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Sample records for dual platelet inhibition

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

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    Lorenz Reinhard

    2010-05-01

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

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

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    Won Jun Oh

    2012-01-01

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

  3. Platelets Inhibit Migration of Canine Osteosarcoma Cells.

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    Bulla, S C; Badial, P R; Silva, R C; Lunsford, K; Bulla, C

    2017-01-01

    The interaction between platelets and tumour cells is important for tumour growth and metastasis. Thrombocytopenia or antiplatelet treatment negatively impact on cancer metastasis, demonstrating potentially important roles for platelets in tumour progression. To our knowledge, there is no information regarding the role of platelets in cancer progression in dogs. This study was designed to test whether canine platelets affected the migratory behaviour of three canine osteosarcoma cell lines and to give insights of molecular mechanisms. Intact platelets, platelet lysate and platelet releasate inhibited the migration of canine osteosarcoma cell lines. Addition of blood leucocytes to the platelet samples did not alter the inhibitory effect on migration. Platelet treatment also significantly downregulated the transcriptional levels of SNAI2 and TWIST1 genes. The interaction between canine platelets or molecules released during platelet activation and these tumour cell lines inhibits their migration, which suggests that canine platelets might antagonize metastasis of canine osteosarcoma. This effect is probably due to, at least in part, downregulation of genes related to epithelial-mesenchymal transition. Copyright © 2016. Published by Elsevier Ltd.

  4. Mapuche herbal medicine inhibits blood platelet aggregation.

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    Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

    2012-01-01

    12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H(2)O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H(2)O) were substantial and confirmed by inhibition of platelet surface activation markers.

  5. Mapuche Herbal Medicine Inhibits Blood Platelet Aggregation

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    Susan Skanderup Falkenberg

    2012-01-01

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

  6. Perioperative platelet inhibition in transurethral interventions: TURP/TURB

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    Michael Wenders

    2012-10-01

    Full Text Available PURPOSE: To determine whether transurethral surgery under platelet inhibition is a feasible procedure. Before transurethral resection of prostate (TURP or bladder tumours (TURB, the administration of platelet-inhibiting medication is often interrupted due to possible bleeding complications. We studied the performance of TURP and TURB under the current recommendations of the American College of Chest Physicians (ACCP on perioperative platelet inhibition. MATERIALS AND METHODS: Patients assigned for transurethral intervention were preoperatively divided into the following risk groups: low, medium and high cardio- or cerebrovascular risk. In patients with a low-risk profile, acetylsalicylic acid (ASA was discontinued. Patients of the medium risk group continued taking 100 mg of ASA. Patients of the high-risk group receiving dual platelet inhibition (ASA + clopidogrel were not treated operatively. In total 346 patients from the low and medium risk groups underwent transurethral intervention. RESULTS: Forty-two out of 198 TURP were performed under 100 mg of ASA. Without ASA, a significantly shorter length of stay and earlier removal of the transurethral catheter was documented. In the parameters postoperative haemorrhage and operative revision, no significant differences were observed. Thirty-two out of 148 TURB were performed under 100 mg of ASA. Regarding the length of stay, time until catheter removal, postoperative haemorrhage and operative revision, no significant differences were found under ASA. Only significantly longer continuous irrigation was documented under ASA. CONCLUSION: In the case of a verified indication for use of platelet inhibitors, it is possible to avoid discontinuation and the consequent increased risk of thromboembolic incidents in transurethral surgery is admissible.

  7. Postmenopausal women have an increased maximal platelet reactivity compared to men despite dual antiplatelet therapy.

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    Bobbert, Peter; Stellbaum, Caroline; Steffens, Daniel; Schütte, Claudia; Bobbert, Thomas; Schultheiss, Heinz Peter; Rauch, Ursula

    2012-12-01

    Dual antiplatelet medication with acetylsalicylic acid (ASA) and clopidogrel is the main therapy for patients with stable coronary vessel disease (CVD) after percutaneous coronary intervention (PCI). Despite platelet inhibition subgroups of patients have been shown to exhibit an increase of risk for adverse cardiovascular events. The aim of our study was to elucidate the influence of sex on platelet reactivity in patients with CVD under medication with ASA and clopidogrel. Two hundred and thirty patients with CVD on combined therapy with ASA (100 mg/day) and clopidogrel (75 mg/day) were included into our study. These patients were divided into a male (n = 128) and female (n = 102) group. Platelet reactivity was assessed by impedance aggregometry. Women demonstrated a significantly higher thrombin receptor-activating peptide (TRAP)-induced platelet reactivity than men (male 79.43 ± 28.55 U vs. female 89.3 ± 30.69 U; P 0.05) or arachidonic acid-induced (male 10.3 ± 12.87 U vs. female 12.76 ± 14.44 U; P > 0.05) platelet aggregation did not differ significantly between women and men. A multivariate linear regression model revealed female sex to be a significant prognostic marker for an increased TRAP-induced platelet reactivity, independent of the ASA and clopidogrel-associated platelet function inhibition. Sex differences did not influence the effectiveness of ASA or clopidogrel-mediated platelet function inhibition. Nevertheless, women had a significantly increased maximal platelet reactivity compared to men despite antiplatelet therapy.

  8. Kaempferol inhibits thrombosis and platelet activation.

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

    2015-08-01

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

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

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    Sirada Srihirun

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

  10. Differential effects of platelets and platelet inhibition by ticagrelor on TLR2- and TLR4-mediated inflammatory responses

    NARCIS (Netherlands)

    Tunjungputri, R.N.; Ven, A.J.A.M. van der; Riksen, N.P.; Rongen, G.A.P.J.M.; Tacke, S.; Berg, T.N.A. van den; Fijnheer, R.; Gomes, M.E.; Dinarello, C.A.; Veerdonk, F.L. van de; Gasem, M.H.; Netea, M.G.; Joosten, L.A.B.; Groot, P.G. de; Mast, Q. de

    2015-01-01

    Platelets and platelet-monocyte interaction play an important role in inflammation. Both pro- and anti-inflammatory effects of platelet inhibition have been reported in animal models. This study aimed to investigate the effect of platelets and platelet inhibition by the new P2Y12 receptor antagonist

  11. A platelet monoclonal antibody inhibition assay for detection of glycoprotein IIb/IIIa-related platelet alloantibodies.

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

    1995-08-18

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

  12. Novel Bioactivity of Ellagic Acid in Inhibiting Human Platelet Activation

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    Yi Chang

    2013-01-01

    Full Text Available Pomegranates are widely consumed either as fresh fruit or in beverage form as juice and wine. Ellagic acid possesses potent antioxidative properties; it is known to be an effective phytotherapeutic agent with antimutagenic and anticarcinogenic qualities. Ellagic acid (20 to 80 μM exhibited a potent activity in inhibiting platelet aggregation stimulated by collagen; however, it did not inhibit platelet aggregation stimulated by thrombin, arachidonic acid, or U46619. Treatment with ellagic acid (50 and 80 μM significantly inhibited platelet activation stimulated by collagen; this alteration was accompanied by the inhibition of relative [Ca2+]i mobilization, and the phosphorylation of phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinases (MAPKs, and Akt, as well as hydroxyl radical (OH● formation. In addition, ellagic acid also inhibited p38 MAPK and Akt phosphorylation stimulated by hydrogen peroxide. By contrast, ellagic acid did not significantly affect PKC activation and platelet aggregation stimulated by PDBu. This study is the first to show that, in addition to being considered a possible agent for preventing tumor growth, ellagic acid possesses potent antiplatelet properties. It appears to initially inhibit the PLCγ2-PKC cascade and/or hydroxyl radical formation, followed by decreased phosphorylation of MAPKs and Akt, ultimately inhibiting platelet aggregation.

  13. Platelets may inhibit leucotriene biosynthesis by human neutrophils at the integrin level.

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    Chabannes, Bernard; Moliere, Patrick; Merhi-Soussi, Faten; Poubelle, Patrice E; Lagarde, Michel

    2003-04-01

    Polymorphonuclear leucocytes and blood platelets co-operate in several pathophysiological processes, and arachidonic acid (AA) metabolites produced in response to the activation of these cells are potent mediators of their functions. We studied the role of platelets in the formation of 5-lipoxygenase products from AA by autologous neutrophils, especially the chemotactic agent leucotriene (LT) B4. The formation of all products, namely 5-hydroxy-eicosatetraenoic acid (5-HETE), LTB4 and the other LTA4-derived metabolites, in response to the calcium ionophore A23187 was evaluated by high-performance liquid chromatography. All the 5-lipoxygenase products were significantly diminished by physiological concentrations of platelets. This inhibitory effect was lost when platelets were previously degranulated by thrombin in non-aggregating conditions. Peptides containing the Arg-Gly-Asp-Ser or His-His-Leu-Gly-Gly-Ala-Lys-Gln-Ala-Gly-Asp-Val sequence, which prevent the adhesion of platelets to neutrophils via the fibrinogen released from platelet granules and the integrin glycoprotein IIb/IIIa, markedly decreased the inhibitory effect of non-degranulated platelets. The production of transcellular metabolites of AA such as LTC4, the dual 5- and 12-lipoxygenase product 5,12-diHETE and lipoxins could not account for the decreased formation of 5-HETE and LTA4-derived metabolites. It is concluded that platelets may inhibit the neutrophil 5-lipoxygenase activity at the integrin level and in turn may play a role in slowing down the production of LTB4 in the course of inflammation.

  14. Alcohol and polyphenolic grape extract inhibit platelet adhesion in flowing blood

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    de Lange, DW; Scholman, WLG; Kraaijenhagen, RJ; Akkerman, JWN; van de Wiel, A

    2004-01-01

    Background Moderate and prolonged alcohol consumption has been associated with decreased cardiovascular morbidity and mortality. Inhibition of platelet function in suspension attributes to these effects. Whether alcohol, red wine, or polyphenolic grape extracts (PGE) inhibit platelet adhesion is not

  15. Comparison of on-treatment platelet reactivity between triple antiplatelet therapy with cilostazol and standard dual antiplatelet therapy in patients undergoing coronary interventions: a meta-analysis.

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    Panchal, Hemang B; Shah, Tejaskumar; Patel, Parthavkumar; Albalbissi, Kais; Molnar, Janos; Coffey, Brandon; Khosla, Sandeep; Ramu, Vijay

    2013-11-01

    The recent literature has shown that triple antiplatelet therapy with cilostazol in addition to the standard dual antiplatelet therapy with aspirin and clopidogrel may reduce platelet reactivity and improve clinical outcomes following percutaneous coronary intervention. The purpose of this meta-analysis is to compare the efficacy of triple antiplatelet therapy and dual antiplatelet therapy in regard to on-treatment platelet reactivity. Nine studies (n = 2179) comparing on-treatment platelet reactivity between dual antiplatelet therapy (n = 1193) and triple antiplatelet therapy (n = 986) in patients undergoing percutaneous coronary intervention were included. Primary end points were P2Y12 reaction unit (PRU) and platelet reactivity index (PRI). Secondary end points were platelet aggregation with adenosine diphosphate (ADP) 5 and 20 µmol/L and P2Y12% inhibition. Mean difference (MD) and 95% confidence intervals (CI) were computed and 2-sided α error antiplatelet therapy, triple antiplatelet therapy had significantly lower maximum platelet aggregation with ADP 5 µmol/L (MD: -14.4, CI: -21.6 to -7.2, P antiplatelet therapy significantly lowers platelet reactivity and may explain a decrease in thromboembolic events following coronary intervention; however, additional studies evaluating clinical outcomes will be helpful to determine the benefit of triple antiplatelet therapy.

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

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

    1988-01-01

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

  17. Human platelets inhibit liver fibrosis in severe combined immunodeficiency mice

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    Takahashi, Kazuhiro; Murata, Soichiro; Fukunaga, Kiyoshi; Ohkohchi, Nobuhiro

    2013-01-01

    concentration of mouse TGF-β in the liver tissue was significantly lower in the hPLT group than in the PBS group (22 ± 5 ng/g liver vs 39 ± 6 ng/g liver, P = 0.02). Phosphorylation of Met was more prevalent in the hPLT group than in the PBS group (37% ± 4%/GAPDH vs 20% ± 8%/GAPDH, P = 0.03). Phosphorylation of SMAD3 was weaker in the hPLT group than in the PBS group (60% ± 12%/GAPDH vs 84% ± 12%/GAPDH, P = 0.1), although this difference was not significant. Furthermore, a lower rate of hepatocyte apoptosis was observed in the hPLT group than in the PBS group (5.9% ± 1.7% vs 2.9% ± 2.1%, P = 0.02). Significant human platelet accumulation was observed in the fibrotic liver tissues, whereas few platelets accumulated in the normal liver. CONCLUSION: Human platelets inhibit liver fibrosis in SCID mice. Increased concentration of HGF in the liver suppresses hepatic stellate cell activation, induces MMPs, and inhibits hepatocyte apoptosis. PMID:23983427

  18. Dual role of IL-21 in megakaryopoiesis and platelet homeostasis.

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    Benbarche, Salima; Strassel, Catherine; Angénieux, Catherine; Mallo, Léa; Freund, Monique; Gachet, Christian; Lanza, François; de la Salle, Henri

    2017-01-05

    Gene profiling studies have indicated that in vitro differentiated human megakaryocytes express the receptor for IL-21 (IL-21R), an immunostimulatory cytokine associated with inflammatory disorders and currently under evaluation in cancer therapy. The aim of this study was to investigate whether IL-21 modulates megakaryopoiesis. We first checked the expression of IL-21 receptor on human bone marrow and in vitro differentiated megakaryocytes. Then, we investigated the effect of IL-21 on the in vitro differentiation of human blood CD34+ progenitors into megakaryocytes. Finally, we analyzed the consequences of hydrodynamic transfection-mediated transient expression of IL-21, on megakaryopoieisis and thrombopoiesis in mice. The IL-21Rα chain was expressed in human bone marrow megakaryocytes and was progressively induced during in vitro differentiation of human peripheral CD34+ progenitors, while the signal transducing γ chain was down-regulated. Consistently, the STAT3 phosphorylation induced by IL-21 diminished during the later stages of megakaryocytic differentiation. In vitro, IL-21 increased the number of CFU-MKs generated from CD34+ cells and the number of megakaryocyte differentiated from CD34+ progenitors in a JAK3- and STAT3-dependent manner. Forced expression of IL-21 in mice increased the density of bi-potent MK progenitors and bone marrow megakaryocytes, and the platelet generation, but increased platelet clearance and consequently resulting in reduced blood platelet counts. Our work suggests that IL-21 regulates megakaryocyte development and platelet homeostasis. Thus IL-21 may link immune responses to physiological or pathological platelet-dependent processes.

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

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

    2010-01-22

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

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

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    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.

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

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

    2011-01-01

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

  2. Inhibition of oxidative stress in blood platelets by different phenolics from Yucca schidigera Roezl. bark.

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    Olas, Beata; Wachowicz, Barbara; Stochmal, Anna; Oleszek, Wieslaw

    2003-01-01

    We investigated the comparative effects of resveratrol (trans-3,4',5-trihydroxystilbene), trans-3,3',5,5'tetrahydroxy-4'-methoxystilbene, and yuccaols A and C isolated from the bark of Yucca schidigera on oxidative stress in resting blood platelets and blood platelets activated by different agonists (thrombin or thrombin receptor activating peptide). Tested phenolics (1-25 microgram/mL) reduced, to different degrees, the level of reactive oxygen species measured by the luminol-dependent chemiluminescence and changed the production of O(2)(-) measured by the reduction of cytochrome c in resting blood platelets. They also inhibited the generation of free radicals in blood platelets activated by thrombin (P 0.05), whereas trans-3,3',5,5'tetrahydroxy-4'-methoxystilbene and the alcohol yucca extract reduced lipid peroxidation in blood platelets (P Yucca schidigera inhibiting free radical generation in blood platelets may be beneficial in protecting against cardiovascular diseases when hyperactivity of platelets is observed.

  3. A mathematical model for in vitro coagulation of blood: role of platelet count and inhibition

    Indian Academy of Sciences (India)

    M SUSREE; M ANAND

    2017-03-01

    A mechanistic model including the role of platelets is proposed for clot formation and growth in plasma in vitro. Initiation of clot formation is by the addition of tissue factor, and initiation via the intrinsic pathway is neglected. Activation of zymogens follows the extrinsic pathway cascade and reactions on platelet membranes are included. Platelet activation occurs due to thrombin and also due to other activated platelets.Inhibition of the active clotting factors is by ATIII and TFPI, whereas inhibition due to APC is not relevant in the conditions modeled. The model predictions matched existing data for thrombin production in synthetic plasma. The model predicts that inhibition of platelet-driven activation of platelets has a major effect on concentration of activated platelets in PRP, normal plasma and PPP. Inhibition of platelet activation by (other activated) platelets significantly delays thrombin production in PRP and normal plasma as compared to that by thrombin. Further, sensitivity analysis shows that the model is most sensitive to the activation of platelet membrane-bound factor X by the intrinsic tenase complex.

  4. An inhibition of p38 mitogen activated protein kinase delays the platelet storage lesion.

    Directory of Open Access Journals (Sweden)

    Andrey Skripchenko

    Full Text Available BACKGROUND AND OBJECTIVES: Platelets during storage undergo diverse alterations collectively known as the platelet storage lesion, including metabolic, morphological, functional and structural changes. Some changes correlate with activation of p38 mitogen activated protein kinase (p38 MAPK. Another MAPK, extracellular signal-related kinase (ERK, is involved in PLT activation. The aim of this study was to compare the properties of platelets stored in plasma in the presence or absence of p38 and ERK MAPK inhibitors. MATERIALS AND METHODS: A single Trima apheresis platelet unit (n = 12 was aliquoted into five CLX storage bags. Two aliquots were continuously agitated with or without MAPK inhibitors. Two aliquots were subjected to 48 hours of interruption of agitation with or without MAPK inhibitors. One aliquot contained the same amount of solvent vehicle used to deliver the inhibitor. Platelets were stored at 20-24°C for 7 days and sampled on Days 1, 4, and 7 for 18 in vitro parameters. RESULTS: Inhibition of p38 MAPK by VX-702 leads to better maintenance of all platelet in vitro storage parameters including platelet mitochondrial function. Accelerated by interruption of agitation, the platelet storage lesion of units stored with VX-702 was diminished to that of platelets stored with continuous agitation. Inhibition of ERK MAPK did not ameliorate decrements in any in vitro platelet properties. CONCLUSION: Signaling through p38 MAPK, but not ERK, is associated with platelet deterioration during storage.

  5. Platelets

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

    Straub, Andreas; Wendel, Hans Peter; Dietz, Klaus; Schiebold, Daniela; Peter, Karlheinz; Schoenwaelder, Simone M; Ziemer, Gerhard

    2008-03-01

    Extracorporeal circulation (ECC) is used in cardiac surgery for cardiopulmonary bypass as well as in ventricular assist devices and for extracorporeal membrane oxygenation. Blood contact with the artificial surface and shear stress of ECC activates platelets and leukocytes resulting in a coagulopathy and proinflammatory events. Blockers of the platelet glycoprotein (GP) IIb/IIIa (CD41/CD61) can protect platelet function during ECC, a phenomenon called "platelet anaesthesia", but may be involved in post-ECC bleeding. We hypothesized that the new selective phosphoinositide 3-kinase p110beta inhibitor TGX-221 that inhibits shear-induced platelet activation without prolonging the bleeding time in vivo may also protect platelet function during ECC. Heparinized blood of healthy volunteers (n = 6) was treated in vitro with either the GP IIb/IIIa blocker tirofiban, TGX-221 or as control and circulated in an ECC model. Before and after 30 minutes circulation CD41 expression on the ECC-tubing as measure for platelet-ECC binding and generation of the platelet activation marker beta-thromboglobulin were determined using ELISA. Platelet aggregation and platelet-granulocyte binding were analysed in flow cytometry. After log-transforming the data statistical evaluation was performed using multifactor ANOVA in combination with Tukey's HSD test (global alpha = 5%). Tirofiban and TGX-221 inhibited platelet-ECC interaction, platelet aggregation and platelet-granulocyte binding. Tirofiban also inhibited ECC-induced beta-thromboglobulin release. The observed inhibition of platelet-ECC interaction and platelet activation by tirofiban contributes to explain the mechanism of "platelet anaesthesia". TGX-221 represents a promising alternative to GP IIb/IIIa blockade and should be further investigated for use during ECC in vivo.

  8. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2009-08-17

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

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

    Science.gov (United States)

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

    2008-12-01

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

  12. Low-power laser irradiation of blood inhibits platelet function: role of cyclic GMP

    Science.gov (United States)

    Brill, Alexander G.; Brill, Gregory E.; Shenkman, Boris; Tamarin, Ilya; Dardik, Rima; Varon, David; Savion, Naphtali

    1998-12-01

    The aim of the present work was to investigate effect of low power laser irradiation (LPLI) on platelet function in vitro. He-Ne laser (Optronix, USA; (lambda) - 632.8 nm, output power - 7 mW) was employed. Platelet adhesion and aggregation in whole blood (WB) under defined shear conditions were assayed by a Cone and Plate(let) Analyzer. Platelet activation was evaluated by flow cytometry. Level of platelet cGMP was estimated by immunoenzyme assay. Experiments performed showed that LPLI of WB resulted in decrease of platelet deposition on extracellular matrix at high shear rate (1300 s-1). Similar results were obtained using surfaces precoated with either collagen type I or von Willebrand factor. LPLI inhibited fibrinogen binding as well as P-selectin expression on the platelet membrane, induced by thrombin analogue. It was found out that primary acceptor of laser energy responsible for the effect on platelets was located in platelets themselves and not in blood plasma or in other blood cells. LPLI of gel- filtered platelets resulted in increase of intracellular level of cGMP both in the absence and in presence of izobutylmethylxantine (phosphodiesterase inhibitor) suggesting stimulation of synthesis rather than destruction of cGMP under the influence of LPLI. It is suggested that guanylate cyclase and/or NO-synthase might serve as primary acceptors of He-Ne laser light in platelets.

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Kodagahalli S Rakesh

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

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

    Science.gov (United States)

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

    2004-11-05

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

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

    National Research Council Canada - National Science Library

    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

    2013-01-01

    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...

  17. Glatiramer acetate (copaxone modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation.

    Directory of Open Access Journals (Sweden)

    Sarah C Starossom

    Full Text Available BACKGROUND: Glatiramer acetate (GA, Copaxone, Copolymer-1 is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE, an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets. CONCLUSIONS: GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.

  18. Arachidonic acid metabolism and inhibition of cyclooxygenase in platelets from asthmatic subjects with aspirin intolerance.

    Science.gov (United States)

    Bonne, C; Moneret-Vautrin, D A; Wayoff, M; Descharmes, A; Gazel, P; Legrand, A; Kalt, C

    1985-02-01

    Exaggerated inhibition of cyclooxygenase has been proposed as a mechanism of drug-induced bronchospasm in aspirin-intolerant patients. This study, using platelets, shows that inhibition of prostaglandin biosynthesis by aspirin is unmodified in patients when compared with healthy subjects. The ratio of cyclooxygenase:lipoxygenase products is similar in platelets from patients and control subjects. We conclude that the cyclooxygenase alteration observed in cells from the respiratory tract is not generalised to other cells such as platelets. We also propose that the major abnormality in NSAID-intolerant patients would affect receptivity to lipoxygenase products more than their biosynthesis.

  19. 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

  20. 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

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

    Directory of Open Access Journals (Sweden)

    Guy Caljon

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

  2. Antiplatelet Agents Inhibit the Generation of Platelet-Derived Microparticles

    Science.gov (United States)

    Giacomazzi, Alice; Degan, Maurizio; Calabria, Stefano; Meneguzzi, Alessandra; Minuz, Pietro

    2016-01-01

    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 PMPs shedding, testing in vitro platelet agonists and inhibitors. Platelet-rich plasma from healthy subjects was stimulated with arachidonic acid (AA), 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 PMPs shedding. The strongest response was to high concentration collagen. ADP-triggered PMPs shedding was dose-independent. ASA reduced PMPs induced by AA- (645, 347–2946 vs. 3061, 446–4901 PMPs/μL; median ad range, n = 9, P PMP shedding. The crucial role of the fibrinogen receptor and the collagen receptor in PMPs generation, independently of platelet aggregation, was identified. PMID:27695417

  3. Salvianolic acid B inhibits platelets-mediated inflammatory response in vascular endothelial cells.

    Science.gov (United States)

    Xu, Shixin; Zhong, Aiqin; Bu, Xiaokun; Ma, Huining; Li, Wei; Xu, Xiaomin; Zhang, Junping

    2015-01-01

    Salvianolic acid B (SAB) is a hydrophilic component isolated from the Chinese herb Salviae miltiorrhizae, which has been used clinically for the treatment of ischemic cardiovascular and cerebrovascular diseases. Platelets-mediated vascular inflammatory response contributes to the initiation and progression of atherosclerosis. In this paper, we focus on the modulating effects of SAB on the inflammatory reaction of endothelial cells triggered by activated platelets. Human umbilical vein endothelial cells (EA.hy926) were pretreated with SAB followed by co-culture with ADP-activated platelets. Adhesion of platelets to endothelial cells was observed by amorphological method. The activation of nuclear factor-kappa B was evaluated by NF-κB p65 nuclear translocation and the protein phosphorylation. A determination of the pro-inflammatory mediators (ICAM-1, IL-1β, IL-6, IL-8, MCP-1) mRNA and protein were also conducted. In addition, the inhibitory effects of SAB on platelets activation were also evaluated using a platelet aggregation assay and assessing the release level of soluble P-selectin. The results showed that SAB dose-dependently inhibited ADP- or α-thrombin-induced human platelets aggregation in platelet rich plasma (PRP) samples, and significantly decreased soluble P-selectin release from both agonists stimulated washed platelets. It was also found that pre-treatment with SAB reduced adhesion of ADP-activated platelets to EA.hy926 cells and inhibited NF-κB activation. In addition, SAB significantly suppressed pro-inflammatory mediators mRNA and protein in EA.hy926 cells in a dose-dependent manner. These results indicated that, in addition to its inhibitory effects on platelets activation, SAB was able to attenuate platelets-mediated inflammatory responses in endothelial cells even if the platelets had already been activated. This anti-inflammatory effect was related to the inhibition of NF-κB activation. Our findings suggest that SAB may be a potential

  4. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  6. Protein disulfide isomerase inhibition blocks thrombin generation in humans by interfering with platelet factor V activation

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2002-10-01

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

  8. Bivalirudin inhibits periprocedural platelet function and tissue factor expression of human smooth muscle cells.

    Science.gov (United States)

    Pepke, Wojciech; Eisenreich, Andreas; Jaster, Markus; Ayral, Yunus; Bobbert, Peter; Mayer, Alexander; Schultheiss, Heinz-Peter; Rauch, Ursula

    2013-04-01

    A major concern of stent implantation after percutaneous coronary intervention (PCI) is acute stent thrombosis. Effective inhibition of periprocedural platelet function in patients with coronary artery disease (CAD) leads to an improved outcome. In this study, we examined the periprocedural platelet reactivity after administrating bivalirudin during PCI compared to unfractionated heparin (UFH) administration. Further, the effect of bivalirudin on induced tissue factor (TF) expression in smooth muscle cells (SMC) was determined. Patients with CAD (n = 58) and double antithrombotic medication were treated intraprocedural with UFH (n = 30) or bivalirudin (n = 28). Platelet activation markers were flow cytometrically measured before and after stenting. The expression of TF in SMC was determined by real-time PCR and Western blotting. The thrombogenicity of platelet-derived microparticles and SMC was assessed via a TF activity assay. Bivalirudin significantly diminished the agonist-induced platelet reactivity post-PCI. Compared to UFH treatment, the adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP)-induced thrombospondin expression post-PCI was reduced when bivalirudin was administrated during intervention. In contrast to UFH, bivalirudin reduced the P-selectin expression of unstimulated and ADP-induced platelets post-PCI. Moreover, bivalirudin inhibited the thrombin-, but not FVIIa- or FVIIa/FX-induced TF expression and pro-coagulant TF activity of SMC. Moreover, bivalirudin reduced the TF activity of platelet-derived microparticles postinduction with TRAP or ADP. Bivalirudin is better than UFH in reducing periprocedural platelet activation. Moreover, thrombin-induced TF expression is inhibited by bivalirudin. Thus, bivalirudin seems to be a better anticoagulant during PCI than UFH. © 2011 Blackwell Publishing Ltd.

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

    Directory of Open Access Journals (Sweden)

    Hideki Ito

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

  10. Glycoxidized HDL, HDL enriched with oxidized phospholipids and HDL from diabetic patients inhibit platelet function.

    Science.gov (United States)

    Lê, Quang Huy; El Alaoui, Meddy; Véricel, Evelyne; Ségrestin, Bérénice; Soulère, Laurent; Guichardant, Michel; Lagarde, Michel; Moulin, Philippe; Calzada, Catherine

    2015-05-01

    High-density lipoproteins (HDL) possess atheroprotective properties including anti-thrombotic and antioxidant effects. Very few studies relate to the functional effects of oxidized HDL on platelets in type 2 diabetes (T2D). The objective of our study was to investigate the effects of in vitro glycoxidized HDL and HDL from patients with T2D on platelet aggregation and arachidonic acid signaling cascade. At the same time, the contents of hydroxylated fatty acids were assessed in HDL. Compared with control HDL, in vitro glycoxidized HDL had decreased proportions of linoleic (LA) and arachidonic (AA) acids in phospholipids and cholesteryl esters, and increased concentrations of hydroxy-octadecadienoic acids (9-HODE and 13-HODE) and 15-hydroxy-eicosatetraenoic acid (15-HETE), derived from LA and AA respectively, especially hydroxy derivatives esterified in phospholipids. Glycoxidized HDL dose-dependently decreased collagen-induced platelet aggregation by binding to scavenger receptor BI (SR-BI). Glycoxidized HDL prevented collagen-induced increased phosphorylation of platelet p38 MAPK and cytosolic phospholipase A2, as well as intracellular calcium mobilization. HDL enriched with oxidized phosphatidylcholine (PC), namely PC(16:0/13-HODE) dose-dependently inhibited platelet aggregation. Increased concentrations of 9-HODE, 13-HODE, and 15-HETE in phospholipids (2.1-, 2.1-, and 2.4-fold increase, respectively) were found in HDL from patients with T2D, and these HDL also inhibited platelet aggregation via SR-BI. Our results suggest that in vitro glycoxidized HDL as well as HDL from patients with T2D inhibit platelet aggregation, and suggest that oxidized LA-containing phospholipids may contribute to the anti-aggregatory effects of glycoxidized HDL and HDL from patients with T2D.

  11. Glycoxidized HDL, HDL enriched with oxidized phospholipids and HDL from diabetic patients inhibit platelet function

    Science.gov (United States)

    Lê, Quang Huy; El Alaoui, Meddy; Véricel, Evelyne; Ségrestin, Bérénice; Soulère, Laurent; Guichardant, Michel; Lagarde, Michel; Moulin, Philippe; Calzada, Catherine

    2015-01-01

    Context High-density lipoproteins (HDL) possess atheroprotective properties including anti-thrombotic and antioxidant effects. Very few studies relate to the functional effects of oxidized HDL on platelets in type 2 diabetes (T2D). Objective The objective of our study was to investigate the effects of in vitro glycoxidized HDL, and HDL from T2D patients on platelet aggregation and arachidonic acid signaling cascade. At the same time, the contents of hydroxylated fatty acids were assessed in HDL. Results Compared to control HDL, in vitro glycoxidized HDL had decreased proportions of linoleic (LA) and arachidonic (AA) acids in phospholipids and cholesteryl esters, and increased concentrations of hydroxy-octadecadienoic acids (9-HODE and 13-HODE) and 15-hydroxy-eicosatetraenoic acid (15-HETE), derived from LA and AA respectively, especially hydroxy derivatives esterified in phospholipids. Glycoxidized HDL dose-dependently decreased collagen-induced platelet aggregation by binding to SR-BI. Glycoxidized HDL prevented collagen-induced increased phosphorylation of platelet p38 MAPK and cytosolic phospholipase A2, as well as intracellular calcium mobilization. HDL enriched with oxidized phospholipids, namely PC(16:0/13-HODE) dose-dependently inhibited platelet aggregation. Increased concentrations of 9-HODE, 13-HODE and 15-HETE in phospholipids (2.1, 2.1 and 2.4-fold increase respectively) were found in HDL from patients with T2D, and these HDL also inhibited platelet aggregation via SR-BI. Conclusions Altogether, our results indicate that in vitro glycoxidized HDL as well as HDL from T2D patients inhibit platelet aggregation, and suggest that oxidized LA-containing phospholipids may contribute to the anti-aggregatory effects of glycoxidized HDL and HDL from T2D patients. PMID:25794249

  12. Dietary flavanols and procyanidin oligomers from cocoa (Theobroma cacao) inhibit platelet function.

    Science.gov (United States)

    Murphy, Karen J; Chronopoulos, Andriana K; Singh, Indu; Francis, Maureen A; Moriarty, Helen; Pike, Marilyn J; Turner, Alan H; Mann, Neil J; Sinclair, Andrew J

    2003-06-01

    Flavonoids may be partly responsible for some health benefits, including antiinflammatory action and a decreased tendency for the blood to clot. An acute dose of flavanols and oligomeric procyanidins from cocoa powder inhibits platelet activation and function over 6 h in humans. This study sought to evaluate whether 28 d of supplementation with cocoa flavanols and related procyanidin oligomers would modulate human platelet reactivity and primary hemostasis and reduce oxidative markers in vivo. Thirty-two healthy subjects were assigned to consume active (234 mg cocoa flavanols and procyanidins/d) or placebo (cocoa flavanols and procyanidins/d) tablets in a blinded parallel-designed study. Platelet function was determined by measuring platelet aggregation, ATP release, and expression of activation-dependent platelet antigens by using flow cytometry. Plasma was analyzed for oxidation markers and antioxidant status. Plasma concentrations of epicatechin and catechin in the active group increased by 81% and 28%, respectively, during the intervention period. The active group had significantly lower P selectin expression and significantly lower ADP-induced aggregation and collagen-induced aggregation than did the placebo group. Plasma ascorbic acid concentrations were significantly higher in the active than in the placebo group (P Cocoa flavanol and procyanidin supplementation for 28 d significantly increased plasma epicatechin and catechin concentrations and significantly decreased platelet function. These data support the results of acute studies that used higher doses of cocoa flavanols and procyanidins.

  13. 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) tr...

  14. ATTENUATION OF ANTI-THY1 GLOMERULONEPHRITIS IN THE RAT BY ANTIINFLAMMATORY PLATELET-INHIBITING AGENTS

    NARCIS (Netherlands)

    POELSTRA, K; BROUWER, E; BALLER, JFW; HARDONK, MJ; BAKKER, WW

    Although both ecto-ADPase and prostacyclin (PGI2) inhibit platelets and neutrophils, their action in acute glomerulonephritis is unknown. We tested the PGI2 analog Iloprost and 2chloro-adenosine (2Cl-ADO), an analog of adenosine, the end product of nucleotidase activities, during anti-Thy1

  15. 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.

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

    Science.gov (United States)

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

    2017-01-01

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

  17. 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

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

    Science.gov (United States)

    Philp, R B; Paul, M L

    1983-06-01

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

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

    OpenAIRE

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

    2006-01-01

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

  20. 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+.

  1. Hydroxytyrosyl alkyl ether derivatives inhibit platelet activation after oral administration to rats.

    Science.gov (United States)

    Muñoz-Marín, Javier; De la Cruz, José Pedro; Reyes, José Julio; López-Villodres, Juan Antonio; Guerrero, Ana; López-Leiva, Inmaculada; Espartero, José Luis; Labajos, María Teresa; González-Correa, José Antonio

    2013-08-01

    The low lipophilicity of hydroxytyrosol (HT) has motivated efforts to synthesize homologous series with better lipid solubility, such as the ethers, which are more lipophilic than HT. Because HT inhibits platelet aggregation, the aim of the study was to assess the possible anti-platelet effect of five HT ether derivatives (ethyl, butyl, hexyl, octyl and dodecyl) after oral administration to rats. Whole blood collagen-induced platelet aggregation and calcium-induced thromboxane B2 (TxB2), aortic 6-keto-prostaglandin F1α (6-keto-PGF1α) and nitrites+nitrates, plasma concentration of lipid peroxides (TBARS) and red blood cell content of reduced glutathione (GSH) were measured. The administration of 20 mg/kg/day inhibited platelet aggregation, TxB2 and TBARS in a non-linear manner related to the length of the carbon chain, with a cut-off effect in the hexyl derivative. Aortic nitrite and red blood cell GSH production were also increased. The aortic production of 6-keto-PGF1α was unaltered except in the group treated with the dodecyl derivative. The administration of 50 mg/kg/day showed a similar pharmacodynamic profile but without the non-linear effect. In conclusion, HT ethers, especially the hexyl derivative, are a potential alternative to hydroxytyrosol, and their effect merits additional research to determine their role in the prophylaxis of vascular disease.

  2. 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.

  3. Inhibition of platelet (/sup 3/H)- imipramine binding by human plasma protein fractions

    Energy Technology Data Exchange (ETDEWEB)

    Strijewski, A.; Chudzik, J.; Tang, S.W.

    1988-01-01

    Inhibition of high-affinity (/sup 3/H)-imipramine binding to platelet membranes by human plasma fractions and isolated plasma proteins was investigated. Several plasma proteins were found to contribute to the observed apparent inhibition and this contribution was assessed in terms of inhibitor units. Alpha/sub 1/ acid glycoprotein, high density and low density lipoprotein, IgG and ..cap alpha../sub 1/-antitrypsin were identified as effective non-specific inhibitors. Alpha-1-acid glycoprotein was confirmed to be the most potent plasma protein inhibitor. Cohn fractions were evaluated for the presence of the postulated endocoid of (/sup 3/H)-imipramine binding site.

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2016-02-05

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

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

    Science.gov (United States)

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

    2015-09-01

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

  7. Clinically relevant HOCl concentrations reduce clot retraction rate via the inhibition of energy production in platelet mitochondria.

    Science.gov (United States)

    Misztal, T; Rusak, T; Tomasiak, M

    2014-12-01

    Using porcine blood, we examined the impact of hypochlorite, product of activated inflammatory cells, on clot retraction (CR), an important step of hemostasis. We found that, in vitro, HOCl is able to reduce CR rate and enlarge final clot size in whole blood (t.c. 100 μM), platelet-rich plasma (PRP) threshold concentration (t.c. 50 μM), and an artificial system (washed platelets and fibrinogen) (t.c. 25 nM). Combination of low HOCl and peroxynitrite concentrations resulted in synergistic inhibition of CR by these stressors. Concentrations of HOCl completely inhibiting CR failed to affect the kinetics of coagulation measured in PRP and in platelet-free plasma. Concentrations of HOCl reducing CR rate in PRP augmented production of lactate, inhibited consumption of oxygen by platelets, and decreased total adenosine triphosphate (ATP) content in PRP-derived clots. In an artificial system, concentrations of HOCl resulting in inhibition of CR (25-100 nM) reduced mitochondrial transmembrane potential and did not affect actin polymerization in thrombin-stimulated platelets. These concentrations of HOCl failed to affect the adhesion of washed platelets to fibrinogen and to evoke sustained calcium signal, thus excluding stressor action on glycoprotein IIb/IIIa receptors. Exogenously added Mg-ATP almost completely recovered HOCl-mediated retardation of CR. Concentrations of HOCl higher than those affecting CR reduced thromboelastometric variables (maximum clot firmness and α angle). We conclude that low clinically relevant HOCl concentrations may evoke the inhibition of CR via the reduction of platelet contractility resulted from malfunction of platelet mitochondria. At the inflammatory conditions, CR may be the predominant HOCl target.

  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. Helenalin and 11 alpha,13-dihydrohelenalin, two constituents from Arnica montana L., inhibit human platelet function via thiol-dependent pathways.

    Science.gov (United States)

    Schröder, H; Lösche, W; Strobach, H; Leven, W; Willuhn, G; Till, U; Schrör, K

    1990-03-15

    This study investigates the effect on human platelet function of two sesquiterpene lactones from Arnica montana L., helenalin (H) and 11 alpha,13-dihydrohelenalin (DH). Both compounds inhibited collagen-induced platelet aggregation, thromboxane formation and 5-hydroxytryptamine secretion in a concentration-dependent manner at 3-300 microM. When arachidonic acid was used as stimulus, thromboxane formation remained unaffected despite of inhibition of platelet aggregation. Both H and DH reduced the number of acid-soluble sulfhydryl groups in platelets, by up to 78% at anti-aggregatory concentrations. Moreover, H- and DH-induced platelet inhibition could be prevented by the thiol containing amino acid cysteine. It is concluded that H and DH inhibit platelet function via interaction with platelet sulfhydryl groups, probably associated with reduced phospholipase A2 activity.

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

    Science.gov (United States)

    Karolczak, Kamil; Pieniazek, Anna; Watala, Cezary

    2017-01-01

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

  11. 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].

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    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.

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

    Science.gov (United States)

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

    2013-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    1985-01-01

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

  15. Kaempferol suppresses collagen-induced platelet activation by inhibiting NADPH oxidase and protecting SHP-2 from oxidative inactivation.

    Science.gov (United States)

    Wang, Su Bin; Jang, Ji Yong; Chae, Yun Hee; Min, Ji Hyun; Baek, Jin Young; Kim, Myunghee; Park, Yunjeong; Hwang, Gwi Seo; Ryu, Jae-Sang; Chang, Tong-Shin

    2015-06-01

    Reactive oxygen species (ROS) generated upon collagen stimulation act as second messengers to propagate various platelet-activating events. Among the ROS-generating enzymes, NADPH oxidase (NOX) plays a prominent role in platelet activation. Thus, NOX has been suggested as a novel target for anti-platelet drug development. Although kaempferol has been identified as a NOX inhibitor, the influence of kaempferol on the activation of platelets and the underlying mechanism have never been investigated. Here, we studied the effects of kaempferol on NOX activation, ROS-dependent signaling pathways, and functional responses in collagen-stimulated platelets. Superoxide anion generation stimulated by collagen was significantly inhibited by kaempferol in a concentration-dependent manner. More importantly, kaempferol directly bound p47(phox), a major regulatory subunit of NOX, and significantly inhibited collagen-induced phosphorylation of p47(phox) and NOX activation. In accordance with the inhibition of NOX, ROS-dependent inactivation of SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) was potently protected by kaempferol. Subsequently, the specific tyrosine phosphorylation of key components (Syk, Vav1, Btk, and PLCγ2) of collagen receptor signaling pathways was suppressed by kaempferol. Kaempferol also attenuated downstream responses, including cytosolic calcium elevation, P-selectin surface exposure, and integrin-αIIbβ3 activation. Ultimately, kaempferol inhibited platelet aggregation and adhesion in response to collagen in vitro and prolonged in vivo thrombotic response in carotid arteries of mice. This study shows that kaempferol impairs collagen-induced platelet activation through inhibition of NOX-derived ROS production and subsequent oxidative inactivation of SHP-2. This effect suggests that kaempferol has therapeutic potential for the prevention and treatment of thrombovascular diseases.

  16. Inhibition of platelet function with clopidogrel is associated with a reduction of inflammation in patients with peripheral artery disease.

    Science.gov (United States)

    Meyer, Alexander; Weithaeuser, Alice; Steffens, Daniel; Bobbert, Peter; Hassanein, Adel; Ayral, Yunus; Schultheiss, Heinz-Peter; Rauch, Ursula

    2016-01-01

    The reactivity of platelets is increased in patients with peripheral artery disease (PAD). RANTES and sCD40L are chemokines which are stored in the alpha-granules of platelets. Clopidogrel inhibits and thus reduces platelet reactivity. Whether a treatment with clopidogrel is associated with an inhibition of systemic inflammation in patients with PAD has not been thoroughly explored. This study examined the effect of clopidogrel on platelet reactivation and the release of inflammatory chemokines in patients with PAD. 40 patients with PAD were randomized into two groups. In the first group A the patients were treated with 100mg acetylsalicylic acid (ASA) and additional placebo for 4weeks. The patients in group B received 75mg/d clopidogrel in addition to ASA 100mg for 4weeks. After obtaining blood at days 0, 7 and 28 the platelet activation was determined by measuring the surface protein expression of CD63, CD62p and thrombospondin (TSP) after stimulation with TRAP and ADP. The release of the chemokines RANTES and sCD40L from platelets was analyzed by ELISA. Platelet activation markers (CD62p and CD63) and chemokine RANTES were significantly reduced in patients with PAD after 7 and 28days after treatment with clopidogrel. No alterations were found in TSP expression and sCD40L during the treatment. The treatment with clopidogrel leads to a reduction of platelet reactivity and release of RANTES from the platelets of patients with PAD. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2016-08-01

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

  18. Trimeresurus venom inhibition of anti-HPA-1a and anti-HPA-1b antibody binding to human platelets.

    Science.gov (United States)

    Wlodar, S J; Stone, D L; Sinor, L T

    1995-01-01

    A solid-phase red cell adherence assay was used to demonstrate the specific inhibitory effect of seven species of Trimeresurus snake venom on the binding of HPA-1a- and HPA-1b-specific platelet antibodies. Trimeresurus venom did not inhibit the binding of HLA-, HPA-3a-, HPA-3b-, HPA-4a-, HPA-5a-, and HPA-5b-specific platelet antibodies. Venom from other genera of snakes, including representatives from Agkistrodon, Ancistrodon, Bitis, Bothrops, Bungarus, Causus, Crotalus, Dendroaspis, Ecis, Micrurus, Naja, Notechis, Ophiophagus, Pseudechis, Sepedon (Hemachatus), and Vipera, all failed to specifically inhibit anti-HPA-1a and HPA-1b binding. These results may indicate that the component in Trimeresurus snake venom previously reported to bind to the platelet GPIIb-IIIa complex, inhibiting fibrinogen binding, binds close to the HPA-1a and HPA-1b epitopes.

  19. Inhibition of collagen-induced platelet aggregation by anopheline antiplatelet protein, a saliva protein from a malaria vector mosquito.

    Science.gov (United States)

    Yoshida, Shigeto; Sudo, Toshiki; Niimi, Masashi; Tao, Lian; Sun, Bing; Kambayashi, Junichi; Watanabe, Hiroyuki; Luo, Enjie; Matsuoka, Hiroyuki

    2008-02-15

    During blood feeding, mosquitoes inject saliva containing a mixture of molecules that inactivate or inhibit various components of the hemostatic response to the bite injury as well as the inflammatory reactions produced by the bite, to facilitate the ingestion of blood. However, the molecular functions of the individual saliva components remain largely unknown. Here, we describe anopheline antiplatelet protein (AAPP) isolated from the saliva of Anopheles stephensi, a human malaria vector mosquito. AAPP exhibited a strong and specific inhibitory activity toward collagen-induced platelet aggregation. The inhibitory mechanism involves direct binding of AAPP to collagen, which blocks platelet adhesion to collagen and inhibits the subsequent increase in intracellular Ca(2+) concentration ([Ca(2+)]i). The binding of AAPP to collagen effectively blocked platelet adhesion via glycoprotein VI (GPVI) and integrin alpha(2)beta(1). Cell adhesion assay showed that AAPP inhibited the binding of GPVI to collagen type I and III without direct effect on GPVI. Moreover, intravenously administered recombinant AAPP strongly inhibited collagen-induced platelet aggregation ex vivo in rats. In summary, AAPP is a malaria vector mosquito-derived specific antagonist of receptors that mediate the adhesion of platelets to collagen. Our study may provide important insights for elucidating the effects of mosquito blood feeding against host hemostasis.

  20. Matrine inhibits proliferation of mouse skin fibroblasts induced by platelet-derived growth factor-BB

    Institute of Scientific and Technical Information of China (English)

    WU Yan-an; GAO Chun-fang; WANG Hao; HUANG Chao; KONG Xian-tao

    2001-01-01

    To study the effect of matrine on proliferation of mouse skin fibroblasts induced by platelet-derived growth factor-BB (PDGF-BB). Methods: Mouse skin fibroblasts were obtained from newborn ⅠCR mice and propagated in vitro. Proliferation of cell was analyzed by mitochondrial reduction of tetrazolium salt MTT and actual cell count. Results: Matrine (50 to 500 μg/ml) caused dose-dependent reduction of serum-stimulated cell growth. Growth inhibition was totally reversed after removal of the drug. Matrine also inhibited PDGF-BB induced cell growth dose-dependently. Conclusion: Matrine exhibits potent anti-proliferation effect on mouse skin fibroblast. This effect appears to be mediated by decrease of PDGF-induced growth. These results suggest that matrine might have preventive and therapeutic implication in skin fibrosis.

  1. 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.

