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Sample records for endothelium-dependent platelet inhibition

  1. Desflurane inhibits endothelium-dependent vasodilation more than sevoflurane with inhibition of endothelial nitric oxide synthase by different mechanisms.

    Science.gov (United States)

    Kazuma, Satoshi; Tokinaga, Yasuyuki; Takada, Yukimasa; Azumaguchi, Ryu; Kimizuka, Motonobu; Hayashi, Shunsuke; Yamakage, Michiaki

    2018-01-01

    The effects of desflurane on endothelium-dependent vasodilation remain uncertain, whereas sevoflurane is known to inhibit it. Endothelium-dependent vasodilation is mainly mediated by endothelial nitric oxide synthase. The effects of desflurane on endothelium-dependent vasodilation were compared with those of sevoflurane, and inhibition mechanisms, including phosphorylation of endothelial nitric oxide synthase and the calcium pathway, were evaluated for the two anesthetics. We hypothesized that desflurane would inhibit endothelium-dependent vasodilation in a concentration-dependent manner more than sevoflurane, with inhibition of a calcium pathway. Isolated rat aortic rings were randomly assigned to treatment with desflurane or sevoflurane for measurements of the vasodilation ratio. To determine NO production with desflurane and sevoflurane, an in vitro assay was performed with cultured bovine aortic endothelial cells. These cells were also used for measurement of intracellular calcium or Western blotting. For endothelium-dependent vasodilation, the ratio of vasodilation was more significantly inhibited by 11.4% desflurane than by 4.8% sevoflurane. Inhibition did not between 5.7% desflurane and 2.4% sevoflurane. No inhibitory effect of desflurane or sevoflurane was observed in endothelium-denuded aorta. Desflurane inhibited nitric oxide production caused by stimulation of bradykinin significantly more than sevoflurane. Desflurane had a greater suppressive effect on the bradykinin-induced increase in intracellular calcium concentration than did sevoflurane. Sevoflurane, but not desflurane, inhibited phosphorylation of the serine 1177 residue by bradykinin stimulation. Desflurane inhibited endothelium-dependent vasodilation more than sevoflurane through inhibition of a calcium pathway. Sevoflurane inhibited endothelium-dependent vasodilation by inhibition of phosphorylation of the serine 1177 residue of endothelial nitric oxide synthase. Copyright © 2017 Elsevier

  2. Hydrogen Sulfide and Endothelium-Dependent Vasorelaxation

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    Jerzy Bełtowski

    2014-12-01

    Full Text Available In addition to nitric oxide and carbon monoxide, hydrogen sulfide (H2S, synthesized enzymatically from l-cysteine or l-homocysteine, is the third gasotransmitter in mammals. Endogenous H2S is involved in the regulation of many physiological processes, including vascular tone. Although initially it was suggested that in the vascular wall H2S is synthesized only by smooth muscle cells and relaxes them by activating ATP-sensitive potassium channels, more recent studies indicate that H2S is synthesized in endothelial cells as well. Endothelial H2S production is stimulated by many factors, including acetylcholine, shear stress, adipose tissue hormone leptin, estrogens and plant flavonoids. In some vascular preparations H2S plays a role of endothelium-derived hyperpolarizing factor by activating small and intermediate-conductance calcium-activated potassium channels. Endothelial H2S signaling is up-regulated in some pathologies, such as obesity and cerebral ischemia-reperfusion. In addition, H2S activates endothelial NO synthase and inhibits cGMP degradation by phosphodiesterase 5 thus potentiating the effect of NO-cGMP pathway. Moreover, H2S-derived polysulfides directly activate protein kinase G. Finally, H2S interacts with NO to form nitroxyl (HNO—a potent vasorelaxant. H2S appears to play an important and multidimensional role in endothelium-dependent vasorelaxation.

  3. Abnormal endothelium-dependent microvascular reactivity in recently preeclamptic women

    NARCIS (Netherlands)

    Blaauw, J; Graaff, R; van Pampus, Maria; van Doormaal, JJ; Smit, AJ; Rakhorst, G; Aarnoudse, JG

    OBJECTIVE: To assess endothelial function at die level of skin microvasculature, using iontophoretic administration of acetylcholine (endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator), in women who recently had a preeclamptic pregnancy. METHODS:

  4. Endothelium-dependent relaxation in coronary arteries requires magnesium ions.

    Science.gov (United States)

    Altura, B. T.; Altura, B. M.

    1987-01-01

    A great deal of interest has recently focused upon the mechanism(s) associated with the generation and action of endothelium-derived relaxant factors (EDRFs) in blood vessels. Since we have shown that extracellular magnesium ions ([Mg2+]o) are important in control of coronary vascular tone and reactivity, we wondered whether these divalent cations play any role in the generation or action of EDRF in coronary arterial smooth muscle. Using isolated canine coronary arterial rings, we have now found that removal of [Mg2+]o inhibits the ability of these vascular preparations to relax when challenged with acetylcholine; in the absence of [Mg2+]o, the relaxation concentration-response curves for acetylcholine are shifted markedly to higher concentrations with small maxima. It, thus, appears that [Mg2+]o is an important co-factor for acetylcholine-induced endothelium-dependent relaxation in canine coronary arteries. These findings support our previous hypothesis that dietary deficiency of Mg may be an important factor in aetiology of coronary vasospasm. PMID:3496933

  5. Endothelium-independent and endothelium-dependent ...

    African Journals Online (AJOL)

    Taken together, these results indicate that ALF is a powerful vasodilator modulated by the formation of NO from endothelium, but also act by directly relaxing the vascular smooth muscle cells, by inhibiting cGMP hydrolyzing PDEs (PDE1, PDE2 and PDE5) and to a lesser extend on cAMP degradation (PDE3 and PDE4), ...

  6. Vildagliptin improves endothelium-dependent vasodilatation in type 2 diabetes

    NARCIS (Netherlands)

    Poppel, P.C. van; Netea, M.G.; Smits, P.; Tack, C.J.J.

    2011-01-01

    OBJECTIVE: To investigate whether the dipeptidyl peptidase-4 inhibitor vildagliptin improves endothelium-dependent vasodilatation in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Sixteen subjects with type 2 diabetes (age 59.8 +/- 6.8 years, BMI 29.1 +/- 4.8 kg/m(2), HbA(1c) 6.97 +/-

  7. Platelet dysfunction and inhibition of multiple electrode platelet aggregometry caused by penicillin

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    von Beckerath Nicolas

    2010-07-01

    Full Text Available Abstract Beta-lactam antibiotics, e.g. penicillin, may inhibit platelet function and lead to reduced response in light transmission aggregometry and adhesion. However, influence on platelet function tests more commonly used in clinical practice, such as multiple electrode platelet aggregometry (MEA, have not been described so far. We report a case of a patient with local streptococcus infection. Treatment with penicillin resulted in mild bleeding tendency after 3 days. While coagulation parameters were normal, assessment of platelet function by MEA revealed strong platelet inhibition of both ADP and arachidonic acid induced platelet aggregation comparable to normal responders to antiplatelet therapy. Change of antibiotic regime resulted in recovery of platelet function. Thus, penicillin therapy may impact on platelet function and consecutively commonly used platelet function assays, e.g. MEA.

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

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    Sirada Srihirun

    Full Text Available 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.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.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.

  9. Correction of glycosylated oxyhemoglobin-induced impairment of endothelium-dependent vasodilatation by gliclazide.

    Science.gov (United States)

    Vallejo, S; Angulo, J; Peiró, C; Sánchez-Ferrer, A; Cercas, E; Nevado, J; Sánchez-Ferrer, C F; Rodríguez-Mañas, L

    2000-01-01

    We have investigated whether gliclazide, a second-generation sulfonylurea hypoglycemic agent, interferes with the impairment of endothelium-dependent nitric-oxide-mediated relaxation produced by 14%-glycosylated human oxyhemoglobin (GHHb). For comparative purposes, other agents, like glibenclamide, aminoguanidine, ascorbic acid or superoxide dismutase (SOD), were also tested. GHHb (10 nM) caused a reduction in endothelium-dependent relaxation induced by acetylcholine (1 nM to 10 microM) in both isolated aortic segments and mesenteric microvessels from normoglycemic nondiabetic rats. Preincubation of the vessels with gliclazide (100 nM to 10 microM) prevented the impairment of endothelial relaxation, the threshold concentration of gliclazide being 300 nM. In addition, 10 microM gliclazide also prevented the reduction by 10 nM GHHb of the relaxation induced by exogenous nitric oxide (NO, 10 nM to 100 microM). Determination of superoxide anion release measured by the reduction in ferricytochrome c indicated that GHHb produced significant amounts of these free radicals that were concentration-dependently inhibited by gliclazide. The impairment of endothelium-mediated responses was also prevented by 100 U/ml SOD or 10 microM ascorbic acid, but not by 10 microM glibenclamide or 100 microM aminoguanidine. We conclude that gliclazide can reduce the impairment of nitric-oxide-mediated endothelium-dependent relaxation produced by GHHb. This reduction is likely related to the antioxidant properties of the drug, a mechanism suggested by these studies which demonstrate the inactivation of superoxide anions produced by the glycosylated protein by gliclazide.

  10. Tamoxifen Directly Inhibits Platelet Angiogenic Potential and Platelet-Mediated Metastasis.

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    Johnson, Kelly E; Forward, Jodi A; Tippy, Mason D; Ceglowski, Julia R; El-Husayni, Saleh; Kulenthirarajan, Rajesh; Machlus, Kellie R; Mayer, Erica L; Italiano, Joseph E; Battinelli, Elisabeth M

    2017-04-01

    Platelets, which are mainly known for their role in hemostasis, are now known to play a crucial role in metastasis. Tamoxifen is a selective estrogen receptor modulator that is widely used for the treatment of breast cancer. Tamoxifen and its metabolites have been shown to directly impact platelet function, suggesting that this drug has additional mechanisms of action. The purpose of this study was to determine whether tamoxifen exerts antitumor effects through direct platelet inhibition. This study found that pretreatment with tamoxifen leads to a significant inhibition of platelet activation. Platelets exposed to tamoxifen released significantly lower amounts of proangiogenic regulator vascular endothelial growth factor. In vitro angiogenesis assays confirmed that tamoxifen pretreatment led to diminished capillary tube formation and decreased endothelial migration. Tamoxifen and its metabolite, 4-hydroxytamoxifen, also significantly inhibited the ability of platelets to promote metastasis in vitro. Using a membrane-based array, we identified several proteins associated with angiogenesis metastasis that were lower in activated releasate from tamoxifen-treated platelets, including angiogenin, chemokine (C-X-C motif) ligand 1, chemokine (C-C motif) ligand 5, epidermal growth factor, chemokine (C-X-C motif) ligand 5, platelet-derived growth factor dimeric isoform BB, whereas antiangiogenic angiopoietin-1 was elevated. Platelets isolated from patients on tamoxifen maintenance therapy were also found to have decreased activation responses, diminished vascular endothelial growth factor release, and lower angiogenic and metastatic potential. We demonstrate that tamoxifen and its metabolite 4-hydroxytamoxifen directly alter platelet function leading to decreased angiogenic and metastatic potential. Furthermore, this study supports the idea of utilizing targeted platelet therapies to inhibit the platelet's role in angiogenesis and malignancy. © 2017 American Heart

  11. Morinda lucida extract induces endothelium-dependent and -independent relaxation of rat aorta.

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    Ettarh, R R; Emeka, P

    2004-06-01

    The effect of an aqueous extract of Morinda lucida (ML) on vascular tone was tested using rat aortic rings precontracted with noradrenaline (10(-7) mol/l). Relaxation responses were determined with endothelium-intact, L-NAME-treated, methylene blue-treated and endothelium-denuded tissues. In the concentration range of 0.25-9.0 mg/ml, ML elicited vasorelaxation in noradrenaline-precontracted rings. This relaxation response was partially attenuated by removal of the endothelium, and completely inhibited by pretreatment of rings with L-NAME and methylene blue. Thus, ML-induced relaxation of vascular smooth muscle occurs via endothelium-dependent and -independent mechanisms, the former of which involves the nitric oxide-cGMP pathway. Copyright 2004 Elsevier B.V.

  12. Flavonolignans inhibit the arachidonic acid pathway in blood platelets.

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    Bijak, Michal; Saluk-Bijak, Joanna

    2017-08-10

    Arachidonic acid metabolism by cyclooxygenase (COX) is a major pathway for blood platelets' activation, which is associated with pro-thrombotic platelet activity and the production of pro-inflammatory mediators. Inhibition of COX activity is one of the major means of anti-platelet pharmacotherapy preventing arterial thrombosis and reducing the incidence of cardiovascular events. Recent studies have presented that a silymarin (standardized extract of Milk thistle (Silybum marianum)) can inhibit the COX pathway. Accordingly, the aim of our study was to determine the effects of three major flavonolignans (silybin, silychristin and silydianin) on COX pathway activity in blood platelets. We determined the effect of flavonolignans on arachidonic acid induced blood platelet aggregation, COX pathway metabolites formation, as well as COX activity in platelets. Additionally, we analysed the potential mechanism of this interaction using the bioinformatic ligand docking method. We observed that tested compounds decrease the platelet aggregation level, both thromboxane A2 and malondialdehyde formation, as well as inhibit the COX activity. The strongest effect was observed for silychristin and silybin. In our in silico study we showed that silychristin and silybin have conformations which interact with the active COX site as competitive inhibitors, blocking the possibility of substrate binding. The results obtained from this study clearly present the potential of flavonolignans as novel antiplatelet and anti-inflammatory agents.

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

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

    2006-07-01

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

  14. Cytochalasins inhibit arachidonic acid metabolism in thrombin-stimulated platelets.

    OpenAIRE

    Siess, W; Lapetina, E G; Cuatrecasas, P

    1982-01-01

    Low concentrations (0.5-1 microM) of cytochalasins inhibit the thrombin-stimulated polymerization of monomeric actin to filamentous actin in platelets. Similar concentrations of cytochalasin B inhibit the formation and metabolism of arachidonic acid in horse platelets stimulated by low concentrations of thrombin (0.1-0.5 unit/ml). However, the release of serotonin is not inhibited by cytochalasin B. Cytochalasins B and D (0.5-1 microM) markedly reduce, in thrombin-stimulated human or horse pl...

  15. Tocotrienols-induced inhibition of platelet thrombus formation and platelet aggregation in stenosed canine coronary arteries

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    Papasian Christopher J

    2011-04-01

    Full Text Available Abstract Background Dietary supplementation with tocotrienols has been shown to decrease the risk of coronary artery disease. Tocotrienols are plant-derived forms of vitamin E, which have potent anti-inflammatory, antioxidant, anticancer, hypocholesterolemic, and neuroprotective properties. Our objective in this study was to determine the extent to which tocotrienols inhibit platelet aggregation and reduce coronary thrombosis, a major risk factor for stroke in humans. The present study was carried out to determine the comparative effects of α-tocopherol, α-tocotrienol, or tocotrienol rich fraction (TRF; a mixture of α- + γ- + δ-tocotrienols on in vivo platelet thrombosis and ex vivo platelet aggregation (PA after intravenous injection in anesthetized dogs, by using a mechanically stenosed circumflex coronary artery model (Folts' cyclic flow model. Results Collagen-induced platelet aggregation (PA in platelet rich plasma (PRP was decreased markedly after treatment with α-tocotrienol (59%; P P P P P Next, pharmacokinetic studies were carried out and tocol levels in canine plasma and platelets were measured. As expected, α-Tocopherol treatment increased levels of total tocopherols in post- vs pre-treatment specimens (57 vs 18 μg/mL in plasma, and 42 vs 10 μg/mL in platelets. However, treatment with α-tocopherol resulted in slightly decreased levels of tocotrienols in post- vs pre-treatment samples (1.4 vs 2.9 μg/mL in plasma and 2.3 vs 2.8 μg/mL in platelets. α-Tocotrienol treatment increased levels of both tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 45 vs 10 μg/mL in plasma and 28 vs 5 μg/mL in platelets; tocotrienols, 2.8 vs 0.9 μg/mL in plasma and 1.28 vs 1.02 μg/mL in platelets. Treatment with tocotrienols (TRF also increased levels of tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 68 vs 20 μg/mL in plasma and 31.4 vs 7.9 μg/mL in platelets; tocotrienols, 8.6 vs 1

  16. Effect of the Menstrual Cycle on Maximum Oxygen Consumption and Endothelium-Dependent Vasodilation

    National Research Council Canada - National Science Library

    Andrews, Thomas

    1997-01-01

    .... We studied endothelium-dependent vasodilation of the brachial artery during three phases of the menstrual cycle in 20 eumenorrheic subjects to determine the effect of endogenous estradiol and progesterone...

  17. Incomplete reversibility of platelet inhibition following prolonged exposure to ticagrelor.

    Science.gov (United States)

    Gerrits, A J; Jakubowski, J A; Sugidachi, A; Michelson, A D; Frelinger, A L

    2017-05-01

    Essentials Irreversible platelet inhibition persists after reversibly-binding ticagrelor is discontinued. Reversibility of platelet inhibition by ticagrelor and its active metabolite was assessed. Incomplete recovery was observed after prolonged exposure to ticagrelor. Activated GPIIb-IIIa and P-selectin, not platelet reactivity index, showed irreversibility. Introduction Ticagrelor is described as a reversible P2Y12 antagonist. However, residual platelet inhibition persists after discontinuation of ticagrelor when plasma levels are undetectable. We assessed the reversibility of platelet inhibition by ticagrelor and its active metabolite (T-AM) in comparison with cangrelor and prasugrel's active metabolite (P-AM). Methods Whole blood was treated in vitro with ~ 50% inhibitory concentrations of ticagrelor, T-AM, cangrelor, P-AM and assessed for ADP-stimulated activated GPIIb-IIIa and P-selectin and vasodilator-stimulated phosphoprotein (VASP) platelet reactivity index (PRI) before and after 100-fold dilution. Results Platelets exposed for 30 min to ticagrelor, T-AM or cangrelor showed full recovery of activated GPIIb-IIIa but only partial recovery of P-selectin. Longer exposure (24 h) to the drug decreased reversibility of activated GPIIb-IIIa by ticagrelor (65.1% [49.5-80.6], % of vehicle with 95% confidence interval [CI]) and T-AM (88.8% [79.2-98.3]), but not by cangrelor (101.4% [96.4-106.4]). Compared with 30 min exposure, the reversibility of P-selectin further decreased after 24 h exposure to ticagrelor (from 91.8% [82.1-101.5] to 51.8% [45.5-85.0]), but not T-AM (from 79.0% [67.8-90.3] to 77.4% [61.8-93.1]) or cangrelor (from 76.0% [67.6-84.4] to 76.2% [70.6-81.8]). In contrast, 24 h exposure to ticagrelor, T-AM and cangrelor resulted in full recovery of platelet reactivity as measured by PRI. Platelets exposed to P-AM showed no recovery of ADP reactivity. Conclusions Incomplete recovery after prolonged exposure to ticagrelor, observed by activated GPIIb

  18. Polyphenols enhance platelet nitric oxide by inhibiting protein kinase C-dependent NADPH oxidase activation: effect on platelet recruitment.

    Science.gov (United States)

    Pignatelli, P; Di Santo, S; Buchetti, B; Sanguigni, V; Brunelli, A; Violi, F

    2006-06-01

    Several studies demonstrated an inverse association between polyphenol intake and cardiovascular events. Platelet recruitment is an important phase of platelet activation at the site of vascular injury, but it has never been investigated whether polyphenols influence platelet recruitment. The aim of the study was to analyze in vitro whether two polyphenols, quercetin and catechin, were able to affect platelet recruitment. Platelet recruitment was reduced by NO donors and by NADPH oxidase inhibitors and was enhanced by L-NAME, an inhibitor of NO synthase. Quercetin and catechin, but not single polyphenol, significantly inhibited platelet recruitment in a concentration-dependent fashion. The formation of superoxide anion was significantly inhibited in platelets incubated with quercetin and catechin but was unaffected by a single polyphenol. Incubation of platelets with quercetin and catechin resulted in inhibition of PKC and NADPH oxidase activation. Treatment of platelets with quercetin and catechin resulted in an increase of NO and also down-regulated the expression of GpIIb/IIIa glycoprotein. This study shows that the polyphenols quercetin and catechin synergistically act in reducing platelet recruitment via inhibition of PKC-dependent NADPH oxidase activation. This effect, resulting in NO-mediated platelet glycoprotein GpIIb/IIIa down-regulation, could provide a novel mechanism through which polyphenols reduce cardiovascular disease.

  19. Endothelium-Dependent Relaxation Effect of Apocynum venetum Leaf Extract via Src/PI3K/Akt Signalling Pathway

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    Yeh Siang Lau

    2015-06-01

    Full Text Available Botanical herbs are consumed globally not only as an essential diet but also as medicines or as functional/recreational food supplements. The extract of the Apocynum venetum leaves (AVLE, also known as Luobuma, exerts its antihypertensive effect via dilating the blood vessels in an endothelium- and concentration-dependent manner with optimal effect seen at as low as 10 µg/mL. A commercial Luoboma “antihypertensive tea” is available commercially in the western province of China. The present study seeks to investigate the underlying cellular mechanisms of the nitric oxide (NO-releasing property of AVLE in rat aortas and human umbilical vein endothelial cells (HUVECs. Endothelium-dependent relaxation induced by AVLE was assessed in organ chambers in the presence or absence of polyethyleneglycol catalase (PP2, 20 µM; inhibitor of Src kinase, wortmannin (30 nM and LY294002 (20 µM; PI3 (phosphatidylinositol3-Kinase inhibitor, NG-nitro-l-arginine (L-NAME, 100 µM; endothelial NO synthase inhibitor (eNOS and ODQ (1 µM; soluble guanylyl cyclase inhibitor. Total nitrite and nitrate (NOx level and protein expression of p-Akt and p-eNOS were measured. AVLE-induced endothelium-dependent relaxation was reduced by PP2, wortmannin and LY294002 and abolished by L-NAME and ODQ. AVLE significantly increased total NOx level in rat aortas and in HUVECs compared to control. It also instigated phosphorylation of Akt and eNOS in cultured HUVECs in a concentration-dependent manner and this was markedly suppressed by PP2, wortmannin and LY294002. AVLE also inhibited superoxide generated from both NADPH oxidase and xanthine/xanthine oxidase system. Taken together, AVLE causes endothelium-dependent NO mediated relaxations of rat aortas through Src/PI3K/Akt dependent NO signalling pathway and possesses superoxide scavenging activity.

  20. The vasorelaxant effect of gallic acid involves endothelium-dependent and -independent mechanisms.

    Science.gov (United States)

    de Oliveira, Lais Moraes; de Oliveira, Thiago Sardinha; da Costa, Rafael Menezes; de Souza Gil, Eric; Costa, Elson Alves; Passaglia, Rita de Cassia Aleixo Tostes; Filgueira, Fernando Paranaíba; Ghedini, Paulo César

    2016-06-01

    The mechanisms of action involved in the vasorelaxant effect of gallic acid (GA) were examined in the isolated rat thoracic aorta. GA exerted a relaxant effect in the highest concentrations (0.4-10mM) in both endothelium-intact and endothelium-denuded aortic rings. Pre-incubation with L-NAME, ODQ, calmidazolium, TEA, 4-aminopyridine, and barium chloride significantly reduced the pEC50 values. Moreover, this effect was not modified by indomethacin, wortmannin, PP2, glibenclamide, or paxillin. Pre-incubation of GA (1, 3, and 10mM) in a Ca(2+)-free Krebs solution attenuated CaCl2-induced contractions and blocked BAY K8644-induced vascular contractions, but it did not inhibit a contraction induced by the release of Ca(2+) from the sarcoplasmatic reticulum stores. In addition, a Western blot analysis showed that GA induces phosphorylation of eNOS in rat thoracic aorta. These results suggest that GA induces relaxation in rat aortic rings through an endothelium-dependent pathway, resulting in eNOS phosphorylation and opening potassium channels. Additionally, the relaxant effect by an endothelium-independent pathway involves the blockade of the Ca(2+) influx via L-type Ca(2+) channels. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Chronic treatment of male rats with daidzein and 17β-oestradiol induces the contribution of EDHF to endothelium-dependent relaxation

    Science.gov (United States)

    Woodman, Owen L; Boujaoude, Mirna

    2003-01-01

    We investigated the effect of chronic (7 days) treatment of male rats with the isoflavone daidzein (0.2 mg kg−1 sc per day) or 17β-oestradiol (0.1 mg kg−1 sc per day) on the contribution of nitric oxide (NO), prostaglandins and endothelium-derived hyperpolarising factor (EDHF) to endothelium-dependent relaxation of isolated aortic rings. The sensitivity and maximum relaxation to acetylcholine (ACh) were significantly greater in aortic rings from rats treated with daidzein or 17β-oestradiol, in comparison to vehicle-treated rats. Inhibition of nitric oxide synthase with N-nitro-L-arginine (L-NOARG) abolished ACh-induced relaxation in the aortae from vehicle-treated rats, but only attenuated relaxation in aortae from daidzein or 17β-oestradiol-treated rats. The presence of haemoglobin in addition to L-NOARG did not cause any further inhibition of relaxation. The cyclooxygenase inhibitor indomethacin had no effect on endothelium-dependent relaxation in aortae from any treatment group. Charybdotoxin (ChTX), which blocks large-conductance calcium-activated potassium channels (BKCa) and intermediate-conductance calcium-activated potassium channels (IKCa), plus apamin, which blocks small-conductance calcium-activated potassium channels (SKCa), but not iberiotoxin, which only blocks BKCa, attenuated endothelium-dependent relaxation of aortae from daidzein or 17β-oestradiol-treated rats. Blockade of KCa channels had no effect on the responses to ACh in aortae from vehicle-treated rats. In aortae from daidzein- or 17β-oestradiol-treated rats, endothelium-dependent relaxation was also attenuated by inhibition of cytochrome P450 (CYP450) epoxygenase with 6-(2-propargylloxyphenyl)hexanoic acid (PPOH) or inhibition of KIR channels and Na+/K+-ATPase with barium and oubain, respectively. This study demonstrates that endothelium-dependent relaxation of male rat aorta is normally entirely mediated by NO, whereas treatment with daidzein or 17β-oestradiol stimulates a

  2. [Isosorbide dinitrate inhibits in vitro platelet aggregation at submicromolar concentrations].

    Science.gov (United States)

    Gachet, C; Guillou, J; Moog, S; Cazenave, J P

    1992-04-01

    Nitrate derivatives have in vivo and in vitro platelet anti-aggregant properties in addition to their vasodilatory effects. The mode of action is related to increased intracytoplasmic cyclic GMP concentrations. It has been shown that isosorbide dinitrate (ISDN) has this type of platelet anti-aggregant activity but the reported results about the active concentrations and the inhibited pathways of activation are contradictory. This study was designed to determine whether ISDN has in vitro platelet anti-aggregant activity at low doses and to verify if this effect is selective by aggregation induced by ADP. Finally, a possible potentialisation of the inhibitors due to ISDN was looked for with cyclic nucleotide phosphodiesterase inhibitors and with agents simulating the effect of adenylate cyclase. The results showed that: 1) ISDN had platelet anti-aggregant activity in vitro at concentrations of about 10-7 M, 2) that this effect was not limited to the aggregation induced by ADP as the aggregation induced by PAF-acether was also inhibited by low dose ISDN, 3) of the cyclic nucleotide modulators tested, only quercetine (flavonoide) potentialised the effects of ISDN.

  3. Endothelium-Dependent Vasorelaxant Effects of Dealcoholized Wine Powder of Wild Grape (Vitis coignetiae in the Rat Thoracic Aorta

    Directory of Open Access Journals (Sweden)

    Sang Keun Ha

    2016-01-01

    Full Text Available The vasorelaxant effects of dealcoholized wild grape (Vitis coignetiae wine were investigated with isolated rat thoracic aorta. In our present study, we demonstrate that wild grape wine powder (WGWP induced relaxation of aortic rings preconstricted with norepinephrine in a dose-dependent manner (at concentrations ranging from 0.1 to 1 mg/mL. The vasorelaxant effect of WGWP was dependent on intact endothelia, which was attenuated by incubation with inhibitors of endothelium-derived relaxing factors, such as NG-nitro-L-arginine (nitric oxide synthase inhibitor, methylene blue (guanylate cyclase inhibitor, and indomethacin (cyclooxygenase inhibitor. Moreover, treatment with WGWP and atropine (muscarinic receptor antagonist or diphenylhydramine (histamine receptor antagonist significantly inhibited endothelium-dependent vasorelaxation. Our results suggest that WGWP induces relaxation in rat aortic rings in an endothelium-dependent manner. Results further indicate that this effect occurs via nitric oxide-cGMP pathway and prostacyclin-cAMP pathway through a muscarinic receptor and histamine receptor.

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

    OpenAIRE

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

    2013-01-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-depende...

  5. Long-term Treatment with Hesperidin Improves Endothelium-dependent Vasodilation in Femoral Artery of Spontaneously Hypertensive Rats: The Involvement of NO-synthase and KvChannels.

    Science.gov (United States)

    Dobiaš, Lukáš; Petrová, Miriam; Vojtko, Róbert; Kristová, Viera

    2016-10-01

    Hesperidin is the most common flavonoid found in citrus fruits and is expected to exert vasodilation action relevant to its health benefits. The present study aimed to explore the effect of hesperidin on the vascular responses in normotensive and hypertensive rats and the involvement of NO-synthase and K v channels. The 15-week-old Wistar and spontaneously hypertensive rats (SHR) were randomized to orally receive either hesperidin (50 mg/kg/day) or a corresponding volume of the water for 4 weeks. Vascular responses of isolated femoral arteries were studied with myograph in control conditions and during inhibition of NO-synthase with l-NNA and K v channels with 4-AP. Hesperidin had no effect on blood pressure. Endothelium-dependent vasodilation in Wistar and SHR was significantly improved by the treatment with hesperidin. The contraction responses after l-NNA were increased in all groups of rats to similar extent, but relaxatory responses were significantly attenuated only in SHR. The inhibition of K v channels significantly reduced endothelium-dependent vasodilatory responses in only in SHR administered with hesperidin. The results of our experiment indicate that hesperidin might improve the endothelium-dependent vasodilation during hypertension, possibly through the enhancement of K v channels function. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Inhibition of rabbit platelet activation in vitro by antagonists of platelet-activating factor (PAF)

    Energy Technology Data Exchange (ETDEWEB)

    Cox, C.P.; Wood, K.L.

    1986-03-05

    The authors used washed, (/sup 3/H)serotonin-labeled rabbit platelets to study the in vitro aggregation and secretion responses induced by graded doses of PAF in the presence or absence of specific antagonists of PAF. These antagonists included CV-3988, L-652,731, triazolam and alprazolam. Platelets were pretreated with either an antagonist or the appropriate diluent for 60 sec prior to the addition of PAF (2 x 10/sup -10/ to 2 x 10/sup -7/ M). Aggregation was monitored continuously and recorded as the height of the aggregation tracing at 60 sec post-PAF. Secretion of (/sup 3/H)-serotonin was measured in a sample of the platelets removed at 60 sec post-PAF. When 2 x 10/sup -10/ M PAF was used as the stimulus, the concentration of antagonist needed for 50% inhibition (IC/sub 50/) of secretion was obtained at 0.05 ..mu..M, 0.15 ..mu..M, 0.6 ..mu..M and 2.5 ..mu..M, respectively, for L-652,731, CV-3988, triazolam and alprazolam. The corresponding IC/sub 50/ for aggregation was obtained at 0.2 ..mu..M, 0.1 ..mu..M, 1.5 ..mu..M and 6.5 ..mu..M, respectively. The inhibitory effects of these antagonists could be overcome by increasing the dose of PAF used. Although all of the antagonists were capable of completely inhibiting platelet aggregation and secretion, L-652,731 was the most potent PAF antagonist on a molar basis.

  8. Effect of hypoxia on endothelium-dependent relaxation of canine and rabbit basilar arteries.

    Science.gov (United States)

    Nakagomi, T; Kassell, N F; Sasaki, T; Hongo, K; Fujiwara, S; Lehman, R M; Vollmer, D G

    1989-01-01

    An important role of endothelium-dependent relaxation in the local regulation of vascular tone has been suggested. In the present study, the effect of hypoxia on endothelium-dependent relaxation was investigated in canine and rabbit basilar and in rabbit common carotid arteries in vitro, using an isometric tension recording method. Hypoxia was introduced by changing the gas mixture in the in vitro chamber from 95% O2-5% CO2 to 95% N2-5% CO2. Thrombin and acetylcholine were used to induce endothelium-dependent relaxation. Thrombin at 0.1 and 1.0 U/ml, respectively, caused dose-dependent relaxation of the canine basilar artery precontracted by 10(-6)M prostaglandin F2 alpha. Acetylcholine also evoked dose-dependent relaxation of rabbit basilar and common carotid arteries precontracted by serotonin. Under hypoxic conditions, the relaxing effect of thrombin or acetylcholine decreased both in canine and in rabbit arteries, although it was not significant in rabbit basilar arteries. It has been postulated that following subarachnoid haemorrhage, diffusion of oxygen to the walls of the major cerebral arteries might be impaired by the subarachnoid clot. This could cause hypoxia of the arteries and contribute to vasospasm by suppressing endothelium-dependent relaxation, as well as by enhancing the contractile responses of the cerebral arteries to the vasoconstrictor agents in the bloody cerebrospinal fluid.

  9. In Vivo Cannabidiol Treatment Improves Endothelium-Dependent Vasorelaxation in Mesenteric Arteries of Zucker Diabetic Fatty Rats

    Directory of Open Access Journals (Sweden)

    Amanda J. Wheal

    2017-05-01

    Full Text Available Background and purpose: We have shown that in vitro treatment with cannabidiol (CBD, 2 h enhances endothelial function in arteries from Zucker diabetic fatty (ZDF rats, partly due to a cyclooxygenase (COX-mediated mechanism. The aim of the present study was to determine whether treatment with CBD in vivo would also enhance endothelial function.Experimental approach: Male ZDF rats, or ZDF Lean rats, were treated for 7 days (daily i.p. injection with either 10mg/kg CBD or vehicle (n = 6 per group. Sections of mesenteric resistance arteries, femoral arteries and thoracic aortae were mounted on a wire myograph, and cumulative concentration-response curves to endothelium-dependent (acetylcholine, ACh, 1 nM–100 μM or endothelium-independent (sodium nitroprusside, SNP, 1 nM–100 μM agents were constructed. Multiplex analysis was used to measure serum metabolic and cardiovascular biomarkers.Key results: Vasorelaxation to ACh was significantly enhanced in mesenteric arteries from CBD-treated ZDF rats, but not ZDF Lean rats. The enhanced vasorelaxation in ZDF mesenteric arteries was no longer observed after COX inhibition using indomethacin or nitric oxide (NO inhibition using L-NAME. Increased levels of serum c-peptide, insulin and intracellular adhesion molecule-1 observed in the ZDF compared to ZDF Lean rats were no longer significant after 7 days CBD treatment.Conclusion and implications: Short-term in vivo treatment with CBD improves ex vivo endothelium-dependent vasorelaxation in mesenteric arteries from ZDF rats due to COX- or NO-mediated mechanisms, and leads to improvements in serum biomarkers.

  10. Platelet secretory products inhibit lipoprotein metabolism in macrophages

    Science.gov (United States)

    Phillips, David R.; Arnold, Kay; Innerarity, Thomas L.

    1985-08-01

    Macrophages possess a receptor that binds low-density lipoproteins (LDL) containing lysine residues modified by acetylation (Ac LDL), acetoacetylation (AcAc LDL) or malondialdehyde treatment1-3. This receptor (referred to as the Ac LDL receptor or scavenger receptor) internalizes the bound lipoprotein. As a consequence, massive amounts of cholesteryl esters accumulate so that macrophages in culture resemble foam cells found in atherosclerotic lesions4,5. In an effort to identify an unmodified mammalian macromolecule that binds to the Ac LDL receptor, we investigated whether platelet secretory products affect the receptor-mediated endocytosis of chemically modified lipoproteins. Platelets are a potential source of such activity because they exist in close association with foam cells in developing atherosclerotic lesions6,7. Our study demonstrates that human blood platelets secrete a product that inhibits the binding and uptake of AcAc LDL by mouse peritoneal macrophages and the subsequent accumulation of cholesteryl esters. This is the first indication that an endogenous macromolecule interacts with Ac LDL receptor on macrophages.

  11. Antiplatelet Agents Inhibit The Generation Of Platelet-Derived Microparticles

    Directory of Open Access Journals (Sweden)

    Alice Giacomazzi

    2016-09-01

    Full Text Available Platelet microparticles (PMPs contribute to thrombogenesis but the effects of antiplatelet drugs on PMPs generation is undefined. The present study investigated the cellular events regulating PMP shedding, testing in vitro platelet agonists and inhibitors. Platelet-rich plasma from healthy subjects was stimulated with arachidonic acid, U46619, collagen type-I (10 and 1.5 µg/mL, epinephrine, ADP or TRAP-6 and pre-incubated with acetylsalicylic acid (ASA, 100 and 10 µmol/L, SQ-29,548, apyrase, PSB-0739, or eptifibatide. PMPs were detected by flow-cytometry using CD61 and annexin-V as fluorescent markers. Platelet agonists induced annexin V-positive PMP shedding. The strongest response was to high concentration collagen. ADP-triggered PMP shedding was dose-independent. ASA reduced PMPs induced by arachidonic acid- (645, 347-2946 vs 3061, 446-4901 PMPs/µL; median ad range, n=9, P<0.001, collagen 10 µg/mL (5317, 2027-15935 vs 10252, 4187-46316 PMPs/µL; n=13, P<0.001, collagen 1.5 µg/mL (1078, 528-2820 vs 1465, 582-5948 PMPs/µL; n=21, P<0.001 and TRAP-6 (2008, 1621-2495 vs 2840, 2404-3031 PMPs/µL; n=3, P<0.01 but did not affect the response to epinephrine or ADP. The ADP scavenger apyrase reduced PMPs induced by U46619 (1256, 395-2908 vs 3045, 1119-5494 PMPs/µL, n=6, P<0.05, collagen 1.5 µg/mL (1006, 780-1309 vs 2422, 1839-3494 PMPs/µL, n=3, P<0.01 and TRAP-6 (904, 761-1224 vs 2840, 2404-3031 PMPs/µL, n=3, P<0.01. The TP receptor antagonist SQ-29,548 and the P2Y12 receptor antagonist PSB-0739 markedly inhibited PMPs induced by low doses of collagen. Except for high-dose collagen, eptifibatide abolished agonist-induced PMP release. Both TXA2 generation and ADP secretion are required as amplifiers of PMP shedding. The crucial role of the fibrinogen receptor and the collagen receptor in PMPs generation, independently of platelet aggregation, was identified.

  12. Assessment of enhanced endothelium-dependent vasodilation by intermittent fasting in Wistar albino rats.

    Science.gov (United States)

    Razzak, Rima L Abdul; Abu-Hozaifa, Bodour M; Bamosa, Abdullah O; Ali, Nemah M

    2011-01-01

    Intermittent fasting (IF), a type of feeding regimen where the frequency of eating is reduced enhances cardiovascular stress adaptation and improves cardiovascular risk factors in rats. Data on the effect of IF on the endothelium is not common, so we examined whether IF showed similarity to documented beneficial effects of caloric restriction on endothelium-dependent vasodilatory responses of rat aortic rings. 25 young male Wistar rats had ad libitum (AL) access to food and 25 others were provided with food every other day for 2 months, during which their weight was measured every 2 weeks. Vascular reactivity of abdominal aorta was simultaneously evaluated using dual wire myographs. Weight gain was greater in the AL group (P<0.001) at all weighing intervals. Acetylcholine (ACh; 10(-10)-10(-5)M) produced greater (P<0.05) vasorelaxation in IF rats at the two highest concentrations. IF reduces weight gain in young male rats and improves their aortic endothelium-dependent vasorelaxation.

  13. Novel approaches to improving endothelium-dependent nitric oxide-mediated vasodilatation

    DEFF Research Database (Denmark)

    Simonsen, Ulf; Rodriguez-Rodriguez, Rosalia; Dalsgaard, Thomas

    2009-01-01

    Endothelial dysfunction, which is defined by decreased endothelium-dependent vasodilatation, is associated with an increased number of cardiovascular events. Nitric oxide (NO) bioavailability is reduced by altered endothelial signal transduction or increased formation of radical oxygen species...... reacting with NO. Endothelial dysfunction is therapeutically reversible and physical exercise, calcium channel blockers, angiotensin converting enzyme inhibitors, and angiotensin receptor antagonists improve flow-evoked endothelium-dependent vasodilation in patients with hypertension and diabetes. We have...... investigated three different approaches, with the aim of correcting endothelial dysfunction in cardiovascular disease. Thus, (1) we evaluated the effect of a cell permeable superoxide dismutase mimetic, tempol, on endothelial dysfunction in small arteries exposed to high pressure, (2) investigated...

  14. Shock releases bile acid inducing platelet inhibition and fibrinolysis.

    Science.gov (United States)

    Wiener, Gregory; Moore, Hunter B; Moore, Ernest E; Gonzalez, Eduardo; Diamond, Scott; Zhu, Shu; D'Alessandro, Angelo; Banerjee, Anirban

    2015-05-15

    Metabolites are underappreciated for their effect on coagulation. Taurocholic acid (TUCA), a bile acid, has been shown to regulate cellular activity and promote fibrin sealant degradation. We hypothesize that TUCA impairs whole blood clot formation and promotes fibrinolysis. TUCA was exogenously added to whole blood obtained from volunteers. A titration from 250 μM-750 μM was used due to biologic relevance. Whole blood mixtures were assayed using thrombelastography for clot strength (maximum amplitude [MA]) and fibrinolysis (LY30) quantification. Tranexamic acid was used to block plasmin-mediated fibrinolysis. Platelet microfluidics were performed. A proteomic analysis was completed on citrated plasma obtained from a shock and resuscitation rat model. Fibrinolysis increased when 750-μM TUCA was added to whole blood (median LY30 0.08-5.7, P = 0.010) and clot strength decreased (median MA of 53.3-43.8, P = 0.010). The addition of tranexamic acid, to a 750-μM TUCA titration, partially reversed the induced fibrinolysis (LY30: without 7.7 versus with 2.7) and the decrease in clot strength (MA: without 48.2 versus with 53.2), but did not reverse the effects to whole blood levels. Platelet function reduced by 50% in the presence of 100-μM TUCA. Rats had a median 52-fold increase in TUCA, after a shock state that stayed elevated after resuscitation. TUCA reduces clot strength and promotes fibrinolysis. The clot strength reduction is attributable to platelet inhibition. This metabolic effect on coagulation warrants further investigation, as localized areas of the body, with high levels of bile acid, may be at risk for postoperative bleeding. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Pycnogenol, French maritime pine bark extract, augments endothelium-dependent vasodilation in humans.

    Science.gov (United States)

    Nishioka, Kenji; Hidaka, Takayuki; Nakamura, Shuji; Umemura, Takashi; Jitsuiki, Daisuke; Soga, Junko; Goto, Chikara; Chayama, Kazuaki; Yoshizumi, Masao; Higashi, Yukihito

    2007-09-01

    Pycnogenol, an extract of bark from the French maritime pine, Pinus pinaster Ait., consists of a concentrate of water-soluble polyphenols. Pycnogenol contains the bioflavonoids catechin and taxifolin as well as phenolcarbonic acids. Antioxidants, such as bioflavonoids, enhance endothelial nitric oxide (NO) synthase expression and subsequent NO release from endothelial cells. The purpose of this study was to determine Pycnogenol's effects on endothelium-dependent vasodilation in humans. This was a double-blind, randomized, placebo and active drug study. We evaluated forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and to sodium nitroprusside (SNP), an endothelium-independent vasodilator, in healthy young men before and after 2 weeks of daily oral administration of Pycnogenol (180 mg/day) (n=8) or placebo (n=8). FBF was measured by using strain-gauge plethysmography. Neither the placebo nor Pycnogenol altered forearm or systemic hemodynamics. Pycnogenol, but not placebo, augmented FBF response to ACh, from 13.1 +/- 7.0 to 18.5 +/- 4.0 mL/min per 100 mL tissue (pPycnogenol groups. The administration of N(G)-monomethyl-L-arginine, an NO synthase inhibitor, completely abolished Pycnogenol-induced augmentation of the FBF response to ACh. These findings suggest that Pycnogenol augments endothelium-dependent vasodilation by increasing in NO production. Pycnogenol would be useful for treating various diseases whose pathogeneses involve endothelial dysfunction.

  16. Effects of autologous platelet transfusion on platelet inhibition in ticagrelor-treated and clopidogrel-treated subjects.

    Science.gov (United States)

    Teng, R; Carlson, G F; Nylander, S; Andersson, T L G

    2016-12-01

    Essentials Limited data on hemostatic benefits of platelet transfusion (PT) exist. 44 healthy subjects had a single dose of ticagrelor or clopidogrel ± autologous PT post-dosing. PT did not reverse ticagrelor's antiplatelet effects and had minimal impact post clopidogrel. Post-ticagrelor, PT is unlikely to be beneficial, and the benefits post-clopidogrel are unknown. Background Antiplatelet agents increase bleeding risk. Few data on hemostatic benefits of platelet transfusion exist. Objective To assess the effect of autologous platelet transfusion on ticagrelor-mediated and clopidogrel-mediated platelet inhibition in a single-center, open-label, randomized, cross-over study (NCT01744288). Methods Forty-four healthy subjects received ticagrelor (180 mg) or clopidogrel (600 mg; two functional CYP2C19 alleles [*1 or *17] required) with or without platelet transfusion (14-day washout). Subjects received one autologous platelet apheresis unit (approximately six pooled donor platelet units) 24 h (n = 15) or 48 h (n = 13) after ticagrelor or 48 h after clopidogrel (n = 16). Platelet apheresis was conducted 72 h before transfusion. Aspirin (81 mg per day) was taken from after apheresis until 24 h before transfusion. P2Y12 reaction units (PRUs) and inhibition of platelet aggregation (IPA) induced by ADP were measured. Results Mean age and body mass index were 30 years (standard deviation [SD] 6 years) and 26.9 kg m(-2) (SD 4.0 kg m(-2) ), respectively; 98% of subjects were men, and 39 of 44 completed treatment. Platelet transfusion 24 h after ticagrelor had minimal effects on IPA or PRU values within 48 h after transfusion. Platelet transfusion 48 h after ticagrelor also had minimal effects on IPA or PRU values at most post-transfusion times. Platelet transfusion 48 h after clopidogrel, versus no transfusion, had a small reversing effect on IPA (24 h, 36 h, and 48 h) and PRU values (12 h, 24 h, and 36 h) after transfusion. Conclusions Autologous platelet transfusion is

  17. Antipsychotic Drugs Inhibit Platelet Aggregation via P2Y1 and P2Y12 Receptors

    Directory of Open Access Journals (Sweden)

    Chang-Chieh Wu

    2016-01-01

    Full Text Available Antipsychotic drugs (APDs used to treat clinical psychotic syndromes cause a variety of blood dyscrasias. APDs suppress the aggregation of platelets; however, the underlying mechanism remains unknown. We first analyzed platelet aggregation and clot formation in platelets treated with APDs, risperidone, clozapine, or haloperidol, using an aggregometer and rotational thromboelastometry (ROTEM. Our data indicated that platelet aggregation was inhibited, that clot formation time was increased, and that clot firmness was decreased in platelets pretreated with APDs. We also examined the role two major adenosine diphosphate (ADP receptors, P2Y1 and P2Y12, play in ADP-mediated platelet activation and APD-mediated suppression of platelet aggregation. Our results show that P2Y1 receptor stimulation with ADP-induced calcium influx was inhibited by APDs in human and rats’ platelets, as assessed by in vitro or ex vivo approach, respectively. In contrast, APDs, risperidone and clozapine, alleviated P2Y12-mediated cAMP suppression, and the release of thromboxane A2 and arachidonic acid by activated platelets decreased after APD treatment in human and rats’ platelets. Our data demonstrate that each APD tested significantly suppressed platelet aggregation via different mechanisms.

  18. Fast rotating atherectomy catheter tip inhibits platelet aggregation and ATP release: a study using platelet-rich plasma.

    Science.gov (United States)

    Gehani, A A; Latif, A B; Rees, M R

    1998-10-01

    The interaction of atherectomy devices with the arterial wall is the focus of many studies, but their effect on the surrounding blood is largely unknown. This is a detailed investigation on the effects of a rotational atherectomy device with a fast rotating tip on platelet structure and function. Platelet-rich plasma (PRP) was obtained from six volunteers, divided into 5 mL samples, and subjected to the atherectomy tip rotating at 20, 40, or 80 thousand rpm for 30 or 60 seconds. Platelet aggregation to collagen or adenosine diphosphate (ADP) was obtained in all samples by means of a dual-chamber optical aggregometer. The fast rotating catheter tip caused marked inhibition of platelet aggregation to both collagen and ADP. The maximum extent of aggregation was reduced from 85% +/-2.8 in control to 46% +/-4.8 with collagen (pinvestigation.

  19. Effects of ethanol treatment on the neurogenic and endothelium-dependent relaxation of corpus cavernosum smooth muscle in the mouse

    National Research Council Canada - National Science Library

    Aydinoglu, Fatma; Yilmaz, Sakir N; Coskun, Banu; Daglioglu, Nebile; Ogulener, Nuran

    2008-01-01

    .... The neurogenic- and endothelium-dependent relaxation of corpus cavernosum smooth muscle and the degenerative effect of subacute ethanol treatment on the endothelial cells of corpus cavernosum was investigated in mice...

  20. ENDOTHELIUM-DEPENDENT RELAXATION IN 2 DIFFERENT MODELS OF CHRONIC HEART-FAILURE AND THE EFFECT OF IBOPAMINE

    NARCIS (Netherlands)

    BUIKEMA, H; VANGILST, WH; VANVELDHUISEN, DJ; DESMET, BJGL; LIE, KI; WESSELING, H

    1993-01-01

    Objectives: The purpose was to relate endothelium dependent relaxation to neurohumoral and haemodynamic changes in rats with chronic heart failure. Methods: Rats were submitted to either coronary ligation causing myocardial infarction or banding of the abdominal aorta (aortic stenosis), and

  1. Aspirin Inhibits Platelet-Derived Sphingosine-1-Phosphate Induced Endothelial Cell Migration.

    Science.gov (United States)

    Polzin, Amin; Knoop, Betül; Böhm, Andreas; Dannenberg, Lisa; Zurek, Mark; Zeus, Tobias; Kelm, Malte; Levkau, Bodo; Rauch, Bernhard H

    2018-01-01

    Aspirin plays a crucial role in the prevention of cardiovascular diseases. We previously described that aspirin has effects beyond inhibition of platelet aggregation, as it inhibited thrombin-mediated release of sphingosine-1-phosphate (S1P) from human platelets. S1P is a bioactive lipid with important functions on inflammation and apoptosis. In endothelial cells (EC), S1P is a key regulator of cell migration. In this study, we aimed to analyze the effects of aspirin on platelet-induced EC migration. Human umbilical EC migration was measured by Boyden chamber assay. EC migration was induced by platelet supernatants of thrombin receptor-activating peptide-1 (AP1) stimulated platelets. To investigate the S1P receptor subtype that promotes EC migration, specific inhibitors of S1P receptor subtypes were applied. S1P induced EC migration in a concentration-dependent manner. EC migration induced by AP1-stimulated platelet supernatants was reduced by aspirin. S1P1 receptor inhibition almost completely abolished EC migration induced by activated platelets. The inhibition of S1P2 or S1P3 receptor had no effect. Aspirin inhibits EC migration induced by activated platelets that is in part due to S1P and mediated by the endothelial S1P1 receptor. The clinical significance of this novel mechanism of aspirin action has to be investigated in future studies. © 2017 S. Karger AG, Basel.

  2. Inhibiting GPIbα shedding preserves post-transfusion recovery and hemostatic function of platelets after prolonged storage

    Science.gov (United States)

    Chen, Wenchun; Liang, Xin; Syed, Anum K.; Jessup, Paula; Church, William R.; Ware, Jerry; Josephson, Cassandra D.; Li, Renhao

    2016-01-01

    Objectives The platelet storage lesion accelerates platelet clearance after transfusion, but the underlying molecular mechanism remains elusive. Although inhibiting sheddase activity hampers clearance of platelets with storage lesion, the target platelet protein responsible for ectodomain shedding-induced clearance is not definitively identified. Monoclonal antibody 5G6 was developed recently to bind specifically human platelet receptor GPIbα and inhibit its shedding but not shedding of other receptors. Here, the role of GPIbα shedding in platelet clearance after transfusion was addressed. Approach and Results Both human leukoreduced apheresis-derived platelets and transgenic mouse platelets expressing human GPIbα (hTg) were stored at room temperature in the presence and absence of 5G6 Fab fragment. At various time points aliquots of stored platelets were analyzed and compared. 5G6 Fab inhibited GPIbα shedding in both platelets during storage and preserved higher level of GPIbα on the platelet surface. Compared with age-matched control platelets, 5G6 Fab-stored platelets exhibited similar levels of platelet activation, degranulation, and agonist-induced aggregation. 5G6 Fab-stored hTg platelets exhibited significantly higher post-transfusion recovery and in vivo hemostatic function in recipient mice than control platelets. Consistently 5G6 Fab-stored 8-day-old human platelets produced similar improvement in post-transfusion recovery in immunodeficient mice and in ex vivo thrombus formation over collagen under shear flow. Conclusions Specific inhibition of GPIbα shedding in the stored platelets improves post-transfusion platelet recovery and hemostatic function, providing clear evidence for GPIbα shedding as a cause of platelet clearance. These results suggest that specific inhibition of GPIbα shedding may be utilized to optimize platelet storage conditions. PMID:27417583

  3. 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.

  4. Aging and estrogen status: a possible endothelium-dependent vascular coupling mechanism in bone remodeling.

    Directory of Open Access Journals (Sweden)

    Rhonda D Prisby

    Full Text Available Bone loss with aging and menopause may be linked to vascular endothelial dysfunction. The purpose of the study was to determine whether putative modifications in endothelium-dependent vasodilation of the principal nutrient artery (PNA of the femur are associated with changes in trabecular bone volume (BV/TV with altered estrogen status in young (6 mon and old (24 mon female Fischer-344 rats. Animals were divided into 6 groups: 1 young intact, 2 old intact, 3 young ovariectomized (OVX, 4 old OVX, 5 young OVX plus estrogen replacement (OVX+E2, and 6 old OVX+E2. PNA endothelium-dependent vasodilation was assessed in vitro using acetylcholine. Trabecular bone volume of the distal femoral metaphysis was determined by microCT. In young rats, vasodilation was diminished by OVX and restored with estrogen replacement (intact, 82±7; OVX, 61±9; OVX+E2, 90±4%, which corresponded with similar modifications in BV/TV (intact, 28.7±1.6; OVX, 16.3±0.9; OVX+E2, 25.7±1.4%. In old animals, vasodilation was unaffected by OVX but enhanced with estrogen replacement (intact, 55±8; OVX, 59±7; OVX+E2, 92±4%. Likewise, modifications in BV/TV followed the same pattern (intact, 33.1±1.6; OVX, 34.4±3.7; OVX+E2, 42.4±2.1%. Furthermore, in old animals with low endogenous estrogen (i.e., intact and old OVX, vasodilation was correlated with BV/TV (R(2 = 0.630; P<0.001. These data demonstrate parallel effects of estrogen on vascular endothelial function and BV/TV, and provide for a possible coupling mechanism linking endothelium-dependent vasodilation to bone remodeling.

  5. Endothelium-dependent vasodilation is impaired in healthy offspring of hypertensive parents.

    Science.gov (United States)

    Bharani, Anil; Jain, Neeraj; Jain, Ashok; Deedwania, Prakash

    2011-01-01

    Impaired endothelium-dependent vasodilation has been demonstrated in asymptomatic normotensive offspring of hypertensive parents in Caucasians and Chinese population. The study was designed to determine whether impaired endothelium-dependent vasodilation is present in Indian normotensive offspring with hypertensive parents. We conducted this study in non smoker, healthy, young volunteers with a positive (n = 45) or a negative parental history (n = 30) of essential hypertension in a case-control, blinded design. The subjects underwent a thorough clinical and routine laboratory evaluation. A high resolution ultrasound was used to assess endothelium-dependent brachial artery flow-mediated dilation by a single observer blinded to the family histories. The brachial artery diameters at baseline and after occlusion release, flow mediated dilatation %, brachial intima-media thickness/lumen diameter were obtained and compared between the two groups using student's t-test. There was no significant difference between the two groups in age, sex, body mass index, blood pressure and total cholesterol levels. However, there was a statistically significant impairment of flow mediated dilatation amongst subjects with parental history of hypertension compared to controls (6.87 SD 8.14 % vs 11.31 SD 5.17%, p < 0.01). Multiple regression analysis revealed no association of FMD with age, blood pressure, BMI or total cholesterol in those with or without parental hypertension. Our study demonstrated impaired brachial artery flow mediated dilatation amongst normotensive offspring with parental hypertension compared to controls. This suggests that endothelial dysfunction possibly precedes clinical hypertension and might have a role in the pathogenesis of essential hypertension.

  6. Endothelium-dependent relaxation of rat aorta to a histamine H3 agonist is reduced by inhibitors of nitric oxide synthase, guanylate cyclase and Na+,K+-ATPase

    Directory of Open Access Journals (Sweden)

    D. M. Djuric

    1996-01-01

    Full Text Available The possible involvement of different effector systems (nitric oxide synthase, guanylate cyclase, β-adrenergic and muscarinic cholinergic receptors, cyclooxygenase and lipoxygenase, and Na+,K+-ATPase was evaluated in a histamine H3 receptor agonist-induced ((Rα-methylhistamine, (Rα-MeHA endothelium-dependent rat aorta relaxation assay. (Rα-MeHA (0.1 nM – 0.01 mM relaxed endothelium-dependent rat aorta, with a pD2 value of 8.22 ± 0.06, compared with a pD2 value of 7.98 ± 0.02 caused by histamine (50% and 70% relaxation, respectively. The effect of (Rα-MeHA (0.1 nM – 0.01 mM was competitively antagonized by thioperamide (1, 10 and 30 nM (pA2 = 9.21 ± 0.40; slope = 1.03 ± 0.35 but it was unaffected by pyrilamine (100 nM, cimetidine (1 μM, atropine (10 μM, propranolol (1 μM, indomethacin (10 μM or nordthydroguaiaretic acid (0.1 mM. Inhibitors of nitric oxide synthase, L-NG-monomethylarginine (L-NMMA, 10 μM and NG-nitro-L-arginine methylester (L-NOARG, 10 μM inhibited the relaxation effect of (Rα-MeHA, by approximately 52% and 70%, respectively. This inhibitory effect of L-NMMA was partially reversed by L-arginine (10 μM. Methylene blue (10 μM and ouabain (10 μM inhibited relaxation (Rα-MeHA-induced by approximately 50% and 90%, respectively. The products of cyclooxygenase and lipoxygenase are not involved in (Rα-MeHA-induced endothelium-dependent rat aorta relaxation nor are the muscarinic cholinergic and β-adrenergic receptors. The results also suggest the involvement of NO synthase, guanylate cyclase and Na+,K+-ATPase in (Rα-MeHA-induced endothelium-dependent rat aorta relaxation.

  7. B2 kinin receptor activation is the predominant mechanism by which trypsin mediates endothelium-dependent relaxation in bovine coronary arteries.

    Science.gov (United States)

    Drummond, Grant R; Selemidis, Stavros; Cocks, Thomas M

    2008-07-01

    The roles of kinin and protease-activated receptors (PAR) in endothelium-dependent relaxations to the serine protease, trypsin, were examined in rings of bovine left anterior descending coronary artery (LAD). Trypsin (0.01-30 U/ml) caused biphasic, endothelium-dependent relaxations-a high potency (0.01-0.3 U/ml), low efficacy relaxation [maximum relaxation (R (max)), 9.0 +/- 5.1%] followed by a lower potency (1-30 U/ml) but high efficacy (R (max), 90.4 +/- 5.5%) relaxation, which was abolished by aprotinin. Captopril (10 microM) caused an approximately 10-fold leftward shift of the second phase response such that the first phase was masked. The second phase relaxation to trypsin was inhibited in a concentration-dependent, non-surmountable manner by the B2 antagonist, HOE-140. At 3 nM HOE-140, the second phase response to trypsin was abolished unmasking the first phase. Kallikrein (0.0003-0.3 U/ml) caused monophasic, endothelium-dependent relaxations (R (max), 33.7 +/- 14.6%), which were potentiated by captopril (R (max), 94.2 +/- 1.0%) and abolished by HOE-140. In the presence of captopril, the second phase relaxation to trypsin was only minimally inhibited by either N(G)-nitro-L: -arginine (100 microM) or 67 mM [K(+)](o) alone but markedly reduced when these two treatments were combined (R (max), 26.1 +/- 11.6% versus 98.6 +/- 2.9% in controls). The PAR1-activating peptide, SFLLRN (0.1-30 microM), but not the PAR2-activating peptide, SLIGRL, caused concentration-dependent relaxations (pEC(50), 5.9 +/- 0.0%; R (max), 43.3 +/- 8.3%). In conclusion, trypsin causes endothelium-dependent relaxations in the bovine LAD predominantly via release of endogenous BK, which in turn activates endothelial B2 receptors. Only a minor role for PAR1-like receptors was evident in this tissue.

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

    Directory of Open Access Journals (Sweden)

    Wei Li

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

  9. Aspirin inhibition of platelet deposition at angioplasty sites: demonstration by platelet scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Cuningham, D.A.; Kumar, B.; Siegel, B.A.; Gilula, L.A.; Totty, W.G.; Welch, M.J.

    1984-05-01

    In-111 platelet scintigraphy was used to evaluate the effects of prior aspirin administration on the accumulation of In-111-labeled autologous platelets at sites of arterial injury resulting from iliac, femoral, or popliteal transluminal angioplasty in a nonrandomized study of 17 men. The degree of platelet localization at angioplasty sites was significantly less in nine men who had received aspirin in varying doses within the 4 days before angioplasty than in eight men who had not received aspirin for at least two weeks. The results suggest that aspirin treatment before angioplasty limits the early platelet deposition at the angioplasty site in men.

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

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    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.

  11. Evaluation of macrocirculatory endothelium-dependent and endothelium-independent vasoreactivity in vascular disease.

    Science.gov (United States)

    Abularrage, Christopher J; Sidawy, Anton N; Aidinian, Gilbert; Singh, Niten; Weiswasser, Jonathan M; Arora, Subodh

    2005-09-01

    Macrocirculatory endothelium-dependent and independent vasodilatation is integral to tissue-bed oxygen delivery and homeostasis. Dysfunction of macrocirculatory vasoreactivity is a precursor to atherosclerosis and occurs in a similar fashion in multiple tissue beds long before the onset of symptoms. Impaired macrocirculatory vasodilatation has been shown to occur in certain disease states including diabetes mellitus, hypercholesterolemia, chronic renal failure, peripheral arterial atherosclerosis, and abdominal aortic aneurysms, as well as secondary to smoking, advanced age, menopause, high-fat diet, and sedentary lifestyle. Brachial artery vasoreactivity is a noninvasive means of assessing macrocirculatory vasodilatory capacity that may help identify patients at increased risk for peripheral and cardiovascular disease and allow for objective assessment and monitoring of treatment. Endothelium-dependent vasoreactivity, or flow-mediated dilatation, is measured after brachial artery occlusion with a pneumatic blood pressure cuff, and endothelium-independent vasoreactivity is measured after the administration of sublingual nitroglycerin. The accuracy of brachial artery vasoreactivity is dependent on hematologic variables, as well as diurnal, day-to-day, ultrasound operator, and reader variations; however, the overall coefficient of variation is only 1.8%. We discuss the importance of the macrocirculation, investigative methods for evaluating macrocirculatory vasoreactivity, and review the literature of vasoreactivity in these different states.

  12. Effects of calcium dobesilate on the synthesis of endothelium-dependent relaxing factors in rabbit isolated aorta

    Science.gov (United States)

    Ruiz, E; Lorente, R; Tejerina, T

    1997-01-01

    Some cardiovascular disturbances which occur in diabetics are a consequence of alterations in vascular contractility as well as in endothelium-dependent relaxation. Calcium dobesilate (DOBE) is a drug used in diabetic retinopathy and its mechanism of action is not yet understood. The aim of this study was to investigate the effects of DOBE on synthesis and release of endothelium-dependent relaxing factor (EDRF) and endothelium-dependent hyperpolarizing factor (EDHF) in rabbit isolated aorta. Endothelium-dependent relaxation induced by acetylcholine (ACh) (10−8–10−5 M) increased in the presence of DOBE 10−5 M only when vascular endothelium was kept intact. NG-nitro-L-arginine methyl ester (L-NAME; 10−8–10−4 M progressively decreased the enhancing effect of DOBE on endothelium-dependent relaxation whereas it was progressively increased by L-Arg. DOBE 10−5 M increased in a non-significant manner endothelium-dependent relaxation induced by ACh when the arteries were incubated with both L-NAME 10−4 M and indomethacin 10−6 M. DOBE (10−6 M and 10−5 M) was able to scavenge superoxide anion radicals generated by the hypoxanthine/xanthine oxidase reaction. These results provide evidence that DOBE is able to affect the vascular disorders associated with diabetes mellitus since it enhances the synthesis of endothelium-dependent relaxing factors. PMID:9208138

  13. Use of Aspirin and P2Y12 Response Assays in Detecting Reversal of Platelet Inhibition With Platelet Transfusion in Patients With Traumatic Brain Injury on Antiplatelet Therapy.

    Science.gov (United States)

    Choi, Phillip A; Parry, Phillip V; Bauer, Joshua S; Zusman, Benjamin E; Panczykowski, David M; Puccio, Ava M; Okonkwo, David O

    2017-01-01

    At present, guidelines are lacking on platelet transfusion in patients with a traumatic intracranial bleed and history of antiplatelet therapy. The aspirin and P2Y 12 response unit (ARU and PRU, respectively) assays detect the effect of aspirin and P2Y 12 inhibitors in the cardiac population. To describe the reversal of platelet inhibition after platelet transfusion using the ARU and PRU assays in patients with traumatic brain injury. Between 2010 and 2015, we conducted a prospective comparative cohort study of patients presenting with a positive head computed tomography and a history of antiplatelet therapy. ARU and PRU assays were performed on admission and 6 hours after transfusion, with a primary end point of detection of disinhibition after platelet transfusion. One hundred seven patients were available for analysis. Seven percent of patients taking aspirin and 27% of patients taking clopidogrel were not therapeutic on admission per the ARU and PRU, respectively. After platelet transfusion, 51% of patients on any aspirin and 67% of patients on any clopidogrel failed to be reversed. ARU increased by 71 ± 76 per unit of apheresis platelets for patients taking any aspirin, and PRU increased by 48 ± 46 per unit of apheresis platelets for patients taking any clopidogrel. A significant percentage of patients taking aspirin or clopidogrel were not therapeutic and thus would be unlikely to benefit from a platelet transfusion. In patients with measured platelet inhibition, a single platelet transfusion was not sufficient to reverse platelet inhibition in almost half.

  14. Achieved platelet aggregation inhibition after different antiplatelet regimens during percutaneous coronary intervention for ST-segment elevation myocardial infarction

    NARCIS (Netherlands)

    Ernst, N.M.S.K.; Suryapranata, H.; Miedema, Kor; Slingerland, R.J.; Ottervanger, J.P.; Hoornije, J.C.A.; Gosselink, A.T.M.; Dambrink, J.H.E.; de Boer, M.J.; Zijlstra, F.; van't Hof, A.W.J.

    2004-01-01

    Objectives To evaluate the extent of platelet aggregation inhibition in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), treated with different antiplatelet agents and dosages. Background The extent of platelet aggregation

  15. Vascular Protective Effect of an Ethanol Extract of Camellia japonica Fruit: Endothelium-Dependent Relaxation of Coronary Artery and Reduction of Smooth Muscle Cell Migration

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    Sin-Hee Park

    2016-01-01

    Full Text Available Camellia japonica is a popular garden plant in Asia and widely used as cosmetic sources and traditional medicine. However, the possibility that C. japonica affects cardiovascular system remains unclear. The aim of the present study was to evaluate vascular effects of an extract of C. japonica. Vascular reactivity was assessed in organ baths using porcine coronary arteries and inhibition of proliferation and migration were assessed using human vascular smooth muscle cells (VSMCs. All four different parts, leaf, stem, flower, and fruits, caused concentration-dependent relaxations and C. japonica fruit (CJF extract showed the strongest vasorelaxation and its effect was endothelium dependent. Relaxations to CJF were markedly reduced by inhibitor of endothelial nitric oxide synthase (eNOS and inhibitor of PI3-kinase, but not affected by inhibitor of cyclooxygenase and endothelium-derived hyperpolarizing factor-mediated response. CJF induced activated a time- and concentration-dependent phosphorylation of eNOS in endothelial cells. Altogether, these studies have demonstrated that CJF is a potent endothelium-dependent vasodilator and this effect was involved in, at least in part, PI3K-eNOS-NO pathway. Moreover, CJF attenuated TNF-α induced proliferation and PDGF-BB induced migration of VSMCs. The present findings indicate that CJF could be a valuable candidate of herbal medicine for cardiovascular diseases associated with endothelial dysfunction and atherosclerosis.

  16. platelets

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    Joanna Saluk

    2014-04-01

    Full Text Available Platelets are the smallest, depleted of nucleus blood cells which contain a typical cellular organelles including the mitochondria, so that have active metabolism. Platelets possess the highly organized cytoskeleton, specific secretory granules and unique membrane receptors system responsible for their high reactivity. The key role of blood platelets is to maintain normal hemostasis, but they also play important roles in inflammation, immune processes and the cancer progression. The anucleated, small platelets occur in representatives of all clusters of mammals, so it seems to be an adaptation feature. In other vertebrates similar hemostatic functions are played by large nucleated platelets, which are much more weakly reactive. Small, reactive platelets, appearing in the evolution of mammals, allowed the formation of clots faster and slower blood loss in case of injury, but also increased the risk of thromboembolic and cardiovascular diseases. Daily the human body forms about 1x1011 platelets, which are produced by a process of differentiation, maturation and fragmentation of the cytoplasm of mature megakaryocytes. The emergence of platelets is the final stage of megakaryocyte differentiation and is followed by formation of the direct precursors called proplatelets. The anucleated platelets are regarded as terminally differentiated cells, which are not capable of further cell division. However, despite the absence of a nucleus, in blood platelets the synthesis and transcription of mitochondrial DNA and protein synthesis occurring on the basis of mRNA from megakaryocytes has been confirmed. However, recent studies published in 2012 show that the platelets are capable not only of the process of protein synthesis, but also of generation of new cells, which are functionally and structurally similar to the parent platelets.

