active metabolite (AM) that binds to the platelet ADP receptor. The antiplatelet effect of clopidogrel is commonly assessed by measuring the aggregatory response to 5 μM ADP by light transmission aggregation (LTA) or multiple electrode aggregometry (MEA) or by the vasodilator-stimulated phosphoprotein platelet reactivity index (VASP-PRI). To determine which of these three tests of platelet ADP receptor pathway inhibition most closely correlates with clopidogrel AM levels. We analyzed blood samples from 82 patients with coronary artery disease who were randomized to receive double-dose or standard dose clopidogrel for 2 weeks. We measured peak clopidogrel AM levels, platelet aggregation in response to ADP and VASP-PRI on days 1, and repeated all the measures on days 7 and 14. Linear regression analysis was used to examine the correlation between clopidogrel AM and LTA, MEA and VASP-PRI. Bland-Altman plots were used to explore the agreement between tests of the antiplatelet effects of clopidogrel. Clopidogrel AM on day 1 correlated most closely with VASP-PRI (r = -0.5767) and demonstrated weaker correlations with LTA (r = -0.4656) and MEA (r = -0.3384) (all p < 0.01). Intra-class correlation (ICC) between VASP-PRI and LTA was 0.6446; VASP-PRI and MEA was 0.4720; and LTA and MEA was 0.4693. Similar results were obtained on days 7 and 14. Commonly used pharmacodynamic measures of clopidogrel response are only moderately correlated with clopidogrel AM levels and may not be suitable to measure the adequacy of clopidogrel therapy. PMID:22797934

  20. The inhibitory mechanism of crude saponin fraction from Korean Red Ginseng in collagen-induced platelet aggregation

    PubMed Central

    Jeon, Bo Ra; Kim, Su Jung; Hong, Seung Bok; Park, Hwa-Jin; Cho, Jae Youl; Rhee, Man Hee

    2015-01-01

    Background Korean Red Ginseng has been used as a traditional oriental medicine to treat illness and to promote health for several thousand years in Eastern Asia. It is widely accepted that ginseng saponins, ginsenosides, are the major active ingredients responsible for Korean Red Ginseng’s therapeutic activity against many kinds of illness. Although the crude saponin fraction (CSF) displayed antiplatelet activity, the molecular mechanism of its action remains to be elucidated. Methods The platelet aggregation was induced by collagen, the ligand of integrin αIIβI and glycoprotein VI. The crude saponin’s effects on granule secretion [e.g., calcium ion mobilization and adenosine triphosphate (ATP) release] were determined. The activation of mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinases (JNKs), and p38 MAPK, and phosphoinositide 3-kinase (PI3K)/Akt was analyzed by immunoblotting. In addition, the activation of integrin αIIbβIII was examined by fluorocytometry. Results CSF strongly inhibited collagen-induced platelet aggregation and ATP release in a concentration-dependent manner. It also markedly suppressed [Ca2+]i mobilization in collagen-stimulated platelets. Immunoblotting assay revealed that CSF significantly suppressed ERK1/2, p38, JNK, PI3K, Akt, and mitogen-activated protein kinase kinase 1/2 phosphorylation. In addition, our fraction strongly inhibited the fibrinogen binding to integrin αIIbβ3. Conclusion Our present data suggest that CSF may have a strong antiplatelet property and it can be considered as a candidate with therapeutic potential for the treatment of cardiovascular disorders involving abnormal platelet function. PMID:26199561

  1. Interactions between Eph kinases and ephrins provide a mechanism to support platelet aggregation once cell-to-cell contact has occurred

    PubMed Central

    Prevost, Nicolas; Woulfe, Donna; Tanaka, Takako; Brass, Lawrence F.

    2002-01-01

    Eph kinases are receptor tyrosine kinases whose ligands, the ephrins, are also expressed on the surface of cells. Interactions between Eph kinases and ephrins on adjacent cells play a central role in neuronal patterning and vasculogenesis. Here we examine the expression of ephrins and Eph kinases on human blood platelets and explore their role in the formation of the hemostatic plug. The results show that human platelets express EphA4 and EphB1, and the ligand, ephrinB1. Forced clustering of EphA4 or ephrinB1 led to cytoskeletal reorganization, adhesion to fibrinogen, and α-granule secretion. Clustering of ephrinB1 also caused activation of the Ras family member, Rap1B. In platelets that had been activated by ADP and allowed to aggregate, EphA4 formed complexes with two tyrosine kinases, Fyn and Lyn, and the cell adhesion molecule, L1. Blockade of Eph/ephrin interactions prevented the formation of these complexes and caused platelet aggregation at low ADP concentrations to become more readily reversible. We propose that when sustained contacts between platelets have occurred in response to agonists such as collagen, ADP, and thrombin, the binding of ephrins to Eph kinases on adjacent platelets provides a mechanism to perpetuate signaling and promote stable platelet aggregation. PMID:12084815

  2. Bromelain proteases reduce human platelet aggregation in vitro, adhesion to bovine endothelial cells and thrombus formation in rat vessels in vivo.

    PubMed

    Metzig, C; Grabowska, E; Eckert, K; Rehse, K; Maurer, H R

    1999-01-01

    The thiol protease, bromelain, an extract from pineapple stem, was suggested to have antithrombotic and anticoagulant activities in vivo. We studied the effects of bromelain on cell size distribution of isolated human platelets in vitro by Coulter Counter measurements. Preincubation of platelets with bromelain (10 micrograms/mL) completely prevented the thrombin (0.2 U/mL) induced platelet aggregation. Papain was less active in preventing platelet aggregation. In vitro, bromelain (0.1 microgram/mL) reduced the adhesion of bound, thrombin stimulated, fluorescent labeled platelets to bovine aorta endothelial cells. In addition, preincubation of platelets with bromelain, prior to thrombin, activation, reduced the platelet adhesion to the endothelial cells to the low binding value of unstimulated platelets. On the basis of mass concentrations, the proteases papain and trypsin were as effective as bromelain. Using a laser thrombosis model, the in vivo effects of orally and intraveneously applied bromelain on thrombus formation in rat mesenteric vessels were studied. Bromelain, orally applied at 60 mg/kg body weight, inhibited the thrombus formation in a time dependent manner, the maximum being after 2 hours in 11% of arterioles and 6% of venoles. Intravenous application at 30 mg/kg was slightly more active in reducing thrombus formation in arterioles (13%) and venoles (5%), suggesting that orally applied bromelain is biologically active. These results may help to explain some of the clinical effects observed after bromelain treatment in patients with thrombosis and related diseases.

  3. [Measurement of the concentration of free cytoplasmic calcium in the process of platelet aggregation using a fluorescent method].

    PubMed

    Popov, E G; Gavrilov, I Iu; Pozin, E Ia; Gabbasov, Z A

    1989-01-01

    A multiwavelength method for measuring free cytosolic calcium concentration is proposed. It is based on the registration of the fluorescent spectrum of calcium--sensitive probe indo-1 and deconvolution of the spectrum into components corresponding to free and bound forms of the probe. Calcium concentration is calculated as a product of calcium-probe dissociation constant by calcium-bound to free form concentration ratio. The obtained values are independent of variations in light-scattering properties of the medium and total dye concentration in the optical channel. It is shown that during ADP-induced platelet aggregation calcium concentration rises without measurable delay after the addition of the inducer and significantly decreases by the time the aggregation begins.

  4. Evaluating the inhibitory potential of Withania somnifera on platelet aggregation and inflammation enzymes: An in vitro and in silico study.

    PubMed

    M, Madhusudan; Zameer, Farhan; Naidu, Akhilender; M N, Nagendra Prasad; Dhananjaya, Bhadrapura Lakkappa; Hegdekatte, Raghavendra

    2016-09-01

    Context Withania somnifera (L.) Dunal is traditionally used for treating various ailments, but lacks scientific evaluation. Objective This study evaluates Withania somnifera (WS) for its effect on platelet activity and inflammatory enzymes. Materials and methods Aqueous and ethanolic (1:1) leaf extracts were subjected to in vitro indirect haemolytic activity using Naja naja venom, human platelet aggregation was quantified for lipid peroxidation using arachidonic acid (AA) as agonist and 5-lipoxygenase (5-LOX) levels were determined using standard spectrometric assays. Further, molecular docking was performed by the ligand fit method using molegro software package (Molegro ApS, Aarhus, Denmark). Results The study found that aqueous and ethanol extracts have very negligible effect (15%) with an IC50 value of 13.8 mg/mL on PLA2 from Naja naja venom. Further, extracts of WS also had very little effect (18%) with an IC50 value of 16.6 mg/mL on malondialdehyde (MDA) formation. However, a 65% inhibition of 5-LOX with an IC50 value of 0.92 mg/mL was observed in 1:1 ethanol extracts. The same was evident from SAR model with the active ingredient withaferin A binding predominantly on Phe 77, Tyr 98, Arg 99, Asp 164, Leu 168, Ser 382, Arg 395, Tyr 396 and Tyr 614 with an atomic contact energy value of -128.96 compared to standard phenidone (-103.61). Thus, the current study validates the application of WS for inflammatory diseases. Conclusion This study reveals the inhibitory potential of W. somnifera on inflammatory enzymes and platelet aggregation. Thus, WS can serve as a newer, safer and affordable medicine for inflammatory diseases. PMID:26704448

  5. Evaluating the inhibitory potential of Withania somnifera on platelet aggregation and inflammation enzymes: An in vitro and in silico study.

    PubMed

    M, Madhusudan; Zameer, Farhan; Naidu, Akhilender; M N, Nagendra Prasad; Dhananjaya, Bhadrapura Lakkappa; Hegdekatte, Raghavendra

    2016-09-01

    Context Withania somnifera (L.) Dunal is traditionally used for treating various ailments, but lacks scientific evaluation. Objective This study evaluates Withania somnifera (WS) for its effect on platelet activity and inflammatory enzymes. Materials and methods Aqueous and ethanolic (1:1) leaf extracts were subjected to in vitro indirect haemolytic activity using Naja naja venom, human platelet aggregation was quantified for lipid peroxidation using arachidonic acid (AA) as agonist and 5-lipoxygenase (5-LOX) levels were determined using standard spectrometric assays. Further, molecular docking was performed by the ligand fit method using molegro software package (Molegro ApS, Aarhus, Denmark). Results The study found that aqueous and ethanol extracts have very negligible effect (15%) with an IC50 value of 13.8 mg/mL on PLA2 from Naja naja venom. Further, extracts of WS also had very little effect (18%) with an IC50 value of 16.6 mg/mL on malondialdehyde (MDA) formation. However, a 65% inhibition of 5-LOX with an IC50 value of 0.92 mg/mL was observed in 1:1 ethanol extracts. The same was evident from SAR model with the active ingredient withaferin A binding predominantly on Phe 77, Tyr 98, Arg 99, Asp 164, Leu 168, Ser 382, Arg 395, Tyr 396 and Tyr 614 with an atomic contact energy value of -128.96 compared to standard phenidone (-103.61). Thus, the current study validates the application of WS for inflammatory diseases. Conclusion This study reveals the inhibitory potential of W. somnifera on inflammatory enzymes and platelet aggregation. Thus, WS can serve as a newer, safer and affordable medicine for inflammatory diseases.

  6. [The relationship between lipid peroxidation and platelet aggregation in atherosclerotic patients].

    PubMed

    Gómez Calviño, C; Simón Carballo, R; Coma Alfonso, C; Sánchez de León, T; Montero Pacheco, E; Rodríguez Piloto, R

    1991-01-01

    We studied 58 patients with arterial esteno-occlusive disease, 32 diabetics and 26 nondiabetics. Some parameters of lipid metabolism and platelet function were evaluated. We show the correlations founded among these parameters and we offer a possible explanation which support this behaviour.

  7. Interactions between integrin αIIbβ3 and the serotonin transporter regulate serotonin transport and platelet aggregation in mice and humans

    PubMed Central

    Carneiro, Ana Marin D.; Cook, Edwin H.; Murphy, Dennis L.; Blakely, Randy D.

    2008-01-01

    The essential contribution of the antidepressant-sensitive serotonin (5-HT) transporter SERT (which is encoded by the SLC6A4 gene) to platelet 5-HT stores suggests an important role of this transporter in platelet function. Here, using SERT-deficient mice, we have established a role for constitutive SERT expression in efficient ADP- and thrombin-triggered platelet aggregation. Additionally, using pharmacological blockers of SERT and the vesicular monoamine transporter (VMAT), we have identified a role for ongoing 5-HT release and SERT activity in efficient human platelet aggregation. We have also demonstrated that fibrinogen, an activator of integrin αIIbβ3, enhances SERT activity in human platelets and that integrin αIIbβ3 interacts directly with the C terminus of SERT. Consistent with these findings, knockout mice lacking integrin β3 displayed diminished platelet SERT activity. Conversely, HEK293 cells engineered to express human SERT and an activated form of integrin β3 exhibited enhanced SERT function that coincided with elevated SERT surface expression. Our results support an unsuspected role of αIIbβ3/SERT associations as well as αIIbβ3 activation in control of SERT activity in vivo that may have broad implications for hyperserotonemia, cardiovascular disorders, and autism. PMID:18317590

  8. Maintaining Moderate Platelet Aggregation and Improving Metabolism of Endothelial Progenitor Cells Increase the Patency Rate of Tissue-Engineered Blood Vessels.

    PubMed

    Wu, Yangxiao; Li, Li; Chen, Wen; Zeng, Wen; Zeng, Lingqin; Wen, Can; Zhu, Chuhong

    2015-07-01

    Small-diameter tissue-engineered blood vessels (TEBVs) have been associated with low, long-term patency rates primarily because of acute thrombosis in early stages and an inability to achieve early endothelialization. Platelets and endothelial progenitor cells (EPCs) play a key role in these processes. A nano delayed-release 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR)-bound TEBV was implanted in rat carotid arteries for 3 months. AICAR-bound TEBVs had a high patency rate compared with control TEBVs after 3 months. We found that AICAR maintained moderate platelet aggregation in vivo. In vitro data indicated that AICAR inhibits the release of 5-hydroxytryptamine and thromboxane A2 in activating platelets to reduce platelet aggregation. Then, we confirmed that AICAR strengthens the EPC energy state, which results in earlier endothelialization. The homing, migration, and paracrine function of EPCs were enhanced by AICAR in vitro. Besides, AICAR can contribute to the migration of endothelial cells near the anastomosis. The cellularization of TEBVs at different time points was observed too. In conclusion, our study suggests that the application of nanodelivery material containing AICAR can effectively improve small-diameter TEBVs by maintaining moderate platelet aggregation and improving metabolism of EPCs.

  9. 1,4-Benzenediboronic-Acid-Induced Aggregation of Gold Nanoparticles: Application to Hydrogen Peroxide Detection and Biotin-Avidin-Mediated Immunoassay with Naked-Eye Detection.

    PubMed

    Yang, Ya-Chun; Tseng, Wei-Lung

    2016-05-17

    Hydrogen-peroxide (H2O2)-induced growth of small-sized gold nanoparticles (AuNPs) is often implemented for H2O2 sensing and plasmonic immunoassay. In contrast, there is little-to-no information in the literature regarding the application of H2O2-inhibited aggregation of citrate-capped AuNPs. This study discloses that benzene-1,4-diboronic acid (BDBA) was effective in driving the aggregation of citrate-capped AuNPs through an interaction between α-hydroxycarboxylate of citrate and boronic acids of BDBA. The H2O2-mediated oxidation of BDBA resulted in the conversion of boronic acid groups to phenol groups. The oxidized BDBA was incapable of triggering the aggregation of citrate-capped AuNPs. Thus, the presence of H2O2 prohibited BDBA-induced aggregation of citrate-capped AuNPs. The BDBA-induced aggregation of citrate-capped AuNPs can be paired with the glucose oxidase (GOx)-glucose system to design a colorimetric probe for glucose. Moreover, a H2O2·BDBA·AuNP probe was integrated with sandwich immunoassay, biotinylated antibody, and avidin-conjugated GOx for the selective naked-eye detection of rabbit immunoglobulin G (IgG) and human-prostate-specific antigen (PSA). The lowest detectable concentrations of rabbit IgG and human PSA by the naked eye were down to 0.1 and 4 ng/mL, respectively. More importantly, the proposed plasmonic immunoassay allowed the naked-eye quantification of 0-10 ng/mL PSA at an interval of 2 ng/mL in plasma samples.

  10. 1,4-Benzenediboronic-Acid-Induced Aggregation of Gold Nanoparticles: Application to Hydrogen Peroxide Detection and Biotin-Avidin-Mediated Immunoassay with Naked-Eye Detection.

    PubMed

    Yang, Ya-Chun; Tseng, Wei-Lung

    2016-05-17

    Hydrogen-peroxide (H2O2)-induced growth of small-sized gold nanoparticles (AuNPs) is often implemented for H2O2 sensing and plasmonic immunoassay. In contrast, there is little-to-no information in the literature regarding the application of H2O2-inhibited aggregation of citrate-capped AuNPs. This study discloses that benzene-1,4-diboronic acid (BDBA) was effective in driving the aggregation of citrate-capped AuNPs through an interaction between α-hydroxycarboxylate of citrate and boronic acids of BDBA. The H2O2-mediated oxidation of BDBA resulted in the conversion of boronic acid groups to phenol groups. The oxidized BDBA was incapable of triggering the aggregation of citrate-capped AuNPs. Thus, the presence of H2O2 prohibited BDBA-induced aggregation of citrate-capped AuNPs. The BDBA-induced aggregation of citrate-capped AuNPs can be paired with the glucose oxidase (GOx)-glucose system to design a colorimetric probe for glucose. Moreover, a H2O2·BDBA·AuNP probe was integrated with sandwich immunoassay, biotinylated antibody, and avidin-conjugated GOx for the selective naked-eye detection of rabbit immunoglobulin G (IgG) and human-prostate-specific antigen (PSA). The lowest detectable concentrations of rabbit IgG and human PSA by the naked eye were down to 0.1 and 4 ng/mL, respectively. More importantly, the proposed plasmonic immunoassay allowed the naked-eye quantification of 0-10 ng/mL PSA at an interval of 2 ng/mL in plasma samples. PMID:27091002

  11. New Acyloxy Nitroso Compounds with Improved Water Solubility and Nitroxyl (HNO) Release Kinetics and Inhibitors of Platelet Aggregation

    PubMed Central

    Mohamed, Heba A. H.; Abdel-Aziz, Mohamed; Abuo-Rahma, Gamal El-Din A. A.; King, S. Bruce.

    2015-01-01

    New acyloxy nitroso compounds, 4-nitrosotetrahydro-2H-pyran-4-yl 2,2,2-trichloroacetate and 4-nitrosotetrahydro-2H-pyran-4-yl 2,2-dichloropropanoate were prepared. These compounds release HNO under neutral conditions with half-lives between 50 and 120 minutes, identifying these HNO donors as kinetically intermediate to the much slower acetate derivative and the faster trifluoroacetic acid derivative. These compounds or HNO-derived from these compounds react with thiols, including glutathione, thiol-containing enzymes and heme-containing proteins in a similar fashion to other acyloxy nitroso compounds. HNO released from these acyloxy nitroso compounds inhibits activated platelet aggregation. These acyloxy nitroso compounds augment the range of release for this group of HNO donors and should be valuable tools in the further study of HNO biology. PMID:26228501

  12. MK-886, an inhibitor of the 5-lipoxygenase-activating protein, inhibits cyclooxygenase-1 activity and suppresses platelet aggregation.

    PubMed

    Koeberle, Andreas; Siemoneit, Ulf; Northoff, Hinnak; Hofmann, Bettina; Schneider, Gisbert; Werz, Oliver

    2009-04-17

    MK-886, an inhibitor of the 5-lipoxygenase-activating protein (FLAP), potently suppresses leukotriene biosynthesis in intact cells and is frequently used to define a role of the 5-lipoxygenase (EC 1.13.11.34) pathway in cellular or animal models of inflammation, allergy, cancer, and cardiovascular disease. Here we show that MK-886 also interferes with the activities of cyclooxygenases (COX, EC 1.14.99.1). MK-886 inhibited isolated COX-1 (IC(50)=8 microM) and blocked the formation of the COX-1-derived products 12(S)-hydroxy-5-cis-8,10-trans-heptadecatrienoic acid (12-HHT) and thromboxane B(2) in washed human platelets in response to collagen as well as from exogenous arachidonic acid (IC(50)=13-15 microM). Isolated COX-2 was less affected (IC(50)=58 microM), and in A549 cells, MK-886 (33 microM) failed to suppress COX-2-dependent 6-keto-prostaglandin (PG)F(1alpha) formation. The distinct susceptibility of MK-886 towards COX-1 and -2 is apparent in automated molecular docking studies that indicate a preferred binding of MK-886 to COX-1 into the active site. MK-886 (10 microM) inhibited COX-1-mediated platelet aggregation induced by collagen or arachidonic acid whereas thrombin- or U-46619-induced (COX-independent) aggregation was not affected. Since leukotrienes and prostaglandins share (patho)physiological properties in the development and regulation of carcinogenesis, inflammation, and vascular functions, caution should be used when interpreting data where MK-886 is used as tool to determine the involvement of FLAP and/or the 5-lipoxygenase pathway in respective experimental models.

  13. Effects of simvastatin/ezetimibe on microparticles, endothelial progenitor cells and platelet aggregation in subjects with coronary heart disease under antiplatelet therapy

    PubMed Central

    Camargo, L.M.; França, C.N.; Izar, M.C.; Bianco, H.T.; Lins, L.S.; Barbosa, S.P.; Pinheiro, L.F.; Fonseca, F.A.H.

    2014-01-01

    It is not known whether the addition of ezetimibe to statins adds cardiovascular protection beyond the expected changes in lipid levels. Subjects with coronary heart disease were treated with four consecutive 1-week courses of therapy (T) and evaluations. The courses were: T1, 100 mg aspirin alone; T2, 100 mg aspirin and 40 mg simvastatin/10 mg ezetimibe; T3, 40 mg simvastatin/10 mg ezetimibe, and 75 mg clopidogrel (300 mg initial loading dose); T4, 75 mg clopidogrel alone. Platelet aggregation was examined in whole blood. Endothelial microparticles (CD51), platelet microparticles (CD42/CD31), and endothelial progenitor cells (CD34/CD133; CDKDR/CD133, or CD34/KDR) were quantified by flow cytometry. Endothelial function was examined by flow-mediated dilation. Comparisons between therapies revealed differences in lipids (T2 and T3T1 and T4, P=0.001). Decreased platelet aggregation was observed after aspirin (arachidonic acid, T1platelet aggregation, the amount of circulating endothelial and platelet microparticles, or endothelial progenitor cells. Cardiovascular protection following therapy with simvastatin/ezetimibe seems restricted to lipid changes and improvement of endothelial function not affecting the release of microparticles, mobilization of endothelial progenitor cells or decreased platelet aggregation. PMID:24760119

  14. Effects of condensation products of biogenic amines on human platelet function

    SciTech Connect

    Given, M.B.

    1983-01-01

    Condensation products (CP) are formed by the reaction of biogenic amines with aldehydes and alpha-keto acids. The purpose of this investigation was to examine the effects of CP on platelet function in vitro. The effect of CP on platelet aggregation was examined. Epinephrine-induced aggregation was inhibited, suggesting CP antagonistic activity on the platelet alpha/sub 2/-adrenergic receptors. Adenosine-diphosphate (ADP), collagen and arachidonic acid induced aggregation was inhibited only at high concentrations. Inhibition of epinephrine and ADP aggregation was reversible, suggesting CP are competitive inhibitors of these agonists. Binding affinities for the platelet alpha/sub 2/-adrenergic receptor were determined using (/sup 3/H)-yohimbine, a specific alpha/sup 2/-receptor antagonist. The order of potency for CP inhibition of (/sup 3/H)-yohimbine binding paralleled that determined for inhibition of epinephrine-induced aggregation. Platelet uptake of serotonin (5-HT) was competitively inhibited by CP, with the exception of salsolinol, which appears to be stimulatory. Release of 5-HT from platelets was induced by CP, with betacarbolines being more potent than tetrahydroisoquinolines. Evidence suggests that CP cause release by displacement of 5-HT from intraplatelet storage sites since this effect can be inhibited by imipramine, thus preventing accumulation of CP by platelets.

  15. The value of flow cytometry in the measurement of platelet activation and aggregation in human immunodeficiency virus infection.

    PubMed

    Nkambule, Bongani B; Davison, Glenda; Ipp, Hayley

    2015-01-01

    Human immunodeficiency deficiency virus (HIV) infection is associated with chronic inflammation and an increased risk of thrombotic events. Activated platelets (PLTs) play an important role in both thrombosis and inflammation, and HIV has been shown to induce PLT activation by both direct and indirect mechanisms. P-selectin (CD62P) is a well-described marker of PLT activation, and PLT glycoprotein (GP) IV (CD36) has been identified as a marker of PLT aggregation. Data on PLT function in the context of HIV infection remain inconclusive. Laboratory techniques, such as flow cytometry, enable the assessment of PLTs in their physiological state and environment, with minimal artifactual in vitro activation and aggregation. In this study, we describe a novel flow cytometry PLT assay, which enabled the measurement of PLT function in HIV infection. Forty-one antiretroviral-naïve HIV-positive individuals and 41 HIV-negative controls were recruited from a clinic in the Western Cape. Platelet function was evaluated by assessing the response of platelets to adenosine diphosphate (ADP) at two concentrations (0.04 mM, 0.2 mM). The percentage expression and mean fluorescence intensity (MFI) of CD62P and CD36 was used to evaluate platelet function. These were then correlated with platelet (PLT) count; CD4 count; % CD38/8; viral load and D-dimers. The % CD62P levels were higher in HIV-positive patients (HIV % CD62P 11.33[5.96-29.36] vs. control 2.48[1.56-6.04]; p < 0.0001). In addition, the HIV group showed higher CD62P MFI levels (HIV CD62P MFI 3.25 ± 7.23 vs. control 2.35 ± 1.31, p = 0.0292). Baseline levels of %CD36 expression were significantly higher in HIV-positive patients (%CD36 12.41[6.31-21.83] vs. control 6.04[1.34-13.15]; p = 0.0091). However, the baseline CD36MFI showed no significant difference between the two groups (HIV CD36 MFI 3.09 ± 0.64 vs. control 2.44 ± 0.11, p = 0.4591). The HIV group showed higher levels of % CD36

  16. Morphologies developed by the drying of droplets containing dispersed and aggregated layered double hydroxide platelets.

    PubMed

    Zhang, Yan; Evans, Julian R G

    2013-04-01

    Despite much interest in the structures formed from droplets of suspension as they dry, there are few studies involving plate-like particles. Layered double hydroxide suspensions were prepared with pH adjusted to give well-dispersed and flocculated variants that were characterised by sedimentation and rheology measurements. In the well-dispersed suspension, the three-phase boundary was pinned and radial flow created a peripheral wall. The platelet structure involved local flat packing but was replete with scrolls that result from the recirculation flows in the droplets as they dry. In contrast, the flocculating suspension produced flatter droplet relics and the microstructure consisted of ordered domains which were disoriented with respect to each other. Although of scientific interest, the control of these structures will make it possible to use direct ink-jet printing to build 3D shapes for the preparation of aligned, ordered nanocomposites based on plate-like particles in which platelet preferred orientation mimics the structures found in nacre.

  17. Ticlopidine, Alka-Seltzer, or a combination of citric acid with aspirin: effects on platelet aggregation in individuals with an insufficient response to aspirin alone.

    PubMed

    Kaplan, S; Kaplan, A; Marcoe, K; Sauvage, L R

    2000-10-01

    Aspirin (ASA) does not effectively lower platelet aggregation in all people. The platelet aggregation (PA) score is an easily used clinical method for measuring the effect in individuals of antiplatelet medications. Fifteen apparently healthy subjects (2 men and 13 women), selected for their resistance to ASA's antiaggregation effect, completed a sequential trial of ticlopidine, Alka-Seltzer, and ASA + citric acid (CTA). Ticlopidine was the strongest aggregation inhibitor and the ASA + CTA combination was more inhibitory than Alka-Seltzer. It was determined that measuring antiaggregation effects of a particular agent in an individual prior to usage would optimize treatment. The PA score methodology provides a means for testing patients prior to antiplatelet therapy for prevention and treatment of the thrombotic complications of vascular disease. PMID:11030528

  18. Effect of allicin (diallyl disulfide-oxide) on prostaglandin endoperoxide H/sub 2/ (PGH/sub 2/) and arachidonic acid (AA) metabolism and platelet aggregation

    SciTech Connect

    Mayeux, P.R.; Agrawal, K.C.; King, B.T.; Kadowitz, P.J.; McNamara, D.B.

    1986-03-01

    The authors report here the effects of pure allicin (the antibacterial component of GO), synthesized from diallyl disulfide and hydrogen peroxide, on human platelet aggregation, PGH/sub 2/ metabolism in microsomes of bovine lung (BL) and bovine coronary artery (BCA), homogenates of human platelet (HP), and on AA metabolism in HP. Allicin at 16 ..mu..g/ml to 160 ..mu..g/ml produced concentration-dependent inhibition of platelet aggregation to 1.6 mM AA and 2.8 ..mu..M U 46619, a stable analog of PGH/sub 2/ and a TXA/sub 2/ minic. BL (200 ..mu..g protein), BCA (10 ..mu..g protein), and HP (1500 ..mu..g protein) were incubated with 10 ..mu..M (/sup 14/C) PGH/sub 2/ +/- allicin. HP (1500 ..mu..g protein) were incubated with 20 ..mu..M (/sup 14/C) AA +/- allicin. Products were separated by TLC and quantified by radiochromatographic scan. Allicin in the concentration range of 10-/sup 6/M-10-/sup 3/M induced no change in the formation of prostacyclin by BL and BCA or of TXA/sub 2/ by BL and HP. These data suggest that the platelet antiaggregatory action of allicin is not due to inhibition of cyclooxygenase or TXA/sub 2/ synthetase in the human platelet, but may be related to interactions at the TXA/sub 2/ receptor or on cyclic nucleotide levels.

  19. Selective anti-platelet aggregation synergism between a prostacyclin-mimetic, RS93427 and the nitrodilators sodium nitroprusside and glyceryl trinitrate.

    PubMed

    Willis, A L; Smith, D L; Loveday, M; Fulks, J; Lee, C H; Hedley, L; VanAntwerp, D

    1989-12-01

    1. Citrated platelet-rich plasma from human donors was used to examine turbidometrically the platelet aggregation response to collagen (2.5 micrograms ml-1) and ADP (1.6 microgram ml-1). 2. With collagen as an aggregating agent, the limited (35% maximal inhibition) inhibitory effects of glyceryl trinitrate (GTN, 0.78-50 micrograms ml-1) were markedly potentiated by threshold (3.3-10 ng ml-1) concentrations of RS93427, an orally active prostacyclin-mimetic. Almost complete inhibition of aggregation could then be produced. 3. A threshold concentration of RS93427 (3.3 ng ml-1) similarly potentiated the ability of sodium nitroprusside (NaNp, 0.78-10 micrograms ml-1) to inhibit collagen-induced platelet aggregation. There was an 8 fold reduction in the IC25 concentration of NaNp. 4. Threshold concentrations of the nitrodilators were also able to potentiate the anti-aggregatory effects of RS93427 (0.03-30 ng ml-1) on collagen-induced platelet aggregation. With threshold concentrations of either GTN (6.3-25 micrograms ml-1) or NaNp (0.3-1.3 microgram ml-1), the mean IC50 concentration of RS93427 was reduced 4 or 6 fold, respectively, while the IC25 concentration was reduced 6 or 10 fold, respectively. 5. No similar synergistic interactions were seen between RS93427 and the nitrodilators when ADP was used as an aggregating agent. 6. In spontaneously hypertensive rats, the dose-response for the hypotensive response to bolus doses of RS93427 was not altered by concomitant steady state infusion of a threshold dose (1 micrograms kg-1 min-1) of GTN. 7. Possible therapeutic implications of these findings are discussed.

  20. Targeting the anionic region of human protease activated receptor 4 (PAR4) inhibits platelet aggregation and thrombosis without interfering with hemostasis

    PubMed Central

    Mumaw, M. M.; de la Fuente, M.; Noble, D. N.; Nieman, M.T.