  2. Salvianolic Acid B inhibits platelet adhesion under conditions of flow by a mechanism involving the collagen receptor alpha 2 beta 1

    NARCIS (Netherlands)

    Wu, Ya Ping; Zhao, Xiao Min; Pan, Shao Dong; Guo, De An; Wei, Ran; Han, Ji Ju; Kainoh, Mie; Xia, Zuo Li; de Groot, Philip G.; Lisman, Ton

    2008-01-01

    Salvianolic acid B (SAB) is a component of Danshen, a herb widely used in Chinese medicine, and was previously shown to exert a number of biological activities including inhibition of platelet function, but the exact mechanisms involved are unclear. SAB dose-dependently inhibited platelet deposition

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

    DEFF Research Database (Denmark)

    Boysen, G; Boss, A H; Ødum, Niels

    1984-01-01

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

  4. Diffuse Alveolar Hemorrhage Associated With Low Molecular Weight Heparin and Dual Anti-platelet Therapy After Percutaneous Coronary Intervention.

    Science.gov (United States)

    Yildirim, Fatma; Kara, İskender; Okuyan, Hızır; Abaci, Adnan; Turkoglu, Melda; Aygencel, Gülbin

    2016-01-19

    A 54-year-old man had undergone to percutaneous coronary intervention (PCI) and two stents were placed to left anterior coronary artery and circumflex artery. Low molecular weight heparin (LMWH) together with ticagrelor 90 mg twice a day and acetylsalicylic acid (Aspirin) were started after PCI due to high risk of stent trombosis. On the fourth day of patient's follow-up in the intensive care unit (ICU), bloody secretion was started from endotracheal tube. Hemoglobin dropping, bilateral infiltration on the chest X-ray and bleeding from lung were diagnosed as diffuse alveolar hemorrhage (DAH). Apart from LMWH and antiplatelet therapies with aspirin and ticagrelor, there were no other identified risk factors for DAH. As far as we know, our report is the first case of DAH caused by LMWH and dual anti-platelet therapy including ticagrelor. This article is protected by copyright. All rights reserved.

  5. Alternative dosing of dual PI3K and MEK inhibition in cancer therapy

    Directory of Open Access Journals (Sweden)

    Jokinen Elina

    2012-12-01

    Full Text Available Abstract Background PI3K/AKT/mTOR and RAS/RAF/MEK/ERK pathways are thought to be the central transducers of oncogenic signals in solid malignancies, and there has been a lot of enthusiasm for developing inhibitors of these pathways for cancer therapy. Some preclinical models have suggested that combining inhibitors of both parallel pathways may be more efficacious, but it remains unknown whether dual inhibition with high enough concentrations of the drugs to achieve meaningful target inhibition is tolerable in a clinical setting. Furthermore, the predictive factors for dual inhibition are unknown. Methods Non-small cell lung cancer (NSCLC cell lines (n=12 with the most frequent oncogenic backgrounds (K-Ras mut n=3, EGFR mut n=3, ALK translocated n=3, and triple-negative n=3 were exposed to PI3K inhibitors (ZSTK474, PI-103 or MEK inhibitor (CI-1040 alone or in combination and analysed with an MTS growth/cytotoxicity assay and statistically by combination index analysis. The activity of the intracellular signaling pathways in response to the inhibitor treatments was analysed with a western blot using phospho-specific antibodies to AKT, ERK1/2, S6, and 4E-BPI. For the differential dosing schedule experiments, additional breast and colon cancer cell lines known to be sensitive to dual inhibition were included. Results Two of the 12 NSCLC cell lines tested, H3122 (ALK translocated and H1437 (triple-negative, showed increased cytotoxicity upon dual MEK and PI3K inhibition. Furthermore, MDA-MB231 (breast and HCT116 (colon, showed increased cytotoxicity upon dual inhibition, as in previous studies. Activation of parallel pathways in the dual inhibition-sensitive lines was also noted in response to single inhibitor treatment. Otherwise, no significant differences in downstream intracellular pathway activity (S6 and 4E-BPI were noted between PI3K alone and dual inhibition other than the increased cytotoxicity of the latter. In the alternative dosing

  6. Plant food anthocyanins inhibit platelet granule secretion in hypercholesterolaemia: Involving the signalling pathway of PI3K-Akt.

    Science.gov (United States)

    Song, Fenglin; Zhu, Yanna; Shi, Zhenyin; Tian, Jinju; Deng, Xiujuan; Ren, Jing; Andrews, Marc C; Ni, Heyu; Ling, Wenhua; Yang, Yan

    2014-11-01

    Controlling platelet granule secretion has been considered an effective strategy to dampen thrombosis and prevent atherosclerosis. Anthocyanins are natural plant pigments and possess a wide range of biological activities, including cardiovascular protective activity. In the present study we explored the effects and the potential mechanisms of anthocyanins on platelet granule secretion in hypercholesterolemia. In a randomised, double-blind clinical trial, 150 hypercholesterolaemic individuals were treated with purified anthocyanins (320 mg/day) or placebo for 24 weeks. Anthocyanins consumption significantly reduced plasma levels of β-thromboglobulin (β-TG), soluble P-selectin, and of Regulated on Activation Normal T cell Expressed and Secreted (RANTES) as compared with the placebo. A minor reduction in platelet factor 4 (PF4) and transforming growth factor β1 (TGF-β1) levels were also observed. In in vitro experiments, we observed that puriӿed anthocyanin mixture, as well as its two main anthocyanin components, delphinidin-3-glucoside (Dp-3-g) and cyanidin-3-glucoside (Cy-3g) directly inhibited platelet á-granule, dense granule, and lysosome secretion evaluated by P-selectin, RANTES, β-TG, PF4, TGF-β1, serotonin, ATP, and CD63 release. Further, anthocyanins inhibited platelet PI3K/Akt activation and consequently attenuated eNOS phosphorylation and cGMP production, thus interrupting MAPK activation. LY294002, a PI3K inhibitor, did not cause additional inhibitory efficacy, indicating that anthocyanin-induced effects may be involved in inhibition of the PI3K/Akt signalling pathway. These results provide evidence that by inhibiting platelet granule secretion, anthocyanins may be a potent cardioprotective agent.

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

    Science.gov (United States)

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

    2012-01-01

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

  8. 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.

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

    Science.gov (United States)

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

    2010-01-01

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

  10. 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.

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    Paul C Armstrong

    Full Text Available BACKGROUND: Clinical use of selective inhibitors of cyclooxygenase (COX-2 appears associated with increased risk of thrombotic events. This is often hypothesised to reflect reduction in anti-thrombotic prostanoids, notably PGI(2, formed by COX-2 present within endothelial cells. However, whether COX-2 is actually expressed to any significant extent within endothelial cells is controversial. Here we have tested the effects of acute inhibition of COX on platelet reactivity using a functional in vivo approach in mice. METHODOLOGY/PRINCIPAL FINDINGS: A non-lethal model of platelet-driven thromboembolism in the mouse was used to assess the effects of aspirin (7 days orally as control diclofenac (1 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. CONCLUSIONS/SIGNIFICANCE: Inhibition of COX-1 by diclofenac or aspirin reduced thrombus formation induced by collagen, which is partly dependent upon platelet-derived TXA(2, but not that induced by U46619, which is independent of platelet TXA(2. These results are consistent with the model demonstrating the effects of COX-1 inhibition in platelets, but provide no support for the hypothesis that acute inhibition of COX-2 in the circulation increases thrombosis.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

    Philp, R B; Paul, M L

    1986-01-01

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

  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

    2016-01-01

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

  14. Staphylococcal SSL5 Binding to Human Leukemia Cells Inhibits Cell Adhesion to Endothelial Cells and Platelets

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    Annemiek M. E. Walenkamp

    2010-01-01

    Full Text Available Bacterial proteins provide promising tools for novel anticancer therapies. Staphylococcal superantigen-like 5 (SSL5 was recently described to bind P-selectin glycoprotein ligand-1 (PSGL-1 on leukocytes and to inhibit neutrophil rolling on a P-selectin surface. As leukocytes and tumor cells share many characteristics in migration and dissemination, we explored the potential of SSL5 as an antagonist of malignant cell behavior. Previously, it was demonstrated that rolling of human HL-60 leukemia cells on activated endothelial cells was mediated by P-selectin. In this study, we show that SSL5 targets HL-60 cells. Binding of SSL5 was rapid and without observed toxicity. Competition of SSL5 with the binding of three anti-PSGL-1 antibodies and P-selectin to HL-60 cells identified PSGL-1 as the ligand on HL-60 cells. Presence of sialyl Lewis x epitopes on PSGL-1 was crucial for its interaction with SSL5. Importantly, SSL5 not only inhibited the interaction of HL-60 cells with activated endothelial cells but also with platelets, which both play an important role in growth and metastasis of cancers. These data support the concept that SSL5 could be a lead in the search for novel strategies against hematological malignancies.

  15. The inhibition of oxygen radical release from human neutrophils by resting platelets is reversed by administration of acetylsalicylic acid or clopidogrel.

    Science.gov (United States)

    Reinisch, C M; Dunzendorfer, S; Pechlaner, C; Ricevuti, G; Wiedermann, C J

    2001-05-01

    Resting platelets inhibit oxygen radical release from neutrophils. Antiplatelet therapy may support this function by preventing platelet activation. Whether antiplatelet agents affect the antioxidative action of resting platelets in the absence of platelet activation is unknown. The effect of acetylsalicylic acid or clopidogrel administration on the antioxidative action of resting platelets was therefore studied in ten healthy volunteers. Preparations of resting platelets were obtained from 5 subjects each - before, during and after an eight-day course of daily treatment with 100 mg of acetylsalicylic acid or 75 mg of the thienopyridine clopidogrel. Human peripheral blood neutrophils were pretreated with the platelets at a ratio of (1/5)0 for 45 min; then formyl-Met-Leu-Phe-triggered oxygen radical release was measured fluorometrically. The inhibitory effect of platelets on oxygen radical release from neutrophils which was seen before treatment was abolished by antiplatelet therapy with either of the drugs, and inhibition was restored gradually after discontinuing acetlsalicylic acid/ clopidogrel intake. Results suggest that the protective role of resting platelets in controlling oxygen radical release from neutrophils in the absence of platelet activation may be impaired by antiplatelet therapy.

  16. Cystamine immobilization on TiO 2 film surfaces and the influence on inhibition of collagen-induced platelet activation

    Science.gov (United States)

    Zhou, Yujuan; Weng, Yajun; Zhang, Liping; Jing, Fengjuan; Huang, Nan; Chen, Junying

    2011-12-01

    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 2 films were firstly synthesized on Si (1 0 0) wafers via unbalanced magnetron sputtering technology, and then polydopamine was grafted on TiO 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.

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

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    Mayara Ribeiro de Queiroz

    2014-01-01

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

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

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    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.

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

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    Binggang Xiang

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

  20. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

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

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    Hedbäck Bo

    2009-06-01

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

  3. Simultaneous administration of high-dose atorvastatin and clopidogrel does not interfere with platelet inhibition during percutaneous coronary intervention

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    Kreutz RP

    2016-06-01

    Full Text Available Rolf P Kreutz,1,2 Jeffrey A Breall,1 Anjan Sinha,1 Elisabeth von der Lohe,1 Richard J Kovacs,1 David A Flockhart,2,† 1Krannert Institute of Cardiology, 2Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN, USA †David A Flockhart passed away on November 26, 2015 Background: Reloading with high-dose atorvastatin shortly before percutaneous coronary interventions (PCIs has been proposed as a strategy to reduce periprocedural myonecrosis. There has been a concern that statins that are metabolized by cytochrome P450 3A4 may interfere with clopidogrel metabolism at high doses. The impact of simultaneous administration of high doses of atorvastatin and clopidogrel on the efficacy of platelet inhibition has not been established. Methods: Subjects (n=60 were randomized to receive atorvastatin 80 mg together with clopidogrel 600 mg loading dose (n=28 versus clopidogrel 600 mg alone (n=32 at the time of PCI. Platelet aggregation was measured at baseline, 4 hours after clopidogrel loading dose, and 16–24 hours after clopidogrel loading dose by light transmittance aggregometry using adenosine diphosphate as agonist. Results: Platelet aggregation was similar at baseline in both the atorvastatin and the control groups (adenosine diphosphate 10 µM: 57%±19% vs 61%±21%; P=0.52. There was no significant difference in platelet aggregation between the atorvastatin and the control groups at 4 hours (37%±18% vs 39%±21%; P=0.72 and 16–24 hours post-clopidogrel loading dose (35%±17% vs 37%±18%; P=0.75. No significant difference in incidence of periprocedural myonecrosis was observed between the atorvastatin and control groups (odds ratio: 1.02; 95% confidence interval 0.37–2.8. Conclusion: High-dose atorvastatin given simultaneously with clopidogrel loading dose at the time of PCI does not significantly alter platelet inhibition by clopidogrel. Statin reloading with high doses of atorvastatin at the time of PCI

  4. Effectiveness of platelet inhibition on major adverse cardiac events in non-cardiac surgery after percutaneous coronary intervention: a prospective cohort study.

    Science.gov (United States)

    Wąsowicz, M; Syed, S; Wijeysundera, D N; Starzyk, Ł; Grewal, D; Ragoonanan, T; Harsha, P; Travis, G; Carroll, J; Karkouti, K; Beattie, W S

    2016-04-01

    Platelet inhibition is mandatory therapy after percutaneous coronary intervention (PCI). Withdrawal of oral antiplatelet agents has been linked to increased incidence of postoperative adverse cardiac events in post-PCI patients having non-cardiac surgery (NCS). There is limited knowledge of temporal changes in platelet inhibition in this high-risk surgical population. We therefore performed a multicentre prospective cohort study evaluating perioperative platelet function and its association with postoperative major adverse cardiac events (MACE). In 201 post-PCI patients having NCS, we assessed the association between platelet function and postoperative MACE. We performed perioperative platelet function testing using a platelet mapping assay (PMA). Troponin-I was measured every 8 h for 2 days, then daily until day 5. Myocardial infarction was assessed using the third universal definition. We used multivariable logistic regression to assess the association between platelet inhibition and MACE. Major adverse cardiac events occurred in 40 patients within 30 days of surgery. Thirty-two of these events were non-ST-elevation myocardial infarction, four ST-elevation myocardial infarction, and four exacerbation of congestive heart failure. We were unable to show an association between platelet inhibition and MACE. The PMA showed declining levels of platelet inhibition the longer the antiplatelet therapy was withheld before surgery. Logistic regression did not show an association between preoperative platelet function or the type of stent and MACE. We found an increased cardiac risk of MACE after surgery within 6 weeks of PCI. The incidence of MACE in patients undergoing NCS after previous PCI is high in spite of adequate perioperative antiplatelet therapy. NCT 01707459 (registered at http://www.clinicaltrials.gov). © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email

  5. /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.

  6. 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

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Dong-Seon Kim

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Hikmatullah Jan

    2010-10-01

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

  10. Study design and rationale of a comparison of prasugrel and clopidogrel in medically managed patients with unstable angina/non-ST-segment elevation myocardial infarction: the TaRgeted platelet Inhibition to cLarify the Optimal strateGy to medicallY manage Acute Coronary Syndromes (TRILOGY ACS

    DEFF Research Database (Denmark)

    Chin, Chee Tang; Roe, Matthew T; Fox, Keith A A;

    2010-01-01

    Practice guidelines recommend dual antiplatelet therapy with aspirin and clopidogrel for patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) regardless of in-hospital management strategy. Prasugrel-a thienopyridine adenosine diphosphate receptor antagonist that provides...... higher and less variable levels of platelet inhibition than clopidogrel-has demonstrated benefit when used to treat ACS patients undergoing percutaneous coronary intervention. However, the optimal approach to antiplatelet therapy for high-risk, medically managed NSTE ACS patients remains uncertain...

  11. 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.

  12. MK615 inhibits pancreatic cancer cell growth by dual inhibition of Aurora A and B kinases

    Institute of Scientific and Technical Information of China (English)

    Toshie Okada; Tokihiko Sawada; Tatsushi Osawa; Masakazu Adachi; Keiichi Kubota

    2008-01-01

    AIM:To investigate the anti-neoplastic effect of MK615,an anti-neoplastic compound isolated from Japanese apricot,against human pancreatic cancer cells in vitro.METHODS:Three human pancreatic cancer cell lines PANC-1,PK-1,and PK45H were cultured with MK615 at concentrations of 600,300,150,and O μg/mL.Growth inhibition was evaluated by cell proliferation assay,and killing activity was determined by lactate dehydrogenase (LDH) assay.Expression of Aurora A and B kinases was detected by real-time polymerase chain reaction (PCR) and Western blotting.Cell cycle stages were evaluated by flow cytometry.RESULTS:The growth inhibitory rates of MK615 at 150,300,and 600 μg/mL were 2.3% ± 0.9%,8.9% ±3.2% and 67.1% ± 8.1% on PANC1 cells,1.3% ± 0.3%,8.7% ± 4.1% and 45.7 ± 7.6% on PK1 cells,and 1.2 ±0.8%,9.1% ± 2.1% and 52.1% ± 5.5% on PK45H cells,respectively (P<0.05).The percentage cytotoxicities of MK615 at 0,150,300,and 600 μg/mL were 19.6% ±1.3%,26.7% ± 1.8%,25.5% ± 0.9% and 26.4% ± 0.9%in PANC1 cells,19.7% ± 1.3%,24.7% ± 0.8%,25.9% ±0.9% and 29.9% ± 1.1% in PK1 cells,and 28.0% ± 0.9%,31.2% ± 0.9%,30.4% ± 1.1% and 35.3 ± 1.0% in PK45H cells,respectively (P<0.05).Real-time PCR and Western blotting showed that MK615 dually inhibited the expression of Aurora A and B kinases.Cell cycle analysis revealed that MK615 increased the population of cells in G2/M phase.CONCLUSION:MK615 exerts an anti-neoplastic effect on human pancreatic cancer cells in vitro by dual inhibition of Aurora A and B kinases.

  13. Platelet microparticles inhibit IL-17 production by regulatory T cells through P-selectin.

    Science.gov (United States)

    Dinkla, Sip; van Cranenbroek, Bram; van der Heijden, Wouter A; He, Xuehui; Wallbrecher, Rike; Dumitriu, Ingrid E; van der Ven, André J; Bosman, Giel J C G M; Koenen, Hans J P M; Joosten, Irma

    2016-04-21

    Self-tolerance and immune homeostasis are orchestrated by FOXP3(+)regulatory T cells (Tregs). Recent data have revealed that upon stimulation, Tregs may exhibit plasticity toward a proinflammatory phenotype, producing interleukin 17 (IL-17) and/or interferon γ (IFN-γ). Such deregulation of Tregs may contribute to the perpetuation of inflammatory processes, including graft-versus-host disease. Thus, it is important to identify immunomodulatory factors influencing Treg stability. Platelet-derived microparticles (PMPs) are involved in hemostasis and vascular health and have recently been shown to be intimately involved in (pathogenic) immune responses. Therefore, we investigated whether PMPs have the ability to affect Treg plasticity. PMPs were cocultured with healthy donor peripheral blood-derived Tregs that were stimulated with anti-CD3/CD28 monoclonal antibodies in the presence of IL-2, IL-15, and IL-1β. PMPs prevented the differentiation of peripheral blood-derived Tregs into IL-17- and IFN-γ-producing cells, even in the presence of the IL-17-driving proinflammatory cytokine IL-1β. The mechanism of action by which PMPs prevent Treg plasticity consisted of rapid and selective P-selectin-dependent binding of PMPs to a CCR6(+)HLA-DR(+)memory-like Treg subset and their ability to inhibit Treg proliferation, in part through CXCR3 engagement. The findings that ~8% of Tregs in the circulation of healthy individuals are CD41(+)P-selectin(+)and that distinct binding of patient plasma PMPs to Tregs was observed support in vivo relevance. These findings open the exciting possibility that PMPs actively regulate the immune response at sites of (vascular) inflammation, where they are known to accumulate and interact with leukocytes, consolidating the (vascular) healing process.

  14. Platelet GPIIb supports initial pulmonary retention but inhibits subsequent proliferation of melanoma cells during hematogenic metastasis

    Science.gov (United States)

    Echtler, Katrin; Konrad, Ildiko; Lorenz, Michael; Schneider, Simon; Hofmaier, Sebastian; Plenagl, Florian; Stark, Konstantin; Czermak, Thomas; Tirniceriu, Anca; Eichhorn, Martin; Walch, Axel; Enders, Georg; Massberg, Steffen; Schulz, Christian

    2017-01-01

    Platelets modulate the process of cancer metastasis. However, current knowledge on the direct interaction of platelets and tumor cells is mostly based on findings obtained in vitro. We addressed the role of the platelet fibrinogen receptor glycoprotein IIb (integrin αIIb) for experimental melanoma metastasis in vivo. Highly metastatic B16-D5 melanoma cells were injected intravenously into GPIIb-deficient (GPIIb-/-) or wildtype (WT) mice. Acute accumulation of tumor cells in the pulmonary vasculature was assessed in real-time by confocal videofluorescence microscopy. Arrest of tumor cells was dramatically reduced in GPIIb-/- mice as compared to WT. Importantly, we found that mainly multicellular aggregates accumulated in the pulmonary circulation of WT, instead B16-D5 aggregates were significantly smaller in GPIIb-/- mice. While pulmonary arrest of melanoma was clearly dependent on GPIIb in this early phase of metastasis, we also addressed tumor progression 10 days after injection. Inversely, and unexpectedly, we found that melanoma metastasis was now increased in GPIIb-/- mice. In contrast, GPIIb did not regulate local melanoma proliferation in a subcutaneous tumor model. Our data suggest that the platelet fibrinogen receptor has a differential role in the modulation of hematogenic melanoma metastasis. While platelets clearly support early steps in pulmonary metastasis via GPIIb-dependent formation of platelet-tumor-aggregates, at a later stage its absence is associated with an accelerated development of melanoma metastases. PMID:28253287

  15. 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.

  16. Point-of-care platelet function assays demonstrate reduced responsiveness to clopidogrel, but not aspirin, in patients with Drug-Eluting Stent Thrombosis whilst on dual antiplatelet therapy

    Directory of Open Access Journals (Sweden)

    Dawkins Keith D

    2008-02-01

    Full Text Available Abstract Background To test the hypothesis that point-of-care assays of platelet reactivity would demonstrate reduced response to antiplatelet therapy in patients who experienced Drug Eluting Stent (DES ST whilst on dual antiplatelet therapy compared to matched DES controls. Whilst the aetiology of stent thrombosis (ST is multifactorial there is increasing evidence from laboratory-based assays that hyporesponsiveness to antiplatelet therapy is a factor in some cases. Methods From 3004 PCI patients, seven survivors of DES ST whilst on dual antiplatelet therapy were identified and each matched with two patients without ST. Analysis was performed using (a short Thrombelastogram PlateletMapping™ (TEG and (b VerifyNow Aspirin and P2Y12 assays. TEG analysis was performed using the Area Under the Curve at 15 minutes (AUC15 as previously described. Results There were no differences in responses to aspirin. There was significantly greater platelet reactivity on clopidogrel in the ST group using the Accumetrics P2Y12 assay (183 ± 51 vs. 108 ± 31, p = 0.02 and a trend towards greater reactivity using TEG AUC15 (910 ± 328 vs. 618 ± 129, p = 0.07. 57% of the ST group by TEG and 43% of the ST cases by Accumetrics PRU had results > two standard deviations above the expected mean in the control group. Conclusion This study demonstrates reduced platelet response to clopidogrel in some patients with DES ST compared to matched controls. The availability of point-of-care assays that can detect these responses raises the possibility of prospectively identifying DES patients at risk of ST and manipulating their subsequent risk.

  17. 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.

  18. The abnormal in vitro response to aspirin of platelets from aspirin-sensitive asthmatics is inhibited after inhalation of nedocromil sodium but not of sodium cromoglycate.

    Science.gov (United States)

    Marquette, C H; Joseph, M; Tonnel, A B; Vorng, H; Lassalle, P; Tsicopoulos, A; Capron, A

    1990-01-01

    1. Blood platelets from patients with aspirin-sensitive asthma (ASA) generated cytotoxic mediators in the presence of aspirin. This abnormal in vitro response to aspirin was abolished within 1 h after nedocromil sodium inhalation but not after sodium cromoglycate inhalation. 2. Platelets recovered this reactivity to aspirin by 12 hours after nedocromil sodium treatment of ASA-patients. 3. The in vitro reactivity to aspirin of ASA platelets isolated before inhalation was inhibited in the presence of serum isolated 15 and 60 min after nedocromil sodium inhalation. PMID:2161678

  19. Individualized dual antiplatelet therapy based on platelet function testing in patients undergoing percutaneous coronary intervention: a meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Zhou, Yijiang; Wang, Yanwei; Wu, Yutao; Huang, Chaoyang; Yan, Hui; Zhu, Weiguo; Xu, Weiwei; Zhang, Li; Zhu, Jianhua

    2017-06-15

    High on-treatment platelet reactivity (HPR) represents a strong risk factor for thrombotic events after PCI. We aim to evaluate the efficacy and safety of individualizing intensified dual antiplatelet therapy (DAPT) in PCI-treated patients with HPR based on platelet function testing (PFT). Electronic databases were searched for randomized control trials that reported the clinical outcomes of using an intensified antiplatelet protocol with P2Y12 receptor inhibitor comparing with standard maintenance dose of clopidogrel on the basis of platelet function testing. Clinical endpoints were assessed. From 2005 to 2016, thirteen clinical studies comprising 7290 patients were included for analysis. Compared with standard antiplatelet therapy with clopidogrel, the intensified protocol based on platelet function testing was associated with a significant reduction in major adverse cardiovascular events (RR:0.55, 95% CI: 0.36-0.84, p = 0.005), cardiovascular death (RR:0.60, 95% CI: 0.38-0.96, p = 0.03), stent thrombosis (RR:0.58, 95% CI: 0.36-0.93, p = 0.02) and target vessel revascularization (RR:0.33, 95% CI: 0.14-0.76, p = 0.009). No significant difference was found in the rate of bleeding events between intensified and standard protocol. Compared with standard clopidogrel therapy, individualized intensified antiplatelet therapy on the basis of platelet reactivity testing reduces the incidence of cardiovascular events in patient undergoing PCI, without increasing the risk of bleeding.

  20. 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.

  1. Delphinidin, a dietary anthocyanidin, inhibits platelet-derived growth factor ligand/receptor (PDGF/PDGFR) signaling.

    Science.gov (United States)

    Lamy, Sylvie; Beaulieu, Edith; Labbé, David; Bédard, Valérie; Moghrabi, Albert; Barrette, Stéphane; Gingras, Denis; Béliveau, Richard

    2008-05-01

    Most cancers are dependent on the growth of tumor blood vessels and inhibition of tumor angiogenesis may thus provide an efficient strategy to retard or block tumor growth. Recently, tumor vascular targeting has expanded to include not only endothelial cells (ECs) but also smooth muscle cells (SMCs), which contribute to a mature and functional vasculature. We have reported previously that delphinidin, a major biologically active constituent of berries, inhibits the vascular endothelial growth factor-induced phosphorylation of vascular endothelial growth factor receptor-2 and blocks angiogenesis in vitro and in vivo. In the present study, we show that delphinidin also inhibits activation of the platelet-derived growth factor (PDGF)-BB receptor-beta [platelet-derived growth factor receptor-beta (PDGFR-beta)] in SMC and that this inhibition may contribute to its antitumor effect. The inhibitory effect of delphinidin on PDGFR-beta was very rapid and led to the inhibition of PDGF-BB-induced activation of extracellular signal-regulated kinase (ERK)-1/2 signaling and of the chemotactic motility of SMC, as well as the differentiation and stabilization of EC and SMC into capillary-like tubular structures in a three-dimensional coculture system. Using an anthocyan-rich extract of berries, we show that berry extracts were able to suppress the synergistic induction of vessel formation by basic fibroblast growth factor-2 and PDGF-BB in the mouse Matrigel plug assay. Oral administration of the berry extract also significantly retarded tumor growth in a lung carcinoma xenograft model. Taken together, these results provide new insight into the molecular mechanisms underlying the antiangiogenic activity of delphinidin that will be helpful for the development of dietary-based chemopreventive strategies.

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

    NARCIS (Netherlands)

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

    2006-01-01

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

  3. Inhibition of blood platelet adhesion and secretion by different phenolics from Yucca schidigera Roezl. bark.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara; Stochmal, Anna; Oleszek, Wieslaw

    2005-02-01

    Yucca schidigera is a plant that grows in Mexico, and it has a very high level of saponins and phenolic compounds with antioxidant action. The products of Y. schidigera are used as food additives and have a generally recognized as safe label. This study investigated the antiplatelet mechanisms of four phenolic compounds. We investigated antiplatelet mechanisms of the phenolic compounds trans-3,4',5-trihydroxystilbene (trans-resveratrol), trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene, and yuccaols A and C that had been isolated from the bark of Y. schidigera by studying their effects on the first step of platelet activation, i.e., platelet adhesion to collagen and fibrinogen. The effects of these compounds on the release of adenine nucleotides, proteins, and beta-N-acetyl-glycosaminidase (a marker of lysosomal secretion) from blood platelets activated by thrombin were also studied. These different phenolic compounds (1 to 25 microg/mL) and their extracts decreased platelet adhesion and secretion. Resveratrol and yucca extract were more reactive in decreasing these processes than were other tested phenolic compounds.

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

  5. An innovative strategy for dual inhibitor design and its application in dual inhibition of human thymidylate synthase and dihydrofolate reductase enzymes.

    Directory of Open Access Journals (Sweden)

    Mahreen Arooj

    Full Text Available Due to the diligence of inherent redundancy and robustness in many biological networks and pathways, multitarget inhibitors present a new prospect in the pharmaceutical industry for treatment of complex diseases. Nevertheless, to design multitarget inhibitors is concurrently a great challenge for medicinal chemists. We have developed a novel computational approach by integrating the affinity predictions from structure-based virtual screening with dual ligand-based pharmacophore to discover potential dual inhibitors of human Thymidylate synthase (hTS and human dihydrofolate reductase (hDHFR. These are the key enzymes in folate metabolic pathway that is necessary for the biosynthesis of RNA, DNA, and protein. Their inhibition has found clinical utility as antitumor, antimicrobial, and antiprotozoal agents. A druglike database was utilized to perform dual-target docking studies. Hits identified through docking experiments were mapped over a dual pharmacophore which was developed from experimentally known dual inhibitors of hTS and hDHFR. Pharmacophore mapping procedure helped us in eliminating the compounds which do not possess basic chemical features necessary for dual inhibition. Finally, three structurally diverse hit compounds that showed key interactions at both active sites, mapped well upon the dual pharmacophore, and exhibited lowest binding energies were regarded as possible dual inhibitors of hTS and hDHFR. Furthermore, optimization studies were performed for final dual hit compound and eight optimized dual hits demonstrating excellent binding features at target systems were also regarded as possible dual inhibitors of hTS and hDHFR. In general, the strategy used in the current study could be a promising computational approach and may be generally applicable to other dual target drug designs.

  6. Actin filaments and microtubule dual-granule transport in human adhered platelets: the role of alpha-dystrobrevins.

    Science.gov (United States)

    Cerecedo, Doris; Cisneros, Bulmaro; Mondragón, Ricardo; González, Sirenia; Galván, Iván J

    2010-04-01

    Upon activation with physiological stimuli, human platelets undergo morphological changes, centralizing their organelles and secreting effector molecules at the site of vascular injury. Previous studies have indicated that the actin filaments and microtubules of suspension-activated platelets play a critical role in granule movement and exocytosis; however, the participation of these cytoskeleton elements in adhered platelets remains unexplored. alpha- and beta-dystrobrevin members of the dystrophin-associated protein complex in muscle and non-muscle cells have been described as motor protein receptors that might participate in the transport of cellular components in neurons. Recently, we characterized the expression of dystrobrevins in platelets; however, their functional diversity within this cellular model had not been elucidated. The present study examined the contribution of actin filaments and microtubules in granule trafficking during the platelet adhesion process using cytoskeleton-disrupting drugs, quantification of soluble P-selectin, fluorescence resonance transfer energy analysis and immunoprecipitation assays. Likewise, we assessed the interaction of alpha-dystrobrevins with the ubiquitous kinesin heavy chain. Our results strongly suggest that microtubules and actin filaments participate in the transport of alpha and dense granules in the platelet adhesion process, during which alpha-dystrobrevins play the role of regulatory and adaptor proteins that govern trafficking events.

  7. Disrupting functional interactions between platelet chemokines inhibits atherosclerosis in hyperlipidemic mice

    DEFF Research Database (Denmark)

    Koenen, RR; Hundelshausen, P; Nesmelova, IV

    2009-01-01

    Atherosclerosis is characterized by chronic inflammation of the arterial wall due to chemokine-driven mononuclear cell recruitment. Activated platelets can synergize with chemokines to exacerbate atherogenesis; for example, by deposition of the chemokines platelet factor-4 (PF4, also known as CXCL4...... and by enhanced monocyte arrest resulting from CCL5-CXCL4 interactions. The CCL5 antagonist Met-RANTES reduces diet-induced atherosclerosis; however, CCL5 antagonism may not be therapeutically feasible, as suggested by studies using Ccl5-deficient mice which imply that direct CCL5 blockade would severely...... monocyte recruitment and reducing atherosclerosis without the aforementioned side effects. These results establish the in vivo relevance of chemokine heteromers and show the potential of targeting heteromer formation to achieve therapeutic effects...

  8. Dual-action hypoglycemic and hypocholesterolemic agents that inhibit glycogen phosphorylase and lanosterol demethylase.

    Science.gov (United States)

    Harwood, H James; Petras, Stephen F; Hoover, Dennis J; Mankowski, Dayna C; Soliman, Victor F; Sugarman, Eliot D; Hulin, Bernard; Kwon, Younggil; Gibbs, E Michael; Mayne, James T; Treadway, Judith L

    2005-03-01

    Diabetic dyslipidemia requires simultaneous treatment with hypoglycemic agents and lipid-modulating drugs. We recently described glycogen phosphorylase inhibitors that reduce glycogenolysis in cells and lower plasma glucose in ob/ob mice (J. Med. Chem., 41: 2934, 1998). In evaluating the series prototype, CP-320626, in dogs, up to 90% reduction in plasma cholesterol was noted after 2 week treatment. Cholesterol reductions were also noted in ob/ob mice and in rats. In HepG2 cells, CP-320626 acutely and dose-dependently inhibited cholesterolgenesis without affecting fatty acid synthesis. Inhibition occurred together with a dose-dependent increase in the cholesterol precursor, lanosterol, suggesting that cholesterolgenesis inhibition was due to lanosterol 14alpha-demethylase (CYP51) inhibition. In ob/ob mice, acute treatment with CP-320626 resulted in a decrease in hepatic cholesterolgenesis with concomitant lanosterol accumulation, further implicating CYP51 inhibition as the mechanism of cholesterol lowering in these animals. CP-320626 and analogs directly inhibited rhCYP51, and this inhibition was highly correlated with HepG2 cell cholesterolgenesis inhibition (R2 = 0.77). These observations indicate that CP-320626 inhibits cholesterolgenesis via direct inhibition of CYP51, and that this is the mechanism whereby CP-320626 lowers plasma cholesterol in experimental animals. Dual-action glycogenolysis and cholesterolgenesis inhibitors therefore have the potential to favorably affect both the hyperglycemia and the dyslipidemia of type 2 diabetes.

  9. 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 (pintegral 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 (pintegral 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.

  10. The polyphenol-rich extract from grape seeds inhibits platelet signaling pathways triggered by both proteolytic and non-proteolytic agonists.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara; Stochmal, Anna; Oleszek, Wiesław

    2012-01-01

    Mechanisms involved in the reduction of blood platelet functions by various plant extract, including the grape seeds extract (rich in phenolic compounds, a mixture of about 95% oligomeric phenols; GSE) are still unclear. In the literature there are few papers describing studies on the effects of GSE on selected element of hemostasis. The aim of our study was to establish and compare the influence of GSE (at final dose of 0.625-50 µg/ml) and resveratrol (3,4',5 - trihydroxystilben), a phenolic compound synthesized in grapes and vegetables and presents in wine, which has been supposed to be beneficial for the prevention of cardiovascular events, on different steps of platelet activation. We measured the effects of GSE and resveratrol on platelet aggregation, the surface expression of P-selectin, platelet microparticle formation (PMP), and superoxide anion radicals ([Formula: see text]) production in blood platelets stimulated by TRAP and thrombin. P-selectin expression and PMP formation were measured by a flow cytometer. In gel-filtered platelets activated by thrombin or TRAP and treated with different concentrations of GSE (1.25-50 µg/ml) a significant decrease of P-selectin expression, PMP formation and platelet aggregation was observed. GSE caused also a dose-dependent reduction of [Formula: see text] produced in platelets activated by TRAP or thrombin. Our present results indicate that GSE inhibits platelet signaling pathways trigged by both proteolytic (thrombin) and non-proteolytic agonist (TRAP). In the comparative studies, GSE was found to be more effective antiplatelet factor, than the solution of pure resveratrol. Thus, the polyphenol-rich extract from grape seeds can be useful as the protecting factor against cardiovascular diseases.

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

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    Qingrong eQu

    2016-03-01

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

  12. Inhibition of platelet function by abciximab or high-dose tirofiban in patients with STEMI undergoing primary PCI: a randomised trial

    Science.gov (United States)

    van Werkum, J.W.; Gerritsen, W.B.M.; Kelder, J.C.; Hackeng, C.M.; Ernst, S.M.; Deneer, V.H.M.; Suttorp, M.J.; Rensing, B.J.W.M.; Plokker, H.W.M.; ten Berg, J.M.

    2007-01-01

    Background In patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI, few data exist on the magnitude of platelet activation, aggregation and dosing of glycoprotein (GP) IIb/IIIa receptor inhibitors. Methods Sixty STEMI patients were randomised to abciximab, to high-dose tirofiban or to no additional GP IIb/IIIa inhibitor treatment. Platelet activation (P-selectin expression) was measured using flow cytometry and the level of inhibition of platelet aggregation was assessed using the Plateletworks assay. Additionally, the PFA-100 with the collagen/adenosine-diphosphate cartridge (CADP) was used to compare the levels of platelet inhibition. All measurements were performed at baseline (T0), immediately after (T1), 30 minutes (T2), 60 minutes (T3) and 120 minutes (T4) after primary PCI. Results The level of platelet activation in both GP IIb/IIIa receptor inhibitor treated groups was significantly lower compared with the control group at all time points after primary PCI (p=0.04). Also the administration of the currently recommended dose of abciximab resulted in significantly lower levels of inhibition of aggregation compared with high-dose tirofiban (p<0.0001). In addition, the CADP closure times were significantly prolonged in both GP IIb/IIIa inhibitor treated groups compared with the control group at time points T1 (p=0.006) and T4 (p<0.0001). Conclusion The administration of high-dose tirofiban resulted in a significantly higher inhibition of platelet aggregation compared with the currently recommended dose of abciximab. Large clinical trials are needed to assess whether this laboratory superiority of high-dose tirofiban translates into higher clinical efficacy. (Neth Heart J 2007;15:375-81.18176639) PMID:18176639

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

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

    1987-11-01

    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of ({sup 3}H)serotonin, or alter the dose-responsive binding of {sup 125}I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF.

  14. Disrupting functional interactions between platelet chemokines inhibits atherosclerosis in hyperlipidemic mice.

    Science.gov (United States)

    Koenen, Rory R; von Hundelshausen, Philipp; Nesmelova, Irina V; Zernecke, Alma; Liehn, Elisa A; Sarabi, Alisina; Kramp, Birgit K; Piccinini, Anna M; Paludan, Søren R; Kowalska, M Anna; Kungl, Andreas J; Hackeng, Tilman M; Mayo, Kevin H; Weber, Christian

    2009-01-01

    Atherosclerosis is characterized by chronic inflammation of the arterial wall due to chemokine-driven mononuclear cell recruitment. Activated platelets can synergize with chemokines to exacerbate atherogenesis; for example, by deposition of the chemokines platelet factor-4 (PF4, also known as CXCL4) and RANTES (CCL5), triggering monocyte arrest on inflamed endothelium. Homo-oligomerization is required for the recruitment functions of CCL5, and chemokine heteromerization has more recently emerged as an additional regulatory mechanism, as evidenced by a mutual modulation of CXCL8 and CXCL4 activities and by enhanced monocyte arrest resulting from CCL5-CXCL4 interactions. The CCL5 antagonist Met-RANTES reduces diet-induced atherosclerosis; however, CCL5 antagonism may not be therapeutically feasible, as suggested by studies using Ccl5-deficient mice which imply that direct CCL5 blockade would severely compromise systemic immune responses, delay macrophage-mediated viral clearance and impair normal T cell functions. Here we determined structural features of CCL5-CXCL4 heteromers and designed stable peptide inhibitors that specifically disrupt proinflammatory CCL5-CXCL4 interactions, thereby attenuating monocyte recruitment and reducing atherosclerosis without the aforementioned side effects. These results establish the in vivo relevance of chemokine heteromers and show the potential of targeting heteromer formation to achieve therapeutic effects.

  15. Causes, Timing, and Impact of Dual Antiplatelet Therapy Interruption for Surgery (from the Patterns of Non-adherence to Anti-platelet Regimens In Stented Patients Registry).

    Science.gov (United States)

    Schoos, Mikkel; Chandrasekhar, Jaya; Baber, Usman; Bhasin, Aarti; Sartori, Samantha; Aquino, Melissa; Vogel, Birgit; Farhan, Serdar; Sorrentino, Sabato; Kini, Annapoorna; Kruckoff, Mitchell; Moliterno, David; Henry, Timothy D; Weisz, Giora; Gibson, C Michael; Iakovou, Ioannis; Colombo, Antonio; Steg, P Gabriel; Witzenbichler, Bernhard; Chieffo, Alaide; Cohen, David; Stuckey, Thomas; Ariti, Cono; Dangas, George; Pocock, Stuart; Mehran, Roxana

    2017-09-15

    Temporary interruption of dual antiplatelet therapy (DAPT) is not infrequently required in patients undergoing percutaneous coronary intervention (PCI). We sought to describe the procedures and outcomes associated with DAPT interruption in patients treated with DAPT following successful PCI from the Patterns of non-adherence to anti-platelet regimens in stented patients registry (n = 5018). DAPT interruption was prespecified as physician recommended cessation for antiplatelet agent was interrupted in 57.2% cases and interruption was frequently recommended by noncardiologists (51.3%). Where type of surgery was reported, majority of DAPT interruptions occurred for minor surgery (68.4% vs 31.6%) and a similar cessation pattern of single versus dual antiplatelet cessation was observed regardless of minor or major surgery. Subsequent to DAPT interruption, 12 patients (2.4%) experienced 1 thrombotic event each, of which 5 (1.0%) occurred during the interruption period. All events occurred in patients who either stopped both agents (8 of 12) or clopidogrel-only (4 of 12), with no events occurring due to aspirin cessation alone. In conclusion, in the Patterns of Non-adherence to Anti-platelet Regiments in Stented Patients registry, 1 in 10 patients were recommended DAPT interruption for surgery within 2 years of PCI. Interruption was more common for a single agent rather than both antiplatelet agents regardless of severity of surgery, and was frequently recommended by noncardiologists. Only 1% of patients with DAPT interruption experienced a subsequent thrombotic event during the interruption period, which mainly occurred in patients stopping both antiplatelet agents. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Celecoxib interferes to a limited extent with aspirin-mediated inhibition of platelets aggregation.

    Science.gov (United States)

    Ruzov, Mark; Rimon, Gilad; Pikovsky, Oleg; Stepensky, David

    2016-02-01

    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. 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. 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. 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. © 2015 The British Pharmacological Society.

  17. RIC-3 phosphorylation enables dual regulation of excitation and inhibition of Caenorhabditis elegans muscle.

    Science.gov (United States)

    Safdie, Gracia; Liewald, Jana F; Kagan, Sarah; Battat, Emil; Gottschalk, Alexander; Treinin, Millet

    2016-10-01

    Brain function depends on a delicate balance between excitation and inhibition. Similarly, Caenorhabditis elegans motor system function depends on a precise balance between excitation and inhibition, as C. elegans muscles receive both inhibitory, GABAergic and excitatory, cholinergic inputs from motor neurons. Here we show that phosphorylation of the ER-resident chaperone of nicotinic acetylcholine receptors, RIC-3, leads to increased muscle excitability. RIC-3 phosphorylation at Ser-164 depends on opposing functions of the phosphatase calcineurin (TAX-6), and of the casein kinase II homologue KIN-10. Effects of calcineurin down-regulation and of phosphorylated RIC-3 on muscle excitability are mediated by GABAA receptor inhibition. Thus RIC-3 phosphorylation enables effects of this chaperone on GABAA receptors in addition to nAChRs. This dual effect provides coordinated regulation of excitation and inhibition and enables fine-tuning of the excitation-inhibition balance. Moreover, regulation of inhibitory GABAA signaling by calcineurin, a calcium- and calmodulin-dependent phosphatase, enables homeostatic balancing of excitation and inhibition.

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

    Directory of Open Access Journals (Sweden)

    Olivia A Lin

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

  19. 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 (pactivity, 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.

  20. Dual effectiveness of sodium chlorite for enzymatic browning inhibition and Escherichia coli inactivation on fresh-cut apples

    Science.gov (United States)

    This study investigated the dual effectiveness of sodium chlorite (SC) for browning inhibition and microbial inactivation on fresh-cut apples. The SC treatment exhibited a strong inhibition on browning reaction of fresh-cut Red Delicious apples during cold storage. Test results from examination of t...

  1. 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.

  2. 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.

  3. Dual effect of metformin on growth inhibition and oestradiol production in breast cancer cells.

    Science.gov (United States)

    Rice, S; Pellat, L; Ahmetaga, A; Bano, G; Mason, H D; Whitehead, S A

    2015-04-01

    Evidence has been accumulating for a role for metformin in reducing breast cancer risk in post-menopausal women. It inhibits growth of breast cancer cells via several mechanisms, primarily the AMPK/mTOR signalling pathway. Another possible protective mechanism may be the ability of metformin to inhibit aromatase activity. In the present study, we investigated the effects of metformin on the basal growth of MCF-7 cells, after oestradiol (E2) stimulation and after the inhibition of mTOR by rapamycin. Secondly, we investigated the effects of metformin on the activity of a number of steroidogenic enzymes and the mRNA expression of aromatase and steroid sulphatase (STS). High doses of metformin significantly inhibited both basal and oestrogen-stimulated cell division. Low-dose rapamycin (10-10 M) did not inhibit growth, but the addition of metformin induced a significant reduction in growth. High-dose rapamycin (10-8 M) inhibited growth, and this was further attenuated by the addition of metformin. Exposure to low (10-7 M) and high (10-4 M) doses of metformin for 7-10 days significantly reduced the conversion of androstenedione (ANDRO) and testosterone (TESTO) (both requiring aromatase), but not the conversion of oestrone or oestrone sulphate (ES) via 17β-hydroxysteroid dehydrogenase/sulphatase to E2. This attenuation was via a downregulation in the expression of total aromatase mRNA and promoter II, whilst the expression of sulphatase was unaffected by metformin. In conclusion, plasma levels of metformin have a dual therapeutic action, first by directly inhibiting cell proliferation which can be augmented by rapamycin analogues, and secondly, by inhibiting aromatase activity and reducing the local conversion of androgens to E2.

  4. Platelet-Derived Growth Factor-Receptor α Strongly Inhibits Melanoma Growth In Vitro and In Vivo1

    Science.gov (United States)

    Faraone, Debora; Aguzzi, Maria Simona; Toietta, Gabriele; Facchiano, Angelo M; Facchiano, Francesco; Magenta, Alessandra; Martelli, Fabio; Truffa, Silvia; Cesareo, Eleonora; Ribatti, Domenico; Capogrossi, Maurizio C; Facchiano, Antonio

    2009-01-01

    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. PMID:19649203

  5. 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.

  6. Greater clinical benefit of more intensive oral antiplatelet therapy with prasugrel in patients with diabetes mellitus in the trial to assess improvement in therapeutic outcomes by optimizing platelet inhibition with prasugrel-Thrombolysis in Myocardial Infarction 38.

    NARCIS (Netherlands)

    Wiviott, S.D.; Braunwald, E.; Angiolillo, D.J.; Meisel, S.; Dalby, A.J.; Verheugt, F.W.A.; Goodman, S.G.; Corbalan, R.; Purdy, D.A.; Murphy, S.A.; McCabe, C.H.; Antman, E.M.

    2008-01-01

    BACKGROUND: Patients with diabetes mellitus (DM) are at high risk for recurrent cardiovascular events after acute coronary syndromes, in part because of increased platelet reactivity. The Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel-Thrombolysi

  7. 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.