  17. Inhibitory effects of ticagrelor compared with clopidogrel on platelet function in patients with acute coronary syndromes: the PLATO (PLATelet inhibition and patient Outcomes) PLATELET substudy.

    Science.gov (United States)

    Storey, Robert F; Angiolillo, Dominick J; Patil, Shankar B; Desai, Bhaloo; Ecob, Rosemary; Husted, Steen; Emanuelsson, Hakan; Cannon, Christopher P; Becker, Richard C; Wallentin, Lars

    2010-10-26

    The PLATO (PLATelet inhibition and patient Outcomes) PLATELET substudy aimed to compare the antiplatelet effects of clopidogrel and ticagrelor in patients with acute coronary syndromes. The PLATO study demonstrated superiority of ticagrelor over clopidogrel in the prevention of ischemic events in patients with acute coronary syndromes. Patients were randomized to receive either clopidogrel (300- to 600-mg loading dose [LD], 75 mg/day) or ticagrelor (180-mg LD, 90 mg twice daily). The effects of maintenance therapy were studied in 69 patients pre- and 2 to 4 h post-dose after at least 28 days. The LD effect was studied in 24 clopidogrel-naive patients. Light transmittance aggregometry (adenosine diphosphate 5 to 20 μM), VerifyNow P2Y12, and VASP phosphorylation assays were performed. During maintenance therapy, ticagrelor achieved greater suppression of platelet reactivity compared with clopidogrel. The mean maximum light transmittance aggregometry responses (adenosine diphosphate 20 μM) post-maintenance dose were 44±15% for clopidogrel and 28±10% for ticagrelor (p<0.001). High platelet reactivity was seen more frequently in the clopidogrel group. Proton pump inhibitor use was associated with higher platelet reactivity with clopidogrel but not ticagrelor. The ticagrelor LD also achieved greater inhibition of platelet aggregation compared with the clopidogrel LD. Ticagrelor achieves greater antiplatelet effect than clopidogrel in patients with acute coronary syndromes, both in the first hours of treatment and during maintenance therapy. Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  18. Inhibition of uptake of adenosine into human blood platelets

    NARCIS (Netherlands)

    Lips, J.P.M.; Sixma, J.J.; Trieschnigg, A.C.

    1980-01-01

    Adenosine transport into human blood platelets is mediated by two independent systems with different affinities. Both systems transport only purine nucleosides and no pyrimidine nucleosides. In experiments with differently substituted purine nucleosides, purines and analogues, differences in carrier

  19. Calcium dobesilate increased endothelium-dependent relaxation in isolated rabbit aorta.

    Science.gov (United States)

    Ruiz, E; Tejerina, T

    1998-05-01

    1. The aim of this study was to investigate the effects of calcium dobesilate on relaxant and contractile responses in the isolated rabbit aorta. 2. Calcium dobesilate (10(-6) and 10(-4) M) shifted the concentration-response curve induced by noradrenaline (10(-8)-10(-4) M) downward and to the right, the IC50 being 5.1 +/- 1.1 x 10(-7) M in the control and 7.5 +/- 1.2 x 10(-6) M and 3.1 +/- 1.9 x 10(-6) M in the presence of calcium dobesilate, 10(-6) M and 10(-4) M respectively. 3. Calcium dobesilate, 10(-5) M, increased the endothelium-dependent relaxation induced by acetylcholine (10(-8)-10(-5) M) but had no actions in the absence of endothelium.

  20. The gastrointestinal peptide obestatin induces vascular relaxation via specific activation of endothelium-dependent NO signalling

    Science.gov (United States)

    Agnew, Andrew J; Robinson, Emma; McVicar, Carmel M; Harvey, Adam P; Ali, Imran HA; Lindsay, Jennifer E; McDonald, Denise M; Green, Brian D; Grieve, David J

    2012-01-01

    BACKGROUND AND PURPOSE Obestatin is a recently discovered gastrointestinal peptide with established metabolic actions, which is linked to diabetes and may exert cardiovascular benefits. Here we aimed to investigate the specific effects of obestatin on vascular relaxation. EXPERIMENTAL APPROACH Cumulative relaxation responses to obestatin peptides were assessed in rat isolated aorta and mesenteric artery (n≥ 8) in the presence and absence of selective inhibitors. Complementary studies were performed in cultured bovine aortic endothelial cells (BAEC). KEY RESULTS Obestatin peptides elicited concentration-dependent relaxation in both aorta and mesenteric artery. Responses to full-length obestatin(1–23) were greater than those to obestatin(1–10) and obestatin(11–23). Obestatin(1–23)-induced relaxation was attenuated by endothelial denudation, l-NAME (NOS inhibitor), high extracellular K+, GDP-β-S (G-protein inhibitor), MDL-12,330A (adenylate cyclase inhibitor), wortmannin (PI3K inhibitor), KN-93 (CaMKII inhibitor), ODQ (guanylate cyclase inhibitor) and iberiotoxin (BKCa blocker), suggesting that it is mediated by an endothelium-dependent NO signalling cascade involving an adenylate cyclase-linked GPCR, PI3K/PKB, Ca2+-dependent eNOS activation, soluble guanylate cyclase and modulation of vascular smooth muscle K+. Supporting data from BAEC indicated that nitrite production, intracellular Ca2+ and PKB phosphorylation were increased after exposure to obestatin(1–23). Relaxations to obestatin(1–23) were unaltered by inhibitors of candidate endothelium-derived hyperpolarizing factors (EDHFs) and combined SKCa/IKCa blockade, suggesting that EDHF-mediated pathways were not involved. CONCLUSIONS AND IMPLICATIONS Obestatin produces significant vascular relaxation via specific activation of endothelium-dependent NO signalling. These actions may be important in normal regulation of vascular function and are clearly relevant to diabetes, a condition characterized by

  1. Affinity labeling of a human platelet membrane protein with 5'-p-fluorosulfonylbenzoyl adenosine. Concomitant inhibition of ADP-induced platelet aggregation and fibrinogen receptor exposure.

    Science.gov (United States)

    Figures, W R; Niewiarowski, S; Morinelli, T A; Colman, R F; Colman, R W

    1981-08-10

    Incubation of washed human blood platelets with 5'-p-fluorosulfonylbenzoyl [3H]adenosine (FSBA) covalently labels a single polypeptide of Mr = 100,000. Protection by ADP has suggested that an ADP receptor on the platelet surface membrane was modified. The modified cells, unlike native platelets, failed to aggregate in response to ADP (100 microM) and fibrinogen (1 mg/ml). The extent of binding of 125I-fibrinogen and aggregation was inhibited to a degree related to the incorporation of 5'-p-sulfonylbenzoyl adenosine (SBA) into platelets, indicating FSBA could inhibit the exposure of fibrinogen receptors by ADP necessary for aggregation. Incubation of SBA platelets with alpha-chymotrypsin cleaved the covalently labeled polypeptide and concomitantly reversed the inhibition of aggregation and fibrinogen binding. Platelets proteolytically digested by chymotrypsin prior to exposure to FSBA did not require ADP for aggregation and fibrinogen binding. Moreover, subsequent exposure to FSBA did not inhibit aggregation or fibrinogen binding. The affinity reagent FSBA can displace fibrinogen bound to platelets in the presence of ADP, as well as promote the rapid disaggregation of the platelets. The apparent initial pseudo-first order rate constant of dissociation of fibrinogen was linearly proportional to FSBA concentrations. These studies suggest that a single polypeptide can be altered either by ADP-induced conformational changes or proteolysis by chymotrypsin to reveal latent fibrinogen receptors and promote aggregation of platelets after fibrinogen binding.

  2. A novel role of sesamol in inhibiting NF-κB-mediated signaling in platelet activation

    Directory of Open Access Journals (Sweden)

    Chang Chao-Chien

    2011-12-01

    Full Text Available Abstract Background Platelet activation is relevant to a variety of coronary heart diseases. Our previous studies revealed that sesamol possesses potent antiplatelet activity through increasing cyclic AMP formation. Although platelets are anucleated cells, they also express the transcription factor, NF-κB, that may exert non-genomic functions in platelet activation. Therefore, we further investigated the inhibitory roles of sesamol in NF-κB-mediated platelet function. Methods Platelet aggregation, Fura 2-AM fluorescence, and immunoblotting analysis were used in this study. Results NF-κB signaling events, including IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation, were markedly activated by collagen (1 μg/ml in washed human platelets, and these signaling events were attenuated by sesamol (2.5~25 μM. Furthermore, SQ22536 and ODQ, inhibitors of adenylate cyclase and guanylate cyclase, respectively, strongly reversed the sesamol (25 μM-mediated inhibitory effects of IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation stimulated by collagen. The protein kinase A (PKA inhibitor, H89, also reversed sesamol-mediated inhibition of IκBα degradation. Moreover, BAY11-7082, an NF-κB inhibitor, abolished IκBα degradation, phospholipase C (PLCγ2 phosphorylation, protein kinase C (PKC activation, [Ca2+]i mobilization, and platelet aggregation stimulated by collagen. Preincubation of platelets with the inhibitors, SQ22536 and H89, both strongly reversed sesamol-mediated inhibition of platelet aggregation and [Ca2+]i mobilization. Conclusions Sesamol activates cAMP-PKA signaling, followed by inhibition of the NF-κB-PLC-PKC cascade, thereby leading to inhibition of [Ca2+]i mobilization and platelet aggregation. Because platelet activation is not only linked to hemostasis, but also has a relevant role in inflammation and metastasis, our data demonstrating that inhibition of NF-κB interferes with platelet function may

  3. Endothelium-dependent vasorelaxation in inhibited by in vivo depletion of vascular thiol levels

    DEFF Research Database (Denmark)

    Laursen, J B; Boesgaard, S; Trautner, S

    2001-01-01

    superoxide anion (O2.-) production in conscious chronically catheterized rats. Thiol depletion induced by buthionine sulfoximine (BSO, 1 g i.p. within 24 h) decreased the hypotensive effect of Ach by 30% (MAP reduction before BSO 27 +/- 3 mmHg, 19 +/- 3 mmHg after BSO, (mean +/- SEM), p ...). The impaired effect of Ach was associated with a significant reduction in eNOS activity (control: 7.7 +/- 0.8, BSO: 3.9 +/- 0.4 pmol/min/mg protein (p ... by BSO (BSO: 4415 +/- 123, control: 4105 +/- 455 counts/mg; n = 6) in rat aorta. It is concluded that in vivo thiol depletion results in endothelial dysfunction and a reduced receptor-mediated vascular relaxation. This effect is caused by reduced endothelial NO formation....

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

    Directory of Open Access Journals (Sweden)

    Milagros Garcia Mesa

    2011-06-01

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Reactive Oxygen Species-Induced Impairment of Endothelium-Dependent Relaxations in Rat Aortic Rings: Protection by Methanolic Extracts of Phoebe grandis

    Directory of Open Access Journals (Sweden)

    Mohd Rais Mustafa

    2011-04-01

    Full Text Available Generation of reactive oxygen species plays a pivotal role in the development of cardiovascular diseases. The present study describes the effects of the methanolic extract of Phoebe grandis (MPG stem bark on reactive oxygen species-induced endothelial dysfunction in vitro. Endothelium-dependent (acetylcholine, ACh and -independent relaxation (sodium nitroprusside, SNP was investigated from isolated rat aorta of Sprague-Dawley (SD in the presence of the β-NADH (enzymatic superoxide inducer and MPG extract. Superoxide anion production in aortic vessels was measured by lucigen chemiluminesence. Thirty minutes incubation of the rat aorta in vitro with β-NADH increased superoxide radical production and significantly inhibited ACh-induced relaxations. Pretreatment with MPG (0.5, 5 and 50 μg/mL restored the ACh-induced relaxations (Rmax: 92.29% ± 2.93, 91.02% ± 4.54 and 88.31 ± 2.36, respectively in the presence of β-NADH. MPG was ineffective in reversing the impaired ACh-induced relaxations caused by pyrogallol, a non-enzymatic superoxide generator. Superoxide dismutase (a superoxide scavenger, however, reversed the impaired ACh relaxations induced by both β-NADH and pyrogallol. MPG also markedly inhibited the β-NADH-induced generation of the superoxide radicals. Furthermore, MPG scavenging peroxyl radicals generated by tBuOOH (10−4 M.These results indicate that MPG may improve the endothelium dependent relaxations to ACh through its scavenging activity as well as by inhibiting the NADH/NADPH oxidase induced generation of superoxide anions.

  7. Reactive oxygen species-induced impairment of endothelium-dependent relaxations in rat aortic rings: protection by methanolic extracts of Phoebe grandis.

    Science.gov (United States)

    Yeh-Siang, Lau; Subramaniam, Gopal; Hadi, A Hamid A; Murugan, Dharmani; Mustafa, Mohd Rais

    2011-04-06

    Generation of reactive oxygen species plays a pivotal role in the development of cardiovascular diseases. The present study describes the effects of the methanolic extract of Phoebe grandis (MPG) stem bark on reactive oxygen species-induced endothelial dysfunction in vitro. Endothelium-dependent (acetylcholine, ACh) and -independent relaxation (sodium nitroprusside, SNP) was investigated from isolated rat aorta of Sprague-Dawley (SD) in the presence of the β-NADH (enzymatic superoxide inducer) and MPG extract. Superoxide anion production in aortic vessels was measured by lucigen chemiluminesence. Thirty minutes incubation of the rat aorta in vitro with β-NADH increased superoxide radical production and significantly inhibited ACh-induced relaxations. Pretreatment with MPG (0.5, 5 and 50 μg/mL) restored the ACh-induced relaxations (R(max): 92.29% ± 2.93, 91.02% ± 4.54 and 88.31 ± 2.36, respectively) in the presence of β-NADH. MPG was ineffective in reversing the impaired ACh-induced relaxations caused by pyrogallol, a non-enzymatic superoxide generator. Superoxide dismutase (a superoxide scavenger), however, reversed the impaired ACh relaxations induced by both β-NADH and pyrogallol. MPG also markedly inhibited the β-NADH-induced generation of the superoxide radicals. Furthermore, MPG scavenging peroxyl radicals generated by tBuOOH (10⁻⁴ M).These results indicate that MPG may improve the endothelium dependent relaxations to ACh through its scavenging activity as well as by inhibiting the NADH/NADPH oxidase induced generation of superoxide anions.

  8. Visfatin impairs endothelium-dependent relaxation in rat and human mesenteric microvessels through nicotinamide phosphoribosyltransferase activity.

    Science.gov (United States)

    Vallejo, Susana; Romacho, Tania; Angulo, Javier; Villalobos, Laura A; Cercas, Elena; Leivas, Alejandra; Bermejo, Elena; Carraro, Raffaele; Sánchez-Ferrer, Carlos F; Peiró, Concepción

    2011-01-01

    Visfatin, also known as extracellular pre-B-cell colony-enhancing factor (PBEF) and nicotinamide phosphoribosyltransferase (Nampt), is an adipocytokine whose circulating levels are enhanced in metabolic disorders, such as type 2 diabetes mellitus and obesity. Circulating visfatin levels have been positively associated with vascular damage and endothelial dysfunction. Here, we investigated the ability of visfatin to directly impair vascular reactivity in mesenteric microvessels from both male Sprague-Dawley rats and patients undergoing non-urgent, non-septic abdominal surgery. The pre-incubation of rat microvessels with visfatin (50 and 100 ng/mL) did not modify the contractile response to noradrenaline (1 pmol/L to 30 µmol/L), as determined using a small vessel myograph. However, visfatin (10 to 100 ng/mL) concentration-dependently impaired the relaxation to acetylcholine (ACh; 100 pmol/L to 3 µmol/L), without interfering with the endothelium-independent relaxation to sodium nitroprusside (1 nmol/L to 3 µmol/L). In both cultured human umbilical vein endothelial cells and rat microvascular preparations, visfatin (50 ng/mL) stimulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, as determined by lucigenin-derived chemiluminiscence. The relaxation to ACh impaired by visfatin was restored by the NADPH oxidase inhibitor apocynin (10 µmol/L). Additionally, the Nampt inhibitor APO866 (10 mmol/L to 10 µmol/L), but not an insulin receptor-blocking antibody, also prevented the stimulation of NADPH oxidase and the relaxation impairment elicited by visfatin. Accordingly, the product of Nampt activity nicotinamide mononucleotide (100 nmol/L to 1 mmol/L) stimulated endothelial NADPH oxidase activity and concentration-dependently impaired ACh-induced vasorelaxation. In human mesenteric microvessels pre-contracted with 35 mmol/L potassium chloride, the endothelium-dependent vasodilation to bradykinin (1 nmol/L to 3 µmol/L) was equally impaired by

  9. Visfatin impairs endothelium-dependent relaxation in rat and human mesenteric microvessels through nicotinamide phosphoribosyltransferase activity.

    Directory of Open Access Journals (Sweden)

    Susana Vallejo

    Full Text Available Visfatin, also known as extracellular pre-B-cell colony-enhancing factor (PBEF and nicotinamide phosphoribosyltransferase (Nampt, is an adipocytokine whose circulating levels are enhanced in metabolic disorders, such as type 2 diabetes mellitus and obesity. Circulating visfatin levels have been positively associated with vascular damage and endothelial dysfunction. Here, we investigated the ability of visfatin to directly impair vascular reactivity in mesenteric microvessels from both male Sprague-Dawley rats and patients undergoing non-urgent, non-septic abdominal surgery. The pre-incubation of rat microvessels with visfatin (50 and 100 ng/mL did not modify the contractile response to noradrenaline (1 pmol/L to 30 µmol/L, as determined using a small vessel myograph. However, visfatin (10 to 100 ng/mL concentration-dependently impaired the relaxation to acetylcholine (ACh; 100 pmol/L to 3 µmol/L, without interfering with the endothelium-independent relaxation to sodium nitroprusside (1 nmol/L to 3 µmol/L. In both cultured human umbilical vein endothelial cells and rat microvascular preparations, visfatin (50 ng/mL stimulated nicotinamide adenine dinucleotide phosphate (NADPH oxidase activity, as determined by lucigenin-derived chemiluminiscence. The relaxation to ACh impaired by visfatin was restored by the NADPH oxidase inhibitor apocynin (10 µmol/L. Additionally, the Nampt inhibitor APO866 (10 mmol/L to 10 µmol/L, but not an insulin receptor-blocking antibody, also prevented the stimulation of NADPH oxidase and the relaxation impairment elicited by visfatin. Accordingly, the product of Nampt activity nicotinamide mononucleotide (100 nmol/L to 1 mmol/L stimulated endothelial NADPH oxidase activity and concentration-dependently impaired ACh-induced vasorelaxation. In human mesenteric microvessels pre-contracted with 35 mmol/L potassium chloride, the endothelium-dependent vasodilation to bradykinin (1 nmol/L to 3 µmol/L was equally impaired

  10. Visfatin Impairs Endothelium-Dependent Relaxation in Rat and Human Mesenteric Microvessels through Nicotinamide Phosphoribosyltransferase Activity

    Science.gov (United States)

    Angulo, Javier; Villalobos, Laura A.; Cercas, Elena; Leivas, Alejandra; Bermejo, Elena; Carraro, Raffaele; Sánchez-Ferrer, Carlos F.; Peiró, Concepción

    2011-01-01

    Visfatin, also known as extracellular pre–B-cell colony–enhancing factor (PBEF) and nicotinamide phosphoribosyltransferase (Nampt), is an adipocytokine whose circulating levels are enhanced in metabolic disorders, such as type 2 diabetes mellitus and obesity. Circulating visfatin levels have been positively associated with vascular damage and endothelial dysfunction. Here, we investigated the ability of visfatin to directly impair vascular reactivity in mesenteric microvessels from both male Sprague-Dawley rats and patients undergoing non-urgent, non-septic abdominal surgery. The pre-incubation of rat microvessels with visfatin (50 and 100 ng/mL) did not modify the contractile response to noradrenaline (1 pmol/L to 30 µmol/L), as determined using a small vessel myograph. However, visfatin (10 to 100 ng/mL) concentration-dependently impaired the relaxation to acetylcholine (ACh; 100 pmol/L to 3 µmol/L), without interfering with the endothelium-independent relaxation to sodium nitroprusside (1 nmol/L to 3 µmol/L). In both cultured human umbilical vein endothelial cells and rat microvascular preparations, visfatin (50 ng/mL) stimulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, as determined by lucigenin-derived chemiluminiscence. The relaxation to ACh impaired by visfatin was restored by the NADPH oxidase inhibitor apocynin (10 µmol/L). Additionally, the Nampt inhibitor APO866 (10 mmol/L to 10 µmol/L), but not an insulin receptor-blocking antibody, also prevented the stimulation of NADPH oxidase and the relaxation impairment elicited by visfatin. Accordingly, the product of Nampt activity nicotinamide mononucleotide (100 nmol/L to 1 mmol/L) stimulated endothelial NADPH oxidase activity and concentration-dependently impaired ACh-induced vasorelaxation. In human mesenteric microvessels pre-contracted with 35 mmol/L potassium chloride, the endothelium-dependent vasodilation to bradykinin (1 nmol/L to 3 µmol/L) was equally impaired by

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

    Science.gov (United States)

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

    2013-12-01

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

  12. Mechanisms of aggregation inhibition by aspirin and nitrate-aspirin prodrugs in human platelets.

    Science.gov (United States)

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

    2012-01-01

    Aspirin is the mainstay of anti-platelet therapy in the secondary prevention of cardiovascular disease. However, problems with aspirin safety and resistance demand clinical strategies based on multiple pharmacological approaches. Prodrugs of aspirin may offer beneficial effects in terms of gastro-intestinal safety and multiple pharmacological approaches. However, the pharmacological profile of aspirin prodrugs in human platelets has not been completed yet. We aimed to compare the effects of aspirin and prodrugs of aspirin (1-5) on human platelet aggregation stimulated by ADP and collagen and associated receptor expression (GPIIb/IIIa and P-selectin) in platelet-rich plasma (PRP) and washed platelets (WP). As aspirin is released from prodrugs following esterase hydrolysis we studied the expression and activity of butyrylcholineterase (BuChE) and carboxyesterase (CE) in plasma and platelets. The mechanism of prodrug-induced platelet aggregation inhibition was explored by studying the effects of plasma and purified human BuChE on aggregation. Finally, the relative contribution of nitric oxide (NO) bioactivity to nitrate-containing prodrugs of aspirin-induced inhibition of aggregation was determined using 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ,) a selective inhibitor of the soluble guanylyl cyclase. ST0702, 2, a nicotinic acid-aspirin codrug was equipotent with aspirin with respect to inhibition of collagen-induced platelet aggregation. Compound 4, a NO releasing aspirin was the most potent inhibitor of ADP-induced platelet aggregation, an effect partially reversed by ODQ. The platelet inhibitory effects of aspirin prodrugs were time-dependent as the maximal inhibitory effects against collagen-induced aggregation were achieved by aspirin at 2 min, 1 at 5 min and ST0702 at 15 min. The aspirin prodrugs were significantly less potent in WP than in PRP and the reverse was true of aspirin. In the presence of complete BuChE inhibition in PRP, there was almost

  13. TRP channel Ca2+ sparklets: fundamental signals underlying endothelium-dependent hyperpolarization

    Science.gov (United States)

    Sullivan, Michelle N.

    2013-01-01

    Important functions of the vascular endothelium, including permeability, production of antithrombotic factors, and control of vascular tone, are regulated by changes in intracellular Ca2+. The molecular identities and regulation of Ca2+ influx channels in the endothelium are incompletely understood, in part because of experimental difficulties associated with application of patch-clamp electrophysiology to native endothelial cells. However, advances in confocal and total internal reflection fluorescence microscopy and the development of fast, high-affinity Ca2+-binding fluorophores have recently allowed for direct visualization and characterization of single-channel transient receptor potential (TRP) channel Ca2+ influx events in endothelial cells. These events, called “TRP channel Ca2+ sparklets,” have been optically recorded from primary endothelial cells and the intact endothelium, and the biophysical properties and fundamental significance of these Ca2+ signals in vasomotor regulation have been characterized. This review will first briefly discuss the role of endothelial cell TRP channel Ca2+ influx in endothelium-dependent vasodilation, describe improved methods for recording unitary TRP channel activity using optical methods, and highlight discoveries regarding the regulation and physiological significance of TRPV4 Ca2+ sparklets in the vascular endothelium enabled by this new technology. Perspectives on the potential use of these techniques to evaluate changes in TRP channel Ca2+ influx activity associated with endothelial dysfunction are offered. PMID:24025865

  14. Hypotensive effect and endothelium-dependent vascular action of leaves of Alpinia purpurata (Vieill K. Schum

    Directory of Open Access Journals (Sweden)

    Alessandra Tesch da Silva

    2014-04-01

    Full Text Available The aims of this study were to evaluate the chemical profile, vascular reactivity, and acute hypotensive effect (AHE of the ethanolic extract of leaves of Alpinia purpurata (Vieill K. Schum (EEAP. Its chemical profile was evaluated using HPLC-UV, ICP-OES, and colorimetric quantification of total flavonoids and polyphenols. The vascular reactivity of the extract was determined using the mesenteric bed isolated from WKY. AHE dose-response curves were obtained for both EEAP and inorganic material isolated from AP (IAP in WKY and SHR animals. Cytotoxic and mutagenic safety levels were determined by the micronucleus test. Rutin-like flavonoids were quantified in the EEAP (1.8 ± 0.03%, and the total flavonoid and polyphenol ratios were 4.1 ± 1.8% and 5.1 ± 0.3%, respectively. We observed that the vasodilation action of EEAP was partially mediated by nitric oxide (·NO. The IAP showed the presence of calcium (137.76 ± 4.08 μg mg-1. The EEAP and IAP showed an AHE in WKY and SHR animals. EEAP did not have cytotoxic effects or cause chromosomic alterations. The AHE shown by EEAP could result from its endothelium-dependent vascular action. Rutin-like flavonoids, among other polyphenols, could contribute to these biological activities, and the calcium present in EEAP could act in a synergistic way.

  15. Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

    Energy Technology Data Exchange (ETDEWEB)

    Burroughs, S.F.; Johnson, G.J. (Veterans Affairs Medical Center, Minneapolis, MN (USA))

    1990-04-01

    beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of (14C)-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with (3H)-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist (3H)-U46619 and antagonist (3H)-SQ29548, occurred. However, low-affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ((Ca2+)i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in (Ca2+)i. The loss of low-affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane.

  16. Sulforaphane prevents human platelet aggregation through inhibiting the phosphatidylinositol 3-kinase/Akt pathway.

    Science.gov (United States)

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

    2013-06-01

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

  17. ST-elevation acute coronary syndromes in the Platelet Inhibition and Patient Outcomes (PLATO) trial

    DEFF Research Database (Denmark)

    Armstrong, Paul W; Siha, Hany; Fu, Yuling

    2012-01-01

    Ticagrelor, when compared with clopidogrel, reduced the 12-month risk of vascular death/myocardial infarction and stroke in patients with ST-elevation acute coronary syndromes intended to undergo primary percutaneous coronary intervention in the PLATelet inhibition and patient Outcomes (PLATO...

  18. 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

  19. Endothelium-dependent relaxation and angiotensin II sensitivity in experimental preeclampsia.

    Directory of Open Access Journals (Sweden)

    Anne Marijn van der Graaf

    Full Text Available OBJECTIVE: We investigated endothelial dysfunction and the role of angiotensin (Ang-II type I (AT1-R and type II (AT2-R receptor in the changes in the Ang-II sensitivity in experimental preeclampsia in the rat. METHODS: Aortic rings were isolated from low dose lipopolysaccharide (LPS infused pregnant rats (experimental preeclampsia; n=9, saline-infused pregnant rats (n=8, and saline (n=8 and LPS (n=8 infused non-pregnant rats. Endothelium-dependent acetylcholine-mediated relaxation was studied in phenylephrine-preconstricted aortic rings in the presence of vehicle, N(G-nitro-L-arginine methyl ester and/or indomethacin. To evaluate the role for AT1-R and AT2-R in Ang-II sensitivity, full concentration response curves were obtained for Ang-II in the presence of losartan or PD123319. mRNA expression of the AT1-R and AT2-R, eNOS and iNOS, COX1 and COX2 in aorta were evaluated using real-time RT-PCR. RESULTS: The role of vasodilator prostaglandins in the aorta was increased and the role of endothelium-derived hyperpolarizing factor and response of the AT1-R and AT2-R to Ang-II was decreased in pregnant saline infused rats as compared with non-pregnant rats. These changes were not observed during preeclampsia. CONCLUSION: Pregnancy induced adaptations in endothelial function, which were not observed in the rat model for preeclampsia. This role of lack of pregnancy induced endothelial adaptation in the pathophysiology of experimental preeclampsia needs further investigation.

  20. Piperlongumine Blocks JAK2-STAT3 to Inhibit Collagen-Induced Platelet Reactivity Independent of Reactive Oxygen Species.

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    Hengjie Yuan

    Full Text Available Piperlongumine (PL is a compound isolated from the piper longum plant. It possesses anti-cancer activities through blocking the transcription factor STAT3 and by inducing reactive oxygen species (ROS in cancer, but not normal cells. It also inhibits platelet aggregation induced by collagen, but the underlying mechanism is not known.We conducted in vitro experiments to test the hypothesis that PL regulates a non-transcriptional activity of STAT3 to specifically reduce the reactivity of human platelets to collagen.PL dose-dependently blocked collagen-induced platelet aggregation, calcium influx, CD62p expression and thrombus formation on collagen with a maximal inhibition at 100 μM. It reduced platelet microvesiculation induced by collagen. PL blocked the activation of JAK2 and STAT3 in collagen-stimulated platelets. This inhibitory effect was significantly reduced in platelets pretreated with a STAT3 inhibitor. Although PL induced ROS production in platelets; quenching ROS using excessive reducing agents: 20 μM GSH and 0.5 mM L-Cysteine, did not block the inhibitory effects. The NADPH oxidase inhibitor Apocynin also had no effect.PL inhibited collagen-induced platelet reactivity by targeting the JAK2-STAT3 pathway. We also provide experimental evidence that PL and collagen induce different oxidants that have differential effects on platelets. Studying these differential effects may uncover new mechanisms of regulating platelet functions by oxidants in redox signals.

  1. Effects of yoga interventions practiced in heated and thermoneutral conditions on endothelium-dependent vasodilation: The Bikram yoga heart study.

    Science.gov (United States)

    Hunter, Stacy D; Laosiripisan, Jitanan; Elmenshawy, Ahmed; Tanaka, Hirofumi

    2018-01-18

    We have previously documented improvements in endothelium-dependent vasodilation with a Bikram (hot) yoga intervention in middle-aged adults. Presently, the effect of environmental temperature in hot yoga on endothelial function is unknown. The purpose of this investigation was to determine the effects of Bikram yoga interventions performed in the heated and thermoneutral conditions on endothelium-dependent vasodilation. Fifty-two sedentary but apparently healthy adults aged 40-60 years were randomly assigned to one of three groups: Bikram yoga practiced at 40.5°C (n = 19), Bikram yoga practiced at 23°C (n = 14), or sedentary time-control (n = 19). The yoga interventions consisted of 90-minute Bikram yoga classes 3 times a week for 12 weeks. Endothelium-dependent vasodilation was measured noninvasively using brachial artery flow-mediated dilation (FMD). Body fat percentage determined via dual energy x-ray absorptiometry was significantly lower in the hot yoga group after the intervention than in the thermoneutral yoga and control conditions. Brachial artery FMD increased (P yoga group and tended to increase in the hot yoga group (P = 0.056). No changes occurred in the control group. There were no significant differences in FMD change scores between groups. Bikram yoga practiced in thermoneutral conditions improved endothelium-dependent vasodilation in healthy, middle-aged adults. These novels findings highlight the effectiveness of hatha yoga postures alone, in the absence of a heated practice environment, in improving vascular health and are of clinical significance given the increased propensity toward heat intolerance in aging adults. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Pomegranate Extract Enhances Endothelium-Dependent Coronary Relaxation in Isolated Perfused Hearts from Spontaneously Hypertensive Ovariectomized Rats

    Science.gov (United States)

    Delgado, Nathalie T. B.; Rouver, Wender do N.; Freitas-Lima, Leandro C.; de Paula, Tiago D.-C.; Duarte, Andressa; Silva, Josiane F.; Lemos, Virgínia S.; Santos, Alexandre M. C.; Mauad, Helder; Santos, Roger L.; Moysés, Margareth R.

    2017-01-01

    prevented the decreasing in plasmatic nitrite. We observed a reduction in total cholesterol and LDL in the Sham-PHE group. The treatment with PHE enhances the endothelium-dependent coronary relaxation and improves cardiovascular parameters, which suggests a therapeutic role of PHE. PMID:28101057

  3. Chronic in vivo or acute in vitro resveratrol attenuates endothelium-dependent cyclooxygenase-mediated contractile signaling in hypertensive rat carotid artery

    Science.gov (United States)

    Denniss, Steven G.; Ford, Rebecca J.; Smith, Christopher S.; Jeffery, Andrew J.

    2016-01-01

    Exaggerated cyclooxygenase (COX) and thromboxane-prostanoid (TP) receptor-mediated endothelium-dependent contraction can contribute to endothelial dysfunction. This study examined the effect of resveratrol (RSV) on endothelium-dependent contraction and cell signaling in the common carotid artery (CCA) from spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Acetylcholine (Ach)-stimulated endothelium-dependent nitric oxide synthase (NOS)-mediated relaxation in precontracted SHR CCA was impaired (maximum 73 ± 6% vs. 87 ± 5% in WKY) (P endothelium-dependent relaxation nor endothelium-dependent contraction and associated prostaglandin (PG) production evaluated in non-precontracted NOS-blocked CCA. In contrast, a chronic ∼7.5 mg·kg−1·day−1 RSV dose improved endothelium-dependent relaxation (94 ± 6%) and attenuated endothelium-dependent contraction (58 ± 4% vs. 73 ± 5% in No-RSV) and PG production (183 ± 43 vs. 519 ± 93 pg/ml) in SHR CCA, while U46619-stimulated TP receptor-mediated contraction was unaffected. In separate acute in vitro experiments, 20-μM RSV preincubation attenuated endothelium-dependent contraction (6 ± 4% vs. 62 ± 2% in No Drug) and PG production (121 ± 15 vs. 491 ± 93 pg/ml) and attenuated U46619-stimulated contraction (134 ± 5% vs. 171 ± 4%) in non-precontracted NOS-blocked SHR CCA. Compound C, a known AMP-activated protein kinase (AMPK) inhibitor, did not prevent the RSV attenuating effect on Ach- and U46619-stimulated contraction but did prevent the RSV attenuating effect on PG production (414 ± 58 pg/ml). These data demonstrate that RSV can attenuate endothelium-dependent contraction both by suppressing arterial wall PG production, which may be partially mediated by AMPK, and by TP receptor hyporesponsiveness, which does not appear to be mediated by AMPK. PMID:26917696

  4. Mechanism study of endothelial protection and inhibits platelet activation of low molecular weight fucoidan from Laminaria japonica

    Science.gov (United States)

    Chen, Anjin; Zhang, Fang; Shi, Jie; Zhao, Xue; Yan, Meixing

    2016-10-01

    Several studies have indicated that fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica could inhibit the activation of platelets directly by reducing the platelet aggregation. To explore the direct effect of LMW fucoidan on the platelet system furthermore and examine the possible mechanism, the endothelial protection and inhibits platelet activation effects of two LMW fucoidan were investigated. In the present study, Endothelial injury model of rats was made by injection of adrenaline (0.4 mg kg-1) and human umbilical vein endothelial cells were cultured. vWF level was be investigated in vivo and in vitro as an important index of endothelial injury. LMW fucoidan could significantly reduce vWF level in vascular endothelial injury rats and also significantly reduce vWF level in vitro. The number of EMPs was be detected as another important index of endothelial injury. The results showed that LMW fucoidan reduced EMPs stimulated by tumor necrosis factor. In this study, it was found that by inhibiting platelet adhesion, LMW fucoidan played a role in anti-thrombosis and the specific mechanism of action is to inhibit the flow of extracellular Ca2+. All in a word, LMW fucoidan could inhibit the activation of platelets indirectly by reducing the concentration of EMPs and vWF, at the same time; LMW fucoidan inhibited the activation of platelets directly by inhibiting the flow of extracellular Ca2+.

  5. Nitric oxide, cholesterol oxides and endothelium-dependent vasodilation in plasma of patients with essential hypertension

    Directory of Open Access Journals (Sweden)

    P. Moriel

    2002-11-01

    Full Text Available The objective of the present study was to identify disturbances of nitric oxide radical (·NO metabolism and the formation of cholesterol oxidation products in human essential hypertension. The concentrations of·NO derivatives (nitrite, nitrate, S-nitrosothiols and nitrotyrosine, water and lipid-soluble antioxidants and cholesterol oxides were measured in plasma of 11 patients with mild essential hypertension (H: 57.8 ± 9.7 years; blood pressure, 148.3 ± 24.8/90.8 ± 10.2 mmHg and in 11 healthy subjects (N: 48.4 ± 7.0 years; blood pressure, 119.4 ± 9.4/75.0 ± 8.0 mmHg.Nitrite, nitrate and S-nitrosothiols were measured by chemiluminescence and nitrotyrosine was determined by ELISA. Antioxidants were determined by reverse-phase HPLC and cholesterol oxides by gas chromatography. Hypertensive patients had reduced endothelium-dependent vasodilation in response to reactive hyperemia (H: 9.3 and N: 15.1% increase of diameter 90 s after hyperemia, and lower levels of ascorbate (H: 29.2 ± 26.0, N: 54.2 ± 24.9 µM, urate (H: 108.5 ± 18.9, N: 156.4 ± 26.3 µM, ß-carotene (H: 1.1 ± 0.8, N: 2.5 ± 1.2 nmol/mg cholesterol, and lycopene (H: 0.4 ± 0.2, N: 0.7 ± 0.2 nmol/mg cholesterol, in plasma, compared to normotensive subjects. The content of 7-ketocholesterol, 5alpha-cholestane-3ß,5,6ß-triol and 5,6alpha-epoxy-5alpha-cholestan-3alpha-ol in LDL, and the concentration of endothelin-1 (H: 0.9 ± 0.2, N: 0.7 ± 0.1 ng/ml in plasma were increased in hypertensive patients. No differences were found for ·NO derivatives between groups. These data suggest that an increase in cholesterol oxidation is associated with endothelium dysfunction in essential hypertension and oxidative stress, although ·NO metabolite levels in plasma are not modified in the presence of elevated cholesterol oxides.

  6. KCa 3.1 upregulation preserves endothelium-dependent vasorelaxation during aging and oxidative stress.

    Science.gov (United States)

    Choi, Shinkyu; Kim, Ji Aee; Li, Hai-Yan; Shin, Kyong-Oh; Oh, Goo Taeg; Lee, Yong-Moon; Oh, Seikwan; Pewzner-Jung, Yael; Futerman, Anthony H; Suh, Suk Hyo

    2016-10-01

    Endothelial oxidative stress develops with aging and reactive oxygen species impair endothelium-dependent relaxation (EDR) by decreasing nitric oxide (NO) availability. Endothelial KCa 3.1, which contributes to EDR, is upregulated by H2 O2 . We investigated whether KCa 3.1 upregulation compensates for diminished EDR to NO during aging-related oxidative stress. Previous studies identified that the levels of ceramide synthase 5 (CerS5), sphingosine, and sphingosine 1-phosphate were increased in aged wild-type and CerS2 mice. In primary mouse aortic endothelial cells (MAECs) from aged wild-type and CerS2 null mice, superoxide dismutase (SOD) was upregulated, and catalase and glutathione peroxidase 1 (GPX1) were downregulated, when compared to MAECs from young and age-matched wild-type mice. Increased H2 O2 levels induced Fyn and extracellular signal-regulated kinases (ERKs) phosphorylation and KCa 3.1 upregulation. Catalase/GPX1 double knockout (catalase(-/-) /GPX1(-/-) ) upregulated KCa 3.1 in MAECs. NO production was decreased in aged wild-type, CerS2 null, and catalase(-/-) /GPX1(-/-) MAECs. However, KCa 3.1 activation-induced, N(G) -nitro-l-arginine-, and indomethacin-resistant EDR was increased without a change in acetylcholine-induced EDR in aortic rings from aged wild-type, CerS2 null, and catalase(-/-) /GPX1(-/-) mice. CerS5 transfection or exogenous application of sphingosine or sphingosine 1-phosphate induced similar changes in levels of the antioxidant enzymes and upregulated KCa 3.1. Our findings suggest that, during aging-related oxidative stress, SOD upregulation and downregulation of catalase and GPX1, which occur upon altering the sphingolipid composition or acyl chain length, generate H2 O2 and thereby upregulate KCa 3.1 expression and function via a H2 O2 /Fyn-mediated pathway. Altogether, enhanced KCa 3.1 activity may compensate for decreased NO signaling during vascular aging. © 2016 The Authors. Aging Cell published by the Anatomical Society and

  7. A New Platelet-Aggregation-Inhibiting Factor Isolated from Bothrops moojeni Snake Venom

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    Bruna Barbosa de Sousa

    2017-01-01

    Full Text Available This work reports the purification and functional characterization of BmooPAi, a platelet-aggregation-inhibiting factor from Bothrops moojeni snake venom. The toxin was purified by a combination of three chromatographic steps (ion-exchange on DEAE-Sephacel, molecular exclusion on Sephadex G-75, and affinity chromatography on HiTrap™ Heparin HP. BmooPAi was found to be a single-chain protein with an apparent molecular mass of 32 kDa on 14% SDS-PAGE, under reducing conditions. Sequencing of BmooPAi by Edman degradation revealed the amino acid sequence LGPDIVPPNELLEVM. The toxin was devoid of proteolytic, haemorrhagic, defibrinating, or coagulant activities and induced no significant oedema or hyperalgesia. BmooPAi showed a rather specific inhibitory effect on ristocetin-induced platelet aggregation in human platelet-rich plasma, whereas it had little or no effect on platelet aggregation induced by collagen and adenosine diphosphate. The results presented in this work suggest that BmooPAi is a toxin comprised of disintegrin-like and cysteine-rich domains, originating from autolysis/proteolysis of PIII SVMPs from B. moojeni snake venom. This toxin may be of medical interest because it is a platelet aggregation inhibitor, which could potentially be developed as a novel therapeutic agent to prevent and/or treat patients with thrombotic disorders.

  8. Mutant botrocetin-2 inhibits von Willebrand factor-induced platelet agglutination.

    Science.gov (United States)

    Matsui, T; Hori, A; Hamako, J; Matsushita, F; Ozeki, Y; Sakurai, Y; Hayakawa, M; Matsumoto, M; Fujimura, Y

    2017-03-01

    Essentials Botrocetin-2 (Bot2) binds to von Willebrand factor (VWF) and induces platelet agglutination. We identified Bot2 residues that are required for binding to VWF and glycoprotein (GP) Ib. We produced a mutant Bot2 that binds to VWF but inhibits platelet agglutination. Mutant Bot2 could be used as a potential anti-thrombotic reagent to block VWF-GPIb interaction. Background Botrocetin-2 (Bot2) is a botrocetin-like protein composed of α and β subunits that have been cloned from the snake Bothrops jararaca. Bot2 binds specifically to von Willebrand factor (VWF), and the complex induces glycoprotein (GP) Ib-dependent platelet agglutination. Objectives To exploit Bot2's VWF-binding capacity in order to attempt to create a mutant Bot2 that binds to VWF but inhibits platelet agglutination. Methods and Results Several point mutations were introduced into Bot2 cDNA, and the recombinant protein (recombinant Bot2 [rBot2]) was purified on an anti-botrocetin column. The mutant rBot2 with either Ala at Asp70 in the β subunit (Aspβ70Ala), or Argβ115Ala and Lysβ117Ala, showed reduced platelet agglutination-inducing activity. rBot2 with Aspβ70Ala showed little binding activity towards immobilized VWF on an ELISA plate, whereas rBot2 with Argβ115Ala/Lysβ117Ala showed reduced binding activity towards GPIb (glycocalicin) after forming a complex with VWF. rBot2 point-mutated to oppositely charged Glu at both Argβ115 and Lysβ117 showed normal binding activity towards VWF but no platelet-agglutinating activity. Furthermore, this doubly mutated protein inhibited ristocetin-induced or high shear stress-induced platelet aggregation, and restrained thrombus formation under flow conditions. Conclusions Asp70 in the β subunit of botrocetin is important for VWF binding, and Arg115 and Lys117 in the β subunit are essential for interaction with GPIb. Doubly mutated rBot2, with Argβ115Glu and Lysβ117Glu, repels GPIb and might have potential as an antithrombotic reagent that

  9. Endothelium-derived hyperpolarizing factor (EDHF) mediates endothelium-dependent vasodilator effects of aqueous extracts from Eucommia ulmoides Oliv. leaves in rat mesenteric resistance arteries.

    Science.gov (United States)

    Jin, Xin; Otonashi-Satoh, Yukiko; Sun, Pengyuan; Kawamura, Naomi; Tsuboi, Takashi; Yamaguchi, Yasuyo; Ueda, Taro; Kawasaki, Hiromu

    2008-10-01

    The vascular effects of an aqueous extract prepared from the leaves of Eucommia ulmoides Oliv. (ELE), a medicinal herb commonly used in antihypertensive herbal prescriptions in China, were investigated in rat mesenteric resistance arteries. The mesenteric vascular bed was perfused with Krebs solution and the perfusion pressure was measured with a pressure transducer. In preparations with an intact endothelium and precontracted with 7 microM methoxamine, perfusion of ELE (107102 mg/ml for 15 min) caused a concentration-dependent vasodilatation, which was abolished by chemical removal of the endothelium. The ELE-induced vasodilatation was inhibited by neither indomethacin (INDO, a cyclooxygenase inhibitor) nor NG-nitro-L-arginine-methyl ester (L-NAME, a nitric oxide inhibitor). The ELE-induced vasodilatation was significantly inhibited by tetraethylammonium (TEA, a K channel blocker) and 18alpha-glycyrrhetinic acid (18alpha-GA, a gap-junction inhibitor), and abolished by high K-containing Krebs' solution. Atropine (a muscarinic acetylcholine receptor antagonist) significantly inhibited the vasodilatation induced by ELE at high concentrations. These results suggest that the ELE-induced vasodilatation is endothelium-dependent but nitric oxide (NO)- and prostaglandin I2 (PGI2)-independent, and is mainly mediated by the endothelium-derived hyperpolarizing factor (EDHF) in the mesenteric resistance arteries. Furthermore, the ELE-induced EDHF-mediated response involves the activation of K-channels and gap junctions.

  10. Metamizole and Platelet Inhibition by Aspirin Following On-Pump Coronary Artery Bypass Grafting.

    Science.gov (United States)

    Wilczyński, Mirosław; Wybraniec, Maciej T; Sanak, Marek; Góral, Joanna; Mizia-Stec, Katarzyna

    2017-06-07

    The purpose of the study was to evaluate the impact of intravenous metamizole on platelet inhibition by aspirin in patients with coronary artery disease early after on-pump coronary artery bypass grafting (CABG). Prospective, single-blind, randomized trial. Tertiary referal hospital. The study comprised 43 patients with multivessel coronary artery disease undergoing CABG. Patients were randomized to postoperative intravenous metamizole ± opioids (study group; n = 23) or opioids alone (control group; n = 20). Aspirin was withheld at least 7 days before the surgery and reinitiated (300 mg) immediately after the procedure prior to metamizole use, and continued daily thereafter (150 mg). Platelet function was evaluated using multielectrode impedance aggregometry (acid-induced platelet activation [ASPI] and collagen-induced platelet activation [COL] test), P-selectin expression and urinary 11-dehydro-thromboxane B2 (11-DTXB2) level at baseline, postoperative day (POD) 0, POD 1, POD 2, and POD 6. Residual platelet reactivity (RPR) was defined as ASPI test >400 AU*min. In all study participants, postoperative ASPI test value moderately decreased (1058.2 v 966.6 AU*min, p = 0.047), urinary 11-DTXB2 level increased (923.4 v 4367.3 pg/mg, p metamizole use did not predict the fluctuations of ASPI and COL test values and P-selectin expression, yet it independently predicted postoperative change of 11-DTXB2 level (b = -0.518, p = 0.001). Intravenous metamizole preceded by a loading dose of aspirin did not modify platelet response to aspirin in the postoperative period after CABG. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Peng Jiang

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

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

    Science.gov (United States)

    Jiang, Peng; Loyau, Stéphane; Tchitchinadze, Maria; Ropers, Jacques; Jondeau, Guillaume; Jandrot-Perrus, Martine

    2015-01-01

    Exposure of platelets to collagen triggers the formation of a platelet clot. Pharmacological agents capable of inhibiting platelet activation by collagen are thus of potential therapeutic interest. Thrombus formation is initiated by the interaction of the GPIb-V-IX complex with collagen-bound vWF, while GPVI interaction with collagen triggers platelet activation that is reinforced by ADP and thromboxane A2. Losartan is an angiotensin II (Ang II) type I receptor (AT1R) antagonist proposed to have an antiplatelet activity via the inhibition of both the thromboxane A2 (TXA2) receptor (TP) and the glycoprotein VI (GPVI). Here, we characterized in vitro the effects of losartan at different doses on platelet responses: losartan inhibited platelet aggregation and secretion induced by 1 μg.mL-1 and 10 μg.mL-1 of collagen with an IC50 of ~ 6 μM. Losartan inhibited platelet responses induced by the GPVI specific collagen related peptide but not by the α2β1 specific peptide. However, losartan did not inhibit the binding of recombinant GPVI to collagen, which is not in favor of a simple competition. Indeed, the clustering of GPVI observed in flow cytometry and using the Duolink methodology, was inhibited by losartan. The impact of a therapeutic dose of losartan (100 mg/day) on platelet responses was analyzed ex vivo in a double blind study. No statistically significant differences were observed between losartan-treated (n=25) and non-treated (n=30) patients in terms of collagen and U46619-induced platelet activation. These data indicate that in treated patients, losartan does not achieve a measurable antiplatelet effect but provide the proof of concept that inhibiting collagen-induced GPVI clustering is of pharmacological interest to obtain an antithrombotic efficacy. Trial Registration ClinicalTrials.gov NCT00763893 PMID:26052700

  13. Inhibition of platelet aggregability by moderate-intensity physical exercise: a randomized clinical trial in overweight men.

    Science.gov (United States)

    Rauramaa, R; Salonen, J T; Seppänen, K; Salonen, R; Venäläinen, J M; Ihanainen, M; Rissanen, V

    1986-11-01

    It has been postulated that platelet function plays an important role in the initiation of atherosclerosis. Currently there are no definitive data on the longer-term effects of regular physical exercise on platelet function in humans. We assessed the influence of regular moderate-intensity physical exercise (brisk walking to slow jogging) on platelet aggregation in a population-based sample of middle-aged, overweight, mildly hypertensive men in eastern Finland. In this controlled study, we evaluated the net effect of exercise on platelet aggregation by studying changes in optical density and ATP release in platelet-rich plasma. A significant inhibition of secondary platelet aggregation from 27% to 36% was observed in the men taking regular exercise. These findings give new insight into the possible protective effects of exercise against the risk of ischemic heart disease.

  14. Platelets Contain Tissue Factor Pathway Inhibitor-2 Derived from Megakaryocytes and Inhibits Fibrinolysis*

    Science.gov (United States)

    Vadivel, Kanagasabai; Ponnuraj, Sathya-Moorthy; Kumar, Yogesh; Zaiss, Anne K.; Bunce, Matthew W.; Camire, Rodney M.; Wu, Ling; Evseenko, Denis; Herschman, Harvey R.; Bajaj, Madhu S.; Bajaj, S. Paul

    2014-01-01

    Tissue factor pathway inhibitor-2 (TFPI-2) is a homologue of TFPI-1 and contains three Kunitz-type domains and a basic C terminus region. The N-terminal domain of TFPI-2 is the only inhibitory domain, and it inhibits plasma kallikrein, factor XIa, and plasmin. However, plasma TFPI-2 levels are negligible (≤20 pm) in the context of influencing clotting or fibrinolysis. Here, we report that platelets contain significant amounts of TFPI-2 derived from megakaryocytes. We employed RT-PCR, Western blotting, immunohistochemistry, and confocal microscopy to determine that platelets, MEG-01 megakaryoblastic cells, and bone marrow megakaryocytes contain TFPI-2. ELISA data reveal that TFPI-2 binds factor V (FV) and partially B-domain-deleted FV (FV-1033) with Kd ∼9 nm and binds FVa with Kd ∼100 nm. Steady state analysis of surface plasmon resonance data reveal that TFPI-2 and TFPI-1 bind FV-1033 with Kd ∼36–48 nm and bind FVa with Kd ∼252–456 nm. Further, TFPI-1 (but not TFPI-1161) competes with TFPI-2 in binding to FV. These data indicate that the C-terminal basic region of TFPI-2 is similar to that of TFPI-1 and plays a role in binding to the FV B-domain acidic region. Using pull-down assays and Western blots, we show that TFPI-2 is associated with platelet FV/FVa. TFPI-2 (∼7 nm) in plasma of women at the onset of labor is also, in part, associated with FV. Importantly, TFPI-2 in platelets and in plasma of pregnant women inhibits FXIa and tissue-type plasminogen activator-induced clot fibrinolysis. In conclusion, TFPI-2 in platelets from normal or pregnant subjects and in plasma from pregnant women binds FV/Va and regulates intrinsic coagulation and fibrinolysis. PMID:25262870

  15. The ent-15α-Acetoxykaur-16-en-19-oic Acid Relaxes Rat Artery Mesenteric Superior via Endothelium-Dependent and Endothelium-Independent Mechanisms

    Directory of Open Access Journals (Sweden)

    Êurica Adélia Nogueira Ribeiro

    2012-01-01

    Full Text Available The objective of the study was to investigate the mechanism of the relaxant activity of the ent-15α-acetoxykaur-16-en-19-oic acid (KA-acetoxy. In rat mesenteric artery rings, KA-acetoxy induced a concentration-dependent relaxation in vessels precontracted with phenylephrine. In the absence of endothelium, the vasorelaxation was significantly shifted to the right without reduction of the maximum effect. Endothelium-dependent relaxation was significantly attenuated by pretreatment with L-NAME, an inhibitor of the NO-synthase (NOS, indomethacin, an inhibitor of the cyclooxygenase, L-NAME + indomethacin, atropine, a nonselective antagonist of the muscarinic receptors, ODQ, selective inhibitor of the guanylyl cyclase enzyme, or hydroxocobalamin, a nitric oxide scavenger. The relaxation was completely reversed in the presence of L-NAME + 1 mM L-arginine or L-arginine, an NO precursor. Diterpene-induced relaxation was not affected by TEA, a nonselective inhibitor of K+ channels. The KA-acetoxy antagonized CaCl2-induced contractions in a concentration-dependent manner and also inhibited an 80 mM KCl-induced contraction. The KA-acetoxy did not interfere with Ca2+ release from intracellular stores. The vasorelaxant induced by KA-acetoxy seems to involve the inhibition of the Ca2+ influx and also, at least in part, by endothelial muscarinic receptors activation, NO and PGI2 release.

  16. [Significance of heterogenity in endothelium-dependent vasodilatation occurrence in healthy individuals with or without coronary risk factors].

    Science.gov (United States)

    Polovina, Marija; Potpara, Tatjana; Giga, Vojislav; Ostojić, Miodrag

    2009-10-01

    Brachial artery flow-mediated dilation (FMD) is extensively used for non-invasive assessment of endothelial function. Traditionally, FMD is calculated as a percent change of arterial diameter from the baseline value at an arbitrary time point after cuff deflation (usually 60 seconds). Considerable individual differences in brachial artery temporal response to hyperemic stimulus have been observed, potentially influenced by the presence of atherosclerotic risk factors (RF). The importance of such differences for the evaluation of endothelial function has not been well established. The aim of the study was to determine the time course of maximal brachial artery endothelium-dependent dilation in healthy adults with and without RF, to explore the correlation of RF with brachial artery temporal response and to evaluate the importance of individual differences in temporal response for the assessment of endothelial function. A total of 115 healthy volunteers were included in the study. Out of them, 58 had no RF (26 men, mean age 44 +/-14 years) and 57 had at least one RF (29 men, mean age 45 +/-14 years). High-resolution color Doppler vascular ultrasound was used for brachial artery imaging. To determine maximal arterial diameter after cuff deflation and the time-point of maximal vasodilation off-line sequential measurements were performed every 10 seconds from 0 to 240 seconds after cuff release. True maximal FMD value was calculated as a percent change of the true maximal diameter from the baseline, and compared with FMD value calculated assuming that every participant reached maximal dilation at 60 seconds post cuff deflation (FMD60). Correlation of different RF with brachial artery temporal response was assessed. A maximal brachial artery endothelium-dependent vasodilation occurred from 30-120 seconds after cuff release, and the mean time of endothelium-dependent dilation was 68 +/-20 seconds. Individuals without RF had faster endothelium-dependent dilation (mean time

  17. Chewing versus Swallowing Ticagrelor to Accelerate Platelet Inhibition in Acute Coronary Syndrome - the CHEERS study. For The PLATIS (Platelets and Thrombosis in Sheba) Study Group.

    Science.gov (United States)

    Asher, Elad; Frydman, Shir; Katz, Moshe; Regev, Ehud; Sabbag, Avi; Mazin, Israel; Abu-Much, Arsalan; Kukuy, Andrew; Mazo, Anna; Erez, Aharon; Berkovitch, Anat; Narodistky, Michael; Barbash, Israel; Segev, Amit; Beigel, Roy; Matetzky, Shlomi

    2017-04-03

    It was the study objective to evaluate whether chewing a 180 mg loading dose of ticagrelor versus an equal dose of traditional oral administration, enhances inhibition of platelet aggregation 1 hour (h) after administering a ticagrelor loading dose in non-ST elevation myocardial infarction (NSTEMI) patients. Dual anti-platelet therapy represents standard care for treating NSTEMI patients. Ticagrelor is a direct acting P2Y12 inhibitor and, unlike clopidogrel and prasugrel, does not require metabolic activation. Fifty NSTEMI patients were randomised to receive either a chewing loading dose of 180 mg ticagrelor or an equal standard oral dose of ticagrelor. Platelet reactivity was evaluated by VerifyNow at baseline, 1 and 4 h post-loading dose. Results are reported in P2Y12 reaction units. Patients then continued to receive standard 90 mg oral ticagrelor twice daily. Baseline characteristics did not differ between the two groups. P2Y12 reaction units in the chewing group compared with the standard group at 0, 1 and 4 h after ticagrelor loading dose were: 245 vs 239 (p=0.59), 45 vs 130 (p=0.001) and 39 vs 60 (p=0.12), respectively, corresponding to a relative inhibition of platelet aggregation of 83 % vs only 47 % at 1 h (pticagrelor loading dose is feasible and facilitates both faster and improved early inhibition of platelet aggregation in NSTEMI patients, compared with a standard oral-loading dose.

  18. Sex differences in the role of transient receptor potential (TRP) channels in endothelium-dependent vasorelaxation in porcine isolated coronary arteries.

    Science.gov (United States)

    Wong, Pui San; Roberts, Richard E; Randall, Michael D

    2015-03-05

    Endothelial and smooth muscle Transient Receptor Potential (TRP) channels contribute to regulation of vascular tone. We have previously reported sex differences in the endothelial function in porcine isolated coronary arteries (PCAs). The present study examined the role of TRP channels in endothelium-dependent and H2O2-induced vasorelaxations in male and female PCAs. Distal PCAs were mounted in a wire myograph and precontracted with U46619. Concentration-response curves to bradykinin, H2O2 and A23187 were constructed in the presence of TRP channel antagonists with or without L-NAME and indomethacin to inhibit NO synthase and cyclooxygenase respectively. 2-APB (TRPC & TRPM antagonist) inhibited the maximum relaxation (Rmax) of the bradykinin-induced vasorelaxation and abolished the EDH-type response in PCAs from both sexes. SKF96365 (TRPC antagonist) inhibited the Rmax of bradykinin-induced vasorelaxation in males, and inhibited Rmax of the EDH-type response in both sexes. Pyr3 (TRPC3 antagonist) inhibited both the NO and EDH components of the bradykinin-induced vasorelaxation in males, but not females. RN1734 (TRPV4 antagonist) reduced the potency of the NO component of the bradykinin-induced vasorelaxation in females only, but inhibited the Rmax of the EDH-type component in both sexes. 2-APB, SKF96365 and RN1734 all reduced the H2O2-induced vasorelaxation, whereas Pyr3 had no effect. No differences in expression level of TRPC3 and TRPV4 between sexes were detected using Western blot. Present study demonstrated a clear sex differences in the role TRP channels where TRPC3 play a role in the NO- and EDH-type response in males and TRPV4 play a role in the NO-mediated response in females. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Hormonal therapy with estradiol and drospirenone improves endothelium-dependent vasodilation in the coronary bed of ovariectomized spontaneously hypertensive rats

    Energy Technology Data Exchange (ETDEWEB)

    Borgo, M.V.; Claudio, E.R.G.; Silva, F.B.; Romero, W.G.; Gouvea, S.A.; Moysés, M.R.; Santos, R.L.; Almeida, S.A. [Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal de Espírito Santo, Vitória, ES (Brazil); Podratz, P.L.; Graceli, J.B. [Departamento de Morfologia, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES (Brazil); Abreu, G.R. [Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal de Espírito Santo, Vitória, ES (Brazil)

    2015-11-17

    Drospirenone (DRSP) is a progestin with anti-aldosterone properties and it reduces blood pressure in hypertensive women. However, the effects of DRSP on endothelium-dependent coronary vasodilation have not been evaluated. This study investigated the effects of combined therapy with estrogen (E2) and DRSP on endothelium-dependent vasodilation of the coronary bed of ovariectomized (OVX) spontaneously hypertensive rats. Female spontaneously hypertensive rats (n=87) at 12 weeks of age were randomly divided into sham operated (Sham), OVX, OVX treated with E2 (E2), and OVX treated with E2 and DRSP (E2+DRSP) groups. Hemodynamic parameters were directly evaluated by catheter insertion into the femoral artery. Endothelium-dependent vasodilation in response to bradykinin in the coronary arterial bed was assessed using isolated hearts according to a modified Langendorff method. Coronary protein expression of endothelial nitric oxide synthase and estrogen receptor alpha (ER-α) was assessed by Western blotting. Histological slices of coronary arteries were stained with hematoxylin and eosin, and morphometric parameters were analyzed. Oxidative stress was assessed in situ by dihydroethidium fluorescence. Ovariectomy increased systolic blood pressure, which was only prevented by E2+DRSP treatment. Estrogen deficiency caused endothelial dysfunction, which was prevented by both treatments. However, the vasodilator response in the E2+DRSP group was significantly higher at the three highest concentrations compared with the OVX group. Reduced ER-α expression in OVX rats was restored by both treatments. Morphometric parameters and oxidative stress were augmented by OVX and reduced by E2 and E2+DRSP treatments. Hormonal therapy with E2 and DRSP may be an important therapeutic option in the prevention of coronary heart disease in hypertensive post-menopausal women.

  20. Delayed inhibition of agonist-induced granulocyte-platelet aggregation after low-dose sevoflurane inhalation in humans.

    Science.gov (United States)

    Wacker, Johannes; Lucchinetti, Eliana; Jamnicki, Marina; Aguirre, José; Härter, Luc; Keel, Marius; Zaugg, Michael

    2008-06-01

    Sevoflurane can be used as sedative-analgesic drug with endothelial protective properties. We tested whether low-dose sevoflurane inhalation provides sustained inhibition of detrimental granulocyte-platelet aggregation in humans. Ten healthy male volunteers were enrolled in this crossover study. Each subject inhaled sevoflurane for 1 h at 0.5-1 vol % end-tidal concentration in oxygen (50 vol %). Inhaling oxygen (50 vol %) alone served as control. Venous blood samples were collected at baseline before inhalation, immediately after inhalation, and 24 h thereafter, and were used for flow cytometry to determine platelet surface marker (CD41, CD42b, CD62P/P-selectin, and PAC-1) on platelets and granulocytes and for kaolin-induced clot formation, as assessed by thromboelastography. In flow cytometry experiments, platelets were stimulated with arachidonic acid (AA, 30 microM), adenosine diphosphate (ADP, 1 microM), and thrombin receptor agonist peptide-6 (TRAP-6, 6 microM). AA, ADP, and TRAP-6 markedly increased the expression of CD62P on platelets, whereas CD42b (shedding) and PAC-1 (heterotypic conjugates) expression decreased. The amount of granulocyte-platelet aggregates increased upon agonist stimulation. Low-dose sevoflurane inhalation reduced ADP-induced CD62P expression on platelets 24 h after inhalation, and inhibited the formation of granulocyte-platelet aggregates under stimulation with AA and ADP after 1 and 24 h, and with TRAP-6 after 24 h compared with control. Inhibition of granulocyte-platelet aggregates was accompanied by reduced clot firmness 24 h after sevoflurane inhalation compared with control. We demonstrated for the first time that inhaling low-dose sevoflurane (<1 vol % end-tidal) inhibits agonist-induced granulocyte-platelet interactions 24 h after administration and thus counteracts thromboinflammatory processes.

  1. 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

  2. Improvement of Endothelium-Dependent Relaxation in Aorta of Rat Models Type 1 and 2 Diabetes by Hespiridin

    Directory of Open Access Journals (Sweden)

    H Mirkhani,

    2008-07-01

    Full Text Available Background: Vascular disease is the principal cause of morbidity and mortality in patients with diabetes. A considerable body of evidence implicates oxidative stress as an important pathogenic factor of diabetic vasculopathies. In the present study, the effect of hesperidin, a flavanone glycoside with antioxidant activity, is studied in endothelium-dependent relaxation of the rat aorta in experimental diabetes mellitus type 1 (DM1 and type 2 (DM2. Patients and Methods: Single dose intraperitoneal injection of streptozocin (60mg/kg and subcutaneous daily injection of dexamethasone (10µg/kg for one month were used to induce DM1 and DM2, respectively. Hesperidin (500mg/kg was administered orally for two months in DM1 and one month in DM2. The effect of acetylcholine (Ach on phenyl ephrine (PE induced. PE contracted aorta was then studied and the EC50 and maximal relaxant effect of Ach were calculated and compared in the two groups.Results: In the experimental DM1, hesperidin restored endothelium-dependent relaxation near to those of normal animals. Its effect on experimental DM2 consisted of a significant reduction of EC50 value of Ach compared to those of diabetic animals. It also showed a great but non-significant effect (P=0.07 on Ach-induced maximum relaxation compared to DM2 untreated animals. Conclusion: These results show that hesperidin can improve vascular endothelial dysfunction in experimental diabetes mellitus.

  3. Traumatic brain injury causes platelet adenosine diphosphate and arachidonic acid receptor inhibition independent of hemorrhagic shock in humans and rats.

    Science.gov (United States)

    Castellino, Francis J; Chapman, Michael P; Donahue, Deborah L; Thomas, Scott; Moore, Ernest E; Wohlauer, Max V; Fritz, Braxton; Yount, Robert; Ploplis, Victoria; Davis, Patrick; Evans, Edward; Walsh, Mark

    2014-05-01

    Coagulopathy in traumatic brain injury (CTBI) is a well-established phenomenon, but its mechanism is poorly understood. Various studies implicate protein C activation related to the global insult of hemorrhagic shock or brain tissue factor release with resultant platelet dysfunction and depletion of coagulation factors. We hypothesized that the platelet dysfunction of CTBI is a distinct phenomenon from the coagulopathy following hemorrhagic shock. We used thrombelastography with platelet mapping as a measure of platelet function, assessing the degree of inhibition of the adenosine diphosphate (ADP) and arachidonic acid (AA) receptor pathways. First, we studied the early effect of TBI on platelet inhibition by performing thrombelastography with platelet mapping on rats. We then conducted an analysis of admission blood samples from trauma patients with isolated head injury (n = 70). Patients in shock or on clopidogrel or aspirin were excluded. In rats, ADP receptor inhibition at 15 minutes after injury was 77.6% ± 6.7% versus 39.0% ± 5.3% for controls (p injury in patients with isolated head trauma. This phenomenon is observed in the absence of hemorrhagic shock or multisystem injury. Thus, TBI alone is shown to be sufficient to induce a profound platelet dysfunction.

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

    Science.gov (United States)

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

    2016-04-01

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

  5. Cell-free released components of Streptococcus sanguis inhibit human platelet aggregation.

    Science.gov (United States)

    Herzberg, M C; Brintzenhofe, K L; Clawson, C C

    1983-01-01

    To study the role of surface components in the selective binding and aggregation of platelet-rich plasma (PRP) by strains of viridans streptococci, we treated the binding, aggregation strain Streptococcus sanguis I 2017-78 by sonication or trypsinization. Morphologically identifiable electron-dense fibrils were released from the cell wall, apparently from an inner electron-dense layer, under conditions that left cells intact. These controlled conditions were determined to cause submaximal loss in adhesion to platelet ghosts and PRP aggregation by treated, washed S. sanguis. Soluble components were recovered from the controlled sonic or L-(tosylamido 2-phenyl)ethyl chloromethyl ketone-trypsin treatments. Each showed dose-response inhibition of aggregation when preincubated with PRP before challenge with fresh, untreated S. sanguis. The time to onset of PRP aggregation was inhibited by 50% with 0.2 mg of TPCK-trypsin peptides or 1.0 mg of the sonicate per ml per 2 X 10(8) platelets. Components of both preparations were immunologically cross-reactive, but lipoteichoic acid was not a major antigen of either. By weight, the TPCK-trypsin peptides were virtually all protein; the sonicate residues identified were about 50% protein and 7% hexose. Each was a complex mixture of components as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. More than 8 TPCK-trypsin peptides and 16 sonicate components were so identified. In contrast, at least four or five components from either preparation were recognized as surface determinants by a rabbit antiserum to whole homologous microbes. Platelet-binding ligands of S. sanguis could be among these determinants. Images PMID:6618669

  6. Albumin inhibits platelet-activating factor (PAF)-induced responses in platelets and macrophages: implications for the biologically active form of PAF.

    OpenAIRE

    Grigoriadis, G.; Stewart, A. G.

    1992-01-01

    1. Platelet-activating factor (PAF) binds with high affinity to albumin leading Clay et al. (1990) to suggest that the active form of PAF is the albumin-PAF complex. 2. In the present study the proposal that albumin-bound, rather than monomeric PAF, is the active form of PAF at PAF receptors was critically evaluated by examining the effect of albumin on the potency of PAF in isolated platelets and macrophages. 3. Bovine serum albumin inhibited concentration-dependently PAF-induced responses i...

  7. 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.