    2014-01-01

    Summary Background Human platelet activation and aggregation is a complex process. To date, many therapies have been developed targeting proteins that mediate this process to prevent unwanted activation. However, the current standard of care for acute coronary syndromes still has limitations including bleeding risk. Objective The aim of the current study is to evaluate the PAR4 anionic cluster as a viable antiplatelet target using a polyclonal antibody (CAN12). Methods We used western blotting, aggregation, and secretion ex vivo to evaluate the ability of CAN12 to interact with PAR4 and inhibit platelet activation. The effects of CAN12 in vivo were evaluated with the Rose Bengal arterial thrombosis model and two models of hemostasis. Results We show that CAN12 is able to interact with human PAR4 and delay PAR4 cleavage. In addition, CAN12 inhibits thrombin induced human platelet aggregation and secretion in a dose dependent manner. We next determined that the specificity of CAN12 is agonist dependent. In vivo, we determined that CAN12 is able to inhibit arterial thrombosis and using two independent methods, we found that CAN12 does not influence hemostasis. Conclusion Targeting the extracellular anionic cluster on PAR4 is a viable novel strategy as an anti-platelet therapy. PMID:24888424

  1. Platelet function in dogs with bacterial infections and leishmaniasis.

    PubMed

    Abid, Monia; Kalbantner, Kerstin; Mischke, Reinhard

    2015-01-01

    The objective of this study was to examine the influence of bacterial infections or leishmaniasis on primary haemostasis in dogs. Capillary bleeding time, automatic platelet function analysis (PFA-100), turbidimetric platelet aggregation, impedance aggregometry, platelet count and, in addition, the haematocrit were investigated in 25 dogs with bacterial infections or leishmaniasis . Results of these diseased dogs were compared to the control group and additionally classified into two subgroups based on criteria of systemic inflammatory response syndrome (SIRS) (groups "SIRS" and "Non-SIRS"). Dogs with infections had a significantly prolonged closure time of the PFA-100 using both cartridges (e. g., collagen/ADP: 83 [55-301] vs. 65 [47-99 s; median [minimum-maximum]; p < 0.0001), a significant decrease in maximal aggregation of the turbidimetric aggregometry (e. g., ADP-induced: 45.2 ± 26.8 vs. 67.3 ± 21.8%; mean ± SD; P = 0.003), a significant increase of collagen-induced impedance aggregometry and a significant suppression of arachidonic acid-induced impedance aggregometry. An enhanced collagen-induced impedance aggregation was the only significant difference between subgroups "SIRS"and "Non-SIRS". In conclusion, although individual tests indicate enhanced platelet aggregation, most of the in vitro tests revealed a normal to moderately reduced functionality. The reduced aggregabiity may partly indicate preactivation of platelets. PMID:26281441

  2. Inhibition of whole blood platelet-aggregation by compounds in garlic clove extracts and commercial garlic products.

    PubMed

    Lawson, L D; Ransom, D K; Hughes, B G

    1992-01-15

    The inhibitory effects of adenosine and 16 quantitatively determined organosulfur compounds derived from garlic cloves or commercial garlic preparations on collagen stimulated in vitro platelet aggregation in whole blood were determined. An estimation of the anti-aggregatory activity of several brands of the major types of commercial garlic preparations was determined from the activities of the individual compounds present in each sample. In platelet rich plasma (PRP) most of the anti-aggregatory activity of garlic clove homogenates was due to adenosine; however, in whole blood neither adenosine nor the polar fraction had any effect and all of the anti-aggregatory activity was due to allicin and other thiosulfinates. Allicin was equally active in whole blood and PRP. Among brands there was a several-fold variation in content of the organosulfur compounds and activity for all types of garlic products tested. The best garlic powder tablets were equally as active as clove homogenates whereas steam-distilled oils were 35% as active and oil-macerates (due to low content) only 12% as active. A garlic product aged many months in aqueous alcohol had no activity. For steam-distilled oils, most of the activity was due to diallyl trisulfide. For the oil-macerates, most of the activity was due largely to the vinyl dithiins. Ajoene, an exclusive component of the oil-macerates, had highest specific activity of all the compounds tested but, because of its low concentration, had only 13% of the activity of diallyl trisulfide and 3% of the activity of allicin. Compounds which may be active in vivo are discussed. PMID:1579891

  3. Cloning of subunits of convulxin, a collagen-like platelet-aggregating protein from Crotalus durissus terrificus venom.

    PubMed Central

    Leduc, M; Bon, C

    1998-01-01

    Convulxin (CVX) is a potent platelet-aggregating glycoprotein from the venom of the snake Crotalus durissus terrificus. It consists of two subunits, alpha and beta, joined by disulphide bridges in a hexameric structure. A cDNA library from venom gland was constructed in the vector pT3T7. The cloned cDNAs encoding the two chains of CVX were sequenced. Both are preceded by an identical 23-amino acid peptide signal sequence and encode sequences of 135 amino acids for the alpha chain and 125 amino acids for the beta chain. These polypeptides include a carbohydrate-recognition domain (CRD) in which some of the specific amino acids required for binding Ca2+ and galactose or mannose are absent. The presence of such a domain means that CVX can be included in the family of C-type lectins along with other snake venom proteins, although it is not a true lectin. Assuming that the localization of intracatenary disulphide bridges of each CVX chain is similar to that of the CRD and that an intercatenary bridge between the alpha and beta chains is similar to that of the C-type lectin botrocetin, we postulate the existence of an additional intercatenary bridge, which explains the tridimeric structure (alphabeta)3 of CVX. PMID:9657980

  4. Sequential sup 1 H NMR assignments of kistrin, a potent platelet aggregation inhibitor and glycoprotein IIb-IIIa antagonist

    SciTech Connect

    Adler, M.; Wagner, G. )

    1992-02-04

    Sequence-specific nuclear magnetic resonances assignments have been obtained for the protons of kistrin. Kistrin is a small naturally occurring snake venom protein that inhibits platelet aggregation by blocking the interaction of fibrinogen with the membrane-bound glycoprotein IIb-IIIa (GP IIb-IIIa), a receptor from the integrin family. Kistrin has an Arg-Gly-Asp sequence which is believed to form an adhesion recognition sequence that is essential for activity. Therefore, the interaction between kistrin and GP IIb-IIIa may provide important information on the motif used by integrins to recognize their target proteins which bear RGD sequences. Kistrin consists of 68 residues and contains six intramolecular disulfide bonds. Although one-third of the amide protons are protected from exchange with the solvent, there appears to be little or no regular secondary structure. The large number of NOE's between residues separated by two and three positions in the sequence indicates that the protein contains a large number of tightly packed loops. Along with the sequential assignments, this paper also discusses the construction and use of computerized data bases for manipulating NMR results. A strategy for computer-assisted sequential resonance using these data bases is also presented.

  5. Discovery and preliminary SAR of 5-arylidene-2,2-dimethyl-1,3-dioxane- 4,6-diones as platelet aggregation inhibitors.

    PubMed

    El Maatougui, Abdelaziz; Azuaje, Jhonny; Coelho, Alberto; Cano, Ernesto; Yañez, Matilde; López, Carmen; Yaziji, Vicente; Carbajales, Carlos; Sotelo, Eddy

    2012-08-01

    We herein document the discovery of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones as a novel family of platelet aggregation inhibitors. The preliminary optimization study enabled us to establish the most salient features of the structure-activity relationships in this series as well as to identify novel derivatives that are upto 60 times more potent than the hit structure 1 and slightly superior to the reference drug Milrinone. PMID:22272691

  6. Discovery and preliminary SAR of 5-arylidene-2,2-dimethyl-1,3-dioxane- 4,6-diones as platelet aggregation inhibitors.

    PubMed

    El Maatougui, Abdelaziz; Azuaje, Jhonny; Coelho, Alberto; Cano, Ernesto; Yañez, Matilde; López, Carmen; Yaziji, Vicente; Carbajales, Carlos; Sotelo, Eddy

    2012-08-01

    We herein document the discovery of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones as a novel family of platelet aggregation inhibitors. The preliminary optimization study enabled us to establish the most salient features of the structure-activity relationships in this series as well as to identify novel derivatives that are upto 60 times more potent than the hit structure 1 and slightly superior to the reference drug Milrinone.

  7. Effects of combination treatment with policosanol and omega-3 fatty acids on platelet aggregation: A randomized, double-blind clinical study

    PubMed Central

    Castaño, Gladys; Arruzazabala, Maria L.; Fernández, Lilia; Mas, Rosa; Carbajal, Daisy; Molina, Vivian; Illnait, José; Mendoza, Sarahí; Gámez, Rafael; Mesa, Melbis; Fernández, Julio

    2006-01-01

    Background: Policosanol is a mixture of long-chain primary aliphatic alcoholspurified from sugar cane wax that has cholesterol lowering and antiplatelet effects. Omega-3 fatty acids (FA) have triglyceride lowering and antiplatelet effects. Combination treatment with policosanol and omega-3 FA (Ω23FA) has been associated with significant inhibition of platelet aggregation in rabbits compared with either drug alone. Objective: The aim of this study was to investigate the effects of combination treatment with Ω3FA (1 g/d) and policosanol (Ω3FA+Poli) compared with Ω3FA (1 g/d) plus placebo (Ω3FA+Pla) on platelet aggregation in human patients with hypercholesterolemia. Methods: This randomized, double-blind, clinical study at the Surgical Medical Research Center (Havana City, Cuba) recruited outpatients from lipid clinics, with some atherosclerotic risk factors. Outpatients of both sexes aged 20 to 75 years with serum total cholesterol (TC) levels ≥5 and <6 mmol/L were eligible to enroll. They were included in the study at the end of a 4-week diet stabilization period if their platelet aggregation to arachidonic acid (AA) was ≥50% and serum TC level remained ≥5 mmol/L. Patients were then evenly randomized to receive Ω3FA (1 g/d) + placebo or Ω3FA (1 g/d) + policosanol (10 mg/d) to be taken PO with the evening meal for 21 days. Treatment was assigned according to a randomization code using balanced blocks and a 1:1 allocation ratio. Inhibition of platelet aggregation to AA was the primary efficacy variable, while effects on platelet aggregation to collagen and epinephrine and on lipid profile were secondary variables. Drug compliance and adverse events (AEs) were monitored. Tolerability was assessed using physical examinations and laboratory test results. Results: Sixty-four subjects were initially enrolled. Fifty-four patients (30 women, 24 men; mean [SD] age, 58.4 [12] years, [range, 40–70 years]) met the inclusion criteria and were randomized to

  8. The effects of a selective 5-HT2 receptor antagonist (ICI 170,809) on platelet aggregation and pupillary responses in healthy volunteers.

    PubMed Central

    Millson, D S; Jessup, C L; Swaisland, A; Haworth, S; Rushton, A; Harry, J D

    1992-01-01

    1. ICI 170,809 (2-(2-dimethylamino-2-methylpropylthio)-3-phenylquinoline hydrochloride) is a potent 5-hydroxytryptamine (5-HT) type 2 postsynaptic receptor antagonist. 2. Effects of ICI 170,809 as single oral doses (3, 7, 15 and 30 mg) or placebo were studied on the duration of antagonism for the ex vivo platelet aggregatory response to 5-HT and to the pupillary light constrictor response in eight healthy male volunteers. 3. Pupillary dark adapted responses to a 0.5 s light stimulus were measured using a portable infrared pupillometer, for up to 24 h after dosing. 4. The in vitro platelet 5-HT aggregation response was reduced by ICI 170,809, with depression of the dose-response curve to 5-HT at all concentrations of 5-HT and with no evidence for a parallel shift. 5. The ex vivo platelet 5-HT response demonstrated a dose related significant (P less than 0.02) decrease in aggregation reaching a maximum at 2 h after dosing with the effect persisting for at least 8 h after dosing with the 7 and 15 mg doses. 6. Resting pupil diameter (RPD), and light induced pupillary responses in the dark adapted pupil, showed a significant (P less than 0.01) dose related reduction with significant (P less than 0.05) effects still present with the 15 and 30 mg doses at 8 h after dosing. 7. We conclude that, changes in both ex vivo platelet aggregation to 5-HT and dark adapted pupil size, are significantly correlated (P less than 0.0001) with log plasma concentrations (ng ml-1) of ICI 170,809, enabling the assessment of 5-HT2-receptor antagonism in man. PMID:1576048

  9. Reduced IL-35 levels are associated with increased platelet aggregation and activation in patients with acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

    PubMed

    Zhang, Xiaohui; Zhou, Yi; Xu, Lanping; Han, Wei; Chen, Huan; Chen, Yuhong; Fu, Haixia; Zhou, Shiyuan; Zhao, Jingzhong; Wang, Qianming; Feng, Feier; Zhu, Xiaolu; Liu, Kaiyan; Huang, Xiaojun

    2015-05-01

    Acute graft-versus-host disease (aGVHD) is a major complication associated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Interleukin (IL)-35 is a novel anti-inflammatory cytokine that suppresses the immune response. This prospective study explored IL-35 plasma levels in 65 patients after HSCT. The results revealed that the peripheral blood of patients with grades III-IV aGVHD (23.46 ng/ml) had reduced IL-35 compared to transplanted patients with grades I-II aGVHD (40.26 ng/ml, p < 0.01) or patients without aGVHD (41.40 ng/ml, p < 0.05). Allografts, including granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cell (PBPC) and G-CSF-primed bone marrow (GBM), from 38 patients were analyzed for IL-35 levels with respect to aGVHD. The patients who received lower levels of IL-35 cells in the GBM (28.0 ng/ml, p = 0.551) or lower levels of IL-35 in PBPC (53.46 ng/ml, p = 0.03) exhibited a higher incidence of aGVHD. Patients with aGVHD have increased platelet aggregation. IL-35 was added to patient blood in vitro, and platelet aggregation was inhibited by IL-35 in a dose-dependent manner. The markers of platelet activation (CD62P/PAC-1) can also be inhibited by IL-35. The results indicate that IL-35 may affect the development of aGVHD by inhibiting platelet activation and aggregation. Our data suggests that IL-35 represents a potentially effective therapeutic agent against aGVHD after allo-HSCT.

  10. [Effect of lovastatin on adhesive and aggregation function of platelets in patients with arterial hypertension and dislipidemia].

    PubMed

    Medvedev, I N; Skoriatina, I A

    2010-01-01

    The aim of the study was to evaluate efficiency of correction of lipid profile disturbances and platelet dysfunction by lovastatin in patients with arterial hypertension and dyslipidemia. Lovastatin was given to 29 patients for 4 months. The main parameters measured included dynamics of blood lipid profile, lipid peroxidation in plasma and platelets, antioxidative protection of blood fluid and platelets, platelet activity. t-Students test was used to assess statistical significance of the results. It was shown that lovastatin has beneficial effect on dyslipoproteidemia and peroxidation syndrome. Moreover, it normalizes intraplatelet regulatory mechanisms and inhibits enhanced platelet activity. Effects of lovastatin in patients with arterial hypertension and dyslipidemia persist under conditions of long-term therapy.

  11. Harpalycin 2 inhibits the enzymatic and platelet aggregation activities of PrTX-III, a D49 phospholipase A2 from Bothrops pirajai venom

    PubMed Central

    2012-01-01

    Background Harpalycin 2 (HP-2) is an isoflavone isolated from the leaves of Harpalyce brasiliana Benth., a snakeroot found in northeast region of Brazil and used in folk medicine to treat snakebite. Its leaves are said to be anti-inflammatory. Secretory phospholipases A2 are important toxins found in snake venom and are structurally related to those found in inflammatory conditions in mammals, as in arthritis and atherosclerosis, and for this reason can be valuable tools for searching new anti-phospholipase A2 drugs. Methods HP-2 and piratoxin-III (PrTX-III) were purified through chromatographic techniques. The effect of HP-2 in the enzymatic activity of PrTX-III was carried out using 4-nitro-3-octanoyloxy-benzoic acid as the substrate. PrTX-III induced platelet aggregation was inhibited by HP-2 when compared to aristolochic acid and p-bromophenacyl bromide (p-BPB). In an attempt to elucidate how HP-2 interacts with PrTX-III, mass spectrometry, circular dichroism and intrinsic fluorescence analysis were performed. Docking scores of the ligands (HP-2, aristolochic acid and p-BPB) using PrTX-III as target were also calculated. Results HP-2 inhibited the enzymatic activity of PrTX-III (IC50 11.34 ± 0.28 μg/mL) although it did not form a stable chemical complex in the active site, since mass spectrometry measurements showed no difference between native (13,837.34 Da) and HP-2 treated PrTX-III (13,856.12 Da). A structural analysis of PrTX-III after treatment with HP-2 showed a decrease in dimerization and a slight protein unfolding. In the platelet aggregation assay, HP-2 previously incubated with PrTX-III inhibited the aggregation when compared with untreated protein. PrTX-III chemical treated with aristolochic acid and p-BPB, two standard PLA2 inhibitors, showed low inhibitory effects when compared with the HP-2 treatment. Docking scores corroborated these results, showing higher affinity of HP-2 for the PrTX-III target (PDB code: 1GMZ) than aristolochic

  12. Impact of Dabigatran versus Phenprocoumon on ADP Induced Platelet Aggregation in Patients with Atrial Fibrillation with or without Concomitant Clopidogrel Therapy (the Dabi-ADP-1 and Dabi-ADP-2 Trials)

    PubMed Central

    Martischnig, Amadea M.; Mehilli, Julinda; Pollak, Janina; Petzold, Tobias; Fiedler, Anette K.; Mayer, Katharina; Schulz-Schüpke, Stefanie; Sibbing, Dirk; Massberg, Steffen; Kastrati, Adnan; Sarafoff, Nikolaus

    2015-01-01

    Background. A relevant number of patients receive triple therapy with clopidogrel, aspirin, and oral anticoagulation. Clopidogrel's efficacy on ADP induced platelet function may be influenced by concomitant antithrombotic therapies. Data regarding the effect of dabigatran on platelet function is limited to in vitro studies and healthy individuals. Methods. The “Dabi-ADP-1” and “Dabi-ADP-2” trials randomized patients with atrial fibrillation to either dabigatran or phenprocoumon for a 2-week period. In Dabi-ADP-1 (n = 70) patients with clopidogrel therapy were excluded and in Dabi-ADP-2 (n = 46) patients had to be treated concomitantly with clopidogrel. The primary endpoint was ADP-induced platelet aggregation between dabigatran and phenprocoumon at 14 days. Secondary endpoints were ADPtest HS-, TRAP-, and COL-induced platelet aggregation. Results. There was no significant difference regarding the primary endpoint between both groups in either trial (Dabi-ADP-1: Dabigatran: 846 [650–983] AU × min versus phenprocoumon: 839 [666–1039] AU × min, P = 0.90 and Dabi-ADP-2: 326 [268–462] versus 350 [214–535], P = 0.70) or regarding the secondary endpoints, ADPtest HS-, TRAP-, and COL-induced platelet aggregation. Conclusion. Dabigatran as compared to phenprocoumon has no impact on ADP-induced platelet aggregation in atrial fibrillation patients neither with nor without concomitant clopidogrel therapy. PMID:26229963

  13. One-step apexification in immature tooth using grey mineral trioxide aggregate as an apical barrier and autologus platelet rich fibrin membrane as an internal matrix

    PubMed Central

    Rudagi, Kavitarani B; Rudagi, BM

    2012-01-01

    Immature teeth with necrotic pulp and periapical lesion are difficult to treat via conventional endodontic therapy. Numerous procedures and materials have been utilized to induce root-end barrier formation. Traditionally, calcium hydroxide has been the material of choice for the apexification of immature permanent teeth; however, Mineral Trioxide Aggregate holds significant promise as an alternative to multiple treatments with calcium hydroxide. One of the technical problems associated with the placement of the restorative materials used as artificial barrier is to prevent overfill and underfill. Using a matrix avoids the extrusion of the material into the periodontal tissues. This case report presents the successful healing and apexification with combined use of Mineral Trioxide Aggregate as an apical barrier, and autologus platelet rich fibrin membrane as an internal matrix. PMID:22557824

  14. Rapid Purification and Procoagulant and Platelet Aggregating Activities of Rhombeobin: A Thrombin-Like/Gyroxin-Like Enzyme from Lachesis muta rhombeata Snake Venom

    PubMed Central

    Torres-Huaco, Frank Denis; Werneck, Cláudio C.; Vicente, Cristina Pontes; Vassequi-Silva, Talita; Nery-Diez, Ana Cláudia Coelho; Mendes, Camila B.; Antunes, Edson; Marangoni, Sérgio; Damico, Daniela C. S.

    2013-01-01

    We report a rapid purification method using one-step chromatography of SVSP Rhombeobin (LMR-47) from Lachesis muta rhombeata venom and its procoagulant activities and effects on platelet aggregation. The venom was fractionated by a single chromatographic step in RP-HPLC on a C8 Discovery BIO Wide Pore, showing high degree of molecular homogeneity with molecular mass of 47035.49 Da. Rhombeobin showed amidolytic activity upon BAρNA, with a broad optimum pH (7–10) and was stable in solution up to 60°C. The amidolytic activity was inhibited by serine proteinase inhibitors and reducing agents, but not chelating agents. Rhombeobin showed high coagulant activity on mice plasma and bovine fibrinogen. The deduced amino acid sequence of Rhombeobin showed homology with other SVSPs, especially with LM-TL (L. m. muta) and Gyroxin (C. d. terrificus). Rhombeobin acts, in vitro, as a strong procoagulant enzyme on mice citrated plasma, shortening the APTT and PT tests in adose-dependent manner. The protein showed, “ex vivo”, a strong defibrinogenating effect with 1 µg/animal. Lower doses activated the intrinsic and extrinsic coagulation pathways and impaired the platelet aggregation induced by ADP. Thus, this is the first report of a venom component that produces a venom-induced consumptive coagulopathy (VICC). PMID:24058917

  15. Engineering new bone via a minimally invasive route using human bone marrow-derived stromal cell aggregates, microceramic particles, and human platelet-rich plasma gel.

    PubMed

    Chatterjea, Anindita; Yuan, Huipin; Fennema, Eelco; Burer, Ruben; Chatterjea, Supriyo; Garritsen, Henk; Renard, Auke; van Blitterswijk, Clemens A; de Boer, Jan

    2013-02-01

    There is a rise in the popularity of arthroscopic procedures in orthopedics. However, the majority of cell-based bone tissue-engineered constructs (TECs) rely on solid preformed scaffolding materials, which require large incisions and extensive dissections for placement at the defect site. Thus, they are not suitable for minimally invasive techniques. The aim of this study was to develop a clinically relevant, easily moldable, bone TEC, amenable to minimally invasive techniques, using human mesenchymal stromal cells (hMSCs) and calcium phosphate microparticles in combination with an in situ forming platelet-rich plasma gel obtained from human platelets. Most conventional TECs rely on seeding and culturing single-cell suspensions of hMSCs on scaffolds. However, for generating TECs amenable to the minimally invasive approach, it was essential to aggregate the hMSCs in vitro before seeding them on the scaffolds as unaggregated MSCs did not generate any bone. Twenty four hours of in vitro aggregation was determined to be optimal for maintaining cell viability in vitro and bone formation in vivo. Moreover, no statistically significant difference was observed in the amount of bone formed when the TECs were implanted via an open approach or a minimally invasive route. TECs generated using MSCs from three different human donors generated new bone through the minimally invasive route in a reproducible manner, suggesting that these TECs could be a viable alternative to preformed scaffolds employed through an open surgery for treating bone defects.

  16. Correlation between spontaneous metastatic potential, platelet-aggregating activity of cell surface extracts, and cell surface sialylation in 10 metastatic-variant derivatives of a rat renal sarcoma cell line.

    PubMed Central

    Pearlstein, E; Salk, P L; Yogeeswaran, G; Karpatkin, S

    1980-01-01

    Several properties of 10 cell lines derived from the polyoma-induced PW20 Wistar-Furth rat renal sarcoma have been examined, including the ability of the tumor cells to metastasize spontaneously from subcutaneous sites in syngeneic hosts, the platelet-aggregating activity of material extracted by urea from the surface of cultured cells, the sialic acid content of the platelet-aggregating material, and the degree of sialylation of cell surface glycoconjugates in cultured cells. A correlation has been observed among all of these parameters. The results suggest a possible link between the degree of cell surface sialylation of tumor cells, their ability to aggregate platelets, and their ability to metastasize. PMID:6933486

  17. Antithrombotic effects of losartan in patients with hypertension complicated by atrial fibrillation: 4A (Angiotensin II Antagonist of platelet Aggregation in patients with Atrial fibrillation), a pilot study.

    PubMed

    Sakamoto, Tomohiro; Kudoh, Takashi; Sakamoto, Kenji; Matsui, Kunihiko; Ogawa, Hisao

    2014-06-01

    Angiotensin receptor blockers (ARBs) are widely used for the treatment of hypertension. It has been reported that the ARB losartan has antiplatelet, anticoagulant and profibrinolytic effects experimentally. These properties could be desirable to treat hypertensive patients with high atherothrombotic and/or thromboembolic risk. To examine the antithrombotic effects of losartan in hypertension, 20 consecutive patients with hypertension complicated by atrial fibrillation (AF) were enrolled in this study. The patients were treated with losartan 50 mg for 8 weeks followed by 100 mg for 4 weeks. Blood samples were obtained from each patient at 0 (pretreatment), 8 and 12 weeks after initiating treatment. Platelet aggregability, plasma levels of tissue factor (TF) and type 1 plasminogen activator inhibitor (PAI-1) activity levels were measured. The area under the curve for small platelet aggregability decreased from 100 to 42.8% at 12 weeks (P<0.0001). TF levels (ng ml(-1)) and PAI-1 activity (IU ml(-1); mean±s.d.) also changed from 14.2±3.6 to 10.9±4.5 at 12 weeks (P=0.0299) and from 11.7±3.6 to 8.5±3.1 at 12 weeks (P=0.0122), respectively. Losartan inhibited platelet activity and coagulation factors in a dose- and time-dependent manner in patients with hypertension complicated by AF, whereas the fibrinolytic capacity was increased. The use of losartan could be advantageous in the treatment of hypertensive patients with high atherothrombotic risk.

  18. Acetylsalicylic Acid Daily vs Acetylsalicylic Acid Every 3 Days in Healthy Volunteers: Effect on Platelet Aggregation, Gastric Mucosa, and Prostaglandin E2 Synthesis.

    PubMed

    Ferreira, Plinio Minghin Freitas; Gagliano-Jucá, Thiago; Zaminelli, Tiago; Sampaio, Marinalva Ferreira; Blackler, Rory Willian; Trevisan, Miriam da Silva; Novaes Magalhães, Antônio Frederico; De Nucci, Gilberto

    2016-07-01

    Substantial platelet inhibition was observed 3 days after a single administration of acetylsalicylic acid 81 mg to healthy volunteers. Here we investigate prostaglandin E2 (PGE2 ) antrum concentrations and gastrointestinal symptoms in two treatment groups: one receiving losartan and acetylsalicylic acid every day and the other receiving losartan every day and acetylsalicylic acid every 3 days. Twenty-eight healthy volunteers from both sexes received either 50 mg losartan and acetylsalicylic acid 81 mg daily or 50 mg losartan and acetylsalicylic acid 81 every 3 days with placebo on the other days. Therapy was delivered for 30 days for both groups. Gastric endoscopy was performed before and after treatment period. Biopsies were collected for PGE2 quantification. Platelet function tests were carried out before and during treatment and TXB2 release on platelet rich plasma was measured. The every 3 day low-dose acetylsalicylic acid regimen produced complete inhibition of platelet aggregation compared to the daily treatment. Thromboxane B2 release was substantially abolished for both groups during treatment. There was no significant difference on the endoscopic score of both treatment groups after the 30-day treatment (P = .215). There was over 50% suppression of antrum PGE2 content on volunteers receiving acetylsalicylic acid daily (P = .0016), while for the every 3 day dose regimen there was no significant difference between pre and post-treatment antrum PGE2 dosages (P = .4193). Since PGE2 is involved in gastric healing, we understand that this new approach could be safer and as efficient as the standard daily therapy on a long-term basis.

  19. Argan oil prevents prothrombotic complications by lowering lipid levels and platelet aggregation, enhancing oxidative status in dyslipidemic patients from the area of Rabat (Morocco)

    PubMed Central

    2013-01-01

    Background It is now established that patients with hyperlipidemia have a high risk of atherosclerosis and thrombotic complications, which are two important events responsible for the onset and progression of cardiovascular disease. In the context of managing dyslipidemia by means of dietary advice based on the consumption of argan oil, we wanted to investigate the effect of virgin argan oil on plasma lipids, and for the first time, on the platelet hyperactivation and oxidative status associated with dyslipidemia. This study concerns patients recruited in the area of Rabat in Morocco. Methods 39 dyslipidemic (79% women) patients were recruited for our study in the area of Rabat in Morocco. They were randomly assigned to the two following groups: the argan group, in which the subjects consumed 25 mL/day of argan oil at breakfast for 3 weeks, and the control group in which argan oil was replaced by butter. Results After a 3-week consumption period, blood total cholesterol was significantly lower in the argan oil group, as was LDL cholesterol (23.8% and 25.6% lower, respectively). However, the HDL cholesterol level had increased by 26% at the end of the intervention period compared to baseline. Interestingly, in the argan oil group thrombin-induced platelet aggregation was lower, and oxidative status was enhanced as a result of lower platelet MDA and higher GPx activity, respectively. Conclusions In conclusion, our results, even if it is not representative of the Moroccan population, show that argan oil can prevent the prothrombotic complications associated with dyslipidemia, which are a major risk factor for cardiovascular disease. PMID:23870174

  20. Purification and characterization of a platelet aggregation inhibitor acidic phospholipase A2 from Indian saw-scaled viper (Echis carinatus) venom.

    PubMed

    Kemparaju, K; Krishnakanth, T P; Veerabasappa Gowda, T

    1999-12-01

    An acidic phospholipase A2 (EC-I-PLA2) has been purified from the Indian saw-scaled viper (Echis carinatus) venom through a combination of column chromatography and electrophoresis. EC-I-PLA2 has a molecular weight of 16000 by SDS-PAGE. It was focussed between pH 4.2 and 4.8 by isoelectro focussing. EC-I-PLA2 was non-lethal to mice and devoid of neurotoxicity, myotoxicity, anticoagulant activity and cytotoxicity. It induced mild oedema in the foot pads of mice. The purified PLA2 inhibited ADP, collagen and epinephrine induced human platelet aggregation and the inhibition was both dose and time dependent. PMID:10519645

  1. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb.

    PubMed

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

    2012-03-01

    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.

  2. 2-Alkynyl derivatives of adenosine-5'-N-ethyluronamide: selective A2 adenosine receptor agonists with potent inhibitory activity on platelet aggregation.

    PubMed

    Cristalli, G; Volpini, R; Vittori, S; Camaioni, E; Monopoli, A; Conti, A; Dionisotti, S; Zocchi, C; Ongini, E

    1994-05-27

    A series of new 2-alkynyl and 2-cycloalkynyl derivatives of adenosine-5'-N-ethyluronamide (NECA) and of N-ethyl-1'-deoxy-1'-(6-amino-2-hexynyl-9H-purin-9-yl)-beta-D- ribofuranuronamide (1, HE-NECA), bearing hydroxy, amino, chloro, and cyano groups in the side chain, were synthesized. The compounds were studied in binding and functional assays to assess their potency for the A2 compared to A1 adenosine receptor. The presence of an alpha-hydroxyl group in the alkynyl chain of NECA derivatives accounts for the A2 agonist potency, leading to compounds endowed with sub-nanomolar affinity in binding studies. However, these analogues also possess good A1 receptor affinity resulting in low A2 selectivity. From functional experiments the 4-hydroxy-1-butynyl (6) and the 4-(2-tetrahydro-2H-pyranyloxy)-1-butynyl (16) derivatives appear to be very potent in inducing vasorelaxation without appreciable effect on heart rate. The new compounds were also tested as inhibitors of platelet aggregation induced by ADP. Introduction of an alpha-hydroxyl group in the alkynyl side chain caused a greater increase in antiaggregatory activity than either NECA or HE-NECA, resulting in the most potent inhibitors of platelet aggregation so far known in the nucleoside series. The presence of an alpha-quaternary carbon such as the 3-hydroxy-3,5-dimethyl-1-hexynyl (12) and the 3-hydroxy-3-phenyl-1-butynyl (15) derivatives markedly reduced the antiaggregatory potency without affecting the A2 affinity. The hydrophobicity index (k') of the new nucleosides barely correlated with the binding data, whereas high k' values were associated with increased A2 vs A1 selectivity but with reduced activity in all functional assays. Some of the compounds synthesized possess interesting pharmacological properties. Compounds having an appropriate balance between vasorelaxation and antiplatelet activity, if confirmed in vivo, deserve further development for the treatments of cardiovascular disorders.

  3. Subpopulations in purified platelets adhering on glass.

    PubMed

    Donati, Alessia; Gupta, Swati; Reviakine, Ilya

    2016-01-01

    Understanding how platelet activation is regulated is important in the context of cardiovascular disorders and their management with antiplatelet therapy. Recent evidence points to different platelet subpopulations performing different functions. In particular, procoagulant and aggregating subpopulations have been reported in the literature in platelets treated with the GPVI agonists. How the formation of platelet subpopulations upon activation is regulated remains unclear. Here, it is shown that procoagulant and aggregating platelet subpopulations arise spontaneously upon adhesion of purified platelets on clean glass surfaces. Calcium ionophore treatment of the adhering platelets resulted in one platelet population expressing both the procoagulant and the adherent population markers phosphatidylserine and the activated form of GPIIb/IIIa, while all of the platelets expressed CD62P independently of the ionophore treatment. Therefore, all platelets have the capacity to express all three activation markers. It is concluded that platelet subpopulations observed in various studies reflect the dynamics of the platelet activation process. PMID:27338300

  4. Ticagrelor--a new platelet aggregation inhibitor in patients with acute coronary syndromes. An improvement of other inhibitors?

    PubMed

    Kowalczyk, Mariusz; Banach, Maciej; Mikhailidis, Dimitri P; Hannam, Simon; Rysz, Jacek

    2009-12-01

    Antiplatelet agents play an essential role in the treatment of acute coronary syndrome (ACS). Thienopyridines are a class of drugs that function via inhibition of the adenosine diphosphate (ADP) P2Y12 platelet receptors. Currently, clopidogrel, a second generation thienopyridine, is the main drug of choice and the combination of aspirin and clopidogrel is administered orally for the treatment of ACS. Clopidogrel, is a pro-drug that needs to be metabolized in the liver and intestines to form active metabolites. Prasugrel, a third generation thienopyridine, was approved for use in Europe in February 2009, and is currently available in the United Kingdom. All thienopyridines however, have pharmacological limitations that lead to a search for more effective non-thienopyridine P2Y12 inhibitors. Promising results have been reported with ticagrelor, an oral first reversible, direct-acting inhibitor of the P2Y12 receptor. Ticagrelor is the first oral P2Y12 receptor binding antagonist that does not require metabolic activation. Furthermore, ticagrelor has at last 1 active metabolite, which has very similar pharmacokinetics to the parent compound. Therefore, ticagrelor has more rapid onset and more pronounced platelet inhibition than other antiplatelet agents. The safety and efficacy of ticagrelor compared with clopidogrel in ACS patient has been recently evaluated by the PLATelet inhibition and patient Outcomes (PLATO) trial. Ticagrelor compared with clopidogrel had a significantly greater reduction in the death rate from vascular causes, myocardial infarction, or stroke without major bleeding. There was however, an increase in non-procedure related bleeding, dyspnoea and ventricular pauses in the first week of treatment. Further studies on new antiplatelet agents are needed to establish a new "gold standard" antiplatelet therapy. PMID:19946242

  5. Enzymatic synthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, a hypotensive and platelet-aggregating lipid

    SciTech Connect

    Wykle, R.L.; Malone, B.; Snyder, F.

    1980-01-01

    1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine, derived chemically from choline plasmalogens of beef heart, has been shown to possess powerful antihypertensive activity and to be an extremely potent platelet-activating factor. In the present study, microsomal preparations of rat spleen were shown to synthesize 1-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine by an acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase reaction; the acetyltransferase appears to be different from the acyltransferase responsible for the transfer of palmitate to glycerolipids.