  8. Staphylococcal SSL5 binding to human leukemia cells inhibits cell adhesion to endothelial cells and platelets

    NARCIS (Netherlands)

    Walenkamp, Annemiek M. E.; Bestebroer, Jovanka; Boer, Ingrid G. J.; Kruizinga, Roeline; Verheul, Henk M.; van Strijp, Jos A. G.; de Haas, Carla J. C.

    2010-01-01

    Bacterial proteins provide promising tools for novel anticancer therapies. Staphylococcal superantigen-like 5 (SSL5) was recently described to bind P-selectin glycoprotein ligand-1 (PSGL-1) on leukocytes and to inhibit neutrophil rolling on a P-selectin surface. As leukocytes and tumor cells share m

  9. Novel dual-mode immunomagnetic method for studying reactivation of nerve agent-inhibited butyrylcholinesterase.

    Science.gov (United States)

    Abney, Carter W; Knaack, Jennifer L S; Ali, Ahmed A I; Johnson, Rudolph C

    2013-05-20

    A novel immunomagnetic method has been developed for the simultaneous measurement of organophosphorus nerve agent (OPNA) adducts to butyrylcholinesterase (BuChE) and free OPNAs in serum. This new approach, deemed dual-mode immunomagnetic analysis (Dual-Mode IMA), combines immunomagnetic separation (IMS) and immunomagnetic scavenging (IMSc) and has been used to measure the effectiveness of cholinesterase reactivators on OPNA-inhibited BuChE in serum. BuChE inhibited by the nerve agent VX, uninhibited BuChE, and unbound VX were measured up to 1 h after the addition of oxime reactivators pralidoxime (2-PAM) and obidoxime. IMS experiments consisted of extracting BuChE and VX-BuChE serum adducts using antibutyrylcholinesterase monoclonal antibodies conjugated to protein-G ferromagnetic particles. In a parallel set of experiments using IMSc, BuChE-coated magnetic beads were used to extract free VX from protein-depleted serum. Adducts from both IMS and IMSc were analyzed using a published IMS liquid chromatography tandem mass spectrometry (IMS-LC-MS/MS) protocol, which has also been demonstrated with other OPNAs. By applying this Dual-Mode IMA approach, 2-PAM was observed to be more potent than obidoxime in reactivating VX-adducted BuChE. VX-BuChE peptide concentrations initially measured at 19.7 ± 0.7 ng/mL decreased over 1 h to 10.6 ± 0.6 ng/mL when reactivated with 2-PAM and 14.4 ± 1.2 ng/mL when reactivated with obidoxime. These experiments also show that previously published IMS-LC-MS/MS analyses are compatible with serum treated with oximes. Dual-Mode IMA is the first immunoaffinity method developed for the simultaneous measurement of OPNA adducted BuChE, unadducted BuChE, and free nerve agent in serum and is a promising new tool for studying reactivator effectiveness on cholinesterases inhibited by nerve agents.

  10. A Metabolomic Approach to Target Compounds from the Asteraceae Family for Dual COX and LOX Inhibition

    Directory of Open Access Journals (Sweden)

    Daniela A. Chagas-Paula

    2015-07-01

    Full Text Available The application of metabolomics in phytochemical analysis is an innovative strategy for targeting active compounds from a complex plant extract. Species of the Asteraceae family are well-known to exhibit potent anti-inflammatory (AI activity. Dual inhibition of the enzymes COX-1 and 5-LOX is essential for the treatment of several inflammatory diseases, but there is not much investigation reported in the literature for natural products. In this study, 57 leaf extracts (EtOH-H2O 7:3, v/v from different genera and species of the Asteraceae family were tested against COX-1 and 5-LOX while HPLC-ESI-HRMS analysis of the extracts indicated high diversity in their chemical compositions. Using O2PLS-DA (R2 > 0.92; VIP > 1 and positive Y-correlation values, dual inhibition potential of low-abundance metabolites was determined. The O2PLS-DA results exhibited good validation values (cross-validation = Q2 > 0.7 and external validation = P2 > 0.6 with 0% of false positive predictions. The metabolomic approach determined biomarkers for the required biological activity and detected active compounds in the extracts displaying unique mechanisms of action. In addition, the PCA data also gave insights on the chemotaxonomy of the family Asteraceae across its diverse range of genera and tribes.

  11. 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.

  12. Losartan inhibits the adhesion of rat platelets to fibrillar collagen--a potential role of nitric oxide and prostanoids.

    Science.gov (United States)

    Matys, T; Chabielska, E; Pawlak, R; Kucharewicz, I; Buczko, W

    2000-12-01

    The aim of the study was to evaluate the effect of losartan on rat platelet adhesion to fibrillar collagen. Washed platelets were counted before and after 15 minutes incubation with collagen (50 microg/ml) and the percentage of adhering platelets was calculated as the index of their adhesion. When the platelets were incubated with collagen 40.8 +/- 0.3% of the platelets adhered. Losartan produced a dose dependent decrease in a number of adhering platelets both when the drug was administered to the animals ex vivo at doses of 3, 10 and 30 mg/kg (p < 0.01-0.001) or was added to the preparation of washed platelets in vitro in concentrations of 10(-8)-10(-5) M (p < 0.01-0.001). In the next step of the study we assessed the influence of L-NAME (10 mg/kg ex vivo, 30 microM in vitro) and indomethacin (2.5 mg/kg ex vivo, 30 microM in vitro) on the antiadhesive effect of losartan (10 mg/kg ex vivo, 10(-6) M in vitro). Blockade of nitric oxide synthase with L-NAME partially reversed the antiadhesive effect of losartan both ex vivo and in vitro. Indomethacin diminished the inhibitory effect of losartan on platelet adhesion when administered ex vivo, but it failed to modify this parameter when added to the suspension of platelets in vitro. In conclusion, losartan reduces platelet adhesion to fibrillar collagen in a dose-dependent manner. The observed action of losartan seems to be mediated mainly by endothelium- and platelet-derived nitric oxide.

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

    Science.gov (United States)

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

    2014-01-01

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

  14. High residual platelet reactivity during dual antiplatelet therapy, found by optical aggregometry and the rate of atherothrombotic complications after coronary artery stenting in patients with ischemic heart disease in clinical practice

    OpenAIRE

    N. F. Puchinyan; N. V. Furman; P. V. Dolotovskaya; L. L. Malinova

    2016-01-01

    Aim. To study the prevalence of high residual platelet reactivity (HRPR) during the dual antiplatelet therapy (DAT) with acetylsalicylic acid (ASA) and clopidogrel by optical aggregometry in patients with ischemic heart disease (IHD) after percutaneous transluminal coronary angioplasty (PTCA) in clinical practice, as well as to determine its value for the prediction of clinical course and outcome of disease.Material and methods. Patients after PTCA and during DAT were included into the study....

  15. Effects of cigarette smoking on platelet reactivity during P2Y12 inhibition in patients with myocardial infarction undergoing drug-eluting stent implantation: results from the prospective cigarette smoking on platelet reactivity (COPTER) study.

    Science.gov (United States)

    Patti, Giuseppe; Polacco, Marina; Taurino, Ester; Gaudio, Carlo; Greco, Cesare

    2016-05-01

    Interaction between cigarette smoking and efficacy of oral antiplatelet drugs is not definitely elucidated. We evaluated the effects of cigarette smoking on platelet reactivity in patients receiving different oral P2Y12 antagonists after myocardial infarction (MI) and drug-eluting stent (DES) implantation. Two-hundred-five consecutive current smokers receiving DES implantation after ST-segment elevation MI were enrolled. All patients were aspirin-treated and were on chronic therapy with clopidogrel (N = 59), prasugrel (N = 71) or ticagrelor (N = 75); by protocol, all patients at baseline had no high on-treatment platelet reactivity by the VerifyNow P2Y12 assay. Platelet reactivity, expressed by P2Y12 reaction units (PRU), was measured in all patients at baseline (T0), after a 15-day period of smoking cessation (T1) and after further 15 days of smoking resumption (T2). In the overall population there was a modest, albeit significant, reduction of PRU values from T0 to T1 (from 173 ± 14 to 165 ± 17, P smoking was associated with re-increase of platelet reactivity (from 165 ± 17 at T1 to 170 ± 17 at T2, P = 0.0002). These variations were consistent in the subgroups receiving clopidogrel, prasugrel or ticagrelor and were irrespective of the number of cigarettes smoked. In conclusion, cigarette smoking weakly influences antiplatelet effects of oral P2Y12 inhibition and this was irrespective of the type of antiplatelet agent; thus, interaction between cigarette smoking and efficacy of oral antiplatelet drugs is modest and unlikely translates into clinical effects (ClinicalTrials.gov Identifier: NCT02026713).

  16. Quercetin diacylglycoside analogues showing dual inhibition of DNA gyrase and topoisomerase IV as novel antibacterial agents.

    Science.gov (United States)

    Hossion, Abugafar M L; Zamami, Yoshito; Kandahary, Rafiya K; Tsuchiya, Tomofusa; Ogawa, Wakano; Iwado, Akimasa; Sasaki, Kenji

    2011-06-09

    A structure-guided molecular design approach was used to optimize quercetin diacylglycoside analogues that inhibit bacterial DNA gyrase and topoisomerase IV and show potent antibacterial activity against a wide spectrum of relevant pathogens responsible for hospital- and community-acquired infections. In this paper, such novel 3,7-diacylquercetin, quercetin 6''-acylgalactoside, and quercetin 2'',6''-diacylgalactoside analogues of lead compound 1 were prepared to assess their target specificities and preferences in bacteria. The significant enzymatic inhibition of both Escherichia coli DNA gyrase and Staphylococcus aureus topoIV suggest that these compounds are dual inhibitors. Most of the investigated compounds exhibited pronounced inhibition with MIC values ranging from 0.13 to 128 μg/mL toward the growth of multidrug-resistant Gram-positive methicillin-resistant S. aureus, methicillin sensitive S. aureus, vancomycin-resistant enterococci (VRE), vancomycin intermediate S. aureus, and Streptococcus pneumoniae bacterial strains. Structure-activity relationship studies revealed that the acyl moiety was absolutely essential for activity against Gram-positive organisms. The most active compound 5i was 512-fold more potent than vancomycin and 16-32-fold more potent than 1 against VRE strains. It also has realistic in situ intestinal absorption in rats and showed very low acute toxicity in mice. So far, this compound can be regarded as a leading antibacterial agent.

  17. Immunotoxin targeting glypican-3 regresses liver cancer via dual inhibition of Wnt signalling and protein synthesis.

    Science.gov (United States)

    Gao, Wei; Tang, Zhewei; Zhang, Yi-Fan; Feng, Mingqian; Qian, Min; Dimitrov, Dimiter S; Ho, Mitchell

    2015-03-11

    Glypican-3 is a cell surface glycoprotein that associates with Wnt in liver cancer. We develop two antibodies targeting glypican-3, HN3 and YP7. The first antibody recognizes a functional epitope and inhibits Wnt signalling, whereas the second antibody recognizes a C-terminal epitope but does not inhibit Wnt signalling. Both are fused to a fragment of Pseudomonas exotoxin A (PE38) to create immunotoxins. Interestingly, the immunotoxin based on HN3 (HN3-PE38) has superior antitumor activity as compared with YP7 (YP7-PE38) both in vitro and in vivo. Intravenous administration of HN3-PE38 alone, or in combination with chemotherapy, induces regression of Hep3B and HepG2 liver tumour xenografts in mice. This study establishes glypican-3 as a promising candidate for immunotoxin-based liver cancer therapy. Our results demonstrate immunotoxin-induced tumour regression via dual mechanisms: inactivation of cancer signalling via the antibody and inhibition of protein synthesis via the toxin.

  18. 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.

  19. PD98059 Inhibited the Activation of Pancreatic Stellate Cells Mediated by Platelet-Derived Growth Factor BB in Rats

    Institute of Scientific and Technical Information of China (English)

    WAN Yuantai; WANG Tiancai; ZHAO Qiu

    2005-01-01

    Summary: To determine the biological effects of extracelluar signal regulated kinase (ERK) specific inhibitor PD98059 on pancreatic stellate cells (PSCs) activated by platelet-derived factor-BB (PDGF-BB), cultured rat PSCs were co-incubated at 37 ℃ for 24 h with 25 ng/ml PDGF-BB and different doses of PD98059 (ranging from 5 ng/ml to 40 ng/ml). Expression of pERK1 protein was detected by Western blot and collagen α1 (Ⅰ) mRNA was tested by reverse transcription-polymerase chain reaction (RT-PCR). Our results showed that there were statistical differences in the expression of pERK1 protein in all groups. Expression of pERK1 protein was up-regulated in the group treated by PDGF-BB, and gradually down-regulated in the other groups treated by PD98059 of different doses. An excellent positive correlation was revealed between the inhibitory effect and PD98059 concentrations. It was also observed that the expression of collagen α1 (Ⅰ) mRNA had similar response to pERK1. The level of collagen α1 (Ⅰ) mRNA was the highest in the PDGF-BB group, and gradually reduced in the other groups treated by PD98059 of different doses. It is concluded that expression of pERK1 protein and collagen α1 (Ⅰ) mRNA was up-regulated in rat PSCs activated by PDGF-BB. Meanwhile, PD98059 could inhibit PSCs activation mediated by PDGF. It is suggested that ERK1 protein plays an important role on PSCs activation mediated by PDGF signal pathway.

  20. Inhibition of platelet activation prevents the P-selectin and integrin-dependent accumulation of cancer cell microparticles and reduces tumor growth and metastasis in vivo.

    Science.gov (United States)

    Mezouar, Soraya; Darbousset, Roxane; Dignat-George, Françoise; Panicot-Dubois, Laurence; Dubois, Christophe

    2015-01-15

    Venous thromboembolism constitutes one of the main causes of death during the progression of a cancer. We previously demonstrated that tissue factor (TF)-bearing cancer cell-derived microparticles accumulate at the site of injury in mice developing a pancreatic cancer. The presence of these microparticles at the site of thrombosis correlates with the size of the platelet-rich thrombus. The objective of this study was to determine the involvement of TF expressed by cancer cell-derived microparticles on thrombosis associated with cancer. We observed that pancreatic cancer cell derived microparticles expressed TF, its inhibitor tissue factor pathway inhibitor (TFPI) as well as the integrins αvβ1 and αvβ3. In mice bearing a tumor under-expressing TF, a significant decrease in circulating TF activity associated with an increase bleeding time and a 100-fold diminished fibrin generation and platelet accumulation at the site of injury were observed. This was mainly due to the interaction of circulating cancer cell-derived microparticles expressing TFPI with activated platelets and fibrinogen. In an ectopic model of cancer, treatment of mice with Clopidogrel, an anti-platelet drug, decreased the size of the tumors and restored hemostasis by preventing the accumulation of cancer cell-derived microparticles at the site of thrombosis. In a syngeneic orthotopic model of pancreatic cancer Clopidogrel also significantly inhibited the development of metastases. Together, these results indicate that an anti-platelet strategy may efficiently treat thrombosis associated with cancer and reduce the progression of pancreatic cancer in mice.

  1. A dual-targeting approach to inhibit Brucella abortus replication in human cells

    Science.gov (United States)

    Czyż, Daniel M.; Jain-Gupta, Neeta; Shuman, Howard A.; Crosson, Sean

    2016-01-01

    Brucella abortus is an intracellular bacterial pathogen and an etiological agent of the zoonotic disease known as brucellosis. Brucellosis can be challenging to treat with conventional antibiotic therapies and, in some cases, may develop into a debilitating and life-threatening chronic illness. We used multiple independent assays of in vitro metabolism and intracellular replication to screen a library of 480 known bioactive compounds for novel B. abortus anti-infectives. Eighteen non-cytotoxic compounds specifically inhibited B. abortus replication in the intracellular niche, which suggests these molecules function by targeting host cell processes. Twenty-six compounds inhibited B. abortus metabolism in axenic culture, thirteen of which are non-cytotoxic to human host cells and attenuate B. abortus replication in the intracellular niche. The most potent non-cytotoxic inhibitors of intracellular replication reduce B. abortus metabolism in axenic culture and perturb features of mammalian cellular biology including mitochondrial function and receptor tyrosine kinase signaling. The efficacy of these molecules as inhibitors of B. abortus replication in the intracellular niche suggests “dual-target” compounds that coordinately perturb host and pathogen are promising candidates for development of improved therapeutics for intracellular infections. PMID:27767061

  2. Platelet regulating properties of insulin revisited

    NARCIS (Netherlands)

    Andrade Ferreira, I. (Irlando)

    2005-01-01

    Disturbances in platelet responsiveness in diabetes mellitus (DM) lead to platelet-dependent complications in the vasculature. Our studies showed that insulin inhibits platelet activation by inhibiting ADP- and thrombin-induced Ca2+ levels. Ca2+ is under control of cAMP that is a potent endogenous p

  3. AD6 (8-monochloro-3-beta-diethylamino-ethyl-4-methyl-7-ethoxycarbonyl-meth oxy coumarin) inhibits the release of arachidonic acid in human platelets stimulated by thrombin

    Energy Technology Data Exchange (ETDEWEB)

    Porcellati, S.; Costantini, V.; Prosdocimi, M.; Pistolesi, R.; Porrovecchio, P.; Nenci, G.G.; Goracci, G.

    1987-07-01

    The coumarin derivative AD6 is known to inhibit platelet aggregation and release and it possesses vasodilatory properties on coronary arteries of laboratory animals. Furthermore, the inhibition of the production of TxB2 from endogenous substrates after stimulation of human platelets with collagen has been demonstrated. The present report demonstrates that AD6 inhibits the production of labeled arachidonic acid and diglycerides from phospholipids of platelets stimulated with thrombin. This effect is dose-dependent and is already evident at a concentration of the drug (25 microM) which is unable to prevent the aggregation. Apparently, AD6 inhibits the release of arachidonic acid from phosphatidylinositol and choline phosphoglycerides which are the main sources of the substrate for the synthesis of prostaglandins and thromboxanes.

  4. Prolonged propagation of rat neural stem cells relies on inhibiting autocrine/paracrine bone morphogenetic protein and platelet derived growth factor signals

    Institute of Scientific and Technical Information of China (English)

    Yirui Sun; Liangfu Zhou; Xing Wu; Hua Liu; Qiang Yuan; Ying Mao; Jin Hu

    2011-01-01

    Continuous expansion of rat neural stem cell lines has not been achieved due to proliferation arrest and spontaneous differentiation in vitro. In the current study, neural precursor cells derived from the subventricular zone of adult rats spontaneously underwent astroglial and oligodendroglial differentiation after limited propagation. This differentiation was largely induced by autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signals. The results showed that, by inhibiting bone morphogenetic protein and platelet derived growth factor signals, adult rat neural precursor cells could be extensively cultured in vitro as tripotent stem cell lines. In addition to adult rat neural stem cells, we found that bone morphogenetic protein antagonists can promote the proliferation of human neural stem cells. Therefore, the present findings illustrated the role of autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signaling in determining neural stem cell self-renewal and differentiation. By antagonizing both signals, the long-term propagation of rat neural stem cell lines can be achieved.

  5. Association of thrombin generation potential with platelet PAR-1 regulation and P-selectin expression in patients on dual antiplatelet therapy.

    Science.gov (United States)

    Badr Eslam, Roza; Posch, Florian; Lang, Irene M; Gremmel, Thomas; Eichelberger, Beate; Ay, Cihan; Panzer, Simon

    2014-02-01

    We studied the association of thrombin generation potential with platelet protease activated receptor (PAR)-1 regulation and platelet activation in 52 stable coronary artery disease patients on continuous therapy with aspirin and clopidogrel (n = 42) or prasugrel (n = 10). Compared to controls, peak thrombin generation potential was elevated in only 11 patients (p > 0.05), while F1.2 was elevated in 26 patients (p P-selectin expression were significantly elevated in patients compared to controls (p P-selectin (p = 0.002), suggesting in vivo depletion of platelet alpha granules due to ongoing platelet activation.

  6. Platelets in inflammation and immunity.

    Science.gov (United States)

    Herter, J M; Rossaint, J; Zarbock, A

    2014-11-01

    The paradigm of platelets as mere mediators of hemostasis has long since been replaced by a dual role: hemostasis and inflammation. Now recognized as key players in innate and adaptive immune responses, platelets have the capacity to interact with almost all known immune cells. These platelet-immune cell interactions represent a hallmark of immunity, as they can potently enhance immune cell functions and, in some cases, even constitute a prerequisite for host defense mechanisms such as NETosis. In addition, recent studies have revealed a new role for platelets in immunity: They are ubiquitous sentinels and rapid first-line immune responders, as platelet-pathogen interactions within the vasculature appear to precede all other host defense mechanisms. Here, we discuss recent advances in our understanding of platelets as inflammatory cells, and provide an exemplary review of their role in acute inflammation.

  7. Dual Inhibition of PI3K/AKT and MEK/ERK Pathways Induces Synergistic Antitumor Effects in Diffuse Intrinsic Pontine Glioma Cells

    Directory of Open Access Journals (Sweden)

    Y. Linda Wu

    2017-04-01

    Full Text Available Diffuse intrinsic pontine glioma (DIPG is a devastating disease with an extremely poor prognosis. Recent studies have shown that platelet-derived growth factor receptor (PDGFR and its downstream effector pathway, PI3K/AKT/mTOR, are frequently amplified in DIPG, and potential therapies targeting this pathway have emerged. However, the addition of targeted single agents has not been found to improve clinical outcomes in DIPG, and targeting this pathway alone has produced insufficient clinical responses in multiple malignancies investigated, including lung, endometrial, and bladder cancers. Acquired resistance also seems inevitable. Activation of the Ras/Raf/MEK/ERK pathway, which shares many nodes of cross talk with the PI3K/AKT pathway, has been implicated in the development of resistance. In the present study, perifosine, a PI3K/AKT pathway inhibitor, and trametinib, a MEK inhibitor, were combined, and their therapeutic efficacy on DIPG cells was assessed. Growth delay assays were performed with each drug individually or in combination. Here, we show that dual inhibition of PI3K/AKT and MEK/ERK pathways synergistically reduced cell viability. We also reveal that trametinib induced AKT phosphorylation in DIPG cells that could not be effectively attenuated by the addition of perifosine, likely due to the activation of other compensatory mechanisms. The synergistic reduction in cell viability was through the pronounced induction of apoptosis, with some effect from cell cycle arrest. We conclude that the concurrent inhibition of the PI3K/AKT and MEK/ERK pathways may be a potential therapeutic strategy for DIPG.

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

    Institute of Scientific and Technical Information of China (English)

    陳一岳; 關超然; 許少珍

    1996-01-01

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

  9. 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.

  10. Hybrid triazoles: Design and synthesis as potential dual inhibitor of growth and efflux inhibition in tuberculosis.

    Science.gov (United States)

    Dixit, Prasad P; Dixit, Prashant P; Thore, Shivajirao N

    2016-01-01

    Efflux inhibition is proven bacterial machinery responsible for removal of bacterial wastage including antibiotics. Recently, efflux inhibitors (EI) have been tested with encouraging results as an adjuvant therapy for treatment of tuberculosis (TB). Although, EI have emerged as innovative approach of treatment for multi drug resistant (MDR) & extensively drug resistant tuberculosis (XDR-TB), toxicity profile limits their wider use. To address this issue, we have attempted synthesizing hybrid molecules those results by combining known EI and triazole. This synthesis was aimed to arrive at structure that possesses pharmacophore from known EI. Synthesized molecules were evaluated as growth inhibitors (GI) and Efflux inhibitor of TB initially against Mycobacterium smegmatis mc(2)155. Pharmacologically active compounds were then tested for their cytotoxicity to further narrow down search. Most active compounds 144, 145, 154 and 163 were then tested for their GEI action against Mycobacterium tuberculosis (Mtb). Synthesized compounds were also tested for their synergistic action with first line and second line anti-TB drugs and ethidium bromide (EtBr). We arrived at compound 135 as most potent dual inhibitor of tuberculosis.

  11. miR-326 targets antiapoptotic Bcl-xL and mediates apoptosis in human platelets.

    Science.gov (United States)

    Yu, Shifang; Huang, Huicong; Deng, Gang; Xie, Zuoting; Ye, Yincai; Guo, Ruide; Cai, Xuejiao; Hong, Junying; Qian, Dingliang; Zhou, Xiangjing; Tao, Zhihua; Chen, Bile; Li, Qiang

    2015-01-01

    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.

  12. 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.

  13. Inhibition of platelet-activating factor- and zymosan-activated serum-induced chemotaxis of human neutrophils by nedocromil sodium, BN 52021 and sodium cromoglycate.

    Science.gov (United States)

    Bruijnzeel, P. L.; Warringa, R. A.; Kok, P. T.

    1989-01-01

    1. Inflammatory cells such as eosinophils and neutrophils are thought to contribute actively to the pathogenesis of asthma since they infiltrate into the lung tissue. These cells are mobilized by lipid-like and protein-like chemotactic factors. As illustrative examples of both groups, platelet-activating-factor (Paf) and zymosan-activated-serum (ZAS) were used in this study. The inhibitory effects of nedocromil sodium, the Paf antagonist BN 52021 and sodium cromoglycate on Paf- and ZAS-induced neutrophil chemotaxis were evaluated. 2. All tested drugs inhibited Paf-induced neutrophil chemotaxis with approximately the same potency (IC50 approximately 1 nM). 3. Nedocromil sodium and sodium cromoglycate were equally potent in inhibiting ZAS-induced neutrophil chemotaxis (IC50 = 0.1-1 microM), whereas BN 52021 was considerably less potent (IC30 = 10 microM). 4. To find out whether the drugs tested could inhibit early events in cell activation, their capacity to inhibit Paf- and ZAS-induced cytosolic free Ca2+-mobilization was investigated. BN 52021, at a concentration of 100 microM, completely inhibited Paf-induced Ca2+-mobilization and inhibited ZAS-induced Ca2+-mobilization by about 50%. Nedocromil sodium and sodium cromoglycate were ineffective. PMID:2551444

  14. A novel dual inhibitor of microtubule and Bruton's tyrosine kinase inhibits survival of multiple myeloma and osteoclastogenesis.

    Science.gov (United States)

    Pandey, Manoj K; Gowda, Krishne; Sung, Shen-Shu; Abraham, Thomas; Budak-Alpdogan, Tulin; Talamo, Giampolo; Dovat, Sinisa; Amin, Shantu

    2017-09-01

    Bruton's tyrosine kinase (BTK) regulates many vital signaling pathways and plays a critical role in cell proliferation, survival, migration, and resistance. Previously, we reported that a small molecule, KS99, is an inhibitor of tubulin polymerization. In the present study, we explored whether KS99 is a dual inhibitor of BTK and tubulin polymerization. Although it is known that BTK is required for clonogenic growth and resistance, and microtubules are essential for cancer cell growth, dual targeting of these two components has not been explored previously. Through docking studies, we predicted that KS99 interacts directly with the catalytic domain of BTK and inhibits phosphorylation at the Y223 residue and kinase activities. Treatment of KS99 reduces the cell viability of multiple myeloma (MM) and CD138(+) cells, with an IC50 of between 0.5 and 1.0 μmol/L. We found that KS99 is able to induce apoptosis in MM cells in a caspase-dependent manner. KS99 suppressed the receptor activator of NF-κB ligand (RANKL)-induced differentiation of macrophages to osteoclasts in a dose-dependent manner and, importantly, inhibited the expression of cytokines associated with bone loss. Finally, we found that KS99 inhibits the in vivo tumor growth of MM cells through the inhibition of BTK and tubulin. Overall, our results show that dual inhibition of BTK and tubulin polymerization by KS99 is a viable option in MM treatment, particularly in the inhibition of refraction and relapse. Copyright © 2017 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

  15. Isolation of bovine platelet cationic proteins which inhibit the surface-mediated activation of factor XII and prekallikrein.

    Science.gov (United States)

    Kodama, K; Kato, H; Iwanaga, S

    1985-01-01

    A possible role of bovine platelets in the surface-mediated activation of Factor XII and prekallikrein was studied, using the contact system reconstituted with the purified proteins from bovine plasma. The washed platelets before and after aggregation by ADP, thrombin or collagen did not show any ability to trigger or accelerate the activation of Factor XII and prekallikrein. On the contrary, these aggregates showed a potent inhibitory activity on the activation of those zymogens triggered by kaolin, amylose sulfate and sulfatide. The inhibitory substances from the supernatant of the thrombin-induced aggregates were separated into two major fractions, a low affinity fraction and a high affinity fraction, on a heparin-Sepharose column. The high affinity protein was identified as platelet factor 4, based on the amino acid composition. From the low affinity fraction, a beta-thromboglobulin (beta-TG)-like substance and three kinds of unknown proteins, named LA1, LA2, and LA3, were isolated by gel-filtration on a column of Sephadex G-100 or Sephadex G-75 followed by chromatography on a column of Mono S. The molecular weights of LA1, LA2, and LA3 were estimated to be 35,000, 26,000, and 11,000, respectively, on SDS-PAGE. LA2 was identified as a carbohydrate-less LA1, as judged from the amino acid composition and carbohydrate content. The inhibitory activities of these five cationic proteins on the activation of Factor XII and prekallikrein mediated with amylose sulfate, sulfatide and kaolin were different from each other. In the case of kaolin-mediated activation, LA3 was the most potent inhibitor, while platelet factor 4 and beta-TG-like substance did not show any significant inhibitory activity. Moreover, the inhibitory activities of all the cationic proteins were not correlated with their anti-heparin activities. Since these proteins were rapidly liberated from platelets by the action of the stimulants, the present results demonstrate a negative role of platelets in

  16. 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...

  17. Platelet Count

    Science.gov (United States)

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

  18. Optimal duration of dual anti-platelet therapy after percutaneous coronary intervention: 2016 consensus position of the Italian Society of Cardiology.

    Science.gov (United States)

    Barillà, Francesco; Pelliccia, Francesco; Borzi, Mauro; Camici, Paolo; Cas, Livio Dei; Di Biase, Matteo; Indolfi, Ciro; Mercuro, Giuseppe; Montemurro, Vincenzo; Padeletti, Luigi; Filardi, Pasquale Perrone; Vizza, Carmine D; Romeo, Francesco

    2017-01-01

    Definition of the optimal duration of dual anti-platelet therapy (DAPT) is an important clinical issue, given the large number of patients having percutaneous coronary intervention (PCI), the costs and risks of pharmacologic therapy, the consequences of stent thrombosis, and the potential benefits of DAPT in preventing ischaemic outcomes beyond stent thrombosis. Nowadays, the rationale for a prolonged duration of DAPT should be not only the prevention of stent thrombosis, but also the prevention of ischaemic events unrelated to the coronary stenosis treated with index PCI. A higher predisposition to athero-thrombosis may persist for years after an acute myocardial infarction, and even stable patients with a history of prior myocardial infarction are at high risk for major adverse cardiovascular events. Recently, results of pre-specified post-hoc analyses of randomized clinical trials, including the PEGASUS-TIMI 54 trial, have shed light on strategies of DAPT in various clinical situations, and should impact the next rounds of international guidelines, and also routine practice. Accordingly, the 2015 to 2016 the Board of the Italian Society of Cardiology addressed newer recommendations on duration of DAPT based on most recent scientific information. The document states that physicians should decide duration of DAPT on an individual basis, taking into account ischaemic and bleeding risks of any given patient. Indeed, current controversy surrounding optimal duration of DAPT clearly reflects the fact that, nowadays, a one size fits all strategy cannot be reliably applied to patients treated with PCI. Indeed, patients usually have factors for both increased ischaemic and bleeding risks that must be carefully evaluated to assess the benefit/risk ratio of prolonged DAPT. Personalized management of DAPT must be seen as a dynamic prescription with regular re-evaluations of the risk/benefit to the patient according to changes in his/her clinical profile. Also, in order to

  19. Platelet receptors and patient responses: The contributions of Professor Stan Heptinstall to platelet research.

    Science.gov (United States)

    Clemetson, Kenneth J

    2015-01-01

    Stan Heptinstall's contributions to platelet research covered organising meetings at the national and European level as well as starting and maintaining the journal "Platelets". The major part of his research addressed problems of inhibition of platelet receptors and the effects of this on patient health. In particular, the effects of P2Y12 inhibitors on patients with acute cardiovascular problems were a major focus. Other studies included the effects of feverfew (Tanacetum parthenium) extracts on platelets, of direct anti-IIb/IIIa receptor (αIIbβ3) inhibitors and of prostanoids on platelet function. Recently, methods for assessing the effectiveness of platelet inhibition were investigated.

  20. Dual active ionic liquids and organic salts for inhibition of microbially influenced corrosion.

    Science.gov (United States)

    Seter, Marianne; Thomson, Melanie J; Stoimenovski, Jelena; MacFarlane, Douglas R; Forsyth, Maria

    2012-06-18

    We describe a series of novel compounds designed to combat the bacterial growth that leads to microbially induced corrosion on steel in the marine environment. A synergistic effect of the ionic components in these dual active organic salts is demonstrated.

  1. Pegylated G-CSF Inhibits Blood Cell Depletion, Increases Platelets, Blocks Splenomegaly, and Improves Survival after Whole-Body Ionizing Irradiation but Not after Irradiation Combined with Burn

    Directory of Open Access Journals (Sweden)

    Juliann G. Kiang

    2014-01-01

    Full Text Available Exposure to ionizing radiation alone (radiation injury, RI or combined with traumatic tissue injury (radiation combined injury, CI is a crucial life-threatening factor in nuclear and radiological accidents. As demonstrated in animal models, CI results in greater mortality than RI. In our laboratory, we found that B6D2F1/J female mice exposed to 60Co-γ-photon radiation followed by 15% total-body-surface-area skin burns experienced an increment of 18% higher mortality over a 30-day observation period compared to irradiation alone; that was accompanied by severe cytopenia, thrombopenia, erythropenia, and anemia. At the 30th day after injury, neutrophils, lymphocytes, and platelets still remained very low in surviving RI and CI mice. In contrast, their RBC, hemoglobin, and hematocrit were similar to basal levels. Comparing CI and RI mice, only RI induced splenomegaly. Both RI and CI resulted in bone marrow cell depletion. It was observed that only the RI mice treated with pegylated G-CSF after RI resulted in 100% survival over the 30-day period, and pegylated G-CSF mitigated RI-induced body-weight loss and depletion of WBC and platelets. Peg-G-CSF treatment sustained RBC balance, hemoglobin levels, and hematocrits and inhibited splenomegaly after RI. The results suggest that pegylated G-CSF effectively sustained animal survival by mitigating radiation-induced cytopenia, thrombopenia, erythropenia, and anemia.

  2. Study design and rationale of 'Influence of Cilostazol-based triple anti-platelet therapy on ischemic complication after drug-eluting stent implantation (CILON-T' study: A multicenter randomized trial evaluating the efficacy of Cilostazol on ischemic vascular complications after drug-eluting stent implantation for coronary heart disease

    Directory of Open Access Journals (Sweden)

    Lee Seung-Pyo

    2010-08-01

    Full Text Available Abstract Background Current guidelines recommend dual anti-platelet therapy, aspirin and clopidogrel, for patients treated with drug-eluting stent for coronary heart disease. In a few small trials, addition of cilostazol on dual anti-platelet therapy (triple anti-platelet therapy showed better late luminal loss. In the real-world unselected patients with coronary heart disease, however, the effect of cilostazol on platelet reactivity and ischemic vascular events after drug-eluting stent implantation has not been tested. It is also controversial whether there is a significant interaction between lipophilic statin and clopidogrel. Methods/Design CILON-T trial was a prospective, randomized, open-label, multi-center, near-all-comer trial to demonstrate the superiority of triple anti-platelet therapy to dual anti-platelet therapy in reducing 6 months' major adverse cardiovascular/cerebrovascular events, composite of cardiac death, nonfatal myocardial infarction, target lesion revascularization and ischemic stroke. It also tested whether triple anti-platelet therapy is superior to dual anti-platelet therapy in inhibiting platelet reactivity in patients receiving percutaneous coronary intervention with drug-eluting stent. Total 960 patients were randomized to receive either dual anti-platelet therapy or triple anti-platelet therapy for 6 months and also, randomly stratified to either lipophilic statin (atorvastatin or non-lipophilic statin (rosuvastatin indefinitely. Secondary endpoints included all components of major adverse cardiovascular/cerebrovascular events, platelet reactivity as assessed by VerifyNow P2Y12 assay, effect of statin on major adverse cardiovascular/cerebrovascular events, bleeding complications, and albumin-to-creatinine ratio to test the nephroprotective effect of cilostazol. Major adverse cardiovascular/cerebrovascular events will also be checked at 1, 2, and 3 years to test the 'legacy' effect of triple anti-platelet therapy

  3. 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.

  4. A class of 3S-2-aminoacyltetrahydro-beta-carboline-3-carboxylic acids: their facile synthesis, inhibition for platelet activation, and high in vivo anti-thrombotic potency.

    Science.gov (United States)

    Liu, Jiawang; Jiang, Xueyun; Zhao, Ming; Zhang, Xiaoyi; Zheng, Meiqing; Peng, Li; Peng, Shiqi

    2010-04-22

    3S-Tetrahydro-beta-carboline-3-carboxylic acid (TCCA) effectively inhibits ADP-induced platelet activation. This paper used TCCA as a lead, modified its 2-position with amino acids, and provided 20 novel 3S-2-aminoacyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids (5a-t). With the in vitro assay, it was demonstrated that this modification diminished the IC(50) values from 701 nM of TCCA to 10 nM of 5a-t. With the in vivo assay, it was demonstrated that this modification reduced the efficacious dose from 5.0 micromol/kg of TCCA to 0.1 micromol/kg of 5a-t. Comparing the Cerius based conformation of them with that of their analogues, the 3-position modified TCCA, it was suggested that the comparatively unfolded conformation was one of the important factors of enhancing the in vivo antithrombotic potency.

  5. Platelet proteomics.

    Science.gov (United States)

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

    2012-01-01

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

  6. Inhibition of hepatocelluar carcinoma MAT2A and MAT2beta gene expressions by single and dual small interfering RNA

    Directory of Open Access Journals (Sweden)

    Sun Quan

    2008-11-01

    Full Text Available Abstract RNA interference (RNAi has been successfully applied in suppression of hepatic cancer genes. In hepatocelluar carcinoma cell, one methionine adenosyltransferase (MAT isozyme, MATII was found to have two catalytic subunits which were encoded by MAT2A and MAT2β respectively. During tumorigeness of hepatocelluar carcinoma, expressions of the two genes were discovered to be increased combining with a switch of MAT (form MATI to MATII, To figure out the role played by MATII in hepatic cancer, In this study, for the first time we established a dual small interfering RNA (siRNA expression system, which could simultaneously express two different siRNA molecules specifically targeting two genes. To test the effectiveness of this system, we applied this approach to express simultaneously two different siRNA duplexes that specifically target MAT2A and MAT2β genes of hepatocelluar carcinoma respectively in HepG2 cell. Results indicated that dual siRNA could simultaneously inhibit the expression of MAT2A and MAT2β gene by 89.5% and 97.8% respectively, In addition, dual siRNA molecules were able to significantly suppress growth of hepatocelluar carcinoma cell in vitro as well as induce apoptosis which was involved in arrest cell cycle at the G1/S checkpoint and the expressions of p21, p27 and Bax.

  7. Platelet lipidomic.

    Science.gov (United States)

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

    2012-01-01

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

  8. Dual antibacterial agents of nano-silver and 12-methacryloyloxydodecylpyridinium bromide in dental adhesive to inhibit caries

    Science.gov (United States)

    Zhang, Ke; Li, Fang; Imazato, Satoshi; Cheng, Lei; Liu, Huaibing; Arola, Dwayne D.; Bai, Yuxing; Xu, Hockin H. K.

    2013-01-01

    Dental resins containing 12-methacryloyloxydodecylpyridinium bromide (MDPB) showed potent antibacterial functions. Recent studies developed antibacterial resins containing nanoparticles of silver (NAg). The objectives of this study were to develop an adhesive containing dual agents of MDPB and NAg for the first time, and to investigate the combined effects of antibacterial adhesive and primer on biofilm viability, metabolic activity, lactic acid, dentin bond strength, and fibroblast cytotoxicity. MDPB and NAg were incorporated into Scotchbond Multi-Purpose (SBMP) adhesive “A” and primer “P”. Five systems were tested: SBMP adhesive A; A+MDPB; A+NAg; A+MDPB+NAg; P+MDPB+NAg together with A+MDPB+NAg. Dental plaque microcosm biofilms were cultured using mixed saliva from ten donors. Metabolic activity, colony-forming units, and lactic acid production of biofilms were investigated. Human fibroblast cytotoxicity of bonding agents was determined. MDPB+NAg in adhesive/primer did not compromise dentin bond strength (p>0.1). MDPB or NAg alone in adhesive substantially reduced the biofilm activities. Dual agents MDPB+NAg in adhesive greatly reduced the biofilm viability compared to each agent alone (padhesive and primer contained MDPB+NAg. Fibroblast viability of groups with dual antibacterial agents was similar to control using culture medium without resin eluents (p>0.1). In conclusion, this study showed for the first time that the antibacterial potency of MDPB adhesive could be substantially enhanced via NAg. Adding MDPB+NAg into both primer and adhesive achieved the strongest anti-biofilm efficacy. The dual agent (MDPB+NAg) method could have wide applicability to other adhesives, sealants, cements and composites to inhibit biofilms and caries. PMID:23529901

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

    Directory of Open Access Journals (Sweden)

    Andrezza C Chagas

    2014-06-01

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

  10. Prostaglandin E2 inhibits platelet-derived growth factor-stimulated cell proliferation through a prostaglandin E receptor EP2 subtype in rat hepatic stellate cells.

    Science.gov (United States)

    Koide, Shigeki; Kobayashi, Yoshimasa; Oki, Yutaka; Nakamura, Hirotoshi

    2004-09-01

    Prostaglandin (PG) E2 inhibits hepatic stellate cell (HSC) mitogenesis. PGE-specific receptors are divided into four subtypes that are coupled either to Ca2+ mobilization (EP1 and EP3) or to the stimulation of adenyl cyclase (EP2 and EP4). The aims of the current study were to identify PGE receptor subtypes in cultured rat HSC and to examine which PGE receptor subtype(s) mediates the inhibitory effect of PGE2 on platelet-derived growth factor (PDGF)-stimulated proliferation. Reverse transcription-polymerase chain reaction analysis was performed to detect PGE receptor subtype mRNA expression. Cell proliferation was determined by measuring [3H]thymidine incorporation, and intracellular cyclic AMP was measured by radioimmunoassay. Cultured rat HSC expressed mRNAs for all four subtypes of PGE receptor. PGE2- and EP2-selective agonist produced dose-dependent inhibitory effects on PDGF-stimulated proliferation. Neither EP1-, EP3-, nor EP4-selective agonists showed any inhibitory effect. An adenylate cyclase inhibitor strongly blunted the inhibition of DNA synthesis elicited by PGE2 and the EP2 agonist. The EP2 agonist generated higher and more prolonged increases in intracellular cyclic AMP than the EP4 agonist. Activation of the PGE EP2 receptor has an antiproliferative effect in HSC that may be mediated by cyclic AMP-related signal transduction pathways.

  11. Inhibition of CD73 AMP hydrolysis by a therapeutic antibody with a dual, non-competitive mechanism of action.

    Science.gov (United States)

    Geoghegan, James C; Diedrich, Gundo; Lu, Xiaojun; Rosenthal, Kim; Sachsenmeier, Kris F; Wu, Herren; Dall'Acqua, William F; Damschroder, Melissa M

    2016-01-01

    CD73 (ecto-5'-nucleotidase) has recently been established as a promising immuno-oncology target. Given its role in activating purinergic signaling pathways to elicit immune suppression, antagonizing CD73 (i.e., releasing the brake) offers a complimentary pathway to inducing anti-tumor immune responses. Here, we describe the mechanistic activity of a new clinical therapeutic, MEDI9447, a human monoclonal antibody that non-competitively inhibits CD73 activity. Epitope mapping, structural, and mechanistic studies revealed that MEDI9447 antagonizes CD73 through dual mechanisms of inter-CD73 dimer crosslinking and/or steric blocking that prevent CD73 from adopting a catalytically active conformation. To our knowledge, this is the first report of an antibody that inhibits an enzyme's function through 2 distinct modes of action. These results provide a finely mapped epitope that can be targeted for selective, potent, and non-competitive inhibition of CD73, as well as establish a strategy for inhibiting enzymes that function in both membrane-bound and soluble states.

  12. How to test the effect of aspirin and clopidogrel in patients on dual antiplatelet therapy?

    Science.gov (United States)

    Bagoly, Zsuzsa; Homoródi, Nóra; Kovács, Emese Gyöngyvér; Sarkady, Ferenc; Csiba, László; Édes, István; Muszbek, László

    2016-01-01

    Dual antiplatelet therapy with clopidogrel and aspirin is frequently used for the prevention of recurrent ischemic events. Various laboratory methods are used to detect the effect of these drugs administered in monotherapy, however their value in dual therapy has not been explored. Here, we determined which methods used for testing the effect of clopidogrel or aspirin are influenced by the other antiplatelet agent. One arm of the study included 53 ischemic stroke patients being on clopidogrel monotherapy showing effective inhibition of the P2Y12 ADP receptor. Laboratory tests routinely used for the detection of aspirin resistance (arachidonic acid (AA)-induced platelet aggregation/secretion, AA-induced thromboxane B2 (TXB2) production in platelet-rich plasma and VerifyNow Aspirin assay) were carried out on samples obtained from these patients. The other arm of the study involved 52 patients with coronary artery disease being on aspirin monotherapy. Methods used for testing the effect of clopidogrel (ADP-induced platelet aggregation and secretion, flow cytometric analysis of vasodilator-stimulated phosphoprotein (VASP) phosphorylation and a newly developed P2Y12-specific platelet aggregation (ADP[PGE1] test)) were performed on samples obtained from these patients. Clopidogrel monotherapy significantly inhibited AA-induced platelet aggregation and secretion, moreover, AA-induced TXB2 production was also significantly decreased. VASP phosphorylation and AA-induced platelet aggregation showed fair correlation in patients taking clopidogrel only. Clopidogrel did not inhibit the VerifyNow Aspirin test significantly. Aspirin monotherapy influenced ADP-induced platelet aggregation and secretion, but did not have an effect on VASP phosphorylation and on the ADP[PGE1] platelet aggregation test.

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

    Science.gov (United States)

    Yang, Chao-Huei; Tsao, Chiung-Fang; Ko, Wang-Sheng; Chiou, Ya-Ling

    2016-01-09

    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 fucoidan reduced the proliferation of PDGF-stimulated ASMCs by 75%-99% after 48 h (p 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.

  14. 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.

  15. Development of Antifouling and Bactericidal Coatings for Platelet Storage Bags Using Dopamine Chemistry.

    Science.gov (United States)

    Hadjesfandiari, Narges; Weinhart, Marie; Kizhakkedathu, Jayachandran N; Haag, Rainer; Brooks, Donald E

    2017-09-29

    Platelets have a limited shelf life, due to the risk of bacterial contamination and platelet quality loss. Most platelet storage bags are made of a mixture of polyvinyl chloride with a plasticizer, denoted as pPVC. To improve biocompatibility of pPVC with platelets and to inhibit bacterial biofilm formation, an antifouling polymer coating is developed using mussel-inspired chemistry. A copolymer of N,N-dimethylacrylamide and N-(3-aminopropyl)methacrylamide hydrochloride is synthesized and coupled with catechol groups, named DA51-cat. Under mild aqueous conditions, pPVC is first equilibrated with an anchoring polydopamine layer, followed by a DA51-cat layer. Measurements show this coating decreases fibrinogen adsorption to 5% of the control surfaces. One-step coating with DA51-cat does not coat pPVC efficiently although it is sufficient for coating silicon wafers and gold substrates. The dual layer coating on platelet bags resists bacterial biofilm formation and considerably decreases platelet adhesion. A cationic antimicrobial peptide, E6, is conjugated to DA51-cat then coated on silicon wafers and introduces bactericidal activity to these surfaces. Time-of-flight second ion-mass spectroscopy is successfully applied to characterize these surfaces. pPVC is widely used in medical devices; this method provides an approach to controlling biofouling and bacterial growth on it without elaborate surface modification procedures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Dual infection and superinfection inhibition of epithelial skin cells by two alphaherpesviruses co-occur in the natural host.

