thromboxane-b2 and Thrombosis

Acetylsalicylic acid (ASA) is a frequently used antiplatelet agent, although some individuals have reduced antiplatelet responses on ASA, with recurrent ischemic events. It has been proposed that shortening the ASA dosing interval may overcome the time-dependent renewal of the drug target, leading to a greater antiplatelet effect. We conducted a systematic review of randomized controlled trials (RCTs) to determine the efficacy of once- versus twice-daily ASA in conditions with increased platelet turnover.. We conducted a systematic review and meta-analysis by searching the CENTRAL, MEDLINE, and Embase databases for RCTs assessing once- versus twice-daily ASA. Data were screened, extracted, and appraised by two independent reviewers, and were pooled using a random-effects model. The primary outcomes were major adverse cardiovascular events (MACEs) and serum thromboxane B2 (TxB2). Other pharmacodynamic measures were retrieved as secondary outcomes. Results were reported as mean differences with corresponding 95% confidence intervals (CIs). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.. Seven RCTs were included, enrolling 379 participants overall. None of the studies reported clinical outcomes. Pooled results showed that compared with once-daily ASA, twice-daily ASA was associated with a decrease in mean TxB2 of 1.42 ng/mL (95% CI - 2.71 to - 0.13; I. Twice-daily ASA was associated with a greater antiplatelet effect compared with standard once-daily ASA.

Topics: Administration, Oral; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Drug Administration Schedule; Humans; Platelet Aggregation Inhibitors; Randomized Controlled Trials as Topic; Thrombosis; Thromboxane B2

Topics: Adenosine Diphosphate; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Atherosclerosis; Biomarkers; Biotransformation; Blood Coagulation Tests; Blood Platelets; Cardiovascular Diseases; Clopidogrel; Cyclooxygenase 1; Cyclooxygenase Inhibitors; Drug Interactions; Drug Resistance; Hemorrhage; Humans; Platelet Activation; Platelet Aggregation Inhibitors; Platelet Function Tests; Prospective Studies; Randomized Controlled Trials as Topic; Receptors, Purinergic P2; Receptors, Purinergic P2Y1; Receptors, Purinergic P2Y12; Thrombosis; Thromboxane A2; Thromboxane B2; Ticlopidine; Treatment Failure

Aspirin is the mainstay antiplatelet treatment in patients with high risk of cardiovascular atherothrombotic events, and its beneficial effect is documented in several clinical trials. Nevertheless, the effectiveness of aspirin has been questioned by the emergence of the concept of 'aspirin resistance' (AR). This phenomenon, although lacking a precise definition, covers the fact that some patients do not exhibit the expected platelet inhibition by use of various techniques for measuring platelet function. In this critical review, we evaluate the methods used for measuring AR. We will discuss the available data regarding the prevalence and the clinical importance of the phenomenon. Finally, the potential mechanisms underlying AR are considered.

Topics: Aspirin; Atherosclerosis; Cardiovascular Diseases; Drug Resistance; Humans; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Thrombosis; Thromboxane A2; Thromboxane B2

Topics: Asthma; Biomarkers; Cardiovascular Diseases; Humans; Immunoenzyme Techniques; Ischemia; Kidney Failure, Chronic; Radioimmunoassay; Reference Values; Specimen Handling; Thrombosis; Thromboxane A2; Thromboxane B2

Topics: Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Blood Platelets; Clinical Trials as Topic; Drug Interactions; Drug Resistance; Humans; Models, Biological; Risk; Thrombosis; Thromboxane A2; Thromboxane B2; Time Factors