    Science.gov (United States)

    Son, Dong Ju; Akiba, Satoshi; Hong, Jin Tae; Yun, Yeo Pyo; Hwang, Seock Yeon; Park, Young Hyun; Lee, Sung Eun

    2014-08-22

    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; 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; 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 (PG)E2 and PGD2 in RAW264.7 cells by suppressing the activity of COX-2, without effect on cPLA2; Our findings indicate that piperine inhibits platelet aggregation and macrophage inflammatory response by different mechanisms.

  8. 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.

  9. P2Y12 Receptor Blockade Augments Glycoprotein IIb‐IIIa Antagonist Inhibition of Platelet Activation, Aggregation, and Procoagulant Activity

    Science.gov (United States)

    Berny‐Lang, Michelle A.; Jakubowski, Joseph A.; Sugidachi, Atsuhiro; Barnard, Marc R.; Michelson, Alan D.; Frelinger, Andrew L.

    2013-01-01

    Background New antiplatelet agents that provide greater, more consistent inhibition of the platelet ADP receptor P2Y12 may be used in combination with glycoprotein (GP) IIb‐IIIa antagonists, but their combined effect on platelet function and procoagulant activity is not well studied. Therefore, the objective of this study was to evaluate the independent and complementary effects of P2Y12 and GPIIb‐IIIa inhibition on platelet function and procoagulant activity. Methods and Results Healthy donor blood was treated with the active metabolite of prasugrel (R‐138727 5 μmol/L), GPIIb‐IIIa antagonists (abciximab 3 μg/mL or eptifibatide 0.9 μg/mL), and combinations thereof, exposed to physiologically relevant agonists (collagen and ADP) and then evaluated for markers of platelet activation and procoagulant activity. Significant interactions between R‐138727 and GPIIb‐IIIa antagonists were observed. R‐138727 and the GPIIb‐IIIa antagonists had additive inhibitory effects on collagen‐stimulated platelet aggregation and on the collagen plus ADP–stimulated level of activated platelet surface GPIIb‐IIIa. R‐138727 and abciximab each inhibited collagen plus ADP–stimulated platelet phosphatidylserine expression and prothrombin cleavage, and the combination produced greater inhibition than achieved with abciximab alone. In contrast, eptifibatide did not inhibit, but instead enhanced, collagen plus ADP–stimulated prothrombin cleavage. Addition of R‐138727 reduced prothrombin cleavage in eptifibatide‐treated samples, suggesting a novel mechanism for potential benefit from combined prasugrel and eptifibatide treatment. Conclusions The complementary effects of abciximab and R‐138727 on platelet activation, aggregation, and procoagulant activity suggest their combined use may, to a greater degree than with either agent alone, reduce thrombus formation in vivo. PMID:23676293

  10. Thieno[2,3-b]pyridine derivatives are potent anti-platelet drugs, inhibiting platelet activation, aggregation and showing synergy with aspirin.

    Science.gov (United States)

    Binsaleh, Naif K; Wigley, Catherine A; Whitehead, Kathryn A; van Rensburg, Michelle; Reynisson, Johannes; Pilkington, Lisa I; Barker, David; Jones, Sarah; Dempsey-Hibbert, Nina C

    2018-01-01

    Drugs which inhibit platelet function are commonly used to prevent blood clot formation in patients with Acute Coronary Syndromes (ACS) or those at risk of stroke. The thieno[3,2-c]pyridine class of therapeutic agents, of which clopidogrel is the most commonly used, target the P2Y12 receptor, and are often used in combination with acetylsalicylic acid (ASA). Six thieno[2,3-b]pyridine were assessed for in vitro anti-platelet activity; all derivatives showed effects on both platelet activation and aggregation, and showed synergy with ASA. Some compounds demonstrated greater activity when compared to clopidogrel. These compounds, therefore, represent potential novel P2Y12 inhibitors for improved treatment for patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. 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 plate...... correlation between these metabolic and functional activities indicates that there exist, besides cAMP-phosphodiesterase inhibition, additional mechanisms of action for the platelet aggregation inhibitory effect of dihydropyrano- and dihydrofuranocoumarins....... 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...

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

    Directory of Open Access Journals (Sweden)

    Karin Hadas

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

  13. A Study of Platelet Inhibition, Using a 'Point of Care' Platelet Function Test, following Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction [PINPOINT-PPCI].

    Directory of Open Access Journals (Sweden)

    Thomas W Johnson

    Full Text Available Rapid coronary recanalization following ST-elevation myocardial infarction (STEMI requires effective anti-platelet and anti-thrombotic therapies. This study tested the impact of door to end of procedure ('door-to-end' time and baseline platelet activity on platelet inhibition within 24hours post-STEMI.108 patients, treated with prasugrel and procedural bivalirudin, underwent Multiplate® platelet function testing at baseline, 0, 1, 2 and 24hours post-procedure. Major adverse cardiac events (MACE, bleeding and stent thrombosis (ST were recorded. Baseline ADP activity was high (88.3U [71.8-109.0], procedural time and consequently bivalirudin infusion duration were short (median door-to-end time 55minutes [40-70] and infusion duration 30minutes [20-42]. Baseline ADP was observed to influence all subsequent measurements of ADP activity, whereas door-to-end time only influenced ADP immediately post-procedure. High residual platelet reactivity (HRPR ADP>46.8U was observed in 75% of patients immediately post-procedure and persisted in 24% of patients at 2hours. Five patients suffered in-hospital MACE (4.6%. Acute ST occurred in 4 patients, all were <120mins post-procedure and had HRPR. No significant bleeding was observed. In a post-hoc analysis, pre-procedural morphine use was associated with significantly higher ADP activity following intervention.Baseline platelet function, time to STEMI treatment and opiate use all significantly influence immediate post-procedural platelet activity.

  14. Platelets contain tissue factor pathway inhibitor-2 derived from megakaryocytes and inhibits fibrinolysis.

    Science.gov (United States)

    Vadivel, Kanagasabai; Ponnuraj, Sathya-Moorthy; Kumar, Yogesh; Zaiss, Anne K; Bunce, Matthew W; Camire, Rodney M; Wu, Ling; Evseenko, Denis; Herschman, Harvey R; Bajaj, Madhu S; Bajaj, S Paul

    2014-11-07

    Tissue factor pathway inhibitor-2 (TFPI-2) is a homologue of TFPI-1 and contains three Kunitz-type domains and a basic C terminus region. The N-terminal domain of TFPI-2 is the only inhibitory domain, and it inhibits plasma kallikrein, factor XIa, and plasmin. However, plasma TFPI-2 levels are negligible (≤20 pM) in the context of influencing clotting or fibrinolysis. Here, we report that platelets contain significant amounts of TFPI-2 derived from megakaryocytes. We employed RT-PCR, Western blotting, immunohistochemistry, and confocal microscopy to determine that platelets, MEG-01 megakaryoblastic cells, and bone marrow megakaryocytes contain TFPI-2. ELISA data reveal that TFPI-2 binds factor V (FV) and partially B-domain-deleted FV (FV-1033) with K(d) ~9 nM and binds FVa with K(d) ~100 nM. Steady state analysis of surface plasmon resonance data reveal that TFPI-2 and TFPI-1 bind FV-1033 with K(d) ~36-48 nM and bind FVa with K(d) ~252-456 nM. Further, TFPI-1 (but not TFPI-1161) competes with TFPI-2 in binding to FV. These data indicate that the C-terminal basic region of TFPI-2 is similar to that of TFPI-1 and plays a role in binding to the FV B-domain acidic region. Using pull-down assays and Western blots, we show that TFPI-2 is associated with platelet FV/FVa. TFPI-2 (~7 nM) in plasma of women at the onset of labor is also, in part, associated with FV. Importantly, TFPI-2 in platelets and in plasma of pregnant women inhibits FXIa and tissue-type plasminogen activator-induced clot fibrinolysis. In conclusion, TFPI-2 in platelets from normal or pregnant subjects and in plasma from pregnant women binds FV/Va and regulates intrinsic coagulation and fibrinolysis. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Salvia miltiorrhiza Bunge (Danshen) extract attenuates permanent cerebral ischemia through inhibiting platelet activation in rats.

    Science.gov (United States)

    Fei, Yu-Xiang; Wang, Si-Qi; Yang, Li-Jian; Qiu, Yan-Ying; Li, Yi-Ze; Liu, Wen-Yuan; Xi, Tao; Fang, Wei-Rong; Li, Yun-Man

    2017-07-31

    Danshen is a crude herbal drug isolated from dried roots of Salvia miltiorrhiza Bunge. This plant is widely used in oriental medicine for the treatment of cardiovascular and cerebrovascular diseases. The supercritical CO2 extract from Danshen (SCED) (57.85%, 5.67% and 4.55% for tanshinone IIA, tanshinone I and cryptotanshinone respectively) was studied in this article, whose potential molecular mechanism remains unclear, especially in anti-thrombosis. The present study was designed to observe the protective effect of SCED on ischemic stroke in rats and to explore the underlying anti-thrombosis mechanism. Following induction of cerebral ischemia in rats by permanent middle cerebral artery occlusion (pMCAO). Neurological defect score, cerebral blood flow, infarct size, and brain edema were measured to evaluate the injury. Arteriovenous shunt thrombosis model and adenosine 5'-diphosphate (ADP) induced acute pulmonary embolism model were conducted to estimate the antithrombotic effect of SCED. In order to investigate the effects of SCED on platelet aggregation, rat platelet-rich-plasma (PRP) were incubated with SCED prior to the addition of the stimuli (ADP or 9, 11-dideoxy-11α, 9α-epoxymethanoprostaglandin F2α (U46619)). Aggregation was monitored in a light transmission aggregometer. Inhibitory effect of SCED on thromboxane A2 (TXA2) release was detected by ELISA kit. Phospholipase C (PLC)/ Protein kinase C (PKC) signaling pathway was analyzed by a Western blot technique. The effect of the SCED was also studied in vivo on bleeding time in mice. SCED improved the neurological defect score, increased cerebral blood flow, reduced infarct size and alleviated brain edema in rats exposed to pMCAO. After administration of SCED, thrombosis formation in arteriovenous shunt was inhibited and recovery time in pulmonary embolism was shortened. The inhibitory effect of SCED on platelet activation was further confirmed by TXB2 ELISA kit and Western blot analysis of PLC

  16. Inverse agonism at the P2Y12 receptor and ENT1 transporter blockade contribute to platelet inhibition by ticagrelor.

    Science.gov (United States)

    Aungraheeta, Riyaad; Conibear, Alexandra; Butler, Mark; Kelly, Eamonn; Nylander, Sven; Mumford, Andrew; Mundell, Stuart J

    2016-12-08

    Ticagrelor is a potent antagonist of the P2Y12 receptor (P2Y12R) and consequently an inhibitor of platelet activity effective in the treatment of atherothrombosis. Here, we sought to further characterize its molecular mechanism of action. Initial studies showed that ticagrelor promoted a greater inhibition of adenosine 5'-diphosphate (ADP)-induced Ca(2+) release in washed platelets vs other P2Y12R antagonists. This additional effect of ticagrelor beyond P2Y12R antagonism was in part as a consequence of ticagrelor inhibiting the equilibrative nucleoside transporter 1 (ENT1) on platelets, leading to accumulation of extracellular adenosine and activation of Gs-coupled adenosine A2A receptors. This contributed to an increase in basal cyclic adenosine monophosphate (cAMP) and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P). In addition, ticagrelor increased platelet cAMP and VASP-P in the absence of ADP in an adenosine receptor-independent manner. We hypothesized that this increase originated from a direct effect on basal agonist-independent P2Y12R signaling, and this was validated in 1321N1 cells stably transfected with human P2Y12R. In these cells, ticagrelor blocked the constitutive agonist-independent activity of the P2Y12R, limiting basal Gi-coupled signaling and thereby increasing cAMP levels. These data suggest that ticagrelor has the pharmacological profile of an inverse agonist. Based on our results showing insurmountable inhibition of ADP-induced Ca(2+) release and forskolin-induced cAMP, the mode of antagonism of ticagrelor also appears noncompetitive, at least functionally. In summary, our studies describe 2 novel modes of action of ticagrelor, inhibition of platelet ENT1 and inverse agonism at the P2Y12R that contribute to its effective inhibition of platelet activation. © 2016 by The American Society of Hematology.

  17. Platelets induce apoptosis during sepsis in a contact-dependent manner that is inhibited by GPIIb/IIIa blockade.

    Directory of Open Access Journals (Sweden)

    Matthew Sharron

    Full Text Available PURPOSE: End-organ apoptosis is well-described in progressive sepsis and Multiple Organ Dysfunction Syndrome (MODS, especially where platelets accumulate (e.g. spleen and lung. We previously reported an acute sepsis-induced cytotoxic platelet phenotype expressing serine protease granzyme B. We now aim to define the site(s of and mechanism(s by which platelet granzyme B induces end-organ apoptosis in sepsis. METHODS: End-organ apoptosis in murine sepsis (i.e. polymicrobial peritonitis was analyzed by immunohistochemistry. Platelet cytotoxicity was measured by flow cytometry following 90 minute ex vivo co-incubation with healthy murine splenocytes. Sepsis progression was measured via validated preclinical murine sepsis score. MEASUREMENTS AND MAIN RESULTS: There was evident apoptosis in spleen, lung, and kidney sections from septic wild type mice. In contrast, there was a lack of TUNEL staining in spleens and lungs from septic granzyme B null mice and these mice survived longer following induction of sepsis than wild type mice. In co-incubation experiments, physical separation of septic platelets from splenocytes by a semi-permeable membrane reduced splenocyte apoptosis to a rate indistinguishable from negative controls. Chemical separation by the platelet GPIIb/IIIa receptor inhibitor eptifibatide decreased apoptosis by 66.6±10.6% (p = 0.008. Mice treated with eptifibatide in vivo survived longer following induction of sepsis than vehicle control mice. CONCLUSIONS: In sepsis, platelet granzyme B-mediated apoptosis occurs in spleen and lung, and absence of granzyme B slows sepsis progression. This process proceeds in a contact-dependent manner that is inhibited ex vivo and in vivo by the platelet GPIIb/IIIa receptor inhibitor eptifibatide. The GPIIb/IIIa inhibitors and other classes of anti-platelet drugs may be protective in sepsis.

  18. Platelets Induce Apoptosis during Sepsis in a Contact-Dependent Manner That Is Inhibited by GPIIb/IIIa Blockade

    Science.gov (United States)

    Sharron, Matthew; Hoptay, Claire E.; Wiles, Andrew A.; Garvin, Lindsay M.; Geha, Mayya; Benton, Angela S.; Nagaraju, Kanneboyina; Freishtat, Robert J.

    2012-01-01

    Purpose End-organ apoptosis is well-described in progressive sepsis and Multiple Organ Dysfunction Syndrome (MODS), especially where platelets accumulate (e.g. spleen and lung). We previously reported an acute sepsis-induced cytotoxic platelet phenotype expressing serine protease granzyme B. We now aim to define the site(s) of and mechanism(s) by which platelet granzyme B induces end-organ apoptosis in sepsis. Methods End-organ apoptosis in murine sepsis (i.e. polymicrobial peritonitis) was analyzed by immunohistochemistry. Platelet cytotoxicity was measured by flow cytometry following 90 minute ex vivo co-incubation with healthy murine splenocytes. Sepsis progression was measured via validated preclinical murine sepsis score. Measurements and Main Results There was evident apoptosis in spleen, lung, and kidney sections from septic wild type mice. In contrast, there was a lack of TUNEL staining in spleens and lungs from septic granzyme B null mice and these mice survived longer following induction of sepsis than wild type mice. In co-incubation experiments, physical separation of septic platelets from splenocytes by a semi-permeable membrane reduced splenocyte apoptosis to a rate indistinguishable from negative controls. Chemical separation by the platelet GPIIb/IIIa receptor inhibitor eptifibatide decreased apoptosis by 66.6±10.6% (p = 0.008). Mice treated with eptifibatide in vivo survived longer following induction of sepsis than vehicle control mice. Conclusions In sepsis, platelet granzyme B-mediated apoptosis occurs in spleen and lung, and absence of granzyme B slows sepsis progression. This process proceeds in a contact-dependent manner that is inhibited ex vivo and in vivo by the platelet GPIIb/IIIa receptor inhibitor eptifibatide. The GPIIb/IIIa inhibitors and other classes of anti-platelet drugs may be protective in sepsis. PMID:22844498

  19. Cannabidiol causes endothelium-dependent vasorelaxation of human mesenteric arteries via CB1 activation.

    Science.gov (United States)

    Stanley, Christopher P; Hind, William H; Tufarelli, Cristina; O'Sullivan, Saoirse E

    2015-09-01

    The protective effects of cannabidiol (CBD) have been widely shown in preclinical models and have translated into medicines for the treatment of multiple sclerosis and epilepsy. However, the direct vascular effects of CBD in humans are unknown. Using wire myography, the vascular effects of CBD were assessed in human mesenteric arteries, and the mechanisms of action probed pharmacologically. CBD-induced intracellular signalling was characterized using human aortic endothelial cells (HAECs). CBD caused acute, non-recoverable vasorelaxation of human mesenteric arteries with an Rmax of ∼ 40%. This was inhibited by cannabinoid receptor 1 (CB1) receptor antagonists, desensitization of transient receptor potential channels using capsaicin, removal of the endothelium, and inhibition of potassium efflux. There was no role for cannabinoid receptor-2 (CB2) receptor, peroxisome proliferator activated receptor (PPAR)γ, the novel endothelial cannabinoid receptor (CBe), or cyclooxygenase. CBD-induced vasorelaxation was blunted in males, and in patients with type 2 diabetes or hypercholesterolemia. In HAECs, CBD significantly reduced phosphorylated JNK, NFκB, p70s6 K and STAT5, and significantly increased phosphorylated CREB, ERK1/2, and Akt levels. CBD also increased phosphorylated eNOS (ser1177), which was correlated with increased levels of ERK1/2 and Akt levels. CB1 receptor antagonism prevented the increase in eNOS phosphorylation. This study shows, for the first time, that CBD causes vasorelaxation of human mesenteric arteries via activation of CB1 and TRP channels, and is endothelium- and nitric oxide-dependent. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

  20. Calcium sensing receptor initiating cystathionine-gamma-lyase/hydrogen sulfide pathway to inhibit platelet activation in hyperhomocysteinemia rat.

    Science.gov (United States)

    Wang, Yuwen; Zhao, Ziqing; Shi, Sa; Gao, Fei; Wu, Jichao; Dong, Shiyun; Zhang, Weihua; Liu, Yanhong; Zhong, Xin

    2017-09-15

    Hyperhomocysteinemia (HHcy, high homocysteine) induces the injury of endothelial cells (ECs). Hydrogen sulfide (H2S) protects ECs and inhibits the activation of platelets. Calcium-sensing receptor (CaSR) regulates the production of endogenous H2S. However, whether CaSR inhibits the injury of ECs and the activation of platelets by regulating the endogenous cystathionine-gamma-lyase (CSE, a major enzyme that produces H2S)/H2S pathway in hyperhomocysteinemia has not been previously investigated. Here, we tested the ultrastructure alterations of ECs and platelets, the changes in the concentration of serum homocysteine and the parameters of blood of hyperhomocysteinemia rats were measured. The aggregation rate and expression of P-selectin of platelets were assessed. Additionally, the expression levels of CaSR and CSE in the aorta of rats were examined by western blotting. The mitochondrial membrane potential and the production of reactive oxygen species (ROS) were measured; the expression of phospho-calmodulin kinases II (p-CaMK II) and Von Willebrand Factor (vWF) of cultured ECs from rat thoracic aortas were measured. We found that the aggregation rate and the expression of P-selectin of platelets increased, and the expression of CaSR and CSE decreased in HHcy rats. In the ECs of HHcy group, the ROS production increased and the mitochondrial membrane potential decreased markedly, the expression of CSE and the p-CaMK II increased after treatment with CaSR agonist while decreased upon administration of U73122 (PLC-specific inhibitor) and 2-APB (IP3 Receptor inhibitor). CaSR agonist or NaHS significantly reversed the ECs injured and platelet aggregation caused by hyperhomocysteinemia. Our results demonstrate that CaSR regulates the endogenous CSE/H2S pathway to inhibit the activation of platelets which concerts the protection of ECs in hyperhomocysteinemia. Copyright © 2017. Published by Elsevier Inc.

  1. Angiographic outcomes in the PLATO Trial (Platelet Inhibition and Patient Outcomes).

    Science.gov (United States)

    Kunadian, Vijay; James, Stefan K; Wojdyla, Daniel M; Zorkun, Cafer; Wu, Jinhui; Storey, Robert F; Steg, Ph Gabriel; Katus, Hugo; Emanuelsson, Hakan; Horrow, Jay; Maya, Juan; Wallentin, Lars; Harrington, Robert A; Gibson, C Michael

    2013-07-01

    The PLATO (Platelet Inhibition and Patient Outcomes) angiographic substudy sought to compare the efficacy of ticagrelor versus clopidogrel with respect to angiographic outcomes before and after PCI in the setting of acute coronary syndrome. Greater platelet inhibition has been associated with improved angiographic outcomes before and after percutaneous coronary intervention (PCI). Therefore, it was hypothesized that treatment with ticagrelor, which achieves more rapid, higher, and more consistent platelet inhibition, would be associated with improved angiographic outcomes when compared with those of clopidogrel treatment. The angiographic cohort consists of 2,616 patients drawn from the 18,624-patient PLATO trial. Clopidogrel naïve or pre-treated patients were randomized to 180 mg of ticagrelor or 300 mg of clopidogrel (75 mg for clopidogrel pre-treated patients). PCI patients were administered, as per treatment group: 1) an additional 90 mg of ticagrelor if >24 h following the initial loading dose; or 2) an optional further 300 mg of clopidogrel or placebo (total 600 mg) prior to PCI. The substudy primary endpoint was the incidence of post-PCI TIMI (Thrombolysis In Myocardial Infarction) myocardial perfusion grade 3 (TMPG 3) among patients who received a study drug prior to PCI. In total, 21.3% of patients were pretreated with clopidogrel prior to randomization. There was a short time interval between randomization and PCI (median: 0.68 [interquartile range (IQR): 0.30 to 2.21] h) among all patients. Post-PCI TMPG 3 was similar between the ticagrelor and clopidogrel groups (47.1% vs. 46.9%; p = 0.96). Likewise, the following pre-PCI outcomes were similar in the ticagrelor and clopidogrel groups, respectively: TMPG 3 (30.5% vs. 31.2%), TIMI flow grade 3 (37.1% vs. 39.3%), corrected TIMI frame count (median: 100 vs. 71 frames), TIMI thrombus grade 0 (24.1% vs. 27.6%), minimum lumen diameter (median: 0.3 [IQR: 0.0 to 0.6] vs. 0.3 [IQR: 0.0 to 0.6] mm) and percentage

  2. Nerve growth factor inhibits metalloproteinase-disintegrins and blocks ectodomain shedding of platelet glycoprotein VI.

    Science.gov (United States)

    Wijeyewickrema, Lakshmi C; Gardiner, Elizabeth E; Gladigau, Elsa L; Berndt, Michael C; Andrews, Robert K

    2010-04-16

    Nerve growth factor (NGF) plays an important role in regulating mammalian neuronal/embryonic development, angiogenesis, and other physiological processes and has recently been investigated as a potential treatment for the neurodegenerative disorder, Alzheimer disease. In this study, we provide evidence that human NGF may also function as a metalloproteinase inhibitor, based on studies of NGF from snake venom. Originally, our aim was to isolate snake venom metalloproteinases targeting platelet receptors and/or ligands relevant to hemostasis and thrombosis, using Ni(2+)-agarose as a purification step based on the conserved metal ion-coordination motif in venom metalloproteinases. However, subsequent analysis of cobra (Naja kaouthia) venom led to the unexpected discovery that cobra venom NGF bound to Ni(2+)-agarose, eluting at approximately 15 mm imidazole, enabling a one-step purification. The identity of the purified protein was confirmed by mass spectrometry and N-terminal sequence analysis. Partial co-purification of NGF within metalloproteinase-enriched venom fractions led us to test whether NGF affected metalloproteinase activity. Venom NGF potently inhibited metalloproteinases isolated from the same or different venom and specifically bound to purified Nk metalloproteinase immobilized on agarose beads. Human NGF also interacted with human metalloproteinases because it blocked metalloproteinase-mediated shedding of the platelet collagen receptor, glycoprotein (GP)VI, and associated with recombinant ADAM10 by surface plasmon resonance. Together, these results suggest that NGF can function as a metalloproteinase inhibitor.

  3. Nerve Growth Factor Inhibits Metalloproteinase-Disintegrins and Blocks Ectodomain Shedding of Platelet Glycoprotein VI*

    Science.gov (United States)

    Wijeyewickrema, Lakshmi C.; Gardiner, Elizabeth E.; Gladigau, Elsa L.; Berndt, Michael C.; Andrews, Robert K.

    2010-01-01

    Nerve growth factor (NGF) plays an important role in regulating mammalian neuronal/embryonic development, angiogenesis, and other physiological processes and has recently been investigated as a potential treatment for the neurodegenerative disorder, Alzheimer disease. In this study, we provide evidence that human NGF may also function as a metalloproteinase inhibitor, based on studies of NGF from snake venom. Originally, our aim was to isolate snake venom metalloproteinases targeting platelet receptors and/or ligands relevant to hemostasis and thrombosis, using Ni2+-agarose as a purification step based on the conserved metal ion-coordination motif in venom metalloproteinases. However, subsequent analysis of cobra (Naja kaouthia) venom led to the unexpected discovery that cobra venom NGF bound to Ni2+-agarose, eluting at ∼15 mm imidazole, enabling a one-step purification. The identity of the purified protein was confirmed by mass spectrometry and N-terminal sequence analysis. Partial co-purification of NGF within metalloproteinase-enriched venom fractions led us to test whether NGF affected metalloproteinase activity. Venom NGF potently inhibited metalloproteinases isolated from the same or different venom and specifically bound to purified Nk metalloproteinase immobilized on agarose beads. Human NGF also interacted with human metalloproteinases because it blocked metalloproteinase-mediated shedding of the platelet collagen receptor, glycoprotein (GP)VI, and associated with recombinant ADAM10 by surface plasmon resonance. Together, these results suggest that NGF can function as a metalloproteinase inhibitor. PMID:20164177

  4. Fruit juice-induced endothelium-dependent relaxations in isolated porcine coronary arteries: evaluation of different fruit juices and purees and optimization of a red fruit juice blend.

    Science.gov (United States)

    Auger, Cyril; Kim, Jong-Hun; Trinh, Sandrine; Chataigneau, Thierry; Popken, Anne M; Schini-Kerth, Valérie B

    2011-05-01

    Numerous studies have indicated that several polyphenol-rich sources such as red wine and green tea are potent inducers of endothelium-dependent relaxations in isolated arteries. As various fruits and berries are known to contain high levels of polyphenols, the aim of the present study was to assess the ability of selected pure fruit juices and purees as well as blends to cause endothelium-dependent relaxations in isolated arteries. Vascular reactivity was assessed using porcine coronary artery rings, and fruit juices, purees and blends were characterized for their content in vitamin C, total phenolic, sugar and antioxidant activity. Fruit juices and purees caused variable concentration-dependent relaxations, with blackcurrant, aronia, cranberry, blueberry, lingonberry, and grape being the most effective fruits. Several blends of red fruits caused endothelium-dependent relaxations. Relaxations to blend D involved both a NO- and an EDHF-mediated components. The present findings indicate that some berries and blends of red fruit juices are potent inducers of endothelium-dependent relaxations in the porcine coronary artery. This effect involves both endothelium-derived NO and EDHF, and appears to be dependent on their polyphenolic composition rather than on the polyphenolic content.

  5. Type 2 diabetes is associated with impaired endothelium-dependent, flow-mediated dilation, but impaired glucose metabolism is not - The Hoorn study

    NARCIS (Netherlands)

    Henry, R.M.A.; Ferreira, I.; Kostense, P.J.; Dekker, J.M.; Nijpels, G.; Heine, R.J.; Kamp, O.; Bouter, L.M.; Stehouwer, C.D.A.

    2004-01-01

    Background: Type 2 diabetes (DM2) and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease risk. Impaired endothelial synthesis of nitric oxide (NO) is an important feature of atherothrombosis and can be estimated from endothelium-dependent flow-mediated dilation

  6. Inhibition of platelet-derived growth factor signaling prevents muscle fiber growth during skeletal muscle hypertrophy.

    Science.gov (United States)

    Sugg, Kristoffer B; Korn, Michael A; Sarver, Dylan C; Markworth, James F; Mendias, Christopher L

    2017-03-01

    The platelet-derived growth factor receptors alpha and beta (PDGFRα and PDGFRβ) mark fibroadipogenic progenitor cells/fibroblasts and pericytes in skeletal muscle, respectively. While the role that these cells play in muscle growth and development has been evaluated, it was not known whether the PDGF receptors activate signaling pathways that control transcriptional and functional changes during skeletal muscle hypertrophy. To evaluate this, we inhibited PDGFR signaling in mice subjected to a synergist ablation muscle growth procedure, and performed analyses 3 and 10 days after induction of hypertrophy. The results from this study indicate that PDGF signaling is required for fiber hypertrophy, extracellular matrix production, and angiogenesis that occur during muscle growth. © 2017 Federation of European Biochemical Societies.

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

    Directory of Open Access Journals (Sweden)

    Paul C Armstrong

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

  8. Consistent platelet inhibition with ticagrelor 60 mg twice-daily following myocardial infarction regardless of diabetes status.

    Science.gov (United States)

    Thomas, Mark R; Angiolillo, Dominick J; Bonaca, Marc P; Ajjan, Ramzi A; Judge, Heather M; Rollini, Fabiana; Franchi, Francesco; Ahsan, Arif J; Bhatt, Deepak L; Kuder, Julia F; Steg, Philippe Gabriel; Cohen, Marc; Muthusamy, Rangasamy; Sabatine, Marc S; Storey, Robert F

    2017-05-03

    Diabetes increases cardiovascular risk and reduces pharmacodynamic response to some oral antiplatelet drugs. This study aimed to determine whether ticagrelor 60 mg twice daily (bid) provided potent and consistent platelet inhibition in patients with vs without diabetes in the PEGASUS-TIMI 54 platelet function substudy. Out of 180 patients studied, 58 patients were randomised to and had received at least four weeks of ticagrelor 60 mg bid, with 20 (34 %) having diabetes, 58 patients received ticagrelor 90 mg bid, with 12 (21 %) having diabetes, and 64 patients received placebo, with 18 (28 %) having diabetes. Blood was sampled pre- and 2 hours post-maintenance dose. In patients treated with ticagrelor 60 mg bid, on-treatment platelet reactivity to ADP, as determined by light transmission aggregometry (LTA), VerifyNow and VASP, was similar in patients with vs without diabetes (LTA post-dose, ADP 20 µM: 29 ± 14 vs 34 ± 10 %, respectively; p = 0.19). A consistent inhibitory effect of ticagrelor 60 mg bid was observed pre- and post-dose regardless of diabetes status, even in insulin-treated patients. Patients with diabetes did not have an increased incidence of high platelet reactivity in either ticagrelor group. Platelet reactivity was similar in patients with diabetes treated with ticagrelor 60 mg vs 90 mg bid. Pharmacokinetics of ticagrelor were not affected by diabetes status. In conclusion, ticagrelor 60 mg bid is equally effective at reducing platelet reactivity in patients with and without diabetes, yielding a consistently high level of platelet inhibition regardless of diabetes status.

  9. Molecular basis of the synergistic inhibition of platelet function by nitrovasodilators and activators of adenylate cyclase: inhibition of cyclic AMP breakdown by cyclic GMP.

    Science.gov (United States)

    Maurice, D H; Haslam, R J

    1990-05-01

    We investigated the roles of cyclic GMP and cyclic AMP in the inhibition of rabbit platelet aggregation and degranulation by two nitrovasodilators, sodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1; the active metabolite of molsidomine), with particular reference to the synergistic interaction of these drugs with prostaglandin E1 (PGE1). Changes in platelet cyclic [3H]GMP and cyclic [3H]AMP were measured by rapid and sensitive prelabeling techniques, the validity of which were confirmed by radioimmunoassays. Incubation of the platelets with 0.1 to 10 microM SNP alone for 0.5 min caused progressively greater inhibitions of platelet function associated with large dose-dependent increases in cyclic [3H]GMP and 1.4- to 3.0-fold increases in cyclic [3H]AMP. However, addition of SNP with the adenylate cyclase activator, PGE1, at a concentration of the latter that had little effect alone, caused much larger increases in cyclic [3H]AMP and greatly enhanced the inhibition of platelet aggregation. SIN-1 had effects similar to those of SNP, although it was less active. The adenylate cyclase inhibitor 2',5'-dideoxyadenosine (DDA) diminished the increases in cyclic [3H]AMP caused by SNP or SIN-1 in both the presence and absence of PGE1 but reduced the inhibition of platelet function caused by the nitrovasodilators only in the presence of PGE1. These results suggest that, although cyclic GMP may mediate the inhibition of rabbit platelet function by high concentrations of nitrovasodilators added alone, the synergistic interaction of lower concentrations with PGE1 depends on an enhanced accumulation of cyclic AMP. Synergistic effects on cyclic [3H]AMP accumulation were also observed on incubation of platelets with SNP and adenosine, another activator of adenylate cyclase. Hemoglobin, which binds nitric oxide, blocked or reversed the increases in both cyclic [3H]GMP and cyclic [3H]AMP in platelets caused by the nitrovasodilators added either alone or with PGE1

  10. Amantadine inhibits platelet-activating factor induced clathrin-mediated endocytosis in human neutrophils

    Science.gov (United States)

    Eckels, Phillip C.; Banerjee, Anirban; Moore, Ernest E.; McLaughlin, Nathan J. D.; Gries, Lynn M.; Kelher, Marguerite R.; England, Kelly M.; Gamboni-Robertson, Fabia; Khan, Samina Y.

    2009-01-01

    Receptor signaling is integral for adhesion, emigration, phagocytosis, and reactive oxygen species production in polymorphonuclear neutrophils (PMNs). Priming is an important part of PMN emigration, but it can also lead to PMN-mediated organ injury in the host. Platelet-activating factor (PAF) primes PMNs through activation of a specific G protein-coupled receptor. We hypothesize that PAF priming of PMNs requires clathrin-mediated endocytosis (CME) of the PAF receptor (PAFr), and, therefore, amantadine, known to inhibit CME, significantly antagonizes PAF signaling. PMNs were isolated by standard techniques to >98% purity and tested for viability. Amantadine (1 mM) significantly inhibited the PAF-mediated changes in the cellular distribution of clathrin and the physical colocalization [fluorescence resonance energy transfer positive (FRET+)] of early endosome antigen-1 and Rab5a, known components of CME and similar to hypertonic saline, a known inhibitor of CME. Furthermore, amantadine had no effect on the PAF-induced cytosolic calcium flux; however, phosphorylation of p38 MAPK was significantly decreased. Amantadine inhibited PAF-mediated changes in PMN physiology, including priming of the NADPH oxidase and shape change with lesser inhibition of increases in CD11b surface expression and elastase release. Furthermore, rimantadine, an amantadine analog, was a more potent inhibitor of PAF priming of the N-formyl-methionyl-leucyl-phenylalanine-activated oxidase. PAF priming of PMNs requires clathrin-mediated endocytosis that is inhibited when PMNs are pretreated with either amantadine or rimantadine. Thus, amantadine and rimantadine have the potential to ameliorate PMN-mediated tissue damage in humans. PMID:19295175

  11. Changes in the neurogenic and endothelium-dependent relaxant responses of rabbit corpus cavernosum smooth muscle after cavernous nerve neurotomy.

    Science.gov (United States)

    Utkan, T; Sarioglu, Y; Yazir, Y

    2010-04-01

    The present study was conducted to investigate the reactivity of the corpus cavernosum smooth muscle after unilateral cavernous nerve neurotomy in rabbits. Rabbits (18) were randomly divided into two groups: sham-operated (n = 9) and those subjected to unilateral neurotomy of a 5-mm segment of the cavernous nerve (n = 9). The reactivity of the corpus cavernosum tissue from the neurotomized and sham groups was studied in organ chambers at 4 weeks postoperation. In the neurotomized group, endothelium-dependent relaxation of the corpus cavernosum smooth muscle to carbachol was significantly increased when compared to the sham group. In addition, the sensitivity (i.e., pD(2)) of neurotomized strips to carbachol was also increased when compared to controls. Electrical field stimulation-induced neurogenic relaxation was significantly reduced in the neurotomized group. Relaxation to the nitric oxide (NO) donor sodium nitroprusside and to papaverine was similar in the cavernosal tissue of both groups. There was no change in agonist potency. Furthermore, neurotomy had no effect on KCl-induced contractile responses. When tissue contraction was induced with phenylephrine to study relaxation to various stimuli, the tension induced was similar in the neurotomized and the sham control groups. We conclude that unilateral, chronic cavernous nerve neurotomy causes significant functional changes to the penile erectile tissue of rabbits, which may contribute to the development of impotence. Copyright 2010 Prous Science, S.A.U. or its licensors. All rights reserved.

  12. Integrin alphaIIbbeta3-specific synthetic human monoclonal antibodies and HCDR3 peptides that potently inhibit platelet aggregation.

    Science.gov (United States)

    Chung, Junho; Rader, Christoph; Popkov, Mikhail; Hur, Young-Mi; Kim, Hyun-Kyung; Lee, Young-Joon; Barbas, Carlos F

    2004-02-01

    The interaction of fibrinogen with integrin alphaIIbbeta3 (GPIIb/IIIa), in part mediated by an RGD tripeptide motif, is an essential step in platelet aggregation. Based on their inhibition of platelet aggregation, three integrin alphaIIbbeta3 inhibitors are clinically approved. The clinically most widely used integrin alphaIIbbeta3 inhibitor abciximab is a chimeric mouse/human antibody that induces thrombocytopenia, often severe, in 1-2% of patients due to a human anti-mouse antibody (HAMA) response. In addition, unlike other ligands mimicking small molecular drugs, abciximab cross-reacts with integrin alphavbeta3 and alphaMbeta2. Here we used phage display to select monoclonal antibodies specific to integrin alphaIIbbeta3 from a synthetic human antibody library based on the randomized HCDR3 sequence VGXXXRADXXXYAMDV. The selected antibodies revealed a strong consensus in HCDR3 (V(V/W)CRAD(K/R)RC) and high specificity toward integrin alphaIIbbeta3 but not to other RGD binding integrins such as alphavbeta3, alphavbeta5, and alpha5beta1. The selected antibodies as well as three synthetic peptides (VWCRADRRC, VWCRADKRC, and VVCRADRRC) whose sequences were derived from the HCDR3 sequences of the selected antibodies strongly inhibited the interaction between integrin alphaIIbbeta3 and fibrinogen and platelet aggregation ex vivo. To our knowledge, these are the first fully human monoclonal antibodies that are specific to integrin alphaIIbbeta3 and can potently inhibit platelet aggregation.

  13. 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

    2016-09-01

    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. 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. 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. 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 prevention or treatment of thrombotic

  14. Serotonin Antagonism Improves Platelet Inhibition in Clopidogrel Low-Responders after Coronary Stent Placement: An In Vitro Pilot Study

    Science.gov (United States)

    Duerschmied, Daniel; Ahrens, Ingo; Mauler, Maximilian; Brandt, Christoph; Weidner, Stefanie; Bode, Christoph; Moser, Martin

    2012-01-01

    Increased residual platelet reactivity remains a burden for coronary artery disease (CAD) patients who received a coronary stent and do not respond sufficiently to treatment with acetylsalicylic acid and clopidogrel. We hypothesized that serotonin antagonism reduces high on-treatment platelet reactivity. Whole blood impedance aggregometry was performed with arachidonic acid (AA, 0.5 mM) and adenosine diphosphate (ADP, 6.5 µM) in addition to different concentrations of serotonin (1–100 µM) in whole blood from 42 CAD patients after coronary stent placement and 10 healthy subjects. Serotonin increased aggregation dose-dependently in CAD patients who responded to clopidogrel treatment: After activation with ADP, aggregation increased from 33.7±1.3% to 40.9±2.0% in the presence of 50 µM serotonin (pclopidogrel low-responders (from 59.9±3.1% to 37.4±3.5, pclopidogrel responders. These results were confirmed with light transmission aggregometry in platelet-rich plasma in a subset of patients. Serotonin hence increased residual platelet reactivity in patients who respond to clopidogrel after coronary stent placement. In clopidogrel low-responders, serotonin receptor antagonism improved platelet inhibition, almost reaching responder levels. This may justify further investigation of triple antiplatelet therapy with anti-serotonergic agents. PMID:22384279

  15. 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.

  16. Gum resin of Boswellia serrata inhibited human monocytic (THP-1) cell activation and platelet aggregation.

    Science.gov (United States)

    Kokkiripati, Praveen K; Bhakshu, Lepakshi Md; Marri, Swathi; Padmasree, K; Row, Anupama T; Raghavendra, Agepati S; Tetali, Sarada D

    2011-09-01

    Stem bark gum resin extract of Boswellia serrata is traditionally used in India for its hemostatic, antiinflammatory and cardiovascular health effects and it is named as Śallakī in Ayurvedic medicine. This study was conducted to evaluate the antioxidative and antithrombotic properties of stem bark gum resin extracts of Boswellia serrata (BS). The inhibitory activity of the BSWE and BSAE on FeCl(3) induced lipid peroxidation (in vitro) in rat liver and heart homogenates was measured spectrophotometrically. Their effect on H(2)O(2) induced reactive oxygen species (ROS) generation in human monocytic (THP-1) cells was investigated by tracking intensity of a cell permeable fluorescent dye, H(2)DCFDA and subjecting the cell samples to confocal microscopy. Further, the effect of BSAE and BSWE on ADP-induced platelet aggregation was assessed using a multimode detection plate reader, plasma coagulation times using an automated blood coagulation analyzer and on human blood clotting factors Xa and XIa using chromogenic substrate. Phytomarker analysis of the water (BSWE) and hydroalcoholic (BSAE) extracts of BS-gum resin was done through HPLC using a standard compound AKβBA. BSAE and BSWE inhibited, to varied extents, the lipid peroxidation in liver (80%) and heart (50%) tissue homogenates of male Wistar rats. Further, BSAE (30 μg dwt/mL) and BSWE (300 μg dwt/mL) attenuated ≥ 60% of H(2)O(2) mediated ROS generation in THP-1 cells. In case of standard compounds, ascorbate (20 μg dwt/mL) and butylated hydroxytoluene (BHT) (10 μg dwt/mL) completely scavenged ROS in the cells. BSAE and BSWE at 3 mg dwt/mL completely inhibited ADP induced platelet aggregation and activities were comparable to 20 μg/mL of heparin. The extracts also showed very high activity in prolonging coagulation time periods. Both types of extracts extended prothrombin time (PT) from ∼13 to >60s and activated partial thromboplastin time (APTT) from ∼32s to >90s. BSAE inhibited clotting factors Xa

  17. Aspirin and P2Y12 inhibition attenuate platelet-induced ovarian cancer cell invasion.

    LENUS (Irish Health Repository)

    Cooke, Niamh M

    2015-09-09

    Platelet-cancer cell interactions play a key role in successful haematogenous metastasis. Disseminated malignancy is the leading cause of death among ovarian cancer patients. It is unknown why different ovarian cancers have different metastatic phenotypes. To investigate if platelet-cancer cell interactions play a role, we characterized the response of ovarian cancer cell lines to platelets both functionally and at a molecular level.

  18. The effect of the phytoestrogen genistein on plasma nitric oxide concentrations, endothelin-1 levels and endothelium dependent vasodilation in postmenopausal women.

    Science.gov (United States)

    Squadrito, Francesco; Altavilla, Domenica; Morabito, Nunziata; Crisafulli, Alessandra; D'Anna, Rosario; Corrado, Francesco; Ruggeri, Pietro; Campo, Giuseppe M; Calapai, Gioacchino; Caputi, Achille P; Squadrito, Giovanni

    2002-08-01

    The phytoestrogen genistein improves endothelial dysfunction in ovariectomized rats through a nitric oxide-dependent mechanism. We investigated whether genistein alters the balance between the nitric oxide products and endothelin-1 and influences endothelium-dependent vasodilation in postmenopausal women. Sixty healthy postmenopausal women were enrolled in the study. A double-blind, placebo controlled, randomized design was employed. After a 4-week stabilization on a standard fat-reduced diet, participants to the study were randomly assigned to receive either genistein (n=30; 54 mg/day) or placebo (n=30). Flow-mediated, endothelium-dependent vasodilation of the brachial artery, plasma nitric oxide breakdown products and endothelin-1 levels were measured at baseline and after 6 months of genistein therapy. The mean baseline level of nitrites/nitrates was 22+/-10 micromol/l and increased to 41+/-10 micromol/ml after 6 months of treatment. The mean baseline plasma endothelin-1 level was 14+/-4 pg/ml and decreased to 7+/-1 pg/ml following 6 months of treatment with genistein. The mean baseline ratio of nitric oxide to endothelin also significantly increased at the end of treatment. Flow-mediated, endothelium-dependent vasodilation of the brachial artery was 3.9+/-0.8 mm at baseline and increased to 4.4+/-0.7 mm after 6 months of treatment. Placebo-treated women showed no changes in plasma nitrites/nitrates, endothelin-1 levels and flow-mediated vasodilation. Genistein therapy improves flow-mediated endothelium dependent vasodilation in healthy postmenopausal women. This improvement may be mediated by a direct effect of genistein on the vascular function and could be the result of an increased ratio of nitric oxide to endothelin.

  19. Imatinib mesylate radiosensitizes human glioblastoma cells through inhibition of platelet-derived growth factor receptor.

    Science.gov (United States)

    Holdhoff, Matthias; Kreuzer, Karl-Anton; Appelt, Christine; Scholz, Regina; Na, Il-Kang; Hildebrandt, Bert; Riess, Hanno; Jordan, Andreas; Schmidt, Christian A; Van Etten, Richard A; Dörken, Bernd; le Coutre, Philipp

    2005-01-01

    Imatinib mesylate is a small molecule inhibitor of the c-Abl, platelet-derived growth factor (PDGF) receptor and c-Kit tyrosine kinases that is approved for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) and gastrointestinal stromal tumors. Glioblastoma multiforme is a highly malignant primary brain tumor that is usually treated with surgery and/or radiotherapy. Previous studies implicate an autocrine loop caused by high expression of PDGF and its receptor, PDGFR, in the proliferation of some glioblastomas. Here, we demonstrate that pretreatment of a human glioblastoma cell line, RuSi RS1, with imatinib significantly enhanced the cytotoxic effect of ionizing radiation. This effect was not seen in human breast cancer (BT20) and colon cancer (WiDr) cell lines. Whereas c-Abl and c-Kit were expressed about equally in the three cell lines, RuSi RS1 cells showed significantly higher expression of PDGFR-beta protein in comparison to BT20 and WiDr. Imatinib treatment of RuSi RS1 cells decreased overall levels of cellular tyrosine phosphorylation and specifically inhibited phosphorylation of PDGFR-beta, while c-Abl was not prominently activated in these cells. These results suggest that imatinib may have clinical utility as a radiosensitizer in the treatment of human glioblastoma, possibly through disruption of an autocrine PDGF/PDGFR loop.

  20. /sup 3/H-PAF-acether displacement and inhibition of binding in intact human platelets by BN 52021

    Energy Technology Data Exchange (ETDEWEB)

    Korth, R.; Le Couedic, J.P.; Benveniste, J.

    1986-03-05

    Intact washed human platelets incubated at 20/sup 0/C in Tyrode's buffer containing 0.25% (w/v) bovine serum albumin bound /sup 3/H paf-acether in a concentration (0-6.5 nM) and time (0-60 min) dependent manner (n=3). BN 52021 (60 ..mu..M) a chemically defined extract from Ginkgo biloba inhibited the binding of increasing concentrations of /sup 3/H paf-acether. Calculated differences between /sup 3/H paf-acether binding in the presence or absence of BN 52021 (60 ..mu..M) reached nearly a plateau in concentrations higher than 0.65 nM /sup 3/H paf-acether. Increasing concentrations of BN 52021 (0-60 ..mu..M) as well as of unlabelled paf-acether (0-50 nM) prevented within 15 min /sup 3/H paf-acether binding (0.65 nM) to platelets in a concentration-dependent way. Increasing BN 52021 concentrations (0-60 ..mu..M) also displaced platelet-bound /sup 3/H paf-acether (0.65 nM) in a concentration-dependent way. Displacement increased with the time length of platelet incubation with BN 52021 and reached a plateau at 15 min. Platelet-bound /sup 3/H paf-acether displacement of 28.3 +/- 6.3%, 31.1 +/- 4.0% and 26.7 +/- 5.6% was observed using 50 nM unlabelled paf-acether, 60 ..mu..M BN 52021 or both substances together (vs 4.3 +/- 7.2% for vehicle alone). No degradation of /sup 3/H paf-acether occurred as assessed by high pressure liquid chromatography. These results demonstrate that BN 52021 competes directly with paf-acether binding sites on human platelets.

  1. Ticagrelor versus clopidogrel in acute coronary syndromes in relation to renal function: results from the Platelet Inhibition and Patient Outcomes (PLATO) trial

    National Research Council Canada - National Science Library

    James, Stefan; Budaj, Andrzej; Aylward, Philip; Buck, Kristen K; Cannon, Christopher P; Cornel, Jan H; Harrington, Robert A; Horrow, Jay; Katus, Hugo; Keltai, Matyas; Lewis, Basil S; Parikh, Keyur; Storey, Robert F; Szummer, Karolina; Wojdyla, Daniel; Wallentin, Lars

    2010-01-01

    .... In the Platelet Inhibition and Patient Outcomes (PLATO) trial, ticagrelor compared with clopidogrel reduced the primary composite end point of cardiovascular death, myocardial infarction, and stroke at 12 months but with similar major bleeding rates...

  2. Sorafenib inhibits imatinib-resistant KIT and platelet-derived growth factor receptor beta gatekeeper mutants.

    Science.gov (United States)

    Guida, Teresa; Anaganti, Suresh; Provitera, Livia; Gedrich, Richard; Sullivan, Elizabeth; Wilhelm, Scott M; Santoro, Massimo; Carlomagno, Francesca

    2007-06-01

    Targeting of KIT and platelet-derived growth factor receptor (PDGFR) tyrosine kinases by imatinib is an effective anticancer strategy. However, mutations of the gatekeeper residue (T670 in KIT and T681 in PDGFRbeta) render the two kinases resistant to imatinib. The aim of this study was to evaluate whether sorafenib (BAY 43-9006), a multitargeted ATP-competitive inhibitor of KIT and PDGFR, was active against imatinib-resistant KIT and PDGFRbeta kinases. We used in vitro kinase assays and immunoblot with phosphospecific antibodies to determine the activity of sorafenib on KIT and PDGFRbeta kinases. We also exploited reporter luciferase assays to measure the effects of sorafenib on KIT and PDGFRbeta downstream signaling events. The activity of sorafenib on interleukin-3-independent proliferation of Ba/F3 cells expressing oncogenic KIT or its imatinib-resistant T670I mutant was also tested. Sorafenib efficiently inhibited gatekeeper mutants of KIT and PDGFRbeta (IC(50) for KIT T670I, 60 nmol/L; IC(50) for PDGFRbeta T681I, 110 nmol/L). Instead, it was less active against activation loop mutants of the two receptors (IC(50) for KIT D816V, 3.8 micromol/L; IC(50) for PDGFRbeta D850V, 1.17 micromol/L) that are also imatinib-resistant. Sorafenib blocked receptor autophosphorylation and signaling of KIT and PDGFRbeta gatekeeper mutants in intact cells as well as activation of AP1-responsive and cyclin D1 gene promoters, respectively. Finally, the compound inhibited KIT-dependent proliferation of Ba/F3 cells expressing the oncogenic KIT mutant carrying the T670I mutation. Sorafenib might be a promising anticancer agent for patients carrying KIT and PDGFRbeta gatekeeper mutations.

  3. C-type natriuretic peptide inhibits leukocyte recruitment and platelet-leukocyte interactions via suppression of P-selectin expression

    Science.gov (United States)

    Scotland, Ramona S.; Cohen, Marc; Foster, Paul; Lovell, Matthew; Mathur, Anthony; Ahluwalia, Amrita; Hobbs, Adrian J.

    2005-10-01

    The multifaceted process of immune cell recruitment to sites of tissue injury is key to the development of an inflammatory response and involved in the pathogenesis of numerous cardiovascular disorders. We recently identified C-type natriuretic peptide (CNP) as an important endothelium-derived mediator that regulates vascular tone and protects against myocardial ischemia/reperfusion injury. Herein, we investigated whether CNP inhibits leukocyte recruitment and platelet aggregation and thereby exerts a potential antiinflammatory influence on the blood vessel wall. We assessed the effects of CNP on leukocyte-endothelial cell interactions in mouse mesenteric postcapillary venules in vivo in animals with high basal leukocyte activation (endothelial nitric oxide synthase knockout mice, eNOS-/-) or under acute inflammatory conditions (induced by interleukin-1 or histamine). CNP suppressed basal leukocyte rolling in eNOS-/- mice in a rapid, reversible, and concentration-dependent manner. These effects of CNP were mimicked by the selective natriuretic peptide receptor-C agonist cANF4-23. CNP also suppressed leukocyte rolling induced by IL-1 or histamine, inhibited platelet-leukocyte interactions, and prevented thrombin-induced platelet aggregation of human blood. Furthermore, analysis of human umbilical vein endothelial cells, leukocytes, and platelets revealed that CNP selectively attenuates expression of P-selectin. Thus, CNP is a modulator of acute inflammation in the blood vessel wall characterized by leukocyte and platelet activation. These antiinflammatory effects appear to be mediated, at least in part, via suppression of P-selectin expression. These observations suggest that endothelial CNP might maintain an anti-atherogenic influence on the blood vessel wall and represent a target for therapeutic intervention in inflammatory cardiovascular disorders. endothelium | natriuretic peptide receptor type C | atherosclerosis | thrombosis

  4. Low-flow mediated constriction is endothelium-dependent: effects of exercise training after radial artery catheterization.

    Science.gov (United States)

    Dawson, Ellen A; Alkarmi, Amr; Thijssen, Dick H J; Rathore, Sudhir; Marsman, Diane E; Cable, N Timothy; Wright, D Jay; Green, Daniel J

    2012-10-01

    Radial artery catheterization is associated with endothelial denudation and impaired vasodilator function, while postcatheterization exercise training may enhance artery function. The impact of catheterization and subsequent exercise training on low-flow mediated vasoconstriction (L-FMC) has not previously been studied. The aim of this study was to examine whether radial artery L-FMC is impaired by catheterization and consequent endothelial denudation. A further aim was to examine the effect of local handgrip exercise training on radial artery L-FMC and flow-mediated dilation (FMD) after transradial catheterization. Thirty-two subjects undergoing transradial catheterization underwent assessment of L-FMC and FMD in the catheterized and contralateral radial artery before, and the day after, catheterization. A further 18 patients were recruited and randomly assigned to either a 6-week handgrip exercise training program (N=9) or a nonexercise control period (N=9). L-FMC was attenuated 1 day postcatheterization in the catheterized arm (-2.07±0.84 to 0.35±0.83), but unchanged in the noncatheterized arm (-0.93±0.86 to -0.90±0.92; P<0.05). In the training study, both FMD and L-FMC of the catheterized arm were preserved in the exercise group 7 weeks after catheterization (FMD-pre, 6.84±0.79; FMD-post, 6.85±1.16; L-FMC-pre, -2.14±1.42; L-FMC-post, -3.58±1.04%), but reduced in the control group (FMD-pre, 8.27±1.52; FMD-post, 4.66±0.70; P=0.06; L-FMC-pre, -3.26±1.19; L-FMC-post, -1.34±1.27%; P<0.05). Catheterization, and associated endothelial denudation, decreases L-FMC in the radial artery, suggesting that it is endothelium-dependent. Moreover, we demonstrate for the first time that exercise training has beneficial impacts on radial artery vasodilator and constrictor function.

  5. Assessment of endothelium: Dependent vasodilation with a non-invasive method in patients with preeclampsia compared to normotensive pregnant women

    Directory of Open Access Journals (Sweden)

    Seyedeh Zahra Allameh

    2014-01-01

    Full Text Available Background: To assess the endothelial function via noninvasive method, in pregnant women with preeclampsia compared to to normotensive pregnant women. Materials and Methods: Brachial artery diameter was measured via ultrasound, in 28 women with preeclampcia in case group and normotensive pregnant women in control group, at rest, after inflation of sphygmomanometer cuff up to 250-300 mmHg, immediately after deflation of the cuff, 60-90 minutes later and 5 min after administration of sublingual trinitroglycerin (TNG. Results of these measurements as well as demographic characteristics of participants in both groups were recorded in special forms. Data were analyzed via Statistical Package for Social Sciences (SPSS version 16, using t-test and repeated measures analysis of variance (ANOVA. P-value < 0.05 was considered statistically significant. The results were presented as mean ± standard deviation (SD. Results: The mean of brachial artery diameter at rest in the case and control groups was 4.49 ± 0.39 and 4.08 ± 0.38 mm, respectively (P = 0.1. Also the results showed that the brachial artery diameter, immediately after deflation of the cuff, was 4.84 ± 0.4 and 4.37 ± 0.30 mm in the case and control groups (P < 0.001, respectively. The mean brachial artery diameter, 60-90 s after deflation of the cuff, was 4.82 ± 0.41 and 4.42 ± 0.38 mm in the case and control groups (P < 0.00, respectively. The brachial artery diameter, 5 min after sublingual NO administration, was 4.95 ± 0.6 and 4.40 ± 0.45 mm in case and control groups (P < 0.001, respectively. Applying of repeated measures ANOVA showed that the mean difference between case and control groups was statistically significant (P < 0.001. Conclusion: Current study concluded that there is no difference in endothelium-dependent vasodilation between women with preeclampsia and pregnant women with normal blood pressure.

  6. TRA-418, a thromboxane A2 receptor antagonist and prostacyclin receptor agonist, inhibits platelet-leukocyte interaction in human whole blood.

    Science.gov (United States)

    Miyamoto, Mitsuko; Ohno, Michihiro; Yamada, Naohiro; Ohtake, Atsushi; Matsushita, Teruo

    2010-10-01

    TRA-418, a compound with both thromboxane A2 receptor (TP receptor) antagonistic and prostacyclin receptor (IP receptor) agonistic activities, was synthesised in our laboratory as a new antithrombotic agent. In this study, we examined the effects of TRA-418 on platelet-leukocyte interactions in human whole blood. Platelet-leukocyte interactions were induced by U-46619 in the presence of epinephrine (U-46619 + epinephrine) or with thrombin receptor agonist peptide 1-6 (TRAP). Platelet-leukocyte interactions were assessed by flow cytometry, with examination of both platelet-neutrophil and platelet-monocyte complexes. In a control experiment, the TP receptor antagonist SQ-29548 significantly inhibited the induction of platelet-leukocyte complexes by the combination of U-46619 and epinephrine, but not TRAP-induced formation of platelet-leukocyte complexes. Conversely, the IP receptor agonist beraprost sodium inhibited platelet-leukocyte complex formation induced by both methods, although the IC50 values of beraprost sodium for U-46619 + epinephrine were at least 10-fold greater than for TRAP. Under such conditions, TRA-418 inhibited both U-46619 + epinephrine-induced and TRAP-induced platelet-leukocyte complex formation in a concentration-dependent manner, in a similar range. These results suggest that TRA-418 exerts its inhibitory effects on platelet-leukocyte interactions by acting as a TP receptor antagonist as well as an IP receptor agonist in an additive or synergistic manner. These inhibitory effects of TRA-418 on formation of platelet-leukocyte complexes suggest the compound is beneficial effects as an antithrombotic agent.

  7. Total steroidal alkaloids from Veratrum patulum L. Inhibit platelet aggregation, thrombi formation and decrease bleeding time in rats.

    Science.gov (United States)

    Song, Qiling; Wang, Shisheng; Zhao, Weijie

    2012-05-07

    Veratrum patulum L. (Liliaceae) is used as one source of the Chinese traditional drug "Lilu" which has been used in the treatment of aphasia arising from apoplexy, wind type dysentery, headache, etc. for thousands of years. To evaluate the antithrombotic effect of Veratrum patulum L. (Liliaceae) total steroidal alkaloids (VpA) and explore the potential mechanisms. The antithrombotic effect of VpA was evaluated in two experimental thrombosis models in rat. The potential antithrombotic mechanisms of VpA were explored by determining the coagulation parameters and platelet aggregation induced by various agonists. Cutting-tail rat model was used to evaluate the influence of VpA on bleeding time. VpA significantly inhibit the formation of arterial and venous thrombosis and showed different inhibitory effect on the platelet aggregation induced by various agonists with the following potency order: collagen>ADP>thrombin. VpA showed no influence on the coagulation parameters in rat. But VpA decreased the cutting-tail bleeding time in rat. VpA possess antithrombotic effect on venous and arterial thrombosis. The antithrombotic effect of VpA is due to its inhibition to platelet aggregation, especially induced by collagen. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. All-trans-Retinoic Acid Ameliorated High Fat Diet-Induced Atherosclerosis in Rabbits by Inhibiting Platelet Activation and Inflammation

    Directory of Open Access Journals (Sweden)

    Birong Zhou

    2012-01-01

    Full Text Available Background. All-trans-retinoic acid (atRA is effective for many proliferative diseases. We investigated the protective effects of atRA against atherosclerosis. Methods. Rabbits were randomly allocated to receive basal diet or an HFD for 4 weeks. HFD group then received rosuvastatin (3 mg/day, atRA (5 mg/kg/day, or the same volume of vehicle, respectively, for next 8 weeks. Results. HFD group showed increases in plasma lipids and aortic plaque formation. P-selectin expression and fibrinogen binding on platelets or deposition on the intima of the aorta also increased significantly as did the levels of TNF-α, IL-6, and fibrinogen in plasma. After 8 weeks of treatment with atRA, there was a significant decrease in plasma lipids and improvement in aortic lesions. AtRA also inhibited the expression of P-selectin and fibrinogen binding on platelets and deposition on the intima of the aorta. Conclusion. AtRA can ameliorate HFD-induced AS in rabbits by inhibiting platelet activation and inflammation.

  9. Ticagrelor compared with clopidogrel by geographic region in the Platelet Inhibition and Patient Outcomes (PLATO) trial.

    Science.gov (United States)

    Mahaffey, Kenneth W; Wojdyla, Daniel M; Carroll, Kevin; Becker, Richard C; Storey, Robert F; Angiolillo, Dominick J; Held, Claes; Cannon, Christopher P; James, Stefan; Pieper, Karen S; Horrow, Jay; Harrington, Robert A; Wallentin, Lars

    2011-08-02

    In the Platelet Inhibition and Patient Outcomes (PLATO) trial, a prespecified subgroup analysis showed a significant interaction between treatment and region (P=0.045), with less effect of ticagrelor in North America than in the rest of the world. Reasons for the interaction were explored independently by 2 statistical groups. Systematic errors in trial conduct were investigated. Statistical approaches evaluated the likelihood of play of chance. Cox regression analyses were performed to quantify how much of the regional interaction could be explained by patient characteristics and concomitant treatments, including aspirin maintenance therapy. Landmark Cox regressions at 8 time points evaluated the association of selected factors, including aspirin dose, with outcomes by treatment. Systematic errors in trial conduct were ruled out. Given the large number of subgroup analyses performed and that a result numerically favoring clopidogrel in at least 1 of the 4 prespecified regions could occur with 32% probability, chance alone cannot be ruled out. More patients in the United States (53.6%) than in the rest of the world (1.7%) took a median aspirin dose ≥300 mg/d. Of 37 baseline and postrandomization factors explored, only aspirin dose explained a substantial fraction of the regional interaction. In adjusted analyses, both Cox regression with median maintenance dose and landmark techniques showed that, in patients taking low-dose maintenance aspirin, ticagrelor was associated with better outcomes compared with clopidogrel, with statistical superiority in the rest of the world and similar outcomes in the US cohort. The regional interaction could arise from chance alone. Results of 2 independently performed analyses identified an underlying statistical interaction with aspirin maintenance dose as a possible explanation for the regional difference. The lowest risk of cardiovascular death, myocardial infarction, or stroke with ticagrelor compared with clopidogrel is

  10. Tissue-engineered endothelial cell layers on surface-modified Ti for inhibiting in vitro platelet adhesion

    Directory of Open Access Journals (Sweden)

    Xiupeng Wang, Fupo He, Xia Li, Atsuo Ito, Yu Sogo, Osamu Maruyama, Ryo Kosaka and Jiandong Ye

    2013-01-01

    Full Text Available A tissue-engineered endothelial layer was prepared by culturing endothelial cells on a fibroblast growth factor-2 (FGF-2–l-ascorbic acid phosphate magnesium salt n-hydrate (AsMg–apatite (Ap coated titanium plate. The FGF-2–AsMg–Ap coated Ti plate was prepared by immersing a Ti plate in supersaturated calcium phosphate solutions supplemented with FGF-2 and AsMg. The FGF-2–AsMg–Ap layer on the Ti plate accelerated proliferation of human umbilical vein endothelial cells (HUVECs, and showed slightly higher, but not statistically significant, nitric oxide release from HUVECs than on as-prepared Ti. The endothelial layer maintained proper function of the endothelial cells and markedly inhibited in vitro platelet adhesion. The tissue-engineered endothelial layer formed on the FGF-2–AsMg–Ap layer is promising for ameliorating platelet activation and thrombus formation on cardiovascular implants.

  11. Coadministration of ticagrelor and ritonavir: Toward prospective dose adjustment to maintain an optimal platelet inhibition using the PBPK approach.

    Science.gov (United States)

    Marsousi, N; Samer, C F; Fontana, P; Reny, J L; Rudaz, S; Desmeules, J A; Daali, Y

    2016-09-01

    Ticagrelor is a potent antiplatelet drug metabolized by cytochrome (CYP)3A. It is contraindicated in patients with human immunodeficiency virus (HIV) because of the expected CYP3A inhibition by most protease inhibitors, such as ritonavir and an increased bleeding risk. In this study, a physiologically based pharmacokinetic (PBPK) model was created for ticagrelor and its active metabolite (AM). Based on the simulated interaction between ticagrelor 180 mg and ritonavir 100 mg, a lower dose of ticagrelor was calculated to obtain, when coadministered with ritonavir, the same pharmacokinetic (PK) and platelet inhibition as ticagrelor administered alone. A clinical study was thereafter conducted in healthy volunteers. Observed PK profiles of ticagrelor and its AM were successfully predicted with the model. Platelet inhibition was nearly complete in both sessions despite administration of a fourfold lower dose of ticagrelor in the second session. This PBPK model could be prospectively used to broaden the usage of ticagrelor in patients with ritonavir-treated HIV regardless of the CYP3A inhibition. © 2016 American Society for Clinical Pharmacology and Therapeutics.

  12. Platelet inhibition and endothelial cell adhesion on elastin-like polypeptide surface modified materials.

    Science.gov (United States)

    Blit, Patrick H; McClung, W Glenn; Brash, John L; Woodhouse, Kimberly A; Santerre, J Paul

    2011-09-01

    Platelet adhesion and activation are important early markers of biomaterial blood compatibility, while surfaces that promote enhanced endothelial cell adhesion and eNOS expression are strategic targets for long term vascular graft applications. Materials surface modified with fluorinated surface modifiers, containing peptides inspired from elastin cross-linking domains, have been used for the cross-linking of elastin-like polypeptide 4 (ELP4) macromolecules onto polyurethane surfaces. In the present study, ELP4 modified polyurethanes were evaluated in vitro to assess platelet adhesion, microparticle formation and bulk platelet activation following blood-material interactions. Reduced platelet adhesion and bulk platelet activation were observed following contact between reconstituted human blood and the ELP4 materials, relative to the uncoated base polyurethane controls. ELP4 modified materials also promoted endothelial cell adhesion and retention over a period of one week and showed that the endothelial cells exhibited an organized actin cytoskeleton and enhanced endothelial nitric oxide synthase (eNOS) expression relative to the control surfaces. These results indicate that polyurethane elastomers modified with ELP4 covalently bound to fluorinated surface modifiers provide a promising approach for endowing synthetic elastomers with both reduced blood platelet activation properties and enhanced endothelial cell adhesion for potential use in vascular graft applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Clinical impact of enhanced inhibition of P2Y12-mediated platelet aggregation in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention.

    Science.gov (United States)

    Capranzano, Piera; Mehran, Roxana; Tamburino, Corrado; Stone, Gregg W; Dangas, George

    2010-11-01

    The combination of aspirin and clopidogrel at a loading dose of 300 mg followed by a maintenance dose of 75 mg daily is a well-established antiplatelet therapy for the secondary prevention of thrombotic complications in the settings of acute coronary syndrome and/or percutaneous coronary intervention (PCI). Despite the demonstrated clinical benefits associated with this antiplatelet therapy, there is accumulating evidence that a consistent proportion of patients persist in having high levels of platelet aggregation following standard clopidogrel dose. Importantly, the high platelet reactivity after clopidogrel treatment has been associated with higher risk for cardiovascular ischemic events, including stent thrombosis. This has warranted the need for alternative oral antiplatelet regimens that achieve a higher degree of platelet inhibition. Several functional studies have shown that a higher clopidogrel loading dose (600 mg) compared with standard dose, and novel oral adenosine diphosphate platelet receptor (P2Y12) antagonists compared with clopidogrel achieve a faster onset of action, increased platelet inhibition, and a more predictable drug response. These more favorable pharmacodynamic characteristics are of particular interest in the setting of primary PCI for ST-segment elevation myocardial infarction (STEMI), in which rapid and consistent inhibition of platelet activation and aggregation is desirable for therapeutic success. The present article reviews data on the clinical impact of enhanced P2Y12 inhibition with either higher clopidogrel dosing or new oral antiplatelet agents, including prasugrel and ticagrelor, in the setting of STEMI, focusing on results in the setting of primary PCI.

  14. Enhanced ex vivo inhibition of platelet function following addition of dipyridamole to aspirin after transient ischaemic attack or ischaemic stroke: first results from the TRinity AntiPlatelet responsiveness (TrAP) study.