    Directory of Open Access Journals (Sweden)

    Keith W Jarosinski

    Full Text Available Hosts can be infected with multiple herpesviruses, known as superinfection; however, superinfection of cells is rare due to the phenomenon known as superinfection inhibition. It is believed that dual infection of cells occurs in nature, based on studies examining genetic exchange between homologous alphaherpesviruses in the host, but to date, this has not been directly shown in a natural model. In this report, gallid herpesvirus 2 (GaHV-2, better known as Marek's disease virus (MDV, was used in its natural host, the chicken, to determine whether two homologous alphaherpesviruses can infect the same cells in vivo. MDV shares close similarities with the human alphaherpesvirus, varicella zoster virus (VZV, with respect to replication in the skin and exit from the host. Recombinant MDVs were generated that express either the enhanced GFP (eGFP or monomeric RFP (mRFP fused to the UL47 (VP13/14 herpesvirus tegument protein. These viruses exhibited no alteration in pathogenic potential and expressed abundant UL47-eGFP or -mRFP in feather follicle epithelial cells in vivo. Using laser scanning confocal microscopy, it was evident that these two similar, but distinguishable, viruses were able to replicate within the same cells of their natural host. Evidence of superinfection inhibition was also observed. These results have important implications for two reasons. First, these results show that during natural infection, both dual infection of cells and superinfection inhibition can co-occur at the cellular level. Secondly, vaccination against MDV with homologous alphaherpesvirus like attenuated GaHV-2, or non-oncogenic GaHV-3 or meleagrid herpesvirus (MeHV-1 has driven the virus to greater virulence and these results implicate the potential for genetic exchange between homologous avian alphaherpesviruses that could drive increased virulence. Because the live attenuated varicella vaccine is currently being administered to children, who in turn could be

  17. Consensus and future directions on the definition of high on-treatment platelet reactivity to adenosine diphosphate.

    Science.gov (United States)

    Bonello, Laurent; Tantry, Udaya S; Marcucci, Rossella; Blindt, Ruediger; Angiolillo, Dominick J; Becker, Richard; Bhatt, Deepak L; Cattaneo, Marco; Collet, Jean Philippe; Cuisset, Thomas; Gachet, Christian; Montalescot, Gilles; Jennings, Lisa K; Kereiakes, Dean; Sibbing, Dirk; Trenk, Dietmar; Van Werkum, Jochem W; Paganelli, Franck; Price, Matthew J; Waksman, Ron; Gurbel, Paul A

    2010-09-14

    The addition of clopidogrel to aspirin treatment reduces ischemic events in a wide range of patients with cardiovascular disease. However, recurrent ischemic event occurrence during dual antiplatelet therapy, including stent thrombosis, remains a major concern. Platelet function measurements during clopidogrel treatment demonstrated a variable and overall modest level of P2Y(12) inhibition. High on-treatment platelet reactivity to adenosine diphosphate (ADP) was observed in selected patients. Multiple studies have now demonstrated a clear association between high on-treatment platelet reactivity to ADP measured by multiple methods and adverse clinical event occurrence. However, the routine measurement of platelet reactivity has not been widely implemented and recommended in the guidelines. Reasons for the latter include: 1) a lack of consensus on the optimal method to quantify high on-treatment platelet reactivity and the cutoff value associated with clinical risk; and 2) limited data to support that alteration of therapy based on platelet function measurements actually improves outcomes. This review provides a consensus opinion on the definition of high on-treatment platelet reactivity to ADP based on various methods reported in the literature and proposes how this measurement may be used in the future care of patients. Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  18. Platelet interaction with bacterial toxins and secreted products.

    Science.gov (United States)

    Shannon, Oonagh

    2015-01-01

    Bacteria that enter the bloodstream will encounter components of the cellular and soluble immune response. Platelets contribute to this response and have emerged as an important target for bacterial pathogens. Bacteria produce diverse extracellular proteins and toxins that have been reported to modulate platelet function. These interactions can result in complete or incomplete platelet activation or inhibition of platelet activation, depending on the bacteria and bacterial product. The nature of the platelet response may be highly relevant to disease pathogenesis.

  19. Dual inhibition of plasminogen kringle 5 on angiogenesis and chemotaxis suppresses tumor metastasis by targeting HIF-1α pathway.

    Directory of Open Access Journals (Sweden)

    Wei-Bin Cai

    Full Text Available We had demonstrated that plasminogen kringle 5 (K5, a potent angiogenic inhibitor, inhibited retinal neovascularization and hepatocellular carcinoma growth by anti-angiogenesis. The current study investigated the effects and the underlying mechanisms of K5 on both tumor growth and spontaneous pulmonary metastasis in Lewis lung carcinoma (LLC implanted mouse model. Similarly, K5 could decrease expression of VEGF in LLC cells and grafted tissues and suppress tumor angiogenesis and growth. K5 had no direct effect on proliferation and apoptosis of LLC. However, K5 could significantly inhibit SDF-1α-induced chemotaxis movement of LLC cells and resulted in a great reduction of surface metastatic nodules and micrometastases in the lungs of LLC tumor-bearing mice. K5 also decreased expression of chemokine (C-X-C motif receptor 4 (CXCR4 in LLC cells and grafted tissues. Furthermore, K5 down-regulated SDF-1α expression in metastatic lung tissues of LLC-bearing mice. Therefore, K5 may suppress tumor pulmonary metastasis through inhibiting SDF-1α-CXCR4 chemotaxis movement and down-regulation of VEGF. Moreover, the role of hypoxia inducible factor-1α (HIF-1α, a crucial transcriptional factor for both VEGF and CXCR4 expression, was evaluated. The siRNA of HIF-1α attenuated expression of VEGF and CXCR4 and inhibited LLC migration. K5 decreased HIF-1α protein level and impaired nuclear HIF-1α accumulation. These results showed for the first time that K5 inhibits LLC growth and metastasis via the dual effects of anti-angiogenesis and suppression of tumor cell motility by targeting the pivotal molecule, HIF-1α.

  20. Potential Dual Role of Eugenol in Inhibiting Advanced Glycation End Products in Diabetes: Proteomic and Mechanistic Insights.

    Science.gov (United States)

    Singh, Priyanka; Jayaramaiah, Ramesha H; Agawane, Sachin B; Vannuruswamy, Garikapati; Korwar, Arvind M; Anand, Atul; Dhaygude, Vitthal S; Shaikh, Mahemud L; Joshi, Rakesh S; Boppana, Ramanamurthy; Kulkarni, Mahesh J; Thulasiram, Hirekodathakallu V; Giri, Ashok P

    2016-01-07

    Medicinally important genus Ocimum harbors a vast pool of chemically diverse metabolites. Current study aims at identifying anti-diabetic candidate compounds from Ocimum species. Major metabolites in O. kilimandscharicum, O. tenuiflorum, O. gratissimum were purified, characterized and evaluated for anti-glycation activity. In vitro inhibition of advanced glycation end products (AGEs) by eugenol was found to be highest. Preliminary biophysical analysis and blind docking studies to understand eugenol-albumin interaction indicated eugenol to possess strong binding affinity for surface exposed lysines. However, binding of eugenol to bovine serum albumin (BSA) did not result in significant change in secondary structure of protein. In vivo diabetic mice model studies with eugenol showed reduction in blood glucose levels by 38% likely due to inhibition of α-glucosidase while insulin and glycated hemoglobin levels remain unchanged. Western blotting using anti-AGE antibody and mass spectrometry detected notably fewer AGE modified peptides upon eugenol treatment both in vivo and in vitro. Histopathological examination revealed comparatively lesser lesions in eugenol-treated mice. Thus, we propose eugenol has dual mode of action in combating diabetes; it lowers blood glucose by inhibiting α-glucosidase and prevents AGE formation by binding to ε-amine group on lysine, protecting it from glycation, offering potential use in diabetic management.

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

    Science.gov (United States)

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

    2009-12-15

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

  2. Acquired platelet function defect

    Science.gov (United States)

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

  3. Platelet Donation

    Science.gov (United States)

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

  4. Beyond inhibition: a dual-process perspective to renew the exploration of binge drinking.

    Science.gov (United States)

    Lannoy, Séverine; Billieux, Joël; Maurage, Pierre

    2014-01-01

    Binge drinking is a widespread alcohol-consumption pattern in youth and is linked to cognitive consequences, mostly for executive functions. However, other crucial factors remain less explored in binge drinking and notably the emotional-automatic processes. Dual-process model postulates that addictive disorders are not only due to impaired reflective system (involved in deliberate behaviors), but rather to an imbalance between under-activated reflective system and over-activated affective-automatic one (involved in impulsive behaviors). This proposal has been confirmed in alcohol-dependence, but has not been tested in binge drinking. The observation of comparable impairments in binge drinking and alcohol-dependence led to the "continuum hypothesis," suggesting similar deficits across different alcohol-related disorders. In this perspective, applying the dual-process model to binge drinking might renew the understanding of this continuum hypothesis. A three-axes research agenda will be proposed, exploring: (1) the affective-automatic system in binge drinking; (2) the systems' interactions and imbalance in binge drinking; (3) the evolution of this imbalance in the transition between binge drinking and alcohol-dependence.

  5. Beyond inhibition: A dual-process perspective to renew the exploration of binge drinking.

    Directory of Open Access Journals (Sweden)

    Severine eLannoy

    2014-06-01

    Full Text Available Binge drinking is a widespread alcohol-consumption pattern in youth and is linked to cognitive consequences, mostly for executive functions. However, other crucial factors remain less explored in binge drinking and notably the emotional-automatic processes. Dual-process model postulates that addictive disorders are not only due to impaired reflective system (involved in deliberate behaviours, but rather to an imbalance between under-activated reflective system and over-activated affective-automatic one (involved in impulsive behaviours. This proposal has been confirmed in alcohol-dependence, but has not been tested in binge drinking. The observation of comparable impairments in binge-drinking and alcohol-dependence led to the continuum hypothesis, suggesting similar deficits across different alcohol-related disorders. In this perspective, applying the dual-process model to binge drinking might renew the understanding of this continuum hypothesis. A three-axes research agenda will be proposed, exploring: (1 the affective-automatic system in binge drinking; (2 the systems’ interactions and imbalance in binge drinking; (3 the evolution of this imbalance in the transition between binge drinking and alcohol-dependence.

  6. Effects of TRA-418, a novel TP-receptor antagonist, and IP-receptor agonist, on human platelet activation and aggregation.

    Science.gov (United States)

    Miyamoto, Mitsuko; Yamada, Naohiro; Ikezawa, Shiho; Ohno, Michihiro; Otake, Atsushi; Umemura, Kazuo; Matsushita, Teruo

    2003-11-01

    [4-[2-(1,1-Diphenylethylsulfanyl)-ethyl]-3,4-dihydro-2H-benzo[1,4]oxazin-8-yloxy]-acetic acid N-Methyl-d-glucamine salt (TRA-418) has both thromboxane A2 (TP)-receptor antagonist and prostacyclin (IP)-receptor agonist properties. The present study examined the advantageous effects of TRA-418 based on the dual activities, over an agent having either activity alone and also the difference in the effects of TRA-418 and a glycoprotein alphaIIb/beta3 integrin (GPIIb/IIIa) inhibitor. TRA-418 inhibited platelet GPIIb/IIIa activation as well as P-selectin expression induced by adenosine 5'-diphosphate, thrombin receptor agonist peptide 1-6 (Ser-Phe-Leu-Leu-Arg-Asn-NH2), and U-46619 in the presence of epinephrine (U-46619+ epinephrine). TRA-418 also inhibited platelet aggregation induced by those platelet-stimulants in Ca2+ chelating anticoagulant, citrate and in nonchelating anticoagulant, d-phenylalanyl-l-prolyl-l-arginyl-chloromethyl ketone (PPACK). The TP-receptor antagonist SQ-29548 inhibited only U-46619+epinephrine-induced GPIIb/IIIa activation, P-selectin expression, and platelet aggregation. The IP-receptor agonist beraprost sodium inhibited platelet activation. Beraprost also inhibited platelet aggregation induced by platelet stimulants we tested in citrate and in PPACK. The GPIIb/IIIa inhibitor abciximab blocked GPIIb/IIIa activation and platelet aggregation. However, abciximab showed slight inhibitory effects on P-selectin expression. TRA-418 is more advantageous as an antiplatelet agent than TP-receptor antagonists or IP-receptor agonists separately used. TRA-418 showed a different inhibitory profile from abciximab in the effects on P-selectin expression.

  7. Cordycepin-Enriched WIB801C from Cordyceps militaris Inhibits Collagen-Induced [Ca2+]i Mobilization via cAMP-Dependent Phosphorylation of Inositol 1, 4, 5-Trisphosphate Receptor in Human Platelets

    Science.gov (United States)

    Lee, Dong-Ha; Kim, Hyun-Hong; Cho, Hyun-Jeong; Yu, Young-Bin; Kang, Hyo-Chan; Kim, Jong-Lae; Lee, Jong-Jin; Park, Hwa-Jin

    2014-01-01

    In this study, we prepared cordycepin-enriched (CE)-WIB801C, a n-butanol extract of Cordyceps militaris-hypha, and investigated the effect of CE-WIB801C on collagen-induced human platelet aggregation. CE-WIB801C dose-dependently inhibited collagen-induced platelet aggregation, and its IC50 value was 175 μg/ml. CE-WIB801C increased cAMP level more than cGMP level, but inhibited collagen-elevated [Ca2+]i mobilization and thromboxane A2 (TXA2) production. cAMP-dependent protein kinase (A-kinase) inhibitor Rp-8-Br-cAMPS increased the CE-WIB801C-downregulated [Ca2+]i level in a dose dependent manner, and strongly inhibited CE-WIB801C-induced inositol 1, 4, 5-trisphosphate receptor (IP3R) phosphorylation. These results suggest that the inhibition of [Ca2+]i mobilization by CE-WIB801C is resulted from the cAMP/A-kinase-dependent phosphorylation of IP3R. CE-WIB801C suppressed TXA2 production, but did not inhibit the activities of cyclooxygenase-1 (COX-1) and TXA2 synthase (TXAS). These results suggest that the inhibition of TXA2 production by WIB801C is not resulted from the direct inhibition of COX-1 and TXAS. In this study, we demonstrate that CE-WIB801C with cAMP-dependent Ca2+-antagonistic antiplatelet effects may have preventive or therapeutic potential for platelet aggregation-mediated diseases, such as thrombosis, myocardial infarction, atherosclerosis, and ischemic cerebrovascular disease. PMID:25009703

  8. Dopamine D1-like receptor stimulation inhibits hypertrophy induced by platelet-derived growth factor in cultured rat renal vascular smooth muscle cells.

    Science.gov (United States)

    Yasunari, K; Kohno, M; Kano, H; Yokokawa, K; Minami, M; Yoshikawa, J

    1997-01-01

    Vascular smooth muscle cell (VSMC) hypertrophy is believed to play some roles in atherosclerosis. To elucidate the role of vascular D1-like receptors in VSMC hypertrophy, the effects of dopamine and specific D1-like receptor agonists SKF 38393 and YM 435 on platelet-derived growth factor (PDGF) BB-mediated VSMC hypertrophy was studied. We observed that cells stimulated by PDGF-BB 5 ng/mL showed increased VSMC hypertrophy. These effects were prevented by coincubation with dopamine, SKF 38393, and YM 435 1-10 mumol/L, and this prevention was reversed by Sch 23390 1 to 10 mumol/L, a specific D1-like receptor antagonist. These actions are mimicked by forskolin 1 to 10 mumol/L, a direct activator of adenylate cyclase and 8-bromo-cAMP 0.1 to 1 mmol/L, and are blocked by a specific protein kinase A (PKA) inhibitor N-[2-(P-bromcoinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H89) but not blocked by its negative control. PDGF-BB (5 ng/mL)-mediated mitogen-activated protein kinase (MAPK) activity was significantly suppressed by coincubation with D1-like receptor agonists, which were reversed by PKA inhibitor H 89. These results suggest that vascular D1-like receptor agonists inhibit hypertrophy of VSMC, possibly through PKA activation and suppression of activated MAPK activity.

  9. 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.

  10. Inhibition of human insulin gene transcription and MafA transcriptional activity by the dual leucine zipper kinase.

    Science.gov (United States)

    Stahnke, Marie-Jeannette; Dickel, Corinna; Schröder, Sabine; Kaiser, Diana; Blume, Roland; Stein, Roland; Pouponnot, Celio; Oetjen, Elke

    2014-09-01

    Insulin biosynthesis is an essential β-cell function and inappropriate insulin secretion and biosynthesis contribute to the pathogenesis of diabetes mellitus type 2. Previous studies showed that the dual leucine zipper kinase (DLK) induces β-cell apoptosis. Since β-cell dysfunction precedes β-cell loss, in the present study the effect of DLK on insulin gene transcription was investigated in the HIT-T15 β-cell line. Downregulation of endogenous DLK increased whereas overexpression of DLK decreased human insulin gene transcription. 5'- and 3'-deletion human insulin promoter analyses resulted in the identification of a DLK responsive element that mapped to the DNA binding-site for the β-cell specific transcription factor MafA. Overexpression of DLK wild-type but not its kinase-dead mutant inhibited MafA transcriptional activity conferred by its transactivation domain. Furthermore, in the non-β-cell line JEG DLK inhibited MafA overexpression-induced human insulin promoter activity. Overexpression of MafA and DLK or its kinase-dead mutant into JEG cells revealed that DLK but not its mutant reduced MafA protein content. Inhibition of the down-stream DLK kinase c-Jun N-terminal kinase (JNK) by SP600125 attenuated DLK-induced MafA loss. Furthermore, mutation of the serine 65 to alanine, shown to confer MafA protein stability, increased MafA-dependent insulin gene transcription and prevented DLK-induced MafA loss in JEG cells. These data suggest that DLK by activating JNK triggers the phosphorylation and degradation of MafA thereby attenuating insulin gene transcription. Given the importance of MafA for β-cell function, the inhibition of DLK might preserve β-cell function and ultimately retard the development of diabetes mellitus type 2.

  11. Interleukin-3 plays dual roles in osteoclastogenesis by promoting the development of osteoclast progenitors but inhibiting the osteoclastogenic process

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Huixian [Department of Hematology, Guangzhou First People’s Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180 (China); Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Shi, Zhenqi [Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Qiao, Ping [Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Department of Pharmacology, Norman Bethune Medical College, Jilin University, Changchun, Jilin 130021 (China); Li, Hui [Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); McCoy, Erin M. [Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Mao, Ping [Department of Hematology, Guangzhou First People’s Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180 (China); Xu, Hui [Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Feng, Xu [Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Wang, Shunqing, E-mail: shqwang_cn@yahoo.com [Department of Hematology, Guangzhou First People’s Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180 (China)

    2013-11-01

    Highlights: •IL-3 treatment of bone marrow cells generates a population of hematopoietic cells. •IL-3-dependent hematopoietic cells are capable of differentiating into osteoclasts. •Osteoclasts derived from IL-3-dependent hematopoietic cells are functional. •IL-3 promotes the development of osteoclast progenitors. •IL-3 inhibits the osteoclastogenic process. -- Abstract: Interleukin (IL)-3, a multilineage hematopoietic growth factor, is implicated in the regulation of osteoclastogenesis. However, the role of IL-3 in osteoclastogenesis remains controversial; whereas early studies showed that IL-3 stimulates osteoclastogenesis, recent investigations demonstrated that IL-3 inhibits osteoclast formation. The objective of this work is to further address the role of IL-3 in osteoclastogenesis. We found that IL-3 treatment of bone marrow cells generated a population of cells capable of differentiating into osteoclasts in tissue culture dishes in response to the stimulation of the monocyte/macrophage-colony stimulating factor (M-CSF) and the receptor activator of nuclear factor kappa B ligand (RANKL). The IL-3-dependent hematopoietic cells were able to further proliferate and differentiate in response to M-CSF stimulation and the resulting cells were also capable of forming osteoclasts with M-CSF and RANKL treatment. Interestingly, IL-3 inhibits M-CSF-/RANKL-induced differentiation of the IL-3-dependent hematopoietic cells into osteoclasts. The flow cytometry analysis indicates that while IL-3 treatment of bone marrow cells slightly affected the percentage of osteoclast precursors in the surviving populations, it considerably increased the percentage of osteoclast precursors in the populations after subsequent M-CSF treatment. Moreover, osteoclasts derived from IL-3-dependent hematopoietic cells were fully functional. Thus, we conclude that IL-3 plays dual roles in osteoclastogenesis by promoting the development of osteoclast progenitors but inhibiting the

  12. Pharmacological inhibition of eicosanoids and platelet-activating factor signaling impairs zymosan-induced release of IL-23 by dendritic cells.

    Science.gov (United States)

    Rodríguez, Mario; Márquez, Saioa; Montero, Olimpio; Alonso, Sara; Frade, Javier García; Crespo, Mariano Sánchez; Fernández, Nieves

    2016-02-15

    The engagement of the receptors for fungal patterns induces the expression of cytokines, the release of arachidonic acid, and the production of PGE2 in human dendritic cells (DC), but few data are available about other lipid mediators that may modulate DC function. The combined antagonism of leukotriene (LT) B4, cysteinyl-LT, and platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) inhibited IL23A mRNA expression in response to the fungal surrogate zymosan and to a lower extent TNFA (tumor necrosis factor-α) and CSF2 (granulocyte macrophage colony-stimulating factor) mRNA. The combination of lipid mediators and the lipid extract of zymosan-conditioned medium increased the induction of IL23A by LPS (bacterial lipopolysaccharide), thus suggesting that unlike LPS, zymosan elicits the production of mediators at a concentration enough for optimal response. Zymosan induced the release of LTB4, LTE4, 12-hydroxyeicosatetraenoic acid (12-HETE), and PAF C16:0. DC showed a high expression and detectable Ser663 phosphorylation of 5-lipoxygenase in response to zymosan, and a high expression and activity of LPCAT1/2 (lysophosphatidylcholine acyltransferase 1 and 2), the enzymes that incorporate acetate from acetyl-CoA into choline-containing lysophospholipids to produce PAF. Pharmacological modulation of the arachidonic acid cascade and the PAF receptor inhibited the binding of P-71Thr-ATF2 (activating transcription factor 2) to the IL23A promoter, thus mirroring their effects on the expression of IL23A mRNA and IL-23 protein. These results indicate that LTB4, cysteinyl-LT, and PAF, acting through their cognate G protein-coupled receptors, contribute to the phosphorylation of ATF2 and play a central role in IL23A promoter trans-activation and the cytokine signature induced by fungal patterns.

  13. Dual effects of acetylsalicylic acid on ERK signaling and Mitf transcription lead to inhibition of melanogenesis.

    Science.gov (United States)

    Nishio, Takashi; Usami, Mai; Awaji, Mizuki; Shinohara, Sumire; Sato, Kazuomi

    2016-01-01

    Acetylsalicylic acid (ASA) is widely used as an analgesic/antipyretic drug. It exhibits a wide range of biological effects, including preventative effects against heart attack and stroke, and the induction of apoptosis in various cancer cells. We previously found that ASA inhibits melanogenesis in B16 melanoma cells. However, the mechanisms of how ASA down-regulates melanin synthesis remain unclear. Here, we investigated the effect of ASA on melanogenic pathways, such as extracellular signal-regulated kinase (ERK) and microphthalmia-associated transcription factor (Mitf) transcription. ASA significantly inhibited melanin synthesis in a dose-dependent manner without oxidative stress and cell death. Semi-quantitative reverse transcription-polymerase chain reaction analysis showed that the inhibitory effect of ASA might be due to the inhibition of Mitf gene transcription. Interestingly, ASA also induced ERK phosphorylation. Additionally, treatment with PD98059, a specific ERK phosphorylation inhibitor, abolished the anti-melanogenic effect of ASA. These results suggest that the depigmenting effect of ASA results from down-regulation of Mitf, which is induced by both the induction of ERK phosphorylation and the inhibition of Mitf transcription.

  14. Tacrolimus-induced hypertension and nephrotoxicity in Fawn-Hooded rats are attenuated by dual inhibition of renin-angiotensin system

    NARCIS (Netherlands)

    Hoskova, Lenka; Malek, Ivan; Kautzner, Josef; Honsova, Eva; van Dokkum, Richard P. E.; Huskova, Zuzana; Vojtiskova, Alzbeta; Varcabova, Sarka; Cervenka, Ludek; Kopkan, Libor

    Chronic immunosuppressive therapy is often complicated by the development of both arterial hypertension and renal dysfunction. The principal aim of this study was to assess the effects of dual inhibition of renin-angiotensin system (RAS) and other antihypertensive treatment on blood pressure and

  15. Tacrolimus-induced hypertension and nephrotoxicity in Fawn-Hooded rats are attenuated by dual inhibition of renin-angiotensin system

    NARCIS (Netherlands)

    Hoskova, Lenka; Malek, Ivan; Kautzner, Josef; Honsova, Eva; van Dokkum, Richard P. E.; Huskova, Zuzana; Vojtiskova, Alzbeta; Varcabova, Sarka; Cervenka, Ludek; Kopkan, Libor

    2014-01-01

    Chronic immunosuppressive therapy is often complicated by the development of both arterial hypertension and renal dysfunction. The principal aim of this study was to assess the effects of dual inhibition of renin-angiotensin system (RAS) and other antihypertensive treatment on blood pressure and ren

  16. Inhibition of Human Immunodeficiency Virus Replication by a Dual CCR5/CXCR4 Antagonist

    Science.gov (United States)

    Princen, Katrien; Hatse, Sigrid; Vermeire, Kurt; Aquaro, Stefano; De Clercq, Erik; Gerlach, Lars-Ole; Rosenkilde, Mette; Schwartz, Thue W.; Skerlj, Renato; Bridger, Gary; Schols, Dominique

    2004-01-01

    Here we report that the N-pyridinylmethyl cyclam analog AMD3451 has antiviral activity against a wide variety of R5, R5/X4, and X4 strains of human immunodeficiency virus type 1 (HIV-1) and HIV-2 (50% inhibitory concentration [IC50] ranging from 1.2 to 26.5 μM) in various T-cell lines, CCR5- or CXCR4-transfected cells, peripheral blood mononuclear cells (PBMCs), and monocytes/macrophages. AMD3451 also inhibited R5, R5/X4, and X4 HIV-1 primary clinical isolates in PBMCs (IC50, 1.8 to 7.3 μM). A PCR-based viral entry assay revealed that AMD3451 blocks R5 and X4 HIV-1 infection at the virus entry stage. AMD3451 dose-dependently inhibited the intracellular Ca2+ signaling induced by the CXCR4 ligand CXCL12 in T-lymphocytic cells and in CXCR4-transfected cells, as well as the Ca2+ flux induced by the CCR5 ligands CCL5, CCL3, and CCL4 in CCR5-transfected cells. The compound did not interfere with chemokine-induced Ca2+ signaling through CCR1, CCR2, CCR3, CCR4, CCR6, CCR9, or CXCR3 and did not induce intracellular Ca2+ signaling by itself at concentrations up to 400 μM. In freshly isolated monocytes, AMD3451 inhibited the Ca2+ flux induced by CXCL12 and CCL4 but not that induced by CCL2, CCL3, CCL5, and CCL7. The CXCL12- and CCL3-induced chemotaxis was also dose-dependently inhibited by AMD3451. Furthermore, AMD3451 inhibited CXCL12- and CCL3L1-induced endocytosis in CXCR4- and CCR5-transfected cells. AMD3451, in contrast to the specific CXCR4 antagonist AMD3100, did not inhibit but enhanced the binding of several anti-CXCR4 monoclonal antibodies (such as clone 12G5) at the cell surface, pointing to a different interaction with CXCR4. AMD3451 is the first low-molecular-weight anti-HIV agent with selective HIV coreceptor, CCR5 and CXCR4, interaction. PMID:15542651

  17. Target enhancement and distractor inhibition affect transitory surround suppression in dual tasks using multiple rapid serial visual presentation streams.

    Science.gov (United States)

    Wu, Xia; Greenwood, Pamela; Fu, Shimin

    2016-01-01

    Few studies have investigated the interaction between temporal and spatial dimensions on selective attention using dual tasks in the multiple rapid serial visual presentation (RSVP) paradigm. A phenomenon that the surround suppression in space changes over time (termed transitory surround suppression, TSS, in the present study) has been observed, suggesting the existence of this time-space interaction. However, it is still unclear whether target enhancement or distractor inhibition modulates TSS. Four behavioural experiments were conducted to investigate the mechanism of TSS by manipulating the temporal lag and spatial distance factors between two targets embedded in six RSVP streams. The TSS effect was replicated in a study that eliminated confounds of perceptual effects and attentional switch (Experiment 1). However, the TSS disappeared when two targets shared the same colour in a between-subjects design (Experiment 2a) and a within-subject design (Experiment 2b), suggesting the impact of target enhancement on TSS. Moreover, the TSS was larger for within-category than for between-category distractors (Experiment 3), indicating the impact of distractor inhibition on TSS. These two influences on TSS under different processing demands of target and distractor processing were further confirmed in a skeletal design (Experiment 4). Overall, combinative effects of target enhancement and distractor suppression contribute to the mechanisms of time-space interaction in selective attention during visual search.

  18. Inhibition of Dual Specific Oncolytic Adenovirus on Esophageal Cancer via Activation of Caspases by a Mitochondrial-dependent Pathway

    Institute of Scientific and Technical Information of China (English)

    SU Jia-qiang; CHI Bao-rong; LI Xiao; LIU Lei; LIU Li-ming; QI Yan-xin; WANG Zhuo-yue; JIN Ning-yi

    2012-01-01

    We investigated the anti-tumor effects of dual cancer specific-oncolytic adenovirus Ad-VP on esophageal cancer(EC).The anti-tumor activity of Ad-VP was compared with that of the control recombinant adenoviruses (Ad-GP,Ad-Apoptin,Ad-EGFP) in human esophageal cancer cell EC-109 and human normal liver cell L02 in vitro.In 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assays,the growth of EC-109 cells was slightly inhibited by Ad-GP.Ad-Apoptin and Ad-EGFP.However,Ad-VP induced a significant cytotoxic effect.Infection of EC-109 cells with Ad-VP resulted in a significant induction of apoptosis of them in vitro,detected by 4′,6-diamidino-2-phenylindole(DAPI) or acridine orange and ethidium bromide staining.The results of Western blot and flow cytometric assay indicate the loss of mitochondrial membrane potential(△ψm),the release of cytochrome c and the activation of caspase-3,6 and 7 in Ad-VP infiected EC-109 cells.In contrast,all these assays show almost no effects of the recombinant adenoviruses on L02 cells.These results demonstrate that the treatment of tumors with Ad-VP selectively inhibits tumor growth and induces apoptosis of esophageal cancer cells.Ad-VP may provide a novel and powerful strategy for cancer gene therapy.

  19. A Versatile Imaging and Therapeutic Platform Based on Dual-Band Luminescent Lanthanide Nanoparticles toward Tumor Metastasis Inhibition.

    Science.gov (United States)

    Li, Yang; Tang, Jinglong; Pan, Dong-Xu; Sun, Ling-Dong; Chen, Chunying; Liu, Ying; Wang, Ye-Fu; Shi, Shuo; Yan, Chun-Hua

    2016-02-23

    Upconversion (UC) luminescent lanthanide nanoparticles (LNPs) are expected to play an important role in imaging and photodynamic therapy (PDT) in vitro and in vivo. However, with the absorption of UC emissions by photosensitizers (PSs) to generate singlet oxygen ((1)O2) for PDT, the imaging signals from LNPs are significantly weakened. It is important to activate another imaging route to track the location of the LNPs during PDT process. In this work, Nd(3+)-sensitized LNPs with dual-band visible and near-infrared (NIR) emissions under single 808 nm excitation were reported to address this issue. The UC emissions in green could trigger covalently linked rose bengal (RB) molecules for efficient PDT, and NIR emissions deriving from Yb(3+) and magnetic resonance imaging (MRI) were used for imaging simultaneously. Notably, the designed therapeutic platform could further effectively avoid the overheating effect induced by the laser irradiation, due to the minimized absorption of biological media at around 808 nm. TdT-mediated dUTP nick end labeling (TUNEL) assay showed serious cell apoptosis in the tumor after PDT for 2 weeks, leading to an effective tumor inhibition rate of 67%. Benefit from the PDT, the tumor growth-induced liver and spleen burdens were largely attenuated, and the liver injury was also alleviated. More importantly, pulmonary and hepatic tumor metastases were significantly reduced after PDT. The Nd(3+)-sensitized LNPs provide a multifunctional nanoplatform for NIR light-assisted PDT with minimized heating effect and an effective inhibition of tumor growth and metastasis.

  20. Impact of neoadjuvant single or dual HER2 inhibition and chemotherapy backbone upon pathological complete response in operable and locally advanced breast cancer: Sensitivity analysis of randomized trials.

    Science.gov (United States)

    Bria, Emilio; Carbognin, Luisa; Furlanetto, Jenny; Pilotto, Sara; Bonomi, Maria; Guarneri, Valentina; Vicentini, Cecilia; Brunelli, Matteo; Nortilli, Rolando; Pellini, Francesca; Sperduti, Isabella; Giannarelli, Diana; Pollini, Giovanni Paolo; Conte, Pierfranco; Tortora, Giampaolo

    2014-08-01

    The role of the dual HER2 inhibition, and the best chemotherapy backbone for neoadjuvant chemotherapy still represent an issue for clinical practice. A literature-based meta-analysis exploring single versus dual HER2 inhibition in terms of pathological complete response (pCR, breast plus axilla) rate and testing the interaction according to the chemotherapy (anthracyclines-taxanes or taxanes) was conducted. In addition, an event-based pooled analysis by extracting activity and safety events and deriving 95% confidence intervals (CI) was accomplished. Fourteen trials (4149 patients) were identified, with 6 trials (1820 patients) included in the meta-analysis and 31 arms (14 trials, 3580 patients) in the event-based pooled analysis. The dual HER2 inhibition significantly improves pCR rate, in the range of 16-19%, regardless of the chemotherapy backbone (relative risk 1.37, 95% CI 1.23-1.53, p<0.0001); pCR was significantly higher in the hormonal receptor negative population, regardless of the HER2 inhibition and type of chemotherapy. pCR and the rate of breast conserving surgery was higher when anthracyclines were added to taxanes, regardless of the HER2 inhibition. Severe neutropenia was higher with the addition of anthracyclines to taxanes, with an absolute difference of 19.7%, despite no differences in febrile neutropenia. While no significant differences according to the HER2 inhibition were found in terms of cardiotoxicity, a slightly difference for grade 3-4 (1.2%) against the addition of anthracyclines was calculated. The dual HER2 inhibition for the neoadjuvant treatment of HER2-positive breast cancer significantly increases pCR; the combination of anthracyclines, taxanes and anti-Her2 agents should be currently considered the standard of care.

  1. Ruthenium-containing P450 inhibitors for dual enzyme inhibition and DNA damage.

    Science.gov (United States)

    Zamora, Ana; Denning, Catherine A; Heidary, David K; Wachter, Erin; Nease, Leona A; Ruiz, José; Glazer, Edith C

    2017-02-14

    Cytochrome P450s are key players in drug metabolism, and overexpression in tumors is associated with significant resistance to many medicinal agents. Consequently, inhibition of P450s could serve as a strategy to restore drug efficacy. However, the widespread expression of P450s throughout the human body and the critical roles they play in various biosynthetic pathways motivates the development of P450 inhibitors capable of controlled local administration. Ruthenium complexes containing P450 inhibitors as ligands were synthesized in order to develop pro-drugs that can be triggered to release the inhibitors in a spatially and temporally controlled fashion. Upon light activation the compounds release ligands that directly bind and inhibit P450 enzymes, while the ruthenium center is able to directly damage DNA.

  2. Inhibition of Monocyte Adhesion to Brain-Derived Endothelial Cells by Dual Functional RNA Chimeras

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2014-01-01

    Full Text Available Because adhesion of leukocytes to endothelial cells is the first step of vascular-neuronal inflammation, inhibition of adhesion and recruitment of leukocytes to vascular endothelial cells will have a beneficial effect on neuroinflammatory diseases. In this study, we used the pRNA of bacteriophage phi29 DNA packaging motor to construct a novel RNA nanoparticle for specific targeting to transferrin receptor (TfR on the murine brain-derived endothelial cells (bEND5 to deliver ICAM-1 siRNA. This RNA nanoparticle (FRS-NPs contained a FB4 aptamer targeting to TfR and a siRNA moiety for silencing the intercellular adhesion molecule-1 (ICAM-1. Our data indicated that this RNA nanoparticle was delivered into murine brain-derived endothelial cells. Furthermore, the siRNA was released from the FRS-NPs in the cells and knocked down ICAM-1 expression in the TNF-α–stimulated cells and in the cells under oxygen-glucose deprivation/reoxygenation (OGD/R condition. The functional end points of the study indicated that FRS-NPs significantly inhibited monocyte adhesion to the bEND5 cells induced by TNF-α and OGD/R. In conclusion, our approach using RNA nanotechnology for siRNA delivery could be potentially applied for inhibition of inflammation in ischemic stroke and other neuroinflammatory diseases, or diseases affecting endothelium of vasculature.

  3. 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.

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

    Science.gov (United States)

    Lannan, Katie L; Refaai, Majed A; Ture, Sara K; Morrell, Craig N; Blumberg, Neil; Phipps, Richard P; Spinelli, Sherry L

    2016-03-01

    Stored platelets undergo biochemical, structural and functional changes that lead to decreased efficacy and safety of platelet transfusions. Not only do platelets acquire markers of activation during storage, but they also fail to respond normally to agonists post-storage. We hypothesized that resveratrol, a cardioprotective antioxidant, could act as a novel platelet storage additive to safely prevent unwanted platelet activation during storage, while simultaneously preserving normal haemostatic function. Human platelets treated with resveratrol and stored for 5 d released less thromboxane B2 and prostaglandin E2 compared to control platelets. Resveratrol preserved the ability of platelets to aggregate, spread and respond to thrombin, suggesting an improved ability to activate post-storage. Utilizing an in vitro model of transfusion and thromboelastography, clot strength was improved with resveratrol treatment compared to conventionally stored platelets. The mechanism of resveratrol's beneficial actions on stored platelets was partly mediated through decreased platelet apoptosis in storage, resulting in a longer half-life following transfusion. Lastly, an in vivo mouse model of transfusion demonstrated that stored platelets are prothrombotic and that resveratrol delayed vessel occlusion time to a level similar to transfusion with fresh platelets. We show resveratrol has a dual ability to reduce unwanted platelet activation during storage, while preserving critical haemostatic function.

  5. Understanding platelet function through signal transduction.

    Science.gov (United States)

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

    2003-01-01

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

  6. Platelet scintigraphy in atherothrombotic disease

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Yoshinari (Osaka National Hospital (Japan))

    1993-01-01

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

  7. 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.

  8. Hemodynamic and hormonal changes to dual renin-angiotensin system inhibition in experimental hypertension.

    Science.gov (United States)

    Moniwa, Norihito; Varagic, Jasmina; Ahmad, Sarfaraz; VonCannon, Jessica L; Simington, Stephen W; Wang, Hao; Groban, Leanne; Brosnihan, K Bridget; Nagata, Sayaka; Kato, Johji; Kitamura, Kazuo; Gomez, R Ariel; Lopez, Maria L Sequeira; Ferrario, Carlos M

    2013-02-01

    We examined the antihypertensive effects of valsartan, aliskiren, or both drugs combined on circulating, cardiac, and renal components of the renin-angiotensin system in congenic mRen2.Lewis hypertensive rats assigned to: vehicle (n=9), valsartan (via drinking water, 30 mg/kg per day; n=10), aliskiren (SC by osmotic mini-pumps, 50 mg/kg per day; n=10), or valsartan (30 mg/kg per day) combined with aliskiren (50 mg/kg per day; n=10). Arterial pressure and heart rate were measured by telemetry before and during 2 weeks of treatment; trunk blood, heart, urine, and kidneys were collected for measures of renin-angiotensin system components. Arterial pressure and left-ventricular weight/tibia length ratio were reduced by monotherapy of valsartan, aliskiren, and further reduced by the combination therapy. Urinary protein excretion was reduced by valsartan and further reduced by the combination. The increases in plasma angiotensin (Ang) II induced by valsartan were reversed by the treatment of aliskiren and partially suppressed by the combination. The decreases in plasma Ang-(1-7) induced by aliskiren recovered in the combination group. Kidney Ang-(1-12) was increased by the combination therapy whereas the increases in urinary creatinine mediated by valsartan were reversed by addition of aliskiren. The antihypertensive and antiproteinuric actions of the combined therapy were associated with marked worsening of renal parenchymal disease and increased peritubular fibrosis. The data show that despite improvements in the surrogate end points of blood pressure, ventricular mass, and proteinuria, dual blockade of Ang II receptors and renin activity is accompanied by worsening of renal parenchymal disease reflecting a renal homeostatic stress response attributable to loss of tubuloglomerular feedback by Ang II.

  9. Positron emission tomographic monitoring of dual phosphatidylinositol-3-kinase and mTOR inhibition in anaplastic large cell lymphoma

    Directory of Open Access Journals (Sweden)

    Graf N

    2014-05-01

    Full Text Available Nicolas Graf,1 Zhoulei Li,2 Ken Herrmann,2,4 Daniel Weh,2 Michaela Aichler,3 Jolanta Slawska,2 Axel Walch,3 Christian Peschel,1 Markus Schwaiger,2 Andreas K Buck,2,4 Tobias Dechow,1,* Ulrich Keller1,* 1III Medical Department, 2Department of Nuclear Medicine, Technische Universität München, Munich, Germany; 3Research Unit Analytical Pathology, Helmholtz Zentrum München, Munich, Germany; 4Department of Nuclear Medicine, Universitätsklinikum Würzburg, Würzburg, Germany *These authors contributed equally to this work Background: Dual phosphatidylinositol-3-kinase (PI3K/mammalian target of rapamycin (mTOR inhibition offers an attractive therapeutic strategy in anaplastic large cell lymphoma depending on oncogenic nucleophosmin-anaplastic lymphoma kinase (NPM-ALK signaling. We tested the efficacy of a novel dual PI3K/mTOR inhibitor, NVP-BGT226 (BGT226, in two anaplastic large cell lymphoma cell lines in vitro and in vivo and performed an early response evaluation with positron emission tomography (PET imaging using the standard tracer, 2-deoxy-2-[18F]fluoro-D-glucose (FDG and the thymidine analog, 3'-deoxy-3'-[18F]fluorothymidine (FLT. Methods: The biological effects of BGT226 were determined in vitro in the NPM-ALK positive cell lines SU-DHL-1 and Karpas299 by 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, propidium iodide staining, and biochemical analysis of PI3K and mTOR downstream signaling. FDG-PET and FLT-PET were performed in immunodeficient mice bearing either SU-DHL-1 or Karpas299 xenografts at baseline and 7 days after initiation of treatment with BGT226. Lymphomas were removed for immunohistochemical analysis of proliferation and apoptosis to correlate PET findings with in vivo treatment effects. Results: SU-DHL-1 cells showed sensitivity to BGT226 in vitro, with cell cycle arrest in G0/G1 phase and an IC50 in the low nanomolar range, in contrast with Karpas299 cells, which were mainly resistant to BGT226. In

  10. 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.

  11. A model-based analysis of the clinical and economic impact of personalising P2Y12-receptor inhibition with platelet function testing in acute coronary syndrome patients.

    Science.gov (United States)

    Straub, Niels; Beivers, Andreas; Lenk, Ekaterina; Aradi, Daniel; Sibbing, Dirk

    2014-02-01

    Although some observational studies reported that the measured level of P2Y12-inhibition is predictive for thrombotic events, the clinical and economic benefit of incorporating PFT to personalize P2Y12-receptor directed antiplatelet treatment is unknown. Here, we assessed the clinical impact and cost-effectiveness of selecting P2Y12-inhibitors based on platelet function testing (PFT) in acute coronary syndrome (ACS) patients undergoing PCI. A decision model was developed to analyse the health economic effects of different strategies. PFT-guided treatment was compared with the three options of general clopidogrel, prasugrel or ticagrelor treatment. In the PFT arm, low responders to clopidogrel received prasugrel, while normal responders carried on with clopidogrel. The associated endpoints in the model were cardiovascular death, stent thrombosis and major bleeding. With a simulated cohort of 10,000 patients treated for one year, there were 93 less events in the PFT arm compared to general clopidogrel. In prasugrel and ticagrelor arms, 110 and 86 events were prevented compared to clopidogrel treatment, respectively. The total expected costs (including event costs, drug costs and PFT costs) for generic clopidogrel therapy were US$ 1,059/patient. In the PFT arm, total costs were US$ 1,494, while in the prasugrel and ticagrelor branches they were US$ 3,102 and US$ 3,771, respectively. The incremental-cost-effectiveness-ratio (ICER) was US$ 46,770 for PFT-guided therapy, US$ 185,783 for prasugrel and US$ 315,360 for ticagrelor. In this model-based analysis, a PFT-guided therapy may have fewer adverse outcomes than general treatment with clopidogrel and may be more cost-effective than prasugrel or ticagrelor treatment in ACS patients undergoing PCI.

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

    Science.gov (United States)

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

    2013-01-01

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

  13. Inhibition of human immunodeficiency virus replication by a dual CCR5/CXCR4 antagonist

    DEFF Research Database (Denmark)

    Princen, Katrien; Hatse, Sigrid; Vermeire, Kurt;

    2004-01-01

    Here we report that the N-pyridinylmethyl cyclam analog AMD3451 has antiviral activity against a wide variety of R5, R5/X4, and X4 strains of human immunodeficiency virus type 1 (HIV-1) and HIV-2 (50% inhibitory concentration [IC(50)] ranging from 1.2 to 26.5 microM) in various T-cell lines, CCR5...... at the virus entry stage. AMD3451 dose-dependently inhibited the intracellular Ca(2+) signaling induced by the CXCR4 ligand CXCL12 in T-lymphocytic cells and in CXCR4-transfected cells, as well as the Ca(2+) flux induced by the CCR5 ligands CCL5, CCL3, and CCL4 in CCR5-transfected cells. The compound did...

  14. Inhibition of HIV Virus by Neutralizing Vhh Attached to Dual Functional Liposomes Encapsulating Dapivirine

    Science.gov (United States)

    Wang, Scarlet Xiaoyan; Michiels, Johan; Ariën, Kevin K.; New, Roger; Vanham, Guido; Roitt, Ivan

    2016-07-01

    efficacy in reducing viral replication in vitro. Thus, dual function liposomes may lead to a novel strategy for the prophylaxis of HIV/AIDS by combining the neutralizing activity of Vhh with antiviral effects of high drug concentrations.

  15. Dual antiplatelet therapy after noncardioembolic ischemic stroke or transient ischemic attack: pros and cons.

    Science.gov (United States)

    Hong, Keun-Sik

    2014-07-01

    Dual antiplatelet therapy simultaneously blocks different platelet activation pathways and might thus be more potent at inhibiting platelet activation and more effective at reducing major ischemic vascular events compared to antiplatelet monotherapy. Aspirin plus clopidogrel dual therapy is now the standard therapy for patients with acute coronary syndrome and for those undergoing percutaneous coronary intervention. However, dual antiplatelet therapy carries an increased risk of bleeding. Patients with ischemic stroke or transient ischemic attack (TIA) are generally older and likely to have a fragile cerebrovascular bed, which further increases the risk of systemic major bleeding events and intracranial hemorrhage. Clinical trials and meta-analyses suggest that in comparison to antiplatelet monotherapy, dual antiplatelet therapy initiated early after noncardioembolic ischemic stroke or TIA further reduces the rate of recurrent stroke and major vascular events without significantly increasing the rate of major bleeding events. In contrast, studies of long-term therapy in patients with noncardioembolic ischemic stroke or TIA have yielded inconsistent data regarding the benefit of dual antiplatelet therapy over monotherapy. However, the harm associated with major bleeding events, including intracranial hemorrhage, which is generally more disabling and more fatal than ischemic stroke, is likely to increase with dual antiplatelet therapy. Physicians should carefully assess the benefits and risks of dual antiplatelet therapy versus antiplatelet monotherapy when managing patients with ischemic stroke or TIA.

  16. Dual Role of a Biosynthetic Enzyme, CysK, in Contact Dependent Growth Inhibition in Bacteria.

    Directory of Open Access Journals (Sweden)

    Soni Kaundal

    Full Text Available Contact dependent growth inhibition (CDI is the phenomenon where CDI+ bacterial strain (inhibitor inhibits the growth of CDI-strain (target by direct cell to cell contact. CDI is mediated by cdiBAI gene cluster where CdiB facilitates the export of CdiA, an exotoxin, on the cell surface and CdiI acts as an immunity protein to protect CDI+ cells from autoinhibition. CdiA-CT, the C-terminal region of the toxin CdiA, from uropathogenic Escherichia coli strain 536 (UPEC536 is a latent tRNase that requires binding of a biosynthetic enzyme CysK (O-acetylserine sulfyhydrylase for activation in the target cells. CdiA-CT can also interact simultaneously with CysK and immunity protein, CdiI, to form a ternary complex in UPEC536. But the role of CysK in the ternary complex is not clear. We studied the hydrodynamic, thermodynamic and kinetic parameters of binary and ternary complexes using AUC, ITC and SPR respectively, to investigate the role of CysK in UPEC536. We report that CdiA-CT binds CdiI and CysK with nanomolar range affinity. We further report that binding of CysK to CdiA-CT improves its affinity towards CdiI by ~40 fold resulting in the formation of a more stable complex with over ~130 fold decrease in dissociation rate. Thermal melting experiments also suggest the role of CysK in stabilizing CdiA-CT/CdiI complex as Tm of the binary complex shifts ~10°C upon binding CysK. Hence, CysK acts a modulator of CdiA-CT/CdiI interactions by stabilizing CdiA-CT/CdiI complex and may play a crucial role in preventing autoinhibition in UPEC536. This study reports a new moonlighting function of a biosynthetic enzyme, CysK, as a modulator of toxin/immunity interactions in UPEC536 inhibitor cells.

