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Sample records for adp-induced platelet aggregation

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

    Institute of Scientific and Technical Information of China (English)

    WEI Yuxi; WANG Changyun; LI Jing; GUO Qi; QI Hongtao

    2009-01-01

    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.

  2. Chlorin e6 Prevents ADP-Induced Platelet Aggregation by Decreasing PI3K-Akt Phosphorylation and Promoting cAMP Production

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    Ji Young Park

    2013-01-01

    Full Text Available A number of reagents that prevent thrombosis have been developed but were found to have serious side effects. Therefore, we sought to identify complementary and alternative medicinal materials that are safe and have long-term efficacy. In the present studies, we have assessed the ability of chlorine e6 (CE6 to inhibit ADP-induced aggregation of rat platelets and elucidated the underlying mechanism. CE6 inhibited platelet aggregation induced by 10 µM ADP in a concentration-dependent manner and decreased intracellular calcium mobilization and granule secretion (i.e., ATP and serotonin release. Western blotting revealed that CE6 strongly inhibited the phosphorylations of PI3K, Akt, c-Jun N-terminal kinase (JNK, and different mitogen-activated protein kinases (MAPKs including extracellular signal-regulated kinase 1/2 (ERK1/2 as well as p38-MAPK. Our study also demonstrated that CE6 significantly elevated intracellular cAMP levels and decreased thromboxane A2 formation in a concentration-dependent manner. Furthermore, we determined that CE6 initiated the activation of PKA, an effector of cAMP. Taken together, our findings indicate that CE6 may inhibit ADP-induced platelet activation by elevating cAMP levels and suppressing PI3K/Akt activity. Finally, these results suggest that CE6 could be developed as therapeutic agent that helps prevent thrombosis and ischemia.

  3. 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

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    Amadea M. Martischnig

    2015-01-01

    Full Text Available 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.

  4. Effects of epinephrine on ADP-induced changes in platelet inositol phosphates

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    Vickers, J.D.; Keraly, C.L.; Kinlough-Rathbone, R.L.; Mustard, J.F.

    1986-03-01

    Epinephrine (EPI) does not aggregate rabbit platelets, but it does increase the labelling of inositol phosphate (IP) at 60s (21%, p < 0.05) in the presence of 20 mM Li/sup +/, in platelets prelabelled with (/sup 3/H) inositol. In contrast, 0.5 ..mu..M ADP which causes aggregation, increases the labelling of inositol bisphosphate (IP/sub 2/) by 30% (p < 0.01) at 10s and by 46% (p < 0.05) at 60s and IP by 26% (p < 0.05) at 60s. The combination of 0.5 ..mu..M ADP and 50 ..mu..M EPI causes more extensive aggregation and increases IP/sub 2/ by 154% (p < 0.01) and IP by 65% (p < 0.01) at 60s. The increase in IP/sub 2/ stimulated by ADP + EPI was greater than the increase caused by ADP (p < 0.05). The authors examined the effects of ..cap alpha..- and ..beta..-adrenergic receptor blockers on EPI + ADP-induced changes in the inositol phosphates. The ..beta..-adrenergic blocker Sotalol (50 ..mu..M), which had no effect by itself, enhanced the accumulation of IP/sub 2/ due to 0.2 ..mu..M ADP + 0.6 ..mu..M EPI by 70% (p < 0.01) at 60s, as well as aggregation. This is consistent with EPI inhibition mediated through stimulation of adenylate cyclase via the ..beta..-adrenergic receptor. The ..cap alpha..-adrenergic blocker phentolamine (50 ..mu..M), reduced aggregation stimulated by 0.5 ..mu..M ADP + 50 ..mu..M EPI, and reduced the accumulation of IP by 53% (p < 0.05) and IP/sub 2/ by 108% (0 < 0.05). These data are compatible with the hypothesis that the effect of EPI on ADP-induced aggregation involves IP/sub 2/ metabolism stimulated via the ..cap alpha..-adrenergic receptor.

  5. Xanthohumol from hop cones (Humulus lupulus L.) prevents ADP-induced platelet reactivity.

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    Luzak, Boguslawa; Kassassir, Hassan; Rój, Edward; Stanczyk, Lidia; Watala, Cezary; Golanski, Jacek

    2017-02-01

    Hop cones (Humulus lupulus L.), very rich source of phenolic compounds, possessing anticancer, antioxidant and anti-inflammatory activities, are considered as beneficial diet ingredients improving human health. In this study, the antiplatelet action of xanthohumol (XN), the principal flavonoid in hop cones, was investigated. XN significantly attenuated ADP-induced blood platelet aggregation (97.2 ± 35.7 AU for 6 μg/ml of XN vs. 120.4 ± 30.1 AU for 0.17% dimethyl sulfoxide (DMSO), p < 0.001) and significantly reduced the expression of fibrinogen receptor (activated form of GPIIbIIIa) on platelets' surface (47.6 ± 15.8 for 1.5 μg/ml XN, 44.6 ± 17.3% for 3 μg/ml XN vs. 54.5 ± 19.2% for control or 43.3 ± 18.4% for 6 μg/ml XN vs. 49.7 ± 19.4% for 0.17% DMSO, p < 0.05 or less). These findings suggest that the phenolic compounds originating from hops (XN) have a novel role as antiplatelet agents and can likely be used as dietary supplements in prophylactic approaches.

  6. Relationship between ADP-induced platelet-fibrin clot strength and anti-platelet responsiveness in ticagrelor treated ACS patients

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    Li, Dan-Dan; Wang, Xu-Yun; Xi, Shao-Zhi; Liu, Jia; Qin, Liu-An; Jing, Jing; Yin, Tong; Chen, Yun-Dai

    2016-01-01

    Background Ticagrelor provides enhanced antiplatelet efficacy but increased risk of bleeding and dyspnea. This study aimed to display the relationship between ADP-induced platelet-fibrin clot strength (MAADP) and clinical outcomes in acute coronary syndrome (ACS) patients treated by ticagrelor. Methods Consecutive Chinese-Han patients with ACS who received maintenance dose of ticagrelor on top of aspirin were recruited. After 5-day ticagrelor maintenance treatment, MAADP measured by thrombelastography (TEG) were recorded for the evaluation of ticagrelor anti-platelet reactivity. Pre-specified cutoffs of MAADP > 47 mm for high on-treatment platelet reactivity (HTPR) and MAADP < 31 mm for low on-treatment platelet reactivity (LTPR) were applied for evaluation. The occurrences of primary ischemic cardiovascular events (including a composite of cardiac death, non-fatal myocardial infarction and stroke), the Thrombolysis in Myocardial Infarction (TIMI) defined bleeding events, and ticagrelor related dyspnea were recorded after a follow-up of three months. Results Overall, 176 ACS patients (Male: 79.55%, Age: 59.91 ± 10.54 years) under ticagrelor maintenance treatment were recruited. The value of MAADP ranged from 4.80% to 72.90% (21.27% ± 12.07% on average), with the distribution higher skewed towards the lower values. Using the pre-specific cutoffs for HTPR and LTPR, seven patients (3.98%) were identified as HTPR and 144 patients (81.82%) as LTPR. After a follow-up of three months in 172 patients, major cardiovascular events occurred in no patient, but TIMI bleeding events in 81 (47.09%) with major bleedings in three patients. All patients with major bleedings were classified as LTPR. Ticagrelor related dyspnea occurred in 31 (18.02%) patients, with 30 (21.28%) classified as LTPR and no one as HTPR (P = 0.02). Conclusions In ticagrelor treated ACS patients, MAADP measured by TEG might be valuable for the prediction of major bleeding and ticagrelor related dyspnea

  7. Platelet activation and aggregation

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    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  8. The inhibitory activity of ginsenoside Rp4 in adenosine diphosphate-induced platelet aggregation

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    Young-Min Son

    2017-01-01

    Conclusion: G-Rp4 significantly inhibited ADP-induced platelet aggregation and this is mediated via modulating the intracellular signaling molecules. These results indicate that G-Rp4 could be a potential candidate as a therapeutic agent against platelet-related cardiovascular diseases.

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

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    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.

  10. Effect of n-tyrosol on blood viscosity and platelet aggregation.

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    Plotnikov, M B; Chernysheva, G A; Smol'yakova, V I; Maslov, M Yu; Cherkashina, I V; Krysin, A P; Sorokina, I V; Tolstikova, T G

    2007-01-01

    Experiments on rats showed that n-tyrosol limited the increase in blood viscosity during thermal exposure at a shear rate of 5-300 sec(-1) and inhibited ADP-induced platelet aggregation. The effects of n-tyrosol are comparable to that of pentoxyphylline.

  11. Platelet aggregation associated with ethanol intoxication

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    Volk, S.; Walenga, J.; Fareed, J.; Schumacher, H. (Loyola Univ. Medical Center, Maywood, IL (USA))

    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.

  12. Platelet aggregation following trauma

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    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  13. Novel aspects of platelet aggregation

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    Roka-Moya Y. M.

    2014-01-01

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

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

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    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.

  15. Anti-aggregation action of ultraviolet irradiation on platelet-rich plasma in the presence of antioxidants

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    Roshchupkin, D.I.; Anosov, A.K.; Potapenko, A.Ya. (2nd Moscow Medical Institute, Moscow (USSR). Dept. of Biophysics)

    1983-05-01

    UV irradiation of platelet-rich plasma (PRP) results in the inhibition of ADP-induced platelet aggregation. This is accounted for by the long-living photoproducts formed in plasma. Platelets destroy these photoproducts in the dark after irradiation. Lipid antioxidants ..cap alpha..-tocopherol and BHT administered in PRP before irradiation reduce the anti-aggregation effect of UV light. Lipid photo-peroxidation is supposed to be responsible for the anti-aggregation effect of UV irradiation on platelet-rich plasma.

  16. Anti-aggregation action of ultraviolet irradiation on platelet-rich plasma in the presence of antioxidants

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    Roshchupkin, D.I.; Anosov, A.K.; Potapenko, A.Ya. (2nd Moscow Medical Institute, Moscow (USSR). Dept. of Biophysics)

    1983-05-01

    UV irradiation of platelet-rich plasma (PRP) results in the inhibition of ADP-induced platelets aggregation. This is accounted for by the long-living photoproducts formed in plasma. Platelets destruct these photoproducts in the dark after irradiation. Lipid antioxidants ..cap alpha..-tocopherol and BHT administered in PRP before irradiation reduce the anti-aggregation effect of UV light. Lipid photo-peroxidation is supposed to be responsible for the anti-aggregation effect of UV irradiation on platelet-rich plasma.

  17. Gingival tissue-produced inhibition of platelet aggregation and the loss of inhibition in streptozotocin-induced diabetic rats

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    Kawamura, Keiichiroh; Tamai, Kazuharu; Shirakawa, Masaharu; Okamoto, Hiroshi; Dohi, Toshihiro; Tsujimoto, Akira

    1988-01-01

    Addition of medium incubated with normal rat gingival tissue to platelet-rich plasma inhibited ADP-induced platelet aggregation. The ability of rat gingiva to produce activity inhibiting platelet aggregation was enhanced by the addition of arachidonic acid. Diabetic rat gingiva failed to inhibit platelet aggregation but did produce the anti-platelet aggregating activity in the presence of arachidonic acid. Indomethacin blocked the production of anti-platelet aggregating activity. There was no difference in conversion of (1-/sup 14/C)arachidonic acid to prostaglandins by normal and diabetic rat gingiva. These results suggest that an arachidonic acid metabolite released from gingiva during incubation inhibits platelet aggregation, and the synthesis of the metabolite is impaired in diabetic rat gingiva. A decrease in availability of arachidonic acid may be a causal factor of the defect in diabetic rat gingiva.

  18. Cyclosporine A enhances platelet aggregation.

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    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.

  19. PPARγ ligands decrease hydrostatic pressure-induced platelet aggregation and proinflammatory activity.

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    Fang Rao

    Full Text Available Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ. We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg or increased (120, 180, 240 mmHg hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg. The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs. These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure.

  20. Inhibition of human platelet aggregation in vitro by standardized extract of Wendtia calycina

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    Milagros Garcia Mesa

    2011-10-01

    Full Text Available Wendtia calycina (Griseb. Griseb., Vivianiaceae, is a Paraguayan herbaceous plant commonly known as burrito. Our previous study indicated that burrito leaves are a very good source of phenylpropanoid glycosides, principally verbascoside. From W. calycina leaves, a standardized, water-soluble extract rich in phenylpropanoid glycosides (WSE has been developed on an industrial scale to be used as a food supplement, cosmetic, phytomedicine, and ingredient of different formulations. In this study, we investigated the effect of the WSE on human platelet aggregation in vitro induced by adenosine diphosphate (ADP, epinephrine (EPN, collagen (COL or arachidonic acid (AA. WSE, concentration-dependently, inhibited ADP and EP-induced human platelet aggregation (IC50 were 0.82±0.15 mg/mL and 0.41±0.02 mg/mL, respectively. It did not inhibit collagen-induced platelet aggregation, thus suggesting a selectivity for the ADP-induced platelet activation pathways.

  1. Uridine Triphosphate Thio Analogues Inhibit Platelet P2Y12 Receptor and Aggregation

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    Gündüz, Dursun; Tanislav, Christian; Sedding, Daniel; Parahuleva, Mariana; Santoso, Sentot; Troidl, Christian; Hamm, Christian W.; Aslam, Muhammad

    2017-01-01

    Platelet P2Y12 is an important adenosine diphosphate (ADP) receptor that is involved in agonist-induced platelet aggregation and is a valuable target for the development of anti-platelet drugs. Here we characterise the effects of thio analogues of uridine triphosphate (UTP) on ADP-induced platelet aggregation. Using human platelet-rich plasma, we demonstrate that UTP inhibits P2Y12 but not P2Y1 receptors and antagonises 10 µM ADP-induced platelet aggregation in a concentration-dependent manner with an IC50 value of ~250 µM. An eight-fold higher platelet inhibitory activity was observed with a 2-thio analogue of UTP (2S-UTP), with an IC50 of 30 µM. The 4-thio analogue (4S-UTP) with an IC50 of 7.5 µM was 33-fold more effective. A three-fold decrease in inhibitory activity, however, was observed by introducing an isobutyl group at the 4S- position. A complete loss of inhibition was observed with thio-modification of the γ phosphate of the sugar moiety, which yields an enzymatically stable analogue. The interaction of UTP analogues with P2Y12 receptor was verified by P2Y12 receptor binding and cyclic AMP (cAMP) assays. These novel data demonstrate for the first time that 2- and 4-thio analogues of UTP are potent P2Y12 receptor antagonists that may be useful for therapeutic intervention. PMID:28146050

  2. Inhibition of platelet aggregation by polyaspartoyl L-arginine and its mechanism

    Institute of Scientific and Technical Information of China (English)

    Yin-ye WANG; Zhi-yu TANG; Min DONG; Xiao-yan LIU; Shi-qi PENG

    2004-01-01

    AIM: To observe the oral anti-platelet efficacy and the potential action mechanism of polyaspartoyl L-arginine (PDR), a new L-arginine rich compound. METHODS: Platelet aggregation was conducted by Born's method;bleeding time was determined using tail's bleeding time in mice; platelet adhesion was carried out with glass bottle method; nitric oxide (NO) was tested with Griess' method; and cAMP, thromboxane B2 (TXB2) and 6-keto-PGF1a were assessed with commercial kits. RESULTS: The inhibition by PDR (15-60 mg/kg ig or 10 mg/kg iv) of platelet aggregation induced by adenosine diphosphate (ADP), collagen or thrombin at 1 h after oral administration or at 20 min after iv injection for rats (P<0.01), and its (15 mg/kg, ig) inhibition of ADP-induced platelet aggregation for rabbits during 6 h after administration were observed. PDR (15-60 mg/kg) prolonged the bleeding time of mice (P<0.05) and (30 mg/kg) increased NO concentration in plasma. On the other hand PDR did not change the contents of cAMP in platelet and TXB2 or 6-keto-PGF1a in plasma. CONCLUSION: PDR is a novel, oral effective platelet aggregation inhibitor and its action mechanism possibly related to increasing NO generation.

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

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    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA) State Univ. of New York, Buffalo (USA))

    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.

  4. 21 CFR 864.5700 - Automated platelet aggregation system.

    Science.gov (United States)

    2010-04-01

    ... addition of an aggregating reagent to a platelet-rich plasma. (b) Classification. Class II (performance... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Automated platelet aggregation system. 864.5700... § 864.5700 Automated platelet aggregation system. (a) Identification. An automated platelet...

  5. Mapuche Herbal Medicine Inhibits Blood Platelet Aggregation

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    Susan Skanderup Falkenberg

    2012-01-01

    Full Text Available 12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM and collagen- (2.0 μg/mL induced aggregations in human blood. These four species in respective extracts (in brackets were Blechnum chilense (MeOH, Luma apiculata (H2O, Amomyrtus luma (DCM : MeOH 1 : 1 and Cestrum parqui (DCM : MeOH 1 : 1. The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1, and L. apiculata (H2O were substantial and confirmed by inhibition of platelet surface activation markers.

  6. Variability of the thrombin- and ADP-induced Ca2+ response among human platelets measured using fluo-3 and fluorescent videomicroscopy.

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    Tao, J; Rose, B; Haynes, D H

    1996-05-28

    The intracellular free Ca2+ concentration ([Ca2+]cyt) of individual human platelets localized between siliconized glass cover slips was determined at rest and after stimulation with thrombin and ADP using the Ca2+ indicator fluo-3 (0.97 +/- 0.30 mmol/l cell volume) with fluorescence video microscopy. Resting [Ca2+]cyt in the presence of 2 mM external Ca2+ showed only small inter-platelet variability ([Ca2+]cyt = 86 +/- 30 (S.D.) nM). Resting [Ca2+]cyt of individual fluo-3-loaded platelets measured as a function of time had a S.D. of 10 nM or 12% (S.D./mean). Individual platelets showed no affinity for the siliconized support and their [Ca2+]cyt showed no tendency to oscillate in either the resting or in the activated state. When 0.2 U/ml thrombin or 20 microM ADP were added, all platelets showed a characteristic Ca2+ transient whereby [Ca2+]cyt increased to peak values within 8-12 sec and then declined. The Ca2+ transients measured with fluo-3 were in approximate synchrony but peak [Ca2+]cyt values showed large inter-platelet variability. The ensemble average peak [Ca2+]cyt for thrombin and ADP were 672 +/- 619 (S.D.) nM and 640 +/- 642 (S.D.) nM, respectively. Thus inter-platelet variations (S.D./mean) were 92% or 100% as large as the average measured values. Mathematically-constructed averages of the single platelet experiments agreed reasonably well with platelet-averaged values obtained in parallel experiments with stirred platelet suspensions in a plastic cuvette, measured with a conventional spectrofluorometer. Peak [Ca2+]cyt values reflecting dense tubular Ca2+ release alone (external Ca2+ removed) also showed large interplatelet variation (171 +/- 105 (S.D.) nM with thrombin and 183 +/- 134 (S.D.) nM with ADP). Dense tubular Ca2+ release induced by cyclopiazonic acid (a dense tubular Ca2+-ATPase inhibitor) gave peak [Ca2+]cyt of 289 +/- 170 nM. Thus the size of the dense tubular Ca2+ pool has an inter-platelet variation of 59% (S.D./mean). Variability of

  7. Platelet Aggregation Inhibitors from Aerial Parts of Ruta Chalepensis Grown in Jordan

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    Mayadah B. Shehadeh

    2007-01-01

    Full Text Available From the aerial parts of Ruta chalepensis L., grown in Jordan, two furanocoumarins (bergapten and chalepensin, one flavonoid glycoside (rutin as well as several minor compounds have been isolated. The structural elucidation of these compounds was established based on spectral data (UV, IR, MS,1H-NMR and 13C-NMR. In Jordan, R. chalepensis is recommended for the treatment of rheumatism, mental disorders and menstrual problems. Fresh and dried leaves are used as flavoring agent in food and beverages. Antiplatelet activities of the crude methanolic and ethylacetate extracts in addition to the three isolated major compounds were measured by the aggrometric method according to Beretz and Casenave. Optical aggregometer connected to dual channel recorder was used for measuring aggregation. Both, ethylacetate and methanol extracts inhibited ADP- induced platelet aggregation (ADP-IA of human blood. However, only ethylacetate extract was able to induce 50% inhibition of collagen-induced platelet aggregation (Co-IA platelet rich plasma. Bergapten was more active against ADP-IA compared to chalepensin while the latter was more active against Co-IA compared to bergapten.

  8. The effect of ticlopidine administration to humans on the binding of adenosine diphosphate to blood platelets

    NARCIS (Netherlands)

    Lips, J.P.M.; Sixma, J.J.; Schiphorst, M.E.

    1980-01-01

    Administration of Ticlopidine to human volunteers resulted in a prolonged bleeding time and decreased or absent aggregation of platelets with collagen and epinephrine. Adenosine diphosphate (ADP) induced platelet aggregation was initiated by a normal shape change, but the rate of the first wave of a

  9. Evaluation of platelet aggregation in platelet concentrates: storage implications

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    Neiva Teresinha J.C.

    2003-01-01

    Full Text Available The use of hemo-derivatives is nowadays a fundamentally important therapeutic modality in the exercise of medicine. Among the various hemo-components employed, we have the platelet concentrate (PC, indicated in cases of hemorrhagic disturbances. We previously showed that platelet function in blood donors is reduced in their screening phase and after the separation process of PCs. Currently, we are providing evidence for the existence of biochemical and functional changes in PC preparations stored for three days at temperatures of 20 ± 2 ºC. Platelet concentrates from 40 healthy donors, collected in CPD anticoagulant and PL-146 polyvinylchloride containers, were examined in order to determine the pH value, pCO2 ,pO2 and lactate concentrations. In addition, the aggregation of platelets with thrombin and collagen were examined to evaluate platelet function. A pH increase from 7.07 ± 0.04 to 7.36 ± 0.07 (p < 0.01 was observed. The pCO2 concentration decreased progressively from 69.2 ± 7.7 mmHg to 28.8 ± 6.2 mmHg (p < 0.001 during the storage period. In contrast, pO2 value increase from 103.4 ± 30.6 to 152.3 ± 24.6 mmHg (p < 0.001 was evidenced during the 48 hours of storage. The lactate concentration increased from 17.97 ± 5.2 to 57.21 ± 5.7 mg/dl (p < 0.001. Platelet aggregation using 0.25 U/ml-thrombin and 2.0 µg/ml-collagen showed significant hypofunction from 61.8 ± 2.7% to 24.8 ± 9.8% and 62.7±5.0 to 33.4± 6.2 (p < 0.001, respectively. We concluded that the evaluated biochemical parameters and the platelet function changed significantly when the platelets were kept under routine storage conditions.

  10. Platelet aggregation secondary to coronary obstruction.

    Science.gov (United States)

    Moore, S

    1976-03-01

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

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

    Science.gov (United States)

    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.

  12. Platelet aggregation and quality control of platelet concentrates produced in the Amazon Blood Bank

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    Maria José Dantas Coêlho

    2011-01-01

    Full Text Available BACKGROUND: The study of platelet aggregation is essential to assess in vitro platelet function by different platelet activation pathways. OBJECTIVE: To assess aggregation and biochemical parameters of random platelet concentrates produced at the Fundação HEMOAM using the quality control tests defined by law. METHODS: Whole blood samples from 80 donors and the respective platelet concentrate units were tested. Platelet concentrates were tested (platelet count, aggregation and pH on days 1, 3 and 5 of storage. Additionally a leukocyte count was done only on day 1 and microbiological tests on day 5 of storage. Collagen and adenosine diphosphate were used as inducing agonists for platelet aggregation testing. RESULTS: Donor whole blood had normal aggregation (aggregation with adenosine diphosphate = 67% and with collagen = 78%. The median aggregation in platelet concentrates with adenosine diphosphate was low throughout storage (18% on day 1, 7% on day 3 and 6% on day 5 and the median aggregation with collagen was normal only on day 1 and low thereafter (54.4% on day 1, 20.5% on day 3 and 9% on day 5. CONCLUSION: Although the results were within the norms required by law, platelet concentrates had low aggregation rates. We suggest the inclusion of a functional assessment test for the quality control of platelet concentrates for a more effective response to platelet replacement therapy.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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), but was able to inhibit platelet fibrinogen binding capacity (P garlic leave juice was significantly lower than that in control group (P 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.

  15. Effects of hormones on platelet aggregation.

    Science.gov (United States)

    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.

  16. Increased platelet aggregability following an atherogenic diet in rabbits

    OpenAIRE

    Velkovski Saško D.; Mazić Sanja; Nešić Dejan M.; Igrački Iva; Milošević Verica L.; Starčević Vesna P.

    2002-01-01

    In atherosclerosis researches different animal models are used but the most common is the rabbit, because of the easy development of atherosclerotic lesions. Atherosclerosis is a multicellular process and platelets play an important role in atherogenesis. Excessive plasma lipids stimulate platelet aggregability and thus atherosclerosis development. The effects of an atherogenic diet on lipid status, abdominal aorta wall structure, and platelet aggregability were studied in rabbits. Adult male...

  17. Effects of Suilysin on Streptococcus suis-induced platelet aggregation

    Directory of Open Access Journals (Sweden)

    Shengwei Zhang

    2016-10-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

  19. Human platelet aggregation inhibitors from thyme (Thymus vulgaris L.).

    Science.gov (United States)

    Okazaki, Kenji; Kawazoe, Kazuyoshi; Takaishi, Yoshihisa

    2002-06-01

    Two antiaggregant compounds, thymol (compound 1) and 3,4,3',4'-tetrahydroxy-5,5'-diisopropyl-2,2'-dimethylbiphenyl (compound 2) were isolated from the leaves of thyme (Thymus vulgaris L.). The structures were determined by (1)H-, (13)C-NMR and mass spectra (MS) studies. These compounds inhibited platelet aggregation induced by collagen, ADP, arachidonic acid (AA) and thrombin except that compound 2 did not inhibit platelet aggregation induced by thrombin.

  20. Reference intervals for platelet aggregation assessed by multiple electrode platelet aggregometry

    DEFF Research Database (Denmark)

    Rubak, Peter; Villadsen, Kirsten; Hvas, Anne-Mette

    2012-01-01

    Abstract Introduction Analyses of platelet aggregation in hirudin whole blood using Multiplate® was validated. Reference intervals for the most commonly used agonists were established, and the association between platelet aggregation, age, gender and haematological values was analysed. Material...... and methods We included 121 healthy individuals to establish reference intervals and six healthy individuals for evaluation of the day-to-day variation. Platelet aggregation was evaluated on hirudin whole blood employing Multiplate® induced by arachidonic acid, ADP, collagen and ristocetin (RISTOlow...... reference interval is presented as 95% confidence interval suitable for any age and both sex. Day-to-day variation was

  1. A physical description of the adhesion and aggregation of platelets

    CERN Document Server

    Chopard, Bastien; Latt, Jonas; Dubois, Frank; Yourassowsky, Catherine; Van Antwerpen, Pierre; Eker, Omer; Vanhamme, Luc; Perez-Morga, David; Courbebaisse, Guy; Boudjeltia, Karim Zouaoui

    2015-01-01

    The early stages of clot formation in blood vessels involve platelets adhesion-aggregation. Although these mechanisms have been extensively studied, gaps in their understanding still persist. We have performed detailed in-vitro experiments and developed a numerical model to better describe and understand this phenomenon. Unlike previous studies, we took into account both activated and non-activated platelets, as well as the 3D nature of the aggregation process. Our investigation reveals that blood albumin is a major parameter limiting platelet adhesion and aggregation. Our results also show that the well accepted Zydney-Colton shear-induced diffusivity is much too low to explain the observed deposition rate. Simulations are in very good agreement with observations and provide quantitative estimates of the adhesion and aggregation rates that are hard to measure experimentally.

  2. Pistacia chinensis Methanolic Extract Attenuated MAPK and Akt Phosphorylations in ADP Stimulated Rat Platelets In Vitro

    Directory of Open Access Journals (Sweden)

    Ji Young Park

    2012-01-01

    (2.5–20 μg/mL inhibited ADP-induced platelet aggregation. While PCME diminished [Ca2+]i, ATP, and TXA2 release in ADP-activated platelets, it enhanced cAMP production in resting platelets. Likewise, PCME inhibited fibrinogen binding to αIIbβ3 and downregulated JNK, ERK, and Akt phosphorylations. Thus, PCME contains potential antiplatelet compounds that could be deployed for their therapeutic values in cardiovascular pathology.

  3. Influence of caffeine on blood pressure and platelet aggregation

    Directory of Open Access Journals (Sweden)

    José Wilson S. Cavalcante

    2000-08-01

    Full Text Available OBJECTIVE: Studies have demonstrated that methylxanthines, such as caffeine, are A1 and A2 adenosine receptor antagonists found in the brain, heart, lungs, peripheral vessels, and platelets. Considering the high consumption of products with caffeine in their composition, in Brazil and throughout the rest of the world, the authors proposed to observe the effects of this substance on blood pressure and platelet aggregation. METHODS: Thirteen young adults, ranging from 21 to 27 years of age, participated in this study. Each individual took 750mg/day of caffeine (250mg tid, over a period of seven days. The effects on blood pressure were analyzed through the pressor test with handgrip, and platelet aggregation was analyzed using adenosine diphosphate, collagen, and adrenaline. RESULTS: Diastolic pressure showed a significant increase 24 hours after the first intake (p<0.05. This effect, however, disappeared in the subsequent days. The platelet aggregation tests did not reveal statistically significant alterations, at any time during the study. CONCLUSION: The data suggest that caffeine increases diastolic blood pressure at the beginning of caffeine intake. This hypertensive effect disappears with chronic use. The absence of alterations in platelet aggregation indicates the need for larger randomized studies.

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

    Science.gov (United States)

    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 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.

  5. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.

    2007-01-01

    Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...... applied. However, the importance of these breed differences remains to be investigated. The PFA-100 method with Col + Epi as agonists, and ADP-induced platelet aggregation appear to be sensitive to ASA in dogs....

  6. Inhibition of smooth muscle contraction and platelet aggregation by peptide 204–212 of lipocortin 5: an attempt to define some structure requirements

    Directory of Open Access Journals (Sweden)

    K. G. Mugridge

    1993-01-01

    Full Text Available Peptide 204–212 of lipocortin (LC 5 inhibited porcine pancreatic phospholipase A2 (PLA2 induced rat stomach strip contractions and ADP induced rabbit platelet aggregation in a concentration dependent manner (IC30 of 10 μM and 400 μM, respectively. The first two amino acids are not necessary since the eptapeptide 206–212 was equipotent in both assays (IC30 of 12.5 μM and 420 μM. Of the two pentapeptides 204–208 and 208–212 only the latter showed inhibitory activity in both models although the potency was much reduced (IC30 of 170 μM and 630 μM compared with that of the parent nonapeptide. Comparison of peptide 204–212 effects with those of its analogues on LC1 and LC2 indicate that lysine 208 and aspartic acid 211 are essential in order to maintain a fully active nonapeptide.

  7. A new ibuprofen derivative inhibits platelet aggregation and ROS mediated platelet apoptosis.

    Directory of Open Access Journals (Sweden)

    Kodagahalli S Rakesh

    Full Text Available Thrombocytopenia is a serious issue connected with the pathogenesis of several human diseases including chronic inflammation, arthritis, Alzheimer's disease, cardiovascular diseases (CVDs and other oxidative stress-associated pathologies. The indiscriminate use of antibiotics and other biological drugs are reported to result in thrombocytopenia, which is often neglected during the treatment regime. In addition, augmented oxidative stress induced by drugs and pathological conditions has also been shown to induce thrombocytopenia, which seems to be the most obvious consequence of elevated rate of platelet apoptosis. Thus, blocking oxidative stress-induced platelet apoptosis would be of prime importance in order to negotiate thrombocytopenia and associated human pathologies. The current study presents the synthesis and platelet protective nature of novel ibuprofen derivatives. The potent anti-oxidant ibuprofen derivative 4f was selected for the study and the platelet protective efficacy and platelet aggregation inhibitory property has been demonstrated. The compound 4f dose dependently mitigates the oxidative stress-induced platelet apoptosis in both platelet rich plasma and washed platelets. The platelet protective nature of compound 4f was determined by assessing various apoptotic markers such as ROS generation, cytosolic Ca2+ levels, PS externalization, cytochrome C translocation, Caspase activation, mitochondrial membrane depolarization, cytotoxicity, LDH leakage and tyrosine phosphorylation of cytosolic proteins. Furthermore, compound 4f dose dependently ameliorated agonist induced platelet aggregation. Therefore, compound 4f can be estimated as a potential candidate in the treatment regime of pathological disorders associated with platelet activation and apoptosis. In addition, compound 4f can be used as an auxiliary therapeutic agent in pathologies associated with thrombocytopenia.

  8. ENHANCED PLATELET AGGREGABILITY UNDER HIGH SHEAR STRESS IN CORONARY CIRCULATION OF PATIENTS WITH UNSTABLE ANGINA

    OpenAIRE

    Doi, Naofumi

    2000-01-01

    Mechanical forces, including high shear stress, have been found to cause platelet aggregation. Although increased platelet aggregation is also associated with the pathophysiology of unstable angina, it is not known whether platelet aggregation induced by high shear stress occurs in the coronary circulation of patients with unstable angina. We assayed high shear stress induced platelet aggregation (h-SIPA) in each of 25 patients with unstable angina and a severe stenotic lesion of the left cor...

  9. Surface-secreted von Willebrand factor mediates aggregation of ADP-activated platelets at moderate shear stress: facilitated by GPIb but controlled by GPIIb-IIIa.

    Science.gov (United States)

    Frojmovic, M M; Kasirer-Friede, A; Goldsmith, H L; Brown, E A

    1997-03-01

    We previously showed that ADP activation of washed human platelets in plasma-free suspensions supports aggregation at moderate shear stress (0.4-1.6 Nm-2) in Poiseuille flow. Although most activated platelets expressed maximal fibrinogen-occupied GPIIb-IIIa receptors, aggregation appeared to be independent of bound fibrinogen, but blocked by the hexapeptide GRGDSP. Here, we tested the hypothesis that von Willebrand factor (vWF) secreted and expressed on activated platelets mediates aggregation at moderate shear rates from 300 to 1000 s-1 corresponding to shear stresses from 0.3 to 1.1 Nm-2. Relatively unactivated platelets (Flow cytometric measurements with monoclonal antibody (mAb) 2.2.9 reporting on surface-bound vWF, and with mAb S12 reporting on alpha-granule secreted P-selectin, showed that 65% and 80%, respectively, of all platelets were maximally activated with respect to maximal secretion and surface expression of these proteins. "Resting" washed platelets exhibited both surface-bound vWF and significant P-selectin secretion. We showed that mAbs 6D1 and NMC4, respectively blocking the adhesive domains on the GPIb receptor recognizing vWF, and on the vWF molecule recognizing the GPIb receptor, partially inhibited ADP-induced aggregation under shear in Couette flow, the degree of inhibition increasing with increasing shear stress. In contrast, mAb 10E5, blocking the vWF binding domain on GPIIb-IIIa, essentially blocked all aggregation at the shear rates tested. We conclude that vWF, expressed on ADP-activated platelets, is at least the predominant cross-bridging molecule mediating aggregation at moderate shear stress. There is an absolute requirement for free activated GPIIb-IIIa receptors, postulated to interact with platelet-secreted, surface bound vWF. The GPIb-vWF cross-bridging reaction plays a facilitative role becoming increasingly important with increasing shear stress. Since aurin tricarboxylic acid, which blocks the GPIb binding domain on vWF, was

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

    DEFF Research Database (Denmark)

    Dag, B; Fornitz, Gitte Gleerup; Bak, A M;

    1994-01-01

    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 ... 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 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....

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. The automation of routine light transmission platelet aggregation

    Science.gov (United States)

    Lawrie, A S; Kobayashi, K; Lane, P J; Mackie, I J; Machin, S J

    2014-01-01

    Introduction The investigation of platelet function by aggregometry requires specialist equipment and is labour intensive. We have developed an automated platelet aggregation method on a routine coagulation analyser. Methods We used a CS-2000i (Sysmex) with prototype software to perform aggregation in platelet-rich plasma (PRP), using the following agonists: ADP (0.5–10 μm), epinephrine (0.5–10 μm), collagen (0.5–10 mg/μL), ristocetin (0.75–1.25 mg/mL) and arachidonic acid (0.12–1.0 mm). Platelet agonists were from Hyphen Biomed, and an AggRAM aggregometer (Helena Biosciences) was used as the reference instrument. Results CS-2000i reaction cuvette stirrer speed was found to influence reaction sensitivity and was optimized to 800 rpm. There were no clinically significant changes in aggregation response when the PRP platelet count was 150–480 x 109/L, but below this there were changes in the maximum amplitude (MA) and slope (rate). Dose response with each of the agonists was comparable between CS-2000i and an AggRAM aggregometer and normal subjects receiving antiplatelet drugs. Aggregation imprecision was similar on both the CS-2000i and AggRAM systems, with a cv for 2–5 μm ADP MA and slope varying between 3–12%. Conclusion Our preliminary studies indicated that optimal sensitivity using the CS-2000i was obtained with a reaction cuvette stirrer speed of 800 rpm and a PRP platelet count of 200–300 x 109/L; aggregation with a PRP count <100 x 109/L showed poor sensitivity. Imprecision and detection of antiplatelet drug effects was similar between the CS-2000i and AggRAM. These data demonstrate that CS-2000i is comparable to a stand-alone aggregometer, although CS-2000i has the advantages of walk-away technology and also required a smaller sample volume than the AggRAM (44% less). PMID:24237750

  13. Spontaneous and Induced Platelet Aggregation during Pregnancy and Labor

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    T. P. Bondar

    2016-01-01

    Full Text Available Objective: to evaluate changes in characteristics of spontaneous platelet (Pt aggregation in patients with obstetric complications associated with hereditary thrombophilia.Materials and methods. Blood samples were taken from 52 recently confined women on the first day after labor; at that, ethic regulations for the preanalytical phase were followed. Determination of PlA1/ PlA2 polymorphism enotype was performed by means of amplificationrestriction analysis. Geometrical characteristics of patients' peripheral blood Pt aggregation were studied by means of AFM Integra Prima. The degree of confidence of the parameters under test was determined using the ttest, and the significance level was considered valid at P<0.05.Results. A statistical analysis of the findings demonstrated that the length of Pt aggregates in healthy pregnant women was significantly higher than that in healthy nonpregnant women at all study phases. Patients with the P1A1/P1A2 polymorphism in the GP IIb/IIIa Pt receptor gene demonstrated increased widthm height, and density of Pt aggregates. The changes were most significant during the incubation phase lasting for 15 and 30 minutes. The study of geometric parameters of different exposures demonstrated the following: the longer the incubation period, the greater the difference between geometric parameters of the aggregates (e.g. height, length, and width. Conclusion. The analysis of obtained data demonstrated that the presence of P1A1/P1A2 polymorphism in GP IIb/IIIa Pt gene receptor contributes to the decrease in the platelet response threshold and enhances the spontaneous Pt aggregation. The imaging of aggregates provides strong evidence for the accelerated growth of the aggregates in thrombotic complications of pregnancy.

  14. Metabolic energy is required in human platelets at any stage during optical aggregation and secretion

    NARCIS (Netherlands)

    Akkerman, Jan Willem N.; Verhoeven, A.J.M.; Mommersteeg, M.E.

    1984-01-01

    The relationship between metabolic energy and platelet aggregation and secretion was investigated by sudden exhaustion of the cell energy content after these platelet responses had been initiated. In normal platelets, optical aggregation was at any stage susceptible to energy exhaustion, whereas sin

  15. VerifyNow and VASP phosphorylation assays give similar results for patients receiving clopidogrel, but they do not always correlate with platelet aggregation.

    Science.gov (United States)

    Bidet, Audrey; Jais, Catherine; Puymirat, Etienne; Coste, Pierre; Nurden, Alan; Jakubowski, Joseph; Nurden, Paquita

    2010-01-01

    Point-of-care testing permits an evaluation of the efficacy of drugs used in the treatment of acute coronary syndromes (ACS). An increased risk of thrombosis after coronary stenting for ACS patients treated with aspirin and clopidogrel has been linked to high platelet reactivity and, for certain patients, poor drug response. The objective of our study was to compare the VerifyNow-P2Y12 device with the VASP (vasodilator-stimulated phosphoprotein) phosphorylation assay and ADP-induced platelet aggregation as assessed by light transmission aggregometry in a group of 81 ACS patients (100 tests) treated in our hospital. There was a good correlation between VerifyNow-P2Y12 and VASP especially during the chronic phase of one month or more after the ischemic event, whereas discordance was sometimes seen with platelet aggregometry. The rapidity and ease of use of the VerifyNow device suggests that it has a valuable place in point-of-care testing of ACS patients.

  16. Influence of gold nanoparticles on platelets functional activity in vitro

    Science.gov (United States)

    Akchurin, Garif G.; Akchurin, George G.; Ivanov, Alexey N.; Kirichuk, Vyacheslav F.; Terentyuk, George S.; Khlebtsov, Boris N.; Khlebtsov, Nikolay G.

    2008-02-01

    Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA >, Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole (>, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

  17. Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available BACKGROUND: Nitrite is a nitric oxide (NO metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated. METHODOLOGY/FINDING: Platelet aggregation was studied in platelet-rich plasma (PRP and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger, suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes. CONCLUSION: Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia.

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

    Science.gov (United States)

    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

  19. Identification of a tsetse fly salivary protein with dual inhibitory action on human platelet aggregation.

    Directory of Open Access Journals (Sweden)

    Guy Caljon

    Full Text Available BACKGROUND: Tsetse flies (Glossina sp., the African trypanosome vectors, rely on anti-hemostatic compounds for efficient blood feeding. Despite their medical importance, very few salivary proteins have been characterized and functionally annotated. METHODOLOGY/PRINCIPAL FINDINGS: Here we report on the functional characterisation of a 5'nucleotidase-related (5'Nuc saliva protein of the tsetse fly Glossina morsitans morsitans. This protein is encoded by a 1668 bp cDNA corresponding at the genomic level with a single-copy 4 kb gene that is exclusively transcribed in the tsetse salivary gland tissue. The encoded 5'Nuc protein is a soluble 65 kDa glycosylated compound of tsetse saliva with a dual anti-hemostatic action that relies on its combined apyrase activity and fibrinogen receptor (GPIIb/IIIa antagonistic properties. Experimental evidence is based on the biochemical and functional characterization of recombinant protein and on the successful silencing of the 5'nuc translation in the salivary gland by RNA interference (RNAi. Refolding of a 5'Nuc/SUMO-fusion protein yielded an active apyrase enzyme with K(m and V(max values of 43+/-4 microM and 684+/-49 nmol Pi/min xmg for ATPase and 49+/-11 microM and 177+/-37 nmol Pi/min xmg for the ADPase activity. In addition, recombinant 5'Nuc was found to bind to GPIIb/IIIa with an apparent K(D of 92+/-25 nM. Consistent with these features, 5'Nuc potently inhibited ADP-induced thrombocyte aggregation and even caused disaggregation of ADP-triggered human platelets. The importance of 5'Nuc for the tsetse fly hematophagy was further illustrated by specific RNAi that reduced the anti-thrombotic activities in saliva by approximately 50% resulting in a disturbed blood feeding process. CONCLUSIONS/SIGNIFICANCE: These data show that this 5'nucleotidase-related apyrase exhibits GPIIb/IIIa antagonistic properties and represents a key thromboregulatory compound of tsetse fly saliva.

  20. [Effect of magnesium, acetylsalicilic acid and emoxypine on aggregation of platelets].

    Science.gov (United States)

    Loznikova, S Zh; Sukhodola, A A; Shcharbina, N Iu; Shcharbin, D G

    2014-01-01

    The thrombin-induced platelet aggregation was studied in the absence and presence of magnesium sulfate, acetylsalicylic acid and emoxypine. It was found that all the preparations studied were able separately to decrease platelet aggregation. In contrast, their joint action was not able to affect the aggregation of platelets. The data obtained can be used to choose the treatment strategy for patients with ischemic stroke.

  1. Validation of a P2Y12-receptor specific whole blood platelet aggregation assay.

    Science.gov (United States)

    Amann, Michael; Ferenc, Miroslaw; Valina, Christian M; Bömicke, Timo; Stratz, Christian; Leggewie, Stefan; Trenk, Dietmar; Neumann, Franz-Josef; Hochholzer, Willibald

    2016-11-01

    Testing of P2Y12-receptor antagonist effects can support clinical decision-making. However, most platelet function assays use only ADP as agonist which is not P2Y12-receptor specific. For this reason P2Y12-receptor specific assays have been developed by adding prostaglandin E1 (PGE1) to reduce ADP-induced platelet activation via the P2Y1-receptor. The present study sought to evaluate a P2Y12-receptor specific assay for determination of pharmacodynamic and clinical outcomes. This study enrolled 400 patients undergoing coronary stenting after loading with clopidogrel or prasugrel. ADP-induced platelet reactivity was assessed by whole blood aggregometry at multiple time points with a standard ADP assay (ADPtest) and a P2Y12-receptor specific assay (ADPtest HS, both run on Multiplate Analyzer, Roche Diagnostics). Patients were clinically followed for 1 month and all events adjudicated by an independent committee. In total, 2084 pairs of test results of ADPtest and ADPtest HS were available showing a strong correlation between results of both assays (r = 0.96, p < 0.001). These findings prevailed in multiple prespecified subgroups (e.g., age; body mass index; diabetes). Calculated cutoffs for ADPtest HS and the established cutoffs of ADPtest showed a substantial agreement for prediction of ischemic and hemorrhagic events with a Cohen's κ of 0.66 and 0.66, respectively. The P2Y12-receptor specific ADPtest HS assay appears similarly predictive for pharmacodynamic and clinical outcomes as compared to the established ADPtest assay indicating its applicability for clinical use. Further evaluation in large cohorts is needed to determine if P2Y12-receptor specific testing offers any advantage for prediction of clinical outcome.

  2. Effect of coffee drinking on platelets: inhibition of aggregation and phenols incorporation.

    Science.gov (United States)

    Natella, F; Nardini, M; Belelli, F; Pignatelli, P; Di Santo, S; Ghiselli, A; Violi, F; Scaccini, C

    2008-12-01

    Epidemiological studies indicate a J-shaped relationship linking coffee consumption and cardiovascular risk, suggesting that moderate coffee consumption can be beneficial. Platelet aggregation is of critical importance in thrombotic events, and platelets play a major role in the aetiology of several CVD. The aim of this study was to evaluate the effect of coffee drinking on platelet aggregation ex vivo, using caffeine as control. A crossover study was performed on ten healthy subjects. In two different sessions, subjects drank 200 ml coffee, containing 180 mg caffeine, or a capsule of caffeine (180 mg) with 200 ml water. Platelets were separated from plasma at baseline and 30 and 60 min after coffee drinking. Platelet aggregation was induced with three different agonists: collagen, arachidonic acid and ADP. Coffee drinking inhibited collagen (P Caffeine intake did not affect platelet aggregation induced by the three agonists. Coffee consumption induced a significant increase of platelet phenolic acids (likely present as glucuronate and sulphate derivatives), caffeic acid, the principal phenolic acid in coffee, raising from 0.3 (SEM 0.1) to 2.4 (SEM 0.6) ng/mg (P Caffeine was not detectable in platelets. Coffee drinking decreases platelet aggregation, and induces a significant increase in phenolic acid platelet concentration. The antiplatelet effect of coffee is independent from caffeine and could be a result of the interaction of coffee phenolic acids with the intracellular signalling network leading to platelet aggregation.

  3. Platelets possess functional TGF-beta receptors and Smad2 protein.

    Science.gov (United States)

    Lev, P R; Salim, J P; Marta, R F; Osorio, M J Mela; Goette, N P; Molinas, F C

    2007-02-01

    TGF-beta1 plays a main role in tissue repair by regulating extracellular matrix production and tissue granulation. Platelets are one of the main sources of this cytokine in the circulation. The aim of this study was to evaluate the presence of the TGF-beta receptors on platelets, the effect of TGF-beta1 on platelet aggregation and the underlying intracellular mechanisms. TGF-beta receptors on platelets were studied by flow cytometry and their mRNA by PCR. Platelet aggregation was assessed by turbidimetric methods and intracellular pathways by Western blot. TGF-beta receptor type II and mRNA codifying for TbetaRI and TbetaRII were found in platelets. We demonstrated that TGF-beta1 did not trigger platelet aggregation by itself but had a modulating effect on ADP-induced platelet aggregation. Either inhibition or increase in platelet aggregation, depending on the exposure time to TGF-beta1 and the ADP concentration used, were shown. We found that platelets possess Smad2 protein and that its phosphorylation state is increased after exposure to TGF-beta1. Besides, TGF-beta1 modified the pattern of ADP-induced tyrosine phosphorylation. Increased phosphorylation levels of 64-, 80- and 125-kDa proteins during short time incubation with TGF-beta1 and increased phosphorylation of 64- and 125-kDa proteins after longer incubation were observed. The modulating effect of TGF-beta1 on platelet aggregation could play a role during pathological states in which circulating TGF-beta1 levels are increased and intravascular platelet activation is present, such as myeloproliferative disorders. In vascular injury, in which platelet activation followed by granule release generates high local ADP concentrations, it could function as a physiological mechanism of platelet activation control.

  4. Production and characterization of monoclonal antibodies against rat platelet GPIIb/IIIa

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, H.; Tamura, S.; Sudo, T.; Suzuki, T. (Kirin Brewery Co., Ltd., Gunma (Japan))

    1990-09-15

    Four murine monoclonal antibodies against rat platelets were produced by fusion of spleen cells from mice intravenously immunized with whole rat platelets. All four antibodies immunoprecipitated two major platelet membrane proteins with apparent molecular weights of 130,000 and 82,000 (nonreduced) and of 120,000 and 98,000 (reduced), which were structurally analogous to human glycoprotein (GP) IIb/IIIa, i.e. rat GPIIb/IIIa. Two of four antibodies, named P9 and P55, strongly inhibited adenosine diphosphate (ADP)-induced aggregation of washed rat platelets and caused approximately 50% inhibition of human fibrinogen binding to ADP-stimulated rat platelets, suggesting that rat GPIIb/IIIa serves as a fibrinogen receptor in ADP-induced aggregation. In contrast, two other antibodies, named P14 and P34, themselves caused aggregation of rat platelets in platelet-rich plasma (PRP) and the secretion of 14C-serotonin from 14C-serotonin-labeled PRP. These results indicate that rat GPIIb/IIIa plays an important role in platelet aggregation.

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

    Science.gov (United States)

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

    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.

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

    Science.gov (United States)

    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.

  7. A practical synthesis of sarpogrelate hydrochloride and in vitro platelet aggregation inhibitory activities of its analogues

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A convenient approach for the preparation of sarpogrelate hydrochloride was developed.Two series of sarpogrelate hydrochloride analogues were designed and synthesized in order to improve their platelet aggregation inhibitory activities, biological tests suggested that these compounds have platelet aggregation inhibitory activities to some extent.

  8. Fusaric acid, a mycotoxin, and its influence on blood coagulation and platelet function.

    Science.gov (United States)

    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.

  9. In vitro effects of mercury on platelet aggregation, thromboxane and vascular prostacyclin production.

    Science.gov (United States)

    Caprino, L; Togna, A R; Cebo, B; Dolci, N; Togna, G

    1983-01-01

    Mercuric chloride [25-50 micrograms/ml platelet-rich plasma (PRP)] lowers the threshold concentration of arachidonic acid (AA) required for triggering rabbit platelet aggregation and causes a marked increase of thromboxane production. The metal, added as HgCl2, does not modify (50 micrograms/ml PRP) or block (100 micrograms/ml PRP) the platelet aggregation wave induced by a normal aggregating dose of AA. Whether or not AA-induced platelet aggregation takes place, a large increase in thromboxane production is observed. Methyl mercury, assayed as reference drug, induces platelet aggregation and a significant increase of thromboxane levels. Finally, HgCl2 and methyl mercury, in a concentration range of 0.125-0.5 micrograms/microliters in the incubation liquid, induce an increased prostacyclin release from rat aortic tissue.

  10. Detection of Platelet-Monocyte Aggregates by the ADAM® Image Cytometer

    OpenAIRE

    Jung, Bo Kyeung; Cho, Chi Hyun; Moon, Kyung Chul; sung Hur, Dae; YOON, Jeong-Ah; Yoon, Soo-Young

    2014-01-01

    Background: Inappropriate platelet activation is known to be associated with various thrombotic disorders. Platelet-monocyte aggregates (PMAs), whose formation is mediated by platelet surface P-selectin (CD62P), can be used as a reliable marker to detect platelet activation. Previous studies have generally detected PMAs through flow cytometry-based approaches. Recently, the ADAM® image cytometer (Nanoentek Inc., Seoul, Korea) was developed for image-based cellular analysis. In this study, we ...