  6. [THE REFERENCE VALUES OF AGGREGATION OF PLATELETS IN ADULT POPULATION OF THE ASTRAKHAN OBLAST USING AGGREGOMETER MULTIPLATE].

    PubMed

    Petrova, O V; Shashin, S A; Tarasov, D G; Jukova, E R; Panova, E V; Gracheva, N P

    2016-01-01

    The modern international standards recommend each laboratory to develop or to confirm available in literature the reference intervalsfor every laboratory indicator In the Astrakhanskaia oblast, sampling of128 healthy males andfemales were examinedfor aggregation function of thrombocytes using impedance technique and applying aggregometer Multiplate ("Verum Diagnostica", Germany). The study used as inductors peptide activating receptor of thrombin; arachidonic and adenosine diphosphoric acids. The reference range of aggregation of thrombocytes with peptide activating receptor of thrombin, at aggregometer Multiplate, in healthy population of theAstrakhanskaia oblast made up to 815.2-1498.4 AU/min, with arachidonic acid--660-1341 AU/min. with adenosine diphosphoric acid--598-1120 AU/min. PMID:27183729

  7. 2-(2-Br-phenyl)-8-methoxy-benzoxazinone (HPW-RX2), a direct thrombin inhibitor with a suppressive effect on thromboxane formation in platelets.

    PubMed

    Wu, Chin-Chung; Wang, Tsai-Wei; Wang, Wei-Ya; Hsieh, Pei-Wen; Wu, Yang-Chang

    2005-12-19

    2-(2-Br-phenyl)-8-methoxy-benzoxazinone (HPW-RX2), a newly synthetic benzoxazinone derivative, has previously been shown to inhibit rabbit platelet aggregation caused by thrombin and arachidonic acid. In the present study, the mechanism for the antiplatelet effect of HPW-RX2 was further investigated. In human platelets, HPW-RX2 concentration-dependently inhibited platelet aggregation, ATP release, P-selectin expression, and intracellular calcium mobilization caused by thrombin. In contrast, HPW-RX2 had no significant effect on either SFLLRN- or GYPGKF-induced platelet aggregation, indicating that HPW-RX2 did not interfere with platelet thrombin receptors. Moreover, HPW-RX2 inhibited the amidolytic activity of thrombin and prolonged the fibrinogen clotting time. These results suggest that the inhibitory effect of HPW-RX2 on thrombin-induced platelet aggregation is via direct inhibition of thrombin proteolytic activity. Besides the inhibition on thrombin, HPW-RX2 also prevented platelet aggregation, ATP release, and increase in [Ca2+]i caused by arachidonic acid and low concentration collagen. In a parallel manner, both arachidonic acid-induced thromboxane B2 and prostaglandin D2 formations were decreased in platelets treated with HPW-RX2. This indicates that HPW-RX2 is able to inhibit the arachidonic acid cascade at the cyclooxygenase level. This is the first report of a benzoxazinone derivative possessing both thrombin and cyclooxygenase inhibitory properties. The dual effect of HPW-RX2 might provide extra therapeutic benefits for treatment of arterial thrombosis. PMID:16313903

  8. Anti-platelet activity of water dispersible curcuminoids in rat platelets.

    PubMed

    Maheswaraiah, Anikisetty; Rao, Lingamallu Jaganmohan; Naidu, Kamatham Akhilender

    2015-03-01

    Curcuminoids are active principle of turmeric with plethora of health beneficial properties. In this study, we have evaluated for the first time the effect of water dispersible curcuminoids on rat platelet aggregation. Curcuminoids (10-30 µg/mL) significantly inhibited platelet aggregation induced by agonists viz., collagen, ADP and arachidonic acid. Curcuminoids were found to be two-fold more potent than curcumin in inhibiting platelet aggregation. Intracellular curcuminoid concentration was relatively higher than curcumin in rat platelets. Curcuminoids significantly attenuated thromboxane A2 , serotonin levels in rat platelets which play an important role in platelet aggregation. Curcuminoid treatment increased nitric oxide (NO) levels in platelets treated with agonists. Curcuminoids inhibited free radicals such as superoxide anion released from activated platelets, which ultimately inhibits platelet aggregation. Further, curcuminoids inhibited 12-lipoxygenase activity and formation of 12-hydroperoxyeicosatetraenoic acid (12-HPETE) in activated rat platelets which regulates platelet aggregation. The results suggest that curcuminoids have remarkable anti-platelet activity by modulating multiple mechanisms involved in platelet aggregation. Thus curcuminoids may have a therapeutic potential to prevent platelet activation related disorders.

  9. Effects of green tea or Sasa quelpaertensis bamboo leaves on plasma and liver lipids, erythrocyte Na efflux, and platelet aggregation in ovariectomized rats.

    PubMed

    Ryou, Sung Hee; Kang, Min Sook; Kim, Kyu Il; Kang, Young Hee; Kang, Jung Sook

    2012-04-01

    This study was conducted to investigate the effects of Sasa quelpaertensis bamboo and green tea on plasma and liver lipids, platelet aggregation, and erythrocyte membrane Na channels in ovariectomized (OVX) rats. Thirty female rats were OVX, and ten female rats were sham-operated at the age of 6 weeks. The rats were divided into four groups at the age of 10 weeks and fed the experiment diets: sham-control, OVX-control, OVX-bamboo leaves (10%), or OVX-green tea leaves (10%) for four weeks. Final body weight increased significantly in the OVX groups compared with that in the sham-control, whereas body weight in the OVX-green tea group decreased significantly compared with that in the OVX-control (P < 0.01). High density lipoprotein (HDL)-cholesterol level decreased in all OVX groups compared with that in the sham-control rats (P < 0.05) but without a difference in plasma total cholesterol. Plasma triglycerides in the OVX-green tea group were significantly lower than those in the sham-control or OVX-control group (P < 0.05). Liver triglycerides increased significantly in the OVX-control compared with those in the sham-control (P < 0.01) but decreased significantly in the OVX-green tea group compared with those in the OVX-control or OVX-bamboo group (P < 0.01). Platelet aggregation in both maximum and initial slope tended to be lower in all OVX rats compared with that in the sham-control rats but was not significantly different. Na-K ATPase tended to increase and Na-K cotransport tended to decrease following ovariectomy. Na-K ATPase decreased significantly in the OVX-green tea group compared with that in the OVX-control group (P < 0.01), and Na-K cotransport increased significantly in the OVX-bamboo and OVX-green tea groups compared with that in the OVX-control (P < 0.05). Femoral bone mineral density tended to be lower in OVX rats than that in the sham-control, whereas the green tea and bamboo leaves groups recovered bone density to some extent. The results show that

  10. Platelet function defects in chronic alcoholism.

    PubMed Central

    Mikhailidis, D P; Jenkins, W J; Barradas, M A; Jeremy, J Y; Dandona, P

    1986-01-01

    Platelet function in alcoholic patients was assessed on admission and during abstinence in hospital. On admission platelets from these patients were significantly less responsive (percentage aggregation and thromboxane A2 release) to conventional in vitro aggregating agents (adrenaline, adenosine diphosphate, and collagen) than platelets from healthy, moderate drinkers. Initially, platelet counts in platelet rich plasma tended to be low and the Simplate II bleeding times frequently prolonged. Platelet aggregation and thromboxane A2 release, however, were inhibited even in patients with normal platelet counts on admission. Platelet aggregation and thromboxane A2 release returned to normal or became hyper-responsive during two to three weeks of abstinence. Platelet counts rose during this period, the largest responses occurring in those patients with the lowest counts on admission. Bleeding times reverted to normal during abstinence and correlated significantly with changes in platelet aggregation, thromboxane A2 release, and platelet count and with the estimated ethanol consumption during the week before admission. Chronic, heavy alcohol ingestion evidently exerts an inhibitory effect on platelet function even in the absence of alcohol in the blood, and this phenomenon is reversible on abstaining. The impaired platelet function, together with the reduced platelet count, may contribute to the bleeding diathesis associated with chronic alcoholism and to the increased incidence and recurrence of gastrointestinal haemorrhage associated with excessive alcohol intake. PMID:3094624

  11. Drug/drug interaction of common NSAIDs with antiplatelet effect of aspirin in human platelets.

    PubMed

    Saxena, Aaruni; Balaramnavar, Vishal M; Hohlfeld, Thomas; Saxena, Anil K

    2013-12-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with the anti-platelet activity of aspirin at the level of the platelet cyclooxygenase-1 (COX-1) enzyme. In order to examine the interference of common NSAIDs with the anti-platelet activity of aspirin the human platelet rich plasma from voluntary donors was used for arachidonic acid-induced aggregation and determination of thromboxane synthesis. Further, docking studies were used to explain the molecular basis of the NSAID/aspirin interaction. The experimental results showed that celecoxib, dipyrone (active metabolite), ibuprofen, flufenamic acid, naproxen, nimesulide, oxaprozin, and piroxicam significantly interfere with the anti-platelet activity of aspirin, while diclofenac, ketorolac and acetaminophen do not. Docking studies suggested that NSAIDs forming hydrogen bonds with Ser530, Arg120, Tyr385 and other amino acids of the COX-1 hydrophobic channel interfere with antiplatelet activity of aspirin while non interfering NSAIDs do not form relevant hydrogen bond interactions within the aspirin binding site. In conclusion, docking analysis of NSAID interactions at the COX-1 active site appears useful to predict their interference with the anti-platelet activity of aspirin. The results, demonstrate that some NSAIDs do not interfere with the antiplatelet action of aspirin while many others do and provide a basis for understanding the observed differences among individual non-aspirin NSAIDs. PMID:24075938

  12. A randomised determination of the Effect of Fluvastatin and Atorvastatin on top of dual antiplatelet treatment on platelet aggregation after implantation of coronary drug-eluting stents. The EFA-Trial.

    PubMed

    Wenaweser, Peter; Eshtehardi, Parham; Abrecht, Linda; Zwahlen, Marcel; Schmidlin, Kurt; Windecker, Stephan; Meier, Bernhard; Haeberli, Andre; Hess, Otto M

    2010-09-01

    Drug-drug interaction between statins metabolised by cytochrome P450 3A4 and clopidogrel have been claimed to attenuate the inhibitory effect of clopidogrel. However, published data regarding this drug-drug interaction are controversial. We aimed to determine the effect of fluvastatin and atorvastatin on the inhibitory effect of dual antiplatelet therapy with acetylsalicylic acid (ASA) and clopidogrel. One hundred one patients with symptomatic stable coronary artery disease undergoing percutaneous coronary intervention and drug-eluting stent implantation were enrolled in this prospective randomised study. After an interval of two weeks under dual antiplatelet therapy with ASA and clopidogrel, without any lipid-lowering drug, 87 patients were randomised to receive a treatment with either fluvastatin 80 mg daily or atorvastatin 40 mg daily in addition to the dual antiplatelet therapy for one month. Platelet aggregation was assessed using light transmission aggregometry and whole blood impedance platelet aggregometry prior to randomisation and after one month of receiving assigned statin and dual antiplatelet treatment. Platelet function assessment after one month of statin and dual antiplatelet therapy did not show a significant change in platelet aggregation from 1st to 2nd assessment for either statin group. There was also no difference between atorvastatin and fluvastatin treatment arms. In conclusion, neither atorvastatin 40 mg daily nor fluvastatin 80 mg daily administered in combination with standard dual antiplatelet therapy following coronary drug-eluting stent implantation significantly interfere with the antiaggregatory effect of ASA and clopidogrel.

  13. Isolation, functional characterization and proteomic identification of CC2-PLA₂ from Cerastes cerastes venom: a basic platelet-aggregation-inhibiting factor.

    PubMed

    Chérifi, Fatah; Namane, Abdelkader; Laraba-Djebari, Fatima

    2014-02-01

    Three-step chromatography and proteomic analysis have been used to purify and characterize a new basic phospholipase A₂ named CC2-PLA₂ from the venom of Cerastes cerastes. This phospholipase A₂ has been isolated to an extent of about 50-folds and its molecular weight was estimated at 13,534 Da. For CC2-PLA₂ identification and LC-MALDI-MS/MS analysis, the protein was reduced, alkylated and double hydrolyzed by lysine-C endopeptidase and trypsin. Tryptic fragments of LC-MS/MS analyzed CC2-PLA₂ showed sequence similarities with other snake venom PLA₂. This presents only 51 % (61/120 amino acid residues) sequence homology with the first PLA₂ (gi |129506|) previously purified from the same venom. The isolated CC2-PLA₂ displayed anti-aggregative effect on platelets and induced an inflammatory response characterized by leukocytosis in the peripheral blood. This inflammatory response is accompanied by a release of inflammatory mediators such as IL-6, eosinophil peroxidase and complement system. Obtained results indicate that CC2-PLA₂ induced a release of high level of pro-inflammatory (IL-6) cytokine and no effect on the level of anti-inflammatory cytokine (IL-10) in blood sera. Furthermore, eosinophil peroxidase activity and hemolytic complement effect increased in peripheral blood. Mononuclear and neutrophil cells were found predominant in the induced leucocytosis following CC2-PLA₂ administration into animals.

  14. An efficient and safe process for the preparation of ticagrelor, a platelet aggregation inhibitor via resin-NO2 catalyzed formation of triazole ring.

    PubMed

    Shinde, Gorakshanath B; Mahale, Pravin K; Padaki, Santhosh A; Niphade, Navnath C; Toche, Raghunath B; Mathad, Vijayavitthal T

    2015-01-01

    An efficient, safe and improved process for the preparation of ticagrelor 1, a platelet aggregation inhibitor is described. Synthesis comprises the condensation of pyrimidine amine derivative 14 with cyclopentyl derivative 13 in ethylene glycol followed by construction of triazole compound 16 by diazotization of the obtained intermediate 15 with a green and safer reagent "Resin-NO2" in water and acetonitrile mixture. Condensation of 16 with cyclopropylamine derivative 10 followed by deprotection of compound 12 with hydrochloric acid in dichloromethane (DCM) furnished ticagrelor 1 with an overall yield of 65 % and purity of 99.78 % by HPLC. Each reaction stage was optimized independently to establish the scalable and plant friendly process. An efficient and a safe process for key intermediate 14 which involve nitration reaction has also been developed. Safety parameters were established by understanding the thermal events of the reaction by DSC analysis.Graphical abstractSynthesis of ticagrelor via resin-NO2 catalysed formation of triazole ring. PMID:26389018

  15. Higher levels of circulating monocyte-platelet aggregates are correlated with viremia and increased sCD163 levels in HIV-1 infection.

    PubMed

    Liang, Hua; Duan, Zhaojun; Li, Dan; Li, Dongliang; Wang, Zheng; Ren, Li; Shen, Tao; Shao, Yiming

    2015-07-01

    Increased levels of monocyte-platelet aggregates (MPAs) are reported to be highly correlated with cardiovascular events. In this study, the MPA levels in different monocyte subsets and the associations between MPA levels, HIV-1 viremia and monocyte activation were evaluated during HIV-1 infection. The results showed that the percentages of MPAs in all three monocyte subsets were higher in HIV-1-infected subjects than in healthy controls, and were associated with the plasma viral load in the non-classical and intermediate monocyte subsets. The plasma levels of sCD14 and sCD163 were upregulated in HIV-1 infection and were positively associated with viral loads and negatively associated with CD4 counts. P-selectin glycoprotein ligand-1 (PSGL-1) was shown to be expressed at significantly lower levels on all three monocyte subsets and was negatively correlated with the sCD163 level. The MPA level was correlated with the levels of plasma sCD163 but negatively correlated with CD163 and PSGL-1 on all three monocyte subsets. An elevated immune activation status was correlated with increased MPA formation, underlying the potential interaction between monocyte activation and MPA formation. This interaction may be related to a higher thromboembolic risk in patients infected with HIV-1.Cellular & Molecular Immunology advance online publication, 11 August 2014; doi:10.1038/cmi.2014.66.

  16. Purification and characterization of AHPM, a novel non-hemorrhagic P-IIIc metalloproteinase with α-fibrinogenolytic and platelet aggregation-inhibition activities, from Agkistrodon halys pallas venom.

    PubMed

    Song, Jiajia; Xu, Xiaolong; Zhang, Yan; Guo, Mingchun; Yan, Xincheng; Wang, Shasha; Gao, Shang

    2013-04-01

    A novel non-hemorrhagic metalloproteinase, AHPM, was purified from the venom of Agkistrodon halys pallas by a combination of ion-exchange and gel filtration chromatography. AHPM is a dimeric glycoprotein with multiple pIs around pH 7.9 and has a molecular mass of 110 kDa with two blocked N-terminuses. Partial sequence of AHPM obtained by LC-MS/MS analysis together with its dimeric nature reveals that it is a P-IIIc snake venom metalloproteinase composed of metalloproteinase, disintegrin-like and cysteine-rich domains. AHPM has a conserved DECD sequence in the disintegrin-like domain. AHPM hydrolyzes casein and fibrinogen and also dissolves fibrin clots and the proteolytic activity is abolished by EDTA, but not by PMSF, suggesting that it is a metalloproteinase. The protease hydrolyzes rapidly the Aα-chain of fibrinogen followed by the Bβ-chain and does not cleave the γ-chain. AHPM contains endogenous Zn(2+) and Ca(2+) ions at a molar ratio of 1:1.9 and 1:4.2, respectively, and Zn(2+) ions are essential for its proteolytic activity. AHPM inhibits collagen-and ADP-induced platelet aggregation with half maximal inhibitory concentrations of 200 ± 8 nM and 280 ± 10 nM, respectively. EDTA markedly attenuates the inhibition of ADP-induced platelet aggregation by AHPM, indicating that the fibrinogenolytic activity of AHPM is involved in its inhibition of ADP-induced platelet aggregation. AHPM is devoid of hemorrhagic activity when injected (up to 30 μg) subcutaneously into mice. AHPM is so far identified as first non-hemorrhagic P-IIIc SVMP which has both fibrinolytic and platelet aggregation-inhibition activities. The bifunctional enzyme may have a potential clinical application as a thrombolytic agent. PMID:23104267

  17. Schistosomes versus platelets.

    PubMed

    Da'dara, Akram A; Skelly, Patrick J

    2014-12-01

    Schistosomes are parasitic platyhelminths that currently infect >200million people and cause the chronic debilitating disease schistosomiasis. While these large intravascular parasites can disturb blood flow, they do not appear to activate platelets and provoke thrombus formation. Host-interactive tegumental molecules have been proposed to be important in this regard. For example, tegumental apyrase, SmATPDase1 can degrade the platelet-activating molecule ADP in the extracellular environment. The parasites themselves can produce prostaglandins (or may induce prostaglandin production by host cells) which could inhibit platelet aggregation. Additional tegumental proteins have been proposed to impede the coagulation cascade and to promote fibrinolysis. Platelets have been shown to be directly toxic to schistosomes. Platelets recovered from infected rats are able to kill larval parasites in culture and platelets obtained at later times post-infection are generally better at killing. Even platelets from uninfected rats can rapidly kill larval schistosomes if first exposed to a variety of activators (such as: serum from infected rats, the IgE fraction of that serum, C-reactive protein, cytokines (TNFα or TNFβ)). Passive transfer of stimulated platelets can protect rats against a challenge schistosome infection. Cytokines (TNFα, TNFβ, IFNγ or IL-6) have been shown to similarly promote normal human platelet killing of schistosomes in vitro. Platelet antimicrobial effector molecules (e.g. platelet microbicidal proteins) may mediate such killing. While platelets can be protective against schistosomes following infection of humans and mice, platelet numbers decline (but not so in the non-permissive rat host) and coagulopathy becomes more apparent as schistosome-induced pathology increases.

  18. Betaine (N,N,N-trimethylglycine) averts photochemically-induced thrombosis in pial microvessels in vivo and platelet aggregation in vitro

    PubMed Central

    Yuvaraju, Priya; Beegam, Sumaya; Ali, Badreldin H

    2015-01-01

    Betaine (N,N,N-trimethylglycine) is an important food component with established health benefits through its homocysteine-lowering effects, and is used to lower total homocysteine concentration in plasma of patients with homocystinuria. It is well established that hyperhomocysteinemia is an established risk factor for cardiovascular disease and stroke. However, the possible protective effect of betaine on coagulation events in vivo and in vitro has thus far not been studied. Betaine was given to mice at oral doses of either 10 mg/kg (n = 6) or 40 mg/kg (n = 6) for seven consecutive days, and control mice (n = 6) received water only. The thrombotic occlusion time in photochemically induced thrombosis in pial arterioles was significantly delayed in mice pretreated with betaine at doses of 10 mg/kg (P < 0.001) and 40 mg/kg (P < 0.01). Similar effects were observed in pial venules with 10 mg/kg (P < 0.05) and 40 mg/kg (P < 0.05) betaine. In vitro, in whole blood samples collected from untreated mice (n = 3–5), betaine (0.01–1 mg/mL) significantly reversed platelet aggregation induced by adenosine diphosphate (5 µM). The number of circulating platelets and plasma concentration of fibrinogen in vivo were not significantly affected by betaine pretreament compared with the control group. Lipid peroxidation (LPO) in mice pretreated with betaine was significantly reduced compared with the control group. Moreover, betaine (0.01–1 mg/mL) caused a dose-dependent and significant prolongation of PT (n = 5) and aPTT (n = 4–6). In conclusion, our data show that betaine protected against coagulation events in vivo and in vitro and decreased LPO in plasma. PMID:25662827

  19. Betaine (N,N,N-trimethylglycine) averts photochemically-induced thrombosis in pial microvessels in vivo and platelet aggregation in vitro.

    PubMed

    Nemmar, Abderrahim; Yuvaraju, Priya; Beegam, Sumaya; Ali, Badreldin H

    2015-07-01

    Betaine (N,N,N-trimethylglycine) is an important food component with established health benefits through its homocysteine-lowering effects, and is used to lower total homocysteine concentration in plasma of patients with homocystinuria. It is well established that hyperhomocysteinemia is an established risk factor for cardiovascular disease and stroke. However, the possible protective effect of betaine on coagulation events in vivo and in vitro has thus far not been studied. Betaine was given to mice at oral doses of either 10 mg/kg (n = 6) or 40 mg/kg (n = 6) for seven consecutive days, and control mice (n = 6) received water only. The thrombotic occlusion time in photochemically induced thrombosis in pial arterioles was significantly delayed in mice pretreated with betaine at doses of 10 mg/kg (P < 0.001) and 40 mg/kg (P < 0.01). Similar effects were observed in pial venules with 10 mg/kg (P < 0.05) and 40 mg/kg (P < 0.05) betaine. In vitro, in whole blood samples collected from untreated mice (n = 3-5), betaine (0.01-1 mg/mL) significantly reversed platelet aggregation induced by adenosine diphosphate (5 µM). The number of circulating platelets and plasma concentration of fibrinogen in vivo were not significantly affected by betaine pretreament compared with the control group. Lipid peroxidation (LPO) in mice pretreated with betaine was significantly reduced compared with the control group. Moreover, betaine (0.01-1 mg/mL) caused a dose-dependent and significant prolongation of PT (n = 5) and aPTT (n = 4-6). In conclusion, our data show that betaine protected against coagulation events in vivo and in vitro and decreased LPO in plasma.

  20. Nutritional zinc increases platelet reactivity.

    PubMed

    Marx, G; Krugliak, J; Shaklai, M

    1991-11-01

    After ingestion of 220 mg zinc sulfate, platelet aggregation was evaluated at various time intervals (i.e., T = 0, 1, and 3 hr) and the autologous plasma analyzed by atomic absorption analysis. The zinc levels increased maximally some 0.4 +/- 0.2 microgram/ml within 3 hr after ingestion, which for the entire blood pool corresponds to only 5% of the ingested zinc. Aggregation responses of platelet rich plasma (PRP), instigated with suboptimal levels of thrombin (less than 0.2 U/ml), ADP (less than 2 microM), epinephrine (less than 2 microM), collagen (less than 2 micrograms/ml), or PAF (less than 50 ng/ml), show significant improvement to at least one aggregant. Mean +/- SEM values for delta % aggregation increase are as follows: thrombin, 51 +/- 10%; epinephrine, 21 +/- 6%; ADP, 31 +/- 6%; collagen 23 +/- 6%; and platelet aggregating factor (PAF), 56 +/- 6%. For controls, the platelets from one individual with Glanzmann thrombasthenia as well as four undosed volunteers exhibited no significant changes in platelet responsiveness. Increased platelet responsiveness to agonists after zinc sulfate ingestion was observed in PRP from blood collected in either citrate or heparin. We demonstrate that within a relatively short time period, single bolus of nutritional zinc intake can significantly increase platelet reactivity. These findings show that nutritional zinc availability is relevant to hemostasis and may pertain to the viability of platelet concentrates in blood banks.

  1. Albocollagenase, a novel recombinant P-III snake venom metalloproteinase from green pit viper (Cryptelytrops albolabris), digests collagen and inhibits platelet aggregation.

    PubMed

    Pinyachat, Anuwat; Rojnuckarin, Ponlapat; Muanpasitporn, Chuanchom; Singhamatr, Pon; Nuchprayoon, Surang

    2011-04-01

    Molecular cloning and functional characterization of P-III snake venom metalloproteinases (SVMPs) will give us deeper insights in the pathogenesis of viper bites. This may lead to novel therapy for venom-induced local tissue damages, the complication refractory to current antivenom. The aim of this study was to elucidate the in vitro activities of a new SVMP from the green pit viper (GPV) using recombinant DNA technology. We report, here, a new cDNA clone from GPV (Cryptelytrops albolabris) venom glands encoding 614 amino acid residues P-III SVMP, termed albocollagenase. The conceptually translated protein comprised a signal peptide and prodomain, followed by a metalloproteinase domain containing a zinc-binding motifs, HEXGHXXGXXH-CIM and 9 cysteine residues. The disintegrin-like and cysteine-rich domains possessed 24 cysteines and a DCD (Asp-Cys-Asp) motif. The albocollagenase deduced amino acid sequence alignments showed approximately 70% identity with other P-III SVMPs. Notably, the prodomain was highly conserved, while the metalloproteinase, disintegrin-like and cysteine-rich domains contained several differences. Albocollagenase without the signal peptide and prodomain was expressed in Pichia pastoris with an N-terminal six-histidine tag. After affinity purification from the supernatant of methanol-induced media, SDS-PAGE and Western blot analysis in both reducing and non-reducing conditions showed a protein band of approximately 62 kDa. The recombinant albocollagenase could digest human type IV collagen from human placenta basement membrane within 1 min. After 10-min incubation, it also inhibited collagen-induced platelet aggregation with 50% inhibitory concentration (IC₅₀) of 70 nM. This is the first report of the active recombinant SVMP enzymes expressed in P. pastoris. The results suggest the significant roles of P-III SVMP in local and systemic pathology of envenomated patients. Inhibitors of this SVMP will be investigated in further studies to find a

  2. Immunohistochemical Evaluation of Fibronectin and Tenascin Following Direct Pulp Capping with Mineral Trioxide Aggregate, Platelet-Rich Plasma and Propolis in Dogs’ Teeth

    PubMed Central

    Moradi, Saeed; Saghravanian, Nasrollah; Moushekhian, Siavash; Fatemi, Samar; Forghani, Maryam

    2015-01-01

    Introduction: The aim of the present study was to evaluate the expression of fibronectin (FN) and tenascin (TN) after direct pulp capping (DPC) in dogs’ teeth with either mineral trioxide aggregate (MTA), Propolis or Platelet-rich plasma (PRP), by means of immunohistochemistry. Methods and Materials: A total of 48 sound molars and premolars with mature apices from four dogs, were included. The teeth were randomly divided into 4 groups according to the material used for DPC: PRP, Propolis, MTA, and glass-ionomer (as the negative control group). Each group was divided into two 7-day and 30-day subgroups. The teeth were restored at the same session. The animals were sacrificed at the mentioned time intervals and the expression of FN and TN in each test group and between each time intervals was assessed with Wilcoxon and Mann-Whitney U tests, respectively. The Kruskal-Wallis test was used to compare FN and TN staining among the test groups. The significance level was set at 0.05. Results: The amount of FN in the MTA group in the 30-day interval was significantly higher than the 7-day interval; however, there were no significant differences among the other groups. The amount of TN in the MTA and Propolis groups in the 30-day interval was significantly higher than that in the 7-day interval; no recognizable difference was observed in the other groups. Moreover, the difference in expression of FN and TN in the 7-day interval was not significant in the experimental groups. Nevertheless, the difference was significant in the 30-day interval, with the highest and lowest expressions belonging to the MTA and glass-ionomer groups, respectively. Conclusion: Based on the results of the present animal study, MTA is still a better choice for direct pulp capping PMID:26213542

  3. Isolation and characterization of two disintegrins inhibiting ADP-induced human platelet aggregation from the venom of Crotalus scutulatus scutulatus (Mohave Rattlesnake)

    SciTech Connect

    Sanchez, Elda E.; Galan, Jacob A.; Russell, William K.; Soto, Julio G.; Russell, David H.; Perez, John C. . E-mail: kfjcp00@tamuk.edu

    2006-04-01

    Disintegrins and disintegrin-like proteins are molecules found in the venom of four snake families (Atractaspididae, Elapidae, Viperidae, and Colubridae). The disintegrins are nonenzymatic proteins that inhibit cell-cell interactions, cell-matrix interactions, and signal transduction, and may have potential in the treatment of strokes, heart attacks, cancers, and osteoporosis. Prior to 1983, the venom of Crotalus scutulatus scutulatus (Mohave Rattlesnake) was known to be only neurotoxic; however, now there is evidence that these snakes can contain venom with: (1) neurotoxins; (2) hemorrhagins; and (3) both neurotoxins and hemorrhagins. In this study, two disintegrins, mojastin 1 and mojastin 2, from the venom of a Mohave rattlesnake collected in central Arizona (Pinal County), were isolated and characterized. The disintegrins in these venoms were identified by mass-analyzed laser desorption ionization/time-of-flight/time-of-flight (MALDI/TOF/TOF) mass spectrometry as having masses of 7.436 and 7.636 kDa. Their amino acid sequences are similar to crotratroxin, a disintegrin isolated from the venom of the western diamondback rattlesnake (C. atrox). The amino acid sequence of mojastin 1 was identical to the amino acid sequence of a disintegrin isolated from the venom of the Timber rattlesnake (C. horridus). The disintegrins from the Mohave rattlesnake venom were able to inhibit ADP-induced platelet aggregation in whole human blood both having IC{sub 5}s of 13.8 nM, but were not effective in inhibiting the binding of human urinary bladder carcinoma cells (T24) to fibronectin.

  4. Platelet Disorders

    MedlinePlus

    ... higher risk of blood clots. With other platelet disorders, the platelets do not work as they should. For example, in von Willebrand Disease, the platelets cannot stick together or cannot attach ...

  5. State of the Art in Platelet Function Testing

    PubMed Central

    E. Kehrel, Beate; F. Brodde, Martin

    2013-01-01

    Summary Platelets perform many functions in hemostasis but also in other areas of physiology and pathology. Therefore, it is obvious that many different function tests have been developed, each one conceived and standardized for a special purpose. This review will summarize the different fields in which platelet function testing is currently in use; diagnostics of patients with bleeding disorders, monitoring patients’ response to anti-platelet therapy, monitoring in transfusion medicine (blood donors, platelet concentrates, and after transfusion), and monitoring in perioperative medicine to predict bleeding tendency. The second part of the review outlines different methods for platelet function testing, spanning bleeding time, and platelet counting as well as determining platelet adhesion, platelet secretion, platelet aggregation, platelet morphology, platelet signal transduction, platelet procoagulant activity, platelet apoptosis, platelet proteomics, and molecular biology. PMID:23653569

  6. [Assessment of platelet function in man].

    PubMed

    Gaussem, Pascale

    2006-01-01

    Assessment of platelet function was primarily designed to explore patients with hemostatic disorders, but is becoming important for the monitoring of anti platelet agents, mostly aspirin and clopidogrel. Beside platelet counting, morphological analysis and bleeding time, a number of dedicated platelet function instruments are now available, generally allowing a rapid evaluation of platelet function in whole blood. The other tests including aggregometry and ELISA measurement of activation markers are generally restricted to specialized laboratories. Although aggregometry is still considered as the "gold standard", the recently developed flow cytometric-based platelet function analysis provides a wide choice of tests that assess the number of surface receptors, the measure of secretion and aggregation, the quantification of microparticules and leukocyte-platelet aggregates. It also allows the measure of the function of the ADP receptor P2Y12 by the phosphorylation level of the VASP protein, method currently under evaluation to monitor the platelet response to clopidogrel treatment. PMID:17243268

  7. Effect of sildenafil on platelet function and platelet cGMP of patients with erectile dysfunction.

    PubMed

    Akand, M; Gencer, E; Yaman, Ö; Erişgen, G; Tekin, D; Özdiler, E

    2015-12-01

    To investigate the effect of sildenafil on platelet function and cyclic guanosine monophosphate (cGMP) levels in patients with erectile dysfunction, we evaluated the association between erectile function and platelet responses after administration of 100 mg sildenafil. Erectile responses were monitored after 8 daily doses of the drug. Adenosine diphosphate (ADP) and collagen-induced platelet aggregation and simultaneous adenosine triphosphate (ATP) release and cGMP levels were determined before and after sildenafil therapy. Basal levels for platelet aggregation, ATP release and cGMP were compared with age-matched controls. There was no difference among basal levels of platelet responses between patients and controls, except for ADP-induced platelet aggregation (P = 0.04). It was significantly higher in the patient group. Analysis of the responses to sildenafil revealed that for the patients who showed a positive erectile response, there was a significant increase in platelet cGMP (P = 0.028) and a decrease in ADP-induced platelet aggregation (P = 0.04). However, for those who showed a negative or poor erectile response, there was no change in platelet cGMP levels and platelet functions. Sildenafil did not affect collagen-induced platelet responses although cGMP levels of the responders increased. It is concluded that sildenafil increases platelet cGMP in the patients with positive erectile response. Therefore, it has been speculated that platelet cGMP may be used as an index for erectile response.