  17. Overcoming paclitaxel resistance in lung cancer cells via dual inhibition of stathmin and Bcl-2.

    Science.gov (United States)

    Han, Zheng-Xiang; Wang, Hong-Mei; Jiang, Guan; Du, Xiu-Ping; Gao, Xiang-Yang; Pei, Dong-Sheng

    2013-06-01

    Lung cancer is the leading cause of death from malignancy in people and over 85% of these patients eventually die from disseminated disease. Paclitaxel (TAX) is widely used as an antimicrotubule agent for the treatment of lung cancer. Unfortunately, the resistance to this antimicrotubule agent occurs frequently. Stathmin (STMN1) is a ubiquitous microtubule destabilizing protein linked to cancer and cell health and its expression level often correlates with cancer stage progression and prognosis for survival. Overexpression of the antiapoptotic protein Bcl-2 has been shown to prolong drug-induced growth arrest, potentially inducing resistance. In this study, we used a short hairpin RNA (shRNA) approach to evaluate the effect of STMN1 and Bcl-2 downregulation in the sensitivity to TAX in lung cancer cells. We achieved significant downregulation of STMN1 and Bcl-2 mRNA and protein expression by a combination of double shRNA treatment strategy. Our experimental data showed that inhibition of STMN1 and Bcl-2 expression with RNA interference can sensitize lung cancer cells to TAX. These findings suggest a novel approach to improve the efficacy of certain antimicrotubule agents against lung cancer by regulating the function of STMN1 and Bcl-2.

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

    Science.gov (United States)

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

    2011-01-01

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

  19. 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)

  20. Platelets kill intraerythrocytic malarial parasites and mediate survival to infection.

    Science.gov (United States)

    McMorran, Brendan J; Marshall, Vikki M; de Graaf, Carolyn; Drysdale, Karen E; Shabbar, Meriam; Smyth, Gordon K; Corbin, Jason E; Alexander, Warren S; Foote, Simon J

    2009-02-01

    Platelets play a critical role in the pathogenesis of malarial infections by encouraging the sequestration of infected red blood cells within the cerebral vasculature. But platelets also have well-established roles in innate protection against microbial infections. We found that purified human platelets killed Plasmodium falciparum parasites cultured in red blood cells. Inhibition of platelet function by aspirin and other platelet inhibitors abrogated the lethal effect human platelets exert on P. falciparum parasites. Likewise, platelet-deficient and aspirin-treated mice were more susceptible to death during erythrocytic infection with Plasmodium chabaudi. Both mouse and human platelets bind malarial-infected red cells and kill the parasite within. These results indicate a protective function for platelets in the early stages of erythrocytic infection distinct from their role in cerebral malaria.

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

    Science.gov (United States)

    Wang, Xin-Hua; Di, Yan-Hui

    2014-06-01

    This study was purposed to explore the mechanism of cooked blanched garlic leave juice against platelet aggregation. The juice of blanched garlic leaves was mixed with platelet rich plasma (PRP), the human platelet aggregation, the activation of human platelets induced by adenosine diphosphate (ADP) and collagen were observed; the expression levels of the activated platelets (Fib-R) and P-selectin (CD62P), and the amount of platelet fibrinogen binding were detected by flow cytometry; 10 rabbits were randomly divided into two groups, in addition to the normal diet, they were fed with physiologic saline and cooked blanched garlic leave juice respectively. After 1, 3, 5 , 8 weeks, the maximum ratio of rabbit platelet aggregation induced by ADP and collagen were observed . The results showed that the cooked blanched garlic leave juice could significantly inhibit human platelet aggregation induced by ADP and collagen (P 0.05), but was able to inhibit platelet fibrinogen binding capacity (P garlic leave juice was significantly lower than that in control group (P garlic leave juice can inhibit platelet aggregation in vitro and in vivo, the inhibition of aggregation pathway mainly is blocking the combination of fibrinogen with Fib-R, which finally results in the inhibition of platelet aggregation. Therefore, regular consumption of cooked blanched garlic leaves may prevent cardiovascular thrombotic diseases.

  2. In vitro effects of buyang huanwu decoction and its ingredients on inhibiting the specific binding of 3H-platelet activating factor to its receptor in rabbits

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND: Pharmacologic action of traditional Chinese medicine compound is the comprehensive effect of various ingredients, and the interactions of various ingredients are closely correlated with the final effect. In order to reveal the compatibility mechanism of buyang huanwu decoction (BHD)'s prescription in treating and preventing ischemic cerebrovascular disease, we need to explore the effect and relation of ingredients in prescription except for considering the effect of each ingredient on the whole prescription.OBJECTIVE: To study the effect of BHD and its ingredients in the prescription on the specific binding of 3H-platelet activating factor (PAF) to its receptor (PAFR)in rabbits in vitro, and to analyze the action of each ingredient in the prescription.DESIGN: A decomposed recipe study based on orthogonal test.SETTING: Guangzhou University of Traditional Chinese Medicine.MATERIALS: Five healthy adult New Zealand rabbits of either gender were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese medicine. The prescription herbal pieces were purchased from Foshan Kangpu Pharmaceuticals Company and Jianmin Pharmaceuticals Company, and were appraised by Professor Yanchen Xu from College of Traditional Chinese Medicine, Guangzhou University of Traditional Chinese Medicine. 3H-PAF was supplied by Amersham Co.,Ltd.(Specific activity:6.475 TBq/mmol;batch number:200402); PAF standard by Biomol Co., Ltd.(batch number: P1318V).METHODS: This experiment was carried out in the Laboratory of Nuclear Medicine, Guangzhou University of Traditional Chinese Medicine between September and December 2004. ① The seven influencing factors were selected: such as Shenghuangqi , Dangguiwei, Chishao, Dilong, Taoren, Honghua, Chuanxiong. Each factor was divided into two levels, selected or not selected. The tests were arranged according to L8 (27) orthogonal test table. ②The specific binding of 3H-PAF to its receptors in rabbits was measured by

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

    OpenAIRE

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

    2012-01-01

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

  4. Lapatinib, a dual EGFR and HER2 tyrosine kinase inhibitor, downregulates thymidylate synthase by inhibiting the nuclear translocation of EGFR and HER2.

    Directory of Open Access Journals (Sweden)

    Hwang-Phill Kim

    Full Text Available BACKGROUND: Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI has been shown to exert a synergistic antitumor effect when combined with fluoropyrimidine. This synergy may be attributable to the downregulation of thymidylate synthase (TS, which is frequently overexpressed in fluoropyrimidine-resistant cancer cells. However, the molecular mechanism underlying the downregulation of TS has yet to be clearly elucidated. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we demonstrate that lapatinib, a dual TKI of EGFR and HER2 downregulates TS via inhibition of the nuclear translocation of EGFR and HER2. From our cDNA microarray experiments, we determined that a variety of nucleotide synthesis-related genes, including TS, were downregulated with lapatinib, and this was apparent in HER2-amplified cells. Targeted and pharmacologic inhibition assays confirmed that the dual inhibition of EGFR and HER2 is required for the more effective reduction of TS as compared to what was observed with gefitinib or trasutuzumab alone. Additionally, we determined that co-transfected EGFR and HER2 activate the TS gene promoter more profoundly than do either EGFR or HER2 alone. The translocation of EGFR and HER2 into the nucleus and the subsequent activation of the TS promoter were inhibited by lapatinib. CONCLUSIONS AND SIGNIFICANCE: These results demonstrate that lapatinib inhibits the nuclear translocation of EGFR and HER2 and downregulates TS, thus sensitizing cancer cells to fluoropyrimidine.

  5. Consistent Reduction in Periprocedural Myocardial Infarction With Cangrelor as Assessed by Multiple Definitions: Findings From CHAMPION PHOENIX (Cangrelor Versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition).

    Science.gov (United States)

    Cavender, Matthew A; Bhatt, Deepak L; Stone, Gregg W; White, Harvey D; Steg, Ph Gabriel; Gibson, C Michael; Hamm, Christian W; Price, Matthew J; Leonardi, Sergio; Prats, Jayne; Deliargyris, Efthymios N; Mahaffey, Kenneth W; Harrington, Robert A

    2016-09-06

    Cangrelor is an intravenous P2Y12 inhibitor approved to reduce periprocedural ischemic events in patients undergoing percutaneous coronary intervention not pretreated with a P2Y12 inhibitor. A total of 11 145 patients were randomized to cangrelor or clopidogrel in the CHAMPION PHOENIX trial (Cangrelor versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition). We explored the effects of cangrelor on myocardial infarction (MI) using different definitions and performed sensitivity analyses on the primary end point of the trial. A total of 462 patients (4.2%) undergoing percutaneous coronary intervention had an MI as defined by the second universal definition. The majority of these MIs (n=433, 93.7%) were type 4a. Treatment with cangrelor reduced the incidence of MI at 48 hours (3.8% versus 4.7%; odds ratio [OR], 0.80; 95% confidence interval [CI], 0.67-0.97; P=0.02). When the Society of Coronary Angiography and Intervention definition of periprocedural MI was applied to potential ischemic events, there were fewer total MIs (n=134); however, the effects of cangrelor on MI remained significant (OR, 0.65; 95% CI, 0.46-0.92; P=0.01). Similar effects were seen in the evaluation of the effects of cangrelor on MIs with peak creatinine kinase-MB ≥10 times the upper limit of normal (OR, 0.64; 95% CI, 0.45-0.91) and those with peak creatinine kinase-MB ≥10 times the upper limit of normal, ischemic symptoms, or ECG changes (OR, 0.63; 95% CI, 0.48-0.84). MIs defined by any of these definitions were associated with increased risk of death at 30 days. Treatment with cangrelor reduced the composite end point of death, MI (Society of Coronary Angiography and Intervention definition), ischemia-driven revascularization, or Academic Research Consortium definite stent thrombosis (1.4% versus 2.1%; OR, 0.69; 95% CI, 0.51-0.92). MI in patients undergoing percutaneous coronary intervention, regardless of definition, remains associated with increased risk of death

  6. High residual platelet reactivity during dual antiplatelet therapy, found by optical aggregometry and the rate of atherothrombotic complications after coronary artery stenting in patients with ischemic heart disease in clinical practice

    Directory of Open Access Journals (Sweden)

    N. F. Puchinyan

    2016-01-01

    Full Text Available Aim. To study the prevalence of high residual platelet reactivity (HRPR during the dual antiplatelet therapy (DAT with acetylsalicylic acid (ASA and clopidogrel by optical aggregometry in patients with ischemic heart disease (IHD after percutaneous transluminal coronary angioplasty (PTCA in clinical practice, as well as to determine its value for the prediction of clinical course and outcome of disease.Material and methods. Patients after PTCA and during DAT were included into the study. Evaluation of the functional activity of platelets by optical aggregometry was performed in all patients at baseline. Resistance to ASA, clopidogrel and DAT were detected. Endpoints included cases of repeated atherothrombotic events (sudden cardiac death, myocardial infarction, unstable angina, ischemic stroke, stent thrombosis. Adherence to therapy was evaluated by Morisky-Green test.Results. 97 patients were included into the final analysis. The risk of myocardial infarction or unstable angina pectoris in the ASA-resistant patients was significantly higher than this in the DAT-sensitive patients [relative risk (RR=7.68; 95% confidence interval (CI 2.8-20.54; p=0.045]. Maximum RR for stent thrombosis was in clopidogrel-resistant (RR=7.1; 95% CI 1.41-35.82; p=0.0485 and DAT-resistant patients (RR=12.8; 95% CI 4.5-36.38; p=0.0491, compared with patients with a sensitivity to antiplatelet therapy. DAT-resistance was associated with a higher RR of the combined endpoint, compared with the sensitivity to antiplatelet therapy (RR=10.24; 95% CI 3.96-26.5; p=0.046], and have a tendency to association with increased risk of combined endpoint compared with isolated ASA-resistance (RR=1.3; 95% CI 0.68-2.6; p=0.081.Conclusion. HRPR during DAT is common in clinical practice in patients with ischemic heart disease after PTCA. Routine use of optical aggregometry in DAT may help to identify patients with an increased risk of thrombotic events in the postoperative period and to

  7. Expansion of the neonatal platelet mass is achieved via an extension of platelet lifespan.

    Science.gov (United States)

    Liu, Zhi-Jian; Hoffmeister, Karin M; Hu, Zhongbo; Mager, Donald E; Ait-Oudhia, Sihem; Debrincat, Marlyse A; Pleines, Irina; Josefsson, Emma C; Kile, Benjamin T; Italiano, Joseph; Ramsey, Haley; Grozovsky, Renata; Veng-Pedersen, Peter; Chavda, Chaitanya; Sola-Visner, Martha

    2014-05-29

    The fetal/neonatal hematopoietic system must generate enough blood cells to meet the demands of rapid growth. This unique challenge might underlie the high incidence of thrombocytopenia among preterm neonates. In this study, neonatal platelet production and turnover were investigated in newborn mice. Based on a combination of blood volume expansion and increasing platelet counts, the platelet mass increased sevenfold during the first 2 weeks of murine life, a time during which thrombopoiesis shifted from liver to bone marrow. Studies applying in vivo biotinylation and mathematical modeling showed that newborn and adult mice had similar platelet production rates, but neonatal platelets survived 1 day longer in circulation. This prolonged lifespan fully accounted for the rise in platelet counts observed during the second week of murine postnatal life. A study of pro-apoptotic and anti-apoptotic Bcl-2 family proteins showed that neonatal platelets had higher levels of the anti-apoptotic protein Bcl-2 and were more resistant to apoptosis induced by the Bcl-2/Bcl-xL inhibitor ABT-737 than adult platelets. However, genetic ablation or pharmacologic inhibition of Bcl-2 alone did not shorten neonatal platelet survival or reduce platelet counts in newborn mice, indicating the existence of redundant or alternative mechanisms mediating the prolonged lifespan of neonatal platelets. © 2014 by The American Society of Hematology.

  8. Platelet Function Tests

    Science.gov (United States)

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

  9. Congenital platelet function defects

    Science.gov (United States)

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

  10. Platelet production in hypoxic and RBC-transfused mice

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, T.P.

    1978-01-01

    Platelet production rates were studied in hypoxic, red blood cell (RBC) transfused, and normal mice. In addition, platelet depletion was induced in some of the mice by injection of rabbit anti-mouse platelet serum (RAMPS) to stimulate platelet production. Hypoxia alone caused an increase in haematocrit and platelet count at 1 to 3 d, followed by a decrease in platelet counts to below normal values at 6 to 7 d. On the other hand, RBC transfusion caused increased haematocrit and decreased platelet count of mice at 1 to 4 d, with a return of platelet counts to normal by 5 to 6 d. Normal mice and mice transfused with RBC responded to platelet depletion with rebound-thrombocytosis with maximum platelet production 3 to 5 d later and elevated platelet counts on day 5 to 6. However, platelet production in platelet-depleted mice exposed to hypoxia was less marked, and platelet counts did not reach normal levels. The data are consistent with the hypothesis that hypoxia causes thrombocytopenia by stem cell competition between erythroid and megakaryocytic cell lines and/or inhibition of thrombopoietin production.

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

    Science.gov (United States)

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

    2012-01-01

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

  12. 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.

  13. Impressive response to dual BRAF and MEK inhibition in patients with BRAF mutant intrahepatic cholangiocarcinoma—2 case reports and a brief review

    Science.gov (United States)

    Lavingia, Viraj

    2016-01-01

    Intrahepatic cholangiocarcinoma (ICC) typically presents at an advanced stage and is associated with a poor oncological outcome. The median survival for metastatic ICC is less than 1 year with standard chemotherapy. ICC is associated with distinct oncogenic drivers including IDH (isocitrate dehydrogenase), HER-2 (human epidermal growth factor 2), and BRAF (v-Raf murine sarcoma viral oncogene homolog B), which may benefit from matching targeted therapies. Hereby we report 2 cases of BRAF V600E refractory ICC treated with dual BRAF and MEK inhibitors (dabrafenib and trametinib) with excellent clinical and radiological response to therapy and with protracted duration of disease control. Our first patient achieved CR (complete remission) at 6 months of treatment with ultimate disease progression at 9 months. The second patient achieved a PR (partial response) at 2 months from starting treatment and remains progression free at 5 months. Our results confirm the activity of dual BRAF and MEK targeting in BRAF mutated ICC, adding further support to 3 additional case-reports in the literature. Dual targeting appears superior to other case reports with BRAF inhibition alone and appear favorable to historic data with cytotoxic chemotherapy. Given the poor outlook and refractoriness of BRAF mutant ICC, future studies should focus on early integration of BRAF/MEK inhibition. PMID:28078132

  14. Dual Inhibition of Bruton's Tyrosine Kinase and Phosphoinositide-3-Kinase p110δ as a Therapeutic Approach to Treat Non-Hodgkin's B Cell Malignancies.

    Science.gov (United States)

    Alfaro, Jennifer; Pérez de Arce, Felipe; Belmar, Sebastián; Fuentealba, Glenda; Avila, Patricio; Ureta, Gonzalo; Flores, Camila; Acuña, Claudia; Delgado, Luz; Gaete, Diana; Pujala, Brahmam; Barde, Anup; Nayak, Anjan K; Upendra, T V R; Patel, Dhananjay; Chauhan, Shailender; Sharma, Vijay K; Kanno, Stacy; Almirez, Ramona G; Hung, David T; Chakravarty, Sarvajit; Rai, Roopa; Bernales, Sebastián; Quinn, Kevin P; Pham, Son M; McCullagh, Emma

    2017-05-01

    Although new targeted therapies, such as ibrutinib and idelalisib, have made a large impact on non-Hodgkin's lymphoma (NHL) patients, the disease is often fatal because patients are initially resistant to these targeted therapies, or because they eventually develop resistance. New drugs and treatments are necessary for these patients. One attractive approach is to inhibit multiple parallel pathways that drive the growth of these hematologic tumors, possibly prolonging the duration of the response and reducing resistance. Early clinical trials have tested this approach by dosing two drugs in combination in NHL patients. We discovered a single molecule, MDVN1003 (1-(5-amino-2,3-dihydro-1H-inden-2-yl)-3-(8-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine), that inhibits Bruton's tyrosine kinase and phosphatidylinositol-3-kinase δ, two proteins regulated by the B cell receptor that drive the growth of many NHLs. In this report, we show that this dual inhibitor prevents the activation of B cells and inhibits the phosphorylation of protein kinase B and extracellular signal-regulated kinase 1/2, two downstream mediators that are important for this process. Additionally, MDVN1003 induces cell death in a B cell lymphoma cell line but not in an irrelevant erythroblast cell line. Importantly, we found that this orally bioavailable dual inhibitor reduced tumor growth in a B cell lymphoma xenograft model more effectively than either ibrutinib or idelalisib. Taken together, these results suggest that dual inhibition of these two key pathways by a single molecule could be a viable approach for treatment of NHL patients. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  15. LIPOPOLYSACCHARIDE INDUCES EXPOSURE OF FIBRINOGEN RECEPTORS ON HUMAN PLATELETS

    Institute of Scientific and Technical Information of China (English)

    于希春; 吴其夏

    1995-01-01

    The effect of lipopolysaccharide (LPS) on the exposure of platelet fibrinogen receptors was investigated.The results showed that:1)LPS increased the binding of fibrinogen-gold complexes to platelets and the labels were primarily limited to shape-changed platelets;2)LPS caused a dose-dependent rise in intracellular Ca2+ concentration in platelets;3)LPS induced the activation of platelet protein kinase C(PKC) and the phosphorylation of glycoprotein llla (GP llla) which was inhibited by H-7.All these results suggest that stimulation of platelets with LPS causes a conformational change in glycoprotein llb/Illa (GPllb/llla) through platelet shape change and/or phosphorylation of GPllla via PKC,which serves to expose the fibrinogen binding sites of GPllb/llla on human platelets.

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

    Science.gov (United States)

    Reed, G. L.; Matsueda, G. R.; Haber, E.

    1992-01-01

    Platelet clots resist fibrinolysis by plasminogen activators. We hypothesized that platelet factor XIII may enhance the fibrinolytic resistance of platelet-rich clots by catalyzing the crosslinking of alpha 2-antiplasmin (alpha 2AP) to fibrin. Analysis of plasma clot structure by polyacrylamide gel electrophoresis and immunoblotting revealed accelerated alpha 2AP-fibrin crosslinking in platelet-rich compared with platelet-depleted plasma clots. A similar study of clots formed with purified fibrinogen (depleted of factor XIII activity), isolated platelets, and specific factor XIII inhibitors indicated that this accelerated crosslinking was due to the catalytic activity of platelet factor XIII. Moreover, when washed platelets were aggregated by thrombin, there was evidence of platelet factor XIII-mediated crosslinking between platelet alpha 2AP and platelet fibrin(ogen). Specific inhibition (by a monoclonal antibody) of the alpha 2AP associated with washed platelet aggregates accelerated the fibrinolysis of the platelet aggregate. Thus in platelet-rich plasma clots, and in thrombin-induced platelet aggregates, platelet factor XIII actively formed alpha 2AP-fibrin crosslinks, which appeared to enhance the resistance of platelet-rich clots to fibrinolysis.

  17. Inhibition of the development of morphine tolerance by a potent dual mu-delta-opioid antagonist, H-Dmt-Tic-Lys-NH-CH2-Ph.

    Science.gov (United States)

    Jinsmaa, Yunden; Marczak, Ewa D; Balboni, Gianfranco; Salvadori, Severo; Lazarus, Lawrence H

    2008-10-01

    Three analogues of the dual mu-/delta-antagonist, H-Dmt-Tic-R-NH-CH2-Ph (R = 1, Lys-Z; 2, Lys-Ac; 3, Lys) were examined in vivo: 1 and 2 exhibited weak bioactivity, while 3 injected intracerebroventricularly was a potent dual antagonist for morphine- and deltorphin C-induced antinociception comparable to naltrindole (delta-antagonist), but 93% as effective as naloxone (nonspecific opioid receptor antagonist) and 4% as active as CTOP, a mu antagonist. Subcutaneous or oral administration of 3 antagonized morphine-induced antinociception indicating passage across epithelial and blood-brain barriers. Mice pretreated with 3 before morphine did not develop morphine tolerance indicative of a potential clinical role to inhibit development of drug tolerance.

  18. Multifunctions of dual Zn/Mg ion co-implanted titanium on osteogenesis, angiogenesis and bacteria inhibition for dental implants.

    Science.gov (United States)

    Yu, Yiqiang; Jin, Guodong; Xue, Yang; Wang, Donghui; Liu, Xuanyong; Sun, Jiao

    2017-02-01

    In order to improve the osseointegration and long-term survival of dental implants, it is urgent to develop a multifunctional titanium surface which would simultaneously have osteogeneic, angiogeneic and antibacterial properties. In this study, a potential dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed via plasma immersion ion implantation (PIII). The Zn/Mg-PIII surfaces were found to promote initial adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) via the upregulation of the gene expression of integrin α1 and integrin β1. More importantly, it was revealed that Zn/Mg-PIII could increase Zn(2+) and Mg(2+) concentrations in rBMSCs by promoting the influx of Zn(2+) and Mg(2+) and inhibiting the outflow of Zn(2+), and then could enhance the transcription of Runx2 and the expression of ALP and OCN. Meanwhile, Mg(2+) ions from Zn/Mg-PIII increased Mg(2+) influx by upregulating the expression of MagT1 transporter in human umbilical vein endothelial cells (HUVECs), and then stimulated the transcription of VEGF and KDR via activation of hypoxia inducing factor (HIF)-1α, thus inducing angiogenesis. In addition to this, it was discovered that zinc in Zn/Mg-PIII had certain inhibitory effects on oral anaerobic bacteria (Pg, Fn and Sm). Finally, the Zn/Mg-PIII implants were implanted in rabbit femurs for 4 and 12weeks with Zn-PIII, Mg-PIII and pure titanium as controls. Micro-CT evaluation, sequential fluorescent labeling, histological analysis and push-out test consistently demonstrated that Zn/Mg-PIII implants exhibit superior capacities for enhancing bone formation, angiogenesis and osseointegration, while consequently increasing the bonding strength at bone-implant interfaces. All these results suggest that due to the multiple functions co-produced by zinc and magnesium, rapid osseointegration and sustained biomechanical stability are enhanced by the novel Zn/Mg-PIII implants, which have the potential

  19. Indium-111-labeled platelet scintigraphy in carotid atherosclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Minar, E.; Ehringer, H.; Dudczak, R.; Schoefl, R.J.; Jung, M.; Koppensteiner, R.; Ahmadi, R.; Kretschmer, G.

    1989-01-01

    We evaluated platelet accumulation in carotid arteries by means of a dual-radiotracer method, using indium-111-labeled platelets and technetium-99m-labeled human serum albumin, in 123 patients (92 men, 31 women; median age 60 years). Sixty patients had symptoms of transient ischemic carotid artery disease, and 63 patients with peripheral arterial occlusive disease served as controls. Antiplatelet treatment with acetylsalicylic acid was taken by 53 of the 123 patients. In 36 of the 60 symptomatic patients, platelet scintigraphy was repeated 3-4 days after carotid endarterectomy. Comparison of different scintigraphic parameters (platelet accumulation index and percent of the injected dose of labeled platelets at the carotid bifurcation) showed no significant differences between symptomatic and asymptomatic patients, and the severity of stenosis and the presence of plaque ulceration also had no influence on the parameters. There was no difference between patients with a short (less than 4 weeks) or long (greater than 4 weeks) interval from the last transient ischemic attack to scintigraphy and no difference between patients with or without antiplatelet treatment. Classifying the patients according to plaque morphology judged by high-resolution real-time ultrasonography also demonstrated no differences. No significant correlation was found between any scintigraphic parameter and other platelet function parameters such as platelet survival time, platelet turnover rate, and concentration of platelet-specific proteins. Quantification of platelet deposition after carotid endarterectomy in 36 patients demonstrated a significant increase of the median platelet accumulation index and the percent injected dose index.

  20. The effect of FAAH, MAGL, and Dual FAAH/MAGL inhibition on inflammatory and colorectal distension-induced visceral pain models in Rodents.

    Science.gov (United States)

    Sakin, Y S; Dogrul, A; Ilkaya, F; Seyrek, M; Ulas, U H; Gulsen, M; Bagci, S

    2015-07-01

    Recent studies showed that the pharmacological inhibition of endocannabinoid degrading enzymes such as fatty acid amide hydrolase (FAAH) and monoacyl glycerol lipase (MAGL) elicit promising analgesic effects in a variety of nociceptive models without serious side effects. However, the full spectrum of activities is not observed upon inhibition of either FAAH or MAGL enzymes alone and thus dual FAAH and MAGL inhibitors have been described. Visceral pain is strongly associated with inflammation and distension of the gut. Thus, we explored the comparable effects of FAAH, MAGL, and dual FAAH/MAGL inhibitors on inflammatory and mechanically evoked visceral pain models. Visceral inflammatory and distension-induced pain were assessed with the 0.6% acetic acid writhing test in mice and colorectal distension (CRD) test in rats, respectively. The selective FAAH inhibitor PF 3845, MAGL inhibitor JZL 184, dual inhibitor JZL 195, and the cannabis analog CP 55,940 were given systemically 30 min prior to nociceptive testing. PF 3845 (5, 10, and 20 mg/kg), JZL 184 (5, 10, and 20 mg/kg), and JZL 195 (5, 10, and 20 mg/kg) elicit dose-dependent antinociceptive in the acetic acid writhing test. In the CRD model, while JZL 195 (5, 10, or 20 mg/kg) and PF3845 (10, 20, and 40 mg/kg) produced dose-dependent antinociceptive effects comparable to those of CP 55,940 (0.1, 0.3, or 1 mg/kg), JZL 184 (10, 20, and 40 mg/kg) alone did not alter the visceromotor response (VMR). The selective FAAH inhibitor and dual FAAH/MAGL inhibitors were effective in both inflammatory and mechanically evoked visceral pain, while the MAGL inhibitor elicited an analgesic effect in inflammatory, but not in distension-induced, visceral pain. © 2015 John Wiley & Sons Ltd.

  1. Modulatory effect of coffee on platelet function.

    Science.gov (United States)

    Bhaskar, Shobha; Rauf, Arun A

    2010-01-01

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

  2. Effects of clopidogrel and aspirin in combination versus aspirin alone on platelet activation and major receptor expression in diabetic patients: the PLavix Use for Treatment Of Diabetes (PLUTO-Diabetes) trial.

    Science.gov (United States)

    Serebruany, Victor L; Malinin, Alex I; Pokov, Alex; Barsness, Gregory; Hanley, Dan F

    2008-01-01

    Clopidogrel is widely used in diabetic patients after vascular events; however, the ability of this thienopyridine to yield additional antiplatelet protection on top of aspirin has never been explored in a controlled study with comprehensive assessment of platelet activity. The objective of this study was to compare the antiplatelet profiles of clopidogrel + aspirin in combination (C + ASA) versus aspirin alone (ASA) in patients with type 2 diabetes mellitus. Seventy patients with documented diabetes already treated with antecedent aspirin were randomly assigned to receive C + ASA or ASA in the PLUTO-Diabetes trial. Platelet studies included adenosine diphosphate-, collagen-, and arachidonic acid-induced aggregometry; PFA-100 (Dade-Behring, Miami, FL) and Ultegra (Accumetrics, San Diego, CA) analyzers; and expression of 6 major receptors by flow cytometry at baseline and at day 30 after randomization. There were no differences in the baseline clinical and platelet characteristics between the C + ASA and ASA groups, or subsequent significant changes in platelet biomarkers in the ASA group, except for diminished collagen-induced aggregation (P = .02). In contrast, when compared with the ASA group, therapy with C + ASA resulted in significant inhibition of platelet activity assessed by adenosine diphosphate aggregation (P = .0001); closure time prolongation (P = .0003) and reduction of platelet activation units with Ultegra (P = .0001); and expression of platelet/endothelial cell adhesion molecule 1 (P = .002), glycoprotein IIb/IIIa antigen (P = .0002), and activity (P = .0001). Treatment with C + ASA for 1 month provides significantly greater inhibition of platelet activity than ASA alone in diabetic patients in this small randomized trial. However, despite dual antiplatelet regimen, diabetic patients exhibit high residual activity of some platelet biomarkers, including unaffected protease-activated receptor 1 receptor expression.

  3. Synthetic antimicrobial β-peptide in dual-treatment with fluconazole or ketoconazole enhances the in vitro inhibition of planktonic and biofilm Candida albicans.

    Science.gov (United States)

    Mora-Navarro, Camilo; Caraballo-León, Jean; Torres-Lugo, Madeline; Ortiz-Bermúdez, Patricia

    2015-12-01

    Fungal infections are a pressing concern for human health worldwide, particularly for immunocompromised individuals. Current challenges such as the elevated toxicity of common antifungal drugs and the emerging resistance towards these could be overcome by multidrug therapy. Natural antimicrobial peptides, AMPs, in combination with other antifungal agents are a promising avenue to address the prevailing challenges. However, they possess limited biostability and susceptibility to proteases, which has significantly hampered their development as antifungal therapies. β-peptides are synthetic materials designed to mimic AMPs while allowing high tunability and increased biostability. In this work, we report for the first time the inhibition achieved in Candida albicans when treated with a mixture of a β-peptide model and fluconazole or ketoconazole. This combination treatment enhanced the biological activity of these azoles in planktonic and biofilm Candida, and also in a fluconazole-resistant strain. Furthermore, the in vitro cytotoxicity of the dual treatment was evaluated towards the human hepatoma cell line, HepG2, a widely used model derived from liver tissue, which is primarily affected by azoles. Analyses based on the LA-based method and the mass-action law principle, using a microtiter checkerboard approach, revealed synergism of the combination treatment in the inhibition of planktonic C. albicans. The dual treatment proved to be fungicidal at 48 and 72 h. Interestingly, it was also found that the viability of HepG2 was not significantly affected by the dual treatments. Finally, a remarkable enhancement in the inhibition of the highly azole-resistant biofilms and fluconazole resistant C. albicans strain was obtained.

  4. APE1/Ref-1 regulates STAT3 transcriptional activity and APE1/Ref-1-STAT3 dual-targeting effectively inhibits pancreatic cancer cell survival.

    Science.gov (United States)

    Cardoso, Angelo A; Jiang, Yanlin; Luo, Meihua; Reed, April M; Shahda, Safi; He, Ying; Maitra, Anirban; Kelley, Mark R; Fishel, Melissa L

    2012-01-01

    Pancreatic cancer is a largely incurable disease, and increasing evidence supports strategies targeting multiple molecular mediators of critical functions of pancreatic ductal adenocarcinoma cells. Intracellular redox state modulates the activity of various signal transduction pathways and biological processes, including cell survival, drug resistance and responsiveness to microenvironmental factors. Recently, it has been shown that the transcription factor STAT3 is under redox control, but the mechanisms involved in its regulation are unknown. Here, we demonstrate for the first time that STAT3 DNA binding and transcriptional activity is directly regulated by the redox function of the APE1/Ref-1 endonuclease, using overexpression and redox-specific mutational strategies, and gene knockdown. Also, pharmacological blockade of APE1/Ref-1 by the redox-selective inhibitor E3330 abrogates STAT3 DNA binding. Since APE1/Ref-1 also exerts redox control on other cancer-associated transcription factors, we assessed the impact of dual-targeting of STAT3 signaling and APE1/Ref-1 redox on pancreatic cancer cell functions. We observed that disruption of APE1/Ref-1 redox activity synergizes with STAT3 blockade to potently inhibit the proliferation and viability of human PDAC cells. Mechanistically, we show that STAT3-APE1/Ref-1 dual targeting promotes marked tumor cell apoptosis, with engagement of caspase-3 signaling, which are significantly increased in comparison to the effects triggered by single target blockade. Also, we show that STAT3-APE1/Ref-1 dual blockade results in significant inhibition of tumor cell migration. Overall, this work demonstrates that the transcriptional activity of STAT3 is directly regulated by the redox function of APE1/Ref-1, and that concurrent blockade of STAT3 and APE1/Ref-1 redox synergize effectively inhibit critical PDAC cell functions.

  5. The dual role of complement in the progression of renal disease in NZB/W F(1) mice and alternative pathway inhibition.

    Science.gov (United States)

    Sekine, Hideharu; Ruiz, Phillip; Gilkeson, Gary S; Tomlinson, Stephen

    2011-10-01

    Complement plays a dual role in the progression of systemic lupus erythematosus since it has important protective functions, such as the clearance of immune complexes and apoptotic cells, but is also a mediator of renal inflammation. To investigate this balance in a clinically relevant setting, we investigated how targeted inhibition of all complement pathways vs. targeted inhibition of only the alternative pathway impacts immune and therapeutic outcomes in NZB/W F(1) mice. Following onset of proteinuria, mice were injected twice weekly with CR2-fH (inhibits alternative pathway), CR2-Crry (inhibits all pathways at C3 activation step), sCR2 (C3d targeting vehicle) or saline. Sera were analyzed every 2 weeks for anti-dsDNA antibody levels, and urinary albumin excretion was determined. Kidneys were collected for histological evaluation at 32 weeks. Compared to the control group, all CR2-fH, CR2-Crry and sCR2 treated groups showed significantly reduced serum anti-dsDNA antibody levels and strong trends towards reduced glomerular IgG deposition levels. Glomerular C3 deposition levels were also significantly reduced in all three-treated groups. However, significant reductions of disease activity (albuminuria and glomerulonephritis) were only seen in the CR2-fH treated group. These data highlight the dual role played by complement in the pathogenesis of lupus, and demonstrate a benefit of selectively inhibiting the alternative complement pathway, presumably because of protective contributions from the classical and/or lectin pathways. The sCR2 targeting moiety appears to be contributing to therapeutic outcome via modulation of autoimmunity. Furthermore, these results are largely consistent with our previous data using the MRL/lpr lupus model, thus broadening the significance of these findings.

  6. Platelet matching for alloimmunized patients

    Institute of Scientific and Technical Information of China (English)

    S H.Hsu

    2010-01-01

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

  7. Dual neural endopeptidase/endothelin-converting [corrected] enzyme inhibition improves endothelial function in mesenteric resistance arteries of young spontaneously hypertensive rats

    DEFF Research Database (Denmark)

    Lemkens, Pieter; Nelissen, Jelly; Meens, Merlijn J P M T;

    2012-01-01

    through cleavage of big ET1 by endothelin-converting enzyme (ECE) and neutral endopeptidase (NEP). METHOD: We investigated whether the dual NEP/ECE inhibitor SOL1 improves resistance artery function and structure in 12 weeks old spontaneously hypertensive rats (SHRs) and whether arterial structural...... responses to decreased (-90%) or increased (+100%) blood flow are impaired in young SHRs. To this end two groups of SHRs received chronic 4-week treatment at two different time points (4-8 and 8-12 weeks) prior to the experiment. We compared in-vitro effects of cyclo-oxygenase inhibition (1 μmol...

  8. Lipoteichoic acid from Lactobacillus plantarum inhibits the expression of platelet-activating factor receptor induced by Staphylococcus aureus lipoteichoic acid or Escherichia coli lipopolysaccharide in human monocyte-like cells.

    Science.gov (United States)

    Kim, Hangeun; Jung, Bong Jun; Jeong, Jihye; Chun, Honam; Chung, Dae Kyun

    2014-08-01

    Platelet-activating factor receptor (PAFR) plays an important role in bacterial infection and inflammation. We examined the effect of the bacterial cell wall components lipopolysaccharide (LPS) and lipoteichoic acid (LTA) from Lactobacillus plantarum (pLTA) and Staphylococcus aureus (aLTA) on PAFR expression in THP-1, a monocyte-like cell line. LPS and aLTA, but not pLTA, significantly increased PAFR expression, whereas priming with pLTA inhibited LPSmediated or aLTA-mediated PAFR expression. Expression of Toll-like receptor (TLR) 2 and 4, and CD14 increased with LPS and aLTA treatments, but was inhibited by pLTA pretreatment. Neutralizing antibodies against TLR2, TLR4, and CD14 showed that these receptors were important in LPS-mediated or aLTA-mediated PAFR expression. PAFR expression is mainly regulated by the nuclear factor kappa B signaling pathway. Blocking PAF binding to PAFR using a PAFR inhibitor indicated that LPS-mediated or aLTA-mediated PAF expression affected TNF-α production. In the mouse small intestine, pLTA inhibited PAFR, TLR2, and TLR4 expression that was induced by heat-labile toxin. Our data suggested that pLTA has an anti-inflammatory effect by inhibiting the expression of PAFR that was induced by pathogenic ligands.

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

    Directory of Open Access Journals (Sweden)

    Mayadah B. Shehadeh

    2007-01-01

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

  10. Enhanced in vivo antitumor efficacy of dual-functional peptide-modified docetaxel nanoparticles through tumor targeting and Hsp90 inhibition.

    Science.gov (United States)

    Jiang, Yao; Yang, Nan; Zhang, Huifeng; Sun, Bo; Hou, Chunying; Ji, Chao; Zheng, Ji; Liu, Yanyong; Zuo, Pingping

    2016-01-10

    Although conventional anticancer drugs exhibit excellent efficacy, serious adverse effects and/or even toxicity have occurred due to their nonselectivity. Moreover, active targeting approaches have not consistently led to successful outcomes. Ligands that simultaneously possess targeting capability and exert a strong influence on intracellular signaling cascades may be expected to improve the therapeutic efficacy of active targeting nanoparticulate carriers. In this study, we screened a targeting peptide, LPLTPLP, which specifically bound to non-small cell lung cancer (NSCLC) specimens in vitro. Surprisingly, this peptide inhibited the expression of Hsp90 and induced apoptosis by preventing autophagy in A549 cells treated with docetaxel. The results suggested that this peptide might be used as a promising dual-functional ligand for cancer treatment. Based on these findings, we designed and developed a novel active targeting delivery system by modifying docetaxel nanoparticles (DNP) with the dual-functional ligand LPLTPLP. We consistently demonstrated that the cellular uptake of nanoparticles (NPs) was significantly enhanced in vitro. Furthermore, the targeting NPs exhibited significantly improved antitumor efficacy and biodistribution compared with nontargeting nanodrug and free docetaxel. These findings demonstrate the feasibility of dual-functional NPs for efficient anticancer therapy.

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

    Science.gov (United States)

    Feghhi, Shirin; Tooley, Wes W; Sniadecki, Nathan J

    2016-10-01

    Platelet contractile forces play a major role in clot retraction and help to hold hemostatic clots against the vessel wall. Platelet forces are produced by its cytoskeleton, which is composed of actin and nonmuscle myosin filaments. In this work, we studied the role of Rho kinase, myosin light-chain kinase, and myosin in the generation of contractile forces by using pharmacological inhibitors and arrays of flexible microposts to measure platelet forces. When platelets were seeded onto microposts, they formed aggregates on the tips of the microposts. Forces produced by the platelets in the aggregates were measured by quantifying the deflection of the microposts, which bent in proportion to the force of the platelets. Platelets were treated with small molecule inhibitors of myosin activity: Y-27632 to inhibit the Rho kinase (ROCK), ML-7 to inhibit myosin light-chain kinase (MLCK), and blebbistatin to inhibit myosin ATPase activity. ROCK inhibition reduced platelet forces, demonstrating the importance of the assembly of actin and myosin phosphorylation in generating contractile forces. Similarly, MLCK inhibition caused weaker platelet forces, which verifies that myosin phosphorylation is needed for force generation in platelets. Platelets treated with blebbistatin also had weaker forces, which indicates that myosin's ATPase activity is necessary for platelet forces. Our studies demonstrate that myosin ATPase activity and the regulation of actin-myosin assembly by ROCK and MLCK are needed for the generation of platelet forces. Our findings illustrate and explain the importance of myosin for clot compaction in hemostasis and thrombosis.

  12. The use of platelet reactivity testing in patients on antiplatelet therapy for prediction of bleeding events after cardiac surgery.

    Science.gov (United States)

    Leunissen, Tesse C; Janssen, Paul W A; Ten Berg, Jurriën M; Moll, Frans L; Korporaal, Suzanne J A; de Borst, Gert Jan; Pasterkamp, Gerard; Urbanus, Rolf T

    2016-02-01

    Many patients are treated with platelet inhibitors such as aspirin and clopidogrel for prevention of thrombotic cardiovascular events. However, the inhibitory effect of antiplatelet therapy is variable between patients; in some, the platelets are hardly inhibited, while in others, the platelets are excessively inhibited. The newer and more potent platelet inhibitors, prasugrel and ticagrelor, often lead to low platelet reactivity, which potentially leads to bleeding events. Preoperative measurement of platelet reactivity in patients receiving platelet inhibitors who undergo cardiac surgery, could be useful to identify those with low platelet reactivity and thus have an increased risk of bleeding during or after surgery. In this review, we discuss the most commonly used platelet inhibitors and platelet function tests. Furthermore, we will provide an overview of the evidence for the prediction of post-operative bleeding at the operation site with preoperative platelet reactivity testing in patients undergoing cardiac surgery. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. 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

    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......-half the patients allocated AZD6140 received a 270-mg loading dose. Patients randomized to receive clopidogrel were given a 300-mg loading dose unless they had already been treated with clopidogrel. Adenosine diphosphate-induced platelet aggregation was assessed by optical aggregometry on day 1 and at 4-week...

  14. 'Dual hit' metabolic modulator LDCA selectively kills cancer cells by efficient competitive inhibition of LDH-A.

    Science.gov (United States)

    Ghosh, Monisankar; Saha, Suchandrima; Dutta, Samir Kumar

    2016-02-07

    Herein, we synthesize and elucidate the potential of a novel 'dual hit' molecule, LDCA, to constitutively block lactate dehydrogenase isoform-A (LDH-A) to selectively subvert apoptosis and rigorously attenuate breast tumor progression in a mouse model, comprehensively delineating the therapeutic prospectus of LDCA in the field of cancer metabolics.

  15. A novel PPAR alpha/gamma dual agonist inhibits cell growth and induces apoptosis in human glioblastoma T98G cells

    Institute of Scientific and Technical Information of China (English)

    Da-chuan LIU; Chuan-bing ZANG; Hong-yu LIU; Kurt POSSINGER; Shao-guang FAN; Elena ELSTNER

    2004-01-01

    AIM: To examine the effect of a novel peroxisome proliferator-activated receptor (PPAR) α/γ dual agonist TZD 18 on cell proliferation and apoptosis in human glioblastoma T98G cells and its possible mechanism. METHODS: RTPCR, MTT, TUNEL, Flow cytometry, and Western blot analysis were employed. RESULTS: TZD18 inhibited the growth of T98G cells in a concentration-dependent manner, which was associated with a G1 to S cell cycle arrest.Besides, significant apoptosis was induced after treatment with a non-toxic dose of TZD 18. During the process,the expression of Bcl-2 protein was down-regulated, while that of Bax and p27kip proteins was up-regulated, and the activity of caspase-3 was elevated. However, this effect appeared to be PPARα and PPARγ independent since their antagonists could not reverse this effect. CONCLUSIONS: TZD18, a novel PPARα/γ dual agonist, inhibited cell growth and induce apoptosis in human glioblastoma T98G cells in vitro, indicating a therapeutic potential for TZD 18 in the treatment of glioblastoma.

  16. Surface tailoring for selective endothelialization and platelet inhibition via a combination of SI-ATRP and click chemistry using Cys-Ala-Gly-peptide.

    Science.gov (United States)

    Khan, Musammir; Yang, Jing; Shi, Changcan; Lv, Juan; Feng, Yakai; Zhang, Wencheng

    2015-07-01

    Surface tailoring is an attractive approach to enhancing selective endothelialization, which is a prerequisite for current vascular prosthesis applications. Here, we modified polycarbonate urethane (PCU) surface with both poly(ethylene glycol) and Cys-Ala-Gly-peptide (CAG) for the purpose of creating a hydrophilic surface with targeting adhesion of endothelial cells (ECs). In the first step, PCU-film surface was grafted with poly(ethylene glycol) methacrylate (PEGMA) to covalently tether hydrophilic polymer brushes via surface initiated atom transfer radical polymerization (SI-ATRP), followed by grafting of an active monomer pentafluorophenyl methacrylate (PFMA) by a second ATRP. The postpolymerization modification of the terminal reactive groups with allyl amine molecules created pendant allyl groups, which were subsequently functionalized with cysteine terminated CAG-peptide via photo-initiated thiol-ene click chemistry. The functionalized surfaces were characterized by water contact angle and XPS analysis. The growth and proliferation of human ECs or human umbilical arterial smooth muscle cells on the functionalized surfaces were investigated for 1, 3 and 7 day/s. The results indicated that these peptide functionalized surfaces exhibited enhanced EC adhesion, growth and proliferation. Furthermore, they suppressed platelet adhesion in contact with platelet-rich plasma for 2h. Therefore, these surfaces with EC targeting ligand could be an effective anti-thrombogenic platform for vascular tissue engineering application.

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

    Directory of Open Access Journals (Sweden)

    Damin Huang

    2012-06-01

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

  18. Inhibition of HPA-1a alloantibody-mediated platelet destruction by a deglycosylated anti-HPA-1a monoclonal antibody in mice: toward targeted treatment of fetal-alloimmune thrombocytopenia.

    Science.gov (United States)

    Bakchoul, Tamam; Greinacher, Andreas; Sachs, Ulrich J; Krautwurst, Annika; Renz, Harald; Harb, Habi; Bein, Gregor; Newman, Peter J; Santoso, Sentot

    2013-07-18

    Fetal/neonatal alloimmune thrombocytopenia (FNAIT) is often caused by maternal alloantibodies against the human platelet antigen (HPA)-1a, which opsonizes fetal platelets (PLTs). Subsequent PLT destruction is mediated via the Fc part of the alloantibodies. The monoclonal antibody (mAb) SZ21 binds to the HPA-1a epitope and inhibits the binding of maternal alloantibodies. However, it also promotes complement activation and phagocytosis. Deglycosylation of antibodies abrogates the Fc-related effector functions. We modified the N-glycan of SZ21 by endoglycosidase F. The in vivo transplacental transport of N-glycan-modified (NGM)-SZ21 was not impaired. When injected into pregnant mice, both native-SZ21 and NGM-SZ21 were transported equally into fetal circulation (8.9% vs 8.7%, respectively, P = .58). Neither the binding properties of NGM-SZ21 to HPA-1a in surface plasmon resonance, nor the inhibition of anti-HPA-1a-induced PLT phagocytosis, were affected by N-glycan modification. NGM-SZ21 prevented PLT destruction induced by maternal anti-HPA-1a antibodies in vivo in a mouse model (PLT clearance after 5 hours; 18% vs 62%, in the presence or absence of NGM-SZ21, respectively, P = .013). Deglycosylation of SZ21 abrogates Fc-effector functions without interfering with placental transport or the ability to block anti-HPA-1a binding. Humanized, deglycosylated anti-HPA-1a mAbs may represent a novel treatment strategy to prevent anti-HPA-1a-mediated PLT destruction in FNAIT.