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

    Science.gov (United States)

    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.

  12. Correlation between the In Vitro Functionality of Stored Platelets and the Cytosolic Esterase-Induced Fluorescence Intensity with CMFDA.

    Science.gov (United States)

    Wang, Jiexi; Yi, Xiaoyang; Liu, Minxia; Zhou, Qian; Ren, Suping; Wang, Yan; Yang, Chao; Zhou, Jianwei; Han, Ying

    2015-01-01

    It has been hypothesized that the cytosolic esterase-induced fluorescence intensity (CEIFI) from carboxy dimethyl fluorescein diacetate (CMFDA) in platelets may related to platelet functions. In the present study, we measured the change of CEIFI in platelets during storage, and examined the correlations of CEIFI with the in vitro functionality of stored platelets, including the ADP-induced aggregation activity, hypotonic shock response, expression of CD62P as well as platelet apoptosis. The CEIFI of fresh platelets, when tested at 10 μM CMFDA, the mean fluorescence intensity index (MFI) was 305.9 ± 49.9 (N = 80). After 1-day storage, it was 203.8 ± 34.4, the CEIFI of the stored platelets started to decline significantly, and reduced to 112.7 ±27.7 after 7-day storage. The change in CEIFI is highly correlated to all four functional parameters measured, with the correlation coefficients being 0.9813, 0.9848, -0.9945 and -0.9847 for the ADP-induced aggregation activity, hypotonic shock response (HSR), expression of CD62P and platelet apoptosis respectively. The above results show that the CEIFI measurement of platelets represents well the viability and functional state of in vitro stored platelets. This may be used as a convenient new method for quality evaluation for stored platelets if this result can be further validated by the following clinical trials.

  13. Platelet aggregation function monitored by light transmittance aggregometry and continuous platelet count%光学比浊法与连续血小板计数法监测血小板聚集功能的比较

    Institute of Scientific and Technical Information of China (English)

    关杰; 任军伟; 朱远; 傅淑宏; 白洁; 邓新立; 丛玉隆

    2013-01-01

      目的评价血小板功能检测仪PL-11应用的连续血小板计数方法(PL-11)监测血小板功能的价值。方法通过光学比浊法(light transmittance aggregometry,LTA)与PL-11连续血小板计数法检测本院2012年26例服用氯吡格雷抗凝治疗的心血管病患者和45例健康志愿者的血小板聚集功能,分析两种方法相关性及差异。结果血小板聚集诱聚剂二磷酸腺苷(adenosine diphosphate,ADP)诱导的LTA与PL-11最大血小板聚集率(maximal aggregation ratio,MAR)存在较好相关性(r=0.766,P<0.0001)。分别用LTA与PL-11检测健康志愿者组、服药患者组,最大血小板聚集率均存在统计学差异(P<0.0001)。在两组人群中,LTA测得最大血小板聚集率范围均较PL-11广。PL-11在每例标本检测过程中,各测试点提供的平均血小板体积(mean platelet volume,MPV)变化趋势与检测期间血小板聚集率变化情况一致。结论 PL-11连续血小板计数法与“金标准”的光学比浊法检测血小板聚集功能时有较好的相关性,其应用价值可供临床及实验室参考。富血小板血浆标本与全血标本可能是两种方法检测结果差异的原因。%Objective To assess the value of continuous platelet count with platelet function analyzer PL-11 in monitoring platelet function. Methods Platelet function of 26 coronary artery disease (CAD) patients admitted to our hospital in 2012 for anticoagulant therapy with clopidogrel and 45 healthy volunteers was detected by light transmittance aggregometry (LTA) and continuous platelet count with platelet function analyzer PL-11, respectively. The correlation and the different results in the two methods were analyzed. Results The adenosine diphosphate (ADP)-induced maximal aggregation ratio (MAR) detected by LTA and continuous platelet count with PL-11 was well-correlated in CAD patients and healthy volunteers (r=0.766, P<0.000 1). The MAR detected by LTA was higher

  14. [Effect of dauricine on rat and human platelet aggregation and metabolism of arachidonic acid in washed rat platelets].

    Science.gov (United States)

    Tong, L; Yue, T L

    1989-01-01

    Dauricine (Dau), an isoquinoline alkaloid extracted from the roots of Menispermum dauricum D. C. and used as an antiarrhythmic agent in China recently, was shown to inhibit rat platelet aggregation induced by arachidonic acid (AA) and ADP, as well as human platelet aggregation induced by AA, ADP and adrenaline (Adr) in vitro in a dose-dependent manner. The concentration of Dau required for 50% inhibition (IC50) of rat platelet aggregation induced by AA and ADP was 26 and 37 mumol/L, respectively. For human platelet aggregation induced by AA, ADP and Adr the IC50 of Dau was found to be 39, 55 and 43 mumol/L, respectively. Dau inhibited the cyclooxygenase pathway metabolites of AA (TXB2 and HHT) in washed intact rat platelets. The production of TXB2 and HHT was reduced by 26% and 19%, respectively, when the Dau concentration was 50 mumol/L and by 46 and 45%, respectively, when the concentration of Dau was 100 mumol/L. The formation of 12-HETE was also inhibited at 100 mumol/L of Dau. The inhibitory effect of Dau on AA metabolism may be one of the mechanisms related to its inhibition of platelet aggregation.

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

    Science.gov (United States)

    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.

  16. Platelet function and fibrinolytic activity following distance running.

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    Knudsen, J B; Brodthagen, U; Gormsen, J; Jordal, R; Nørregaard-Hansen, K; Paulev, P E

    1982-11-01

    6 long distance runners from the Danish marathon elite and 6 non-runners completed test runs of 28 and 12 km, respectively. Distance runners and non-runners showed the same responses in platelet function. We found a significant decrease in ADP induced platelet aggregability, a decreased serotonin release induced by ADP and collagen and an increase in platelet factor 4 immediately following the run. The antithrombin III levels remained constant. Euglobulin lysis time was shortened (by approximately 50%) and the plasminogen levels significantly increased. The last 2 findings indicate an equal increase in fibrinolytic activity during distance running in both groups. While short term, strenuous exercise induces platelet hyperaggregation, long term distance running induces a state of exhaustion of platelet aggregation capacity.

  17. EFFECTS OF CARVEDILOL ON PLATELET AGGREGATION IN MEN WITH ST-ELEVATION ACUTE MYOCARDIAL INFARCTION

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    A. N. Zakirova

    2010-01-01

    Full Text Available Aim. To study influence of beta-blockers carvedilol and metoprolol tartrate on platelet aggregative ability, evaluated by three different methods, in patients with acute ST segment elevation myocardial infarction (STEMI.Material and methods. A total of 86 men aged 36-68 with uncomplicated STEMI were included into an open, comparative, randomized study. Patients were randomized into two groups of beta-blocker treatments. Patients (n=44 of the first group received carvedilol; patients (n=42 of the second one - metoprolol tartrate. Parameters of platelet hemostasis: the maximum amplitude and rate of platelet aggregation induced by ADP, ristomycin and collagen; mean platelet volume (MPV; serum level of soluble CD40 ligand (sCD40L were evaluated on the 2nd and 24th day after STEMI onset.Results. In patients with uncomplicated STEMI carvedilol more prominently reduced in vitro platelet aggregation induced by adenozin-5'-diphosphate in high concentration, ristomycin and collagen than metoprolol tartrate. Сarvedilol also more significantly decreased MPV in comparison with metoprolol tartrate. However, effect of both carvedilol and metoprolol tartrate on the level of another platelet aggregation marker - sCD40L was comparable.Conclusion. Carvedilol and metoprolol tartrate have similar effect on platelet aggregation though in according to some tests carvedilol more prominently reduces platelet aggregation than metoprolol tartrate.

  18. Platelet aggregation measurement for assessment of hemostasis failure mechanisms in patients with gastroduodenal ulcer bleeding

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    Barinov, Edward; Sulaieva, Oksana; Lyakch, Yuriy; Guryanov, Vitaliy; Kondratenko, Petr; Radenko, Yevgeniy

    2013-01-01

    Background The purpose of this study was to identify factors associated with the risk of unsustainable hemostasis in patients with gastric and duodenal ulcer bleeding by in vitro assessment of platelet reactivity using artificial neural networks. Methods Patients with gastroduodenal ulcers complicated by bleeding were studied. Platelet aggregation was measured using aggregometry with adenosine diphosphate 5 μM, epinephrine 2.5 μM, 5-hydroxytryptophan 10 μM, collagen 1 μM, and thrombin 0.06 NIH Unit/mL as agonists. Multiple logistic regression was used to evaluate the independent relationship between demographic, clinical, endoscopic, and laboratory data and in vitro assessment of platelet reactivity and local parameters of hemostasis in patients with ulcer bleeding. Results Analysis of platelet aggregation in patients with gastroduodenal ulcer bleeding allowed the variability of platelet response to different agonists used in effective concentration which induces 50% platelet aggregation (EC50) to be established. The relationship between platelet aggregation and the spatial-temporal characteristics of ulcers complicated by bleeding was demonstrated. Adrenoreactivity of platelets was associated with time elapsed since the start of ulcer bleeding and degree of hemorrhage. The lowest platelet response to collagen and thrombin was detected in patients with active bleeding (P < 0.001) and unsustainable recent bleeding (P < 0.01). Decreased adenosine diphosphate-induced platelet aggregation in patients with ulcer bleeding was correlated with the platelet response to thrombin (r = 0.714, P < 0.001) and collagen (r = 0.584, P < 0.01). Conclusion Estimation of platelet reactivity in vitro indicates the key mechanisms of failure of hemostasis in patients with ulcer bleeding. In addition to gender, an important determinant of unsustainable hemostasis was a decreased platelet response to thrombin and adenosine diphosphate. PMID:23950655

  19. Adenosine diphosphate-induced aggregation of human platelets in flow through tubes. I. Measurement of concentration and size of single platelets and aggregates.

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    Bell, D N; Spain, S; Goldsmith, H L

    1989-11-01

    A double infusion flow system and particle sizing technique were developed to study the effect of time and shear rate on adenosine diphosphate-induced platelet aggregation in Poiseuille flow. Citrated platelet-rich plasma, PRP, and 2 microM ADP were simultaneously infused into a 40-microliters cylindrical mixing chamber at a fixed flow ratio, PRP/ADP = 9:1. After rapid mixing by a rotating magnetic stirbar, the platelet suspension flowed through 1.19 or 0.76 mm i.d. polyethylene tubing for mean transit times, t, from 0.1 to 86 s, over a range of mean tube shear rate, G, from 41.9 to 1,000 s-1. Known volumes of suspension were collected into 0.5% buffered glutaraldehyde, and all particles in the volume range 1-10(5) microns 3 were counted and sized using a model ZM particle counter (Coulter Electronics Inc., Hialeah, FL) and a logarithmic amplifier. The decrease in the single platelet concentration served as an overall index of aggregation. The decrease in the total particle concentration was used to calculate the collision capture efficiency during the early stages of aggregation, and aggregate growth was followed by changes in the volume fraction of particles of successively increasing size. Preliminary results demonstrate that both collision efficiency and particle volume fraction reveal important aspects of the aggregation process not indicated by changes in the single platelet concentration alone.

  20. Mechanisms of xenogeneic baboon platelet aggregation and phagocytosis by porcine liver sinusoidal endothelial cells.

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    Qiang Peng

    Full Text Available BACKGROUND: Baboons receiving xenogeneic livers from wild type and transgenic pigs survive less than 10 days. One of the major issues is the early development of profound thrombocytopenia that results in fatal hemorrhage. Histological examination of xenotransplanted livers has shown baboon platelet activation, phagocytosis and sequestration within the sinusoids. In order to study the mechanisms of platelet consumption in liver xenotransplantation, we have developed an in vitro system to examine the interaction between pig endothelial cells with baboon platelets and to thereby identify molecular mechanisms and therapies. METHODS: Fresh pig hepatocytes, liver sinusoidal and aortic endothelial cells were isolated by collagenase digestion of livers and processing of aortae from GTKO and Gal+ MGH-miniature swine. These primary cell cultures were then tested for the differential ability to induce baboon or pig platelet aggregation. Phagocytosis was evaluated by direct observation of CFSE labeled-platelets, which are incubated with endothelial cells under confocal light microscopy. Aurintricarboxylic acid (GpIb antagonist blocking interactions with von Willebrand factor/vWF, eptifibatide (Gp IIb/IIIa antagonist, and anti-Mac-1 Ab (anti-α(Mβ(2 integrin Ab were tested for the ability to inhibit phagocytosis. RESULTS: None of the pig cells induced aggregation or phagocytosis of porcine platelets. However, pig hepatocytes, liver sinusoidal and aortic endothelial cells (GTKO and Gal+ all induced moderate aggregation of baboon platelets. Importantly, pig liver sinusoidal endothelial cells efficiently phagocytosed baboon platelets, while pig aortic endothelial cells and hepatocytes had minimal effects on platelet numbers. Anti-MAC-1 Ab, aurintricarboxylic acid or eptifibatide, significantly decreased baboon platelet phagocytosis by pig liver endothelial cells (P<0.01. CONCLUSIONS: Although pig hepatocytes and aortic endothelial cells directly caused

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

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    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

  2. Myeloperoxidase modulates human platelet aggregation via actin cytoskeleton reorganization and store-operated calcium entry

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    Irina V. Gorudko

    2013-07-01

    Myeloperoxidase (MPO is a heme-containing enzyme released from activated leukocytes into the extracellular space during inflammation. Its main function is the production of hypohalous acids that are potent oxidants. MPO can also modulate cell signaling and inflammatory responses independently of its enzymatic activity. Because MPO is regarded as an important risk factor for cardiovascular diseases associated with increased platelet activity, we studied the effects of MPO on human platelet functional properties. Laser scanning confocal microscopy was used to reveal carbohydrate-independent MPO binding to human platelet membrane. Adding MPO to platelets did not activate their aggregation under basal conditions (without agonist. In contrast, MPO augmented agonist-induced platelet aggregation, which was not prevented by MPO enzymatic activity inhibitors. It was found that exposure of platelets to MPO leads to actin cytoskeleton reorganization and an increase in their elasticity. Furthermore, MPO evoked a rise in cytosolic Ca2+ through enhancement of store-operated Ca2+ entry (SOCE. Together, these findings indicate that MPO is not a direct agonist but rather a mediator that binds to human platelets, induces actin cytoskeleton reorganization and affects the mechanical stiffness of human platelets, resulting in potentiating SOCE and agonist-induced human platelet aggregation. Therefore, an increased activity of platelets in vascular disease can, at least partly, be provided by MPO elevated concentrations.

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

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    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.

  4. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

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    Navdaev, Alexey; Subramanian, Hariharan; 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.

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

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    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.

  6. Propranolol modifies platelet serotonergic mechanisms in rats.

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    Zółtowski, R; Pawlak, R; Matys, T; Pietraszek, M; Buczko, W

    2002-06-01

    Though the mechanisms for the vascular actions of vasodilatory beta-blockers are mostly determined, some of their interactions with monoaminergic systems are not elucidated. Because there are evidences supporting a possible involvement of serotonin (5-HT) in the actions of beta-blockers, we studied the effect of propranolol on peripheral serotonergic mechanisms in normotensive and Goldblatt two-kidney - one clip (2K1C) hypertensive rats. In both groups of animals propranolol decreased systolic blood pressure, significantly increased whole blood serotonin concentration and at the same time it decreased platelet serotonin level. The uptake of the amine by platelets from hypertensive animals was lower than that of normotensive animals and it was decreased by propranolol only in the latter. In both groups propranolol inhibited potentiation of ADP-induced platelet aggregation by serotonin. In conclusion, this study provides evidence that propranolol modifies platelet serotonergic mechanisms in normotensive and renal hypertensive rats.

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

    Science.gov (United States)

    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 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.

  8. The effect of different strains of Helicobacter pylori on platelet aggregation

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    Paul A Corcoran

    2007-01-01

    Full Text Available BACKGROUND AND AIMS: Helicobacter pylori is the major causative agent in peptic ulcer disease and is strongly implicated in the development of gastric cancer. It has also been linked, less strongly, to cardiovascular disease. The mechanisms by which certain strains of H pylori induce platelet aggregation through interactions with platelet glycoprotein Ib have been previously described.

  9. [Studies of platelet aggregation in six cases of EDTA-dependent pseudothrombocytopenia].

    Science.gov (United States)

    Shimasaki, A; Kato, T; Ozaki, Y

    1994-06-01

    Peripheral blood count was performed by a Coulter Model S Plus STKR on six pseudothrombocytopenia patients (age: 16-70, 2 men and 4 women) using three different anticoagulants. Treatment with ethylene diamine tetraacetate (EDTA, 1 mg/ml) or sodium heparin (25 U/ml) aggregated platelets, but sodium citrate (3.8%, 1:9) had no effect. Smear examination revealed much platelet clumping but the satellite phenomenon was not present. No specific pattern was elucidated concerning cell size distribution curves between treatment by EDTA and heparin. Theophylline (10 mg/ml) and prostaglandin I2 (1 microM) inhibited EDTA-induced platelet aggregation but aspirin (1.8 mM) did not. On the other hand, these three substances inhibited heparin-induced platelet aggregation. These findings, taken together, suggested that EDTA and heparin initiated platelet activation and EDTA-induced platelet aggregation might be a process unrelated to thromboxane A2 production. Heparin may not be a suitable anticoagulant since it aggregates platelets of some healthy individuals.

  10. RANDOMIZED DOUBLE BLIND COMPARISON OF TWO BRANDS OF CLOPIDOGREL IN INHIBITION OF PLATELET AGGREGATION

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    Hikmatullah Jan

    2010-10-01

    Full Text Available Objectives: To compare the anti platelet effects of locally manufactured clopidogrel with the anti platelet effect of clopidogrel manufactured by multinational pharmaceutical abroad. Methodology: A total of 118 subjects were enrolled, 18 to 65 years of age, who presented with suspected ischemic heart disease and were randomly assigned to receive either drug A (Pidogrel or drug B (Plavix in a double blind manner for 7 days. Platelet aggregation was measured in both the groups at baseline and at final visit. Results: Base line platelet aggregability in both drug groups was not significantly different (p=0.317 Mean reduction in platelet aggregation by drug-A was 8.47+/- 0.45 ohms (p<0.001 and mean reduction in platelet aggregation by drug-B was 8.62+/- 0.46 (p<0.001. The difference in platelet aggregability at day 7(follow up between the two groups was not statistically significant i.e., was the same. Conclusion: Locally manufactured clopidogrel is equally effective as that manufactured by the multinational company abroad giving us the added advantage of cost effectiveness

  11. Cilostazol inhibits accumulation of triglyceride in aorta and platelet aggregation in cholesterol-fed rabbits.

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    Hideki Ito

    Full Text Available 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.

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

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    Francis J Castellino

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

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

    Science.gov (United States)

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

    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.

  14. Duration of exposure to high fluid shear stress is critical in shear-induced platelet activation-aggregation.

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    Zhang, Jian-ning; Bergeron, Angela L; Yu, Qinghua; Sun, Carol; McBride, Latresha; Bray, Paul F; Dong, Jing-fei

    2003-10-01

    Platelet functions are increasingly measured under flow conditions to account for blood hydrodynamic effects. Typically, these studies involve exposing platelets to high shear stress for periods significantly longer than would occur in vivo. In the current study, we demonstrate that the platelet response to high shear depends on the duration of shear exposure. In response to a 100 dyn/cm2 shear stress for periods less than 10-20 sec, platelets in PRP or washed platelets were aggregated, but minimally activated as demonstrated by P-selectin expression and binding of the activation-dependent alphaIIbbeta3 antibody PAC-1 to sheared platelets. Furthermore, platelet aggregation under such short pulses of high shear was subjected to rapid disaggregation. The disaggregated platelets could be re-aggregated by ADP in a pattern similar to unsheared platelets. In comparison, platelets that are exposed to high shear for longer than 20 sec are activated and aggregated irreversibly. In contrast, platelet activation and aggregation were significantly greater in whole blood with significantly less disaggregation. The enhancement is likely via increased collision frequency of platelet-platelet interaction and duration of platelet-platelet association due to high cell density. It may also be attributed to the ADP release from other cells such as red blood cells because increased platelet aggregation in whole blood was partially inhibited by ADP blockage. These studies demonstrate that platelets have a higher threshold for shear stress than previously believed. In a pathologically relevant timeframe, high shear alone is likely to be insufficient in inducing platelet activation and aggregation, but acts synergistically with other stimuli.

  15. Comparative Effects of α-, β-, and γ-Carbolines on Platelet Aggregation and Lipid Membranes

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    Hironori Tsuchiya

    2011-01-01

    Full Text Available Cigarette smoking and alcohol consumption possibly affect platelet functions. To verify the hypothesis that some α-, β-, and γ-carboline components in cigarette smoke and alcoholic beverages may change platelet aggregability, their effects on human platelets were determined by aggregometry together with investigating their membrane effects by turbidimetry. Carbolines inhibited platelet aggregation induced by five agents with the potency being 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole > 3-amino-1-methyl-5H-pyrido[4,3-b]indole > 1-methyl-9H-pyrido[3,4-b]indole. The most potent 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole showed 50% aggregation-inhibitory concentrations of 6–172 μM. Both γ-carbolines interacted with phosphatidylcholine membranes to lower the lipid phase transition temperature with the potency correlating to the antiplatelet activity, suggesting that the interaction with platelet membranes to increase their fluidity underlies antiplatelet effects. Given their possible concentration and accumulation in platelets, γ- and β-carbolines would provide cigarette smokers and alcohol drinkers with reduced platelet aggregability, and they may be responsible for the occurrence of hemorrhagic diseases associated with heavy smoking and alcoholics.

  16. Comparison of cytotoxic and anti-platelet activities of polyphenolic extracts from Arnica montana flowers and Juglans regia husks.

    Science.gov (United States)

    Rywaniak, Joanna; Luzak, Boguslawa; Podsedek, Anna; Dudzinska, Dominika; Rozalski, Marcin; Watala, Cezary

    2015-01-01

    Polyphenolic compounds of plant origin are well known to be beneficial to human health: they exert protective effects on haemostasis and have a particular influence on blood platelets. However, the anti-platelet properties of polyphenolic compounds observed so far have not been weighed against their potential cytotoxic action against platelets. The aim of this study was to demonstrate that anti-platelet and cytotoxic effects on blood platelets may interfere and therefore, may often lead to confusion when evaluating the properties of plant extracts or other agents towards blood platelets. The anti-platelet and cytotoxic in vitro effects of plant extracts obtained from the husks of walnuts (J. regia) and flowers of arnica (A. montana) on platelet reactivity and viability were examined. Platelet function was assessed using standard methods (flow cytometry: P-selectin expression, activation of GPIIbIIIa complex, vasodilator-stimulated phosphoprotein, VASP index; turbidimetric and impedance aggregometry) and newly set assays (flow cytometric monitoring of platelet cytotoxicity). The results reveal that none of the studied plant extracts demonstrated cytotoxicity towards blood platelets. The phenolic acid-rich extract of A. montana (7.5 and 15 µg/ml) significantly reduced the ADP-induced aggregation in both whole blood and PRP, and decreased the platelet reactivity index (PRI; VASP phosphorylation) in whole blood, while showing excellent antioxidant capacity. The extract of J. regia husks significantly reduced ADP-induced platelet aggregation in whole blood when applied at 7.5 µg/ml, and only slightly decreased the PRI at 15 µg/ml. Both examined extracts suppressed platelet hyper-reactivity, and such influence did not interfere with cytotoxic effects of the extracts. Thus, its high polyphenol content, excellent antioxidant capacity and distinct anti-platelet properties, in combination with its lack of toxicity, make the extract of A. montana flowers a possible

  17. Bacillus pasteurii urease shares with plant ureases the ability to induce aggregation of blood platelets.

    Science.gov (United States)

    Olivera-Severo, D; Wassermann, G E; Carlini, C R

    2006-08-15

    Ureases (EC 3.5.1.5) are highly homologous enzymes found in plants, bacteria and fungi. Canatoxin, an isoform Canavalia ensiformis urease, has several biological properties unrelated to its ureolytic activity, like platelet-aggregating and pro-inflammatory effects. Here, we describe that Bacillus pasteurii urease (BPU) also induces aggregation of rabbit platelets, similar to the canatoxin-induced effect (ED(50) 0.4 and 0.015 mg/mL, respectively). BPU induced-aggregation was blocked in platelets pretreated with dexamethasone and esculetin, a phospholipase A(2) and a lipoxygenase inhibitor, respectively, while platelets treated with indomethacin, a cyclooxygenase inhibitor, showed increased response to BPU. Methoxyverapamil (Ca(2+) channel blocker) and AMP (ADP antagonist) abrogated urease-induced aggregation, whereas the PAF-acether antagonist Web2170 had no effect. We concluded that platelet aggregation induced by BPU is mediated by lipoxygenase-derived eicosanoids and secretion of ADP from the platelets through a calcium-dependent mechanism. Potential relevance of these findings for bacterium-plant interactions and pathogenesis of bacterial infections are discussed.

  18. Platelet aggregation measurement for assessment of hemostasis failure mechanisms in patients with gastroduodenal ulcer bleeding

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    Barinov E

    2013-08-01

    Full Text Available Edward Barinov,1 Oksana Sulaieva,1 Yuriy Lyakch,2 Vitaliy Guryanov,2 Petr Kondratenko,3 Yevgeniy Radenko3 1Department of Histology, Cytology, and Embryology, 2Department of Medical, Biological Physics, Medical Informatics, and Biostatistics, 3Department of Surgery and Endoscopy, M Gorky Donetsk National Medical University, Donetsk, Ukraine Background: The purpose of this study was to identify factors associated with the risk of unsustainable hemostasis in patients with gastric and duodenal ulcer bleeding by in vitro assessment of platelet reactivity using artificial neural networks. Methods: Patients with gastroduodenal ulcers complicated by bleeding were studied. Platelet aggregation was measured using aggregometry with adenosine diphosphate 5 µM, epinephrine 2.5 µM, 5-hydroxytryptophan 10 µM, collagen 1 µM, and thrombin 0.06 NIH Unit/mL as agonists. Multiple logistic regression was used to evaluate the independent relationship between demographic, clinical, endoscopic, and laboratory data and in vitro assessment of platelet reactivity and local parameters of hemostasis in patients with ulcer bleeding. Results: Analysis of platelet aggregation in patients with gastroduodenal ulcer bleeding allowed the variability of platelet response to different agonists used in effective concentration which induces 50% platelet aggregation (EC50 to be established. The relationship between platelet aggregation and the spatial-temporal characteristics of ulcers complicated by bleeding was demonstrated. Adrenoreactivity of platelets was associated with time elapsed since the start of ulcer bleeding and degree of hemorrhage. The lowest platelet response to collagen and thrombin was detected in patients with active bleeding (P< 0.001 and unsustainable recent bleeding (P < 0.01. Decreased adenosine diphosphate-induced platelet aggregation in patients with ulcer bleeding was correlated with the platelet response to thrombin (r = 0.714, P < 0.001 and collagen (r

  19. Inhibitory effect of GBH on platelet aggregation through inhibition of intracellular Ca2+ mobilization in activated human platelets.

    Science.gov (United States)

    Park, Won-Hwan; Kim, Han-Kyu; Nam, Kyung-Soo; Shon, Yun-Hee; Jeon, Byung Hun; Moon, Sung-Kwon; Kim, Min-Gon; Kim, Cheorl-Ho

    2004-11-05

    Geiji-Bokryung-Hwan (GBH) was studied on antiplatelet activity in human platelet suspensions. GBH consists of the 5 herbs Cinnamomi Ramulus, Poria Cocos, Mountan Cortex Radicis, Paeoniae Radix, and Persicae Semen, which have been used in herbal medicine for thousands of years for atherosclerosis. The mechanism involved in the antiplatelet activity of GBH in human platelet suspensions was investigated. GBH inhibited platelet aggregation and Ca2+ mobilization in a concentration-dependent manner without increasing intracellular cyclic AMP and cyclic GMP. GBH had no inhibitory effect on thromboxane B2 (TXB2) production in cell-free systems. Collagen-related peptide (CRP)-induced Ca2+ mobilization is regulated by phospholipase C-2 (PLC-gamma2) activation. We evaluated the effect of GBH on tyrosine phosphorylation of PLC-gamma2 and the production of inositol-1,4,5-trisphosphate (IP3). GBH at concentrations that inhibited platelet aggregation and Ca2+ mobilization had no effects on tyrosine phosphorylation of PLC-gamma2 or on the formation of IP3 induced by CRP. Similar results were obtained with thrombin-induced platelet activation. GBH inhibited platelet aggregation and Ca2+ mobilization induced by thrombin without affecting the production of IP3. We then evaluated the effect of GBH on the binding of IP3 to its receptor. GBH at high concentrations partially blocked the binding of IP3 to its receptor. Therefore, the results suggested that GBH suppresses Ca2+ mobilization at a step distal to IP3 formation. GBH may provide a good tool for investigating Ca2+ mobilization.

  20. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    Science.gov (United States)

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

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

    Directory of Open Access Journals (Sweden)

    Wolfgang Marx

    Full Text Available 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.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.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.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.The evidence that ginger affects platelet aggregation and coagulation is equivocal and further study is needed to definitively address this question.

  2. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

    Directory of Open Access Journals (Sweden)

    Alexey Navdaev

    Full Text Available 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.

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

    Science.gov (United States)

    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

  4. Platelet Reactivity Is Independent of Left Atrial Wall Deformation in Patients with Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Nathan Procter

    2016-01-01

    Full Text Available It has been documented recently that left atrial (LA deformation in AF patients (while in AF is predictive of subsequent stroke risk. Additionally, diminished LA deformation during AF correlates with the presence of LA blood stasis. Given that endothelial function is dependent on laminar blood flow, the present study sought to investigate the effect of diminished LA deformation (during AF on platelet reactivity and inflammation in AF patients. Patients (n=17 hospitalised with AF underwent echocardiography (while in AF for determination of peak positive LA strain (LASp. Whole blood impedance aggregometry was used to measure extent of ADP-induced aggregation and subsequent inhibitory response to the nitric oxide (NO donor, sodium nitroprusside. Platelet thioredoxin-interacting protein (Txnip content was determined by immunohistochemistry. LASp tended (p=0.078 to vary inversely with CHA2DS2VASc scores. However, mediators of inflammation (C-reactive protein, Txnip did not correlate significantly with LASp nor did extent of ADP-induced platelet aggregation or platelet NO response. These results suggest that the thrombogenic risk associated with LA stasis is independent of secondary effects on platelet aggregability or inflammation.

  5. Inhibitory effects of yuzu and its components on human platelet aggregation.

    Science.gov (United States)

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

    2015-03-01

    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.

  6. Prolactin does not affect human platelet aggregation or secretion

    NARCIS (Netherlands)

    Reuwer, A.Q.; Nieuwland, R.; Fernandez, I.; Goffin, V.; van Tiel, C.M.; Schaap, M.C.L.; Berckmans, R.J.; Kastelein, J.J.P.; Twickler, M.T.B.

    2009-01-01

    Platelets play an important role in the development of plaque formation and in the events after rupture of the atherosclerotic plaque, leading to atherothrombosis. Multiple hormones, either in excess or when deficient, are involved in the development of atherothrombotic disease, but, to which extent

  7. Glycoprotein IIb/IIIa and P2Y12 Induction by Oligochitosan Accelerates Platelet Aggregation

    Science.gov (United States)

    Halim, Ahmad Sukari; Hussein, Abdul Rahim; Ujang, Zanariah

    2014-01-01

    Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro. PMID:25247182

  8. Generation of Anti-platelet Autoantibody During Dengue Virus Infection

    Directory of Open Access Journals (Sweden)

    Huan-Yao Lei

    2008-01-01

    Full Text Available Dengue virus infection causes dengue fever, Dengue Hemorrhagic Fever (DHF and Dengue Shock Syndrome (DSS. Thrombocytopenia is common in dengue fever and is always found in DHF/DSS. The pathogenesis of thrombocytopenia is poorly understood. To further understand the relationship between anti-dengue virus antibody and anti-platelet antibody, we generated monoclonal anti-dengue virus antibodies from the dengue virus infected mice that developed transient thrombocytopenia post dengue infection. The analysis of a panel of monoclonal anti-NS-1 antibodies reveals three different patterns of platelet binding: strong, intermediate, or dull. Their isotypes are different, some are IgM while others are IgG1. Most of anti-platelet antibodies are cross-reactive with NS-1 of dengue virus and can be competitively inhibited by recombinant NS-1 protein, suggesting a molecular mimicry between dengue virus NS-1 protein and platelet. A clone, 13-F4-G5, preferentially bound activated platelets, can recognize two or three proteins around 150 kD on platelets. The binding to platelet would lyse the platelet in the presence of complement or enhance the ADP-induced platelet aggregation. Furthermore, some of these monoclonal antibodies would also react with the cellular antigens of BHK. Based on the data, we conclude that dengue virus infection induces auto anti-platelet antibodies which thereafter may involve in the manifestation of thrombocytopenia. A molecular mimicry between NS-1 and platelet is demonstrated.

  9. Determination of serum aluminum, platelet aggregation and lipid peroxidation in hemodialyzed patients

    Directory of Open Access Journals (Sweden)

    T.J.C. Neiva

    2002-03-01

    Full Text Available Aluminum (Al3+ overload is frequently associated with lipid peroxidation and neurological disorders. Aluminum accumulation is also reported to be related to renal impairment, anemia and other clinical complications in hemodialysis patients. The aim of the present study was to determine the degree of lipid peroxidation, platelet aggregation and serum aluminum in patients receiving regular hemodialytic treatment. The level of plasma lipid peroxidation was evaluated on the basis of thiobarbituric acid reactive substances (TBARS. Mean platelet peroxidation in patients undergoing hemodialysis was significantly higher than in normal controls (2.7 ± 0.03 vs 1.8 ± 0.06 nmol/l, P<0.05. Platelet aggregation and serum aluminum levels were determined by a turbidimetric method and atomic absorption spectrophotometry, respectively. Serum aluminum was significantly higher in patients than in normal controls (44.5 ± 29 vs 10.8 ± 2.5 µg/l, P<0.05. Human blood platelets were stimulated with collagen (2.2 µg/ml, adenosine diphosphate (6 µM and epinephrine (6 µM and showed reduced function with the three agonists utilized. No correlation between aluminum levels and platelet aggregation or between aluminum and peroxidation was observed in hemodialyzed patients.

  10. Plasma pharmacological study on Da Huang Zhe Chong capsule on platelet aggregation of normal person

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-sheng; CHEN Fang-ping; XIAO Chang-jiang; HE Shi-lin; FU Bin; LI Xin; CAO Xing-yu; CHEN Yan; XIE Qin-zhi

    2005-01-01

    Objective To develop a plasma pharmacological method evaluates the effect of Da Huang Zhe Chong capsule on platelet aggregation and its mechanism, which is a representative Traditional Chinese Medicine Patent Prescription Promoting blood circulation by removing blood stasis. Methods Platelets specimens from healthy volunteers made serum and plasma with medicine, while platelet PRP were separated, which were divided into 8groups,i.e. auto-serum, allo-serum, serum with Da Huang Zhe Chong capsule , serum with aspirin, auto-plasma, plasma with Da Huang Zhe Chong capsule, plasma with aspirin, every group added to serum and plasma to hatch. After ADP and adrenalin were added into the specimens and hatched, the effects of specimens on platelet aggregation were observed. Results After ADP adrenalin were added, all the serum groups did not present platelet aggregation,while all the plasma group presented platelet aggregation. P1, P5, Pmax, t and TM have no significant difference (P>0. 05) between auto-plasma group and allo-plasma group induced by ADP and adrenalin. P1, P5, t and Pmax have significant differences (P<0. 01) and TM decreased significantly (P<0. 05) comparing plasma group with Da Huang Zhe Chong capsule and plasma group of aspirin to allo-plasma group. P1, t and Pmax have significant difference (P<0.05), and P5 and TM are simulate comparing plasma group with Da Huang Zhe Chong capsule to plasma group of aspirin. P1, P5, t and Pmax have significant differences (P<0. 01), P1, TM have also significant(P<0. 05), comparing plasma group of Da Huang Zhe Chong capsule with plasma of aspirin to allo-plasma group induced by adrenalin. P1 ,P5 and Pmax have significant differences (P<0.05), and t and Pmax are simulate comparing plasma group with Da Huang Zhe Chong capsule with plasma group of aspirin. Conclusion The serum pharmacological study is inappropriate to study platelet aggregation in vitro. The plasma pharmacological study is inappropriate to study

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

    Science.gov (United States)

    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.

  12. The clinical usefulness of the platelet aggregation test for the diagnosis of heparin-induced thrombocytopenia

    NARCIS (Netherlands)

    Chong, B H; Burgess, J; Ismail, F

    1993-01-01

    The platelet aggregation test is widely used for the diagnosis of heparin-induced thrombocytopenia (HIT), a potentially serious complication of heparin therapy. We have evaluated its sensitivity and specificity in comparison with those of the 14C-serotonin release test. The sensitivity of the platel

  13. Dauricoside, a new glycosidal alkaloid having an inhibitory activity against blood-platelet aggregation.

    Science.gov (United States)

    Hu, S M; Xu, S X; Yao, X S; Cui, C B; Tezuka, Y; Kikuchi, T

    1993-10-01

    Dauricoside (1), a new glycosidal alkaloid, was isolated from the rhizomes of Menispermum dauricum DC. along with dauricine (2), daurisoline (3), dauriporphine (4), menisporphine (5), and 6-O-demethylmenisporphine (6), and its structure was determined by means of spectroscopic methods. Compounds 1, 2, and 3 inhibited blood-platelet aggregation induced by adenosine 5'-diphosphate (ADP).

  14. Effects of heparin on platelet aggregation and release and thromboxane A2 production

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad, S.F.; Anderson, W.H.; Smith, J.B.; Chuang, H.Y.; Mason, R.G.

    1981-08-01

    Heparin, when added to citrated platelet-rich plasma (PRP), caused potentiation of platelet aggregation and the release reaction induced by the aggregating agents adenosine diphosphate (ADP), arachidonic acid, collagen, and epinephrine. At low concentrations (4.7 x 10(-5) M) arachidonic acid failed to cause aggregation of platelets in citrated PRP. However, in the presence of heparin, the same concentration of arachidonic acid caused aggregation. Examination of PRP for the presence of thromboxane A2 (TxA2) by use of a bioassay revealed that heparin also stimulated release of TxA2. This finding indicated that platelets released more TxA2 when they were challenged by low concentrations of arachidonic acid in the presence of heparin than in its absence. Platelets were labeled with /sup 3/H-arachidonic acid and /sup 14/C-serotonin, and attempts were made to determine whether heparin stimulated the platelet release reaction first with subsequent increased production of TxA2, or alternatively, whether heparin stimulated TxA2 production first with subsequent enhancement of the release reaction. In view of the demonstrated simultaneous release of /sup 14/C-serotonin and /sup 3/H-arachidonic acid metabolites, it appeared that either release of /sup 14/C and /sup 3/H occurs concurrently or, even if one of these events is dependent on the other, both events take place in rapid succession. Timed sequential studies revealed that in the presence of arachidonic acid, the addition of heparin hastened the apparently simultaneous release of both /sup 14/C and /sup 3/H.

  15. Research Influence Biological Active Agents in the Course of Regulation of Functional Activity of Platelets and System of a Haemostasis

    Directory of Open Access Journals (Sweden)

    Nozim N. Khoshimov

    2015-06-01

    Full Text Available It is shown that the flavonoid pulikarin suppresses activity of an adenylate cyclase and reduces level intracellular [Ca2+], perhaps its effect is connected with inhibition of a gain of cytoplasmatic Ca2+ as at the expense of its entrance outside, and release from intracellular storages. Perhaps, oppression of fluorescence of membrane-bound Ca2+ is connected with inhibition of a pulikarin of release of calcium from intracellular depots. The inhibiting effect of a pulikarin on ADP-induced aggregation of platelets is connected with oppression of a gain of cytoplasmatic concentration of Ca2+ from depot of platelets.

  16. Iron-induced platelet aggregation measurement : a novel method to measure platelet function in stenting for ST segment elevation myocardial infarction

    NARCIS (Netherlands)

    Smit, J. J. J.; van Oeveren, W.; Ottervanger, J. P.; Slingerland, R. J.; Remijn, J. A.; Zijlstra, F.; van 't Hof, A. W. J.

    2009-01-01

    Iron and (stainless) steel are potent platelet aggregation activators, and may be involved in stent thrombosis, a serious complication after intracoronary stenting. Current platelet function tests are suboptimal, because of inappropriate agonists and/or lack of reproducibility. We tested the feasibi

  17. Effect of dietary copper on platelet volume and aggregation in men

    Energy Technology Data Exchange (ETDEWEB)

    Milne, D.B.; Gallagher, S.K. (Dept. of Agriculture, Grand Forks, ND (United States))

    1991-03-15

    A study conducted in the authors' laboratory indicated that mean platelet (PLT) volume (MPV) in rats was affected by dietary copper. They suggested that PLT aggregation may also be affected. Ten men aged 19 to 39 yrs, who lived in a metabolic unit, participated in a study that was divided into four six-week dietary periods in a 2 {times} 2 factorial design with 0.65 and 2.65 mg Cu/d and 0.75 and 2.75 g cystine/d as variables. Plasma copper was not significantly affected by the dietary manipulations, but enzymatically measured ceruloplasmin (Cp) was significantly depressed during low copper intake. Maximum 5 {mu}M ADP-stimulated PLT aggregation in platelet rich plasma was significantly greater during low copper intake than during high Cu intake. Total platelet count and collagen or epinephrine stimulated PLT aggregation were not significantly affected by dietary treatment. Four men who responded to low copper intake with elevated serum cholesterol and depressed specific activity of Cp had significantly elevated MPV and maximum ADP-stimulated PLT aggregation during low Cu intake. The other six men exhibited only increased PLT aggregation during only the low copper, low cystine dietary period. These data indicate that dietary copper is a factor in PLT function in humans.

  18. Low-dose aspirin (ASA) renders human platelets more vulnerable to inhibition of aggregation by prostacyclin (PGI2).

    Science.gov (United States)

    Philp, R B; Paul, M L

    1983-06-01

    Pre-treatment of human, platelet-rich plasma with concentrations of aspirin that produced 50% or less inhibition of aggregation induced by collagen, arachidonic acid or adenosine diphosphate, significantly increased the % inhibition of platelet aggregation by a low concentration of authentic prostacyclin or by prostacyclin-like activity generated by incubation of rat aorta rings in human platelet-poor plasma. Similarly a single aspirin tablet (325 mg) taken orally by human volunteers significantly increased the sensitivity of their platelets to inhibition of aggregation by authentic prostacyclin (8.1 X 10(-10) M) for 2-48 h after ingestion. Statistical significance was lost at 72 h but the trend was still evident. These results support the contention that low doses of aspirin may be efficacious in the therapy of arterial thromboembolism since this could preserve some arterial prostacyclin-generating activity which might be sufficient to inhibit adhesion and aggregation of the aspirin-treated platelets.

  19. C-phycocyanin, a very potent and novel platelet aggregation inhibitor from Spirulina platensis.

    Science.gov (United States)

    Hsiao, George; Chou, Po-Hsiu; Shen, Ming-Yi; Chou, Duen-Suey; Lin, Chien-Huang; Sheu, Joen-Rong

    2005-10-05

    The aim of this study was to systematically examine the inhibitory mechanisms of C-phycocyanin (C-PC), one of the major phycobiliproteins of Spirulina platensis (a blue-green alga), in platelet activation. In this study, C-PC concentration-dependently (0.5-10 nM) inhibited platelet aggregation stimulated by agonists. C-PC (4 and 8 nM) inhibited intracellular Ca2+ mobilization and thromboxane A2 formation but not phosphoinositide breakdown stimulated by collagen (1 microg/mL) in human platelets. In addition, C-PC (4 and 8 nM) markedly increased levels of cyclic GMP and cyclic GMP-induced vasodilator-stimulated phosphoprotein (VASP) Ser(157) phosphorylation. Rapid phosphorylation of a platelet protein of Mw 47,000 (P47), a marker of protein kinase C activation, was triggered by phorbol-12,13-dibutyrate (150 nM). This phosphorylation was markedly inhibited by C-PC (4 and 8 nM). In addition, C-PC (4 and 8 nM) markedly reduced the electron spin resonance (ESR) signal intensity of hydroxyl radicals in collagen (1 microg/mL)-activated platelets. The present study reports on a novel and very potent (in nanomolar concentrations) antiplatelet agent, C-PC, which is involved in the following inhibitory pathways: (1) C-phycocyanin increases cyclic GMP/VASP Ser157 phosphorylation and subsequently inhibits protein kinase C activity, resulting in inhibition of both P47 phosphorylation and intracellular Ca2+ mobilization, and (2) C-PC may inhibit free radicals (such as hydroxyl radicals) released from activated platelets, which ultimately inhibits platelet aggregation. These results strongly indicate that C-PC appears to represent a novel and potential antiplatelet agent for treatment of arterial thromboembolism.

  20. CONGESTIVE HEART FAILURE IN DOGS IS ASSOCIATED WITH INCREASED PLATELET LEUKOCYTE AGGREGATION MEASURED BY FLOW CYTOMETRY

    DEFF Research Database (Denmark)

    Tarnow, Inge; Andreasen, Susanne SH; Olsen, Lisbeth Høier

    2010-01-01

    CONGESTIVE HEART FAILURE IN DOGS IS ASSOCIATED WITH ENHANCED PLATELET-LEUKOCYTE AGGREGATES - A MARKER FOR PLATELET ACTIVATION. I Tarnow1, LH Olsen2, SHS Andreasen2, SG Moesgaard2, CE Rasmussen2, AT Kristensen1, T Falk2. 1Departments of Small Animal Clinical Sciences and 2Animal and Veterinary Basic...... Sciences, Faculty of Life Science, University of Copenhagen, Denmark. Chronic congestive heart failure (CHF) in humans is associated with abnormal hemostasis, and changes in hemostatic biomarkers carry a poor prognosis. CHF in dogs has been associated with plasma markers of hypercoagulability, however...

  1. Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets.

    Science.gov (United States)

    Ehrlich, Daniela; Humpel, Christian

    2014-01-01

    It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

  2. Suppression of Aggrus/podoplanin-induced platelet aggregation and pulmonary metastasis by a single-chain antibody variable region fragment.

    Science.gov (United States)

    Miyata, Kenichi; Takagi, Satoshi; Sato, Shigeo; Morioka, Hiroshi; Shiba, Kiyotaka; Minamisawa, Tamiko; Takami, Miho; Fujita, Naoya

    2014-12-01

    Almost all highly metastatic tumor cells possess high platelet aggregating abilities, thereby form large tumor cell-platelet aggregates in the microvasculature. Embolization of tumor cells in the microvasculature is considered to be the first step in metastasis to distant organs. We previously identified the platelet aggregation-inducing factor expressed on the surfaces of highly metastatic tumor cells and named as Aggrus. Aggrus was observed to be identical to the marker protein podoplanin (alternative names, T1α, OTS-8, and others). Aggrus is frequently overexpressed in several types of tumors and enhances platelet aggregation by interacting with the platelet receptor C-type lectin-like receptor 2 (CLEC-2). Here, we generated a novel single-chain antibody variable region fragment (scFv) by linking the variable regions of heavy and light chains of the neutralizing anti-human Aggrus monoclonal antibody MS-1 with a flexible peptide linker. Unfortunately, the generated KM10 scFv failed to suppress Aggrus-induced platelet aggregation in vitro. Therefore, we performed phage display screening and finally obtained a high-affinity scFv, K-11. K-11 scFv was able to suppress Aggrus-induced platelet aggregation in vitro. Moreover, K-11 scFv prevented the formation of pulmonary metastasis in vivo. These results suggest that K-11 scFv may be useful as metastasis inhibitory scFv and is expected to aid in the development of preclinical and clinical examinations of Aggrus-targeted cancer therapies.

  3. Analysis of anti-platelet aggregation components of Rhizoma Zingiberis using chicken thrombocyte extract and high performance liquid chromatography

    Institute of Scientific and Technical Information of China (English)

    NIE Hong; MENG Lan-zhen; ZHANG Hui; ZHANG Jian-yu; YIN Zhen; HUANG Xue-song

    2008-01-01

    Background The conventional procedure for screening bioactive components from traditional Chinese medicine is time-consuming,expensive and low efficient.Therefore,some alternative strategies are needed urgently.A novel method for screening anti-platelet aggregation components from oleoresins was developed using chicken thrombocyte extract and high performance liquid chromatography.Methods The anti-platelet aggregation components of oleoresins were combined with receptors,channels and enzymes of chicken thrombocytes under physiological environment.Unbound substances were washed away and bound compounds were eluted using specific phosphate buffered solution(PBS).Compounds released from target sites were collected and analyzed by high performance liquid chromatography and LC-MS.The activity of three compounds which were screened from this model was confirmed using platelet aggregation pharmacology in vivo.Results There were four typical compounds that bound to the thrombocytes:6-gingerol,8-gingerol,6-shogaol and 10-gingerol,and all had shown anti-platelet aggregation activities.Eight-gingerol displayed the best anti-platelet aggregation effect.Conclusions Chicken thromobcyte extract can be used to isolate chemicals that are ligands of the receptor or other bio-targets on the platelet.This may therefore be a simple and efficient method to screen for anti-platelet aggregation compounds from traditional Chinese medicine.

  4. Calprotectin and platelet aggregation in patients with stable coronary artery disease.

    Directory of Open Access Journals (Sweden)

    Sanne Bøjet Larsen

    Full Text Available Recent studies suggest that the inflammation-associated protein calprotectin may be implicated in the pathogenesis of coronary artery disease (CAD. However, the impact of calprotectin levels on platelet aggregation in CAD patients has never been investigated.We investigated the association between calprotectin levels and platelet aggregation in stable, high-risk CAD patients receiving aspirin as mono antiplatelet therapy. Furthermore, we aimed to investigate independent clinical and laboratory determinants of calprotectin levels.We performed a cross-sectional study including 581 stable, high-risk CAD patients. All patients received 75 mg aspirin daily as mono antiplatelet therapy. Platelet aggregation was assessed by 1 impedance aggregometry (Multiplate Analyzer using arachidonic acid (AA and collagen as agonists and by 2 the VerifyNow Aspirin Assay. Low-grade inflammation was evaluated by calprotectin, high-sensitive C-reactive-protein (hs-CRP and interleukin-6. Platelet activation was assessed by soluble P-selectin, and cyclooxygenase-1 inhibition was evaluated by serum thromboxane B2, both measured by ELISA.Calprotectin levels correlated positively with platelet aggregation according to Multiplate Analyzer (r=0.12, p=0.01. Additionally, calprotectin was positively associated with leukocytes (r=0.33, p<0.0001, hs-CRP (r=0.31, p<0.0001, interleukin-6 (r=0.28, p<0.0001, soluble P-selectin (r=0.10, p=0.02 and serum thromboxane B2 (r=0.10, p=0.02. Type 2 diabetes mellitus was an independent predictor of increased calprotectin levels (p=0.004, and trends were seen for body mass index (p=0.06 and smoking (p=0.07. Compliance with aspirin was confirmed by low serum thromboxane B2 levels in all patients (median [25%;75%]: 1.07 [0.52;1.87] ng/mL.Calprotectin levels correlated positively, though weakly, with platelet aggregation and activation as well as serum thromboxane B2 in high-risk, stable CAD patients treated with aspirin.

  5. Protective Mechanisms of Guanosine from Solanum lycopersicum on Agonist-Induced Platelet Activation: Role of sCD40L

    Directory of Open Access Journals (Sweden)

    Iván Palomo

    2013-07-01

    Full Text Available In the past 30 years, only three natural products have been sources of new drugs with antiplatelet activity. In this study, we have demonstrated for the first time that guanosine from Solanum lycopersicum possesses antiplatelet (secretion, spreading, adhesion and aggregation activity in vitro and inhibition of platelet inflammatory mediator of atherosclerosis (sCD40L. According to ADP-induced platelet aggregation inhibiting, the total extract residue was fractionated by liquid chromatography/phase separation, affording an aqueous fraction. This fraction was subjected to repeated permeation over Sephadex LH-20 and semi-preparative TLC. The isolated compound finally obtained was identified as guanosine on the basis of its UV-spectra, HPLC and 1H-NMR data. Guanosine concentration dose-dependently (1 to 4 mmol/L inhibited platelet secretion and aggregation induced by ADP and collagen. Spread of human platelets on collagen in the presence of guanosine was fully inhibited. After incubation of whole blood with guanosine, the platelet adhesion and aggregation under flow conditions was inhibited concentration dependently (0.2 to 2 mmol/L. At the same concentrations that guanosine inhibits platelet aggregation, levels of sCD40L were significantly decreased. Guanosine is thus likely to exert significant protective effects in thromboembolic-related disorders by inhibiting platelet aggregation.