Excessive oxidative stress due to hyperglycemia and glycoxidation leads to an increased production of F2-isoprostanes, one of which, 8-iso-PGF2 alpha, reaches high concentrations in plasma and urine in both insulin-dependent and non-insulin-dependent diabetics. This is associated with an increase in platelet activation, reflected by an increased urinary excretion of platelet-derived TxB2. Improved metabolic control or vitamin E supplementation reduces urinary 8-iso-PGF2 alpha and TxB2, whereas aspirin or indobufen reduces TxB2 but not 8-iso-PGF2 alpha. Since TxB2 in the urine seems to represent the common link between diabetes (as well as other risk factors) and the thrombotic complications of vascular disease, platelet activation due to lipid-glycoxidation is an important aspect in the pathogenesis of vascular complications of diabetes mellitus. Among the various plasma coagulation and fibrinolysis factors that are found to be altered in diabetes, the increased level of plasminogen activator inhibitor (PAI-1) in the plasma and in the vessel wall is of the utmost importance. Indeed, it is suspected that the atherosclerotic plaques formed in the presence of high concentrations of PAI-1 are more prone to rupture and ensuing thrombosis. The thrombosis-oriented modifications of blood platelets, coagulation and fibrinolysis are an important cause behind the high prevalence of vascular events in diabetes.

Topics: Blood Coagulation Factors; Cardiovascular Diseases; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Fibrinolysis; Glycosylation; Humans; Oxidative Stress; Plasminogen Activator Inhibitor 1; Platelet Activation; Risk Factors; Thrombosis; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Circulation; Cerebrovascular Disorders; Coronary Disease; Drugs, Chinese Herbal; Humans; Medicine, Chinese Traditional; Syndrome; Thrombosis; Thromboxane B2

Topics: Aspirin; Humans; Thrombosis; Thromboxane B2

Topics: Animals; Arteries; Arteriosclerosis; Blood Platelets; Hemodynamics; Humans; Platelet Activation; Smoking; Thrombosis; Thromboxane B2

The interaction between blood factors and the vessel wall is important in the development of common cardiovascular diseases. Clinical markers of these interactions should be sought to help in the understanding of the processes involved, and such markers should ideally be available to identify people at risk from the disease, screen relatives, help identify appropriate treatment, and monitor the outcome of the therapy. Various aspects of platelet interaction with the vessel wall can be used, as can some changes in levels of coagulation factors, fibrinolytic proteins, and natural anticoagulants. All have their advantages and disadvantages in terms of having the attributes of the ideal marker that would identify the pathophysiological processes and be reproducible, inexpensive, and easy to perform. This review will consider the value of various clinical markers, taking account of their advantages and disadvantages.

Topics: beta-Thromboglobulin; Blood Coagulation Factors; Blood Platelets; Coronary Disease; Coronary Thrombosis; Fibrinolysin; Fibrinolysis; Fibrinopeptide A; Humans; Muscle, Smooth, Vascular; Plasminogen; Platelet Aggregation; Platelet Factor 4; Thrombosis; Thromboxane B2

Thromboxane A2, the predominant cyclooxygenase product in platelets, is a potent platelet agonist and vasoconstrictor in vitro. Prostacyclin, the major product of vascular endothelium, has opposite effects on platelet function and vascular tone. These properties prompted the hypothesis that a "balance" between these compounds regulated interactions between platelets and the vessel wall in vivo. Although this possibility has been addressed extensively through experiments in vitro, clinical investigations commonly have been confounded by problems with analytic methodology, by selection of inappropriate metabolic targets for analysis, and by artifacts of trial design. The most reliable forms of assessing biosynthesis that are currently available still do not provide definitive information as to the tissue of origin of the compound studied and are directed toward stable but biologically inactive metabolites rather than the evanescent primary compounds themselves. Despite these limitations, both biochemical evidence and clinical trials clearly implicate thromboxane A2 as an important mediator of vascular occlusive disease in humans. The role of prostacyclin is much more conjectural. It does not circulate in concentrations sufficient to exert a systemic effect, but it may play a local homeostatic role in the regulation of platelet-vascular interactions. Whether preservation of the capacity to form prostacyclin coincident with inhibition of thromboxane A2 is of functional importance can be addressed only by clinical trials comparing inhibitors of thromboxane synthesis inhibition that are selective with cyclooxygenase inhibitors that also block the biosynthesis of prostacyclin. The recognition that multiple factors have the potential to regulate both platelet and vascular function at their interface renders the concept of a thromboxane A2-prostacyclin "balance" somewhat unlikely. However, both eicosanoids may interact with other factors to determine the development or persistence of vascular occlusion. Inhibition of the synthesis or function of thromboxane A2 remains the predominant mechanism for achieving interference with platelet function in vivo. Accumulating evidence for the efficacy of aspirin in human syndromes of vascular occlusion suggests that the biologic role of these compounds in humans should be pursued.

