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Induced Platelet Aggregation (induced + platelet_aggregation)
Selected AbstractsADP-induced platelet aggregation in acute ischemic stroke patients on aspirin therapyEUROPEAN JOURNAL OF NEUROLOGY, Issue 12 2008J.-K. Cha Background and purpose:, Aspirin is an important therapeutic regimen to prevent the recurrent ischemic events or death after acute ischemic stroke. In this study, we evaluated the relationship between the extent of adenosine diphosphate (ADP) -induced platelet aggregation and outcome in acute ischemic stroke patients on aspirin therapy. Methods:, We selected 107 acute ischemic stroke patients who had been prescribed aspirin and evaluated platelet function test by using optic platelet aggregometer test after 5 days of taking it and investigated the prognosis 90 days after ischemic events. Kaplan,Meyer curve was used for survival analysis. Results:, After stratification of the subjected patients by tertiles of ADP-induced platelet aggregation, the events rates were 7.4%, 9.3% and 30.8% (P = 0.023). In multiple logistic regression analysis, old age over 70 years (OR, 13.7; 95% CI, 2.14,88.07; P = 0.001) and the increased ADP-induced platelet aggregation had independent significance to the risk of primary end-points after acute ischemic stroke (OR, 1.1; 95% CI 1.01 to 1.20; P = 0.026). Conclusions:, This study showed that the increased ADP-induced platelet aggregation under using aspirin is associated with poor outcome after acute ischemic stroke. [source] BIOACTIVE POLAR LIPIDS IN OLIVE OIL, POMACE AND WASTE BYPRODUCTSJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2008HARALABOS C. KARANTONIS ABSTRACT Olive oil protects against atherosclerosis because of biologically active microconstituents. In this study, total polar lipids from olive oil, pomace, pomace oil and waste byproducts were extracted, fractionated by thin layer chromatography and tested for their bioactivity. The most active ones were further purified on high-performance liquid chromatography, and the resulting lipid fractions were tested for their bioactivity. Bioactive compounds were determined in all samples with the exception of olive pomace oil. These lipids inhibited platelet-activating factor (PAF)-induced platelet aggregation and also induced platelet aggregation. The bioactive compound from olive pomace has been chemically characterized as a glycerylether-sn-2-acetyl glycolipid based on mass spectra. Chemical determinations and mass spectrometry data reinforce the assumption that these active microconstituents share both similar bioactivity and common structural features. The existence of PAF antagonists in polar lipid extracts from olive oil waste by-products render them biologically valuable materials for the food industry that could be used for the production of functional foods. PRACTICAL APPLICATIONS Isolated bioactive polar lipids from waste by-products of the olive oil industry that act as inhibitors of platelet-activating factor (PAF) may be used for enrichment and production of foods with higher nutritional value, as PAF plays a major role in inflammatory disorders, including atherosclerosis development. [source] The Residual Platelet Aggregation after Deployment of Intracoronary Stent (PREDICT) scoreJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2008T. GEISLER Summary.,Background:,Recent studies suggest a high interindividual variability of response to clopidogrel associated with adverse cardiovascular outcome. Different clinical factors are considered to influence a persistent residual platelet aggregation (RPA) despite conventional antiplatelet therapy. Objectives:,To investigate clinical factors that affect RPA after 600-mg clopidogrel loading in a large unselected cohort of patients with symptomatic CAD. Methods:,The study population included a consecutive cohort of 1092 patients treated with coronary stenting for stable angina and acute coronary syndromes (ACS). Residual platelet activity was assessed by ADP (20 ,mol L,1)-induced platelet aggregation , 6 h after LD. Eleven clinical factors were included in the primary analysis. Results:,In multivariate regression analysis increased RPA was significantly influenced by ACS, reduced LV-function, diabetes mellitus, renal failure (creatinine > 1.5 mg dL,1), and age > 65 years. In a factor-weighed model the risk for high RPA increased with higher score levels (OR for patients with a score of 1,3, 1.21, 95% CI 0.7,2.1; score 4,6, OR 2.0, 95% CI 1.17,3.5; P = 0.01; score 7,9, OR 3.3, 95% CI 1.8,6.0). During a 30-day