  6. Anti-platelet aggregation triterpene saponins from the galls of Sapindus mukorossi.

    Science.gov (United States)

    Huang, Hui-Chi; Tsai, Wei-Jern; Liaw, Chia-Ching; Wu, Shih-Hsiung; Wu, Yang-Chang; Kuo, Yao-Haur

    2007-09-01

    Bioassay-directed fractionation of an ethanolic extract of the galls of Sapindus mukorossi has resulted in the isolation of two new tirucallane-type triterpenoid saponins, sapinmusaponins Q (1) and R (2), along with three known oleanane-type triterpenoid saponins (3-5). Their structures were elucidated on the basis of spectroscopic analysis and chemical hydrolysis. Biological evaluation showed that both sapinmusaponins Q and R demonstrated more potent anti-platelet aggregation activity than aspirin.

  7. Synthesis of huaicarbon A/B and their activating effects on platelet glycoprotein VI receptor to mediate collagen-induced platelet aggregation

    Science.gov (United States)

    Yu, Hongli; Chen, Yeqing; Wu, Hao; Wang, Kuilong; Liu, Liping; Zhang, Xingde

    2017-01-01

    Quercetin and rhamnose were efficiently converted into huaicarbon A/B by heating at 250°C for 10-15 min or at 200°C for 25-30 min. With the optimum molar ratio of quercetin/rhamnose (1:3), huaicarbon A and B yields reached 25% and 16% respectively after heating at 250°C, with 55% quercetin conversion. Huaicarbon A/B both promoted washed platelet aggregation dose-dependently, which was antagonized by an inhibitor of glycoprotein VI (GPVI) receptor. Similarly, they both promoted collagen-induced platelet aggregation in platelet-rich plasma in dose-dependent manners. According to the S type dose-response model, EC50 values of huaicarbon A and huaicarbon B were calculated as 33.48 μM and 48.73 μM respectively. They induced intracellular Ca2+ accumulation that was specifically blocked by GPVI antagonist. Huaicarbon A/B enhanced intracellular Ca2+ accumulation and facilitated collagen-induced platelet aggregation, which were blocked by GPVI antagonist. They were conducive to collagen-induced platelet aggregation by activating platelet GPVI receptor. PMID:28337278

  8. Response to platelet-activating factor in human platelets stored and aged in plasma. Decrease in aggregation, phosphoinositide turnover, and receptor affinity

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, S.D.; Morrison, W.J.; Klachko, D.M.

    1989-07-01

    Human platelet concentrates were stored in polyolefin bags at 22 to 24 degrees C on a horizontal shaker for up to 8 days. At different intervals, aliquots of platelet-rich plasma (PRP) were removed aseptically and five variables, i.e., platelet counts, morphology, platelet-activating factor (PAF)-stimulated aggregation, phosphoinositide turnover, and (3H)PAF binding to platelet receptors, were studied. The number of platelets did not change during the 8 days of storage. Scanning electron microscopy of the platelets revealed a gradual morphologic change from biconcave flat discs to irregular, crenated forms. The PAF-induced aggregation of platelets declined with time of storage. A decrease to 50 percent of the Day 1 aggregatory response to PAF was evident on Day 2, and there was a further decline to about 20 percent by Day 6. Similarly, PAF receptor-coupled phosphoinositide turnover, as monitored by 32P incorporation into individual phosphoinositides, decreased dramatically with storage. After 2 to 3 days of storage, the phosphoinositide turnover was reduced to 50 percent of the original response, and it continued to decline to about 25 percent of original response by Day 5 or 6. The binding of (3H)PAF to washed human platelets indicated subtle changes between Days 2 and 4, which became more noticeable by Day 6. These results have raised the possibility of changes in the number of the receptors and/or their affinity for the ligand during storage. We conclude that although the number of platelets was maintained during storage for 8 days, a general deterioration of their responses to PAF occurred at the levels of cell surface receptor, transmembrane signaling (phosphoinositide turnover), and response (aggregation).

  9. Aminoglycosides prevent and dissociate the aggregation of platelets in patients with EDTA-dependent pseudothrombocytopenia.

    Science.gov (United States)

    Sakurai, S; Shiojima, I; Tanigawa, T; Nakahara, K

    1997-12-01

    Although EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) is of practical importance because failure to recognize this clinical entity may result in misdiagnosis and subsequent mismanagement of the patients, the pathophysiological nature of EDTA-PTCP remains unknown. To develop an effective way to evaluate the platelet counts in patients with EDTA-PTCP, we introduced aminoglycosides-supplemented anticoagulating agents. When kanamycin was pre-supplemented with EDTA for anticoagulating blood samples from EDTA-PTCP patients there was no significant change in the platelet counts and the morphology of blood cells after 150 min of incubation at room temperature. Furthermore, when kanamycin was added to EDTA-anticoagulated blood samples from EDTA-PTCP patients within 30 min after blood withdrawal, rapid dissociation of platelets without apparent morphological changes of blood cells was observed, and complete blood cell counts as well as the histogram patterns were almost the same as those examined immediately after blood sampling. The dissociation of aggregated platelets was also detected when other antibiotics were used, although it was associated with some extent of morphological changes of blood cells. These findings indicate that the supplementation of aminoglycosides either before or after blood sampling is a useful method for the diagnosis EDTA-PTCP and for the evaluation of platelet counts in patients with EDTA-PTCP.

  10. Effect of the crude extract of Cestrum parqui on carrageenin-induced rat paw oedema and aggregation of human blood platelets.

    Science.gov (United States)

    Shehnaz, D; Hamid, F; Baqai, F T; Uddin Ahmad, V

    1999-08-01

    An extract of Cestrum parqui aerial parts in methanol:water (1:1) showed inhibition of carrageenin-induced oedema. The aggregation of human blood platelets induced by adenosine diphosphate and platelet activating factor was also inhibited (IC(50)s were 3 and 2 mg/mL, respectively). On the contrary, the extract did not inhibit arachidonic acid-mediated platelet aggregation.

  11. Changes in the level of cytosolic calcium, nitric oxide and nitric oxide synthase activity during platelet aggregation: an in vitro study in platelets from normal subjects and those with cirrhosis

    Indian Academy of Sciences (India)

    Sam Annie-JeyachristYn; Arumugam Geetha; Rajagopal Surendran

    2008-03-01

    Variceal bleeding due to abnormal platelet function is a well-known complication of cirrhosis. Nitric oxide-related stress has been implicated in the pathogenesis of liver cirrhosis. In the present investigation, we evaluated the level of platelet aggregation and concomitant changes in the level of platelet cytosolic calcium (Ca2+), nitric oxide (NO) and NO synthase (NOS) activity in liver cirrhosis. The aim of the present study was to investigate whether the production of NO by NOS and level of cytosolic Ca2+ influence the aggregation of platelets in patients with cirrhosis of the liver. Agonist-induced aggregation and the simultaneous changes in the level of cytosolic Ca2+, NO and NOS were monitored in platelets of patients with cirrhosis. Platelet aggregation was also measured in the presence of the eNOS inhibitor, diphenylene iodinium chloride (DIC). The level of agonist-induced platelet aggregation was significantly low in the platelets of patients with cirrhosis compared with that in platelets from normal subjects. During the course of platelet aggregation, concomitant elevation in the level of cytosolic Ca2+ was observed in normal samples, whereas the elevation was not significant in platelets of patients with cirrhosis. A parallel increase was observed in the levels of NO and NOS activity. In the presence of the eNOS inhibitor, platelet aggregation was enhanced and accompanied by an elevated calcium level. The inhibition of platelet aggregation in liver cirrhosis might be partly due to greater NO formation by eNOS. Defective Ca2+ release from the internal stores to the cytosol may account for inhibition of aggregation of platelets in cirrhosis. The NO-related defective aggregation of platelets in patients with cirrhosis found in our study is of clinical importance, and the underlying mechanism of such changes suggests a possible therapeutic strategy with cell-specific NO blockers.

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

    Science.gov (United States)

    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.

  13. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study

    OpenAIRE

    Hubbard, G; Wolffram, S; Vos, de, W.M.; Bovy, A.G.; Gibbins, J.; Lovegrove, J

    2006-01-01

    Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate the possible inhibitory effects of quercetin ingestion from a dietary source on collagen-stimulated platelet aggregation and signalling. A double-blind randomised cross-over pilot study was undertak...

  14. Platelet response to increased aspirin dose in patients with persistent platelet aggregation while treated with aspirin 81 mg.

    Science.gov (United States)

    Gengo, Fran; Westphal, Erica S; Rainka, Michelle M; Janda, Maria; Robson, Matthew J; Hourihane, J Maurice; Bates, Vernice

    2016-04-01

    This study demonstrates that patients who are taking 81 mg of aspirin and are nonresponsive benefit from a dose of 162 mg or greater vs a different antiplatelet therapy. We identified 100 patients who were nonresponsive to aspirin 81 mg via whole blood aggregometry and observed how many patients became responsive at a dose of 162 mg or greater. Platelet nonresponsiveness was defined as >10 Ω of resistance to collagen 1 µg/mL and/or an ohms ratio of collagen 1 µg/mL to collagen 5 µg/mL >0.5 and/or >6 Ω to arachidonate. Borderline response was defined as an improvement in 1 but not both of the above criteria. Of the initial 100 patients who were nonresponsive to an aspirin dose of 81 mg, 79% became responsive at a dose of 162 mg or >162 mg. Only 6% did not respond to any increase in dose. We believe that patients treated with low-dose aspirin who have significant risk for secondary vascular events should be individually assessed to determine their antiplatelet response. Those found to have persistent platelet aggregation despite treatment with 81 mg of aspirin have a higher likelihood of obtaining an adequate antiplatelet response at a higher aspirin dose.

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

    Science.gov (United States)

    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.

  16. Prostaglandin A1 inhibits increases in intracellular calcium concentration, TXA2 production and platelet activation

    Institute of Scientific and Technical Information of China (English)

    Yi ZHU; Zhen-lun GU; Zhong-qin LIANG; Hui-lin ZHANG; Zheng-hong QIN

    2006-01-01

    Aim: In our previous studies we found that cyclopentenane prostaglandin A1 (PGA1) had neuroprotective effects in a rodent ischemic model. In the present study we aimed to investigate the inhibitory effect of PGA1 on platelet function. Method: The rate of aggregation of human platelets was measured by using turbidimetry. The rate of adhesion of platelets to cultured endothelial cells was determined by using [3H]-adenine labeled platelets. 5-Hydroxytryptamine release from platelets was measured with O-phthaldialdehyde fluorospectrophotometry. The levels of TXB2, a stable metabolite of TXA2, were determined by radioimmunoassay. Alternations in platelet morphology were observed using an electron microscope, and the intraplatelet free calcium concentrations were measured with Fluo-3/AM FCM assay. Results: PGA1 significantly inhibited thrombin-collagen-and ADP-induced aggregation and adhesion of platelets. The morphological changes of platelets induced by thrombin were blocked by PGA1. PGA1 inhibited the release of 5-hydroxytyptamine from dense granules and the synthesis of TXA2. Conclusion: PGA1 inhibits the activation of platelets probably through blocking increases in intracellular calcium concentration and TXA2 synthesis.

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

    Science.gov (United States)

    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.

  18. Platelet aggregation is affected by nitrosothiols in patients with chronic hepatitis: In vivo and in vitro studies

    Institute of Scientific and Technical Information of China (English)

    A Federico; C Loguercio; A Filippelli; M Falciani; C Tuccillo; A Tiso; A Floreani; R Naccarato; F Rossi; C Del Vecchio Blanco

    2007-01-01

    AIM: To investigate the relationship among the number of platelets and plasma levels of S-nitrosothiols (S-NO),nitrite, total non-protein SH (NPSH), glutathione (GSH), cysteine (CYS), malondialdehyde (MDA),4-hydroxininenal (4HNE), tumor necrosis factor-alpha (TNFα) and interleukin (IL)-6 in patients with chronic hepatitis C (CH).METHODS: In vitro the aggregation of platelets derived from controls and CH patients was evaluated before and after the addition of adenosine diphosphate (ADP) and collagen, both in basal conditions and after incubation with nitrosoglutathione (GSNO).RESULTS: In vivo, S-NO plasma levels increased significantly in CH patients and they were significantly directly correlated with platelet numbers. Patients with platelet counts < 150000/μL, had a smaller increase in S-NO, lower levels of GSH, CYS, NPSH, TNFα, and IL-6,and higher levels of nitrite, MDA, and 4-HNE relative to those of patients with platelet counts > 150000/μL.In vitro, the ADP and collagen aggregation time was increased in platelets from patients and not from controls; in addition, platelets from CH patients but not from controls also showed a latency time after exposure to collagen.CONCLUSION: The incubation of platelets with GSNO improved the percentage aggregation and abolished the latency time.

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

    Science.gov (United States)

    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

  20. Inhibition of glutamate receptors reduces the homocysteine-induced whole blood platelet aggregation but does not affect superoxide anion generation or platelet membrane fluidization.

    Science.gov (United States)

    Karolczak, Kamil; Pieniazek, Anna; Watala, Cezary

    2017-01-01

    Homocysteine (Hcy) is an excitotoxic amino acid. It is potentially possible to prevent Hcy-induced toxicity, including haemostatic impairments, by antagonizing glutaminergic receptors. Using impedance aggregometry with arachidonate and collagen as platelet agonists, we tested whether the blockade of platelet NMDA (N-methyl-D-aspartate), AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and kainate receptors with their inhibitors: MK-801 (dizocilpine hydrogen maleate, [5R,10S]-[+]-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine), CNQX (7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile) and UBP-302 (2-{[3-[(2S)-2-amino-2-carboxyethyl]-2,6-dioxo-3,6-dihydropyrimidin 1(2H)-yl]methyl}benzoic acid) may hamper Hcy-dependent platelet aggregation. All the tested compounds significantly inhibited Hcy-augmented aggregation of blood platelets stimulated either with arachidonate or collagen. Hcy stimulated the generation of superoxide anion in whole blood samples in a concentration-dependent manner; however, this process appeared as independent on ionotropic glutamate receptors, as well as on NADPH oxidase and protein kinase C, and was not apparently associated with the extent of either arachidonate- or collagen-dependent platelet aggregation. Moreover, Hcy acted as a significant fluidizer of surface (more hydrophilic) and inner (more hydrophobic) regions of platelet membrane lipid bilayer, when used at the concentration range from 10 to 50 µmol/l. However, this effect was independent on the Hcy action through glutamate ionotropic receptors, since there was no effects of MK-801, CNQX or UBP-302 on Hcy-mediated membrane fluidization. In conclusion, Hcy-induced changes in whole blood platelet aggregation are mediated through the ionotopic excitotoxic receptors, although the detailed mechanisms underlying such interactions remain to be elucidated.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Santos-Martinez MJ

    2012-01-01

    Full Text Available Maria Jose Santos-Martinez1–3, Iwona Inkielewicz-Stepniak1,4, Carlos Medina1, Kamil Rahme5,6, Deirdre M D'Arcy1, Daniel Fox3, Justin D Holmes3,5, Hongzhou Zhang3, Marek Witold Radomski3,51School of Pharmacy and Pharmaceutical Sciences, 2School of Medicine, 3Center for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin, Ireland; 4Department of Medicinal Chemistry, Medical University of Gdansk, Gdansk, Poland; 5Materials and Supercritical Fluids Group, Department of Chemistry and the Tyndall National Institute, University College Cork, Cork, Ireland; 6Department of Sciences, Faculty of Natural and Applied Science, Notre Dame University, Zouk Mosbeh, LebanonAbstract: 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

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

    Science.gov (United States)

    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 raspberry and by 38-55% for dewberry, P 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.

  4. Platelet-neutrophil complex formation-a detailed in vitro analysis of murine and human blood samples.

    Science.gov (United States)

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

    2016-05-01

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

  5. The effect of cimetidine on platelet function: a study involving gastric fluid measurements.

    Science.gov (United States)

    Mikhailidis, D P; Christofides, J; Barradas, M A; Jeremy, J Y; Dilawari, J; Dandona, P

    1986-10-01

    Gastric fluid samples were aspirated 30 and 60 minutes after the ingestion of two 200 mg tablets of cimetidine. The concentration of cimetidine in these samples was measured and their effect on platelet aggregation assessed in vitro. Gastric fluid samples significantly inhibited adrenaline- and ADP-induced platelet aggregation in vitro. In a further series of experiments, cimetidine solutions, at concentrations found in gastric fluid, inhibited platelet aggregation and thromboxane A2 (TXA2) release, in vitro. Ranitidine, another H2-receptor antagonist, was a more potent inhibitor of platelet aggregation than cimetidine. Since ranitidine is also the more potent H2-receptor antagonist which, unlike cimetidine, does not include an imidazole group (which is known to inhibit TXA2 synthesis) in its structure, we conclude that H2 blockade mediates the observed inhibition of aggregation. This platelet anti-aggregatory effect may be relevant to haemostatic mechanisms involved in bleeding peptic ulcers or gastric erosions exposed to high local concentrations of H2-receptor antagonists.

  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.

    Science.gov (United States)

    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. Anti-platelet Aggregation and Anti-thrombotic Effects of Marine Natural Products Sargahydroquinoic Acid and Sargaquinoic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byonggon; Oh, Sangtae; Kwon, Daeho; Cui, Yuan; Ham, Jungyeob; Shin, Woonseob; Lee, Seokjoon [Kwandong Univ. College of Medicine, Gangneung (Korea, Republic of)

    2013-10-15

    On the basis of the results of the in vitro platelet aggregation inhibition test, we discovered that of SHQA (1) and SQA (2) show a strong inhibitory effect on platelet aggregation. To enable preclinical and clinical studies to be conducted, we synthesized SQA from natural SHQA in high yield. In addition, we confirmed that SHQA (1) and SQA (2) show a fast recovery time from paralysis in the mouse pulmonary thromboembolism model, indicating that they are strong, novel anti-platelet drug candidates. As bleeding is a main side effect of the APDs used clinically, we also plan to conduct a bleeding test with SHQA and SQA and will report these results in a future proper paper. Platelets circulate in blood and their activity is regulated by nitric oxide (NO) and prostaglandin I{sub 2} (PGI{sub 2}) released from endothelial cells in a quiescent state under physiological conditions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Gyrid [Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen (Norway); Department of Biomedicine, University of Bergen, Bergen (Norway); Herfindal, Lars; Kopperud, Reidun [Department of Biomedicine, University of Bergen, Bergen (Norway); Aragay, Anna M. [Department of Biomedicine, University of Bergen, Bergen (Norway); Molecular Biology Institute of Barcelona (IBMB, CSIC), Barcelona (Spain); Holmsen, Holm; Døskeland, Stein Ove; Kleppe, Rune [Department of Biomedicine, University of Bergen, Bergen (Norway); Selheim, Frode, E-mail: Frode.Selheim@biomed.uib.no [Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen (Norway); Department of Biomedicine, University of Bergen, Bergen (Norway)

    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.

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

    Science.gov (United States)

    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, p0.05). These results indicates that variations of GP IIb/IIIa content affect platelet aggregating activity within first hours of ACS upon ASA treatment. However after saturation with clopidogrel this factor has no significant influence on platelet aggregation

  10. Ehlers-danlos syndrome with platelet aggregation defect-presenting as mysterious bleeding disorder

    Directory of Open Access Journals (Sweden)

    Sawhney M

    2003-01-01

    Full Text Available A 7-year-old girl presented with recurrent episodes of petechiae, purpura and ecchymoses since six months of age and recurrent episodes of mild to severe epistaxis since two years of age requiring repeated blood transfusions. In April '99 while being investigated for a massive epistaxis, she was found to have platelet function defect with abnormal aggregation of platelets to ADP, epinephrine, collagen as well as to ristocetin. Further investigations ruled out the possibility of Glanzmann's disorder and von-Willebrand's disease as to its cause. In May 2001 she was referred to the dermatologist for evaluation of subcutaneous tumours, which had developed since the last six months. On clinical evaluation, she was found to be having mild hyperextensibility of the skin, joint hypermobility, atrophic scars over knee, spontaneous bruises over right forearm and left thigh and nontender firm to hard subcutaneous nodules over both wrists, both shoulders, right index finger and dorsum of right foot consistent with a clinical picture of a mild form of Ehlers-Danlos syndrome (EDS. Histopathology of the nodule from left wrist was consistent with molluscoid tumour of EDS and skin histopathology and ultrastructure studies showed thick irregular collagen fibrils. Only other sibling, a five-year-old male also had history of repeated mild to moderate epistaxis and on examination was found to have a milder variant of EDS. Born out of I degree consanguineous marriage of normal parents with mildly affected other sibling, she was diagnosed to be suffering from EDS with autosomal recessive inheritance, most probably EDS type X due to the associated platelet aggregation defect. Only one such family with EDS type X has been reported so far.

  11. Decreased threshold of aggregation to low-dose epinephrine is evidence of platelet hyperaggregability in patients with thrombosis

    Directory of Open Access Journals (Sweden)

    Chelsea Hayes

    2014-08-01

    Full Text Available Sticky platelet syndrome has been described as a hereditary thrombophilic condition. The aim of this study is to identify the presence of platelet hyperaggregability in patients who have experienced thrombosis. Light-transmittance platelet aggregometry was used to assess for spontaneous platelet aggregation, aggregation in response to full and low-dose (LD epinephrine (Epi and adenosine diphosphate, as well as arachidonic acid, and identify a distinct pattern of platelet hyperaggregability. Light-transmittance platelet aggregometry results were correlated with PFA-100® (Dade-Behring, Marburg, Germany results, when available. An exaggerated response to LD Epi was found in 68% of patients with thrombosis compared to only 36% of healthy controls (P=0.034. Patients with thrombosis, either arterial or venous, demonstrated an exaggerated response to LD Epi nearly twice as frequently as healthy controls, even without significant family history of thrombophilia or other known risk factors for thrombosis. This suggests that platelet hyperaggregability may be multifactorial in nature and not necessarily hereditary.

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

    Directory of Open Access Journals (Sweden)

    Mayara Ribeiro de Queiroz

    2014-01-01

    Full Text Available 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.

  13. Dengue fever activates the L-arginine-nitric oxide pathway: an explanation for reduced aggregation of human platelets.

    Science.gov (United States)

    Mendes-Ribeiro, Antonio C; Moss, Monique B; Siqueira, Mariana As; Moraes, Thalyta L; Ellory, J Clive; Mann, Giovanni E; Brunini, Tatiana Mc

    2008-10-01

    In patients with Dengue fever, a viral inflammatory syndrome, haemorrhage is a significant pathological feature, yet the underlying mechanisms remain unclear. Nitric oxide (NO) is an important regulator of platelet function, inhibiting aggregation, recruitment and adhesion to the vascular endothelium. We have investigated whether changes in the activity of the L-arginine-NO pathway in human platelets may account for increased bleeding in patients with Dengue fever. A total of 16 patients with Dengue fever and 18 age-matched healthy volunteers participated in the study. Collagen induced platelet aggregation in a dose-dependent manner in both Dengue patients and controls, but the degree of platelet aggregation was significantly reduced in the patient group. Elevated rates of L-arginine transport in Dengue fever patients were associated with enhanced NO synthase activity and elevated plasma fibrinogen levels. The present study provides the first evidence that Dengue fever is associated with increased L-arginine transport and NO generation and reduced platelet aggregation.

  14. Platelets

    Science.gov (United States)

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

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

    Science.gov (United States)

    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 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.

  16. The effect of physical exercise on the daily rhythm of platelet aggregation and body temperature in horses.

    Science.gov (United States)

    Piccione, Giuseppe; Grasso, Fortunata; Fazio, Francesco; Giudice, Elisabetta

    2008-05-01

    The goal of this study was to investigate the influence of physical activity on the daily rhythm of platelet aggregation and body temperature in horses. Blood samples from 12 Thoroughbred horses, six sedentary animals and six athletes (studied both before and after a period of inactivity) were collected at 4h intervals for 48h via an intravenous cannula inserted into the jugular vein. Body temperature was recorded every 4h for 48h with a rectal probe. Platelet aggregation was measured with an aggregometer. Collagen was used to test the aggregation of the plasma samples. Statistical analysis of the data was performed by one-way repeated-measures analysis of variance (ANOVA) and by single cosinor method. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. On each single day, there was a highly significant effect of time in all the horses, with P values Temperature rhythms were unaffected by exercise. Platelet aggregation in exercising horses differed from the sedentary horses, and this difference disappeared after a 2-week period of rest. The results could be interpreted as indicating that physical exercise has an influence on the daily rhythm of platelet aggregation in horses.

  17. Effects of aspirin dosage and time of administration on arterial prostacyclin production and platelet aggregation in rats.

    Science.gov (United States)

    Philp, R B; Paul, M L

    1984-07-01

    Previously we reported that electrically-induced carotid artery thrombosis in anesthetized rats was prevented by 3.3 or 10 mg/kg aspirin (ASA) given i.v. 10 min before injury but not by 1.7, 20 or 100 mg/kg and protection was lost by delaying injury to 20 min (Haemostasis 13:42, 1983). Here, collagen-induced platelet aggregation and arterial prostacyclin-generating activity, measured by RIA for 6 keto-PGF1 alpha and by human platelet aggregation bioassay, were studied ex vivo after i.v. ASA to anesthetized rats. In all cases where platelet aggregation was inhibited less than 50%, no protection had been observed (1.7 mg/kg at 10 min, 3.3 at 20 min, 20 at 10 min). In the two cases where protection had been observed, platelet aggregation was inhibited by about 75% or more and in one, prostacyclin activity was about 50% of normal (3.3 mg/kg at 10 min). Thus in five of six dose-time combinations tested, antithrombotic protection could be explained by a requirement for about 50% of normal prostacyclin activity and about 75% of inhibition of collagen aggregation. Aberrant findings are discussed in the light of knowledge of salicylate/aspirin competition for cyclooxygenase.

  18. An inhibitor selective for collagen-stimulated platelet aggregation from the salivary glands of hard tick Haemaphysalis longicornis and its mechanism of action

    Institute of Scientific and Technical Information of China (English)

    程远国; 吴厚永; 李德昌

    1999-01-01

    Soluble materials of salivary glands from Haemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longieornin, is a protein of moleeular weight 16 000 on SDS-PAGE under both reduced and nonredueed conditions. Collagen-mediated aggregation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effeetors, including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate acetate, was observed. Longieonin had no effect on platelet adhension to collagen. Not only platelet aggregation but also release reaction, and increase of intraeellar Ca2+ level of platelets in response to collagen were com

  19. Effect of Desmopressin on Platelet Aggregation and Blood Loss in Patients Undergoing Valvular Heart Surgery

    Institute of Scientific and Technical Information of China (English)

    Lei Jin; Hong-Wen Ji

    2015-01-01

    Background:Blood loss after cardiac surgery can be caused by impaired platelet (PLT) function after cardiopulmonary bypass.Desmopressin or 1-deamino-8-D-arginine vasopressin (DDAVP) is a synthetic analog of vasopressin.DDAVP can increase the level of von Willebrand factor and coagulation factor Ⅷ,thus it may enhance PLT function and improve coagulation.In this study,we assessed the effects of DDAVP on PLT aggregation and blood loss in patients undergoing cardiac surgery.Methods:A total of 102 patients undergoing valvular heart surgery (from October 2010 to June 2011) were divided into DDAVP group (n =52) and control group (n =50).A dose of DDAVP (0.3 μtg/kg) was administered to the patients intravenously when they were being re-warmed.At the same time,an equal volume of saline was given to the patients in the control group.PLT aggregation rate was measured with the AggRAM four-way PLT aggregation measurement instrument.The blood loss and transfusion,hemoglobin levels,PLT counts,and urine outputs at different time were recorded and compared.Results:The postoperative blood loss in the first 6 h was significantly reduced in DDAVP group (202 ± 119 ml vs.258 ± 143 ml,P =0.023).The incidence of fresh frozen plasma (FFP) transfusion was decreased postoperatively in DDAVP group (3.8% vs.12%,P =0.015).There was no significant difference in the PLT aggregation,urine volumes,red blood cell transfusions and blood loss after 24 h between two groups.Conclusions:A single dose of DDAVP can reduce the first 6 h blood loss and FFP transfusion postoperatively in patients undergoing valvular heart surgery,but has no effect on PLT aggregation.

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

    Science.gov (United States)

    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.

  1. Synthesis of ((pyridin-3-yl) methoxy) aromatic acid derivatives and their inhibitory effects on platelet aggregation%((吡啶-3-基)甲氧基)芳酸衍生物的合成及抗血小板聚集活性

    Institute of Scientific and Technical Information of China (English)

    李家明; 马逢时; 龙子江; 钟国琛; 周鹏; 袁明

    2011-01-01

    以具有活血化瘀作用的中药有效成分阿魏酸为先导物,按生物电子等排原理,设计合成了6个((吡啶-3-基)甲氧基)芳酸衍生物,其结构经IR,1H NMR,13C NMR及MS确证.体外药效筛选结果显示,部分((吡啶-3-基)甲氧基)芳酸衍生物对二磷酸腺苷(ADP)诱导的血小板聚集具有较好的抑制活性,其中化合物1a的抑制作用明显强于阳性对照药奥扎格雷钠.%Ferulic acid, which is useful compound of Chinese traditional medicine, was used as leading compound,six ( (pyridin-3-yl) methoxy)aromatic acid derivatives were designed and synthesized based on bioisosterism.Their structures were characterized by IR, 1H NMR, 13C NMR and mass spectra.In vitro experiment, some compounds have good inhibitory effects on adenosine diphophate (ADP) induced platelet aggregation, among them compound la showed more potent potent aggregation inhibitory activity than 0zagrel.

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

    Directory of Open Access Journals (Sweden)

    Eduardo Fuentes

    2013-01-01

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

  3. Extract from Aronia melanocarpa fruits potentiates the inhibition of platelet aggregation in the presence of endothelial cells

    Science.gov (United States)

    Luzak, Boguslawa; Golanski, Jacek; Rozalski, Marek; Krajewska, Urszula; Olas, Beata

    2010-01-01

    Introduction Some polyphenolic compounds extracted from Aronia melanocarpa fruits (AM) have been reported to be cardioprotective agents. In this study we evaluated the ability of AM extract to increase the efficacy of human umbilical vein endothelial cells (HUVECs) to inhibit platelet functions in vitro. Material and methods This study encompasses two models of monitoring platelet reactivity: optical aggregation and platelet degranulation (monitored as the surface CD62P expression) in PRP upon the stimulation with ADP. Results We observed that only at low concentrations (5 µg/ml) did AM extract significantly improve antiplatelet action of HUVECs towards ADP-activated platelets in the aggregation test. Conclusions It is concluded that the potentiating effect of AM extract on the endothelial cell-mediated inhibition of platelet aggregation clearly depends on the used concentrations of Aronia-derived active compounds. Therefore, despite these encouraging preliminary outcomes on the beneficial effects of AM extract polyphenols, more profound dose-effect studies should certainly be considered before the implementation of Aronia-originating compounds in antiplatelet therapy and the prevention of cardiovascular diseases. PMID:22371737

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

    Science.gov (United States)

    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

  5. Prolongation of bleeding time and inhibition of platelet aggregation by low-dose acetylsalicylic acid in patients with cerebrovascular disease

    DEFF Research Database (Denmark)

    Boysen, G; Boss, A H; Ødum, Niels

    1984-01-01

    Platelet aggregation and bleeding time was measured in 43 cerebrovascular patients participating in a controlled double-blind study of low-dose acetylsalicylic acid. In 19 patients with satisfactory inhibition of the platelet aggregation obtained by 50 to 70 mg acetylsalicylic acid per day...... the bleeding time averaged 11.2 minutes in contrast to 7.0 minutes in the placebo group, p less than 0.001. This study confirms our previous findings of platelet inhibition by low-dose acetylsalicylic acid in patients with cerebrovascular disease. The prolongation of the bleeding time demonstrates that we...... are dealing not merely with an in vitro phenomenon but with a significant in vivo effect. The study provides the rationale for clinical evaluations of low-dose acetylsalicylic acid in stroke prophylaxis....

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

    Science.gov (United States)

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

    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.

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

    Science.gov (United States)

    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.

  8. Extracts from Trifolium pallidum and Trifolium scabrum aerial parts as modulators of blood platelet adhesion and aggregation.

    Science.gov (United States)

    Kolodziejczyk-Czepas, Joanna; Olas, Beata; Malinowska, Joanna; Wachowicz, Barbara; Szajwaj, Barbara; Kowalska, Iwona; Oleszek, Wieslaw; Stochmal, Anna

    2013-01-01

    A growing number of reports indicate that some species of clover (Trifolium) may have remarkable medical importance; however, the effects of these plants on blood platelets and hemostasis are inadequately recognized. This work was designed to study the effects of Trifolium pallidum and Trifolium scabrum extracts on the functions of human blood platelets in vitro. Platelet suspensions were preincubated with extracts from aerial parts of T. pallidum (phenolic fraction and clovamide fraction) and T. scabrum (phenolic fraction) at the final concentrations of 12.5, 25, and 50 µg/ml. Then, for platelet activation thrombin (0.1 U/ml), thrombin receptor activating peptide (TRAP; 20 µM), or adenosine diphosphate (ADP; 1 µM) were used. The effects of Trifolium extracts on adhesion of blood platelets to fibrinogen and collagen were determined by enzyme-linked immunosorbent assay (ELISA) method. Platelet aggregation was monitored on a dual-channel Chronolog aggregometer. In these studies, we also compared the action of tested plant extracts with the effects of another antiplatelet plant-derived compound - resveratrol (3,4',5-trihydroxystilbene). The performed assays demonstrated that the tested extracts might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of all tested extracts on adhesion of thrombin-stimulated platelets to collagen was found. Both extracts from T. pallidum and from T. scabrum reduced the thrombin-induced platelet adhesion to fibrinogen. Furthermore, in the presence of all three extracts, the platelet aggregation induced by thrombin was slightly inhibited. Our results also indicate that the tested plant extracts (at the highest concentrations used of 50 µg/ml), similar to purified resveratrol, inhibit selected steps of platelet activation stimulated by both proteolytic (thrombin) and nonproteolytic agonists (TRAP or ADP). In the comparative studies, T. pallidum and T. scabrum extracts was not found

  9. Anti-Platelet Aggregation and Vasorelaxing Effects of the Constituents of the Rhizomes of Zingiber officinale

    Directory of Open Access Journals (Sweden)

    Tian-Shung Wu

    2012-07-01

    Full Text Available In the present study, the chemical investigation of the bioactive fractions of the rhizomes of Zingiber officinale has resulted in the identification of twenty-nine compounds including one new compound, O-methyldehydrogingerol (1. Some of the isolates were subjected into the evaluation of their antiplatelet aggregation and vasorelaxing bioactivities. Among the tested compounds, [6]-gingerol (13 and [6]-shogaol (17 exhibited potent anti-platelet aggregation bioactivity. In addition, [10]-gingerol (15 inhibited the Ca2+-dependent contractions in high K+ medium. According to the results in the present research, the bioactivity of ginger could be related to the anti-platelet aggregation and vasorelaxing mechanism.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  12. Decreased platelet aggregation by shear stress-stimulated endothelial cells in vitro: description of a method and first results in diabetes.

    Science.gov (United States)

    De Franceschi, Maria S; Palange, Anna L; Mancuso, Anna; Grande, Laura; Muccari, Domenico; Scavelli, Faustina B; Irace, Concetta; Gnasso, Agostino; Carallo, Claudio

    2015-01-01

    The interaction between platelets and endothelium in vivo is a complex phenomenon. Our aim was to develop an in vitro system that mimics the in vivo environment and investigate platelet function in a common pathological condition. Human umbilical vein endothelial cells were used and platelets from 28 type 2 diabetes patients were studied under shear stress conditions. Mean coefficient of variation of platelet aggregation was 10% in dynamic conditions in the presence of endothelium. Endothelial cells increased the concentration of inductor needed to achieve 50% platelet aggregation to adenosine diphosphate from 2.6 ± 1.3 in static conditions to 3.7 ± 1.3 µM in dynamic conditions. A similar pattern was observed when collagen was used for platelet activation. Incubation of endothelium with a nitric oxide inhibitor abolished this effect, indicating platelet inhibitory effect of endothelial cells is nitric oxide mediated. Platelet reactivity of healthy controls was less influenced by the presence of endothelial cells and displayed reduced basal platelet reactivity compared with platelets from diabetes patients. We show that platelet aggregation in diabetes as commonly reported in vitro may not fully reflect the in vivo pathophysiological process. Future studies are warranted to investigate other pathological conditions and analyse the effects of antiplatelet agents using this system.

  13. Effect of Platelet Concentration of Platelet-rich Plasma on Platelet Aggregation%富血小板血浆中血小板浓度对血小板聚集的影响

    Institute of Scientific and Technical Information of China (English)

    李祖兰; 张靓; 杨亮程; 任军伟; 丛玉隆; 夏杰成; 李健; 马长生; 邓新立; 王海立

    2012-01-01

    Objective To explore the effect of platelet concentration of platelet-rich plasma (PEP) on platelet aggregation. Methods 107 blood samples of outpatient volunteers were randomly collected and centrifuged, PRP and PPP( platelet-poor plasma) were gotten , then platelet concentration of PRP was detected by the blood analyzer and diluted with their own PPP into a series of platelet concentration of plasma in the gradient: 50×109/ L ~ 400×109/L, then platelet aggregation rates of the plasma were detected according to the standard protocols by plasma turbidimetry. Results The platelet concentrations of the plasma were in the range of 50×109/L ~ 400 ×109/L, and the platelet aggregation rate gradually increased with a higher concentration of platelet, but slowly at the concentration of 250×109/L. When platelet concentrations 150×109/L at least for routine platelet aggregation tests. The platelet concentration of 250×10 /L seems to be the optimal concentration for platelet aggregation by plasma turbidimetry.%目的 探讨富血小板血浆(PRP)血小板浓度对血小板聚集的影响.方法 随机收集107名门诊体检健康志愿者静脉血浆,分离PRP和PPP(贫血小板血浆)后,用血液分析仪测定PRP血小板浓度,按PRP浓度用自身PPP配成50×109/L ~400×109/L浓度梯度的血浆,用血浆比浊法测血小板聚集率.结果 PRP血小板浓度在50×109/L~400×109/L,二磷酸腺苷(ADP)和花生四烯酸(AA)诱导的血小板聚集率分别为(10.4±8.7)%至(55.3±9.9)%和0%至(75.2±10.1)%,血小板聚集率随血小板浓度的增高而增高,血小板浓度为250×109/L时,聚集率增幅减缓,血小板浓度小于150×109/L时,血小板聚集率明显降低.结论 PRP血小板浓度对血小板聚集的影响明显,血小板聚集试验PRP血小板浓度大于150×109/L;血浆比浊法血小板聚集试验适宜的血小板浓度为250×109/L.

  14. Targeted deep resequencing identifies coding variants in the PEAR1 gene that play a role in platelet aggregation.

    Directory of Open Access Journals (Sweden)

    Yoonhee Kim

    Full Text Available Platelet aggregation is heritable, and genome-wide association studies have detected strong associations with a common intronic variant of the platelet endothelial aggregation receptor1 (PEAR1 gene both in African American and European American individuals. In this study, we used a sequencing approach to identify additional exonic variants in PEAR1 that may also determine variability in platelet aggregation in the GeneSTAR Study. A 0.3 Mb targeted region on chromosome 1q23.1 including the entire PEAR1 gene was Sanger sequenced in 104 subjects (45% male, 49% African American, age = 52±13 selected on the basis of hyper- and hypo- aggregation across three different agonists (collagen, epinephrine, and adenosine diphosphate. Single-variant and multi-variant burden tests for association were performed. Of the 235 variants identified through sequencing, 61 were novel, and three of these were missense variants. More rare variants (MAF<5% were noted in African Americans compared to European Americans (108 vs. 45. The common intronic GWAS-identified variant (rs12041331 demonstrated the most significant association signal in African Americans (p = 4.020×10(-4; no association was seen for additional exonic variants in this group. In contrast, multi-variant burden tests indicated that exonic variants play a more significant role in European Americans (p = 0.0099 for the collective coding variants compared to p = 0.0565 for intronic variant rs12041331. Imputation of the individual exonic variants in the rest of the GeneSTAR European American cohort (N = 1,965 supports the results noted in the sequenced discovery sample: p = 3.56×10(-4, 2.27×10(-7, 5.20×10(-5 for coding synonymous variant rs56260937 and collagen, epinephrine and adenosine diphosphate induced platelet aggregation, respectively. Sequencing approaches confirm that a common intronic variant has the strongest association with platelet aggregation in African Americans

  15. Inhibition of human platelet aggregation by dihydropyrano- and dihydrofuranocoumarins, a new class of cAMP-phosphodiesterase inhibitors

    DEFF Research Database (Denmark)

    Thastrup, Ole; Knudsen, J B; Lemmich, J;

    1985-01-01

    Certain esters of dihydropyranocoumarin and dihydrofuranocoumarin alcohols have previously been shown to inhibit the cAMP-phosphodiesterase from bovine heart. We now report that these naturally occurring coumarins inhibit the high affinity (Km = 1.1 microM) cAMP-phosphodiesterase from human...... platelets with activities that closely correlate with those obtained using phosphodiesterase from bovine heart tissue. Additionally the coumarins inhibit the aggregation of human platelets induced with ADP, adrenaline and collagen with activities comparable to those of dipyridamole. A lack of significant...

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

    Science.gov (United States)

    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 Ca(2+) 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 Ca(2+) channels in platelets. Overall, our results show that PLC and MAPK inhibitors proved

  17. Differences between mainstream and sidestream tobacco smoke extracts and nicotine in the activation and aggregation of platelets subjected to cardiovascular conditions in diabetes.

    Science.gov (United States)

    Yin, Wei; Rubenstein, David A

    2013-01-01

    Mainstream and sidestream tobacco smoke extracts have been shown to increase platelet activation directly. Furthermore, advanced glycation end products, which are present in the diabetic vasculature, have also been shown to enhance platelet activity. However, the combined effects of these two risk factors on platelet functions remain unclear. Platelets were exposed to tobacco extracts concurrently with advanced glycation end products. Timed samples were removed to assess the extent of platelet activity. The presence of smoke extracts enhanced platelet activity as compared to control conditions, this was especially prevalent for sidestream extracts. With the addition of irreversibly glycated albumin, there was an additive effect, further enhancing platelet responses. This was at least partially regulated by α-granule release and CD41 expression. The combination of cardiovascular risk factors can significantly enhance platelet activation and aggregation, and therefore it is possible to accelerate cardiovascular diseases through the interactions of multiple cardiovascular risk factors.

  18. 血小板数量对血浆比浊法测定血小板聚集率的影响%The Effect of Different Platelet Counts for Plasma Turbidimetry on Platelet Aggregation Rate

    Institute of Scientific and Technical Information of China (English)

    张庆

    2015-01-01

    Objective To investigate the effect of platelet counts on platelet aggregation test,to regulate platelet aggrega-tion rate detection to improve detection quality,in order to ensure the reliability of measurements of platelet aggregation. Meth-ods 211 cases of healthy people venous whole blood samples were included and centrifuged to obtain platelet-rich plasma ( plate-let-rich plasma,PRP) and platelet-poor plasma (platelet-poor plasma,PPP),the PRP with PPP got different dilutions of platelet concentration of PRP samples tested ,concentration of PRP platelet were confirmed in plasma;Platelet aggregation rate was detected by platelet aggregation nephelometry, and discuss the correlation with platelet. Results Adenosine diphosphate ( ADP ) and arachidonic acid( AA) induced platelet aggregation rate within a laboratory setting reference range. with decreasing concentration of platelet,the aggregation rate decreased significantly(P<0. 05);when the concentration was reduced to <95 ×109/L,the aggre-gate rate of the test resulted below the established reference range;platelet 90~350 × 10 9/L was significantly correlation with the accumulation(rAA =0. 67,rADP =0. 69),other concentrations and aggregation had no correlation. Conclusion Platelet concentra-tion can affect platelet aggregation rate,determination of aggregation rate should be limited at above of 95 × 10 9/L,which reflect the relation of concentration and aggregation rate,and accurately reflect the concentration of aggregation.%目的 探讨血小板数量对血小板聚集率检测的影响,提高检测质量,保证聚集率测定结果的可靠性. 方法 收集211例健康人静脉全血标本,离心获取富血小板血浆( platelet-rich plasma,PRP)和乏血小板血浆( platelet-poor plas-ma,PPP) ,将PRP用自身PPP梯度稀释后获取不同血小板浓度的PRP检测样本,并确认PRP血浆中血小板浓度;利用血浆比浊法测定血小板聚集率,讨论血小板数量与血小

  19. The effects of Lonomin V, a toxin from the caterpillar (Lonomia achelous), on hemostasis parameters as measured by platelet function.

    Science.gov (United States)

    Guerrero, Belsy; Arocha-Piñango, Carmen L; Salazar, Ana M; Gil, Amparo; Sánchez, Elda E; Rodríguez-Acosta, Alexis; Lucena, Sara

    2011-09-15

    Platelets play a central role in hemostasis during vascular injury. Patients affected with the hemorrhagic syndrome caused by contact with Lonomia achelous caterpillars (Lac) Lepidoptera distributed in various South American countries, show digestive, pulmonary and intraperitoneal bleeding in combination with hematomas and echymosis. In the present study, we have evaluated the effects of Lonomin V (serine protease isolated from Lac hemolymph) on some functional properties of platelets, evaluating its importance in primary hemostasis. Platelet adhesion to fibrinogen was reduced by 19, 20, 36, and 37% after pre-treated with 0.2, 2, 20 and 40 nM of Lonomin V, respectively. Pre-incubation of the platelets with 408 nM of Lonomin V, for 4 min at 37 °C, resulted in complete inhibition of the collagen-induced platelet aggregation, in contrast to 56% inhibition of the ADP - induced platelet aggregation. Lonomin V also inhibited anti-α(IIb)β(3) integrin binding to platelets by 56, 57, 52 and 54% at concentrations of 0.2, 2, 20 and 40 nM respectively. Additionally, Lonomin V inhibited anti-P-selectin binding to platelets by 28, 37, 33 and 33% at the same concentrations. The platelets tested with Lonomin V did not modify their viability. In summary, Lonomin V inhibited platelet aggregation, probably caused by the degradation of collagen. The anti-platelet activity of Lonomin V has been shown to be unique and a potentially useful tool for investigating cell-matrix and cell-cell interactions and for the development of antithrombotic agents in terms of their anti-adhesive activities.

  20. Effect of pretreatment with aspirin and ticlopidine on the change of platelet aggregability after radiofrequency catheter ablation

    Institute of Scientific and Technical Information of China (English)

    王利宏; 陈君柱; 郑良荣; 陶谦民

    2002-01-01

    Eighty-two patients with supraventricular tachycardia undergoing radi o frequency catheter ablation (RFCA) were studied to observe the inhibition effect of aspirin and ticlopidine on platelet aggregability (PAG) and thromboxane B2 (T XB2) of the blood samples. Patients were divided into aspirin group A, ticlopi di ne group B, aspirin+ticlopidine group C and control group D. PAG and TXB2 were i ncreased clearly after RFCA in all groups (P<0.001). Treatment with aspirin or t iclopidine before operation could reduce the platelet aggregability caused by RF CA and the joint effect of two drugs(change rate of group A:52.51±12.51%; group B:54.78±11.27%;group C: 30.51±10.59%;group D:91.75±21.43%; P<0.05)was st udie d. The much decreased platelet aggregability after antiplatelet therapy was evid ence of the potential benefit of the treatment in preventing thromboembolism aft er ablation. Pretreatment with aspirin and ticlopidine together is a good way to decrease palatelet aggregability after RFCA.

  1. Specific inhibiting effects of Ilexonin A on von Willebrand factor-dependent platelet aggregation under high shear rate

    Institute of Scientific and Technical Information of China (English)

    李敏; 吴伟康; 刘良; 廖福龙; 篠原幸人; 半田俊之介; 後藤信哉

    2004-01-01

    Background Ilexonin A (IA), purified from the Chinese herbal medicine Maodongqing (Ilex pubescens Hook, et Am) has been commonly used in south China to treat thrombotic disorders. In this study, we aimed to study the inhibiting effects and mechanism of lA on von Willebrand factor (vWF)-dependent high shear-induced platelet aggregation. Methods vWF-dependent high shear (10 800 s-1) induced aggregation of platelets obtained from normal donors in the presence or absence of lA was measured by a modified cone-plate viscometer and shear-induced vWF binding was measured by quantitative flowcytometry with monoclonal antibody known to bind exclusively to the C-terminal domain of vWF (LJ-C3) directly labeled with fluorescein isothiocyanate (FITC). P-selectin surface expression was also measured by a similar method with FITC conjugated anti-P-selectin monoclonal antibody (WGA1).Results Shear-induced platelet aggregation was inhibited by IA in a dose-dependent manner. The extent of aggregation decreased from (78.6±4.6)% in the absence of lA to (36.5±2.1 )% in the presence of lA (3.3 mmol/L) (P<0.0001, n=9) with a high shear rate of 10800 s-1. vWF binding and P-selectin expression were also inhibited by lA in a dose dependent manner. The number of binding FITC-LJ-C3 molecules increased after exposure of platelet-rich plasma to a high shear rate of 10 800 s-1 for 6 minutes, but this shear-induced increased binding platelet surface vWF molecules and P-selectin expression can be decreased in the presence of IA.Conclusion vWF binding and vWF mediated platelet activation, aggregation occurring under high shear rate were inhibited by IA. lA may be a unique antithrombotic drug inhibiting the vWF-GP Ib α interaction, and may thus facilitate drug design targeting arterial thrombosis.

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

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    R. Manjunatha Kini

    2016-09-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

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

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    Dong-Seon Kim

    2017-01-01

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

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

    Science.gov (United States)

    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).