  19. Enhanced Inhibition of Prostate Tumor Growth by Dual Targeting the Androgen Receptor and the Regulatory Subunit Type Iα of Protein Kinase A in Vivo

    Science.gov (United States)

    Eder, Iris E.; Egger, Martina; Neuwirt, Hannes; Seifarth, Christof; Maddalo, Danilo; Desiniotis, Andreas; Schäfer, Georg; Puhr, Martin; Bektic, Jasmin; Cato, Andrew C. B.; Klocker, Helmut

    2013-01-01

    Progression to castration resistance is a major problem in the treatment of advanced prostate cancer and is likely to be driven by activation of several molecular pathways, including androgen receptor (AR) and cyclic AMP-dependent protein kinase A (PKA). In this study, we examined the therapeutic efficacy of a combined inhibition of the AR and the regulatory subunit type Iα (RIα) of protein kinase A with second generation antisense oligonucleotides (ODNs) in androgen-sensitive LNCaP and castration-resistant LNCaPabl tumors in vivo. We found that targeting the AR alone inhibited LNCaP, as well as LNCaPabl tumors. Combined inhibition resulted in an improved response over single targeting and even a complete tumor remission in LNCaPabl. Western blot analysis revealed that both ODNs were effective in reducing their target proteins when administered alone or in combination. In addition, treatment with the ODNs was associated with an induction of apoptosis. Our data suggest that dual targeting of the AR and PKARIα is more effective in inhibiting LNCaP and LNCaPabl tumor growth than single treatment and may give a treatment benefit, especially in castration-resistant prostate cancers. PMID:23736698

  20. 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.

  1. Transcellular lipoxygenase metabolism between monocytes and platelets

    Energy Technology Data Exchange (ETDEWEB)

    Bigby, T.D.; Meslier, N. (Univ. of California, San Francisco (USA))

    1989-09-15

    We have examined the effects of co-culture and in vitro co-stimulation on lipoxygenase metabolism in monocytes and platelets. Monocytes were obtained from the peripheral blood of normal volunteers by discontinuous gradient centrifugation and adherence to tissue culture plastic. Platelets were obtained from the platelet-rich plasma of the same donor. When 10(9) platelets and 2.5 x 10(6) monocytes were co-stimulated with 1 microM A23187, these preparations released greater quantities of 12(S)-hydroxy-10-trans-5,8,14-cis-eicosatetraenoic acid, 5(S),12-(S)dihydroxy-6,10-trans-8,14-cis-eicosatetraenoic acid, and leukotriene C4, 5(S)-hydroxy-6(R)-S-glutathionyl-7,9-trans-11,14-cis-eicosatetraenoic (LTC4) when compared with monocytes alone. Release of arachidonic acid, 5-HETE, delta 6-trans-LTB4, and delta 6-trans-12-epi-LTB4 from monocytes was decreased in the presence of platelets. A dose-response curve was constructed and revealed that the above changes became evident when the platelet number exceeded 10(7). Dual radiolabeling experiments with 3H- and 14C-arachidonic acid revealed that monocytes provided arachidonic acid, 5-HETE, and LTA4 for further metabolism by the platelet. Monocytes did not metabolize platelet intermediates detectably. In addition, as much as 1.2 microM 12(S)-hydroxy-10-trans-5,8,14-cis-eicosatetraenoic acid and 12(S)-hydroperoxy-10-trans-5,8,14-cis-eicosatetraenoic acid had no effect on monocyte lipoxygenase metabolism. Platelets were capable of converting LTA4 to LTC4, but conversion of LTA4 to LTB4 was not detected. We conclude that the monocyte and platelet lipoxygenase pathways undergo a transcellular lipoxygenase interaction that differs from the interaction of the neutrophil and platelet lipoxygenase pathways. In this interaction monocytes provide intermediate substrates for further metabolic conversion by platelets in an unidirectional manner.

  2. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical Univ. Lubeck, Lubeck (DE))

    1990-01-01

    This book presents papers on the clinical applications of radiolabelled platelets. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection.

  3. LRD-22, a novel dual dithiocarbamatic acid ester, inhibits Aurora-A kinase and induces apoptosis and cell cycle arrest in HepG2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiling; Li, Ridong [State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing (China); Li, Li [Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing (China); Ge, Zemei [State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing (China); Zhou, Rouli, E-mail: rlzhou@bjmu.edu.cn [Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing (China); Li, Runtao, E-mail: lirt@bjmu.edu.cn [State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing (China)

    2015-02-27

    In this study we investigated the antitumor activity of the novel dual dithiocarbamatic acid ester LRD-22 in vitro and in vivo. Several cancer cell lines were employed to determine the effect of LRD-22 on cell growth, and the MTT assay showed there was a significant decrease in viable tumor cell numbers in the presence of LRD-22, especially in the HepG2 cell line. Colony formation assay also showed LRD-22 strongly inhibits HepG2 cell growth. Evaluation of the mechanism involved showed that inhibitory effects of LRD-22 on cell growth are due to induction of apoptosis and G2/M arrest. LRD-22 inhibited Aurora-A phosphorylation at Thr{sub 288} and subsequently impaired p53 phosphorylation at Ser{sub 315} which was associated with the proteasome degradation pathway. Tumor suppressor protein p53 is stabilized by this mechanism and accumulates through inhibition of Aurora-A kinase activity via treatment with LRD-22. In vivo study of HepG2 xenograft in nude mice also shows LRD-22 suppresses tumor growth at a concentration of 5 mg/kg without animals suffering loss of body weight. In conclusion, our results demonstrate LRD-22 acts as an Aurora-A kinase inhibitor to induce apoptosis and inhibit proliferation in HepG2 cells, and should be considered as a promising targeting agent for HCC therapy. - Highlights: • LRD-22 significantly inhibits cancer cell growth, especially in the HepG2 cell line. • The inhibitory effect of LRD-22 is due to induction of apoptosis and cell cycle arrest. • LRD-22 inhibits Aurora-A phosphorylation which results in subsequent impairment of the p53 pathway. • LRD-22 suppresses tumor growth in xenograft mice without body weight loss.

  4. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

  6. Platelets and erythrocyte-bound platelets bind infectious HIV-1 in plasma of chronically infected patients.

    Science.gov (United States)

    Beck, Zoltan; Jagodzinski, Linda L; Eller, Michael A; Thelian, Doris; Matyas, Gary R; Kunz, Anjali N; Alving, Carl R

    2013-01-01

    Chronic HIV-1 infection is associated with persistent viremia in most patients, but it remains unclear how free virus may survive the potential hostile effects of plasma. We investigated whether sites might exist on the surfaces of circulating blood cells for protection of infectious HIV-1 particles. Red blood cells (RBC) either from blood of uninfected normal individuals, or from blood obtained without EDTA from chronically infected HIV-1 patients, invariably contained a small number of RBC having attached platelets as determined by flow cytometry, light microscopy, and immunofluorescence microscopy. After mixing normal RBC with platelet-rich plasma, discrete populations of RBC, platelets, and complexes of platelets attached to RBC were purified by fluorescence-activated cell sorting. Upon incubation of purified cells or platelets with HIV-1 followed by washing and co-incubation with CD4-positive peripheral blood mononuclear cells (PBMC), platelets, and platelet-RBC complexes, but not platelet-free RBC, caused infection of PBMC. Infection was prevented by pre-treating the platelet-RBC complexes with EDTA. Plasma and RBC (comprising a RBC/platelet-RBC mixture) from chronically infected patients with low viral loads were also co-incubated with PBMC ex vivo to determine the presence of infectious HIV-1. All freshly isolated plasmas from the HIV-1-infected donors, obtained in the absence of anticoagulant, were noninfectious. Interestingly, the RBC from most of the patients caused cell-cell infection of PBMC that was prevented by stripping the RBC with EDTA. A monoclonal antibody to DC-SIGN partially inhibited cell-cell HIV-1 infection of PBMC by normal RBC pre-incubated with platelets and HIV-1. We conclude: (a) platelet-free EDTA-free plasma from chronically infected HIV-1 patients, although containing viral RNA, is an environment that lacks detectable infectious HIV-1; (b) platelets and platelet-RBC complexes, but not purified RBC, bind infectious HIV-1; (c) DC

  7. Platelets and erythrocyte-bound platelets bind infectious HIV-1 in plasma of chronically infected patients.

    Directory of Open Access Journals (Sweden)

    Zoltan Beck

    Full Text Available Chronic HIV-1 infection is associated with persistent viremia in most patients, but it remains unclear how free virus may survive the potential hostile effects of plasma. We investigated whether sites might exist on the surfaces of circulating blood cells for protection of infectious HIV-1 particles. Red blood cells (RBC either from blood of uninfected normal individuals, or from blood obtained without EDTA from chronically infected HIV-1 patients, invariably contained a small number of RBC having attached platelets as determined by flow cytometry, light microscopy, and immunofluorescence microscopy. After mixing normal RBC with platelet-rich plasma, discrete populations of RBC, platelets, and complexes of platelets attached to RBC were purified by fluorescence-activated cell sorting. Upon incubation of purified cells or platelets with HIV-1 followed by washing and co-incubation with CD4-positive peripheral blood mononuclear cells (PBMC, platelets, and platelet-RBC complexes, but not platelet-free RBC, caused infection of PBMC. Infection was prevented by pre-treating the platelet-RBC complexes with EDTA. Plasma and RBC (comprising a RBC/platelet-RBC mixture from chronically infected patients with low viral loads were also co-incubated with PBMC ex vivo to determine the presence of infectious HIV-1. All freshly isolated plasmas from the HIV-1-infected donors, obtained in the absence of anticoagulant, were noninfectious. Interestingly, the RBC from most of the patients caused cell-cell infection of PBMC that was prevented by stripping the RBC with EDTA. A monoclonal antibody to DC-SIGN partially inhibited cell-cell HIV-1 infection of PBMC by normal RBC pre-incubated with platelets and HIV-1. We conclude: (a platelet-free EDTA-free plasma from chronically infected HIV-1 patients, although containing viral RNA, is an environment that lacks detectable infectious HIV-1; (b platelets and platelet-RBC complexes, but not purified RBC, bind infectious HIV

  8. 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....

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

    Directory of Open Access Journals (Sweden)

    Huan-Yao Lei

    2008-01-01

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

  10. Propranolol modifies platelet serotonergic mechanisms in rats.

    Science.gov (United States)

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

    2002-06-01

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

  11. Inhibition of osteosarcoma-induced thermal hyperalgesia in mice by the orally active dual enkephalinase inhibitor PL37. Potentiation by gabapentin.

    Science.gov (United States)

    Menéndez, Luis; Hidalgo, Agustín; Meana, Alvaro; Poras, Hervé; Fournié-Zaluski, Marie-Claude; Roques, Bernard P; Baamonde, Ana

    2008-10-31

    We have previously shown that stimulation of peripheral opioid receptors by exogenous opiates counteracts the thermal hyperalgesia elicited by a tibial osteosarcoma due to intraosteal inoculation of NCTC 2472 cells to mice. Aiming to study whether pheripheral endogenous enkephalins could also counteract this painful symptom, we assayed in this model the effects of PL37, an orally active dual inhibitor of enkephalin inactivating enzymes. Oral administration of PL37 (25 mg/kg) completely supressed osteosarcoma-induced thermal hyperalgesia through the activation of micro-opioid receptors, since the administration of cyprodime (1 mg/kg) inhibited its antihyperalgesic effect. Neither naltrindole (0.1 mg/kg) nor nor-binaltorphimine (10 mg/kg) modified this PL37-induced antihyperalgesic effect. Moreover, the inhibition of the antihyperalgesic effect induced by PL37 after the administration of naloxone-methiodide (2 mg/kg), a non selective opioid antagonist that does not cross the blood-brain barrier, demonstrates the involvement of peripheral opioid receptors. In contrast, centrally mediated effects may be detected when assaying a higher dose of PL37 (50 mg/kg). Besides, the administration of gabapentin (6.25-25 mg/kg, i.p.) dose-dependently inhibited osteosarcoma-induced thermal hyperalgesia. Interestingly, the combined administration of subeffective doses of PL37 and gabapentin completely prevented this type of thermal hyperalgesia. An isobolographic analysis of this interaction demonstrated a synergistic interaction between both drugs.

  12. Dual inhibition of ATR and ATM potentiates the activity of trabectedin and lurbinectedin by perturbing the DNA damage response and homologous recombination repair.

    Science.gov (United States)

    Lima, Michelle; Bouzid, Hana; Soares, Daniele G; Selle, Frédéric; Morel, Claire; Galmarini, Carlos M; Henriques, João A P; Larsen, Annette K; Escargueil, Alexandre E

    2016-05-03

    Trabectedin (Yondelis®, ecteinascidin-743, ET-743) is a marine-derived natural product approved for treatment of advanced soft tissue sarcoma and relapsed platinum-sensitive ovarian cancer. Lurbinectedin is a novel anticancer agent structurally related to trabectedin. Both ecteinascidins generate DNA double-strand breaks that are processed through homologous recombination repair (HRR), thereby rendering HRR-deficient cells particularly sensitive. We here characterize the DNA damage response (DDR) to trabectedin and lurbinectedin in HeLa cells. Our results show that both compounds activate the ATM/Chk2 (ataxia-telangiectasia mutated/checkpoint kinase 2) and ATR/Chk1 (ATM and RAD3-related/checkpoint kinase 1) pathways. Interestingly, pharmacological inhibition of Chk1/2, ATR or ATM is not accompanied by any significant improvement of the cytotoxic activity of the ecteinascidins while dual inhibition of ATM and ATR strongly potentiates it. Accordingly, concomitant inhibition of both ATR and ATM is an absolute requirement to efficiently block the formation of γ-H2AX, MDC1, BRCA1 and Rad51 foci following exposure to the ecteinascidins. These results are not restricted to HeLa cells, but are shared by cisplatin-sensitive and -resistant ovarian carcinoma cells. Together, our data identify ATR and ATM as central coordinators of the DDR to ecteinascidins and provide a mechanistic rationale for combining these compounds with ATR and ATM inhibitors.

  13. The novel PPAR α/γ dual agonist MHY 966 modulates UVB-induced skin inflammation by inhibiting NF-κB activity.

    Directory of Open Access Journals (Sweden)

    Min Hi Park

    Full Text Available Ultraviolet B (UVB; 290~320nm irradiation-induced lipid peroxidation induces inflammatory responses that lead to skin wrinkle formation and epidermal thickening. Peroxisome proliferator-activated receptor (PPAR α/γ dual agonists have the potential to be used as anti-wrinkle agents because they inhibit inflammatory response and lipid peroxidation. In this study, we evaluated the function of 2-bromo-4-(5-chloro-benzo[d]thiazol-2-yl phenol (MHY 966, a novel synthetic PPAR α/γ dual agonist, and investigated its anti-inflammatory and anti-lipid peroxidation effects. The action of MHY 966 as a PPAR α/γ dual agonist was also determined in vitro by reporter gene assay. Additionally, 8-week-old melanin-possessing hairless mice 2 (HRM2 were exposed to 150 mJ/cm(2 UVB every other day for 17 days and MHY 966 was simultaneously pre-treated every day for 17 days to investigate the molecular mechanisms involved. MHY 966 was found to stimulate the transcriptional activities of both PPAR α and γ. In HRM2 mice, we found that the skins of mice exposed to UVB showed significantly increased pro-inflammatory mediator levels (NF-κB, iNOS, and COX-2 and increased lipid peroxidation, whereas MHY 966 co-treatment down-regulated these effects of UVB by activating PPAR α and γ. Thus, the present study shows that MHY 966 exhibits beneficial effects on inflammatory responses and lipid peroxidation by simultaneously activating PPAR α and γ. The major finding of this study is that MHY 966 demonstrates potential as an agent against wrinkle formation associated with chronic UVB exposure.

  14. Detection of platelet deposition in cases of arteriosclerosis obliterans (ASO) using indium-111 platelets and Tc-99m human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Kitagawa, Kazuo; Miyai, Motonobu; Etani, Hideki

    1987-02-01

    We evaluated platelet deposition in vivo in 10 patients with arteriosclerosis obliterans (ASO) of the lower limbs and 8 normal subjects with a dual-tracer technique using indium-111 platelets and Tc-99m human serum albumin. Each patient with ASO showed intermittent claudication and angiographically occlusive vascular lesions in either the aorta, common iliac artery, external iliac artery, internal iliac artery or femoral artery. Of the 8 patients who were not under antiplatelet medication, 5 showed positive platelet deposition at angiographically occlusive vascular sites, whereas none of the normal subjects showed in vivo platelet deposition. In three patients who showed platelet deposition without antiplatelet medication and thereafter received aspirin therapy (650 mg/day), platelet deposition at all occlusive vascular sites was resolved after aspirin therapy. This preliminary study indicated that platelet scintigraphy might be useful in evaluating thrombogenicity and the effect of antiplatelet medication in vivo, in patients with ASO.

  15. 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.

  16. Dual apoptotic DNA fragmentation system in the fly: Drep2 is a novel nuclease of which activity is inhibited by Drep3.

    Science.gov (United States)

    Park, Ok Kyeung; Park, Hyun Ho

    2012-09-21

    DNA fragmentation is the hallmark of apoptotic cells and mainly mediated by the DNA fragmentation factor DFF40(CAD)/DFF45(ICAD). DFF40 is a novel nuclease, whereas DFF45 is an inhibitor that can suppress the nuclease activity. Apoptotic DNA fragmentation in the fly is controlled by four DFF-related proteins, known as Drep1, 2, 3 and 4. However, the functions of Drep2 and Drep3 are totally unknown. Here, we found that Drep2 is a novel nuclease whose activity is inhibited by Drep3 through a tight interaction with the CIDE domain. Our results suggest that the fly has dual apoptotic DNA fragmentation systems: Drep1: Drep4 and Drep2: Drep3 complexes.

  17. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev

    2014-09-01

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

  18. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study: Variation in Platelet Response to Clopidogrel and Aspirin.

    Science.gov (United States)

    Bozzi, Laura M; Mitchell, Braxton D; Lewis, Joshua P; Ryan, Kathy A; Herzog, William R; O'Connell, Jeffrey R; Horenstein, Richard B; Shuldiner, Alan R; Yerges-Armstrong, Laura M

    2016-01-01

    Clopidogrel and aspirin are commonly prescribed anti-platelet medications indicated for patients who have experienced, or are at risk for, ischemic cardiovascular events. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study was designed to characterize determinants of clopidogrel and dual anti-platelet therapy (DAPT) response in a healthy cohort of Old Order Amish from Lancaster, PA. Following a loading dose, clopidogrel was taken once a day for 7 days. One hour after the last dose of clopidogrel, 325 mg of aspirin was given. Ex vivo platelet aggregometry was performed at baseline, post-clopidogrel, and post-DAPT. Platelet aggregation measurements were significantly lower after both interventions for all agonists tested (p pharmacogenomics studies.

  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.

  20. Inhibition of Notch Signaling Ameliorates Acute Kidney Failure and Downregulates Platelet-Derived Growth Factor Receptor β in the Mouse Model.

    Science.gov (United States)

    Kramer, Jan; Schwanbeck, Ralf; Pagel, Horst; Cakiroglu, Figen; Rohwedel, Jürgen; Just, Ursula

    2016-01-01

    Ischemic acute kidney injury (AKI) is associated with high morbidity and frequent complications. Repeated episodes of AKI may lead to end-stage renal failure. The pathobiology of regeneration in AKI is not well understood and there is no effective clinical therapy that improves regeneration. The Notch signaling pathway plays an essential role in kidney development and has been implicated in tissue repair in the adult kidney. Here, we found that kidneys after experimental AKI in mice showed increased expression of Notch receptors, specifically Notch1-3, of the Notch ligands Jagged-1 (Jag1), Jag2 and Delta-like-4 (Dll4) and of the Notch target genes Hes1, Hey2, HeyL, Sox9 and platelet-derived growth factor receptor β (Pdgfrb). Treatment of ischemic mice with the x03B3;-secretase inhibitor DBZ blocked Notch signaling and specifically downregulated the expression of Notch3 and the Notch target genes Hes1, Hey2, HeyL and Pdgfrb. After DBZ treatment, the mice developed less interstitial edema and displayed altered interstitial inflammation patterns. Furthermore, serum urea and creatinine levels were significantly decreased from 6 h onwards when compared to control mice treated with DMSO only. Our data are consistent with an amelioration of the severity of kidney injury by blocking Notch activation following AKI, and suggest an involvement of Notch-regulated Pdgfrb in AKI pathogenesis.

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

    Science.gov (United States)

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

    2014-02-01

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

  2. Dual PI3K/mTOR inhibition shows antileukemic activity in MLL-rearranged acute myeloid leukemia.

    Science.gov (United States)

    Sandhöfer, N; Metzeler, K H; Rothenberg, M; Herold, T; Tiedt, S; Groiß, V; Carlet, M; Walter, G; Hinrichsen, T; Wachter, O; Grunert, M; Schneider, S; Subklewe, M; Dufour, A; Fröhling, S; Klein, H-G; Hiddemann, W; Jeremias, I; Spiekermann, K

    2015-04-01

    In acute myeloid leukemia (AML), several signaling pathways such as the phosphatidylinositol-3-kinase/AKT and the mammalian target of rapamycin (PI3K/AKT/mTOR) pathway are deregulated and constitutively activated as a consequence of genetic and cytogenetic abnormalities. We tested the effectiveness of PI3K/AKT/mTOR-targeting therapies and tried to identify alterations that associate with treatment sensitivity. By analyzing primary samples and cell lines, we observed a wide range of cytotoxic activity for inhibition of AKT (MK-2206), mTORC1 (rapamycin) and PI3K/mTORC1/2 (BEZ-235) with a high sensitivity of cells carrying an MLL rearrangement. In vivo PI3K/mTOR inhibition delayed tumor progression, reduced tumor load and prolonged survival in an MLL-AF9(+)/FLT3-ITD(+) xenograft mouse model. By performing targeted amplicon sequencing in 38 MLL-AF9(+) and 125 cytogenetically normal AML patient samples, we found a high additional mutation rate for genes involved in growth factor signaling in 79% of all MLL-AF9(+) samples, which could lead to a possible benefit of this cohort. PI3K/mTOR inhibition for 24 h led to the cross-activation of the ERK pathway. Further in vitro studies combining PI3K/mTOR and ERK pathway inhibition revealed highly synergistic effects in apoptosis assays. Our data implicate a possible therapeutic benefit of PI3K/mTOR inhibition in the MLL-mutated subgroup. Inhibiting rescue pathways could improve the therapeutic efficacy of PI3K-targeted therapies in AML.

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

    Science.gov (United States)

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

    1999-08-01

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

  4. Dual PI3K/mTOR Inhibition in Colorectal Cancers with APC and PIK3CA Mutations.

    Science.gov (United States)

    Foley, Tyler M; Payne, Susan N; Pasch, Cheri A; Yueh, Alex E; Van De Hey, Dana R; Korkos, Demetra P; Clipson, Linda; Maher, Molly E; Matkowskyj, Kristina A; Newton, Michael A; Deming, Dustin A

    2017-02-09

    Therapeutic targeting of the PI3K pathway is an active area of research in multiple cancer types, including breast and endometrial cancers. This pathway is commonly altered in cancer and plays an integral role in numerous vital cellular functions. Mutations in the PIK3CA gene, resulting in a constitutively active form of PI3K, often occur in colorectal cancer, though the population of patients who would benefit from targeting this pathway has yet to be identified. In human colorectal cancers, PIK3CA mutations most commonly occur concomitantly with loss of adenomatous polyposis coli (APC). Here, treatment strategies are investigated that target the PI3K pathway in colon cancers with mutations in APC and PIK3CA Colorectal cancer spheroids with Apc and Pik3ca mutations were generated and characterized confirming that these cultures represent the tumors from which they were derived. Pan and alpha isomer-specific PI3K inhibitors did not induce a significant treatment response, whereas the dual PI3K/mTOR inhibitors BEZ235 and LY3023414 induced a dramatic treatment response through decreased cellular proliferation and increased differentiation. The significant treatment responses were confirmed in mice with Apc and Pik3ca-mutant colon cancers as measured using endoscopy with a reduction in median lumen occlusion of 53% with BEZ235 and a 24% reduction with LY3023414 compared with an increase of 53% in controls (P APC and PIK3CA-mutant colorectal cancers. Thus, further clinical studies of dual PI3K/mTOR inhibitors are warranted in colorectal cancers with these mutations. Mol Cancer Res; 15(3); 1-11. ©2016 AACR.

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

    Science.gov (United States)

    Wang, Wenqing; Lau, Wayne Bond; Wang, Yajing; Ma, Xinliang; Li, Rong

    2016-01-11

    Platelet hyper-reactivity is a crucial cause of accelerated atherosclerosis increasing risk of thrombotic vascular events in diabetic patients. The mechanisms leading to abnormal platelet activity during diabetes are complex and not fully defined. The current study attempted to clarify the role of CTRP9, a novel adiponectin paralog, in enhanced platelet activity and determined whether CTRP9 may inhibit platelet activity. Adult male C57BL/6 J mice were randomized to receive high-fat diet (HFD) or normal diet (ND). 8 weeks after HFD, animals were sacrificed, and both plasma CTRP9 and platelet aggregation were determined. HFD-fed animals increased weight gain significantly, and became hyperglycemic and hyperinsulinemic 8 weeks post-HFD. Compared to ND animals, HFD animals exhibited significantly decreased plasma CTRP9 concentration and increased platelet response to ADP, evidenced by augmented aggregation amplitude, steeper aggregation slope, larger area under the curve, and shorter lag time (P animals. Taken together, our results suggest reduced plasma CTRP9 concentration during diabetes plays a causative role in platelet hyper-activity, contributing to platelet-induced cardiovascular damage during this pathologic condition. Enhancing CTRP9 production and/or exogenous supplementation of CTRP9 may protect against diabetic cardiovascular injury via inhibition of abnormal platelet activity.

  6. p38 mitogen-activated protein kinase activation during platelet storage: consequences for platelet recovery and hemostatic function in vivo.

    Science.gov (United States)

    Canault, Matthias; Duerschmied, Daniel; Brill, Alexander; Stefanini, Lucia; Schatzberg, Daphne; Cifuni, Stephen M; Bergmeier, Wolfgang; Wagner, Denisa D

    2010-03-01

    Platelets undergo several modifications during storage that reduce their posttransfusion survival and functionality. One important feature of these changes, which are known as platelet storage lesion, is the shedding of the surface glycoproteins GPIb-alpha and GPV. We recently demonstrated that tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) mediates mitochondrial injury-induced shedding of adhesion receptors and that TACE activity correlates with reduced posttransfusion survival of these cells. We now confirm that TACE mediates receptor shedding and clearance of platelets stored for 16 hours at 37 degrees C or 22 degrees C. We further demonstrate that both storage and mitochondrial injury lead to the phosphorylation of p38 mitogen-activated kinase (MAPK) in platelets and that TACE-mediated receptor shedding from mouse and human platelets requires p38 MAP kinase signaling. Protein kinase C, extracellular regulated-signal kinase MAPK, and caspases were not involved in TACE activation. Both inhibition of p38 MAPK and inactivation of TACE during platelet storage led to a markedly improved posttransfusion recovery and hemostatic function of platelets in mice. p38 MAPK inhibitors had only minor effects on the aggregation of fresh platelets under static or flow conditions in vitro. In summary, our data suggest that inhibition of p38 MAPK or TACE during storage may significantly improve the quality of stored platelets.

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

    Institute of Scientific and Technical Information of China (English)

    赵凯华; 周雄辉; 刘强; 汪金; 李丽萍; 王科

    2013-01-01

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

  8. Evaluation of platelet thromboxane radioimmunoassay method to measure platelet life-span: Comparison with /sup 111/indium-platelet method

    Energy Technology Data Exchange (ETDEWEB)

    Vallabhajosula, S.; Machac, J.; Badimon, L.; Lipszyc, H.; Goldsmith, S.J.; Fuster, V.

    1985-05-01

    The platelet activation during radiolabeling in vitro with Cr-51 and In-111 may affect the platelet life-span (PLS) in vivo. A new RIA method to measure PLS is being evaluated. Aspirin inhibits platelet thromboxane (TxA/sub 2/) by acetylating cyclooxygenase. The time required for the TxA/sub 2/ levels to return towards control values depends on the rate of new platelets entering circulation and is a measure of PLS. A single dose of aspirin (150mg) was given to 5 normal human subjects. Blood samples were collected for 2 days before aspirin and daily for 10 days. TxA/sub 2/ production in response to endogenous thrombin was studied by allowing 1 ml blood sample to clot at 37/sup 0/C for 90 min. Serum TxB/sub 2/ (stable breakdown product of Tx-A/sub 2/) levels determined by RIA technique. The plot of TxB/sub 2/ levels (% control) against time showed a gradual increase. The PLS calculated by linear regression analysis assuming a 2-day lag period before cyclooxygenase recovery is 9.7 +- 2.37. In the same 5 subjects, platelets from a 50ml blood sample were labeled with /sup 111/In-tropolone in 2 ml autologous plasma. Starting at 1 hr after injection of labeled platelets, 10 blood samples were obtained over a 8 day period. The PLS calculated based on a linear regression analysis is 10.2 +. 1.4. The PLS measured from the rate of platelet disappearance from circulation and the rate of platelet regeneration into circulation are quite comparable in normal subjects. TxA/sub 2/ regeneration RIA may provide a method to measure PLS without administering radioactivity to patient.

  9. miR-564 acts as a dual inhibitor of PI3K and MAPK signaling networks and inhibits proliferation and invasion in breast cancer

    Science.gov (United States)

    Mutlu, Merve; Saatci, Özge; Ansari, Suhail A.; Yurdusev, Emre; Shehwana, Huma; Konu, Özlen; Raza, Umar; Şahin, Özgür

    2016-09-01

    Dysregulation of PI3K and MAPK pathways promotes uncontrolled cell proliferation, apoptotic inhibition and metastasis. Individual targeting of these pathways using kinase inhibitors has largely been insufficient due to the existence of cross-talks between these parallel cascades. MicroRNAs are small non-coding RNAs targeting several genes simultaneously and controlling cancer-related processes. To identify miRNAs repressing both PI3K and MAPK pathways in breast cancer, we re-analyzed our previous miRNA mimic screen data with reverse phase protein array (RPPA) output, and identified miR-564 inhibiting both PI3K and MAPK pathways causing markedly decreased cell proliferation through G1 arrest. Moreover, ectopic expression of miR-564 blocks epithelial-mesenchymal transition (EMT) and reduces migration and invasion of aggressive breast cancer cells. Mechanistically, miR-564 directly targets a network of genes comprising AKT2, GNA12, GYS1 and SRF, thereby facilitating simultaneous repression of PI3K and MAPK pathways. Notably, combinatorial knockdown of these target genes using a cocktail of siRNAs mimics the phenotypes exerted upon miR-564 expression. Importantly, high miR-564 expression or low expression of target genes in combination is significantly correlated with better distant relapse-free survival of patients. Overall, miR-564 is a potential dual inhibitor of PI3K and MAPK pathways, and may be an attractive target and prognostic marker for breast cancer.

  10. Role of nitric oxide synthase in collagen-platelet interaction: involvement of platelet nonintegrin collagen receptor nitrotyrosylation.

    Science.gov (United States)

    Chiang, T M; Cole, F; Woo-Rasberry, V; Kang, E S

    2001-05-15

    Platelets possess the endothelial isoform of nitric oxide synthase (eNOS), which plays an important role in platelet function. Other laboratories, including ours, have reported that nitric oxide (NO) is released upon exposure of platelets to collagen, but the mechanism of the interaction is not yet established. The objective of this study is to examine the possible role of nonintegrin receptor nitrotyrosylation on collagen-induced platelet aggregation. Results of the study show that two platelet proteins with M(r) of 65- and 23-kDa proteins are nitrotyrosylated in a time-dependent manner after the addition of type I collagen. The M(r) 65-kDa protein is identified as the platelet receptor for type I collagen. The recombinant protein of the platelet receptor for type I collagen can also be nitrotyrosylated. The nitrotyrosylated recombinant protein loses its ability to inhibit type I collagen-induced platelet aggregation. In addition, the polyclonal anti-65 kDa immunoprecipitates eNOS suggesting that the platelet nonintegrin receptor for type I collagen is closely linked to the eNOS. These results demonstrate that the inhibitory effect of NO on collagen-induced platelet aggregation may be mediated by the nitrotyrosylation of the 65-kDa receptor.

  11. Design and Synthesis of New Dual Binding Site Cholinesterase Inhibitors: in vitro Inhibition Studies with in silico Docking.

    Science.gov (United States)

    Yar, Muhammad; Bajda, Marek; Mehmood, Rana Atif; Sidra, Lala Rukh; Ullah, Nisar; Shahzadi, Lubna; Ashraf, Muhammad; Ismail, Tayaba; Shahzad, Sohail Anjum; Khan, Zulfiqar Ali; Naqvi, Syed Ali Raza; Mahmood, Nasir

    2014-03-01

    Cholinesterases (ChEs) play a vital role in the regulation of cholinergic transmission. The inhibition of ChEs is considered to be involved in increasing acetylcholine level in the brain and thus has been implicated in the treatment of Alzheimer's disease. We have designed and synthesized a series of novel indole derivatives and screened them for inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Most of the tested compounds exhibited inhibitory activity against AChE and BChE. Among them 4f and 6e showed the highest AChE inhibitory activity with IC50 91.21±0.06 and 68.52±0.04 μM, respectively. However compound 5a exhibited the highest inhibitory activity against BChE (IC50 55.21±0.12 μM).

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

    Institute of Scientific and Technical Information of China (English)

    Sheikh Arshad SAEED; Huma RASHEED

    2003-01-01

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

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

    Science.gov (United States)

    Okazaki, Kenji; Kawazoe, Kazuyoshi; Takaishi, Yoshihisa

    2002-06-01

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

  14. Signaling mechanisms mediated by G-protein coupled receptors in human platelets

    Institute of Scientific and Technical Information of China (English)

    Sheikh Arshad SAEED; Huma RASHEED; Faisal A Wahed FECTO; Mohammad Ilyas ACHAKZAI; Rahmat ALI; John Dennis CONNOR; Anwar-ul-Hassan GILANI

    2004-01-01

    AIM: The present study deals with the investigation of mechanisms involved in the synergistic interaction between epinephrine and arachidonic acid (AA). METHODS: Venous blood was taken from healthy human volunteers reported to be free of medications for one week. Platelet aggregation was monitored at 37 ℃ using Dual-channel Lumi-aggregometer. The resulting aggregation was recorded for 5 min by the measurement of light transmission as a function of time. RESULTS: The data show that a synergism in platelet aggregation mediated by subthreshold concentrations of epinephrine (1μmol/L) and AA (0.2μmol/L) was inhibited by the α2-receptor antagonist (yohimbine, IC50=0.6 μmol/L) and an inhibitor of AA-cyclooxygenase (COX), indomethacin (IC50=0.25 μmol/L).In examining receptor influence on intraplatelet signalling pathways, it was found that the synergistic effect was inhibited by calcium channel blockers, verapamil (IC50=0.4 μtmol/L) and diltiazem (IC50=2.5 μmol/L), as well as by low concentrations of inhibitors of phospholipase C (PLC) (U73122; IC50=0.2 μmol/L) and mitogens activated protein kinase (MAPK) (PD 98059; IC50=3.8 μmol/L). Herbimycin A, a specific inhibitor of tyrosine light chain kinase (TLCK), showed inhibition at IC50 value of 15 μmol/L, whereas chelerythrine, a protein kinase C (PKC)inhibitor, had no effect up to 20 μmol/L. CONCLUSION: These data suggest that synergism between epinephrine and AA in platelet aggregation is triggered through receptors coupled to G-protein, which in turn, activate PLC,COX, and MAP kinase-signaling pathways.

  15. Pegylated G-CSF Inhibits Blood Cell Depletion, Increases Platelets, Blocks Splenomegaly, and Improves Survival after Whole-Body Ionizing Irradiation but Not after Irradiation Combined with Burn

    Science.gov (United States)

    2014-03-05

    of the mice to be treated. The suspension was centrifuged to remove the particulate filler and the supernatant solution was passed through a 0.45-m...processes that involve the destruction of abnormal RBC in the spleen. From our results, we speculate that sple- nomegalymay be caused by removal of RBC...B. Elliott, “ Ciprofloxacin inhibits gamma radiation-induced increases in -H2AX, p53 phosphorylation in human tumor cells and p53 phosphorylation

  16. DUAL INHIBITION OF PI3K/AKT AND mTOR SIGNALING IN HUMAN NON-SMALL CELL LUNG CANCER CELLS BY A DIETARY FLAVONOID FISETIN

    Science.gov (United States)

    Khan, Naghma; Afaq, Farrukh; Khusro, Fatima H.; Adhami, Vaqar Mustafa; Suh, Yewseok; Mukhtar, Hasan

    2011-01-01

    Lung cancer is one of the most commonly occurring malignancies. It has been reported that mTOR is phosphorylated in lung cancer and its activation was more frequent in tumors with over-expression of PI3K/Akt. Therefore, dual inhibitors of PI3K/Akt and mTOR signaling could be valuable agents for treating lung cancer. In the present study, we show that fisetin, a dietary tetrahydroxyflavone inhibits cell-growth with the concomitant suppression of PI3K/Akt and mTOR signaling in human non-small cell lung cancer (NSCLC) cells. Using autodock 4, we found that fisetin physically interacts with the mTOR complex at two sites. Fisetin treatment was also found to reduce the formation of A549 cell colonies in a dose-dependent manner. Treatment of cells with fisetin caused decrease in the protein expression of PI3K (p85 and p110), inhibition of phosphorylation of Akt, mTOR, p70S6K1, eIF-4E and 4E-BP1. Fisetin-treated cells also exhibited dose-dependent inhibition of the constituents of mTOR signaling complex like Rictor, Raptor, GβL and PRAS40. There was increase in the phosphorylation of AMPKα and decrease in the phosphorylation of TSC2 on treatment of cells with fisetin. We also found that treatment of cells with mTOR inhibitor rapamycin and mTOR-siRNA caused decrease in phosphorylation of mTOR and its target proteins which were further downregulated on treatment with fisetin, suggesting that these effects are mediated in part, through mTOR signaling. Our results show that fisetin suppressed PI3K/Akt and mTOR signaling in NSCLC cells and thus, could be developed as a chemotherapeutic agent against human lung cancer. PMID:21618507

  17. Mitogenesis of Vascular Smooth Muscle Cell Stimulated by Platelet-Derived Growth Factor-bb Is Inhibited by Blocking of Intracellular Signaling by Epigallocatechin-3-O-Gallate

    Directory of Open Access Journals (Sweden)

    Mi Hee Lee

    2013-01-01

    Full Text Available Epigallocatechin gallate (EGCG is known to exhibit antioxidant, antiproliferative, and antithrombogenic effects and reduce the risk of cardiovascular diseases. Key events in the development of cardiovascular disease are hypertrophy and hyperplasia according to vascular smooth muscle cell proliferation. In this study, we investigated whether EGCG can interfere with PDGF-bb stimulated proliferation, cell cycle distribution, and the gelatinolytic activity of MMP and signal transduction pathways on RAOSMC when it was treated in two different ways—cotreatment with PDGF-bb and pretreatment of EGCG before addition of PDGF-bb. Both cotreated and pretreated EGCG significantly inhibited PDGF-bb induced proliferation, cell cycle progression of the G0/G1 phase, and the gelatinolytic activity of MMP-2/9 on RAOSMC. Also, EGCG blocked PDGF receptor-β (PDGFR-β phosphorylation on PDGF-bb stimulated RAOSMC under pretreatment with cells as well as cotreatment with PDGF-bb. The downstream signal transduction pathways of PDGFR-β, including p42/44 MAPK, p38 MAPK, and Akt phosphorylation, were also inhibited by EGCG in a pattern similar to PDGFR-β phosphorylation. These findings suggest that EGCG can inhibit PDGF-bb stimulated mitogenesis by indirectly and directly interrupting PDGF-bb signals and blocking the signaling pathway via PDGFR-β phosphorylation. Furthermore, EGCG may be used for treatment and prevention of cardiovascular disease through blocking of PDGF-bb signaling.

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  19. 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.

  20. Rivastigmine: the advantages of dual inhibition of acetylcholinesterase and butyrylcholinesterase and its role in subcortical vascular dementia and Parkinson’s disease dementia

    Directory of Open Access Journals (Sweden)

    Kandiah N

    2017-04-01

    Full Text Available Nagaendran Kandiah,1,2 Ming-Chyi Pai,3,4 Vorapun Senanarong,5 Irene Looi,6,7 Encarnita Ampil,8 Kyung Won Park,9 Ananda Krishna Karanam,10 Stephen Christopher11 1Department of Neurology, National Neuroscience Institute, Tan Tock Seng Hospital, 2Duke-NUS, Graduate Medical School, Singapore; 3Division of Behavioral Neurology, Department of Neurology, 4Alzheimer’s Disease Research Center, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan City, Taiwan; 5Division of Neurology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand; 6Clinical Research Centre, 7Department of Medicine, Hospital Seberang Jaya, Penang, Malaysia; 8Department of Neurology and Psychiatry, Faculty of Medicine and Surgery, University of Santo Tomas, Manila, Philippines; 9Department of Neurology and Cognitive Disorders and Dementia Center, Institute of Convergence Bio-Health, Dong-A University College of Medicine, Busan, Republic of Korea; 10Novartis Healthcare Private Limited, Hyderabad, India; 11Novartis (Singapore Pte. Ltd., Singapore Abstract: Several studies have demonstrated clinical benefits of sustained cholinesterase inhibition with rivastigmine in Alzheimer’s disease (AD and Parkinson’s disease dementia (PDD. Unlike donepezil and galantamine that selectively inhibit acetylcholinesterase (AChE; EC 3.1.1.7, rivastigmine is a unique cholinesterase inhibitor with both AChE and butyrylcholinesterase (BuChE; EC 3.1.1.8 inhibitory activity. Rivastigmine is also available as transdermal patch that has been approved by the US Food and Drug Administration for the treatment of mild, moderate, and severe AD as well as mild-to-moderate PDD. In this review, we explore the role of BuChE inhibition in addition to AChE inhibition with rivastigmine in the outcomes of cognition, global function, behavioral symptoms, and activities of daily living. Additionally, we review the evidence supporting the use of dual

  1. An investigation of hierachical protein recruitment to the inhibitory platelet receptor, G6B-b.

    Science.gov (United States)

    Coxon, Carmen H; Sadler, Amanda J; Huo, Jiandong; Campbell, R Duncan

    2012-01-01

    Platelet activation is regulated by both positive and negative signals. G6B-b is an inhibitory platelet receptor with an immunoreceptor tyrosine-based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM). The molecular basis of inhibition by G6B-b is currently unknown but thought to involve the SH2 domain-containing tyrosine phosphatase SHP-1. Here we show that G6B-b also associates with SHP-2, as well as SHP-1, in human platelets. Using a number of biochemical approaches, we found these interactions to be direct and that the tandem SH2 domains of SHP-2 demonstrated a binding affinity for G6B-b 100-fold higher than that of SHP-1. It was also observed that while SHP-1 has an absolute requirement for phosphorylation at both motifs to bind, SHP-2 can associate with G6B-b when only one motif is phosphorylated, with the N-terminal SH2 domain and the ITIM being most important for the interaction. A number of other previously unreported SH2 domain-containing proteins, including Syk and PLCγ2, also demonstrated specificity for G6B-b phosphomotifs and may serve to explain the observation that G6B-b remains inhibitory in the absence of both SHP-1 and SHP-2. In addition, the presence of dual phosphorylated G6B-b in washed human platelets can reduce the EC(50) for both CRP and collagen.

  2. An investigation of hierachical protein recruitment to the inhibitory platelet receptor, G6B-b.

    Directory of Open Access Journals (Sweden)

    Carmen H Coxon

    Full Text Available Platelet activation is regulated by both positive and negative signals. G6B-b is an inhibitory platelet receptor with an immunoreceptor tyrosine-based inhibitory motif (ITIM and an immunoreceptor tyrosine-based switch motif (ITSM. The molecular basis of inhibition by G6B-b is currently unknown but thought to involve the SH2 domain-containing tyrosine phosphatase SHP-1. Here we show that G6B-b also associates with SHP-2, as well as SHP-1, in human platelets. Using a number of biochemical approaches, we found these interactions to be direct and that the tandem SH2 domains of SHP-2 demonstrated a binding affinity for G6B-b 100-fold higher than that of SHP-1. It was also observed that while SHP-1 has an absolute requirement for phosphorylation at both motifs to bind, SHP-2 can associate with G6B-b when only one motif is phosphorylated, with the N-terminal SH2 domain and the ITIM being most important for the interaction. A number of other previously unreported SH2 domain-containing proteins, including Syk and PLCγ2, also demonstrated specificity for G6B-b phosphomotifs and may serve to explain the observation that G6B-b remains inhibitory in the absence of both SHP-1 and SHP-2. In addition, the presence of dual phosphorylated G6B-b in washed human platelets can reduce the EC(50 for both CRP and collagen.

  3. 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.

  4. Massive elimination of multinucleated osteoclasts by eupatilin is due to dual inhibition of transcription and cytoskeletal rearrangement

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    Ju-Young Kim

    2015-12-01

    Full Text Available Osteoporosis is an aging-associated disease requiring better therapeutic modality. Eupatilin is a major flavonoid from Artemisia plants such as Artemisia princeps and Artemisia argyi which has been reported to possess various beneficial biological effects including anti-inflammation, anti-tumor, anti-cancer, anti-allergy, and anti-oxidation activity. Complete blockade of RANK-dependent osteoclastogenesis was accomplished upon stimulation prior to the receptor activator of nuclear factor κB (RANK-ligand (RANKL treatment or post-stimulation of bone marrow macrophages (BMCs in the presence of RANKL with eupatilin. This blockade was accompanied by inhibition of rapid phosphorylation of Akt, GSK3β, ERK and IκB as well as downregulation of c-Fos and NFATc1 at protein, suggesting that transcriptional suppression is a key mechanism for anti-osteoclastogenesis. Transient reporter assays or gain of function assays confirmed that eupatilin was a potent transcriptional inhibitor in osteoclasts (OC. Surprisingly, when mature osteoclasts were cultured on bone scaffolds in the presence of eupatilin, bone resorption activity was also completely blocked by dismantling the actin rings, suggesting that another major acting site of eupatilin is cytoskeletal rearrangement. The eupatilin-treated mature osteoclasts revealed a shrunken cytoplasm and accumulation of multi-nuclei, eventually becoming fibroblast-like cells. No apoptosis occurred. Inhibition of phosphorylation of cofilin by eupatilin suggests that actin may play an important role in the morphological change of multinucleated cells (MNCs. Human OC similarly responded to eupatilin. However, eupatilin has no effects on osteoblast differentiation and shows cytotoxicity on osteoblast in the concentration of 50 μM. When eupatilin was administered to LPS-induced osteoporotic mice after manifestation of osteoporosis, it prevented bone loss. Ovariectomized (OVX mice remarkably exhibited bone protection effects

  5. 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

  6. Inhibition of CPU0213, a Dual Endothelin Receptor Antagonist, on Apoptosis via Nox4-Dependent ROS in HK-2 Cells

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    Qing Li

    2016-06-01

    Full Text Available Background/Aims: Our previous studies have indicated that a novel endothelin receptor antagonist CPU0213 effectively normalized renal function in diabetic nephropathy. However, the molecular mechanisms mediating the nephroprotective role of CPU0213 remain unknown. Methods and Results: In the present study, we first detected the role of CPU0213 on apoptosis in human renal tubular epithelial cell (HK-2. It was shown that high glucose significantly increased the protein expression of Bax and decreased Bcl-2 protein in HK-2 cells, which was reversed by CPU0213. The percentage of HK-2 cells that showed Annexin V-FITC binding was markedly suppressed by CPU0213, which confirmed the inhibitory role of CPU0213 on apoptosis. Given the regulation of endothelin (ET system to oxidative stress, we determined the role of redox signaling in the regulation of CPU0213 on apoptosis. It was demonstrated that the production of superoxide (O2-. was substantially attenuated by CPU0213 treatment in HK-2 cells. We further found that CPU0213 dramatically inhibited expression of Nox4 protein, which gene silencing mimicked the role of CPU0213 on the apoptosis under high glucose stimulation. We finally examined the role of CPU0213 on ET-1 receptors and found that high glucose-induced protein expression of endothelin A and B receptors was dramatically inhibited by CPU0213. Conclusion: Taken together, these results suggest that this Nox4-dependenet O2- production is critical for the apoptosis of HK-2 cells in high glucose. Endothelin receptor antagonist CPU0213 has an anti-apoptosis role through Nox4-dependent O2-.production, which address the nephroprotective role of CPU0213 in diabetic nephropathy.