Topics: Cardiovascular Diseases; Eicosanoic Acids; Epoprostenol; Humans; Thrombosis; Thromboxane A2; Thromboxane B2

Thromboxane has characteristics that signify potential importance in cardiovascular disease states. In models developed for studying thrombotic sudden death, thromboxane appears to be an important mediator. Thus, in arachidonic acid-induced sudden death, agents that either inhibit thromboxane generation or block thromboxane receptor activation prevent the occurrence of thrombotic death. Thromboxane mimetics are also useful in modeling sudden death; when injected i.v., these compounds elicit effects similar to those obtained with arachidonic acid. In this case, however, pretreatment with cyclooxygenase or thromboxane synthetase inhibitors confers no protection, whereas the thromboxane receptor antagonist retains its efficacy. Other factors that affect susceptibility to experimental sudden death include gender, species, and endocrine status. Thrombotic sudden death models have now been used to test, in vivo, the in vitro antiplatelet aggregatory effect of calcium-channel blockers. The data suggest that dihydropyridine agents such as nifedipine and nisoldipine are protective against thrombosis, whereas verapamil may have little such activity. Furthermore, sudden death induced by a variety of thrombotic challenges is prevented by pretreatment with nifedipine. The thrombotic sudden death models currently employed are useful for the in vivo study of the thrombotic process and for the evaluation of agents with potentially thrombotic or antithrombotic properties.

Topics: Angina Pectoris; Animals; Arachidonic Acid; Arachidonic Acids; Calcium Channel Blockers; Castration; Death; Estrogens; Fatty Acids, Monounsaturated; Fatty Acids, Unsaturated; Female; Glucocorticoids; Humans; Male; Methacrylates; Prostaglandin Endoperoxides, Synthetic; Sex Factors; Testosterone; Thrombosis; Thromboxane A2; Thromboxane B2; Thromboxanes

Topics: Animals; Blood Platelets; Blood Vessels; Dietary Fats; Eicosanoic Acids; Endothelium; Fatty Acids, Unsaturated; Humans; Lipid Metabolism; Lipoproteins; Phospholipids; Platelet Aggregation; Prostaglandins E; Prostaglandins F; Thrombosis; Thromboxane B2

Once-daily (od), low-dose aspirin (75-100 mg) is recommended to reduce the thrombotic risk of patients with essential thrombocytemia (ET). This practice is based on data extrapolated from other high-risk patients and an aspirin trial in polycythemia vera, with the assumption of similar aspirin pharmacodynamics in the two settings. However, the pharmacodynamics of low-dose aspirin is impaired in ET, reflecting accelerated renewal of platelet cyclooxygenase (COX)-1. ARES is a parallel-arm, placebo-controlled, randomized, dose-finding, phase II trial enrolling 300 ET patients to address two main questions. First, whether twice or three times 100 mg aspirin daily dosing is superior to the standard od regimen in inhibiting platelet thromboxane (TX)A

Topics: Aspirin; Biomarkers; Clinical Protocols; Disease Management; Female; Humans; Male; Patient Selection; Platelet Aggregation Inhibitors; Research Design; Thrombocythemia, Essential; Thrombosis; Thromboxane B2

Current guidelines recommend acetylsalicylic acid (ASA) treatment after coronary artery bypass grafting (CABG) to reduce thrombotic vein graft occlusion. The optimal dosage of ASA is not known.. Forty-two patients undergoing elective CABG were randomized to receive either ASA 75mg or 160mg once daily (OD) or 75mg twice daily (BID) after the operation. Platelet function testing was performed before, and one and three months after the operation.. White blood cell counts increased during the initial postoperative days whereas platelet counts were initially slightly reduced after the operation but increased after one month without any major changes of mean platelet volumes. Serum thromboxane B. Less effective inhibition of platelet activation was obtained with ASA 75mg OD than with ASA 160mg OD or 75mg BID up to three months after CABG. Especially the latter dose is of interest for further studies of efficacy and clinical outcomes after CABG.