    LENUS (Irish Health Repository)

    Tobin, William Oliver

    2012-02-01

    Ex vivo dipyridamole \\'non-responsiveness\\' has not been extensively studied in ischaemic cerebrovascular disease. Platelet surface marker expression, leucocyte-platelet complex formation and inhibition of platelet function at high shear stress as detected by the PFA-100(R) Collagen-Adenosine-diphosphate (C-ADP) and Collagen-Epinephrine cartridges was assessed in 52 patients within 4 weeks of transient ischaemic attack (TIA) or ischaemic stroke on aspirin, and then 14 d (14 d) and >90 d (90 d) after adding dipyridamole. A novel definition of \\'Dipyridamole non-responsiveness\\' was used. The median C-ADP closure time increased following addition of dipyridamole, remained elevated at 90 d (P <\\/= 0.03), and was unaffected by aspirin dose. 59% at 14 d and 56% at 90 d were \\'dipyridamole non-responders\\' on the PFA-100. The proportion of non-responders at 14 and 90 d was similar (P= 0.9). Compared with baseline (4.6%), median monocyte-platelet complexes increased at 14 d (5.0%, P= 0.03) and 90 d (4.9%, P= 0.04). Low C-ADP closure times were associated with increased monocyte-platelet complexes at 14 d (r= -0.32, P= 0.02) and 90 d (r= -0.33, P = 0.02). Monocyte-platelet complexes increased in the subgroup of dipyridamole non-responders on the PFA-100 (P<\\/= 0.045), but not in responders (P >\\/= 0.5), at 14 and 90 d versus baseline. Additional inhibition of platelet function has been detected with the PFA-100 when dipyridamole is added to aspirin. Elevated monocyte-platelet complexes may contribute to ex vivo dipyridamole non-responsiveness.

  15. Pregnancy-specific glycoproteins bind integrin αIIbβ3 and inhibit the platelet-fibrinogen interaction.

    Directory of Open Access Journals (Sweden)

    Daniel K Shanley

    Full Text Available Pregnancy-specific glycoproteins (PSGs are immunoglobulin superfamily members encoded by multigene families in rodents and primates. In human pregnancy, PSGs are secreted by the syncytiotrophoblast, a fetal tissue, and reach a concentration of up to 400 ug/ml in the maternal bloodstream at term. Human and mouse PSGs induce release of anti-inflammatory cytokines such as IL-10 and TGFβ1 from monocytes, macrophages, and other cell types, suggesting an immunoregulatory function. RGD tri-peptide motifs in the majority of human PSGs suggest that they may function like snake venom disintegrins, which bind integrins and inhibit interactions with ligands. We noted that human PSG1 has a KGD, rather than an RGD motif. The presence of a KGD in barbourin, a platelet integrin αIIbβ3 antagonist found in snake venom, suggested that PSG1 may be a selective αIIbβ3 ligand. Here we show that human PSG1 binds αIIbβ3 and inhibits the platelet - fibrinogen interaction. Unexpectedly, however, the KGD is not critical as multiple PSG1 domains independently bind and inhibit αIIbβ3 function. Human PSG9 and mouse Psg23 are also inhibitory suggesting conservation of this function across primate and rodent PSG families. Our results suggest that in species with haemochorial placentation, in which maternal blood is in direct contact with fetal trophoblast, the high expression level of PSGs reflects a requirement to antagonise abundant (3 mg/ml fibrinogen in the maternal circulation, which may be necessary to prevent platelet aggregation and thrombosis in the prothrombotic maternal environment of pregnancy.

  16. Effect of proton pump inhibitors on platelet inhibition activity of clopidogrel in Chinese patients with percutaneous coronary intervention

    Directory of Open Access Journals (Sweden)

    Kwan T

    2011-06-01

    Full Text Available Joanne Kwan1, Wah Wah Htun2, Yili Huang3, Wilson Ko3, Tak W Kwan31Boston University, Boston, MA, USA; 2Lutheran Medical Center, Brooklyn, NY, USA; 3Beth Israel Medical Center, New York, NY, USABackground: The purpose of this study was to examine the effect of proton pump inhibitors (PPI on the antiplatelet activity of clopidogrel in a consecutive series of Chinese patients after they had received coronary stents.Methods: A sample of 51 consecutive Chinese patients treated with coronary stents and taking PPI and clopidogrel for more than 30 days were enrolled in this study. Mean values for platelet residual units and percentage inhibition before PPI (+PPI and 14 days after discontinuation of PPI (-PPI were compared using the paired t-test.Results: There was no effect of concomitant use of esomeprazole and clopidogrel or omeprazole and clopidogrel on the inhibition assay, but platelet residual units and percentage inhibition showed statistically significant improvement after stopping lansoprazole in Chinese patients who were on chronic clopidogrel therapy. Clopidogrel resistance existed more frequently in the Chinese-American population examined, and was as high as 68% (+PPI to 73% (-PPI.Conclusion: The clopidogrel resistance found is cause for concern, although its relationship with clinical events is currently unknown in this population. Further study with other thienopyridines or genetic variant analysis is suggested.Keywords: proton pump inhibitors, clopidogrel resistance, Chinese population, percutaneous coronary intervention

  17. Function of Platelet-Induced Epithelial Attachment at Titanium Surfaces Inhibits Microbial Colonization.

    Science.gov (United States)

    Maeno, M; Lee, C; Kim, D M; Da Silva, J; Nagai, S; Sugawara, S; Nara, Y; Kihara, H; Nagai, M

    2017-06-01

    The aim of this study was to evaluate the barrier function of platelet-induced epithelial sheets on titanium surfaces. The lack of functional peri-implant epithelial sealing with basal lamina (BL) attachment at the interface of the implant and the adjacent epithelium allows for bacterial invasion, which may lead to peri-implantitis. Although various approaches have been reported to combat bacterial infection by surface modifications to titanium, none of these have been successful in a clinical application. In our previous study, surface modification with protease-activated receptor 4-activating peptide (PAR4-AP), which induced platelet activation and aggregation, was successful in demonstrating epithelial attachment via BL and epithelial sheet formation on the titanium surface. We hypothesized that the platelet-induced epithelial sheet on PAR4-AP-modified titanium surfaces would reduce bacterial attachment, penetration, and invasion. Titanium surface was modified with PAR4-AP and incubated with platelet-rich plasma (PRP). The aggregated platelets released collagen IV, a critical BL component, onto the PAR4-AP-modified titanium surface. Then, human gingival epithelial cells were seeded on the modified titanium surface and formed epithelial sheets. Green fluorescent protein (GFP)-expressing Escherichia coli was cultured onto PAR4-AP-modified titanium with and without epithelial sheet formation. While Escherichia coli accumulated densely onto the PAR4-AP titanium lacking epithelial sheet, few Escherichia coli were observed on the epithelial sheet on the PAR4-AP surface. No bacterial invasion into the interface of the epithelial sheet and the titanium surface was observed. These in vitro results indicate the efficacy of a platelet-induced epithelial barrier that functions to prevent bacterial attachment, penetration, and invasion on PAR4-AP-modified titanium.

  18. Chewed ticagrelor tablets provide faster platelet inhibition compared to integral tablets: The inhibition of platelet aggregation after administration of three different ticagrelor formulations (IPAAD-Tica) study, a randomised controlled trial.

    Science.gov (United States)

    Venetsanos, Dimitrios; Sederholm Lawesson, Sofia; Swahn, Eva; Alfredsson, Joakim

    2017-01-01

    To provide pharmacodynamic data of crushed and chewed ticagrelor tablets, in comparison with standard integral tablets. Ninety nine patients with stable angina were randomly assigned, in a 3:1:1 fashion, to one of the following 180mg ticagrelor loading dose (LD) formulations: A) Integral B) Crushed or C) Chewed tablets. Platelet reactivity (PR) was assessed with VerifyNow before, 20 and 60min after LD. High residual platelet reactivity (HRPR) was defined as >208 P2Y12 reaction units (PRU). There was no significant difference in PRU values at baseline. PRU 20min after LD were 237 (182-295), 112 (53-238) and 84 (29-129) and 60min after LD, 56 (15-150), 51 (18-85) and 9 (7-34) in integral, crushed and chewed ticagrelor LD, respectively (pticagrelor tablets resulted in significantly lower PRU values compared to crushed or integral tablets at 20 and 60min. Crushed ticagrelor LD resulted in significantly lower PRU values compared to integral tablets at 20min whereas no difference was observed at 60min. At 20min, no patients had HRPR with chewed ticagrelor compared to 68% with integral and 30% with crushed ticagrelor LD (pticagrelor tablets a more rapid platelet inhibition may be achieved, compared to standard integral tablets. We also show that administration of chewed tablets is feasible and provides faster inhibition than either crushed or integral tablets. European Clinical Trial Database (EudraCT number 2014-002227-96). Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Platelet Inhibition With Ticagrelor 60 mg Versus 90 mg Twice Daily in the PEGASUS-TIMI 54 Trial.

    Science.gov (United States)

    Storey, Robert F; Angiolillo, Dominick J; Bonaca, Marc P; Thomas, Mark R; Judge, Heather M; Rollini, Fabiana; Franchi, Francesco; Ahsan, Arif J; Bhatt, Deepak L; Kuder, Julia F; Steg, Philippe Gabriel; Cohen, Marc; Muthusamy, Rangasamy; Braunwald, Eugene; Sabatine, Marc S

    2016-03-15

    The PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis In Myocardial Infarction 54) trial studied 2 doses of ticagrelor, 90 mg twice a day (bid) and 60 mg bid, for long-term prevention of ischemic events in patients with prior myocardial infarction. Both doses similarly reduced the rate of ischemic events versus placebo. The pharmacokinetics and pharmacodynamics of ticagrelor 60 mg bid have not been studied. In this study, the authors sought to study the pharmacokinetics and pharmacodynamics for ticagrelor 60 mg compared with 90 mg bid. A total of 180 patients who received >4 weeks of study medication had blood sampling in the morning pre-maintenance dose and again 2 h post-dose. All patients received aspirin. Plasma levels of ticagrelor and its active metabolite AR-C124910XX were determined. P2Y12 inhibition was assessed by the VerifyNow P2Y12 assay (Accumetrics, Inc., San Diego, California) (P2Y12 reaction units [PRU]), light transmittance aggregometry (adenosine diphosphate 5 and 20 μmol/l and arachidonic acid), and vasodilator-stimulated phosphoprotein phosphorylation assays. VerifyNow Aspirin assays and serum thromboxane B2 measurements were performed. Mean pre- and post-dose plasma levels of ticagrelor were 35% and 38% lower, respectively, with 60 mg versus 90 mg. Both doses achieved high levels of platelet inhibition pre- and post-dose, with numerically slightly more variability with 60 mg: mean (SD) pre-dose PRU values were 59 ± 63 and 47 ± 43 for ticagrelor 60 and 90 mg, respectively (p = 0.34). High platelet reactivity, determined as PRU >208, was rare with the 60-mg pre-dose and was absent post-dose. Platelet reactivity pre- and post-dose, as measured by light transmittance aggregometry or vasodilator-stimulated phosphoprotein assays, was numerically but not significantly lower with 90 mg than with 60 mg. Aspirin response was not affected

  20. Partial inhibition of platelet thromboxane A2 synthesis by aspirin is associated with myonecrosis in patients with ST-segment elevation myocardial infarction.

    Science.gov (United States)

    Valles, Juana; Santos, M Teresa; Fuset, M Paz; Moscardo, Antonio; Ruano, Miguel; Perez, Francisca; Piñon, Marta; Breña, Silvia; Aznar, Justo

    2007-01-01

    Heterogeneity in response to aspirin (ASA) treatment, or "aspirin resistance," could be of importance in patients with ST-segment elevation myocardial infarction (STEMI). Decreased effects of ASA in platelets could be due to partial inhibition of cyclo-oxygenase-1 (COX-1) or to COX-1-independent mechanisms. We evaluated the effect of ASA treatment in patients with STEMI for (1) platelet thromboxane A(2) (TXA(2)) synthesis, (2) platelet recruitment elicited by TXA(2)-dependent and -independent mechanisms, and (3) a possible association of these aspects of platelet reactivity with serum markers of myonecrosis. We studied 62 ASA-treated patients within 48 hours of onset of the acute event and 69 ASA-free and 10 ASA-treated controls. TXA(2) synthesis and platelet recruitment (fluid-phase proaggregate activity of cell-free releasate) were assessed after collagen stimulation (1 micro g/ml) of whole blood. Partial inhibition of TXA(2) by ASA was found in 21 patients (34%). This was associated with significant increases in troponin T, creatine kinase-MB mass, creatine kinase, and recruiting activity versus 41 patients with blocked TXA(2) production. This was independent of fibrinolysis, and platelet COX-2 expression was not augmented. TXA(2) blockade was achieved after subsequent daily treatments or platelet incubation with ASA in vitro, suggesting lower sensitivity of COX-1 to ASA. In addition, 28 patients (45%) had an abnormally increased recruiting activity despite TXA(2) blockade, which was also associated with increased myonecrosis. In conclusion, ASA resistance, elicited by TXA(2)-dependent and TXA(2)-independent mechanisms, was prevalent in patients with STEMI. This study describes, for the first time, the association of partial platelet TXA(2) inhibition with myonecrosis.

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

    Directory of Open Access Journals (Sweden)

    Bonnie C Shaddinger

    Full Text Available 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.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.Lp-PLA2 inhibition does not enhance platelet aggregation.1 Study 1: ClinicalTrials.gov NCT01745458 2 Study 2: ClinicalTrials.gov NCT00387257.

  2. Nerve Growth Factor Inhibits Metalloproteinase-Disintegrins and Blocks Ectodomain Shedding of Platelet Glycoprotein VI*

    OpenAIRE

    Wijeyewickrema, Lakshmi C.; Gardiner, Elizabeth E.; Gladigau, Elsa L.; Berndt, Michael C; Andrews, Robert K

    2010-01-01

    Nerve growth factor (NGF) plays an important role in regulating mammalian neuronal/embryonic development, angiogenesis, and other physiological processes and has recently been investigated as a potential treatment for the neurodegenerative disorder, Alzheimer disease. In this study, we provide evidence that human NGF may also function as a metalloproteinase inhibitor, based on studies of NGF from snake venom. Originally, our aim was to isolate snake venom metalloproteinases targeting platelet...

  3. Acetaminophen and Meloxicam Inhibit Platelet Aggregation and Coagulation in Blood Samples from Humans

    Science.gov (United States)

    2014-01-01

    used for over 50 years to relieve pains associated with arthritis, headache, mus- cular aches, and to reduce fever in adults and children . As in most...of over-the- counter drugs such as aspirin , ibuprofen, herbal products, or nonsteroidal anti-inflammatory drugs within 7 days. Preparation of platelet...tinal bleeding and hemostatic disturbances, as compared with aspirin . However, some adverse effects of ibuprofen on coagulation have been recognized in

  4. Scutellarin attenuates endothelium-dependent aasodilation impairment induced by hypoxia reoxygenation, through regulating the PKG signaling pathway in rat coronary artery.

    Science.gov (United States)

    Chen, Ya-Juan; Wang, Lei; Zhou, Guang-Yu; Yu, Xian-Lun; Zhang, Yong-Hui; Hu, Na; Li, Qing-Qing; Chen, Chen; Qing, Chen; Liu, Ying-Ting; Yang, Wei-Min

    2015-04-01

    Scutellarin (SCU), a flavonoid from a traditional Chinese medicinal plant. Our previous study has demonstrated that SCU relaxes mouse aortic arteries mainly in an endothelium-depend-ent manner. In the present study, we investigated the vasoprotective effects of SCU against HR-induced endothelial dysfunction (ED) in isolated rat CA and the possible mechanisms involving cyclic guanosine monophosphate (cGMP) dependent protein kinase (PKG). The isolated endothelium-intact and endothelium-denuded rat CA rings were treated with HR injury. Evaluation of endothelium-dependent and -independent vasodilation relaxation of the CA rings were performed using wire myography and the protein expressions were assayed by Western blotting. SCU (10-1 000 μmol·L(-1)) could relax the endothelium-intact CA rings but not endothelium-denuded ones. In the intact CA rings, the PKG inhibitor, Rp-8-Br-cGMPS (PKGI-rp, 4 μmol·L(-1)), significantly blocked SCU (10-1 000 μmol·L(-1))-induced relaxation. The NO synthase (NOS) inhibitor, NO-nitro-L-arginine methylester (L-NAME, 100 μmol·L(-1)), did not significantly change the effects of SCU (10-1 000 μmol·L(-1)). HR treatment significantly impaired ACh-induced relaxation, which was reversed by pre-incubation with SCU (500 μmol·L(-1)), while HR treatment did not altered NTG-induced vasodilation. PKGI-rp (4 μmol·L(-1)) blocked the protective effects of SCU in HR-treated CA rings. Additionally, HR treatment reduced phosphorylated vasodilator-stimulated phosphoprotein (p-VASP, phosphorylated product of PKG), which was reversed by SCU pre-incubation, suggesting that SCU activated PKG phosphorylation against HR injury. SCU induces CA vasodilation in an endothelium-dependent manner to and repairs HR-induced impairment via activation of PKG signaling pathway. Copyright © 2015 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  5. Platelet-targeted microbubbles inhibit re-occlusion after thrombolysis with transcutaneous ultrasound and microbubbles.

    Science.gov (United States)

    Zhou, X B; Qin, H; Li, J; Wang, B; Wang, C B; Liu, Y M; Jia, X D; Shi, N

    2011-04-01

    Microbubbles (MBs) can augment the acoustic cavitation' (US), thereby facilitating the thrombolysis of external ultrasound. But we observed re-thrombosis after successful thrombolysis by MBs and transcutaneous ultrasound in an endothelium injury model. This study was designed to explore whether platelet-targeted MBs can prevent the reformation of thrombi. Arterial injury was induced in canine femoral arteries with balloon, and the arteries were completely thrombotically occluded. The arteries were treated with intra-arterial MBs or platelet-targeted MBs (TMB) and transcutaneous low frequency ultrasound (LFUS) to achieve complete thrombolysis. The arterial flow was monitored with angiogram for 4h following treatment. Results showed that both MBs and TMBs produced successful dissolution of clots in the presence of ultrasound. The re-occlusion began to occur 1h after thrombolysis in MB/LFUS treatment, and 7 of 8 arteries were re-occluded within 3h. Most of the arteries (7 of 8) in the TMB/LFUS group remained patent for 4h following treatment. The flow tended to decrease after thrombolysis in MB/LFUS treatment. These results indicated that platelet-targeted microbubbles were beneficial in preventing re-thrombosis in vivo and microbubbles served as good carrier of thrombolytic and anticoagulation drugs. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Chronic treatment with Vitamin D lowers arterial blood pressure and reduces endothelium-dependent contractions in the aorta of the SHR

    DEFF Research Database (Denmark)

    Wong, Michael S K; Delansorne, Remi; Svenningsen, Per

    2010-01-01

    Vitamin D has cardiovascular protective effects besides regulating calcium homeostasis. To examine the chronic in vivo effect of a physiological dose 1,25-dihydroxyvitamin D3 on the occurrence of endothelium-dependent contractions, spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY......) were treated with the vitamin D derivative for six weeks. The serum 1,25-dihydroxyvitamin D3 level of both treated WKY and SHR was significantly higher than in untreated rats while the mean arterial blood pressure of the treated SHR was significantly lower than that of control SHR. Aortic rings...... with or without endothelium were studied in conventional organ chambers for isometric force measurement. Confocal microscopy was used to measure the cytosolic-free calcium concentration (with the fluorescent dye Fluo-4) and reactive oxygen species (ROS; with dichlorodihydrofluorescein diacetate). Reverse...

  7. Endothelium-dependent modulation of cGMP levels and intrinsic smooth muscle tone in isolated bovine intrapulmonary artery and vein.

    Science.gov (United States)

    Ignarro, L J; Byrns, R E; Wood, K S

    1987-01-01

    The role of the endothelium in modulating cyclic nucleotide levels and intrinsic smooth muscle tone was studied in isolated rings of bovine intrapulmonary artery and vein. Cyclic 3',5'-guanosine monophosphate (cGMP) levels were threefold to fourfold higher in unrubbed artery and vein than in vessels that had been denuded of endothelium. Cyclic 3',5'-adenosine monophosphate (cAMP) levels were twofold higher in unrubbed than in endothelium-denuded artery, but no differences were observed in veins. Methylene blue, an inhibitor of guanylate cyclase, decreased cGMP but not cAMP levels, and this was accompanied by increases in smooth muscle tone. M&B 22,948, an inhibitor of cGMP-phosphodiesterase, increased cGMP but not cAMP levels, and this was accompanied by decreases in smooth muscle tone. Unrubbed vessels were more sensitive than endothelium-denuded vessels to the actions of both methylene blue and M&B 22,948, and this may be attributed to endothelium-dependent increases in cGMP turnover. Moreover, unrubbed vessels were more sensitive than endothelium-denuded vessels to contractile responses to phenylephrine and potassium, and these responses were potentiated by methylene blue and attenuated by M&B 22,948. Although indomethacin lowered cAMP levels in unrubbed artery, no changes in tone or contractile responsiveness were observed. A consistent observation was that the smaller branches of unrubbed but not endothelium-denuded intrapulmonary artery and vein had higher levels of cGMP but not cAMP, were sensitive to endothelium-dependent vasodilators, were more sensitive to methylene blue, and would not maintain a steady level of submaximal tone to phenylephrine when compared with larger branches from a common vascular bed.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Impact of selective platelet inhibition in reducing cardiovascular risk - role of vorapaxar

    Directory of Open Access Journals (Sweden)

    Cheng JWM

    2016-06-01

    Full Text Available Judy WM Cheng Department of Pharmacy Practice, MCPHS University, Boston, MA, USA Abstract: This article reviews the pharmacology, clinical efficacy, and safety of vorapaxar in reducing cardiovascular risk. Vorapaxar is a tricyclic himbacine-derived reversible inhibitor of platelet surface protease activator receptor-1, which prevents thrombin from activating platelets. Two Phase III clinical trials and multiple subanalyses from the two trials with vorapaxar have been published. In patients with recent acute coronary syndrome, vorapaxar, when added to standard therapy, did not reduce the composite cardiovascular end point. In contrary, in a study of secondary prevention for patients with cardiovascular diseases, vorapaxar reduced the risk of cardiovascular death or ischemic events (myocardial infarction, stroke in patients with stable atherosclerosis who were receiving standard therapy. Vorapaxar is approved in the US for use with aspirin and/or clopidogrel in the secondary prevention of thrombogenic cardiovascular events in stable patients with peripheral arterial disease or a history of myocardial infarction. Vorapaxar increases risk of bleeding and is contraindicated in patients with previous cerebrovascular events. It is essential to balance individual patient’s bleeding risk to any further cardiovascular benefits that they may get. Future investigation is also needed to evaluate use of vorapaxar with newer antiplatelet agents such as ticagrelor and cangrelor, as well as its role as monotherapy. Keywords: vorapaxar, protease activator receptor-1 antagonist, atherosclerotic disease

  9. Dipyrone (metamizole) markedly interferes with platelet inhibition by aspirin in patients with acute and chronic pain: A case-control study.

    Science.gov (United States)

    Schmitz, Andrea; Romann, Larissa; Kienbaum, Peter; Pavlaković, Goran; Werdehausen, Robert; Hohlfeld, Thomas

    2017-05-01

    Nonopioid analgesic drugs may interfere with platelet inhibition by aspirin. Recent in vitro and clinical studies in patients with cardiovascular disease have suggested that this pharmacodynamic interaction may also occur with dipyrone, a nonopioid analgesic popular in Europe, Asia and South America. Dipyrone is used extensively in acute and chronic pain. This study was undertaken to provide clinical data, so far missing, on its interactions in this group of patients. A case-control study. Primary care in one European university hospital centre. In total, 27 patients with stable cardiovascular, cerebrovascular or peripheral arterial disease and acute or chronic pain were identified and given dipyrone for at least 5 days in combination with low-dose aspirin. In total, 10 comparable patients on low-dose aspirin alone served as controls. Platelet-rich plasma was prepared to determine arachidonic acid-induced aggregation (aggregometry) and thromboxane formation (immunoassay). Platelet sensitivity to aspirin was examined in vitro. The presence of dipyrone (metabolites) in plasma was confirmed by HPLC. Additional in vitro measurements examined the aspirin/dipyrone interaction in healthy donors. Inhibition of aggregation was observed in only six of 27 patients receiving aspirin with dipyrone, with absence of complete inhibition by antiplatelet therapy showing in 78% of patients. In contrast, aggregation was completely inhibited in nine of 10 control patients (P < 0.001). Platelet thromboxane synthesis was higher in patients receiving dipyrone + aspirin compared with controls (387 ± 89 vs. 7 ± 1 ng ml, P < 0.001). Aspirin added in vitro failed to inhibit aggregation and thromboxane synthesis in platelet-rich plasma from dipyrone-treated patients. In vitro measurements with blood from healthy individuals confirmed that dipyrone dramatically reduces inhibition of platelet thromboxane synthesis by aspirin. Dipyrone given for 5 days or longer blunts

  10. Inhibition effect of tacrolimus and platelet-derived growth factor-BB on restenosis after vascular intimal injury.

    Science.gov (United States)

    Ma, Xu; Jiang, Chunyu; Li, Yuehua; Feng, Lishuai; Liu, Jingjing; Wang, Jianbo

    2017-09-01

    Excessive proliferation and migration of vascular smooth muscle cells(VSMCs) and delayed proliferation and migration of endothelial cells(ECs) were the main cause of restenosis after endovascular interventional therapy. Since tacrolimus has proved to be more sensitive to inhibiting VSMCs' proliferation,and platelet-derived growth factor-BB(PDGF-BB) benefitted ECs' and VSMCs' proliferation, this study was aimed to identify combined effect of tacrolimus and PDGF-BB, investigate any mechanisms underneath and demonstrate combined effect of two drugs in vivo. As the results showed we confirmed differential effect of PDGF-BB and tacrolimus on ECs and VSMCs. On the concentration level of 2-5μg/ml tacrolimus plus 10ng/ml PDGF-BB, combination of drugs could effectively promote ECs proliferation and migration, and meanwhile inhibit VSMCs proliferation and migration, and the inhibition of p-mTOR's expression within VSMCs played an important role in this differentiated effect. Raising concentration level of PDGF-BB would weaken inhibitory effect of tacrolimus on both kinds of cell. For injured intima, the mix solution of two drugs could promote intima healing and suppress excessive intimal hyperplasia. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. Acidic peptides enhanced genistein-dependent inhibition of human platelet aggregation: potential protective effect of digestible peptides plus genistein against atherosclerosis.

    Science.gov (United States)

    Borgwardt, Kerstin; Bonifatius, Susanne; Gardemann, Andreas

    2008-08-01

    The leading cause of death in the United States and European countries is coronary heart disease. We hypothesized that the ingestion of soy compounds may not only have beneficial effects on atherosclerotic risk by lowering lipid compounds, but also by reducing platelet aggregability. Therefore, we analyzed in vitro the influence of defined and digestible peptides, frequently found in glycinin and beta-conglycinin as important proteins of soy bean, on platelet aggregation of 180 healthy volunteers with or without the isoflavone genistein by aggregometry and flow cytometry. (i) The predominating share of amino acids and acidic, neutral, and basic di- and tripeptides of up to 2 mmol/L did not modify platelet aggregation induced by collagen, adenosine diphosphate, epinephrine, or arachidonic acid. (ii) Genistein inhibited agonist-induced platelet aggregation dose dependently. (iii) In the presence of the acidic peptides glutamate-glutamate and aspartate-aspartate-aspartate (1 mmol/L each), genistein reduced collagen- and ADP-dependent platelet activation stronger than 250 micromol/L of this isoflavone alone. Other peptides were less effective (eg, glutamate-glutamate-glutamate) or ineffective (eg, asparagine-asparagine). (iv) Glutamate-glutamate-glutamate (1 nmol/L), glutamate-glutamate (1 micromol/L), and aspartate-aspartate-aspartate (1 micromol/L) enhanced the inhibition of genistein on platelet aggregation induced by arachidonic acid. Thus, the results of the present in vitro investigation allow the assumption that nutrition with specific compounds of soy--acidic peptides together with genistein--might protect against coronary atherosclerosis by attenuating platelet activity. In vivo studies are warranted to check this assumption.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

  13. Novel Nanohybrids of Silver Particles on Clay Platelets for Inhibiting Silver-Resistant Bacteria

    Science.gov (United States)

    Su, Hong-Lin; Lin, Siou-Hong; Wei, Jiun-Chiou; Pao, I-Chuan; Chiao, Shu-Her; Huang, Chieh-Chen; Lin, Shinn-Zong; Lin, Jiang-Jen

    2011-01-01

    We develop a novel nanohybrid showing a strong antibacterial activity on all of the tested pathogens, including methicillin-resistant Staphylococcus auerus and silver-resistant E. coli. The nanohybrid consists of silver nanoparticles (AgNPs) supported on 1 nm-thick silicate platelets (NSPs). The AgNP/NSP nanohybrid enables to encapsulate bacteria and triggers death signals from the cell membrane. The geographic shape of the NSPs concentrates AgNPs but impedes their penetration into attached cells, mitigating the detrimental effect of silver ion deposition in applied tissues. Moreover, the tightly tethered AgNPs on NSP surface achieve a stronger biocidal effect than silver nitrate, but bypassing Ag+ mechanism, on silver-resistant bacteria. This nanohybrid presents an effective and safe antimicrobial agent in a new perspective. PMID:21695045

  14. Novel nanohybrids of silver particles on clay platelets for inhibiting silver-resistant bacteria.

    Directory of Open Access Journals (Sweden)

    Hong-Lin Su

    Full Text Available We develop a novel nanohybrid showing a strong antibacterial activity on all of the tested pathogens, including methicillin-resistant Staphylococcus auerus and silver-resistant E. coli. The nanohybrid consists of silver nanoparticles (AgNPs supported on 1 nm-thick silicate platelets (NSPs. The AgNP/NSP nanohybrid enables to encapsulate bacteria and triggers death signals from the cell membrane. The geographic shape of the NSPs concentrates AgNPs but impedes their penetration into attached cells, mitigating the detrimental effect of silver ion deposition in applied tissues. Moreover, the tightly tethered AgNPs on NSP surface achieve a stronger biocidal effect than silver nitrate, but bypassing Ag(+ mechanism, on silver-resistant bacteria. This nanohybrid presents an effective and safe antimicrobial agent in a new perspective.

  15. Celecoxib interferes to a limited extent with aspirin‐mediated inhibition of platelets aggregation

    Science.gov (United States)

    Ruzov, Mark; Rimon, Gilad; Pikovsky, Oleg

    2015-01-01

    Aims The aim of the study was to analyze the interaction between celecoxib and low dose aspirin for COX‐1 binding and its consequences on the aspirin‐mediated antiplatelet effects. Methods We investigated ex vivo the interaction between celecoxib and aspirin for COX‐1 binding and measured the resulting antiplatelet effects. We applied mechanism‐based pharmacokinetic−pharmacodynamic (PKPD) modelling to analyze these data and to predict in vivo platelet aggregation for different doses and administration schedules of aspirin and celecoxib. Results The predictions of the PK‐PD model were consistent with results from previous studies that investigated interaction between aspirin and celecoxib. The modelling results indicate that celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. The extent of this interaction can be substantial (up to 15% increase in platelet aggregation by 200 mg day−1 celecoxib when combined with low dose aspirin) during the first days of aspirin administration in patients who are already treated with celecoxib, and it cannot be prevented by separate administration of the interacting drugs. Conclusions At the recommended therapeutic doses, celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. Patients receiving a combination of low dose aspirin and the recommended doses of celecoxib were not identified to have increased risk of cardiovascular and cerebrovascular events due to competition between these drugs for COX‐1 binding. Interaction between low dose aspirin and other COX‐2 inhibitors and its clinical consequences requires further investigation. PMID:26456703

  16. Impact of chronic kidney disease on platelet inhibition of clopidogrel and prasugrel in Japanese patients.

    Science.gov (United States)

    Nishi, Takeshi; Ariyoshi, Noritaka; Nakayama, Takashi; Fujimoto, Yoshihide; Sugimoto, Kazumasa; Wakabayashi, Shinichi; Hanaoka, Hideki; Kobayashi, Yoshio

    2017-05-01

    The impact of chronic kidney disease (CKD) on the antiplatelet effect of clopidogrel and low-dose (3.75mg) prasugrel in Japanese patients is largely unknown. A total of 53 consecutive Japanese patients with stable coronary artery disease who received aspirin and clopidogrel were enrolled, and categorized by estimated glomerular filtration rate (eGFR): CKD group (n=15, eGFRClopidogrel was switched to 3.75mg prasugrel. Platelet reactivity measurement using the VerifyNow P2Y12 assay (Accumetrics, San Diego, CA, USA) was performed at baseline (on clopidogrel) and day 14 (on prasugrel). The VerifyNow P2Y12 reaction units (PRU) during clopidogrel therapy was significantly higher in the CKD group than that in the non-CKD group (185.2±51.1 PRU vs. 224.3±57.0 PRU, p=0.02), whereas, the PRU with the prasugrel therapy in the CKD group and non-CKD group were not significantly different (149.9±51.1 PRU vs. 165.3±61.8 PRU, p=0.36). The PRU was significantly lower with the prasugrel therapy compared to that with the clopidogrel therapy both in the CKD group and in the non-CKD group. Antiplatelet effect of clopidogrel but not prasugrel is attenuated in patients with CKD. Prasugrel achieves a consistently lower platelet reactivity compared with clopidogrel regardless of the presence of mild to moderate CKD. Copyright © 2016 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  17. Regional myocardial perfusion defects during exercise, as assessed by three dimensional integration of morphology and function, in relation to abnormal endothelium dependent vasoreactivity of the coronary microcirculation

    Science.gov (United States)

    Schindler, T H; Nitzsche, E; Magosaki, N; Brink, I; Mix, M; Olschewski, M; Solzbach, U; Just, H

    2003-01-01

    Objective: To test the hypothesis that scintigraphic regional myocardial perfusion defects during exercise in patients with normal coronary angiography may be related to abnormal endothelium dependent vasoreactivity of the corresponding myocardial territory in response to cold pressor testing. Methods: 38 patients were classified into two groups according to the presence or absence of exercise induced scintigraphic myocardial perfusion defects. A cold pressor test was done in all patients during routine coronary angiography, followed by dynamic positron emission tomography to establish coronary blood flow mediated vasoreactivity of the epicardial coronary artery and the myocardial territories supplied by the left anterior descending, left circumflex, and right coronary arteries. Results: 28 patients had regional myocardial perfusion defects while 10 had normal scintigraphic imaging. The three dimensional scintigraphic fusion image revealed 49 regional myocardial perfusion defects with a mean (SD) reversibility of the original stress defect of 20 (3)%. In patients with exercise induced regional myocardial perfusion defects, the responses of epicardial luminal area and regional myocardial blood flow (RMBF) to cold pressor testing were reduced compared with patients with normal perfusion imaging (epicardial luminal area: 5.2 (1.2) to 4.2 (0.86) mm2 v 4.7 (0.5) to 5.8 (0.5) mm2; RMBF: 0.75 (0.16) to 0.78 (0.20) ml/g/min v 0.75 (0.15) to 1.38 (0.26) ml/g/min; p ≤ 0.03, respectively). In patients with regional abnormal scintigraphic perfusion, the corresponding RMBF response to cold pressor testing was more severely impaired than the mean myocardial blood flow in the remaining two vascular territories, but the difference was not significant (0.75 (0.16) to 0.78 (0.20) ml/g/min v 0.75 (0.10) to 0.87 (0.12) ml/g/min; NS). The endothelium independent increase in RMBF induced by glyceryl trinitrate did not differ between patients with exercise induced myocardial perfusion

  18. Endothelium-Dependent Vasorelaxant Effect of Butanolic Fraction from Caryocar brasiliense Camb. Leaves in Rat Thoracic Aorta.

    Science.gov (United States)

    de Oliveira, Lais Moraes; Rodrigues, Aline Gabriela; da Silva, Elaine Fernanda; Cerqueira, Letícia Bonancio; Castro, Carlos Henrique; Pedrino, Gustavo Rodrigues; de Carvalho, Maria Helena Catelli; Pontarolo, Roberto; Costa, Elson Alves; Campos, Francinete Ramos; Filgueira, Fernando Paranaiba; Ghedini, Paulo César

    2012-01-01

    Caryocar brasiliense Camb. "pequi" is a native plant from the Cerrado region of Brazil that contains bioactive components reported to be antioxidant agents. Previous work has demonstrated that dietary supplementation with pequi decreased the arterial pressure of volunteer athletes. We found that the crude hydroalcoholic extract (CHE) of C. brasiliense leaves relaxed, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine, and that the butanolic fraction (BF) produced an effect similar to that of the CHE. Aortic relaxation induced by BF was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylatecyclase inhibitor ODQ. However, incubation with atropine and pyrilamine had no effect on the BF-induced vasorelaxation. Moreover, this effect was not inhibited by indomethacin and tetraethylammonium. The concentration-response curve to calcium in denuded-endothelium rings was not modified after incubation with BF, and the vasorelaxation by BF in endothelium-intact rings precontracted with KCl was abolished after incubation with L-NAME. In addition, administration of BF in anesthetized rats resulted in a reversible hypotension. The results reveal that C. brasiliense possesses both in vivo and in vitro activities and that the vascular effect of BF involves stimulation of the nitric oxide/cyclic GMP pathway.

  19. Endothelium-Dependent Vasorelaxant Effect of Butanolic Fraction from Caryocar brasiliense Camb. Leaves in Rat Thoracic Aorta

    Directory of Open Access Journals (Sweden)

    Lais Moraes de Oliveira

    2012-01-01

    Full Text Available Caryocar brasiliense Camb. “pequi” is a native plant from the Cerrado region of Brazil that contains bioactive components reported to be antioxidant agents. Previous work has demonstrated that dietary supplementation with pequi decreased the arterial pressure of volunteer athletes. We found that the crude hydroalcoholic extract (CHE of C. brasiliense leaves relaxed, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine, and that the butanolic fraction (BF produced an effect similar to that of the CHE. Aortic relaxation induced by BF was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylatecyclase inhibitor ODQ. However, incubation with atropine and pyrilamine had no effect on the BF-induced vasorelaxation. Moreover, this effect was not inhibited by indomethacin and tetraethylammonium. The concentration-response curve to calcium in denuded-endothelium rings was not modified after incubation with BF, and the vasorelaxation by BF in endothelium-intact rings precontracted with KCl was abolished after incubation with L-NAME. In addition, administration of BF in anesthetized rats resulted in a reversible hypotension. The results reveal that C. brasiliense possesses both in vivo and in vitro activities and that the vascular effect of BF involves stimulation of the nitric oxide/cyclic GMP pathway.

  20. Platelet Activating Factor (PAF) biosynthesis is inhibited by phenolic compounds in U-937 cells under inflammatory conditions.

    Science.gov (United States)

    Vlachogianni, Ioanna C; Fragopoulou, Elizabeth; Stamatakis, George M; Kostakis, Ioannis K; Antonopoulou, Smaragdi

    2015-09-01

    Interleukin 1 beta (IL-1β) induced platelet activating factor (PAF) synthesis in U-937 cells through stimulation of acetyl-CoA:lysoPAF-acetyltransferase (lyso PAF-AT) at 3 h and DTT-independentCDP-choline-1-alkyl-2-acetyl-sn-glycerol cholinophosphotransferase (PAF-CPT) at 0.5 h. The aim of this study was to investigate the effect of tyrosol (T), resveratrol (R) and their acetylated derivatives(AcDs) which exhibit enhanced bioavailability, on PAF synthesis in U-937 after IL-1β stimulation. The specific activity of PAF enzymes and intracellular levels were measured in cell homogenates. T and R concentration capable of inducing 50% inhibition in IL-1β effect on lyso PAF-AT was 48 μΜ ± 11 and 157 μΜ ± 77, for PAF-CPT 246 μΜ ± 61 and 294 μΜ ± 102, respectively. The same order of concentration was also observed on inhibiting PAF levels produced by IL-1β. T was more potent inhibitor than R (p<0.05). AcDs of T retain parent compound inhibitory activity, while in the case of R only two AcDs retain the activity. The observed inhibitory effect by T,R and their AcDs, may partly explain their already reported beneficial role. Copyright © 2015. Published by Elsevier Inc.

  1. Inhibition of tumor cell-induced platelet aggregation and lung metastasis by the oral GpIIb/IIIa antagonist XV454.

    Science.gov (United States)

    Amirkhosravi, Ali; Mousa, Shaker A; Amaya, Mildred; Blaydes, Susan; Desai, Hina; Meyer, Todd; Francis, John L

    2003-09-01

    Platelets are known to play a role in blood borne metastasis. Previous experimental studies have suggested that platelet GpIIb/IIIa may be a therapeutic target. However, the need for intravenous administration limits the potential application of current GpIIb/IIIa inhibitors to cancer therapy. The aim of the present study was to assess the efficacy of a novel, non-peptide oral GpIIb/IIIa antagonist (XV454) on tumor cell-induced platelet aggregation in vivo and on experimental metastasis. A Lewis lung carcinoma (LL2) mouse model of experimental metastasis was used in this study. XV454 (100 micro g) was administered intravenously (via tail vein) or orally (gavages) to 20 g mice. To determine the effect of XV454 on platelet aggregation, blood samples were collected by cardiac puncture 10 minutes after intravenous and 1-24 hrs after oral XV454, and platelet function was assessed by aggregometry, thrombelastography and the Platelet Function Analyzer (PFA100). The effect of XV454 on tumor cell-induced thrombocytopenia was determined 10 minutes after intravenous and 3 hrs after oral XV454 administration. Tumor cells (2 x 10(6)) were injected intravenously and 15 minutes after cell injection, platelet count was measured and compared to baseline (pre-injection) counts. To assess the effect on metastasis, XV454 was administered intravenous or orally 10 minutes and 3 hrs before tumor cell injection, respectively. Eighteen days later, surface lung tumor nodules were counted and the total lung tumor burden assessed. In a fourth group, in addition to the initial oral dose (before tumor cell injection), oral XV454 was given daily for the first week and three times in the second week. Administration of XV454 (5 mg/kg) completely inhibited platelet aggregation and this effect persisted for at least 24 hrs after oral delivery. Both intravenous and oral XV454 significantly inhibited tumor cell-induced thrombocytopenia (P < 0.01), the number of surface lung tumor nodules (80-85%; P

  2. Suboptimal inhibition of platelet cyclo-oxygenase-1 (COX-1) by aspirin in lupus erythematosus: Association with metabolic syndrome

    Science.gov (United States)

    Kawai, Vivian K.; Avalos, Ingrid; Oeser, Annette; Oates, John A.; Milne, Ginger L.; Solus, Joseph F.; Chung, Cecilia P.; Stein, C. Michael

    2013-01-01

    Objectives Low-dose aspirin prevents platelet aggregation by suppressing thromboxane A2 synthesis. However, in some individuals thromboxane A2 suppression by aspirin is impaired, indicating suboptimal inhibition of platelet COX-1 by aspirin. Because patients with systemic lupus erythematosus (SLE) have increased risk of thrombotic events, many receive aspirin; however, the efficacy of aspirin in SLE has not been determined. We examined the hypothesis that aspirin response is impaired in SLE. Methods We assessed the effect of aspirin by measuring concentrations of the stable metabolite of thromboxane A2 - serum thromboxane B2 (sTxB2), before and after treatment with 81 mg daily aspirin for 7 days in 34 patients with SLE and 36 control subjects. The inability to suppress sTxB2 synthesis to aspirin. Results Aspirin almost completely suppressed sTXB2 in control subjects to 1.5, [0.8–2.7] ng/ml (median and interquartile ranges [IQR]), but had less effect in patients with SLE (3.1, [2.2–5.3] ng/ml) (P=0.002). A suboptimal effect of aspirin was present in 15% (5/34) of the patients with SLE but not in control subjects (0/36) (P=0.023). Incomplete responders were more likely to have metabolic syndrome (P=0.048), obesity (P=0.048) and higher concentrations of CRP (P=0.018). Conclusion The pharmacologic effect of aspirin is suboptimal in 15% of patients with SLE but in none of the control subjects, and the suboptimal response was associated with metabolic syndrome, obesity, and higher CRP concentrations. PMID:24022862

  3. Targeting of type I protein kinase A to lipid rafts is required for platelet inhibition by the 3',5'-cyclic adenosine monophosphate-signaling pathway.

    Science.gov (United States)

    Raslan, Z; Magwenzi, S; Aburima, A; Taskén, K; Naseem, K M

    2015-09-01

    Platelet adhesion to von Willebrand factor (VWF) is modulated by 3',5'-cyclic adenosine monophosphate (cAMP) signaling through protein kinase A (PKA)-mediated phosphorylation of glycoprotein (GP)Ibβ. A-kinase anchoring proteins (AKAPs) are proposed to control the localization and substrate specificity of individual PKA isoforms. However, the role of PKA isoforms in regulating the phosphorylation of GPIbβ and platelet response to VWF is unknown. We wished to determine the role of PKA isoforms in the phosphorylation of GPIbβ and platelet activation by VWF as a model for exploring the selective partitioning of cAMP signaling in platelets. The two isoforms of PKA in platelets, type I (PKA-I) and type II (PKA-II), were differentially localized, with a small pool of PKA-I found in lipid rafts. Using a combination of Far Western blotting, immunoprecipitation, proximity ligation assay and cAMP pull-down we identified moesin as an AKAP that potentially localizes PKA-I to rafts. Introduction of cell-permeable anchoring disruptor peptide, RI anchoring disruptor (RIAD-Arg11 ), to block PKA-I/AKAP interactions, uncoupled PKA-RI from moesin, displaced PKA-RI from rafts and reduced kinase activity in rafts. Examination of GPIbβ demonstrated that it was phosphorylated in response to low concentrations of PGI2 in a PKA-dependent manner and occurred primarily in lipid raft fractions. RIAD-Arg11 caused a significant reduction in raft-localized phosphoGPIbβ and diminished the ability of PGI2 to regulate VWF-mediated aggregation and thrombus formation in vitro. We propose that PKA-I-specific AKAPs in platelets, including moesin, organize a selective localization of PKA-I required for phosphorylation of GPIbβ and contribute to inhibition of platelet VWF interactions. © 2015 International Society on Thrombosis and Haemostasis.

  4. Inhibition of platelet activation by lachrymatory factor synthase (LFS)-silenced (tearless) onion juice.

    Science.gov (United States)

    Thomson, Susan J; Rippon, Paula; Butts, Chrissie; Olsen, Sarah; Shaw, Martin; Joyce, Nigel I; Eady, Colin C

    2013-11-06

    Onion and garlic are renowned for their roles as functional foods. The health benefits of garlic are attributed to di-2-propenyl thiosulfinate (allicin), a sulfur compound found in disrupted garlic but not found in disrupted onion. Recently, onions have been grown with repressed lachrymatory factor synthase (LFS) activity, which causes these onions to produce increased amounts of di-1-propenyl thiosulfinate, an isomer of allicin. This investigation into the key health attributes of LFS-silenced (tearless) onions demonstrates that they have some attributes more similar to garlic and that this is likely due to the production of novel thiosulfinate or metabolites. The key finding was that collagen-induced in vitro platelet aggregation was significantly reduced by tearless onion extract over normal onion extract. Thiosulfinate or derived compounds were shown not to be responsible for the observed changes in the inflammatory response of AGS (stomach adenocarcinoma) cells to tumor necrosis factor alpha (TNFα) when pretreated with model onion juices. A preliminary rat feeding trial indicated that the tearless onions may also play a key role in reducing weight gain.

  5. Cystamine immobilization on TiO{sub 2} film surfaces and the influence on inhibition of collagen-induced platelet activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yujuan [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Weng Yajun, E-mail: wengyj7032@sohu.com [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Zhang Liping; Jing Fengjuan; Huang Nan [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Chen Junying, E-mail: chenjy@263.net [Key Lab. of Advanced Technology for Materials of Chinese Education Ministry, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2011-12-15

    Poor haemocompatibility is a main issue of artificial cardiovascular materials in clinical application. Nitric oxide (NO), produced by vascular endothelial cells, is a well known inhibitor of platelet adhesion and activation. Thus, NO-releasing biomaterials are beneficial for improving haemocompatibility of blood-contacting biomedical devices. In this paper, a novel method was developed for enhancement of haemocompatibility by exploiting endogenous NO donors. TiO{sub 2} films were firstly synthesized on Si (1 0 0) wafers via unbalanced magnetron sputtering technology, and then polydopamine was grafted on TiO{sub 2} films and used as a linker for further immobilization of cystamine. The obtained surfaces were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. NO generation is evaluated by saville-griess reagents, and it shows that cystamine immobilized samples are able to catalytically generate NO by decomposing endogenous S-nitrosothiols (RSNO). In vitro platelet adhesion results reveal that cystamine modified surfaces can inhibit collagen-induced platelet activation. ELISA analysis reveals that cGMP in platelets obviously increases on cystamine immobilized surface, which suggests the reducing of platelet activation is through NO/cGMP signal channel. It can be concluded that cystamine immobilized surface shows better blood compatibility by catalyzing NO release from the endogenous NO donor. It may be a promising method for improvement of haemocompatibility of blood-contacting implants.

  6. Platelet-Derived Growth Factor-Receptor α Strongly Inhibits Melanoma Growth In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Debora Faraone

    2009-08-01

    Full Text Available Cutaneous melanoma is the most aggressive skin cancer; it is highly metastatic and responds poorly to current therapies. The expression of platelet-derived growth factor receptors (PDGF-Rs is reported to be reduced in metastatic melanoma compared with benign nevi or normal skin; we then hypothesized that PDGF-Rα may control growth of melanoma cells. We show here that melanoma cells overexpressing PDGF-Rα respond to serum with a significantly lower proliferation compared with that of controls. Apoptosis, cell cycle arrest, pRb dephosphorylation, and DNA synthesis inhibition were also observed in cells overexpressing PDGF-Rα. Proliferation was rescued by PDGF-Rα inhibitors, allowing to exclude nonspecific toxic effects and indicating that PDGF-Rα mediates autocrine antiproliferation signals in melanoma cells. Accordingly, PDGF-Rα was found to mediate staurosporine cytotoxicity. A protein array-based analysis of the mitogen-activated protein kinase pathway revealed that melanoma cells overexpressing PDGF-Rα show a strong reduction of c-Jun phosphorylated in serine 63 and of protein phosphatase 2A/Bα and a marked increase of p38γ, mitogen-activated protein kinase kinase 3, and signal regulatory protein α1 protein expression. In a mouse model of primary melanoma growth, infection with the Ad-vector overexpressing PDGF-Rα reached a significant 70% inhibition of primary melanoma growth (P < .001 and a similar inhibition of tumor angiogenesis. All together, these data demonstrate that PDGF-Rα strongly impairs melanoma growth likely through autocrine mechanisms and indicate a novel endogenous mechanism involved in melanoma control.

  7. MiR-34a inhibits colon cancer proliferation and metastasis by inhibiting platelet-derived growth factor receptor α.

    Science.gov (United States)

    Li, Chunyan; Wang, Yulin; Lu, Shuming; Zhang, Zhuqing; Meng, Hua; Liang, Lina; Zhang, Yan; Song, Bo

    2015-11-01

    The microRNA (miRNA), miR‑34a is significant in colon cancer progression. In the present study, the role of miR‑34a in colon cancer cell proliferation and metastasis was investigated. It was found that the expression of miR‑34a in colon cancer tissues and cell lines was lower when compared with that of normal tissues and cells. Further research demonstrated that miR‑34a inhibited cell proliferation, induced G1 phase arrest, and suppressed metastasis and epithelial mesenchymal transition in colon cancer cells. Bioinformatic prediction indicated that platelet‑derived growth factor receptor α (PDGFRA) was a potential target gene of miR‑34a and a luciferase assay identified that PDGFRA was a novel direct target gene of miR‑34a. In addition, assays of western blot analyses and quantitative reverse‑transcription polymerase chain reaction confirmed that miR‑34a decreased PDGFRA mRNA expression and protein levels in colon cancer cells. Assessment of cellular function indicated that miR‑34a inhibited colon cancer progression via PDGFRA. These findings demonstrate that miR‑34a may act as a negative regulator in colon cancer by targeting PDGFRA.

  8. 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.

  9. Inhibition of fumonisin B1 cytotoxicity by nanosilicate platelets during mouse embryo development.

    Directory of Open Access Journals (Sweden)

    Yu-Jing Liao

    Full Text Available Nanosilicate platelets (NSP, the form of natural silicate clay that was exfoliated from montmorillonite (MMT, is widely used as a feed additive for its high non-specific binding capacity with mycotoxins such as fumonisin B1 (FB1, and has been evaluated its safety for biomedical use including cytotoxicity, genotoxicity, and lethal dosage (LD. In the study, we further examined its toxicity on the development of CD1 mouse embryos and its capacity to prevent teratogenesis-induced by FB1. In vitro cultures, NSP did not disturb the development and the quality of intact pre-implantation mouse embryos. Further, newborn mice from females consumed with NSP showed no abnormalities. NSP had an unexpected high adsorption capacity in vitro. In contrast to female mice consumed with FB1 only, a very low residual level of FB1 in the circulation, reduced incidence of neutral tube defects and significantly increased fetal weight were observed in the females consumed with FB1 and NSP, suggesting a high alleviation effect of NSP on FB1 in vivo. Furthermore, FB1 treatment disturbed the gene expression of sphingolipid metabolism enzymes (longevity assurance homolog 5, LASS 5; sphingosine kinase 1, Sphk1; sphingosine kinase 2, Sphk2; sphingosine 1- phosphate lyase, Sgpl1; sphingosine 1-phosphate phosphatase, Sgpp1 in the maternal liver, uterus, fetus, and placenta, but NSP administration reversed the perturbations. Based on these findings, we conclude that NSP is a feasible and effective agent for supplementary use in reducing the toxicity of FB1 to animals.

  10. High glucose inhibits the aspirin-induced activation of the nitric oxide/cGMP/cGMP-dependent protein kinase pathway and does not affect the aspirin-induced inhibition of thromboxane synthesis in human platelets.

    Science.gov (United States)

    Russo, Isabella; Viretto, Michela; Barale, Cristina; Mattiello, Luigi; Doronzo, Gabriella; Pagliarino, Andrea; Cavalot, Franco; Trovati, Mariella; Anfossi, Giovanni

    2012-11-01

    Since hyperglycemia is involved in the "aspirin resistance" occurring in diabetes, we aimed at evaluating whether high glucose interferes with the aspirin-induced inhibition of thromboxane synthesis and/or activation of the nitric oxide (NO)/cGMP/cGMP-dependent protein kinase (PKG) pathway in platelets. For this purpose, in platelets from 60 healthy volunteers incubated for 60 min with 5-25 mmol/L d-glucose or iso-osmolar mannitol, we evaluated the influence of a 30-min incubation with lysine acetylsalicylate (L-ASA; 1-300 μmol/L) on 1) platelet function under shear stress; 2) aggregation induced by sodium arachidonate or ADP; 3) agonist-induced thromboxane production; and 4) NO production, cGMP synthesis, and PKG-induced vasodilator-stimulated phosphoprotein phosphorylation. Experiments were repeated in the presence of the antioxidant agent amifostine. We observed that platelet exposure to 25 mmol/L d-glucose, but not to iso-osmolar mannitol, 1) reduced the ability of L-ASA to inhibit platelet responses to agonists; 2) did not modify the L-ASA-induced inhibition of thromboxane synthesis; and 3) prevented the L-ASA-induced activation of the NO/cGMP/PKG pathway. Preincubation with amifostine reversed the high-glucose effects. Thus, high glucose acutely reduces the antiaggregating effect of aspirin, does not modify the aspirin-induced inhibition of thromboxane synthesis, and inhibits the aspirin-induced activation of the NO/cGMP/PKG pathway. These results identify a mechanism by which high glucose interferes with the aspirin action.

  11. Platelet-rich plasma inhibits inflammatory factors and represses rheumatoid fibroblast-like synoviocytes in rheumatoid arthritis.

    Science.gov (United States)

    Tong, Shichao; Liu, Ji; Zhang, Changqing

    2017-11-01

    Rheumatoid arthritis (RA) is a chronic disease affecting daily life of numerous patients, and uncontrolled proliferation of synovial fibroblasts plays vital role during the pathology of RA. Platelet-rich plasma (PRP), widely used in tissue regeneration and pain management, is rarely studied in RA. This study aims to investigate the effect of PRP on synovial fibroblasts during RA. Rheumatoid fibroblast-like synoviocyte MH7A cells were stimulated by lipopolysaccharide (LPS) to simulate RA conditions and treated with PRP, after that the concentration of inflammatory factors interleukin (IL) 1β, tumor necrosis factor alpha (TNFα) and IL6 in the supernatant of culture medium was quantified by ELISA. MTT assay, flow cytometry and tube formation assay were performed to assess changes in cell viability, apoptosis and effect on angiogenesis in vitro, respectively. Besides, the expression levels of main factors in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathway were examined. Results showed that PRP markedly inhibited the production of IL1β, TNFα and IL6 (P investigation is necessary to reveal detailed mechanism of PRP.

  12. [Subgroup analysis results of platelet inhibition trial in acute coronary syndrome patients (PLATO) who underwent intervention or medical treatment].

    Science.gov (United States)

    Aksakal, Enbiya

    2013-04-01

    Antiplatelet agents are among the most important drug classes in reducing mortality in patients with acute coronary syndromes (ACS). Ticagrelor is the first reversible and direct acting P2Y(12) receptor inhibitor with an earlier onset of action compared to clopidogrel. The PLATO study (Platelet Inhibition and Patient Outcomes) with ticagrelor was conducted with a design providing consistency with the current clinical practice, including all forms of ACS and a wide spectrum of treatment options in 18624 patients from 862 centers in 43 countries. Of these patients, 13408 underwent interventional procedures (ticagrelor/clopidogrel; 6732/6676) (PLATO-INVASIVE). As reported by the investigator, non-invasive treatment strategy was planned for 5216 patients (ticagrelor/clopidogrel; 2601/2615). However, 2040 patients in this group received interventional treatment during the follow-up (PLATO-NON-INVASIVE/MEDICAL TREATMENT). 1261 patients requiring surgical treatment underwent coronary artery bypass grafting (CABG) within 7 days after the discontinuation of study treatment (ticagrelor/clopidogrel; 632/629) (PLATO-CABG). The results of these three subgroups were consistent with the main PLATO study results, demonstrating that ticagrelor reduced the primary (cardiovascular death, myocardial Infarction and stroke) and secondary composite endpoints without increasing bleeding compared with clopidogrel. Ticagrelor fulfills an important unmet need regarding antiplatelet effectiveness in patients with ACS. This review evaluates the INVASIVE and MEDICAL subgroup studies of the PLATO study.

  13. Projected inhibition of platelet aggregation with ticagrelor twice daily vs. clopidogrel once daily based on patient adherence data (the TWICE project)

    OpenAIRE

    Vrijens, Bernard; Claeys, M.J.; Legrand, Victor; Vandendriessche, E; Van de Werf, F

    2014-01-01

    Abstract Aim Twice daily dosing is often perceived as inferior to once daily dosing due to a higher likelihood of missing a dose. However, more important is the extent to which drug action is maintained when doses are delayed or missed. We compared the estimated inhibition of platelet aggregation (eIPA) for ticagrelor twice daily and clopidogrel once daily, based on their pharmacokinetic/ pharmacodynamic relationships and patient dosing history data. Methods Drug dosing histories of 5014 ...

  14. Ticagrelor versus clopidogrel in patients with ST-elevation acute coronary syndromes intended for reperfusion with primary percutaneous coronary intervention: A Platelet Inhibition and Patient Outcomes (PLATO) trial subgroup analysis

    National Research Council Canada - National Science Library

    Steg, Philippe Gabriel; James, Stefan; Harrington, Robert A; Ardissino, Diego; Becker, Richard C; Cannon, Christopher P; Emanuelsson, Håkan; Finkelstein, Ariel; Husted, Steen; Katus, Hugo; Kilhamn, Jan; Olofsson, Sylvia; Storey, Robert F; Weaver, W Douglas; Wallentin, Lars

    2010-01-01

    ...) or undergoing coronary stenting. Ticagrelor, a reversible oral P2Y12-receptor antagonist, provides faster, greater, and more consistent platelet inhibition than clopidogrel and may be useful for patients with acute ST-segment elevation (STE...

  15. Inhibition of targeted platelet-derived growth factor receptor-α RNA interference into vitreous cavity for experimental proliferative vitreoretinopathy

    Directory of Open Access Journals (Sweden)

    Zhu Meng

    2016-01-01

    Full Text Available AIM:To observe the therapeutic effect of platelet-derived growth factor receptor-α RNA interference on inhibiting experimental proliferative vitreoretinopathy(PVR.METHODS:Different concentrations of PDGFR-α shRNA were blended with lip2000,and the final scale of PDGFR-α shRNA/lip2 000 complex was 1:1, 1:2 and 1:3 respectively(the concentration of PDGFR-α shRNA was respectively 2μg, 3μg and 4μg.All the complexes were cultivated in human retinal pigment epithelium(HRPEfor 24h after transfection and then respectively injected 0.1mL to rabbit vitreous cavity.Forty healthy adult rabbits were seleceted in this study and randomly divided into colored balanced salt solution(BSSgroup(N, comprising lipofectamineTM2 000 HRPE cell dilution group(group A. The highest transduction efficiency of 1.0, 1.5 and 2.0μmol/L containing PDGFR-α receptors shRNA, lipofectamineTM2 000 of HRPE cell dilution were selected(respectively group B, C and Dwith 8 eyes each, the right eyes as the experimental eye. The extent of PVR was observed by indirect ophthalmoscope; and slice staining situation was observed by immunohistochemistry.The fundus changes were observed by histopathology.RESULTS:The highest transduction efficiency of PDGFR-αshRNA/lip2 000 ratio was 1:2.The extent of PVR, the histopathology changes and the immunohistochemistry of PDGFR-α in group B,C and group D were significantly lower than that in group A, while group D was much lower than those of group B and C.CONCLUSION:PDGFR-αRNA interference could inhibit the formation of experimental PVR.

  16. Endothelium-dependent vasodilator effect of Euterpe oleracea Mart. (Açaí) extracts in mesenteric vascular bed of the rat.

    Science.gov (United States)

    Rocha, A P M; Carvalho, L C R M; Sousa, M A V; Madeira, S V F; Sousa, P J C; Tano, T; Schini-Kerth, V B; Resende, A C; Soares de Moura, R

    2007-02-01

    Açai (Euterpe oleracea Mart.) a fruit from the Amazon region, largely consumed in Brazil is rich in polyphenols. Experiments were undertaken to determine whether hydro-alcoholic extract obtained from stone of açaí induces a vasodilator effect in the rat mesenteric vascular bed precontracted with norepinephrine (NE) and, if so, to elucidate the underlying mechanism. Açai stone extract (ASE, 0.3-100 microg) induced a long-lasting endothelium-dependent vasodilation that was significantly reduced by N(G)-nitro-l-arginine methyl ester (l-NAME) and (1)H-[1,2,3] oxadiazolo [4,4-a] quinoxalin-l-one (ODQ) and abolished by KCl (45 mM) plus l-NAME. In vessels precontrated with NE and KCl (45 mM) or treated with K(Ca)(+2) channel blockers (charybdotoxin plus apamin), the effect of ASE was significantly reduced. However this effect is not affect by indomethacin, glybenclamide and 4-aminopiridine. Atropine, pyrilamine, yohimbine and HOE 140 significantly reduced the vasodilator effect of acetylcholine, histamine, clonidine and bradykinin, respectively, but did not change the vasodilator effect of ASE. In cultured endothelial cells ASE (100 microg/mL) induced the formation of NO that was reduced by N(G)-nitro-l-arginine (l-NA, 100 microM). The present study demonstrates that the vasodilator effect of ASE is dependent on activation of NO-cGMP pathway and may also involve endothelium-derived hyperpolarizing factor (EDHF) release. The vasodilator effect suggest a possibility to use ASE as a medicinal plant, in the treatment of cardiovascular diseases.

  17. Mechanisms underlying the endothelium-dependent vasodilatory effect of an aqueous extract of Elaeis Guineensis Jacq. (Arecaceae) in porcine coronary artery rings.

    Science.gov (United States)

    Ndiaye, Mamadou; Anselm, Eric; Séne, Madièye; Diatta, Williams; Dièye, Amadou Moctar; Faye, Babacar; Schini-Kerth, Valérie B

    2009-12-30

    This study was undertaken to investigate the vasodilatory effect of an aqueous extract of Elaeis guineensis Jacq (EGE) in the porcine coronary artery and elicit its possible mechanism(s) of action. Vascular effects of crude extract of dried and powdered leaves of Elaeis guineensis were evaluated on isolated coronary arteries on organ chambers. Determination of eNOS expression and the phosphorylation level of eNOS were determined by Western blot analysis. In the presence of indomethacin, EGE caused pronounced relaxations in endothelium-intact but not in endothelium-denuded coronary artery rings. Relaxations to EGE were significantly reduced by N(ω)-nitro-L-arginine (L-NA, a competitive inhibitor of NO synthase), slightly but not significantly by charybdotoxin plus apamin (two potent inhibitors of EDHF-mediated responses) and abolished by the combination of L-NA and charybdotoxin plus apamin. Relaxations to EGE were abolished by the membrane permeant, SOD mimetic, MnTMPyP, and significantly reduced by wortmannin, an inhibitor of PI3-kinase. Exposure of endothelial cells to EGE increased the phosphorylation level of eNOS at Ser1177 in a time and concentration-dependent manner. MnTMPyP abolished the EGE-induced phosphorylation of eNOS.In conclusion, the obtained data indicate that EGE induces pronounced endothelium-dependent relaxations of the porcine coronary artery, which involve predominantly NO. The stimulatory effect of EGE on eNOS involves the redox-sensitive phosphorylation of eNOS at Ser1177 most likely via the PI3-kinase pathway.

  18. Downregulation of Endothelial Transient Receptor Potential Vanilloid Type 4 Channel and Small-Conductance of Ca2+-Activated K+ Channels Underpins Impaired Endothelium-Dependent Hyperpolarization in Hypertension.

    Science.gov (United States)

    Seki, Takunori; Goto, Kenichi; Kiyohara, Kanako; Kansui, Yasuo; Murakami, Noboru; Haga, Yoshie; Ohtsubo, Toshio; Matsumura, Kiyoshi; Kitazono, Takanari

    2017-01-01

    Endothelium-dependent hyperpolarization (EDH)-mediated responses are impaired in hypertension, but the underlying mechanisms have not yet been determined. The activation of small- and intermediate-conductance of Ca2+-activated K+ channels (SKCa and IKCa) underpins EDH-mediated responses. It was recently reported that Ca2+ influx through endothelial transient receptor potential vanilloid type 4 channel (TRPV4) is a prerequisite for the activation of SKCa/IKCa in endothelial cells in specific beds. Here, we attempted to determine whether the impairment of EDH in hypertension is attributable to the dysfunction of TRPV4 and S/IKCa, using isolated superior mesenteric arteries of 20-week-old stroke-prone spontaneously hypertensive rats (SHRSP) and age-matched Wistar-Kyoto (WKY) rats. In the WKY arteries, EDH-mediated responses were reduced by a combination of SKCa/IKCa blockers (apamin plus TRAM-34; 1-[(2-chlorophenyl)diphenylmethl]-1H-pyrazole) and by the blockade of TRPV4 with the selective antagonist RN-1734 or HC-067047. In the SHRSP arteries, EDH-mediated hyperpolarization and relaxation were significantly impaired when compared with WKY. GSK1016790A, a selective TRPV4 activator, evoked robust hyperpolarization and relaxation in WKY arteries. In contrast, in SHRSP arteries, the GSK1016790A-evoked hyperpolarization was small and relaxation was absent. Hyperpolarization and relaxation to cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine, a selective SKCa activator, were marginally decreased in SHRSP arteries compared with WKY arteries. The expression of endothelial TRPV4 and SKCa protein was significantly decreased in the SHRSP mesenteric arteries compared with those of WKY, whereas function and expression of IKCa were preserved in SHRSP arteries. These findings suggest that EDH-mediated responses are impaired in superior mesenteric arteries of SHRSP because of a reduction in both TRPV4 and SKCa input to EDH. © 2016 American Heart Association

  19. Platelet sparing effect of COX II inhibition used with pegylated interferon alfa-2a for the treatment of chronic hepatitis C: a short term pilot study.

    Science.gov (United States)

    George, Magdalene M; Li, S David; Mindikoglu, Ayse L; Baluch, Mehdi H; Dhillon, Sonu; Farr, Deborah; Van Thiel, David H

    2004-09-21

    The role of a cyclooxygenase (COX) II inhibitor in reducing microvascular inflammation and the platelet count associated with interferon (IFN) plus ribavirin therapy of chronic hepatitis C (HCV) was assessed. Three plasma mediators (biomarkers) associated with platelet activation, inflammation and fibrosis were measured. Eighteen IFN naïve patients were studied. Nine were treated with pegylated IFN alfa-2a (PEG-IFN alpha-2a) plus ribavirin and rofecoxib; nine were treated with PEG-IFN alpha-2a plus ribavirin. A complete blood count, liver panel and HCV-RNA were assayed weekly. Human soluble P-selectin (hs-P-selectin), human interleukin-8 (IL-8), human interleukin-13 (IL-13) and human thrombopoietin (TPO) were assayed at 4 week intervals. The COX II inhibitor reduced the platelet reduction experienced with PEG-IFN alpha-2a treatment of HCV despite a reduction in the plasma TPO level. Hs-P-selectin was increased in both groups. In contrast, human IL-8 levels declined to undetectable levels in virologic responders. Similarly, human IL-13 levels declined with therapy (P < 0.001). These data suggest that: (1) a COX II inhibition is associated with an increase in the platelet count despite a reduction in the TPO level; (2) human IL-8 and human IL-13 but not hs-P-selectin levels decline in those who experience an early virologic response.

  20. The PFA-100R cannot detect blood group-dependent inhibition of platelet function by eptifibatide or abciximab at therapeutic plasma concentrations.

    Science.gov (United States)

    Feuring, M; Ruf, A; Schultz, A; Wehling, M

    2010-01-01

    Previous investigations revealed that AB0 blood groups are associated with divergent concentrations of several coagulation factors. Concentrations of von Willebrand factor (vWF) and factor VIII are lower in individuals with blood group 0 compared to subjects with blood group A, B or AB, which might in turn result in a reduced inhibition of platelet aggregation in individuals with blood group 0. The aim of the present in vitro investigation was to elucidate the impact of AB0 blood group-dependent vWF concentrations on eptifibatide and abciximab mediated inhibition of GPIIb/IIIa function. Platelet function was measured with the platelet function analyzer PFA-100(R) at baseline and at increasing concentrations of eptifibatide and abciximab. It was stratified for blood group 0 vs A. If measured with the collagen/ADP cartridge, blood group 0 was associated with a prolonged mean baseline closure time in comparison with blood group A (94.3 +/- 14.6 s vs. 74.6 +/- 9.9 s, p = 0.007) which was paralleled by reduced concentrations of vWF and factor VIII. In contrast, no statistically significant differences in closure times (167.4 +/- 83.9 s vs. 140.1 +/- 99.0 s, p = 0.562) could be found in the presence of eptifibatide (0.1 microg/ml). Higher concentrations of abciximab (1 microg/ml) than those of eptifibatide were needed to increase the closure times in both cartridges of the PFA-100, but at this concentration of abciximab differences in closure times could not be detected most probably due to higher variability at these drug concentrations. The PFA-100(R) is not suitable for monitoring abciximab or eptifibatide within the therapeutic concentration range because the highest concentrations where the PFA-100(R) had measurable closure times of below 300 s is much too low to lead to the necessary platelet inhibition and, consequently, does not resemble the in vivo situation.