  8. The role of platelets in inflammation.

    PubMed

    Thomas, Mark R; Storey, Robert F

    2015-08-31

    There is growing recognition of the critical role of platelets in inflammation and immune responses. Recent studies have indicated that antiplatelet medications may reduce mortality from infections and sepsis, which suggests possible clinical relevance of modifying platelet responses to inflammation. Platelets release numerous inflammatory mediators that have no known role in haemostasis. Many of these mediators modify leukocyte and endothelial responses to a range of different inflammatory stimuli. Additionally, platelets form aggregates with leukocytes and form bridges between leukocytes and endothelium, largely mediated by platelet P-selectin. Through their interactions with monocytes, neutrophils, lymphocytes and the endothelium, platelets are therefore important coordinators of inflammation and both innate and adaptive immune responses.

  9. Osmotic stability of blood platelets

    PubMed Central

    Fantl, P.

    1968-01-01

    1. Hypotonic solutions added to human platelet-containing plasma cause a transient decrease of absorbancy of light at 610 mμ which is followed by a gradual increase of absorbancy. 2. When platelets are stored for 7 hr at 4° C the absorbancy changes with variations of osmolarity and their aggregation with adenosine diphosphate (ADP) remain the same. However, the reversal of absorbancy declines during storage of platelet-containing plasma. 3. Platelets are not aggregated by stearate. Platelets appear to be only slightly affected by stearate concentration higher than 0·8 mM, but oleate has no effect. 4. Hypertonic solutions of NaCl and urea cause increase in absorbancy of platelet-containing human plasma. Hypertonic sucrose solutions produce no more change than isotonic solutions. Hypertonic NaCl produces permanent increases in absorbancy. In human platelet-containing plasma the increased absorbancy caused by hypertonic urea is transient and declines. 5. The osmotic platelet changes occur in isolated platelets as well as in platelet-containing plasma. 6. The absorbancy of frozen and thawed platelet-containing plasma is not significantly altered by hypotonic solutions but the absorbancy changes caused by hypertonic solutions are similar to that of unfrozen plasma. 7. The immediate absorbancy changes caused by hypo- and by hypertonic solutions are the same at 5° C and 30° C and are therefore probably of a physical nature. The reversal of absorbancy and aggregation of platelets by added adenosine diphosphate have Q10 > 1 and are therefore probably of a chemical-enzymic nature. 8. Divalent cations and contact activation are not required for the osmotic platelet changes and 10-3 M-Cu2+ and Zn2+ do not interfere. Inhibitors of oxidative phosphorylation, electron transfer, sodium, potassium activated adenosine triphosphatases and adenosine triphosphate do not inhibit reversal of absorbancy of platelets exposed to hypotonic solutions. Cyanide, 5 × 10-3 M, fluoride, 1

  10. Effects of LY117018 and the estrogen analogue, 17alpha-ethinylestradiol, on vascular reactivity, platelet aggregation, and lipid metabolism in the insulin-resistant JCR:LA-cp male rat: role of nitric oxide.

    PubMed

    Russell, J C; McKendrick, J D; Dubé, P J; Dolphin, P J; Radomski, M W

    2001-01-01

    The JCR:LA-cp rat is obese and insulin resistant and develops a major vasculopathy, with associated ischemic damage to the heart. Male rats were treated with 17alpha-ethinylestradiol (EE), LY117018, and/or the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). LY117018 decreased plasma cholesterol esters, with a 40% reduction in total cholesterol. EE increased triglyceride levels and modestly decreased cholesterol esters. L-NAME increased blood pressure and aortic contractile sensitivity to phenylephrine and inhibited acetylcholine-induced relaxation. LY117018 decreased the force of contraction. The L-NAME-mediated increase in force of contraction and decrease in response to acetylcholine was inhibited by LY117018. L-NAME-induced hypertension was prevented by LY117018. Platelet aggregation was not different between obese and lean rats and was unaffected by L-NAME. LY117018, both in the absence and presence of L-NAME, inhibited platelet aggregation. The effects of LY117018 are apparently mediated through both NO-dependent and -independent mechanisms. The changes induced by EE and LY117018 may reflect the activation of multiple mechanisms, both estrogen receptor-dependent and -independent. The changes induced by LY117018 are significant and may prove to be cardioprotective in the presence of the insulin resistance syndrome.

  11. Salivary Antigen-5/CAP Family Members Are Cu2+-dependent Antioxidant Enzymes That Scavenge O2⨪ and Inhibit Collagen-induced Platelet Aggregation and Neutrophil Oxidative Burst*

    PubMed Central

    Assumpção, Teresa C. F.; Ma, Dongying; Schwarz, Alexandra; Reiter, Karine; Santana, Jaime M.; Andersen, John F.; Ribeiro, José M. C.; Nardone, Glenn; Yu, Lee L.; Francischetti, Ivo M. B.

    2013-01-01

    The function of the antigen-5/CAP family of proteins found in the salivary gland of bloodsucking animals has remained elusive for decades. Antigen-5 members from the hematophagous insects Dipetalogaster maxima (DMAV) and Triatoma infestans (TIAV) were expressed and discovered to attenuate platelet aggregation, ATP secretion, and thromboxane A2 generation by low doses of collagen (<1 μg/ml) but no other agonists. DMAV did not interact with collagen, glycoprotein VI, or integrin α2β1. This inhibitory profile resembles the effects of antioxidants Cu,Zn-superoxide dismutase (Cu,Zn-SOD) in platelet function. Accordingly, DMAV was found to inhibit cytochrome c reduction by O2⨪ generated by the xanthine/xanthine oxidase, implying that it exhibits antioxidant activity. Moreover, our results demonstrate that DMAV blunts the luminescence signal of O2⨪ generated by phorbol 12-myristate 13-acetate-stimulated neutrophils. Mechanistically, inductively coupled plasma mass spectrometry and fluorescence spectroscopy revealed that DMAV, like Cu,Zn-SOD, interacts with Cu2+, which provides redox potential for catalytic removal of O2⨪. Notably, surface plasmon resonance experiments (BIAcore) determined that DMAV binds sulfated glycosaminoglycans (e.g. heparin, KD ∼100 nmol/liter), as reported for extracellular SOD. Finally, fractions of the salivary gland of D. maxima with native DMAV contain Cu2+ and display metal-dependent antioxidant properties. Antigen-5/CAP emerges as novel family of Cu2+-dependent antioxidant enzymes that inhibit neutrophil oxidative burst and negatively modulate platelet aggregation by a unique salivary mechanism. PMID:23564450

  12. A novel β-lactam derivative, albactam from the flowers of Albizia lebbeck with platelets anti-aggregatory activity in vitro.

    PubMed

    El-Gamal, Ali Ali; Abd-El-Halim, Mohamed Farag; Kalil, Ashraf Taha; Basudan, Omer Ahmed; Al-Rehaily, Adnan Jathlan; Ahmad, Mohamed Shamim; El-Tahir, Kamal Hussin; Al-Massarani, Shaza Mohamed; Abdel-Mageed, Wael Moustafa

    2015-03-01

    A novel β-lactam derivative, albactam, was isolated from the alcoholic extract of the flowers of Albizia lebbeck. It showed a significant anti-aggregatory activity against adenosine diphosphate and arachidonic acid induced guinea-pigs' platelets aggregation in vitro. Six more known compounds were also isolated and fully characterized by measuring 1D and 2D NMR, two of them are the triterpenes β-amyrin and 11α, 12α-oxidotaraxerol, two ceramide derivatives and two flavonoids, kampferol 3-O-rutinoside and rutin. PMID:25796149

  13. Platelet function tests: a comparative review

    PubMed Central

    Paniccia, Rita; Priora, Raffaella; Alessandrello Liotta, Agatina; Abbate, Rosanna

    2015-01-01

    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-tried and innovative platelet function tests and their methodological features and clinical applications are considered. PMID:25733843

  14. Platelet-derived ERp57 mediates platelet incorporation into a growing thrombus by regulation of the αIIbβ3 integrin

    PubMed Central

    Wang, Lu; Zhou, Junsong; Ahmad, Syed S.; Mutus, Bulent; Garbi, Natalio; Hämmerling, Günter; Liu, Junling

    2013-01-01

    The platelet protein disulfide isomerase called ERp57 mediates platelet aggregation, but its role in thrombus formation is unknown. To determine the specific role of platelet-derived ERp57 in hemostasis and thrombosis, we generated a megakaryocyte/platelet-specific knockout. Despite normal platelet counts and platelet glycoprotein expression, mice with ERp57-deficient platelets had prolonged tail-bleeding times and thrombus occlusion times with FeCl3-induced carotid artery injury. Using a mesenteric artery thrombosis model, we found decreased incorporation of ERp57-deficient platelets into a growing thrombus. Platelets lacking ERp57 have defective activation of the αIIbβ3 integrin and platelet aggregation. The defect in aggregation was corrected by the addition of exogenous ERp57, implicating surface ERp57 in platelet aggregation. Using mutants of ERp57, we demonstrate the second active site targets a platelet surface substrate to potentiate platelet aggregation. Binding of Alexa 488−labeled ERp57 to thrombin-activated and Mn2+-treated platelets lacking β3 was decreased substantially, suggesting a direct interaction of ERp57 with αIIbβ3. Surface expression of ERp57 protein and activity in human platelets increased with platelet activation, with protein expression occurring in a physiologically relevant time frame. In conclusion, platelet-derived ERp57 directly interacts with αIIbβ3 during activation of this receptor and is required for incorporation of platelets into a growing thrombus. PMID:24030382

  15. Platelet-derived ERp57 mediates platelet incorporation into a growing thrombus by regulation of the αIIbβ3 integrin.

    PubMed

    Wang, Lu; Wu, Yi; Zhou, Junsong; Ahmad, Syed S; Mutus, Bulent; Garbi, Natalio; Hämmerling, Günter; Liu, Junling; Essex, David W

    2013-11-21

    The platelet protein disulfide isomerase called ERp57 mediates platelet aggregation, but its role in thrombus formation is unknown. To determine the specific role of platelet-derived ERp57 in hemostasis and thrombosis, we generated a megakaryocyte/platelet-specific knockout. Despite normal platelet counts and platelet glycoprotein expression, mice with ERp57-deficient platelets had prolonged tail-bleeding times and thrombus occlusion times with FeCl3-induced carotid artery injury. Using a mesenteric artery thrombosis model, we found decreased incorporation of ERp57-deficient platelets into a growing thrombus. Platelets lacking ERp57 have defective activation of the αIIbβ3 integrin and platelet aggregation. The defect in aggregation was corrected by the addition of exogenous ERp57, implicating surface ERp57 in platelet aggregation. Using mutants of ERp57, we demonstrate the second active site targets a platelet surface substrate to potentiate platelet aggregation. Binding of Alexa 488-labeled ERp57 to thrombin-activated and Mn(2+)-treated platelets lacking β3 was decreased substantially, suggesting a direct interaction of ERp57 with αIIbβ3. Surface expression of ERp57 protein and activity in human platelets increased with platelet activation, with protein expression occurring in a physiologically relevant time frame. In conclusion, platelet-derived ERp57 directly interacts with αIIbβ3 during activation of this receptor and is required for incorporation of platelets into a growing thrombus. PMID:24030382

  16. Phosphorylation of platelet actin-binding protein during platelet activation

    SciTech Connect

    Carroll, R.C.; Gerrard, J.M.

    1982-03-01

    In this study we have followed the 32P-labeling of actin-binding protein as a function of platelet activation. Utilizing polyacrylamide-sodium dodecyl sulfate gel electrophoresis to resolve total platelet protein samples, we found 2 to 3-fold labeling increases in actin-binding protein 30 to 60 sec after thrombin stimulation. Somewhat larger increases were observed for 40,000 and 20,000 apparent molecular weight peptides. The actin-binding protein was identified on the gels by coelectrophoresis with purified actin-binding protein, its presence in cytoskeletal cores prepared by detergent extraction of activated 32P-labeled platelets, and by direct immunoprecipitation with antibodies against guinea pig vas deferens filamin (actin-binding protein). In addition, these cytoskeletal cores indicated that the 32P-labeled actin-binding protein was closely associated with the activated platelet's cytoskeleton. Following the 32P-labeling of actin-binding protein over an 8-min time course revealed that in aggregating platelet samples rapid dephosphorylation to almost initial levels occurred between 3 and 5 min. A similar curve was obtained for the 20,000 apparent molecular weight peptide. However, rapid dephosphorylation was not observed if platelet aggregation was prevented by chelating external calcium or by using thrombasthenic platelets lacking the aggregation response. Thus, cell-cell contact would seem to be crucial in initiating the rapid dephosphorylation response.

  17. Cancer procoagulant and blood platelet activation.

    PubMed

    Olas, B; Wachowicz, B; Mielicki, W P

    2001-08-28

    The effects of cancer procoagulant (CP), cysteine protease (EC 3.4.22.26), on the pig blood platelet secretory process and platelet aggregation have been studied. The response of platelets to CP was compared with the response of these cells to thrombin. The obtained results show that blood platelets treated with CP (0.5, 1, 2.5, and 5 microg/ml, 2-30 min, 37 degrees C) released adenine nucleotides (P < 0.05) and proteins (P < 0.05). The secretion of compounds from blood platelets after incubation with CP does not correlate with the release of platelet lactic dehydrogenase activity (marker of cell lysis) into the extracellular medium. In comparison with thrombin action, CP stimulates secretory process to a smaller extent than thrombin alone. In the presence of CP, the thrombin action is suppressed (P < 0.05). We noticed that CP does not induce platelet aggregation.

  18. Platelet antibodies.

    PubMed

    Pulkrabek, S M

    1996-12-01

    The proper diagnosis of patients with immune-mediated thrombocytopenias can be accomplished by using the advances made in the field of platelet serology. These techniques range from solid phase red cell adherence to sequencing platelet antigen amino acids by polymerase chain reaction. This article describes platelet antigens, the clinical tests available to detect platelet antigens and antibodies, and the value of these tests in supporting clinical diagnoses.

  19. Interaction of polypeptide antibiotic gramicidin S with platelets.

    PubMed

    Hackl, Ellen V; Berest, Vladimir P; Gatash, Sergey V

    2012-12-01

    Gramicidin S (GS) is a cyclic decapeptide antibiotic active against both Gram-positive and Gram-negative bacteria as well as against several pathogenic fungi. However, clinical application of GS is limited because of GS hemolytic activity. The large number of GS analogues with potentially attenuated hemolytic activity has been developed over the last two decades. For all new GS derivatives, the antimicrobial test is accompanied with the hemolytic activity assay. At the same time, neither GS nor its analogues were tested against other blood cells. In the present work, the effects of GS on platelets and platelet aggregates have been studied. GS interaction with platelets is concentration dependent and leads either to platelet swelling or platelet shape change. Effect of GS on platelets is independent of platelet aggregation mechanism. GS induces disaggregation of platelet aggregates formed in the presence of aggregation agonists. The rate of the GS interaction with platelet membranes depends on membrane lipid mobility and significantly increases with temperature. The interaction of GS with the platelet membranes depends strongly on the state of the membrane lipids. Factors affecting the membrane lipids (temperature, lipid peroxidation and ionising irradiation) modify GS interaction with platelets. Our results show that GS is active not only against erythrocytes but also against other blood cells (platelets). The estimated numbers of GS molecules per 1 µm2 of a blood cell required to induce erythrocyte hemolysis and disaggregation of platelet aggregates are comparable. This must be considered when developing new antimicrobial GS analogues with improved hemolytic properties.

  20. Rupture Forces among Human Blood Platelets at different Degrees of Activation.

    PubMed

    Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

    2016-01-01

    Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects.

  1. Rupture Forces among Human Blood Platelets at different Degrees of Activation

    PubMed Central

    Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

    2016-01-01

    Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004

  2. The platelet receptor for type III collagen (TIIICBP) is present in platelet membrane lipid microdomains (rafts).

    PubMed

    Maurice, Pascal; Waeckel, Ludovic; Pires, Viviane; Sonnet, Pascal; Lemesle, Monique; Arbeille, Brigitte; Vassy, Jany; Rochette, Jacques; Legrand, Chantal; Fauvel-Lafève, Françoise

    2006-04-01

    Platelet interactions with collagen are orchestrated by the presence or the migration of platelet receptor(s) for collagen into lipid rafts, which are specialized lipid microdomains from the platelet plasma membrane enriched in signalling proteins. Electron microscopy shows that in resting platelets, TIIICBP, a receptor specific for type III collagen, is present on the platelet membrane and associated with the open canalicular system, and redistributes to the platelet membrane upon platelet activation. After platelet lysis by 1% Triton X-100 and the separation of lipid rafts on a discontinuous sucrose gradient, TIIICBP is recovered in lipid raft-containing fractions and Triton X-100 insoluble fractions enriched in cytoskeleton proteins. Platelet aggregation, induced by type III collagen, was inhibited after disruption of the lipid rafts by cholesterol depletion, whereas platelet adhesion under static conditions did not require lipid raft integrity. These results indicate that TIIICBP, a platelet receptor involved in platelet interaction with type III collagen, is localized within platelet lipid rafts where it could interact with other platelet receptors for collagen (GP VI and alpha2beta1 integrin) for efficient platelet activation. PMID:16205938

  3. Endodontic management of nonvital permanent teeth having immature roots with one step apexification, using mineral trioxide aggregate apical plug and autogenous platelet-rich fibrin membrane as an internal matrix: Case series

    PubMed Central

    Sharma, Vivek; Sharma, Sarang; Dudeja, Pooja; Grover, Shibani

    2016-01-01

    A tooth with blunderbuss canal and open apex can be an endodontic challenge because of difficulty in obtaining an apical seal, and existing thin radicular walls which are susceptible to fracture. To overcome the limitations of traditional long-term calcium hydroxide apexification procedures, nonsurgical one step apexification using an array of materials such as mineral trioxide aggregate (MTA) has been suggested. However, adequate compaction of MTA in teeth with wide open apices can be an arduous task, and an internal matrix is required for controlled placement of MTA against which obturating material can be condensed. Platelet-rich fibrin (PRF), a second generation platelet concentrate containing several growth factors that promotes hard and soft-tissue healing, has been used as an internal matrix to create an apical plug of MTA and hence prevent extrusion of filling materials. This case series presents the endodontic management of immature permanent teeth with open apices using internal matrix of autologous PRF membrane and one step apical barrier placement of MTA. PMID:27041904

  4. Endodontic management of nonvital permanent teeth having immature roots with one step apexification, using mineral trioxide aggregate apical plug and autogenous platelet-rich fibrin membrane as an internal matrix: Case series.

    PubMed

    Sharma, Vivek; Sharma, Sarang; Dudeja, Pooja; Grover, Shibani

    2016-01-01

    A tooth with blunderbuss canal and open apex can be an endodontic challenge because of difficulty in obtaining an apical seal, and existing thin radicular walls which are susceptible to fracture. To overcome the limitations of traditional long-term calcium hydroxide apexification procedures, nonsurgical one step apexification using an array of materials such as mineral trioxide aggregate (MTA) has been suggested. However, adequate compaction of MTA in teeth with wide open apices can be an arduous task, and an internal matrix is required for controlled placement of MTA against which obturating material can be condensed. Platelet-rich fibrin (PRF), a second generation platelet concentrate containing several growth factors that promotes hard and soft-tissue healing, has been used as an internal matrix to create an apical plug of MTA and hence prevent extrusion of filling materials. This case series presents the endodontic management of immature permanent teeth with open apices using internal matrix of autologous PRF membrane and one step apical barrier placement of MTA. PMID:27041904

  5. Platelet factor XIII increases the fibrinolytic resistance of platelet-rich clots by accelerating the crosslinking of alpha 2-antiplasmin to fibrin

    NASA Technical Reports Server (NTRS)

    Reed, G. L.; Matsueda, G. R.; Haber, E.

    1992-01-01

    Platelet clots resist fibrinolysis by plasminogen activators. We hypothesized that platelet factor XIII may enhance the fibrinolytic resistance of platelet-rich clots by catalyzing the crosslinking of alpha 2-antiplasmin (alpha 2AP) to fibrin. Analysis of plasma clot structure by polyacrylamide gel electrophoresis and immunoblotting revealed accelerated alpha 2AP-fibrin crosslinking in platelet-rich compared with platelet-depleted plasma clots. A similar study of clots formed with purified fibrinogen (depleted of factor XIII activity), isolated platelets, and specific factor XIII inhibitors indicated that this accelerated crosslinking was due to the catalytic activity of platelet factor XIII. Moreover, when washed platelets were aggregated by thrombin, there was evidence of platelet factor XIII-mediated crosslinking between platelet alpha 2AP and platelet fibrin(ogen). Specific inhibition (by a monoclonal antibody) of the alpha 2AP associated with washed platelet aggregates accelerated the fibrinolysis of the platelet aggregate. Thus in platelet-rich plasma clots, and in thrombin-induced platelet aggregates, platelet factor XIII actively formed alpha 2AP-fibrin crosslinks, which appeared to enhance the resistance of platelet-rich clots to fibrinolysis.

  6. Platelet proteomics.

    PubMed

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

    2012-01-01

    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.

  7. Platelet lipidomic.

    PubMed

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

    2012-01-01

    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

  8. Interaction between canine platelets and adult heartworms: platelet recognition of heartworm surfaces.

    PubMed

    Clemmons, R M; Yamaguchi, R A; Schaub, R G; Fleming, J; Dorsey-Lee, M R; McDonald, T L

    1986-02-01

    An interaction between blood platelets and adult heartworms was examined in vitro. Surfaces of glutaraldehyde-fixed heartworms, which were taken from infected dogs washed, and incubated in platelet-rich plasma (PRP), were evaluated by scanning electron microscopy. Adherence of platelets to heartworms occurred only with PRP from infected dogs. Aggregation to epinephrine and adenosine diphosphate of PRP incubated with heartworms was monitored. Seemingly, platelet activation to heartworm membranes occurs in dogs with heartworm disease. The increased platelet reactivity was also observed in dogs with occult heartworm disease, indicating that the presence of circulating microfilaria was not important for this process. The ability to transfer the reactivity to heartworm-negative platelets by suspending them in heartworm-positive plasma indicated that this reactivity resided in the plasma. The processes leading to platelet activation may be responsible for the platelet-associated vascular disorders of canine heartworm disease.

  9. Image analysis of blood platelets adhesion.

    PubMed

    Krízová, P; Rysavá, J; Vanícková, M; Cieslar, P; Dyr, J E

    2003-01-01

    Adhesion of blood platelets is one of the major events in haemostatic and thrombotic processes. We studied adhesion of blood platelets on fibrinogen and fibrin dimer sorbed on solid support material (glass, polystyrene). Adhesion was carried on under static and dynamic conditions and measured as percentage of the surface covered with platelets. Within a range of platelet counts in normal and in thrombocytopenic blood we observed a very significant decrease in platelet adhesion on fibrin dimer with bounded active thrombin with decreasing platelet count. Our results show the imperative use of platelet poor blood preparations as control samples in experiments with thrombocytopenic blood. Experiments carried on adhesive surfaces sorbed on polystyrene showed lower relative inaccuracy than on glass. Markedly different behaviour of platelets adhered on the same adhesive surface, which differed only in support material (glass or polystyrene) suggest that adhesion and mainly spreading of platelets depends on physical quality of the surface. While on polystyrene there were no significant differences between fibrin dimer and fibrinogen, adhesion measured on glass support material markedly differed between fibrin dimer and fibrinogen. We compared two methods of thresholding in image analysis of adhered platelets. Results obtained by image analysis of spreaded platelets showed higher relative inaccuracy than results obtained by image analysis of platelets centres and aggregates.

  10. Effect of serotonin on platelet function in cocaine exposed blood

    PubMed Central

    Ziu, Endrit; Hadden, Coedy; Li, Yicong; Lowery, Curtis Lee; Singh, Preeti; Ucer, Serra S.; Mercado, Charles P.; Gu, Howard H.; Kilic, Fusun

    2014-01-01

    5-hydroxytryptamine (5-HT) reuptake inhibitors counteract the pro-thrombotic effect of elevated plasma 5-HT by down-regulating the 5-HT uptake rates of platelets. Cocaine also down-regulates the platelet 5-HT uptake rates but in contrast, the platelets of cocaine-injected mice show a much higher aggregation rate than the platelets of control mice. To examine the involvement of plasma 5-HT in cocaine-mediated platelet aggregation, we studied the function of platelets isolated from wild-type and transgenic, peripheral 5-HT knock-out (TPH1-KO) mice, and cocaine-insensitive dopamine transporter knock in (DAT-KI) mice. In cocaine-injected mice compared to the control mice, the plasma 5-HT level as well as the surface level of P-selectin was elevated; in vitro platelet aggregation in the presence of type I fibrillar collagen was enhanced. However, cocaine injection lowered the 5-HT uptake rates of platelets and increased the plasma 5-HT levels of the DAT-KI mice but did not change their platelets aggregation rates further which are already hyper-reactive. Furthermore, the in vitro studies supporting these in vivo findings suggest that cocaine mimics the effect of elevated plasma 5-HT level on platelets and in 5-HT receptor- and transporter-dependent pathways in a two-step process propagates platelet aggregation by an additive effect of 5-HT and nonserotonergic catecholamine. PMID:25091505

  11. Onion (Allium cepa L.) peel extract has anti-platelet effects in rat platelets.

    PubMed

    Ro, Ju-Ye; Ryu, Jin-Hyeob; Park, Hwa-Jin; Cho, Hyun-Jeong

    2015-01-01

    The effects of onion peel extract (OPE) in collagen (5 μg/mL)-stimulated washed rat platelet aggregation were investigated. OPE inhibited platelet aggregation via inhibition of aggregation-inducing molecules, intracellular Ca(2+) and thromboxane A2 (TXA2) by blocking cyclooxygenase-1 (COX-1) and TXA2 synthase (TXAS) activities in a dose-dependent manner. In addition, OPE elevated the formation of cyclic adenosine monophosphate (cAMP), aggregation-inhibiting molecule, but not cyclic guanosine monophosphate (cGMP). High performance liquid chromatography (HPLC) analysis of OPE revealed that OPE contains quercetin, one of the major flavonoids, which has anti-platelet effect. In conclusion, we suggest that OPE is an effective inhibitor of collagen-stimulated platelet aggregation in vitro. Therefore, it can be a promising and safe strategy for anti-cardiovascular diseases. PMID:25628983

  12. The effects of an inhibitor of diglyceride lipase on collagen-induced platelet activation.

    PubMed

    Jackson, Elke C G; Ortar, Giorgio; McNicol, Archie

    2013-12-01

    Human platelet activation by collagen occurs in a dose-dependent manner. High concentrations of collagen bind to a pair of receptors, the α2β1 integrin and glycoprotein (GP)VI/Fc-receptor γ-chain (FcRγ), which stimulate a cascade of events including Syk, LAT, Btk, Gads, and phospholipase Cγ2, leading to calcium release and protein kinase C (PKC) activation. Calcium and PKC are responsible for a range of platelet responses including exocytosis and aggregation, as well as the cytosolic phospholipase A2 (cPLA2)-mediated release of arachidonic acid, which is converted to thromboxane (Tx)A2. In contrast, low concentrations of collagen are acutely aspirin-sensitive, and calcium release and aggregation are TxA2-dependent. Under these conditions, cPLA2 is not involved and it has been suggested that phospholipase C generates 1,2-diacylglycerol (DG) from which arachidonic acid is liberated by diglyceride lipase (DGL). Here a novel DGL blocker (OMDM-188) inhibited collagen-, but not arachidonic acid-induced aggregation and TxA2 synthesis. Furthermore, OMDM-188 inhibited collagen-induced arachidonic acid release. Finally OMDM-188 inhibited collagen-induced p38(MAPK) phosphorylation, but not extracellular signal-regulated kinase (ERK) phosphorylation, with no effect on the phosphorylation of either enzyme in response to arachidonic acid. Taken together, these data suggest a role for a pathway involving phospholipase C liberating DG from membrane phospholipids in response to minimally activating concentrations of collagen. The DG serves as a substrate for DGL, potentially under the regulations of p38(MAPK), to release arachidonic acid, which is subsequently converted to TxA2, which mediates the final platelet response.

  13. Reduction of CTRP9, a novel anti-platelet adipokine, contributes to abnormal platelet activity in diabetic animals.

    PubMed

    Wang, Wenqing; Lau, Wayne Bond; Wang, Yajing; Ma, Xinliang; Li, Rong

    2016-01-11

    Platelet hyper-reactivity is a crucial cause of accelerated atherosclerosis increasing risk of thrombotic vascular events in diabetic patients. The mechanisms leading to abnormal platelet activity during diabetes are complex and not fully defined. The current study attempted to clarify the role of CTRP9, a novel adiponectin paralog, in enhanced platelet activity and determined whether CTRP9 may inhibit platelet activity. Adult male C57BL/6 J mice were randomized to receive high-fat diet (HFD) or normal diet (ND). 8 weeks after HFD, animals were sacrificed, and both plasma CTRP9 and platelet aggregation were determined. HFD-fed animals increased weight gain significantly, and became hyperglycemic and hyperinsulinemic 8 weeks post-HFD. Compared to ND animals, HFD animals exhibited significantly decreased plasma CTRP9 concentration and increased platelet response to ADP, evidenced by augmented aggregation amplitude, steeper aggregation slope, larger area under the curve, and shorter lag time (P < 0.01). A significant negative correlation between plasma CTRP9 concentration and platelet aggregation amplitude was observed. More importantly, in vitro pre-treatment with CTRP9 significantly inhibited ADP-stimulated platelet activation in platelet samples from both ND and HFD animals. Taken together, our results suggest reduced plasma CTRP9 concentration during diabetes plays a causative role in platelet hyper-activity, contributing to platelet-induced cardiovascular damage during this pathologic condition. Enhancing CTRP9 production and/or exogenous supplementation of CTRP9 may protect against diabetic cardiovascular injury via inhibition of abnormal platelet activity.

  14. A 'touch' of the White platelet syndrome.

    PubMed

    White, James G; Key, Nigel S; King, Richard A; Vercellotti, Gregory M

    2005-09-01

    Investigations into structural defects in platelets from a large family with the White platelet syndrome (WPS) separated the members into three groups. The first group of 22 members was the subject of our first report (White JG, Key NS, King RA, Vercellotti GM. The white platelet syndrome: A new autosomal dominant platelet disorder. Platelets 2004;15:173-184). A third group of 13 members had no abnormalities of platelet ultrastructure. The second group of 17 members, the focus of the present study, had a 'touch' of the WPS. Platelet counts, mean platelet volumes (MPVs) and platelet responses to aggregating agents were normal in 'touch' patients in contrast to platelets of those with the full WPS in whom these parameters were abnormal. Up to 13% of the full WPS platelets contained large, fully developed Golgi complexes, up to seven in number, extruding innumerable vesicles from the trans-Golgi face and filling the cytoplasm of many platelets. Many Golgi complexes had centrioles associated with them. 'Touch' platelets had one or two Golgi complexes of intermediate size in 3-5% of their platelets. Golgi vesicles were uncommon and centrioles absent. Gray platelets and hypogranular cells were infrequent in patients with a 'touch' of the WPS, whereas up to 44% of the platelets from those with the WPS were gray or hypogranular. Elements of the dense tubular system were prominent in full WPS platelets, together with their formation into areas of cytoplasmic sequestration and autodigestion. These features were absent in 'touch' platelets. As commonly observed in full WPS platelets, mitochondria were larger and more numerous than alpha granules in some 'touch' cells. Both 'touch' and full WPS platelets frequently contained giant and rod-shaped granules. Dense bodies, however, were normal in size and number in 'touch' platelets, and half normal size in full WPS platelets. The separation of ultrastructural abnormalities in the two varieties of the WPS suggests that genetic

  15. Stability of lyophilized human platelets loaded with small molecule carbohydrates.

    PubMed

    Wang, J X; Yang, C; Wan, W; Liu, M X; Ren, S P; Quan, G B; Han, Y

    2011-01-01

    Long-term preservation of platelets is a great challenge for blood transfusion centers, due to the required narrow storage temperature arange (22 ± 2 degree C). Short shelf life and potential bacterial growth often lead to the shortage of high-quality platelets. Freeze-dried preservation is thus believed to be a potential solution for long-term platelet storage without losing the hemostasis function. Here we report a new platelet preservation method, which uses small molecule carbohydrates to extend storage time and to maintain platelet function. The activities of lyophilized platelets that were stabilized with small molecule carbohydrate (e.g., cell viability, mean platelet volume, activation characteristics, and aggregation kinetics) were maintained after storage of 30, 60, and 90 days at room temperature, 4 degree C, and -20 degree C. The recovery of freeze-dried platelets was 87 percent in comparison to fresh platelets. The mean platelet volume of rehydrated platelets increased (from 6.8 fl to 8.0 fl). About 40 percent of rehydrated platelets was in the early-activated stage (PCA-1 positive) and 30 percent was in the terminal-activated stage (CD62P positive). The cell viability was about 60 percent as measured with CMFDA vital probes. The aggregation rate of rehydrated platelets after 90-day storage was similar to fresh platelets stored at 22 degree C ± 2 degree C.

  16. Platelet cytoskeleton and its hemostatic role.

    PubMed

    Cerecedo, Doris

    2013-12-01

    Upon vascular injury, platelets adhere to the exposed extracellular matrix, which triggers the platelet activation and aggregation to form a hemostatic plug to seal the wound. All of these events involve dramatic changes in shape because of the cytoskeleton reorganization. The versatility of the cytoskeleton's main elements depends on the biochemical nature of the elements, as well as on the associated proteins that confer multiple functions within the cell. The list of these associated proteins grows actively, increasing our knowledge concerning the complexity of platelet cytoskeleton machinery. The present review evidences the recently described platelet proteins that promote characteristic modifications in their cytoskeleton organization, with special focus on the dystrophin-glycoprotein complex.

  17. Platelet thrombopathy in asthmatic patients with elevated immunoglobulin e.

    PubMed

    Maccia, C A; Gallagher, J S; Ataman, G; Glueck, H I; Brooks, S M; Bernstein, I L

    1977-02-01

    Abnormalities of second-wave platelet aggregation were demonstrated in 17 of 33 asthmatic patients in whom drug and diet intake were controlled in the hospital. Mean abnormal responses were significantly greater after epinephrine- (p less than 0.001), adenosine diphosphate-(less than 0.001), collagen- (p = 0.01), and thrombin- (p less than 0.001) induced platelet aggregation in patients with immunologically mediated asthma and serum IgE levels greater than 250 U/ml as compared to patients without immunologic factors and/or normal controls. Mean pollen-specific radioallergosorbent (RAST) binding was also significantly higher in patients with abnormal aggregation as compared to normal platelet responders (p = 0.02). Release of serotonin generally reflected abnormal aggregation patterns in asthmatic patients. Platelet factor 4 release was significantly decreased in the same groups of patients. These results suggest that the allergic state may affect platelet membrane responsiveness to multiple aggregating agents.