Topics: Aged; Aspirin; Blood Platelets; Coronary Artery Bypass; Female; Humans; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Prospective Studies; Thrombosis; Thromboxane B2

Angiotensin type 1 receptor (AT 1 R) antagonists are extensively used for blood pressure control in elderly patients with hypertension. This study aimed to investigate the inhibitory effects of AT 1 R antagonist valsartan on platelet aggregation and the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.. Two-hundred and ten patients with hypertension and aged > 60 years were randomized to valsartan (n = 140) or amlodipine (n = 70) on admission. The primary endpoint was platelet aggregation rate (PAR) induced by arachidonic acid at discharge, and the secondary endpoint was the rate of thrombotic events including brain infarction and myocardial infarction during follow-up. Human aortic endothelial cells (HAECs) were stimulated by angiotensin II (Ang II, 100 nmol/L) with or without pretreatment of valsartan (100 nmol/L), and relative expression of cyclooxygenase-2 (COX-2) and thromboxane B 2 (TXB 2 ) and both p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-kB (NF-kB) activities were assessed. Statistical analyses were performed by GraphPad Prism 5.0 software (GraphPad Software, Inc., California, USA).. PAR was lower after treatment with valsartan (11.49 ± 0.69% vs. 18.71 ± 2.47%, P < 0.001), associated with more reduced plasma levels of COX-2 (76.94 ± 7.07 U/L vs. 116.4 ± 15.89 U/L, P < 0.001) and TXB 2 (1667 ± 56.50 pg/ml vs. 2207 ± 180.20 pg/ml) (all P < 0.001). Plasma COX-2 and TXB 2 levels correlated significantly with PAR in overall patients (r = 0.109, P < 0.001). During follow-up (median, 18 months), there was a significantly lower thrombotic event rate in patients treated with valsartan (14.3% vs. 32.8%, P = 0.002). Relative expression of COX-2 and secretion of TXB 2 with concordant phosphorylation of p38MAPK and NF-kB were increased in HAECs when stimulated by Ang II (100 nmol/L) but were significantly decreased by valsartan pretreatment (100 nmol/L).. AT 1 R antagonist valsartan decreases platelet activity by attenuating COX-2/TXA 2 expression through p38MAPK and NF-kB pathways and reduces the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.

Topics: Aged; Aged, 80 and over; Angiotensin Receptor Antagonists; Blood Platelets; Blotting, Western; Cell Line; Cyclooxygenase 2; Female; Humans; Hypertension; Male; Platelet Aggregation; Real-Time Polymerase Chain Reaction; Tetrazoles; Thrombosis; Thromboxane B2; Valine; Valsartan

Effects of high-protein diets that are rich in saturated fats on cell adhesion molecules, thrombogenicity and other nonlipid markers of atherosclerosis in humans have not been firmly established. We aim to investigate the effects of high-protein Malaysian diets prepared separately with virgin olive oil (OO), palm olein (PO) and coconut oil (CO) on cell adhesion molecules, lipid inflammatory mediators and thromobogenicity indices in healthy adults.. A randomized cross-over intervention with three dietary sequences, using virgin OO, PO and CO as test fats, was carried out for 5 weeks on each group consisting of 45 men and women. These test fats were incorporated separately at two-thirds of 30% fat calories into high-protein Malaysian diets.. For fasting and nonfasting blood samples, no significant differences were observed on the effects of the three test-fat diets on thrombaxane B2 (TXB2), TXB2/PGF1α ratios and soluble intracellular and vascular cell adhesion molecules. The OO diet induced significantly lower (P<0.05) plasma leukotriene B4 (LTB4) compared with the other two test diets, whereas PGF1α concentrations were significantly higher (P<0.05) at the end of the PO diet compared with the OO diet.. Diets rich in saturated fatty acids from either PO or CO and high in monounsaturated oleic acid from virgin OO do not alter the thrombogenicity indices-cellular adhesion molecules, thromboxane B2 (TXB2) and TXB2/prostacyclin (PGF1α) ratios. However, the OO diet lowered plasma proinflammatory LTB4, whereas the PO diet raised the antiaggregatory plasma PGF1α in healthy Malaysian adults. This trial was registered at clinicaltrials.gov as NCT 00941837.