  6. The Effect of Ticagrelor on Platelet Aggregation Ratio in Patients with Clopidogrel Resistance%替格瑞洛在治疗氯吡格雷抵抗患者时血小板聚集率分析

    Institute of Scientific and Technical Information of China (English)

    李江; 刘文娴; 赵一楠; 任燕龙

    2014-01-01

    Objective To research the variance of the platelet aggregation ratio after using ticagrelor instead of clopi-dogrel in patients with clopidogrel resistance. Methods Adenosine diphosphate( ADP)induced platelet aggregation ratio test was run to identify patients with clopidogrel resistance in 512 patients undergoing the treatment of percutaneous coronary interven-tion( PCI)and clopidogrel 75 mg/d. 88 patients with clopidogrel resistance were given randomly clopidogrel 75 mg/d or ticagrelor (90 mg twice a day)for 7 days and took the test of the platelet aggregation ratio after the treatment. Results Aftertreatment for ti-cagrelor group compared with clopidogrel platelet aggregation rate low〔(43. 3 ± 8. 2)% vs. (56. 9 ± 5. 3)%〕,the difference was statistically significant ( P ﹤0. 05 );for the ticagrelor group, platelet aggregation rate decrease than clopidogrel group〔(16. 4 ±9. 8)% vs. (1. 1 ± 4. 1)%〕,the difference is statistically significant(P﹤0. 05);for the the ticagrelor group, platelet aggregation rate compliance rate than clopidogrel group was higher(84. 4% vs. 4. 7%),the difference was statistically significant(P﹤0. 05);for the ticagrelor group and clopidogrel group in the course of the experiment showed no major bleed-ing. Conclusion Ticagrelor,comparing the regular-dose treatment of clopidogrel,can decrease the platelet aggregation ratio in patients with clopidogrel resistance.%目的:探讨在治疗氯吡格雷抵抗患者时,将氯吡格雷更换为替格瑞洛后血小板聚集率的变化情况。方法选择正在应用氯吡格雷75 mg/d治疗的经皮冠状动脉介入治疗( PCI)术后患者512例,用比浊法测定血小板聚集率,根据血小板聚集率筛选出氯吡格雷抵抗患者88例。然后将这88例患者1:1随机分为氯吡格雷组及替格瑞洛组,氯吡格雷组继续服用氯吡格雷(75 mg/d),替格瑞洛组将氯吡格雷(75 mg/d)更换为替格瑞洛(90 mg,2次/d)。随访7d

  7. 脉血康胶囊对经皮冠状动脉介入治疗急性冠脉综合征患者血小板聚集率及其长期预后的影响%Effects of Maixuekang Capsule on the Platelet Aggregation Rate and Its Long-term Prognosis of Patients with Acute Coronary Syndrome under Percutaneous Coronary Intervention

    Institute of Scientific and Technical Information of China (English)

    葛长江; 季凤清; 霍勇; 吕树铮; 柳弘; 宋现涛; 陈欣; 孟康; 苑飞; 冯利霞; 赵聪

    2012-01-01

    Objective To study the changes of adenosine diphosphate (ADP)-induced platelet aggregation rate, and evaluate the effects of Maixuekang Capsule (MC) on the platelet aggregation rate, high-sensitive C-reactive protein (hs-CRP) and the long-term prognosis in patients with acute coronary syndrome under percutaneous coronary intervention (PCI). Methods Totally 236 inpatients with acute coronary syndrome under PCI, who successively received PCI from July 2008 to June 2010, were randomly assigned to the routine treatment group (RTT, 120 cases) and the MC treatment group (MKT, 116 cases). Besides routine medication, patients in the MKT group additionally took MC, 12 capsules daily for 12 successive months. The ADP-induced platelet aggregation rate and hs-CRP concentration were determined before PCI, 12 h and 30 days after PCI. In the meantime, the incidence of adverse cardio-/cerebro-vascular events was recorded during the twelve-month clinical follow-up. Results Compared with before PCI, ADP-induced platelet aggregation rate and the serum hs-CRP concentration were significantly higher 12 h after PCI (P< 0.05). They were significantly reduced after 30-day treatment of MC, showing statistical difference when compared with those in the RTT group (P<0. 05). In the 12-month follow-up, the incidence of adverse cardio-/cerebrovascu-lar events was significantly lower in the MKT group than in the RTT group (6. 9% vs 12. 5%, P<0. 01). Conclusions ADP-induced platelet aggregation function was significantly elevated after PCI, which was a predictive factor of poor coronary events. MC improved the long-term prognosis of patients with acute coronary syndrome possibly through inhibiting the platelet aggregation rate and the hs-CRP concentration.%目的 研究脉血康胶囊对急性冠脉综合征患者行经皮冠状动脉介入治疗(percutaneous coronary intervention,PCI)术后二磷酸腺苷(adenosinediphosphate,ADP)介导血小板聚集率水平

  8. Anti-platelet effect of cumanastatin 1, a disintegrin isolated from venom of South American Crotalus rattlesnake.

    Science.gov (United States)

    Da Silva, Manuel; Lucena, Sara; Aguilar, Irma; Rodríguez-Acosta, Alexis; Salazar, Ana M; Sánchez, Elda E; Girón, Maria E; Carvajal, Zoila; Arocha-Piñango, Carmen L; Guerrero, Belsy

    2009-03-01

    Disintegrins have been previously described in the venom of several snake families inhibiting signal transduction, cell-cell interactions, and cell-matrix interactions and may have therapeutic potential in heart attacks, thrombotic diseases, and cancers. This investigation describes the first disintegrin isolated from South American Crotalus venom (Venezuelan rattlesnake Crotalus durissus cumanensis), which inhibits platelet adhesion to matrix proteins. C. d. cumanensis crude venom was first separated on a Sephadex G-100 column into 4 fractions (SI to SIV). Crude venom and SIII fraction significantly diminished platelet adhesion to fibrinogen (Fg) and to fibronectin (Fn). Anti-adhesive SIII fraction was further separated by DEAE-Sephacel followed by C-18 reverse phase high performance liquid chromatography (HPLC). The platelet anti-adhesive fraction obtained was designated as cumanastatin-1. This disintegrin has a mass of 7.442 kDa as determined by mass spectrometry (MALDI-TOF/TOF) and pI of 8.5. Cumanastatin-1 also inhibited ADP-induced platelet aggregation with an IC(50) of 158 nM. However, it did not significantly inhibit collagen and thrombin-induced platelet aggregation. Cumanastatin-1 considerably inhibited anti-alpha(IIb)beta(3) integrin binding to platelets in a dose-dependent manner; however, it did not present any effect on the alpha(5)beta(1) integrin or on P-selectin.

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

    Science.gov (United States)

    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 infection. We were able to show that, although PLTs are significantly activated in HIV compared to uninfected controls, they retain their functional capacity.

  10. Platelet aggregation unchanged by lipoprotein-associated phospholipase A₂ inhibition: results from an in vitro study and two randomized phase I trials.

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    Bonnie C Shaddinger

    Full Text Available BACKGROUND: We explored the theorized upregulation of platelet-activating factor (PAF- mediated biologic responses following lipoprotein-associated phospholipase A2 (Lp-PLA2 inhibition using human platelet aggregation studies in an in vitro experiment and in 2 clinical trials. METHODS AND RESULTS: Full platelet aggregation concentration response curves were generated in vitro to several platelet agonists in human plasma samples pretreated with rilapladib (selective Lp-PLA2 inhibitor or vehicle. This was followed by a randomized, double-blind crossover study in healthy adult men (n = 26 employing a single-agonist dose assay of platelet aggregation, after treatment of subjects with 250 mg oral rilapladib or placebo once daily for 14 days. This study was followed by a second randomized, double-blind parallel-group trial in healthy adult men (n = 58 also treated with 250 mg oral rilapladib or placebo once daily for 14 days using a full range of 10 collagen concentrations (0-10 µg/ml for characterizing EC50 values for platelet aggregation for each subject. Both clinical studies were conducted at the GlaxoSmithKline Medicines Research Unit in the Prince of Wales Hospital, Sydney, Australia. EC50 values derived from multiple agonist concentrations were compared and no pro-aggregant signals were observed during exposure to rilapladib in any of these platelet studies, despite Lp-PLA2 inhibition exceeding 90%. An increase in collagen-mediated aggregation was observed 3 weeks post drug termination in the crossover study (15.4% vs baseline; 95% confidence interval [CI], 3.9-27.0, which was not observed during the treatment phase and was not observed in the parallel-group study employing a more robust EC50 examination. CONCLUSIONS: Lp-PLA2 inhibition does not enhance platelet aggregation. TRIAL REGISTRATION: 1 Study 1: ClinicalTrials.gov NCT01745458 2 Study 2: ClinicalTrials.gov NCT00387257.

  11. Effect of pretreatment with aspirin and ticlopidine on the change of platelet aggregability after radiofrequency catheter ablation

    Institute of Scientific and Technical Information of China (English)

    王利宏; 陈君柱; 郑良荣; 陶谦民

    2002-01-01

    Eighty-two patients with supraventricular tachycardia undergoing radiofrequency catheter ablation (RFCA) were studied to observe the inhibition effect of aspirin and ticlopidine on platelet aggregability(PAG) and thromboxane B2(TXB2) of the blood samples.Patients were divided into aspirin group A.ticlopidine group B.aspirin+ticlopidine group C and control group D.PAG and TXB2 were increased clearly after RFCA in all groups(P<0.001).Treatment with aspirin or ticlopidine before operation could reduce the patelet aggregability caused by RFCA and the joint effect of two drugs(change rate of group A:52.51±12.51%;group B:54.78±11.27%;group C:30.51±10.59%;group D:91.75±21.43%;(P<0.05)was studied .The much decreased platelet aggregability after antiplatelet therapy was evidence of the potential benefit of the treatment in preventing thromboembolism after ablation.Pretreatment with aspirin and ticlopidine together is a good way to decrease palateler aggregability after RFCA.

  12. 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

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    Hung-Cheng Shih

    2014-03-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  14. Use of tailored loading-dose clopidogrel in patients undergoing selected percutaneous coronary intervention based on adenosine diphosphate-mediated platelet aggregation

    Institute of Scientific and Technical Information of China (English)

    MENG Kang; L(U) Shu-zheng; ZHU Hua-gang; CHEN Xin; GE Chang-jiang; SONG Xian-tao

    2010-01-01

    Background Adenosine phosphate-mediated platelet aggregation is a prognostic factor for major adverse cardiac events in patients who have undergone selective percutaneous coronary interventions. This study aimed to assess whether an adjusted loading dose of clopidogrel could more effectively inhibit platelet aggregation in patients undergoing selected percutaneous coronary intervention.Methods A total of 205 patients undergoing selected percutaneous coronary intervention were enrolled in this multicenter, prospective, randomized study. Patients receiving domestic clopidogrel (n=104) served as the Talcom (Taijia)group; others (n=101) received Plavix, the Plavix group, Patients received up to 3 additional 300-mg loading doses of clopidogrel to decrease the adenosine phosphate-mediated platelet aggregation index by more than 50% (the primary endpoint) compared with the baseline. The secondary endpoint was major adverse cardiovascular events at 12 months.Results Compared with the rational loading dosage, the tailored loading dosage better inhibited platelet aggregation based on a >50% decrease in adenosine phosphate-mediated platelet aggregation (rational loading dosage vs. tailored loading dosage, 48% vs. 73%, P=0.028). There was no significant difference in the eligible index between the Talcom and Plavix groups (47% vs. 49% at 300 mg; 62% vs. 59% at 600 mg; 74% vs. 72% at 900 mg; P >0.05) based on a standard adenosine diphosphate-mediated platelet aggregation decrease of >50%. After 12 months of follow-up, there were no significant differences in major adverse cardiac events (2.5% vs. 2.9%, P=5.43). No acute or subacute stent thrombosis events occurred.Conclusion An adjusted loading dose of clopidogrel could have significant effects on antiplatelet aggregation compared with a rational dose, decreasing 1-year major adverse cardiac events in patients undergoing percutaneous coronary interventions based on adenosine phosphate-mediated platelet aggregation with no

  15. SDF-1α/CXCR4 Signaling in Lipid Rafts Induces Platelet Aggregation via PI3 Kinase-Dependent Akt Phosphorylation

    Science.gov (United States)

    Hayashi, Moyuru; Kaneda, Mizuho; Iida, Kazuko; Shimonaka, Motoyuki; Hara, Takahiko; Arai, Morio; Koike, Yuichi; Yamamoto, Naomasa; Kasahara, Kohji

    2017-01-01

    Stromal cell-derived factor-1α (SDF-1α)-induced platelet aggregation is mediated through its G protein-coupled receptor CXCR4 and phosphatidylinositol 3 kinase (PI3K). Here, we demonstrate that SDF-1α induces phosphorylation of Akt at Thr308 and Ser473 in human platelets. SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the CXCR4 antagonist AMD3100 or the PI3K inhibitor LY294002. SDF-1α also induces the phosphorylation of PDK1 at Ser241 (an upstream activator of Akt), GSK3β at Ser9 (a downstream substrate of Akt), and myosin light chain at Ser19 (a downstream element of the Akt signaling pathway). SDF-1α-induced platelet aggregation is inhibited by pretreatment with the Akt inhibitor MK-2206 in a dose-dependent manner. Furthermore, SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the raft-disrupting agent methyl-β-cyclodextrin. Sucrose density gradient analysis shows that 35% of CXCR4, 93% of the heterotrimeric G proteins Gαi-1, 91% of Gαi-2, 50% of Gβ and 4.0% of PI3Kβ, and 4.5% of Akt2 are localized in the detergent-resistant membrane raft fraction. These findings suggest that SDF-1α/CXCR4 signaling in lipid rafts induces platelet aggregation via PI3K-dependent Akt phosphorylation. PMID:28072855

  16. SDF-1α/CXCR4 Signaling in Lipid Rafts Induces Platelet Aggregation via PI3 Kinase-Dependent Akt Phosphorylation.

    Science.gov (United States)

    Ohtsuka, Hiroko; Iguchi, Tomohiro; Hayashi, Moyuru; Kaneda, Mizuho; Iida, Kazuko; Shimonaka, Motoyuki; Hara, Takahiko; Arai, Morio; Koike, Yuichi; Yamamoto, Naomasa; Kasahara, Kohji

    2017-01-01

    Stromal cell-derived factor-1α (SDF-1α)-induced platelet aggregation is mediated through its G protein-coupled receptor CXCR4 and phosphatidylinositol 3 kinase (PI3K). Here, we demonstrate that SDF-1α induces phosphorylation of Akt at Thr308 and Ser473 in human platelets. SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the CXCR4 antagonist AMD3100 or the PI3K inhibitor LY294002. SDF-1α also induces the phosphorylation of PDK1 at Ser241 (an upstream activator of Akt), GSK3β at Ser9 (a downstream substrate of Akt), and myosin light chain at Ser19 (a downstream element of the Akt signaling pathway). SDF-1α-induced platelet aggregation is inhibited by pretreatment with the Akt inhibitor MK-2206 in a dose-dependent manner. Furthermore, SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the raft-disrupting agent methyl-β-cyclodextrin. Sucrose density gradient analysis shows that 35% of CXCR4, 93% of the heterotrimeric G proteins Gαi-1, 91% of Gαi-2, 50% of Gβ and 4.0% of PI3Kβ, and 4.5% of Akt2 are localized in the detergent-resistant membrane raft fraction. These findings suggest that SDF-1α/CXCR4 signaling in lipid rafts induces platelet aggregation via PI3K-dependent Akt phosphorylation.

  17. The antidepressant 5-HT2A receptor antagonists pizotifen and cyproheptadine inhibit serotonin-enhanced platelet function.

    Directory of Open Access Journals (Sweden)

    Olivia A Lin

    Full Text Available There is considerable interest in defining new agents or targets for antithrombotic purposes. The 5-HT2A receptor is a G-protein coupled receptor (GPCR expressed on many cell types, and a known therapeutic target for many disease states. This serotonin receptor is also known to regulate platelet function. Thus, in our FDA-approved drug repurposing efforts, we investigated the antiplatelet activity of cyproheptadine and pizotifen, two antidepressant 5-HT2A Receptor antagonists. Our results revealed that cyproheptadine and pizotifen reversed serotonin-enhanced ADP-induced platelet aggregation in vitro and ex vivo. And the inhibitory effects of these two agents were found to be similar to that of EMD 281014, a 5-HT2A Receptor antagonist under development. In separate experiments, our studies revealed that these 5-HT2A receptor antagonists have the capacity to reduce serotonin-enhanced ADP-induced elevation in intracellular calcium levels and tyrosine phosphorylation. Using flow cytometry, we also observed that cyproheptadine, pizotifen, and EMD 281014 inhibited serotonin-enhanced ADP-induced phosphatidylserine (PS exposure, P-selectin expression, and glycoprotein IIb-IIIa activation. Furthermore, using a carotid artery thrombosis model, these agents prolonged the time for thrombotic occlusion in mice in vivo. Finally, the tail-bleeding time was investigated to assess the effect of cyproheptadine and pizotifen on hemostasis. Our findings indicated prolonged bleeding time in both cyproheptadine- and pizotifen-treated mice. Notably, the increases in occlusion and bleeding times associated with these two agents were comparable to that of EMD 281014, and to clopidogrel, a commonly used antiplatelet drug, again, in a fashion comparable to clopidogrel and EMD 281014. Collectively, our data indicate that the antidepressant 5-HT2A antagonists, cyproheptadine and pizotifen do exert antiplatelet and thromboprotective effects, but similar to clopidogrel and

  18. Salicylate antagonism of acetylsalicylic acid inhibition of platelet aggregation in male and female subjects: influence of citrate concentration.

    Science.gov (United States)

    Philp, R B; Paul, M L

    1986-01-01

    Platelets from volunteers were exposed for 1 min to sodium salicylate (SA) before and after the addition of acetylsalicylic acid (ASA) to produce greater than or equal to 50% inhibition of aggregation induced by arachidonic acid (AA) or collagen. SA:ASA concentrations = 20:1. SA protection against ASA inhibition was always observed even if ASA exposure time was 15 min, whereas reversal could not be demonstrated once exposure of platelets to ASA exceeded a minimum of 3-10 min with AA as the stimulus. Reversal was even less effective when collagen was the stimulus. An apparent, increased sensitivity to SA reversal of ASA inhibition in females disappeared when citrate concentration was adjusted to compensate for lower packed cell volume. The proposed male dependency for protection in ASA treatment of thromboembolic disorders cannot be explained on the basis of differences in the SA-ASA competition at platelet cyclooxygenase and, if collagen is an important in vivo stimulus of platelet interaction with damaged vessel wall, the antagonism of ASA by SA may not be important.

  19. Use of selective-serotonin reuptake inhibitors and platelet aggregation inhibitors among individuals with co-occurring atherosclerotic cardiovascular disease and depression or anxiety

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    J Douglas Thornton

    2016-12-01

    Full Text Available Objective: Medications commonly used to treat heart disease, anxiety, and depression can interact resulting in an increased risk of bleeding, warranting a cautious approach in medical decision making. This retrospective, descriptive study examined the prevalence and the factors associated with the use of both selective-serotonin reuptake inhibitor and platelet aggregation inhibitor among individuals with co-occurring atherosclerotic cardiovascular disease and anxiety or depression. Methods: Respondents aged 22 years and older, alive throughout the study period, and diagnosed with co-occurring atherosclerotic cardiovascular disease and anxiety or depression (n = 1507 in years 2007 through 2013 of the Medical Expenditures Panel Survey were included. The use of treatment was grouped as follows: selective-serotonin reuptake inhibitor and platelet aggregation inhibitor, selective-serotonin reuptake inhibitor or platelet aggregation inhibitor, and neither selective-serotonin reuptake inhibitor nor platelet aggregation inhibitor. Results: Overall, 16.5% used both selective-serotonin reuptake inhibitor and platelet aggregation inhibitor, 61.2% used selective-serotonin reuptake inhibitor or platelet aggregation inhibitor, and 22.3% used neither selective-serotonin reuptake inhibitor nor platelet aggregation inhibitor. Respondents aged over 65 years (adjusted odds ratio = 1.93 (95% confidence interval = 1.08–3.45 and having a diagnosis of diabetes (adjusted odds ratio = 1.63 (95% confidence interval = 1.15–2.31 and hypertension (adjusted odds ratio = 1.84 (95% confidence interval = 1.04–3.27 were more likely to be prescribed the combination. Conclusion: The drug interaction was prevalent in patients who are already at higher risk of health disparities and worse outcomes thus requiring vigilant evaluation.

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

    Directory of Open Access Journals (Sweden)

    Chen Yu

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

  1. Selective and rapid monitoring of dual platelet inhibition by aspirin and P2Y12 antagonists by using multiple electrode aggregometry

    Directory of Open Access Journals (Sweden)

    Lorenz Reinhard

    2010-05-01

    Full Text Available Abstract Background Poor platelet inhibition by aspirin or clopidogrel has been associated with adverse outcomes in patients with cardiovascular diseases. A reliable and facile assay to measure platelet inhibition after treatment with aspirin and a P2Y12 antagonist is lacking. Multiple electrode aggregometry (MEA, which is being increasingly used in clinical studies, is sensitive to platelet inhibition by aspirin and clopidogrel, but a critical evaluation of MEA monitoring of dual anti-platelet therapy with aspirin and P2Y12 antagonists is missing. Design and Methods By performing in vitro and ex vivo experiments, we evaluated in healthy subjects the feasibility of using MEA to monitor platelet inhibition of P2Y12 antagonists (clopidogrel in vivo, cangrelor in vitro and aspirin (100 mg per day in vivo, and 1 mM or 5.4 mM in vitro alone, and in combination. Statistical analyses were performed by the Mann-Whitney rank sum test, student' t-test, analysis of variance followed by the Holm-Sidak test, where appropriate. Results ADP-induced platelet aggregation in hirudin-anticoagulated blood was inhibited by 99.3 ± 1.4% by in vitro addition of cangrelor (100 nM; p 95% and 100 ± 3.2%, respectively (p in vitro or ex vivo. Oral intake of clopidogrel did not significantly reduce AA-induced aggregation, but P2Y12 blockade by cangrelor (100 nM in vitro diminished AA-stimulated aggregation by 53 ± 26% (p Conclusions Selective platelet inhibition by aspirin and P2Y12 antagonists alone and in combination can be rapidly measured by MEA. We suggest that dual anti-platelet therapy with these two types of anti-platelet drugs can be optimized individually by measuring platelet responsiveness to ADP and AA with MEA before and after drug intake.

  2. Abciximab treatment in vitro after aspirin treatment in vivo has additive effects on platelet aggregation, ATP release, and P-selectin expression.

    Science.gov (United States)

    Scazziota, A; Altman, R; Rouvier, J; Gonzalez, C; Ahmed, Z; Jeske, W P; Walenga, J M; Fareed, J

    2000-12-15

    To prevent arterial thrombosis, abciximab is administered together with aspirin. However, whether or not there are benefits to combine abciximab with aspirin is not yet well defined. Healthy volunteers were studied for the effect of aspirin + abciximab using sodium arachidonate and adenosine diphosphate (ADP) alone or in combination to induce platelet activation/aggregation. Abciximab produced complete inhibition of platelet aggregation induced with ADP but only 40% inhibition of aggregation induced by 0.75-mmol/l sodium arachidonate. Abciximab added in vitro to platelet-rich plasma (PRP) from platelets from aspirin-treated donors produced an almost complete inhibition of platelet aggregation. Aspirin, and abciximab alone, did not inhibit adenosine triphosphate (ATP) release as thoroughly as aspirin + abciximab did. Abciximab (3-5 microg/ml) produced inhibition of P-selectin expression induced with 5 (from 46.2 +/- 6.0% to 27.4 +/- 7.0%, P=0.002) and 20-micromol/l ADP (from 53.1 +/- 8.1% to 35.1 +/- 11.0%, P=0.019), but no effect was observed when 0.75-mmol/l sodium arachidonate was used (P=0.721). Aspirin diminished P-selectin expression in sodium arachidonate-stimulated platelets (from 77.7 +/- 11.8% to 40.2 +/- 3.6%, P<0.0001) in non-aspirinated and platelets from aspirin-treated donors, respectively. Abciximab (3, 4, and 5 microg/ml) added to platelets from aspirin-treated donors decreased P-selectin expression in platelets stimulated with sodium arachidonate from 40.2 +/- 8.6% to 25.6 +/- 11.5% (P=0.027), to 20.5 +/- 3.5% (P<0.0001), and to 22.5 +/- 1.8% (P<0.0001). We concluded that the antiplatelet effect of abciximab is greatly increased by aspirin.

  3. Effects of ticlopidine or ticlopidine plus aspirin on platelet aggregation and ATP release in normal volunteers: why aspirin improves ticlopidine antiplatelet activity.

    Science.gov (United States)

    Altman, R; Scazziota, A; Rouvier, J; Gonzalez, C

    1999-10-01

    Aspirin and ticlopidine are used to prevent arterial thrombosis. In some clinical settings ticlopidine is administered with aspirin for improving antithrombotic effect. We administered aspirin (100 mg/day), ticlopidine (500 mg/day), or ticlopidine and aspirin for 7 days to healthy volunteers. Platelet aggregation and ATP release induced by sodium arachidonate, ADP, or a combination of both were measured. Sodium arachidonate (0.25 mmol/L), which produces no platelet aggregation, combined with adenosine diphosphate (1 mumol/L), which produced a reversible platelet aggregation of 20% after ticlopidine, resulted in a synergistic platelet aggregation response in normal (74.6 +/- 9.2%) and in ticlopidine platelet-rich plasma (59.1% +/- 14.9%, p < 0.0001). Synergism after sodium arachidonate (0.75 mmol/L) plus adenosine diphosphate (4 mumol/L) fell from 75.8% +/- 11.0% and 59.1% +/- 15.6% after ticlopidine or aspirin, respectively, to 14.8% +/- 18.0% (p < 0.0001) after ticlopidine plus aspirin. Aspirin and ticlopidine alone did not inhibit adenosine triphosphate release as thoroughly as did aspirin plus ticlopidine. Aspirin or ticlopidine does not adequately prevent platelet activity as ticlopidine plus aspirin do. Addition of aspirin to treatment with ticlopidine improves their antiplatelet activity and better results could be obtained in arterial thrombotic prevention strategies.

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

    Science.gov (United States)

    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.

  5. One-step apexification using platelet rich fibrin matrix and mineral trioxide aggregate apical barrier

    Directory of Open Access Journals (Sweden)

    Anisha Kumar

    2014-01-01

    In one-step apexification using MTA, the technical problem encountered is controlling the overfill or underfill of MTA. The use of a matrix material helps to overcome this shortcoming. Platelet rich fibrin (PRF is an immune platelet concentrate, which can be used as a matrix, it also promotes wound healing and repair. This case report presents a case of one step apexification using MTA as an apical barrier and autologous PRF as an internal matrix.

  6. 粉防己碱对兔血小板聚集和血小板活化因子生成的影响%Effects of tetrandrine on rabbit platelet aggregation and platelet activating factor generation

    Institute of Scientific and Technical Information of China (English)

    张敏; 张乐之; 吕金胜

    1995-01-01

    目的:探讨粉防己碱(Tet)对兔血小板聚集和PAF生成的影响.方法:卡西霉素(Cal)和PAF诱导血小板聚集的聚集率和Tet对血小板聚集的抑制率被测定;给予或未给予Tet处理之血小板用Cal刺激释放PAF的量也被测定.结果:在4-64 μmol·L-1浓度范围,Tet明显抑制Cal和PAF诱导的血小板聚集.IC50值分别为8.6μmol·L-1和14.0μmol·L-1.Tet 也浓度依赖性的抑制Cal诱导血小板释放PAF,IC50值为21.0 μmol·L-1.结论:Tet抑制血小板聚集作用与抑制内源性PAF生成有关.%AIM: To study the effects of tetrandrine (Tet) on platelet aggregation and platelet activating factor (PAF) generation in rabbit platelet-rich plasma (PRP). METHODS:The aggregation rate of platelets induced by calcimycin (Cal) and PAF and the inhibition rate of Tet on platelet aggregation were measured. The amount of PAF in PRP stimulated with Cal and treated with Tet was also meaaggregation. At the final concentrations of 4PRP aggregation by Cal, there was a marked increase in PAF content. Tet dependented the release of PAF from platelets by Cal in a concentration-dependent manner, with IC50 of 21hibition effect of Tet on platelet aggregation might be concerned with the reduction of endogenous PAF generation.

  7. A Decreased Responsiveness of Platelet to Nitric Oxide in Cholesterol-Fed Rabbits

    Institute of Scientific and Technical Information of China (English)

    SUNJing; ZHANGAi-xia; LUOChun-xia; WANGWei; SUNYong-jun; ZHUDong-ya

    2004-01-01

    To determine whether endothelial dysfunction leads to an abnormal responsiveness of platelet to nitric oxide(NO)during the development of atherosclerosis. Methods:Rabbits were fed a 1% cholesterol chow for 12 weeks to induce atherosclerosis. Sermn NOx levels and the responsiveness of platelet to NO donor SNP were determined every 4 weeks during maintaining on a chow containing 1% cholesterol. The measurement of serum lipids and the examination of morphological feature and endothelial-dependent relaxation of aorta were performed after 12 weeks of cholesterol diet. Resu/ts.Cholesterol diet significantly increased sermn levels of cholesterol and LDL, caused a remarkable platelet hyperaggregability, and produced an evident endothelial dysfunction as indicated by the diminished vasorelaxation induced by acetylcholine and endothelial cell lesion as exhibited by scanning electron microscope examination. The percentage of inhibition of ADP-induced platelet aggregation by NO donor SNIP was significantly smaller in cholesterol chow group than that in normal chow group although no significant difference in serum NOx levels between normal and cholesterol chow group was observed throughout the development of atherosclexosis. :The present study suggests that the endothelial dysfunction caused by enhanced sermn cholesterol and LDL levels induces a decreased responsiveness of platelet to NO.

  8. [Induction of native platelets aggregation by incubation media of the UV irradiated leukocytes: possible role of the photo-induced ADP release].

    Science.gov (United States)

    Anosov, A K; Gorbach, M M

    2014-01-01

    It is shown that during incubation after UV irradiation (22-24 hours at 7-9 degrees C) irradiated isolated rabbit leukocytes release the compound(s) which induces platelets aggregation in the native platelet rich plasma. Treatment of the incubation media of irradiated leukocytes by heat (5 minutes at 100 degrees C) does not significantly change its pro-aggregation activity. Treatment of the platelet-rich plasma by the incubation media of irradiated leukocytes without stirring induces the refractoriness of platelets to ADP. The platelets treated by ADP without stirring do not react to the incubation media of irradiated leukocytes. The absorption spectrum of the incubation media of irradiated leukocytes has the maximum at 260 nm similar to that of the absorption spectra of ADP. It is possible that UVradiation induces the ADP release from leukocytes during post-irradiation incubation. Accumulation of this substance in the incubation media may be the cause of its pro-aggregation activity for native blood platelets.

  9. A novel pentapeptide targeting integrin β3-subunit inhibits platelet aggregation and its application in rat for thrombosis prevention

    Directory of Open Access Journals (Sweden)

    Qingrong eQu

    2016-03-01

    Full Text Available Background: Antiplatelet therapy plays a pivotal role in the prevention and treatment of thrombotic diseases. We reported the screening of P1C as a novel integrin-binding peptide from the C-terminal of connective tissue growth factor. Primary study indicated that P1C has potential against platelet aggregation. Objectives: In this study, we aimed to find the shortest active unit from the P1C fragments and explore its in vivo and in vitro activities. Methods: A series of truncated P1C fragments was prepared and screened for antiplatelet activity. The most active fragment was evaluated using coagulation assays. Flow cytometry and confocal microscopy were used to determine the interaction between the peptide and the integrin. The in vivo potential was further explored using two types of rat models. Results: From a series of truncated P1C forms, a so-called P1Cm peptide of 5-amino acids, namely, IRTPK, was screened out as the shortest active unit with superior activity. Coagulation experiments and an in vivo toxicity assay demonstrated that P1Cm is safe in vivo and inhibits ADP- and TH-induced human platelet aggregation in vitro in a concentration-dependent manner. Furthermore, it has limited effect on the coagulation parameters. Flow cytometry and confocal microscopy experiments consistently indicated that the peptide specifically binds the β3-subunit of integrin on platelets. Further experiments using rat models of artery-vein shunt and carotid arterial thrombosis illustrated that P1Cm can effectively prevent thrombosis formation. Conclusion: All the results suggested that P1Cm may be a new, promising antithrombotic alternative to currently available antiplatelet treatments.

  10. Effect of nano-clay platelets on the J-aggregation of thiacyanine dye organized in Langmuir-Blodgett films: A spectroscopic investigation

    Science.gov (United States)

    Bhattacharjee, D.; Hussain, Syed Arshad; Chakraborty, S.; Schoonheydt, R. A.

    2010-09-01

    In this paper we report the effect of the incorporation of nano-dimensional clay platelets, laponite, on the J-aggregation of a thiacyanine dye N, N'-dioctadecyl thiacyanine perchlorate (NK) assembled into Langmuir-Blodgett (LB) monolayers. π- A isotherms and atomic force microscopic studies confirm the successful incorporation of clay platelets into the Langmuir monolayer of NK. J-aggregates of NK remain present in LB films lifted at lower as well as higher surface pressures in the absence of laponite clay platelets. However, with the incorporation of clay platelets, J-aggregates are formed only in LB films lifted at higher surface pressure of 30 mN/m and totally absent in the films lifted at lower surface pressures of 10 and 15 mN/m. This may be due to the formation of nano-trapping level by overlapping of clay platelets at higher surface pressure. NK molecules may get squeezed to these nano-trapping to form J-aggregates.

  11. Increased platelet aggregation and turnover in the acute phase of ST-elevation myocardial infarction

    DEFF Research Database (Denmark)

    Jensen, Kristian Løkke Funck; Dalsgaard, Jens; Grove, Erik Lerkevang

    2013-01-01

    Newly produced platelets are present in the acute phase of ST-elevation myocardial infarction (STEMI). This may influence the antiplatelet effect of aspirin and clopidogrel administered prior to primary percutaneous coronary intervention (PPCI). The aims of this study were to investigate the anti......Newly produced platelets are present in the acute phase of ST-elevation myocardial infarction (STEMI). This may influence the antiplatelet effect of aspirin and clopidogrel administered prior to primary percutaneous coronary intervention (PPCI). The aims of this study were to investigate...

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

    Science.gov (United States)

    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.

  13. Heparin-induced platelet aggregation (H-IPA): dose/response relationship for two low molecular weight (LMW) heparin preparations (CY 216 and CY 222)

    Energy Technology Data Exchange (ETDEWEB)

    Brace, L.D.; Fareed, J.

    1986-03-01

    The authors have previously demonstrated that heparin and a LMW heparin derivative (PK 10169) causes platelet aggregation in a dose-dependent manner that can be inhibited by antagonists of the thromboxane pathway. Using fractions of these agents separated on the basis of molecular weight (MW) by gel permeation chromatography, the authors showed that H-IPA was directly dependent upon the MW of the agents tested. In order to further examine this MW dependence, the authors tested two other LMW heparin preparations, CY 216 and CY 222 and subfractions of these agents separated on the basis of MW. Citrate anticoagulated whole blood was drawn from drug-free normal healthy donors whose platelets aggregated when heparin was added to their platelet-rich plasma (PRP). PRP was prepared, various concentrations of the agents or their subfractions were added and aggregation was monitored for 40 minutes at 37/sup 0/C. The results demonstrate that like heparin and PK 10169, CY 216 and CY 222 caused platelet aggregation in a dose and MW dependent manner. Fractions with MW less than 2500 daltons caused aggregation only at concentrations exceeding the therapeutic range of the agents. The authors conclude that the ability to cause H-IPA is an inherent property of heparin and its fractions.

  14. Piperine Inhibits the Activities of Platelet Cytosolic Phospholipase A2 and Thromboxane A2 Synthase without Affecting Cyclooxygenase-1 Activity: Different Mechanisms of Action Are Involved in the Inhibition of Platelet Aggregation and Macrophage Inflammatory Response

    Directory of Open Access Journals (Sweden)

    Dong Ju Son

    2014-08-01

    Full Text Available PURPOSE: Piperine, a major alkaloid of black pepper (Piper nigrum and long pepper (Piper longum, was shown to have anti-inflammatory activity through the suppression of cyclooxygenase (COX-2 gene expression and enzyme activity. It is also reported to exhibit anti-platelet activity, but the mechanism underlying this action remains unknown. In this study, we investigated a putative anti-platelet aggregation mechanism involving arachidonic acid (AA metabolism and how this compares with the mechanism by which it inhibits macrophage inflammatory responses; METHODS: Rabbit platelets and murine macrophage RAW264.7 cells were treated with piperine, and the effect of piperine on the activity of AA-metabolizing enzymes, including cytosolic phospholipase A2 (cPLA2, COX-1, COX-2, and thromboxane A2 (TXA2 synthase, as well as its effect on AA liberation from the plasma membrane components, were assessed using isotopic labeling methods and enzyme immunoassay kit; RESULTS: Piperine significantly suppressed AA liberation by attenuating cPLA2 activity in collagen-stimulated platelets. It also significantly inhibited the activity of TXA2 synthase, but not of COX-1, in platelets. These results suggest that piperine inhibits platelet aggregation by attenuating cPLA2 and TXA2 synthase activities, rather than through the inhibition of COX-1 activity. On the other hand, piperine significantly inhibited lipopolysaccharide-induced generation of prostaglandin (PGE2 and PGD2 in RAW264.7 cells by suppressing the activity of COX-2, without effect on cPLA2; CONCLUSION: Our findings indicate that piperine inhibits platelet aggregation and macrophage inflammatory response by different mechanisms.

  15. A novel ranacyclin-like peptide with anti-platelet activity identified from skin secretions of the frog Amolops loloensis.

    Science.gov (United States)

    Hao, Xue; Tang, Xiaopeng; Luo, Lei; Wang, Yuming; Lai, Ren; Lu, Qiumin

    2016-01-15

    Albeit many bioactive peptides have been reported from amphibian skins, no anti-platelet peptide has been identified till to date. Here, an anti-platelet peptide, namely Zongdian platelet inhibitor (ZDPI), with the molecular weight of 1798.6 Da, was purified and characterized from skin secretions of the frog, Amolops loloensis. The amino acid sequence of ZDPI was determined as FRGCWLKNYSPRGCL-NH2 by combination methods of Edman degradation, mass spectrometry analysis and carboxypeptidase Y treatment revealing that it is composed of 15 amino acid residues with two cysteines formed an intra-molecular disulfide bridge and C-terminal amidation. cDNA encoding ZDPI precursor was cloned from skin cDNA library of A. loloensis. The precursor is composed of 63 amino acid (aa) residues including the predicted signal peptide (22 aa), an acidic spacer peptide (19 aa), and mature ZDPI. BLAST search indicates that ZDPI belongs to antimicrobial peptide family of ranacyclin, peptide leucine arginine or odorranain. It was found to inhibit ADP-induced platelet aggregation in a dose-dependent manner. At the concentration of 32 μg/ml, ZDPI completely inhibited platelet aggregation induced by ADP. To the best of our knowledge, this is the first report about an anti-platelet peptide from amphibian skin secretions. Considering its strong inhibitory ability on platelets and simple structure, ZDPI might be an excellent candidate or template to develop anti-thrombosis agent. In addition, the discovery of anti-platelet peptide in the frog skin increases biological function spectrum of amphibian skin peptides.

  16. Flavanols and Platelet Reactivity

    Directory of Open Access Journals (Sweden)

    Debra A. Pearson

    2005-01-01

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

  17. Enhanced Shear-induced Platelet Aggregation Due to Low-temperature Storage

    Science.gov (United States)

    2013-07-01

    pathogen inactivation technologies.4,5 In principle, storage of PLTs under refrigeration (4°C), which is standard practice for red blood cells (RBCs), can...by more than 100% (i.e., twofold) compared to freshly isolated PLTs at high shear rates. Effect of cell – cell collisions and fluid shear stress on...in aggregating stored PLTs. PLT aggregation under shear is controlled by cell – cell collision frequency and the force applied to the cells .26 These

  18. Effect of ginger (Zingiber officinale Rosc.) and fenugreek (Trigonella foenumgraecum L.) on blood lipids, blood sugar and platelet aggregation in patients with coronary artery disease.

    Science.gov (United States)

    Bordia, A; Verma, S K; Srivastava, K C

    1997-05-01

    In a placebo-controlled study the effect of ginger and fenugreek was examined on blood lipids, blood sugar, platelet aggregation, fibrinogen and fibrinolytic activity. The subjects included in this study were healthy individuals, patients with coronary artery disease (CAD), and patients with non-insulin-dependent diabetes mellitus (NIDDM) who either had CAD or were without CAD. In patients with CAD powdered ginger administered in a dose of 4 g daily for 3 months did not affect ADP- and epinephrine-induced platelet aggregation. Also, no change in the fibrinolytic activity and fibrinogen level was observed. However, a single dose of 10 g powdered ginger administered to CAD patients produced a significant reduction in platelet aggregation induced by the two agonists. Ginger did not affect the blood lipids and blood sugar. Fenugreek given in a dose of 2.5 g twice daily for 3 months to healthy individuals did not affect the blood lipids and blood sugar (fasting and post prandial). However, administered in the same daily dose for the same duration to CAD patients also with NIDDM, fenugreek decreased significantly the blood lipids (total cholesterol and triglycerides) without affecting the HDL-c. When administered in the same daily dose to NIDDM (non-CAD) patients (mild cases), fenugreek reduced significantly the blood sugar (fasting and post prandial). In severe NIDDM cases, blood sugar (both fasting and post prandial) was only slightly reduced. The changes were not significant. Fenugreek administration did not affect platelet aggregation, fibrinolytic activity and fibrinogen.

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

    Energy Technology Data Exchange (ETDEWEB)

    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. [Universidade Federal de São Paulo, Escola Paulista de Medicina, Departamento de Medicina, São Paulo, SP, Brasil, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil)

    2014-04-15

    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.

  20. The effect of different doses and different routes of acetylsalicylic acid administration on platelet aggregation in healthy volunteers and ischemic stroke patients.

    Science.gov (United States)

    Chýlová, Miroslava; Moťovská, Zuzana; Osmančík, Pavel; Procházka, Bohumír; Kalvach, Pavel

    2015-04-01

    The purpose was to assess the effect of different doses and different routes of acetylsalicylic acid (ASA) administration on platelet aggregation and the comparison between platelet aggregation after the single and the repetitive administration of ASA in healthy individuals and in patients after ischemic stroke. The study group consists of 22 healthy individuals and 30 patients with documented ischemic stroke. Platelet aggregation was measured in healthy individuals: (a) twice before ASA and (b) 2 h after different single doses and different routes of ASA administration-(b1) 500 mg orally, (b2) 500 mg intravenously, and (b3) 100 mg orally. We measured aggregability in healthy individuals after five consecutive days of 100 mg of ASA q.d. and in patients on chronic ASA 100 mg q.d. The VerifyNow was used with results expressed in aspirin reaction units (ARU). In healthy individuals, the dose-(b1) 500 mg orally-reduced the aggregability to mean (SD) 392 (36) ARU (p administration, and the same is true for the suppression after single dose of 500 mg orally and 100 mg orally (p = 0.011). Oral dose 100 mg for 5 days in healthy individuals reduced aggregation to 405 (37) and in post-stroke patients to 433 (54). All doses of ASA, both orally and intravenously, have produced a significant reduction of platelet aggregation. Preference of the parenteral to oral application has not been established.

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

    Science.gov (United States)

    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.

  2. 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.

    Science.gov (United States)

    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 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.

  3. Dual Roles of Quercetin in Platelets: Phosphoinositide-3-Kinase and MAP Kinases Inhibition, and cAMP-Dependent Vasodilator-Stimulated Phosphoprotein Stimulation

    Directory of Open Access Journals (Sweden)

    Won Jun Oh

    2012-01-01

    Full Text Available Background. Progressive diseases including cancer, metabolic, and cardiovascular disorders are marked by platelet activation and chronic inflammation. Studies suggest that dietary flavonoids such as quercetin possess antioxidant, anti-inflammatory, and antiplatelet properties, which could prevent various chronic diseases including atherosclerosis and thrombosis. However, the mechanism and the signaling pathway that links quercetin's antiplatelet activity with its anti-inflammatory property is limited and thus further exploration is required. The aim of this paper was to examine the link between antiplatelet and anti-inflammatory roles of quercetin in agonist-induced platelet activation. Methods. Quercetin effects on agonist-activated platelet-aggregation, granule-secretion, [Ca2+]i, and glycoprotein-IIb/IIIa activation were examined. Its effects on PI3K/Akt, VASP, and MAPK phosphorylations were also studied on collaged-activated platelets. Results. Quercetin dose dependently suppressed collagen, thrombin, or ADP-induced platelet aggregation. It significantly inhibited collagen-induced ATP release, P-selectin expression, [Ca2+]i mobilization, integrin-αIIbβ3 activation, and augmented cAMP and VASP levels. Moreover, quercetin attenuated PI3K, Akt, ERK2, JNK1, and p38 MAPK activations, which were supported by platelet-aggregation inhibition with the respective kinase inhibitors. Conclusion. Quercetin-mediated antiplatelet activity involves PI3K/Akt inactivation, cAMP elevation, and VASP stimulation that, in turn, suppresses MAPK phosphorylations. This result suggests quercetin may have a potential to treat cardiovascular diseases involving aberrant platelet activation and inflammation.

  4. Impact of reticulated platelets on antiplatelet response to thienopyridines is independent of platelet turnover.

    Science.gov (United States)

    Stratz, Christian; Nührenberg, Thomas; Amann, Michael; Cederqvist, Marco; Kleiner, Pascal; Valina, Christian M; Trenk, Dietmar; Neumann, Franz-Josef; Hochholzer, Willibald

    2016-10-28

    Reticulated platelets are associated with impaired antiplatelet response to thienopyridines. It is uncertain whether this interaction is caused by a decreased drug exposure due to high platelet turnover reflected by elevated levels of reticulated platelets or by intrinsic properties of reticulated platelets. This study sought to investigate if the impact of reticulated platelets on early antiplatelet response to thienopyridines is mainly caused by platelet turnover as previously suggested. Elective patients undergoing coronary intervention were randomised to loading with clopidogrel 600 mg or prasugrel 60 mg (n=200). Adenosine diphosphate (ADP)-induced platelet reactivity was determined by impedance aggregometry before, at 30, 60, 90, and 120 minutes and at day 1 after loading. Immature platelet count was assessed as marker of reticulated platelets by flow cytometry. Platelet reactivity increased with rising levels of immature platelet count in both groups. This effect was more distinctive in patients on clopidogrel as compared to patients on prasugrel. Overall, immature platelet count correlated well with on-treatment platelet reactivity at all time-points (p < 0.001). These correlations did not change over time in the entire cohort as well as in patients treated with clopidogrel or prasugrel indicating an effect independent of platelet turnover (comparison of correlations 120 minutes/day 1: p = 0.64). In conclusion, the association of immature platelet count with impaired antiplatelet response to thienopyridines is similar early and late after loading. This finding suggests as main underlying mechanism another effect of reticulated platelets on thienopyridines than platelet turnover.

  5. A novel dynamic layer-by-layer assembled nano-scale biointerface: functionality tests with platelet adhesion and aggregate morphology influenced by adenosine diphosphate.

    Science.gov (United States)

    Watson, Melanie G; Lopez, Juan M; Paun, Mihaela; Jones, Steven A

    2013-11-01

    An improved biointerface was developed, dynamic layer-by-layer self-assembly surface (d-LbL), and utilized as a biologically-active substrate for platelet adhesion and aggregation. Possible clinical applications for this research include improved anti-coagulation surfaces. This work demonstrated the functionality of d-LbL biointerfaces in the presence of platelet-rich-plasma (PRP) with the addition of 20 μM adenosine diphosphate (ADP), a thrombus activator. The surface morphology of the experimental control, plain PRP, was compared to PRP containing additional ADP (PRP + ADP) and resulted in an expected increase of platelet adhesions along the fibrinogen d-LbL substrate. The d-LbL process was used to coat glass slides with fibrinogen, Poly (sodium 4-styrene-sulfonate), and Poly (diallydimethlyammonium chloride). Slides were exposed to PRP under flow and static conditions with and without 20 μM of ADP. Fluorescence microscopy (FM), phase contrast microscopy (PCM), atomic force microscopy (AFM), and field emission-scanning electron microscopy (FE-SEM) were used to evaluate platelet adhesions under the influence of varied shear conditions. PCM images illustrated differences between the standard LbL and d-LbL substrates. FM images provided percent surface coverage values. For high-shear conditions, percent surface coverage values increased when using ADP whereas plain PRP exposure displayed no significant increase. AFM scans also displayed higher mean peak height values and unique surface characteristics for PRP + ADP as opposed to plain PRP. FE-SEM images revealed platelet adhesions along the biointerface and unique characteristics of the d-LbL surface. In conclusion, PRP + ADP was more effective at increasing platelet aggregation, especially under high shear conditions, providing further validation of the improved biointerface.

  6. Analgesic effect of parecoxib and flurbiprofen axetil for patients undergoing laparoscopic cholecystectomy and their influences on platelet aggregation

    Institute of Scientific and Technical Information of China (English)

    JI Fu-hai; JIN Xin; YANG Jian-ping; ZAN Li-li

    2010-01-01

    It is known that opioids produce postoperative analgesia,while it can also cause, especially in large doses, side effects like nausea, vomiting, constipation, syncope, skin itching, urinary retention and even respiratory inhibition.These factors have all greatly limited its clinical use for treating postoperative pain. Meanwhile, non-steroidal anti-inflammatory drags (NSAIDs) play an increasingly important role in postoperative analgesia. Some studies suggest that NSAIDS may be neural protective in cerebral ischemic conditions.1 Flurbiprofen axetil, which utilizes a lipid microsphere drag delivery system, may promote accumulation of flurbiprofen granular at inflammatory lesion sites and absorption by inflammatory cells,2 both factors which help to effectively target therapy. Parecoxib is the first selective cyclooxygenase-2 (COX-2) inhibitor available for intravenous injection, which is beneficial to patients susceptible to NSAIDs3 and those prone to gastrointestinal disturbances like perforation, ulcers, and bleeding.4 This investigation assesses the analgesic effect of parecoxib and flurbiprofen axetil for patients undergoing laparoscopic cholecystectomy and their influence on platelet aggregation in order to offer some guidance for clinic practice.

  7. Three new phenylpropanoids from the roots of Piper taiwanense and their inhibitory activities on platelet aggregation and Mycobacterium tuberculosis.

    Science.gov (United States)

    Chen, Si; Cheng, Ming-Jen; Wu, Chin-Chung; Peng, Chien-Fang; Huang, Hung-Yi; Chang, Hsun-Shuo; Wang, Chyi-Jia; Chen, Ih-Sheng

    2014-05-01

    Bioassay-guided fractionation of the active AcOEt-soluble fraction from the roots of Piper taiwanense has led to the isolation of two new phenylpropanoids, taiwanensols A and B (1 and 2, resp.), a new natural product, taiwanensol C (3), and 3-acetoxy-4-hydroxy-1-allylbenzene (4). The compounds were obtained as two isomer mixtures (1/2 and 3/4, resp.). Their structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. Compounds 1-4 were evaluated for their antiplatelet and antitubercular activities. The mixtures 1/2 and 3/4 showed potent inhibitory activities against platelet aggregation induced by collagen, with IC50 values of 35.2 and 8.8 μM, respectively. In addition, 1/2 and 3/4 showed antitubercular activities against Mycobacterium tuberculosis H37Rv, with MIC values of 30.0 and 48.0 μg/ml, respectively.

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

    Science.gov (United States)

    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.

  9. Tetrandrine differentially inhibits aggregation and ATP-release of rat platelets%粉防己碱特异抑制大鼠血小板聚集和ATP释放

    Institute of Scientific and Technical Information of China (English)

    陳一岳; 關超然; 許少珍

    1996-01-01

    To examine the effects of tetrandrine (Tet)on the aggregation and ATP-release of rat washed platelets induced by several platelet activators.METHODS: Gel-filtration (Sepharose 2B) was used to isolate washed platelets from adult rats and the platelet aggragation and ATP-release were measured simultaneously. RESULTS: In the presence of Ca2+ 1 mmol·L-1, Tet 300 μmol·L-1 inhibited the aggregation induced by ADP (25μmol· L- 1 ), collagen (2.5 g·L-1), and thrombin (103 unit·L-1)by 62 %, 60 %, and 34 %, respectively. It also inhibited arachidonic acid ( 1 mmol· L- 1 )-induced aggregation. Elevating intracellular Ca2+ concentration with the Ca2+ ionophore, calcimycin (30μmol· L-1), or by blocking the intracellular calcium pump with cyclopiazonic acid (5 μmol· L-1) initiated platelet aggregation, which was also inhibited by Tet. In Ca2 + -free medium, Tet still elicited an inhibitory effect on aggregation induced by ristocetin(2.5 g· L- 1). Lower concentrations of Tet (30nmol· L-1 to 3 μmol· L-1) failed to inhibit the aggregation (requiring Tet 10 - 300 μmol· L- 1 ), but strongly suppressed ATP-release induced by ADP 10μmol· L- 1, both of which were measured simultaneously in a single sample. CONCLUSION: Tet elicits a nonselective inhibitory effect on platelet aggregation not solely due to its Ca2+ antagonism and may act on a final common pathway leading to platelet aggregation. Furthermore, Tet is a much potent inhibitor of the release of ATP in platelets.

  10. Effects of Oxidized Low Density Lipoprotein and Native LDL on Low Shear-Induced Platelet Aggregation(Special Issue in Hornor of the Retirement of Professor Makoto Iwata at the Department of Neurology, Tokyo Women's Medical University)

    OpenAIRE

    矢野, 知佐子; 山崎, 昌子; 内山, 真一郎; 岩田, 誠; YANO, Chisako; YAMAZAKI, Masako; UCHIYAMA, Shinichiro; IWATA, Makoto

    2008-01-01

    Oxidized LDL (ox-LDL) is known to be closely associated with atherosclerosis, and it is one of the sources of oxidized cellular injury. Previous studies show that ox-LDL affects platelet aggregation. We studied the effects of ox-LDL on shear-induced platelet aggregation (SIPA) and compared it with native LDL. Methods: We incubated ox-LDL with LDL and CuSO_4 for 16 hours at 37℃. We incubated platelet-rich plasma (PRP) with ox-LDL or native LDL, and measured SIP A. And we compared the effect of...

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

    NARCIS (Netherlands)

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

    2006-01-01

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

  12. Platelet aggregation inhibitors in primary and secondary prevention of ischemic stroke

    Science.gov (United States)

    Gorenoi, Vitali; Kulp, Werner; Greiner, Wolfgang; von der Schulenburg, Johann-Matthias

    2006-01-01

    Background The ischaemic stroke (IS) is one of the most frequent cause of death in Germany. Besides of non-drug many drug-based interventions are used in primary or secondary prevention of IS, among them the thrombocyte aggregation inhibitors (TAI). Objectives The evaluation addresses the questions on medical efficacy and cost-effectiveness of the TAI administration in the prevention of IS as compared to the management of risk factors alone as well as to the use of anticoagulant drugs. Methods The literature search for articles published after 1997 was conducted in December 2003 in the most important medical and economic databases. The medical analysis was performed on the basis of the most up-to date meta-analyses of randomised controlled trials (RCT) as well as of new published RCT. The data from the studies for stroke, bleeding complications as well as for the combined endpoint "severe vascular events" (SVE: death or stroke or myocardial infarction) were summarised in meta-analyses. In order to include grey literature contact has been taken up with the pharmaceutical manufacturers of TAI. Results are presented in a descriptive way. Results The medical analysis included data from 184 RCT (vs. placebo) and from 22 RCT (vs. anticoagulant drugs). The absolute reduction of IS (4.8% vs. 6.6%; p<0,00001) and SVE (10.0% vs. 12.4%; p<0,00001) were definitely higher than the absolute increase of bleeding complications (1.6% vs. 0.9%; p<0,00001), but relatively similar to this absolute increase in a subpopulation with a low risk for SVE. With regard to the stroke prevention, evidence of efficacy could be yielded for acetylsalicil acid (ASA), dipyridamole, cilostazol, ridogrel and the combination ASA with dipyridamole. ASA is less effective than anticoagulants in the prevention of ischaemic stroke in atrial fibrillation, however, it causes fewer bleeding complications. Low dosed ASA can be considered cost-effective in secondary prevention of ischemic stroke, which is not

  13. 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.