  18. Platelets deficient in glycoprotein I have normal Fc receptor expression.

    PubMed

    Pfueller, S L; de Rosbo, N K; Bilston, R A

    1984-04-01

    Platelet glycoprotein I (GPI) is known to be required for the interaction of platelets with ristocetin and factor VIII:von Willebrand factor (VIII:vWf). However, its role as Fc receptor is not clear. Some studies have shown that enzymatic removal of GPI destroys the ability of platelets to react with VIII:vWf but not their ability to bind Ig G (IgG). Others have shown that IgG immune complexes which block the Fc receptor also inhibit VIII:vWf interaction with platelets. This subject has been re-examined by testing the ability of platelets with reduced amounts of GPI to aggregate and undergo the release reaction in response to stimuli which act at the platelet Fc receptor. Platelets from two patients with Bernard-Soulier syndrome, congenitally deficient in GPI, both aggregated and released 14C-serotonin normally when exposed to latex particles coated with IgG. Levels of GPI were decreased experimentally in normal platelets by treating them with chymotrypsin. Platelets treated in this manner did not aggregate or release [14C]serotonin in response to ristocetin-VIII:vWf. They did, however, both aggregate and release when incubated with heat-aggregated IgG, antigen-antibody complexes or latex particles coated with IgG. Thus the presence of GPI is not a prerequisite for platelet stimulation via the Fc receptor. PMID:6231945

  19. Platelet Count

    MedlinePlus

    ... rash Small purplish spots on the skin called purpura, caused by bleeding under the skin Testing may ... Idiopathic thrombocytopenia (ITP), also known as immune thrombocytopenic purpura, is the result of antibody production against platelets. ...

  20. In vitro inhibition of platelet aggregation by peptides derived from oat (Avena sativa L.), highland barley (Hordeum vulgare Linn. var. nudum Hook. f.), and buckwheat (Fagopyrum esculentum Moench) proteins.

    PubMed

    Yu, Guoyong; Wang, Feng; Zhang, Bolin; Fan, Junfeng

    2016-03-01

    Bioactive compounds present in foods could have beneficial effects on human health. In this study, we report the capacity of peptides released from oat, highland barley, and buckwheat proteins after enzymatic digestion to inhibit platelet aggregation in vitro. All hydrolysates showed high antiplatelet activity, with IC50 values of 0.282mg/ml (oat flour gastrointestinal hydrolysate, 6h) to 2.496mg/ml (highland barley glutelin tryptic hydrolysate, 14h) in a dose-dependent manner. Thirty-eight peptides with more than seven residues were identified in the tryptic hydrolysates of oat globulin. Results of computational modeling revealed that nine peptides, including ALPIDVLANAYR, EFLLAGNNKR, GEEFGAFTPK, QLAQIPR, LQAFEPLR, ALPVDVLANAYR, GEEFDAFTPK, QKEFLLAGNNK, and TNPNSMVSHIAGK bound the cyclooxygenase-1 active centers with low binding energy (-6.5 to -7.5kcal/mol). This is the first report to identify antiplatelet peptides from grain hydrolysates and the binding modes at the molecular level, leading to their possible use as functional food ingredients to prevent thrombosis.

  1. In vitro inhibition of platelet aggregation by peptides derived from oat (Avena sativa L.), highland barley (Hordeum vulgare Linn. var. nudum Hook. f.), and buckwheat (Fagopyrum esculentum Moench) proteins.

    PubMed

    Yu, Guoyong; Wang, Feng; Zhang, Bolin; Fan, Junfeng

    2016-03-01

    Bioactive compounds present in foods could have beneficial effects on human health. In this study, we report the capacity of peptides released from oat, highland barley, and buckwheat proteins after enzymatic digestion to inhibit platelet aggregation in vitro. All hydrolysates showed high antiplatelet activity, with IC50 values of 0.282mg/ml (oat flour gastrointestinal hydrolysate, 6h) to 2.496mg/ml (highland barley glutelin tryptic hydrolysate, 14h) in a dose-dependent manner. Thirty-eight peptides with more than seven residues were identified in the tryptic hydrolysates of oat globulin. Results of computational modeling revealed that nine peptides, including ALPIDVLANAYR, EFLLAGNNKR, GEEFGAFTPK, QLAQIPR, LQAFEPLR, ALPVDVLANAYR, GEEFDAFTPK, QKEFLLAGNNK, and TNPNSMVSHIAGK bound the cyclooxygenase-1 active centers with low binding energy (-6.5 to -7.5kcal/mol). This is the first report to identify antiplatelet peptides from grain hydrolysates and the binding modes at the molecular level, leading to their possible use as functional food ingredients to prevent thrombosis. PMID:26471595

  2. Fusaric acid, a mycotoxin, and its influence on blood coagulation and platelet function.

    PubMed

    Devaraja, Sannaningaiah; Girish, Kesturu S; Santhosh, Martin S; Hemshekhar, Mahadevappa; Nayaka, Siddaiah C; Kemparaju, Kempaiah

    2013-06-01

    The current study intended to explore the effect of fusaric acid on blood coagulation including plasma coagulation and platelet aggregation. Fusaric acid exhibited biphasic effects on citrated human plasma recalcification time. At concentrations below 50 ng, fusaric acid decreased the clotting time of plasma dose-dependently from 130 ± 3s control value to 32 ± 3s; however, above 50 ng, fusaric acid increased the clotting time from 32 ± 3s and reached a maximum of 152 s at 100 ng and remained unaltered thereafter for the increased dose of fusaric acid. Fusaric acid without damaging red blood cells and platelets, inhibited agonists such as collagen, ADP, thrombin, and epinephrine-induced aggregation of both platelet-rich plasma (PRP) and washed platelets preparations of human. Interestingly, fusaric acid showed biphasic effects only in thrombin-induced platelet aggregation of washed platelets, and at lower concentration (below 900 ng) it activated platelet aggregation; however, in increased concentration (above 900 ng) it inhibited the platelet aggregation of washed platelets. In addition, fusaric acid also inhibited the agonist ADP-induced platelet aggregation of washed platelet suspension but did not show biphasic effect. Further, fusaric acid did not induce the platelets to generate reactive oxygen species (ROS) that clearly suggests that the induction of platelet function could be the result of the fusaric acid-mediated receptor interaction but not through the morphological shape change.

  3. Dose-dependent platelet stimulation and inhibition induced by anti-PIA1 IgG

    SciTech Connect

    Ryu, T.; Davis, J.M.; Schwartz, K.A. )

    1990-07-01

    The PIA1 antibody produces several clinically distinct and severe thrombocytopenias. Investigations have demonstrated divergent effects on platelet function; prior reports demonstrated inhibition, while a conflicting publication showed platelet activation. We have resolved this conflict using anti-PIA1 IgG produced by a patient with posttransfusion purpura. Relatively low concentrations stimulated platelet aggregation and release of adenosine triphosphate (ATP) whereas high concentrations inhibited platelet function, producing a thrombasthenia-like state. The number of molecules of platelet-associated IgG necessary to initiate aggregation and ATP release (2,086 +/- 556) or produce maximum aggregation (23,420 +/- 3,706) or complete inhibition (63,582 +/- 2654) were measured with a quantitative radiometric assay for bound anti-PIA1. Preincubation of platelets with high concentrations of PIA1 antibody inhibited platelet aggregation with 10 mumol/L adenosine diphosphate and blocked 125I-labeled fibrinogen platelet binding. Platelet activation with nonfibrinogen dependent agonist, 1 U/ml thrombin, was not inhibited by this high concentration of PIA1 IgG. In conclusion, anti-PIAI IgG produces (1) stimulation of platelet aggregation and ATP release that is initiated with 2000 molecules IgG per platelet and is associated with an increase of 125I-fibrinogen binding; (2) conversely, inhibition of platelet aggregation is observed with maximum antibody binding, 63,000 molecules IgG per platelet, and is mediated via a blockade of fibrinogen binding.

  4. Hypersensitivity to thrombin of platelets from hypercholesterolemic rats

    SciTech Connect

    Winocour, P.D.; Rand, M.L.; Kinlough-Rathbone, R.L.; Mustard, J.F.

    1986-03-01

    Hypersensitivity of platelets to thrombin has been associated with hypercholesterolemia. The authors have examined the mechanisms involved in this hypersensitivity. Rats were given diets rich in milk fat and containing added cholesterol and taurocholate to produce hypercholesterolemia (HC) (262 +/- 25 mg%) or added sitosterol as a normocholesterolemic control (NC) (89 +/- 6 mg%). Washed platelets were prelabelled with /sup 14/C-serotonin. In the presence of acetylsalicyclic acid (ASA) (to inhibit thromboxane A/sub 2/ (TXA/sub 2/) formation) and creatine phosphate/creatine phosphokinase (CP/CPK) (to remove released ADP), HC platelets aggregated more (26 +/- 1%) and released more /sup 14/C (9.1 +/- 2.0%) than NC platelets (aggregation: 0%, p < 0.001; /sup 14/C release: 1.5 +/- 0.5%, p < 0.002) in response to thrombin (0.075 U/ml). Thus, a pathway independent of released ADP or TXA/sub 2/ formation is involved in the hypersensitivity of HC platelets to thrombin. Total binding of /sup 125/I-thrombin to HC platelets was less than that to NC platelets but HC platelets were smaller and had less protein than NC platelets; the thrombin binding per mg platelet protein was the same for HC and NC platelets, indicating that hypersensitivity to thrombin of HC platelets does not result from increased thrombin binding. Thus, hypersensitivity of HC platelets to thrombin is not due to TXA/sub 2/ formation, the action of released ADP or increased thrombin binding.

  5. Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis.

    PubMed

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

    2014-07-31

    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.

  6. Comparison between urinary 11-dehydrothromboxane B2 detection and platelet Light Transmission Aggregometry (LTA) assays for evaluating aspirin response in elderly patients with coronary artery disease.

    PubMed

    Liu, Tengfei; Zhang, Jingwei; Chen, Xiahuan; Feng, Xueru; Fu, Sidney W; McCaffrey, Timothy A; Liu, Meilin

    2015-10-15

    Aspirin is widely used in the primary and secondary prevention of cardiovascular diseases. The aim of our study was to compare between two established methods of aspirin response, urinary 11-dehydrothromboxane B2 (11dhTXB2) and platelet Light Transmission Aggregometry (LTA) assays in elderly Chinese patients with coronary artery disease (CAD), and to investigate the clinical significance of both methods in predicting cardiovascular events. Urinary 11dhTxB2 assay and arachidonic acid-induced (AA, 0.5mg/ml) platelet aggregation by Light Transmission Aggregometry (LTAAA) assay were measured to evaluate aspirin responses. High-on aspirin platelet reactivity (HAPR) was defined as urinary 11dhTxB2>1500pg/mg or AA-induced platelet aggregation≥15.22%-the upper quartile of our enrolled population. The two tests showed a poor correlation for aspirin inhibition (r=0.063) and a poor agreement in classifying HAPR (kappa=0.053). With a mean follow-up time of 12months, cardiovascular events occurred more frequently in HAPR patients who were diagnosed by LTA assay as compared with no-HAPR patients (22.5% versus 10.6%, P=0.039, OR=2.45, 95% CI=1.06-5.63). However, the HAPR status, as determined by urinary 11dTXB2 measurement, did not show a significant correlation with outcomes. PMID:26095809

  7. Comparison between urinary 11-dehydrothromboxane B2 detection and platelet Light Transmission Aggregometry (LTA) assays for evaluating aspirin response in elderly patients with coronary artery disease.

    PubMed

    Liu, Tengfei; Zhang, Jingwei; Chen, Xiahuan; Feng, Xueru; Fu, Sidney W; McCaffrey, Timothy A; Liu, Meilin

    2015-10-15

    Aspirin is widely used in the primary and secondary prevention of cardiovascular diseases. The aim of our study was to compare between two established methods of aspirin response, urinary 11-dehydrothromboxane B2 (11dhTXB2) and platelet Light Transmission Aggregometry (LTA) assays in elderly Chinese patients with coronary artery disease (CAD), and to investigate the clinical significance of both methods in predicting cardiovascular events. Urinary 11dhTxB2 assay and arachidonic acid-induced (AA, 0.5mg/ml) platelet aggregation by Light Transmission Aggregometry (LTAAA) assay were measured to evaluate aspirin responses. High-on aspirin platelet reactivity (HAPR) was defined as urinary 11dhTxB2>1500pg/mg or AA-induced platelet aggregation≥15.22%-the upper quartile of our enrolled population. The two tests showed a poor correlation for aspirin inhibition (r=0.063) and a poor agreement in classifying HAPR (kappa=0.053). With a mean follow-up time of 12months, cardiovascular events occurred more frequently in HAPR patients who were diagnosed by LTA assay as compared with no-HAPR patients (22.5% versus 10.6%, P=0.039, OR=2.45, 95% CI=1.06-5.63). However, the HAPR status, as determined by urinary 11dTXB2 measurement, did not show a significant correlation with outcomes.

  8. Platelet Function Tests in Bleeding Disorders.

    PubMed

    Lassila, Riitta

    2016-04-01

    Functional disorders of platelets can involve any aspect of platelet physiology, with many different effects or outcomes. These include platelet numbers (thrombocytosis or thrombocytopenia); changes in platelet production or destruction, or capture to the liver (Ashwell receptor); altered adhesion to vascular injury sites and/or influence on hemostasis and wound healing; and altered activation or receptor functions, shape change, spreading and release reactions, procoagulant and antifibrinolytic activity. Procoagulant membrane alterations, and generation of thrombin and fibrin, also affect platelet aggregation. The above parameters can all be studied, but standardization and quality control of assay methods have been limited despite several efforts. Only after a comprehensive clinical bleeding assessment, including family history, information on drug use affecting platelets, and exclusion of coagulation factor, and tissue deficits, should platelet function testing be undertaken to confirm an abnormality. Current diagnostic tools include blood cell counts, platelet characteristics according to the cell counter parameters, peripheral blood smear, exclusion of pseudothrombocytopenia, whole blood aggregometry (WBA) or light transmission aggregometry (LTA) in platelet-rich plasma, luminescence, platelet function analysis (PFA-100) for platelet adhesion and deposition to collagen cartridges under blood flow, and finally transmission electron microscopy to exclude rare structural defects leading to functional deficits. The most validated test panels are included in WBA, LTA, and PFA. Because platelets are isolated from their natural environment, many simplifications occur, as circulating blood and interaction with vascular wall are omitted in these assays. The target to reach a highly specific platelet disorder diagnosis in routine clinical management can be exhaustive, unless needed for genetic counseling. The elective overall assessment of platelet function disorder

  9. Platelets and infections - complex interactions with bacteria.

    PubMed

    Hamzeh-Cognasse, Hind; Damien, Pauline; Chabert, Adrien; Pozzetto, Bruno; Cognasse, Fabrice; Garraud, Olivier

    2015-01-01

    Platelets can be considered sentinels of vascular system due to their high number in the circulation and to the range of functional immunoreceptors they express. Platelets express a wide range of potential bacterial receptors, including complement receptors, FcγRII, Toll-like receptors but also integrins conventionally described in the hemostatic response, such as GPIIb-IIIa or GPIb. Bacteria bind these receptors either directly, or indirectly via fibrinogen, fibronectin, the first complement C1q, the von Willebrand Factor, etc. The fate of platelet-bound bacteria is questioned. Several studies reported the ability of activated platelets to internalize bacteria such as Staphylococcus aureus or Porphyromonas gingivalis, though there is no clue on what happens thereafter. Are they sheltered from the immune system in the cytoplasm of platelets or are they lysed? Indeed, while the presence of phagolysosome has not been demonstrated in platelets, they contain antimicrobial peptides that were shown to be efficient on S. aureus. Besides, the fact that bacteria can bind to platelets via receptors involved in hemostasis suggests that they may induce aggregation; this has indeed been described for Streptococcus sanguinis, S. epidermidis, or C. pneumoniae. On the other hand, platelets are able to display an inflammatory response to an infectious triggering. We, and others, have shown that platelet release soluble immunomodulatory factors upon stimulation by bacterial components. Moreover, interactions between bacteria and platelets are not limited to only these two partners. Indeed, platelets are also essential for the formation of neutrophil extracellular traps by neutrophils, resulting in bacterial clearance by trapping bacteria and concentrating antibacterial factors but in enhancing thrombosis. In conclusion, the platelet-bacteria interplay is a complex game; its fine analysis is complicated by the fact that the inflammatory component adds to the aggregation response

  10. Congenital platelet function defects

    MedlinePlus

    Platelet storage pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... disorder may also cause severe bleeding. Platelet storage pool disorder (also called platelet secretion disorder) occurs when ...

  11. Effect of SJAMP on ATP release of platelet.

    PubMed

    Guo, T; Shen, D; Song, S; Wei, W

    1999-01-01

    The aggregation and ATP release of placelet of normal subjects were measured by platelet lumi-aggregometer. It was found that the aggregation curve induced by SJAMP at the concentration of 100 mg/L was a typical second phase aggregation. There existed a certain lag between platelet aggregation and secretion. The secretion actually began slightly after the second phase of aggregation, suggesting that the second phase aggregation induced by SJAMP is not dependent upon the release of contents of dense granule alone. If platelets were incubated with cyclo-oxygenase inhibitor, the second phase aggregation was inhibited and no ATP was released. The results indicated that the aggregation and release reaction induced by SJAMP were dependent upon the generation of prostaglandin endoperoxides and TXA2 in normal subjects. The amount of ATP release was 0.69 +/- 0.22 nmol/10(8) platelets as stimulated with SJAMP (100 mg/L). But the amount of ATP release were 1.60 +/- 0.25 and 1.37 +/- 0.15 nmol/10(8) platelets when platelets were stimulated with ADP (5 mumol/L) and collagen (5 mg/L). The amount of ATP release induced by SJAMP was significantly lower than that of ADP and collagen. These findings indicated that SJAMP was a weaker agonist than ADP in terms of platelets release reaction.

  12. Action of platelet-activating factor on type 1 diabetic human platelets

    SciTech Connect

    Greco, N.J.; Arnold, J.H.; O'Dorisio, T.M.; Cataland, S.; Panganamala, R.V.

    1985-04-01

    Platelets from patients with type 1 diabetes have exhibited more sensitivity to aggregation when compared with platelets from controls without diabetes after challenge with platelet-activating factor (PAF). The production of thromboxane B2 (TxB2) and 12-hydroxyeicosatetraenoic acid (12-HETE) and the release of 5-hydroxytryptamine (5HT) were increased when the platelets were challenged by PAF (5.0 x 10(-6) mol/L and 1.0 x 10(-6) mol/L). The production of TxB2 and 12-HETE and the release of 5HT were related to the irreversible biphasic aggregation profiles observed in the patients with diabetes. Inhibition of thromboxane A2 (TxA2) production by acetylsalicylic acid abolished the secondary wave of aggregation of platelets from patients with diabetes, changing an irreversible aggregation to a reversible one. Inhibition of both TxA2 and 12-HETE production by eicosatetraenoic acid did not contribute further to the inhibition caused by acetylsalicylic acid alone, indicating that 12-HETE was not involved in the secondary wave of aggregation. These data show that the increased aggregation observed in the platelets from the group with diabetes in response to PAF results in part from their higher production of TxA2 and release of 5HT.

  13. Platelet-leukocyte interaction in adhesion to endothelial cells induced by platelet-activating factor in vitro.

    PubMed Central

    Hirafuji, M.; Shinoda, H.

    1991-01-01

    1. Platelet-activating factor (PAF, 10 nM) did not induce platelet adhesion to endothelial cells cultured in monolayer but it induced their adhesion to protein-coated plastic. However, PAF induced a marked platelet adhesion to endothelial cells when polymorphonuclear leukocytes (PMNs) were present. Lyso-PAF had no effect. 2. Phase-contrast microscopic examination showed that single platelets rather than their aggregates adhered to the endothelial cell surface around aggregating and adhering PMNs. 3. Significant platelet adhesion was induced by PAF at concentrations higher that 0.01 nM with the maximal response at 10 nM. Platelet adhesion occurred within minutes after PAF addition, reaching a maximum approximately after 30 min. Platelet adhesion also occurred significantly at a PMN:platelet ratio of 1:800, and linearly up to 1:50. 4. The PAF-induced platelet adhesion was suppressed by three structurally unrelated PAF antagonists, WEB 2086, ONO 6240 and BN 52021, in a concentration-dependent manner. 5. PAF also increased PMN adhesion to endothelial cell monolayers, which was further augmented by the presence of platelets. 6. The present study demonstrates that PAF induces platelet adhesion to endothelial cells in vitro when PMNs are present and that there is a close interaction between platelets and PMNs in their adhesion to endothelial cells. The present study further suggests that PMNs could play a central role in platelet adhesion to vascular endothlium in certain pathological conditions. Images Figure 2 PMID:1884095

  14. Platelet and other hemostatic characteristics in patients with chronic urticaria.

    PubMed

    Isiksacan, Nilgun; Koser, Murat; Cemsitoglu, Ferhan; Kucuksezer, Umut C; Gurdol, Figen

    2015-04-01

    Several publications have pointed out the importance of coagulation and fibrinolysis in the occurrence of chronic urticaria (CU), but only a few indicated the direct role of platelets. We assessed platelet aggregation and evaluated parameters of coagulation and fibrinolysis in patients with CU. Patients (n = 34) diagnosed as having CU and 36 healthy controls were enrolled. Platelet aggregation was assayed using an impedance aggregometer and adenosine diphosphate, arachidonic acid, thrombin receptor-activating peptide (TRAP), and ristocetin as agonists. In patients with CU, significantly decreased platelet aggregation to some agonists (ristocetin and TRAP) was observed. The D-dimer levels were elevated, mean platelet volume was decreased, but no alteration was observed in other coagulation assays. Elevated D-dimer levels indicated that coagulation and fibrinolysis are activated in the patients with CU. Evaluation of platelet function may contribute to identify the role of these cells in the pathogenesis of CU.

  15. Factor VIII is a positive regulator of platelet function.

    PubMed

    Obergfell, A; Sturm, A; Speer, C P; Walter, U; Grossmann, R

    2006-11-01

    FVIII is an important cofactor in the tenase coagulation factor complex, lack of FVIII causes severe bleeding, whereas high FVIII levels seem to be associated with venous and arterial thromboembolism. Resting platelets do not bind FVIII, but activated platelets bind unactivated FVIII if vWF is not present. We investigated a possible influence of platelet bound FVIII on platelet function itself as it is unclear if there is a direct effect of FVIII on platelet function. The influence of FVIII on platelet function was investigated by flow cytometric analysis of P-selectin expression (CD62P) and PAC-1 binding before and after submaximal stimulation with TRAP-6 (5 microM final concentration), by confocal microscopy and by platelet aggregometry. For flow cytometry and confocal microscopy, washed platelets were incubated with human recombinant FVIII for 5 min at 37 degrees C. Analysis of platelet surface area was measured by computerized image analysis. Treatment with FVIII only caused no changes in P-selectin expression or PAC-1 binding, respectively. Stimulation of platelets with TRAP-6 increased the expression of P-selectin (445%) and PAC-1 binding (934%) as expected. These effects were further increased when platelets were stimulated with TRAP-6 and FVIII (P-selectin 499%, difference not significant; PAC-1 1626%, P < 0.05. Values were expressed in%, related to unstimulated, buffer treated platelets). Platelet spreading on fibrinogen was significantly increased when platelets were treated with FVIII and TRAP-6 compared to TRAP-6 alone (368 vs. 307 average pixel/platelet, P<0.05). In addition platelet aggregation was enhanced when platelets were stimulated with FVIII and TRAP-6 compared to TRAP-6 alone. FVIII can act as a positive regulator of platelet function in TRAP-co-stimulated platelets. We hypothesize that FVIII induced increase in platelet activation might contribute to venous and even arterial thrombus formation in patients with high FVIII levels. PMID:17074720

  16. Point-of-care platelet function tests: detection of platelet inhibition induced by nonopioid analgesic drugs.

    PubMed

    Scharbert, Gisela; Gebhardt, Kristina; Sow, Zacharia; Duris, Monika; Deusch, Engelbert; Kozek-Langenecker, Sibylle

    2007-12-01

    Detection of platelet inhibition is of clinical relevance in the preinterventional risk-benefit assessment in chronic low-back-pain patients scheduled for invasive pain therapy. We evaluated the sensitivity of various point-of-care platelet function tests for the detection of platelet inhibition induced by nonopioid analgesic drugs. After Institutional Review Board approval and informed consent, citrated whole blood from 40 patients with chronic unspecific low back pain was investigated before and 30 min after intravenous infusion of the study medication consisting of diclofenac 75 mg (plus orphenadrin 30 mg; Neodolpasse; Fresenius Kabi Austria GmbH, Austria), parecoxib 40 mg (Dynastat; Pharmacia Europe EEIG, UK), paracetamol 1 g (Perfalgan; Bieffe Medital S.P.A., Italy), or normal saline in a randomized, cross-over, double-blinded, placebo-controlled study. Platelet function was assessed using the PFA-100 platelet function analyzer and thromboelastometry, as well as impedance aggregometry (in the last 17 patients recruited after it became commercially available). Sensitivity for detecting diclofenac-induced platelet inhibition was 85% for the PFA-100 using epinephrine as agonist and 94% for arachidonic acid-induced impedance aggregometry. ADP-induced platelet function tests, as well as cytochalasin D-modified thromboelastometry were unreliable. All tests had a low incidence of false-positive test results after normal saline. Paracetamol and parecoxib had no significant platelet inhibiting effect. The PFA-100 using epinephrine as agonist and arachidonic acid-induced impedance aggregometry are recommended for the detection of cyclooxygenase-I-inhibiting effects of nonsteroidal anti-inflammatory drugs such as diclofenac. Our findings confirm that a single rescue dose of paracetamol and parecoxib has no antiplatelet effect. PMID:17982319

  17. Regulation of fibrinogen receptor expression on human platelets

    SciTech Connect

    Shattil, S.J.; Motulsky, H.J.; Insel, P.A.; Brass, L.F.

    1986-03-01

    Platelet aggregation requires the binding of fibrinogen to specific receptors on the plasma membrane glycoprotein IIb-IIIa complex. Although the IIb-IIIa complex is identifiable on the surface of resting platelets, the fibrinogen receptor is expressed only after platelet activation. The authors have developed a monoclonal anti-IIb-IIIa antibody (PAC-1) that binds only to stimulated platelets and only in the presence of Ca. In order to better understand the steps leading to platelet aggregation, the authors used radiolabeled PAC-1 and fibrinogen to examine the effect of the ..cap alpha../sub 2/-adrenergic agonist, epinephrine, on the expression and function of the fibrinogen receptor. The addition of epinephrine to unstirred platelets caused and immediate increase in PAC-1 and fibrinogen binding that was associated with platelet aggregation once the platelets were stirred. Even after prolonged incubation of the platelets with epinephrine, fibrinogen receptor expression could be reversed by adding EGTA, PGl/sub 2/, or the ..cap alpha../sub 2/-adrenergic antagonist, phentolamine. When unstirred platelets were exposed to epinephrine for more than 10 min, the extent of aggregation caused by subsequent stirring was decreased by 70%. Surprisingly, these desensitized platelets bound PAC-1 and fibrinogen normally, indicating that the loss of aggregation was not due to a decrease in fibrinogen receptor expression or function. These studies demonstrate that: (1) fibrinogen receptor expression is dependent on extracellular CA; (2) induction of the fibrinogen receptor by epinephrine requires the continued presence of the agonist; and (3) prolonged stimulation of the platelet by epinephrine can lead to a reduced aggregation response by a mechanism that does not involve a loss of either fibrinogen recepor expression or fibrinogen binding.

  18. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study: Variation in Platelet Response to Clopidogrel and Aspirin.

    PubMed

    Bozzi, Laura M; Mitchell, Braxton D; Lewis, Joshua P; Ryan, Kathy A; Herzog, William R; O'Connell, Jeffrey R; Horenstein, Richard B; Shuldiner, Alan R; Yerges-Armstrong, Laura M

    2016-01-01

    Clopidogrel and aspirin are commonly prescribed anti-platelet medications indicated for patients who have experienced, or are at risk for, ischemic cardiovascular events. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study was designed to characterize determinants of clopidogrel and dual anti-platelet therapy (DAPT) response in a healthy cohort of Old Order Amish from Lancaster, PA. Following a loading dose, clopidogrel was taken once a day for 7 days. One hour after the last dose of clopidogrel, 325 mg of aspirin was given. Ex vivo platelet aggregometry was performed at baseline, post-clopidogrel, and post-DAPT. Platelet aggregation measurements were significantly lower after both interventions for all agonists tested (p <0.05), although there was large inter-individual variation in the magnitude of anti-platelet response. Female sex and older age were associated with higher platelet aggregation at all three time-points. Change in aggregation was correlated among the various agonists at each time point. Heritability (h2) of change in platelet aggregation was significant for most traits at all time-points (range h2=0.14-0.57). Utilization of a standardized, short-term intervention provided a powerful approach to investigate sources of variation in platelet aggregation response due to drug therapy. Further, this short-term intervention approach may provide a useful paradigm for pharmacogenomics studies.

  19. Decreased fibrinolytic activity and increased platelet function in hypertension. Possible influence of calcium antagonism.

    PubMed

    Gleerup, G; Winther, K

    1991-02-01

    Twelve patients with mild hypertension were compared, after 14 days of placebo, with an age- and gender-matched group of 12 healthy volunteers for platelet aggregability and fibrinolytic activity. Following this, 10 of the 12 hypertensives were treated with the calcium antagonist isradipine for 12 months. Blood was drawn for determinations of platelet aggregation and fibrinolytic activity after two weeks and 12 months of treatment. Platelet aggregation tended to increase in the hypertensives compared with controls, indicated by a lowering of the adenosine diphosphate (ADP) threshold value for irreversible aggregation. Tissue-plasminogen activator (t-PA) activity was significantly decreased in hypertensives compared to controls (P less than .05). During therapy, platelet aggregation decreased and t-PA activity increased (P less than .05). The present data suggest that fibrinolytic activity is decreased and platelet aggregation increased in mild hypertension. Besides the blood pressure-lowering effect, isradipine may protect against thromboembolic diseases by modifying platelet function and fibrinolytic activity.

  20. Resveratrol preserves the function of human platelets stored for transfusion.

    PubMed

    Lannan, Katie L; Refaai, Majed A; Ture, Sara K; Morrell, Craig N; Blumberg, Neil; Phipps, Richard P; Spinelli, Sherry L

    2016-03-01

    Stored platelets undergo biochemical, structural and functional changes that lead to decreased efficacy and safety of platelet transfusions. Not only do platelets acquire markers of activation during storage, but they also fail to respond normally to agonists post-storage. We hypothesized that resveratrol, a cardioprotective antioxidant, could act as a novel platelet storage additive to safely prevent unwanted platelet activation during storage, while simultaneously preserving normal haemostatic function. Human platelets treated with resveratrol and stored for 5 d released less thromboxane B2 and prostaglandin E2 compared to control platelets. Resveratrol preserved the ability of platelets to aggregate, spread and respond to thrombin, suggesting an improved ability to activate post-storage. Utilizing an in vitro model of transfusion and thromboelastography, clot strength was improved with resveratrol treatment compared to conventionally stored platelets. The mechanism of resveratrol's beneficial actions on stored platelets was partly mediated through decreased platelet apoptosis in storage, resulting in a longer half-life following transfusion. Lastly, an in vivo mouse model of transfusion demonstrated that stored platelets are prothrombotic and that resveratrol delayed vessel occlusion time to a level similar to transfusion with fresh platelets. We show resveratrol has a dual ability to reduce unwanted platelet activation during storage, while preserving critical haemostatic function.

  1. Biochemical and functional abnormalities in hypercholesterolemic rabbit platelets

    SciTech Connect

    Dalal, K.B.; Ebbe, S.; Mazoyer, E.; Carpenter, D.; Yee, T. )

    1990-02-01

    This study was designed to elucidate changes in rabbit platelet lipids induced by a cholesterol rich diet and to explore the possible correlation of these lipid changes with platelet abnormalities. Pronounced biochemical alterations were observed when serum cholesterol levels of 700-1000 mg% were reached. Hypercholesterolemic (HC) platelets contained 37% more neutral lipids and 16% less phospholipids than the controls. Lysolecithin, cholesterol esters and phosphatidylinositol (PI) levels were increased in HC platelets, and the levels of phosphatidylcholine (PC) were decreased. The cholesterol/phospholipid molar ratio of lipidemic platelets increased from 0.55 +/- 0.011 to 0.89 +/- 0.016 (P less than 0.01) in eight weeks. HC platelets had 90% more arachidonic acid (AA) in the PI than normal platelets. No significant changes in AA of PC were observed. Platelet function was monitored by the uptake and release of (14C)serotonin in platelet rich plasma (PRP), using varying concentrations of collagen as an aggregating agent. The uptake of (14C)serotonin in HC and normal platelets ranged from 78-94%. The percent of (14C)serotonin released from normal and HC platelets was proportional to the concentration of collagen. However, lipidemic platelets were hyperreactive to low concentrations of collagen. Incorporation of 50 microM acetylsalicylic acid into the aggregating medium suppressed the release of (14C)serotonin in normal PRP by more than 90%, but had only a partial effect on lipidemic PRP.

  2. Fractionation of platelets according to size: functional and biochemical characteristics

    SciTech Connect

    Carty, D.J.; Gear, A.R.

    1986-01-01

    The functional and biochemical heterogeneity of platelets has been studied using graded differential centrifugation to fractionate human platelets according to size while maintaining their morphological and functional integrity as indicated by scanning electron microscopy and content of beta-thromboglobulin. Aggregation kinetics were studied by both optical and quenched-flow methods involving single-particle counting. Large platelets were significantly more sensitive to ADP, but aggregated less rapidly than small platelets. Thrombin exerted a similar influence. Large platelets were also enriched in surface sialic acid and sulfhydryl groups and in internal glycogen, ATP, ADP, calcium, cyclic AMP, malonaldehyde, and succinate cytochrome c reductase when compared to small platelets, even when normalized per unit volume. ADP caused a more rapid breakdown of cyclic AMP in small platelets. Potential aging relationships were tested by isotope studies in rats. /sup 75/Se-selenomethionine was incorporated in vivo at a similar rate into all fractions. Large platelets labeled with /sup 51/Cr disappeared from circulation linearly and had a longer mean lifespan than small platelets, which disappeared exponentially. This behavior supports independent aging of platelet populations of differing size. The data suggest a distinct heterogeneity in platelet function and fate, which could derive from protection of large platelets against excessive activation by Ca2+-regulated events.