follow-up the incidence of major adverse events was higher in patients with RPA in the upper tertile (4.8% vs. 2.5% in the 2nd and 1.5% in the 1st tertile; P < 0.05). Conclusions:,The PREDICT score provides a good tool to estimate residual platelet activity after clopidogrel LD by easily available patient details. Additionally, we demonstrate its association with short-term outcome. Thus, patients with a high score may benefit from intensified antiplatelet therapy by improved platelet inhibition and risk reduction for thromboischemic events. [source] Differential response of platelets to chemokines: RANTES non-competitively inhibits stimulatory effect of SDF-1,JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2004B. Shenkman Summary.,Background:,Among the chemokines related to CXC and CC receptor groups and released from platelets, leukocytes and endothelial cells, SDF-1, TARC and MDC have been found to be platelet agonists. Platelets do not contain SDF-1,. In contrast, RANTES is constitutively present in platelet ,-granules and released upon platelet activation. Objectives:,To study a possible role of RANTES as a modulator of SDF-1, effect on platelets, in relation to CXCR4 and various CC receptors. Methods:,CXCR-4 (CXCL12) receptor expression and platelet activation were evaluated by flow cytometry, platelet deposition was studied by cone and plate(let) analyzer, and platelet aggregation by turbidometric aggregometry. Results:,Flow cytometry studies revealed similar expression of CXCR-4, the specific receptor of SDF-1, on intact, inactivated, and activated platelets. Preincubation of platelets with RANTES affected neither CXCR-4 expression, nor SDF-1, binding to the platelet membrane. In the presence of fibrinogen, SDF-1, activated gel-filtered platelets. RANTES did not activate platelets, but substantially (by 70%) inhibited SDF-1,-induced fibrinogen binding. Similarly, RANTES abrogated the promoting effect of SDF-1, on whole blood platelet adhesion to endothelial cell monolayer under venous flow conditions. In platelet-rich plasma, RANTES moderately inhibited SDF-1,-induced platelet aggregation, while it did not affect aggregation induced by thrombin-receptor activation peptide, adenosine diphosphate, or phorbol 12-myristate 13-acetate. A synergistic inhibitory effect of RANTES and prostaglandin E1 used at subthreshold concentrations, on SDF-1,-induced aggregation and SDF-1,-induced fibrinogen binding to platelets was observed, which may suggest involvement of RANTES in a cAMP-dependent signal transduction pathway. Conclusions:,RANTES non-competitively inhibits activation of platelets by SDF-1,, and thus may play a regulatory role in platelet response to inflammation. [source] Inhibition of human platelet aggregation by a novel S-nitrosothiol is abolished by haemoglobin and red blood cells in vitro: implications for anti-thrombotic therapyBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2000Ian L Megson S-Nitrosothiols are nitric oxide (NO) donor drugs that have been shown to inhibit platelet aggregation in platelet rich plasma (PRP) in vitro and to inhibit platelet activation in vivo. The aim of this study was to compare the platelet effects of a novel S-nitrosated glyco-amino acid, RIG200, with an established S-nitrosothiol, S-nitrosoglutathione (GSNO) in PRP, and to investigate the effects of cell-free haemoglobin and red blood cells on S-nitrosothiol-mediated inhibition of platelet aggregation. The effects of GSNO and RIG200 in collagen (2.5 ,g ml,1)-induced platelet aggregation in PRP and whole blood were investigated in vitro. Both compounds were found to be powerful inhibitors of aggregation in PRP, and RIG200 was significantly more potent (IC50=2.0 ,M for GSNO and 0.8 ,M for RIG200; P=0.04). Neither compound inhibited aggregation in whole blood, even at concentrations of 100 ,M. Red blood cell concentrations as low as 1% of the haematocrit, and cell-free haemoglobin (2.5 ,M), significantly reduced their inhibitory effects on platelets. Experiments involving measurement of cyclic GMP levels, electrochemical detection of NO and electron paramagnetic resonance of haemoglobin in red blood cells, indicated that scavenging of NO generated from S-nitrosothiols by haemoglobin was responsible for the lack of effect of S-nitrosothiols on platelets in whole blood. These studies suggest that scavenging of NO by haemoglobin in blood might limit the therapeutic application of S-nitrosothiols as anti-platelet agents. British Journal of Pharmacology (2000) 131, 1391,1398; doi:10.1038/sj.bjp.0703731 [source] | ||||||||||