    Science.gov (United States)

    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 (PLosartan 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.

  14. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study

    NARCIS (Netherlands)

    Hubbard, G.; Wolffram, S.; Vos, de C.H.; Bovy, A.G.; Gibbins, J.; Lovegrove, J.

    2006-01-01

    Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate t

  15. PL-11血小板分析仪检测血小板计数及聚集功能的性能评价%Performance evaluation of PL-11 platelet analyzer in the detection of platelet count and platelet aggregation

    Institute of Scientific and Technical Information of China (English)

    蔡玉婵; 赵旭鸿; 韩平; 陈昌明; 李智

    2015-01-01

    目的:探讨PL-11血小板分析仪在检测血小板数量及聚集功能方面的性能。方法按照美国临床实验室标准化协会( CLSI)制定的仪器性能验证标准及我国卫生行业标准 WS/T 406-2012《临床血液学检验常规项目分析质量要求》对PL-11血小板分析仪进行血小板计数及聚集功能的性能评价。采用PL-11血小板分析仪、LBY-NJ4血小板聚集仪及TEG-5000血栓弹力图仪检测健康人群血小板聚集率,分析各仪器检测结果间的相关性。结果 PL-11血小板分析仪的批内及日间精密度均<1/3总误差(7%);携带污染率为0.32%;在(4.12~1380.4)×109/L线性范围内回归方程斜率为1.03,R2=0.993;血小板计数结果与血小板参考方法的结果符合率为84%,均符合行业标准要求。分别采用PL-11血小板分析仪、LBY-NJ4血小板聚集仪及TEG-5000血栓弹力图仪检测79例2型糖尿病患者单服用氯匹格雷前、后血小板聚集率,3种仪器之间差异均无统计学意义( P>0.05),患者服药前、后血小板聚集率差异有统计学意义(P<0.01)。结论 PL-11血小板分析仪可为临床提供准确、可靠的血小板计数及聚集功能的检测结果。%Objective To investigate the performance of PL-11 platelet analyzer in the detection of platelet count and platelet aggregation.Methods According to the instrument performance verification standards in the Clinical and Laboratory Standards Institute ( CLSI) and the Health Industry Standard of the People′s Republic of China, WS/T 406-2012:the Quality Standard of Routine Tests in Clinical Hematology, the performance of PL-11 platelet analyzer in the detection of platelet count and platelet aggregation were evaluated.Platelet aggregation rate in healthy subjects was compared for correlation, which was detected by PL-11 platelet analyzer, LBY-NJ4 platelet tester and TEG-5000 thromboelastogram

  16. Inhibition of platelet aggregation by AZD6140, a reversible oral P2Y12 receptor antagonist, compared with clopidogrel in patients with acute coronary syndromes

    DEFF Research Database (Denmark)

    Storey, Robert F; Husted, Steen; Harrington, Robert A

    2007-01-01

    OBJECTIVES: In a substudy of DISPERSE (Dose confIrmation Study assessing anti-Platelet Effects of AZD6140 vs. clopidogRel in non-ST-segment Elevation myocardial infarction)-2, we compared the antiplatelet effects of AZD6140 and clopidogrel and assessed the effects of AZD6140 in clopidogrel......-pretreated patients. BACKGROUND: Clopidogrel, in combination with aspirin, reduces cardiovascular events in patients with acute coronary syndromes (ACS). However, patients with poor inhibition of platelet aggregation with clopidogrel may be less well protected. AZD6140 is a reversible oral P2Y(12) receptor antagonist...... that has been studied in ACS patients in comparison with clopidogrel (DISPERSE-2 study). METHODS: Patients were randomized to receive either AZD6140 90 mg twice a day, AZD6140 180 mg twice a day, or clopidogrel 75 mg once a day for up to 12 weeks in a double-blind, double-dummy design. One...

  17. Management of pulpal floor perforation and grade II Furcation involvement using mineral trioxide aggregate and platelet rich fibrin: A clinical report

    Directory of Open Access Journals (Sweden)

    Rhythm Bains

    2012-01-01

    Full Text Available To report the management of an iatrogenic perforation of pulpal floor in the furcation of mandibular first molar, using Mineral Trioxide Aggregate (MTA and platelet rich fibrin (PRF. Unpredictable endodontic root/pulp chamber floor perforations resulting in unacceptable high rate of clinical failure has now been a lesser threat with the advent of new technologies and biocompatible materials that utilize the applications of basic research along with tissue engineering concept in clinical practice. Present case report illustrates the use of MTA and platelet rich fibrin (PRF for the repair of the perforation defect and regeneration of the lost periodontium in furcation area. Although, histologic events and reaction of MTA with PRF is not studied so far, however, the autologous and biocompatible nature of the components used for present treatment modalities seems to be beneficial for the long term clinical results obtained in our case.

  18. Surface modification of CoCr alloy using varying concentrations of phosphoric and phosphonoacetic acids: albumin and fibrinogen adsorption, platelet adhesion, activation, and aggregation studies.

    Science.gov (United States)

    Thiruppathi, Eagappanath; Larson, Mark K; Mani, Gopinath

    2015-01-01

    CoCr alloy is commonly used in various cardiovascular medical devices for its excellent physical and mechanical properties. However, the formation of blood clots on the alloy surfaces is a serious concern. This research is focused on the surface modification of CoCr alloy using varying concentrations (1, 25, 50, 75, and 100 mM) of phosphoric acid (PA) and phosphonoacetic acid (PAA) to generate various surfaces with different wettability, chemistry, and roughness. Then, the adsorption of blood plasma proteins such as albumin and fibrinogen and the adhesion, activation, and aggregation of platelets with the various surfaces generated were investigated. Contact angle analysis showed PA and PAA coatings on CoCr provided a gradient of hydrophilic surfaces. FTIR showed PA and PAA were covalently bound to CoCr surface and formed different bonding configurations depending on the concentrations of coating solutions used. AFM showed the formation of homogeneous PA and PAA coatings on CoCr. The single and dual protein adsorption studies showed that the amount of albumin and fibrinogen adsorbed on the alloy surfaces strongly depend on the type of PA and PAA coatings prepared by different concentrations of coating solutions. All PA coated CoCr showed reduced platelet adhesion and activation when compared to control CoCr. Also, 75 and 100 mM PA-CoCr showed reduced platelet aggregation. For PAA coated CoCr, no significant difference in platelet adhesion and activation was observed between PAA coated CoCr and control CoCr. Thus, this study demonstrated that CoCr can be surface modified using PA for potentially reducing the formation of blood clots and improving the blood compatibility of the alloy.

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

    Directory of Open Access Journals (Sweden)

    Slattery, David E

    2009-08-01

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

  20. Antimicrobial, antioxidant, cytotoxicity and platelet aggregation inhibitory activity of a novel molecule isolated and characterized from mango ginger (Curcuma amada Roxb.) rhizome

    Indian Academy of Sciences (India)

    R S Policegoudra; K Rehna; L Jaganmohan Rao; S M Aradhya

    2010-06-01

    Mango ginger (Curcuma amada Roxb.) rhizome is used in the manufacture of pickles and other food preparations due to its unique raw mango flavour. The chloroform extract of mango ginger rhizome was subjected to antibacterial activity-guided purification by repeated silica gel column chromatography to obtain a pure compound. The structure of the isolated compound was deduced by analysing UV, IR, LC-MS and 2D-HMQCT NMR spectral data, and named it as amadaldehyde, a novel compound. It exhibited a wide range of antibacterial activity with potential bactericidal activity against several bacteria. The purified compound also exhibited antioxidant activity, cytotoxicity and platelet aggregation inhibitory activities.

  1. 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

    Directory of Open Access Journals (Sweden)

    Kavitarani B Rudagi

    2012-01-01

    Full Text Available 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.

  2. Experimental Study on Pharmacological Equivalence of Salvia Granules and Standard Decoction on the Anti-platelet Aggregation of Rabbits in vivo%丹参配方颗粒与标准煎剂体内抗家兔血小板聚集药理等效性研究

    Institute of Scientific and Technical Information of China (English)

    杜铁良; 赵自明; 陈玉兴; 崔景朝; 曾晓会; 黄雪君; 姚楠; 周瑞玲

    2011-01-01

    Objective; To study the pharmacological equivalence of Salvia granules and standard decoction on the anti-platelet aggregation of rabbits in vivo. Method: The rabbits were randomly divided into three groups and respectively given single oral dose of Salvia standard decoction (1/4-32 times of the clinical equivalent dose),Salvia granules ( 1/4-32 times of the clinical equivalent dose) and compound Salvia dropping pills ( 1/8-16 times of the clinical equivalent dose). The platelet aggregation inhibition rate at 1,3 and 5 min and the maximum platelet aggregation inhibition rate (MAIR) of the three groups were observed and compared. The dose equivalent effect ( DEE) and equivalent effect dose ( EED) of the three Salvia preparations were calculated in the comparable range by the dose-effect curves with MAIR as the effect indicator. Result; The three Salvia preparations all could significantly inhibit the ADP-induced platelet aggregation (P <0. 01) , and the effect of Salvia granules and compound Salvia dropping pills was both better than that of Salvia standard decoction (P < 0. 01 ). Within the MAIR limit of 47. 15% -63. 99% , DEESalvia Granules ( mg · kg-1 ) = - 62. 432 + 0. 115 × DEESalvis standara decoction (mg·kg-1 ) ,and in the range of 1/4-2 times the clinical equivalent dose (175-1 400 mg·kg-1 ) ,EEDSalvia granules ( % ) = 30. 558 + 0. 775 × EEDSalvis standara decoction (%). Conclusion: Within the certain range of doses, the effect of Salvia granules on anti-platelet aggregation is lower than that of compound Salvia dropping pills, while better than that of Salvia standard decoction at the same dose.%目的:观察丹参配方颗粒与丹参标准煎剂体内抗血小板聚集效应的药理等效性.方法:对比观察8个剂量丹参标准煎剂(1/4~32倍临床等效剂量)、丹参配方颗粒(1/4~32倍临床等效剂量)和复方丹参滴丸(1/8 ~16倍)一次口服给药后对家兔血小板1,3,5 min和最大聚集抑制率(MAIR)的影响,并

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

    Science.gov (United States)

    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.

  4. 蒺藜总黄酮对大鼠血小板黏附和聚集功能的影响%Effects of total flavonoid glycosides of Tribulus terrestris L.on platelet adherence and aggregation function in rats

    Institute of Scientific and Technical Information of China (English)

    王云; 韩继举; 赵晓民; 吴亚平; 冯蕾

    2011-01-01

    目的:探讨蒺藜总黄酮对血小板黏附和聚集功能的影响.方法:选用不同药物浓度,采用体外血液灌流的方法,在低切变率下观察血小板在胶原蛋白表面上的黏附形态,计算黏附面积;利用血小板聚集仪,以二磷酸腺苷诱导大鼠血小板聚集,测定血小板最大聚集率.结果:不同浓度的蒺藜总黄酮均能明显降低血小板在胶原蛋白表面上的黏附面积(P<0.01),对照组血小板的黏附聚集成团,实验组则疏松散在或单个黏附;血小板最大聚集率在蒺藜总黄酮高、中剂量组也显著下降(P<0.01).结论:蒺藜总黄酮具有显著抑制血小板黏附和聚集的作用.%OBJECTIVE To observe the effects of Tribulus terrestris L. On platelet adherence and aggregation function. METHODS Under different concentration of the drug, the adherence appearance of platelet on collagen protein were observed and calculated the area by hemoperfusion in vitro at low shear rate; adenosine diphosphate was used to induce platelet aggregation and the maximum ratio of platelet aggregation was detected. RESULTS Total flavonoid glycosides of Tribulus terrestris L. Reduced platelet adherence area on collagen surface significantly (P<0. 01). In control group, platelet agglutinated into pieces and single platelet was rare. In experimental group, the platelet adhered loosely and there were many single spreading triangle or polygon platelets. The maximum ratio of platelet aggregation decreased significantly at higher concentration of the drug (P<0. 01). CONCLUSION The results suggest that total flavonoid glycosides of Tribulus terrestris L. Can inhibit experimental platelet adherence and aggregation.

  5. Homers regulate calcium entry and aggregation in human platelets: a role for Homers in the association between STIM1 and Orai1.

    Science.gov (United States)

    Jardin, Isaac; Albarrán, Letizia; Bermejo, Nuria; Salido, Ginés M; Rosado, Juan A

    2012-07-01

    Homer is a family of cytoplasmic adaptor proteins that play different roles in cell function, including the regulation of G-protein-coupled receptors. These proteins contain an Ena (Enabled)/VASP (vasodilator-stimulated phosphoprotein) homology 1 domain that binds to the PPXXF sequence motif, which is present in different Ca²⁺-handling proteins such as IP3 (inositol 1,4,5-trisphosphate) receptors and TRPC (transient receptor potential canonical) channels. In the present study we show evidence for a role of Homer proteins in the STIM1 (stromal interaction molecule 1)-Orai1 association, as well as in the TRPC1-IP3RII (type II IP3 receptor) interaction, which might be of relevance in platelet function. Treatment of human platelets with thapsigargin or thrombin results in a Ca²⁺-independent association of Homer1 with TRPC1 and IP3RII. In addition, thapsigargin and thrombin enhanced the association of Homer1 with STIM1 and Orai1 in a Ca²⁺-dependent manner. Interference with Homer function by introduction of the synthetic PPKKFR peptide into cells, which emulates the proline-rich sequences of the PPXXF motif, reduced STIM1-Orai1 and TRPC1- IP3RII associations, as compared with the introduction of the inactive PPKKRR peptide. The PPKKFR peptide attenuates thrombin-evoked Ca²⁺ entry and the maintenance of thapsigargin-induced store-operated Ca²⁺ entry. Finally, the PPKKFR peptide attenuated thrombin-induced platelet aggregation. The findings of the present study support an important role for Homer proteins in thrombin-stimulated platelet function, which is likely to be mediated by the support of agonist-induced Ca²⁺ entry.

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

    Science.gov (United States)

    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.

  7. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev

    2014-09-01

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

  8. Calcium-dependent synergistic interaction of platelet activating factor and epinephrine in human platelet aggregation%血小板活化因子和肾上腺素对人血小板凝集的钙依赖性协同作用

    Institute of Scientific and Technical Information of China (English)

    Sheikh Arshad SAEED; Huma RASHEED

    2003-01-01

    AIM: To investigate the mechanism (s) involved in the synergistic interaction of platelet activating factor (PAF) and epinephrine. METHODS: Blood was obtained from healthy human subjects reported to be free of medications for at least two weeks before sampling. Aggregation was monitored at 37 ℃ using Dual-channel Lumi-aggregometer.The resulting aggregation was recorded for 5 min by the measurement of light transmission as a function of time.RESULTS: Platelet aggregation mediated by subthreshold concentrations of PAF (5-8 nmol/L) plus epinephrine (0.5-2 μmol/L) was inhibited by α2-receptor blocker, yohimbine, and PAF receptor antagonist WEB 2086. This synergism was inhibited by calcium channel blockers, verapamil and diltiazem. In addition, platelet aggregation by co-addition of PAF and epinephrine was also inhibited by very low concentrations of phospholipase C (PLC)inhibitor (U73122; IC50=0.2 μmol/L), the MAP kinase inhibitor, PD 98059 (IC50=3 μmol/L), and cyclooxygenase (COX-1) inhibitors including indomethacin (IC50=0.25 μmol/L), flurbiprofen (IC50=0.7 μmol/L), and piroxicam (IC50=7 μmol/L). However, COX-2 inhibitors, nimesulide (IC50=26 μmol/L), NS-398 (IC50=7 μmol/L), and etodolac (IC50=15 μmol/L) were also effective in inhibiting the aggregation. The inhibitors of protein kinase C (chelerythrine)and tyrosine kinase (genistien), and phosphatidylinositol 3-kinase inhibitor (wortmannin) had no significant effect on platelet aggregation induced by PAF and epinephrine. CONCLUSION: The synergistic effect of PAF and epinephrine on human platelet aggregation is receptor-mediated and involves the activation of PLC/Ca2+, COX and MAP kinase signalling pathways.

  9. Combined blockade of ADP receptors and PI3-kinase p110β fully prevents platelet and leukocyte activation during hypothermic extracorporeal circulation.

    Directory of Open Access Journals (Sweden)

    Stefanie Krajewski

    Full Text Available Extracorporeal circulation (ECC and hypothermia are used to maintain stable circulatory parameters and improve the ischemia tolerance of patients in cardiac surgery. However, ECC and hypothermia induce activation mechanisms in platelets and leukocytes, which are mediated by the platelet agonist ADP and the phosphoinositide-3-kinase (PI3K p110β. Under clinical conditions these processes are associated with life-threatening complications including thromboembolism and inflammation. This study analyzes effects of ADP receptor P(2Y(12 and P(2Y(1 blockade and PI3K p110β inhibition on platelets and granulocytes during hypothermic ECC. Human blood was treated with the P(2Y(12 antagonist 2-MeSAMP, the P(2Y(1 antagonist MRS2179, the PI3K p110β inhibitor TGX-221, combinations thereof, or PBS and propylene glycol (controls. Under static in vitro conditions a concentration-dependent effect regarding the inhibition of ADP-induced platelet activation was found using 2-MeSAMP or TGX-221. Further inhibition of ADP-mediated effects was achieved with MRS2179. Next, blood was circulated in an ex vivo ECC model at 28°C for 30 minutes and various platelet and granulocyte markers were investigated using flow cytometry, ELISA and platelet count analysis. GPIIb/IIIa activation induced by hypothermic ECC was inhibited using TGX-221 alone or in combination with P(2Y blockers (p<0.05, while no effect of hypothermic ECC or antiplatelet agents on GPIIb/IIIa and GPIbα expression and von Willebrand factor binding was observed. Sole P(2Y and PI3K blockade or a combination thereof inhibited P-selectin expression on platelets and platelet-derived microparticles during hypothermic ECC (p<0.05. P(2Y blockade alone or combined with TGX-221 prevented ECC-induced platelet-granulocyte aggregate formation (p<0.05. Platelet adhesion to the ECC surface, platelet loss and Mac-1 expression on granulocytes were inhibited by combined P(2Y and PI3K blockade (p<0.05. Combined blockade of P

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

    Science.gov (United States)

    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.

  11. Continuation of medically necessary platelet aggregation inhibitors - acetylsalicylic acid and clopidogrel - during surgery for spinal degenerative disorders: Results in 100 patients

    Directory of Open Access Journals (Sweden)

    Reza Akhavan-Sigari

    2014-01-01

    Full Text Available Background: Patients undergoing spinal surgery while under anticoagulation therapy are at risk of developing bleeding complications, even though lower incidences have been reported for joint arthroplasty surgery. There is a gap in the medical literature examining the incidence of postoperative spinal bleeding in patients who were under anticoagulation medication at the time of surgery. Methods: We prospectively followed a consecutive cohort of 100 patients (58 male, 42 female undergoing spinal surgery. The average patient age was 48.7 years and the minimum follow up time was 12 months. Diagnosis was lumbar spinal stenosis in 20, herniated lumbar discs in 63, degenerative cervical disc disease in 3, and cervical disc herniation in 14 cases. In our study, platelet aggregation inhibitors (clopidogrel and/or acetylsalicylic acid were given for the treatment of cardiovascular and cerebrovascular thrombotic events, to reduce risk of stroke in patients who have had transient ischemia of the brain or acute coronary syndrome, and as secondary prevention of atherosclerotic events (fatal or nonfatal myocardial infarction (MI. A cessation of anticoagulants (acetylsalicylic acid or clopidogrel in our patients in the peri- and postoperative period was contraindicated. Results: Sixty-three patients were on both clopidogrel and acetylsalicylic acid and 37 on acetylsalicylic acid only. None of the patients suffered any postoperative bleeding complication. Three patients suffered postoperative wound dehiscence and one patient had an infection that required reoperation. Conclusion: The question of whether preoperative platelet aggregation inhibitors must be stopped before elective spinal surgery has never been answered in the literature. In our prospective series, we have found no increase in the risk of postoperative spinal bleeding with the use of clopidogrel or acetylsalicylic acid. This finding suggests that spine surgery can be done without stopping

  12. LpMab-12 Established by CasMab Technology Specifically Detects Sialylated O-Glycan on Thr52 of Platelet Aggregation-Stimulating Domain of Human Podoplanin.

    Directory of Open Access Journals (Sweden)

    Yukinari Kato

    Full Text Available Podoplanin (PDPN, also known as Aggrus, possesses three tandem repeat of platelet aggregation-stimulating (PLAG domains in its N-terminus. Among the PLAG domains, sialylated O-glycan on Thr52 of PLAG3 is essential for the binding to C-type lectin-like receptor-2 (CLEC-2 and the platelet-aggregating activity of human PDPN (hPDPN. Although various anti-hPDPN monoclonal antibodies (mAbs have been generated, no specific mAb has been reported to target the epitope containing glycosylated Thr52. We recently established CasMab technology to develop mAbs against glycosylated membrane proteins. Herein, we report the development of a novel anti-glycopeptide mAb (GpMab, LpMab-12. LpMab-12 detected endogenous hPDPN by flow cytometry. Immunohistochemical analyses also showed that hPDPN-expressing lymphatic endothelial and cancer cells were clearly labeled by LpMab-12. The minimal epitope of LpMab-12 was identified as Asp49-Pro53 of hPDPN. Furthermore, LpMab-12 reacted with the synthetic glycopeptide of hPDPN, corresponding to 38-54 amino acids (hpp3854: 38-EGGVAMPGAEDDVVTPG-54, which carries α2-6 sialylated N-acetyl-D-galactosamine (GalNAc on Thr52. LpMab-12 did not recognize non-sialylated GalNAc-attached glycopeptide, indicating that sialylated GalNAc on Thr52 is necessary for the binding of LpMab-12 to hPDPN. Thus, LpMab-12 could serve as a new diagnostic tool for determining whether hPDPN possesses the sialylation on Thr52, a site-specific post-translational modification critical for the hPDPN association with CLEC-2.

  13. Inhibitory effects of Tabebuia impetiginosa inner bark extract on platelet aggregation and vascular smooth muscle cell proliferation through suppressions of arachidonic acid liberation and ERK1/2 MAPK activation.

    Science.gov (United States)

    Son, Dong-Ju; Lim, Yong; Park, Young-Hyun; Chang, Sung-Keun; Yun, Yeo-Pyo; Hong, Jin-Tae; Takeoka, Gary R; Lee, Kwang-Geun; Lee, Sung-Eun; Kim, Mi-Ran; Kim, Jeong-Han; Park, Byeoung-Soo

    2006-11-03

    The antiplatelet and antiproliferative activities of extract of Tabebuia impetiginosa inner bark (taheebo) were investigated using washed rabbit platelets and cultured rat aortic vascular smooth muscle cells (VSMCs) in vitro. n-Hexane, chloroform and ethyl acetate fractions showed marked and selective inhibition of platelet aggregation induced by collagen and arachidonic acid (AA) in a dose-dependent manner. These fractions, especially the chloroform fraction, also significantly suppressed AA liberation induced by collagen in [(3)H]AA-labeled rabbit platelets. The fractions, especially the chloroform fraction, potently inhibited cell proliferation and DNA synthesis induced by platelet derived growth factor (PDGF)-BB, and inhibited the levels of phosphorylated extracellular signal regulated kinase (ERK1/2) mitogen activated protein kinase (MAPK) stimulated by PDGF-BB, in the same concentration range that inhibits VSMC proliferation and DNA synthesis.

  14. New organic nitrate-containing benzyloxy isonipecotanilide derivatives with vasodilatory and anti-platelet activity.

    Science.gov (United States)

    de Candia, Modesto; Marini, Elisabetta; Zaetta, Giorgia; Cellamare, Saverio; Di Stilo, Antonella; Altomare, Cosimo D

    2015-05-25

    A number of new nitric oxide (NO)-precursors were synthesized by grafting nitrate-containing moieties on the structures of the benzyloxy isonipecotanilide derivatives 1 and 2 already reported as moderately potent antiplatelet agents. Various nitrooxy (ONO2)-alkyl side chains were covalently linked to the piperidine nitrogen of the parent compounds through carbamate and amide linkage, and the synthesis of a benzyl nitrate analog (15) of compound 1 was also achieved. The in vitro vasodilatory activities, as well as platelet anti-aggregatory effects, of the newly synthesized organic nitrates were assessed. The (ONO2)methyl carbamate-based derivative 5a and the benzyl nitrate analog 15, which on the other hand retain activity as inhibitors of ADP-induced platelet aggregation, exhibited strong NO-mediated vasodilatory effects on pre-contracted rat aorta strips, with EC50 values in the low nanomolar range (13 and 29 nM, respectively). Experiments carried out with the selectively inhibited soluble guanylate cyclase (sGC), which is the key enzyme of the NO-mediated pathway leading to vascular smooth muscle relaxation, confirmed the involvement of NO in the observed vasodilation. The nitrate derivatives proved to be stable in acidic aqueous solution and at pH 7.4. In human serum, unlike 5a, which showed not to undergo enzyme-catalyzed decomposition, the other tested (ONO2)-alkyl carbamate-based compounds (5b and 5e) and benzyl nitrate 15 underwent a faster degradation. However, their decomposition rates in serum were quite slow (t½>2.6 h), which suggests that nitrate moiety is poorly metabolized in blood plasma and that much of the in vitro anti-platelet activity has to be attributed to the intact (ONO2)-containing molecules.

  15. 猪链球菌溶血素(SLY)引起血小板聚集活性分析%Activity identification of Streptococcus suis suilysin inducing platelets aggregation

    Institute of Scientific and Technical Information of China (English)

    张省委; 刘鹏; 徐茂凯; 尚学义; 郑玉玲; 袁媛; 姜永强

    2016-01-01

    目的:研究重组表达的2型猪链球菌溶血素( SLY)与血小板的相互作用,为临床猪链球菌感染的救治提供理论基础。方法镍柱亲和层析法纯化重组SLY蛋白,光密度法检测其溶血活性,再通过血小板聚集仪和扫描电子显微镜观察SLY蛋白与血小板的相互作用,并研究抗血小板药物阿司匹林对SLY引起的血小板聚集的影响,通过比较野生株05ZYH33和sly基因突变株Δsly对小鼠体内血小板体积和数量的影响,推测SLY蛋白对体内血小板的影响。结果与结论重组SLY蛋白溶血活性为2000 HU,1μg/ml SLY蛋白可引起血小板高度聚集,5 mmol/L阿司匹林可显著抑制聚集,SLY蛋白可引起小鼠体内单个血小板体积增大和血小板数量减少。%Objective To explore the interaction of streptococcus suis serotype 2 recombinant suilysin ( SLY ) with platelets, and provide the theoretical basis for clinic treatment of patients infected with S.suis.Methods The nickel column affinity chromatography was used to purify the recombinant SLY.The hemolytic acivity was identified by optical density before the platelets aggregation induced by a SLY was detected by a platelet aggregometer or electron microscope and the effect of aspirin on platelets aggregation was analyzed.The impact of wild type 05ZYH33 and sly-deficient mutant strainΔSLY on platelets of mice was compared to predict the interaction of the SLY with platelets in vivo.Results and Conclusion Hemolytic activity of recombinant SLY was 2000 hemolytic units( HU) and platelets aggregation was induced at 1 μg/ml.The aggregation can be inhibited by aspirin in 5 mmol/L.SLY can also increase the volume and reduce the amount of platelets in mice.

  16. Effects of fused hirudin on activity of thrombin and function of platelets

    Institute of Scientific and Technical Information of China (English)

    SHEN Li; CHEN Shao-ping; CAI Zai-long; YANG Sheng-sheng; QIN Yong-wen

    2005-01-01

    Objective: To investigate whether fused hirudin peptide has both antithrombin and antiplatelet functions. Methods: The core region of fused hirudin was the C-terminal tail of hirudin(hirudin53-64),which could bind to the anion binding exosite (ABE) of thrombin.Arg-Pro-Pro-Gly-Phe(RPPGF) amino acid sequence,a metabolite of bradykinin,was added to the N-terminus of hirudin53-64.It bound to the active site of thrombin.Additionally,Arg-Gly-Asp(RGD)amino acid sequence,an inibitor of glycoprotein Ⅱb/Ⅲa( GP Ⅱb/Ⅲa) receptor,was linked to C-terminus of hirudin53-64.This 26-animo acid-fused hirudin peptide was artificially synthesized,purified and analysed. Results: Fused hirudin peptide significantly lengthened the activated partial thromboplastin time(APTT),thrombin time(TT)and prothrombin time(PT) and inhibited the amidolytic activity of thrombin.The ADP-induced platelet aggregation was markedly inhibited by fused hirudin peptide. Conclusion: Fused hirudin peptide has activity of antithrombin as well as antiplatelet.Therefore bifunctional anticoagulation peptide has capacity to target various components of haemostatic process and may become more powerful antithrombosis agent.

  17. Platelet Donation

    Science.gov (United States)

    ... For Hospitals Home > Platelet Donation Printable Version Platelet Donation Sign Up to Donate Platelets Everything you need ... Platelets Explained in Two Minutes Why Your Platelet Donation Matters Cassie Brabb descibes how it felt to ...

  18. Betaine (N,N,N-trimethylglycine) averts photochemically-induced thrombosis in pial microvessels in vivo and platelet aggregation in vitro.

    Science.gov (United States)

    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 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.

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

    Directory of Open Access Journals (Sweden)

    Andrezza C Chagas

    2014-06-01

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

  20. Experimental study on the anti-platelet aggregation and anti-coagulant activity of isoliensinine%异莲心碱抗血小板聚集和抗凝血作用

    Institute of Scientific and Technical Information of China (English)

    陈灵骏; 罗顺德

    2011-01-01

    目的:探讨异莲心碱(isoliensinine,IL)对大鼠体内血小板聚集和凝血功能的影响.方法:以二磷酸腺苷(ADP)诱导血小板聚集,采用比浊法观察IL对兔体内外血小板1,3,5 min聚集率和最大聚集率的影响,同时评价IL对大鼠凝血酶原时间(PT)、活化部分凝血激酶时间(APTT)及凝血酶时间(TT)的影响.结果:IL4 mg·L-1和8 mg·L-1能显著抑制ADP诱导的兔体外血小板1,3,5 min聚集率和最大聚集率,其抑制率为14.4%和27.9%;IL5 mg·kg-1和10 mg·kg-1能显著抑制ADP诱导的兔体内血小板1,3,5 min聚集率和最大聚集率,其抑制率为20.0%和32.6%; IL能显著延长大鼠PT,APTT和TT.结论:IL具有对抗血小板聚集和凝血作用.%OBJECTIVE To investigate the inhibitory effects of isoliensinine on platelet aggregation in rabbits and coagulation function in rats. METHODS Inhibition rates of platelet aggregation for isoliensinine in vivo and vitro were determined by the model of platelet aggregation induced by adenosine diphosphate. The effects of isoliensinine were also evaluated on pro-thrombin time (PT) , activated partial thromboplastin time (APTT) and thrombin time (TT). RESULTS Isoliensinine inhibited platelet aggregation in vitro at the concentration of 4 and 8 mg·L-1 , inhibition rates were 14. 4% and 27. 9%. Isoliensinine inhibited platelet aggregation in vivo at the concentration of 5 and 10 mg·kg-1 , inhibition rates were 20. 0% and 32. 6%. Isoliensinine also markedly prolonged PT, APTT and TT also. CONCLUSION Isoliensinine exerted remarkable effects against platelet aggregation and coagulation in animal study.

  1. Platelet surface glutathione reductase-like activity.

    Science.gov (United States)

    Essex, David W; Li, Mengru; Feinman, Richard D; Miller, Anna

    2004-09-01

    We previously found that reduced glutathione (GSH) or a mixture of GSH/glutathione disulfide (GSSG) potentiated platelet aggregation. We here report that GSSG, when added to platelets alone, also potentiates platelet aggregation. Most of the GSSG was converted to GSH by a flavoprotein-dependent platelet surface mechanism. This provided an appropriate redox potential for platelet activation. The addition of GSSG to platelets generated sulfhydryls in the beta subunit of the alpha(IIb)beta(3) fibrinogen receptor, suggesting a mechanism for facilitation of agonist-induced platelet activation.

  2. Cisplatin triggers platelet activation.

    Science.gov (United States)

    Togna, G I; Togna, A R; Franconi, M; Caprino, L

    2000-09-01

    Clinical observations suggest that anticancer drugs could contribute to the thrombotic complications of malignancy in treated patients. Thrombotic microangiopathy, myocardial infarction, and cerebrovascular thrombotic events have been reported for cisplatin, a drug widely used in the treatment of many solid tumours. The aim of this study is to explore in vitro cisplatin effect on human platelet reactivity in order to define the potentially active role of platelets in the pathogenesis of cisplatin-induced thrombotic complications. Our results demonstrate that cisplatin increases human platelet reactivity (onset of platelet aggregation wave and thromboxane production) to non-aggregating concentrations of the agonists involving arachidonic acid metabolism. Direct or indirect activation of platelet phospholipase A(2) appears to be implicated. This finding contributes to a better understanding of the pathogenesis of thrombotic complications occurring during cisplatin-based chemotherapy.

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

    Science.gov (United States)

    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 bamboo group (P bamboo and OVX-green tea groups compared with that in the OVX-control (P bamboo leaves groups recovered bone density to some extent. The results show that ovariectomy caused an increase in body weight and liver triglycerides, and that green tea was effective for lowering body weight and triglycerides in OVX rats. Ovariectomy induced an increase in Na efflux via Na-K ATPase and a decrease in Na efflux via Na-K cotransport. Furthermore, consumption of green tea and bamboo leaves affected Na efflux channels, controlling electrolyte and body water balance.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Effect of Acetic Acid and Low Molecular Weight Component of Mature Vinegar on Platelet Aggregation%醋酸及陈醋低分子量成分的抗血小板聚集活性

    Institute of Scientific and Technical Information of China (English)

    何璐薇; 李志敏; 孙严; 张艳艳; 范俊峰

    2012-01-01

    The effects of acetic acid and low molecular weight component of mature vinegar on platelet aggregation induced by arachidonic acid and collagen were assayed. Results showed that the maximal inhibition rate of acetic acid on platelet aggregation induced by collagen was 75. 95% and the minimum concentration of acetic acid which could inhibit the aggregation rate was 0. 05mol/L while the maximal inhibition rate of acetic acid on platelet aggregation induced by arachidonic acid was 83.62% and the minimum concentration acetic acid was 0. 01 mol/L Compared with the control group, acetic acid and low molecular weight component of mature vinegar independently inhibited the platelet aggregation induced by arachidonic acid and collagen obviously, and the effect of acetic acid on platelet aggregation induced by arachidonic acid was greater than collagen.%以食醋中的醋酸和陈醋低分子成分为研究对象,评价其对由花生四烯酸和胶原诱导的血小板聚集反应的影响。结果表明,醋酸对由胶原诱导的血小板聚集的最大抑制率为75.95%,能起到作用的最低醋酸浓度为0.05mol/L;醋酸对由花生四烯酸诱导的血小板聚集的最大抑制率为83.62%,能起到作用的最低醋酸浓度为0.01mol/L。与空白对照组相比,醋酸及陈醋低分子成分均对由花生四烯酸和胶原诱导的血小板聚集有明显抑制作用,且抑制作用均呈浓度依赖型,其中醋酸对以花生四烯酸为诱导剂引起的血小板聚集的作用更为明显。

  7. 血小板聚集影响因素在血细胞计数中的临床应用%Clinical application of platelet aggregation for white blood cell count

    Institute of Scientific and Technical Information of China (English)

    胡恩亮; 赵媛; 王妍; 樊爱琳; 郑善銮

    2016-01-01

    Objective To analyze the cause of platelet aggregation in blood specimens ,so as to provide basis for reducing platelet aggregation ,and avoiding false positive of platelet count ,false report ,misdiagnosis and mistreatment .Methods The blood speci-mens which platelet was below 80 × 109 /L ,below 125 × 109 /L with histogram hinted platelet aggregation ,were smeared ,stained with Wright-Giemsa ,and observed by microscope for platelet morphological changes .The data between each groups were calculated and analyzed by statistical software SPSS version 18 .0 .Results A total of 184 cases of ethylenediaminetetraacetic acid dependent pseudothrombocytopenia(EDTA-PTCP) were found ,accounted for 0 .444 ‰ totally ,including 0 .244 ‰ of out-patients (101 cases) , 0 .159 ‰ of hospitalized patients (66 cases) ,and 0 .041 ‰ of health examination personnel (17 cases) .3 cases of multi-dependent pseudothrombocytopenia and 25 cases of pseudo platelet aggregation were found ,and accounted for 0 .007 ‰ and 0 .060 ‰ respec-tively .Conclusion The discovery of platelet aggregation which caused mainly by EDTA-PTCP ,still relies on microscopy ,and pseu-do platelet aggregation comes mainly from sampling ,so it needs to strengthen the skills training .%目的:分析血小板聚集影响因素,为降低血小板聚集所致血小板假性减低、实验室规避报告风险及减低误诊误治提供依据。方法对血小板小于80×109/L 、小于125×109/L 合并直方图提示血小板凝集标本进行推片、瑞氏-吉姆萨染色后显微镜下观察是否聚集,并采用统计软件 SPSS 18.0进行统计分析。结果乙二胺四乙酸依赖性血小板减少症(EDTA-PTCP)共计184例,占0.444‰,其中门诊患者101例,占0.244‰,住院患者66例,占0.159‰,体检者17例,占0.041‰;多重抗凝剂依赖性血小板假性减少共计3例,占0.007‰,假性血小板聚集共计25例,占0.060‰。结论血小

  8. 根据生物学变异度确定血液学检测下限的研究%Use biological variation to value the lower detect limit of hematology and platelet aggregation test

    Institute of Scientific and Technical Information of China (English)

    吴俊; 赵洁; 宋英; 赵磊; 赵京忠

    2013-01-01

    目的 确定血常规分析,血小板聚集检验最低检测下限范围.方法 Sysmex2100血液分析仪检测血常规,将标本倍比稀释后重复检测10次样本,计算变异系数CV值,做曲线及计算方程,以1/2生物变异度规定为允许CV值,该CV值代入方程为检测低限.对于血小板聚集,稀释后检测血小板聚集,在低于平台区的范围定位检测下限.结果 白细胞检测下限为0.11×109/l,红细胞检测下限为0.14×1012/l,红细胞压积检测下限3.03%,血小板检测下限为15.31×109/l.血小板聚集需要最低的血小板数量为200×109/l.结论 以生物变异度为基础的CV来确认仪器检测下限,方法可行,且与临床实际情况相符合.可作为确定仪器检测下限的方法.%Objective To detect the lower limit of hematology,platelet aggregation. Methods we use sysmex 2100 hematology analyzer blood cell account;Chrono-log platelet function instrument test platelet aggregation rate. After di luting samples,we retest the sample 10 times, plot X-axis with concentration, Y-axis with CV%, calculated the equa tion. We set 1/2 biological variation as standard CV to get the lower limit of detection. As for platelet aggregation, the concentration below the plateau is the lower limit concentration. Results Low limit detection of white blood cell, red blood cell,hematocrit,platelet is 0.11 ×109/1,0.14 × 1012/1,3.03% ,15.31 × 109/1, respectivly. The low concentration of platelet aggregation is 200×109/1. Conclusion Use biological variation to set the lower limit of detection is practica ble. It fit with clinical situation. The 1/2 biological variation could be the standard of lower limit of detection evaluation.

  9. In vitro function of random donor platelets stored for 7 days in composol platelet additive solution

    Directory of Open Access Journals (Sweden)

    Gupta Ashish

    2011-01-01

    Full Text Available Background and Aim: Platelets are routinely isolated from whole blood and stored in plasma for 5 days. The present study was done to assess the in vitro function of random donor platelets stored for 7 days in composol platelet additive solution at 22°C. Materials and Methods: The study sample included 30 blood donors of both sex in State Blood Bank, CSM Medical University, Lucknow. Random donor platelets were prepared by platelet rich plasma method. Whole blood (350 ml was collected in anticoagulant Citrate Phosphate Dextrose Adenine triple blood bags. Random donor platelets were stored for 7 days at 22°C in platelet incubators and agitators, with and without additive solution. Results: Platelet swirling was present in all the units at 22°C on day 7, with no evidence of bacterial contamination. Comparison of the mean values of platelet count, platelet factor 3, lactate dehydrogenase, pH, glucose and platelet aggregation showed no significant difference in additive solution, whereas platelet factor 3, glucose and platelet aggregation showed significant difference (P < 0.001 on day 7 without additive solution at 22°C. Conclusion: Our study infers that platelet viability and aggregation were best maintained within normal levels on day 7 of storage in platelet additive solution at 22°C. Thus, we may conclude that in vitro storage of random donor platelets with an extended shelf life of 7 days using platelet additive solution may be advocated to improve the inventory of platelets.

  10. Scratching below the surface: wound healing and alanine mutagenesis provide unique insights into interactions between eristostatin, platelets and melanoma cells.

    Science.gov (United States)

    McLane, Mary Ann; Zhang, Xiaoming; Tian, Jing; Zelinskas, Claire; Srivastava, Apoorva; Hensley, Brett; Paquette-Straub, Carrie

    2005-01-01

    To study the molecular mechanism of the disintegrin eristostatin, cellular functional studies were performed using ten recombinant alanine mutants. ADP-induced platelet aggregation revealed critical contributions of seven residues within the 'RGD loop' (R24, R27, G28, N31) and C-terminus (W47, N48, G49) of this disintegrin. Using an in vitro scratch wound healing assay, four human melanoma cell lines yielded similar results when exposed to wildtype eristostatin. All eristostatin-treated cells healed less of the wounded area than control conditions. This phenomenon was reproduced when using fibronectin as the matrix. C8161 cells showed significant delay in wound closure with the N-terminal mutant P4A but not with R24A or G28A. Evidence from our laboratory and others suggests neither alpha IIb, alpha 4 nor alpha 5 integrins are directly involved in eristostatin's interactions. Eristostatin did not affect the number of melanoma cells in culture after 24 h or the development of apoptosis. However, phosphorylation studies performed after these melanoma cells were exposed to eristostatin revealed changes in several tyrosine phosphorylated molecules.

  11. Effect of ionizing radiation on platelet function in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kalovidouris, A.E.; Papayannis, A.G. (Evangelismos Hospital, Athens (Greece))

    1981-01-01

    The effect of ionizing radiation on platelet function was investigated in vitro. Platelet-rich plasma (300x10/sup 9//l) was irradiated with doses of 1, 4, 10, 20 and 50 Gy. Platelet function tests were performed on both irradiated and control (non-irradiated) platelet samples. The platelet function tests were (1) platelet aggregation by ADP (1, 2, 4 ..mu..mol final concentration), adrenaline and collagen, (2) ADP-release from platelets, (3) clot retraction and (4) platelet factor-3 availability. It was found that roentgen irradiation of platelets in vitro did not affect these platelet function tests.

  12. Immunohistochemical Evaluation of Fibronectin and Tenascin Following Direct Pulp Capping with Mineral Trioxide Aggregate, Platelet-Rich Plasma and Propolis in Dogs’ Teeth

    Science.gov (United States)

    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

  13. Comparative evaluation of platelet-rich fibrin, mineral trioxide aggregate, and calcium hydroxide as pulpotomy agents in permanent molars with irreversible pulpitis: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Varun Kumar

    2016-01-01

    Full Text Available Background: Pulpotomy has been proposed as an alternative for the management of irreversible pulpitis in permanent molars with closed apices. Aim: To compare the performances of calcium hydroxide (CH, mineral trioxide aggregate (MTA, and platelet-rich fibrin (PRF as pulpotomy agents in mature permanent molars with irreversible pulpitis. Materials and Methods: Fifty-four permanent mandibular molars with carious exposure and symptoms of irreversible pulpitis were randomly allocated to three groups, and full pulpotomy was performed using CH,MTA, or PRF as pulpotomy agents. Pain intensity was recorded using numeric rating scale score at baseline, 24 h, 7 days, 6 months, and 1 year. Clinical and radiographic assessments were done at 6 months and 1 year. Statistical Analysis: Kruskal–Wallis test and Friedman test were used for intergroup and intragroup comparison of pain scores, respectively. The radiographic outcomes between the three study arms were compared using Chi-square test. Results: Clinical success rate was 94.4% at 7 days, which dropped to 85.4% at 12 months. All three agents were equally effective in providing pain relief at all the intervals tested, with no significant difference between them (P > 0.05 at all intervals. However, at 6 months and 12 months, 26.2% and 52.4% teeth depicted slight widening of periodontal ligament space. No significant difference was observed between the radiographic success rates observed with the three groups (P = 0.135 at 6 months, 0.717 at 12 months. Conclusion: Pulpotomy exhibited a high clinical success rate in mature molars with irreversible pulpitis and selection of biomaterial did not affect its outcome.

  14. Comparative evaluation of platelet-rich fibrin, mineral trioxide aggregate, and calcium hydroxide as pulpotomy agents in permanent molars with irreversible pulpitis: A randomized controlled trial

    Science.gov (United States)

    Kumar, Varun; Juneja, Ruchi; Duhan, Jigyasa; Sangwan, Pankaj; Tewari, Sanjay

    2016-01-01

    Background: Pulpotomy has been proposed as an alternative for the management of irreversible pulpitis in permanent molars with closed apices. Aim: To compare the performances of calcium hydroxide (CH), mineral trioxide aggregate (MTA), and platelet-rich fibrin (PRF) as pulpotomy agents in mature permanent molars with irreversible pulpitis. Materials and Methods: Fifty-four permanent mandibular molars with carious exposure and symptoms of irreversible pulpitis were randomly allocated to three groups, and full pulpotomy was performed using CH, MTA, or PRF as pulpotomy agents. Pain intensity was recorded using numeric rating scale score at baseline, 24 h, 7 days, 6 months, and 1 year. Clinical and radiographic assessments were done at 6 months and 1 year. Statistical Analysis: Kruskal–Wallis test and Friedman test were used for intergroup and intragroup comparison of pain scores, respectively. The radiographic outcomes between the three study arms were compared using Chi-square test. Results: Clinical success rate was 94.4% at 7 days, which dropped to 85.4% at 12 months. All three agents were equally effective in providing pain relief at all the intervals tested, with no significant difference between them (P > 0.05 at all intervals). However, at 6 months and 12 months, 26.2% and 52.4% teeth depicted slight widening of periodontal ligament space. No significant difference was observed between the radiographic success rates observed with the three groups (P = 0.135 at 6 months, 0.717 at 12 months). Conclusion: Pulpotomy exhibited a high clinical success rate in mature molars with irreversible pulpitis and selection of biomaterial did not affect its outcome. PMID:27994420

  15. Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study

    Directory of Open Access Journals (Sweden)

    Hedbäck Bo

    2009-06-01

    Full Text Available Abstract Background Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effects of ASA and clopidogrel. The adhesion assay measures several aspects of platelet adhesion simultaneously, which increases the probability of finding conditions sensitive for anti-platelet treatment. Methods With a randomised cross-over design we evaluated the anti-platelet effects of ASA combined with clopidogrel as well as monotherapy with either drug alone in 29 patients with a recent acute coronary syndrome. Also, 29 matched healthy controls were included to evaluate intra-individual variability over time. Platelet function was measured by flow cytometry, serum thromboxane B2 (TXB2-levels and by static platelet adhesion to different protein surfaces. The results were subjected to Principal Component Analysis followed by ANOVA, t-tests and linear regression analysis. Results The majority of platelet adhesion measures were reproducible in controls over time denoting that the assay can monitor platelet activity. Adenosine 5'-diphosphate (ADP-induced platelet adhesion decreased significantly upon treatment with clopidogrel compared to ASA. Flow cytometric measurements showed the same pattern (r2 = 0.49. In opposite, TXB2-levels decreased with ASA compared to clopidogrel. Serum TXB2 and ADP-induced platelet activation could both be regarded as direct measures of the pharmacodynamic effects of ASA and clopidogrel respectively. Indirect pharmacodynamic measures such as adhesion to albumin induced by various soluble activators as well as SFLLRN

  16. 山绿茶提取物对体外人血小板聚集的影响%Effect of Extracts from Ilex Hainanensis Merr.on Human Platelet Aggregation in Vitro

    Institute of Scientific and Technical Information of China (English)

    李浩野; 孟兰贞; 黄卫华; 赵静; 刘华钢; 李绍平

    2013-01-01

    山绿茶为广西少数民族民间中草药,具有活血通脉等治疗心血管疾病的功效.为观察山绿茶提取物对花生四烯酸钠盐(AA)、二磷酸腺苷(ADP)、盐酸肾上腺素(ADR)诱导的体外人血小板聚集的影响,通过阿司匹林为阳性药建立体外抗人血小板聚集模型,以健康人富血小板血浆为研究对象,分别以AA、ADP、ADR作为诱导剂,运用Born氏比浊法测定体外诱导的人血小板聚集率,探究不同山绿茶提取物对体外诱导的人抗血小板聚集的影响.实验结果表明:阳性药阿司匹林对诱导的体外人血小板聚集有明显抑制作用,而山绿茶各提取物对诱导的体外人血小板聚集无显著影响,虽然山绿茶提取物对体外人血小板聚集的抑制作用为阴性结果,但为地方中药材标准的完善提供了实验依据.%Ilex hainanensis Merr is the national minority folk herbal medicine in the Guangxi Zhuang Autonomous Region,and its effects of blood invigorate and pulse promotion can provide potential therapeutic approaches to treatment cardiovascular diseases.The aim of this paper is to observe the effect of different extracts from Ilex hainanensis Merr (IHE) on human platelet aggregation induced by arachidonic acid sodium salt (AA),adenosine diphosphate (ADP),and epinephrine hydrochlaride (ADR),respectively,in vitro.In this study,aspirin was used as positive control drug to establish the in vitro anti-platelet aggregation model and platelet aggregation rate was measured by Born's method.Platelet-rich plasma was collected from healthy donors and induced by AA,ADP and ADR,respectively and the model was applied to study the effect of different IHE on the platelet aggregation.The results showed that aspirin can significantly inhibit platelet aggregation induced by AA,ADP and ADR in vitro,respectively,but the IHE did not show inhibiting effect on the human platelet aggregation significantly.However,the IHE negative results can provide solid

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  18. Nucleolin down-regulation is involved in ADP-induced cell cycle arrest in S phase and cell apoptosis in vascular endothelial cells.

    Directory of Open Access Journals (Sweden)

    Wenmeng Wang

    Full Text Available High concentration of extracellular ADP has been reported to induce cell apoptosis, but the molecular mechanisms remain not fully elucidated. In this study, we found by serendipity that ADP treatment of human umbilical vein endothelial cells (HUVEC and human aortic endothelial cells (HAEC down-regulated the protein level of nucleolin in a dose- and time-dependent manner. ADP treatment did not decrease the transcript level of nucloelin, suggesting that ADP might induce nucleolin protein degradation. HUVEC and HAEC expressed ADP receptor P2Y13 receptor, but did not express P2Y1 or P2Y12 receptors. However, P2Y1, 12, 13 receptor antagonists MRS2179, PSB0739, MRS2211 did not inhibit ADP-induced down-regulation of nucleolin. Moreover, MRS2211 itself down-regulated nucleolin protein level. In addition, 2-MeSADP, an agonist for P2Y1, 12 and 13 receptors, did not down-regulate nucleolin protein. These results suggested that ADP-induced nucleolin down-regulation was not due to the activation of P2Y1, 12, or 13 receptors. We also found that ADP treatment induced cell cycle arrest in S phase, cell apoptosis and cell proliferation inhibition via nucleolin down-regulation. The over-expression of nucleolin by gene transfer partly reversed ADP-induced cell cycle arrest, cell apoptosis and cell proliferation inhibition. Furthermore, ADP sensitized HUVEC to cisplatin-induced cell death by the down-regulation of Bcl-2 expression. Taken together, we found, for the first time to our knowledge, a novel mechanism by which ADP regulates cell proliferation by induction of cell cycle arrest and cell apoptosis via targeting nucelolin.