  3. Platelet function in the postprandial period

    PubMed Central

    2012-01-01

    Background Postprandial hyperlipidemia and hyperglycemia have been related to cardiovascular events. Among different underlying mechanisms platelet activation seems to be responsible too. No comparable data between various tests in normo- vs. hyperlipidemics before and at different time intervals are available after a fat meal. We aimed to compare 9 of them within the same patients at several time points in postprandial hyperlipidemia. Results For some tests baseline values between the groups were significantly different (TXB2, platelet sensitivity, sedimentation and WU-test). However, hyperlipidemia revealed a variable influence on the tests examined. Some of the available tests apparently sensitive to show platelet activation reflect the increase in triglycerides (TG), such as the sedimentation index. ADP-induced platelet aggregatory activity in count adjusted washed isolated platelet samples during postprandial hyperlipidemia indicates mildly enhanced platelet activity, but does not seem to induce significant changes in aggregation. In patients with severe hypertriglyceridemia (> 400 mg/dl fasting) changes in platelet function are more pronounced due to delayed decay and may last up to 16 hours paralleling TG reaching the prevalue. The overwhelming majority of platelet function tests do not significantly respond to postprandial hyperlipidemia. The correlation between the tests applied is poor. For standardization purpose, platelet aggregation tests, aimed to examine proaggregatory capacity in atherosclerosis, should only be performed at the same time of the day after a fasting period > 6 hours. The great variation in preanalytical work-up on comparison of various tests, large number of platelet tests available and their respective potential value are discussed. Conclusions At present, the suspicion that platelet function is significantly activated in the postprandial period cannot be supported by any of the tests used. The information provided is valuable to

  4. Exposure of fibrinogen receptors in human platelets by surface proteolysis with elastase.

    PubMed Central

    Kornecki, E; Ehrlich, Y H; De Mars, D D; Lenox, R H

    1986-01-01

    Human platelets that were preincubated with porcine elastase aggregated spontaneously upon the addition of fibrinogen. Maximal aggregation to fibrinogen was observed with platelets pretreated with an elastase concentration of 111 micrograms/ml, and half-maximal aggregation occurred after treatment with 11 micrograms/ml elastase. Binding of radiolabeled fibrinogen to elastase-treated platelets was specific, saturable, and showed a single class of 48,400 +/- 9,697 fibrinogen-binding sites per platelet with a dissociation constant of 6.30 +/- 1.48 X 10(-7) M. ATP, apyrase, and the stimulators of platelet adenylate cyclase forskolin, prostaglandin E1, prostacyclin, and N6, 2'-O-dibutyryl cyclic AMP did not inhibit the fibrinogen-induced aggregation of elastase-treated platelets. EDTA completely blocked the initiation of aggregation and reversed the fibrinogen-induced aggregation of elastase-treated platelets. Monoclonal and polyclonal antibodies directed against glycoproteins (GP) IIb and IIIa completely blocked the fibrinogen-induced aggregation of elastase-treated platelets. Immunoprecipitates with these antibodies obtained from detergent extracts of surface-radiolabeled, intact, and elastase-treated platelets contained the glycoproteins IIb and IIIa. We conclude that surface proteolysis by low concentrations of elastase can expose fibrinogen-binding sites associated with GPIIb and GPIIIa on the platelet surface, resulting in spontaneous aggregation upon the addition of fibrinogen. These findings may be relevant to hemostatic changes observed in patients with increased levels of circulating elastase. Images PMID:3005363

  5. Fibronectin unfolded by adherent but not suspended platelets: An in vitro explanation for its dual role in haemostasis.

    PubMed

    Huynh, Khon; Gyenes, Marianna; Hollenberg, Cornelis P; Nguyen, Thi-Hiep; Van Vo, Toi; Stoldt, Volker R

    2015-10-01

    Fibronectin (FN), a dimeric adhesive glycoprotein, which is present both in plasma and the extracellular matrix can interact with platelets and thus contribute to platelet adhesion and aggregation. It has been shown that FN can decrease platelet aggregation but enhance platelet adhesion, suggesting a dual role of FN in haemostasis. The prevalent function(s) of FN may be determined by its fibril form. To explore the suggested dual role of this adhesive protein for haemostasis in further detail, we now tested for any differences of adherent and suspended platelets with regard to their effect to unfold and assemble FN upon interaction. Platelet aggregation and adhesion assays were performed using washed platelets in the presence of exogenous FN. Addition of plasma FN reduced platelet aggregation in response to collagen or PMA by 50% or 25% but enhanced platelet adhesion onto immobilized collagen, as compared to control experiments. Analyses by fluorescence resonance energy transfer (FRET) demonstrated that adherent platelets but not suspended platelets were capable of unfolding FN during 3h incubation. Fluorescence microscopy and deoxycholate (DOC) solubility assays demonstrated that FN fibrils formed only on the surfaces of adherent platelets. In addition, platelets adherent onto FN revealed a significantly higher activity of specific Src phosphorylation (pY418) than platelets in suspension. These data suggest (1) that the function of FN in haemostasis is prevalent to its assembly, unfolding and subsequent fibril formation on the surface of adherent platelets and (2) that outside-in signaling contributes to the interaction of platelets and FN.

  6. [A study of platelet abnormalities in obese subjects (author's transl)].

    PubMed

    Juhan, I; Gabrielli, M; Jouve, R; Calas, M F; Durand-Dessemon, F; Vague, J

    1980-03-01

    In 81 obese subjects the following studies were performed: --measurement of fat mass and its distribution in the body, --exploration of carbohydrate tolerance and lipid plasma level, --assessment of platelet aggregation and coagulation activity, --investigation of the chemical composition of platelet phospholipids. Platelet hyperactivity was demonstrated in certain patients, as evidenced by the presence of irreversible platelet aggregation with low doses of aggregation agents and by an increase in platelet coagulant activity; the latter phenomenon was not accompanied by a change in the biochemical composition of platelet phospholipids. Results of this work showed that platelet activity was not related to body weight and displayed no correlation or a slightly negative one to fat mass excess. Platelet activity was significantly increased in cases where obesity predominated in the upper body (hyperandroid obesity). The classical association of diabetes and atherosclerosis with hyperandroid obesity did not allow us to distinguish between the relative importance of hyperandroid obesity and diabetes in the observed platelet hyperactivity. Regardless of the causal mechanism involved, the relationship between platelet hyperactivity and upper body fat excess should be kept in mind.

  7. Autologous Platelet-Rich Plasma Preparations

    PubMed Central

    Schippinger, Gert; Prüller, Florian; Divjak, Manuela; Mahla, Elisabeth; Fankhauser, Florian; Rackemann, Steve; Raggam, Reinhard Bernd

    2015-01-01

    Background Autologous platelet-rich plasma (PRP) has been widely used for the treatment of sports injuries. It has been associated with improved healing and regeneration of soft tissues in elite athletes. Athletes are commonly receiving nonsteroidal anti-inflammatory drugs (NSAIDs). As yet, the effect of these drugs on platelet function in PRP formulations has not been taken into consideration. Hypothesis The function of platelets in PRP produced under the influence of NSAIDs is inhibited and may lessen a possible healing effect on the site of injury. Study Design Controlled laboratory study. Methods PRP was collected from patients receiving NSAIDs after elective orthopaedic surgery, and platelet function was evaluated using light transmission aggregometry (LTA). Results were compared with those obtained from healthy volunteers without a history of NSAID intake during the previous 2 weeks. Two different systems for blood collection and PRP production (Arthrex ACP double-syringe system and standard 4.5-mL sodium citrate blood collection tubes) were used and compared regarding the quality of PRP that was produced. Results For both groups, the baseline platelet counts of whole blood and the platelet counts of PRP formulations were found to be in the normal range. Both collection systems for PRP produced comparable results without significant differences between the groups. Platelet function testing with LTA revealed significantly impaired platelet aggregation in both PRP preparations, obtained from patients taking NSAIDs, irrespective of the type of NSAID (P < .001). All subjects from the control group showed normal platelet aggregation patterns when tested with LTA. Conclusion Autologous PRP produced from subjects after NSAID medication shows significantly impaired platelet function and may result in lower quality regarding the content of bioactive compounds. Clinical Relevance If required, the administration of NSAIDs should be performed after blood collection for

  8. Effects of trifluoperazine on platelet activation.

    PubMed

    Ardlie, N G; Boatwright, C; Garrett, J; McGuiness, J A

    1985-06-15

    Previous reports of the inhibitory effects of trifluoperazine on platelet responses to different aggregating agents have been conflicting, and the mechanism of action remains unclear. We have found that aggregation by minimum concentrations of collagen and arachidonic acid, and second phase aggregation by minimum concentrations of ADP, thrombin, epinephrine and the calcium ionophore A23187 were inhibited by 40-60 microM trifluoperazine. The first phase of aggregation by a minimum concentration of epinephrine was completely inhibited by 100 microM trifluoperazine, and the first phase of aggregation induced by ADP, thrombin or A23187 was decreased by 300 microM trifluoperazine. The platelet shape change caused by collagen, but by no other aggregating agent examined, was inhibited by 300 microM trifluoperazine. Secretion of 3H-5 hydroxytryptamine by minimum concentrations of ADP, collagen, epinephrine and arachidonic acid was completely suppressed by 50 microM trifluoperazine. Secretion by thrombin and A23187 was incompletely inhibited by 300 microM trifluoperazine. Thromboxane B2 formation caused by all aggregating agents, except epinephrine, was incompletely suppressed by 50 microM trifluoperazine, and 300 microM trifluoperazine only caused complete inhibition of thromboxane B2 formation by ADP, collagen and epinephrine. The phorbol ester, TPA, which mimics diacylglycerol by activating protein kinase C, caused aggregation and secretion. Aggregation, but not secretion, by low concentrations of TPA was inhibited by concentrations of trifluoperazine as low as 50 microM. However, aggregation by a combination of TPA and A23187 was only inhibited by concentrations of trifluoperazine in excess of 100 microM. Secretion by TPA was inhibited by concentrations of trifluoperazine in excess of 200 microM. Our findings suggest that low concentrations of trifluoperazine inhibit platelet activation by inhibiting phospholipase A2, and that higher concentrations inhibit platelet

  9. Effects of methaqualone on blood platelet function.

    PubMed

    Mills, D G

    1978-06-01

    To study the mechanism whereby toxic doses of methaqualone cause a bleeding tendency in humans, the effects of methaqualone, diphenhydramine, and the combination of methaqualone plus diphenhydramine on blood platelet function were investigated. Exposure of human platelets in platelet-rich plasma in vitro to final concentrations of methaqualone ranging from 1.1 to 4.5 X 10(-4)) M resulted in nearly complete inhibition of the secondary phase and significant inhibition of the primary phase of adenosine diphosphate (ADP)--induced aggregation. Both the slope and height of collagen-induced aggregation responses were reduced significantly in vitro by the drug. When methaqualone final concentrations of 1.1, 2.3, and 4.5 X 10(-4) M were studied in the presence of diphenhydramine (1.1, 2.3, and 4.5 X 10(-5) M, respectively), the degree of inhibition of ADP-induced aggregation was only slightly greater (not significant) than that observed with methaqualone. The platelets of rabbits injected intravenously with methaqualone, 10 mg/kg, demonstrated a significantly decreased ability to aggregate with ADP and collagen 30 and 60 min after administration of the drug. These results suggest that a drug-induced defect of blood platelet function may play a role in the bleeding associated with methaqualone toxicity.

  10. A factor VIII-derived peptide enables von Willebrand factor (VWF)-binding of artificial platelet nanoconstructs without interfering with VWF-adhesion of natural platelets

    NASA Astrophysics Data System (ADS)

    Haji-Valizadeh, Hassan; Modery-Pawlowski, Christa L.; Sen Gupta, Anirban

    2014-04-01

    There is substantial clinical interest in synthetic platelet analogs for potential application in transfusion medicine. To this end, our research is focused on self-assembled peptide-lipid nanoconstructs that can undergo injury site-selective adhesion and subsequently promote site-directed active platelet aggregation, thus mimicking platelet's primary hemostatic actions. For injury site-selective adhesion, we have utilized a coagulation factor FVIII-derived VWF-binding peptide (VBP). FVIII binds to VWF's D'-D3 domain while natural platelet GPIbα binds to VWF's A1 domain. Therefore, we hypothesized that the VBP-decorated nanoconstructs will adhere to VWF without mutual competition with natural platelets. We further hypothesized that the adherent VBP-decorated constructs can enhance platelet aggregation when co-decorated with a fibrinogen-mimetic peptide (FMP). To test these hypotheses, we used glycocalicin to selectively block VWF's A1 domain and, using fluorescence microscopy, studied the binding of fluorescently labeled VBP-decorated nanoconstructs versus platelets to ristocetin-treated VWF. Subsequently, we co-decorated the nanoconstructs with VBP and FMP and incubated them with human platelets to study construct-mediated enhancement of platelet aggregation. Decoration with VBP resulted in substantial construct adhesion to ristocetin-treated VWF even if the A1-domain was blocked by glycocalicin. In comparison, such A1-blocking resulted in significant reduction of platelet adhesion. Without A1-blocking, the VBP-decorated constructs and natural platelets could adhere to VWF concomitantly. Furthermore, the constructs co-decorated with VBP and FMP enhanced active platelet aggregation. The results indicate significant promise in utilizing the FVIII-derived VBP in developing synthetic platelet analogs that do not interfere with VWF-binding of natural platelets but allow site-directed enhancement of platelet aggregation when combined with FMP.There is substantial

  11. The influence of bromelain on platelet count and platelet activity in vitro.

    PubMed

    Gläser, Doreen; Hilberg, Thomas

    2006-02-01

    Bromelain is a general name for a family of sulfhydryl-containing, proteolytic enzymes from the pineapple plant. The aim of the present study was to investigate the influence of bromelain on platelet count, platelet aggregation and platelet activity in vitro. Blood samples were taken from the antecubital vein of 10 healthy male non-smokers. Platelet count decreased after incubation with 2.5 and 5 mg bromelain/ml from 277 +/- 17 platelets/nl before to 256 +/- 21 and 247 +/- 19 platelets/nl after the treatment. The ADP and TRAP-6 induced platelet aggregation led to a significant decrease after the incubation with 2.5 mg (ADP: 48.6 +/- 25.7%; TRAP-6: 49.6 +/- 28.9%) or 5 mg (ADP: 5.0 +/- 4.6%; TRAP-6: 9.0 +/- 4.9%) bromelain/ml in comparison to control (ADP: 81.4 +/- 5.0%; TRAP-6: 77.4 +/- 10.4%). The percentage of unstimulated CD62P positive platelets which were investigated by flow cytometry was minimally higher after incubation with 5 mg bromelain/ml (0.57 +/- 0.48% PC) in comparison to control (0.22 +/- 0.11% PC), but after TRAP-6 stimulation the incubation with 5 mg bromelain/ml led to a remarkable decrease in comparison to the untreated control (50.4 +/- 20.2 to 0.9 +/- 0.8% PC). The changes of CD62P (TRAP-stimulated) and the results of platelet aggregation after incubation with bromelain in vitro may demonstrate the potential of bromelain as a substance for platelet inhibition. PMID:16308185

  12. Platelet receptor polymorphisms do not influence Staphylococcus aureus-platelet interactions or infective endocarditis.

    PubMed

    Daga, Shruti; Shepherd, James G; Callaghan, J Garreth S; Hung, Rachel K Y; Dawson, Dana K; Padfield, Gareth J; Hey, Shi Y; Cartwright, Robyn A; Newby, David E; Fitzgerald, J Ross

    2011-03-01

    Cardiac vegetations result from bacterium-platelet adherence, activation and aggregation, and are associated with increased morbidity and mortality in infective endocarditis. The GPIIb/IIIa and FcγRIIa platelet receptors play a central role in platelet adhesion, activation and aggregation induced by endocarditis pathogens such as Staphylococcus aureus, but the influence of known polymorphisms of these receptors on the pathogenesis of infective endocarditis is unknown. We determined the GPIIIa platelet antigen Pl(A1/A2) and FcγRIIa H131R genotype of healthy volunteers (n = 160) and patients with infective endocarditis (n = 40), and investigated the influence of these polymorphisms on clinical outcome in infective endocarditis and S. aureus-platelet interactions in vitro. Platelet receptor genotype did not correlate with development of infective endocarditis, vegetation characteristics on echocardiogram or the composite clinical end-point of embolism, heart failure, need for surgery or mortality (P > 0.05 for all), even though patients with the GPIIIa Pl(A1/A1) genotype had increased in vivo platelet activation (P = 0.001). Furthermore, neither GPIIIa Pl(A1/A2) nor FcγRIIa H131R genotype influenced S. aureus-induced platelet adhesion, activation or aggregation in vitro (P > 0.05). Taken together, our data suggest that the GPIIIa and FcγRIIa platelet receptor polymorphisms do not influence S. aureus-platelet interactions in vitro or the clinical course of infective endocarditis.

  13. [A new highly sensitive method of analysis of thrombocyte aggregation].

    PubMed

    Gabbasov, Z A; Popov, E G; Gavrilov, I Iu; Pozin, E Ia; Markosian, R A

    1989-01-01

    The new method for studies of the platelet aggregation kinetics is based on the creation of a platelet stream through the optic canal and on an analysis of fluctuations in the intensity of the luminous flux that has passed through the sample. The relative dispersion of fluctuations in the intensity of the light passed through the sample is suggested as a parameter for the estimation of the platelet aggregation and for analysis of their aggregation kinetics. The method permits recording the platelet aggregation in citrate plasma, enriched for platelets, after exposure to the inductor in very low concentrations (0.05-0.15 microM ADP). Scanning electron microscopy has shown that aggregates are indeed formed in such cases, and they can be recorded from the increase of the relative dispersion in the fluctuations in the passed light intensity but cannot be recorded by Born's optic method.

  14. A factor VIII-derived peptide enables von Willebrand factor (VWF)-binding of artificial platelet nanoconstructs without interfering with VWF-adhesion of natural platelets.

    PubMed

    Haji-Valizadeh, Hassan; Modery-Pawlowski, Christa L; Sen Gupta, Anirban

    2014-05-01

    There is substantial clinical interest in synthetic platelet analogs for potential application in transfusion medicine. To this end, our research is focused on self-assembled peptide-lipid nanoconstructs that can undergo injury site-selective adhesion and subsequently promote site-directed active platelet aggregation, thus mimicking platelet's primary hemostatic actions. For injury site-selective adhesion, we have utilized a coagulation factor FVIII-derived VWF-binding peptide (VBP). FVIII binds to VWF's D'-D3 domain while natural platelet GPIbα binds to VWF's A1 domain. Therefore, we hypothesized that the VBP-decorated nanoconstructs will adhere to VWF without mutual competition with natural platelets. We further hypothesized that the adherent VBP-decorated constructs can enhance platelet aggregation when co-decorated with a fibrinogen-mimetic peptide (FMP). To test these hypotheses, we used glycocalicin to selectively block VWF's A1 domain and, using fluorescence microscopy, studied the binding of fluorescently labeled VBP-decorated nanoconstructs versus platelets to ristocetin-treated VWF. Subsequently, we co-decorated the nanoconstructs with VBP and FMP and incubated them with human platelets to study construct-mediated enhancement of platelet aggregation. Decoration with VBP resulted in substantial construct adhesion to ristocetin-treated VWF even if the A1-domain was blocked by glycocalicin. In comparison, such A1-blocking resulted in significant reduction of platelet adhesion. Without A1-blocking, the VBP-decorated constructs and natural platelets could adhere to VWF concomitantly. Furthermore, the constructs co-decorated with VBP and FMP enhanced active platelet aggregation. The results indicate significant promise in utilizing the FVIII-derived VBP in developing synthetic platelet analogs that do not interfere with VWF-binding of natural platelets but allow site-directed enhancement of platelet aggregation when combined with FMP.

  15. Effect of propranolol on platelet signal transduction.

    PubMed Central

    Dash, D; Rao, K

    1995-01-01

    Propranolol inhibits platelet secondary aggregation and secretion by mechanisms unrelated to its beta-adrenergic-blocking activity. We previously reported that a major effect of the drug is perturbation of the physical microenvironment of the human platelet membrane. To explore further the molecular mechanisms underlying propranolol-mediated platelet inhibition, we studied protein kinase C activity, estimated from the phosphorylation of the substrate protein pleckstrin, in propranolol-treated human platelets. The drug inhibited activation of the enzyme in thrombin-stimulated platelets but not in platelets stimulated with phorbol esters, indicating that its site of action might be upstream of protein kinase C. It also inhibited the activity of phospholipase C, determined from the extent of generation of inositol phosphates and phosphatidic acid, in platelets stimulated with thrombin as well as the non-hydrolysable GTP analogue guanosine 5'-[beta, gamma-imido]triphosphate in a dose-dependent manner. These data suggest that propranolol inhibits signal transduction in thrombin-stimulated platelets by interacting at the level of phospholipase C and exclude interaction of the drug with the downstream effector enzyme protein kinase C. Images Figure 1 Figure 2 Figure 3 PMID:7619088

  16. Hydrogen peroxide is involved in collagen-induced platelet activation.

    PubMed

    Pignatelli, P; Pulcinelli, F M; Lenti, L; Gazzaniga, P P; Violi, F

    1998-01-15

    In this study, we investigated whether (1) collagen-induced platelet aggregation is associated with a burst of H2O2, (2) this oxidant species is involved in the activation of platelets, and (3) the pathways of platelet activation are stimulated by H2O2. Collagen-induced platelet aggregation was associated with production of H2O2, which was abolished by catalase, an enzyme that destroys H2O2. H2O2 production was not observed when ADP or thrombin were used as agonists. Catalase inhibited dose-dependently thromboxane A2 production, release of arachidonic acid from platelet membrane, and Inositol 1,4,5P3 (IP3) formation. In aspirin-treated platelets stimulated with high concentrations of collagen, catalase inhibited platelet aggregation, calcium mobilization, and IP3 production. This study suggests that collagen-induced platelet aggregation is associated with a burst of H2O2 that acts as a second messenger by stimulating the arachidonic acid metabolism and phospholipase C pathway.

  17. Common variants in the human platelet PAR4 thrombin receptor alter platelet function and differ by race.

    PubMed

    Edelstein, Leonard C; Simon, Lukas M; Lindsay, Cory R; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E; Chen, Edward S; Ma, Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A; Bray, Paul F

    2014-11-27

    Human platelets express 2 thrombin receptors: protease-activated receptor (PAR)-1 and PAR4. Recently, we reported 3.7-fold increased PAR4-mediated aggregation kinetics in platelets from black subjects compared with white subjects. We now show that platelets from blacks (n = 70) express 14% more PAR4 protein than those from whites (n = 84), but this difference is not associated with platelet PAR4 function. Quantitative trait locus analysis identified 3 common single nucleotide polymorphisms in the PAR4 gene (F2RL3) associated with PAR4-induced platelet aggregation. Among these single nucleotide polymorphisms, rs773902 determines whether residue 120 in transmembrane domain 2 is an alanine (Ala) or threonine (Thr). Compared with the Ala120 variant, Thr120 was more common in black subjects than in white subjects (63% vs 19%), was associated with higher PAR4-induced human platelet aggregation and Ca2+ flux, and generated greater inositol 1,4,5-triphosphate in transfected cells. A second, less frequent F2RL3 variant, Phe296Val, was only observed in blacks and abolished the enhanced PAR4-induced platelet aggregation and 1,4,5-triphosphate generation associated with PAR4-Thr120. PAR4 genotype did not affect vorapaxar inhibition of platelet PAR1 function, but a strong pharmacogenetic effect was observed with the PAR4-specific antagonist YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole]. These findings may have an important pharmacogenetic effect on the development of new PAR antagonists.

  18. Common variants in the human platelet PAR4 thrombin receptor alter platelet function and differ by race

    PubMed Central

    Edelstein, Leonard C.; Simon, Lukas M.; Lindsay, Cory R.; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E.; Chen, Edward S.; Ma, Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A.

    2014-01-01

    Human platelets express 2 thrombin receptors: protease-activated receptor (PAR)-1 and PAR4. Recently, we reported 3.7-fold increased PAR4-mediated aggregation kinetics in platelets from black subjects compared with white subjects. We now show that platelets from blacks (n = 70) express 14% more PAR4 protein than those from whites (n = 84), but this difference is not associated with platelet PAR4 function. Quantitative trait locus analysis identified 3 common single nucleotide polymorphisms in the PAR4 gene (F2RL3) associated with PAR4-induced platelet aggregation. Among these single nucleotide polymorphisms, rs773902 determines whether residue 120 in transmembrane domain 2 is an alanine (Ala) or threonine (Thr). Compared with the Ala120 variant, Thr120 was more common in black subjects than in white subjects (63% vs 19%), was associated with higher PAR4-induced human platelet aggregation and Ca2+ flux, and generated greater inositol 1,4,5-triphosphate in transfected cells. A second, less frequent F2RL3 variant, Phe296Val, was only observed in blacks and abolished the enhanced PAR4-induced platelet aggregation and 1,4,5-triphosphate generation associated with PAR4-Thr120. PAR4 genotype did not affect vorapaxar inhibition of platelet PAR1 function, but a strong pharmacogenetic effect was observed with the PAR4-specific antagonist YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole]. These findings may have an important pharmacogenetic effect on the development of new PAR antagonists. PMID:25293779

  19. Abnormal Whole Blood Thrombi in Humans with Inherited Platelet Receptor Defects

    PubMed Central

    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

    2012-01-01

    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. PMID:23300803

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

    PubMed Central

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

    2014-01-01

    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 spectrometry analysis of lipids (termed “lipidomics”) has begun to alter our understanding of how these molecules participate in key cellular processes. While, the application of lipidomics to platelet biology is still in its infancy, seminal earlier studies have shaped our knowledge of how lipids regulate key aspects of platelet biology, including aggregation, shape change, coagulation and degranulation, as well as how lipids generated by platelets influence other cells, such as leukocytes and the vascular wall, and thus how they regulate hemostasis, vascular integrity and inflammation, as well as contribute to pathologies including arterial/deep vein thrombosis and atherosclerosis. This review will provide a brief historical perspective on the characterization of lipids in platelets, then an overview of the new generation lipidomic approaches, their recent application to platelet biology, and future perspectives for research in this area. The major platelet-regulatory lipid families, their formation, metabolism, and their role in health and disease, will be summarized. PMID:24677238

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

    PubMed

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

    2014-03-28

    Lipids are diverse families of biomolecules that perform essential structural and signaling roles in platelets. Their formation and metabolism are 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 plays essential roles in hemostasis. In recent years, new generation mass spectrometry analysis of lipids (termed lipidomics) has begun to alter our understanding of how these molecules participate in key cellular processes. Although the application of lipidomics to platelet biology is still in its infancy, seminal earlier studies have shaped our knowledge of how lipids regulate key aspects of platelet biology, including aggregation, shape change, coagulation, and degranulation, as well as how lipids generated by platelets influence other cells, such as leukocytes and the vascular wall, and thus how they regulate hemostasis, vascular integrity, and inflammation, as well as contribute to pathologies, including arterial/deep vein thrombosis and atherosclerosis. This review will provide a brief historical perspective on the characterization of lipids in platelets, then an overview of the new generation lipidomic approaches, their recent application to platelet biology, and future perspectives for research in this area. The major platelet-regulatory lipid families, their formation, metabolism, and their role in health and disease, will be summarized.

  2. Involvement of platelet cyclic GMP but not cyclic AMP suppression in leukocyte-dependent platelet adhesion to endothelial cells induced by platelet-activating factor in vitro.

    PubMed Central

    Hirafuji, M.; Nezu, A.; Shinoda, H.; Minami, M.

    1996-01-01

    1. Incubation of endothelial cells with platelets in the absence or the presence of PAF (10 nM) markedly increased platelet cyclic AMP levels, which were significantly decreased by indomethacin (3 microM). Co-incubation of endothelial cells and platelets with polymorphonuclear leukocytes (PMNs) did not change the platelet cyclic AMP levels. 2. Incubation of endothelial cells with platelets in the absence of PAF increased platelet cyclic GMP levels, which were increased 3.5 fold by PAF. These cyclic GMP levels were significantly decreased by NG-nitro-L-arginine (100 microM), and completely by methylene blue (10 microM). When endothelial cells and platelets were co-incubated with PMNs, the cyclic GMP level in the cell mixture was 42.5 and 65.3% lower than that in endothelial cells and platelets without and with PAF stimulation, respectively. 3. PAF induced platelet adhesion to endothelial cells only when PMNs were present. Methylene blue dose-dependently potentiated the PMN-dependent platelet adhesion induced by PAF, although it had no effect in the absence of PMNs. 4. Sodium nitroprusside and 8-bromo cyclic GMP but not dibutyryl cyclic AMP significantly, although partially, inhibited the platelet adhesion. Inhibition of cyclic GMP-specific phosphodiesterase by zaprinast slightly inhibited the PMN-induced platelet adhesion and potentiated the inhibitory effect of 8-bromo cyclic GMP, while these drugs markedly inhibited the adhesion of platelet aggregates induced by PMN sonicates. 5. These results suggest that the impairment by activated PMNs of EDRF-induced platelet cyclic GMP formation is involved in part in the mechanism of PMN-dependent platelet adhesion to endothelial cells induced by PAF in vitro. The precise mechanism still remains to be clarified. PMID:8789382

  3. Optimized Preparation Method of Platelet-Concentrated Plasma and Noncoagulating Platelet-Derived Factor Concentrates: Maximization of Platelet Concentration and Removal of Fibrinogen

    PubMed Central

    Araki, Jun; Jona, Masahiro; Eto, Hitomi; Aoi, Noriyuki; Kato, Harunosuke; Suga, Hirotaka; Doi, Kentaro; Yatomi, Yutaka

    2012-01-01

    Abstract Platelet-rich plasma (PRP) has been clinically used as an easily prepared growth factor cocktail that can promote wound healing, angiogenesis, and tissue remodeling. However, the therapeutic effects of PRP are still controversial, due partly to the lack of optimized and standardized preparation protocols. We used whole blood (WB) samples to optimize the preparation protocols for PRP, white blood cell-containing (W-PRP), platelet-concentrated plasma (PCP), and noncoagulating platelet-derived factor concentrate (PFC). PRP and W-PRP were most efficiently collected by 10 min centrifugation in a 15-mL conical tube at 230–270 g and 70 g, respectively. To prepare PCP, platelets were precipitated by centrifugation of PRP at >2300 g, 90% of supernatant plasma was removed, and the platelets were resuspended. For preparation of noncoagulating PFC, the supernatant was replaced with one-tenth volume of saline, followed by platelet activation with thrombin. Platelet (before activation) and platelet-derived growth factor (PDGF)-BB (after activation) concentrations in PCP were approximately 20 times greater than those in WB, whereas PFC contained a 20-times greater concentration of platelets before platelet activation and a 50-times greater concentration of PDGF-BB without formation of a fibrin gel after platelet activation than WB. Surprisingly, total PDGF-BB content in the PFC was twice that of activated WB, which suggested that a substantial portion of the PDGF-BB became trapped in the fibrin glue, and replacement of plasma with saline is crucial for maximization of platelet-derived factors. As an anticoagulant, ethylene di-amine tetra-acetic acid disodium inhibited platelet aggregation more efficiently than acid citrate dextrose solution, resulting in higher nonaggregated platelet yield and final PDGF-BB content. These results increase our understanding of how to optimize and standardize preparation of platelet-derived factors at maximum concentrations. PMID

  4. Platelets, immune-mediated thrombocytopenias, and fetal hemorrhage.

    PubMed

    Xu, Xiaohong Ruby; Gallant, Reid C; Ni, Heyu

    2016-05-01

    Platelets are small versatile blood cells generated from megakaryocytes in the bone marrow and cleared in the reticuloendothelial system. Platelet accumulation (adhesion and aggregation) at the site of injury has been considered the first wave of hemostasis. Interestingly, although fibrinogen and von Willebrand factor (VWF) are documented to be essential for hemostasis, fibrinogen/VWF-independent platelet aggregation and thrombosis still occur. Following platelet activation and phosphatidylserine expression, platelets also contribute to cell-based thrombin generation and blood coagulation - the second wave of hemostasis. Most recently, deposition of fibronectin and other plasma proteins onto the injured vessel wall was identified as a "protein wave" of hemostasis, in which platelets may release their granule proteins and thus also contribute to this very early hemostatic event. Due to the central roles of platelets in hemostasis, excessive platelet clearance may lead to bleeding disorders as observed in auto- and alloimmune-mediated thrombocytopenias. In this review, we will introduce several new pathways of thrombosis and hemostasis as well as antibody Fc-independent platelet clearance, which may play an important role in immune-mediated thrombocytopenias. We will also discuss the roles of platelets in fetal hemostasis that may deserve further investigation. PMID:27207432

  5. Platelet functions in relation to dietary fats in farmers from two regions of France.

    PubMed

    Renaud, S; Dumont, E; Godsey, F; Suplisson, A; Thevenon, C

    1979-02-15

    To determine whether the long-term feeding of dietary fats affect platelet functions in man, platelet aggregation (to thrombin ADP, collagen, epinephrine) and clotting activity of platelet-rich plasma (PRP), platelet-poor plasma and of washed platelets were studied in a mobile-laboratory in 44 healthy male farmers (40--45 years) from two French regions Var and Moselle, in relation to lipemia, glycemia, dietary nutriments, and platelet phospholipid composition. In the Moselle subjects, the platelet clotting activity of PRP and of washed platelets, the platelet aggregation to thrombin and ADP, were highly significantly (p less than 0.001) increased as compared to those of Var, but not the plasma cholesterol, which was identical in the two regions. In Moselle, the intake of total calories, total lipids and saturated fats was higher than in the Var. However, it was only with the saturated fat intake (mostly stearic acid) that the platelet clotting activity (p less than 0.01) and the platelet aggregation (p less than 0.001) were highly significantly correlated. The platelet clotting activity was also significantly (p less than 0.001) correlated with the fatty acid composition of the platelet phospholipid fractions phosphatidyl serine + phosphatidyl inositol.