  7. 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 patient...

  8. 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...

  9. Gasotransmitters and platelets.

    Science.gov (United States)

    Truss, Nicola J; Warner, Timothy D

    2011-11-01

    Platelets are essential to prevent blood loss and promote wound healing. Their activation comprises of several complex steps which are regulated by a range of mediators. Over the last few decades there has been intense interest in a group of gaseous mediators known as gasotransmitters; currently comprising nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S). Here we consider the action of gasotransmitters on platelet activity. NO is a well established platelet inhibitor which mediates its effects predominantly through activation of soluble guanylyl cyclase leading to a decrease in intraplatelet calcium. More recently CO has been identified as a gasotransmitter with inhibitory actions on platelets; CO acts through the same mechanism as NO but is less potent. The in vivo and platelet functions of the most recently identified gasotransmitter, H(2)S, are still the subject of investigations, but they appear generally inhibitory. Whilst there is evidence for the individual action of these mediators, it is also likely that combinations of these mediators are more relevant regulators of platelets. Furthermore, current evidence suggests that these mediators in combination alter the production of each other, and so modify the circulating levels of gasotransmitters. The use of gasotransmitters as therapeutic agents is also being explored for a range of indications. In conclusion, the importance of NO in the regulation of vascular tone and platelet activity has long been understood. Other gasotransmitters are now establishing themselves as mediators of vascular tone, and recent evidence suggests that these other gasotransmitters may also modulate platelet function.

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

    Directory of Open Access Journals (Sweden)

    Ji Young Park

    2012-01-01

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

  11. 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.

  12. Alloimmune refractoriness to platelet transfusions.

    Science.gov (United States)

    Sandler, S G

    1997-11-01

    Patients who are transfused on multiple occasions with red cells or platelets may develop platelet-reactive alloantibodies and experience decreased clinical responsiveness to platelet transfusion. This situation, conventionally described as "refractoriness to platelet transfusions," is defined by an unsatisfactory low post-transfusion platelet count increment. If antibodies to HLAs are detected, improved clinical outcomes may result from transfusions of HLA-matched or donor-recipient cross-matched platelets. Because refractoriness is an expected, frequently occurring phenomenon, prevention of HLA alloimmunization is an important management strategy. Prevention strategies include efforts to decrease the number of transfusions, filtration of cellular components to reduce the number of HLA-bearing leukocytes, or pretransfusion ultraviolet B irradiation of cellular components to decrease their immunogenicity. Other investigational approaches include reducing the expression of HLAs on transfused platelets, inducing a transient reticuloendothelial system blockade by infusions of specialized immunoglobulin products, or transfusing semisynthetic platelet substitutes (thromboerythrocytes, thrombospheres) or modified platelets (infusible platelet membranes, lyophilized platelets).

  13. Platelet function in dogs

    DEFF Research Database (Denmark)

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

    2007-01-01

    Cairn Terriers, 10 Boxers, and 11 Labrador Retrievers) were included in the study. Platelet function was assessed by whole-blood aggregation with ADP (1, 5, 10, and 20 µM) as agonist and by PFA-100 using collagen and epinephrine (Col + Epi) and Cpæ + ADP as agonists. Plasma thromboxane B2 concentration......Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...

  14. Cisplatin triggers platelet activation.

    Science.gov (United States)

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

    2000-09-01

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

  15. 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....

  16. Quercetin sensitizes glioblastoma to t-AUCB by dual inhibition of Hsp27 and COX-2 in vitro and in vivo.

    Science.gov (United States)

    Li, Junyang; Tang, Chao; Li, Liwen; Li, Rujun; Fan, Youwu

    2016-04-02

    Evidences indicate that inflammatory process plays pivotal role in tumor disease. Soluble epoxide hydrolase inhibitors (sEHIs) have been shown to participate in anti-inflammation and tumorigenesis by protecting epoxyeicosatrienoic acids (EETs). Although we have previously revealed some effects of t-AUCB on glioma in vitro, further investigations are needed to demonstrate its effects on glioblastoma growth in vivo and how to strengthen its antitumor effect. CCK-8 kit was used to test cell growth. Cell migration capacity was performed by wound healing assays. Transwell assay was used to test cell invasion potency. Cell-cycle analysis and cell apoptosis was performed by flow cytometry. The activity of caspase-3 in cells was measured using caspase-3 activity assay kits. Total RNA was extracted from cells lysated by TRIzol reagent. qRT-PCR was performed by ABI 7500 fast RT- PCR system. Lipofectamine RNAiMAX Transfection Reagent (Invitrogen) was used for siRNA transfection. Western blootting was used to test protein expression. Tumor cell xenograft mouse models were used for in vivo study. The SPSS version 17.0 software was applied for statistical analysis. Our data shown that t-AUCB inhibits cell proliferation, migration and invasion and induces cell cycle G1 phase arrest in vitro but induces no cell apoptosis; increased Hsp27 activation and following COX-2 overexpression confer resistance to t-AUCB treatment in glioblastoma both in vitro and in vivo; quercetin sensitizes glioblastoma to t-AUCB by dual inhibition of Hsp27 and COX-2 in vitro and in vivo. These results indicate that combination of t-AUCB and quercetin may be a potential approach to treating glioblastoma.

  17. Blocking the chaperone kinome pathway: Mechanistic insights into a novel dual inhibition approach for supra-additive suppression of malignant tumors

    Energy Technology Data Exchange (ETDEWEB)

    Grover, Abhinav [Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016 (India); Shandilya, Ashutosh [Supercomputing Facility for Bioinformatics and Computational Biology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016 (India); Agrawal, Vibhuti; Pratik, Piyush; Bhasme, Divya; Bisaria, Virendra S. [Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016 (India); Sundar, Durai, E-mail: sundar@dbeb.iitd.ac.in [Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016 (India)

    2011-01-07

    Research highlights: {yields} Withaferin A and 17-DMAG synergistically inhibit the Hsp90-Cdc37 chaperone pair. {yields} Binding of WA to Cdc37 cleft suppresses its kinase binding activity. {yields} 17-DMAG binding to the association complex results in H-bonds with 60% clustering. {yields} The ligands' bound complex was found structurally and thermodynamically stable. -- Abstract: The chaperone Hsp90 is involved in regulating the stability and activation state of more than 200 'client' proteins and takes part in the cancer diseased states. The major clientele-protein kinases depend on Hsp90 for their proper folding and functioning. Cdc37, a kinase targeting co-chaperone of Hsp90, mediates the interactions between Hsp90 and protein kinases. Targeting of Cdc37 has the prospect of delivering predominantly kinase-selective molecular responses as compared to the current pharmacologic Hsp90 inhibitors. The present work reports a bio-computational study carried out with the aim of exploring the dual inhibition of Hsp90/Cdc37 chaperone/co-chaperone association complex by the naturally occurring drug candidates withaferin A and 17-DMAG along with their possible modes of action. Our molecular docking studies reveal that withaferin A in combination with 17-DMAG can act as potent chaperone system inhibitors. The structural and thermodynamic stability of the ligands' bound complex was also observed from molecular dynamics simulations in water. Our results suggest a novel tumor suppressive action mechanism of herbal ligands which can be looked forward for further clinical investigations for possible anticancer drug formulations.

  18. 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.

  19. Targeting acute myeloid leukemia by dual inhibition of PI3K signaling and Cdk9-mediated Mcl-1 transcription.

    Science.gov (United States)

    Thomas, Daniel; Powell, Jason A; Vergez, Francois; Segal, David H; Nguyen, Nhu-Y N; Baker, Adele; Teh, Tse-Chieh; Barry, Emma F; Sarry, Jean-Emmanuel; Lee, Erwin M; Nero, Tracy L; Jabbour, Anissa M; Pomilio, Giovanna; Green, Benjamin D; Manenti, Stéphane; Glaser, Stefan P; Parker, Michael W; Lopez, Angel F; Ekert, Paul G; Lock, Richard B; Huang, David C S; Nilsson, Susie K; Récher, Christian; Wei, Andrew H; Guthridge, Mark A

    2013-08-01

    Resistance to cell death is a hallmark of cancer and renders transformed cells resistant to multiple apoptotic triggers. The Bcl-2 family member, Mcl-1, is a key driver of cell survival in diverse cancers, including acute myeloid leukemia (AML). A screen for compounds that downregulate Mcl-1 identified the kinase inhibitor, PIK-75, which demonstrates marked proapoptotic activity against a panel of cytogenetically diverse primary human AML patient samples. We show that PIK-75 transiently blocks Cdk7/9, leading to transcriptional suppression of MCL-1, rapid loss of Mcl-1 protein, and alleviation of its inhibition of proapoptotic Bak. PIK-75 also targets the p110α isoform of PI3K, which leads to a loss of association between Bcl-xL and Bak. The simultaneous loss of Mcl-1 and Bcl-xL association with Bak leads to rapid apoptosis of AML cells. Concordantly, low Bak expression in AML confers resistance to PIK-75-mediated killing. On the other hand, the induction of apoptosis by PIK-75 did not require the expression of the BH3 proteins Bim, Bid, Bad, Noxa, or Puma. PIK-75 significantly reduced leukemia burden and increased the survival of mice engrafted with human AML without inducing overt toxicity. Future efforts to cotarget PI3K and Cdk9 with drugs such as PIK-75 in AML are warranted.

  20. Dual Inhibition of Activin/Nodal/TGF-β and BMP Signaling Pathways by SB431542 and Dorsomorphin Induces Neuronal Differentiation of Human Adipose Derived Stem Cells

    Directory of Open Access Journals (Sweden)

    Vedavathi Madhu

    2016-01-01

    Full Text Available Damage to the nervous system can cause devastating diseases or musculoskeletal dysfunctions and transplantation of progenitor stem cells can be an excellent treatment option in this regard. Preclinical studies demonstrate that untreated stem cells, unlike stem cells activated to differentiate into neuronal lineage, do not survive in the neuronal tissues. Conventional methods of inducing neuronal differentiation of stem cells are complex and expensive. We therefore sought to determine if a simple, one-step, and cost effective method, previously reported to induce neuronal differentiation of embryonic stem cells and induced-pluripotent stem cells, can be applied to adult stem cells. Indeed, dual inhibition of activin/nodal/TGF-β and BMP pathways using SB431542 and dorsomorphin, respectively, induced neuronal differentiation of human adipose derived stem cells (hADSCs as evidenced by formation of neurite extensions, protein expression of neuron-specific gamma enolase, and mRNA expression of neuron-specific transcription factors Sox1 and Pax6 and matured neuronal marker NF200. This process correlated with enhanced phosphorylation of p38, Erk1/2, PI3K, and Akt1/3. Additionally, in vitro subcutaneous implants of SB431542 and dorsomorphin treated hADSCs displayed significantly higher expression of active-axonal-growth-specific marker GAP43. Our data offers novel insights into cell-based therapies for the nervous system repair.

  1. A colorimetric and fluorometric dual-signal sensor for arginine detection by inhibiting the growth of gold nanoparticles/carbon quantum dots composite.

    Science.gov (United States)

    Liu, Ting; Li, Na; Dong, Jiang Xue; Zhang, Ying; Fan, Yu Zhu; Lin, Shu Min; Luo, Hong Qun; Li, Nian Bing

    2017-01-15

    A bidimensional optical sensing platform which combines the advantages of fluorescence and colorimetry has been designed for arginine (Arg) detection. The system was established by monitoring the influence of Arg on the growth of gold nanoparticles/carbon quantum dots (Au/CQDs) composite, and the CQDs synthesized by ethylene glycol were used as the reducing and stabilizing agent in this paper. Considering that Arg is the only amino acid with guanidine group and has the highest isoelectric point (pI) value at 10.76, Arg would carry positive charges at pH 7.4. Consequently, the positively charged guanidine group of Arg could attract AuCl4(-) and CQDs through electrostatic interaction, which inhibited the growth of Au/CQDs composite. Thereby, the color of the system almost did not change and the fluorescence quenching of CQDs was prevented in the presence of Arg. Based on the color change a low detection limit for Arg was 37nM, and a detection limit of 450nM was obtained by fluorescence spectroscopy. Moreover, this dual-signal sensor also revealed excellent selectivity toward Arg over other amino acids. Besides, Arg can be detected in urine samples with satisfactory results, which demonstrate the potential applications for real analysis.

  2. Applying a dual process model of self-regulation: The association between executive working memory capacity, negative urgency, and negative mood induction on pre-potent response inhibition.

    Science.gov (United States)

    Gunn, Rachel L; Finn, Peter R

    2015-03-01

    This study tested a dual-process model of self-control where the combination of high impulsivity (negative urgency - NU), weak reflective / control processes (low executive working memory capacity - E-WMC), and a cognitive load is associated with increased failures to inhibit pre-potent responses on a cued go/no-go task. Using a within-subjects design, a cognitive load with and without negative emotional load was implemented to consider situational factors. Results suggested that: (1) high NU was associated with low E-WMC; (2) low E-WMC significantly predicted more inhibitory control failures across tasks; and (3) there was a significant interaction of E-WMC and NU, revealing those with low E-WMC and high NU had the highest rates of inhibitory control failures on all conditions of the task. In conclusion, results suggest that while E-WMC is a strong independent predictor of inhibitory control, NU provides additional information for vulnerability to problems associated with self-regulation.

  3. Dual Inhibition of the Epidermal Growth Factor Receptor Pathway with Cetuximab and Erlotinib: A Phase I Study in Patients with Advanced Solid Malignancies

    Science.gov (United States)

    Guarino, Michael J.; Schneider, Charles J.; Hosford, Martha A.; Brahmer, Julie R.; Rudin, Charles M.; Finckenstein, Friedrich Graf; Philip-Norton, Robyn E.; Lu, Haolan; Weber, Martin R.; Ettinger, David S.

    2017-01-01

    Purpose To determine the optimal dose of the antiepidermal growth factor receptor (EGFR) monoclonal antibody cetuximab that can be safely administered in combination with a standard daily dose of erlotinib in patients with advanced solid malignancies. Patients and Methods Patients with advanced solid malignancies who had failed standard chemotherapies received escalating doses of cetuximab without a loading dose (100, 200, 250 mg/m2 i.v. weekly) in combination with a fixed dose of erlotinib (150 mg daily orally) until disease progression or unacceptable toxicity. Results Twenty-two patients were treated, including 14 patients (64%) with non-small cell lung cancer. Twenty patients received combination treatment at the highest dose level for a median of 5.5 weeks (range, 1–31 weeks). One dose-limiting toxicity was observed: grade 3 skin rash. Overall, the most common adverse events (any grade, grade 3/4) were consistent with the safety profiles of the individual drugs: acneform rash (100%, 9%), diarrhea (77%, 5%), and hypomagnesemia (59%, 12%). Seven of 18 evaluable patients (38.9%) had stable disease lasting for a median of 16.6 weeks (range, 6.1–25.1 weeks). Conclusion Dual EGFR inhibition with cetuximab and erlotinib is feasible; the observed toxicities were manageable and consistent with the safety profiles of the individual drugs. The recommended doses for phase II studies are 250 mg/m2 i.v. weekly for cetuximab and 150 mg daily orally for erlotinib. PMID:19182243

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

    Science.gov (United States)

    Tong, L; Yue, T L

    1989-01-01

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    platelet aggregation ruled out bleeding tendency in thrombocytopenic patients. Summary: Background: Methods for testing platelet aggregation in thrombocytopenia are lacking. Objective: To establish a flow-cytometric test of in vitro platelet aggregation independently of the patient's platelet count......, and examine the association of aggregation with a bleeding history in thrombocytopenic patients. Patients/methods: We established a flow-cytometric assay of platelet aggregation, and measured samples from healthy individuals preincubated with antiplatelet drugs, and samples from two patients with inherited...... platelets at platelet counts of > 10 × 109 L-1; otherwise, platelet isolation was required. The platelet aggregation percentage decreased with increasing antiplatelet drug concentration. Platelet aggregation in patients was reduced as compared with healthy individuals: 42% (interquartile range [IQR] 27...

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

    Background Large-scale clinical trials have shown that routine monitoring of the platelet function in patients after percutanous coronary intervention (PCI) is not necessary.However,it is still unclear whether patients received high-risk PCI would benefit from a therapy which is guided by a selective platelet function monitoring.This explanatory study sought to assess the benefit of a therapy guided by platelet function monitoring for these patients.Methods Acute coronary syndrome (ACS) patients (n=384) who received high-risk,complex PCI were randomized into two groups.PCI in the two types of lesions described below was defined as high-risk,complex PCI:lesions that could result in severe clinical outcomes if stent thrombosis occurred or lesions at high risk for stent thrombosis.The patients in the conventionally treated group received standard dual antiplatelet therapy.The patients in the platelet function monitoring guided group received an antiplated therapy guided by a modified thromboelastography (TEG) platelet mapping:If inhibition of platelet aggregation (IPA) induced by arachidonic acid (AA) was less than 50% the aspirin dosage was raised to 200 mg/d; if IPA induced by adenosine diphosphate (ADP) was less than 30% the clopidogrel dosage was raised to 150 mg/d,for three months.The primary efficacy endpoint was a composite of myocardial infarction,emergency target vessel revascularization (eTVR),stent thrombosis,and death in six months.Results This study included 384 patients; 191 and 193 in the conventionally treated group and platelet function monitoring guided group,respectively.No significant differences were observed in the baseline clinical characteristics and interventional data between the two groups.In the platelet function monitoring guided group,the mean IPA induced by AA and ADP were (69.2±24.5)% (range,4.8% to 100.0%) and (51.4±29.8)% (range,0.2% to 100.0%),respectively.The AAinduced IPA of forty-three (22.2%) patients was less

  7. Development of tetravalent IgG1 dual targeting IGF-1R-EGFR antibodies with potent tumor inhibition.

    Science.gov (United States)

    Croasdale, Rebecca; Wartha, Katharina; Schanzer, Juergen M; Kuenkele, Klaus-Peter; Ries, Carola; Mayer, Klaus; Gassner, Christian; Wagner, Martina; Dimoudis, Nikolaos; Herter, Sylvia; Jaeger, Christiane; Ferrara, Claudia; Hoffmann, Eike; Kling, Lothar; Lau, Wilma; Staack, Roland F; Heinrich, Julia; Scheuer, Werner; Stracke, Jan; Gerdes, Christian; Brinkmann, Ulrich; Umana, Pablo; Klein, Christian

    2012-10-15

    In this study we present novel bispecific antibodies that simultaneously target the insulin-like growth factor receptor type I (IGF-1R) and epidermal growth factor receptor (EGFR). For this purpose disulfide stabilized scFv domains of the EGFR/ADCC antibody GA201 were fused via serine-glycine connectors to the C-terminus of the heavy (XGFR2) or light chain (XGFR4), or the N-termini of the light (XGFR5) or heavy chain (XGFR3) of the IGF-1R antibody R1507 as parental IgG1 antibody. The resulting bispecific IGF-1R-EGFR antibodies XGFR2, XGFR3 and XGFR4 were successfully generated with yields and stability comparable to conventional IgG1 antibodies. They effectively inhibited IGF-1R and EGFR phosphorylation and 3D proliferation of H322M and H460M2 tumor cells, induced strong down-modulation of IGF-1R as well as enhanced EGFR down-modulation compared to the parental EGFR antibody GA201 and were ADCC competent. The bispecific XGFR derivatives showed a strong format dependent influence of N- or C-terminal heavy and light chain scFv attachment on ADCC activity and an increase in receptor downregulation over the parental combination in vitro. XGFR2 and XGFR4 were selected for in vivo evaluation and showed potent anti-tumoral efficacy comparable to the combination of monospecific IGF-1R and EGFR antibodies in subcutaneous BxPC3 and H322M xenograft models. In summary, we have managed to overcome issues of stability and productivity of bispecific antibodies, discovered important antibody fusion protein design related differences on ADCC activity and receptor downmodulation and show that IGF-1R-EGFR antibodies represent an attractive therapeutic strategy to simultaneously target two key components de-regulated in multiple cancer types, with the ultimate goal to avoid the formation of resistance to therapy.

  8. Role of blood platelets in infection and inflammation.

    Science.gov (United States)

    Klinger, Matthias H F; Jelkmann, Wolfgang

    2002-09-01

    Blood platelets are here presented as active players in antimicrobial host defense and the induction of inflammation and tissue repair in addition to their participation in hemostasis. Megakaryopoiesis is inhibited after acute infection with viruses or bacteria. In contrast, chronic inflammation is often associated with reactive thrombocytosis. Platelets can bind and internalize pathogens and release microbicidal proteins that kill certain bacteria and fungi. By making cell-cell contacts with leukocytes and endothelial cells, platelets assist white blood cells in rolling, arrest and transmigration. On stimulation by bacteria or thrombin, platelets release the content of their alpha-granules, which include an arsenal of bioactive peptides, such as CC-chemokines and CXC-chemokines and growth factors for endothelial cells, smooth muscle cells and fibroblasts. Thus, integral to innate immunity, the tiny little platelets may become bombshells when irritated by pathogens.

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

    Directory of Open Access Journals (Sweden)

    Ting-Lin Yen

    2014-01-01

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

  10. P-selectin-mediated platelet adhesion promotes the metastasis of murine melanoma cells.

    Science.gov (United States)

    Qi, Cui-Ling; Wei, Bo; Ye, Jie; Yang, Yang; Li, Bin; Zhang, Qian-Qian; Li, Jiang-Chao; He, Xiao-Dong; Lan, Tian; Wang, Li-Jing

    2014-01-01

    Studies have indicated that the aggregation of activated platelets with cancer cells facilitates tumor metastasis; the adhesion molecule P-selectin may be an important mediator of this process, but the detailed mechanism is unclear. In the current study, we established a B16F10 (B16) cell metastatic model in P-selectin knockout (P-sel-/-) mice to determine the effect of P-selectin-mediated platelet adhesion on metastasis. Compared with C57 mice, P-sel-/- mice developed fewer metastatic foci, and cell proliferation within the metastatic tumors was inhibited by P-selectin deficiency. The platelet refusion assay demonstrated that mice with P-sel-/- platelets developed fewer lung metastatic foci (PP-selectin deficiency inhibited the metastasis of B16 cells and that wild-type platelet refusion reversed this inhibition. The P-selectin-mediated interaction between platelets and B16 cells promoted angiogenesis by up-regulating VEGF.

  11. Platelet accumulation in abdominal aortic aneurysm and the effect of antiplatelet drugs; Assessment by indium platelet scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Etami, Hideki (Osaka-Minami National Hospital, Kawachi-nagano (Japan)); Kimura, Kazufumi; Isaka, Yoshinari (and others)

    1992-06-01

    A dual tracer technique using {sup 111}In labeled platelets and {sup 99m}Tc labeled human serum albumin was applied to evaluate the in vivo thrombogenicity in 12 cases with abdominal aortic aneurysm (AAA) and the effect of antiplatelet drug on the thrombogenicity. The magnitude of platelet accumulation at AAA was expressed as the ratio of radioactivity of {sup 111}In platelets on the vascular wall to those in the blood pool (PAI; platelet accumulation index). Of the 12 patients with AAA, 11 had positive studies on baseline imaging and 1 had equivocally positive image. The PAI value (Mean{+-}SD) over the AAA was 53.8{+-}34.1% as compared to -8.6{+-}4.4% in the control group (p<0.01). Seven patients with an AAA and positive baseline images were restudied during platelet active drug with 325 mg of aspirin. During treatment with aspirin, of 7 patients, 5 had positive images, of which 3 were decreased and others unchanged compared to baseline studies, 1 equivocally positive one and one negative one. The PAI value during treatment (21.9{+-}18.6%) was significantly decreased compared to those in baseline study (52.1{+-}23.9%). Our results suggest that the method used for platelet imaging in the present study may be useful for studying the in vivo thrombogenicity and the effect of platelet active drugs in AAA. (author).

  12. Angiogenesis is regulated by a novel mechanism: pro- and antiangiogenic proteins are organized into separate platelet α granules and differentially released

    OpenAIRE

    Italiano, Joseph E.; Richardson, Jennifer L.; Patel-Hett, Sunita; Battinelli, Elisabeth; Zaslavsky, Alexander; Short, Sarah; Ryeom, Sandra; Folkman, Judah; Klement, Giannoula L.

    2008-01-01

    Platelets, in addition to their function in hemostasis, play an important role in wound healing and tumor growth. Because platelets contain angiogenesis stimulators and inhibitors, the mechanisms by which platelets regulate angiogenesis remain unclear. As platelets adhere to activated endothelium, their action can enhance or inhibit local angiogenesis. We therefore suspected a higher organization of angiogenesis regulators in platelets. Using double immunofluorescence and immunoelectron micro...

  13. The use of platelet reactivity testing in patients on antiplatelet therapy for prediction of bleeding events after cardiac surgery

    NARCIS (Netherlands)

    Leunissen, Tesse C; Janssen, Paul; Ten Berg, Jur; Moll, Frans L; Korporaal, Suzanne J A; de Borst, Gert Jan; Pasterkamp, Gerard; Urbanus, Rolf T

    Many patients are treated with platelet inhibitors such as aspirin and clopidogrel for prevention of thrombotic cardiovascular events. However, the inhibitory effect of antiplatelet therapy is variable between patients; in some, the platelets are hardly inhibited, while in others, the platelets are

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

    Science.gov (United States)

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

    2014-01-01

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

  15. Thioredoxin Inhibitors Attenuate Platelet Function and Thrombus Formation

    Science.gov (United States)

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

    2016-01-01

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

  16. The platelet glycoprotein thrombospondin binds specifically to sulfated glycolipids.

    Science.gov (United States)

    Roberts, D D; Haverstick, D M; Dixit, V M; Frazier, W A; Santoro, S A; Ginsburg, V

    1985-08-05

    The human platelet glycoprotein thrombospondin (TSP) binds specifically and with high affinity to sulfatides (galactosylceramide-I3-sulfate). Binding of 125I-TSP to lipids from sheep and human erythrocytes and human platelets resolved on thin layer chromatograms indicates that sulfatides are the only lipids in the membrane which bind TSP. Binding to less than 2 ng of sulfatide could be detected. TSP failed to bind to other purified lipids including cholesterol 3-sulfate, phospholipids, neutral glycolipids, and gangliosides. Binding of 125I-TSP was inhibited by unlabeled TSP, by low pH, and by reduction of intersubunit disulfide bonds with dithiothreitol. A monoclonal antibody against TSP (A2.5), which inhibits hemagglutination and agglutination of fixed activated platelets by TSP, strongly inhibited TSP binding to sulfatides. A second monoclonal antibody (C6.7), which inhibits hemagglutination and aggregation of thrombin-activated live platelets, weakly inhibited sulfatide binding. Binding was inhibited by high ionic strength and by some monosaccharide sulfates including methyl-alpha-D-GlcNAc-3-sulfate. Neutral sugars did not inhibit. Fucoidan, a sulfated fucan, strongly inhibited binding with 50% inhibition at 0.3 micrograms/ml fucoidan. Other sulfated polysaccharides including heparin and dextran sulfates were good inhibitors, whereas hyaluronic acid and keratan sulfate were very weak.

  17. Defining Platelet Function During Polytrauma

    Science.gov (United States)

    2013-02-01

    using calibrated automated thrombography ( CAT ). 3. Platelet-induced clot contraction and using viscoelastic measures such as TEG with Platelet Mapping...using calibrated automated thrombography ( CAT ) in platelet-rich plasma. 3. Platelet-induced clot contraction and effect on clot structure by platelet...if injury with stable vital signs on initial evaluation.  Pregnancy (confirmed with urine pregnancy testing)  Documented do not resuscitate order

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

    Science.gov (United States)

    Etulain, Julia; Negrotto, Soledad; Carestia, Agostina; Pozner, Roberto Gabriel; Romaniuk, María Albertina; D'Atri, Lina Paola; Klement, Giannoula Lakka; Schattner, Mirta

    2012-01-01

    Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.

  19. The role of platelets in hemostasis and the effects of snake venom toxins on platelet function.

    Science.gov (United States)

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

    2017-07-01

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

  20. 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

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

    Science.gov (United States)

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

    2011-12-01

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

  2. Investigating GABA and its function in platelets as compared to neurons.

    Science.gov (United States)

    Kaneez, Fatima Shad; Saeed, Sheikh Arshad

    2009-08-01

    We have recently suggested that platelets could be used as a model for neuronal receptors. In this paper we have investigated gamma-aminobutyric acid (GABA) metabolism and GABA receptors in platelets and in cultured neurons to see whether platelets' GABA mimics neuronal GABA receptor activities. We used the ELISA technique for detecting the GABA concentration in platelet rich plasma and cultured neurons. The functional effects of GABA and its receptor ligands on platelets were determined using an aggregometer. We found that the GABA concentration is 30% lower in platelets than in neurons and in both preparations GABA was metabolized by GABA transaminase (GABA-T). GABA potentiated calcium dependent platelet aggregation with a higher value in washed platelets suspension (WPS) then in platelet rich plasma (PRP). This effect was inhibited by benzodiazepines, calcium channel blockers and the selective phosphoinositide 3-kinase antagonist Wortmannin. GABA neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions. We concluded that platelets could be further developed to be used as a peripheral model to study neuronal GABAergic function and its abnormality in diseases such as epilepsy and schizophrenia. Furthermore our results indicated that PI3-kinase is involved in calcium dependent GABA induced platelet aggregation as this synergistic effect is inhibited by Wortmannin in dose dependent manner.

  3. Role of platelet plasma membrane Ca2+-ATPase in health and disease

    Institute of Scientific and Technical Information of China (English)

    William; L; Dean

    2010-01-01

    Platelets have essential roles in both health and disease. Normal platelet function is required for hemostasis.Inhibition of platelet function in disease or by pharmacological treatment results in bleeding disorders.On the other hand,hyperactive platelets lead to heart attack and stroke.Calcium is a major second messenger in platelet activation,and elevated intracellular calcium leads to hyperactive platelets.Elevated platelet calcium has been documented in hypertension and diabetes;both conditions increase the likelihood of heart attack and stroke. Thus,proper regulation of calcium metabolism in the platelet is extremely important.Plasma membrane Ca2+-ATPase(PMCA)is a major player in platelet calcium metabolism since it provides the only significant route for calcium efflux.In keeping with the important role of calcium in platelet function,PMCA is a highly regulated transporter.In human platelets,PMCA is activated by Ca2+/calmodulin,by cAMP-dependent phosphorylation and by calpain-dependent removal of the inhibitory peptide.It is inhibited by tyrosine phosphorylation and calpain-dependent proteolysis.In addition,the cellular location of PMCA is regulated by a PDZ-domain-dependent interaction with the cytoskeleton during platelet activation.Rapid regulation by phosphorylation results in changes in the rate of platelet activation,whereas calpain-dependent proteolysis and interaction with the cytoskeleton appears to regulate later events such as clot retraction.In hypertension and diabetes,PMCA expression is upregulated while activity is decreased, presumably due to tyrosine phosphorylation.Clearly,a more complete understanding of PMCA function in human platelets could result in the identification of new ways to control platelet function in disease states.

  4. The use of amlodipine, but not of P-glycoprotein inhibiting calcium channel blockers is associated with clopidogrel poor-response.

    Science.gov (United States)

    Harmsze, Ankie M; Robijns, Karen; van Werkum, Jochem W; Breet, Nicoline J; Hackeng, Christian M; Ten Berg, Jurrien M; Ruven, Hendrik J T; Klungel, Olaf H; de Boer, Anthonius; Deneer, Vera H M

    2010-05-01

    Clopidogrel is a prodrug that has to be converted in vivo to its active metabolite by cytochrome (CYP)P450 iso-enzymes. As calcium channel blockers (CCBs) are inhibitors of CYP3A4, concomitant use of these drugs might play a role in the wide inter-individual variability in the response to clopidogrel. However, some CCBs also have strong inhibitory effects on the drug transporter P-glycoprotein (Pgp), which mediates clopidogrel's intestinal absorption. It was the aim of this study to evaluate the effect of co-administration of Pgp-inhibiting and non-Pgp-inhibiting CCBs on on-clopidogrel platelet reactivity in patients on dual antiplatelet therapy undergoing elective percutaneous coronary intervention (PCI). In a total of 623 consecutive patients undergoing elective PCI treated with clopidogrel and aspirin, platelet reactivity to 5 and 20 muM adenosine diphospate (ADP) and clopidogrel poor-response (defined as > 70% platelet aggregation to 20 muM ADP) were evaluated by light transmittance aggregometry. A total of 222 patients (35.6%) were on CCB treatment, of which 98 used Pgp-inhibiting CCBs (verapamil, nifedipine, diltiazem, barnidipine) and 124 patients used the non-Pgp-inhibiting CCB amlodipine. Adjusted mean ADP-induced on-clopidogrel platelet reactivity was significantly higher in both users of Pgp-inhibiting CCBs and amlodipine as compared to CCB non-users (all p<0.05). However, only the use of amlodipine was significantly associated with a 2.3-fold increased risk of clopidogrel poor-response. This study demonstrates that concomitant use of Pgp-inhibiting CCBs and amlodipine increases on-clopidogrel platelet reactivity. Only amlodipine was associated with clopidogrel poor-response. The drug-drug interaction between clopidogrel and amlodipine might be more clinically relevant as compared to P-glycoprotein-inhibiting CCBs.

  5. Coated platelets function in platelet-dependent fibrin formation via integrin αIIbβ3 and transglutaminase factor XIII.

    Science.gov (United States)

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

    2016-04-01

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

  6. A multi-target approach for pain treatment: dual inhibition of fatty acid amide hydrolase and TRPV1 in a rat model of osteoarthritis.

    Science.gov (United States)

    Malek, Natalia; Mrugala, Monika; Makuch, Wioletta; Kolosowska, Natalia; Przewlocka, Barbara; Binkowski, Marcin; Czaja, Martyna; Morera, Enrico; Di Marzo, Vincenzo; Starowicz, Katarzyna

    2015-05-01

    The pharmacological inhibition of anandamide (AEA) hydrolysis by fatty acid amide hydrolase (FAAH) attenuates pain in animal models of osteoarthritis (OA) but has failed in clinical trials. This may have occurred because AEA also activates transient receptor potential vanilloid type 1 (TRPV1), which contributes to pain development. Therefore, we investigated the effectiveness of the dual FAAH-TRPV1 blocker OMDM-198 in an MIA-model of osteoarthritic pain. We first investigated the MIA-induced model of OA by (1) characterizing the pain phenotype and degenerative changes within the joint using X-ray microtomography and (2) evaluating nerve injury and inflammation marker (ATF-3 and IL-6) expression in the lumbar dorsal root ganglia of osteoarthritic rats and differences in gene and protein expression of the cannabinoid CB1 receptors FAAH and TRPV1. Furthermore, we compared OMDM-198 with compounds acting exclusively on FAAH or TRPV1. Osteoarthritis was accompanied by the fragmentation of bone microstructure and destroyed cartilage. An increase of the mRNA levels of ATF3 and IL-6 and an upregulation of AEA receptors and FAAH in the dorsal root ganglia were observed. OMDM-198 showed antihyperalgesic effects in the OA model, which were comparable with those of a selective TRPV1 antagonist, SB-366,791, and a selective FAAH inhibitor, URB-597. The effect of OMDM-198 was attenuated by the CB1 receptor antagonist, AM-251, and by the nonpungent TRPV1 agonist, olvanil, suggesting its action as an "indirect" CB1 agonist and TRPV1 antagonist. These results suggest an innovative strategy for the treatment of OA, which may yield more satisfactory results than those obtained so far with selective FAAH inhibitors in human OA.

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

    Science.gov (United States)

    Edelstein, Leonard C.; Simon, Lukas M.; Lindsay, Cory R.; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E.; Chen, Edward S.; Ma, Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A.

    2014-01-01

    Human platelets express 2 thrombin receptors: protease-activated receptor (PAR)-1 and PAR4. Recently, we reported 3.7-fold increased PAR4-mediated aggregation kinetics in platelets from black subjects compared with white subjects. We now show that platelets from blacks (n = 70) express 14% more PAR4 protein than those from whites (n = 84), but this difference is not associated with platelet PAR4 function. Quantitative trait locus analysis identified 3 common single nucleotide polymorphisms in the PAR4 gene (F2RL3) associated with PAR4-induced platelet aggregation. Among these single nucleotide polymorphisms, rs773902 determines whether residue 120 in transmembrane domain 2 is an alanine (Ala) or threonine (Thr). Compared with the Ala120 variant, Thr120 was more common in black subjects than in white subjects (63% vs 19%), was associated with higher PAR4-induced human platelet aggregation and Ca2+ flux, and generated greater inositol 1,4,5-triphosphate in transfected cells. A second, less frequent F2RL3 variant, Phe296Val, was only observed in blacks and abolished the enhanced PAR4-induced platelet aggregation and 1,4,5-triphosphate generation associated with PAR4-Thr120. PAR4 genotype did not affect vorapaxar inhibition of platelet PAR1 function, but a strong pharmacogenetic effect was observed with the PAR4-specific antagonist YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole]. These findings may have an important pharmacogenetic effect on the development of new PAR antagonists. PMID:25293779

  8. The ultrastructure of camel blood platelets: a comparative study with human, bovine, and equine cells.

    Science.gov (United States)

    Gader, Abdel Galil M Abdel; Ghumlas, Abeer K Al; Hussain, Mansour F; Haidari, Ahmed Al; White, James G

    2008-02-01

    Previous studies indicated that the camel has a very active haemostatic mechanism with a short bleeding time and thrombocytosis. However, platelet function, when tested by agonist-induced aggregation and PFA 100 closure time, showed marked inhibition compared to humans. Since camels are also far more resistant to long exposure to excessive heat and high body temperature than humans, it seemed worthwhile to explore fundamental morphological differences between human and camel platelets and those from other species. The present study has examined the ultrastructure of camel platelets and compared them with the fine structures of human, bovine and equine thrombocytes. Camel platelets, like bovine and equine cells, are discoid in shape and about two-thirds the size of human platelets. A circumferential coil of microtubular supports the disk-like form of camel platelets. Their cytoplasm, like bovine and equine platelets, is filled with alpha granule twice as large as those in human platelets, but lacking the organized matrix of equine alpha granules. Dense bodies are present in camel platelets with whip-like extensions not present on bovine or equine thrombocytes, but found on occasional human platelet dense bodies. Camel platelets, like bovine and equine thrombocytes, lack an open canalicular system (OCS) and must secrete granule products by fusion with the cell wall rather than an OCS. Future studies will determine if the differences in ultrastructural anatomy protect camel platelets from heat more than human thrombocytes.

  9. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical University Luebeck (Federal Republic of Germany). Department of Neurology); Hardeman, M.R. (Amsterdam Univ. (Netherlands). Academisch Ziekenhuis); Henningsen, H. (Heidelberg Univ. (Germany, F.R.). Neurologische Klinik); Petrovici, J.-N. (Cologne-Merheim Hospital (Federal Republic of Germany). Department of Neurology) (eds.)

    1990-01-01

    The increasing number of therapeutic modalities available for the management of patients with thromboembolic complications, such as fibrinolytic treatment or vascular surgery, require the development of new imaging techniques to provide more information on the xtent, age and activity of the thromboembolic material causing clinical symptoms. Since the introduction of radiolabelling of platelets with indium-111, platelet scintigraphy (PSC) has been used as a tool in the diagnosis of various thromboembolic diseases. During the International Symposium on Radiolabelled Platelets scientists from a variety of medical backgrounds presented their results on the clinical applictions of radiolabelled platelets. The papers presented there have been updated to take account of the latest results before publication in this volume. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection. refs.; figs.; tabs.

  10. Platelet preservation: agitation and containers.

    Science.gov (United States)

    van der Meer, Pieter F; de Korte, Dirk

    2011-06-01

    For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted.

  11. Characterization of human platelet glutathione reductase.

    Science.gov (United States)

    Moroff, G; Kosow, D P

    1978-12-08

    Glutathione reductase (NAD(P)h:oxidized glutathione oxidoreductase, EC 1.6.4.2) has been purified 1000-fold from the cytoplasmic fraction of human platelets. Salts, including the heretofore unreported effect of sodium citrate, activate the NADPH-dependent reduction of oxidized glutathione. Sodium citrate and monovalent salt activation appears to involve multiple sites having different binding affinities. At sub-saturating sodium phosphate, non-linear double reciprocal plots indicative of substrate activation by oxidized glutathione were observed. Initial velocity double reciprocal plots at sub-saturating and saturating concentrations of phosphate generate a family of converging lines. NADP+ is a partial inhibitor, indicating that the reduction of oxidized glutathione can proceed by more than one pathway. FMN, FAD, and riboflavin inhibit platelet glutathione reductase by influencing only the V while nitrofurantoin inhibition is associated with an increase Koxidized glutathione and a decreased V.

  12. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong

    2010-12-01

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

  13. The critical roles of cyclic AMP/cyclic AMP-dependent protein kinase in platelet physiology

    Institute of Scientific and Technical Information of China (English)

    Rong YAN; Suping LI; Kesheng DAI

    2009-01-01

    Platelets are the primary players in both thrombosis and hemostasis.Cyclic AMP (cAMP) and cAMP-dependent protein kinase (PKA) are important signaling molecules in the regulation of platelet function,such as adhesion,aggregation,and secretion.Elevation of intracellular cAMP,which induces the activation of PKA,results in the inhibition of platelet function.Thus,tight control of the intracellular cAMP/PKA signaling pathway has great implications for platelet-dependent hemostasis and effective cardiovascular therapy.In this review,we summarize the PKA substrates and their contributions to platelet function,especially the advancing understanding of the cAMP/PKA-dependent signaling pathway in platelet physiology.In addition,we suggest the possibility that cAMP/PKA is involved in the platelet procoagulant process and receptor ectodomain shedding.

  14. Beta-lactam antibiotic-mediated changes in platelet reactivity and vascular endothelial functions.

    Science.gov (United States)

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

    2001-05-01

    To evaluate vascular and platelet compatibility of intravenous administration of beta-lactam antibiotics, we assessed the effects of therapeutic concentrations of ceftriaxone, aztreonam, and ceftazidime on platelet reactivity to different agonists (sodium arachidonate, collagen and adenosine diphosphate) and on selected vascular endothelial functions (adenosine diphosphatase activity, prostacyclin production and t-PA release). Ceftriaxone and, to a lesser degree, aztreonam, enhanced platelet reactivity, evaluated as onset of platelet aggregating response, and increased thromboxane production to subthreshold concentrations of arachidonate. There was no modification in platelet reactivity after ceftazidime treatment. Ceftriaxone and ceftazidime, but not aztreonam, inhibited endothelial adenosine diphosphatase activity. Prostacyclin production and t-PA release were inhibited only by ceftriaxone at high concentrations. While it is difficult to establish which marker (platelet or endothelial functions) has more clinical reference in human vascular compatibility, it seems feasible to consider aztreonam the most compatible of the beta-lactams studied.

  15. 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.

  16. SDF-1α is a novel autocrine activator of platelets operating through its receptor CXCR4.

    Science.gov (United States)

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

    2015-01-01

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

  17. The Platelet and Platelet Function Testing in Liver Disease

    NARCIS (Netherlands)

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

    2009-01-01

    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

  18. Investigation of platelet function and platelet disorders using flow cytometry.

    Science.gov (United States)

    Rubak, Peter; Nissen, Peter H; Kristensen, Steen D; Hvas, Anne-Mette

    2016-01-01

    Patients with thrombocytopenia or platelet disorders are at risk of severe bleeding. We report the development and validation of flow cytometry assays to diagnose platelet disorders and to assess platelet function independently of platelet count. The assays were developed to measure glycoprotein levels (panel 1) and platelet function (panel 2) in sodium citrated blood. Twenty healthy volunteers and five patients diagnosed with different platelet disorders were included. Glycoprotein expression levels of the receptors Ia, Ib, IIb, IIIa and IX were measured and normalised with forward scatter (FS) as a measurement of platelet size. Platelet function was assessed by CD63, P-selectin and bound fibrinogen in response to arachidonic acid, adenosine diphosphate (ADP), collagen-related peptide, ristocetin and thrombin receptor-activation peptide-6. All patients except one with suspected δ-granule defect showed aberrant levels of glycoproteins in panel 1. Glanzmann's thrombasthenia and genetically verified Bernard-Soulier syndrome could be diagnosed using panel 1. All patients showed reduced platelet function according to at least one agonist. Using panel 2 it was possible to diagnose Bernard-Soulier syndrome, δ-granule defect and GPVI disorder. By combining the two assays, we were able to diagnose different platelet disorders and investigate platelet function independent of platelet count.

  19. 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.

  20. Epithelial sodium channel modulates platelet collagen activation.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Alonso-Rangel, Lea; Benítez-Cardoza, Claudia; Ortega, Arturo

    2014-03-01

    Activated platelets adhere to the exposed subendothelial extracellular matrix and undergo a rapid cytoskeletal rearrangement resulting in shape change and release of their intracellular dense and alpha granule contents to avoid hemorrhage. A central step in this process is the elevation of the intracellular Ca(2+) concentration through its release from intracellular stores and on throughout its influx from the extracellular space. The Epithelial sodium channel (ENaC) is a highly selective Na(+) channel involved in mechanosensation, nociception, fluid volume homeostasis, and control of arterial blood pressure. The present study describes the expression, distribution, and participation of ENaC in platelet migration and granule secretion using pharmacological inhibition with amiloride. Our biochemical and confocal analysis in suspended and adhered platelets suggests that ENaC is associated with Intermediate filaments (IF) and with Dystrophin-associated proteins (DAP) via α-syntrophin and β-dystroglycan. Migration assays, quantification of soluble P-selectin, and serotonin release suggest that ENaC is dispensable for migration and alpha and dense granule secretion, whereas Na(+) influx through this channel is fundamental for platelet collagen activation.

  1. Murine monoclonal antibody to platelet factor 4/heparin complexes as a potential reference standard for platelet activation assays in heparin-induced thrombocytopenia.

    Science.gov (United States)

    Asada, Reiko; Wanaka, Keiko; Walenga, Jeanine; Prechel, Margaret; Miyashita, Kumiko; Escalante, Vicki; Kaneko, Chieko; Hoshino, Nobuhiro; Oosawa, Mitsuru; Matsuo, Miyako

    2013-01-01

    Quality control of the platelet activation assays to diagnose heparin-induced thrombocytopenia (HIT), (14)C-serotonin release assay (SRA) and platelet aggregation test (PAT) has yet to be established due to lack of reference standards and the difficulty of obtaining significant amounts of HIT antibodies from patients with HIT. We prepared a murine monoclonal antibody to human platelet factor 4 (hPF4)/heparin complexes (HIT-MoAb) and investigated the platelet activating action of HIT-MoAb by using SRA and PAT. The HIT-MoAb activated human platelets at low heparin concentration and the platelet activations were inhibited at high heparin concentration in both SRA and PAT. The HIT-MoAb produced a concentration-dependent effect. Moreover, the platelet activation at low heparin concentration was inhibited by anti-FcγRIIa antibody. These results indicated that HIT-MoAb has characteristics similar to human HIT antibodies regarding heparin-dependent platelet activation. Therefore, it is suggested that HIT-MoAb has the potential to be a positive control or reference standard in platelet activation assays.

  2. Clopidogrel discontinuation and platelet reactivity following coronary stenting

    LENUS (Irish Health Repository)

    2011-01-01

    Summary. Aims: Antiplatelet therapy with aspirin and clopidogrel is recommended for 1 year after drug-eluting stent (DES) implantation or myocardial infarction. However, the discontinuation of antiplatelet therapy has become an important issue as recent studies have suggested a clustering of ischemic events within 90 days of clopidogrel withdrawal. The objective of this investigation was to explore the hypothesis that there is a transient ‘rebound’ increase in platelet reactivity within 3 months of clopidogrel discontinuation. Methods and Results: In this prospective study, platelet function was assessed in patients taking aspirin and clopidogrel for at least 1 year following DES implantation. Platelet aggregation was measured using a modification of light transmission aggregometry in response to multiple concentrations of adenosine diphosphate (ADP), epinephrine, arachidonic acid, thrombin receptor activating peptide and collagen. Clopidogrel was stopped and platelet function was reassessed 1 week, 1 month and 3 months later. Thirty-two patients on dual antiplatelet therapy were recruited. Discontinuation of clopidogrel increased platelet aggregation to all agonists, except arachidonic acid. Platelet aggregation in response to ADP (2.5, 5, 10, and 20 μm) and epinephrine (5 and 20 μm) was significantly increased at 1 month compared with 3 months following clopidogrel withdrawal. Thus, a transient period of increased platelet reactivity to both ADP and epinephrine was observed 1 month after clopidogrel discontinuation. Conclusions: This study demonstrates a transient increase in platelet reactivity 1 month after clopidogrel withdrawal. This phenomenon may, in part, explain the known clustering of thrombotic events observed after clopidogrel discontinuation. This observation requires confirmation in larger populations.