  19. Platelet function monitoring guided antiplatelet therapy in patients receiving high-risk coronary interventions

    Institute of Scientific and Technical Information of China (English)

    Xu Li; Wang Lefeng; Yang Xinchun; Li Kuibao; Sun Hao; Zhang Dapeng; Wang Hongshi

    2014-01-01

    than 50% and the ADP-induced IPA of fifty-seven (29.5%) patients was less than 30%; therefore,their drug dosages were adjusted.The TEG was rechecked one to four weeks after PCI,and the results indicated that the IPAs had significantly improved (P <0.01).However,no significant differences were found in the rates of the primary efficacy endpoint.Rates in the conventionally treated group and platelet function monitoring guided group were 4.7% and 5.2%,respectively (hazard ratio:1.13; P=0.79).Conclusion An antiplatelet therapy guided by TEG monitored platelet function could not improve clinical efficacy even in ACS patients treated with high-risk complex PCI.

  20. Impact of high dose vitamin C on platelet function

    Science.gov (United States)

    Mohammed, Bassem M; Sanford, Kimberly W; Fisher, Bernard J; Martin, Erika J; Contaifer Jr, Daniel; Warncke, Urszula Osinska; Wijesinghe, Dayanjan S; Chalfant, Charles E; Brophy, Donald F; Fowler III, Alpha A; Natarajan, Ramesh

    2017-01-01

    AIM To examine the effect of high doses of vitamin C (VitC) on ex vivo human platelets (PLTs). METHODS Platelet concentrates collected for therapeutic or prophylactic transfusions were exposed to: (1) normal saline (control); (2) 0.3 mmol/L VitC (Lo VitC); or (3) 3 mmol/L VitC (Hi VitC, final concentrations) and stored appropriately. The VitC additive was preservative-free buffered ascorbic acid in water, pH 5.5 to 7.0, adjusted with sodium bicarbonate and sodium hydroxide. The doses of VitC used here correspond to plasma VitC levels reported in recently completed clinical trials. Prior to supplementation, a baseline sample was collected for analysis. PLTs were sampled again on days 2, 5 and 8 and assayed for changes in PLT function by: Thromboelastography (TEG), for changes in viscoelastic properties; aggregometry, for PLT aggregation and adenosine triphosphate (ATP) secretion in response to collagen or adenosine diphosphate (ADP); and flow cytometry, for changes in expression of CD-31, CD41a, CD62p and CD63. In addition, PLT intracellular VitC content was measured using a fluorimetric assay for ascorbic acid and PLT poor plasma was used for plasma coagulation tests [prothrombin time (PT), partial thrombplastin time (PTT), functional fibrinogen] and Lipidomics analysis (UPLC ESI-MS/MS). RESULTS VitC supplementation significantly increased PLTs intracellular ascorbic acid levels from 1.2 mmol/L at baseline to 3.2 mmol/L (Lo VitC) and 15.7 mmol/L (Hi VitC, P 0.05). PLT function assayed by TEG, aggregometry and flow cytometry was not significantly altered by Lo or Hi VitC for up to 5 d. However, PLTs exposed to 3 mmol/L VitC for 8 d demonstrated significantly increased R and K times by TEG and a decrease in the α-angle (P 0.05). Collagen and ADP-induced ATP secretion was also not different between the three groups (P > 0.05). Finally, VitC at the higher dose (3 mmol/L) also induced the release of several eicosanoids including thromboxane B2 and prostaglandin E2, as

  1. Variation in dietary salt intake induces coordinated dynamics of monocyte subsets and monocyte-platelet aggregates in humans: implications in end organ inflammation.

    Directory of Open Access Journals (Sweden)

    Xin Zhou

    Full Text Available BACKGROUND: Monocyte activation and tissue infiltration are quantitatively associated with high-salt intake induced target organ inflammation. We hypothesized that high-salt challenge would induce the expansion of CD14++CD16+ monocytes, one of the three monocyte subsets with a pro-inflammatory phenotype, that is associated with target organ inflammation in humans. METHODOLOGY/PRINCIPAL FINDINGS: A dietary intervention study was performed in 20 healthy volunteers, starting with a 3-day usual diet and followed with a 7-day high-salt diet (≥15 g NaCl/day, and a 7-day low-salt diet (≤5 g NaCl/day. The amounts of three monocyte subsets ("classical" CD14++CD16-, "intermediate" CD14++CD16+ and "non-classical" CD14+CD16++ and their associations with monocyte-platelet aggregates (MPAs were measured by flow cytometry. Blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI was used to evaluate renal hypoxia. Switching to a high-salt diet resulted in CD14++ monocyte activation and a rapid expansion of CD14++CD16+ subset and MPAs, with a reciprocal decrease in the percentages of CD14++CD16- and CD14+CD16++ subsets. In vitro study using purified CD14++ monocytes revealed that elevation in extracellular [Na(+] could lead to CD14++CD16+ expansion via a ROS dependent manner. In addition, high-salt intake was associated with progressive hypoxia in the renal medulla (increased R2* signal and enhanced urinary monocyte chemoattractant protein-1 (MCP-1 excretion, indicating a temporal and spatial correlation between CD14++CD16+ subset and renal inflammation. The above changes could be completely reversed by a low-salt diet, whereas blood pressure levels remained unchanged during dietary intervention. CONCLUSIONS/SIGNIFICANCE: The present work demonstrates that short-term increases in dietary salt intake could induce the expansion of CD14++CD16+ monocytes, as well as an elevation of MPAs, which might be the underlying cellular basis of high-salt induced

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

    Science.gov (United States)

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

    2016-04-30

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

  3. 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.

    Science.gov (United States)

    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.

  4. 血小板亲和萃取-HPLC分析法在栀子提取物抗血小板聚集效应物质分析中的应用%Analysis on Anti-platelet Aggregation Effectors from Gardenia Jasminoides Extract with Employment of Platelet Affinity Extraction Method Coupled with HPLC

    Institute of Scientific and Technical Information of China (English)

    郭青丽; 杜守颖; 陆洋; 李鹏跃; 徐攀; 王振; 郭懿望; 尚可心; 程艳珂

    2014-01-01

    This study was aimed to search anti-platelet aggregation effectors from Gardenia jasminoides extract with the employment of platelet affinity extraction method coupled with HPLC, in order to provide pharmacological experi-mental evidences of the selected effectors to verify its feasibility. Under physiological conditions, washed rat platelets were added into G. jasminoides extract and then a mixture was gained. Consequently, some components from G. jas-minoides extract were combined to the platelets in the mixture while some were not owing to their special chemical structures and properties. Firstly, the uncombined components were washed off from the mixture. Secondly, the com-bined components in the leftover was washed down and collected, respectively, right after destroying the occupied platelets' structures. Thirdly, different collected eluents were analyzed, respectively, by HPLC established in the pre-vious work to search the effectors. Fourthly, pharmacological experiments were implemented for confirmation. The re-sults showed that dominant effective components from G. jasminoides extract acting on anti-platelet aggregation were identified as geniposide. Further evident was provided as well by pharmacological experiment that geniposide exhibit-ed significant inhibitory effect on anti-platelet aggregation in rats induced by ADP, rat tail collagen and thrombin(P< 0.01). It was concluded that the platelet affinity extraction-HPLC method proposed in this paper can be utilized to analyze the correlation of effectors from G. jasminoides extract and its pharmacological effects. Moreover, there are some correlations between screened chemical substances and their pharmacological effects.%目的:应用血小板生物亲和萃取-HPLC分析法分析栀子提取物中抗血小板聚集的活性成分,并对活性成分进行药理实验,以验证血小板生物亲和萃取-HPLC分析法在栀子提取物抗血小板聚集效应物质分析中的可行性。方法

  5. Severely impaired von Willebrand factor-dependent platelet aggregation in patients with a continuous-flow left ventricular assist device (HeartMate II)

    DEFF Research Database (Denmark)

    Klovaite, Jolanta; Gustafsson, Finn; Mortensen, Svend A

    2009-01-01

    OBJECTIVES: This study investigated the influence of the mechanical blood pump HeartMate II (HMII) (Thoratec Corporation, Pleasanton, California) on blood coagulation and platelet function. BACKGROUND: HMII is an implantable left ventricular assist device used for the treatment of heart failure...

  6. 岩乌头根部的生物碱类成分及其抗PAF活性%Diterpenoid Alkaloids from roots of Aconitum recemulosum and their inhibitory effects on PAF-induced platelet aggregation

    Institute of Scientific and Technical Information of China (English)

    葛永辉; 穆淑珍; 张建新; 汪冶; 孙黔云; 郝小江

    2009-01-01

    Objective:To study diterpenoid alkaloids from the roots of Aconitum recemulosum,and their inhibitory effects on PAF-induced platelet aggregation.Method:The root of A.recemulosum was extracted with 95% EtOH.The total alkaloids extracted were isolated and purified by several kinds of column chromatography over silica gel,RP-18,and Sephadex LH-20,and identified based on spectral analysis.And the inhibitory effects of isolated compounds on PAF-induced platelet aggregation were detected.Result:Five alkaloids were isolated and identified as sachaconitine(1),14-acetylsachaconitine(2),hemsleyanine C(3),circinasine A(4),and talatisamine(5).The results showed compounds 1 and 2 have moderate inhibition effect on PAF.Conclusion:Compounds 1-5 were firstly isolated from this plant.Furthermore,compounds 1 and 2 possessed moderate inhibitory effects on PAF-induced platelet aggregation.%目的:研究岩乌头根部的二萜生物碱类成分及其抗PAF活性.方法:95%乙醇提取,所得浸膏采用经典的酸-碱处理方法,得到总碱,总碱经硅胶,RP-18,sephadex LH-20等多种材料柱色谱分离,得到生物碱单体,再通过波谱解析鉴定其化学结构;并对分离鉴定的生物碱进行抗PAF活性的检测.结果:分离鉴定了5个二萜类生物碱,分别为sachaconitine(1),14-acetylsachaconitine(2),hemsleyanine C(3),circinasine A(4),talatisamine(5);化合物1和2显示了一定的抗PAF活性.结论:所有化合物均为首次从该植物中分得,化合物1和2对PAF诱导的血小板聚集具有一定的抑制作用.

  7. PREGNANCY WITH PLATELET FUNCTION DISORDER

    Directory of Open Access Journals (Sweden)

    Sheila K

    2014-01-01

    Full Text Available latelets play a vital role in haemostasis . Antenatal patients with platelet function disorders should be managed in tertiary care centres that are well equipped to tackle any obstetric haemorrhage that can ensue during labour and delivery . Primi gravida was admitted for safe confinement . She had been evaluated earlier for complaints of multiple episodes of mucosal bleeding . On evaluation she had nor mal platelet counts and coagulation factor assay was normal . Platelet aggregometry revealed mild disorder of platelet aggregation . She was planned for induction of labour after arranging enough blood and blood products . She got into active labour and was p ut on syntocinon augmentation . She had emergency Caesarean section for foetal distress . Oxytocics were given proactively . Intraoperatively platelet transfusions and tranexamic acid infusion were given . Complete haemostasis was achieved . She had an uneventf ul postoperative period . Patients with functional platelet disorders can be successfully managed with local application of antifibrinolytic agents like tranexamic acid , in case of minor bleeds . Platelet transfusions are very effective in tackling major ble eds , especially during surgeries and for obstetric indications . If a patient has the history of clinically significant bleeding suggestive of platelet dysfunction , appropriate platelet function tests should be obtained so that the risk of bleeding can be adequately assessed and therapy chosen more rationally . . In obstetric practice the response of such patients to platelet transfusions has been excellent

  8. Defining predictive values using three different platelet function tests for CYP2C19 phenotype status on maintenance dual antiplatelet therapy after PCI.

    Science.gov (United States)

    Zhang, Hong-Zhe; Kim, Moo Hyun; Han, Jin-Yeong; Jeong, Young-Hoon

    2014-01-01

    Published data suggests that the presence of CYP2C19*2 or *3 loss of function (LOF) alleles is indicative of increased platelet aggregation and a higher risk of adverse cardiovascular events after clopidogrel administration. We sought to determine cut-off values using three different assays for prediction of the CYP2C19 phenotype in Korean percutaneous coronary intervention (PCI) patients. We enrolled 244 patients with drug-eluting stent implantation who were receiving clopidogrel and aspirin maintenance therapy for one month or more. Platelet reactivity was assessed with light transmittance aggregometry (LTA), multiple electrode aggregometry (MEA) and the VerifyNow P2Y12 assay (VN). The CYP2C19 genotype was analyzed by polymerase chain reaction (PCR) and snapshot method. The frequency of CYP2C19 LOF allele carriers was 58.6%. The cut-off values from LTA, MEA and VerifyNow for the identification of LOF allele carriers were as follows: 10 µM ADP-induced LTA ≥ 48 %, VN>242 PRU and MEA ≥ 37 U. Between the three tests, correlation was higher between LTA vs. VN assays (r=0.69) and LTA vs. MEA (r=0.56), with moderate agreement (κ=0.46 and κ=0.46), but between VN assay and MEA, both devices using whole blood showed a lower correlation (r=0.42) and agreement (κ=0.3). Our results provide guidance regarding cut-off levels for LTA, VerifyNow and MEA assays to detect the CYP2C19 LOF allele in patients during dual antiplatelet maintenance therapy.

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

    OpenAIRE

    Haimeur, Adil; Messaouri, Hafida; Ulmann, Lionel; Mimouni, Virginie; Masrar, Azelarab; Chraibi, Abdelmjid; Tremblin, Gérard; Meskini, Nadia

    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 associa...

  10. Effect of polytetrafluoroethylene artificial blood vessels on platelet aggregation and its cytocompatibility%聚四氟乙烯人工血管对血小板聚集的影响及细胞相容性

    Institute of Scientific and Technical Information of China (English)

    姜正明; 陈魁; 胡彩娜

    2016-01-01

    背景:聚四氟乙烯人工血管是临床常用的医用材料,但其具体的基础研究内容尚未完善。目的:观察聚四氟乙烯人工血管对血小板聚集的作用及细胞相容性。方法:①对血小板聚集的作用:检测聚四氟乙烯人工血管的凝血时间、复钙时间。将生理盐水、蒸馏水及聚四氟乙烯人工血管分别加入兔红细胞悬液中,计算溶血率;②细胞生物相容性:将SD大鼠原代心肌细胞分别接种于普通玻璃爬片与聚四氟乙烯人工血管片上,3 d后,检测细胞乳酸脱氢酶释放;5 d后,检测细胞增殖。结果与结论:①聚四氟乙烯人工血管对兔血的动态凝血时间、复钙时间没有影响;聚四氟乙烯人工血管的溶血率为2.3%;②与接种于普通玻璃爬片上的心肌细胞相比,接种于聚四氟乙烯人工血管片上的心肌细胞增殖及乳酸脱氢酶释放无明显变化;③结果表明,聚四氟乙烯人工血管血小板聚集无影响,具有良好的血液相容性与细胞相容性。%BACKGROUND:Polytetrafluoroethylene artificial blood vessels have been extensively used in clinic. However, there is stil a lack of basic study on it. OBJECTIVE:To observe the effect of polytetrafluoroethylene artificial blood vessels on platelet aggregation and its cytocompatibility. METHODS:Effect on platelet aggregation:Dynamic platelet clotting time and plasma recalcification time were detected. Normal saline, distil ed water and polytetrafluoroethylene artificial blood vessels were added into the rabbit red cel suspensions, respectively, to count the hemolysis ratio. Cytocompatibility:Primary myocardial cel s from Sprague-Dawley rats were respectively seeded onto the common round coverslip and polytetrafluoroethylene artificial blood vessels, and the lactate deshydrogenase release and cel proliferation were detected at 3 and 5 days, respectively. RESULTS AND CONCLUSION:Polytetrafluoroethylene artificial

  11. Overview of platelet physiology and laboratory evaluation of platelet function.

    Science.gov (United States)

    Rodgers, G M

    1999-06-01

    Appropriate laboratory testing for the platelet-type bleeding disorders hinges on an adequate assessment in the history and physical examination. Patients with histories and screening laboratory results consistent with coagulation disorders (hemophilia, disseminated intravascular coagulation) are not appropriate candidates for platelet function testing. In contrast, patients with a lifelong history of platelet-type bleeding symptoms and perhaps a positive family history of bleeding would be appropriate for testing. Figure 6 depicts one strategy to evaluate these patients. Platelet morphology can easily be evaluated to screen for two uncommon qualitative platelet disorders: Bernard-Soulier syndrome (associated with giant platelets) and gray platelet syndrome, a subtype of storage pool disorder in which platelet granulation is morphologically abnormal by light microscopy. If the bleeding disorder occurred later in life (no bleeding with surgery or trauma early in life), the focus should be on acquired disorders of platelet function. For those patients thought to have an inherited disorder, testing for vWD should be done initially because approximately 1% of the population has vWD. The complete vWD panel (factor VIII coagulant activity, vWf antigen, ristocetin cofactor activity) should be performed because many patients will have abnormalities of only one particular panel component. Patients diagnosed with vWD should be classified using multimeric analysis to identify the type 1 vWD patients likely to respond to DDAVP. If vWD studies are normal, platelet aggregation testing should be performed, ensuring that no antiplatelet medications have been ingested at least 1 week before testing. If platelet aggregation tests are normal and if suspicion for an inherited disorder remains high, vWD testing should be repeated. The evaluation of thrombocytopenia may require bone marrow examination to exclude primary hematologic disorders. If future studies with thrombopoietin assays

  12. Rubia cordifolia, Fagonia cretica linn and Tinospora cordifolia exert anti-inflammatory properties by modulating platelet aggregation and VEGF, COX-2 and VCAM gene expressions in rat hippocampal slices subjected to ischemic reperfusion injury.

    Directory of Open Access Journals (Sweden)

    A K Rawal

    2009-03-01

    Full Text Available Summary: The formation of cerebral edema and central nervous system (CNS inflammation are a result of cerebral ischemia. Pharmacological strategies to reverse or minimize acute ischemic brain injury include "antiplatelet" agents, anticoagulants, and thrombolytics. However, these therapies have either exhibited undesirable side effects or are not cost-effective for the common people. We report here the neuroprotective effects of three herbs Rubia cordifolia (RC, Fagonia cretica linn (FC and Tinospora cordifolia (TC as potent anti-inflammatory agents in view of their ability to downregulate the expressions of COX2 and VCAM genes and upregulate VEGF expression and inhibit platelet aggregation induced by multiple agonists in hypoxic-ischemic hippocampal slices. All the three herbs exhibited appreciable anti-inflammatory properties. Industrial relevance: The above work will lead to development of new anti-inflammatory drugs with less toxic preparations and has the potential to generate employment among people who will go farming of such medicinal plants.

  13. Platelet Count

    Science.gov (United States)

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

  14. Platelet mimicry

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  15. 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

    Directory of Open Access Journals (Sweden)

    Vivek Sharma

    2016-01-01

    Full Text Available 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.

  16. Platelet factor XIII increases the fibrinolytic resistance of platelet-rich clots by accelerating the crosslinking of alpha 2-antiplasmin to fibrin

    Science.gov (United States)

    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.

  17. 钩藤碱对家兔血小板聚集及胞浆游离钙离子浓度的影响%Effect of rhynchophylline on platelet aggregation and cytoplasmic free calcium level in rabbits

    Institute of Scientific and Technical Information of China (English)

    谢笑龙; 龚其海; 陆远富; 邓江; 聂晶; 陈文明; 石京山

    2011-01-01

    OBJECTIVE To investigate the effect of rhynchophylline (Rhy) on the rabbit cytoplasmic free calcium level and platelet aggregation, and the possible mechanism. METHODS Blood samples from 56 male rabbits were randomly divided into control group ( normal saline), aspirin(Asp) 0.85, 1.69 and 2.78 mmol ·L-1 groups, and Rhy 0.33, 0.65 and 1.30 mmol·L-1 groups. Platelet aggregation and cytoplasmic free calcium level were determined by Born method and double beam fluorescence spectrophotometric method, respectively. RESULTS Compared with the platelet aggregation rate (59.6 ±0.6)% in control group induced by ADP 15 μmol·L-1, the platelet aggregation rates in Rhy 0.33, 0.65 and 1.30 mmol· L- 1 groups were decreased to ( 35.4 ±7.7 ) %, ( 18.2 ± 4.8 ) % and (6.9 ± 0.9 ) %, respectively ( P < 0.05 ). Compared with control group ( 80.8 ± 1.5 ) %, the maximum platelet aggregation rate induced by thrombin 3 kU· L- 1 in Rhy 0.65 and 1.30 mmol·L - 1 was (42.8 ± 3.9 ) % and ( 18.9 ± 5.5 ) % ( P < 0.05 ), respectively. In the presence of extracellular Ca2+ , a comparison of the cytoplasmic free calcium level (528 ± 25 )nmol·L -1 in control group and Rhy group was performed. Rhy 0.33, 0.65 and 1.30 mmol·L -1 depressed obviously the cytoplasmic free calcium level to 418 ±27,303 ±7 and (257 ±25 )nmol·L-1,respectively. During the inducement of ADP and thrombin, the cytoplasmic free calcium level in control group was 751 ± 29 and ( 982 ± 50 ) nmol· L- 1. After Rhy 0.65 and 1.30 mmol· L - 1 were administered, the cytoplasmic free calcium level induced by ADP decreased to 620 ± 37 and (528 ±17)nmol·L-1, respectively (P < 0. 05), the cytoplasmic free calcium level induced by thrombin decreased to 777 ± 29 and ( 658 ± 23 ) nmol· L-1, respectively ( P < 0.05 ).In the absence of extracellular Ca2+ , Rhy had no significant influence on cytoplasmic free calcium level of rabbit platelet. CONCLUSION Rhy markedly inhibits rabbit platelet

  18. Modulatory effect of coffee on platelet function.

    Science.gov (United States)

    Bhaskar, Shobha; Rauf, Arun A

    2010-01-01

    Blood platelets play a major role in cardiovascular disease (CVD) and thrombosis. Conflicting information exists regarding the effect of coffee consumption on the cardiovascular system. We have investigated whether the consumption of moderate amount of coffee affect platelet functions and primary hemostasis in vivo in normal and high fat diet fed rats. Coffee fed group showed significant (P production from membrane arachidonic acid and it was decreased in coffee treated group. Platelet aggregation studies with ADP, collagen, arachidonic acid and epinephrine showed significant (P coffee fed group. Scanning electron microscopic studies revealed that platelet aggregation tendency increased in HFD group and was reduced in coffee fed group. These results indicate that coffee is active in inhibiting platelet aggregation, a critical step involved in thrombosis.

  19. Patients with previous definite stent thrombosis have a larger fraction of immature platelets and a reduced antiplatelet effect of aspirin

    DEFF Research Database (Denmark)

    Würtz, Morten; Grove, Erik; Wulff, Lise Nielsen;

    turnover. Key Words: aspirin; immature platelets; platelet aggregation; platelet function tests; stent thrombosis Abbreviations: ARU, aspirin reaction units; AU, aggregation units; BMS, bare-metal stent(s); DES, drug-eluting stent(s); IPF, immature platelet fraction; MEA, multiple electrode aggregometry...

  20. Platelet affinity for burro aorta collagen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.D.

    1977-10-01

    Despite ingenious concepts, there are no unequivocal clues as to what, when, and how some undefined biochemical factor(s) or constituent(s) that localizes in the arterial wall can precipitate a thromboatheromatous lesion or arterial disease. The present study focused on the extraction, partial purification, and characterization of a collagen-active platelet stimulator from the aortas of aged burros. The aggregator moiety in the aorta extracts invariably had a higher affinity for platelets in citrated platelet-rich plasma of human beings than for platelets of homologous burros. The platelet-aggregating factor(s) in the aorta extract was retained by incubation with ..cap alpha..-chymotrypsin. Platelet-aggregating activity was rapidly abolished after incubation with collagenase, as determined by platelet-aggregometry tests. Evidence based on light microscope and polysaccharide histochemical reactions indicates a probability that the intracellular amorphous matrix (PAS-positive) and filamentous components (PTAH-positive) expelled from smooth muscle cells disrupted during homogenization of the aorta may be a principal source of a precursor collagen species which is a potent inducer of platelet aggregation.

  1. Evaluation of the performance of PRECIL LBY-NJ4A automatic platelet aggregation analyzer%普利生LBY-NJ4A全自动血小板聚集仪性能评价

    Institute of Scientific and Technical Information of China (English)

    石冬敏; 吴元健; 马伟

    2012-01-01

    目的 对普利生LBY-NJ4A全自动血小板聚集仪(NJ4A)进行性能评估.方法 109 mmol/L枸橼酸钠真空管采血,分离富含血小板血浆(PRP)和贫血小板血浆(PPP),应用NJ4A及配套质控品、诱导剂和清洗液,测定血小板最大聚集率(MAR),测试精密度、通道一致性、不确定度、检测限、干扰等.结果 批内不精密度测试,变异系数(CV)为3.4%~5.0%;4个不同通道测定均值差异无统计学意义(P>0.05);携带污染率2.82%;CV批内≤3.5%,CV批间≤4.2%,CV总≤3.8%;总误差范围为5.6%~10.3%,不确定度在可接受范围;2个水平质控品测定值与靶值差异无统计学意义(P>0.05);NJ4A与LBY-NJ2比对结果相关良好(r=0.998,P0.05).结论 NJ4A精密度、准确度、不确定度、灵敏度、携带污染率、抗干扰等性能指标符合CLSI规范,可在临床应用.%Objective To check and evaluate the performance of PRECIL LBY-NJ4A automatic platelet aggregation analyzer (NJ4A) .Methods Blood samples were collected with 109 mmol/L sodium citrate using vacuum tube,then the platelet-rich plasma (PRP)and platelet-poor plasma(PPP) were separated .The NJ4A analyzer with mating quality control,agonists and cleaning solution were used to measure the maximum aggregate rate of platelet (MAR),precision,channel consistency,inaccuracy,detection limitation and inference .Results The precision ranged from 3 .4/0 to 5 .0% .The means of four different channels have no statistically difference(P>0 .05),when carryover rate was 2 .82% .The intra,inter hatch and total coefficient of variance was less than or equal to 3 .5%,4 .2% and 3 .8/0,respectively .The total error ranged from 5 .6/0 to 10 .3%,with an acceptable inaccuracy .Two levels of quality control have no statistically difference with each target value (P>0.05).The correlation of NJ4 and LBY-NJ2 was 0.998 (P0.05) compared to the well-recognized reference range .Conclusion The performance indicators of precision, accuracy, uncertainty

  2. Platelet reactions to modified surfaces under dynamic conditions.

    Science.gov (United States)

    Rhodes, N P; Shortland, A P; Rattray, A; Williams, D F

    1998-12-01

    The influence of surfaces on the reactions of platelets in whole blood under laminar flow was investigated in a cone and plate viscometer. Citrated whole blood was exposed to steel, PMMA and PMMA modified with PEO at low (500 s(-1)) and high (4000 s(-1)) wall shear rates at room temperature for a period of 100 s. Treated blood samples were fixed with paraformaldehyde, stained with a monoclonal antibody for CD41 (platelet GPIIb/IIIa) conjugated with phycoerythrin and analyzed by flow cytometry. The reactions of platelets (microparticle generation and formation of platelet-platelet, platelet-red blood cell and red blood cell-microparticle aggregates) to these environments were quantified. Additionally, the size of platelet-platelet aggregates was assessed. The percentage platelet aggregation and numbers of microparticles generated were independent of surface type at any shear rate. The composition of the aggregates formed was influenced by the surface: at low and high shear rates PMMA caused the generation of platelet-platelet aggregates of the greatest size. The numbers of red blood cell-platelet and red blood cell-microparticle aggregates also varied depending on the surface. Fewer red blood cell-platelet aggregates were formed at higher shear rates, whereas the reverse was true for red blood cell-microparticle aggregates. It is concluded that these variations may help to explain the differential effects of surfaces to the induction of distant thrombotic events: microparticles may be protected from loss from the blood stream by their association with red blood cells at high shear rates.

  3. Platelet proteomics.

    Science.gov (United States)

    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.

  4. Image analysis of blood platelets adhesion.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, M G

    1977-07-31

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

  6. Influence of Oxidative Stress on Stored Platelets

    Directory of Open Access Journals (Sweden)

    K. Manasa

    2016-01-01

    Full Text Available Platelet storage and its availability for transfusion are limited to 5-6 days. Oxidative stress (OS is one of the causes for reduced efficacy and shelf-life of platelets. The studies on platelet storage have focused on improving the storage conditions by altering platelet storage solutions, temperature, and materials. Nevertheless, the role of OS on platelet survival during storage is still unclear. Hence, this study was conducted to investigate the influence of storage on platelets. Platelets were stored for 12 days at 22°C. OS markers such as aggregation, superoxides, reactive oxygen species, glucose, pH, lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed. OS increased during storage as indicated by increments in aggregation, superoxides, pH, conjugate dienes, and superoxide dismutase and decrements in glucose and catalase. Thus, platelets could endure OS till 6 days during storage, due to the antioxidant defense system. An evident increase in OS was observed from day 8 of storage, which can diminish the platelet efficacy. The present study provides an insight into the gradual changes occurring during platelet storage. This lays the foundation towards new possibilities of employing various antioxidants as additives in storage solutions.

  7. Platelet lipidomic.

    Science.gov (United States)

    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. Comparison of inhibitive effect on EDTA-dependent platelet aggregation between two drugs%两种药物对EDTA依赖性血小板聚集的抑制作用比较

    Institute of Scientific and Technical Information of China (English)

    赵凯华; 周雄辉; 刘强; 汪金; 李丽萍; 王科

    2013-01-01

    bjective To investigate the inhibitive effects on EDTA-dependent platelet aggregation between amikacin and ticlopidine in vitro. Methods The XT4800i five classification blood corpuscle analyzer was used to count the blood cells in the complete blood samples added with two anticoagulamt drugs of various concentrations . The counting results were compared with those obtained by manual counting method. Results There were significant differences in PLT counting between amikacin or ticlopidine -anticoagulated samples and EDTA -K2 anticoagulated ones (P 0. 05). The MPV of PLT obtained with anticoagulamt drugs method was samilar to that obtained by the conventional detection (P > 0. 05 ). Conclusion Amikacin and ticlopidine have good inhibitive effects on EDTA-dependent pseudo platelet aggregation , which is suitable for the PLT counting.%目的 探讨阿米卡星、噻氯匹啶两种药物在体外对血小板依赖性聚集的抑制作用.方法 采用XT-1800i五分类血球分析仪,对添加不同药物浓度抗凝血进行计数分析,并与手工法计数结果比较.结果 加入阿米卡星或噻氯匹啶的抗凝管与EDTA-K2抗凝管计数血小板有显著差异(P<0.01),而与手工法比较无显著差异(P>0.05);对于血小板平均体积(MPV)测定与常规测定比较无显著差异(P>0.05).结论 阿米卡星、噻氯匹啶对EDTA依赖性假性血小板聚集具有很好的抑制作用,适用于血小板的测定.

  9. Platelet function tests: a comparative review

    Directory of Open Access Journals (Sweden)

    Paniccia R

    2015-02-01

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

  10. The Influence of Low Platelet Count on Whole Blood Aggregometry Assessed by Multiplate

    DEFF Research Database (Denmark)

    Stissing, Trine; Dridi, Nadia P; Ostrowski, Sisse R;

    2011-01-01

    The Multiplate, a whole blood (WB) platelet function test, has shown promising results identifying patients on antiplatelet therapy at increased risk of rethrombosis. In the present study, the influence of low platelet count on platelet aggregation was analyzed and compared with aggregation results...... in an artificial matrix, platelet-rich plasma (PRP). Heparinized and citrated blood was diluted with autologous plasma to platelet concentrations 200 to 25 × 10(9)/L in WB samples (n = 10) and 200 to 100 × 10(9)/L in PRP samples (n = 7). The platelet aggregation was investigated by the ADP-, ASPI-, COL-, and TRAP...

  11. Synergism interaction between arachidonic acid by 5-hydroxytryptamine in human platelet aggregation is mediated through multiple signalling pathways%多种信号途径介导花生四烯酸与5-羟色胺在促人类血小板凝集中的协同作用

    Institute of Scientific and Technical Information of China (English)

    Sheikh Arshad SAEED; Huma RASHEED; Anwar-ul-Hassan GILANI

    2003-01-01

    AIM: To examine the signalling mechanisms involved in the synergistic interaction of 5-hydroxytryptamine (5-HT)and arachidonic acid (AA) in human platelet aggregation. METHODS: Blood was obtained from healthy human subjects, mixed with 3.8 % sodium citrate (9:1), and centrifuged to prepare platelet rich plasma (PRP). Aggregation was monitored using a Dual-channel Lumi-aggregometer. The agonist-induced influx of Ca2+ was measured using Fura-2 AM. TXA2 formation was studied using radiochemical method. RESULTS: Subthreshold concentration of 5-HT (2 μmol/L) potentiated the effect of low dose of AA (0.2 mmol/L) in human platelets. This synergistic effect was blocked by 5-HT2 receptor antagonist (methysergide IC50=5.2 nmol/L; cyproheptadine IC50=0.6 nmol/L), and thromboxane A2 receptor antagonist (SQ 29 548; IC50=30 nmol/L), showing that the effect is receptor-mediated.To examine the down-stream signalling pathways, we found that such an interaction was inhibited by calcium channel blockers (diltiazem; IC50=3 μmol/L and verapamil; IC50=5 μmol/L), phospholipase C (PLC) inhibitor (U73122;IC50=4 μmol/L), cyclooxygenase inhibitor, (indomethacin; IC50=0.2 μmol/L) and mitogen-activated protein (MAP)kinase inhibitor (PD98059; IC50=3 μmol/L). The effect was also inhibited by a specific tyrosine light chain kinase (TLCK) inhibitor, herbimycin A with IC50 value of 5 μmol/L. Pretreatment of platelet with 5-HT and AA induced rise in intracellular calcium and this effect was blocked by verapamil. CONCLUSION: The synergism between 5-HT and AA in platelet aggregation involves activation of PLC/Ca2+, COX, and MAP kinase pathways.

  12. 麒麟菜中多肽的提取及多肽的抗血小板聚集和抗菌活性%Peptides extracted from eucheuma and their activity against platelet aggregation and bacterial growth

    Institute of Scientific and Technical Information of China (English)

    刘彬; 余华军; 伍俊; 崔运忠; 张海涛

    2016-01-01

    was designed to establish a feasible method of purifying polypeptides from eucheuma and investigate their activity against platelet aggre⁃gation and bacterial growth. Methods We extracted peptides from eucheuma with acidic solution, detected the effects of different doses of small molecular polypeptide ( 0, 5, 10, 20, and 40μg/mL) on the growth of Escherichia coli ( D1314) and Staphylococcus aureus (s.agr+, RN4220) using the method of turbidity, and analyzed the anti⁃platelet aggregation activity of the peptides with a whole blood aggregometer. Results The rates of peptides extracted from 50, 100,150, and 200 g of eucheuma were 0.382%, 0.405%, 0.389%, and 0.389%, respectively. The purified sample exhibited a single band on SDS⁃PAGE. The relative molecular weight of the peptides was about 3kD. The extracted peptides inhibited the growth of Escherichia coli, Staphylococcus aureus, and thrombin⁃induced platelet aggregation in a dose⁃dependent manner, with inhibition rates of 44.71%, 51.86%, and 75.00%, respectively. Conclusion The present method can be used to successfully purify low⁃molecular⁃weight peptides from eucheuma and effectively inhibit platelet aggre⁃gation and bacterial growth. The peptides extracted is a potential anti⁃platelet aggregation agent.

  13. Stability of lyophilized human platelets loaded with small molecule carbohydrates.

    Science.gov (United States)

    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.

  14. Platelet cytoskeleton and its hemostatic role.

    Science.gov (United States)

    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.

  15. 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.

    Science.gov (United States)

    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.

  16. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets

    OpenAIRE

    Ye-Ming Lee; Kuo-Hsien Hsieh; Wan-Jung Lu; Hsiu-Chu Chou; Duen-Suey Chou; Li-Ming Lien; Joen-Rong Sheu; Kuan-Hung Lin

    2012-01-01

    Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.). Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation...

  17. Calpain Activator Dibucaine Induces Platelet Apoptosis

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2011-03-01

    Full Text Available Calcium-dependent calpains are a family of cysteine proteases that have been demonstrated to play key roles in both platelet glycoprotein Ibα shedding and platelet activation and altered calpain activity is associated with thrombotic thrombocytopenic purpura. Calpain activators induce apoptosis in several types of nucleated cells. However, it is not clear whether calpain activators induce platelet apoptosis. Here we show that the calpain activator dibucaine induced several platelet apoptotic events including depolarization of the mitochondrial inner transmembrane potential, up-regulation of Bax and Bak, down-regulation of Bcl-2 and Bcl-XL, caspase-3 activation and phosphatidylserine exposure. Platelet apoptosis elicited by dibucaine was not affected by the broad spectrum metalloproteinase inhibitor GM6001. Furthermore, dibucaine did not induce platelet activation as detected by P-selectin expression and PAC-1 binding. However, platelet aggregation induced by ristocetin or α-thrombin, platelet adhesion and spreading on von Willebrand factor were significantly inhibited in platelets treated with dibucaine. Taken together, these data indicate that dibucaine induces platelet apoptosis and platelet dysfunction.

  18. Platelet scintigraphy in atherothrombotic disease

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Yoshinari (Osaka National Hospital (Japan))

    1993-01-01

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

  19. Research of the relevance with storage temperature fluctuations on the frozen platelet occurrence of irreversible aggregation%贮存温度波动与冰冻血小板不可逆聚集发生的相关性研究

    Institute of Scientific and Technical Information of China (English)

    李交; 夏传友; 贾璋林

    2009-01-01

    Objective Discussion on the relevance of the frozen platelet preservation during temperature fluctuations with the frozen platelet occurrence irreversible aggregation.Methods During 2006-2008,a total of 1 842 bags of frozen platelets preservation and melting data were statistically analysed,and the relevance of the frozen platelets preservation during temperature fluctuations with the occurrence of platelet irreversible aggregation after resuscitative melting were investigated.Results The frozen platelets storage temperature between -80 ℃ and -60 ℃ and -80 ℃ and -50 ℃ range of fluctuation,the platelets after melt resuscitative occurrence irreversible aggregation were 6.39% and 31.21%.Compared the two observation groups with the control group(preservation temperature between -80 ℃ and -70 ℃ range of fluctuation),there were significant differences(P<0.01).Under the preservation temperature between -80 ℃ and -50 ℃ range of fluctuation,apheresis platelets and concentrate platelets after melt resuscitative,apheresis platelet occurrence irreversible aggregation was 72.97%,the concentrate platelet occurrence irreversible aggregation was 18.33%. Compared the two groups,there were significant difference (χ2=39.33,P<0.01);under preservation temperature between -80 ℃ and -60 ℃ range of fluctuation,apheresis platelet and concentrate platelet after melt resuscitative,there were no significant difference(χ2=0.89,P>0.05).Conclusion Under preservation temperature between -80 ℃ and -60 ℃ and between -80 ℃ and -50 ℃ range of fluctuation,the platelet after melt resuscitative occurrence irreversible aggregation,incidence could occur often.Under preservation temperature between -80 ℃ and -70 ℃ range of fluctuation,the platelet after melt resuscitative occurrence irreversible aggregation,there is few incidence.Temperature range between -80 ℃ and -70 ℃ can be used as the current Blood Bank of frozen platelet reference temperature choice

  20. Acquired platelet function defect

    Science.gov (United States)

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

  1. Platelet function in patients with a history of unexplained recurrent miscarriage who subsequently miscarry again.

    LENUS (Irish Health Repository)

    Dempsey, Mark Anthony

    2015-05-01

    This study was designed to evaluate platelet aggregation in pregnant women with a history of unexplained recurrent miscarriage (RM) and to compare platelet function in such patients who go on to have either another subsequent miscarriage or a successful pregnancy.

  2. Epinephrine enhances platelet-neutrophil adhesion in whole blood in vitro.

    NARCIS (Netherlands)

    Horn, N.A.; Anastase, D.M.; Hecker, K.E.; Baumert, J.H.; Robitzsch, T.; Rossaint, R.

    2005-01-01

    Previous studies showed that alpha- or beta-adrenoceptor stimulation by catecholamines influenced neutrophil function, cytokine liberation, and platelet aggregability. We investigated whether adrenergic stimulation with epinephrine also alters platelet-neutrophil adhesion. This might be of specific

  3. Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis.

    Science.gov (United States)

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

    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.

  4. Platelet and other hemostatic characteristics in patients with chronic urticaria.

    Science.gov (United States)

    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.

  5. Platelet Function Tests in Bleeding Disorders.

    Science.gov (United States)

    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

  6. Effective estimation of correct platelet counts in pseudothrombocytopenia using an alternative anticoagulant based on magnesium salt

    OpenAIRE

    2013-01-01

    Pseudothrombocytopenia remains a challenge in the haematological laboratory. The pre-analytical problem that platelets tend to easily aggregate in vitro, giving rise to lower platelet counts, has been known since ethylenediamine-tetra acetic acid EDTA and automated platelet counting procedures were introduced in the haematological laboratory. Different approaches to avoid the time and temperature dependent in vitro aggregation of platelets in the presence of EDTA were tested, but none of them...

  7. Regulation of fibrinogen receptor expression on human platelets

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Effect of a Korean traditional formulation, Hwaotang, on superoxide generation in human neutrophils, platelet aggregation in human blood, and nitric oxide, prostaglandin E2 production and paw oedema induced by carrageenan in mice.

    Science.gov (United States)

    Park, Won-Hwan; Park, Soo-Young; Kim, Hyung-Min; Kim, Cheorl-Ho

    2004-02-01

    Hwaotang, a traditional Korean medicinal formulation, is a dried decoctum of a mixture of 7 herbal medicines, consisting of Angelica gigantis Radix, Rehmanniae radix, Paeoniae radix, Ciniamomi cortex, Cnidii rhizoma, Persicae semen and Carthami flos. We have investigated that Hwaotang water extract (HOT) has various effects on stimulus-induced superoxide generation in human neutrophils. The effects of HOT on superoxide generation in human neutrophils were investigated. HOT significantly inhibited N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide generation in a concentration-dependent manner, but not that induced by arachidonic acid (AA). On the other hand, HOT enhanced superoxide generation induced by phorbol 12-myristate 13-acetate (PMA) in a concentration-dependent manner. The superoxide generation induced by PMA with HOT was suppressed by staurosporine, an inhibitor of protein kinase C, but was not suppressed by genistein, an inhibitor of protein tyrosine kinase. Tyrosyl phosphorylation of a 58 kDa protein, which was increased by fMLP, was inhibited by HOT. HOT also inhibited the generation of a 47 kDa protein and platelet aggregation in human blood. The results suggest that protein tyrosine kinase participates in fMLP-mediated superoxide generation by HOT-treated human neutrophils. HOT inhibited neutrophil functions, including degranulation, superoxide generation, and leukotriene B4 production, without any effect on 5-lipoxygenase activity. HOT reduced nitric oxide (NO) and prostaglandin E2 production in mouse peritoneal macrophages stimulated with lipopolysaccharide, whereas no influence on the activity of iNOS, COX-2 or COX-1 was observed. HOT significantly reduced mouse paw oedema induced by carrageenan. Western blot analysis showed that HOT reduced the expression of iNOS and COX-2. The results indicate that HOT exerts anti-inflammatory effects related to the inhibition of neutrophil functions and of NO and prostaglandin E2 production, which

  9. Functional alterations of human platelets following indium-111 labelling using different incubation media and labelling agents

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Yoshinari; Imaizumi, Masatoshi (Osaka National Hospital (Japan). Dept. of Cardiovascular Medicine and Radiological Science); Kimura, Kazufumi (Osaka Univ. (Japan). Dept. of Nuclear Medicine); Matsumoto, Masayasu; Kamada, Takenobu (Osaka Univ. (Japan). 1. Dept. of Internal Medicine)

    1991-05-01

    Human platelets were labelled in the absence of presence of plasma using {sup 111}In-labelled oxine sulphate, tropolone or 2-mercaptopyridine-N-oxide (MPO). Under in vitro and in vivo conditions, platelet functions were evaluated by measuring their aggregability, survival, recovery and early distribution. High labelling efficiency was achieved in saline labelling, whereas with plasma labelling, it was necessary to concentrate the platelet-rich plasma to 4.8x10{sup 6} platelets/{mu}l. The aggregation of platelets labelled in plasma or saline was compared with that of controls; platelets labelled in saline showed lower aggregability in 2 {mu}M ADP but not in 5 {mu}M ADP nor with collagen. No significant differences in platelet survival and recovery were noted between platelets labelled in plasma and those labelled in saline. Our results indicate that partial loss of ADP aggregability in vitro does not influence the in vivo viability of platelets labelled in saline. Scintigraphic studies showed that platelets labelled in a saline medium were temporarily sequestrated in the liver but not in the spleen or heart. Thus, platelet labelling in saline does not affect platelet function adversely, but platelets labelled in plasma are more desirable for assessing the early distribution of platelets in the reticuloendothelial system. (orig.).

  10. Inibição e reversão da agregação plaquetária de eqüinos in vitro com o uso de ketoprofeno, fenilbutazona e flunixim meglumine In vitro inibition and reversion of equine platelet aggregation using ketoprophen, phenylbutazone and flunixin meglumin

    Directory of Open Access Journals (Sweden)

    Fabiola O. Paes Leme

    2009-10-01

    Full Text Available Como são várias as enfermidades e os distúrbios que induzem à hipercoagulabilidade e à pré-ativação de plaquetas em eqüinos. A atividade de medicamentos utilizados para controle dessas enfermidades sobre a agregação de plaquetas pode, não apenas servir para avaliar sua evolução, como também a resposta terapêutica. Com o objetivo de avaliar a prevenção e a reversão da agregação plaquetária de eqüinos in vitro foram utilizados os antiinflamatórios não esteroidais (AINES: ketoprofeno, fenilbutazona e flunixim meglumine. A comparação demonstrou que a fenilbutazona e o ketoprofeno previnem a agregação de plaquetas de eqüinos induzida pelo ADP, de forma mais eficaz do que o flunixim-meglumine e, superior ao fragmento monoclonal de anticorpo Reopro, sendo semelhante a dos bloqueadores de receptores de membrana Ro-438857 e RGDS. Quanto a reverão da agregação plaquetária tanto a fenilbutazona quanto o ketoprofeno demonstraram efeitos dose-dependente.Several diseases may lead to platelet pre-activation and hypercoagulability states in horses. The activity of many drugs against platelet aggregation may, not only contribute to the evaluation of a disease but also its response to the therapy. With the aim to study in vitro prevention and reversion of platelet aggregation, the non steroidal anti-inflammatory drug (NSAID: ketoprophen, phenylbutazone and flunixin-meglumin were evaluated. The comparison demonstrated that phenylbutazone and ketoprophen prevented platelet aggregation induced by ADP better than flunixin-meglumin, in a superior manner to the monoclonal antibody Reopro, and in a better way than the membrane receptor blockers Ro-438857 and RGDS. The reversion of platelet aggregation demonstrated that even phenylbutazone or ketoprophen have a dose-dependent effect.

  11. Biochemical and functional abnormalities in hypercholesterolemic rabbit platelets

    Energy Technology Data Exchange (ETDEWEB)

    Dalal, K.B.; Ebbe, S.; Mazoyer, E.; Carpenter, D.; Yee, T. (Lawrence Berkeley Laboratory, CA (USA))

    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.

  12. Resveratrol preserves the function of human platelets stored for transfusion.

    Science.gov (United States)

    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.

  13. Thrombopoietin induces p-selectin expression on platelets and subsequent platelet/leukocyte interactions.

    Science.gov (United States)

    Tibbles, Heather E; Navara, Christopher S; Hupke, Michael A; Vassilev, Alexei O; Uckun, Fatih M

    2002-04-12

    Ligation of thrombopoietin (TPO) to the platelet c-Mpl receptor induces numerous biochemical pathways in the absence of aggregation. Two forms of recombinant TPO are currently in clinical trials for the treatment of thrombocytopenia. This study focuses on the effects of the full-length recombinant human TPO (rhTPO) on platelets in a whole blood system. Platelet-leukocyte associations (PLAs) were visualized following rhTPO stimulation as CD42b/CD 45 double positive clusters by FACS analysis. Treatment of washed platelets with rhTPO induced granule release and expression of the leukocyte adhesion receptor P-selectin (CD 62P) in the absence of aggregation and calcium mobilization. RhTPO also induced platelet-leukocyte interactions in whole blood. Following stimulation, leukocytes were recruited by platelets through P-selectin in a calcium-dependent manner. rhTPO stimulates platelet-leukocyte associations in whole blood through expression of platelet P-selectin. To our knowledge, this is the first report that identifies TPO as a promoter of platelet-leukocyte interactions.

  14. Mechanism of platelet activation induced by endocannabinoids in blood and plasma.

    Science.gov (United States)

    Brantl, S Annette; Khandoga, Anna L; Siess, Wolfgang

    2014-01-01

    Platelets play a central role in atherosclerosis and atherothrombosis, and circulating endocannabinoids might modulate platelet function. Previous studies concerning effects of anandamide (N-arachidonylethanolamide) and 2-arachidonoylglycerol (2-AG) on platelets, mainly performed on isolated cells, provided conflicting results. We therefore investigated the action of three main endocannabinoids [anandamide, 2-AG and virodhamine (arachidonoylethanolamine)] on human platelets in blood and platelet-rich plasma (PRP). 2-AG and virodhamine induced platelet aggregation in blood, and shape change, aggregation and adenosine triphosphate (ATP) secretion in PRP. The EC50 of 2-AG and virodhamine for platelet aggregation in blood was 97 and 160 µM, respectively. Lower concentrations of 2-AG (20 µM) and virodhamine (50 µM) synergistically induced aggregation with other platelet stimuli. Platelet activation induced by 2-AG and virodhamine resembled arachidonic acid (AA)-induced aggregation: shape change, the first platelet response, ATP secretion and aggregation induced by 2-AG and virodhamine were all blocked by acetylsalicylic acid (ASA) or the specific thromboxane A2 (TXA2) antagonist daltroban. In addition, platelet activation induced by 2-AG and virodhamine in blood and PRP were inhibited by JZL184, a selective inhibitor of monoacylglycerol lipase (MAGL). In contrast to 2-AG and virodhamine, anandamide, a substrate of fatty acid amidohydrolase, was inactive. Synthetic cannabinoid receptor subtype 1 (CB1) and 2 (CB2) agonists lacked stimulatory as well as inhibitory platelet activity. We conclude that 2-AG and virodhamine stimulate platelets in blood and PRP by a MAGL-triggered mechanism leading to free AA and its metabolism by platelet cyclooxygenase-1/thromboxane synthase to TXA2. CB1, CB2 or non-CB1/CB2 receptors are not involved. Our results imply that ASA and MAGL inhibitors will protect platelets from activation by high endocannabinoid levels, and that

  15. [Glycoproteins, inherited diseases of platelets, and the role of platelets in wound healing].

    Science.gov (United States)

    Nurden, Alan T; Nurden, Paquita

    2013-02-01

    Recognition that platelets have a glycocalyx rich in membrane glycoproteins prompted the discovery in France that inherited bleeding syndromes due to defects of platelet adhesion and aggregation were caused by deficiencies in major receptors at the platelet surface. Identification of the alpha IIb beta3 integrin prompted the development of powerful anti-thrombotic drugs that have gained worldwide use. Since these discoveries, the genetic causes of many other defects of platelet function and production have been elucidated, with the identification of an ADP receptor, P2 Y12, another widespread target for anti-thrombotic drugs. Discovery of the molecular basis of a rare disease of storage of biologically active proteins in platelet alpha-granules has been accompanied by the recognition of the roles of platelets in inflammation, the innate immune system and tissue repair, opening new avenues for therapeutic advances.