  6. Zinc is a transmembrane agonist that induces platelet activation in a tyrosine phosphorylation-dependent manner.

    PubMed

    Watson, Ben R; White, Nathan A; Taylor, Kirk A; Howes, Joanna-Marie; Malcor, Jean-Daniel M; Bihan, Dominique; Sage, Stewart O; Farndale, Richard W; Pugh, Nicholas

    2016-01-01

    Following platelet adhesion and primary activation at sites of vascular injury, secondary platelet activation is induced by soluble platelet agonists, such as ADP, ATP, thrombin and thromboxane. Zinc ions are also released from platelets and damaged cells and have been shown to act as a platelet agonist. However, the mechanism of zinc-induced platelet activation is not well understood. Here we show that exogenous zinc gains access to the platelet cytosol and induces full platelet aggregation that is dependent on platelet protein tyrosine phosphorylation, PKC and integrin αIIbβ3 activity and is mediated by granule release and secondary signalling. ZnSO4 increased the binding affinity of GpVI, but not integrin α2β1. Low concentrations of ZnSO4 potentiated platelet aggregation by collagen-related peptide (CRP-XL), thrombin and adrenaline. Chelation of intracellular zinc reduced platelet aggregation induced by a number of different agonists, inhibited zinc-induced tyrosine phosphorylation and inhibited platelet activation in whole blood under physiologically relevant flow conditions. Our data are consistent with a transmembrane signalling role for zinc in platelet activation during thrombus formation.

  7. Assessment of platelet function in healthy sedated cats using three whole blood platelet function tests.

    PubMed

    Ho, Kimberly K; Abrams-Ogg, Anthony C G; Wood, R Darren; O'Sullivan, M Lynne; Kirby, Gordon M; Blois, Shauna L

    2015-05-01

    The objectives of this study were to establish feline references intervals for 3 commercial whole blood platelet function test analyzer systems: Multiplate analyzer (MP; Roche Diagnostics International Ltd., Rotkreuz, Switzerland), Platelet Function Analyzer-100 (PF: Siemens Canada, Mississauga, Ontario, Canada), and Plateletworks Combo-25 kit (PW; Helena Laboratories, Beaumont, TX). Venipuncture was performed on 55 healthy sedated cats, and platelet aggregation in response to adenosine diphosphate (ADP), collagen (COL), and arachidonic acid (AA; MP only) was assessed using citrated blood. For the MP analyzer, median (95% confidence intervals [CIs]) area under curve (Units) for ADP, COL, and AA agonists were 87 (11-176), 81 (32-129), and 91 (59-129), respectively. For the PF analyzer, median (95% CIs) closure time, using COL-ADP cartridges, was 69 (46-89) sec. For the PW assay, median (95% CIs) percent aggregations for ADP and COL agonists were 71 (18-92) and 49 (9-96), respectively, using impedance hematology analyzer platelet counts, and 94 (25-98) and 68 (14-119), respectively, using flow cytometry hematology analyzer platelet counts. There were low correlations between the PF analyzer (COL-ADP cartridge) and MP analyzer (COL agonist; ρ = 0.11), and between the PF analyzer (COL-ADP cartridge) and PW assay (COL agonist using impedance platelet counts; ρ = 0.14). The PW assay percent aggregations using impedance and flow cytometric platelet counts were correlated for both ADP (ρ = 0.64) and COL (ρ = 0.64) agonists. Platelet function testing using these tests are feasible in cats, but 95% CIs are wide, so single results may be difficult to interpret. Platelet counting by impedance or flow cytometry may be used for the PW assay but are not interchangeable.

  8. Radiolabelling of platelets with technetium-99m

    SciTech Connect

    Sundrehagen, E.; Urdal, P.; Heggli, D.E.; Lindegaard, M.W.; Jacobsen, E. )

    1990-03-01

    A method for labelling of platelets with technetium-99m (Tc-99m) is presented. In principle, aminobenzoic acid and tartaric acid are used as reagents, allowing Tc-99m complexes of intermediate chemical stability to be formed. These complexes react rapidly with proteins, such as platelet proteins, when added. We have examined the isolation procedure for the platelets and the labelling procedure using residual aggregational ability and residual content of beta-thromboglobulin (beta-TG) as indicators of damage to the platelets. In its final version the method allowed a 32.6 +/- 2.7% (mean +/- SD) incorporation of Tc-99m into platelets which again showed a 66 +/- 15% residual aggregational ability, tested by 50 mumol/l of ADP, and a 79 +/- 17% residual content of beta-TG releasable by 10 IU/ml of thrombin. In a pilot clinical study involving 28 patients we found labelled autologous platelets useful in detecting lung embolism and deep vein thrombosis.

  9. [Applications of platelets in studies on traditional Chinese medicines promoting blood circulation to remove blood stasis].

    PubMed

    Wang, Feng-Qin; Chen, Cen; Xia, Zhi-Ning; Yang, Feng-Qing

    2014-08-01

    Thrombotic diseases in different forms become a great threat to human health. Such anti-platelet aggregation drugs as aspirin and clopidogrel are common drugs in clinic. However, along with the appearance of resistance and side effects of western anti-platelet aggregation drugs, anti-platelet aggregation traditional Chinese medicines promoting blood circulation to remove blood stasis have gradually become an important study orientation. Platelet is one of major participant in thrombosis, and plays an important role as a bioactive material in studies on traditional Chinese medicines promoting blood circulation to remove blood stasis, mainly involving two aspects--the evaluation for the anti-platelet aggregation activity of traditional Chinese medicines and the screening of their active components. This paper summarized the applications of platelets in studies on traditional Chinese medicines promoting blood circulation to remove blood stasis, so as to provide basis for further studies.

  10. Platelet-like nanoparticles: mimicking shape, flexibility, and surface biology of platelets to target vascular injuries.

    PubMed

    Anselmo, Aaron C; Modery-Pawlowski, Christa Lynn; Menegatti, Stefano; Kumar, Sunny; Vogus, Douglas R; Tian, Lewis L; Chen, Ming; Squires, Todd M; Sen Gupta, Anirban; Mitragotri, Samir

    2014-11-25

    Targeted delivery of therapeutic and imaging agents in the vascular compartment represents a significant hurdle in using nanomedicine for treating hemorrhage, thrombosis, and atherosclerosis. While several types of nanoparticles have been developed to meet this goal, their utility is limited by poor circulation, limited margination, and minimal targeting. Platelets have an innate ability to marginate to the vascular wall and specifically interact with vascular injury sites. These platelet functions are mediated by their shape, flexibility, and complex surface interactions. Inspired by this, we report the design and evaluation of nanoparticles that exhibit platelet-like functions including vascular injury site-directed margination, site-specific adhesion, and amplification of injury site-specific aggregation. Our nanoparticles mimic four key attributes of platelets, (i) discoidal morphology, (ii) mechanical flexibility, (iii) biophysically and biochemically mediated aggregation, and (iv) heteromultivalent presentation of ligands that mediate adhesion to both von Willebrand Factor and collagen, as well as specific clustering to activated platelets. Platelet-like nanoparticles (PLNs) exhibit enhanced surface-binding compared to spherical and rigid discoidal counterparts and site-selective adhesive and platelet-aggregatory properties under physiological flow conditions in vitro. In vivo studies in a mouse model demonstrated that PLNs accumulate at the wound site and induce ∼65% reduction in bleeding time, effectively mimicking and improving the hemostatic functions of natural platelets. We show that both the biochemical and biophysical design parameters of PLNs are essential in mimicking platelets and their hemostatic functions. PLNs offer a nanoscale technology that integrates platelet-mimetic biophysical and biochemical properties for potential applications in injectable synthetic hemostats and vascularly targeted payload delivery. PMID:25318048

  11. Platelet morphologic changes and fibrinogen receptor localization. Initial responses in ADP-activated human platelets.

    PubMed

    Hensler, M E; Frojmovic, M; Taylor, R G; Hantgan, R R; Lewis, J C

    1992-09-01

    Platelet exposure to agonists results in rapid morphologic changes paralleled by fibrinogen binding and platelet aggregation. The current study used standardized stereology in conjunction with immunogold electron microscopy to correlate the initial morphologic changes with fibrinogen receptor localization on the surfaces of ADP-activated human platelets. A 45% increase in platelet circumference was observed after 3 seconds of activation (P = 0.001). Virtually all of this increase was due to a 13-fold increase in projection membrane, and the projections observed by stereo microscopy at this time were mostly blunt. Both blunt and long projections also accounted for the increase in platelet-platelet contacts at 10 seconds of activation. Immunogold electron microscopy using the monoclonal antibodies P2 and AP-2 against the fibrinogen receptor, glycoprotein IIb/IIIa (GP IIb/IIIa), showed relatively equivalent immunogold densities on projections compared with cell body during 30 seconds of activation. The activation-dependent anti-GP IIb/IIIa monoclonal antibody, 7E3, showed an immunogold density 37% greater on projections compared with cell body (P = 0.0001). Colocalization studies using 7E3 with a polyclonal antifibrinogen antibody showed bound fibrinogen in close proximity to the GP IIb/IIIa localized by 7E3 on projections. These studies support an important role for platelet projections during the earliest stages of fibrinogen binding and ADP-induced aggregation.

  12. Inherited platelet disorders.

    PubMed

    Franchini, Massimo; Lippi, Giuseppe; Veneri, Dino; Targher, Giovanni; Zaffanello, Marco; Guidi, Gian Cesare

    2008-01-01

    Inherited platelet disorders are a rare, but probably underdiagnosed, cause of symptomatic bleeding. They are characterized by abnormalities of platelet number (inherited thrombocytopenias), function (inherited disorders of platelet function) or both. This review briefly discusses the inherited platelet disorders with respect to molecular defects, diagnostic evaluation and treatment strategies.

  13. Platelet protein disulfide isomerase is required for thrombus formation but not for hemostasis in mice.

    PubMed

    Kim, Kyungho; Hahm, Eunsil; Li, Jing; Holbrook, Lisa-Marie; Sasikumar, Parvathy; Stanley, Ronald G; Ushio-Fukai, Masuko; Gibbins, Jonathan M; Cho, Jaehyung

    2013-08-01

    Protein disulfide isomerase (PDI) derived from intravascular cells is required for thrombus formation. However, it remains unclear whether platelet PDI contributes to the process. Using platelet-specific PDI-deficient mice, we demonstrate that PDI-null platelets have defects in aggregation and adenosine triphosphate secretion induced by thrombin, collagen, and adenosine diphosphate. Such defects were rescued by wild-type but not mutant PDI, indicating that the isomerase activity of platelet surface PDI is critical for the regulatory effect. PDI-deficient platelets expressed increased levels of intracellular ER protein 57 (ERp57) and ERp72. Platelet PDI regulated αIIbβ3 integrin activation but not P-selectin exposure, Ca(2+) mobilization, β3-talin1 interaction, or platelet spreading on immobilized fibrinogen. Inhibition of ERp57 further diminished αIIbβ3 integrin activation and aggregation of activated PDI-deficient platelets, suggesting distinct roles of PDI and ERp57 in platelet functions. We found that platelet PDI is important for thrombus formation on collagen-coated surfaces under shear. Intravital microscopy demonstrates that platelet PDI is important for platelet accumulation but not initial adhesion and fibrin generation following laser-induced arteriolar injury. Tail bleeding time in platelet-specific PDI-deficient mice were not significantly increased. Our results provide important evidence that platelet PDI is essential for thrombus formation but not for hemostasis in mice. PMID:23788140

  14. [Prophylactic platelet transfusions].

    PubMed

    Ilmakunnas, Minna; Remes, Kari; Hiippala, Seppo; Mäkisalo, Heikki; Åberg, Fredrik

    2016-01-01

    The consumption of platelet products in Finland is exceptionally high. For the most part, platelets are transfused pre-operatively to thrombocytopenic patients in order to prevent hemorrhage. Most of the minor procedures could, however, be conducted even if the patients'platelet levels would be lower than usual. In cardiac surgery, platelets are used because of the hemorrhagic diathesis associated with platelet inhibitors. Platelet inhibitors will, however, also bind to transfused platelets, whereby instead of prophylactic platelet transfusions it would be more sensible to leave the thorax open and not carry out ineffective platelet transfusions until the effect of the inhibitors has run out. We outline the prophylactic use of platelets based on recent international clinical practice guidelines. PMID:27400590

  15. Proplatelets and stress platelets.

    PubMed

    Tong, M; Seth, P; Penington, D G

    1987-02-01

    The process of platelet formation by the fragmentation of megakaryocyte pseudopodia, termed proplatelets, demonstrable in the marrow sinusoids is poorly understood. "Stress" platelets produced under conditions of stimulated platelet production differ from normal circulating platelets with respect to volume and a number of functional characteristics. To clarify the relationship of stress platelets to proplatelets, rats were injected with heterologous platelet antiserum. Nondiscoid platelet forms, some characteristically beaded in appearance, strongly resembling bone marrow proplatelets, can be recovered in the circulation of normal rats. During the early period of recovery from acute thrombocytopenia, there was a substantial increase in the proportion of these elongated platelets in the citrated platelet rich plasma. Exposure to EDTA rendered them spherical. Circulating proplatelets may contribute significantly to the prompt increase in platelet volume during recovery from acute thrombocytopenia at a time prior to significant increase in megakaryocyte size and ploidy. PMID:3801667

  16. Role of oxidative stress on platelet hyperreactivity during aging.

    PubMed

    Fuentes, Eduardo; Palomo, Iván

    2016-03-01

    Thrombotic events are common causes of morbidity and mortality in the elderly. Age-accelerated vascular injury is commonly considered to result from increased oxidative stress. There is abundant evidence that oxidative stress regulate several components of thrombotic processes, including platelet activation. Thus oxidative stress can trigger platelet hyperreactivity by decreasing nitric oxide bioavailability. Therefore oxidative stress measurement may help in the early identification of asymptomatic subjects at risk of thrombosis. In addition, oxidative stress inhibitors and platelet-derived nitric oxide may represent a novel anti-aggregation/-activation approach. In this article the relative contribution of oxidative stress and platelet activation in aging is explored.

  17. Interaction of the protein C activation peptide with platelets.

    PubMed

    Martínez-Cruz, Ruth; Canseco, María Del S Pina; Lopez-Martínez, Jael; Cruz, Pedro A Hernández; Pérez-Campos, Eduardo; Cruz, Margarito Martínez; Alva, Félix Córdoba; Majluf-Cruz, Abraham; Zenteno, Edgar; Ruiz-Argüelles, Alejandro

    2007-01-01

    The peptide NH(2)-DTEDQEDQVDPR-COOH is released during activation of protein C zymogen. We measured the effect of a synthetic peptide with an amino acid sequence similar to that of the natural peptide on platelets from healthy individuals using platelet aggregometry. We found that this synthetic peptide inhibits platelet aggregation induced by thrombin; furthermore, it diminishes mobilization of intraplatelet calcium. Molecular docking showed weak interaction between the synthetic peptide and thrombin. Our findings suggest that this synthetic peptide may interact with a receptor located on the platelet cell membrane.

  18. External quality assessment of platelet disorder investigations: results of international surveys on diagnostic tests for dense granule deficiency and platelet aggregometry interpretation.

    PubMed

    Hayward, Catherine P M; Moffat, Karen A; Plumhoff, Elizabeth; Timleck, Marnie; Hoffman, Suzanne; Spitzer, Ernie; Van Cott, Elizabeth M; Meijer, Piet

    2012-09-01

    The quality of platelet aggregation and dense granule deficiency testing is important for diagnosing platelet function disorders. After a successful pilot exercise on diagnosing platelet dense granule deficiency by electron microscopy (EM), the North American Specialized Coagulation Laboratory Association (NASCOLA) has launched regular external quality assurance (EQA) for dense granule EM, as well as for the interpretation of platelet aggregation findings. EQA records were analyzed to assess performance. For EM EQA, between 2009 and 2011, there was excellent performance in distinguishing normal from dense granule-deficient samples and good (>70%) agreement on classifying most electron dense structures in platelets. For aggregation EQA, some normal variants were misclassified and overall case interpretations were more acceptable for rare disorders than for common findings. NASCOLA experiences with these EQAs indicate that there is a need to improve the quality of platelet disorder evaluations. For aggregometry interpretations, deficits in performance could be addressed by translating guideline recommendations into practice.

  19. Current and emerging approaches for evaluating platelet disorders.

    PubMed

    Podda, G; Femia, E A; Cattaneo, M

    2016-05-01

    Platelets play a central role in physiological hemostasis and also in pathological thrombosis. It is well established that congenital or acquired abnormalities of platelet function are associated with a heightened risk of bleeding of variable severity and excessive hemorrhage after surgery or trauma. Several kinds of different platelet function tests have been developed over the years to identify or diagnose platelet function disorders. The use of these tests for the assessment of thrombotic risk or for monitoring the effects of drugs inhibiting platelet function is not well established. Light transmission aggregometry (LTA) is the gold standard for the study of patients with defects of platelet function. Its results are affected by several pre-analytical and analytical variables. The Subcommittee on Platelet Physiology of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis published official guidelines for the standardization of the variables affecting LTA, which should be followed to harmonize the procedures across different laboratories worldwide. The lumi-aggregometer, a modification of LTA that measures platelet secretion in parallel with aggregation, is preferable to LTA for diagnosing inherited defects of platelet function, because it is more sensitive to the most common disorders, which are characterized by abnormalities of platelet secretion. LTA (or lumi-aggregometry) is useful as a first screening test of patients with the clinical suspicion of defects of platelet function, because it helps to provide an interim diagnostic hypothesis, which can then be confirmed or discounted using appropriate and specific tests. PMID:27426860

  20. Microfluidics for simultaneous quantification of platelet adhesion and blood viscosity

    PubMed Central

    Yeom, Eunseop; Park, Jun Hong; Kang, Yang Jun; Lee, Sang Joon

    2016-01-01

    Platelet functions, including adhesion, activation, and aggregation have an influence on thrombosis and the progression of atherosclerosis. In the present study, a new microfluidic-based method is proposed to estimate platelet adhesion and blood viscosity simultaneously. Blood sample flows into an H-shaped microfluidic device with a peristaltic pump. Since platelet aggregation may be initiated by the compression of rotors inside the peristaltic pump, platelet aggregates may adhere to the H-shaped channel. Through correlation mapping, which visualizes decorrelation of the streaming blood flow, the area of adhered platelets (APlatelet) can be estimated without labeling platelets. The platelet function is estimated by determining the representative index IA·T based on APlatelet and contact time. Blood viscosity is measured by monitoring the flow conditions in the one side channel of the H-shaped device. Based on the relation between interfacial width (W) and pressure ratio of sample flows to the reference, blood sample viscosity (μ) can be estimated by measuring W. Biophysical parameters (IA·T, μ) are compared for normal and diabetic rats using an ex vivo extracorporeal model. This microfluidic-based method can be used for evaluating variations in the platelet adhesion and blood viscosity of animal models with cardiovascular diseases under ex vivo conditions. PMID:27118101

  1. Thromboembolism in inflammatory bowel disease: role of platelets.

    PubMed Central

    Webberley, M J; Hart, M T; Melikian, V

    1993-01-01

    Patients with inflammatory bowel disease are susceptible to thromboembolism and recently small vessel thrombosis has been implicated as an aetiological factor in Crohn's disease. This study therefore investigated platelet function in 104 patients with inflammatory bowel disease of whom eight had previous thromboembolism. Thirty five patients had reproducible spontaneous platelet aggregation of more than 30% (0 in controls) (p < 0.0001). A further 20 patients showed hypersensitivity of platelets to low concentrations of aggregating agents (p < 0.001). Plasma thromboxane B2 and beta thromboglobulin levels were significantly higher than controls (p < 0.001 and p < 0.001), but platelet lifespan studies were normal. There was no correlation with disease activity. Patients with inflammatory bowel disease have abnormal platelet activity, which may contribute to the inflammatory process. PMID:8432482

  2. Major depression induces oxidative stress and platelet hyperaggregability.

    PubMed

    Ormonde do Carmo, Monique B O; Mendes-Ribeiro, Antônio Cláudio; Matsuura, Cristiane; Pinto, Vivian L; Mury, Wanda V; Pinto, Nathalia O; Moss, Monique B; Ferraz, Marcos Rochedo; Brunini, Tatiana M C

    2015-02-01

    We have previously demonstrated an impairment of intraplatelet L-arginine-nitric oxide-cGMP pathway in major depression (MD) associated to platelet dysfunction. Here, we evaluated arginase pathway and phosphodiesterase 5 (PDE5) expression in platelets, systemic and intraplatelet oxidative status in untreated MD patients, and their effects on platelet aggregation. Blood samples were collected from 22 treatment naive MD patients (31 ± 2 yr) and 27 healthy subjects (33 ± 2 yr). MD patients presented with an activation of platelet arginase II, which competes with L-arginine for the production of nitric oxide (NO). An increase in protein carbonylation, overexpression of NADPH oxidase and PDE5, an enzyme that inactivates cGMP, was observed in platelets from MD patients compared to controls. In this context, platelet hyperaggregability was found in MD patients. On the other hand, antioxidant enzymes catalase, glutathione peroxidase and superoxide dismutase activities in serum and in platelets did not differ between groups. The increased activation of intraplatelet arginase and platelet aggregability, in addition to an overexpression of PDE5 and oxidative stress may contribute to alterations in L-arginine-NO-cGMP pathway and in platelet function, and consequently to the increased thrombotic risk in MD. PMID:25560770

  3. Platelets and cancer: a casual or causal relationship: revisited

    PubMed Central

    Menter, David G.; Tucker, Stephanie C.; Kopetz, Scott; Sood, Anil K.; Crissman, John D.; Honn, Kenneth V.

    2014-01-01

    Human platelets arise as subcellular fragments of megakaryocytes in bone marrow. The physiologic demand, presence of disease such as cancer, or drug effects can regulate the production circulating platelets. Platelet biology is essential to hemostasis, vascular integrity, angiogenesis, inflammation, innate immunity, wound healing, and cancer biology. The most critical biological platelet response is serving as “First Responders” during the wounding process. The exposure of extracellular matrix proteins and intracellular components occurs after wounding. Numerous platelet receptors recognize matrix proteins that trigger platelet activation, adhesion, aggregation, and stabilization. Once activated, platelets change shape and degranulate to release growth factors and bioactive lipids into the blood stream. This cyclic process recruits and aggregates platelets along with thrombogenesis. This process facilitates wound closure or can recognize circulating pathologic bodies. Cancer cell entry into the blood stream triggers platelet-mediated recognition and is amplified by cell surface receptors, cellular products, extracellular factors, and immune cells. In some cases, these interactions suppress immune recognition and elimination of cancer cells or promote arrest at the endothelium, or entrapment in the microvasculature, and survival. This supports survival and spread of cancer cells and the establishment of secondary lesions to serve as important targets for prevention and therapy. PMID:24696047

  4. Adenovirus type 3 induces platelet activation in vitro.

    PubMed

    Jin, Ying-Yu; Yu, Xiu-Nan; Qu, Zhang-Yi; Zhang, Ai-Ai; Xing, Yu-Ling; Jiang, Li-Xin; Shang, Lei; Wang, Ying-Chen

    2014-01-01

    In the present study, we aimed to investigate platelet activation induced by adenovirus type 3 (HAdV3) in vitro. Platelet-rich plasma (PRP) or whole blood was incubated with or without HAdV at various concentrations. Platelet aggregation, platelet counting, fibrinogen and expression of platelet membrane antigens (CD41a and CD62P) were determined following incubation with HAdV for different periods of time. The results demonstrated that HAdV at the concentrations of 109-1011 vp/ml enhanced adenosine diphosphate (ADP) or ristocetin-induced platelet aggregation, however did not alter the platelet count. Infection with HAdVs also reduced fibrinogen level. P-selectin and CD41a appeared rapidly on the surface after platelets were incubated with HAdVs in vitro for 30 min. In conclusion, HAdVs may induce activation of platelets and lead to a pre-thrombotic state of peripheral blood. This finding may aid in the development of measures to prevent severe HAdV infection.

  5. Platelets from thrombocytopenic ponies acutely infected with equine infectious anemia virus are activated in vivo and hypofunctional.

    PubMed

    Russell, K E; Perkins, P C; Hoffman, M R; Miller, R T; Walker, K M; Fuller, F J; Sellon, D C

    1999-06-20

    Thrombocytopenia is a consistent finding and one of the earliest hematological abnormalities in horses acutely infected with equine infectious anemia virus (EIAV), a lentivirus closely related to human immunodeficiency virus. Multifactorial mechanisms, including immune-mediated platelet destruction and impaired platelet production, are implicated in the pathogenesis of EIAV-associated thrombocytopenia. This study was undertaken to investigate whether regenerative thrombopoiesis and platelet destruction occurred in ponies acutely infected with EIAV. Circulating large, immature platelets were increased in ponies acutely infected with EIAV late in the infection when platelet count was at a nadir. Morphometric analysis of bone marrow from acutely infected ponies revealed significant increased in megakaryocyte area and megakaryocyte nuclear area. A trend toward increased numbers of megakaryocytes was also observed. Platelets from acutely infected ponies had increased surface-bound fibrinogen and ultrastructural changes consistent with in vivo platelet activation. Platelets also had hypofunctional aggregation responses to three agonists in vitro. We conclude that thrombocytopenia in ponies acutely infected with EIAV is regenerative and suggest that bone marrow platelet production is not severely compromised in these ponies. Our findings reveal that in vivo platelet activation occurs in ponies acutely infected with EIAV, and as a result platelets are hypofunctional in vitro. Activation of platelets in vivo may cause platelet degranulation or formation of platelet aggregates, which would result in removal of these damages platelets from circulation. This may represent a form of nonimmune-mediated platelet destruction in ponies acutely infected with EIAV.

  6. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets.

    PubMed

    Etulain, Julia; Negrotto, Soledad; Carestia, Agostina; Pozner, Roberto Gabriel; Romaniuk, María Albertina; D'Atri, Lina Paola; Klement, Giannoula Lakka; Schattner, Mirta

    2012-01-01

    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.

  7. In-vitro model for the ultrastructural study of the formation of thrombi in human platelets.

    PubMed

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

    2006-03-01

    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.

  8. The interaction of sodium nitroprusside with human endothelial cells and platelets: nitroprusside and prostacyclin synergistically inhibit platelet function

    SciTech Connect

    Levin, R.I.; Weksler, B.B.; Jaffe, E.A.

    1982-12-01

    Sodium nitroprusside (NP) is a potent vasodilator that also inhibits platelet aggregation. To test the hypothesis that NP causes both of these effects by altering the balance between prostacyclin (PGI2) produced by endothelial cells and thromboxane A2 (TXA2) produced by platelets, we incubated each of these cell types with NP for 5 minutes and assayed the PGI2 and TXA2 produced. NP at pharmacologically achieved doses (0.01--30 micrograms/ml) inhibited platelet aggregation and resultant TXA2 synthesis in a dose- and time-dependent manner (p less than 0.001). The inhibition was not dependent on cAMP production, external calcium concentration, or suppression of TXA2 synthesis. NP did not alter the production of PGI2 by cultured human endothelial cells as measured by radioimmunoassay for 6-Keto-PGF1 alpha, the stable hydrolysis product of PGI2. However, supernates of NP-treated endothelial cells containing low, noninhibitory concentrations of NP unexpectedly inhibited platelet aggregation. This inhibition of platelet aggregation was due to synergy between PGI2 (0.1--3 nM) and NP (p interaction less than 0.03). The synergistic inhibition by NP and PGI2 of platelet aggregation and TXA2 synthesis in vivo may explain some of the beneficial actions of NP in the treatment of hypertension and congestive heart failure.

  9. Serotonin uptake rates in platelets from angiotensin II-induced hypertensive mice.

    PubMed

    Singh, Preeti; Fletcher, Terry W; Li, Yicong; Rusch, Nancy J; Kilic, Fusun

    2013-03-01

    Angiotensin II (Ang II) is a critical component of the renin-angiotensin system that contributes to hypertension. Although platelets in blood from hypertensive subjects have an abnormal biological profile, it is unclear if circulating Ang II influences platelet aggregation or thrombus formation. One of the abnormalities presented to the platelets during hypertension is an elevated plasma concentration of serotonin (5-HT) caused by reduced 5-HT uptake secondary to loss of the 5-HT transporter (SERT) on the platelet plasma membrane. In the current study, we evaluated in vivo platelet function after 7 days of subcutaneous Ang II infusion to establish hypertension in mice and additionally assessed the biology of isolated platelets exposed to Ang II in vitro. The administration of Ang II elevated systolic blood pressure, but markers of platelet activation including P-selectin and (PE)Jon/A staining were not changed. However, the aggregation response to collagen was reduced in isolated platelets from Ang II-infused mice, which also showed reduced 5-HT uptake by SERT. In vitro exposure of isolated platelets to Ang II also resulted in a loss of surface SERT associated with a reduced aggregation response to collagen. These abnormalities were reversed by increasing concentrations of the Ang II receptor antagonist, valsartan. Interestingly, SERT KO mice failed to fully develop hypertension in response to Ang II infusion and isolated platelets from these animals were insensitive to the anti-aggregatory influence of Ang II. Thus, Ang II blunts the aggregation responses of platelets and the mechanism underlying this action may involve a loss of SERT on the platelet plasma membrane. The latter event depletes intracellular 5-HT in platelets, an event that is associated with reduced aggregation. The widespread use of antihypertensive drugs that target the renin-angiotensin system suggest the potential clinical utility of our findings and emphasize the importance of understanding

  10. Serotonin uptake rates in platelets from angiotensin II-induced hypertensive mice

    PubMed Central

    Singh, Preeti; Fletcher, Terry W.; Li, Yicong; Rusch, Nancy J.; Kilic, Fusun

    2013-01-01

    Angiotensin II (Ang II) is a critical component of the renin-angiotensin system that contributes to hypertension. Although platelets in blood from hypertensive subjects have an abnormal biological profile, it is unclear if circulating Ang II influences platelet aggregation or thrombus formation. One of the abnormalities presented to the platelets during hypertension is an elevated plasma concentration of serotonin (5-HT) caused by reduced 5-HT uptake secondary to loss of the 5-HT transporter (SERT) on the platelet plasma membrane. In the current study, we evaluated in vivo platelet function after 7 days of subcutaneous Ang II infusion to establish hypertension in mice and additionally assessed the biology of isolated platelets exposed to Ang II in vitro. The administration of Ang II elevated systolic blood pressure, but markers of platelet activation including P-selectin and PEJon/A staining were not changed. However, the aggregation response to collagen was reduced in isolated platelets from Ang II-infused mice, which also showed reduced 5-HT uptake by SERT. In vitro exposure of isolated platelets to Ang II also resulted in a loss of surface SERT associated with a reduced aggregation response to collagen. These abnormalities were reversed by increasing concentrations of the Ang II receptor antagonist, valsartan. Interestingly, SERT KO mice failed to fully develop hypertension in response to Ang II infusion and isolated platelets from these animals were insensitive to the anti-aggregatory influence of Ang II. Thus, Ang II blunts the aggregation responses of platelets and the mechanism underlying this action may involve a loss of SERT on the platelet plasma membrane. The latter event depletes intracellular 5-HT in platelets, an event that is associated with reduced aggregation. The widespread use of antihypertensive drugs that target the renin-angiotensin system suggest the potential clinical utility of our findings and emphasize the importance of understanding the

  11. Anucleate platelets generate progeny

    PubMed Central

    Schwertz, Hansjörg; Köster, Sarah; Kahr, Walter H. A.; Michetti, Noemi; Kraemer, Bjoern F.; Weitz, David A.; Blaylock, Robert C.; Kraiss, Larry W.; Greinacher, Andreas; Zimmerman, Guy A.

    2010-01-01

    Platelets are classified as terminally differentiated cells that are incapable of cellular division. However, we observe that anucleate human platelets, either maintained in suspension culture or captured in microdrops, give rise to new cell bodies packed with respiring mitochondria and α-granules. Platelet progeny formation also occurs in whole blood cultures. Newly formed platelets are structurally indistinguishable from normal platelets, are able to adhere and spread on extracellular matrix, and display normal signal-dependent expression of surface P-selectin and annexin V. Platelet progeny formation is accompanied by increases in biomass, cellular protein levels, and protein synthesis in expanding populations. Platelet numbers also increase during ex vivo storage. These observations indicate that platelets have a previously unrecognized capacity for producing functional progeny, which involves a form of cell division that does not require a nucleus. Because this new function of platelets occurs outside of the bone marrow milieu, it raises the possibility that thrombopoiesis continues in the bloodstream. PMID:20086251

  12. What Is Vinculin Needed for in Platelets?

    PubMed Central

    Mitsios, John V.; Prévost, Nicolas; Kasirer-Friede, Ana; Gutierrez, Edgar; Groisman, Alex; Abrams, Charles S.; Wang, Yanfeng; Litvinov, Rustem I.; Zemljic-Harpf, Alice; Ross, Robert S.; Shattil, Sanford J.