  3. Benefit and safety of dual anti-platelet therapy after coronary artery bypass grafting: a Meta-analysis of 15 studies%冠状动脉旁路移植术后双联抗血小板治疗meta分析

    Institute of Scientific and Technical Information of China (English)

    魏光夏; 孙战文

    2016-01-01

    -term curative effect after coronary artery bypass grafting with the comparison of benefit and safety between dual anti-platelet therapy and aspirin therapy alone.Methods Medline, Embase, ScienceDirect and Cochrane Library were searched to identify randomized controlled trials concerning the comparison of benefit and safety between dual anti-platelet therapy and aspirin therapy alone, with extraction effect sizes including mortality, bleeding events, myocardial ischemia and graft occlusion.Newcastle-Ottawa Scale and Jadal scales were used to evaluate the quality of observational case-control studies and randomized controlled studies.Statistical analysis was performed using Meta R.15.2 software package.Results 15 literatures were enrolled for Meta-analyses, including 8randomized controlled studies, 3 prospective observational studies and 4 retrospective observational studies.Among a total of 31 365patiens, 8 642 patients were received combination therapy of aspirin and clopidogrel after CABG, and 22 723 patients were received combination therapy of aspirin and placebo or aspirin therapy alone.The Meta-analysis results, with comparison of the early postoperative curative effect in 13 literatures, showed that, relative to aspirin therapy alone, dual anti-platelet therapy could reduce the risk of graft occlusion(OR =0.53,95% CI: 0.37-0.76, P =0.001), reduce the risk of myocardial ischemia (OR =0.84, 95 % CI: 0.71-0.99, P =0.038) , reduce the risk of mortality after CABG (OR =0.47,95 % CI: 0.36-0.61, P <0.001), simultaneously not increase the risk of bleeding events.The Meta-analysis results, with comparison of the long-term postoperative curative effect in 2 literatures, showed that the significant difference could not be found between two method of therapy about affecting the risk of graft occlusion (OR =0.40, 95 % CI: 0.02-6.90, P =0.523) , myocardial ischemia(OR =0.49, 95% CI: 0.04-6.10, P =0.597), and mortality (OR =0.55, 95 % CI: 0.13-2.80, P =0.420).Conclusion

  4. Crocin prevents sesamol-induced oxidative stress and apoptosis in human platelets.

    Science.gov (United States)

    Thushara, Ram M; Hemshekhar, Mahadevappa; Paul, Manoj; Shanmuga Sundaram, Mahalingam; Shankar, Rohith L; Kemparaju, Kempaiah; Girish, Kesturu S

    2014-10-01

    Recent studies have reported the platelet proapoptotic propensity of plant-derived molecules such as, resveratrol, thymoquinone, andrographolide and gossypol. Meanwhile, there were also reports of phytochemicals such as cinnamtannin B1, which shows antiapoptotic effect towards platelets. Platelets are mainly involved in hemostasis, thrombosis and wound healing. However, altered platelet functions can have serious pathological outcomes that include cardiovascular diseases. Platelets are sensitive to external and internal stimuli including therapeutic and dietary components. The anuclear platelets do undergo apoptosis via mitochondrial pathway. However, exaggerated rate of platelet apoptosis could lead to thrombocytopenia and other bleeding disorders. The present study deals with ameliorative efficacy of crocin on sesamol-induced platelet apoptosis. The antiapoptotic property of crocin and the proapoptotic tendency of sesamol in platelets were previously demonstrated. Therefore, it was interesting to see how these two compounds would interact and wield their effects on human platelets. Crocin effectively inhibited sesamol-induced oxidative stress on platelets, which was evidenced by the measurement of endogenously generated reactive oxygen species, particularly hydrogen peroxide, and changes in thiol levels. Further, crocin abrogated sesamol-induced biochemical events of apoptosis in platelets, which include intracellular calcium mobilization, changes in mitochondrial membrane integrity, cytochrome c release, caspase activity and phosphatidylserine externalization. Even though sesamol has proapoptotic effects on platelets, its anti-platelet activity cannot be neglected. Thus, the study proposes that sesamol could be supplemented with crocin, an approach that could not only abolish the toxic effects of sesamol on platelets, but also enhance the quality of treatment due to their synergistic action.

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

    Science.gov (United States)

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

    2003-10-01

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

  6. Platelets from pulmonary hypertension patients show increased mitochondrial reserve capacity

    Science.gov (United States)

    Nguyen, Quyen L.; Corey, Catherine; White, Pamela; Watson, Annie; Gladwin, Mark T.; Simon, Marc A.

    2017-01-01

    Accumulating evidence suggests that altered cellular metabolism is systemic in pulmonary hypertension (PH) and central to disease pathogenesis. However, bioenergetic changes in PH patients and their association with disease severity remain unclear. Here, we hypothesize that alteration in bioenergetic function is present in platelets from PH patients and correlates with clinical parameters of PH. Platelets isolated from controls and PH patients (n = 28) were subjected to extracellular flux analysis to determine oxygen consumption and glycolytic rates. Platelets from PH patients showed greater glycolytic rates than controls. Surprisingly, this was accompanied by significant increases in the maximal capacity for oxygen consumption, leading to enhanced respiratory reserve capacity in PH platelets. This increased platelet reserve capacity correlated with mean pulmonary artery pressure, pulmonary vascular resistance, and right ventricular stroke work index in PH patients and was abolished by the inhibition of fatty acid oxidation (FAO). Consistent with a shift to FAO, PH platelets showed augmented enzymatic activity of carnitine palmitoyltransferase-1 and electron transport chain complex II. These data extend the observation of a metabolic alteration in PH from the pulmonary vascular axis to the hematologic compartment and suggest that measurement of platelet bioenergetics is potentially useful in assessment of disease progression and severity. PMID:28289721

  7. Lactodifucotetraose, a human milk oligosaccharide, attenuates platelet function and inflammatory cytokine release.

    Science.gov (United States)

    Newburg, David S; Tanritanir, Ayse C; Chakrabarti, Subrata

    2016-07-01

    Human milk strongly quenches inflammatory processes in vitro, and breastfed infants have lower incidence of inflammatory diseases than those fed artificially. Platelets from neonates, in contrast to those from adults, are less responsive to platelet agonists such as collagen, thrombin, ADP, and epinephrine. Breastfed infants absorb oligosaccharides intact from the human milk in their gut to the circulation. This study was to determine whether these oligosaccharides can attenuate platelet function and platelet secretion of pro-inflammatory proteins, and to identify the active component. The natural mixture of oligosaccharides from human milk and pure individual human milk oligosaccharides were tested for their ability to modulate responses of platelets isolated from human blood following exposure to thrombin, ADP, and collagen. Human milk and the natural mixture of human milk oligosaccharides inhibited platelet release of inflammatory proteins. Of the purified human milk oligosaccharides tested, only lactodifucotetraose (LDFT) significantly inhibited thrombin induced release of the pro-inflammatory proteins RANTES and sCD40L. LDFT also inhibited platelet adhesion to a collagen-coated surface, as well as platelet aggregation induced by ADP or collagen. These data indicate that LDFT may help modulate hemostasis by suppressing platelet-induced inflammatory processes in breastfed infants. This activity suggests further study of LDFT for its potential as a therapeutic agent in infants and adults.

  8. P-selectin-mediated platelet adhesion promotes the metastasis of murine melanoma cells.

    Directory of Open Access Journals (Sweden)

    Cui-Ling Qi

    Full Text Available Studies have indicated that the aggregation of activated platelets with cancer cells facilitates tumor metastasis; the adhesion molecule P-selectin may be an important mediator of this process, but the detailed mechanism is unclear. In the current study, we established a B16F10 (B16 cell metastatic model in P-selectin knockout (P-sel-/- mice to determine the effect of P-selectin-mediated platelet adhesion on metastasis. Compared with C57 mice, P-sel-/- mice developed fewer metastatic foci, and cell proliferation within the metastatic tumors was inhibited by P-selectin deficiency. The platelet refusion assay demonstrated that mice with P-sel-/- platelets developed fewer lung metastatic foci (P<0.01 with a lower microvascular density (MVD than mice with wild-type platelets. A co-culture model of platelets and B16 cells was utilized to determine the difference in VEGF concentration in the supernatants. The results demonstrated that the supernatant from the P-sel-/- platelet/B16 co-culture had a lower concentration of VEGF. Therefore, our findings indicated that P-selectin deficiency inhibited the metastasis of B16 cells and that wild-type platelet refusion reversed this inhibition. The P-selectin-mediated interaction between platelets and B16 cells promoted angiogenesis by up-regulating VEGF.

  9. IκB kinase phosphorylation of SNAP-23 controls platelet secretion.

    Science.gov (United States)

    Karim, Zubair A; Zhang, Jinchao; Banerjee, Meenakshi; Chicka, Michael C; Al Hawas, Rania; Hamilton, Tara R; Roche, Paul A; Whiteheart, Sidney W

    2013-05-30

    Platelet secretion plays a key role in thrombosis, thus the platelet secretory machinery offers a unique target to modulate hemostasis. We report the regulation of platelet secretion via phosphorylation of SNAP-23 at Ser95. Phosphorylation of this t-soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) occurs upon activation of known elements of the platelet signaling cascades (ie, phospholipase C, [Ca(2+)]i, protein kinase C) and requires IκB kinase (IKK)-β. Other elements of the nuclear factor κB/IκB cascade (ie, IKK-α,-β,-γ/NEMO and CARMA/MALT1/Bcl10 complex) are present in anucleate platelets and IκB is phosphorylated upon activation, suggesting that this pathway is active in platelets and implying a nongenomic role for IKK. Inhibition of IKK-β, either pharmacologically (with BMS-345541, BAY11-7082, or TPCA-1) or by genetic manipulation (platelet factor 4 Cre:IKK-β(flox/flox)), blocked SNAP-23 phosphorylation, platelet secretion, and SNARE complex formation; but, had no effect on platelet morphology or other metrics of platelet activation. Consistently, SNAP-23 phosphorylation enhanced membrane fusion of SNARE-containing proteoliposomes. In vivo studies with IKK inhibitors or platelet-specific IKK-β knockout mice showed that blocking IKK-β activity significantly prolonged tail bleeding times, suggesting that currently available IKK inhibitors may affect hemostasis.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

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

    Science.gov (United States)

    Navdaev, Alexey; Subramanian, Hariharan; Petunin, Alexey; Clemetson, Kenneth J; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

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

  12. 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.

  13. 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 NH4Cl (a lysosome inhibitor). Furthermore, platelet aggregation induced by AA was markedly attenuated by resveratrol and reSIRT1. Likewise, the increased pulmonary thrombus formation in mice treated with AA was also attenuated by SIRT1 activators. In line with these results, pulmonary thrombus formation was markedly attenuated in SIRT1-TG mice. Taken together, this study showed that SIRT1 downregulates PAFR expression on platelets via proteasomal and lysosomal pathways, and that this downregulation inhibits platelet aggregation in vitro and pulmonary thrombus formation in vivo.

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

    African Journals Online (AJOL)

    Amira M. Elsayed

    2016-03-30

    Mar 30, 2016 ... Abstract The mean platelet volume (MPV) is a laboratory marker associated with platelet func- tion and activity. .... the first 24 h of presentation to the emergency department. Severity of ..... J Neurol Neurosurg Psychiatry.

  15. The effects of bupivacaine and pipecoloxylidide on platelet function in vitro.

    Science.gov (United States)

    Odoom, J A; Sturk, A; Dokter, P W; Bovill, J G; ten Cate, J W; Oosting, J

    1989-07-01

    The influence of bupivacaine and its major metabolite, pipecoloxylidide, on human platelet function was studied in vitro. Significant inhibition of ADP and collagen-induced platelet aggregation occurred only with concentrations of bupivacaine above 10 micrograms.ml-1. This concentration (10-25 micrograms.ml-1) is much higher than would be expected in routine clinical use of bupivacaine for epidural analgesia. The inhibition of platelet aggregation was associated with a significant decrease in beta-thromboglobulin secretion. In contrast, pipecoloxylidide had no effect on platelet aggregation or the beta-thromboglobulin release. We conclude that the previously reported 30-min time-lag between the maximal plasma concentration of bupivacaine and the inhibition of platelet aggregation is unlikely to be due to a metabolism of bupivacaine to pipecoloxylidide.

  16. Effect of flunarizine and calcium on serotonin uptake in human and rat blood platelets and rat synaptosomes

    DEFF Research Database (Denmark)

    Jensen, P N; Smith, D F; Poulsen, J H

    1994-01-01

    in blood platelets, whereas no effect was observed in synaptosomes. Flunarizine inhibited serotonin uptake in a concentration dependent manner with an IC50 value of 1 mumol/L in blood platelets and 5 mumol/L in synaptosomes. The inhibition did not depend on the presence of extracellular calcium indicating...

  17. 替格瑞洛联合比伐卢定对STEMI-PCI患者血小板抑制率、聚集率及预后的影响%Effect of ticagrelor combined with bivalirudin on platelet inhibition rate, aggregation rate, and prognosis in patients with STEMI-PCI

    Institute of Scientific and Technical Information of China (English)

    张晓霞

    2016-01-01

    目的 观察替格瑞洛联合比伐卢定对行冠状动脉介入治疗的ST段抬高心肌梗死(STEMI-PCI)患者血小板抑制率、聚集率及预后的影响.方法 以2014年2月至2015年1月本院心内科收治的80例STEMI-PCI患者为研究对象,随机数字表法均分为观察组和对照组.对照组给予替格瑞洛治疗,观察组替格瑞洛联合比伐卢定治疗,比较治疗后两组血小板抑制率、聚集率及预后.结果 治疗后,观察组血小板抑制率[(80.98±9.98)%]较对照组[(48.89±8.89)%]显著高(P<0.05);两组治疗后血小板聚集率均较治疗前显著降低,且观察组血小板聚集率[(35.69±5.01)%、(29.21±4.33)%、(24.2l±3.21)%]均较对照组显著降低(P< 0.05);观察组治疗后不良事件总发生率显著低于对照组(P<0.05);两组不良反应发生率差异无统计学意义(P>0.05).结论 替格瑞洛联合比伐卢定对STEMI-PCI患者改善血小板抑制、聚集作用均显著,对患者预后效果佳.%Objective To observe the effect of ticagrelor combined with bivalirudin on the platelet inhibition,aggregation rate,and prognosis in patients with ST segment elevation myocardial infarction and undergoing percutaneous coronary intervention (STEMI-PCI).Methods Eighty patients with STEMI-PCI admitted into our hospital from February,2014 to January,2015 were randomized into an observation group and a control group.The control group was treated with ticagrelor and the observation group ticagrelor and bivalirudin.The effects on platelet inhibition rate,aggregation rate,and prognosis were compared between these two groups after treatment.Results After treatment,the platelet inhibition rate was significantly higher in the observation group than in the control group [(80.98±9.98)% vs.(48.89±8.89)%] (P < 0.05).The platelet aggregation rates were significantly lower after than before treatment in both groups.The platelet aggregation rates in the observation group [(35.69±5

  18. Contractile proteins of endothelial cells, platelets and smooth muscle.

    Science.gov (United States)

    Becker, C G; Nachman, R L

    1973-04-01

    In experiments described herein it was observed, by direct and indirect immunofluorescence technics, that rabbit antisera to human platelet actomyosin (thrombosthenin) stained mature megakaryocytes, blood platelets, endothelial cells and smooth muscle cells of arteries and veins, endothelial cells of liver sinusoids and certain capillaries, uterine smooth muscle cells, myoepithelial cells, perineurial cells of peripheral nerves and "fibroblastic" cells of granulation tissue. The specificity of immunohistologic staining was confirmed by appropriate absorption and blocking studies and immunodiffusional analysis in agarose gel. It was also observed by immunodiffusional analysis in agarose gel, electrophoresis of actomyosin fragments in polyacrylamide gels, immune inhibition of actomyosin ATPase activity and immune aggregation of platelets that uterine and platelet actomyosin are partially, but not completely, identical.

  19. Dual high-resolution inhibition profiling and HPLC-HRMS-SPE-NMR analysis for identification of α-glucosidase and radical scavenging inhibitors in Solanum americanum Mill

    DEFF Research Database (Denmark)

    Silva, Eder Lana e; Almeida-Lafetá, Rita C.; Borges, Ricardo Moreira

    2017-01-01

    Solanum americanum is one of the most prominent species used to treat type 2 diabetes in Guatemala. In our ongoing efforts to find antidiabetic and antioxidative compounds from natural sources, an ethyl acetate extract of this medicinal herb was investigated using dual high-resolution α......-glucosidase/radical scavenging inhibition profiling. The high-resolution biochromatograms obtained by this technique were used to target subsequent structural elucidation by HPLC-HRMS-SPE-NMR analysis towards the bioactive constituents. This led to identification of 4-hydroxybenzoic acid ( 1 ) and 3-indolecarboxylic acid ( 6...

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Prophylactic platelets in dengue

    DEFF Research Database (Denmark)

    Whitehorn, James; Rodriguez Roche, Rosmari; Guzman, Maria G

    2012-01-01

    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...

  3. Development of the platelet micro-orifice injector. [for liquid propellant rocket engines

    Science.gov (United States)

    La Botz, R. J.

    1984-01-01

    For some time to come, liquid rocket engines will continue to provide the primary means of propulsion for space transportation. The injector represents a key to the optimization of engine and system performance. The present investigation is concerned with a unique injector design and fabrication process which has demonstrated performance capabilities beyond that achieved with more conventional approaches. This process, which is called the 'platelet process', makes it feasible to fabricate injectors with a pattern an order of magnitude finer than that obtainable by drilling. The fine pattern leads to an achievement of high combustion efficiencies. Platelet injectors have been identified as one of the significant technology advances contributing to the feasibility of advanced dual-fuel booster engines. Platelet injectors are employed in the Space Shuttle Orbit Maneuvering System (OMS) engines. Attention is given to injector design theory as it relates to pattern fineness, a description of platelet injectors, and test data obtained with three different platelet injectors.

  4. Risk and benefit of dual antiplatelet treatment among nonrevascularized myocardial infarction patients in different age groups

    DEFF Research Database (Denmark)

    Juul, Nikolai; Gislason, Gunnar; Olesen, Jonas Bjerring;

    2017-01-01

    BACKGROUND: Dual anti-platelet treatment with clopidogrel and aspirin is indicated for most patients after myocardial infarction. We examined the risk/benefit relationship of dual anti-platelet treatment according to age in a nationwide cohort of 30,532 myocardial infarction patients without...... revascularization. METHODS: Patients admitted with first-time myocardial infarction in 2002-2010, not undergoing revascularization, were identified from nationwide Danish registers. Dual anti-platelet treatment use was assessed by claimed prescriptions. Stratified into age groups, risk of bleeding, all...... included (mean age 67.02 (±13.8) years and 64.7% males). Use of dual anti-platelet treatment decreased with age: 80% (79 years). We found a reduced risk of cardiovascular death, recurrent myocardial infarction and ischaemic stroke in users

  5. Rho GTPases in platelet function.

    Science.gov (United States)

    Aslan, J E; McCarty, O J T

    2013-01-01

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

  6. Sulfatides partition disabled-2 in response to platelet activation.

    Directory of Open Access Journals (Sweden)

    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. 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.

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

    Science.gov (United States)

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

    2007-02-01

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

  9. Expansion of the neonatal platelet mass is achieved via an extension of platelet lifespan

    OpenAIRE

    Liu, Zhi-Jian; Hoffmeister, Karin M.; Hu, Zhongbo; Mager, Donald E.; Ait-Oudhia, Sihem; Debrincat, Marlyse A.; Pleines, Irina; Josefsson, Emma C.; Benjamin T Kile; Italiano, Joseph; Ramsey, Haley; Grozovsky, Renata; Veng-Pedersen, Peter; Chavda, Chaitanya; Sola-Visner, Martha

    2014-01-01

    Rapid growth and rising platelet counts result in a significant expansion of platelet mass during neonatal life.The rise in platelet counts is mediated by a prolongation in the neonatal platelet lifespan.

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

    Science.gov (United States)

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

    2012-03-01

    Postprandial platelet hyperactivity and aggregation play a crucial role in the pathogenesis of metabolic syndrome. The purpose of the present study was to evaluate the effect of boiled wild plants consumption on the postprandial platelet aggregation in metabolic syndrome patients. Patients consumed 5 meals in a random order (ie, 4 wild plant meals, namely, Reichardia picroides [RP], Cynara cardunculus, Urospermum picroides [UP], and Chrysanthemum coronarium, and a control meal, which contained no wild plants). Several biochemical indices as well as platelet activating factor (PAF)- and adenosine diphosphate-induced ex vivo platelet aggregation were measured postprandially. Moreover, the ability of plants extract to inhibit rabbit platelet aggregation was tested in vitro. The consumption of RP and UP meals significantly reduced ex vivo adenosine diphosphate-induced postprandial platelet aggregation compared with the control meal. The consumption of UP meals significantly reduced the ex vivo PAF-induced platelet aggregation postprandially. Both UP and RP extracts significantly inhibited PAF-induced rabbit platelet aggregation in vitro. Wild plants consumption reduced postprandial platelet hyperaggregability of metabolic syndrome patients, which may account for their healthy effects. Copyright © 2012 Elsevier Inc. All rights reserved.

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

    Indian Academy of Sciences (India)

    Sam Annie-JeyachristYn; Arumugam Geetha; Rajagopal Surendran

    2008-03-01

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

  12. 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.

  13. MECHANISM OF PRESERVING EFFECT OF APROTININ ON PLATELET FUNCTION DURING CARDIOPULMONARY BYPASS

    Institute of Scientific and Technical Information of China (English)

    黄惠民; 丁文祥; 苏肇伉; 张伟忠

    1992-01-01

    The deficiency of platelet function is the main defect of hemostatic mechanism during cardiopulmonary bypass (CPB), which attributed to the postoperative bleeding complication to a great extent. The proteinase inhibitor aprotinin was reported to have preserving effect on platelet adhesion during CPB. In this clinical reserch we found that CPB caused plasma alpha 2-antiplasmin decreasing, indicating the fibrinolytic system activation. Meanwhile, the ristocetin-induced aggregation declined to 39.6% and platelet GPIb decreased to 50% of preoperative value. However, by treatment with aprotinin, the plasma alpha 2-antiplasmin during CPB did not change, platelet aggregation was improved and platelet GPIb was preserved, and consequently resulted in a 46% lower blood loss postoperatively. These results confirmed that aprotinin could inhibit the fibrinolysis during CPB, and thus relieve the platelet damage and improve the postoperative hemostatic mechanism.

  14. PREGNANCY WITH PLATELET FUNCTION DISORDER

    Directory of Open Access Journals (Sweden)

    Sheila K

    2014-01-01

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

  15. Dual inhibition of the PI3K/AKT/mTOR pathway suppresses the growth of leiomyosarcomas but leads to ERK activation through mTORC2: biological and clinical implications.

    Science.gov (United States)

    Fourneaux, Benjamin; Chaire, Vanessa; Lucchesi, Carlo; Karanian, Marie; Pineau, Raphael; Laroche-Clary, Audrey; Italiano, Antoine

    2017-01-31

    The PI3K/AKT/mTOR pathway plays a crucial role in the development of leiomyosarcomas (LMSs). In this study, we tested the efficacy of dual PI3K/mTOR (BEZ235), PI3K (BKM120) and mTOR (everolimus) inhibitors in three human LMS cell lines. In vitro and in vivo studies using LMS cell lines showed that BEZ235 has a significantly higher anti-tumor effect than either BKM120 or everolimus, resulting in a greater reduction in tumor growth and more pronounced inhibitory effects on mitotic activity and PI3K/AKT/mTOR signaling. Strikingly, BEZ235 but neither BKM120 nor everolimus markedly enhanced the ERK pathway. This effect was reproduced by the combination of BKM120 and everolimus, suggesting the involvement of mTORC2 via a PI3K-independent mechanism. Silencing of RICTOR in LMS cells confirmed the role of mTORC2 in the regulation of ERK activity. Combined treatment with BEZ235 and GSK1120212, a potent MEK inhibitor, resulted in synergistic growth inhibition and apoptosis induction in vitro and in vivo. These findings document for the first time that dual PI3K/mTOR inhibition in leiomyosarcomas suppress a negative feedback loop mediated by mTORC2, leading to enhanced ERK pathway activity. Thus, combining a dual PI3K/mTOR inhibitor with MEK inhibitors may be a relevant approach to increase anti-tumor activity and prevent drug resistance in patients with LMS.

  16. The NLRP3 inflammasome and bruton's tyrosine kinase in platelets co-regulate platelet activation, aggregation, and in vitro thrombus formation.

    Science.gov (United States)

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

    2017-01-29

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

  17. Stimulation of Toll-like receptor 2 in human platelets induces a thromboinflammatory response through activation of phosphoinositide 3-kinase.

    Science.gov (United States)

    Blair, Price; Rex, Sybille; Vitseva, Olga; Beaulieu, Lea; Tanriverdi, Kahraman; Chakrabarti, Subrata; Hayashi, Chie; Genco, Caroline A; Iafrati, Mark; Freedman, Jane E

    2009-02-13

    Cells of the innate immune system use Toll-like receptors (TLRs) to initiate the proinflammatory response to microbial infection. Recent studies have shown acute infections are associated with a transient increase in the risk of vascular thrombotic events. Although platelets play a central role in acute thrombosis and accumulating evidence demonstrates their role in inflammation and innate immunity, investigations into the expression and functionality of platelet TLRs have been limited. In the present study, we demonstrate that human platelets express TLR2, TLR1, and TLR6. Incubation of isolated platelets with Pam(3)CSK4, a synthetic TLR2/TLR1 agonist, directly induced platelet aggregation and adhesion to collagen. These functional responses were inhibited in TLR2-deficient mice and, in human platelets, by pretreatment with TLR2-blocking antibody. Stimulation of platelet TLR2 also increased P-selectin surface expression, activation of integrin alpha(IIb)beta(3), generation of reactive oxygen species, and, in human whole blood, formation of platelet-neutrophil heterotypic aggregates. TLR2 stimulation also activated the phosphoinositide 3-kinase (PI3-K)/Akt signaling pathway in platelets, and inhibition of PI3-K significantly reduced Pam(3)CSK4-induced platelet responses. In vivo challenge with live Porphyromonas gingivalis, a Gram-negative pathogenic bacterium that uses TLR2 for innate immune signaling, also induced significant formation of platelet-neutrophil aggregates in wild-type but not TLR2-deficient mice. Together, these data provide the first demonstration that human platelets express functional TLR2 capable of recognizing bacterial components and activating the platelet thrombotic and/or inflammatory pathways. This work substantiates the role of platelets in the immune and inflammatory response and suggests a mechanism by which bacteria could directly activate platelets.

  18. The properties of B-form monoamine oxidase in mitochondria from monkey platelet.

    Science.gov (United States)

    Obata, Toshio; Aomine, Masahiro

    The present study was examined the effect of the properties of monkey platelet monoamine oxidase (MAO) based on inhibitor sensitivity. Monkey platelet showed a high MAO activity with beta-phenylethylamine (beta-PEA) as substrate and a very low A-form MAO activity with 5 hydroxytryptamine (5-HT) as substrate. Moreover, monkey platelet MAO was sensitive to the drugs deprenyl as B-form MAO inhibitor and less sensitive to clorgyline and harmaline as A form MAO inhibitor with beta-PEA as the B-form MAO substrate. B-form MAO from monkey platelet was more stable against heat treatment at 55 degrees C than B-form MAO in brain. After digestion with trypsin at 37 degrees C for 4 hrs, it was found that MAO from platelet was inhibited about 70% with beta-PEA as substrate with brain. The tricyclic antidepressant imipramine and nortriptyline inhibited B-form MAO activity more potency than B-form MAO in brain. However, when the noncyclic antidepressant nomifensine was used, monkey platelet B-form MAO activities were less potently inhibited. All these reagents were noncompetitive inhibitors of B form MAO in monkey platelet. The present studies demonstrated that monkey platelet MAO is a single of B-form MAO and sensitive to tricyclic antidepressants.

  19. 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...

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

    Science.gov (United States)

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

    2014-07-01

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

  1. PGE2 decreases reactivity of human platelets by activating EP2 and EP4.

    Science.gov (United States)

    Smith, James P; Haddad, Elias V; Downey, Jason D; Breyer, Richard M; Boutaud, Olivier

    2010-07-01

    Platelet hyperreactivity associates with cardiovascular events in humans. Studies in mice and humans suggest that prostaglandin E2 (PGE2) regulates platelet activation. In mice, activation of the PGE2 receptor subtype 3 (EP3) promotes thrombosis, but the significance of EP3 in humans is less well understood. To characterize the regulation of thromboxane-dependent human platelet activation by PGE2. Platelets collected from nineteen healthy adults were studied using an agonist of the thromboxane receptor (U46,619), PGE2, and selective agonists and/or antagonists of the EP receptor subtypes. Platelet activation was assayed by (1) optical aggregometry, (2) measurement of dense granule release, and (3) single-platelet counting. Healthy volunteers demonstrated significant interindividual variation in platelet response to PGE2. PGE2 completely inhibited U46,619-induced platelet aggregation and ATP release in 26% of subjects; the remaining 74% had partial or no response to PGE2. Antagonism of EP4 abolished the inhibitory effect of PGE2. In all volunteers, a selective EP2 agonist inhibited U46,619-induced aggregation. Furthermore, the selective EP3 antagonist DG-041 converted all PGE2 nonresponders to full responders. There is significant interindividual variation of platelet response to PGE2 in humans. The balance between EP2, EP3, and EP4 activation determines its net effect. PGE2 can prevent thromboxane-induced platelet aggregation in an EP4-dependent manner. EP3 antagonism converts platelets of nonresponders to a PGE2-responsive phenotype. These data suggest that therapeutic targeting of EP pathways may have cardiovascular benefit by decreasing platelet reactivity. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  2. Platelet adhesion and degranulation induce pro-survival and pro-angiogenic signalling in ovarian cancer cells.

    Directory of Open Access Journals (Sweden)

    Karl Egan

    Full Text Available Thrombosis is common in ovarian cancer. However, the interaction of platelets with ovarian cancer cells has not been critically examined. To address this, we investigated platelet interactions in a range of ovarian cancer cell lines with different metastatic potentials [HIO-80, 59M, SK-OV-3, A2780, A2780cis]. Platelets adhered to ovarian cancer cells with the most significant adhesion to the 59M cell line. Ovarian cancer cells induced platelet activation [P-selectin expression] in a dose dependent manner, with the most significant activation seen in response to the 59M cell line. The platelet antagonists [cangrelor, MRS2179, and apyrase] inhibited 59M cell induced activation suggesting a P2Y12 and P2Y1 receptor mediated mechanism of platelet activation dependent on the release of ADP by 59M cells. A2780 and 59M cells potentiated PAR-1, PAR-4, and TxA2 receptor mediated platelet activation, but had no effect on ADP, epinephrine, or collagen induced activation. Analysis of gene expression changes in ovarian cancer cells following treatment with washed platelets or platelet releasate showed a subtle but valid upregulation of anti-apoptotic, anti-autophagy pro-angiogenic, pro-cell cycle and metabolic genes. Thus, ovarian cancer cells with different metastatic potential adhere and activate platelets differentially while both platelets and platelet releasate mediate pro-survival and pro-angiogenic signals in ovarian cancer cells.

  3. Effect of curcumin on the adhesion of platelets to brain microvascular endothelial cells in vitro

    Institute of Scientific and Technical Information of China (English)

    Li ZHANG; Zhen-lun GU; Zheng-hong QIN; Zhong-qin LIANG

    2008-01-01

    Aim: To determine whether curcumin prevents the adhesion of platelets to brain microvascular endothelial cells (BMECs) cultured in vitro. Methods: [3H]Ad-chine-labeled platelets were incubated with BMECs to investigate the role of curcumin in the adhesion of platelets to BMECs. The number of platelets adher-ing to the BMECs monolayer was determined by liquid scintillation spectroscopy. The thrombin-induced expression of platelets P-selectin, glycoprotein Ⅱb (GPⅡb), and glycoprotein Ⅲa (GPⅢa) on the cell surface, was measured by flow cytometry. P-selectin mRNA levels of BMECs were determined by RT-PCR. The TNF-α-induced expressions of P-selectin and E-selectin on the surface of BMECs were determined by Western blotting. Results: The adhesion between thrombin-acti-vated platelets and normal BMECs, and that of TNF-α-activated BMECs and normal platelets were significantly increased, and this increase could be inhibited by curcumin (30-240 μmol/L) in a concentration-dependant manner. The platelets activated with thrombin and BMECs stimulated by TNF-α demonstrated an upregulated expressions of P-selectin and E-selectin, and this increase, when pretreated with curcumin for 30 min, could be restrained dose dependently. Curcumin also inhibited the increase of the GPⅡb/GPⅢa expression of thrombin-activated platelets in a concentration-dependent manner. Conclusion: Curcumin can inhibit the platelets to BMECs. This effect may be related to the decreased expressions of P-selectin, E-selectin, and GPⅡb/GPⅢa on platelets and BMECs.

  4. Platelet function and hemolysis in centrifugal pumps: in vitro investigations.

    Science.gov (United States)

    Steines, D; Westphal, D; Göbel, C; Reul, H; Rau, G

    1999-08-01

    The effects of centrifugal pumps on blood components other than erythrocytes, namely platelets and their interaction with the coagulation system, are not very well known. In a comparative study with three centrifugal pumps (BioMedicus BP-80, St. Jude Isoflow, and Sarns Delphin) and the Stockert roller pump hemolysis, platelet counts, thromboplastin and partial thromboplastin times, as well as resonance thrombography (RTG) parameters for the assessment of platelet and coagulation function were evaluated in vitro. Normalized indices of hemolysis (NIH) with ACD anticoagulation after 360 minutes were 0.008+/-0.004 (Isoflow), 0.018+/-0.017 (BP-80), 0.085+/-0.051 (Delphin), and 0.049+/-0.010 g/1001 (roller pump). Plasmatic coagulation was activated in all circuits. Platelet function was severely inhibited by the BP-80, indicated by increase in RTG platelet time to 358%+/-150% of initial values compared to 42%+/-29% (Isoflow), 40%+/-20% (Delphin), and 12%+/-10% (roller pump). Fibrin polymerization was affected similarly. The large surface area of the BP-80 leads to an extensive activation of platelets and plasminogen.

  5. 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.

  6. Drug effects on platelet adherence to collagen and damaged vessel walls.

    Science.gov (United States)

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

    1978-01-01

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

  7. Estrogen, inflammation, and platelet phenotype.

    Science.gov (United States)

    Miller, Virginia M; Jayachandran, Muthuvel; Hashimoto, Kazumori; Heit, John A; Owen, Whyte G

    2008-01-01

    Although exogenous estrogenic therapies increase the risk of thrombosis, the effects of estrogen on formed elements of blood are uncertain. This article examines the genomic and nongenomic actions of estrogen on platelet phenotype that may contribute to increased thrombotic risk. To determine aggregation, secretion, protein expression, and thrombin generation, platelets were collected from experimental animals of varying hormonal status and from women enrolled in the Kronos Early Estrogen Prevention Study. Estrogen receptor beta predominates in circulating platelets. Estrogenic treatment in ovariectomized animals decreased platelet aggregation and adenosine triphosphate (ATP) secretion. However, acute exposure to 17beta-estradiol did not reverse decreases in platelet ATP secretion invoked by lipopolysaccharide. Thrombin generation was positively correlated to the number of circulating microvesicles expressing phosphatidylserine. Assessing the effect of estrogen treatments on blood platelets may lead to new ways of identifying women at risk for adverse thrombotic events with such therapies.

  8. Effects of Pneumolysin on Human Polymorphonuclear Leukocytes and Platelets

    OpenAIRE

    Johnson, M K; Boese-Marrazzo, D; Pierce, W. A.

    1982-01-01

    Pneumolysin was bound by human polymorphonuclear leukocytes in a reaction which occurred very rapidly at 0 degrees C. Low concentrations of pneumolysin were found to stimulate leukocyte migration and lysosomal enzyme secretion. At increasing lysin levels, inhibition of spontaneous migration and chemotaxis, cell death, and lysis were observed. Pneumolysin was also found to lyse platelets and to activate serum to become chemotactic.

  9. Mechanism investigation of platelet apoptosis inhibition by N-Arachidonoylethanolamine%花生四烯乙醇胺对血小板凋亡的抑制作用及其机制探讨

    Institute of Scientific and Technical Information of China (English)

    庄云龙; 乔文本; 张毅; 于媛; 房云海; 徐群; 张心声; 张文静

    2014-01-01

    目的 探讨血站标准存储条件下花生四烯乙醇胺(ANA)对血小板凋亡的抑制作用及相关机制.方法 取志愿者血小板,分别单独加入0.5 μmol/L ANA或联合加入0.5 μmol/L ANA和l μmol/L大麻素1型受体抑制剂利莫那班(Rimonabant,SR141716),在(22±2)℃水平振荡仪中振荡保存7d,同时设不加药物的血小板作为对照组.流式细胞术检测血小板膜磷脂酰丝氨酸(PS)表达水平;Western blot法检测凋亡相关蛋白表达;用细胞色素C(Cyt-C)检测试剂盒检测其从线粒体释放到胞质水平;免疫共沉淀法检测BCL-XL和Bak蛋白相互作用.结果 ANA处理组PS表达阳性率(早期细胞凋亡率)显著低于对照组[(8.29±1.44)%对(14.24±2.47)%];ANA处理组Cyt-C从线粒体释放到胞质的百分比显著低于对照组[(3.29±1.44)%对(15.24±3.40)%];ANA处理组血小板凋亡相关蛋白磷酸化(p)-Akt和p-Bad表达水平均高于对照组[(71.33±10.26)%对(35.00±6.00)%; (39.00±9.64)%对(10.33±1.53)%,P值均< 0.05];ANA处理组BCL-XL和Bak蛋白的结合量显著高于对照组(约为对照组的2.6倍);ANA处理组活化的caspase-9和caspase-3水平均显著低于对照组[(9.63±1.47)%对(23.24±2.47)%;(6.30±1.40)%对(13.20±2.50)%].ANA+ SR141716组各项检测指标与对照组结果相似,两组相比差异无统计学意义.结论ANA通过影响凋亡蛋白的表达水平,抑制Cyt-C释放到胞质使血小板免于凋亡而起到保护作用.%Objective To investigate the mechanism of N-Arachidonoylethanolamine (ANA) on inhibiting platelets (PLT) apoptosis under standard blood bank storage conditions.Methods Samples taken from collected apheresis PLT by the Amicus instrument were split into three parts.An aliquot of 0.5 μmol/L ANA were added to one part of storage PLT as the ANA group; an aliquot of 0.5 μmol/L ANA and 1 μmol/L SR141716 was added to the another part as the ANA + SR141716 group; and the third part without ANA and SR141716

  10. Complement Activation Alters Platelet Function

    Science.gov (United States)

    2015-12-01

    Award Number: W81XWH-12-1-0523 TITLE: Complement Activation Alters Platelet Function PRINCIPAL INVESTIGATOR: George Tsokos, M.D. CONTRACTING...Activation Alters Platelet Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0523 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) George Tsokos, M.D...a decreased level of disease. Further studies will expand upon these observations better outlining the function of platelets in the injury associated

  11. 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.

  12. In vitro short-term platelet adhesion on various metals.

    Science.gov (United States)

    Tanaka, Yuta; Kurashima, Kazuya; Saito, Haruka; Nagai, Akiko; Tsutsumi, Yusuke; Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao

    2009-01-01

    The in vitro short-term platelet adhesion on various metals, as accelerated by the addition of Ca(2+), was evaluated in this study. Metals used for medical devices [an austenitic stainless steel, a cobalt (Co)-chromium (Cr)-molybdenum (Mo) alloy, a titanium (Ti)-6 aluminum (Al)-4 vanadium (V) alloy, a Ti-6Al-7 niobium (Nb) alloy, a Tinickel (Ni) alloy, and commercially pure Ti] were immersed into a platelet-rich plasma solution for 5 or 20 min, and platelet adhesion and aggregation on the surfaces were observed using a scanning electron microscope. The platelet adhesion level on each metal after 5 min of immersion in a platelet-rich plasma solution was the smallest in this order: stainless steel alloy alloy alloy alloy = Ti. The levels after 5 min of immersion were almost the same as those after 20 min of immersion. Platelet adhesion was minimal on stainless steel and Co-Cr-Mo alloy, which have a Cr(2)O(3)-containing passive surface oxide film, but was accelerated on Ti and Ti alloys having a TiO(2)-containing film. A Cr(2)O(3)-containing oxide film has a lower relative permittivity than a TiO(2)-containing film; it thus supports a larger electrostatic force than the latter, adsorbs more albumins, which work as inhibitory proteins, and inhibits platelet aggregation. Therefore, platelet adhesion and aggregation are controlled by the composition of the surface oxide film on a metal due to the relative permittivity of the metal, which influences the amount of adsorbed proteins.

  13. Nanoparticle-induced platelet aggregation and vascular thrombosis.

    Science.gov (United States)

    Radomski, Anna; Jurasz, Paul; Alonso-Escolano, David; Drews, Magdalena; Morandi, Maria; Malinski, Tadeusz; Radomski, Marek W

    2005-11-01

    Ever increasing use of engineered carbon nanoparticles in nanopharmacology for selective imaging, sensor or drug delivery systems has increased the potential for blood platelet-nanoparticle interactions. We studied the effects of engineered and combustion-derived carbon nanoparticles on human platelet aggregation in vitro and rat vascular thrombosis in vivo. Multiplewall (MWNT), singlewall (SWNT) nanotubes, C60 fullerenes (C60CS) and mixed carbon nanoparticles (MCN) (0.2-300 microg ml(-1)) were investigated. Nanoparticles were compared with standard urban particulate matter (SRM1648, average size 1.4 microm). Platelet function was studied using lumi aggregometry, phase-contrast, immunofluorescence and transmission electron microscopy, flow cytometry, zymography and pharmacological inhibitors of platelet aggregation. Vascular thrombosis was induced by ferric chloride and the rate of thrombosis was measured, in the presence of carbon particles, with an ultrasonic flow probe. Carbon particles, except C60CS, stimulated platelet aggregation (MCN>or=SWNT>MWNT>SRM1648) and accelerated the rate of vascular thrombosis in rat carotid arteries with a similar rank order of efficacy. All particles resulted in upregulation of GPIIb/IIIa in platelets. In contrast, particles differentially affected the release of platelet granules, as well as the activity of thromboxane-, ADP, matrix metalloproteinase- and protein kinase C-dependent pathways of aggregation. Furthermore, particle-induced aggregation was inhibited by prostacyclin and S-nitroso-glutathione, but not by aspirin. Thus, some carbon nanoparticles and microparticles have the ability to activate platelets and enhance vascular thrombosis. These observations are of importance for the pharmacological use of carbon nanoparticles and pathology of urban particulate matter.

  14. Platelet effects on ovarian cancer

    Science.gov (United States)

    Davis, Ashley; Afshar-Kharghan, Vahid; Sood, Anil K.

    2014-01-01

    Growing understanding of the role of thrombocytosis, high platelet turnover, and the presence of activated platelets in the circulation in cancer progression and metastasis has brought megakaryocytes into focus. Platelet biology is essential to hemostasis, vascular integrity, angiogenesis, inflammation, innate immunity, wound healing, and cancer biology. However, before megakaryocyte/platelet-directed therapies can be considered for clinical use, understanding of the mechanism and biology of paraneoplastic thrombocytosis in malignancy is required. Here, we provide an overview of the clinical implications, biological significance, and mechanisms of paraneoplastic thrombocytosis in the context of ovarian cancer. PMID:25023353

  15. 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.

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

    Science.gov (United States)

    Rodgers, G M

    1999-06-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

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

    OpenAIRE

    Edelstein, Leonard C.; Simon, Lukas M.; Lindsay, Cory R.; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E.; Chen, Edward S.; Ma,Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A.; Bray, Paul F.

    2014-01-01

    White individuals have a high frequency of the common PAR4 gene (F2RL3) variant Ala120; blacks have a high frequency of Thr120.PAR4 Thr120 induces greater signaling and is associated with greater platelet aggregation and reduced inhibition by a PAR4 antagonist.

  19. Differential proteomic analysis of platelets suggested possible signal cascades network in platelets treated with salvianolic acid B.

    Directory of Open Access Journals (Sweden)

    Chao Ma

    Full Text Available BACKGROUND: Salvianolic acid B (SB is an active component isolated from Danshen, a traditional Chinese medicine widely used for the treatment of cardiovascular disorders. Previous study suggested that SB might inhibit adhesion as well as aggregation of platelets by a mechanism involving the integrin α2β1. But, the signal cascades in platelets after SB binding are still not clear. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, a differential proteomic analysis (two-dimensional electrophoresis was conducted to check the protein expression profiles of rat platelets with or without treatment of SB. Proteins altered in level after SB exposure were identified by MALDI-TOF MS/MS. Treatment of SB caused regulation of 20 proteins such as heat shock-related 70 kDa protein 2 (hsp70, LIM domain protein CLP-36, copine I, peroxiredoxin-2, coronin-1 B and cytoplasmic dynein intermediate chain 2C. The regulation of SB on protein levels was confirmed by Western blotting. The signal cascades network induced by SB after its binding with integrin α2β1 was predicted. To certify the predicted network, binding affinity of SB to integrin α2β1 was checked in vitro and ex vivo in platelets. Furthermore, the effects of SB on protein levels of hsp70, coronin-1B and intracellular levels of Ca²+ and reactive oxygen species (ROS were checked with or without pre-treatment of platelets using antibody against integrin α2β1. Electron microscopy study confirmed that SB affected cytoskeleton structure of platelets. CONCLUSIONS/SIGNIFICANCE: Integrin α2β1 might be one of the direct target proteins of SB in platelets. The signal cascades network of SB after binding with integrin α2β1 might include regulation of intracellular Ca²+ level, cytoskeleton-related proteins such as coronin-1B and cytoskeleton structure of platelets.

  20. Differential Proteomic Analysis of Platelets Suggested Possible Signal Cascades Network in Platelets Treated with Salvianolic Acid B

    Science.gov (United States)

    Ma, Chao; Yao, Yan; Yue, Qing-Xi; Zhou, Xin-Wen; Yang, Peng-Yuan; Wu, Wan-Ying; Guan, Shu-Hong; Jiang, Bao-Hong; Yang, Min; Liu, Xuan; Guo, De-An

    2011-01-01

    Background Salvianolic acid B (SB) is an active component isolated from Danshen, a traditional Chinese medicine widely used for the treatment of cardiovascular disorders. Previous study suggested that SB might inhibit adhesion as well as aggregation of platelets by a mechanism involving the integrin α2β1. But, the signal cascades in platelets after SB binding are still not clear. Methodology/Principal Findings In the present study, a differential proteomic analysis (two-dimensional electrophoresis) was conducted to check the protein expression profiles of rat platelets with or without treatment of SB. Proteins altered in level after SB exposure were identified by MALDI-TOF MS/MS. Treatment of SB caused regulation of 20 proteins such as heat shock-related 70 kDa protein 2 (hsp70), LIM domain protein CLP-36, copine I, peroxiredoxin-2, coronin-1 B and cytoplasmic dynein intermediate chain 2C. The regulation of SB on protein levels was confirmed by Western blotting. The signal cascades network induced by SB after its binding with integrin α2β1 was predicted. To certify the predicted network, binding affinity of SB to integrin α2β1 was checked in vitro and ex vivo in platelets. Furthermore, the effects of SB on protein levels of hsp70, coronin-1B and intracellular levels of Ca(2+) and reactive oxygen species (ROS) were checked with or without pre-treatment of platelets using antibody against integrin α2β1. Electron microscopy study confirmed that SB affected cytoskeleton structure of platelets. Conclusions/Significance Integrin α2β1 might be one of the direct target proteins of SB in platelets. The signal cascades network of SB after binding with integrin α2β1 might include regulation of intracellular Ca(2+) level, cytoskeleton-related proteins such as coronin-1B and cytoskeleton structure of platelets. PMID:21379382