  16. 不同分子量肝素对肾炎患者血小板活化和凝聚功能影响的研究%Effects of Different Molecular Weight Heparin on Functions of Activation and Aggregation of Platelet in Patients with Glomerulonephritis

    Institute of Scientific and Technical Information of China (English)

    李宏向; 张纪云; 孙念政; 郑楠; 常向秀

    2001-01-01

    Objective:To investigate the effects of different molecular weight heparin on functions of activation and aggregation of platelet in the patients with glomerulonephritis(GN).Methods:We tested the platelet count(PLT),mean platelet volume(MPV),platelet distribution width(PDW) by automatic blood analytic apparatus,and detected the expressive levels of platelet granule membrane protein(GMP-140) and fibrinogen receptor(GPⅡb-Ⅲa)by flow cytometry.Results:The study showed low molecular weight heprin(LMWH) did not afected significantly PLT,MPV,PDW in the patients with GN(P>0.05) and the expressive levels of GMP-140 and GPⅡb-Ⅲa on the surface of platelet(P>0.05);general heparin(GH)led to PLT decreasing,MPV enlarging,PDW exceeding normal volume in the patients with glomerulosclerosis(GS),membranous nephropathy(MN) or proliferative glomerulonephritis(PGN)(P<0.01),GH also led to the expressive levels of GMP-140 and GPⅡb-Ⅲa on platelets in the patients with GS,MN,PGN significant increasing(P<0.01).Conclusion:LMWH may not significantly affect the functions of activation and aggregation of platelet in the patients with GN,however,GH may strengthen the functions of activation and aggregation of platelet in the patients with GN.%目的:探讨普通肝素(GH)和低分子量肝素(LMWH)对肾炎患者血小板活化和凝聚的影响。方法:用全自动血细胞分析仪测定血小板计数(PLT)、体积(MPV)、分布宽度(PDW),用流式细胞学方法测定血小板表面颗粒膜蛋白(GMP-140)和纤维蛋白原受体(GPⅡb-Ⅲa)。结果:文中显示LMWH对各型肾炎患者PLT、MPV、PDW无显著性影响,可使血小板GMP-140和GPⅡb-Ⅲa表达水平上调,但未达统计学意义(P>0.05);GH可使GS、MN、PGN患者PLT减少,MPV增大(P<0.01),PDW超过正常值,且5.1%患者PLT降至100×109/L以下,使血小板GMP-140和GPⅡb-Ⅲa表达水平显著性上调(P<0.01),且显著高于LMWH治疗

  17. Effect of safflower yellow on platelet activating factor mediated platelet activation in patients with coronary heart disease

    Directory of Open Access Journals (Sweden)

    Damin Huang

    2012-06-01

    Full Text Available The platelet aggregation and 5-HT release by washed platelet from coronary heart disease patients following platelet activating factor (PAF treatment were detected by turbidimetry and O-phthalaldehyde assay. The free calcium concentration in the platelets was measured with the fura-2/AM probe fluorescent technique. Results showed safflower yellow could inhibit the PAF induced washed platelet aggregation and 5-HT release, which were in a safflor-yellow-dose dependent manner. When the PAF was 2.0×10-9 mol/L, the inhibition rate of platelet aggregation was 26.2%, 41.3%, 58.1%, 81.2%, and the inhibition rate of 5-HT release was 3.7%, 11.9%, 29.9% and 54.4% after treatment with safflower yellow at 0.21, 0.42, 0.85 and 1.69 g/L, respectively. The study concludes safflower yellow can inhibit the PAF induced platelet aggregation, 5-HT release by platelets and elevation of free calcium in platelets.

  18. The effect of centrifugation speed and time on pre-analytical platelet activation

    DEFF Research Database (Denmark)

    Söderström, Anna Cecilia; Nybo, Mads; Nielsen, Christian

    2016-01-01

    . METHODS: Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean...... platelet volume (MPV), immature platelet fraction (IPF), and platelet distribution width (PDW) were measured. Platelet aggregation in platelet-rich plasma induced by arachidonic acid (AA), ADP or thrombin receptor activator peptide-6 (TRAP) was tested by 96-well aggregometry. RESULTS: The median percentage...... of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), p...

  19. Evaluation of electrical aggregometry: comparison with optical aggregometry, secretion of ATP, and accumulation of radiolabeled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Ingerman-Wojenski, C.; Smith, J.B.; Silver, M.J.

    1983-01-01

    Platelet aggregation has been most commonly studied in vitro by measuring increases in light transmission as platelets aggregate in PRP (platelet-rich plasma). Recently, an electrical impedance method for measuring platelet aggregation has been introduced. This method can be used with either PRP or whole blood and measures an increase in impedance across electrodes placed in the blood samples as platelets accumulate on them. Results obtained by the two methods were compared using ADP and collagen as aggregating agents, and also have measured the secretion of platelet ATP simultaneously. Although the aggregometry results were similar, recordings obtained by the electrical method did not distinguish two waves of platelet aggregation or correlate with secretion as well as recordings obtained by the optical method. When PGI/sub 2/ (prostacyclin) or PGE/sub 1/ (prostaglandin E/sub 1/) was added to the PRP, both the rate and extent of the increase in light transmittance were inhibited, but the main effect on the increase in impedance was a decrease in its rate and not in its extent. Increases in impedance and secretion of ATP were also measured in whole blood after the platelets had been labeled with a /sup 125/I-containing antibody specific for platelet surface glycoproteins. It appeared that the increases in impedance lagged several minutes behind the formation of platelet aggregates and the secretion of platelet ATP.

  20. Function of eltrombopag-induced platelets compared to platelets from control patients with immune thrombocytopenia.

    Science.gov (United States)

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

    2013-04-01

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

  1. [A case of pseudothrombocytopenia due to platelet cold agglutinins].

    Science.gov (United States)

    Hayashi, Satoru; Nishiyama, Miho; Jouzaki, Kiyoshi; Tomiyama, Yoshiaki; Kurata, Yoshiyuki

    2005-08-01

    We report a case of pseudothrombocytopenia due to platelet cold agglutinins. Platelet counts were decreased in blood drawn in a tube without anti-coagulant just after withdrawal as well as in blood drawn in a tube with anti-coagulant, such as EDTA-2K, MgSO4, citrate or heparin. In our case, platelet aggregates were noted on blood-smear made from blood samples obtained with and without anti-coagulant. RBC and WBC counts were within the normal range. Platelet aggregates mainly consisted of 2-5 platelets. Patient plasma agglutinated normal platelets at a temperature below 10 degrees C. Immunoglobulin class was determined as IgM by flow cytometry.

  2. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets.

    Science.gov (United States)

    Lee, Ye-Ming; Hsieh, Kuo-Hsien; Lu, Wan-Jung; Chou, Hsiu-Chu; Chou, Duen-Suey; Lien, Li-Ming; Sheu, Joen-Rong; Lin, Kuan-Hung

    2012-01-01

    Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.). Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca(2+)](i) mobilization, thromboxane A(2) formation, hydroxyl radical (OH(●)) formation, and phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinase (MAPK), and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A(2) formation, thereby leading to inhibition of [Ca(2+)](i) and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  3. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus, Prevents Platelet Activation in Human Platelets

    Directory of Open Access Journals (Sweden)

    Ye-Ming Lee

    2012-01-01

    Full Text Available Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.. Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca2+]i mobilization, thromboxane A2 formation, hydroxyl radical (OH● formation, and phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinase (MAPK, and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A2 formation, thereby leading to inhibition of [Ca2+]i and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  4. Platelet satellitism in infectious disease?

    Science.gov (United States)

    Laskaj, Renata; Sikiric, Dubravka; Skerk, Visnja

    2015-01-01

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

  5. Functional platelet defects in children with severe chronic ITP as tested with 2 novel assays applicable for low platelet counts.

    Science.gov (United States)

    van Bladel, Esther R; Laarhoven, Annemieke G; van der Heijden, Laila B; Heitink-Pollé, Katja M; Porcelijn, Leendert; van der Schoot, C Ellen; de Haas, Masja; Roest, Mark; Vidarsson, Gestur; de Groot, Philip G; Bruin, Marrie C A

    2014-03-06

    Immune thrombocytopenia (ITP) is an autoimmune disease with a complex heterogeneous pathogenesis and a bleeding phenotype that is not necessarily correlated to platelet count. In this study, the platelet function was assessed in a well-defined cohort of 33 pediatric chronic ITP patients. Because regular platelet function test cannot be performed in patients with low platelet counts, 2 new assays were developed to determine platelet function: first, the microaggregation test, measuring in platelets isolated from 10 mL of whole blood the platelet potential to form microaggregates in response to an agonist; second, the platelet reactivity assay, measuring platelet reactivity to adenosine diphosphate (ADP), convulxin (CVX), and thrombin receptor activator peptide in only 150 μL of unprocessed whole blood. Patients with a severe bleeding phenotype demonstrated a decreased aggregation potential upon phorbol myristate acetate stimulation, decreased platelet degranulation following ADP stimulation, and a higher concentration of ADP and CVX needed to activate the glycoprotein IIbIIIa complex compared with patients with a mild bleeding phenotype. In conclusion, here we have established 2 functional tests that allow for evaluation of platelet function in patients with extremely low platelet counts (platelet function is related to bleeding phenotype in chronic ITP.

  6. Platelet Function in Basset Hound Hereditary Thrombopathy.

    Science.gov (United States)

    1986-01-01

    Hematol, 17(4),242-258, 1980. 5. CHARO, I.F., FEINMAN , R.D., DETWILER, T.C. Interrelation of platelet aggregation and secretion. J. Clin. Invest...of dogs affected with Basset Hound Hereditary Thrombopathy. Thromb Au, 3, 61-71, 1985. 4. DETWILER, T.C., CHARO, I.F., AND FEINMAN , R.D. Evidence...glycoproteins. Surv Synth Path Res 1:274, 1983. Charo IF, Feinman RD, and Detwiler TC. Interrelation of platelet aggregation and secretion. J Clin Invest 60

  7. Platelet receptor polymorphisms do not influence Staphylococcus aureus-platelet interactions or infective endocarditis.

    Science.gov (United States)

    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.

  8. Plasma functionalization of titanium surface for repulsion of blood platelets

    OpenAIRE

    Cvelbar, Uros; Modic, Martina; Kovac, J.; Lazovic, S; Filipic, G; Vujosevic, D; Junkar, Ita; Elersic, Kristina; Brühl, S.P.; Canal Barnils, Cristina; Belmonte, Thierry; Mozetic, Miran

    2012-01-01

    Thrombosis and restenosis are the most common problems during insertion of biocompatible implants like titanium stents into human blood, due to aggregation of platelets on their surfaces. Because of this reason, we studied the response of blood platelets to a plasma treated titanium surface. The aim was to design a functionalized surface which would repel blood platelets or prevent their adhesion. Therefore, we functionalized surfaces with low-temperature inductively coupled oxygen plasma tre...

  9. A factor VIII-derived peptide enables von Willebrand factor (VWF)-binding of artificial platelet nanoconstructs without interfering with VWF-adhesion of natural platelets.

    Science.gov (United States)

    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.

  10. Platelets and white blood cells in acute coronary syndromes

    NARCIS (Netherlands)

    Smit, Jaap Jan Johannes

    2008-01-01

    In this thesis, we have studied the role of leukocytes and platelets as methods to measure platelets aggregation, in the clinical management of presenting with acute coronary syndromes. We have tried to incidence and to identify predictors of adverse cardiac events with function tests or inflammator

  11. Platelet Function Tests

    Science.gov (United States)

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

  12. Congenital platelet function defects

    Science.gov (United States)

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

  13. Hereditary sideroblastic anemia with associated platelet abnormalities.

    Science.gov (United States)

    Soslau, G; Brodsky, I

    1989-12-01

    A 62 year old male (R.H.) presented with a mild anemia (Hb 11-12 gm%) and a history of multiple hemorrhagic episodes. The marrow had 40-50% sideroblasts. Marrow chromosomes were normal. His wife was hematologically normal, while one daughter, age 30 years, had a sideroblastic anemia (Hb 11-12 gm%) with 40-50% sideroblasts in the marrow. Her anemia was first noted at age 15 years. Administration of vitamin B6 did not correct the anemia in either the father or daughter. Platelet abnormalities inherited jointly with this disorder are described for the first time. Both R.H. and his daughter had prolonged bleeding times, with normal PTT, PT times, fVIII:C, fVIII:Ag levels, and vWF multimers, which may rule out a von Willebrand's disease. They have normal platelet numbers but abnormally low platelet adhesiveness and greatly depressed ADP, collagen, and epinephrine responsiveness. Response to ristocetin was in the low normal range, and aggregation with thrombin was normal. While desmopressin completely normalized R.H.'s bleeding time, none of these platelet parameters were improved. No differences in the SDS PAGE protein patterns of RH platelets could be detected in comparison to normal samples. His platelets took up and released serotonin (5HT) normally, and electron micrographs defined no morphological abnormalities. However, no ATP was released from platelets activated with collagen, and when followed by thrombin about fourfold greater ATP was released by control platelets as compared to RH platelets. The dense granule fraction derived from RH platelets contained about 20% the level of ATP, 40% the level of ADP, and 50% the level of 5HT detected in a normal sample. The results indicate that the bleeding disorder is related to a non-classical heritable storage pool defect. The connection between the inherited sideroblastic anemia and platelet defects is obscure.

  14. Common variants in the human platelet PAR4 thrombin receptor alter platelet function and differ by race

    Science.gov (United States)

    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

  15. The Influence of Low Platelet Count on Whole Blood Aggregometry Assessed by Multiplate

    DEFF Research Database (Denmark)

    Stissing, Trine; Dridi, Nadia P; Ostrowski, Sisse R

    2011-01-01

    in an artificial matrix, platelet-rich plasma (PRP). Heparinized and citrated blood was diluted with autologous plasma to platelet concentrations 200 to 25 × 10(9)/L in WB samples (n = 10) and 200 to 100 × 10(9)/L in PRP samples (n = 7). The platelet aggregation was investigated by the ADP-, ASPI-, COL-, and TRAP...

  16. Reduction of CTRP9, a novel anti-platelet adipokine, contributes to abnormal platelet activity in diabetic animals.

    Science.gov (United States)

    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 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.

  17. Platelet content of nitric oxide synthase 3 phosphorylated at Serine 1177 is associated with the functional response of platelets to aspirin.

    Directory of Open Access Journals (Sweden)

    Javier Modrego

    Full Text Available OBJECTIVE: To analyse if platelet responsiveness to aspirin (ASA may be associated with a different ability of platelets to generate nitric oxide (NO. PATIENTS/METHODS: Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26 and ASA-resistant (n = 24 using a platelet functionality test (PFA-100. RESULTS: ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3 was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2 isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position -786 (T(-786 → C in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser(1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser(1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018 of NOS3 phosphorylation at Ser(1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser(1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. CONCLUSIONS: Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser(1177.

  18. Sulfonylureas and on-clopidogrel platelet reactivity in type 2 diabetes mellitus patients.

    Science.gov (United States)

    Harmsze, Ankie M; Van Werkum, Jochem W; Moral, Fulya; Ten Berg, Jurri N M; Hackeng, Christian M; Klungel, Olaf H; De Boer, Anthonius; Deneer, Vera H M

    2011-01-01

    Clopidogrel is a prodrug that needs to be converted in?vivo by several cytochrome (CYP) P450 iso-enzymes to become active. Both clopidogrel and the oral hypoglycemic drug class sulfonylureas are metabolized by the iso-enzyme CYP2C9. The objective of the study was to evaluate the relationship of sulfonylureas and on-clopidogrel platelet reactivity in type 2 diabetes mellitus patients undergoing elective coronary stent implantation. In this prospective, observational study, on-clopidogrel platelet reactivity was quantified using adenosine diphosphate (ADP)-induced light transmittance aggregometry in 139 type 2 diabetes mellitus patients undergoing elective coronary stent implantation treated with clopidogrel and aspirin. High on-clopidogrel platelet reactivity was defined as >70.7% platelet reactivity to 20 μmol/L ADP. A total of 53 patients (38.1%) were on concomitant treatment with sulfonylureas. The remaining 86 patients were on other hypoglycemic drugs. On-clopidogrel platelet reactivity was significantly higher in patients with concomitant sulfonylurea treatment as compared to patients without concomitant sulfonylurea treatment (for 5 μmol/L ADP: 46.0% ± 11.8 vs. 40.6% ± 16.0; p=0.035, adjusted p=0.032 and for 20 μmol/L ADP: 64.6% ± 10.8 vs. 58.7% ± 15.5; p=0.019, adjusted p=0.017). The concomitant use of sulfonylureas was associated with a 2.2-fold increased risk of high on-clopidogrel platelet reactivity (OR 2.2, 95% CI 1.1-4.7, p=0.039 and after adjustment for confounders: OR(adj) 2.0, 95% CI 1.0-5.7, p=0.048). Concomitant treatment with sulfonylureas might be associated with decreased platelet inhibition by clopidogrel in type 2 diabetes mellitus patients on dual antiplatelet therapy undergoing elective coronary stent implantation.

  19. Clopidogrel pretreatment of patients with ST-elevation myocardial infarction does not affect platelet reactivity after subsequent prasugrel-loading: platelet reactivity in an observational study.

    Science.gov (United States)

    Nührenberg, Thomas G; Trenk, Dietmar; Leggewie, Stefan; Ristau, Inga; Amann, Michael; Stratz, Christian; Hochholzer, Willibald; Valina, Christian M; Neumann, Franz-Josef

    2013-01-01

    Current guidelines recommend prasugrel or ticagrelor for patients undergoing percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). Whereas available data support ticagrelor independent of pretreatment with clopidogrel, corresponding data for prasugrel are missing. Here, we investigated platelet reactivity after loading with prasugrel in clopidogrel-naïve vs. clopidogrel-pretreated patients. Forty-seven consecutive patients with STEMI referred for primary PCI were enrolled. Use of GPIIb/IIIa inhibitors and known contraindications to prasugrel served as exclusion criteria. A total of 31 patients were already treated with a loading dose of clopidogrel 600 mg by the emergency medical system before admission, while 16 patients were P2Y12 antagonist naïve. All patients received a loading dose of prasugrel 60 mg immediately before PCI. Adenosine diphosphate (ADP) induced platelet reactivity was determined by VerifyNow™ P2Y12 assay, by light transmission aggregometry (LTA) and by multiple electrode impedance aggregometry (MEIA; Multiplate™ analyser). No differences in platelet reactivity were observed at day 1 after PCI between the bolus-on-bolus treatment regimen and single prasugrel loading. Platelet reactivity was profoundly decreased to 10 [8-31] platelet reactivity unit (PRU; median [interquartile range]) in patients on clopidogrel + prasugrel vs. 9 [6-60] PRU in patients on prasugrel only (p = 0.916). Consistent results were obtained by LTA and MEIA. The proportion of patients reaching a MEIA associated with increased risk bleeding (<188 AU*min) was also similar between the two study groups. The level of platelet reactivity at day 1 after the 60 mg loading dose of prasugrel was independent of pretreatment with clopidogrel. Our results do not support withholding prasugrel in patients pretreated with clopidogrel who undergo PCI for STEMI.

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

    Directory of Open Access Journals (Sweden)

    Sebastian Hofmann

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

  1. Platelet functions in relation to dietary fats in farmers from two regions of France.

    Science.gov (United States)

    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.

  2. 新型N-取代四氢噻吩并[3,2-c]吡啶类衍生物的合成及其抗血小板聚集活性%Synthesis and Anti-platelet Aggregation Activities of Novel N-substituted-tetrahydrothieno [3,2-c] pyridine Derivatives

    Institute of Scientific and Technical Information of China (English)

    刘颖; 陈立功; 廖上腾; 刘登科

    2013-01-01

    A series of novel piperazine-bearing thienopyridine derivatives (3a ~ 3p) were designed and synthesized from 4,5,6,7-tetrahydrothieno[3,2-c] pyridine.The structures were characterized by 1H NMR,13C NMR,IR and ESI-HR-MS.In vivo anti-platelet aggregation tests in rats showed that 3a ~ 3p exhibited certain anti-platelet aggregation activities.The inhibitions of 3a,3c,3i and 3j were 66.8%,69.5%,70.4% and 65.2%,respectively.%以4,5,6,7-四氢噻吩并[3,2-c]吡啶为起始原料,设计并合成了一系列新型的含哌嗪结构的噻吩并吡啶类化合物(3a ~3p),其结构经1H NMR,13C NMR,IR和ESI-HR-MS表征.大鼠体内抗血小板聚集活性研究表明,3a~3p均具有一定的抗血小板聚集作用,其中3a,3c,3i和3j的抑制率分别为66.8%,69.5%,70.4%和65.2%.

  3. 急性冠状动脉综合征氯吡格雷抵抗患者换用替格瑞洛后的PAR变化%The changes of platelet aggregation ratio in acute coronary syndrome patients with clopigogrel resistance following alternated by ticagrelor

    Institute of Scientific and Technical Information of China (English)

    李枚岭; 李刚

    2015-01-01

    Objective To observe the variance of the platelet aggregation ratio after using ticagrelor for instead of clopidogrel in acute coronary syndrome patients suffering from clopidogrel resistance. Methods Platelet aggregation ratio test induced by adenosine diphosphate (ADP) identified acute coronary syndrome patients with clopidogrel resistance underwent the PCI(percutaneous coronary intervention) from July 2013 to July 2014. The 57 patients with clopidogrel resistance were given 180mg ticagrelor load followed by 90mg twice daily maintenance therapy,for instead of clopidogrel 75mg once daily for 1 month,and the platelet aggregation ratio were tested. Results Platelet aggregation rate had significant difference (P<0.05) statistically after administration of ticagrelor compared with clopidogrel. Conclusion Compared with the regular-dose treatment of clopidogrel,ticagrel can effectively decrease the platelet aggregation ratio in acute coronary syndrome patients with clopidogrel resistance.%目的:探讨急性冠状动脉综合征(ACS)氯吡格雷抵抗患者换用替格瑞洛后血小板聚集率(PAR)的变化情况。方法急性冠状动脉综合征患者,经皮冠状动脉介入治疗(PCI)术后测定二磷酸腺苷(ADP)诱导血小板聚集率,根据血小板聚集率筛选出氯吡格雷抵抗患者57例,男45例,年龄(62.98±10.51)岁,体重指数(24.53±2.53) kg/m2;女12例,年龄(64.17±5.84)岁,体重指数(25.49±3.37) kg/m2。氯吡格雷抵抗患者将氯吡格雷75 mg,1次/d更换为替格瑞洛负荷量180 mg,次日开始90 mg,2次/d。随访30 d,应用替格瑞洛后7、15、30 d检测血小板聚集率。结果服用替格瑞洛后血小板聚集率明显降低,与应用氯吡格雷后血小板聚集率的差异有显著统计学意义(P<0.05),患者吸烟,是否合并高血压或糖尿病及服用降压、降糖药物,其血小板聚集率下降程度之

  4. Platelet-derived microparticles and platelet function profile in children with congenital heart disease.

    Science.gov (United States)

    Ismail, Eman Abdel Rahman; Youssef, Omneya Ibrahim

    2013-01-01

    Platelet microparticles (PMPs) and function profile in children with congenital heart disease (CHD) have not been widely explored. We investigated platelet aggregation, flow cytometric platelet surface receptors (P-selectin and glycoprotein (GP) IIb/IIIa) and PMPs in 23 children with cyanotic CHD (CCHD), 30 children with acyanotic CHD (ACHD) and 30 healthy controls correlating these variables to hematological and coagulation parameters including von Willebrand factor antigen (vWF Ag) as a marker of endothelial dysfunction. Hemoglobin, hematocrit (HCT), D-dimer, and vWF Ag were significantly higher in CCHD than ACHD group. Platelet MPs and P-selectin expression were increased in patients than controls, particularly in CCHD and positively correlated to HCT, D-dimer, and vWF Ag while platelet count, aggregation, and GP IIb/IIIa expression were decreased in CCHD compared with ACHD group and negatively correlated to HCT. The overproduction of PMPs and platelet activation with suppressed aggregation may be implicated in the pathogenesis of coagulation/hemostatic abnormalities in children with CCHD.

  5. Incidence of platelet dysfunction by thromboelastography-platelet mapping in children supported with ECMO: A Pilot Retrospective Study.

    Directory of Open Access Journals (Sweden)

    Arun eSaini

    2016-01-01

    Full Text Available Background: Bleeding complications are common and decrease the odds of survival in children supported with extracorporeal membrane oxygenation (ECMO. The role of platelet dysfunction on ECMO-induced coagulopathy and resultant bleeding complications is not well understood. The primary objective of this pilot study was to determine the incidence and magnitude of platelet dysfunction according to thromboelastography (TEG®-platelet mapping (PM testing. Methods: Retrospective chart review of children <18 years old who required ECMO at a tertiary level hospital. We collected TEG®-PM and conventional coagulation tests data. We also collected demographic, medications, blood products administered, and clinical outcome data. We defined severe platelet dysfunction as less than 50 % aggregation in response to an agonist. Results: We identified 24 out of 46 children on ECMO, who had TEG®-PM performed during the study period. We found the incidence of severe bleeding was 42%, and mortality was 54% in our study cohort. In all samples measured, severe qualitative platelet dysfunction was more common for adenosine diphosphate (ADP-mediated aggregation (92% compared to arachidonic acid (AA-mediated aggregation (75%, (p=0.001. Also, ADP-mediated percent of platelet aggregation was significant lower than AA-mediated platelet aggregation (15% [IQR 2.8-48] vs 49% [IQR 22-82.5], p<0.001. There was no difference in kaolin-activated heparinase TEG® parameters between the bleeding group and the non-bleeding group. Only absolute platelet count and TEG®-PM had increased predictive value on receiver operating characteristics analyses for severe bleeding and mortality compared to ACT. Conclusions: We found frequent and severe qualitative platelet dysfunction on TEG®-PM testing in children on ECMO. Larger studies are needed to determine if the assessment of qualitative platelet function by TEG®-PM can improve prediction of bleeding complications for children on ECMO.

  6. Migration distance-based platelet function analysis in a microfluidic system

    OpenAIRE

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

    2013-01-01

    Aggregation and adhesion of platelets to the vascular wall are shear-dependent processes that play critical roles in hemostasis and thrombosis at vascular injury sites. In this study, we designed a simple and rapid assay of platelet aggregation and adhesion in a microfluidic system. A shearing mechanism using a rotating stirrer provided adjustable shear rate and shearing time and induced platelet activation. When sheared blood was driven through the microchannel under vacuum pressure, shear-a...

  7. Effects of Agrimoni Pilosa aqueous extract on platelet aggregation,coagulation function and hemorheology%仙鹤草水提物体外对血小板聚集、凝血功能及血液流变学的影响

    Institute of Scientific and Technical Information of China (English)

    费鲜明; 陈艳; 吴万飞; 蒋雷; 邱莲女; 周永列

    2013-01-01

    AIM: To observe the in vitro effects of Agrimoni Pilosa aqueous extract on platelet aggregation, coagulation function and hemorheology, and to explore its related mecha nisms of action on hemostatic and coagulation function. METHODS: Platelet rich plasma (PRP) and platelet poor plasma (PPP) from volunteers were mixed with 0,4 ,20 and 80 g/L Agrimoni Pilosa aqueous extract. The maximal platelet aggregation rate (PAR) of PRP induced by adenosine diphosphate (ADP) with platelet aggregation analyzer, expression levels of P-se lection and fibrinogen receptor (Fg-R) were det emined by Flow cytometry. Prothrombin time ( PT ) , activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (Fg) of PPP were detected with blood coagula tion analyzer, respectively, blood doting time (CT) and plasma ionized calcium (Ca2-) were detected with manual method and blood-gas ana lyzer, respectively, coagulable factor VII, VIII, IX and XI were detected by poor factor plasma correcting test. Blood viscosity, plasma viscosi ty and index of red cell aggregation were meas ured with hemorheology analyzer. RESULTS: At 4 g/L group, PAR, Fg-R and P-selectin expres sion levels were significantly lower than those at 0 g/L group (R<0. 01). There was negative correlation between extract dose and any one of PAR, Fg-R and P-selectin level, but positive correlation between extract dose and inhibitory rate of platelet aggregation (R<0. 01). At 4 g/ L group, APTT, CT and FVII levels were re markably higher , but PT, FVIII, FIX and FXI levels were lower, than those at 0 g/L group (R <0. 01). APTT. CT and FVII levels showed positive correlation, but PT, FVIII, FIX and FXI levels showed negative correlation with ex tract dose (R<0.01). At 4g/L group, levels of blood viscosity (Is-1 and 200 s-1), plasma vis cosity and index of red cell aggregation were markedly higher than those at 0 g/L group (R< 0. 01 ). They all indicated positive correlation with extract dose (R<0. 01). CONCLUSION

  8. Platelet-Leukocyte Interaction and Thrombosis

    Institute of Scientific and Technical Information of China (English)

    贺石林; 范金茹

    2007-01-01

    @@ Cerebrocardiac thrombotic disease such as acute myocardial infarction and acute ischemic stroke cause signifieant morbidity and mortality.Present therapies for these diseases besides anticoagulation and fibrinolysis mainly aim toward limiting platelet adhesion and aggregation processes.However,their incomplete effectiveness suggests that other mechanisms may be important.

  9. External quality assessment of platelet disorder investigations: results of international surveys on diagnostic tests for dense granule deficiency and platelet aggregometry interpretation.

    Science.gov (United States)

    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.

  10. L-amino acid oxidase from Naja atra venom activates and binds to human platelets

    Institute of Scientific and Technical Information of China (English)

    Rui Li; Shaowen Zhu; Jianbo Wu; Wanyu Wang; Qiumin Lu; Kenneth J.Clemetson

    2008-01-01

    An L-amino acid oxidase (LAAO),NA-LAAO,was purified from the venom of Naja atra.Its N-terminal sequence shows great similarity with LAAOs from other snake venoms.NALAAO dose-dependently induced aggregation of washed human platelets.However,it had no activity on platelets in platelet-rich plasma.A low concentration of NA-LAAO greatly promoted the effect of hydrogen peroxide,whereas hydrogen peroxide itself had little activation effect on platelets.NA-LAAO induced tyrosine phosphorylation of a number of platelet proteins including Src kinase,spleen tyrosine kinase,and phospholipase C γ2.Unlike convulxin,Fc receptor γ chain and T lymphocyte adapter protein are not phosphorylated in NA-LAAO activated platelets,suggesting an activation mechanism different from the glycoprotein VI pathway.Catalase inhibited the platelet aggregation and platelet protein phosphorylation induced by NA-LAAO.NA-LAAO bound to fixed platelets as well as to platelet lysates of Western blots.Furthermore,affinity chromatography of platelet proteins on an NA-LAAO Sepharose 4B column isolated a few platelet membrane proteins,suggesting that binding of NA-LAAO to the platelet membrane might play a role in its action on platelets.

  11. Inappropriate platelet transfusion in a patient with ethylenediamine tetra- acetic acid (EDTA)--induced pseudothrombocytopenia.

    Science.gov (United States)

    Kakkar, Naveen; Garg, Geetu

    2006-01-01

    Automated platelet counts in the laboratory may be fictitiously low at times and require manual confirmation. Ethylenediaminetetra-acetic acid (EDTA) in few patients and healthy individuals can induce platelet aggregation, giving rise to a spuriously low automated platelet count. This phenomenon which occurs due to the presence of IgG antibodies, if unrecognized, can result in incorrect diagnosis and consequent inappropriate treatment. We present a patient who received inappropriate platelet transfusion as a result of EDTA induced spurious thrombocytopenia.

  12. Monocyte-Platelet Interaction Induces a Pro-Inflammatory Phenotype in Circulating Monocytes

    OpenAIRE

    2011-01-01

    BACKGROUND: Activated platelets exert a pro-inflammatory action that can be largely ascribed to their ability to interact with leukocytes and modulate their activity. We hypothesized that platelet activation and consequent formation of monocyte-platelet aggregates (MPA) induces a pro-inflammatory phenotype in circulating monocytes. METHODOLOGY/PRINCIPAL FINDINGS: CD62P(+) platelets and MPA were measured, and monocytes characterized, by whole blood flow cytometry in healthy subjects, before an...

  13. Cigarette smoking inhibits the anti-platelet activity of aspirin in patients with coronary heart disease

    Institute of Scientific and Technical Information of China (English)

    LI Wei-ju; ZHANG Hong-yin; MIAO Cheng-long; TANG Ri-bo; DU Xin; SHI Ji-hui; MA Chang-sheng

    2011-01-01

    Objective Tobacco smoking results in increased platelet aggregability, which suggests that low-dose aspirin used in common clinical practice may not effectively inhibit platelet activity in smokers with coronary heart disease (CHD). This review was performed to assess the effect of aspirin on platelet aggregation in patients with CHD.Data sources We performed an electronic literature search of MEDLINE (starting from the beginning to March 15, 2009)using the term "smoking" or "tobacco" paired with the following: "platelet", "aspirin" or "coronary heart disease".Study selection We looked for review articles regarding the effect of tobacco smoking on platelet activity and on the anti-platelet efficacy of aspirin in healthy people and patients with CHD. The search was limited in "core clinical journal".In total, 1321 relevant articles were retrieved, and 36 articles were ultimately cited.Results Tobacco smoking results in increased platelet aggregability, which can be inhibited by low-dose aspirin in the healthy population. However, in patients with CHD, the increased platelet aggregability can not be effectively inhibited by the same low-dose of aspirin. A recent study indicated that clopidogrel or an increased dose of aspirin can effectively inhibit the increased platelet aggregability induced by tobacco smoking in patients with CHD.Conclusions It is important for patients with CHD to quit smoking. For the current smoker, it may be necessary to take larger doses of aspirin than normal or take an adenosine diphosphate receptor inhibitor along with aspirin to effectively inhibit the increased platelet activity.

  14. Effects of drugs on platelet function.

    Science.gov (United States)

    Morse, E E

    1977-01-01

    Numerous drugs and chemicals affect the function of human blood platelets. The mechanism of action of some medications is partly understood. Aspirin is the most frequently involved drug. It appears to interfere with the platelet release reaction by acetylation of a platelet membrane protein which may be involved in the synthesis of prostaglandins. Other anti-inflammatory drugs, including indomethacin, phenylbutazone, ibuprophen (Motrin) and clonixin, also interfere with the release reaction but have a shorter acting course than aspirin. Some drugs stimulate adenylcyclase (gliclazide) or block phosphodiesterase, (dipyridamole, caffeine) both of which actions lead to an increase in adenosine cyclic 3':5' monophosphate (cAMP) and decrease aggregation by adenosine diphosphate (ADP). These interactions should be known to clinical scientists since patients using these medicaments may manifest abnormal platelet function tests in the laboratory and mild hemorrhagic syndromes in the clinic.

  15. In vitro effect of the herbicide glyphosate on human blood platelet aggregation and coagulation Efeito in vitro do herbicida glifosato na agregação plaquetária e coagulação sanguínea em humanos

    Directory of Open Access Journals (Sweden)

    Teresinha de Jesus C. Neiva

    2010-01-01

    Full Text Available Glyphosate [N-(phosphonomethyl-glycine] is a broad-spectrum, non-selective, post-emergence herbicide that is extensively used in agriculture. Published data referring to the effects of this product on human health are contradictory. We showed previously that long-term treatment of rats with low doses of Glyphosate-Biocarb® may induce hepatic histological changes and bleeding without decreasing platelet counts. The aim of the current study was to investigate, in vitro, the effect of glyphosate on human blood platelet aggregation and coagulation. Materials and methods: Platelet aggregation was determined in the platelet-rich plasma using the agents: 6µM-adenosine diphosphate, 6µM-epinephrine and 4µg/mL-collagen. Pretreatment with 500µg/mL glyphosate showed significant hypofunction of the three aggregating agents. The inhibitory effect was dose-dependent at concentrations from 50 to 500 µg/mL. The release of ATP was lower for glyphosate-treated platelets after stimulation by collagen. On the other hand, glyphosate did not promote any inhibitory effects on prothrombin time, thromboplastin time and thrombin time. In conclusion, the results demonstrate that glyphosate promotes changes in the platelet metabolism with an inhibitory effect on primary hemostasis.O glifosato [N-(phosphonomethyl-glycine] é um herbicida pós-emergente não seletivo de amplo espectro muito utilizado na agricultura. Dados da literatura referentes aos efeitos desse produto na saúde humana são contraditórios. Em estudos prévios demonstramos que ratos previamente tratados com glifosato apresentavam lesões hepáticas e sangramento sem alterações quantitativas de plaquetas. O objetivo do presente estudo é investigar os efeitos in vitro do glifosato (GP na agregação plaquetária e coagulação sanguínea em humanos. A agregação plaquetária foi determinada em plasma rico em plaquetas (PRP usando os agentes adenosina difosfato (ADP 6µM, epinefrina 6µM e col

  16. Modified expression of surface glyconjugates in stored human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Dhar, A.; Ganguly, P.

    1987-05-01

    Platelets are anucleated cells which play an important part in blood coagulation and thrombosis. These cells may be stored in the blood bank for only 4/5 days. In order to improve the storage of platelets, it is essential to first understand the changes in these cells due to storage. In this work, human platelets were stored in autologous plasma at 4/sup 0/ or 22/sup 0/ and their surface changes were monitored with three lectins - wheat germ afflutinin (WGA), concanavalin A (Con A) and lentil lectin (LL). Blood was drawn from healthy donors and platelet rich plasma (PRP) was collected by slow speed centrifugation. Platelets stored at either temperature for different times showed increased sensitivity to agglutination by WGA after 34-48 hrs. Lectins, Con A and LL, which were not agglutinating to fresh platelets readily caused agglutination after 48-72 hrs. The platelets stored for 25 hrs or longer period were insensitive to thrombin but showed enhanced aggregation with WGA. Labelling of surface glycoconjugates of stored platelets with /sup 3/H-boro-hydride revealed progressive loss of a glycoprotein of Mr 150,000 (GPIb infinity) together with the appearance of components of Mr 69,000; Mr 60,000; Mr 25,000. New high molecular weight glycoproteins were also detected only in stored platelets. The author studies clearly indicate that modification or altered expression of platelets surface glycoproteins may be one factor of storage related dysfunction of platelets.

  17. Anti-platelet effects of yuzu extract and its component.

    Science.gov (United States)

    Yu, Hye Yon; Park, Se Won; Chung, Ill Min; Jung, Yi-Sook

    2011-12-01

    In this study, we investigated whether the methanolic extract of yuzu (yuzu ME) and its components hesperidin and naringin, have anti-platelet activities. Yuzu ME and hesperidin inhibited collagen-, arachidonic acid (AA)-, ADP- and thrombin-induced rat platelet aggregation in vitro and ex vivo. Naringin also inhibited platelet aggregation induced by collagen, AA, or thrombin, but not aggregation induced by ADP. The oral administration of yuzu ME or hesperidin prolonged mouse tail vein bleeding time in a dose-dependent manner in vivo. These results suggest that yuzu ME and hesperidin have anti-platelet activity, and that intake of yuzu, which includes various flavonoids such as hesperidin, may be beneficial for individuals at high risk of cardiovascular diseases.

  18. Estudo comparativo entre agregação plaquetária por turbidimetria e impedância elétrica em pacientes sob terapia antiplaquetária à base de ácido acetilsalicílico Comparative study of platelet aggregation by turbidimetric and impedance methods in patients under acetylsalicylic acid antiplatelet therapy

    Directory of Open Access Journals (Sweden)

    Leonardo Lorenzo da Silva

    2010-01-01

    Full Text Available INTRODUÇÃO: A hiperagregação (agregação excessiva das plaquetas pode causar a formação de um trombo e a posterior oclusão dos vasos sanguíneos levando à isquemia. Esse fenômeno é responsável por doenças isquêmicas cardiovasculares, como angina pectoris e aterosclerose, bem como outras formas de isquemia, como o acidente vascular cerebral. Visando diminuir a função das plaquetas para reduzir a formação de trombos, o ácido acetilsalicílico vem sendo utilizado para tratamento antitrombótico, com diversos estudos mostrando sua eficácia. Dessa forma faz-se mister o uso de uma ferramenta laboratorial para o monitoramento da efetividade do tratamento, o que é feito por meio do teste de agregação plaquetária. O objetivo desse estudo foi comparar duas metodologias para esse exame (impedância elétrica e turbidimetria em relação a trinta pacientes adultos de ambos os sexos em uso do fármaco. CONCLUSÃO: Os resultados mostraram uma boa correlação entre os métodos, possibilitando o uso concomitante de ambas as técnicas em laboratórios clínicos de rotina.INTRODUCTION: Hyperaggregation of platelets can cause the formation of thrombi and subsequent occlusion of blood vessels leading to ischemia. This phenomenon can be responsible for ischemic cardiovascular diseases such as angina pectoris and atherosclerosis as well as other forms of ischemia such as stroke. To decrease platelet function and reduce the formation of thrombi, acetylsalicylic acid has been used for antithrombotic treatment, with several studies showing its effectiveness. Therefore it is necessary to use a laboratory tool to monitor the effectiveness of treatment, which is achieved through laboratory testing of platelet aggregation. The aim of this study was to compare two different methods (impedance and turbidimetry to test platelet aggregation in 30 adult patients of both genders taking acetylsalicylic acid. CONCLUSION: The results show that there is a

  19. Platelet matching for alloimmunized patients

    Institute of Scientific and Technical Information of China (English)

    S H.Hsu

    2010-01-01

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

  20. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets.

    Science.gov (United States)

    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.

  1. In-vitro model for the ultrastructural study of the formation of thrombi in human platelets.

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Taisuke Watanabe

    2017-01-01

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

  3. Nonmuscle Myosin IIA Regulates Platelet Contractile Forces Through Rho Kinase and Myosin Light-Chain Kinase.

    Science.gov (United States)

    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.

  4. Effects of pathogen reduction systems on platelet microRNAs, mRNAs, activation, and function.

    Science.gov (United States)

    Osman, Abdimajid; Hitzler, Walter E; Meyer, Claudius U; Landry, Patricia; Corduan, Aurélie; Laffont, Benoit; Boilard, Eric; Hellstern, Peter; Vamvakas, Eleftherios C; Provost, Patrick

    2015-01-01

    Pathogen reduction (PR) systems for platelets, based on chemically induced cross-linking and inactivation of nucleic acids, potentially prevent transfusion transmission of infectious agents, but can increase clinically significant bleeding in some clinical studies. Here, we documented the effects of PR systems on microRNA and mRNA levels of platelets stored in the blood bank, and assessed their impact on platelet activation and function. Unlike platelets subjected to gamma irradiation or stored in additive solution, platelets treated with Intercept (amotosalen+ ultraviolet-A [UVA] light) exhibited significantly reduced levels of 6 of the 11 microRNAs, and 2 of the 3 anti-apoptotic mRNAs (Bcl-xl and Clusterin) that we monitored, compared with platelets stored in plasma. Mirasol (riboflavin+ UVB light) treatment of platelets did not produce these effects. PR neither affected platelet microRNA synthesis or function nor induced cross-linking of microRNA-sized endogenous platelet RNA species. However, the reduction in the platelet microRNA levels induced by Intercept correlated with the platelet activation (p platelet aggregation response to ADP (p platelet activation, resulting in the release of microRNAs and mRNAs from platelets. The clinical implications of this reduction in platelet nucleic acids secondary to Intercept remain to be established.

  5. Role of platelets in the pathogenesis of antiphospholipid syndrome

    Directory of Open Access Journals (Sweden)

    NK Singh

    2013-07-01

    Full Text Available AimTo delineate the role of platelets in thrombotic process in APS patients.BackgroundPathogenesis of APS is an ongoing area of research and studying the role of platelets will be helpful in developing newer diagnostic and therapeutic strategies.Materials and methodsForty patients with APS, diagnosed as per modified 2006 Sapporo’s Criteria and who were not on aspirin or any other antiplatelet drug, were included. The same number of age- and sex-matched healthy controls was also recruited for comparison. The following platelet function studies were performed using the blood samples collected from APS patients as well as healthy controls: platelet aggregation studies, platelet secretion of dense granules (a. total degranulation b. platelet secretion of granules in relation to time c. visualization of platelet degranulation, clot retraction studies, and western blot studies on clot retracted samples for demonstration of activated proteomes.ResultsA significant increase (P < 0.001 in the platelet aggregation in APS patients as compared to healthy controls was noted. The subjects also showed a significant increase (P < 0.05 in the platelet granule release as well as more degranulation (P < 0.001 in relation to time at stored condition, which were well-visualized under phase-contrast microscope. Sixty-five percent of APS patients showed lesser as well as delayed clot retraction as compared to healthy controls, signifying that the platelet clots are less retractile in APS patients.ConclusionThe study clearly demonstrates the hyperactivity of platelets in APS patients in each step of their activation as compared to the controls. This indicates the major role played by platelets in APS pathogenesis.

  6. The functional role of platelets in the regulation of angiogenesis.

    Science.gov (United States)

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

    2015-01-01

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

  7. Selective inhibition of the platelet phosphoinositide 3-kinase p110beta as promising new strategy for platelet protection during extracorporeal circulation.

    Science.gov (United States)

    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.

  8. Platelet Dysfunction in Patients with Chronic Myeloid Leukemia: Does Imatinib Mesylate Improve It?

    Directory of Open Access Journals (Sweden)

    Olga Meltem Akay

    2016-05-01

    Full Text Available Objective: The aim of this study was to investigate the effects of imatinib mesylate on platelet aggregation and adenosine triphosphate (ATP release in chronic myeloid leukemia patients. Materials and Methods: Platelet aggregation and ATP release induced by 5.0 mM adenosine diphosphate, 0.5 mM arachidonic acid, 1.0 mg/ mL ristocetin, and 2 µg/mL collagen were studied by whole blood platelet lumi-aggregometer in 20 newly diagnosed chronic myeloid leukemia patients before and after imatinib mesylate treatment. Results: At the time of diagnosis, 17/20 patients had abnormal platelet aggregation results; 8 (40% had hypoactivity, 6 (30% had hyperactivity, and 3 (15% had mixed hypo- and hyperactivity. Repeat platelet aggregation studies were performed after a mean of 19 months (min: 5 months-max: 35 months in all patients who received imatinib mesylate during this period. After therapy, 18/20 (90% patients had abnormal laboratory results; 12 (60% had hypoactive platelets, 4 (20% had mixed hypo- and hyperactive platelets, and 2 (10% had hyperactive platelets. Three of the 8 patients with initial hypoactivity remained hypoactive, while 2 developed a mixed picture, 2 became hyperactive, and 1 normalized. Of the 6 patients with initial hyperactivity, 4 became hypoactive and 2 developed a mixed pattern. All of the 3 patients with initial hypo- and hyperactivity became hypoactive. Finally, 2 of the 3 patients with initial normal platelets became hypoactive while 1 remained normal. There was a significant decrease in ristocetin-induced platelet aggregation after therapy (p0.05. Conclusion: These findings indicate that a significant proportion of chronic myeloid leukemia patients have different patterns of platelet function abnormalities and imatinib mesylate has no effect on these abnormalities, with a significant impairment in ristocetin-induced platelet aggregation.

  9. Identification of the platelet ADP receptor targeted by antithrombotic drugs.

    Science.gov (United States)

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

    2001-01-11

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

  10. Effects of irradiation on platelet function

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Interaction of platelets with poly(vinylidene fluoride-co-hexafluoropropylene) electrospun surfaces.

    Science.gov (United States)

    Ahmed, Furqan; Choudhury, Namita Roy; Dutta, Naba K; Brito e Abreu, Susana; Zannettino, Andrew; Duncan, Elizabeth

    2014-03-10

    Platelets are the major contributors in the process of thrombosis and in the failure of biomedical implants. A number of factors influence the platelet interaction with foreign surfaces such as surface morphology, surface chemistry, and adsorbed proteins. This study examined the effect of surface topography and chemistry of pristine and fibrinogen-adsorbed solvent cast (SC) and electrospun (ES) samples of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) on platelet adhesion, activation, and aggregation. Qualitative and quantitative studies of fibrinogen adsorption were performed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), while SEM, aggregometry, and liquid scintillation analyses were performed to evaluate platelet adhesion, aggregation, and serotonin release. While little or no platelet adhesion was observed on pristine ES surfaces, considerable adhesion, and measurable aggregation and serotonin release were observed on pristine SC surfaces. Notably, increased adhesion of platelets was observed following fibrinogen adsorption on SC surface with considerable aggregation and serotonin release compared with ES samples, where limited aggregation and platelet adhesion was observed. A further comparison of platelet adhesion, aggregation, and serotonin release was performed with plasma-adsorbed SC and ES surfaces. SC surfaces showed enhanced platelet adhesion, aggregation, and serotonin release compared to ES surfaces. This study shows that the morphology of samples plays a critical role on the biocompatibility of samples by altering the adsorption and adhesion of biomolecules and cells. The low level of adhesion, low aggregation, and serotonin release of platelets, even in the presence of fibrinogen and plasma-derived proteins, suggested that ES samples have the least thrombogenicity.

  12. The influence of platelets, plasma and red blood cells on functional haemostatic assays.

    Science.gov (United States)

    Bochsen, Louise; Johansson, Pär I; Kristensen, Annemarie T; Daugaard, Gedske; Ostrowski, Sisse R

    2011-04-01

    Functional whole blood haemostatic assays are used increasingly to guide transfusion therapy and monitor medical treatment and are also applied for in-vitro evaluations of the haemostatic potential of stored platelets. We investigated how the cellular and plasmatic elements, both isolated and combined, influenced the two methodologically different assays, thrombelastography (TEG) and impedance aggregometry (Multiplate). Platelet-rich plasma (200 × 10/l) or pure plasma (0 platelets), with and without added red blood cells (RBCs), hematocrit 0, 0.15 or 0.29, were produced in vitro from platelet concentrates, fresh frozen plasma and stored RBC. Pure platelets were investigated by removing plasma components from platelet concentrates by diafiltration against the platelet storage solution Intersol. Plasma was readded by diafiltration against plasma in Intersol. Haemostatic function was evaluated by TEG and Multiplate. In the TEG, increasing amounts of RBC reduced clot strength and clot kinetics (α-angle), most markedly in plasma/RBC without platelets. In contrast, RBC in a platelet concentrate matrix enhanced Multiplate aggregation in response to weak agonists (ADP and arachidonic acid). Furthermore, removing plasma from platelet concentrates eliminated the TEG response and diminished the Multiplate aggregation response, but readding plasma to the pure platelet concentrates restored the response. Each of the elements in whole blood, plasma, platelets and RBC, affected the Multiplate and TEG results differently. The results emphasize that the concentrations of all cellular and plasmatic components in whole blood should be taken into account when interpreting results obtained by TEG and multiplate.

  13. Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

    Science.gov (United States)

    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.

  14. A novel inflammatory role for platelets in sickle cell disease.

    Science.gov (United States)

    Davila, Jennifer; Manwani, Deepa; Vasovic, Ljiljana; Avanzi, Mauro; Uehlinger, Joan; Ireland, Karen; Mitchell, W Beau

    2015-01-01

    The severe pain, ischemia and organ damage that characterizes sickle cell disease (SCD) is caused by vaso-occlusion, which is the blockage of blood vessels by heterotypic aggregates of sickled erythrocytes and other cells. Vaso-occlusion is also a vasculopathy involving endothelial cell dysfunction, leukocyte activation, platelet activation and chronic inflammation resulting in the multiple adhesive interactions between cellular elements. Since platelets mediate inflammation as well as thrombosis via release of pro- and anti-inflammatory molecules, we hypothesized that platelets may play an active inflammatory role in SCD by secreting increased amounts of cytokines. Since platelets have been shown to contain mRNA and actively produce proteins, we also hypothesized that SCD platelets may contain increased cytokine mRNA. In this cross-sectional study, we sought to compare both the quantity of cytokines secreted and the cytokine mRNA content, between SCD and control platelets. We measured the secretion of Th1, Th2, and Th17-related cytokines from platelets in a cohort of SCD patients. We simultaneously measured platelet mRNA levels of those cytokines. Platelets from SCD patients secreted increased quantities of IL-1β, sCD40L, and IL-6 compared to controls. Secretion was increased in patients with alloantibodies. Additionally, mRNA of those cytokines was increased in SCD platelets. Platelets from sickle cell patients secrete increased amounts of inflammatory cytokines, and contain increased cytokine mRNA. These findings suggest a novel immunological role for platelets in SCD vasculopathy, in addition to their thrombotic role, and strengthen the rationale for the use of anti-platelet therapy in SCD.