  1. Piperine inhibits platelet-derived growth factor-BB-induced proliferation and migration in vascular smooth muscle cells.

    Science.gov (United States)

    Lee, Kang Pa; Lee, Kwan; Park, Won-Hwan; Kim, Hyuck; Hong, Heeok

    2015-02-01

    The proliferation and migration of vascular smooth muscle cells (VSMCs) in blood vessels are important in the pathogenesis of vascular disorders such as atherosclerosis and restenosis. Piperine, a major component of black pepper, has antioxidant, anticancer, and anti-inflammatory activity. However, the antiatherosclerotic effects of piperine have not been investigated. In this study, the effects of piperine on platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of VSMCs were investigated. The antiproliferative effects of piperine were determined using MTT assays, cell counting, real-time polymerase chain reaction, and western blots. Our results showed that piperine significantly attenuated the proliferation of VSMCs by increasing the expression of p27(kip1), regulating the mRNA expression of cell cycle enzymes (cyclin D, cyclin E, and PCNA), and decreasing the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 in a noncytotoxic concentration-dependent manner (30-100 μM). Moreover, we examined the effects of piperine on the migration of PDGF-BB-stimulated VSMCs, as determined by the Boyden chamber assay, H2DCFDA staining, and western blots. Our results showed that 100 μM piperine decreased cell migration, the production of reactive oxygen species (ROS), and phosphorylation of the p38 mitogen-activated protein kinase (MAPK). Taken together, our results suggest that piperine inhibits PDGF-BB-induced proliferation and the migration of VSMCs by inducing cell cycle arrest and suppressing MAPK phosphorylation and ROS. These findings suggest that piperine may be beneficial for the treatment of vascular-related disorders and diseases.

  2. Ticagrelor effects on myocardial infarction and the impact of event adjudication in the PLATO (Platelet Inhibition and Patient Outcomes) trial.

    Science.gov (United States)

    Mahaffey, Kenneth W; Held, Claes; Wojdyla, Daniel M; James, Stefan K; Katus, Hugo A; Husted, Steen; Steg, Philippe Gabriel; Cannon, Christopher P; Becker, Richard C; Storey, Robert F; Khurmi, Nardev S; Nicolau, José C; Yu, Cheuk-Man; Ardissino, Diego; Budaj, Andrzej; Morais, Joao; Montgomery, Debra; Himmelmann, Anders; Harrington, Robert A; Wallentin, Lars

    2014-04-22

    This study sought to report the treatment effect of ticagrelor on myocardial infarction (MI) and the strategy for and impact of event adjudication in the PLATO (Platelet Inhibition and Patient Outcomes) trial. In PLATO, ticagrelor reduced cardiovascular death, MI, or stroke in patients with acute coronary syndromes (ACS). A clinical events committee (CEC) prospectively defined and adjudicated all suspected MI events, on the basis of events reported by investigators and by triggers on biomarkers. Treatment comparisons used CEC-adjudicated data, and per protocol, excluded silent MI. Overall, 1,299 (610 ticagrelor, 689 clopidogrel) MIs reported by the CEC occurred during the trial. Of these, 1,097 (504 ticagrelor, 593 clopidogrel) contributed to the primary composite endpoint. Site investigators reported 1,198 (580 ticagrelor, 618 clopidogrel) MIs. Ticagrelor significantly reduced overall MI rates (12-month CEC-adjudicated Kaplan-Meier rates: 5.8% ticagrelor, 6.9% clopidogrel; hazard ratio [HR]: 0.84; 95% confidence interval [CI]: 0.75 to 0.95). Nonprocedural MI (HR: 0.86; 95% CI: 0.74 to 1.01) and MI related to percutaneous coronary intervention or stent thrombosis tended to be lower with ticagrelor. MIs related to coronary artery bypass graft surgery were few, but numerical excess was observed in patients assigned ticagrelor. Analyses of overall MIs using investigator-reported data showed similar results but did not reach statistical significance (HR: 0.88; 95% CI: 0.78 to 1.00). In patients with ACS, ticagrelor significantly reduced the incidence of MI compared with clopidogrel, with consistent results across most MI subtypes. CEC procedures identified more MI endpoints compared with site investigators. (A Comparison of Ticagrelor [AZD6140] and Clopidogrel in Patients With Acute Coronary Syndrome [PLATO]; NCT00391872). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  3. Genistein, an isoflavone included in soy, inhibits thrombotic vessel occlusion in the mouse femoral artery and in vitro platelet aggregation.

    Science.gov (United States)

    Kondo, Kazunao; Suzuki, Yasuhiro; Ikeda, Yasuhiko; Umemura, Kazuo

    2002-11-22

    Diet can be the most important factor that influences risks for cardiovascular diseases. Genistein included in soy is one candidate that may benefit the cardiovascular system. Here, we investigated the inhibitory effects of genistein on thrombotic vessel occlusion in the mouse femoral artery using a photochemical reaction, and in vitro platelet aggregation in whole blood measured by single platelet counting. Genistein (10 mg/kg), intravenously administered 10 min before the rose bengal injection, significantly prolonged the thrombotic occlusion time from 6.1+/-0.4 to 8.4+/-0.8 min (PGenistein at doses higher than 30 microM significantly (Pgenistein was intravenously administered, ex vivo platelet aggregation induced by collagen (1 and 3 microg/ml) was significantly suppressed (Pgenistein prevented in vivo thrombogenesis and suppressed in vitro platelet aggregation. These results suggest that dietary supplementation of soy may prevent the progression of thrombosis and atherosclerosis.

  4. Cross-Linking GPVI-Fc by Anti-Fc Antibodies Potentiates Its Inhibition of Atherosclerotic Plaque- and Collagen-Induced Platelet Activation

    Directory of Open Access Journals (Sweden)

    Janina Jamasbi, RPh

    2016-04-01

    Full Text Available To enhance the antithrombotic properties of recombinant glycoprotein VI fragment crystallizable (GPVI-Fc, the authors incubated GPVI-Fc with anti-human Fc antibodies to cross-link the Fc tails of GPVI-Fc. Cross-linking potentiated the inhibition of human plaque- and collagen-induced platelet aggregation by GPVI-Fc under static and flow conditions without increasing bleeding time in vitro. Cross-linking with anti-human-Fc Fab2 was even superior to anti-human-Fc immunoglobulin G (IgG. Advanced optical imaging revealed a continuous sheath-like coverage of collagen fibers by cross-linked GPVI-Fc complexes. Cross-linking of GPVI into oligomeric complexes provides a new, highly effective, and probably safe antithrombotic treatment as it suppresses platelet GPVI-plaque interaction selectively at the site of acute atherothrombosis.

  5. 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...

  6. Retrospectively gated MRI for in vivo assessment of endothelium-dependent vasodilatation and endothelial permeability in murine models of endothelial dysfunction.

    Science.gov (United States)

    Bar, Anna; Skórka, Tomasz; Jasiński, Krzysztof; Sternak, Magdalena; Bartel, Żaneta; Tyrankiewicz, Urszula; Chlopicki, Stefan

    2016-08-01

    Endothelial dysfunction is linked to impaired endothelial-dependent vasodilatation and permeability changes. Here, we quantify both of these phenomena associated with endothelial dysfunction by MRI in vivo in mice. Endothelial function was evaluated in the brachiocephalic artery (BCA) and left carotid artery (LCA) in ApoE/LDLR(-/-) and high-fat diet (HFD)-fed mice as compared with control mice (C57BL/6J). The 3D IntraGate® FLASH sequence was used for evaluation of changes in vessels' cross-sectional area (CSA) and volume following acetylcholine (Ach) administration. Evaluation of endothelial permeability after administration of contrast agent (Galbumin, BioPAL) was based on the variable flip angle method for the assessment of parameters based on the relaxation time (T1 ) value. In order to confirm the involvement of nitric oxide (NO) in response to Ach, L-NAME-treated mice were also analyzed. To confirm that endothelial permeability changes accompany the impairment of Ach-dependent vasodilatation, permeability changes were analyzed in isolated, perfused carotid artery. In C57BL/6J mice, Ach-induced vasodilatation led to an approximately 25% increase in CSA in both vessels, which was temporarily dissociated from the effect of Ach on heart rate. In ApoE/LDLR(-/-) or HFD-fed mice Ach induced a paradoxical vasoconstriction that amounted to approximately 30% and 50% decreases in CSA of BCA and LCA respectively. In ApoE/LDLR(-/-) and HFD-fed mice endothelial permeability in BCA was also increased (fall in T1 by about 25%). In L-NAME-treated mice Ach-induced vasodilatation in BCA was lost. In isolated, perfused artery from ApoE/LDLR(-/-) mice endothelial permeability was increased. MRI-based assessment of endothelium-dependent vasodilatation induced by Ach and endothelial permeability using a retrospectively self-gated 3D gradient-echo sequence (IntraGate® FLASH) enables the reliable detection of systemic endothelial dysfunction in mice and provides an important tool

  7. Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats.

    Directory of Open Access Journals (Sweden)

    Chu-Lin Chou

    Full Text Available Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group. Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L. These results suggest a protective role of calcitriol treatment on endothelial

  8. Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats.

    Science.gov (United States)

    Chou, Chu-Lin; Pang, Cheng-Yoong; Lee, Tony J F; Fang, Te-Chao

    2015-01-01

    Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose

  9. Bone Morphogenic Protein 4-Smad-Induced Upregulation of Platelet-Derived Growth Factor AA Impairs Endothelial Function.

    Science.gov (United States)

    Hu, Weining; Zhang, Yang; Wang, Li; Lau, Chi Wai; Xu, Jian; Luo, Jiang-Yun; Gou, Lingshan; Yao, Xiaoqiang; Chen, Zhen-Yu; Ma, Ronald Ching Wan; Tian, Xiao Yu; Huang, Yu

    2016-03-01

    Bone morphogenic protein 4 (BMP4) is an important mediator of endothelial dysfunction in cardio-metabolic diseases, whereas platelet-derived growth factors (PDGFs) are major angiogenic and proinflammatory mediator, although the functional link between these 2 factors is unknown. The present study investigated whether PDGF mediates BMP4-induced endothelial dysfunction in diabetes mellitus. We generated Ad-Bmp4 to overexpress Bmp4 and Ad-Pdgfa-shRNA to knockdown Pdgfa in mice through tail intravenous injection. SMAD4-shRNA lentivirus, SMAD1-shRNA, and SMAD5 shRNA adenovirus were used for knockdown in human and mouse endothelial cells. We found that PDGF-AA impaired endothelium-dependent vasodilation in aortas and mesenteric resistance arteries. BMP4 upregulated PDGF-AA in human and mouse endothelial cells, which was abolished by BMP4 antagonist noggin or knockdown of SMAD1/5 or SMAD4. BMP4-impared relaxation in mouse aorta was also ameliorated by PDGF-AA neutralizing antibody. Tail injection of Ad-Pdgfa-shRNA ameliorates endothelial dysfunction induced by Bmp4 overexpression (Ad-Bmp4) in vivo. Serum PDGF-AA was elevated in both diabetic patients and diabetic db/db mice compared with nondiabetic controls. Pdgfa-shRNA or Bmp4-shRNA adenovirus reduced serum PDGF-AA concentration in db/db mice. PDGF-AA neutralizing antibody or tail injection with Pdgfa-shRNA adenovirus improved endothelial function in aortas and mesenteric resistance arteries from db/db mice. The effect of PDGF-AA on endothelial function in mouse aorta was also inhibited by Ad-Pdgfra-shRNA to inhibit PDGFRα. The present study provides novel evidences to show that PDGF-AA impairs endothelium-dependent vasodilation and PDGF-AA mediates BMP4-induced adverse effect on endothelial cell function through SMAD1/5- and SMAD4-dependent mechanisms. Inhibition of PGDF-AA ameliorates vascular dysfunction in diabetic mice. © 2016 American Heart Association, Inc.

  10. Early percutaneous coronary intervention, platelet inhibition with eptifibatide, and clinical outcomes in patients with acute coronary syndromes. PURSUIT Investigators

    NARCIS (Netherlands)

    N.S. Kleiman (Neal); D.V. Cokkinos (Dennis); M.L. Simoons (Maarten); R.A. Harrington (Robert Alex); R.M. Califf (Robert); E.J. Topol (Eric); A.M. Lincoff (Michael); G.C. Flaker; K.S. Pieper (Karen); R.G. Wilcox (Robert); L.G. Berdan (Lisa); T.J. Lorenz; H. Boersma (Eric)

    2000-01-01

    textabstractBACKGROUND: Platelet glycoprotein (GP) IIb/IIIa antagonists prevent the composite end point of death or myocardial infarction (MI) in patients with acute coronary syndromes. There is uncertainty about whether this effect is confined to patients who have percutaneous

  11. 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.

  12. N1-(Quinolin-2-ylmethyl) butane-1, 4-diamine, a polyamine analog: inhibition of platelet aggregation mediated by an elevated VASP, and decreased MAPK phosphorylation.

    Science.gov (United States)

    Gao, Yuan; Ji, Bian-Sheng

    2014-07-01

    The current study intended to examine the signal transduction pathway of N-(quinolin-2-ylmethyl) butane-1, 4-diamine (QMA) in antiplatelet aggregation. Rats were divided randomly into five groups: control group; QMA-treated groups (0.3, 1, and 3 mg/kg); and r-Hirudin-treated group (0.3 mg/kg). Sample groups intravenously injected the corresponding agents once a day for 5 days; control group took 0.9% NaCl in the same way. Ten minutes after the last injection, blood samples were obtained from the rat abdominal aorta. Aggregation ex vivo was tested after irritating platelets by 1.5 U/ml thrombin for 5 min with a platelet aggregometer. Malondialdehyde production, activity of superoxide dismutase and nitric oxide production were determined by the microplate reader. Measurement of [Ca]i was performed using a fluorescence spectrophotometer. Thromboxane A2, cyclic adenosine monophosphate and cyclic guanosine monophosphate levels, vasodilator-stimulated phosphoprotein, and mitogen-activated protein kinase phosphorylation were measured with ELISA kits. Phospholipase C γ2 and protein kinase C were observed by immunoblotting study. QMA inhibited thrombin-induced platelet aggregation ex vivo. QMA significantly elevated superoxide dismutase activity, levels of cyclic adenosine monophosphate, cyclic guanosine monophosphate, nitric oxide, and subsequently promoted vasodilator-stimulated phosphoprotein phosphorylation. Meanwhile, QMA suppressed phospholipase C γ2, protein kinase C and mitogen-activated protein kinase phosphorylation, as well as malondialdehyde, thromboxane A2 formation and [Ca]i mobilization. QMA has a strong antiplatelet potential via its multitarget mechanism.

  13. 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...

  14. 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.

  15. Platelet GP IIb/IIIa Receptor Inhibition by Eptifibatide in non ST-elevation MI-Acute Coronary Syndrome

    Directory of Open Access Journals (Sweden)

    M Momtahen

    2009-06-01

    Full Text Available Background: Recent trials of platelet glycoprotein IIb/IIIa receptor inhibitors have improved our understandingto best use these powerful antiplatelet drugs in acute coronary syndrome. We tested the hypothesis that inhibitionof GPIIb/IIIa platelet receptor with Eptifibatide is effective as an empiric therapy in patients with acute coronarysyndrome who do not necessarily undergo immediate revascularization.Methods: Since Feb 2006 one hundred and ninety-six patients who had presented with non ST-elevation acutecoronary syndrome (NSTE-ACS were randomly assigned to receive Eptifibatide in addition to standard therapy,for up to 72 hours or routine standard therapy. The primary end point was composite of death and non-fatalmyocardial infarction (MI or urgent target vessel revascularization (TVR in 30 days.Results: The incidence of composite end point of death, non fatal MI and urgent TVR was significantly lower inEptifibatide group than standard group (16% vs. 0% - P value <0.01,particularly in troponin positive subgroupof patients (27.8% vs. 0% - P value <0.01.Any major adverse reaction such as major bleeding, stroke, or thrombocytopenia was not seen.Conclusion: Early administration of GP IIb/IIIa receptor inhibitor is recommended in patients with high-riskacute coronary syndrome.

  16. Projected inhibition of platelet aggregation with ticagrelor twice daily vs. clopidogrel once daily based on patient adherence data (the TWICE project)

    Science.gov (United States)

    Vrijens, Bernard; Claeys, Marc J; Legrand, Victor; Vandendriessche, Eef; Van de Werf, Frans

    2014-01-01

    AIM Twice daily dosing is often perceived as inferior to once daily dosing due to a higher likelihood of missing a dose. However, more important is the extent to which drug action is maintained when doses are delayed or missed. We compared the estimated inhibition of platelet aggregation (eIPA) for ticagrelor twice daily and clopidogrel once daily, based on their pharmacokinetic/pharmacodynamic relationships and patient dosing history data. METHODS Drug dosing histories of 5014 patients prescribed cardiovascular medications (primarily antihypertensive medicines) were extracted from an electronically compiled dosing history database. eIPA levels were simulated for 677 twice daily and 677 once daily dosing histories over a 30 day period, based on published onset/offset models for ticagrelor and clopidogrel IPA characteristics. RESULTS While many patients treated twice daily missed at least one dose in 30 days, only 25.7% missed two consecutive doses. By comparison, 46.8% of patients treated once daily missed at least one dose. Simulations based on patient adherence over time showed that the average mean eIPA for ticagrelor twice daily remained significantly higher than for clopidogrel once daily (81.1% vs. 55.0%, P Ticagrelor twice daily patients had an eIPA below 10% for 0.20% of the 30 day period compared with 2.05% for clopidogrel once daily (P A= 0.0001). CONCLUSIONS The projected level of platelet inhibition remained higher for ticagrelor twice daily than clopidogrel once daily, mainly due to the higher eIPA level achieved with ticagrelor and the relatively low likelihood of missing two consecutive twice daily doses. This modelling and simulation study suggests a therapeutic benefit of ticagrelor over clopidogrel when taking into account the most common dosing omissions. PMID:24868573

  17. Projected inhibition of platelet aggregation with ticagrelor twice daily vs. clopidogrel once daily based on patient adherence data (the TWICE project).

    Science.gov (United States)

    Vrijens, Bernard; Claeys, Marc J; Legrand, Victor; Vandendriessche, Eef; Van de Werf, Frans

    2014-05-01

    Twice daily dosing is often perceived as inferior to once daily dosing due to a higher likelihood of missing a dose. However, more important is the extent to which drug action is maintained when doses are delayed or missed. We compared the estimated inhibition of platelet aggregation (eIPA) for ticagrelor twice daily and clopidogrel once daily, based on their pharmacokinetic/ pharmacodynamic relationships and patient dosing history data. Drug dosing histories of 5014 patients prescribed cardiovascular medications (primarily antihypertensive medicines) were extracted from an electronically compiled dosing history database. eIPA levels were simulated for 677 twice daily and 677 once daily dosing histories over a 30 day period, based on published onset/offset models for ticagrelor and clopidogrel IPA characteristics. While many patients treated twice daily missed at least one dose in 30 days, only 25.7% missed two consecutive doses. By comparison, 46.8% of patients treated once daily missed at least one dose. Simulations based on patient adherence over time showed that the average mean eIPA for ticagrelor twice daily remained significantly higher than for clopidogrel once daily (81.1% vs. 55.0%, P Ticagrelor twice daily patients had an eIPA below 10% for 0.20% of the 30 day period compared with 2.05% for clopidogrel once daily (P = 0.0001). The projected level of platelet inhibition remained higher for ticagrelor twice daily than clopidogrel once daily, mainly due to the higher eIPA level achieved with ticagrelor and the relatively low likelihood of missing two consecutive twice daily doses. This modelling and simulation study suggests a therapeutic benefit of ticagrelor over clopidogrel when taking into account the most common dosing omissions. © 2013 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd

  18. Preaggregation reactions of platelets.

    Science.gov (United States)

    Gear, A R

    1981-09-01

    Whether platelet volume increases during the morphological changes preceding aggregation has been investigated. Previous research is controversial; resistive-counting techniques reveal an increase, centrifugal methods do not. Platelets were sized with a computerized, resistive-particle counter before and after incubation with adenosine diphosphate (ADP). Resistive volume increased by 14% (p less than 0.001) in the absence of EDTA, and only 7% in its presence (ADP, 10 micro M). EDTA inhibited platelet volume changes, whether these were shrinking induced by warming or swelling by ADP. Handling of platelets, such as during centrifugation, also caused particle swelling. Particle density decreased after ADP exposure, without release of serotonin, suggesting uptake of water. Platelet shape was experimentally manipulated to test the hypothesis that resistive volume changes stem from artifacts of particle shape. Scanning electron microscopy confirmed that colchicine, chlorpromazine, and a temperature cycle of 0 degrees to 37 degrees all caused extensive alteration from the disc shape. Subsequent exposure to ADP increased resistive volume, and in the case of chlorpromazine, no long pseudopodia were extruded. It is concluded that preaggregation reactions of platelets can be associated with an increase in particle volume, and that earlier research based on centrifugation and the presence of ETA failed to reveal the increase because of inhibitory and apparent swelling effects.

  19. Efeito dos ácidos graxos ômega-3 sobre o relaxamento-dependente do endotélio em coelhos hipercolesterolêmicos Effects of omega-3 fatty acids on endothelium-dependent relaxation in hypercholesterolemic rabbits

    Directory of Open Access Journals (Sweden)

    Paulo Afonso Ribeiro Jorge

    1997-07-01

    Full Text Available OBJETIVO: Estudar o efeito dos ácidos graxos ômega-3 sobre o relaxamento-dependente do endotélio, o colesterol plasmático, as LDL, VLDL, HDL, triglicérides e a peroxidação lipídica das partículas de LDL-nativas, oxidadas e da parede arterial. MÉTODOS: Coelhos da raça Nova Zelândia foram submetidos a dieta enriquecida com colesterol (0,5% e gordura de coco (2%, por 30 dias e separados em grupo hipercolesterolemia (H e ômega-3 (O-3, sendo administrado ao O-3 ácidos graxos ômega-3 na dose de 300mg/kg/dia, durante 15 dias, através de gavagem. O colesterol plasmático, triglicérides, LDL-colesterol, VLDL e HDL-colesterol foram medidos através de kits enzimáticos e os resultados expressos em mg/dl. As LDL foram obtidas por ultracentrifugação e oxidadas através da exposição ao Cu++. A peroxidação lipídica das LDL e da parede da aorta foi mensurada pela dosagem do malondialdeido (MDA. A função endotelial foi avaliada por curvas de concentração-efeito obtidas pela acetilcolina e nitroprussiato, após contração com norepinefrina. RESULTADOS: Houve aumento do colesterol plasmático e das VLDL, sem interferência nos níveis de LDL e HDL, no O-3. Observou-se redução significante dos triglicérides. Verificou-se aumento significante do teor de MDA nas LDL-nativas e oxidadas, assim como na parede arterial. O relaxamento-dependente do endotélio foi significativamente menor no O-3. CONCLUSÃO: A administração de ácidos graxos ômega-3 na dosagem de 300/mg/kg/dia, a coelhos hipercolesterolêmicos aumentou o colesterol e as VLDL plasmáticas, enquanto reduziu os triglicérides. O relaxamento-dependente do endotélio foi menor que no grupo H.PURPOSE: To study the effect of omega-3 fatty acid on endothelium-dependent relaxation, total plasma cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides levels as well as, the malondialdehyde (MDA content of the LDL particles and arterial wall. METHODS: Fourteen male rabbits

  20. Rupatadine inhibits inflammatory mediator release from human laboratory of allergic diseases 2 cultured mast cells stimulated by platelet-activating factor.

    Science.gov (United States)

    Alevizos, Michail; Karagkouni, Anna; Vasiadi, Magdalini; Sismanopoulos, Nikolaos; Makris, Michael; Kalogeromitros, Dimitrios; Theoharides, Theoharis C

    2013-12-01

    Mast cells are involved in allergy and inflammation by the secretion of multiple mediators, including histamine, cytokines, and platelet-activating factor (PAF), in response to different triggers, including emotional stress. PAF has been associated with allergic inflammation, but there are no clinically available PAF inhibitors. To investigate whether PAF could stimulate human mast cell mediator release and whether rupatadine (RUP), a dual histamine-1 and PAF receptor antagonist, could inhibit the effect of PAF on human mast cells. Laboratory of allergic diseases 2 cultured mast cells were stimulated with PAF (0.001, 0.01, and 0.1 μmol/L) and substance P (1 μmol/L) with or without pretreatment with RUP (2.5 and 25 μmol/L), which was added 10 minutes before stimulation. Release of β-hexosaminidase was measured in supernatant fluid by spectrophotoscopy, and histamine, interleukin-8, and tumor necrosis factor were measured by enzyme-linked immunosorbent assay. PAF stimulated a statistically significant release of histamine, interleukin-8, and tumor necrosis factor (0.001-0.1 μmol/L) that was comparable to that stimulated by substance P. Pretreatment with RUP (25 μmol/L) for 10 minutes inhibited this effect. In contrast, pretreatment of laboratory of allergic diseases 2 cells with diphenhydramine (25 μmol/L) did not inhibit mediator release, suggesting that the effect of RUP was not due to its antihistaminic effect. PAF stimulates human mast cell release of proinflammatory mediators that is inhibited by RUP. This action endows RUP with additional properties in treating allergic inflammation. Copyright © 2013 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  1. Effects of antimycin A and 2-deoxyglucose on secretion in human platelets. Differential inhibition of the secretion of acid hydrolases and adenine nucleotides.

    Science.gov (United States)

    Holmsen, H; Robkin, L; Day, H J

    1979-08-15

    1. Shape change, aggregation and secretion of dense-granule constituents in platelets differ in their dependence on cellular energy metabolism. The possibility that such a difference also exists between secretion of dense-granule constituents and acid hydrolases was investigated. 2. Human platelets were incubated with [(14)C]adenine in plasma, and then washed and resuspended in salt solutions. The effects of incubating the cells with antimycin A and 2-deoxyglucose on the concentrations of [(14)C]ATP, ADP, AMP, IMP and inosine plus hypoxanthine and on thrombin-induced secretion of ATP plus ADP and acid hydrolases were studied. The metabolic inhibitors only affected (14)C-labelled nucleotides, whereas thrombin only liberated unlabelled ATP and ADP. 3. The extent of secretion decreased progressively with time during incubation with the metabolic inhibitors. At any time the secretion of acid hydrolases, beta-N-acetylglucosaminidase, beta-glucuronidase and beta-galactosidase was inhibited to a greater extent than secretion of ATP plus ADP (dense-granule secretion). 4. Incubation with the metabolic inhibitors shifted the log (dose)-response relationship to higher thrombin concentrations, and with a greater shift for acid hydrolase secretion than for dense-granule secretion. 5. Antimycin, when present alone, caused a marked decrease in the rate of acid hydrolase secretion, but had no effect on dense-granule secretion. 6. These results further support the view that acid hydrolase secretion and dense-granule secretion are separate processes with different requirements for ATP energy. Acid hydrolase secretion, but not dense-granule secretion, appears to depend on a simultaneous rapid generation of ATP, which can be accomplished by oxidative, but not by glycolytic, ATP production.

  2. Ticagrelor vs. clopidogrel in patients with acute coronary syndromes and diabetes: a substudy from the PLATelet inhibition and patient Outcomes (PLATO) trial.

    Science.gov (United States)

    James, Stefan; Angiolillo, Dominick J; Cornel, Jan H; Erlinge, David; Husted, Steen; Kontny, Frederic; Maya, Juan; Nicolau, Josë C; Spinar, Jindrich; Storey, Robert F; Stevens, Susanna R; Wallentin, Lars

    2010-12-01

    patients with diabetes mellitus (DM) have high platelet reactivity and are at increased risk of ischaemic events and bleeding post-acute coronary syndromes (ACS). In the PLATelet inhibition and patient Outcomes (PLATO) trial, ticagrelor reduced the primary composite endpoint of cardiovascular death, myocardial infarction, or stroke, but with similar rates of major bleeding compared with clopidogrel. We aimed to investigate the outcome with ticagrelor vs. clopidogrel in patients with DM or poor glycaemic control. we analysed patients with pre-existing DM (n = 4662), including 1036 patients on insulin, those without DM (n = 13 951), and subgroups based on admission levels of haemoglobin A1c (HbA1c; n = 15 150). In patients with DM, the reduction in the primary composite endpoint (HR: 0.88, 95% CI: 0.76-1.03), all-cause mortality (HR: 0.82, 95% CI: 0.66-1.01), and stent thrombosis (HR: 0.65, 95% CI: 0.36-1.17) with no increase in major bleeding (HR: 0.95, 95% CI: 0.81-1.12) with ticagrelor was consistent with the overall cohort and without significant diabetes status-by-treatment interactions. There was no heterogeneity between patients with or without ongoing insulin treatment. ticagrelor reduced the primary endpoint, all-cause mortality, and stent thrombosis in patients with HbA1c above the median (HR: 0.80, 95% CI: 0.70-0.91; HR: 0.78, 95% CI: 0.65-0.93; and HR: 0.62, 95% CI: 0.39-1.00, respectively) with similar bleeding rates (HR: 0.98, 95% CI: 0.86-1.12). ticagrelor, when compared with clopidogrel, reduced ischaemic events in ACS patients irrespective of diabetic status and glycaemic control, without an increase in major bleeding events.

  3. Triazolopyrimidine (trapidil), a platelet-derived growth factor antagonist, inhibits parathyroid bone disease in an animal model for chronic hyperparathyroidism

    Science.gov (United States)

    Lotinun, Sutada; Sibonga, Jean D.; Turner, Russell T.

    2003-01-01

    Parathyroid bone disease in humans is caused by chronic hyperparathyroidism (HPT). Continuous infusion of PTH into rats results in histological changes similar to parathyroid bone disease, including increased bone formation, focal bone resorption, and severe peritrabecular fibrosis, whereas pulsatile PTH increases bone formation without skeletal abnormalities. Using a cDNA microarray with over 5000 genes, we identified an association between increased platelet-derived growth factor-A (PDGF-A) signaling and PTH-induced bone disease in rats. Verification of PDGF-A overexpression was accomplished with a ribonuclease protection assay. Using immunohistochemistry, PDGF-A peptide was localized to mast cells in PTH-treated rats. We also report a novel strategy for prevention of parathyroid bone disease using triazolopyrimidine (trapidil). Trapidil, an inhibitor of PDGF signaling, did not have any effect on indexes of bone turnover in normal rats. However, dramatic reductions in marrow fibrosis and bone resorption, but not bone formation, were observed in PTH-treated rats given trapidil. Also, trapidil antagonized the PTH-induced increases in mRNA levels for PDGF-A. These results suggest that PDGF signaling is important for the detrimental skeletal effects of HPT, and drugs that target the cytokine or its receptor might be useful in reducing or preventing parathyroid bone disease.

  4. The Oligo Fucoidan Inhibits Platelet-Derived Growth Factor-Stimulated Proliferation of Airway Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Chao-Huei Yang

    2016-01-01

    Full Text Available In the pathogenesis of asthma, the proliferation of airway smooth muscle cells (ASMCs is a key factor in airway remodeling and causes airway narrowing. In addition, ASMCs are also the effector cells of airway inflammation. Fucoidan extracted from marine brown algae polysaccharides has antiviral, antioxidant, antimicrobial, anticlotting, and anticancer properties; however, its effectiveness for asthma has not been elucidated thus far. Platelet-derived growth factor (PDGF-treated primary ASMCs were cultured with or without oligo-fucoidan (100, 500, or 1000 µg/mL to evaluate its effects on cell proliferation, cell cycle, apoptosis, and Akt, ERK1/2 signaling pathway. We found that PDGF (40 ng/mL increased the proliferation of ASMCs by 2.5-fold after 48 h (p < 0.05. Oligo-fucoidan reduced the proliferation of PDGF-stimulated ASMCs by 75%–99% after 48 h (p < 0.05 and induced G1/G0 cell cycle arrest, but did not induce apoptosis. Further, oligo-fucoidan supplementation reduced PDGF-stimulated extracellular signal-regulated kinase (ERK1/2, Akt, and nuclear factor (NF-κB phosphorylation. Taken together, oligo-fucoidan supplementation might reduce proliferation of PDGF-treated ASMCs through the suppression of ERK1/2 and Akt phosphorylation and NF-κB activation. The results provide basis for future animal experiments and human trials.

  5. Selective Inhibition of ADAM17 Efficiently Mediates Glycoprotein Ibα Retention During Ex Vivo Generation of Human Induced Pluripotent Stem Cell-Derived Platelets.

    Science.gov (United States)

    Hirata, Shinji; Murata, Takahiko; Suzuki, Daisuke; Nakamura, Sou; Jono-Ohnishi, Ryoko; Hirose, Hidenori; Sawaguchi, Akira; Nishimura, Satoshi; Sugimoto, Naoshi; Eto, Koji

    2016-10-05

    : Donor-independent platelet concentrates for transfusion can be produced in vitro from induced pluripotent stem cells (iPSCs). However, culture at 37°C induces ectodomain shedding on platelets of glycoprotein Ibα (GPIbα), the von Willebrand factor receptor critical for adhesive function and platelet lifetime in vivo, through temperature-dependent activation of a disintegrin and metalloproteinase 17 (ADAM17). The shedding can be suppressed by using inhibitors of panmetalloproteinases and possibly of the upstream regulator p38 mitogen-activated protein kinase (p38 MAPK), but residues of these inhibitors in the final platelet products may be accompanied by harmful risks that prevent clinical application. Here, we optimized the culture conditions for generating human iPSC-derived GPIbα(+) platelets, focusing on culture temperature and additives, by comparing a new and safe selective ADAM17 inhibitor, KP-457, with previous inhibitors. Because cultivation at 24°C (at which conventional platelet concentrates are stored) markedly diminished the yield of platelets with high expression of platelet receptors, 37°C was requisite for normal platelet production from iPSCs. KP-457 blocked GPIbα shedding from iPSC platelets at a lower half-maximal inhibitory concentration than panmetalloproteinase inhibitor GM-6001, whereas p38 MAPK inhibitors did not. iPSC platelets generated in the presence of KP-457 exhibited improved GPIbα-dependent aggregation not inferior to human fresh platelets. A thrombus formation model using immunodeficient mice after platelet transfusion revealed that iPSC platelets generated with KP-457 exerted better hemostatic function in vivo. Our findings suggest that KP-457, unlike GM-6001 or p38 MAPK inhibitors, effectively enhances the production of functional human iPSC-derived platelets at 37°C, which is an important step toward their clinical application. This study is a tip for overcoming a practical but critical barrier for manufacturing human

  6. Anticoagulant mechanism and platelet deaggregation property of a non-cytotoxic, acidic phospholipase A2 purified from Indian cobra (Naja naja) venom: inhibition of anticoagulant activity by low molecular weight heparin.

    Science.gov (United States)

    Dutta, Sumita; Gogoi, Debananda; Mukherjee, Ashis K

    2015-03-01

    In the present study, anticoagulant and platelet modulating activities of an acidic phospholipase A2 (NnPLA2-I) purified from Indian cobra Naja naja venom was investigated. The NnPLA2-I displayed a mass of 15.2 kDa and 14,186.0 Da when analyzed by SDS-PAGE and MALDI-TOF-MS, respectively. Peptide mass fingerprinting analysis of the NnPLA2-I showed its significant similarity with phospholipase A2 enzymes purified from cobra venom. BLAST analysis of one tryptic peptide sequence of NnPLA2-I demonstrated putative conserved domains of the PLA2-like superfamily. The Km and Vmax values of NnPLA2-I toward hydrolysis of its most preferred substrate-phosphotidylcholine (PC)-were determined to be 0.72 mM and 29.3 μmol min(-1) mg(-1), respectively. The anticoagulant activity of NnPLA2-I was found to be higher than the anticoagulant activity of heparin/AT-III or warfarin. The histidine modifying reagent, monovalent and polyvalent antivenom differentially inhibited the catalytic and anticoagulant activities of NnPLA2-I. Low molecular weight heparin did not inhibit the catalytic and platelet deaggregation activity of NnPLA2-I, albeit its anticoagulant activity was significantly reduced. The NnPLA2-I showed a non-enzymatic, mixed inhibition of thrombin with a Ki value of 9.3 nM. Heparin significantly decreased, with an IC50 value of 15.23 mIU, the thrombin inhibitory activity of NnPLA2-I. The NnPLA2-I uniquely increased the amidolytic activity of FXa without influencing its prothrombin activating property. NnPLA2-I showed dose-dependent deaggregation of platelet rich plasma (PRP) and inhibited the collagen and thrombin-induced aggregation of PRP. However, deaggregation of washed platelets by NnPLA2-I demonstrated in presence of PC or platelet poor plasma. Alkylation of histidine residue of NnPLA2-I resulted in 95% and 21% reduction of its platelet deaggregation and platelet binding properties, respectively. NnPLA2-I did not show cytotoxicity against human glioblastoma U87MG cells

  7. Sponge-derived acetylenic alcohols, petrosiols, inhibit proliferation and migration of platelet-derived growth factor (PDGF)-induced vascular smooth muscle cells.

    Science.gov (United States)

    Choi, Bong-Keun; Cha, Byung-Yoon; Yagyu, Takuya; Woo, Je-Tae; Ojika, Makoto

    2013-04-01

    Platelet-derived growth factor (PDGF) induces the proliferation and migration of vascular smooth muscle cells (VSMCs), leading to the development of various vascular disorders such as restenosis and atherosclerosis. Therefore, inhibitors of PDGF-induced cellular events would be candidate agents for treating these diseases. During the search for such inhibitors from marine sources, we isolated petrosiols A-D (1-4) and related compounds from the marine sponge Petrosia strongylata. These metabolites, which we previously reported as neurotrophic substances, showed an inhibitory effect on PDGF-induced DNA synthesis at IC50 values of 0.69-2.2 μM. Petrosiol A (1) inhibited PDGF-induced cell proliferation without remarkable cytotoxicity and arrested cell cycle progression from the G0/G1 to S phase by inducing the downregulation of the expression of G1 checkpoint proteins cyclin D1, cyclin E, cyclin-dependent kinases (CDK)2, and CDK4 and the upregulation of the expression of p21 and p27. In addition, petrosiol A (1) inhibited the phosphorylation of PDGF receptor-β and its downstream proteins such as phospholipase C (PLC)-γ1, Akt, and extracellular signal-regulated kinase (ERK)1/2. These results suggest that 1 inhibited PDGF-induced VSMC proliferation by interrupting the phosphorylation of PDGF receptor-β followed by downstream signal transduction. Furthermore, petrosiol A (1) suppressed PDGF-induced actin filament dissociation and cell migration, suggesting that 1 and its derivatives may be used for the prevention and treatment of vascular diseases. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Coadministration of ticagrelor and ritonavir: Toward prospective dose adjustment to maintain an optimal platelet inhibition using the PBPK approach

    OpenAIRE

    Marsousi, Niloufar; Samer, Caroline Flora; Fontana, Pierre; Reny, Jean-Luc; Rudaz, Serge; Desmeules, Jules Alexandre; Daali, Youssef

    2016-01-01

    Ticagrelor is a potent antiplatelet drug metabolized by cytochrome (CYP)3A. It is contraindicated in patients with human immunodeficiency virus (HIV) because of the expected CYP3A inhibition by most protease inhibitors, such as ritonavir and an increased bleeding risk. In this study, a physiologically based pharmacokinetic (PBPK) model was created for ticagrelor and its active metabolite (AM). Based on the simulated interaction between ticagrelor 180 mg and ritonavir 100 mg, a lower dose of t...

  9. Antioxidants change platelet responses to various stimulating events

    OpenAIRE

    Sobotková, Alžběta; Mášová-Chrastinová, Leona; Suttnar, Jiří; Štikarová, Jana; Májek, Pavel; Reicheltová, Zuzana; Kotlín, Roman; Weisel, John W.; Malý, Martin; Jan E. Dyr

    2009-01-01

    The role of platelets in hemostasis may be influenced by alteration of the platelet redox state—the presence of antioxidants and the formation of reactive oxygen and nitrogen species. We investigated the effects of two antioxidants, resveratrol and trolox, on platelet activation. Trolox and resveratrol inhibited aggregation of washed platelets and platelet-rich plasma activated by ADP, collagen, and thrombin receptor-activating peptide. Resveratrol was a more effective agent in reducing plate...

  10. Camptothecin inhibits platelet-derived growth factor-BB-induced proliferation of rat aortic vascular smooth muscle cells through inhibition of PI3K/Akt signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eun-Seok [Department of Applied Biochemistry, Division of Life Science, College of Health and Biomedical Science, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Kang, Shin-il [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of); Yoo, Kyu-dong [Hazardous Substances Analysis Division, Gwangju Regional Food and Drug Administration, Gwangju (Korea, Republic of); Lee, Mi-Yea [Department of Nursing Kyungbok University, Pocheon (Korea, Republic of); Yoo, Hwan-Soo; Hong, Jin-Tae [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of); Shin, Hwa-Sup [Department of Applied Biochemistry, Division of Life Science, College of Health and Biomedical Science, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Kim, Bokyung [Department of Physiology, Konkuk Medical School, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Yun, Yeo-Pyo, E-mail: ypyun@chungbuk.ac.kr [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of)

    2013-04-15

    The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is a major cause of vascular disorders such as atherosclerosis and restenosis after angioplasty. In this study, we investigated not only the inhibitory effects of camptothecin (CPT) on PDGF-BB-induced VSMC proliferation, but also its molecular mechanism of this inhibition. CPT significantly inhibited proliferation with IC50 value of 0.58 μM and the DNA synthesis of PDGF-BB-stimulated VSMCs in a dose-dependent manner (0.5–2 μM ) without any cytotoxicity. CPT induced the cell cycle arrest at G0/G1 phase. Also, CPT decreased the expressions of G0/G1-specific regulatory proteins including cyclin-dependent kinase (CDK)2, cyclin D1 and PCNA in PDGF-BB-stimulated VSMCs. Pre-incubation of VSMCs with CPT significantly inhibited PDGF-BB-induced Akt activation, whereas CPT did not affect PDGF-receptor beta phosphorylation, extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and phospholipase C (PLC)-γ1 phosphorylation in PDGF-BB signaling pathway. Our data showed that CPT pre-treatment inhibited VSMC proliferation, and that the inhibitory effect of CPT was enhanced by LY294002, a PI3K inhibitor, on PDGF-BB-induced VSMC proliferation. In addition, inhibiting the PI3K/Akt pathway by LY294002 significantly enhanced the suppression of PCNA expression and Akt activation by CPT. These results suggest that the anti-proliferative activity of CPT is mediated in part by downregulating the PI3K/Akt signaling pathway. - Highlights: ► CPT inhibits proliferation of PDGF-BB-induced VSMC without cytotoxicity. ► CPT arrests the cell cycle in G0/G1 phase by downregulation of cyclin D1 and CDK2. ► CPT significantly attenuates Akt phosphorylation in PDGF-BB signaling pathway. ► LY294002 enhanced the inhibitory effect of CPT on VSMC proliferation. ► Thus, CPT is mediated by downregulating the PI3K/Akt signaling pathway.

  11. Effects of cancer on platelets.

    Science.gov (United States)

    van Es, Nick; Sturk, Auguste; Middeldorp, Saskia; Nieuwland, Rienk

    2014-06-01

    The main function of circulating platelets is to stop bleeding upon vascular injury by the formation of a hemostatic plug. The presence of cancer results in numerical and functional abnormalities of platelets. Thrombocytosis is commonly observed in cancer patients and is associated with decreased survival. Conversely, thrombocytopenia has been shown to have antimetastatic effects in experimental models. Tumor cells also can induce changes in the platelet activation status, both in direct and indirect manners. Direct tumor cell-induced platelet aggregation enables the formation of a cloak of aggregated platelets around circulating tumor cells (CTCs) that shields them from attacks by the immune system and facilitates metastasis to distant sites. Cancer also can induce platelet activation in various indirect ways. Tumor cells shed small extracellular vesicles that expose the transmembrane protein tissue factor (TF)--the initiator of the extrinsic coagulation cascade. The abundant presence of TF in the circulation of cancer patients can result in local generation of thrombin, the most potent platelet activator. Another pathway of indirect platelet activation is by increased formation of neutrophil extracellular traps in the presence of tumor-secreted granulocyte colony-stimulating factor (G-CSF). Last, tumor cells may regulate the selective secretion of angiogenic proteins from platelet granules, which enables the tumor to stimulate and stabilize the immature neovasculature in the tumor environment. Since there is little doubt that the cancer-induced platelet alterations are beneficial to tumor growth and dissemination, it could be worthwhile to intervene in the underlying mechanisms for anticancer purposes. Antiplatelet and anticoagulant agents that inhibit platelet activation and thrombin generation can potentially slow cancer progression, although the clinical evidence thus far is not unequivocal. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. A novel family of RGD-containing disintegrin (Tablysin-15) from the salivary gland of the horsefly Tabanus yao targets integrins αIIbβ3 and αVβ3 and inhibits platelet aggregation and angiogenesis

    Science.gov (United States)

    Ma, Dongying; Xu, Xueqing; An, Su; Liu, Huan; Yang, Xuening; Andersen, John F.; Wang, Yipeng; Tokumasu, Fuyuki; Ribeiro, José M. C.; Francischetti, Ivo M. B.; Lai, Ren

    2012-01-01

    A novel family of RGD-containing molecule (Tablysin-15) has been molecularly characterized from the salivary gland of the hematophagous horsefly Tabanus yao. Tablysin-15 does not share primary sequence homology to any disintegrin discovered so far, and displays an RGD motif in the N-terminus of the molecule. It is also distinct from disintegrins from Viperidae since its mature form is not released from a metalloproteinase precursor. Tablysin-15 exhibits high affinity for platelet αIIbβ3 and endothelial cell αvβ3 integrins, but not for α5β1 or α2β1. Accordingly, it blocks endothelial cell adhesion to vitronectin (IC50 ~ 1 nM) and marginally to fibronectin (IC50 ~ 1 µM), but not to collagen. It also inhibits FGF-induced endothelial cell proliferation, and attenuates tube formation in vitro. In platelets, Tablysin-15 inhibits aggregation induced by collagen, ADP and convulxin, and prevents static platelet adhesion to immobilized fibrinogen. In addition, solid-phase assays and flow cytometry demonstrates that αIIbβ3 binds to Tablysin-15. Moreover, immobilized Tablysin-15 supports platelet adhesion by a mechanism which was blocked by anti-integrin αIIbβ3 monoclonal antibody (e.g. abciximab) or by EDTA. Furthermore, Tablysin-15 dose-dependently attenuates thrombus formation to collagen under flow, without affecting platelet adhesion to collagen fibrils. Consistent with these findings, Tablysin-15 displays antithrombotic properties in vivo suggesting that it is a useful tool to block αIIbβ3, or as a prototype to develop antithrombotics. The RGD motif in the unique sequence of Tablysin-15 represents a novel template for studying the structure-function relationship of the disintegrin family of inhibitors. PMID:21475772

  13. Vasorelaxant and anti-platelet aggregation effects of aqueous Ocimum basilicum extract.

    Science.gov (United States)

    Amrani, Souliman; Harnafi, Hicham; Gadi, Dounia; Mekhfi, Hassane; Legssyer, Abdelkhaleq; Aziz, Mohammed; Martin-Nizard, Françoise; Bosca, Lisardo

    2009-08-17

    In this work the endothelium-dependant vasorelaxant and anti-platelet aggregation activities of an aqueous extract from Ocimum basilicum were studied. The vasorelaxant effect was undertaken in thoracic aorta from three experimental groups of rats: one of them (NCG) fed with standard diet, the second (HCG) with hypercholesterolemic diet (HCD) and the third (BTG) with hypercholesterolemic diet together with an intragastric administration of Ocimum basilicum extract at a dose of 0.5 g/kg body weight for a period of 10 weeks. The in vitro anti-platelet aggregation of Ocimum basilicum extract was studied using thrombin (0.5 U/ml) and ADP (5 microM) as agonists. The results show that the HCD statistically decreases vascular relaxation in HCG compared to NCG (pOcimum basilicum extract exerts a significant vasorelaxant effect at 10(-5) M (pOcimum basilicum as medicinal plant could be beneficial for cardiovascular system.

  14. Inhibition of platelet-derived growth factor (PDGF) receptor affects follicular development and ovarian proliferation, apoptosis and angiogenesis in prepubertal eCG-treated rats.

    Science.gov (United States)

    Pascuali, Natalia; Scotti, Leopoldina; Abramovich, Dalhia; Irusta, Griselda; Di Pietro, Mariana; Bas, Diana; Tesone, Marta; Parborell, Fernanda

    2015-09-05

    The platelet-derived growth factor (PDGF) system is crucial for blood vessel stability. In the present study, we evaluated whether PDGFs play a critical intraovarian survival role in gonadotropin-dependent folliculogenesis. We examined the effect of intrabursal administration of a selective platelet-derived growth factor receptor (PDGFR) inhibitor (AG1295) on follicular development, proliferation, apoptosis and blood vessel formation and stability in ovaries from rats treated with equine chorionic gonadotropin (eCG). The percentages of preantral follicles (PAFs) and early antral follicles (EAFs) were lower in AG1295-treated ovaries than in control ovaries (p < 0.01-0.05). The percentage of atretic follicles (AtrFs) increased in AG1295-treated ovaries compared to control (p < 0.05). The ovarian weight and estradiol concentrations were lower in AG1295-treated ovaries than in the control group (p < 0.01 and p < 0.05, respectively), whereas progesterone concentrations did not change. AG1295 decreased the proliferation index in EAFs (p < 0.05) and increased the percentage of nuclei positive for cleaved caspase-3 and apoptotic DNA fragmentation (p < 0.01-0.05). AG1295 increased the expression of Bax (p < 0.05) without changes in the expression of Bcl-2 protein. AG1295-treated ovaries increased the cleavage of caspase-8 (p < 0.05) and decreased AKT and BAD phosphorylation compared with control ovaries (p < 0.05). AG1295 caused a decrease not only in the endothelial cell area but also in the area of pericytes and vascular smooth muscle cells (VSMCs) in the ovary (p < 0.05). Our findings suggest that the local inhibition of PDGFs causes an increase in ovarian apoptosis through an imbalance in the ratio of antiapoptotic to proapoptotic proteins, thus leading a larger number of follicles to atresia. PDGFs could exert their mechanism of action through an autocrine/paracrine effect on granulosa and theca cells mediated by PDGFRs. In

  15. Complement Activation Alters Platelet Function

    Science.gov (United States)

    2014-10-01

    been shown to participate directly in the immune response through interaction with vascular endothelium , with antigen presenting cells (APC) and...Syk inhibition decreases platelet lodging in the lungs indicating Syk is integral in platelet sequestration and organ damage. Crossing B6.lpr...adhesive phenotype: role of PAF in spatially regulating neutrophil adhesion and spreading. Blood 110:1879-1886. 7. Lapchak, P.H., A. Ioannou, P. Rani

  16. Platelet Donation

    Science.gov (United States)

    ... body. I imagined the faces of many different strangers, taking time out of their day… their jobs… ... thing to do for another human being. A stranger. Someone’s platelets made their way to Phil that ...

  17. Platelet Function Tests

    Science.gov (United States)

    ... Patient Resources For Health Professionals Subscribe Search Platelet Function Tests Send Us Your Feedback Choose Topic At ... Also Known As Platelet Aggregation Studies PFT Platelet Function Assay PFA Formal Name Platelet Function Tests This ...

  18. Platelet antibodies blood test

    Science.gov (United States)

    This blood test shows if you have antibodies against platelets in your blood. Platelets are a part of the blood ... Chernecky CC, Berger BJ. Platelet antibody - blood. In: Chernecky ... caused by platelet destruction, hypersplenism, or hemodilution. ...

  19. LDL oxidation by platelets propagates platelet activation via an oxidative stress-mediated mechanism.

    Science.gov (United States)

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

    2014-11-01

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

  20. Pulmonary function in patients with acute coronary syndrome treated with ticagrelor or clopidogrel (from the Platelet Inhibition and Patient Outcomes [PLATO] pulmonary function substudy).

    Science.gov (United States)

    Storey, Robert F; Becker, Richard C; Harrington, Robert A; Husted, Steen; James, Stefan K; Cools, Frank; Steg, Philippe Gabriel; Khurmi, Nardev S; Emanuelsson, Hakan; Lim, Soo Teik; Cannon, Christopher P; Katus, Hugo A; Wallentin, Lars

    2011-12-01

    The Platelet Inhibition and Patient Outcomes (PLATO) trial showed that ticagrelor reduced the risk for cardiovascular events in patients with acute coronary syndromes compared to clopidogrel but was associated with increased incidence of dyspnea. This substudy assessed whether ticagrelor affects pulmonary function in patients with acute coronary syndromes: 199 patients enrolled in the PLATO trial and receiving randomized treatment with ticagrelor 90 mg twice daily (n = 101) or clopidogrel 75 mg/day (n = 98) took part in the pulmonary function substudy. Patients with advanced lung disease, congestive heart failure, or coronary artery bypass graft surgery after the index event were excluded. Pulse oximetry (blood oxygen saturation), spirometry (forced expiratory volume in 1 second, forced vital capacity, and forced expiratory flow between 25% and 75% of forced vital capacity before and 20 minutes after inhalation of a β(2) agonist), lung volumes (total lung capacity, functional residual capacity, residual volume), and diffusion capacity were performed after patients received study medication for 30 to 40 days. Tests were then repeated <10 days before and approximately 30 days after the discontinuation of study medication. After a mean treatment duration of 31 days, there were no differences between the groups for any of the pulmonary function parameters. At the end of treatment (mean 211 days) and after the discontinuation of study medication (mean 32 days after the last dose), there was also no evidence of a change in pulmonary function in either group. For example, forced expiratory volume in 1 second values before β(2) agonist inhalation in the ticagrelor and clopidogrel groups were 2.81 ± 0.73 and 2.70 ± 0.84 L, respectively, at the first visit and did not change significantly at subsequent visits. In conclusion, no effect of ticagrelor on pulmonary function was seen in this cohort of patients with acute coronary syndromes compared to clopidogrel. Copyright

  1. Relationship Between Early and Late Nonsustained Ventricular Tachycardia and Cardiovascular Death in Patients With Acute Coronary Syndrome in the Platelet Inhibition and Patient Outcomes (PLATO) Trial.

    Science.gov (United States)

    Bui, An H; Cannon, Christopher P; Steg, Philippe Gabriel; Storey, Robert F; Husted, Steen; Guo, Jianping; Im, KyungAh; James, Stefan K; Michelson, Eric L; Himmelmann, Anders; Held, Claes; Varenhorst, Christoph; Wallentin, Lars; Scirica, Benjamin M

    2016-02-01

    Nonsustained ventricular tachycardia (NSVT) is common after acute coronary syndrome (ACS) and a marker of increased risk of arrhythmogenic death. However, the prognostic significance of NSVT when evaluated with other contemporary risk markers and at later time points after ACS remains uncertain. In the Platelet Inhibition and Patient Outcomes (PLATO) trial, continuous ECGs were performed during the first 7 days after ACS (n=2866) and repeated for another 7 days at day 30 (n=1991). Median follow-up was 1 year. There was a time-varying interaction between NSVT and cardiovascular death such that NSVT was significantly associated with increased risk within the first 30 days after randomization (22/999 [2.2%] versus 16/1825 [0.9%]; adjusted hazard ratio, 2.84; 95% confidence interval, 1.39-5.79; P=0.004) but not after 30 days (28/929 [3.0%] versus 42/1734 [2.4%]; P=0.71). Detection of NSVT during the convalescent phase (n=428/1991; 21.5%) was also associated with an increased risk of cardiovascular death, and was most marked within the first 2 months after detection (1.9% versus 0.3%; adjusted hazard ratio, 5.48; 95% confidence interval, 1.07-28.20; P=0.01), and then decreasing over time such that the relationship was no longer significant by ≈5 months after ACS. NSVT occurred frequently during the acute and convalescent phases of ACS. The risk of cardiovascular death associated with NSVT was the greatest during the first 30 days after presentation; however, patients with NSVT detected during the convalescent phase were also at a significantly increased risk of cardiovascular death that persisted for an additional several months after the index event. http://www.clinicaltrials.gov. Unique identifier: NCT00391872. © 2016 American Heart Association, Inc.

  2. Ticagrelor Versus Clopidogrel in Patients With Acute Coronary Syndromes and Chronic Obstructive Pulmonary Disease: An Analysis From the Platelet Inhibition and Patient Outcomes (PLATO) Trial.

    Science.gov (United States)

    Andell, Pontus; James, Stefan K; Cannon, Christopher P; Cyr, Derek D; Himmelmann, Anders; Husted, Steen; Keltai, Matyas; Koul, Sasha; Santoso, Anwar; Steg, Ph Gabriel; Storey, Robert F; Wallentin, Lars; Erlinge, David

    2015-10-09

    Patients with chronic obstructive pulmonary disease (COPD) experiencing acute coronary syndromes (ACS) are at high risk for clinical events. In the Platelet Inhibition and Patient Outcomes (PLATO) trial, ticagrelor versus clopidogrel reduced the primary endpoint of death from vascular causes, myocardial infarction, or stroke after ACS, but increased the incidence of dyspnea, which may lead clinicians to withhold ticagrelor from COPD patients. In 18 624 patients with ACS randomized to treatment with ticagrelor or clopidogrel, history of COPD was recorded in 1085 (5.8%). At 1 year, the primary endpoint occurred in 17.7% of patients with COPD versus 10.4% in those without COPD (PPLATO-defined major bleeding rates at 1 year 14.6% versus 16.6% (HR=0.85; 95% CI: 0.61 to 1.17). Dyspnea occurred more frequently with ticagrelor (26.1% vs. 16.3%; HR=1.71; 95% CI: 1.28 to 2.30). There was no differential increase in the relative risk of dyspnea compared to non-COPD patients (HR=1.85). No COPD status-by-treatment interactions were found, showing consistency with the main trial results. In this post-hoc analysis, COPD patients experienced high rates of ischemic events. Ticagrelor versus clopidogrel reduced and substantially decreased the absolute risk of ischemic events (5.8%) in COPD patients, without increasing overall major bleeding events. The benefit-risk profile supports the use of ticagrelor in patients with ACS and concomitant COPD. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00391872. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  3. Ticagrelor versus clopidogrel in patients with acute coronary syndromes intended for non-invasive management: substudy from prospective randomised PLATelet inhibition and patient Outcomes (PLATO) trial.

    Science.gov (United States)

    James, Stefan K; Roe, Matthew T; Cannon, Christopher P; Cornel, Jan H; Horrow, Jay; Husted, Steen; Katus, Hugo; Morais, Joao; Steg, Ph Gabriel; Storey, Robert F; Stevens, Susanna; Wallentin, Lars; Harrington, Robert A

    2011-06-17

    To evaluate efficacy and safety outcomes in patients in the PLATelet inhibition and patient Outcomes (PLATO) trial who at randomisation were planned for a non-invasive treatment strategy. Pre-specified analysis of pre-randomisation defined subgroup of prospective randomised clinical trial. 862 centres in 43 countries. 5216 (28%) of 18,624 patients admitted to hospital for acute coronary syndrome who were specified as planned for non-invasive management. Randomised treatment with ticagrelor (n=2601) versus clopidogrel (2615). Primary composite end point of cardiovascular death, myocardial infarction, and stroke; their individual components; and PLATO defined major bleeding during one year. 2183 (41.9%) patients had coronary angiography during their initial hospital admission, 1065 (20.4%) had percutaneous coronary intervention, and 208 (4.0%) had coronary artery bypass surgery. Cumulatively, 3143 (60.3%) patients had been managed non-invasively by the end of follow-up. The incidence of the primary end point was lower with ticagrelor than with clopidogrel (12.0% (n=295) v 14.3% (346); hazard ratio 0.85, 95% confidence interval 0.73 to 1.00; P=0.04). Overall mortality was also lower (6.1% (147) v 8.2% (195); 0.75, 0.61 to 0.93; P=0.01). The incidence of total major bleeding (11.9% (272) v 10.3% (238); 1.17, 0.98 to 1.39; P=0.08) and non-coronary artery bypass grafting related major bleeding (4.0% (90) v 3.1% (71); 1.30, 0.95 to 1.77; P=0.10) was numerically higher with ticagrelor than with clopidogrel. In patients with acute coronary syndrome initially intended for non-invasive management, the benefits of ticagrelor over clopidogrel were consistent with those from the overall PLATO results, indicating the broad benefits of P2Y12 inhibition with ticagrelor regardless of intended management strategy. Clinical trials NCT00391872.

  4. Mechanisms underlying the endothelium-dependent vasodilatory ...

    African Journals Online (AJOL)

    Relaxations to EGE were abolished by the membrane permeant, SOD mimetic, MnTMPyP, and significantly reduced by wortmannin, an inhibitor of PI3-kinase. Exposure of endothelial cells to EGE increased the phosphorylation level of eNOS at Ser1177 in a time and concentration-dependent manner. MnTMPyP abolished ...

  5. 109 ENDOTHELIUM-DEPENDENT AND -INDEPENDENT ...

    African Journals Online (AJOL)

    using a 25% urethane and 1% chloralose mixture given intraperitoneally at a dose of 5mg/kg. ... to control (P<0.05).The IC50 of acetylcholine in aortic rings from L-NAME rats (7.9 x 10-1 ± 6.0 x 10-. 3) was significantly higher than in rings from control (9.4 x 10-8 ± 2.8 x 10-8), .... with a 95% O2 5% CO2 gas mixture (pH 7.35-.

  6. 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.

  7. Flow cytometric assessment of activation of peripheral blood platelets in dogs with normal platelet count and asymptomatic thrombocytopenia.

    Science.gov (United States)

    Żmigrodzka, M; Guzera, M; Winnicka, A

    2016-01-01

    Platelets play a crucial role in hemostasis. Their activation has not yet been evaluated in healthy dogs with a normal and low platelet count. The aim of this study was to determine the influence of activators on platelet activation in dogs with a normal platelet count and asymptomatic thrombocytopenia. 72 clinically healthy dogs were enrolled. Patients were allocated into three groups. Group 1 consisted of 30 dogs with a normal platelet count, group 2 included 22 dogs with a platelet count between 100 and 200×109/l and group 3 consisted of 20 dogs with a platelet count lower than 100×109/l. Platelet rich-plasma (PRP) was obtained from peripheral blood samples using tripotassium ethylenediaminetetraacetic acid (K3-EDTA) as anticoagulant. Next, platelets were stimulated using phorbol-12-myristate-13-acetate or thrombin, stabilized using procaine or left unstimulated. The expression of CD51 and CD41/CD61 was evaluated. Co-expression of CD41/CD61 and Annexin V served as a marker of platelet activation. The expression of CD41/CD61 and CD51 did not differ between the 3 groups. Thrombin-stimulated platelets had a significantly higher activity in dogs with a normal platelet count than in dogs with asymptomatic thrombocytopenia. Procaine inhibited platelet activity in all groups. In conclusion, activation of platelets of healthy dogs in vitro varied depending on the platelet count and platelet activator.

  8. Eptifibatide provides additional platelet inhibition in non-ST-elevation myocardial infarction patients already treated with aspirin and clopidogrel. Results of the platelet activity extinction in non-Q-wave myocardial infarction with aspirin, clopidogrel, and eptifibatide (PEACE) study.

    Science.gov (United States)

    Dalby, Miles; Montalescot, Gilles; Bal dit Sollier, Claire; Vicaut, Eric; Soulat, Thierry; Collet, Jean Philippe; Choussat, Rémi; Gallois, Vanessa; Drobinski, Gérard; Drouet, Ludovic; Thomas, Daniel

    2004-01-21

    The present study hypothesis was that eptifibatide offered further antiplatelet efficacy above clopidogrel in non-ST-elevation myocardial infarction (NSTEMI) patients before an expeditive coronary intervention. Although thienopyridines and glycoprotein (GP) IIb/IIIa antagonists are often co-prescribed in the context of NSTEMI, the antiplatelet interaction of these agents is poorly described and the superiority of GP IIb/IIIa antagonists above thienopyridine treatment alone is not clear. Thirty-two NSTEMI patients treated with aspirin and enoxaparin were studied using flow cytometry to define parameters of platelet activation with a panel of agonists before clopidogrel, after clopidogrel, and during an eptifibatide infusion following the clopidogrel load. After platelet activation with adenosine diphosphate, thrombin receptor-activating peptide, or U46-619, relative reductions in conformationally activated GP IIb/IIIa receptor expression (evaluated with PAC-1) of 48%, 43%, and 33%, respectively (all p pro-inflammatory effect.

  9. Amiodarona causa vasodilatação dependente do endotélio em artérias coronárias caninas Amiodarone causes endothelium-dependent vasodilation in canine coronary arteries

    Directory of Open Access Journals (Sweden)

    Alfredo José Rodrigues

    2005-03-01

    polysorbate 80, amiodarone dissolved in water, amiodarone dissolved in polysorbate 80, and a commercial presentation of amiodarone (Cordarone. The experiments were conducted in the presence of the following enzymatic blockers: only indomethacin, Nw-nitro-L-arginine associated with indomethacin, and only Nw-nitro-L-arginine. RESULTS: Polysorbate 80 caused a small degree of nonendothelium-dependent relaxation. Cordarone, amiodarone dissolved in water, and amiodarone dissolved in polysorbate 80 caused endothelium-dependent relaxation, which was greater for amiodarone dissolved in polysorbate and for Cordarone. Only the association of indomethacin and Nw-nitro-L-arginine could eliminate the endothelium-dependent relaxation caused by amiodarone dissolved in polysorbate 80. CONCLUSION: The results obtained indicate that vasodilation promoted by amiodarone in canine coronary arteries is mainly caused by stimulation of the release of nitric oxide and cyclooxygenase-dependent relaxing endothelial factors.

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

    Science.gov (United States)

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

    2015-08-01

    Regular consumption of chocolate and cocoa products has been linked to reduced cardiovascular mortality. This study compared the effects of high flavanol dark chocolate (HFDC; 1064mg flavanols/day for 6weeks) and low flavanol dark chocolate (LFDC; 88mg flavanols/day for 6weeks) on blood pressure, heart rate, vascular function and platelet aggregation in men with pre-hypertension or mild hypertension. Vascular function was assessed by pulse wave analysis using radial artery applanation tonometry in combination with inhaled salbutamol (0.4mg) to assess changes due to endothelium-dependent vasodilatation. HFDC did not significantly reduce blood pressure compared to baseline or LFDC. Heart rate was increased by LFDC compared to baseline, but not by HFDC. Vascular responses to salbutamol tended to be greater after HFDC. Platelet aggregation induced by collagen or the thromboxane analogue U46619 was unchanged after LFDC or HFDC, whereas both chocolates reduced responses to ADP and the thrombin receptor activator peptide, SFLLRNamide (TRAP6), relative to baseline. Pre-incubation of platelets with theobromine also attenuated platelet aggregation induced by ADP or TRAP6. We conclude that consumption of HFDC confers modest improvements in cardiovascular function. Platelet aggregation is modulated by a flavanol-independent mechanism that is likely due to theobromine. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. 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)

  12. Drug-Free Platelets Can Act as Seeds for Aggregate Formation During Antiplatelet Therapy

    Science.gov (United States)

    Hoefer, Thomas; Armstrong, Paul C.; Finsterbusch, Michaela; Chan, Melissa V.; Kirkby, Nicholas S.

    2015-01-01

    Objective— Reduced antiplatelet drug efficacy occurs in conditions of increased platelet turnover, associated with increased proportions of drug-free, that is, uninhibited, platelets. Here, we detail mechanisms by which drug-free platelets promote platelet aggregation in the face of standard antiplatelet therapy. Approach and Results— To model standard antiplatelet therapy, platelets were treated in vitro with aspirin, the P2Y12 receptor blocker prasugrel active metabolite, or aspirin plus prasugrel active metabolite. Different proportions of uninhibited platelets were then introduced. Light transmission aggregometry analysis demonstrated clear positive associations between proportions of drug-free platelets and percentage platelet aggregation in response to a range of platelet agonists. Using differential platelet labeling coupled with advanced flow cytometry and confocal imaging we found aggregates formed in mixtures of aspirin-inhibited platelets together with drug-free platelets were characterized by intermingled platelet populations. This distribution is in accordance with the ability of drug-free platelets to generate thromboxane A2 and so drive secondary platelet activation. Conversely, aggregates formed in mixtures of prasugrel active metabolite–inhibited or aspirin plus prasugrel active metabolite–inhibited platelets together with drug-free platelets were characterized by distinct cores of drug-free platelets. This distribution is consistent with the ability of drug-free platelets to respond to the secondary activator ADP. Conclusions— These experiments are the first to image the interactions of inhibited and uninhibited platelets in the formation of platelet aggregates. They demonstrate that a general population of platelets can contain subpopulations that respond strikingly differently to overall stimulation of the population and so act as the seed for platelet aggregation. PMID:26272940

  13. The efficacy of ticagrelor is maintained in women with acute coronary syndromes participating in the prospective, randomized, PLATelet inhibition and patient Outcomes (PLATO) trial.

    Science.gov (United States)

    Husted, Steen; James, Stefan K; Bach, Richard G; Becker, Richard C; Budaj, Andrzej; Heras, Magda; Himmelmann, Anders; Horrow, Jay; Katus, Hugo A; Lassila, Riita; Morais, Joao; Nicolau, José C; Steg, Ph Gabriel; Storey, Robert F; Wojdyla, Daniel; Wallentin, Lars

    2014-06-14

    The aim of this study was to assess the relationship between sex and clinical outcomes and treatment-related complications in patients with ST-elevation or non-ST-elevation acute coronary syndromes (ACS) randomized to treatment with ticagrelor or clopidogrel in the PLATelet inhibition and patient Outcomes (PLATO) trial. The associations between sex subgroup and the primary composite outcomes, secondary outcomes, and major bleeding endpoints as well as interaction of sex subgroup with treatment effects were analysed using Cox proportional-hazards models. Sex was not significantly associated with the probability of the primary composite endpoint [adjusted hazard ratio (HR): 1.02 (0.91-1.16)], or other adverse cardiovascular endpoints. Ticagrelor was similarly more effective than clopidogrel in reducing rates of the primary endpoint in women 11.2 vs. 13.2% [adjusted HR: 0.88 (0.74-1.06)] and men 9.4 vs. 11.1% [adjusted HR: 0.86 (0.76-0.97)] (interaction P-value 0.78), all-cause death in women 5.8 vs. 6.8% [adjusted HR: 0.90 (0.69-1.16)] and men 4.0 vs. 5.7% [adjusted HR: 0.80 (0.67-0.96)] (interaction P-value 0.49), and definite stent thrombosis in women 1.2 vs. 1.4% [adjusted HR: 0.71 (0.36-1.38)] and men 1.4 vs. 2.1% [adjusted HR: 0.63 (0.45-0.89)] (interaction P-value 0.78). The treatments did not differ for PLATO-defined overall major bleeding complications in women [adjusted HR: 1.01 (0.83-1.23)] or men [adjusted HR: 1.10 (0.98-1.24)]. Sex had no significant association with these outcomes (interactions P = 0.43-0.88). Female sex is not an independent risk factor for adverse clinical outcomes in moderate-to-high risk ACS patients. Ticagrelor has a similar efficacy and safety profile in men and women. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Cardiology.