    2010-01-01

    Summary Background Vinculin links integrins to the cell cytoskeleton by virtue of its binding to proteins such as talin and F-actin. It has been implicated in the transmission of mechanical forces from the extracellular matrix to the cytoskeleton of migrating cells. Vinculin’s function in platelets is unknown. Objective To determine whether vinculin is required for the functions of platelets and their major integrin, αIIbβ3. Methods The murine vinculin gene (Vcl) was deleted in the megakaryocyte/platelet lineage by breeding Vcl fl/fl mice with Pf4-Cre mice. Platelet and integrin functions were studied in vivo and ex vivo. Results Vinculin was undetectable in platelets from Vcl fl/fl Cre+ mice, as determined by immunoblotting and fluorescence microscopy. Vinculin-deficient megakaryocytes exhibited increased membrane tethers in response to mechanical pulling on αIIbβ3 with laser tweezers, suggesting that vinculin helps to maintain membrane cytoskeleton integrity. Surprisingly, vinculin-deficient platelets displayed normal agonist-induced fibrinogen binding to αIIbβ3, aggregation, spreading, actin polymerization/organization, clot retraction and the ability to form a procoagulant surface. Furthermore, vinculin-deficient platelets adhered to immobilized fibrinogen or collagen normally, both under static and flow conditions. Tail bleeding times were prolonged in 59% of vinculin-deficient mice. However, these mice exhibited no spontaneous bleeding and they formed occlusive platelet thrombi comparable to wild-type littermates in response to carotid artery injury with FeCl3. Conclusion Despite promoting membrane cytoskeleton integrity when mechanical force is applied to αIIbβ3, vinculin is not required for the traditional functions of αIIbβ3 or the platelet actin cytoskeleton. PMID:20670372

  13. Nonmuscle Myosin IIA Regulates Platelet Contractile Forces Through Rho Kinase and Myosin Light-Chain Kinase.

    PubMed

    Feghhi, Shirin; Tooley, Wes W; Sniadecki, Nathan J

    2016-10-01

    Platelet contractile forces play a major role in clot retraction and help to hold hemostatic clots against the vessel wall. Platelet forces are produced by its cytoskeleton, which is composed of actin and nonmuscle myosin filaments. In this work, we studied the role of Rho kinase, myosin light-chain kinase, and myosin in the generation of contractile forces by using pharmacological inhibitors and arrays of flexible microposts to measure platelet forces. When platelets were seeded onto microposts, they formed aggregates on the tips of the microposts. Forces produced by the platelets in the aggregates were measured by quantifying the deflection of the microposts, which bent in proportion to the force of the platelets. Platelets were treated with small molecule inhibitors of myosin activity: Y-27632 to inhibit the Rho kinase (ROCK), ML-7 to inhibit myosin light-chain kinase (MLCK), and blebbistatin to inhibit myosin ATPase activity. ROCK inhibition reduced platelet forces, demonstrating the importance of the assembly of actin and myosin phosphorylation in generating contractile forces. Similarly, MLCK inhibition caused weaker platelet forces, which verifies that myosin phosphorylation is needed for force generation in platelets. Platelets treated with blebbistatin also had weaker forces, which indicates that myosin's ATPase activity is necessary for platelet forces. Our studies demonstrate that myosin ATPase activity and the regulation of actin-myosin assembly by ROCK and MLCK are needed for the generation of platelet forces. Our findings illustrate and explain the importance of myosin for clot compaction in hemostasis and thrombosis. PMID:27548633

  14. Platelet-mimetic strategies for modulating the wound environment and inflammatory responses

    PubMed Central

    Nandi, Seema

    2016-01-01

    Platelets closely interface with the immune system to fight pathogens, target wound sites, and regulate tissue repair. Natural platelet levels within the body can be depleted for a variety of reasons, including excessive bleeding following traumatic injury, or diseases such as cancer and bacterial or viral infections. Platelet transfusions are commonly used to improve platelet count and hemostatic function in these cases, but transfusions can be complicated by the contamination risks and short storage life of donated platelets. Lyophilized platelets that can be freeze-dried and stored for longer periods of time and synthetic platelet-mimetic technologies that can enhance or replace the functions of natural platelets, while minimizing adverse immune responses have been explored as alternatives to transfusion. Synthetic platelets typically comprise nanoparticles surface-decorated with peptides or ligands to recreate specific biological characteristics of platelets, including targeting of wound and disease sites and facilitating platelet aggregation. Recent efforts in synthetic platelet design have additionally focused on matching platelet shape and mechanics to recreate the marginalization and clot contraction capabilities of natural platelets. The ability to specifically tune the properties of synthetic platelet-mimetic materials has shown utility in a variety of applications including hemostasis, drug delivery, and targeted delivery of cancer therapeutics. PMID:27190260

  15. Relationship between size and thiazole orange fluorescence of platelets in patients undergoing high-dose chemotherapy.

    PubMed

    Balduini, C L; Noris, P; Spedini, P; Belletti, S; Zambelli, A; Da Prada, G A

    1999-07-01

    The reticulated platelet count relies upon the assumption that newly formed platelets contain a residual amount of RNA which selectively binds the dye thiazole orange (TO) and greatly enhances its fluorescence signal. It has, however, recently been shown that almost half of the platelet TO-signal is derived from the labelling of dense-granule nucleotides. It is therefore possible that the higher TO fluorescence of young platelets partially derives from the higher granule content due to their larger volume. To investigate the relationship between platelet size and TO fluorescence we studied 13 patients with high-risk breast cancer undergoing high-dose chemotherapy. Mean platelet volume, platelet distribution width, platelet-large cell ratio, membrane content of glycoprotein Ib and IIb-IIIa and platelet aggregation were significantly greater during resolution than during development of thrombocytopenia, suggesting a prevalence of young and old platelets respectively. Mean TO fluorescence per cell was higher in the platelet population enriched in young cells than in that enriched in old cells, but this difference was no longer observed when the ratio TO signal/platelet size was examined. Moreover, RNase treatment and platelet degranulation reduced TO fluorescence to a similar extent in platelet populations enriched in young or old cells. Therefore our data suggest that the higher TO signal of young platelets is derived, to a significant extent, from their larger volume and granule content.

  16. Role of Siglec-7 in Apoptosis in Human Platelets

    PubMed Central

    Nguyen, Kim Anh; Hamzeh-Cognasse, Hind; Palle, Sabine; Anselme-Bertrand, Isabelle; Arthaud, Charles-Antoine; Chavarin, Patricia; Pozzetto, Bruno; Garraud, Olivier; Cognasse, Fabrice

    2014-01-01

    Background Platelets participate in tissue repair and innate immune responses. Sialic acid-binding immunoglobulin-like lectins (Siglecs) are well-characterized I-type lectins, which control apoptosis. Methodology/Principal Findings We characterized the expression of Siglec-7 in human platelets isolated from healthy volunteers using flow cytometry and confocal microscopy. Siglec-7 is primarily expressed on α granular membranes and colocalized with CD62P. Siglec-7 expression was increased upon platelet activation and correlated closely with CD62P expression. Cross-linking Siglec-7 with its ligand, ganglioside, resulted in platelet apoptosis without any significant effects on activation, aggregation, cell morphology by electron microscopy analysis or secretion. We show that ganglioside triggered four key pathways leading to apoptosis in human platelets: (i) mitochondrial inner transmembrane potential (ΔΨm) depolarization; (ii) elevated expression of pro-apoptotic Bax and Bak proteins with reduced expression of anti-apoptotic Bcl-2 protein; (iii) phosphatidylserine exposure and (iv), microparticle formation. Inhibition of NAPDH oxidase, PI3K, or PKC rescued platelets from apoptosis induced by Siglec-7 recruitment, suggesting that the platelet receptors P2Y1 and GPIIbIIIa are essential for ganglioside-induced platelet apoptosis. Conclusions/Significance The present work characterizes the role of Siglec-7 and platelet receptors in regulating apoptosis and death. Because some platelet pathology involves apoptosis (idiopathic thrombocytopenic purpura and possibly storage lesions), Siglec-7 might be a molecular target for therapeutic intervention/prevention. PMID:25230315

  17. Selective inhibition of the platelet phosphoinositide 3-kinase p110beta as promising new strategy for platelet protection during extracorporeal circulation.

    PubMed

    Straub, Andreas; Wendel, Hans Peter; Dietz, Klaus; Schiebold, Daniela; Peter, Karlheinz; Schoenwaelder, Simone M; Ziemer, Gerhard

    2008-03-01

    Extracorporeal circulation (ECC) is used in cardiac surgery for cardiopulmonary bypass as well as in ventricular assist devices and for extracorporeal membrane oxygenation. Blood contact with the artificial surface and shear stress of ECC activates platelets and leukocytes resulting in a coagulopathy and proinflammatory events. Blockers of the platelet glycoprotein (GP) IIb/IIIa (CD41/CD61) can protect platelet function during ECC, a phenomenon called "platelet anaesthesia", but may be involved in post-ECC bleeding. We hypothesized that the new selective phosphoinositide 3-kinase p110beta inhibitor TGX-221 that inhibits shear-induced platelet activation without prolonging the bleeding time in vivo may also protect platelet function during ECC. Heparinized blood of healthy volunteers (n = 6) was treated in vitro with either the GP IIb/IIIa blocker tirofiban, TGX-221 or as control and circulated in an ECC model. Before and after 30 minutes circulation CD41 expression on the ECC-tubing as measure for platelet-ECC binding and generation of the platelet activation marker beta-thromboglobulin were determined using ELISA. Platelet aggregation and platelet-granulocyte binding were analysed in flow cytometry. After log-transforming the data statistical evaluation was performed using multifactor ANOVA in combination with Tukey's HSD test (global alpha = 5%). Tirofiban and TGX-221 inhibited platelet-ECC interaction, platelet aggregation and platelet-granulocyte binding. Tirofiban also inhibited ECC-induced beta-thromboglobulin release. The observed inhibition of platelet-ECC interaction and platelet activation by tirofiban contributes to explain the mechanism of "platelet anaesthesia". TGX-221 represents a promising alternative to GP IIb/IIIa blockade and should be further investigated for use during ECC in vivo.

  18. Expression of surface platelet receptors (CD62P and CD41/61) in horses with recurrent airway obstruction (RAO).

    PubMed

    Iwaszko-Simonik, Alicja; Niedzwiedz, Artur; Graczyk, Stanislaw; Slowikowska, Malwina; Pliszczak-Krol, Aleksandra

    2015-03-15

    Recurrent airway obstruction (RAO) is an allergic disease of horses similar to human asthma, which is characterized by airway inflammation and activation of neutrophils, lymphocytes and platelets. Platelet activation and an increase in circulating platelet-leukocyte aggregates may lead to airway remodeling. The aim of this study was to investigate platelet status in RAO-affected horses based on the platelet morphology and platelet surface expression of CD41/61 and CD62P. Ten RAO-affected horses and ten healthy horses were included in this study. Blood samples were obtained to determine the platelet count (PLT), mean platelet volume (MPV) and platelet large cell ratio (P-LCR). Expression of CD62P and CD41/61 was detected by flow cytometry on activated platelets. The median PLT was significantly reduced in horses with RAO compared to the controls. The MPV and the P-LCR values were significantly higher in RAO horses than controls. Expression of CD41/61 on platelets was increased in RAO horses, while CD62P expression was reduced. This study demonstrated the morphological changes in platelets and expression of platelet surface receptors. Despite the decrease of CD62P expression, the observed increased surface expression of CD41/61 on platelets in horses with RAO may contribute to the formation of platelet aggregates in their respiratory system.

  19. Thrombin-Mediated Platelet Activation of Lysed Whole Blood and Platelet-Rich Plasma: A Comparison Between Platelet Activation Markers and Ultrastructural Alterations.

    PubMed

    Augustine, Tanya N; van der Spuy, Wendy J; Kaberry, Lindsay L; Shayi, Millicent

    2016-06-01

    Platelet ultrastructural alterations representing spurious activation have been identified in pathological conditions. A limitation of platelet studies is that sample preparation may lead to artifactual activation processes which may confound results, impacting the use of scanning electron microscopy as a supplemental diagnostic tool. We used scanning electron microscopy and flow cytometry to analyze platelet activation in platelet-rich plasma (PRP) and whole blood (WB) samples. PRP generated using a single high g force centrifugation, and WB samples treated with a red blood cell lysis buffer, were exposed to increasing concentrations of the agonist thrombin. Platelets in lysed WB samples responded to thrombin by elevating the activation marker CD62p definitively, with corresponding ultrastructural changes indicating activation. Conversely, CD62p expression in PRP preparations remained static. Ultrastructural analysis revealed fully activated platelets even under low concentration thrombin stimulation, with considerable fibrin deposition. It is proposed that the method for PRP production induced premature platelet activation, preventable by using an inhibitor of platelet aggregation and fibrin polymerization. Nevertheless, our results show a definitive correspondence between flow cytometry and scanning electron microscopy in platelet activation studies, highlighting the potential of the latter technique as a supplemental diagnostic tool. PMID:27329313

  20. Antiaggregant effects of Arbutus unedo extracts in human platelets.

    PubMed

    El Haouari, Mohammed; López, José J; Mekhfi, Hassane; Rosado, Juan A; Salido, Ginés M

    2007-09-01

    Platelet hyperaggregability plays a pivotal role in the pathogenesis of cardiovascular diseases. Thrombin evokes aggregation through Ca(2+) mobilization, tyrosine phosphorylation and generation of reactive oxygen species (ROS). We have investigated the antiaggregant properties of Arbutus unedo extracts in human platelets. Changes in cytosolic Ca(2+) concentration and intracellular oxidants production were registered by espectrofluorimetry using fura-2 and dichlorodihydrofluorescein, respectively, platelet aggregation was assessed by aggregometry and protein tyrosine phosphorylation was detected by Western blotting. Platelet treatment with increasing concentrations (0.015-1.5mg/mL) of crude aqueous, ethyl acetate or diethyl ether extracts reduced platelet aggregation evoked by thrombin (0.5 U/mL) and show a potent ROS scavenger activity, preventing thrombin-evoked endogenous generation of ROS. Treatment with Arbutus unedo extracts did not alter thrombin-evoked Ca(2+) release from the intracellular stores but reduced store-operated Ca(2+) entry induced by thrombin or by selective depletion of the two Ca(2+) stores in platelets, the dense tubular system and the acidic stores. In addition, platelet treatment with extracts reduced both basal and thrombin-stimulated protein tyrosine phosphorylation. We conclude that Arbutus unedo extracts show antiaggregant actions due to attenuation of Ca(2+) mobilization, ROS production and protein tyrosine phosphorylation and might be used for the treatment and/or prevention of cardiovascular diseases. PMID:17681442

  1. Effects of irradiation on platelet function

    SciTech Connect

    Rock, G.; Adams, G.A.; Labow, R.S.

    1988-09-01

    Current medical practice involves the irradiation of blood components, including platelet concentrates, before their administration to patients with severe immunosuppression. The authors studied the effect of irradiation on in vitro platelet function and the leaching of plasticizers from the bag, both immediately and after 5 days of storage. The platelet count, white cell count, pH, glucose, lactate, platelet aggregation and release reaction, and serotonin uptake were not altered by the irradiation of random-donor or apheresis units with 2000 rads carried out at 0 and 24 hours and 5 days after collection. The leaching of di(2-ethylhexyl)phthalate from the plastic bags followed by the conversion to mono(2-ethylhexyl)phthalate was not increased by irradiation. Therefore, it is possible to irradiate platelet concentrates on the day of collection and subsequently store them for at least 5 days while maintaining in vitro function. This procedure could have considerable benefit for blood banks involved in the provision of many platelet products.

  2. The effect of ageing on human platelet sensitivity to serotonin.

    PubMed

    Gleerup, G; Winther, K

    1988-10-01

    Twelve healthy young volunteers (mean age 21, range 18-27 years) and 12 elderly people (mean age 77, range 72-86 years) were tested regarding platelet aggregation induced by adrenaline, ADP and serotonin. The serum levels of thromboxane B2 (TXB2) and serum 6-keto-PGF1 alpha and the plasma level of adrenaline and cyclic AMP (cAMP) were also measured. Platelet aggregation induced by adrenaline and ADP increased significantly in the elderly compared with the young group (P less than 0.05 and P less than 0.02, respectively). There was a substantial and highly significant increase in the response of platelets from elderly people to serotonin (P less than 0.01). No alteration was observed in the serum level of TXB2 or 6-keto-PGF1 alpha. Plasma adrenaline increased in the old group, but plasma cAMP was unaffected. As serotonin is known to amplify adrenaline- and ADR-induced platelet aggregation, the considerable increase in platelet sensitivity to serotonin could be an important factor in the increased adrenaline and ADP-induced platelet aggregability of elderly people.

  3. Characterization of the platelet transcriptome by RNA sequencing in patients with acute myocardial infarction.

    PubMed

    Eicher, John D; Wakabayashi, Yoshiyuki; Vitseva, Olga; Esa, Nada; Yang, Yanqin; Zhu, Jun; Freedman, Jane E; McManus, David D; Johnson, Andrew D

    2016-01-01

    Transcripts in platelets are largely produced in precursor megakaryocytes but remain physiologically active as platelets translate RNAs and regulate protein/RNA levels. Recent studies using transcriptome sequencing (RNA-seq) characterized the platelet transcriptome in limited number of non-diseased individuals. Here, we expand upon these RNA-seq studies by completing RNA-seq in platelets from 32 patients with acute myocardial infarction (MI). Our goals were to characterize the platelet transcriptome using a population of patients with acute MI and relate gene expression to platelet aggregation measures and ST-segment elevation MI (STEMI) (n = 16) vs. non-STEMI (NSTEMI) (n = 16) subtypes. Similar to other studies, we detected 9565 expressed transcripts, including several known platelet-enriched markers (e.g. PPBP, OST4). Our RNA-seq data strongly correlated with independently ascertained platelet expression data and showed enrichment for platelet-related pathways (e.g. wound response, hemostasis, and platelet activation), as well as actin-related and post-transcriptional processes. Several transcripts displayed suggestively higher (FBXL4, ECHDC3, KCNE1, TAOK2, AURKB, ERG, and FKBP5) and lower (MIAT, PVRL3, and PZP) expression in STEMI platelets compared to NSTEMI. We also identified transcripts correlated with platelet aggregation to TRAP (ATP6V1G2, SLC2A3), collagen (CEACAM1, ITGA2), and ADP (PDGFB, PDGFC, ST3GAL6). Our study adds to current platelet gene expression resources by providing transcriptome-wide analyses in platelets isolated from patients with acute MI. In concert with prior studies, we identify various genes for further study in regards to platelet function and acute MI. Future platelet RNA-seq studies examining more diverse sets of healthy and diseased samples will add to our understanding of platelet thrombotic and non-thrombotic functions.

  4. Prostacyclin receptor expression on platelets of humans with type 2 diabetes is inversely correlated with hemoglobin A1c levels.

    PubMed

    Knebel, Stephanie M; Sprague, Randy S; Stephenson, Alan H

    2015-01-01

    Inappropriate platelet aggregation can result in thrombosis and tissue ischemia. When compared to healthy human platelets, those of humans with type 2 diabetes (DM2) exhibit increased aggregation when stimulated. Activation of the platelet prostacyclin receptor (IPR) results in cAMP accumulation and inhibition of platelet aggregation. We hypothesized that DM2 platelets express decreased IPR when compared to platelets of healthy humans, resulting in decreased IPR agonist-induced cAMP accumulation. We measured IPR expression with radioligand binding of [(3)H]-iloprost, a stable prostacyclin analog, and with Western blotting of the IPR protein. Iloprost-stimulated platelet cAMP levels were used to identify the functional response to IPR activation. IPR binding, expression of the IPR protein and the levels of cAMP in platelets incubated with iloprost were significantly decreased in DM2 platelets when compared to platelets of healthy humans. IPR expression decreased in platelets as glycemic control of the subjects worsened, as indicated by increased hemoglobin A1c levels. Taken together, these findings suggest that reduced IPR expression in DM2 platelets may contribute to platelet hyperactivity in humans with type 2 diabetes. PMID:25617843

  5. Cardiac and vascular imaging with labeled platelets and leukocytes

    SciTech Connect

    Dewanjee, M.K.

    1984-07-01

    The contribution of platelets in atherosclerosis and thrombosis in animal models and in clinical studies has been quantified with 111In-platelet scintigraphy. New in vitro quantitative techniques have been developed using 111In-labeled platelets to determine the number of adherent platelets on deendothelialized surfaces of damaged vessel walls and synthetic vascular grafts. In vivo imaging techniques are semi-quantitative in nature; in these studies 111In radioactivity on thrombotic vessels or graft surfaces of iliac, femoral, or popliteal arteries is compared with contralateral vessels. Background 111In radioactivity in the circulating blood pool of venous and capillary networks and radioactivity in marrow decreases the sensitivity of these techniques. Subtraction of blood pool radioactivity with 99mTc-labeled autologous red cells and calculation of 111In radioactivity associated with platelet thrombus on vessel walls also have been performed for coronary, carotid, and femoral arteries. Although platelet concentrates are used frequently after open heart surgery (one to six per patient), consumption of platelets in the artificial lung or oxygenator, lysis of platelets during pumping, and suction of blood only recently have been quantified with the use of 111In-labeled platelets. These studies also demonstrated far less trauma to platelets with the use of a membrane rather than a bubble oxygenator. Further reduction in platelet consumption and trauma was observed with the use of prostacyclin, a short-acting drug with significant beneficial effect on platelet thrombus reduction and disaggregation of aggregated platelets. The role of polymorphonuclear leukocytes in inflammation, infection and myocardial infarction, and in vivo evaluation with 111In-leukocyte scintigraphy in animals and humans has been described.

  6. Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  7. [Ultrastructural and functional assessment on platelets loaded with small molecule carbohydrates].

    PubMed

    Yang, Chao; Wang, Jie-Xi; Han, Ying; Wang, Yan; Quan, Guo-Bo; Liu, Min-Xia; Gao, Feng; Liu, An

    2008-06-01

    The aim of this study was to investigate the effect of loading some small molecule carbohydrates into human platelets on ultrastucture and function. The ultrastructure of platelets were observed by transmission electron microscope (TEM); the platelet counts and mean platelet volume (MPV) were measured by hemocytometer, the maximal platelet aggregation rate was measured optically in an aggregometer; the surface marker of platelet membranes CD62p and phosphatidyl serine were analyzed by flow cytometry. The results showed that no significant changes of the ultrastructure of platelets loaded with small molecule carbohydrates were seen. The aggregation responsiveness of platelets loaded with small molecule carbohydrates reached to 60% of the fresh control platelets. The values of platelet counts and MPV showed no significant differences. The expression level of CD62p and the binding rate with Annexin V before and after loading small molecule carbohydrates into platelets were no different. It is concluded that the platelets after loading with small molecule carbohydrates remained fine ultrastructure and function.

  8. Platelets and Infections – Complex Interactions with Bacteria

    PubMed Central

    Hamzeh-Cognasse, Hind; Damien, Pauline; Chabert, Adrien; Pozzetto, Bruno; Cognasse, Fabrice; Garraud, Olivier

    2015-01-01

    Platelets can be considered sentinels of vascular system due to their high number in the circulation and to the range of functional immunoreceptors they express. Platelets express a wide range of potential bacterial receptors, including complement receptors, FcγRII, Toll-like receptors but also integrins conventionally described in the hemostatic response, such as GPIIb–IIIa or GPIb. Bacteria bind these receptors either directly, or indirectly via fibrinogen, fibronectin, the first complement C1q, the von Willebrand Factor, etc. The fate of platelet-bound bacteria is questioned. Several studies reported the ability of activated platelets to internalize bacteria such as Staphylococcus aureus or Porphyromonas gingivalis, though there is no clue on what happens thereafter. Are they sheltered from the immune system in the cytoplasm of platelets or are they lysed? Indeed, while the presence of phagolysosome has not been demonstrated in platelets, they contain antimicrobial peptides that were shown to be efficient on S. aureus. Besides, the fact that bacteria can bind to platelets via receptors involved in hemostasis suggests that they may induce aggregation; this has indeed been described for Streptococcus sanguinis, S. epidermidis, or C. pneumoniae. On the other hand, platelets are able to display an inflammatory response to an infectious triggering. We, and others, have shown that platelet release soluble immunomodulatory factors upon stimulation by bacterial components. Moreover, interactions between bacteria and platelets are not limited to only these two partners. Indeed, platelets are also essential for the formation of neutrophil extracellular traps by neutrophils, resulting in bacterial clearance by trapping bacteria and concentrating antibacterial factors but in enhancing thrombosis. In conclusion, the platelet–bacteria interplay is a complex game; its fine analysis is complicated by the fact that the inflammatory component adds to the aggregation response

  9. Rhesus monkey platelets

    SciTech Connect

    Harbury, C.B.

    1986-03-01

    The purpose of this abstract is to describe the adenine nucleotide metabolism of Rhesus monkey platelets. Nucleotides are labelled with /sup 14/C-adenine and extracted with EDTA-ethanol (EE) and perchlorate (P). Total platelet ATP and ADP (TATP, TADP) is measured in the Holmsen Luciferase assay, and expressed in nanomoles/10/sup 8/ platelets. TR=TATP/TADP. Human platelets release 70% of their TADP, with a ratio of released ATP/ADP of 0.7. Rhesus platelets release 82% of their TADP, with a ratio of released ATP/ADP of 0.33. Thus, monkey platelets contain more ADP than human platelets. Thin layer chromatography of EE gives a metabolic ratio of 11 in human platelets and 10.5 in monkey platelets. Perchlorate extracts metabolic and actin bound ADP. The human and monkey platelets ratios were 5, indicating they contain the same proportion of actin. Thus, the extra ADP contained in monkey platelets is located in the secretory granules.

  10. Effect of hydrogen peroxide and catalase derivatives on functional activity of platelets.

    PubMed

    Vavaev, A V; Buryachkovskaya, L I; Uchitel, I A; Tishchenko, E G; Maksimenko, A V

    2012-01-01

    Effects of H(2)O(2) on platelet aggregation were estimated in vitro in the presence and absence of inductors (ADP, serotonin, TRAP) and native and modified catalase. Dose-dependent effect of H(2)O(2) (50 μM or more) was investigated in a pathophysiological concentration of 300 μM inducing platelet aggregation. H(2)O(2) modulated aggregation induced by ADP, serotonin, and TRAP significantly increasing the initial platelet aggregation followed by disaggregation, which was always more pronounced than in control. Catalase derivatives (native and modified forms) dose-dependently reduced the effect of H(2)O(2) and completely abolished it in a dose of 9000 U catalase activity per 1 ml of solution for native catalase and 1200 U/ml for modified one. Modified catalase, in contrast to native one, produced an independent inhibitory effect on induced platelet aggregation. Components of modified catalase (individual substance and simple mixture) had no antiaggregant effect.

  11. Association of MicroRNAs and YRNAs with Platelet Function

    PubMed Central

    Bender, Lukas H.; Barwari, Temo; Willeit, Peter; Pechlaner, Raimund; Sunderland, Nicholas P.; Willeit, Karin; Morton, Allison C.; Armstrong, Paul C.; Chan, Melissa V.; Lu, Ruifang; Yin, Xiaoke; Gracio, Filipe; Dudek, Katarzyna; Langley, Sarah R.; Zampetaki, Anna; de Rinaldis, Emanuele; Ye, Shu; Warner, Timothy D.; Saxena, Alka; Kiechl, Stefan; Storey, Robert F.; Mayr, Manuel

    2016-01-01

    Rationale Platelets shed microRNAs (miRNAs). Plasma miRNAs change upon platelet inhibition. It is unclear if plasma miRNA levels correlate with platelet function. Objective To link small RNAs to platelet reactivity. Methods and Results Next-generation sequencing of small RNAs in plasma revealed two peaks at 22-23 and 32-33 nucleotides corresponding to miRNAs and YRNAs, respectively. Among YRNAs, predominantly fragments of RNY4 and RNY5 were detected. Plasma miRNAs and YRNAs were measured in 125 patients with a history of ACS who had undergone detailed assessment of platelet function 30 days after the acute event. Using quantitative real-time polymerase chain reactions, 92 miRNAs were assessed in ACS patients on different anti-platelet therapies. Key platelet-related miRNAs and YRNAs were correlated with platelet function tests. MiR-223 (rp=0.28, n=121, P=0.002), miR-126 (rp=0.22, n=121, P=0.016), other abundant platelet miRNAs and YRNAs showed significant positive correlations with the vasodilator-stimulated phosphoprotein phosphorylation assay. YRNAs, miR-126 and miR-223 were also among the small RNAs showing the greatest dependency on platelets, and strongly correlated with plasma levels of P-selectin, platelet factor 4 and platelet basic protein in the population-based Bruneck study (n=669). A single nucleotide polymorphism that facilitates processing of pri-miR-126 to mature miR-126 accounted for a rise in circulating platelet activation markers. Inhibition of miR-126 in mice reduced platelet aggregation. MiR-126 directly and indirectly affects ADAM9 and P2Y12 receptor expression. Conclusions Levels of platelet-related plasma miRNAs and YRNAs correlate with platelet function tests in ACS patients and platelet activation markers in the general population. Alterations in miR-126 affect platelet reactivity. PMID:26646931

  12. gamma. -hexachlorocyclohexane (. gamma. -HCH) activates washed rabbit platelets

    SciTech Connect

    Lalau-Keraly, C.; Delautier, D.; Benveniste, J.; Puiseux-Dao, S.

    1986-03-01

    In guinea-pig macrophages, ..gamma..-HCH triggers activation of the phosphatidylinositol cycle and Ca/sup 2 +/ mobilization. Since these two biochemical events are also involved in platelet activation, the authors examined the effects of ..gamma..-HCH on washed rabbit platelets. Release of /sup 14/C-serotonin (/sup 14/C-5HT) and ATP from platelets prelabelled with /sup 14/C-5HT was measured simultaneously with aggregation. ..gamma..-HCH induced shape-change, aggregation and release reaction of platelets. Maximal aggregation (89 arbitrary units, AU), was observed using 170 ..mu..M ..gamma..-HCH, and was associated with 38.1 +/- 6.9% and 161 +/- 48 nM for /sup 14/C-5HT and ATP release respectively (mean +/- 1 SD, n=3). Using 80 ..mu..M ..gamma..-HCH yielded 18 AU, 12.8 +/- 1.0% and 27 +/- 14 nM for aggregation, C-5HT and ATP release respectively (n=3). No effect was observed with 40 ..mu.. M ..gamma..-HCH. Aspirin (ASA), a cyclooxygenase blocker, did not affect ..gamma..-HCH-induced platelet activation. Apyrase (APY), an ADP scavenger, inhibited by 90% aggregation induced by 170 ..mu..M ..gamma..-HCH and slightly inhibited (15%) the /sup 14/C-5HT release. In the presence of both ASA and APY, 96% inhibition of aggregation and 48% inhibition of /sup 14/C-5HT release were observed. Thus, ..gamma..-HCH induced platelet activation in a dose-dependent manner ADP, but not cyclooxygenase-dependent arachidonate metabolites, is involved in ..gamma..-HCH-induced aggregation, whereas, both appear to play a role in ..gamma..-HCH-induced release reaction.

  13. Early posttraumatic pulmonary platelet trapping and its potentiation by oral pretreatment with alcohol

    SciTech Connect

    Thoerne, J.B.; Blomquist, S.; Elmer, O.; Joensson, B.A.L.; Lindahl, S.; Strand, S.E.

    1986-02-01

    Soft tissue trauma is associated with platelet aggregation and sequestration in the lungs. This is believed to be an early step in the later development of adult respiratory distress syndrome. In the present experiment using a new method for in vivo dynamic studies of platelet sequestration, we wanted to evaluate the effect of soft tissue trauma on pulmonary platelet trapping in pigs and the influence of acute alcohol intoxication. The results show that significant pulmonary platelet trapping is registered within minutes of trauma and that alcohol significantly increases platelet sequestration in the lungs. This indicates an increased risk for posttraumatic pulmonary problems in alcohol-intoxicated trauma victims.

  14. [Adhesion of blood platelets to electric-featuring polymers].

    PubMed

    Shumakov, V I; Chepurov, A K; Kozlov, W K; Kazakova, T I

    1975-01-01

    The authors studied the effect of electric potential arising on the plastic surface upon the blood clotting process. The study was performed according to the Breddin method. The study concerned fluorosilicone rubber, fluoroplast, polyester, polyethylene and polyvinyl chloride with various surface potentials. The authors found that the negatively charged blood platelets adhere to negatively charged plastic surfaces only to a low extent and undergo no disintegration and agglomeration. To the surfaces of the same plastics being electrically neutral, only small aggregates of blood platelets adhere. On the other hand, on the positively charged surfaces the accumulation of blood platelets takes place with concurrent aggregation and disintegration, thus initiating the thrombus formation. The authors observed the intensity of these changes using blood platelet adhesion index and fluorescence microscope.

  15. Decreased platelet membrane anisotropy in patients with adrenoleukodystrophy treated with erucic acid (22:1)-rich triglycerides.

    PubMed

    Stöckler, S; Opper, C; Greinacher, A; Hunneman, D H; Korenke, G C; Unkrig, C J; Hanefeld, F

    1997-03-01

    Low platelet count and bleeding diathesis have been observed in patients with adrenoleukodystrophy (ALD) treated with erucic acid (22:1)-rich triglycerides ("Lorenzo's oil'). To investigate possible alterations of biophysical membrane properties, we measured platelet membrane anisotropy, which is inversely related to membrane fluidity, in 16 patients with and in 3 patients without treatment. In patients on treatment, platelet membrane anisotropy was significantly decreased. Additionally, we found increased platelet concentrations of 22:1 and compromised in vitro platelet aggregation response. The decrease of platelet membrane anisotropy is probably a main cause of bleeding diathesis. Long-term haematological side-effects must be considered in ALD patients treated with Lorenzo's oil.

  16. A Spatial-Temporal Model of Platelet Deposition and Blood Coagulation Under Flow

    NASA Astrophysics Data System (ADS)

    Leiderman Gregg, Karin; Fogelson, Aaron

    2009-11-01

    In the event of a vascular injury, a blood clot will form to prevent bleeding. This response involves two intertwined processes: platelet aggregation and coagulation. Activated platelets are critical to coagulation in that they provide localized reactive surfaces on which many of the coagulation reactions occur. The final product from the coagulation cascade directly couples the coagulation system to platelet aggregation by acting as a strong activator of platelets and cleaving blood-borne fibrinogen into fibrin which then forms a mesh to help stabilize platelet aggregates. Together, the fibrin mesh and the platelet aggregates comprise a blood clot, which in some cases, can grow to occlusive diameters. Transport of coagulation proteins to and from the vicinity of the injury is controlled largely by the dynamics of the blood flow. It is crucial to learn how blood flow affects the growth of clots, and how the growing masses, in turn, feed back and affect the fluid motion. We have developed the first spatial-temporal model of platelet deposition and blood coagulation under flow that includes detailed decriptions of the coagulation biochemistry, chemical activation and deposition of blood platelets, as well as the two-way interaction between the fluid dynamics and the growing platelet mass.

  17. Platelet Hyperactivity in TNFSF14/LIGHT Knockout Mouse Model of Impaired Healing

    PubMed Central

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

    2016-01-01

    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. PMID:27785376

  18. Differential changes in platelet reactivity induced by acute physical compared to persistent mental stress.