  15. Platelet turnover in stable coronary artery disease - influence of thrombopoietin and low-grade inflammation.

    Directory of Open Access Journals (Sweden)

    Sanne Bøjet Larsen

    Full Text Available BACKGROUND: Newly formed platelets are associated with increased aggregation and adverse outcomes in patients with coronary artery disease (CAD. The mechanisms involved in the regulation of platelet turnover in patients with CAD are largely unknown. AIM: To investigate associations between platelet turnover parameters, thrombopoietin and markers of low-grade inflammation in patients with stable CAD. Furthermore, to explore the relationship between platelet turnover parameters and type 2 diabetes, prior myocardial infarction, smoking, age, gender and renal insufficiency. METHODS: We studied 581 stable CAD patients. Platelet turnover parameters (immature platelet fraction, immature platelet count, mean platelet volume, platelet distribution width and platelet large cell-ratio were determined using automated flow cytometry (Sysmex XE-2100. Furthermore, we measured thrombopoietin and evaluated low-grade inflammation by measurement of high-sensitive CRP and interleukin-6. RESULTS: We found strong associations between the immature platelet fraction, immature platelet count, mean platelet volume, platelet distribution width and platelet large cell ratio (r = 0.61-0.99, p<0.0001. Thrombopoietin levels were inversely related to all of the platelet turnover parameters (r = -0.17--0.25, p<0.0001. Moreover, thrombopoietin levels were significantly increased in patients with diabetes (p = 0.03 and in smokers (p = 0.003. Low-grade inflammation evaluated by high-sensitive CRP correlated significantly, yet weakly, with immature platelet count (r = 0.10, p = 0.03 and thrombopoietin (r = 0.16, p<0.001. Also interleukin-6 correlated with thrombopoietin (r = 0.10, p = 0.02. CONCLUSION: In stable CAD patients, thrombopoietin was inversely associated with platelet turnover parameters. Furthermore, thrombopoietin levels were increased in patients with diabetes and in smokers. However, low-grade inflammation did not seem to have a

  16. The influence of platelets, plasma and red blood cells on functional haemostatic assays

    DEFF Research Database (Denmark)

    Bochsen, Louise; Johansson, Pär I.; Kristensen, Annemarie Thuri

    2011-01-01

    and combined, influenced the two methodologically different assays, thrombelastography (TEG) and impedance aggregometry (Multiplate). Platelet-rich plasma (200 × 10/l) or pure plasma (0 platelets), with and without added red blood cells (RBCs), hematocrit 0, 0.15 or 0.29, were produced in vitro from platelet...... concentrates, fresh frozen plasma and stored RBC. Pure platelets were investigated by removing plasma components from platelet concentrates by diafiltration against the platelet storage solution Intersol. Plasma was readded by diafiltration against plasma in Intersol. Haemostatic function was evaluated by TEG...... and Multiplate. In the TEG, increasing amounts of RBC reduced clot strength and clot kinetics (α-angle), most markedly in plasma/RBC without platelets. In contrast, RBC in a platelet concentrate matrix enhanced Multiplate aggregation in response to weak agonists (ADP and arachidonic acid). Furthermore, removing...

  17. [Effects of two trypanosomicide drugs, gention violet and WR6026, on platelet concentrates preservation].

    Science.gov (United States)

    Soares, Sheila; Moraes-Souza, Hélio; Tostes, Maria Aparecida Vieira; Lourenço, Dayse Maria

    2004-01-01

    In order to verify the viability of platelet concentrate during its preservation period when added with two trypanosomicidal chemical substances, gentian violet and quinoline WR6026, we tested these concentrates and verified the following parameters: number of platelets, pH and platelet aggregation test with a pair of agonists. Significant alterations were observed in the platelet concentrate treated with gentian violet suggesting important damage to the platelet viability. With WR6026 similar values to the controls were observed, opening new perspectives for the utilization of this salt for the chemoprophylaxis of transfusional Chagas' disease in highly endemic regions.

  18. Effective estimation of correct platelet counts in pseudothrombocytopenia using an alternative anticoagulant based on magnesium salt.

    Science.gov (United States)

    Schuff-Werner, Peter; Steiner, Michael; Fenger, Sebastian; Gross, Hans-Jürgen; Bierlich, Alexa; Dreissiger, Katrin; Mannuß, Steffen; Siegert, Gabriele; Bachem, Maximilian; Kohlschein, Peter

    2013-09-01

    Pseudothrombocytopenia remains a challenge in the haematological laboratory. The pre-analytical problem that platelets tend to easily aggregate in vitro, giving rise to lower platelet counts, has been known since ethylenediamine-tetra acetic acid EDTA and automated platelet counting procedures were introduced in the haematological laboratory. Different approaches to avoid the time and temperature dependent in vitro aggregation of platelets in the presence of EDTA were tested, but none of them proved optimal for routine purposes. Patients with unexpectedly low platelet counts or flagged for suspected aggregates, were selected and smears were examined for platelet aggregates. In these cases patients were asked to consent to the drawing of an additional sample of blood anti-coagulated with a magnesium additive. Magnesium was used in the beginning of the last century as anticoagulant for microscopic platelet counts. Using this approach, we documented 44 patients with pseudothrombocytopenia. In all cases, platelet counts were markedly higher in samples anti-coagulated with the magnesium containing anticoagulant when compared to EDTA-anticoagulated blood samples. We conclude that in patients with known or suspected pseudothrombocytopenia the magnesium-anticoagulant blood samples may be recommended for platelet counting.

  19. Platelet Hyperactivity in TNFSF14/LIGHT Knockout Mouse Model of Impaired Healing.

    Science.gov (United States)

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

    2016-10-01

    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.

  20. Migration distance-based platelet function analysis in a microfluidic system.

    Science.gov (United States)

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

    2013-01-01

    Aggregation and adhesion of platelets to the vascular wall are shear-dependent processes that play critical roles in hemostasis and thrombosis at vascular injury sites. In this study, we designed a simple and rapid assay of platelet aggregation and adhesion in a microfluidic system. A shearing mechanism using a rotating stirrer provided adjustable shear rate and shearing time and induced platelet activation. When sheared blood was driven through the microchannel under vacuum pressure, shear-activated platelets adhered to a collagen-coated surface, causing blood flow to significantly slow and eventually stop. To measure platelet adhesion and aggregation, the migration distance (MD) of blood through the microchannel was monitored. As the microstirrer speed increased, MD initially decreased exponentially but then increased beyond a critical rpm. For platelet-excluded blood samples, there were no changes in MD with increasing stirrer speed. These findings imply that the stirrer provided sufficiently high shear to activate platelets and that blood MD is a potentially valuable index for measuring the shear-dependence of platelet activation. Our microfluidic system is quick and simple, while providing a precise assay to measure the effects of shear on platelet aggregation and adhesion.

  1. The influence of conjugates isolated from Matricaria chamomilla L. on platelets activity and cytotoxicity.

    Science.gov (United States)

    Bijak, Michał; Saluk, Joanna; Tsirigotis-Maniecka, Marta; Komorowska, Halina; Wachowicz, Barbara; Zaczyńska, Ewa; Czarny, Anna; Czechowski, Franciszek; Nowak, Paweł; Pawlaczyk, Izabela

    2013-10-01

    Cardiovascular diseases (CVD) remain the principal cause of death in both advanced and developing countries of the world. Blood platelets are involved in the pathogenesis of atherosclerosis and thrombosis. Platelet adhesion and aggregation are critical events that occur in unstable coronary syndromes. The current research is focused on the role of polysaccharide-polyphenolic conjugates isolated from chamomile (Matricaria chamomilla L.) at concentrations of 10, 25, 50 and 100 μg/mL on blood platelets (obtained from healthy donors and from patients received combined anti-platelet therapy complex with clopidogrel and acetylsalicylic acid) aggregation and experimentally induced cell toxicity. The treatment of PRP obtained from healthy donors with polyphenolic-polysaccharide conjugates from M. chamomilla (L.) (MC) resulted in a dose-dependent, decrease of platelet aggregation induced by multiple agonists (ADP, collagen and arachidonic acid). In this study we also observed that the MC reduced platelet aggregation in PRP obtained from patients with cardiovascular disorders. The result of testing the MC on human blood platelets, mouse fibroblast cultures L929 and human lung cells A549 did not show any cytotoxicity effects. Compounds obtained from M. chamomilla L. are potential composite to the development of a new anti-platelet agent, which could be an alternative to the currently used anti-platelet drugs.

  2. The nature of interactions between tissue-type plasminogen activator and platelets

    Energy Technology Data Exchange (ETDEWEB)

    Torr, S.R.; Winters, K.J.; Santoro, S.A.; Sobel, B.E. (Washington Univ., St. Louis, MO (USA))

    1990-07-15

    To elucidate interactions responsible for inhibition of aggregation of platelets in platelet-rich plasma (PRP) harvested from whole blood preincubated with t-PA, experiments were performed with PRP and washed platelets under diverse conditions of preincubation. Both ADP and collagen induced aggregation were inhibited in PRP unless aprotinin had been added to the preincubated whole blood concomitantly with t-PA. However, in washed platelets prepared after the same exposure aggregation was intact. When washed platelets were supplemented with fibrinogen degradation products (FDPs) in concentrations simulating those in whole blood preincubated with t-PA, aggregation induced with either ADP or collagen was inhibited. Thus, the inhibition in PRP depended on generation of FDPs by activated plasminogen. The functional integrity of surface glycoprotein (GP) IIb/IIIa receptors in washed platelets was documented by autoradiography after SDS-PAGE of surface labeled GPs and by fibrinogen binding despite preincubation of the whole blood or washed platelets themselves with t-PA and plasminogen as long as exogenous calcium (greater than or equal to 0.1 microM) was present. In contrast, when calcium was absent, the platelet GP IIb/IIIa receptor was rendered susceptible to degradation by plasmin, and aggregation was inhibited by preincubation at 37 degrees C even if aprotinin was present when aggregation was being assayed. These observations reconcile disparate results in the literature from studies in vivo and in vitro by demonstrating that inhibition of aggregation of platelets in PRP and in whole blood reflects indirect effects of plasminogen activation rather than direct effects of t-PA or plasmin on the platelets themselves.

  3. Evaluation of a BED-SIDE Platelet Function Assay : Performance and Clinical Utility.

    Directory of Open Access Journals (Sweden)

    Lau Wei

    2002-01-01

    Full Text Available Platelets have a pivotal role in the initial defense against insult to the vasculature and are also recognized of critical importance in the acute care settings of percutaneous coronary intervention and cardiopulmonary bypass. In these environments both platelet count and function may be markedly compromised. Unfortunately, current assays to evaluate the parameters of platelet count and function are of limited utility for bed-side testing. Moreover, it is suggested that there may be significant inter patient variation in response to antiplatelet therapy that may be exacerbated by other agents (e.g. heparin that are routinely administered during cardiac intervention. Here we describe a practical, rapid and user-friendly whole blood platelet function assay that has been developed for use in bed-side settings. Platelet agonists were formulated with an anticoagulant and lyophilized in blood collection tubes standardised to receive a l mL fresh whole blood sample. In the presence of an agonist, platelets are activated and interact (aggregate. Using traditional cell counting principles, non-aggregated platelets are counted whereas aggregated platelets are not. The percentage (% of functional platelets in reference to a baseline tube may then be determined. Results are available within four minutes. Platelet aggregation in whole blood demonstrated good correlation with turbidometric aggregometry for both ADP (r=0.91 and collagen (r=0.88. Moreover, in clinical settings where antiplatelet agents were administered, this rapid, bed-side, platelet function assay demonstrated utility in monitoring patient response to these therapies. This novel bed-side assay of platelet function is extremely suitable for the clinical environment with a rapid turn-around time. In addition, it provides a full haematology profile, including platelet count, and should permit enhancement of transfusion and interventional decisions.

  4. The detection of platelet isoantibodies by membrane immunofluorescence.

    Science.gov (United States)

    van der Schans, G S; Veenhoven, W A; Snijder, J A; Nieweg, H O

    1977-07-01

    A membrane ummunofluorescence test for the detection of platelet isoantibodies is described. Gel filtration of the incubation mixture was incorporated in the procedure and proved effective for the removal of serum proteins from the platelet suspension. With this technique isoantibodies were found in the serum of 13 out of a group of 16 patients who had received multiple transfusions. The results were checked by measuring the uptake of 125I-labeled anti-IgG fraction by gel-filtered platelets. Subsequently the membrane immunofluorescence method was also compared with established techniques described for the detection of isoantibodies such as the microtest for lymphocytotoxicity and a complement-fixation method and the procedures based on the release of labeled serotonin, the phagocytosis of chromium-tagged platelets, the increase of platelet factor 3 activity, and on platelet aggregation. We had the opportunity to investigate the serum of one patient for the presence of isoantibodies against platelets from HLA identical siblings both before and after the administration of their platelets. On the basis of this experience it is concluded that the membrane immunofluorescence test for platelet isoantibodies is a relatively simple method with a high degree of specificity and adequate sensitivity.

  5. Platelets protect lung from injury induced by systemic inflammatory response

    Science.gov (United States)

    Luo, Shuhua; Wang, Yabo; An, Qi; Chen, Hao; Zhao, Junfei; Zhang, Jie; Meng, Wentong; Du, Lei

    2017-01-01

    Systemic inflammatory responses can severely injure lungs, prompting efforts to explore how to attenuate such injury. Here we explored whether platelets can help attenuate lung injury in mice resulting from extracorporeal circulation (ECC)-induced systemic inflammatory responses. Mice were subjected to ECC for 30 min, then treated with phosphate-buffered saline, platelets, the GPIIb/IIIa inhibitor Tirofiban, or the combination of platelets and Tirofiban. Blood and lung tissues were harvested 60 min later, and lung injury and inflammatory status were assessed. As expected, ECC caused systemic inflammation and pulmonary dysfunction, and platelet transfusion resulted in significantly milder lung injury and higher lung function. It also led to greater numbers of circulating platelet-leukocyte aggregates and greater platelet accumulation in the lung. Platelet transfusion was associated with higher production of transforming growth factor-β and as well as lower levels of tumour necrosis factor-α and neutrophil elastase in plasma and lung. None of these platelet effects was observed in the presence of Tirofiban. Our results suggest that, at least under certain conditions, platelets can protect lung from injury induced by systemic inflammatory responses. PMID:28155889

  6. In vitro screening of Amazonian plants for hemolytic activity and inhibition of platelet aggregation in human blood Testes in vitro de plantas Amazônicas para atividade hemolítica e inibição da agregação plaquetária em sangue humano

    Directory of Open Access Journals (Sweden)

    Viviana Maria Araújo de Oliveira

    2009-01-01

    Full Text Available In the present study, different aerial parts from twelve Amazonian plant species found in the National Institute for Amazon Research's (INPA's Adolpho Ducke Forest Reserve (in Manaus, Amazonas, Brazil were collected. Separate portions of dried, ground plant materials were extracted with water (by infusion, methanol and chloroform (by continuous liquid-solid extraction and solvents were removed first by rotary evaporation, and finally by freeze-drying which yielded a total of seventy-one freeze-dried extracts for evaluation. These extracts were evaluated initially at concentrations of 500 and 100 µg/mL for in vitro hemolytic activity and in vitro inhibition of platelet aggregation in human blood, respectively. Sixteen extracts (23 % of all extracts tested, 42 % of all plant species, representing the following plants: Chaunochiton kappleri (Olacaceae, Diclinanona calycina (Annonaceae, Paypayrola grandiflora (Violaceae, Pleurisanthes parviflora (Icacinaceae, Sarcaulus brasiliensis (Sapotaceae, exhibited significant inhibitory activity towards human platelet aggregation. A group of extracts with antiplatelet aggregation activity having no in vitro hemolytic activity has therefore been identified. Three extracts (4 %, all derived from Elaeoluma nuda (Sapotaceae, exhibited hemolytic activity. None of the plant species in this study has known use in traditional medicine. So, these data serve as a baseline or minimum of antiplatelet and hemolytic activities (and potential usefulness of non-medicinal plants from the Amazon forest. Finally, in general, these are the first data on hemolytic and inhibitory activity on platelet aggregation for the genera which these plant species represent.No presente estudo, partes aéreas obtidas de doze (12 espécies vegetais da Amazônia encontradas na Reserva Florestal Adolpho Ducke (localizada na cidade de Manaus, Estado do Amazonas, Brasil do Instituto Nacional de Pesquisas da Amazônia foram coletadas, secadas e mo

  7. N6-烷基-2-烷氧基腺苷化合物的合成及抗血小板凝集活性%Synthesis of 2-Alkoxy-N6-alkyl Adenosine Compounds and Their Anti-platelet Aggregation Activity

    Institute of Scientific and Technical Information of China (English)

    吴兆军; 李顺来; 丁忠仁; 杜洪光

    2011-01-01

    Guanosine (1) as the starting material was protected by acetic anhydride to get 2',3',5'-tri-O-acetyl-guanosine (2), then chlorinated with phosphorus oxychloride to obtain 2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (3). Compound 3 was diazotized and hydrolyzed, subsequently reacted with several alkyl halides respectively to afford 2-alkoxy-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (4a~4c). 2-Alkoxy-N6-alkyl adenosine compounds 5a~5c were acquired by aminolysis and deprotection reaction of compounds 4a~4c. All compounds 5a~5c have not been reported so far. The structures of compounds 5a~5c were identified by 1H NMR, 13C NMR, IR and HRMS techniques. What is more, the anti-platelet aggregation rates for the final compounds were measured. At a concentration of 100 μmol/L, the test results of the biological activity of anti-platelet aggregation showed that N6-(4-methylbenzyl)-2-benzyloxy adenosine (5c3) and N6-(2-phenethyl)-2-benzyloxy adenosine (5c4) have a relatively low aggregation rate and have a certain anti-platelet aggregation activity.%以鸟瞟呤核苷(1)为原料,经羟基保护得到2’,3’,5’-三-O-乙酰基鸟嘌呤核苷(2),2与三氯氧磷反应得到2-氨基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(3),3经重氮化、水解和O-烷基化得到2-烷氧基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(4a~4c),4a~4c经胺解和水解脱保护反应得到12个未见报道的N6-烷基-2-烷氧基腺苷化合物5a~5c.化合物的结构经1HNMR,13C NMR,IR和HRMS等得到表征,同时对合成的N6-烷基-2-烷氧基腺苷化合物进行了抗血小板凝集活性测试.结果表明,在测试浓度为100 μmol/L时,N6-(4-甲基苄基)-2-苄氧基腺苷(5c3)和N6-(2-苯乙基)-2-苄氧基腺苷(5c4)具有相对较低的聚集率,具有一定的抗血小板凝集活性.

  8. Platelets as Central Mediators of Systemic Inflammatory Responses

    OpenAIRE

    Smith, Tammy L; Weyrich, Andrew S.

    2010-01-01

    Systemic inflammatory responses are associated with high morbidity and mortality and represent a diverse and clinically challenging group of diseases. Platelets are increasingly linked to inflammation, in addition to their well-known roles in hemostasis and thrombosis. There is agreement that traditional functions of platelets, including adherence, aggregation, and secretion of preformed mediators, contribute to systemic inflammatory responses. However, emerging evidence indicates that platel...

  9. Reactivity, swelling and aggregation of mixed-size silicate nanoplatelets

    Science.gov (United States)

    Segad, M.; Cabane, B.; Jönsson, Bo

    2015-10-01

    Montmorillonite is a key ingredient in a number of technical applications. However, little is known regarding the microstructure and the forces between silicate platelets. The size of montmorillonite platelets from different natural sources can vary significantly. This has an influence on their swelling behavior in water as well as in salt solutions, particularly when tactoid formation occurs, that is when divalent counterions are present in the system. A tactoid consists of a limited number of platelets aggregated in a parallel arrangement with a constant separation. The tactoid size increases with platelet size and with very small nanoplatelets, ~30 nm, no tactoids are observed irrespectively of the platelet origin and concentration of divalent ions. The formation and dissociation of tactoids seem to be reversible processes. A large proportion of small nanoplatelets in a mixed-size system affects the tactoid formation, reduces the aggregation number and increases the extra-lamellar swelling in the system.

  10. p38 mitogen-activated protein kinase activation during platelet storage: consequences for platelet recovery and hemostatic function in vivo.

    Science.gov (United States)

    Canault, Matthias; Duerschmied, Daniel; Brill, Alexander; Stefanini, Lucia; Schatzberg, Daphne; Cifuni, Stephen M; Bergmeier, Wolfgang; Wagner, Denisa D

    2010-03-01

    Platelets undergo several modifications during storage that reduce their posttransfusion survival and functionality. One important feature of these changes, which are known as platelet storage lesion, is the shedding of the surface glycoproteins GPIb-alpha and GPV. We recently demonstrated that tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) mediates mitochondrial injury-induced shedding of adhesion receptors and that TACE activity correlates with reduced posttransfusion survival of these cells. We now confirm that TACE mediates receptor shedding and clearance of platelets stored for 16 hours at 37 degrees C or 22 degrees C. We further demonstrate that both storage and mitochondrial injury lead to the phosphorylation of p38 mitogen-activated kinase (MAPK) in platelets and that TACE-mediated receptor shedding from mouse and human platelets requires p38 MAP kinase signaling. Protein kinase C, extracellular regulated-signal kinase MAPK, and caspases were not involved in TACE activation. Both inhibition of p38 MAPK and inactivation of TACE during platelet storage led to a markedly improved posttransfusion recovery and hemostatic function of platelets in mice. p38 MAPK inhibitors had only minor effects on the aggregation of fresh platelets under static or flow conditions in vitro. In summary, our data suggest that inhibition of p38 MAPK or TACE during storage may significantly improve the quality of stored platelets.

  11. Platelet-derived HMGB1 is a critical mediator of thrombosis.

    Science.gov (United States)

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

    2015-12-01

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

  12. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study: Variation in Platelet Response to Clopidogrel and Aspirin.

    Science.gov (United States)

    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 pharmacogenomics studies.

  13. Investigating GABA and its function in platelets as compared to neurons.

    Science.gov (United States)

    Kaneez, Fatima Shad; Saeed, Sheikh Arshad

    2009-08-01

    We have recently suggested that platelets could be used as a model for neuronal receptors. In this paper we have investigated gamma-aminobutyric acid (GABA) metabolism and GABA receptors in platelets and in cultured neurons to see whether platelets' GABA mimics neuronal GABA receptor activities. We used the ELISA technique for detecting the GABA concentration in platelet rich plasma and cultured neurons. The functional effects of GABA and its receptor ligands on platelets were determined using an aggregometer. We found that the GABA concentration is 30% lower in platelets than in neurons and in both preparations GABA was metabolized by GABA transaminase (GABA-T). GABA potentiated calcium dependent platelet aggregation with a higher value in washed platelets suspension (WPS) then in platelet rich plasma (PRP). This effect was inhibited by benzodiazepines, calcium channel blockers and the selective phosphoinositide 3-kinase antagonist Wortmannin. GABA neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions. We concluded that platelets could be further developed to be used as a peripheral model to study neuronal GABAergic function and its abnormality in diseases such as epilepsy and schizophrenia. Furthermore our results indicated that PI3-kinase is involved in calcium dependent GABA induced platelet aggregation as this synergistic effect is inhibited by Wortmannin in dose dependent manner.

  14. Glatiramer acetate (copaxone modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation.

    Directory of Open Access Journals (Sweden)

    Sarah C Starossom

    Full Text Available BACKGROUND: Glatiramer acetate (GA, Copaxone, Copolymer-1 is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE, an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets. CONCLUSIONS: GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.

  15. Studies on the Biological Effects of Ozone: 10. Release of Factors from Ozonated Human Platelets

    Directory of Open Access Journals (Sweden)

    G. Valacchi

    1999-01-01

    Full Text Available In a previous work we have shown that heparin, in the presence of ozone (O3, promotes a dose-dependent platelet aggregation, while after Ca2+ chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor (PDGF, transforming growth factor β1 (TGF-β1 and interleukin-8(IL-8 are released in a dose-dependent manner after ozonation of heparinised platelet-rich plasma samples. These findings may explain the enhanced healing of torpid ulcers in patients with chronic limbischemia treated with O3 autohaemoteraphy (O3-AHT.

  16. Studies on the biological effects of ozone: 10. Release of factors from ozonated human platelets.

    Science.gov (United States)

    Valacchi, G; Bocci, V

    1999-01-01

    In a previous work we have shown that heparin, in the presence of ozone (O3), promotes a dose-dependent platelet aggregation, while after Ca2+ chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor (PDGF), transforming growth factor beta1 (TGF-beta1) and interleukin-8 (IL-8) are released in a dose-dependent manner after ozonation of heparinised platelet-rich plasma samples. These findings may explain the enhanced healing of torpid ulcers in patients with chronic limb ischemia treated with O3 autohaemoteraphy (O3-AHT).

  17. Novel Bioactivity of Ellagic Acid in Inhibiting Human Platelet Activation

    Directory of Open Access Journals (Sweden)

    Yi Chang

    2013-01-01

    Full Text Available Pomegranates are widely consumed either as fresh fruit or in beverage form as juice and wine. Ellagic acid possesses potent antioxidative properties; it is known to be an effective phytotherapeutic agent with antimutagenic and anticarcinogenic qualities. Ellagic acid (20 to 80 μM exhibited a potent activity in inhibiting platelet aggregation stimulated by collagen; however, it did not inhibit platelet aggregation stimulated by thrombin, arachidonic acid, or U46619. Treatment with ellagic acid (50 and 80 μM significantly inhibited platelet activation stimulated by collagen; this alteration was accompanied by the inhibition of relative [Ca2+]i mobilization, and the phosphorylation of phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinases (MAPKs, and Akt, as well as hydroxyl radical (OH● formation. In addition, ellagic acid also inhibited p38 MAPK and Akt phosphorylation stimulated by hydrogen peroxide. By contrast, ellagic acid did not significantly affect PKC activation and platelet aggregation stimulated by PDBu. This study is the first to show that, in addition to being considered a possible agent for preventing tumor growth, ellagic acid possesses potent antiplatelet properties. It appears to initially inhibit the PLCγ2-PKC cascade and/or hydroxyl radical formation, followed by decreased phosphorylation of MAPKs and Akt, ultimately inhibiting platelet aggregation.

  18. Glycoprotein VI but not alpha2beta1 integrin is essential for platelet interaction with collagen

    DEFF Research Database (Denmark)

    Nieswandt, B; Brakebusch, C; Bergmeier, W

    2001-01-01

    Platelet adhesion on and activation by components of the extracellular matrix are crucial to arrest post-traumatic bleeding, but can also harm tissue by occluding diseased vessels. Integrin alpha2beta1 is thought to be essential for platelet adhesion to subendothelial collagens, facilitating...... subsequent interactions with the activating platelet collagen receptor, glycoprotein VI (GPVI). Here we show that Cre/loxP-mediated loss of beta1 integrin on platelets has no significant effect on the bleeding time in mice. Aggregation of beta1-null platelets to native fibrillar collagen is delayed......, but not reduced, whereas aggregation to enzymatically digested soluble collagen is abolished. Furthermore, beta1-null platelets adhere to fibrillar, but not soluble collagen under static as well as low (150 s(-1)) and high (1000 s(-1)) shear flow conditions, probably through binding of alphaIIbbeta3 to von...

  19. MECHANISM OF PRESERVING EFFECT OF APROTININ ON PLATELET FUNCTION DURING CARDIOPULMONARY BYPASS

    Institute of Scientific and Technical Information of China (English)

    黄惠民; 丁文祥; 苏肇伉; 张伟忠

    1992-01-01

    The deficiency of platelet function is the main defect of hemostatic mechanism during cardiopulmonary bypass (CPB), which attributed to the postoperative bleeding complication to a great extent. The proteinase inhibitor aprotinin was reported to have preserving effect on platelet adhesion during CPB. In this clinical reserch we found that CPB caused plasma alpha 2-antiplasmin decreasing, indicating the fibrinolytic system activation. Meanwhile, the ristocetin-induced aggregation declined to 39.6% and platelet GPIb decreased to 50% of preoperative value. However, by treatment with aprotinin, the plasma alpha 2-antiplasmin during CPB did not change, platelet aggregation was improved and platelet GPIb was preserved, and consequently resulted in a 46% lower blood loss postoperatively. These results confirmed that aprotinin could inhibit the fibrinolysis during CPB, and thus relieve the platelet damage and improve the postoperative hemostatic mechanism.

  20. Calcium-binding proteins from human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Gogstad, G.O.; Krutnes, M.B.; Solum, N.O.

    1983-06-01

    Calcium-binding platelet proteins were examined by crossed immunoelectrophoresis of solubilized platelets against antibodies to whole platelets followed by incubation of the immunoplates with /sup 45/Ca/sup 2 +/ and autoradiography. When the immunoplates had been pretreated with EDTA at pH 9.0 in order to remove divalent cations, three immunoprecipitates were markedly labelled with /sup 45/Ca/sup 2 +/. These corresponded to the glycoprotein IIb-IIIa complex, glycoprotein Ia and a presently unidentified antigen termed G18. These antigens were membrane-bound and surface-oriented. When an excess of EDTA was introduced in the incubation media the results revealed that the glycoprotein IIb-IIIa complex and antigen G18, but not glycoprotein Ia, contained sites with a stronger affinity for calcium than has EDTA at pH 7.4. Immunoprecipitates of the separate glycoproteins IIb and IIIa both bound calcium in the same manner as the glycoprotein IIb-IIIa complex. As another approach, platelet-rich plasma was incubated with /sup 45/Ca/sup 2 +/ prior to crossed immunoelectrophoresis of the solubilized platelets. A single immunoprecipitate was weakly labelled. This did not correspond to any of the immunoprecipitates which were visible after staining with Coomassie blue. The labelling of this antigen was markedly increased when the platelet-rich plasma had been preincubated with EDTA and in this case a weak labelling of the glycoprotein IIB-IIIa precipitate also became apparent. No increased incorporation of calcium occured in any of these immunoprecipitates when the platelets were aggregated with ADP in the presence of /sup 45/Ca/sup 2 +/.

  1. Inhibitory effects of total saponin from Korean Red Ginseng on [Ca2+]i mobilization through phosphorylation of cyclic adenosine monophosphate-dependent protein kinase catalytic subunit and inositol 1,4,5-trisphosphate receptor type I in human platelets

    Directory of Open Access Journals (Sweden)

    Jung-Hae Shin

    2015-10-01

    Conclusion: These results strongly indicate that KRG-TS is a potent beneficial compound that inhibits [Ca2+]i mobilization in thrombin–platelet interactions, which may result in the prevention of platelet aggregation-mediated thrombotic disease.

  2. L-carnitine effectively improves the metabolism and quality of platelet concentrates during storage.

    Science.gov (United States)

    Deyhim, Mohammad Reza; Mesbah-Namin, Seyed Alireza; Yari, Fatemeh; Taghikhani, Mohammad; Amirizadeh, Naser

    2015-04-01

    Human platelets undergo structural and biochemical alternations during storage which are collectively called platelet storage lesion (PSL). PSL is characterized as metabolic and functionally changes. It causes decrease in platelet recovery and survival. Here, we evaluated the effect of L-carnitine (LC) on the metabolism, function, and mitochondrial metabolic activity of platelet during storage. Platelet-rich plasma was used to prepare platelet concentrate (PC) in Iranian Blood Transfusion Organization. For this purpose, ten PC bags from healthy donors were stored at 22 °C with gentle agitation in the presence or absence of LC. The effects of LC (15 mM) on the platelet quality were assessed by analyzing the levels of glucose, lactate, ATP, and lactate dehydrogenase (LDH) activity. Platelet aggregations induced by arachidonate and ristocetin were analyzed by aggregometer. Platelet mitochondrial melablolic activity was measured by tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) assay; platelet count and mean platelet volume were also determined by a hematology analyzer during 5 days of PC storage. The results indicated that LC could significantly decrease lactate concentration and glucose consumption accompanied with the increased oxygen consumption in stored PC. LDH activity also less significantly increased in LC-treated PC on days 2 and 5 of storage. Platelet aggregation in response to the ristocetin and arachidonate was significantly higher in LC-treated PC than that in untreated PC on day 5 of storage. Finally, platelet mitochondrial metabolic activity less significantly decreased in LC-treated PC compared to the control group on days 2 and 5 of storage. It seems that LC would be a good additive to reduce PSL and improve the platelet metabolism and quality of the stored PC for platelet transfusion therapy.

  3. Cyclic nucleotides and mitogen-activated protein kinases: regulation of simvastatin in platelet activation

    Directory of Open Access Journals (Sweden)

    Hou Ssu-Yu

    2010-06-01

    Full Text Available Abstract Background 3-Hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA reductase inhibitors (statins have been widely used to reduce cardiovascular risk. These statins (i.e., simvastatin may exert other effects besides from their cholesterol-lowering actions, including inhibition of platelet activation. Platelet activation is relevant to a variety of coronary heart diseases. Although the inhibitory effect of simvastatin in platelet activation has been studied; the detailed signal transductions by which simvastatin inhibit platelet activation has not yet been completely resolved. Methods The aim of this study was to systematically examine the detailed mechanisms of simvastatin in preventing platelet activation. Platelet aggregation, flow cytometric analysis, immunoblotting, and electron spin resonance studies were used to assess the antiplatelet activity of simvastatin. Results Simvastatin (20-50 μM exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists (i.e., thrombin. Simvastatin inhibited collagen-stimulated platelet activation accompanied by [Ca2+]i mobilization, thromboxane A2 (TxA2 formation, and phospholipase C (PLCγ2, protein kinase C (PKC, and mitogen-activated protein kinases (i.e., p38 MAPK, JNKs phosphorylation in washed platelets. Simvastatin obviously increased both cyclic AMP and cyclic GMP levels. Simvastatin markedly increased NO release, vasodilator-stimulated phosphoprotein (VASP phosphorylation, and endothelial nitric oxide synthase (eNOS expression. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the simvastatin-mediated inhibitory effects on platelet aggregation, PLCγ2 and p38 MAPK phosphorylation, and simvastatin-mediated stimulatory effects on VASP and eNOS phosphorylation. Conclusion The most important findings of this study demonstrate for the first time that inhibitory effect of simvastatin in platelet activation may involve activation of the cyclic AMP

  4. The effect of consuming meat enriched in walnut paste on platelet aggregation and thrombogenesis varies in volunteers with different apolipoprotein A4 genotype El efecto del consumo de carne enriquecida en pasta de nuez sobre la agregacion plaquetaria y la trombogenesis varia en voluntarios con diferente genotipo para la apolipoproteina A4

    Directory of Open Access Journals (Sweden)

    A. Canales

    2010-10-01

    Full Text Available Background and aim: Low-fat meat (LM has been considered adequate under a cardiovascular disease point of view. Meat enriched in walnut paste (WM consumption produces beneficial antithrombogenic effects but with striking inter-individual variability that may be related to gene polymorphism. Variants in the APOA4 gene (APOA4 polymorphism are known to affect the cardiovascular risk. This study aimed to compare the effects of consumption of WM and LM on platelet aggregation, production of thromboxane A2 (TXA2 and prostacyclin I2 (PGI2, and the TXA2/PGI2 ratio in 22 volunteers with different APOA4 polymorphism. Subjects and Methods: Six volunteers carried the Gln allele (APOA4-2 while 16 were homozygous for the His allele (APOA4-1. Platelet aggregation, TXA2 (measured as TXB2, PGI2 (measured as 6-keto-PGF1α, and the thrombogenic ratio (TXB2/6-keto-PGF1α were determined at baseline and at weeks 3 and 5 for the WM and LM dietary periods. Results: Platelet aggregation decreased significantly (PAntecedentes y objetivos: La carne con bajo contenido graso (LM se considera adecuada bajo el punto de vista cardiovascular. La ingesta de carne enriquecida en pasta de nuez (WM, mejora los efectos antitrombogénicos con una variabilidad inter-individual que puede estar relacionada con el polimorfismo genético. Variaciones en los genes APOA4 (APOA4 del polimorfismo afectan el riesgo cardiovascular. Este estudio compara los efectos de la ingesta de WM y LM sobre la agregación plaquetaria, la producción de tromboxano A2 (TXA2 y prostaciclina I2 (PGI2, y el cociente TXA2/PGI2 ratio en 22 voluntarios con diferentes polimorfismos APOA4. Material y métodos: Seis voluntarios portaban el alelo Gln (APOA4-2 frente a los 16 homozigotos para el alelo His (APOA4-1. La agregación plaquetaria, el TXA2 (medido como TXB2, la PGI2 (medida como 6-keto-PGF1α, y el cociente trombogenético (TXB2/6-keto-PGF1α se determinaron al comienzo y en las semanas 3 y 5 de los periodos

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  6. Extract of a spice--omum (Trachyspermum ammi)-shows antiaggregatory effects and alters arachidonic acid metabolism in human platelets.

    Science.gov (United States)

    Srivastava, K C

    1988-07-01

    An ethereal extract of omum (Trachyspermum ammi; Hindustani: ajwan)--a frequently consumed spice--was found to inhibit platelet aggregation induced by arachidonic acid (AA), epinephrine and collagen; in this respect it was most effective against AA-induced aggregation. Inhibition of aggregation by omum could be explained by its effect on platelet thromboxane production as suggested by the following experimental observation. (i) Omum reduced TxB2 formation in intact platelet preparations from added arachidonate, and (ii) it reduced the formation of TxB2 from AA-labelled platelets after stimulation with Ca2+-ionophore A23187 by a direct action on cyclooxygenase as it did not affect the release of AA from labelled platelets. An increased formation of lipoxygenase-derived products from exogenous AA in omum-treated platelets was apparently due to redirection of AA from cyclooxygenase to the lipoxygenase pathway.

  7. Helicobacter pylori urease activates blood platelets through a lipoxygenase-mediated pathway.

    Science.gov (United States)

    Wassermann, German E; Olivera-Severo, Deiber; Uberti, Augusto F; Carlini, Célia R

    2010-07-01

    The bacterium Helicobacter pylori causes peptic ulcers and gastric cancer in human beings by mechanisms yet not fully understood. H. pylori produces urease which neutralizes the acidic medium permitting its survival in the stomach. We have previously shown that ureases from jackbean, soybean or Bacillus pasteurii induce blood platelet aggregation independently of their enzyme activity by a pathway requiring platelet secretion, activation of calcium channels and lipoxygenase-derived eicosanoids. We investigated whether H. pylori urease displays platelet-activating properties and defined biochemical pathways involved in this phenomenon. For that the effects of purified recombinant H. pylori urease (HPU) added to rabbit platelets were assessed turbidimetrically. ATP secretion and production of lipoxygenase metabolites by activated platelets were measured. Fluorescein-labelled HPU bound to platelets but not to erythrocytes. HPU induced aggregation of rabbit platelets (ED(50) 0.28 microM) accompanied by ATP secretion. No correlation was found between platelet activation and ureolytic activity of HPU. Platelet aggregation was blocked by esculetin (12-lipoxygenase inhibitor) and enhanced approximately 3-fold by indomethacin (cyclooxygenase inhibitor). A metabolite of 12-lipoxygenase was produced by platelets exposed to HPU. Platelet responses to HPU did not involve platelet-activating factor, but required activation of verapamil-inhibitable calcium channels. Our data show that purified H. pylori urease activates blood platelets at submicromolar concentrations. This property seems to be common to ureases regardless of their source (plant or bacteria) or quaternary structure (single, di- or tri-chain proteins). These properties of HPU could play an important role in pathogenesis of gastrointestinal and associated cardiovascular diseases caused by H. pylori.

  8. Research on relationship of the occurrence of ischemic stroke with serum folic acid, platelet aggregation rate, homocysteine and vitamin B12%缺血性脑卒中的发生与血清叶酸、血小板聚集率、同型半胱氨酸和维生素B12的关系研究

    Institute of Scientific and Technical Information of China (English)

    王秀梅; 郝钦芳; 陈烨

    2011-01-01

    目的:探讨缺血性脑卒中患者血清叶酸( Folic Acid,FA)、血小板聚集率(Platelet Aggregation Rate,PAR)、同型半胱氨酸( Homocysteine,Hcy)和维生素B12(vitamin B12,VitB12)变化的原因及其关系.方法:选择缺血性脑卒中患者和健康对照组各60例,利用免疫法测其FA、PAR、Hcy和vitamin B12水平.结果:缺血性脑卒中患者体内FA水平偏低,PAR、VitB12和Hcy水平偏高,P<0.05;与缺血性脑卒中关系依次为FA>VitB12>PAR>Hcy,FA与PAR的相关关系r=0.006,P<0.01;HCY与PAR的相关关系r=0.03,P<0.05,FA与HCY的相关关系r=0.07.结论:缺血性脑卒中患者FA水平偏低,补充叶酸能降低PAR、改善HCY的氧化和VitB12的吸收,降低缺血性脑卒中的发生.%Objective: To explore the reason of changes and the interrelationships of serum Folic Acid (FA) , Homocysteine (Hcy) ,Platelet Aggregation Rate (PAR) and vitamin B12(VitB12) in ischaemic stroke patients. Methods: 60 ischemic stroke patients and 60 healthy controls were selected for concentration detection of FA, PAR, VitB12 and Hey by immune method. Results: FA level is low in ischemic stroke patients, while PAR, VitB12 and Hey level were high (P VitB12 > PAR > Hcy. The correlation between FA and PAR is r = 0.006, P < 0.01. The correlation between Hey and PAR is r = 0.03, P<0.05. The correlation between FA and Hey is r=0.07. Conclusion; FA level in ischemic stroke patients is low. Supplement of FA can reduce PAR, avoid Hcy oxidation, improve VitB12 absorption and reduce the occurrence of ischemic stroke.

  9. Extract of feverfew inhibits interactions of human platelets with collagen substrates

    Energy Technology Data Exchange (ETDEWEB)

    Loesche, W.M.; Mazurov, A.V.; Heptinstall, S.; Groenewegen, W.A.; Repin, V.S.; Till, U.

    1987-12-01

    The interaction of platelets with surfaces coated with collagens of type III (C III) or IV (C IV) has been studied by measuring the deposition of /sup 51/Cr-labeled platelets and by scanning electron microscopy (SEM). Experiments were performed using platelet-rich plasma (PRP) and suspensions of gel-filtered platelets (GFP). Platelets were deposited on C III mainly as surface-bound aggregates. In contrast they were deposited on C IV mainly as spread forms of individual cells. Formation of aggregates on C III was more extensive for PRP than for GFP; in contrast platelet spreading on C IV was more extensive for GFP than for PRP. The effects of an extract of the plant feverfew on platelet-collagen interactions were determined. Feverfew extract inhibited the deposition of /sup 51/Cr-labeled platelets on both C III and C IV in a dose-dependent way. Similar concentrations of extract were needed to inhibit the formation of surface-bound aggregates and to inhibit platelet spreading in both PRP and GFP.

  10. Effects of Antimalarial Tafenoquine on Blood Platelet Activity and Survival

    Directory of Open Access Journals (Sweden)

    Hang Cao

    2017-01-01

    Full Text Available Background/Aims: The 8-aminoquinoline tafenoquine has been shown to be effective against Plasmodia, Leishmania and Trypanosoma. The substance is at least in part effective by triggering apoptosis of the parasites. Moreover, tafenoquine has been shown to trigger eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. The effect of tafenoquine on eryptosis is in part due to stimulation of Ca2+ entry and oxidative stress. Ca2+ entry is a critical event in the activation of blood platelets by thrombin and collagen related peptide (CRP. The present study explored, whether tafenoquine influences Ca2+ entry, activation and apoptosis of blood platelets. Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to tafenoquine (2.5 µg/ml without or with an additional treatment with thrombin (0.01 U/ml or CRP (2 µg/ml or 5 µg/ml. Flow cytometry was employed to estimate cytosolic Ca2+-activity ([Ca2+]i from Fluo-3 fluorescence, platelet degranulation from P-selectin abundance, integrin activation from αIIbβ3 integrin abundance, phosphatidylserine abundance from annexin-V-binding, relative platelet volume from forward scatter, reactive oxygen species (ROS from DCF fluorescence, caspase 3 activity with an active caspase-3 Staining kit, and aggregation utilizing staining with CD9-APC and CD9-PE. Results: Both, thrombin (0.01 U/ml and CRP (2 µg/ml or 5 µg/ml, significantly increased [Ca2+]i, P-selectin abundance, active αIIbβ3 integrin, and annexin-V-binding, and both significantly decreased platelet volume, activated caspase 3 and stimulated aggregation. Administration of tafenoquine (2.5 µg/ml, 30 min significantly decreased [Ca2+]i both, in the absence and presence of thrombin and CRP. Tafenoquine significantly blunted the effect of thrombin and CRP on [Ca2+]i, P-selectin abundance, and active αIIbβ3 integrin, but

  11. Clopidogrel discontinuation and platelet reactivity following coronary stenting

    LENUS (Irish Health Repository)

    2011-01-01

    Summary. Aims: Antiplatelet therapy with aspirin and clopidogrel is recommended for 1 year after drug-eluting stent (DES) implantation or myocardial infarction. However, the discontinuation of antiplatelet therapy has become an important issue as recent studies have suggested a clustering of ischemic events within 90 days of clopidogrel withdrawal. The objective of this investigation was to explore the hypothesis that there is a transient ‘rebound’ increase in platelet reactivity within 3 months of clopidogrel discontinuation. Methods and Results: In this prospective study, platelet function was assessed in patients taking aspirin and clopidogrel for at least 1 year following DES implantation. Platelet aggregation was measured using a modification of light transmission aggregometry in response to multiple concentrations of adenosine diphosphate (ADP), epinephrine, arachidonic acid, thrombin receptor activating peptide and collagen. Clopidogrel was stopped and platelet function was reassessed 1 week, 1 month and 3 months later. Thirty-two patients on dual antiplatelet therapy were recruited. Discontinuation of clopidogrel increased platelet aggregation to all agonists, except arachidonic acid. Platelet aggregation in response to ADP (2.5, 5, 10, and 20 μm) and epinephrine (5 and 20 μm) was significantly increased at 1 month compared with 3 months following clopidogrel withdrawal. Thus, a transient period of increased platelet reactivity to both ADP and epinephrine was observed 1 month after clopidogrel discontinuation. Conclusions: This study demonstrates a transient increase in platelet reactivity 1 month after clopidogrel withdrawal. This phenomenon may, in part, explain the known clustering of thrombotic events observed after clopidogrel discontinuation. This observation requires confirmation in larger populations.

  12. In vitro short-term platelet adhesion on various metals.

    Science.gov (United States)

    Tanaka, Yuta; Kurashima, Kazuya; Saito, Haruka; Nagai, Akiko; Tsutsumi, Yusuke; Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao

    2009-01-01

    The in vitro short-term platelet adhesion on various metals, as accelerated by the addition of Ca(2+), was evaluated in this study. Metals used for medical devices [an austenitic stainless steel, a cobalt (Co)-chromium (Cr)-molybdenum (Mo) alloy, a titanium (Ti)-6 aluminum (Al)-4 vanadium (V) alloy, a Ti-6Al-7 niobium (Nb) alloy, a Tinickel (Ni) alloy, and commercially pure Ti] were immersed into a platelet-rich plasma solution for 5 or 20 min, and platelet adhesion and aggregation on the surfaces were observed using a scanning electron microscope. The platelet adhesion level on each metal after 5 min of immersion in a platelet-rich plasma solution was the smallest in this order: stainless steel alloy alloy alloy alloy = Ti. The levels after 5 min of immersion were almost the same as those after 20 min of immersion. Platelet adhesion was minimal on stainless steel and Co-Cr-Mo alloy, which have a Cr(2)O(3)-containing passive surface oxide film, but was accelerated on Ti and Ti alloys having a TiO(2)-containing film. A Cr(2)O(3)-containing oxide film has a lower relative permittivity than a TiO(2)-containing film; it thus supports a larger electrostatic force than the latter, adsorbs more albumins, which work as inhibitory proteins, and inhibits platelet aggregation. Therefore, platelet adhesion and aggregation are controlled by the composition of the surface oxide film on a metal due to the relative permittivity of the metal, which influences the amount of adsorbed proteins.

  13. Role of reactive nitrogen species in blood platelet functions.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara

    2007-12-01

    Blood platelets, in analogy to other circulating blood cells, can generate reactive oxygen/nitrogen species (ROS/RNS) that may behave as second messengers and may regulate platelet functions. Accumulating evidence suggest a role of ROS/RNS in platelet activation. On the other hand, an increased production of ROS/RNS causes oxidative stress, and thus, may contribute to the development of different diseases, including vascular complications, inflammatory and psychiatric illnesses. Oxidative stress in platelets leads to chemical changes in a wide range of their components, and platelet proteins may be initial targets of ROS/RNS action. It has been demonstrated that reaction of proteins with ROS/RNS results in the oxidation and nitration of some amino acid residues, formation of aggregates or fragmentation of proteins. In oxidized proteins new carbonyl groups and protein hydroperoxides are also formed. In platelets, low molecular weight thiols such as glutathione (GSH), cysteine and cysteinylglycine and protein thiols may be also target for ROS/RNS action. This review describes the chemical structure and biological activities of reactive nitrogen species, mainly nitric oxide ((*)NO) and peroxynitrite (ONOO(-)) and their effects on blood platelet functions, and the mechanisms involved in their action on platelets.

  14. Platelet membrane glycoproteins and their function: an overview.

    Science.gov (United States)

    Kunicki, T J

    1989-07-01

    The membrane glycoproteins (GP) of human platelets act as receptors that mediate two important functions, adhesion to the subendothelial matrix and platelet-platelet cohesion, or aggregation. Many of these glycoprotein receptors exist as noncovalently linked heterodimers, including those that belong to the supergene family of adhesion receptors called the integrins. Human platelets contain at least five members of this integrin family, including a collagen receptor (GP Ia-IIa; alpha 2, beta 1), a fibronectin receptor (GP Ic-IIa; alpha 5, beta 1), a laminin receptor (GP Ic'-IIa; alpha 6, beta 1), a vitronectin receptor (VnR; alpha v, beta 3), and a promiscuous, activation-dependent receptor that is thought to be the receptor most responsible for fibrinogen-dependent, platelet-platelet cohesion (GP IIb-IIIa; alpha IIb, beta 3). Some, but not all, of the integrins bind to a tripeptide sequence, arginine-glycine-aspartic acid (RGD), on the adhesive proteins. In addition to the integrins, platelets contain other membrane glyco-proteins: GP Ib-IX, a receptor for von Willebrand factor, which is thought to be the receptor most responsible for platelet adhesion to the subendothelial matrix in a flowing system; GP V, which may be associated with GP Ib-IX and whose function remains unknown; and GP IV (GP IIIb), which functions as a receptor for thrombospondin and collagen.

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

    Directory of Open Access Journals (Sweden)

    Särndahl Eva

    2010-06-01

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

  16. IL-17A facilitates platelet function through the ERK2 signaling pathway in patients with acute coronary syndrome.

    Directory of Open Access Journals (Sweden)

    Shuang Zhang

    Full Text Available BACKGROUND: Platelet aggregation mediated by inflammation played a critical role in the development of coronary heart diseases (CHD. Our previous clinical researches showed that Th17 cells and their characteristic cytokine IL-17A were associated with the plaque destabilization in patients with acute coronary syndrome (ACS. However, the potent effect of IL-17A on platelets-induced atherothrombosis remains unknown. METHODS AND RESULTS: In this study, we detected the plasma IL-17A levels and platelet aggregation in patients with stable angina (SA, unstable angina (UA, acute myocardial infarction (AMI and chest pain syndrome (CPS. In addition, the markers of platelet activation (CD62P/PAC-1 and the mitogen-activated protein kinases (MAPKs pathway were detected in platelets from ACS patients. We found that plasma IL-17A levels and platelet aggregation in patients with ACS (UA and AMI were significantly higher than patients with SA and CPS, and the plasma IL-17A levels were positively correlated with the platelet aggregation (R = 0.47, P<0.01. In addition, in patients with ACS, the platelet aggregation, CD62P/PAC-1 and the phosphorylation of ERK2 signaling pathway were obviously elevated in platelets pre-stimulated with IL-17A in vitro. Furthermore, the specific inhibitor of ERK2 could attenuate platelet aggregation and activation triggered by IL-17A. CONCLUSION: Our experiment firstly proved that IL-17A could promote platelet function in patients with ACS via activating platelets ERK2 signaling pathway and may provide a novel target for antiplatelet therapies in CHD.

  17. The critical roles of cyclic AMP/cyclic AMP-dependent protein kinase in platelet physiology

    Institute of Scientific and Technical Information of China (English)

    Rong YAN; Suping LI; Kesheng DAI

    2009-01-01

    Platelets are the primary players in both thrombosis and hemostasis.Cyclic AMP (cAMP) and cAMP-dependent protein kinase (PKA) are important signaling molecules in the regulation of platelet function,such as adhesion,aggregation,and secretion.Elevation of intracellular cAMP,which induces the activation of PKA,results in the inhibition of platelet function.Thus,tight control of the intracellular cAMP/PKA signaling pathway has great implications for platelet-dependent hemostasis and effective cardiovascular therapy.In this review,we summarize the PKA substrates and their contributions to platelet function,especially the advancing understanding of the cAMP/PKA-dependent signaling pathway in platelet physiology.In addition,we suggest the possibility that cAMP/PKA is involved in the platelet procoagulant process and receptor ectodomain shedding.

  18. Accurate platelet counting in an insidious case of pseudothrombocytopenia.

    Science.gov (United States)

    Lombarts, A J; Zijlstra, J J; Peters, R H; Thomasson, C G; Franck, P F

    1999-01-01

    Anticoagulant-induced aggregation of platelets leads to pseudothrombocytopenia. Blood cell counters generally trigger alarms to alert the user. We describe an insidious case of pseudothrombocytopenia, where the complete absence of Coulter counter alarms both in ethylenediaminetetraacetic acid blood and in citrate or acid citrate dextrose blood samples was compounded by the fact that the massive aggregates were exclusively found at the edges of the blood smear. Non-recognition of pseudothrombocytopenia can have serious diagnostic and therapeutic consequence