  14. Osteoprotegerin Is Associated With Major Bleeding But Not With Cardiovascular Outcomes in Patients With Acute Coronary Syndromes: Insights From the PLATO (Platelet Inhibition and Patient Outcomes) Trial.

    Science.gov (United States)

    Ueland, Thor; Åkerblom, Axel; Ghukasyan, Tatevik; Michelsen, Annika E; Aukrust, Pål; Becker, Richard C; Bertilsson, Maria; Himmelmann, Anders; James, Stefan K; Siegbahn, Agneta; Storey, Robert F; Kontny, Frederic; Wallentin, Lars

    2018-01-12

    Elevated levels of osteoprotegerin, a secreted tumor necrosis factor-related molecule, might be associated with adverse outcomes in patients with coronary artery disease. We measured plasma osteoprotegerin concentrations on hospital admission, at discharge, and at 1 and 6 months after discharge in a predefined subset (n=5135) of patients with acute coronary syndromes in the PLATO (Platelet Inhibition and Patient Outcomes) trial. The associations between osteoprotegerin and the composite end point of cardiovascular death, nonprocedural spontaneous myocardial infarction or stroke, and non-coronary artery bypass grafting major bleeding during 1 year of follow-up were assessed by Cox proportional hazards models. Event rates of the composite end point per increasing quartile groups at baseline were 5.2%, 7.5%, 9.2%, and 11.9%. A 50% increase in osteoprotegerin level was associated with a hazard ratio (HR) of 1.31 (95% confidence interval [CI], 1.21-1.42) for the composite end point but was not significant in adjusted analysis (ie, clinical characteristics and levels of C-reactive protein, troponin T, NT-proBNP [N-terminal pro-B-type natriuretic peptide], and growth differentiation factor-15). The corresponding rates of non-coronary artery bypass grafting major bleeding were 2.4%, 2.2%, 3.8%, and 7.2%, with an unadjusted HR of 1.52 (95% CI, 1.36-1.69), and a fully adjusted HR of 1.26 (95% CI, 1.09-1.46). The multivariable association between the osteoprotegerin concentrations and the primary end point after 1 month resulted in an HR of 1.09 (95% CI, 0.89-1.33); for major bleeding after 1 month, the HR was 1.33 (95% CI, 0.91-1.96). In patients with acute coronary syndrome treated with dual antiplatelet therapy, osteoprotegerin was an independent marker of major bleeding but not of ischemic cardiovascular events. Thus, high osteoprotegerin levels may be useful in increasing awareness of increased bleeding risk in patients with acute coronary syndrome receiving

  15. Enhanced platelet MRP4 expression and correlation with platelet function in patients under chronic aspirin treatment.

    Science.gov (United States)

    Massimi, Isabella; Lotti, Lavinia Vittoria; Temperilli, Flavia; Mancone, Massimo; Sardella, Gennaro; Calcagno, Simone; Turriziani, Ombretta; Frati, Luigi; Pulcinelli, Fabio M

    2016-11-30

    Platelet multidrug resistance protein4 (MRP4)-overexpression has a role in reducing aspirin action. Aspirin in vivo treatment enhances platelet MRP4 expression and MRP4 mediated transport inhibition reduces platelet function and delays thrombus formation. The aim of our work was to verify whether MRP4 expression is enhanced in platelets obtained from patients under chronic aspirin treatment and whether it correlates with residual platelet reactivity. We evaluated changes on mRNA and protein-MRP4 expression and platelet aggregation in four populations: healthy volunteers (HV), aspirin-free control population (CTR), patients who started the treatment less than one month ago (ASAaspirinated patients who started the treatment more than two months ago (ASA>2 months patients). In platelets obtained from ASA>2 months patients, it was found a statistically significant MRP4 enhancement of both mRNA and protein expression compared to HV, CTR and ASA2 months patients that present high levels of platelet MRP4, have higher serum TxB2 levels and collagen-induced platelet aggregation compared to patient with low levels of MRP4 in platelets. In addition collagen induced platelet aggregation is higher in in vitro aspirinated platelets obtained from patients with high levels of MRP4 patients compared to those obtained from patients with low MRP4 levels. We can assert that, in patients under chronic aspirin treatment, platelets that present high MRP4 levels have an increase of residual platelet reactivity, which is due in part to incomplete COX-1 inhibition, and in part to COX-1-independent mechanism.

  16. Platelet transfusion.

    Science.gov (United States)

    1998-01-01

    The statement printed below was agreed at a consensus conference on platelet transfusion organised by the Royal College of Physicians of Edinburgh and held in Edinburgh in November 1997. We publish this statement at the request of the organising committee to bring it to the attention of physicians who do not read the haematological literature. The statement will also appear in the British Journal of Haematology in 1998 with the scientific evidence upon which it is based.

  17. 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.

  18. Platelet Supernatant Suppresses LPS-Induced Nitric Oxide Production from Macrophages Accompanied by Inhibition of NF-κB Signaling and Increased Arginase-1 Expression.

    Directory of Open Access Journals (Sweden)

    Yusuke Ando

    Full Text Available We previously reported that mouse bone marrow-derived macrophages (BMDMs that had been co-cultured with platelets exhibited lower susceptibility to bacterial lipopolysaccharide (LPS and produced lower levels of nitric oxide (NO and inflammatory cytokines including TNF-α and IL-6. The suppression of macrophage responses was mediated, at least in part, by platelet supernatant. In the present study, we assessed phenotypic changes of BMDMs induced by incubation with the supernatant from thrombin-activated platelets (PLT-sup and found that BMDMs cultured with PLT-sup (PLT-BMDMs expressed a lower level of inducible NO synthase (iNOS and a higher level of arginase-1, both of which are involved in the L-arginine metabolism, upon stimulation with LPS or zymosan. We also examined possible modulation of the NF-κB signaling pathway and observed suppression of IκBα phosphorylation and a decrease of NF-κB p65 expression in LPS-stimulated PLT-BMDMs. These results suggest that PLT-sup suppresses inflammatory responses of BMDMs via negative regulation of NF-κB signaling leading to lowered expression of iNOS and enhanced L-arginine catabolism by arginase-1.

  19. Gallic Acid Attenuates Platelet Activation and Platelet-Leukocyte Aggregation: Involving Pathways of Akt and GSK3β

    Directory of Open Access Journals (Sweden)

    Shih-Sheng Chang

    2012-01-01

    Full Text Available Platelet activation and its interaction with leukocytes play an important role in atherothrombosis. Cardiovascular diseases resulted from atherothrombosis remain the major causes of death worldwide. Gallic acid, a major constituent of red wine and tea, has been believed to have properties of cardiovascular protection, which is likely to be related to its antioxidant effects. Nonetheless, there were few and inconsistent data regarding the effects of gallic acid on platelet function. Therefore, we designed this in vitro study to determine whether gallic acid could inhibit platelet activation and the possible mechanisms. From our results, gallic acid could concentration-dependently inhibit platelet aggregation, P-selectin expression, and platelet-leukocyte aggregation. Gallic acid prevented the elevation of intracellular calcium and attenuated phosphorylation of PKCα/p38 MAPK and Akt/GSK3β on platelets stimulated by the stimulants ADP or U46619. This is the first mechanistic explanation for the inhibitory effects on platelets from gallic acid.

  20. [Study on platelet-associated tissue factor and its significance].

    Science.gov (United States)

    Huang, Xi-lian; Chen, Fang-ping; Du, Jian-wei; Peng, Min-yuan; Fu, Bin; Xie, Qin-zhi; He, Shi-lin

    2005-09-01

    To explore whether normal platelet contains tissue factor (TF), and the significance of platelet-associated TF (PATF). Platelets were isolated by Sepharose 2B gel column. ELISA was used to detect the TF content in the lysates of washed platelets. Procoagulant activity of PATF was measured by one stage clotting time assay. The mRNA of TF was detected by reverse transcription polymerase chain reaction (RT-PCR). A certain amount of TF antigen (16.37 +/- 6.39) ng/L was detected in the washed-platelet lysates. Upon activation by collagen, platelets released TF and caused a marked increase in TF level in plasma (P collagen increased significantly, which could be blocked by TF McAb and poor VII plasma. TF mRNA could not be detected in washed platelets. TF content in platelets from patients with coronary heart disease was significantly higher than that from normal controls (P < 0.05). Resting platelets from the patients showed a higher procoagulant activity, which could be inhibited by TF McAb. Platelets contain TF and the latter released by activated platelet was functionally active. Platelet itself might not synthesize TF. Protein content and procoagulant activity of PATF in patients with coronary heart disease were higher than that in controls. All these indicate that platelet may be involved in coagulation and thrombosis by releasing TF.

  1. Impacto dos stents e do sirolimus por via oral na vasomotilidade coronariana dependente e independente do endotelio Impact of stenting and oral sirolimus on endothelium-dependent and independent coronary vasomotion

    Directory of Open Access Journals (Sweden)

    Rósley Weber Alvarenga Fernandes

    2012-04-01

    compared to bare metal stenting (BMS. OBJECTIVE: This study aims to assess the impact of BMS and the effect of oral sirolimus on endothelial function. METHODS: Forty-five patients were randomized into three groups: BMS + high-dose oral sirolimus (initial dose of 15 mg, followed by 6 mg/day for four weeks; BMS + low-dose sirolimus (6 mg followed by 2 mg daily for four weeks; and BMS without sirolimus. Changes in vasoconstriction or vasodilation in a 15 mm segment starting at the distal stent end in response to acetylcholine and nitroglycerin were assessed by quantitative angiography. RESULTS: The groups had similar angiographic characteristics. The percent variation in diameter in response to acetylcholine was similar in all groups at the two time points (p = 0.469. Four hours after stenting, the target segment presented an endothelial dysfunction that was maintained after eight months in all groups. In all groups, endothelium-independent vasomotion in response to nitroglycerin was similar at four hours and eight months, with increased target segment diameter after nitroglycerin infusion (p = 0.001. CONCLUSION: The endothelial dysfunction was similarly present at the 15 mm segment distal to the treated segment, at 4 hours and 8 months after stenting. Sirolimus administered orally during 4 weeks to prevent restenosis did not affect the status of endothelium-dependent and independent vasomotion.

  2. Vesiculation of platelets during in vitro aging.

    Science.gov (United States)

    Bode, A P; Orton, S M; Frye, M J; Udis, B J

    1991-02-15

    Membranous microparticles (MP) appearing in the supernatant plasma of stored platelet concentrates (PC) were analyzed by flow cytometry. Two populations of MP were arbitrarily delineated by light scatter as larger or smaller than 0.5 micron fluorescent beads. An estimate of MP concentration was obtained by adding a known amount of fluorescent beads to each sample before analysis of a set number of counts on the flow cytometer. The addition of platelet activation inhibitors (prostaglandin E-1, theophylline, and aprotinin) to the anticoagulant during preparation of PC combined with a reduction in surface area of the storage container caused approximately a 40% reduction in the number of MP appearing during storage relative to donor-matched controls. In addition, the inhibited concentrates had 84% less platelet factor 3 (PF3) activity in the supernatant and 61% less released lactic dehydrogenase. A reduction in surface area of the container in the controls partially offset these differences. A significant correlation was found (rs = .748) between PF3 levels and the concentration of larger MP. The inhibitors did not reduce the small number of MP found in stored platelet-poor plasma. Surface antigen analysis showed that the majority of MP in PC were platelet-derived; most were positive for glycoprotein (GP) IIbIIIa (73%) and/or for GPIb (43% to 46%). We conclude that procoagulant MP are released from platelets during storage as a result of platelet activation augmented by interaction of platelets with the bag wall.

  3. Antioxidants change platelet responses to various stimulating events

    Science.gov (United States)

    Sobotková, Alžběta; Mášová-Chrastinová, Leona; Suttnar, Jiří; Štikarová, Jana; Májek, Pavel; Reicheltová, Zuzana; Kotlín, Roman; Weisel, John W.; Malý, Martin; Dyr, Jan E.

    2010-01-01

    The role of platelets in hemostasis may be influenced by alteration of the platelet redox state—the presence of antioxidants and the formation of reactive oxygen and nitrogen species. We investigated the effects of two antioxidants, resveratrol and trolox, on platelet activation. Trolox and resveratrol inhibited aggregation of washed platelets and platelet-rich plasma activated by ADP, collagen, and thrombin receptor-activating peptide. Resveratrol was a more effective agent in reducing platelet static and dynamic adhesion in comparison with trolox. The antioxidant capacity of resveratrol was, however, the same as that of trolox. After incubation of platelets with antioxidants, the resveratrol intraplatelet concentration was about five times lower than the intracellular concentration of trolox. Although both antioxidants comparably lowered hydroxyl radical and malondialdehyde production in platelets stimulated with collagen, TxB2 levels were decreased by resveratrol much more effectively than by trolox. Cyclooxygenase 1 was inhibited by resveratrol and not by trolox. Our data indicate that antioxidants, apart from nonspecific redox or radical-quenching mechanisms, inhibit platelet activation also by specific interaction with target proteins. The results also show the importance of studying platelet activation under conditions of real blood flow in contact with reactive surfaces, e.g., using dynamic adhesion experiments. PMID:19766712

  4. Towards evidence-based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 1: Which form of aspirin is the fastest to inhibit platelet aggregation in emergency department patients with non-ST segment elevation myocardial infarction?

    Science.gov (United States)

    Morris, Niall; Rigg, Kaitlynn; Hogg, Kerstin

    2015-10-01

    A short cut review was carried out to establish whether, in patients with suspected acute coronary syndromes presenting to the emergency department, what form of aspirin has the most rapid onset of action. Papers comparing the speed of onset of chewable aspirin, or soluble aspirin or solid aspirin were included. This summarises all three parts of a combined best evidence topic report (BET). The clinical bottom line is that chewable aspirin may be faster than soluble aspirin at decreasing the amount of time to achieve platelet inhibition in a patient. Soluble aspirin is faster than whole solid aspirin, which is faster than enteric-coated aspirin. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. Reactivation of Gαi-coupled formyl peptide receptors is inhibited by Gαq-selective inhibitors when induced by signals generated by the platelet-activating factor receptor.

    Science.gov (United States)

    Holdfeldt, André; Dahlstrand Rudin, Agnes; Gabl, Michael; Rajabkhani, Zahra; König, Gabriele M; Kostenis, Evi; Dahlgren, Claes; Forsman, Huamei

    2017-09-01

    Formyl peptide receptor (FPR)-desensitized neutrophils display increased production/release of superoxide (O2-) when activated by platelet-activating factor (PAF), a priming of the response achieved through a unique receptor crosstalk mechanism. The aim of this study was to determine the effect of an inhibitor selective for small, heterotrimeric G proteins belonging to the Gαq subclass on that receptor crosstalk. We show that signals generated by FPRs and the PAF receptor (PAFR) induce activation of the neutrophil O2-, producing NADPH-oxidase, and that response was sensitive to Gαq inhibition in cells activated by PAF, but no inhibition was obtained in cells activated by FPR agonists. Signaling in naive neutrophils is terminated fairly rapidly, and the receptors become homologously desensitized. The downstream sensitivity to Gαq inhibition in desensitized cells displaying increased production/release of O2- through the PAFR receptor crosstalk mechanism also comprised the reactivation of the FPRs, and the activation signals were redirected from the PAFR to the desensitized/reactivated FPRs. The Gαq-dependent activation signals generated by the PAFRs activate the Gαi-coupled FPRs, a receptor crosstalk that represents a novel pathway by which G protein-coupled receptors can be regulated and signaling can be turned on and off. © Society for Leukocyte Biology.

  6. Technetium-99m labeled 50H. 19 antibody fragments: interaction of the antibody with platelets

    Energy Technology Data Exchange (ETDEWEB)

    Valone, F.H.; Stricker, R.B.; Zamora, P.O.; Shah, V.O.; Mann, P.L.

    1988-01-01

    The monoclonal antibody 50H.19 recognized three antigens (Msub(tau) = 31-, 40-, 45-K) on normal and thromboasthenic platelets, but only one (Msub(tau) = 31-K) on Bernard-Soulier platelets. The intact antibody and its F(ab')/sub 2/ fragments, had direct platelet-aggregating activity, and induced the platelet release reaction. The intact antibody potentiated platelet aggregation induced by platelet-activating factor or thrombin. Additions of indomethacin did not inhibit aggregation: addition of PGI/sub 2/, or a calcium channel blocker completely inhibited aggregation. A reduced amount of platelet-aggregating activity was observed with antibody fragments prepared for labeling with sup(99m)Tc by pre-exposure to stannous ions, and herein used in biodistribution studies and elsewhere in thrombus imaging studies. Antibody fragments radiolabeled with sup(99m)Tc bound to isolated platelets and to clots containing platelets.

  7. Human blood platelets lack nitric oxide synthase activity.

    Science.gov (United States)

    Böhmer, Anke; Gambaryan, Stepan; Tsikas, Dimitrios

    2015-01-01

    Reports on expression and functionality of nitric oxide synthase (NOS) activity in human blood platelets and erythrocytes are contradictory. We used a specific gas chromatography-mass spectrometry (GC-MS) method to detect NOS activity in human platelets. The method measures simultaneously [(15)N]nitrite and [(15)N]nitrate formed from oxidized (15)N-labeled nitric oxide ((15)NO) upon its NOS-catalyzed formation from the substrate l-[guanidino-(15)N2]-arginine. Using this GC-MS assay, we did not detect functional NOS in non-stimulated platelets and in intact platelets activated by various agonists (adenosine diphosphate, collagen, thrombin, or von Willebrand factor) or lysed platelets. l-[guanidino-nitro]-Arginine-inhibitable NOS activity was measured after addition of recombinant human endothelial NOS to lysed platelets. Previous and recent studies from our group challenge expression and functionality of NOS in human platelets and erythrocytes.

  8. Evaluating platelet aggregation dynamics from laser speckle fluctuations.

    Science.gov (United States)

    Hajjarian, Zeinab; Tshikudi, Diane M; Nadkarni, Seemantini K

    2017-07-01

    Platelets are key to maintaining hemostasis and impaired platelet aggregation could lead to hemorrhage or thrombosis. We report a new approach that exploits laser speckle intensity fluctuations, emanated from a drop of platelet-rich-plasma (PRP), to profile aggregation. Speckle fluctuation rate is quantified by the speckle intensity autocorrelation, g2(t), from which the aggregate size is deduced. We first apply this approach to evaluate polystyrene bead aggregation, triggered by salt. Next, we assess dose-dependent platelet aggregation and inhibition in human PRP spiked with adenosine diphosphate and clopidogrel. Additional spatio-temporal speckle analyses yield 2-dimensional maps of particle displacements to visualize platelet aggregate foci within minutes and quantify aggregation dynamics. These findings demonstrate the unique opportunity for assessing platelet health within minutes for diagnosing bleeding disorders and monitoring anti-platelet therapies.

  9. Dabigatran reduces thrombin-induced platelet aggregation and activation in a dose-dependent manner

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Nielsen, Christian; Söderström, Anna Cecilia

    2017-01-01

    Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet thrombin receptors. The aim was to investigate the effect of dabigatran on platelet activation and platelet aggregation. Healthy donor...... platelet activation and platelet thrombin receptor expression (SPAN-12 and WEDE-15 expression). Agonists were thrombin, thrombin receptor-activating peptide, protease-activated receptor-4 agonist, collagen, collagen-related peptide, arachidonic acid, and adenosine diphosphate. All concentrations...... of dabigatran fully inhibited platelet aggregation for thrombin up to 2 IU/mL, while dabigatran did not affect platelet aggregation by other agonists. Platelet activation (percentage of platelets positive for activated GPIIb/IIIa, CD63, P-selectin) was reduced after thrombin stimulation in samples...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-03-01

    Ethanol is reported to inhibit platelet aggregation in vivo and in vitro, but the mechanisms of its action on stimulus-response coupling in platelets is unknown. Platelet aggregation to thrombin occurs through at least three pathways: released ADP; thromboxane A/sub 2/ (TXA/sub 2/); and a third pathway(s). Aggregation of rabbit platelets in citrated platelet-rich plasma (PRP) or washed suspensions to ADP (0.5-10 ..mu..M) was not affected by ethanol, at concentrations up to 5 mg/ml (lethal). Primary ADP-induced (5 ..mu..M) aggregation of human platelets in PRP was also unaffected by ethanol, but secondary aggregation and release of /sup 14/C-serotonin, due to TXA/sub 2/ formation, was inhibited by ethanol (2 and 4 mg/ml). Since arachidonate (AA)-induced (25-250 ..mu..M) aggregation and release by washed rabbit platelets was unaltered by ethanol, it may inhibit mobilization of AA from platelet membrane phospholipids. Ethanol (2-4 mg/ml) inhibited rabbit platelet aggregation and release to low concentrations of thrombin (< 10 mU/ml) or collagen, and also inhibited aggregation and release of aspirin-treated (500 ..mu.. M) rabbit platelets (that cannot form TXA/sub 2/) to low concentrations of thrombin (< 10 mU/ml). Thus, ethanol does not inhibit the mobilization of AA, and partially inhibits the third pathway(s) of platelet aggregation.

  11. Hepatic transformation of prostaglandin D2 to a new prostanoid, 9 alpha,11 beta-prostaglandin F2, that inhibits platelet aggregation and constricts blood vessels

    Energy Technology Data Exchange (ETDEWEB)

    Pugliese, G.; Spokas, E.G.; Marcinkiewicz, E.; Wong, P.Y.

    1985-11-25

    The metabolic transformation of tritium-labeled prostaglandin D2 ((TH)PGD2) was investigated in the isolated Tyrode's-perfused rabbit liver. One major product was isolated and identified in the perfusate as a new prostanoid. The structure of this metabolite was further confirmed by gas chromatography-mass spectrometry and chemical methods to be 9 alpha,11 beta,15-L-trihydroxyprosta-5-cis, 13-trans-dienoic acid, namely (9 alpha,11 beta-PGF2). This new prostanoid was found to be an inhibitor of platelet aggregation and to cause constriction of canine coronary artery strips. These results suggested that on passage through the hepatic circulation exogenous PGD2 is converted to 9 alpha,11 beta-PGF2, the latter having a biological profile which differs from that of PGD2 and PGF2 alpha.

  12. CYP2C19*17 increases clopidogrel-mediated platelet inhibition but does not alter the pharmacokinetics of the active metabolite of clopidogrel

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Steen; Nielsen, Flemming; Stage, Tore Bjerregaard

    2014-01-01

    The aim of the present study was to determine the impact of CYP2C19*17 on the pharmacokinetics and pharmacodynamics of the active metabolite of clopidogrel and the pharmacokinetics of proguanil. Thus, we conducted an open-label two-phase cross-over study in 31 healthy male volunteers (11 CYP2C19......*1/*1, 11 CYP2C19*1/*17 and nine CYP2C19*17/*17). In Phase A, the pharmacokinetics of the derivatized active metabolite of clopidogrel (CAMD) and platelet function were determined after administration of a single oral dose of 600 mg clopidogrel (Plavix; Sanofi-Avensis, Horsholm, Denmark). In Phase B...... or higher exposure to the active metabolite after a single oral administration of 600 mg clopidogrel....

  13. Bleeding complications with the P2Y12 receptor antagonists clopidogrel and ticagrelor in the PLATelet inhibition and patient Outcomes (PLATO) trial.

    Science.gov (United States)

    Becker, Richard C; Bassand, Jean Pierre; Budaj, Andrzej; Wojdyla, Daniel M; James, Stefan K; Cornel, Jan H; French, John; Held, Claes; Horrow, Jay; Husted, Steen; Lopez-Sendon, Jose; Lassila, Riitta; Mahaffey, Kenneth W; Storey, Robert F; Harrington, Robert A; Wallentin, Lars

    2011-12-01

    AIMS More intense platelet-directed therapy for acute coronary syndrome (ACS) may increase bleeding risk. The aim of the current analysis was to determine the rate, clinical impact, and predictors of major and fatal bleeding complications in the PLATO study. METHODS AND RESULTS PLATO was a randomized, double-blind, active control international, phase 3 clinical trial in patients with acute ST elevation and non-ST-segment elevation ACS. A total of 18 624 patients were randomized to either ticagrelor, a non-thienopyridine, reversibly binding platelet P2Y(12) receptor antagonist, or clopidogrel in addition to aspirin. Patients randomized to ticagrelor and clopidogrel had similar rates of PLATO major bleeding (11.6 vs. 11.2%; P = 0.43), TIMI major bleeding (7.9 vs. 7.7%, P = 0.56) and GUSTO severe bleeding (2.9 vs. 3.1%, P = 0.22). Procedure-related bleeding rates were also similar. Non-CABG major bleeding (4.5 vs. 3.8%, P = 0.02) and non-procedure-related major bleeding (3.1 vs. 2.3%, P = 0.05) were more common in ticagrelor-treated patients, primarily after 30 days on treatment. Fatal bleeding and transfusion rates did not differ between groups. There were no significant interactions for major bleeding or combined minor plus major bleeding between treatment groups and age ≥75 years, weight 325 mg on the day of randomization, pre-randomization clopidogrel administration, or clopidogrel loading dose. CONCLUSION Ticagrelor compared with clopidogrel was associated with similar total major bleeding but increased non-CABG and non-procedure-related major bleeding, primarily after 30 days on study drug treatment. Fatal bleeding was low and did not differ between groups.

  14. Platelet Factor 4 Binds to Vascular Proteoglycans and Controls Both Growth Factor Activities and Platelet Activation.

    Science.gov (United States)

    Lord, Megan S; Cheng, Bill; Farrugia, Brooke L; McCarthy, Simon; Whitelock, John M

    2017-03-10

    Platelet factor 4 (PF4) is produced by platelets with roles in both inflammation and wound healing. PF4 is stored in platelet α-granules bound to the glycosaminoglycan (GAG) chains of serglycin. This study revealed that platelet serglycin is decorated with chondroitin/dermatan sulfate and that PF4 binds to these GAG chains. Additionally, PF4 had a higher affinity for endothelial-derived perlecan heparan sulfate chains than serglycin GAG chains. The binding of PF4 to perlecan was found to inhibit both FGF2 signaling and platelet activation. This study revealed additional insight into the ways in which PF4 interacts with components of the vasculature to modulate cellular events. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Platelet recruitment to venous stent thrombi.

    Science.gov (United States)

    McBane, Robert D; Karnicki, Krzysztof; Wysokinski, Waldemar E

    2013-11-01

    Thrombosis following venous stent placement is a morbid clinical outcome. Whether to target platelets or coagulation factors for venous stent thromboprophylaxis remains unclear. We sought to determine whether integrin α(IIb)β3 antagonism with lamifiban would inhibit platelet recruitment to venous stent thrombosis. Anti-thrombotic efficacy was compared between venous and arterial circulations. Pigs received either lamifiban (0.2 mg/kg bolus plus 0.2 mg/kg/h infusion; n = 6) or saline (n = 12). Carotid arteries were crush injured and then harvested 30 min later to provide an assessment of antithrombotic efficacy in the arterial circulation. Iliac venous stents were then deployed and thrombi allowed to propagate for 2 h before harvesting. Platelet deposition was measured by scintillation detection of autologous (111)In-platelets. Venous thrombi were quantified by weight and compared to platelet, Von Willebrand factor (VWF) and fibrinogen content. Arterial platelet deposition (×10(6)/cm(2)) was reduced >80% by lamifiban (398 ± 437) compared to controls (1,540 ± 883; p thrombi occurs in part through the integrin α(IIb)β3 receptor. Unlike arterial thrombosis, inhibition of this receptor is insufficient to prevent venous stent thrombosis.

  16. Platelet Count and Plateletcrit

    African Journals Online (AJOL)

    Aim: To determine whether platelet count, plateletcrit (PCT), mean platelet volume (MPV) and platelet distribution width. (PDW) and their ratios can predict mortality in hospitalised children. Methods: Children who died during hospital stay were the cases. Controls were age matched children admitted contempora- neously.

  17. Anti-platelet Therapy Resistance – Concept, Mechanisms and Platelet Function Tests in Intensive Care Facilities

    Directory of Open Access Journals (Sweden)

    Mărginean Alina

    2016-01-01

    Full Text Available It is well known that critically ill patients require special attention and additional consideration during their treatment and management. The multiple systems and organ dysfunctions, typical of the critical patient, often results in different patterns of enteral absorption in these patients. Anti-platelet drugs are the cornerstone in treating patients with coronary and cerebrovascular disease. Dual anti-platelet therapy with aspirin and clopidogrel is the treatment of choice in patients undergoing elective percutaneous coronary interventions and is still widely used in patients with acute coronary syndromes. However, despite the use of dual anti-platelet therapy, some patients continue to experience cardiovascular ischemic events. Recurrence of ischemic events is partly attributed to the fact that some patients have poor inhibition of platelet reactivity despite treatment. These patients are considered low- or nonresponders to therapy. The underlying mechanisms leading to resistance are not yet fully elucidated and are probably multifactorial, cellular, genetic and clinical factors being implicated. Several methods have been developed to asses platelet function and can be used to identify patients with persistent platelet reactivity, which have an increased risk of thrombosis. In this paper, the concept of anti-platelet therapy resistance, the underlying mechanisms and the methods used to identify patients with low responsiveness to anti-platelet therapy will be highlighted with a focus on aspirin and clopidogrel therapy and addressing especially critically ill patients.

  18. 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.

  19. miR-503 inhibits platelet-derived growth factor-induced human aortic vascular smooth muscle cell proliferation and migration through targeting the insulin receptor.

    Science.gov (United States)

    Bi, Rui; Ding, Fangbao; He, Yi; Jiang, Lianyong; Jiang, Zhaolei; Mei, Ju; Liu, Hao

    2016-12-01

    Abnormal proliferation and migration of vascular smooth muscle cells (VSMC) is a common feature of disease progression in atherosclerosis. Here, we investigated the potential role of miR-503 in platelet-derived growth factor (PDGF)-induced proliferation and migration of human aortic smooth muscle cells and the underlying mechanisms of action. miR-503 expression was significantly downregulated in a dose- and time-dependent manner following PDGF treatment. Introduction of miR-503 mimics into cultured SMCs significantly attenuated cell proliferation and migration induced by PDGF. Bioinformatics analyses revealed that the insulin receptor (INSR) is a target candidate of miR-503. miR-503 suppressed luciferase activity driven by a vector containing the 3'-untranslated region of INSR in a sequence-specific manner. Downregulation of INSR appeared critical for miR-503-mediated inhibitory effects on PDGF-induced cell proliferation and migration in human aortic SMCs. Based on the collective data, we suggest a novel role of miR-503 as a regulator of VSMC proliferation and migration through modulating INSR. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Effect of tomato industrial processing (different hybrids, paste, and pomace) on inhibition of platelet function in vitro, ex vivo, and in vivo.

    Science.gov (United States)

    Rodríguez-Azúa, Rosio; Treuer, Adriana; Moore-Carrasco, Rodrigo; Cortacáns, Daniel; Gutiérrez, Margarita; Astudillo, Luis; Fuentes, Eduardo; Palomo, Iván

    2014-04-01

    Cardiovascular disease (CVD) is the leading cause of death worldwide. Healthy eating is among its safeguards, especially the daily intake of fruits and vegetables. In this context it has been shown that tomato (Solanum lycopersicum) presents antiplatelet activity. In the present study, we evaluated in vitro antiplatelet activity of fresh hybrid tomato process (nine hybrids: Apt 410, H 9888, Bos 8066, Sun 6366, AB3, HMX 7883, H 9665, H 7709, and H 9997), paste and its by-product of industrial processes (pomace). We assessed antiplatelet activity ex vivo and bleeding time in rats that ingested 0.1 and 1.0 g/kg of pomace each day. In studies in vitro, no significant differences in antiplatelet activity was observed in fresh tomato hybrids. Furthermore, the agro-industrial process did not affect the antiplatelet activity of paste and pomace. Likewise, pomace intake of 1.0 g/kg per day prolonged bleeding time and reduced ex vivo platelet aggregation in rats. The data obtained indicate that tomato has one or more compounds that caused antiplatelet activity. Regular consumption of tomato and its industrial derivatives could be part of a CVD prevention regimen.

  1. Rhesus monkey platelets

    Energy Technology Data Exchange (ETDEWEB)

    Harbury, C.B.

    1986-03-01

    The purpose of this abstract is to describe the adenine nucleotide metabolism of Rhesus monkey platelets. Nucleotides are labelled with /sup 14/C-adenine and extracted with EDTA-ethanol (EE) and perchlorate (P). Total platelet ATP and ADP (TATP, TADP) is measured in the Holmsen Luciferase assay, and expressed in nanomoles/10/sup 8/ platelets. TR=TATP/TADP. Human platelets release 70% of their TADP, with a ratio of released ATP/ADP of 0.7. Rhesus platelets release 82% of their TADP, with a ratio of released ATP/ADP of 0.33. Thus, monkey platelets contain more ADP than human platelets. Thin layer chromatography of EE gives a metabolic ratio of 11 in human platelets and 10.5 in monkey platelets. Perchlorate extracts metabolic and actin bound ADP. The human and monkey platelets ratios were 5, indicating they contain the same proportion of actin. Thus, the extra ADP contained in monkey platelets is located in the secretory granules.

  2. Ticagrelor versus clopidogrel in patients with ST-elevation acute coronary syndromes intended for reperfusion with primary percutaneous coronary intervention: A Platelet Inhibition and Patient Outcomes (PLATO) trial subgroup analysis.

    Science.gov (United States)

    Steg, Philippe Gabriel; James, Stefan; Harrington, Robert A; Ardissino, Diego; Becker, Richard C; Cannon, Christopher P; Emanuelsson, Håkan; Finkelstein, Ariel; Husted, Steen; Katus, Hugo; Kilhamn, Jan; Olofsson, Sylvia; Storey, Robert F; Weaver, W Douglas; Wallentin, Lars

    2010-11-23

    Aspirin and clopidogrel are recommended for patients with acute coronary syndromes (ACS) or undergoing coronary stenting. Ticagrelor, a reversible oral P2Y12-receptor antagonist, provides faster, greater, and more consistent platelet inhibition than clopidogrel and may be useful for patients with acute ST-segment elevation (STE) ACS and planned primary percutaneous coronary intervention. Platelet Inhibition and Patient Outcomes (PLATO), a randomized, double-blind trial, compared ticagrelor with clopidogrel for the prevention of vascular events in 18 624 ACS patients. This report concerns the 7544 ACS patients with STE or left bundle-branch block allocated to either ticagrelor 180-mg loading dose followed by 90 mg twice daily or clopidogrel 300-mg loading dose (with provision for 300 mg clopidogrel at percutaneous coronary intervention) followed by 75 mg daily for 6 to 12 months. The reduction of the primary end point (myocardial infarction, stroke, or cardiovascular death) with ticagrelor versus clopidogrel (10.8% versus 9.4%; hazard ratio [HR], 0.87; 95% confidence interval, 0.75 to 1.01; P=0.07) was consistent with the overall PLATO results. There was no interaction between presentation with STE/left bundle-branch block and randomized treatment (interaction P=0.29). Ticagrelor reduced several secondary end points, including myocardial infarction alone (HR, 0.80; P=0.03), total mortality (HR, 0.82; P=0.05), and definite stent thrombosis (HR, 0.66; P=0.03). The risk of stroke, low in both groups, was higher with ticagrelor (1.7% versus 1.0%; HR,1.63; 95% confidence interval, 1.07 to 2.48; P=0.02). Ticagrelor did not affect major bleeding (HR, 0.98; P=0.76). In patients with STE-ACS and planned primary percutaneous coronary intervention, the effects of ticagrelor were consistent with those observed in the overall PLATO trial. URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00391872.

  3. The incidence of bradyarrhythmias and clinical bradyarrhythmic events in patients with acute coronary syndromes treated with ticagrelor or clopidogrel in the PLATO (Platelet Inhibition and Patient Outcomes) trial: results of the continuous electrocardiographic assessment substudy.

    Science.gov (United States)

    Scirica, Benjamin M; Cannon, Christopher P; Emanuelsson, Håkan; Michelson, Eric L; Harrington, Robert A; Husted, Steen; James, Stefan; Katus, Hugo; Pais, Prem; Raev, Dimitar; Spinar, Jindrich; Steg, Ph Gabriel; Storey, Robert F; Wallentin, Lars

    2011-05-10

    The aim of this study was to determine whether ticagrelor increased the risk of ventricular pauses compared with clopidogrel and whether these pauses were associated with any clinical bradycardic events in patients presenting with acute coronary syndromes. Ticagrelor, an oral reversibly binding P2Y(12) inhibitor, provides more potent and consistent inhibition of platelet aggregation than clopidogrel but in a phase II study was associated with increased risk for ventricular pauses. A prospective continuous electrocardiographic (cECG) assessment was therefore performed within the PLATO (Platelet Inhibition and Patient Outcomes) study comparing ticagrelor and clopidogrel in patients hospitalized with acute coronary syndromes. Patients in the cECG assessment had planned 7-day cECG recording initiated at the time of randomization (week 1), which was within 24 h of symptom onset, and then repeated at 1 month after randomization during the convalescent phase. The principal safety endpoint was the incidence of ventricular pauses lasting at least 3 s. Investigators also reported symptomatic bradycardic adverse events during the entire study duration (median 277 days). A total of 2,908 patients were included in the cECG assessment, of whom 2,866 (98.5%) had week 1 recordings, 1,991 (68.4%) had 1-month recordings, and 1,949 (67.0%) had both. During the first week after randomization, ventricular pauses ≥3 s occurred more frequently in patients receiving ticagrelor than clopidogrel (84 [5.8%] vs. 51 [3.6%]; relative risk: 1.61; p = 0.006). At 1 month, pauses ≥3 s occurred overall less frequently and were similar between treatments (2.1% vs. 1.7%). Most were ventricular pauses, and the greatest excess associated with ticagrelor were asymptomatic, sinoatrial nodal in origin (66%), and nocturnal. There were no differences between ticagrelor and clopidogrel in the incidence of clinically reported bradycardic adverse events, including syncope, pacemaker placement, and cardiac

  4. Platelets: developmental biology, physiology, and translatable platforms for preclinical investigation and drug development.

    Science.gov (United States)

    Kleiman, Neal S; Freedman, Jane E; Tracy, Paula B; Furie, Barbara C; Bray, Paul F; Rao, Sunil V; Phillips, David R; Storey, Robert F; Rusconi, Christopher P; French, Patricia A; Steinhubl, Steven R; Becker, Richard C

    2008-06-01

    This paper, developed from the proceedings of the 2007 Platelet Colloquium, considers emerging constructs in platelet biology, preclinical models of thrombosis, and their potential application to the development of platelet-directed pharmacotherapies. Discussed first is the developmental biology of platelets, including megakaryocyte maturation, and the role of apoptotic and growth factors and other proteins in thrombopoiesis. A brief overview of current methods and observations from platelet proteomic analyses is also presented, illustrating the complex interplay of genes, gene expression, protein expression, and protein modification in various atherothrombotic phenotypes. The factor Xa-platelet interface is used as a working model for discussion of anticoagulants as platelet antagonists, highlighting the importance of receptor expression, substrate binding kinetics, platelet subpopulations, and cofactors in thrombosis. Finally, we discuss the use of emerging technologies--such as intravital microscopy and ex vivo perfusion chambers--as translatable platforms for investigating the role of platelets and their pharmacologic inhibition in human health and disease.

  5. Dual roles for hepatic lectin receptors in the clearance of chilled platelets

    DEFF Research Database (Denmark)

    Rumjantseva, Viktoria; Grewal, Prabhjit K; Wandall, Hans H

    2009-01-01

    -GlcNAc moieties by galactosylation prevents clearance of short-term-cooled platelets, this strategy is ineffective after prolonged refrigeration. We report here that prolonged refrigeration increased the density and concentration of exposed galactose residues on platelets such that hepatocytes, through Ashwell-Morell...... transfusion. Inhibition of chilled platelet clearance by both beta(2) integrin and Ashwell-Morell receptors may afford a potentially simple method for storing platelets in the cold....

  6. Role of Siglec-7 in apoptosis in human platelets.

    Directory of Open Access Journals (Sweden)

    Kim Anh Nguyen

    Full Text Available Platelets participate in tissue repair and innate immune responses. Sialic acid-binding immunoglobulin-like lectins (Siglecs are well-characterized I-type lectins, which control apoptosis.We characterized the expression of Siglec-7 in human platelets isolated from healthy volunteers using flow cytometry and confocal microscopy. Siglec-7 is primarily expressed on α granular membranes and colocalized with CD62P. Siglec-7 expression was increased upon platelet activation and correlated closely with CD62P expression. Cross-linking Siglec-7 with its ligand, ganglioside, resulted in platelet apoptosis without any significant effects on activation, aggregation, cell morphology by electron microscopy analysis or secretion. We show that ganglioside triggered four key pathways leading to apoptosis in human platelets: (i mitochondrial inner transmembrane potential (ΔΨm depolarization; (ii elevated expression of pro-apoptotic Bax and Bak proteins with reduced expression of anti-apoptotic Bcl-2 protein; (iii phosphatidylserine exposure and (iv, microparticle formation. Inhibition of NAPDH oxidase, PI3K, or PKC rescued platelets from apoptosis induced by Siglec-7 recruitment, suggesting that the platelet receptors P2Y1 and GPIIbIIIa are essential for ganglioside-induced platelet apoptosis.The present work characterizes the role of Siglec-7 and platelet receptors in regulating apoptosis and death. Because some platelet pathology involves apoptosis (idiopathic thrombocytopenic purpura and possibly storage lesions, Siglec-7 might be a molecular target for therapeutic intervention/prevention.

  7. Autologous Platelet-Rich Plasma Preparations: Influence of Nonsteroidal Anti-inflammatory Drugs on Platelet Function.

    Science.gov (United States)

    Schippinger, Gert; Prüller, Florian; Divjak, Manuela; Mahla, Elisabeth; Fankhauser, Florian; Rackemann, Steve; Raggam, Reinhard Bernd

    2015-06-01

    Autologous platelet-rich plasma (PRP) has been widely used for the treatment of sports injuries. It has been associated with improved healing and regeneration of soft tissues in elite athletes. Athletes are commonly receiving nonsteroidal anti-inflammatory drugs (NSAIDs). As yet, the effect of these drugs on platelet function in PRP formulations has not been taken into consideration. The function of platelets in PRP produced under the influence of NSAIDs is inhibited and may lessen a possible healing effect on the site of injury. Controlled laboratory study. PRP was collected from patients receiving NSAIDs after elective orthopaedic surgery, and platelet function was evaluated using light transmission aggregometry (LTA). Results were compared with those obtained from healthy volunteers without a history of NSAID intake during the previous 2 weeks. Two different systems for blood collection and PRP production (Arthrex ACP double-syringe system and standard 4.5-mL sodium citrate blood collection tubes) were used and compared regarding the quality of PRP that was produced. For both groups, the baseline platelet counts of whole blood and the platelet counts of PRP formulations were found to be in the normal range. Both collection systems for PRP produced comparable results without significant differences between the groups. Platelet function testing with LTA revealed significantly impaired platelet aggregation in both PRP preparations, obtained from patients taking NSAIDs, irrespective of the type of NSAID (P < .001). All subjects from the control group showed normal platelet aggregation patterns when tested with LTA. Autologous PRP produced from subjects after NSAID medication shows significantly impaired platelet function and may result in lower quality regarding the content of bioactive compounds. If required, the administration of NSAIDs should be performed after blood collection for preparation of autologous PRP; otherwise, the therapeutic effect may be limited.

  8. Aerobic exercise training lowers platelet reactivity and improves platelet sensitivity to prostacyclin in pre- and postmenopausal women

    DEFF Research Database (Denmark)

    Lundberg Slingsby, Martina Helena; Nyberg, Michael Permin; Egelund, Jon

    2017-01-01

    .7 (52.5-55.0) years old, participated in an intervention study: 3-month high-intensity supervised aerobic spinning-cycle training (1hr, x3/week). Basal platelet reactivity was analyzed in platelet rich plasma from venous blood as agonist-induced %aggregation. In a subgroup of 13 pre- and 14...... exercise in late pre- and recent postmenopausal women by testing basal platelet reactivity and platelet sensitivity to prostacyclin and nitric oxide. METHODS: 25 sedentary, but healthy, late premenopausal and 24 matched recently postmenopausal women, mean (95% confidence interval) 49.1 (48.2-49.9) and 53......-68) versus premenopausal women; 45% (35-55). Exercise training reduced basal platelet reactivity to collagen(1μg/ml) in the premenopausal women only; from 63% (55-71%) to 51% (41-62%). After the training intervention, platelet aggregation was more inhibited by the arterial prostacyclin infusion and the acute...

  9. Platelet transfusion does not improve outcomes in patients with brain injury on antiplatelet therapy.

    Science.gov (United States)

    Holzmacher, Jeremy L; Reynolds, Cassandra; Patel, Mayur; Maluso, Patrick; Holland, Seth; Gamsky, Nathaniel; Moore, Henry; Acquista, Elizabeth; Carrick, Matthew; Amdur, Richard; Hancock, Heather; Metzler, Michael; Dunn, Julie; Sarani, Babak

    2018-01-01

    Platelet dysfunction following traumatic brain injury (TBI) is associated with worse outcomes. The efficacy of platelet transfusion to reverse antiplatelet medication (APM) remains unknown. Thrombelastography platelet mapping (TEG-PM) assesses platelet function. We hypothesize that platelet transfusion can reverse the effects of APM but does not improve outcomes following TBI. An observational study at six US trauma centres was performed. Adult patients on APM with CT evident TBI after blunt injury were enrolled. Demographics, brain CT and TEG-PM results before/after platelet transfusion, length of stay (LOS), and injury severity score (ISS) were abstracted. Sixty six patients were enrolled (89% aspirin, 50% clopidogrel, 23% dual APM) with 23 patients undergoing platelet transfusion. Transfused patients had significantly higher ISS and admission CT scores. Platelet transfusion significantly reduced platelet inhibition due to aspirin (76.0 ± 30.2% to 52.7 ± 31.5%, p clopidogrel-associated inhibition (p = 0.07). Platelet transfusion was associated with longer length of stay (7.8 vs. 3.5 days, p < 0.01), but there were no differences in mortality. Platelet transfusion significantly decreases platelet inhibition due to aspirin but is not associated with change in outcomes in patients on APM following TBI.

  10. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Platelet proteins cause basophil histamine release through an immunoglobulin-dependent mechanism.

    Science.gov (United States)

    Lee, Donna Dong-Young; Muskaj, Igla; Savage, William

    2017-07-01

    A general understanding of allergic transfusion reaction mechanisms remains elusive. Multiple mechanisms have been proposed, but none have been compared experimentally. We used histamine release (HR) from healthy human donor basophils to model allergic transfusion reactions. Platelet component supernatant (plasma), platelet lysate, and manipulated platelet lysates (dialyzed, delipidated, trypsinized, mild heat-inactivated, and ultracentrifuged) were used to characterize allergic stimuli. Immunoglobulin-dependent mechanisms were investigated through cell surface immunoglobulin depletion and ibrutinib signaling inhibition. HR induced by platelet mitochondria was compared with HR by platelet lysate with or without DNase treatment. Robust, dose-responsive HR to platelet lysate was observed in two of eight nulliparous, never-transfused, healthy donors. No HR was observed with plasma. Among manipulated platelet lysates, only trypsin treatment significantly reduced HR (39% reduction; p = 0.008). HR in response to platelet lysate significantly decreased with either cell surface immunoglobulin depletion or ibrutinib pretreatment. Platelet mitochondria induced minimal basophil HR, and DNase treatment did not inhibit platelet lysate-induced HR. Type I immediate hypersensitivity to platelet proteins may be an allergic transfusion reaction mechanism. Prior sensitization to human proteins is not required for basophil responses to platelet proteins. Further study into the relative contributions of hypersensitivity to platelet versus plasma proteins in transfusion is warranted. © 2017 AABB.

  12. Comparison of ticagrelor, the first reversible oral P2Y(12) receptor antagonist, with clopidogrel in patients with acute coronary syndromes: Rationale, design, and baseline characteristics of the PLATelet inhibition and patient Outcomes (PLATO) trial.

    Science.gov (United States)

    James, Stefan; Akerblom, Axel; Cannon, Christopher P; Emanuelsson, Håkan; Husted, Steen; Katus, Hugo; Skene, Allan; Steg, Philippe Gabriel; Storey, Robert F; Harrington, Robert; Becker, Richard; Wallentin, Lars

    2009-04-01

    Antiplatelet therapy is essential treatment for acute coronary syndromes (ACS). Current therapies, however, have important limitations affecting their clinical success. Ticagrelor, the first reversible oral P2Y(12) receptor antagonist, provides faster, greater, and more consistent adenosine diphosphate-receptor inhibition than clopidogrel. The phase III PLATelet inhibition and patient Outcomes (PLATO) trial is designed to test the hypothesis that ticagrelor compared with clopidogrel will result in a lower risk of recurrent thrombotic events in a broad patient population with ACS. PLATO is an international, randomized, double-blind, event-driven trial involving >18,000 patients hospitalized for ST-elevation ACS with scheduled primary percutaneous coronary intervention or for non-ST-elevation ACS. After loading doses of ticagrelor 180 mg or clopidogrel 300 mg in a double-blind, double-dummy fashion (with provision for additional 300 mg clopidogrel at percutaneous coronary intervention), patients will receive ticagrelor 90 mg twice daily or clopidogrel 75 mg once daily for 6 to 12 months on top of acetylsalicylic acid. The primary efficacy end point is time to first occurrence of death from vascular causes, myocardial infarction, or stroke. The primary safety variable is PLATO-defined major bleeding. An extensive substudy program will explore the pathophysiology of ACS, indicators of prognosis and response to treatment, mechanisms of effect and safety of the study medications, health economics, and quality of life. The PLATO study will provide a pivotal comparison of the efficacy and safety of ticagrelor with those of clopidogrel in ACS patients, together with extensive information on treatment outcomes in different subsets of ACS in a broad patient population.

  13. Sulforaphane inhibits platelet-derived growth factor-induced vascular smooth muscle cell proliferation by targeting mTOR/p70S6kinase signaling independent of Nrf2 activation.

    Science.gov (United States)

    Shawky, Noha M; Segar, Lakshman

    2017-05-01

    Activation of nuclear factor erythroid 2-related factor 2 (Nrf2, a transcription factor) and/or inhibition of mammalian target of rapamycin (mTOR) are implicated in the suppression of vascular smooth muscle cell (VSMC) proliferation. The present study has examined the likely regulatory effects of sulforaphane (SFN, an antioxidant) on Nrf2 activation and platelet-derived growth factor (PDGF)-induced mTOR signaling in VSMCs. Using human aortic VSMCs, nuclear extraction and siRNA-mediated downregulation studies were performed to determine the role of Nrf2 on SFN regulation of PDGF-induced proliferative signaling. Immunoprecipitation and/or immunoblot studies were carried out to determine how SFN regulates PDGF-induced mTOR/p70S6K/S6 versus ERK and Akt signaling. Immunohistochemical analysis was performed to determine SFN regulation of S6 phosphorylation in the injured mouse femoral artery. SFN (5μM) inhibits PDGF-induced activation of mTOR without affecting mTOR association with raptor in VSMCs. While SFN inhibits PDGF-induced phosphorylation of p70S6K and 4E-BP1 (downstream targets of mTOR), it does not affect ERK or Akt phosphorylation. In addition, SFN diminishes exaggerated phosphorylation of S6 ribosomal protein (a downstream target of p70S6K) in VSMCs in vitro and in the neointimal layer of injured artery in vivo. Although SFN promotes Nrf2 accumulation to upregulate cytoprotective genes (e.g., heme oxygenase-1 and thioredoxin-1), downregulation of endogenous Nrf2 by target-specific siRNA reveals an Nrf2-independent effect for SFN-mediated inhibition of mTOR/p70S6K/S6 signaling and suppression of VSMC proliferation. Strategies that utilize local delivery of SFN at the lesion site may limit restenosis after angioplasty by targeting mTOR/p70S6K/S6 axis in VSMCs independent of Nrf2 activation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Inhibitory effect of hericenone B from Hericium erinaceus on collagen-induced platelet aggregation.

    Science.gov (United States)

    Mori, Koichiro; Kikuchi, Haruhisa; Obara, Yutaro; Iwashita, Masaya; Azumi, Yoshihito; Kinugasa, Satomi; Inatomi, Satoshi; Oshima, Yoshiteru; Nakahata, Norimichi

    2010-12-01

    Platelet aggregation in the blood vessel causes thrombosis. Therefore, inhibitors of platelet aggregation promise to be preventive or therapeutic agents of various vascular diseases, including myocardial infarction and stroke. In the present study, we found that hericenone B had a strong anti-platelet activity and it might be a novel compound for antithrombotic therapy possessing a novel mechanism. Prior to this study, we examined anti-platelet aggregation activity of ethanol extracts of several species of mushrooms, and found that extract of Hericium erinaceus potently inhibited platelet aggregation induced by collagen. Therefore, we first fractionated the ethanol extract of H. erinaceus to identify the active substances. The anti-platelet activity of each fraction was determined using washed rabbit platelets. As a result, an active component was isolated and identified as hericenone B. Hericenone B selectively inhibited collagen-induced platelet aggregation, but it did not suppress the aggregation induced by U46619 (TXA₂ analogue), ADP, thrombin, or adrenaline. Furthermore, hericenone B did not inhibit arachidonic acid- or convulxin (GPVI agonist)-induced platelet aggregation. Therefore, hericenone B was considered to block collagen signaling from integrin α2/β1 to arachidonic acid release. Moreover, we found that collagen-induced aggregation was inhibited by hericenone B in human platelets, similar to in rabbit platelets. Copyright © 2010 Elsevier GmbH. All rights reserved.

  15. Platelet alloimmunization after transfusion

    DEFF Research Database (Denmark)

    Taaning, E; Simonsen, A C; Hjelms, E

    1997-01-01

    BACKGROUND AND OBJECTIVES: The frequency of platelet-specific antibodies after one series of blood transfusions has not been reported, and in multiply transfused patients is controversial. MATERIALS AND METHODS: We studied the frequency of alloimmunization against platelet antigens in 117 patients...... who received a single series of blood transfusions. They received mostly saline-adenine-glucose+mannitol red blood cell components (poor in leukocytes and platelets) in connection with cardiac surgery. Platelet-specific antibodies were detected with the platelet ELISA and the monoclonal...... immunization. CONCLUSION: There was a low incidence of platelet-specific antibodies after one series of blood transfusions in this group of patients. This is similar to the results of some previous studies in multiply transfused patients, but not with those of others who found a higher incidence....

  16. Serotonergic mechanisms enhance platelet-mediated thrombogenicity.

    Science.gov (United States)

    Galan, Ana M; Lopez-Vilchez, Irene; Diaz-Ricart, Maribel; Navalon, Fulgencio; Gomez, Esther; Gasto, Cristobal; Escolar, Gines

    2009-09-01

    Although it is generally acknowledged that serotonin (5-HT) is a weak agonist for human platelets, recent information suggests an association between serotonergic mechanisms and cardiovascular risk. We investigated the action of 5-HT on adhesive, cohesive and procoagulant properties of human platelets. Impact of 5-HT on whole blood coagulation and thrombin generation was measured by modified thromboelastometry (TEM) and specific fluorogenic assays. We evaluated the effects of 5-HT on thrombus formation in an in-vitro model of thrombosis using human flowing blood. In platelet-rich plasma (PRP), 5-HT favoured the expression of CD62-P, and procoagulant molecules on platelet membranes. These effects were potentiated in the presence of Ca(++) and/or ADP. Incubation with 5-HT accelerated clotting times and augmented clot strength in whole blood TEM, and enhanced thrombin generation in PRP. In perfusion studies, 5-HT significantly increased fibrin deposition at low shear (300s(-1)) and enhanced platelet thrombus formation on the damaged vascular surface at high shear (1,200s(-1)). Selective inhibition of serotonin reuptake (SSRI) attenuated effects of 5-HT on platelet activation and downregulated the prothrombotic tendencies observed in the previous experimental conditions. In general, reductions of thrombogenic patterns observed with SSRI were more evident under shear conditions (aggregation and perfusion systems) and less evident under steady conditions (TEM and thrombin generation assays). In conclusion, 5-HT is not a weak agonist for human platelets; instead it accentuates platelet activation, potentiates procoagulant responses on human blood and increases thrombogenesis on damaged vascular surfaces. The remarkable antithrombotic actions achieved through SSRI deserve further mechanistic and clinical investigations.

  17. RhoA signaling through platelet P2Y₁ receptor controls leukocyte recruitment in allergic mice.

    Science.gov (United States)

    Amison, Richard T; Momi, Stefania; Morris, Abigail; Manni, Giorgia; Keir, Sandra; Gresele, Paolo; Page, Clive P; Pitchford, Simon C

    2015-02-01

    Clinical studies reveal platelet activation in patients with asthma, allergic rhinitis, and eczema. This is distinct from platelet aggregation, which is critical for the maintenance of hemostasis and in which a role for platelet purinergic receptors is well documented. However, purines are also essential for inflammatory cell trafficking in animal models of allergic lung inflammation, which are known to be platelet dependent, yet the role of purines in the platelet activation accompanying inflammation is unknown. We investigated whether the involvement of purine activation of platelets during allergic inflammation is distinct from purine involvement in platelet aggregation. BALB/c mice were sensitized to ovalbumin and subsequent airway ovalbumin challenge. Bronchoalveolar lavage fluid was analyzed for inflammatory cells, and blood samples were assessed for platelet activation. The role of platelet purinergic receptors and associated signaling mechanisms (RhoA) were assessed. P2Y₁, but not P2Y₁₂ or P2X₁, antagonism inhibited pulmonary leukocyte recruitment. The formation of platelet-leukocyte complexes in vivo and platelet/P-selectin-dependent polymorphonuclear cell migration in vitro were exclusively platelet P2Y₁ receptor dependent. Furthermore, platelet P2Y₁ activation resulted in RhoA activity in vivo after allergen challenge, and RhoA signaling in platelets through P2Y₁ stimulation was required for platelet-dependent leukocyte chemotaxis in vitro. Leukocyte recruitment in thrombocytopenic mice remained suppressed after reinfusion of platelets pretreated with a P2Y₁ antagonist or a Rho-associated kinase 1 inhibitor, confirming the crucial role of platelet P2Y₁ receptor and subsequent activation of RhoA. RhoA signaling downstream of platelet P2Y₁, but not P2Y₁₂, represents a clear dichotomy in platelet activation during allergic inflammation versus hemostasis. Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by

  18. Mean platelet volume and mean platelet volume/platelet count ratio ...

    African Journals Online (AJOL)

    Mean platelet volume and mean platelet volume/platelet count ratio as a risk stratification tool in the assessment of severity of acute ischemic stroke. ... The mean platelet volume (MPV) is a laboratory marker associated with platelet function and activity. Increased MPV in thromboembolic disease is reflected as an important ...

  19. An antagonist of the platelet-activating factor receptor inhibits adherence of both nontypeable Haemophilus influenzae and Streptococcus pneumoniae to cultured human bronchial epithelial cells exposed to cigarette smoke

    Directory of Open Access Journals (Sweden)

    Shukla SD

    2016-07-01

    cells. In silico analyses identified a binding pocket for PAF/WEB-2086 in the predicted PAFr structure.Conclusion: WEB-2086 represents an innovative class of candidate drugs for inhibiting PAFr-dependent lung infections caused by the main bacterial drivers of smoking-related COPD. Keywords: airway epithelium, NTHi, pneumococci, WEB-2086, platelet-activating factor receptor, PAFr antagonist

  20. Measurement of platelet aggregation, independently of patient platelet count

    DEFF Research Database (Denmark)

    Vinholt, P J; Frederiksen, H; Hvas, A-M

    2017-01-01

    Essentials •Platelet function may influence bleeding risk in thrombocytopenia, but useful tests are needed. •A flow cytometric platelet aggregation test independent of the patient platelet count was made. •Platelet aggregation was reduced in thrombocytopenic patients with hematological cancer....... •High platelet aggregation ruled out bleeding tendency in thrombocytopenic patients. Summary Background Methods for testing platelet aggregation in thrombocytopenia are lacking. Objective To establish a flow-cytometric test of in vitro platelet aggregation independently of the patient's platelet count...

  1. Hydrogen peroxide lowers ATP levels in platelets without altering adenyalte energy charge and platelet function.

    Science.gov (United States)

    Holmsen, H; Robkin, L

    1977-03-10

    H2O2 irreversibly reduced metabolic platelet ATP levels with a corresponding accumulation of hypoxanthine. This process was enhanced by sodium azide or potassium cyanide and by increasing H2O2 concentrations. The adenylate energy charge was unaltered when less than two thirds of the metabolic ATP had disappeared but decreased markedly when more ATP disappeared. Platelet shape change, primary aggregation, dense granule and alpha-granule secretion were unaffected by H2O2-induced lowering of ATP provided that the adenylate energy charge did not fall by more than 5%; at greater adenylate energy charge reduction, platelet functions were inhibited. These results indicate that cell functions depend more on adenyalte energy charge than on the ATP level and expands the applicability of this view from bacterial systems to a mammalian cell, the human platelet.

  2. Surfactants reduce platelet-bubble and platelet-platelet binding induced by in vitro air embolism.

    Science.gov (United States)

    Eckmann, David M; Armstead, Stephen C; Mardini, Feras

    2005-12-01

    The effect of gas bubbles on platelet behavior is poorly characterized. The authors assessed platelet-bubble and platelet-platelet binding in platelet-rich plasma in the presence and absence of bubbles and three surface-active compounds. Platelet-rich plasma was prepared from blood drawn from 16 volunteers. Experimental groups were surfactant alone, sparging (microbubble embolization) alone, sparging with surfactant, and neither sparging nor surfactant. The surfactants were Pluronic F-127 (Molecular Probes, Eugene, OR), Perftoran (OJSC SPC Perftoran, Moscow, Russia), and Dow Corning Antifoam 1510US (Dow Corning, Midland, MI). Videomicroscopy images of specimens drawn through rectangular glass microcapillaries on an inverted microscope and Coulter counter measurements were used to assess platelet-bubble and platelet-platelet binding, respectively, in calcium-free and recalcified samples. Histamine-induced and adenosine diphosphate-induced platelet-platelet binding were measured in unsparged samples. Differences between groups were considered significant for P bubbles in sparged, surfactant-free samples. With sparging and surfactant, few platelets adhered to bubbles. Numbers of platelet singlets and multimers not adherent to bubbles were different (P surfactant. No significant platelet-platelet binding occurred in uncalcified, sparged samples, although 20-30 platelets adhered to bubbles. Without sparging, histamine and adenosine diphosphate provoked platelet-platelet binding with and without surfactants present. Sparging causes platelets to bind to air bubbles and each other. Surfactants added before sparging attenuate platelet-bubble and platelet-platelet binding. Surfactants may have a clinical role in attenuating gas embolism-induced platelet-bubble and platelet-platelet binding.

  3. Correlation between Platelet Gelsolin and Platelet Activation Level in Acute Myocardial Infarction Rats and Intervention Effect of Effective Components of Chuanxiong Rhizome and Red Peony Root

    Directory of Open Access Journals (Sweden)

    Yue Liu

    2013-01-01

    Full Text Available The biological role of platelet gelsolin in platelet activation of acute myocardial infarction is not defined. In order to provide a potential new antiplatelet target for Chinese medicine and to elucidate the contribution of Xiongshao capsule, the effective components of Chuanxiong rhizome and red peony root, in this study, we randomly allocated Sprague Dawley rats to left anterior descending coronary artery ligation or sham surgery and different drug prophylaxis as control. We found that gelsolin is highly expressed in platelet rich plasma and lowly expressed in platelet poor plasma, accompanied by the high platelet activation level in model rats; plasma actin filaments and mean fluorescence intensity (MFI of platelet calcium ion increased and plasma vitamin D binding protein decreased in model rats. Xiongshao capsule could inhibit the gelsolin expression in platelet rich plasma and ischemic heart tissue simultaneously and reduce the level of plasma F-actin and MFI of platelet calcium ion. Our study concludes that platelet gelsolin is an important contributor to platelet activation, and platelet gelsolin inhibition may form a novel target for antiplatelet therapy. Xiongshao capsule may be a promising Chinese medicine drug for antiplatelet and aspirin-like cardioprotection effect.

  4. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    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...

  5. 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.

  6. 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....

  7. Cystatin C- and creatinine-based estimates of renal function and their value for risk prediction in patients with acute coronary syndrome: results from the PLATelet Inhibition and Patient Outcomes (PLATO) study.

    Science.gov (United States)

    Åkerblom, Axel; Wallentin, Lars; Larsson, Anders; Siegbahn, Agneta; Becker, Richard C; Budaj, Andrzej; Himmelmann, Anders; Horrow, Jay; Husted, Steen; Storey, Robert F; Asenblad, Nils; James, Stefan K

    2013-09-01

    The estimated glomerular filtration rate (eGFR) independently predicts cardiovascular death or myocardial infarction (MI) and can be estimated by creatinine and cystatin C concentrations. We evaluated 2 different cystatin C assays, alone or combined with creatinine, in patients with acute coronary syndrome. We analyzed plasma cystatin C, measured with assays from Gentian and Roche, and serum creatinine in 16 279 patients from the PLATelet Inhibition and Patient Outcomes (PLATO) trial. We evaluated Pearson correlation and agreement (Bland-Altman) between methods, as well as prognostic value in relation to cardiovascular death or MI during 1 year of follow up by multivariable logistic regression analysis including clinical variables, biomarkers, c-statistics, and relative integrated discrimination improvement (IDI). Median cystatin C concentrations (interquartile intervals) were 0.83 (0.68-1.01) mg/L (Gentian) and 0.94 (0.80-1.14) mg/L (Roche). Overall correlation was 0.86 (95% CI 0.85-0.86). The level of agreement was within 0.39 mg/L (2 SD) (n = 16 279). The areas under the curve (AUCs) in the multivariable risk prediction model with cystatin C (Gentian, Roche) or Chronic Kidney Disease Epidemiology Collaboration eGFR (CKD-EPI) added were 0.6914, 0.6913, and 0.6932. Corresponding relative IDI values were 2.96%, 3.86%, and 4.68% (n = 13 050). Addition of eGFR by the combined creatinine-cystatin C equation yielded AUCs of 0.6923 (Gentian) and 0.6924 (Roche) with relative IDI values of 3.54% and 3.24%. Despite differences in cystatin C concentrations, overall correlation between the Gentian and Roche assays was good, while agreement was moderate. The combined creatinine-cystatin C equation did not outperform risk prediction by CKD-EPI.

  8. Mechanism of platelet functional changes and effects of anti-platelet agents on in vivo hemostasis under different gravity conditions.

    Science.gov (United States)

    Li, Suping; Shi, Quanwei; Liu, Guanglei; Zhang, Weilin; Wang, Zhicheng; Wang, Yuedan; Dai, Kesheng

    2010-05-01

    Serious thrombotic and hemorrhagic problems or even fatalities evoked by either microgravity or hypergravity occur commonly in the world. We recently reported that platelet functions are inhibited in microgravity environments and activated under high-G conditions, which reveals the pathogenesis for gravity change-related hemorrhagic and thrombotic diseases. However, the mechanisms of platelet functional variations under different gravity conditions remain unclear. In this study we show that the amount of filamin A coimmunoprecipitated with GPIbalpha was enhanced in platelets exposed to modeled microgravity and, in contrast, was reduced in 8 G-exposed platelets. Hypergravity induced actin filament formation and redistribution, whereas actin filaments were reduced in platelets treated with modeled microgravity. Furthermore, intracellular Ca2+ levels were elevated by hypergravity. Pretreatment of platelets with the cell-permeable Ca2+ chelator BAPTA-AM had no effect on cytoskeleton reorganization induced by hypergravity but significantly reduced platelet aggregation induced by ristocetin/hypergravity. Two anti-platelet agents, aspirin and tirofiban, effectively reversed the shortened tail bleeding time and reduced the death rate of mice exposed to hypergravity. Furthermore, the increased P-selectin surface expression was obviously reduced in platelets from mice treated with aspirin/hypergravity compared with those from mice treated with hypergravity alone. These data suggest that the actin cytoskeleton reorganization and intracellular Ca2+ level play key roles in the regulation of platelet functions in different gravitational environments. The results with anti-platelet agents not only further confirm the activation of platelets in vivo but also suggest a therapeutic potential for hypergravity-induced thrombotic diseases.

  9. Platelet counts and mean platelet volume amongst elderly Nigerians ...

    African Journals Online (AJOL)

    determining reference values of Platelet Counts, Mean Platelet Volume and the relationship between the Platelet Count and Mean Platelet Volume. These parameters were determined from 400 healthy elderly subjects comprising 210 males and 190 females. with a mean age of 69.4±7.9 years . 400 young adults were used ...

  10. Platelet-mediated metabolism of the common dietary flavonoid, quercetin.

    Directory of Open Access Journals (Sweden)

    Bernice Wright

    2010-03-01

    Full Text Available Flavonoid metabolites remain in blood for periods of time potentially long enough to allow interactions with cellular components of this tissue. It is well-established that flavonoids are metabolised within the intestine and liver into methylated, sulphated and glucuronidated counterparts, which inhibit platelet function.We demonstrate evidence suggesting platelets which contain metabolic enzymes, as an alternative location for flavonoid metabolism. Quercetin and a plasma metabolite of this compound, 4'-O-methyl quercetin (tamarixetin were shown to gain access to the cytosolic compartment of platelets, using confocal microscopy. High performance liquid chromatography (HPLC and mass spectrometry (MS showed that quercetin was transformed into a compound with a mass identical to tamarixetin, suggesting that the flavonoid was methylated by catechol-O-methyl transferase (COMT within platelets.Platelets potentially mediate a third phase of flavonoid metabolism, which may impact on the regulation of the function of these cells by metabolites of these dietary compounds.

  11. Metabolic Plasticity in Resting and Thrombin Activated Platelets

    Science.gov (United States)

    Ravi, Saranya; Chacko, Balu; Sawada, Hirotaka; Kramer, Philip A.; Johnson, Michelle S.; Benavides, Gloria A.; O’Donnell, Valerie; Marques, Marisa B.; Darley-Usmar, Victor M.

    2015-01-01

    Platelet thrombus formation includes several integrated processes involving aggregation, secretion of granules, release of arachidonic acid and clot retraction, but it is not clear which metabolic fuels are required to support these events. We hypothesized that there is flexibility in the fuels that can be utilized to serve the energetic and metabolic needs for resting and thrombin-dependent platelet aggregation. Using platelets from healthy human donors, we found that there was a rapid thrombin-dependent increase in oxidative phosphorylation which required both glutamine and fatty acids but not glucose. Inhibition of fatty acid oxidation or glutamine utilization could be compensated for by increased glycolytic flux. No evidence for significant mitochondrial dysfunction was found, and ATP/ADP ratios were maintained following the addition of thrombin, indicating the presence of functional and active mitochondrial oxidative phosphorylation during the early stages of aggregation. Interestingly, inhibition of fatty acid oxidation and glutaminolysis alone or in combination is not sufficient to prevent platelet aggregation, due to compensation from glycolysis, whereas inhibitors of glycolysis inhibited aggregation approximately 50%. The combined effects of inhibitors of glycolysis and oxidative phosphorylation were synergistic in the inhibition of platelet aggregation. In summary, both glycolysis and oxidative phosphorylation contribute to platelet metabolism in the resting and activated state, with fatty acid oxidation and to a smaller extent glutaminolysis contributing to the increased energy demand. PMID:25875958

  12. Metabolic plasticity in resting and thrombin activated platelets.

    Directory of Open Access Journals (Sweden)

    Saranya Ravi

    Full Text Available Platelet thrombus formation includes several integrated processes involving aggregation, secretion of granules, release of arachidonic acid and clot retraction, but it is not clear which metabolic fuels are required to support these events. We hypothesized that there is flexibility in the fuels that can be utilized to serve the energetic and metabolic needs for resting and thrombin-dependent platelet aggregation. Using platelets from healthy human donors, we found that there was a rapid thrombin-dependent increase in oxidative phosphorylation which required both glutamine and fatty acids but not glucose. Inhibition of fatty acid oxidation or glutamine utilization could be compensated for by increased glycolytic flux. No evidence for significant mitochondrial dysfunction was found, and ATP/ADP ratios were maintained following the addition of thrombin, indicating the presence of functional and active mitochondrial oxidative phosphorylation during the early stages of aggregation. Interestingly, inhibition of fatty acid oxidation and glutaminolysis alone or in combination is not sufficient to prevent platelet aggregation, due to compensation from glycolysis, whereas inhibitors of glycolysis inhibited aggregation approximately 50%. The combined effects of inhibitors of glycolysis and oxidative phosphorylation were synergistic in the inhibition of platelet aggregation. In summary, both glycolysis and oxidative phosphorylation contribute to platelet metabolism in the resting and activated state, with fatty acid oxidation and to a smaller extent glutaminolysis contributing to the increased energy demand.

  13. 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

  14. Platelets and their chemokines in atherosclerosis – clinical applications

    Directory of Open Access Journals (Sweden)

    Philipp evon Hundelshausen

    2014-08-01

    Full Text Available The concept of platelets as important players in the process of atherogenesis has become increasingly accepted due to accumulating experimental and clinical evidence. Despite the progress in understanding the molecular details of atherosclerosis, particularly by using animal models, the inflammatory and thrombotic roles of activated platelet s especially in the human system remain difficult to dissect, as often only the complications of atherosclerosis i.e. stroke and myocardial infarction are definable but not the plaque burden.Platelet indices including platelet count and mean platelet volume and soluble mediators released by activated platelets are associated with atherosclerosis. The chemokine CXCL4 has multiple atherogenic activities e.g. altering the differentiation of T cells and macrophages by inhibiting neutrophil and monocyte apoptosis and by increasing the uptake of oxLDL and synergizing with CCL5. CCL5 is released and deposited on endothelium by activated platelets thereby triggering atherogenic monocyte recruitment, which can be attenuated by blocking the corresponding chemokine receptor CCR5. Atheroprotective and plaque stabilizing properties are attributed to CXCL12, which plays an important role in regenerative processes by attracting progenitor cells. Its release from luminal attached platelets accelerates endothelial healing after injury. Platelet surface molecules GPIIb/IIIa, GP1bα, P-selectin, JAM-A and the CD40/CD40L dyade are crucially involved in the interaction with endothelial cells, leukocytes and matrix molecules affecting atherogenesis. Beyond the effects on the arterial inflammatory infiltrate, platelets affect cholesterol metabolism by binding, modifying and endocytosing LDL particles via their scavenger receptors and contribute to the formation of lipid laden macrophages. Current medical therapies for the prevention of atherosclerotic therapies enable the elucidation of mechanisms linking platelets to inflammation

  15. Macroscopic domain formation in the platelet plasma membrane

    DEFF Research Database (Denmark)

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

    2009-01-01

    phase behavior of the platelet plasma membrane by FTIR, and compare it to a POPC/Sphingomyelin/Cholesterol model representing the outer leaflet composition. We find that this model closely reflects the platelet phase behavior. Previous work has shown that the platelet plasma membrane presents......There has been ample debate on whether cell membranes can present macroscopic lipid domains as predicted by three-component phase diagrams obtained by fluorescence microscopy. Several groups have argued that membrane proteins and interactions with the cytoskeleton inhibit the formation of large...

  16. The effect of ginkgo formulations on platelet aggregation in rats

    OpenAIRE

    Skoko, Marija; Đikić, Domagoj; Čolić, Ivan; Tomičić, Maja; Vučemilo, Tiha

    2017-01-01

    Ginkgo biloba is an herbal remedy can be found as an ingredient of many dietary supplements. Ginkgo contains different biologically active compounds that can inhibit platelet aggregation. Prolonged platelet aggregation can have apositive effect on the cardiovascular system in cancer patients undergoing chemotherapy, but in oncological surgery (in particular major abdominal, gynecological, and operations with reconstructions) it can increase risk of bleeding.Consequently in these patients ther...

  17. Congenital platelet function defects

    Science.gov (United States)

    Arnold DM, Patriquin C, Toltl LJ, Nazi I, Smith J, Kelton J. Diseases of platelet number: immune thrombocytopenia, neonatal alloimmune thrombocytopenia, and posttransfusion purpura. In: Hoffman R, Benz EJ ...

  18. Dissolution of arterial platelet thrombi in vivo with a bifunctional platelet GPIIIa49-66 ligand which specifically targets the platelet thrombus.

    Science.gov (United States)

    Zhang, Wei; Li, Yong-Sheng; Nardi, Michael A; Dang, Suying; Yang, Jing; Ji, Yong; Li, Zongdong; Karpatkin, Simon; Wisniewski, Thomas

    2010-09-30

    Patients with HIV-1 immune-related thrombocytopenia have a unique antibody (Ab) against integrin GPIIIa49-66 capable of inducing oxidative platelet fragmentation via Ab activation of platelet nicotinamide adenine dinucleotide phosphate oxidase and 12-lipoxygenase releasing reactive oxygen species. Using a phage display single-chain antibody (scFv) library, we developed a novel human monoclonal scFv Ab against GPIIIa49-66 (named A11) capable of inducing fragmentation of activated platelets. In this study, we investigated the in vivo use of A11. We show that A11 does not induce significant thrombocytopenia or inhibit platelet function. A11 can prevent the cessation of carotid artery flow produced by induced artery injury and dissolve the induced thrombus 2 hours after cessation of blood flow. In addition, A11 can prevent, as well as ameliorate, murine middle cerebral artery stroke, without thrombocytopenia or brain hemorrhage. To further optimize the antithrombotic activity of A11, we produced a bifunctional A11-plasminogen first kringle agent (SLK), which homes to newly deposited fibrin strands within and surrounding the platelet thrombus, reducing effects on nonactivated circulating platelets. Indeed, SLK is able to completely reopen occluded carotid vessels 4 hours after cessation of blood flow, whereas A11 had no effect at 4 hours. Thus, a new antithrombotic agent was developed for platelet thrombus clearance.

  19. Outcomes after planned invasive or conservative treatment strategy in patients with non-ST-elevation acute coronary syndrome and a normal value of high sensitivity troponin at randomisation: A Platelet Inhibition and Patient Outcomes (PLATO) trial biomarker substudy.

    Science.gov (United States)

    Giannitsis, Evangelos; Wallentin, Lars; James, Stefan K; Bertilsson, Maria; Siegbahn, Agneta; Storey, Robert F; Husted, Steen; Cannon, Christopher P; Armstrong, Paul W; Steg, Philippe G; Katus, Hugo A

    2017-09-01

    Current guidelines for patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) recommend early invasive treatment in intermediate-to-high risk patients based on medical history, electrocardiogram (ECG) and elevated troponin. Patients with normal levels of cardiac troponin measured with a high-sensitivity method (cTnT-hs) might not benefit from early invasive procedures. In this Prospective Randomized Platelet Inhibition and Patient Outcomes (PLATO) blood-core substudy, 1232 patients presented with NSTE-ACS had a high sensitivity cardiac troponin T (cTnT-hs) level <99th percentile (<14 ng/l) at randomisation. The outcomes in relation to a planned invasive ( n=473) vs planned conservative treatment ( n=759), were evaluated by adjusted Cox proportional hazard analyses. In patients with a normal cTnT-hs at randomisation, regardless of randomised treatment, a planned invasive vs conservative treatment was associated with a 2.3-fold higher risk (7.3% vs 3.4%, p=0.0028) for cardiovascular (CV) death or myocardial infarction (MI), driven by higher rates of procedure-related MI (3.4% vs 0.1%), while there were no differences in rates of CV death (1.3% vs 1.3%, p=0.72) or spontaneous MI (3.0% vs 2.1%, p=0.28). There were significantly more major bleeds (hazard ratio (HR) 2.98, p<0.0001), mainly due to coronary artery bypass graft (CABG)-related (HR 4.05, p<0.0001) and non-CABG procedural-related major bleeding events (HR 5.31, p=0.0175), however there were no differences in non-procedure-related major bleeding (1.5% vs 1.9%, p=0.45). Findings were consistent for patients with a normal cTnI-hs at randomisation. In patients with NSTE-ACS and normal cTnT-hs, a planned early invasive treatment strategy was associated with increased rates of procedure-related MI and bleeding but no differences in long-term spontaneous MI, non-procedure-related bleeding or mortality.

  20. Cyclooxygenase-2 inhibition restored endothelium-mediated relaxation in old obese Zucker rat mesenteric arteries

    Directory of Open Access Journals (Sweden)

    Emilie Vessieres

    2010-11-01

    Full Text Available Metabolic syndrome is associated with reduced endothelial vasodilator function. It is also associated with the induction of cyclooxygenase-2 (COX2, which produces vasoactive prostanoids. The frequency of metabolic syndrome increases with age and aging per se is a risk factor associated with reduced endothelium-mediated relaxation. Nevertheless, the combined effect of aging and metabolic syndrome on the endothelium is less known. We hypothesized that COX2 derived prostanoids may affect endothelium function in metabolic syndrome associated with aging. We used obese Zucker rats, a model of metabolic syndrome. First order mesenteric arteries were isolated from 4 and 12 month-old rats and acetylcholine (endothelium-dependent relaxation determined using wire-myography.Endothelium-mediated relaxation, impaired in young Zucker rats (89 vs 77% maximal relaxation; lean vs. Zucker, was further reduced in old Zucker rats (72 vs 51%, lean vs. Zucker. The effect of the NO-synthesis inhibitor L-NAME on the relaxation was reduced in both young and old Zucker rats without change in eNOS expression level. COX inhibition (indomethacin improved acetylcholine-mediated relaxation in old obese rats only, suggesting involvement of vasoconstrictor prostanoids. In addition, COX2 inhibition (NS398 and TxA2/PGH2 receptor blockade (SQ29548 both improved relaxation in old Zucker rat arteries. Old Zucker rats had the highest TxB2 (TxA2 metabolite blood level associated with increased COX2 immunostaining. Chronic COX2 blockade (Celecoxib, 3 weeks restored endothelium-dependent relaxation in old Zucker rats to the level observed in old lean rats. Thus the combination of aging and metabolic syndrome further impairs endothelium-dependent relaxation by inducing an excessive production of COX2-derived vasoconstrictor(s; possibly TxA2.

  1. Clinical uses of radiolabeled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Datz, F.L.; Christian, P.E.; Baker, W.J.

    1985-12-01

    Platelets were first successfully radiolabeled in 1953. At that time, investigators were primarily interested in developing a technique to accurately measure platelet life span in both normal and thrombocytopenic patients. Studies using platelets labeled with /sup 51/Cr have shown shortened platelet survival times in a number of diseases including idiopathic thrombocytopenic purpura, coronary artery disease, and diabetes mellitus. More recently, labels such as /sup 111/In have been developed that allow in vivo imaging of platelets. Indium-111 platelets are being used to better understand the pathophysiology of atherosclerosis, thrombophlebitis, pulmonary embolism and clotting disorders, and to improve the clinical diagnosis of these diseases.

  2. Platelets stimulate fibroblast-mediated contraction of collagen gels

    Directory of Open Access Journals (Sweden)

    Lundahl Joachim

    2003-10-01

    Full Text Available Abstract Background Platelets are thought to play a role in a variety of inflammatory conditions in the lung, some of which may lead to fibrosis. In the current study we tested the hypothesis that whole platelets and platelet lysate can mediate remodelling of extracellular matrix in vitro by affecting fibroblast-mediated contraction of a collagen gel. We also sought to determine to what extent platelet-derived growth factor (PDGF and transforming growth factor-β (TGF-β contribute to this effect. Methods Washed platelets, isolated from healthy blood donors, and platelet lysate (freezing and thawing, were cast together with human lung fibroblasts in three-dimensional collagen gels. The gels were then released and cultured for four days. PDGF and TGF-β1 concentrations were measured in culture supernatants by ELISA. Results Both platelets and platelet lysate augmented fibroblast-mediated gel contraction in a time and concentration dependent manner (19.9% ± 0.1 (mean ± SEM of initial area vs. 48.0% ± 0.4 at 48 hours; P 1 and PDGF-AA/AB were released in co-culture. PDGF-AA/AB had a maximum release at 24 hours whereas TGF-β1 release increased with longer culture periods. Neutralising antibodies to these mediators partially inhibited platelet-induced gel contraction. Conclusion We conclude that platelets may promote remodelling of extracellular matrix in vitro and that PDGF and TGF-β partially mediate this effect, also indicating a role for other mediators. The findings may be an important mechanism in regulating repair processes after injury.

  3. Endothelium-dependent and -independent relaxations in aortic rings ...

    African Journals Online (AJOL)

    Hypertension was induced in inbred hooded rats (n=8 each) by administering 8% salt in the diet and /or 100 mg/kg/day Nω-nitro-L-arginine-methyl-ester (LNAME) in the drinking water for six and/or four weeks respectively. The rats were anaesthetized using a 25% urethane and 1% chloralose mixture given intraperitoneally ...

  4. Altered Endothelium-Dependent Vasoreactivity of Aortic Rings ...

    African Journals Online (AJOL)

    Purpose: The use of L-arginine and potassium chloride separately as supplements has been reported to result in altered vascular reactivity. The concentration of either agent used has varied widely and there has been no report on the outcome of combined supplementation with both agents on vascular reactivity.

  5. Plasma components are required for platelet activation by the toxin of Loxosceles reclusa.

    Science.gov (United States)

    Rees, R S; Gates, C; Timmons, S; Des Prez, R M; King, L E

    1988-01-01

    We have used a partially purified toxin from the venom of the brown recluse spider, Loxosceles reclusa, to study its effects on human platelets isolated from plasma proteins. This toxin, which produced skin necrosis in rabbits, contained sphingomyelinase D activity. The toxin induced platelet aggregation and secretion of [3H]serotonin in human plasma but not in buffer or in human neonate plasma. Ca2+ was required for the interaction of toxin, platelets, and plasma factor(s). The addition of C-reactive protein restored aggregation and serotonin release of platelets incubated in human neonate plasma. The ADP-degrading enzyme, apyrase, and the non-steroidal, anti-inflammatory drug, indomethacin, inhibited platelet aggregation, suggesting that ADP secreted from platelet storage granules and indomethacin-sensitive pathway(s) are involve in the toxin-induced human platelet activation (aggregation and serotonin release). Generation of platelet activating factor (PAF) from the platelet by brown recluse toxin is not likely since the PAF receptor antagonist, BN 52021, did not inhibit platelet aggregation induced by the brown recluse toxin.

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

    Science.gov (United States)

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

    2010-11-01

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

  7. Flavonoids and platelet aggregation: A brief review.

    Science.gov (United States)

    Faggio, Caterina; Sureda, Antoni; Morabito, Silvia; Sanches-Silva, Ana; Mocan, Andrei; Nabavi, Seyed Fazel; Nabavi, Seyed Mohammad

    2017-07-15

    Platelets are small anucleated fragments derived from a megakaryocyte precursor. Platelets play a key role in many physiological functions especially in hemostasis and wound healing processes in order to maintain the integrity of the circulatory system. In addition, activated platelets release cytokines and chemokines which modulate the immune response and, in some cases of hyperactivation, they could be associated to the pathogenesis of inflammatory diseases. Flavonoids are polyphenolic compounds ubiquosly found in plants known to be potent antioxidants with positive effects against diverse diseases such as cancer, neurodegenerative or cardiovascular disease. It has been reported that some flavonoids possess anti-platelet aggregation effects though different pathways, being the inhibition of the arachidonic acid-based pathway the most representative mechanism of action. In the present review, the main sources of flavonoids, as well as their bioavailability and metabolism are summarized. Moreover, the available data about the anti-aggregation effects of flavonoids and the different mechanisms of action that has been proposed until now are also discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The Platelet and Platelet Function Testing in Liver Disease

    NARCIS (Netherlands)

    Hugenholtz, Greg G. C.; Porte, Robert J.; Lisman, Ton

    Patients who have liver disease commonly present with alterations in platelet number and function. Recent data have questioned the contribution of these changes to bleeding complications in these patients. Modern tests of platelet function revealed compensatory mechanisms for the decreased platelet

  9. Mean Platelet Volume (MPV), Platelet Distribution Width (PDW ...

    African Journals Online (AJOL)

    Background: Thrombocytopenia has been shown to predict mortality. We hypothesize that platelet indices may be more useful prognostic indicators. Our study subjects were children one month to 14 years old admitted to our hospital. Aim: To determine whether platelet count, plateletcrit (PCT), mean platelet volume (MPV) ...

  10. Reproducibility of Manual Platelet Estimation Following Automated Low Platelet Counts

    Directory of Open Access Journals (Sweden)

    Zainab S Al-Hosni

    2016-11-01

    Full Text Available Objectives: Manual platelet estimation is one of the methods used when automated platelet estimates are very low. However, the reproducibility of manual platelet estimation has not been adequately studied. We sought to assess the reproducibility of manual platelet estimation following automated low platelet counts and to evaluate the impact of the level of experience of the person counting on the reproducibility of manual platelet estimates. Methods: In this cross-sectional study, peripheral blood films of patients with platelet counts less than 100 × 109/L were retrieved and given to four raters to perform manual platelet estimation independently using a predefined method (average of platelet counts in 10 fields using 100× objective multiplied by 20. Data were analyzed using intraclass correlation coefficient (ICC as a method of reproducibility assessment. Results: The ICC across the four raters was 0.840, indicating excellent agreement. The median difference of the two most experienced raters was 0 (range: -64 to 78. The level of platelet estimate by the least-experienced rater predicted the disagreement (p = 0.037. When assessing the difference between pairs of raters, there was no significant difference in the ICC (p = 0.420. Conclusions: The agreement between different raters using manual platelet estimation was excellent. Further confirmation is necessary, with a prospective study using a gold standard method of platelet counts.

  11. Evaluation of the TEG® platelet mapping™ assay in blood donors

    Directory of Open Access Journals (Sweden)

    Steinbrüchel Daniel A

    2007-02-01

    Full Text Available Abstract Background Monitoring of antiplatelet therapy in patients at cardiovascular risk is difficult because existing platelet function tests are too sophisticated for clinical routine. The whole blood TEG® Platelet Mapping™ assay measures clot strength as maximal amplitude (MA and enables for quantification of platelet function, including the contribution of the adenosine diphosphate (ADP and thromboxane A2 (TxA2 receptors to clot formation. Methods In 43 healthy blood donors, the analytical (CVa and inter-individual variability (CVg of the TEG® Platelet Mapping™ assay were determined together with platelet receptor inhibition in response to arachidonic acid (AA and ADP. Results The CVa of the assay for maximal platelet contribution to clot strength (MAThrombin was 3.5%, for the fibrin contribution to clot strength (MAFibrin 5.2%, for MAAA 4.5% and for MAADP it was 6.6%. The MAThrombin CVg was 2.8%, MAFibrin 4.7%, MAAA 6.6% and for MAADP it was 26.2%. Females had a higher MAThrombin compared to males (62.8 vs. 58.4 mm, p = 0.005. The platelet TxA2 receptor inhibition was 1.2% (range 0–10% and lower than for the ADP receptor (18.6% (0–58%; p Conclusion The high variability in ADP receptor inhibition may explain both the differences in response to ADP receptor inhibitor therapy and why major bleeding sometimes develops during surgery in patients not treated with ADP receptor inhibitors. An analytical variation of ~5 % for the TEG® enables, however, for routine monitoring of the variability in ADP receptor inhibition and of antiplatelet therapy.

  12. Material-induced tissue factor expression but not CD11b upregulation depends on the presence of platelets.

    Science.gov (United States)

    Gorbet, M B; Sefton, M V

    2003-12-01

    Biomaterials activate leukocytes as well as platelets when exposed to blood. One feature of leukocyte activation at least at times beyond a few hours is tissue factor expression, contributing to a procoagulant state. We show here that platelet activation and specifically platelet-monocyte aggregate formation appears to be a precondition for tissue factor expression. Material-induced Tissue Factor (TF) expression by isolated leukocytes (6 x 10(6) cells/mL) resuspended in increasing concentrations of platelets in plasma was elevated when the platelet concentration was 50 x 10(6) platelets/mL or more; at lower platelet concentrations (1-25 x 10(6). cells/mL) the TF expression remained at background levels. On the other hand, significant CD11b upregulation was observed on leukocytes, in bulk and adherent to beads, at all platelet concentrations. This platelet effect on material-induced TF expression appeared to be mediated by the formation of platelet-monocyte aggregates. Anti-P-selectin, which blocked the association between platelets and leukocytes, reduced monocyte adhesion and material-induced TF expression for bulk monocytes. Anti-GPIIb/IIIa, a GPIIb/IIIa platelet antagonist, also reduced monocyte adhesion and material-induced TF expression in the bulk, most likely due to its inhibiting effect on the formation of platelet-monocyte aggregates, secondary to platelet activation. However, the antibody-associated reductions for bulk leukocytes (mainly neutrophils) were small and incomplete. Similar levels of TF expression, in the bulk, were observed with both polystyrene (PS), a strong platelet activator, and polyethylene glycol-modified PEG (PS-PEG), a mild platelet activator. The role of platelets in material-induced TF expression appears to be mediated in part via the formation of platelet-monocyte aggregates, although other mechanisms are likely also involved. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 792-800, 2003

  13. Glu- and Lys-forms of plasminogen differentially affect phosphatidylserine exposure on the platelet surface

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    D. D. Zhernossekov

    2017-04-01

    Full Text Available Plasminogen/plasmin system is known for its ability to support hemostatic balance of blood. However, plasminogen may be considered as an adhesive ligand and in this way could affect the functioning of blood cells. We showed that exogenous Lys-plasminogen, but not its Glu-form, inhibited platelet aggregation and suppressed platelet α-granule secretion. The aim of this work was to investigate the influence of Glu- and Lys-form of plasminogen on the formation of platelet procoagulant surface using phosphatidylserine exposure as a marker. Human platelets were obtained from human platelet-rich plasma (donors were healthy volunteers, men aged 30-40 years by gel-filtration on Sepharose 2B. Phosphatidylserine exposure on the platelet surface was evaluated by flow cytometry with FITC-conjugated annexin A5. Glu- and Lys-plasminogen have different impact on the platelet functioning. Exogenous Lys-plasminogen has no significant effect on phosphatidylserine exposure, while Glu-plasminogen increases phosphatidylserine exposure on the surface of thrombin- and collagen-activated human platelets. Glu-plasminogen can be considered as a co-stimulator of agonist-induced platelet secretion and procoagulant surface formation. Meanwhile effects of Lys-plasminogen are probably directed at platelet-platelet interactions and not related to agonist-stimulated pro-apoptotic changes. The observed different effects of Glu- and Lys-plasminogen on phosphatidylserine exposure can be explained by their structural peculiarities.

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

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    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.

  15. SIRT1 prevents pulmonary thrombus formation induced by arachidonic acid via downregulation of PAF receptor expression in platelets.

    Science.gov (United States)

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

    2016-12-01

    SIRT1, a class III histone deacetylase, is critically involved in cellular response to stress and modulates cardiovascular risk factors. However, its role in thrombus formation is largely unknown. Thus, this study investigated the effect of SIRT1 on pulmonary thrombus formation, and then identified its role in the modulation of platelet aggregation. In isolated human platelets, cell aggregation was increased by various platelet activators, such as platelet activating factor (PAF), arachidonic acid (AA), ADP, and thrombin. AA- and PAF-mediated platelet aggregations were suppressed by WEB2086, a PAF receptor (PAFR) antagonist. Pulmonary thrombus formation induced by PAF or AA was also attenuated by WEB2086, suggesting that PAFR plays a key role in AA-induced platelet aggregation. In platelets isolated from SIRT1-TG mice as well as in platelets treated with resveratrol or reSIRT1, PAFR expression was decreased, whereas this expressional downregulation by SIRT1 activators was inhibited in platelets treated with MG132 (a proteasome inhibitor) or NH 4 Cl (a lysosome inhibitor). Furthermore, platelet aggregation induced by AA was markedly attenuated by resveratrol and reSIRT1. Likewise, the increased pulmonary thrombus formation in mice treated with AA was also attenuated by SIRT1 activators. In line with these results, pulmonary thrombus formation was markedly attenuated in SIRT1-TG mice. Taken together, this study showed that SIRT1 downregulates PAFR expression on platelets via proteasomal and lysosomal pathways, and that this downregulation inhibits platelet aggregation in vitro and pulmonary thrombus formation in vivo.

  16. Novel direct factor Xa inhibitory compounds from Tenebrio molitor with anti-platelet aggregation activity.

    Science.gov (United States)

    Lee, Wonhwa; Kim, Mi-Ae; Park, InWha; Hwang, Jae Sam; Na, MinKyun; Bae, Jong-Sup

    2017-11-01

    Tenebrio molitor is an edible insect that has antimicrobial, anticancer, and antihypertensive effects. The aim of this study was to identify the unreported bioactive compounds from T. molitor larvae with inhibitory activities against factor Xa (FXa) and platelet aggregation. Isolated compounds were evaluated for their anti-FXa and anti-platelet aggregation properties by monitoring clotting time, platelet aggregation, FXa activity, and thrombus formation. A diketopiperazine (1, cyclo(L-Pro-L-Tyr)) and a phenylethanoid (2, N-acetyltyramine) were isolated and inhibited the catalytic activity of FXa in a mixed inhibition model and inhibited platelet aggregation induced by adenosine diphosphate (ADP) and U46619. They inhibited ADP- and U46619-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) and the expression of P-selectin and PAC-1 in platelets. They also improved the production of nitric oxide and inhibited the oversecretion of endothelin-1 compared to that of the ADP- or U46619-treated group. In an animal model of arterial and pulmonary thrombosis, the isolated compounds showed enhanced antithrombotic effects. They also elicited anticoagulant effects in mice. Compounds 1-2 inhibited ADP-, collagen-, or U46619-induced platelet aggregation and showed similar anti-thrombotic efficacy to rivaroxaban, a positive control. Therefore, 1-2 could serve as candidates and provide scaffolds for the development of new anti-FXa and anti-platelet drugs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. FcgammaRII mediates platelet aggregation caused by disintegrins and GPIIb/IIIa monoclonal antibody, AP2.

    Science.gov (United States)

    Huang, Tur-Fu; Chang, Chien-Hsin; Ho, Pei-Ling; Chung, Ching-Hu

    2008-12-01

    Disintegrins, snake venom-derived Arg-Gly-Asp (RGD)-containing polypeptides, and GPIIb/IIIa antagonist (AP2) block fibrinogen binding to GPIIb/IIIa of activated platelets, however, the combination of these two agents caused platelet aggregation. We hypothesize that disintegrin initially binds to specific epitope of GPIIb/IIIa, causing conformational change, and the recruitment of FcgammaRII, which can be bound by AP2, and finally triggering platelet aggregation. We prepared human platelet suspensions and measured platelet aggregation, Ca2+ mobilization, thromboxane B2 formation, and signal transduction. Disintegrin (e.g., accutin) and AP2 (a monoclonal antibody [mAb]-raised against GPIIb/IIIa) individually inhibited human platelet aggregation caused by collagen. However, as both accutin and AP2 were sequentially added into platelet suspension, platelet aggregation occurred. Accutin/AP2 caused shape change, cytosolic Ca2+ mobilization, P-selectin expression, and thromboxane A2 formation. Tirofiban, FcgammaRII mAb, or indomethacin completely inhibited platelet aggregation caused by accutin/AP2. Accutin/AP2 also caused tyrosine phosphorylation of signal molecules. Disintegrins enhanced AP2 binding to platelets, and AP2 also promoted disintegrin binding to platelets. FcgammaRII mAb inhibited the enhanced fluorescein isothiocyanate-disintegrin binding to platelet caused by AP2. Immunoprecipitation of the lysates of disintegrin/AP2-treated platelets using FcgammaRII Ab showed complex formation of GPIIb/IIIa and FcgammaRII. FcgammaRII mediates platelet aggregation caused by disintegrin and AP2, triggering a phospholipase C, phospholipase A2, Src-, Syk kinases, and Ca2+-dependent activation process. AP2 triggers platelet aggregation via binding to accessible FcgammaRII and the conformation-altered GPIIb/IIIa caused by disintegrin.

  18. 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.

  19. Biology of Platelet Purinergic Receptors and Implications for Platelet Heterogeneity

    Directory of Open Access Journals (Sweden)

    Milka Koupenova

    2018-01-01

    Full Text Available Platelets are small anucleated cells present only in mammals. Platelets mediate intravascular hemostatic balance, prevent interstitial bleeding, and have a major role in thrombosis. Activation of platelet purinergic receptors is instrumental in initiation of hemostasis and formation of the hemostatic plug, although this activation process becomes problematic in pathological settings of thrombosis. This review briefly outlines the roles and function of currently known platelet purinergic receptors (P1 and P2 in the setting of hemostasis and thrombosis. Additionally, we discuss recent novel studies on purinergic receptor distribution according to heterogeneous platelet size, and the possible implication of this distribution on hemostatic function.

  20. 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.

  1. Anti-platelet activity of a three-finger toxin (3FTx) from Indian monocled cobra (Naja kaouthia) venom.

    Science.gov (United States)

    Chanda, Chandrasekhar; Sarkar, Angshuman; Sistla, Srinivas; Chakrabarty, Dibakar

    2013-11-22

    A low molecular weight anti-platelet peptide (6.9 kDa) has been purified from Naja kaouthia venom and was named KT-6.9. MALDI-TOF/TOF mass spectrometry analysis revealed the homology of KT-6.9 peptide sequence with many three finger toxin family members. KT-6.9 inhibited human platelet aggregation process in a dose dependent manner. It has inhibited ADP, thrombin and arachidonic acid induced platelet aggregation process in dose dependent manner, but did not inhibit collagen and ristocetin induced platelet aggregation. Strong inhibition (70%) of the ADP induced platelet aggregation by KT-6.9 suggests competition with ADP for its receptors on platelet surface. Anti-platelet activity of KT-6.9 was found to be 25 times stronger than that of anti-platelet drug clopidogrel. Binding of KT-6.9 to platelet surface was confirmed by surface plasma resonance analysis using BIAcore X100. Binding was also observed by a modified sandwich ELISA method using anti-KT-6.9 antibodies. KT-6.9 is probably the first 3 FTx from Indian monocled cobra venom reported as a platelet aggregation inhibitor. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Peroxynitrite may affect fibrinolysis via the reduction of platelet-related fibrinolysis resistance and alteration of clot structure.

    Science.gov (United States)

    Misztal, Tomasz; Rusak, Tomasz; Brańska-Januszewska, Justyna; Ostrowska, Halina; Tomasiak, Marian

    2015-12-01

    We tested the hypothesis that in vitro peroxynitrite (ONOO(-), a product of activated inflammatory cells) may affect fibrinolysis in human blood through the reduction of platelet-related fibrinolysis resistance. It was found that ONOO(-) (25-300 µM) accelerated lysis of platelet-fibrin clots (in PRP) dose-dependently, whereas fibrinolysis of platelet-free clots was slightly inhibited by ≥ 1000 µM stressor. Concentrations of ONOO(-) affecting the lysis of platelet-rich clots, inhibited clot retraction (CR) in a dose-dependent manner. Thromboelastometry (ROTEM) measurements performed in PRP showed that treatment with ONOO(-) (threshold conc. 100 µM) prolongs clotting time, and reduces alpha angle, and clot formation velocity parameters indicating for reduced thrombin formation rate. In PRP, ONOO(-) (threshold conc. 100 µM) reduced the collagen-evoked exposure of phosphatidylserine (PS) on platelets' plasma membrane, the shedding of platelet-derived microparticles (PMP), and inhibited platelet-dependent thrombin generation (measured in artificial system), dose-dependently. As judged by confocal microscopy, similar ONOO(-) concentrations altered the architecture of clots formed in collagen-treated PRP. Clots formed in the presence of ONOO(-) were less dense and were composed of thicker fibers, which make them more susceptible to lysis. In platelet-depleted plasma, ONOO(-) (up to milimolar concentration) did not alter clot structure. Blockage of PS exposed on platelets resulted in an alteration of clot architecture toward more prone to lysis. ONOO(-), at lysis-affecting concentrations, inhibited the collagen-evoked secretion of fibrinolytic inhibitors from platelets. We conclude that physiologically relevant ONOO(-) concentrations may accelerate the lysis of platelet-fibrin clots predominantly via downregulation of platelet-related mechanisms including: platelet secretion, clot retraction, platelet procoagulant response, and the alteration in clot architecture

  3. The Impact of Helicobacter pylori Urease upon Platelets and Consequent Contributions to Inflammation

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    Adriele Scopel-Guerra

    2017-12-01

    Full Text Available Gastric infection by Helicobacter pylori is considered a risk factor for gastric and duodenal cancer, and extragastric diseases. Previous data have shown that, in a non-enzymatic way, H. pylori urease (HPU activates neutrophils to produce ROS and also induces platelet aggregation, requiring ADP secretion modulated by the 12-lipoxygenase pathway, a signaling cascade also triggered by the physiological agonist collagen. Here we investigated further the effects on platelets of recombinant versions of the holoenzyme HPU, and of its two subunits (HpUreA and HpUreB. Although HpUreA had no aggregating activity on platelets, it partially inhibited collagen-induced aggregation. HpUreB induced platelet aggregation in the nanomolar range, and also interfered dose-dependently on both collagen- and ADP-induced platelet aggregation. HPU-induced platelet aggregation was inhibited by antibodies against glycoprotein VI (GPVI, the main collagen receptor in platelets. Flow cytometry analysis revealed exposure of P-selectin in HPU-activated platelets. Anti-glycoprotein IIbIIIa (GPIIbIIIa antibodies increased the binding of FITC-labeled HPU to activated platelets, whereas anti-GPVI did not. Evaluation of post-transcriptional events in HPU-activated platelets revealed modifications in the pre-mRNA processing of pro-inflammatory proteins, with increased levels of mRNAs encoding IL-1β and CD14. We concluded that HPU activates platelets probably through its HpUreB subunit. Activation of platelets by HPU turns these cells into a pro-inflammatory phenotype. Altogether, our data suggest that H. pylori urease, besides allowing bacterial survival within the gastric mucosa, may have an important, and so far overlooked, role in gastric inflammation mediated by urease-activated neutrophils and platelets.

  4. The Impact of Helicobacter pylori Urease upon Platelets and Consequent Contributions to Inflammation.

    Science.gov (United States)

    Scopel-Guerra, Adriele; Olivera-Severo, Deiber; Staniscuaski, Fernanda; Uberti, Augusto F; Callai-Silva, Natália; Jaeger, Natália; Porto, Bárbara N; Carlini, Celia R

    2017-01-01

    Gastric infection by Helicobacter pylori is considered a risk factor for gastric and duodenal cancer, and extragastric diseases. Previous data have shown that, in a non-enzymatic way, H. pylori urease (HPU) activates neutrophils to produce ROS and also induces platelet aggregation, requiring ADP secretion modulated by the 12-lipoxygenase pathway, a signaling cascade also triggered by the physiological agonist collagen. Here we investigated further the effects on platelets of recombinant versions of the holoenzyme HPU, and of its two subunits (HpUreA and HpUreB). Although HpUreA had no aggregating activity on platelets, it partially inhibited collagen-induced aggregation. HpUreB induced platelet aggregation in the nanomolar range, and also interfered dose-dependently on both collagen- and ADP-induced platelet aggregation. HPU-induced platelet aggregation was inhibited by antibodies against glycoprotein VI (GPVI), the main collagen receptor in platelets. Flow cytometry analysis revealed exposure of P-selectin in HPU-activated platelets. Anti-glycoprotein IIbIIIa (GPIIbIIIa) antibodies increased the binding of FITC-labeled HPU to activated platelets, whereas anti-GPVI did not. Evaluation of post-transcriptional events in HPU-activated platelets revealed modifications in the pre-mRNA processing of pro-inflammatory proteins, with increased levels of mRNAs encoding IL-1β and CD14. We concluded that HPU activates platelets probably through its HpUreB subunit. Activation of platelets by HPU turns these cells into a pro-inflammatory phenotype. Altogether, our data suggest that H. pylori urease, besides allowing bacterial survival within the gastric mucosa, may have an important, and so far overlooked, role in gastric inflammation mediated by urease-activated neutrophils and platelets.

  5. Hyaluronic acid influence on platelet-induced airway smooth muscle cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Svensson Holm, Ann-Charlotte B., E-mail: ann-charlotte.svensson@liu.se [Division of Drug Research/Pharmacology, Department of Medical and Health Sciences, Faculty of Health Sciences, Linkoeping University, SE-581 85 Linkoeping (Sweden); Experimental Pathology, Department of Clinical and Experimental Medicine, Linkoeping University, SE-581 85 Linkoeping (Sweden); Bengtsson, Torbjoern [Department of Biomedicine, School of Health and Medical Sciences, Oerebro University, SE-70182 Oerebro (Sweden); Grenegard, Magnus; Lindstroem, Eva G. [Division of Drug Research/Pharmacology, Department of Medical and Health Sciences, Faculty of Health Sciences, Linkoeping University, SE-581 85 Linkoeping (Sweden)

    2012-03-10

    Hyaluronic acid (HA) is one of the main components of the extracellular matrix (ECM) and is expressed throughout the body including the lung and mostly in areas surrounding proliferating and migrating cells. Furthermore, platelets have been implicated as important players in the airway remodelling process, e.g. due to their ability to induce airway smooth muscle cell (ASMC) proliferation. The aim of the present study was to investigate the role of HA, the HA-binding surface receptor CD44 and focal adhesion kinase (FAK) in platelet-induced ASMC proliferation. Proliferation of ASMC was measured using the MTS-assay, and we found that the CD44 blocking antibody and the HA synthase inhibitor 4-Methylumbelliferone (4-MU) significantly inhibited platelet-induced ASMC proliferation. The interaction between ASMC and platelets was studied by fluorescent staining of F-actin. In addition, the ability of ASMC to synthesise HA was investigated by fluorescent staining using biotinylated HA-binding protein and a streptavidin conjugate. We observed that ASMC produced HA and that a CD44 blocking antibody and 4-MU significantly inhibited platelet binding to the area surrounding the ASMC. Furthermore, the FAK-inhibitor PF 573228 inhibited platelet-induced ASMC proliferation. Co-culture of ASMC and platelets also resulted in increased phosphorylation of FAK as detected by Western blot analysis. In addition, 4-MU significantly inhibited the increased FAK-phosphorylation. In conclusion, our findings demonstrate that ECM has the ability to influence platelet-induced ASMC proliferation. Specifically, we propose that HA produced by ASMC is recognised by platelet CD44. The platelet/HA interaction is followed by FAK activation and increased proliferation of co-cultured ASMC. We also suggest that the mitogenic effect of platelets represents a potential important and novel mechanism that may contribute to airway remodelling.

  6. Sulfatides partition disabled-2 in response to platelet activation.

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    Karen E Drahos

    Full Text Available BACKGROUND: Platelets contact each other at the site of vascular injury to stop bleeding. One negative regulator of platelet aggregation is Disabled-2 (Dab2, which is released to the extracellular surface upon platelet activation. Dab2 inhibits platelet aggregation through its phosphotyrosine-binding (PTB domain by competing with fibrinogen for alphaIIbbeta3 integrin receptor binding by an unknown mechanism. METHODOLOGY/PRINCIPAL FINDINGS: Using protein-lipid overlay and liposome-binding assays, we identified that the N-terminal region of Dab2, including its PTB domain (N-PTB, specifically interacts with sulfatides. Moreover, we determined that such interaction is mediated by two conserved basic motifs with a dissociation constant (K(d of 0.6 microM as estimated by surface plasmon resonance (SPR analysis. In addition, liposome-binding assays combined with mass spectroscopy studies revealed that thrombin, a strong platelet agonist, cleaved N-PTB at a site located between the basic motifs, a region that becomes protected from thrombin cleavage when bound to sulfatides. Sulfatides on the platelet surface interact with coagulation proteins, playing a major role in haemostasis. Our results show that sulfatides recruit N-PTB to the platelet surface, sequestering it from integrin receptor binding during platelet activation. This is a transient recruitment that follows N-PTB internalization by an actin-dependent process. CONCLUSIONS/SIGNIFICANCE: Our experimental data support a model where two pools of Dab2 co-exist at the platelet surface, in both sulfatide- and integrin receptor-bound states, and their balance controls the extent of the clotting response.

  7. Mean Platelet Volume

    African Journals Online (AJOL)

    Department of Chest Disease, Bolu, Turkey. E-mail: abanttip14@gmail.com. Telephone number: +903742534618. Fax number: +903742534615 effective and should have wide spread acceptance. At present, none of the available diagnostic tests meets all these criteria. The mean platelet volume (MPV) is potentially one of.

  8. Platelet dynamics during natural and pharmacologically induced torpor and forced hypothermia.

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    Edwin L de Vrij

    Full Text Available Hibernation is an energy-conserving behavior in winter characterized by two phases: torpor and arousal. During torpor, markedly reduced metabolic activity results in inactivity and decreased body temperature. Arousal periods intersperse the torpor bouts and feature increased metabolism and euthermic body temperature. Alterations in physiological parameters, such as suppression of hemostasis, are thought to allow hibernators to survive periods of torpor and arousal without organ injury. While the state of torpor is potentially procoagulant, due to low blood flow, increased viscosity, immobility, hypoxia, and low body temperature, organ injury due to thromboembolism is absent. To investigate platelet dynamics during hibernation, we measured platelet count and function during and after natural torpor, pharmacologically induced torpor and forced hypothermia. Splenectomies were performed to unravel potential storage sites of platelets during torpor. Here we show that decreasing body temperature drives thrombocytopenia during torpor in hamster with maintained functionality of circulating platelets. Interestingly, hamster platelets during torpor do not express P-selectin, but expression is induced by treatment with ADP. Platelet count rapidly restores during arousal and rewarming. Platelet dynamics in hibernation are not affected by splenectomy before or during torpor. Reversible thrombocytopenia was also induced by forced hypothermia in both hibernating (hamster and non-hibernating (rat and mouse species without changing platelet function. Pharmacological torpor induced by injection of 5'-AMP in mice did not induce thrombocytopenia, possibly because 5'-AMP inhibits platelet function. The rapidness of changes in the numbers of circulating platelets, as well as marginal changes in immature platelet fractions upon arousal, strongly suggest that storage-and-release underlies the reversible thrombocytopenia during natural torpor. Possibly, margination of

  9. 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.

  10. Pyocyanin inhibits both nitric oxide-dependent and -independent relaxation in porcine coronary arteries.

    Science.gov (United States)

    Hempenstall, Allison; Grant, Gary D; Anoopkumar-Dukie, Shailendra; Johnson, Peter J

    2015-02-01

    The effects of the Pseudomonas aeruginosa virulence factor pyocyanin (PCN) on the contractile function of porcine coronary arteries was investigated in vitro. Artery rings (5 mm) were suspended in organ baths containing Krebs' solution for the measurement of isometric tension. The effect of PCN on resting and precontracted coronary arteries was initially investigated with various agents. Arteries were precontracted with prostaglandin (PG) F2α or potassium chloride and endothelium-dependent relaxations were induced by various agents in the presence of PCN. Pyocyanin (0.1-10 μmol/L) evoked small-amplitude, dose-dependent contractions in resting porcine coronary arteries. In addition, PCN amplified the contractile response to PGF2α , but did not alter responses to carbachol. Pyocyanin (0.1-10 μmol/L) significantly inhibited endothelium-dependent relaxations evoked by neurokinin A. Pyocyanin also inhibited relaxations evoked by diethylamine nitric oxide (a nitric oxide donor), forskolin (an adenylate cyclase activator), dibuytyryl-cAMP (a cAMP analogue), 8-bromo-cGMP (a cGMP analogue) and P1075 (a KATP channel activator), but not isoprenaline (β-adrenoceceptor agonist). These results indicate that physiological concentrations of PCN interfere with multiple intracellular processes involved in vascular smooth muscle relaxation, in particular pathways downstream of nitric oxide release. Thus, PCN may alter normal vascular function in patients infected with P. aeruginosa. © 2014 Wiley Publishing Asia Pty Ltd.

  11. Comparison of platelet counting technologies in equine platelet concentrates.

    Science.gov (United States)

    O'Shea, Caitlin M; Werre, Stephen R; Dahlgren, Linda A

    2015-04-01

    (1) To compare the performance of 4 platelet counting technologies in equine platelet concentrates and (2) to evaluate the ability of the Magellan platelet rich plasma (PRP) system to concentrate equine platelets. Experimental study to assess method agreement. Adult mixed breed horses (n = 32). Acid citrate dextrose-A anti-coagulated whole blood was collected and PRP produced using the Magellan system according to the manufacturer's instructions. Platelets were quantified using 4 counting methods: optical scatter (Advia 2120), impedance (CellDyn 3700), hand counting, and fluorescent antibody flow cytometry. Platelet concentrations were compared using Passing and Bablok regression analyses and mixed model ANOVA. Significance was set at P CellDyn 3700. Systematic and proportional biases were observed between these 2 automated methods when analyzed by regression analysis of the larger sample size. No bias (systematic or proportional) was observed among any of the other counting methods. Despite the bias detected between the 2 automated systems, there were no significant differences on average among the 4 counting methods evaluated, based on the ANOVA. The Magellan system consistently generated high platelet concentrations as well as higher than expected WBC concentrations. The Magellan system delivered desirably high platelet concentrations; however, WBC concentrations may be unacceptably high for some orthopedic applications. All 4 platelet counting methods tested were equivalent on average and therefore suitable for quantifying platelets in equine PRP used for clinical applications. © Copyright 2014 by The American College of Veterinary Surgeons.

  12. Aprotinin administration in the pericardial cavity does not prevent platelet activation

    NARCIS (Netherlands)

    Maquelin, K. N.; Nieuwland, R.; Lentjes, E. G.; Böing, A. N.; Mochtar, B.; Eijsman, L.; Sturk, A.

    2000-01-01

    Aprotinin is frequently administered systemically to patients undergoing cardiopulmonary bypass to inhibit activation of platelets and plasma protein systems and thus reduce postoperative blood loss. Two reports on local aprotinin administration, that is, into the pericardial cavity, also indicated

  13. Storage of platelets: effects associated with high platelet content in platelet storage containers.

    Science.gov (United States)

    Gulliksson, Hans; Sandgren, Per; Sjödin, Agneta; Hultenby, Kjell

    2012-04-01

    A major problem associated with platelet storage containers is that some platelet units show a dramatic fall in pH, especially above certain platelet contents. The aim of this study was a detailed investigation of the different in vitro effects occurring when the maximum storage capacity of a platelet container is exceeded as compared to normal storage. Buffy coats were combined in large-volume containers to create primary pools to be split into two equal aliquots for the preparation of platelets (450-520×10(9) platelets/unit) in SSP+ for 7-day storage in two containers (test and reference) with different platelet storage capacity (n=8). Exceeding the maximum storage capacity of the test platelet storage container resulted in immediate negative effects on platelet metabolism and energy supply, but also delayed effects on platelet function, activation and disintegration. Our study gives a very clear indication of the effects in different phases associated with exceeding the maximum storage capacity of platelet containers but throw little additional light on the mechanism initiating those negative effects. The problem appears to be complex and further studies in different media using different storage containers will be needed to understand the mechanisms involved.

  14. Impact of aspirin and clopidogrel interruption on platelet function in patients undergoing major vascular surgery.

    Directory of Open Access Journals (Sweden)

    Yannick Le Manach

    Full Text Available AIMS: To investigate functional platelet recovery after preoperative withdrawal of aspirin and clopidogrel and platelet function 5 days after treatment resumption. METHODS/RESULTS: We conducted an observational study, which prospectively included consecutive patients taking aspirin, taking clopidogrel, and untreated controls (15 patients in each group. The antiplatelet drugs were withdrawn five days before surgery (baseline and were reintroduced two days after surgery. Platelet function was evaluated by optical aggregation in the presence of collagen, arachidonic acid (aspirin and ADP (clopidogrel and by VASP assay (clopidogrel. Platelet-leukocyte complex (PLC level was quantified at each time-point. At baseline, platelet function was efficiently inhibited by aspirin and had recovered fully in most patients 5 days after drug withdrawal. PLC levels five days after aspirin reintroduction were similar to baseline (+4±10%; p = 0.16, in line with an effective platelet inhibition. Chronic clopidogrel treatment was associated with variable platelet inhibition and its withdrawal led to variable functional recovery. PLC levels were significantly increased five days after clopidogrel reintroduction (+10±15%; p = 0.02, compared to baseline. CONCLUSIONS: Aspirin withdrawal 5 days before high-bleeding-risk procedures was associated with functional platelet recovery, and its reintroduction two days after surgery restored antiplaletet efficacy five days later. This was not the case of clopidogrel, and further work is therefore needed to define its optimal perioperative management.

  15. Platelet proteome reveals novel pathways of platelet activation and platelet-mediated immunoregulation in dengue.

    Directory of Open Access Journals (Sweden)

    Monique Ramos de Oliveira Trugilho

    2017-05-01

    Full Text Available Dengue is the most prevalent human arbovirus disease worldwide. Dengue virus (DENV infection causes syndromes varying from self-limiting febrile illness to severe dengue. Although dengue pathophysiology is not completely understood, it is widely accepted that increased inflammation plays important roles in dengue pathogenesis. Platelets are blood cells classically known as effectors of hemostasis which have been increasingly recognized to have major immune and inflammatory activities. Nevertheless, the phenotype and effector functions of platelets in dengue pathogenesis are not completely understood. Here we used quantitative proteomics to investigate the protein content of platelets in clinical samples from patients with dengue compared to platelets from healthy donors. Our assays revealed a set of 252 differentially abundant proteins. In silico analyses associated these proteins with key molecular events including platelet activation and inflammatory responses, and with events not previously attributed to platelets during dengue infection including antigen processing and presentation, proteasome activity, and expression of histones. From these results, we conducted functional assays using samples from a larger cohort of patients and demonstrated evidence for platelet activation indicated by P-selectin (CD62P translocation and secretion of granule-stored chemokines by platelets. In addition, we found evidence that DENV infection triggers HLA class I synthesis and surface expression by a mechanism depending on functional proteasome activity. Furthermore, we demonstrate that cell-free histone H2A released during dengue infection binds to platelets, increasing platelet activation. These findings are consistent with functional importance of HLA class I, proteasome subunits, and histones that we found exclusively in proteome analysis of platelets in samples from dengue patients. Our study provides the first in-depth characterization of the platelet

  16. Platelet proteome reveals novel pathways of platelet activation and platelet-mediated immunoregulation in dengue.

    Science.gov (United States)

    Trugilho, Monique Ramos de Oliveira; Hottz, Eugenio Damaceno; Brunoro, Giselle Villa Flor; Teixeira-Ferreira, André; Carvalho, Paulo Costa; Salazar, Gustavo Adolfo; Zimmerman, Guy A; Bozza, Fernando A; Bozza, Patrícia T; Perales, Jonas

    2017-05-01

    Dengue is the most prevalent human arbovirus disease worldwide. Dengue virus (DENV) infection causes syndromes varying from self-limiting febrile illness to severe dengue. Although dengue pathophysiology is not completely understood, it is widely accepted that increased inflammation plays important roles in dengue pathogenesis. Platelets are blood cells classically known as effectors of hemostasis which have been increasingly recognized to have major immune and inflammatory activities. Nevertheless, the phenotype and effector functions of platelets in dengue pathogenesis are not completely understood. Here we used quantitative proteomics to investigate the protein content of platelets in clinical samples from patients with dengue compared to platelets from healthy donors. Our assays revealed a set of 252 differentially abundant proteins. In silico analyses associated these proteins with key molecular events including platelet activation and inflammatory responses, and with events not previously attributed to platelets during dengue infection including antigen processing and presentation, proteasome activity, and expression of histones. From these results, we conducted functional assays using samples from a larger cohort of patients and demonstrated evidence for platelet activation indicated by P-selectin (CD62P) translocation and secretion of granule-stored chemokines by platelets. In addition, we found evidence that DENV infection triggers HLA class I synthesis and surface expression by a mechanism depending on functional proteasome activity. Furthermore, we demonstrate that cell-free histone H2A released during dengue infection binds to platelets, increasing platelet activation. These findings are consistent with functional importance of HLA class I, proteasome subunits, and histones that we found exclusively in proteome analysis of platelets in samples from dengue patients. Our study provides the first in-depth characterization of the platelet proteome in dengue

  17. Dynamic platelet adhesion in patients with an acute coronary syndrome: The effect of antiplatelet therapy.

    Science.gov (United States)

    Tsoumani, Maria E; Tatsidou, Prokopia T; Ntalas, Ioannis V; Goudevenos, John A; Tselepis, Alexandros D

    2016-12-01

    Platelet adhesion and aggregation are key functions leading to thrombus formation. The effect of aspirin, clopidogrel, and ticagrelor on platelet aggregation has been well established, however, there is limited data on the effect of these drugs on platelet adhesion. We therefore evaluated the effect of these drugs on platelet adhesion in acute coronary syndrome (ACS) patients. Citrated blood was collected from 50 ACS patients loaded with 325 mg of aspirin (baseline) and at 5 days after the administration of aspirin 100 mg/day and clopidogrel (600 mg loading dose, 75 mg/day) (n = 26) or ticagrelor (180 mg loading dose, 90 mg × 2/day) (n = 24). High on-treatment platelet reactivity (HTPR) to clopidogrel was estimated by vasodilator stimulated phosphoprotein (VASP) phosphorylation assay. Platelet adhesion to collagen was studied for 6 min under high shear stress and was evaluated using the time to platelet recruitment (TPR), the perimeter and average area of each adherent object, number of adherent objects, and the total percent of surface coverage (SC%). Six ACS patients exhibited HTPR to clopidogrel and excluded from the platelet adhesion assays. TPR and SC% values were similar among patient groups at baseline and controls. However, all other adhesion parameters were different in ACS patients, indicating the formation of more aggregates in regard to controls. At 5 days post-treatment with either clopidogrel or ticagrelor, the TPR values were increased and the SC% values were reduced to a similar extent compared with baseline. However, significant differences were observed in the ticagrelor group in the perimeter, number of adherent objects, and the average area of each adherent object indicating a more potent inhibition of adherence-induced platelet aggregation than clopidogrel. In conclusion, aspirin does not affect platelet adherence to collagen, whereas clopidogrel and ticagrelor inhibit to a similar extent dynamic platelet adhesion at 5 days post-treatment in

  18. Extension of platelet concentrate storage.

    Science.gov (United States)

    Simon, T L; Nelson, E J; Carmen, R; Murphy, S

    1983-01-01

    Extension of the storage time of platelet concentrates in a satellite bag which is part of a new blood bag system was studied by reinfusing autologous 51Cr-labeled platelets into normal volunteers, and measuring postinfusion platelet counts and bleeding times in patients requiring platelet transfusions. This satellite bag, made of polyvinylchloride plasticized with a new agent, was found to protect platelet concentrates against fall of pH better than other containers studied. This protection was felt to be due to the greater gas permeability of the new plastic. Mean in vivo recovery and half-life (greater than 31% and 3.3 days, respectively) of autologous reinfused platelets were satisfactory following 5 days of storage. Following 7 days of storage, mean recovery was 41 percent and half-life was 2.8 days. Peripheral platelet count increments in patients following platelet transfusions with concentrates stored 4 to 7 days in the new plastic were comparable to increments following transfusion of platelets stored 2 to 3 days in the other plastics studied. Bleeding times shortened in three of four patients receiving platelet concentrates stored from 4 to 6 days in the new plastic. Platelet concentrates stored in the new bag at 20 to 24 degrees C with flat-bed or elliptical agitation could be transfused for up to 5 days following phlebotomy with acceptable clinical results. The new plastic container is promising for storage of platelet concentrates for up to 7 days. Due to the higher pH of 50-ml platelet concentrates stored in bags made with the new plastic, the concentrates were superior at any storage interval to those stored in bags made of the other plastics studied.

  19. El ejercicio físico aeróbico incrementa la vasodilatación dependiente del endotelio y el consumo de oxígeno de mujeres primigestantes saludables. Ensayo clínico controlado, aleatorizado. NCT00741312 Aerobic physical exercise increases endothelium-dependent vasodilation and oxygen consumption in healthy primigravida. Controlled randomized clinical trial. NCT00741312

    Directory of Open Access Journals (Sweden)

    Róbinson Ramírez-Vélez

    2010-12-01

    Full Text Available OBJETIVO: evaluar el efecto del ejercicio aeróbico en la función dependiente del endotelio (VDE y en el consumo de oxígeno en mujeres primigestantes. MÉTODOS: ensayo clínico controlado, enmascarado y aleatorizado, llevado a cabo en 67 mujeres saludables, primigestantes, entre 16 a 20 semanas de gestación. Grupo de intervención: ejercicio aeróbico entre 50% y 65% de la frecuencia cardiaca máxima, durante 45 minutos, tres veces por semana, durante dieciséis semanas. Grupo control: actividad física habitual. Mediciones: VDE: vasodilatación mediada por flujo (VMF, consumo de oxígeno VO2max: prueba de caminata de seis minutos; antropometría: peso y talla. RESULTADOS: en las mediciones iniciales no se encontraron diferencias entre grupos en ninguna de las variables. Al finalizar la intervención, las participantes que realizaron ejercicio tenían mayor capacidad física, medida por la distancia recorrida en el test de caminata (p=0,043 y por el VO2max (p=0,023. Además, el grupo de ejercicio tuvo menor frecuencia cardiaca en reposo y mayor VMF que el grupo control (pOBJECTIVE: evaluate the effect of aerobic exercise on endothelium-dependent function (EDF and oxygen consumption in primigravida. METHODS: double-blind, randomized controlled clinical trial carried out in primigravida between 16 to 20 weeks of gestation. The intervention group had aerobic exercise between 50% to 65% of the maximum heart rate during 45 minutes, three times a week for sixteen weeks. The control group had habitual physical activity. MEASUREMENTS REALIZED: EDF: flow-mediated dilation (FMD, oxygen consumption VO2max: 6 minute walking test, anthropometry: weight and size. RESULTS: no differences were found between the two groups in any variables in the initial measurements. At the end of the intervention, participants who exercised had greater physical capacity, measured by the distance covered in walking test (p = 0.043 and VO2max (p = 0.023. In addition, the

  20. Evolving role of platelet function testing in coronary artery interventions.

    Science.gov (United States)

    Sharma, Rakesh K; Voelker, Donald J; Sharma, Rohit; Reddy, Hanumanth K; Dod, Harvinder; Marsh, James D

    2012-01-01

    The substantial reduction in ischemic events provided by the dual antiplatelet regimen with aspirin and clopidogrel is well documented in patients with acute coronary syndrome and patients undergoing percutaneous coronary intervention. Recently the variable response to the antiplatelet agents has received considerable attention after several "boxed warnings" on clopidogrel. This led to intense controversy on pharmacokinetic, pharmacodynamic, and pharmacogenomic issues of antiplatelet drugs, especially clopidogrel. Research use of platelet function testing has been successfully validated in identifying new antiplatelet drugs like prasugrel and ticagrelor. These platelet function assays are no longer regarded just as a laboratory phenomenon but rather as tools that have been shown to predict mortality in several clinical trials. It is believed that suboptimal response to an antiplatelet regimen (pharmacodynamic effect) may be associated with cardiovascular, cerebrovascular, and peripheral arterial events. There has been intense controversy about this variable response of antiplatelet drugs and the role of platelet function testing to guide antiplatelet therapy. While the importance of routine platelet function testing may be uncertain, it may be useful in high-risk patients such as those with diabetes mellitus, diffuse three vessels coronary artery disease, left main stenosis, diffuse atherosclerotic disease, and those with chronic renal failure undergoing percutaneous coronary intervention. It could also be useful in patients with suspected pharmacodynamic interaction with other drugs to assure the adequacy of platelet inhibition. While we wait for definitive trials, a predictive prognostic algorithm is necessary to individualize antiplatelet therapy with P2Y12 inhibitors based on platelet function assays and genetic testing.

  1. 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.

  2. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    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...

  3. 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.

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

    Science.gov (United States)

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

    2017-12-01

    Thrombopoietin (TPO) may facilitate platelet activation and aggregation. However, data on the impact of TPO on platelet aggregation in patients with stable coronary artery disease (CAD) are scarce. We aimed to investigate associations between TPO and platelet aggregation and activation in patients with stable coronary artery disease (CAD). We studied 900 stable CAD patients. Serum TPO was assessed by ELISA. Platelet aggregation was evaluated using the Multiplate Analyzer (agonists: arachidonic acid [AA] and collagen) and the VerifyNow Aspirin Assay. Platelet activation was evaluated by soluble (s)P-selectin. Cyclooxygenase-1 inhibition was evaluated by serum thromboxane B2 (TXB2). We found that TPO correlated weakly with platelet aggregation evaluated by Multiplate using AA (r = -0.09, p = 0.01) and collagen as agonists (r = -0.03, p = 0.43) and by VerifyNow (r = 0.07, p = 0.03). We found no correlation between TPO and sP-selectin (r = -0.01, p = 0.70). Independent predictors of AA-induced platelet aggregation by Multiplate included high levels of sP-selectin and serum TXB2, high platelet count, increasing age and body mass index, female sex, and active smoking. Independent predictors of TPO included low AA-induced platelet aggregation by Multiplate, high levels of hs-CRP, active smoking, and high platelet aggregation evaluated by VerifyNow. In conclusion, TPO levels did not correlate with platelet activation and only weak associations were found between TPO and platelet aggregation, suggesting that TPO did not substantially facilitate platelet aggregation in stable CAD patients.

  5. Platelet immunology in fungal infections.

    Science.gov (United States)

    Speth, Cornelia; Rambach, Günter; Lass-Flörl, Cornelia

    2014-10-01

    Up to date, perception of platelets has changed from key players in coagulation to multitaskers within the immune network, connecting its most diverse elements and crucially shaping their interplay with invading pathogens such as fungi. In addition, antimicrobial effector molecules and mechanisms in platelets enable a direct inhibitory effect on fungi, thus completing their immune capacity. To precisely assess the impact of platelets on the course of invasive fungal infections is complicated by some critical parameters. First, there is a fragile balance between protective antimicrobial effects and detrimental reactions that aggravate the fungal pathogenesis. Second, some platelet effects are exerted indirectly by other immune mediators and are thus difficult to quantify. Third, drugs such as antimycotics, antibiotics, or cytostatics, are commonly administered to the patients and might modulate the interplay between platelets and fungi. Our article highlights selected aspects of the complex interactions between platelets and fungi and the relevance of these processes for the pathogenesis of fungal infections.

  6. Evolving role of platelet function testing in coronary artery interventions

    Directory of Open Access Journals (Sweden)

    Reddy HK

    2012-02-01

    Full Text Available Rakesh K Sharma1, Donald J Voelker1, Rohit Sharma1, Hanumanth K Reddy1, Harvinder Dod1, James D Marsh21Medical Center of South Arkansas, 2Division of Cardiology, University of Arkansas for Medical Sciences, Little Rock, AR, USAAbstract: The substantial reduction in ischemic events provided by the dual antiplatelet regimen with aspirin and clopidogrel is well documented in patients with acute coronary syndrome and patients undergoing percutaneous coronary intervention. Recently the variable response to the antiplatelet agents has received considerable attention after several “boxed warnings” on clopidogrel. This led to intense controversy on pharmacokinetic, pharmacodynamic, and pharmacogenomic issues of antiplatelet drugs, especially clopidogrel. Research use of platelet function testing has been successfully validated in identifying new antiplatelet drugs like prasugrel and ticagrelor. These platelet function assays are no longer regarded just as a laboratory phenomenon but rather as tools that have been shown to predict mortality in several clinical trials. It is believed that suboptimal response to an antiplatelet regimen (pharmacodynamic effect may be associated with cardiovascular, cerebrovascular, and peripheral arterial events. There has been intense controversy about this variable response of antiplatelet drugs and the role of platelet function testing to guide antiplatelet therapy. While the importance of routine platelet function testing may be uncertain, it may be useful in high-risk patients such as those with diabetes mellitus, diffuse three vessels coronary artery disease, left main stenosis, diffuse atherosclerotic disease, and those with chronic renal failure undergoing percutaneous coronary intervention. It could also be useful in patients with suspected pharmacodynamic interaction with other drugs to assure the adequacy of platelet inhibition. While we wait for definitive trials, a predictive prognostic algorithm is

  7. Platelet receptors for the Streptococcus sanguis adhesin and aggregation-associated antigens are distinguished by anti-idiotypical monoclonal antibodies.

    Science.gov (United States)

    Gong, K; Wen, D Y; Ouyang, T; Rao, A T; Herzberg, M C

    1995-09-01

    Platelets aggregate in response to an adhesin and the platelet aggregation-associated protein (PAAP) expressed on the cell surfaces of certain strains of Streptococcus sanguis. We sought to identify the corresponding PAAP receptor and accessory adhesin binding sites on platelets. Since the adhesion(s) of S. sanguis for platelets has not been characterized, an anti-idiotype (anti-id) murine monoclonal antibody (MAb2) strategy was developed. First, MAb1s that distinguished the adhesin and PAAP antigens on the surface of S. sanguis I 133-79 were selected. Fab fragments of MAb1.2 (immunoglobulin G2b [IgG2b]; 70 pmol) reacted with 5 x 10(7) cells of S. sanguis to completely inhibit the aggregation of human platelets in plasma. Under similar conditions, MAb1.1 (IgG1) inhibited the adhesion of S. sanguis cells to platelets by a maximum of 34%, with a comparatively small effect on platelet aggregation. Together, these two MAb1s inhibited S. sanguis-platelet adhesion by 63%. In Western immunoblots, both MAb1s reacted with S. sanguis 133-79 87- and 150-kDa surface proteins and MAb1.2 also reacted with purified type I collagen. The hybridomas producing MAb1.1 and MAb1.2 were then injected into BALB/c mice. Enlarged spleens were harvested, and a panel of MAb2 hybridomas was prepared. To identify anti-ids against the specific MAb1s, the MAb2 panel was screened by enzyme-linked immunosorbent assay for reaction with rabbit polyclonal IgG antibodies against the 87- and 150-kDa antigens. The reactions between the specific rabbit antibodies and anti-ids were inhibited by the 87- and 150-kDa antigens. When preincubated with platelets, MAb2.1 (counterpart of MAb1.1) inhibited adhesion to platelets maximally by 46% and MAb2.2 (anti-MAb1.2) inhibited adhesion to platelets maximally by 35%. Together, both MAb2s inhibited the adhesion of S. sanguis to platelets by 81%. MAb2.2 also inhibited induction of platelet aggregation. MAb2.2 immunoprecipitated a biotinylated platelet membrane

  8. The effects of ropivacaine hydrochloride on platelet function: an assessment using the platelet function analyser (PFA-100).

    LENUS (Irish Health Repository)

    Porter, J

    2012-02-03

    Amide local anaesthetics impair blood clotting in a concentration-dependent manner by inhibition of platelet function and enhanced fibrinolysis. We hypothesised that the presence of ropivacaine in the epidural space could decrease the efficacy of an epidural blood patch, as this technique requires that the injected blood can clot in order to be effective. Ropivacaine is an aminoamide local anaesthetic used increasingly for epidural analgesia during labour. The concentration of local anaesthetic in blood achieved in the epidural space during the performance of an epidural blood patch is likely to be the greatest which occurs (intentionally) in any clinical setting. This study was undertaken to investigate whether concentrations of ropivacaine in blood, which could occur: (i) clinically in the epidural space and (ii) in plasma during an epidural infusion of ropivacaine, alter platelet function. A platelet function analyser (Dade PFA-100, Miami) was employed to assess the effects of ropivacaine-treated blood on platelet function. The greater concentrations of ropivacaine studied (3.75 and 1.88 mg x ml(-1)), which correspond to those which could occur in the epidural space, produced significant inhibition of platelet aggregation. We conclude that the presence of ropivacaine in the epidural space may decrease the efficacy of an early or prophylactic epidural blood patch.

  9. Orthobiologics and platelet rich plasma

    National Research Council Canada - National Science Library

    Dhillon, Mandeep S; Behera, Prateek; Patel, Sandeep; Shetty, Vijay

    2014-01-01

    ... in many chronic musculoskeletal ailments. Investigators have published results of laboratory as well as clinical studies, using orthobiologics like platelet rich plasma, stem cells, autologous conditioned serum etc...

  10. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    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.

  11. Isolation of Platelet-Derived Extracellular Vesicles

    NARCIS (Netherlands)

    Aatonen, Maria; Valkonen, Sami; Böing, Anita; Yuana, Yuana; Nieuwland, Rienk; Siljander, Pia

    2017-01-01

    Platelets participate in several physiological functions, including hemostasis, immunity, and development. Additionally, platelets play key roles in arterial thrombosis and cancer progression. Given this plethora of functions, there is a strong interest of the role of platelet-derived

  12. Platelet activation, adhesion, inflammation, and aggregation potential are altered in the presence of electronic cigarette extracts of variable nicotine concentrations.

    Science.gov (United States)

    Hom, Sarah; Chen, Li; Wang, Tony; Ghebrehiwet, Berhane; Yin, Wei; Rubenstein, David A

    2016-11-01

    Tobacco smoke extracts prepared from both mainstream and sidestream smoking have been associated with heightened platelet activation, aggregation, adhesion, and inflammation. Conversely, it has been shown that pure nicotine inhibits similar platelet functions. In this work, we 1) evaluated the effects of e-cigarette extracts on platelet activities and 2) elucidated the differences between the nicotine-dependent and non-nicotine dependent (e.g. fine particulate matter or toxic compounds) effects of tobacco and e-cigarette products on platelet activities. To accomplish these goals, platelets from healthy volunteers (n = 50) were exposed to tobacco smoke extracts, e-cigarette vapor extracts, and pure nicotine and changes in platelet activation, adhesion, aggregation, and inflammation were evaluated, using optical aggregation, flow cytometry, and ELISA methods. Interestingly, the exposure of platelets to e-vapor extracts induced a significant up-regulation in the expression of the pro-inflammatory gC1qR and cC1qR and induced a marked increase in the deposition of C3b as compared with traditional tobacco smoke extracts. Similarly, platelet activation, as measured by a prothrombinase based assay, and platelet aggregation were also significantly enhanced after exposure to e-vapor extracts. Finally, platelet adhesion potential toward fibrinogen, von Willebrand factor, and other platelets was also enhanced after exposure to e-cigarette vapor extracts. In the presence of pure nicotine, platelet functions were observed to be inhibited, which further suggests that other constituents of tobacco smoke and electronic vapor can antagonize platelet functions, however, the presence of nicotine in extracts somewhat perpetuated the platelet functional changes in a dose-dependent manner.

  13. Platelets activate a pathogenic response to blood-stage Plasmodium infection but not a protective immune response.

    Science.gov (United States)

    Gramaglia, Irene; Velez, Joyce; Combes, Valery; Grau, Georges E R; Wree, Melanie; van der Heyde, Henri C

    2017-03-23

    Clinical studies indicate that thrombocytopenia correlates with the development of severe falciparum malaria, suggesting that platelets either contribute to control of parasite replication, possibly as innate parasite killer cells or function in eliciting pathogenesis. Removal of platelets by anti-CD41 mAb treatment, platelet inhibition by aspirin, and adoptive transfer of wild-type (WT) platelets to CD40-KO mice, which do not control parasite replication, resulted in similar parasitemia compared with control mice. Human platelets at a physiologic ratio of 1 platelet to 9 red blood cells (RBCs) did not inhibit the in vitro development or replication of blood-stage Plasmodium falciparum The percentage of Plasmodium-infected (iRBCs) with bound platelets during the ascending parasitemia in Plasmodium chabaudi- and Plasmodium berghei-infected mice and the 48-hour in vitro cycle of P falciparum was <10%. P chabaudi and P berghei iRBCs with apoptotic parasites (TdT+) exhibited minimal platelet binding (<5%), which was similar to nonapoptotic iRBCs. These findings collectively indicate platelets do not kill bloodstage Plasmodium at physiologically relevant effector-to-target ratios. P chabaudi primary and secondary parasitemia was similar in mice depleted of platelets by mAb-injection just before infection, indicating that activation of the protective immune response does not require platelets. In contrast to the lack of an effect on parasite replication, adoptive transfer of WT platelets to CD40-KO mice, which are resistant to experimental cerebral malaria, partially restored experimental cerebral malaria mortality and symptoms in CD40-KO recipients, indicating platelets elicit pathogenesis and platelet CD40 is a key molecule. © 2017 by The American Society of Hematology.

  14. Influenza Virus Infection Induces Platelet-Endothelial Adhesion Which Contributes to Lung Injury.

    Science.gov (United States)

    Sugiyama, Michael G; Gamage, Asela; Zyla, Roman; Armstrong, Susan M; Advani, Suzanne; Advani, Andrew; Wang, Changsen; Lee, Warren L

    2015-12-04

    Lung injury after influenza infection is characterized by increased permeability of the lung microvasculature, culminating in acute respiratory failure. Platelets interact with activated endothelial cells and have been implicated in the pathogenesis of some forms of acute lung injury. Autopsy studies have revealed pulmonary microthrombi after influenza infection, and epidemiological studies suggest that influenza vaccination is protective against pulmonary thromboembolism; however, the effect of influenza infection on platelet-endothelial interactions is unclear. We demonstrate that endothelial infection with both laboratory and clinical strains of influenza virus increased the adhesion of human platelets to primary human lung microvascular endothelial cells. Platelets adhered to infected cells as well as to neighboring cells, suggesting a paracrine effect. Influenza infection caused the upregulation of von Willebrand factor and ICAM-1, but blocking these receptors did not prevent platelet-endothelial adhesion. Instead, platelet adhesion was inhibited by both RGDS peptide and a blocking antibody to platelet integrin α5β1, implicating endothelial fibronectin. Concordantly, lung histology from infected mice revealed viral dose-dependent colocalization of viral nucleoprotein and the endothelial marker PECAM-1, while platelet adhesion and fibronectin deposition also were observed in the lungs of influenza-infected mice. Inhibition of platelets using acetylsalicylic acid significantly improved survival, a finding confirmed using a second antiplatelet agent. Thus, influenza infection induces platelet-lung endothelial adhesion via fibronectin, contributing to mortality from acute lung injury. The inhibition of platelets may constitute a practical adjunctive strategy to the treatment of severe infections with influenza.IMPORTANCE There is growing appreciation of the involvement of the lung endothelium in the pathogenesis of severe infections with influenza virus. We have

  15. 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.

  16. Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets.

    Science.gov (United States)

    Palabrica, T; Lobb, R; Furie, B C; Aronovitz, M; Benjamin, C; Hsu, Y M; Sajer, S A; Furie, B

    1992-10-29

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

  17. Early Platelet Dysfunction: An Unrecognized Role in the Acute Coagulopathy of Trauma

    Science.gov (United States)

    Wohlauer, Max V.; Moore, Ernest E.; Thomas, Scott; Sauaia, Angela; Evans, Ed; Harr, Jeffrey; Silliman, Christopher C.; Ploplis, Victoria; Castellino, Francis J.; Walsh, Mark

    2012-01-01

    Background To determine the prevalence of platelet dysfunction, using an end-point of assembly into a stable thrombus, following severe injury. Background: Although the current debate on acute traumatic coagulopathy (ATC) has focused on the consumption or inhibition of coagulation factors, the question of early platelet dysfunction in this setting remains unclear. Study Design Prospective platelet function in assembly and stability of the thrombus was determined within 30 minutes of injury using whole blood samples from trauma patients at the point of care employing thrombelastography (TEG)-based platelet functional analysis. Results There were 51 patients in the study. There were significant differences in the platelet response between trauma patients and healthy volunteers such that there was impaired aggregation to these agonists. In trauma patients, the median ADP inhibition of platelet function was 86.1% (IQR: 38.6–97.7%), compared to 4.2 % (IQR 0–18.2%) in healthy volunteers. Following trauma, the impairment of platelet function in response to AA was 44.9% (IQR 26.6–59.3%), compared to 0.5% (IQR 0–3.02%) in volunteers (Wilcoxon non parametric test ptrauma, before significant fluid or blood administration. These data suggest a potential role for early platelet transfusion in severely injured patients at risk for postinjury coagulopathy. PMID:22520693

  18. Mean Platelet Volume and Platelet Immunofluorescence as Indicators of Platelet Compatibility.

    Science.gov (United States)

    1983-02-23

    2.5 ml of 1.2% EDTA in 0.9% NaCl. The platelet- rich plasm (PRP) was isolated by centrifugation at 280 X g for 5 mimmter. The PRP from all the blood...samples was pooled, and the platelets were concentrated by cpntrifugation at 1000 X g for 10 minutes. The platelet- poor plasma (PPP) was removed and the...to -6.4% 2 shrinking 18. TABLE 2 .60A PLATLET _RLUME OF A+ OR 0+ DONOR PLATELETS TREATED WITH EITHER &U,&06OS S O SRUMNFRN AN AOIMMUNIZED TR

  19. Comparative Effects of Phenylbutazone, Naproxen and Flunixin Meglumine on Equine Platelet Aggregation and Platelet Factor 3 Availability in vitro

    Science.gov (United States)

    Johnstone, I.B.

    1983-01-01

    Nonsteroidal anti-inflammatory drugs are commonly used in the treatment of inflammatory conditions, and have potential value in the treatment of thrombotic disease in the horse. This study compares the potency of three nonsteroidal anti-inflammatory drugs phenylbutazone, naproxen (equiproxen) and flunixin meglumine (banamine) with respect to their effects on equine platelets. Two functional responses of horse platelets were evaluated in vitro: their ability to aggregate and their ability to make available platelet factor 3 procoagulant activity. Flunixin at a concentration of 10-6 M significantly depressed the maximum degree of adenosine diphosphate-induced (10-6M) aggregation while much higher concentrations of phenylbutazone and naproxen (5 X 105M) were required to produce similar effects. None of the non-steriodal anti-inflammatory drugs significantly affected the duration of the lag phase or the initial velocity of adenosine diphosphate-induced aggregation within the range of drug concentrations used (10-6-10-3M). The lag phase and initial velocity of acid-soluble collagen-induced aggregation were significantly affected by 10-6 M flunixin and 10-4 M phenylbutazone or naproxen was required to produce equivalent effects. Concentrations of 5 X 10-6 M flunixin and 5 X 10-4 M phenylbutazone or naproxen were required to significantly depress the degree of collaen-induced aggregation of horse platelets. Although the effects of the nonsteroidal anti-inflammatory drugs were qualitatively similar, flunixin was a much more potent inhibitor of platelet aggregation than either of the other two drugs (which were equipotent). At very high drug concentrations (5 X 10-4 M and greater), all three drugs produced the same degree of inhibition of equine platelet aggregation. Platelet factor 3 activity was made available by exposing horse platelets to 10-5 M adenosine diphosphate or 1:800 acid-soluble collagen; but not by exposure to a suspension of kaolin particles. Only a small

  20. Platelet Rich Plasma in Periodontal Therapy

    National Research Council Canada - National Science Library

    S Sathya Priya Eshwar; Dhayanand John Victor; S Sangeetha; PSG Prakash

    2017-01-01

    Keywords: Growth factors, Platelet concentrates, Platelet Rich Plasma, Regenerative medicine, Tissue engineering Introduction The goal of periodontal therapy is to improve periodontal health and thereby...

  1. Macrophage pro-inflammatory cytokine secretion is enhanced following interaction with autologous platelets

    Directory of Open Access Journals (Sweden)

    Fischer Thomas H

    2010-11-01

    Full Text Available Abstract Background Macrophages are the dominant phagocyte at sites of wound healing and inflammation, and the cellular and acellular debris encountered by macrophages can have profound effects on their inflammatory profile. Following interaction with apoptotic cells, macrophages are known to switch to an anti-inflammatory phenotype. Activated platelets, however, are also a major component of inflammatory lesions and have been proposed to be pro-inflammatory mediators. In the present study, we tested the hypothesis that macrophage interaction with activated platelets results in an inflammatory response that differs from the response following phagocytosis of apoptotic cells. Methods Human monocyte-derived macrophages (hMDMs were co-incubated with autologous activated platelets (AAPs and the platelet-macrophage interaction was examined by electron microscopy and flow cytometry. The cytokines TNF-α, IL-6, and IL-23 were also measured during LPS-activated hMDM co-incubation with AAPs, which was compared to co-incubation with apoptotic lymphocytes. Cytokine secretion was also compared to platelets pre-treated with the gluococorticoid dexamethasone. Results Macrophages trapped and phagocytized AAPs utilizing a mechanism that was significantly inhibited by the scavenger receptor ligand fucoidan. LPS-induced macrophage secretion of TNF-α, IL-6, and IL-23 was inhibited by co-incubation with apoptotic cells, but enhanced by co-incubation with AAPs. The platelet-dependent enhancement of LPS-induced cytokines could be reversed by pre-loading the platelets with the glucocorticoid dexamethasone. Conclusions The interaction of human macrophages with autologous platelets results in scavenger-receptor-mediated platelet uptake and enhancement of LPS-induced cytokines. Therefore, the presence of activated platelets at sites of inflammation may exacerbate pro-inflammatory macrophage activation. The possibility of reversing macrophage activation with

  2. 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.

  3. The Toxicity of a Chemically Synthesized Peptide Derived from Non-Integrin Platelet Collagen Receptors

    Directory of Open Access Journals (Sweden)

    Thomas M. Chiang

    2008-01-01

    Full Text Available A chemically synthesized peptide derived from platelet non-integrin collagen receptor has been shown to be an effective agent for inhibiting collagen-induced platelet aggregation and adhesion of washed radiolabeled platelets onto natural matrices and collagen coated microtiter plates. In order to be a therapeutic agent, we have used a cell culturing system and an animal model to test its cytotoxicities. In cell culture experiments, the peptide is not toxic to MEG-01, a megakaryoblastic cell line. Prior to performing experiments in rats, the existence of both platelet type I and type III collagen receptors and its functional roles in rat platelets had to be established. In this investigation, we report that rat platelets contain both receptors and the cHyB peptide inhibits both type I and type III collagen-induced rat platelet aggregation. In addition, analysis of the rat sera collected at various time intervals following an injection of cHyB into the rat-tail vein, did not show an increase in the activity of key enzymes which indicate tissue and/or organ damage. These results suggest that the cHyB peptide is safe and its development into a potential therapeutic agent for inhibiting thrombi formation is possible.

  4. The Toxicity of a Chemically Synthesized Peptide Derived from Non-Integrin Platelet Collagen Receptors

    Directory of Open Access Journals (Sweden)

    Thomas M. Chiang

    2008-08-01

    Full Text Available A chemically synthesized peptide derived from platelet non-integrin collagen receptor has been shown to be an effective agent for inhibiting collagen-induced platelet aggregation and adhesion of washed radiolabeled platelets onto natural matrices and collagen coated microtiter plates. In order to be a therapeutic agent, we have used a cell culturing system and an animal model to test its cytotoxicities. In cell culture experiments, the peptide is not toxic to MEG-01, a megakaryoblastic cell line. Prior to performing experiments in rats, the existence of both platelet type I and type III collagen receptors and its functional roles in rat platelets had to be established. In this investigation, we report that rat platelets contain both receptors and the cHyB peptide inhibits both type I and type III collagen-induced rat platelet aggregation. In addition, analysis of the rat sera collected at various time intervals following an injection of cHyB into the rat-tail vein, did not show an increase in the activity of key enzymes which indicate tissue and/or organ damage. These results suggest that the cHyB peptide is safe and its development into a potential therapeutic agent for inhibiting thrombi formation is possible.

  5. The Toxicity of a Chemically Synthesized Peptide Derived from Non-Integrin Platelet Collagen Receptors

    Directory of Open Access Journals (Sweden)

    Thomas M. Chiang

    2008-01-01

    Full Text Available A chemically synthesized peptide derived from platelet non-integrin collagen receptor has been shown to be an effective agent for inhibiting collagen-induced platelet aggregation and adhesion of washed radiolabeled platelets onto natural matrices and collagen coated microtiter plates. In order to be a therapeutic agent, we have used a cell culturing system and an animal model to test its cytotoxicities. In cell culture experiments, the peptide is not toxic to MEG-01, a megakaryo-blastic cell line. Prior to performing experiments in rats, the existence of both platelet type I and type III collagen receptors and its functional roles in rat platelets had to be established. In this investigation, we report that rat platelets contain both receptors and the cHyB peptide inhibits both type I and type III collagen-induced rat platelet aggregation. In addition, analysis of the rat sera collected at various time intervals following an injection of cHyB into the rat-tail vein, did not show an increase in the activity of key enzymes which indicate tissue and/or organ damage. These results suggest that the cHyB peptide is safe and its development into a potential therapeutic agent for inhibiting thrombi formation is possible.

  6. The diversity of platelet microparticles.

    Science.gov (United States)

    Boilard, Eric; Duchez, Anne-Claire; Brisson, Alain

    2015-09-01

    Platelet microparticles are small extracellular vesicles abundant in blood. The present review will introduce the mechanisms underlying the generation of microparticles, and will describe the diverse microparticle subtypes identified to date. The most appropriate methodologies used to distinguish microparticle subtypes will be also presented. Both the megakaryocytes and platelets can generate microparticles. Circulating microparticles originating from megakaryocytes are distinguished from those derived from activated platelets by the presence of CD62P, LAMP-1, and immunoreceptor-based activation motif receptors. Close examination of platelet activation has shed light on a novel mechanism leading to microparticle production. Under physiologic flow, microparticles bud off from long membrane strands formed by activated platelets. Furthermore, mounting evidence supports the notion of microparticle heterogeneity. Platelet microparticles are commonly characterized by the expression of surface platelet antigens and phosphatidylserine. In fact, only a fraction of platelet microparticles harbor phosphatidylserine, and a distinct subset contains respiratory-competent mitochondria. During disease, the microparticle surface may undergo posttranslational modifications such as citrullination, further supporting the concept of microparticle diversity. An appreciation of the microparticle heterogeneity will support their development as potential biomarkers and may reveal functions unique to each microparticle subtype in health and disease.

  7. Effects of cancer on platelets

    NARCIS (Netherlands)

    van Es, Nick; Sturk, Auguste; Middeldorp, Saskia; Nieuwland, Rienk

    2014-01-01

    The main function of circulating platelets is to stop bleeding upon vascular injury by the formation of a hemostatic plug. The presence of cancer results in numerical and functional abnormalities of platelets. Thrombocytosis is commonly observed in cancer patients and is associated with decreased

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

    Directory of Open Access Journals (Sweden)

    Qiang Peng

    Full Text Available 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.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.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.Although pig hepatocytes and aortic endothelial cells directly caused aggregation of baboon platelets, only pig liver

  9. Role of platelets in inflammation

    Directory of Open Access Journals (Sweden)

    Kadir Serkan Yalçın

    2012-09-01

    Full Text Available Inflammation, which is extremely useful process for humanbody is the response of living vascular tissues topathological phenomena that removes the pathogens andinitiates the healing procedure. Microorganisms, physicaltrauma, chemical, mechanical, irradiation, or thermal injury,ischemia and immune reactions are most commoncauses of this exceptionally important event for humanbody. Platelets are non-nucleated cells in blood that producedin bone marrow as derived from megakaryocytes.Apart from stop bleeding and achieving hemostasis thereare incredibly important roles of platelets in inflammation.Platelets contain important mediators for inflammationlike neutrophils or macrophages and can alter the courseof mechanism. In this article changing platelet function ininflammation and the effect of these functions to the processof inflammation will be discussed.Key words: Platelet, inflammation, cytokines

  10. Platelet aggregation associated with ethanol intoxication

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Platelet indices in SGA newborns.

    Science.gov (United States)

    Wasiluk, A; Dabrowska, M; Osada, J; Jasinska, E; Laudanski, T; Redzko, S

    2011-01-01

    The current study objective was to compare blood platelet indices in full-term small-for-gestational-age newborns (SGA) and full-term appropriate-for-gestational-age newborns (AGA). We introduced to our study 61 SGA newborns (31 females and 30 males) and 70 eutrophic infants (32 females and 38 males). The SGA newborns were divided into two groups: those weighing less than the 5th centile: 35 infants (16 females and 19 males) and those between the 5th and 10th centiles: 26 infants (15 females and 11 males). Platelet indices were estimated in blood samples collected from the umbilical artery. SGA demonstrated a decreased count of blood platelets (238×103/μ) as compared with AGA (286×103/μL), p=0.0001. Platelet hematocrit (PTC) also showed differences in both groups (SGA=0.19% vs. AGA=0.22%; p=0.0005). Mean platelet volume (MPV) was higher in SGA (8.25fl) as compared with AGA (7.84fl); p=0.008. Large platelet count (LPLT) was higher in AGA 6.26% vs. SGA=4.75%; p=0.01. Platelet distribution width (PDW) was found to be nearly the same (SGA=47%, AGA=46%). PDW was higher in SGA newborns SGA infants between the 5th and 10th centiles (52%); p=0.008. A decreased blood platelet count, platelet hematocrit and large metabolically active platelet count, which in addition to reduced synthesis and excessive consumption of coagulation factors in states of hiperclotting is characteristic of IUGR, enhances the possibility of bleeding complications and increases the risk of infections. From a clinical point of view, it is important to take into consideration the degree of intrauterine hypotrophy during the evaluation of hemostatic disorders.

  12. Oral streptococci and cardiovascular disease: searching for the platelet aggregation-associated protein gene and mechanisms of Streptococcus sanguis-induced thrombosis.

    Science.gov (United States)

    Herzberg, Mark C; Nobbs, Angela; Tao, Lin; Kilic, Ali; Beckman, Eric; Khammanivong, Ali; Zhang, Yongshu

    2005-11-01

    Pathogenic mechanisms in infective endocarditis, disseminated intravascular coagulation, and cardiovascular events involve the aggregation of platelets into thrombi. Attendant infection by oral bacteria contributes to these diseases. We have been studying how certain oral streptococci induce platelet aggregation in vitro and in vivo. Streptococcus sanguis expresses a platelet aggregation-associated protein (PAAP), which contributes little to adhesion to platelets. When specific antibodies or peptides block PAAP, S. sanguis fails to induce platelet aggregation in vitro or in vivo. We used subtractive hybridization to identify the gene encoding for PAAP. After subtraction of strain L50 (platelet aggregation-negative), four strain 133-79 specific sequences were characterized. Sequence agg4 encoded a putative collagen-binding protein (CbpA), which was predicted to contain two PAAP collagen-like octapeptide sequences. S. sanguis CbpA- mutants were constructed and tested for induction of platelet aggregation in vitro. Platelet aggregation was substantially inhibited when compared to the wild-type using platelet-rich plasma from the principal donor, but adhesion was unaffected. Other donor platelets responded normally to the CbpA- strain, suggesting additional mechanisms of response to S. sanguis. In contrast, CshA- and methionine sulfoxide reductase-negative (MsrA-) strains neither adhered nor induced platelet aggregation. CbpA was suggested to contribute to site 2 interactions in our two-site model of platelet aggregation in response to S. sanguis. Platelet polymorphisms were suggested to contribute to the thrombogenic potential of S. sanguis.

  13. Allicin and disulfiram enhance platelet integrin alphaIIbbeta3-fibrinogen binding.

    Science.gov (United States)

    Manaster, Yoav; Shenkman, Boris; Rosenberg, Nurit; Savion, Naphtali

    2009-09-01

    Activation of the platelet receptor alphaIIbbeta3 (glycoprotein IIbIIIa) involves a change in the disulfide bonds pattern in the extra-cellular domain of the receptor. The disulfide-bond reducing agent, dithiothreitol (DTT), can increase integrin activity, and point mutations of specific cysteine residues of the integrin can cause its lockage at the high affinity state. The present study is aimed to support the hypothesis that prevention of specific alphaIIbbeta3 intra-molecular disulfide bond formation increases receptor-ligand binding activity. Platelet aggregation was induced by collagen or ADP and epinephrine. Integrin alphaIIbbeta3-fibrinogen binding was evaluated on prostaglandins E(1) (PGE(1))-treated washed platelets or baby hamster kidney (BHK) cells expressing human alphaIIbbeta3. Integrin was directly activated by an anti-ligand induced binding site (LIBS) PT25-2 antibody. The effect of sulfhydryl-reactive agents, such as allicin, glutathione, dithiobis nitrobenzoic acid (DTNB) and disulfiram, was tested on alphaIIbbeta3 activity. Allicin (40 microM) completely inhibited washed platelets agonist-induced aggregation. Both allicin and disulfiram (40 microM) inhibited alphaIIbbeta3-fibrinogen binding and P-selectin expression in washed platelets. However, there was an increase in alphaIIbbeta3-fibrinogen binding but not P-selectin expression in PGE(1)-treated washed platelets activated by PT25-2 antibody. At a high concentration (400 microM) both inhibited alphaIIbbeta3-fibrinogen binding. Similarly, in BHK cells expressing alphaIIbbeta3 activated by PT25-2 antibody, allicin at a low concentration increased alphaIIbbeta3 activity. Allicin and disulfiram inhibit agonist-induced washed platelet activation probably via inhibition of platelet signaling, but enhance PT25-2 antibody-induced alphaIIbbeta3 integrin activity most likely by preventing reformation of disulfide bridges thereby stabilizing the active conformation of the integrin.

  14. Effects of antiplatelet therapy on platelet extracellular vesicle release and procoagulant activity in health and in cardiovascular disease.

    Science.gov (United States)

    Connor, David E; Ly, Ken; Aslam, Anoosha; Boland, John; Low, Joyce; Jarvis, Susan; Muller, David W; Joseph, Joanne E

    2016-12-01

    Dual antiplatelet therapy with aspirin and clopidogrel is commonly used to prevent recurrent ischemic events in patients with cardiovascular disease. Whilst their effects on platelet reactivity are well documented, it is unclear, however, whether antiplatelet therapy inhibits platelet extracellular vesicle (EV) release. The aim of this study was to investigate the effects of antiplatelet therapy on platelet EV formation and procoagulant activity. Blood samples from 10 healthy controls not receiving antiplatelet therapy were incubated in vitro with aspirin or a P2Y12 inhibitor (MeSAMP). Blood samples from 50 patients receiving long-term dual antiplatelet therapy and undergoing coronary angiography were also studied. Platelet reactivity was assessed by Multiplate™ impedance aggregometry. Platelet EV formation and procoagulant activity of pretreated and untreated blood samples in response to arachidonic acid (AA), adenosine diphosphate (ADP), ADP+PGE1, and thrombin receptor-activating peptide (TRAP) stimulation were assessed by flow cytometry and Procoag-PL assays, respectively. Incubation of normal platelets with aspirin significantly inhibited AA-induced platelet reactivity, EV formation, and procoagulant activity, whilst MeSAMP significantly inhibited platelet reactivity and EV formation in response to AA, ADP, and TRAP, but had minimal effect on procoagulant activity. Most patients receiving dual antiplatelet therapy showed an appropriate reduction in platelet reactivity in response to their treatment; however there was not complete inhibition of increased platelet and EV procoagulant activity in response to ADP, AA, or TRAP. In addition, we could not find any correlation between platelet reactivity and procoagulant activity in patients receiving dual antiplatelet therapy.

  15. Human Platelets Express Functional Thymic Stromal Lymphopoietin Receptors: a Potential Role in Platelet Activation in Acute Coronary Syndrome

    Directory of Open Access Journals (Sweden)

    Boyuan Wang

    2013-12-01

    Full Text Available Background: Thymic stromal lymphopoietin (TSLP has been shown to be expressed in various inflammatory tissues, such as human atherosclerotic plaques. Many types of myeloid cells involved in atherosclerosis, including mast cells, lymphocytes, dendritic cells and monocytes/macrophages, present TSLP receptors (TSLPR. However, it is unknown whether platelets, which also play important roles in atherothrombosis, express TSLPR. Methods and Results: We applied flow cytometry and western blotting to show that TSLPR was expressed on the surface of human platelets. Following the addition of TSLP to platelets, the expression of CD62P, CD63, PAC-1 and p-Akt as well as aggregation and ATP release were increased significantly. A TSLPR antibody and a PI3K (phosphatidylinositol 3-kinase enzyme inhibitor (LY294002 significantly inhibited the platelet activation induced by TSLP. The expression of TSLPR, CD62P and CD63 and the increment of the expression of CD62P and CD63 induced by TSLP in the acute coronary syndrome (ACS group were markedly higher than those in the control group and the stable angina pectoris (SAP group. The expression and the increment of the expression of CD62P and CD63 induced by TSLP were positively correlated with the expression of TSLPR. Conclusion: Human platelets express functional TSLPR, which can be activated by TSLP to promote platelet activation. TSLP/TSLPR functions via activating the PI3K/AKT pathway, and this signalling pathway may be one of the mechanisms involved in thrombosis in ACS. In coronary disease patients, the determination of TSLPR in platelets may help to identify the risk of ACS.

  16. Secretory products from thrombin-stimulated human platelets exert an inhibitory effect on NK-cytotoxic activity

    DEFF Research Database (Denmark)

    Skov Madsen, P; Hokland, P; Hokland, M

    1987-01-01

    We have investigated the interaction between human platelets and the NK-system, with special emphasis on the action of secretory products from platelets in an NK assay with 51Cr-labelled K562 as target cells. Supernatants from thrombin-stimulated platelets added to the NK assay consistently...... with thrombin, are capable of secreting different, yet undefined factors, which significantly inhibit NK activity in vitro. The results also suggest that the role of products from contaminating in vitro activated platelets should be borne in mind when performing conventional NK assays. Udgivelsesdato: 1986-Oct...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Immunochemical characterization of platelet-specific alloantigens

    NARCIS (Netherlands)

    Mulder, A.; van Leeuwen, E. F.; Veenboer, G. J.; Tetteroo, P. A.; von dem Borne, A. E.

    1984-01-01

    Immunoprecipitation was performed with platelet-specific alloantisera (anti-Zwa, -Zwb, -Baka and antiserum Luc) and 125I-labelled platelets of a panel of donors typed for these platelet-specific alloantigens. This was done by sensitization of intact, radiolabelled platelets with the antisera,

  20. Neonatal thrombocytopenia and platelets transfusion

    Directory of Open Access Journals (Sweden)

    Anil K Gupta

    2012-01-01

    Full Text Available Background: Neonates often develop thrombocytopenia at some time during hospital stay. Platelet transfusion are frequently given to them and are likely to result in unnecessary transfusion. Material and Methods: Thus, we analyzed thrombocytopenia in neonates, its prevalence, and relationship if any, between clinical condition and platelet transfusion in neonates, which would have been helpful in developing guidelines and/or protocols for platelet transfusion (and reducing the donor exposure in neonates. Results: A total of 870 neonates who were admitted in Neonatal Intensive Care Unit (NICU with various morbidities had platelets count done; of these, 146 (16.7% neonate revealed thrombocytopenia. Discussion: Low birth weight babies (P 0.009 and babies born with mother having hypertension (P 0.04 showed significant thrombocytopenia. Neonates with intrauterine growth retardation (IUGR diagnosed during antenatal screening showed lower platelet count (P 0.022. Neonates having associated illness, such as sepsis, gastrointestinal, and respiratory problems, and on vasopressor drugs were found to be associated with low platelet count. Conclusion: In our study, 16.40% of thrombocytopenic neonates required platelet transfusion either alone or with other blood component during their stay in NICU.

  1. miR-326 targets antiapoptotic Bcl-xL and mediates apoptosis in human platelets.

    Directory of Open Access Journals (Sweden)

    Shifang Yu

    Full Text Available Platelets play crucial roles in hemostasis, thrombosis, wound healing, inflammation, angiogenesis, and tumor metastases. Because they are anucleated blood cells, platelets lack nuclear DNA, but they do contain mitochondrial DNA, which plays a key role in regulating apoptosis. Recent evidence has suggested that miRNAs are also involved in regulating gene expression and apoptosis in platelets. Our previous study showed that the expression of miR-326 increased visibly when apheresis platelets were stored in vitro. The antiapoptotic Bcl-2 family regulator Bcl-xL has been identified as a putative target of miR-326. In the present study, dual reporter luciferase assays were used to characterize the function of miR-326 in the regulation of the apoptosis of platelet cells. These assays demonstrated that miR-326 bound to the 3'-translated region of Bcl-xL. To directly assess the functional effects of miR-326 expression, levels of Bcl-xL and the apoptotic status of stored apheresis platelets were measured after transfection of miR-326 mimic or inhibitor. Results indicated that miR-326 inhibited Bcl-xL expression and induced apoptosis in stored platelets. Additionally, miR-326 inhibited Bcl-2 protein expression and enhanced Bak expression, possibly through an indirect mechanism, though there was no effect on the expression of Bax. The effect of miR-326 appeared to be limited to apoptosis, with no significant effect on platelet activation. These results provide new insight into the molecular mechanisms affecting differential platelet gene regulation, which may increase understanding of the role of platelet apoptosis in multiple diseases.

  2. Prophylactic platelets in dengue

    DEFF Research Database (Denmark)

    Whitehorn, James; Rodriguez Roche, Rosmari; Guzman, Maria G

    2012-01-01

    Dengue is the most important arboviral infection of humans. Thrombocytopenia is frequently observed in the course of infection and haemorrhage may occur in severe disease. The degree of thrombocytopenia correlates with the severity of infection, and may contribute to the risk of haemorrhage...... of platelets in dengue. Respondents were all physicians involved with the treatment of patients with dengue. Respondents were asked that their answers reflected what they would do if they were the treating physician. We received responses from 306 physicians from 20 different countries. The heterogeneity...... of the responses highlights the variation in clinical practice and lack of an evidence base in this area and underscores the importance of prospective clinical trials to address this key question in the clinical management of patients with dengue....

  3. The origin and function of platelet glycosyltransferases

    DEFF Research Database (Denmark)

    Wandall, Hans H; Rumjantseva, Viktoria; Sørensen, Anne Louise Tølbøll

    2012-01-01

    that megakaryocytes package these Golgi-derived glycosyltransferases into vesicles that are sent via proplatelets to nascent platelets, where they accumulate. These glycosyltransferases are active, and intact platelets glycosylate large exogenous substrates. Furthermore, we show that activation of platelets results...... to function in the extracellular space. This platelet glycosylation machinery offers a pathway to a simple glycoengineering strategy improving storage of platelets and may serve hitherto unknown biological functions....

  4. 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.

  5. Effect of montelukast on platelet activating factor- and tachykinin induced mucus secretion in the rat

    Directory of Open Access Journals (Sweden)

    Groneberg David A

    2008-02-01

    Full Text Available Abstract Background Platelet activating factor and tachykinins (substance P, neurokinin A, neurokinin B are important mediators contributing to increased airway secretion in the context of different types of respiratory diseases including acute and chronic asthma. Leukotriene receptor antagonists are recommended as add-on therapy for this disease. The cys-leukotriene-1 receptor antagonist montelukast has been used in clinical asthma therapy during the last years. Besides its inhibitory action on bronchoconstriction, only little is known about its effects on airway secretions. Therefore, the aim of this study was to evaluate the effects of montelukast on platelet activating factor- and tachykinin induced tracheal secretory activity. Methods The effects of montelukast on platelet activating factor- and tachykinin induced tracheal secretory activity in the rat were assessed by quantification of secreted 35SO4 labelled mucus macromolecules using the modified Ussing chamber technique. Results Platelet activating factor potently stimulated airway secretion, which was completely inhibited by the platelet activating factor receptor antagonist WEB 2086 and montelukast. In contrast, montelukast had no effect on tachykinin induced tracheal secretory activity. Conclusion Cys-leukotriene-1 receptor antagonism by montelukast reverses the secretagogue properties of platelet activating factor to the same degree as the specific platelet activating factor antagonist WEB 2086 but has no influence on treacheal secretion elicited by tachykinins. These results suggest a role of montelukast in the signal transduction pathway of platelet activating factor induced secretory activity of the airways and may further explain the beneficial properties of cys-leukotriene-1 receptor antagonists.

  6. Microbicidal properties of Leukocyte- and Platelet-Rich Plasma/Fibrin (L-PRP/L-PRF): new perspectives.

    Science.gov (United States)

    Cieslik-Bielecka, A; Dohan Ehrenfest, D M; Lubkowska, A; Bielecki, T

    2012-01-01

    Platelets, as main actors of the first stage of the healing process, play an important role in tissue repair. Their granules contain many active substances, particularly over 30 growth factors with significant effects on the resident cells at the site of injury, such as mesenchymal stem cells, chondrocytes, fibroblasts, osteoblasts. This potential may be increased by the concentration of the platelets, using platelet-rich plasma/fibrin products. In the four families of platelet concentrates, 2 families contain also significant concentrations of leukocytes: L-PRP (Leukocyte- and Platelet-Rich Plasma) and L-PRF (Leukocyte- and Platelet-Rich Fibrin). Inductive properties of platelet concentrates were widely described. However, they present also antimicrobial effects. The antibacterial effects of L-PRP were highlighted in only a few in vitro studies. Strong activity comparable to gentamicin and oxacillin for L-PRP against methicillin susceptible Staphylococcus aureus (MSSA) was already demonstrated. L-PRP also inhibited the growth of methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli. Some authors also reported clinical observations about the reduction of infections and the induction of healing processes after the use of platelet concentrates in cardiac, orthopaedic, oral and maxillofacial surgery. However, very little is yet known about the antibacterial effects of these concentrates. In this manuscript, the current data about the antimicrobial agents and cells present in the platelet-rich plasma/fibrin are highlighted and discussed, in order to introduce this new key chapter of the platelet concentrate technology history.

  7. Deletion of GLUT1 and GLUT3 Reveals Multiple Roles for Glucose Metabolism in Platelet and Megakaryocyte Function

    Directory of Open Access Journals (Sweden)

    Trevor P. Fidler

    2017-07-01

    Full Text Available Anucleate platelets circulate in the blood to facilitate thrombosis and diverse immune functions. Platelet activation leading to clot formation correlates with increased glycogenolysis, glucose uptake, glucose oxidation, and lactic acid production. Simultaneous deletion of glucose transporter (GLUT 1 and GLUT3 (double knockout [DKO] specifically in platelets completely abolished glucose uptake. In DKO platelets, mitochondrial oxidative metabolism of non-glycolytic substrates, such as glutamate, increased. Thrombosis and platelet activation were decreased through impairment at multiple activation nodes, including Ca2+ signaling, degranulation, and integrin activation. DKO mice developed thrombocytopenia, secondary to impaired pro-platelet formation from megakaryocytes, and increased platelet clearance resulting from cytosolic calcium overload and calpain activation. Systemic treatment with oligomycin, inhibiting mitochondrial metabolism, induced rapid clearance of platelets, with circulating counts dropping to zero in DKO mice, but not wild-type mice, demonstrating an essential role for energy metabolism in platelet viability. Thus, substrate metabolism is essential for platelet production, activation, and survival.

  8. Dietary α-linolenic acid increases the platelet count in ApoE-/- mice by reducing clearance.

    Science.gov (United States)

    Stivala, Simona; Reiner, Martin F; Lohmann, Christine; Lüscher, Thomas F; Matter, Christian M; Beer, Juerg H

    2013-08-08

    Previously we reported that dietary intake of alpha-linolenic acid (ALA) reduces atherogenesis and inhibits arterial thrombosis. Here, we analyze the substantial increase in platelet count induced by ALA and the mechanisms of reduced platelet clearance. Eight-week-old male apolipoprotein E knockout (ApoE(-/-)) mice were fed a 0.21g% cholesterol diet complemented by either a high- (7.3g%) or low-ALA (0.03g%) content. Platelet counts doubled after 16 weeks of ALA feeding, whereas the bleeding time remained similar. Plasma glycocalicin and glycocalicin index were reduced, while reticulated platelets, thrombopoietin, and bone marrow megakaryocyte colony-forming units remained unchanged. Platelet contents of liver and spleen were substantially reduced, without affecting macrophage function and number. Glycoprotein Ib (GPIb) shedding, exposure of P-selectin, and activated integrin αIIbβ3 upon activation with thrombin were reduced. Dietary ALA increased the platelet count by reducing platelet clearance in the reticulo-endothelial system. The latter appears to be mediated by reduced cleavage of GPIb by tumor necrosis factor-α-converting enzyme and reduced platelet activation/expression of procoagulant signaling. Ex vivo, there was less adhesion of human platelets to von Willebrand factor under high shear conditions after ALA treatment. Thus, ALA may be a promising tool in transfusion medicine and in high turnover/high activation platelet disorders.

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Effects of tipranavir, darunavir, and ritonavir on platelet function, coagulation, and fibrinolysis in healthy volunteers.

    Science.gov (United States)

    Kort, Jens J; Aslanyan, Stella; Scherer, Joseph; Sabo, John P; Kohlbrenner, Veronika; Robinson, Patrick

    2011-06-01

    The use of HIV protease inhibitors (PIs) as part of antiretroviral therapy in the treatment of HIV-1 infection may be associated with an increased risk of bleeding. This prospective, randomized, open-label trial in healthy volunteers compared the effects of tipranavir/ritonavir (TPV/r), darunavir/ ritonavir (DRV/r), and ritonavir (RTV) alone on platelet aggregation after a single dose and at steady-state concentrations. Subjects were selected on the basis of normal platelet aggregation and arachidonic acid (AA)-induced platelet aggregation inhibition after administration of a single 325-mg dose of aspirin. All 3 PI therapies were administered twice daily for 10 days. In some but not all subjects, TPV/r inhibited AA-induced platelet aggregation and prolonged PFA-100® closure time with collagen-epinephrine cartridge, which was of lesser magnitude and consistency compared with aspirin, but greater when compared to DRV/r and RTV. At least 2 subjects in each treatment arm showed complete inhibition of AA-induced platelet aggregation on treatment, and the magnitude of change in all platelet-function tests did not correlate with PI plasma concentrations. Effects of TPV/r on platelet aggregation were reversed 24 hours after the last TPV/r dose. None of the PI treatments tested were associated with increases in bleeding time, decreases in plasma coagulation factors, or increase in fibrinolysis. There was large inter-patient variability in antiplatelet effect for all PI treatments, ranging from no effect to complete inhibition of AA-induced platelet aggregation.

  11. Genetic determinants of platelet large-cell ratio, immature platelet fraction, and other platelet-related phenotypes.

    Science.gov (United States)

    Pujol-Moix, Núria; Vázquez-Santiago, Miquel; Morera, Agnès; Ziyatdinov, Andrey; Remacha, Angel; Nomdedeu, Josep F; Fontcuberta, Jordi; Soria, José Manuel; Souto, Juan Carlos

    2015-08-01

    Platelets play a significant role in arterial thrombosis and are involved also in venous thrombosis. The genetic determinants of several platelet-related phenotypes have been studied previously. However, to the best of our knowledge, the genetic determinants of other platelet phenotypes have not been reported such as platelet-large-cell ratio (P-LCR) index, immature platelet fraction (IPF) parameters and overall platelet function measured through the PFA-100 system. As part of the GAIT-2 (Genetic Analysis of Idiopathic Thrombophilia 2) Project, 935 individuals from 35 large Spanish families, ascertained through a proband with thrombophilia, were studied. Using variance component methods, implemented in the SOLAR package, the heritability of the following sets of platelet-related phenotypes was determined: platelet count and indices, IPF, and platelet function. High heritabilities of the platelet count and index phenotypes (from 0.41 to 0.64) were found, especially for those related to platelet volume. The heritabilities of the IPF phenotypes, as a measure of platelet turnover, were the highest (from 0.65 to 0.69). The heritabilities of the platelet function phenotypes were high also (0.45 and 0.62). The covariate age influenced all of the platelet phenotypes. Smoking influenced the platelet indices related to platelet volume and all the IPF phenotypes. Venous thrombosis showed a heritability of 0.67. We did not find a genetic correlation between any of the platelet-related phenotypes and venous thrombosis. The high heritabilities found for all of the platelet phenotypes provid promising data for the identification of new genes that underly these phenotypes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Differential proteomic analysis of platelets suggested target-related proteins in rabbit platelets treated with Rhizoma Corydalis.

    Science.gov (United States)

    Li, Chun-Hong; Chen, Cen; Zhang, Qian; Tan, Chen-Ning; Hu, Yuan-Jia; Li, Peng; Wan, Jian-Bo; Feng, Gang; Xia, Zhi-Ning; Yang, Feng-Qing

    2017-12-01

    Corydalis yanhusuo W.T. Wang (Papaveraceae) (Rhizoma Corydalis) showed inhibitory effects on rabbit platelet aggregation induced by ADP, thrombin (THR) or arachidonic acid (AA). This study separates and identifies the possible target-related platelet proteins and suggests possible signal cascades of RC antiplatelet aggregation. Based on comparative proteomics, the differentially expressed platelet proteins treated before and after with 50 mg/mL RC 90% ethanol extract (for 15 min at 37 °C) were analyzed and identified by two dimensional gel electrophoresis (2-DE) and MALDI-TOF-MS/MS. To further verify the possible signalling pathways of RC antiplatelet aggregation function, the concentration of calcium (Ca2+) was measured by Fura-2/AM fluorescence (Ex 340/380 nm, Em 500 nm) (RC final concentrations of 0.0156-0.1563 mg/mL), the levels of P-selectin and cyclic guanosine monophosphate (cGMP) were quantified by ELISA (OD. 450 nm) (RC final concentrations of 0.0156-1.5625 mg/mL), and the 5-hydroxytryptamine (5-HT) level was measured using ortho-phthalaldehyde (OPT) fluorescence (Ex 340 nm, Em 470 nm) (RC final concentrations of 0.3125-1.5625 mg/mL). The expression of 52 proteins were altered in rabbit platelets after the treatment and the MALDI-TOF-MS analysis indicated that those proteins include 12 cytoskeleton proteins, 7 cell signalling proteins, 3 molecular chaperone proteins, 6 proteins related to platelet function, 16 enzymes and 7 other related proteins. Furthermore, RC extract could decrease the levels of 5-HT [inhibition rate of 96.80% (p rabbit platelets. The present study indicated that P2Y12 receptor might be one of the direct target proteins of RC in platelets. The signal cascades network of RC after binding with P2Y12 receptor is mediating Gαi proteins to activate downstream signalling pathways (AC and/or PI3K signalling pathways) for the inhibition of platelet aggregation.

  13. Platelet signaling-a primer.

    Science.gov (United States)

    Goggs, Robert; Poole, Alastair W

    2012-02-01

    To review the receptors and signal transduction pathways involved in platelet plug formation and to highlight links between platelets, leukocytes, endothelium, and the coagulation system. Original studies, review articles, and book chapters in the human and veterinary medical fields. Platelets express numerous surface receptors. Critical among these are glycoprotein VI, the glycoprotein Ib-IX-V complex, integrin α(IIb) β(3) , and the G-protein-coupled receptors for thrombin, ADP, and thromboxane. Activation of these receptors leads to various important functional events, in particular activation of the principal adhesion receptor α(IIb) β(3) . Integrin activation allows binding of ligands such as fibrinogen, mediating platelet-platelet interaction in the process of aggregation. Signals activated by these receptors also couple to 3 other important functional events, secretion of granule contents, change in cell shape through cytoskeletal rearrangement, and procoagulant membrane expression. These processes generate a stable thrombus to limit blood loss and promote restoration of endothelial integrity. Improvements in our understanding of how platelets operate through their signaling networks are critical for diagnosis of unusual primary hemostatic disorders and for rational antithrombotic drug design. © Veterinary Emergency and Critical Care Society 2012.

  14. Maternal extracellular vesicles and platelets promote preeclampsia via inflammasome activation in trophoblasts.

    Science.gov (United States)

    Kohli, Shrey; Ranjan, Satish; Hoffmann, Juliane; Kashif, Muhammed; Daniel, Evelyn A; Al-Dabet, Moh'd Mohanad; Bock, Fabian; Nazir, Sumra; Huebner, Hanna; Mertens, Peter R; Fischer, Klaus-Dieter; Zenclussen, Ana C; Offermanns, Stefan; Aharon, Anat; Brenner, Benjamin; Shahzad, Khurrum; Ruebner, Matthias; Isermann, Berend

    2016-10-27

    Preeclampsia (PE) is a placenta-induced inflammatory disease associated with maternal and fetal morbidity and mortality. The mechanisms underlying PE remain enigmatic and delivery of the placenta is the only known remedy. PE is associated with coagulation and platelet activation and increased extracellular vesicle (EV) formation. However, thrombotic occlusion of the placental vascular bed is rarely observed and the mechanistic relevance of EV and platelet activation remains unknown. Here we show that EVs induce a thromboinflammatory response specifically in the placenta. Following EV injection, activated platelets accumulate particularly within the placental vascular bed. EVs cause adenosine triphosphate (ATP) release from platelets and inflammasome activation within trophoblast cells through purinergic signaling. Inflammasome activation in trophoblast cells triggers a PE-like phenotype, characterized by pregnancy failure, elevated blood pressure, increased plasma soluble fms-like tyrosine kinase 1, and renal dysfunction. Intriguingly, genetic inhibition of inflammasome activation specifically in the placenta, pharmacological inhibition of inflammasome or purinergic signaling, or genetic inhibition of maternal platelet activation abolishes the PE-like phenotype. Inflammasome activation in trophoblast cells of women with preeclampsia corroborates the translational relevance of these findings. These results strongly suggest that EVs cause placental sterile inflammation and PE through activation of maternal platelets and purinergic inflammasome activation in trophoblast cells, uncovering a novel thromboinflammatory mechanism at the maternal-embryonic interface. © 2016 by The American Society of Hematology.

  15. The effects of aminoglycoside antibiotics on platelet aggregation and blood coagulation.

    Science.gov (United States)

    Chen, Guoqiang; Fei, Xianming; Ling, Jie

    2012-09-01

    To investigate the effects of different aminoglycoside antibiotics on platelet aggregation and blood coagulation, as well as the underlying mechanisms. Blood samples were collected and prepared as platelet-rich plasma and platelet-poor plasma samples. Then assigned into different groups for the following antibiotics treatments: gentamicin, streptomycin, etimicin, amikacin, and kanamycin, as group 0 mg/L, group 30 mg/L, group 91mg/L, and group 910 mg/L for each drugs. The maximum platelet aggregation rate induced by adenosine diphosphate, expression levels of CD62p and FIB-R, prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen were measured. The sodium citrate and sodium heparin were used in whole blood tests for the whole blood coagulation time as well as the Ca(2+) in blood plasma. Amikacin and gentamicin could inhibit the aggregation of platelets, which contributed to the whole blood clotting disorder. Amikacin and gentamicin might inhibit the platelet aggregation by blocking the activation and release of FIB-R or probably the inhibition of endogenous clotting factor as well. This effect was not dependent on calcium ions.

  16. Thromboelastograph with Platelet Mapping(TM) predicts postoperative chest tube drainage in patients undergoing coronary artery bypass grafting.

    Science.gov (United States)

    Chowdhury, Mohsin; Shore-Lesserson, Linda; Mais, Alec M; Leyvi, Galina

    2014-04-01

    The goal of this study was to evaluate the ability of Thromboelastograph with Platelet Mapping (TEG-PM(TM)) to predict postoperative bleeding tendency in patients with a history of recent anti-platelet therapy undergoing coronary artery bypass grafting (CABG). A retrospective analysis. Association between predictor variables (MAADP [maximum amplitude produced by adenosine diphosphate], MAAA [maximum amplitude produced by arachidonic acid], percent of platelets inhibited by clopidogrel, percent of platelets inhibited by aspirin) and the outcomes as elevated chest tube drainage (CTD) and blood transfusion were investigated by logistic regression model. CTD was considered elevated if it was ≥ 600 mL within 12 hours after surgery. A university hospital. Patients on antiplatelet therapy scheduled to undergo CABG that had TEG-PM(TM) done as a point-of-care test. None. A total of 78 patients had preoperative TEG-PM(TM) test and on-pump CABG surgeries performed on the same day. Among them, 20 patients (25.6%) had elevated CTD. Decreased MAADP (odds ratio [OR] 0.94), increased percent inhibition of platelets by clopidogrel (OR 1.03), and lower body mass index (BMI) (OR 0.78) were significantly associated with elevated CTD. The same parameters were also associated with platelets transfusion: MAADP (OR 0.94), percent of inhibition of platelets by clopidogrel (OR 1.03) and BMI (OR 0.77). TEG-PM(TM) parameters and BMI are predictive of elevated CTD and platelets transfusion. A 1 mm decrease in MAADP increases the likelihood of elevated CTD and the likelihood of platelets transfusion by 6% whereas 1 unit decrease in BMI is associated with an increased likelihood of elevated CTD and platelets transfusion by 22% and 23% respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Interactions of gallic acid, resveratrol, quercetin and aspirin at the platelet cyclooxygenase-1 level. Functional and modelling studies.

    Science.gov (United States)

    Crescente, Marilena; Jessen, Gisela; Momi, Stefania; Höltje, Hans-Dieter; Gresele, Paolo; Cerletti, Chiara; de Gaetano, Giovanni

    2009-08-01

    While resveratrol and quercetin possess antiplatelet activity, little is known on the effect of gallic acid on platelets. We studied the interactions of these three different polyphenols among themselves and with aspirin, at the level of platelet cyclooxygenase-1 (COX-1). Both functional (in vitro and in vivo) and molecular modelling approaches were used. All three polyphenols showed comparable antioxidant activity (arachidonic acid [AA]-induced intraplatelet ROS production); however, resveratrol and quercetin, but not gallic acid, inhibited AA-induced platelet aggregation. Gallic acid, similarly to salicylic acid, the major aspirin metabolite, prevented inhibition of AA-induced platelet function by aspirin but, at variance with salicylic acid, also prevented inhibition by the other two polyphenols. Molecular modelling studies, performed by in silico docking the polyphenols into the crystal structure of COX-1, suggested that all compounds form stable complexes into the COX-1 channel, with slightly different but functionally relevant interaction geometries. Experiments in mice showed that gallic acid administered before aspirin, resveratrol or quercetin fully prevented their inhibitory effect on serum TxB(2). Finally, a mixture of resveratrol, quercetin and gallic acid, at relative concentrations similar to those contained in most red wines, did not inhibit platelet aggregation, but potentiated sub-inhibitory concentrations of aspirin. Gallic acid interactions with other polyphenols or aspirin at the level of platelet COX-1 might partly explain the complex, and possibly contrasting, effects of wine and other components of the Mediterranean diet on platelets and on the pharmacologic effect of low-dose aspirin.

  18. Platelet CD40 Mediates Leukocyte Recruitment and Neointima Formation after Arterial Denudation Injury in Atherosclerosis-Prone Mice.

    Science.gov (United States)

    Jin, Rong; Xiao, Adam Y; Song, Zifang; Yu, Shiyong; Li, Jarvis; Cui, Mei-Zhen; Li, Guohong

    2018-01-01

    The role of platelets in the development of thrombosis and abrupt closure after angioplasty is well recognized. However, the direct impact of platelets on neointima formation after arterial injury remains undetermined. Herein, we show that neointima formation after carotid artery wire injury reduces markedly in CD40-/- apolipoprotein E-deficient (apoE-/-) mice but only slightly in CD40 ligand-/-apoE-/- mice, compared with apoE-/- mice. Wild-type and CD40-deficient platelets were isolated from blood of apoE-/- and CD40-/-apoE-/- mice, respectively. The i.v. injection of thrombin-activated platelets into CD40-/-apoE-/- mice was performed every 5 days, starting at 2 days before wire injury. Injection of wild-type platelets promoted neointima formation, which was associated with increased inflammation by stimulating leukocyte recruitment via up-regulation of circulating platelet surface P-selectin expression and the formation of platelet-leukocyte aggregates. It was also associated with further promoting the luminal deposition of platelet-derived regulated on activation normal T cell expressed and secreted/chemokine (C-C motif) ligand 5 and expression of monocyte chemoattractant protein-1 and vascular cell adhesion molecule 1 in wire-injured carotid arteries. Remarkably, all these inflammatory actions by activated platelets were abrogated by lack of CD40 on injected platelets. Moreover, injection of wild-type platelets inhibited endothelial recovery in wire-injured carotid arteries, but this effect was also abrogated by lack of CD40 on injected platelets. Results suggest that platelet CD40 plays a pivotal role in neointima formation after arterial injury and might represent an attractive target to prevent restenosis after vascular interventions. Copyright © 2018 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  19. A megakaryocyte with no platelets: anti-platelet antibodies, apoptosis, and platelet production.

    Science.gov (United States)

    Perdomo, José; Yan, Feng; Chong, Beng H

    2013-01-01

    Primary immune thrombocytopenia (ITP) and drug-induced thrombocytopenia (DITP) are disorders caused primarily by the presence of anti-platelet auto-antibodies (Abs). Hematologists have traditionally seen thrombocytopenia as the result of increased destruction of Ab-coated platelets by the reticuloendothelial system. While accurate, this approach does not fully account for other laboratory observations. There is increasing evidence suggesting a significant cellular component in the etiology of both ITP and DITP. In ITP, megakaryocytes (Mks) show characteristics consistent with increased apoptosis, which correlates with a reduction in platelet production capacity. Platelet production by Mks is impaired in both the bone marrow of ITP patients and in Mks produced in vitro when treated with ITP or DITP auto-Abs. Recently, it was shown that anti GPIb/IX DITP Abs act directly on Mks and induce apoptosis, hinder differentiation, and prevent platelet production. The origin of pathological megakaryocytic apoptosis is yet to be explored in more detail but current observations imply that there is a direct contribution by anti-platelet Abs. Here we review the evidence for Ab-mediated megakaryocytic damage in ITP and DITP, examine possible molecular mechanisms and consider potential clinical implications.

  20. Platelet-interactive products of Streptococcus sanguis protoplasts.

    Science.gov (United States)

    Herzberg, M C; Erickson, P R; Kane, P K; Clawson, D J; Clawson, C C; Hoff, F A

    1990-01-01

    To isolate a more native, platelet-interactive macromolecule (class II antigen) of Streptococcus sanguis, cultured protoplasts were used as a source. Protoplasts were optimally prepared from fresh washed cells by digestion with 80 U of mutanolysin per ml for 75 min at 37 degrees C while osmotically stabilized in 26% (wt/vol) raffinose. Osmotically stabilized forms were surrounded by a 9-nm bilaminar membrane, as shown by transmission electron microscopy. Protoplasts were cultured in chemically defined synthetic medium and osmotically stabilized by ammonium chloride. Spent culture media were harvested daily for 7 days. Each day, soluble proteins were isolated from media, preincubated with platelet-rich plasma, and tested for inhibition of platelet aggregation induced by S. sanguis cells. Products released from S. sanguis protoplasts and reactive with an anti-class II antigen immunoaffinity matrix were able to inhibit S. sanguis-induced platelet aggregation. As resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, anti-class II-reactive protoplast products included silver-stained bands of 67, 79, 115, 216, and 248 kDa. The 115-kDa protein fraction was isolated by gel filtration and ion-exchange chromatography. This form of the class II antigen contained N-formylmethionine at its amino terminus. Rhamnose constituted 18.2% of the total residual dry weight and nearly half of its carbohydrate content. Diester phosphorus constituted 1% of this fraction. After trypsinization of the protoplast products from either preparation, a 65-kDa protein fragment was recovered. This protoplast protein fragment and the S. sanguis cell-derived 65-kDa class II antigen, previously implicated in the induction of platelet aggregation, were shown to be functionally and immunologically identical. Images PMID:2254032

  1. Platelets and infection — an emerging role of platelets in viral infection

    Directory of Open Access Journals (Sweden)

    Alice eAssinger

    2014-12-01

    Full Text Available Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts (thrombocytosis are associated with increased risk of thrombotic complications, low platelet counts (thrombocytopenia and several platelet function disorders increase the risk of bleeding. Over the last years more and more evidence has emerged that platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients.Viral infections often coincide with platelet activation. Host inflammatory responses result in the release of platelet activating mediators and a pro-oxidative and pro-coagulant environment, which favours platelet activation. However, viruses can also directly interact with platelets and megakaryocytes and modulate their function. Furthermore, platelets can be activated by viral antigen-antibody complexes and in response to some viruses B-lymphocytes also generate anti-platelet antibodies.All these processes contributing to platelet activation result in increased platelet consumption and removal and often lead to thrombocytopenia, which is frequently observed during viral infection. However, virus-induced platelet activation does not only modulate platelet count, but also shapes immune responses. Platelets and their released products have been reported to directly and indirectly suppress infection and to support virus persistence in response to certain viruses, making platelets a double-edged sword during viral infections. This review aims to summarize the current knowledge on platelet interaction with different types of viruses, the viral impact on platelet activation and platelet-mediated modulations of innate and adaptive immune responses.

  2. Cellular pathology of atherosclerosis: smooth muscle cells promote adhesion of platelets to cocultured endothelial cells.

    Science.gov (United States)

    Tull, Samantha P; Anderson, Steve I; Hughan, Sascha C; Watson, Steve P; Nash, Gerard B; Rainger, G Ed

    2006-01-06

    Although platelets do not ordinarily bind to endothelial cells (EC), pathological interactions between platelets and arterial EC may contribute to the propagation of atheroma. Previously, in an in vitro model of atherogenesis, where leukocyte adhesion to EC cocultured with smooth muscle cells was greatly enhanced, we also observed attachment of platelets to the EC layer. Developing this system to specifically model platelet adhesion, we show that EC cocultured with smooth muscle cells can bind platelets in a process that is dependent on EC activation by tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta1. Recapitulating the model using EC alone, we found that a combination of TGF-beta1 and TNF-alpha promoted high levels of platelet adhesion compared with either agent used in isolation. Platelet adhesion was inhibited by antibodies against GPIb-IX-V or alpha(IIb)beta3 integrin, indicating that both receptors are required for stable adhesion. Platelet activation during interaction with the EC was also essential, as treatment with prostacyclin or theophylline abolished stable adhesion. Confocal microscopy of the surface of EC activated with TNF-alpha and TGF-beta1 revealed an extensive matrix of von Willebrand factor that was able to support the adhesion of flowing platelets at wall shear rates below 400 s(-1). Thus, we have demonstrated a novel route of EC activation which is relevant to the atherosclerotic microenvironment. EC activated in this manner would therefore be capable of recruiting platelets in the low-shear environments that commonly exist at points of atheroma formation.

  3. Discharge aspirin dose and clinical outcomes in patients with acute coronary syndromes treated with prasugrel versus clopidogrel: an analysis from the TRITON-TIMI 38 study (trial to assess improvement in therapeutic outcomes by optimizing platelet inhibition with prasugrel-thrombolysis in myocardial infarction 38).

    Science.gov (United States)

    Kohli, Payal; Udell, Jacob A; Murphy, Sabina A; Cannon, Christopher P; Antman, Elliott M; Braunwald, Eugene; Wiviott, Stephen D

    2014-01-28

    The goal of this study was to determine whether there is a relationship between aspirin dose and the potent antiplatelet agent prasugrel in the TRITON-TIMI 38 (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel-Thrombolysis In Myocardial Infarction 38) study. Optimal aspirin dosing after acute coronary syndromes remains uncertain. Previous studies have raised questions regarding an interaction between high-dose aspirin and the potent antiplatelet agent ticagrelor. In TRITON-TIMI 38, we classified 12,674 patients into low-dose (TIMI major bleeding = 1.40 [95% CI 0.81 to 2.42] and TIMImajor bleeding = 1.30 [95% CI 0.63 to 2.68], respectively; p value for interaction = 0.84) compared with clopidogrel. In TRITON-TIMI 38, the safety and efficacy outcomes of prasugrel compared with those of clopidogrel were directionally consistent regardless of aspirin dose, although only the primary efficacy endpoint achieved statistical significance. There was no clinically meaningful interaction of aspirin with prasugrel, suggesting that previous observations with potent antiplatelet agents indicating differential results are not universal. (A Comparison of Prasugrel [CS-747] and Clopidogrel in Acute Coronary Syndrome Subjects Who Are to Undergo Percutaneous Coronary Intervention; NCT00097591). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

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

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

    2009-09-01

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

  5. Dose-effect and metabolism of docosahexaenoic acid: pathophysiological relevance in blood platelets.

    Science.gov (United States)

    Lagarde, M; Calzada, C; Guichardant, M; Véricel, E

    2013-01-01

    Docosahexaenoic acid (DHA) is known as a major nutrient from marine origin. Considering its beneficial effect in vascular risk prevention, the effect of DHA on blood components, especially platelets, will be reviewed here. Investigating the dose-effect of DHA in humans shows that daily intake lower than one gram/day brings several benefits, such as inhibition of platelet aggregation, resistance of monocytes against apoptosis, and reinforced antioxidant status in platelets and low-density lipoproteins. However, higher daily intake may be less efficient on those parameters, especially by losing the antioxidant effect. On the other hand, a focus on the inhibition of platelet aggregation by lipoxygenase end-products of DHA is made. The easy conversion of DHA by lipoxygenases and the formation of a double lipoxygenation product named protectin DX, reveal an original way for DHA to contribute in platelet inhibition through both the cyclooxygenase inhibition and the antagonism of thromboxane A₂ action. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Inhibitory effect by new monocyclic 4-alkyliden-beta-lactam compounds on human platelet activation.

    Science.gov (United States)

    Pavanetto, Martina; Zarpellon, Alessandro; Giacomini, Daria; Galletti, Paola; Quintavalla, Arianna; Cainelli, Gianfranco; Folda, Alessandra; Scutari, Guido; Deana, Renzo

    2007-08-01

    In the present study some new beta-lactam compounds were screened for their ability to inhibit human platelet activation. In particular four compounds differing in the group on the nitrogen atom of the azetidinone ring were investigated. A beta-lactam having an ethyl 2-carboxyethanoate N-bound group was demonstrated to inhibit, in the micromolar range, both the Ca(2+) release from endoplasmic reticulum, induced either by thrombin or by the ATPase inhibitor thapsigargin, and the Ca(2+) entry in platelets driven by emptying the endoplasmic reticulum. The compound also inhibited the platelet aggregation induced by a variety of physiological agonists including ADP, collagen, thrombin and thrombin mimetic peptide TRAP. The beta-lactam reduced the phosphorylation of pleckstrin (apparent MW 47 kDa), elicited by thrombin but not by the protein kinase C activator phorbol ester. Accordingly it did not significantly affect the aggregation evoked by phorbol ester or Ca(2+) ionophore. It was concluded that the beta-lactam likely exerts its anti-platelet-activating action by hampering the agonist induced cellular Ca(2+) movements. The beta-lactam concentration, which significantly inhibited platelet activation, only negligibly affected the cellular viability. Even if it is still premature to draw definitive conclusions, the present results suggest that this new compound might constitute a tool of potential clinical interest and the starting-point for the synthesis of new more beneficial anti-thrombotic compounds.

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

    Directory of Open Access Journals (Sweden)

    Nauder Faraday

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

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

    Science.gov (United States)

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

    2014-01-01

    The aggregation of platelets on the plaque rupture site on the coronary artery is reported to cause both acute coronary syndromes (ACS) and acute myocardial infarction (AMI). While the inhibition of platelet aggregation by acetyl salicylic acid was reported to produce beneficial effects in ACS, it failed to do in AMI. The concentration of a stress induced protein (dermcidin isoform-2) was much higher in AMI than that in ACS. Incubation of normal platelet rich plasma (PRP) with dermcidin showed one high affinity (Kd = 40 nM) and one low affinity binding sites (Kd = 333 nM). When normal PRP was incubated with 0.4 μM dermcidin, the platelets became resistant to the inhibitory effect of aspirin similar to that in the case of AMI. Incubation of PRP from AMI with dermcidin antibody restored the sensitivity of the platelets to the aspirin effect. Incubation of AMI PRP pretreated with 15 μM aspirin, a stimulator of the NO synthesis, resulted in the increased production of NO in the platelets that removed the bound dermcidin by 40% from the high affinity binding sites of AMI platelets. When the same AMI PRP was retreated with 10 μM aspirin, the aggregation of platelets was completely inhibited by NO synthesis. PMID:25055737

  9. Effects of 9,12,15-octadecatrien-6-ynoic acid on the metabolism of arachidonic acid in platelets and on the platelet aggregation.

    Science.gov (United States)

    Guichardant, M; Michel, M; Borel, C; Fay, L; Crozier, G; Magnolato, D; Finot, P A

    1992-01-01

    An acetylenic fatty acid: 9,12,15-octadecatrien-6-ynoic acid (dicranin), extracted from Dicranum Scoparium was preincubated with platelets stimulated by exogenous arachidonic acid (20:4 n-6). Dicranin (10(-4) M) weakly inhibited the cyclooxygenase activity as assessed by measurement of 12-hydroxy-heptadecatrienoic acid (HHT) In contrast, the 12-hydroxy-eicosatetraenoic acid (12-HETE) synthesized by the 12-lipoxygenase was strongly increased by about 650%. The same effects were observed with 10(-6) M of dicranin but to a lesser extent. The main platelet hydroxylated dicranin metabolite determined by GC-MS was a 13-hydroxy derivative Platelet aggregation induced either by thrombin or by arachidonic acid or by U46619, an structural PGH2 analogue was inhibited by 10(-4) M of dicranin.

  10. Ex vivo recapitulation of trauma-induced coagulopathy and assessment of trauma patient platelet function under flow using microfluidic technology

    Science.gov (United States)

    Li, Ruizhi; Elmongy, Hanna; Sims, Carrie; Diamond, Scott L.

    2015-01-01

    Background Relevant to trauma induced coagulopathy (TIC) diagnostics, microfluidic assays allow controlled hemodynamics for testing of platelet and coagulation function using whole blood. Methods Hemodilution or hyperfibrinolysis was studied under flow with modified healthy whole blood. Furthermore, platelet function was also measured using whole blood from trauma patients admitted to a Level 1 Trauma center. Platelet deposition was measured with PPACK-inhibited blood perfused over collagen surfaces at a wall shear rate of 200 s−1, while platelet/fibrin deposition was measured with corn trypsin inhibitor (CTI)-treated blood perfused over TF/collagen. Results In hemodilution studies, PPACK-treated blood displayed almost no platelet deposition when diluted to 10% Hct with saline, platelet poor plasma (PPP), or platelet rich plasma (PRP). Using similar dilutions, platelet/fibrin deposition was essentially absent for CTI-treated blood perfused over TF/collagen. To mimic hyperfibrinolysis during trauma, exogenous tPA (50 nM) was added to blood prior to perfusion over TF/collagen. At both venous and arterial flows, the generation and subsequent lysis of fibrin was detectable within 6 min, with lysis blocked by addition of the plasmin inhibitor, ε-aminocaproic acid. Microfluidic assay of PPACK-inhibited whole blood from trauma patients revealed striking defects in collagen response and secondary platelet aggregation in 14 of 21 patients, while platelet hyperfunction was detected in 3 of 20 patients. Conclusions Rapid microfluidic detection of (i) hemodilution-dependent impairment of clotting, (ii) clot instability due to lysis, (iii) blockade of fibrinolysis, or (iv) platelet dysfunction during trauma may provide novel diagnostic opportunities to predict TIC risk. Level of Evidence Level IV Study type Diagnostic Test PMID:27082706

  11. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress

    Science.gov (United States)

    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  12. TRA-418, a novel compound having both thromboxane A(2) receptor antagonistic and prostaglandin I(2) receptor agonistic activities: its antiplatelet effects in human and animal platelets.

    Science.gov (United States)

    Yamada, N; Miyamoto, M; Isogaya, M; Suzuki, M; Ikezawa, S; Ohno, M; Otake, A; Umemura, K

    2003-08-01

    TRA-418 is a novel compound that has been found in our screening for compounds having both thromboxane A2 (TP) receptor antagonistic and prostaglandin I2 (IP) receptor agonistic activities. In the binding assays, TRA-418 showed a 10-f