Topics: Adult; Algorithms; Arecaceae; Biomarkers; Cell Adhesion Molecules; Coconut Oil; Cross-Over Studies; Diet, High-Fat; Dietary Fats, Unsaturated; Female; Humans; Leukotriene B4; Malaysia; Male; Middle Aged; Olive Oil; Plant Oils; Prostaglandins F; Risk; Thrombosis; Thromboxane B2; Triolein; Young Adult

Microvascular obstruction seems to predict poor outcome in patients undergoing elective percutaneous coronary intervention (PCI), but the underlying mechanism is still unclear. We analyzed whether serum thromboxane B2, a stable metabolite of thromboxane A2, may be implicated in post-PCI microvascular obstruction.. We enrolled 91 patients (74 males, 66±10 years) on chronic low-dose aspirin therapy (aspirin, 100 mg daily) scheduled for elective PCI and randomly assigned to receive aspirin reload (325 mg orally, n=46) or no reload (control group, n=45) ≥1 hour before elective PCI. Serum levels of thromboxane B2, reperfusion indexes (corrected Thrombolysis In Myocardial Infarction frame count and myocardial blush grade), and serum cardiac troponin I were assessed before and after PCI. Serum thromboxane B2 significantly increased after 120 minutes (P=0.0447) from PCI in control but not in aspirin reload group. After PCI, both groups showed a statistically significant reduction in corrected Thrombolysis In Myocardial Infarction frame count more evident in aspirin reload group (P=0.0023). Moreover, after PCI, 61% of patients allocated to aspirin reload and only 32% of patients allocated to control group reached normal microcirculatory reperfusion (myocardial blush grade=3); patients with myocardial blush grade=3 exhibited lower values of serum thromboxane B2 compared with those with myocardial blush grade <3 (P=0.05). Periprocedural cardiac troponin I significantly increased (F=3.64; P=0.01334) and correlated with serum thromboxane B2 (ρ=0.31; P=0.0413) in control but not in aspirin reload group. In addition, left ventricular ejection fraction significantly increased after PCI only in the aspirin reload group (P=0.0005).. Aspirin loading dose before elective PCI improves myocardial reperfusion and injury indexes, suggesting a possible role of platelet thromboxane A2 in microvascular occlusion.. http://www.clinicaltrials.gov. Unique identifier: NCT01374698.

Topics: Aged; Aspirin; Female; Humans; Male; Microvessels; Middle Aged; Myocardial Reperfusion Injury; Percutaneous Coronary Intervention; Postoperative Complications; Preoperative Period; Thrombosis; Thromboxane B2; Treatment Outcome; Troponin I

Aspirin's therapeutic action is via inhibition of platelet cyclooxygenase 1 (COX-1) thromboxane A2 (TxA2) production. The aim of this study was to evaluate TxA2 production, in the absence of platelet COX-1 activity, in coronary atherosclerotic heart disease patients with and without atherothrombotic myocardial infarction (MI).. TxA2 production, in the absence of platelet COX-1 activity, was evaluated in 44 patients taking aspirin on 3 commercially available assays that detect metabolites of TxA2 in the urine. Two assays measure urine 11-dehydro-thromboxane B2 (TxB2) alone and 1 measures urine 11-dehydro-TxB2 plus 11-dehydro-2,3-dinor-TxB2. Platelet COX-1 inhibition was confirmed on <10% platelet aggregation in response to ≥1 mmol/L arachidonic acid. Median urine 11-dehydro-TxB2 was no different in those with and without a diagnosis of atherothrombotic MI (325 vs. 311 pg/mg creatinine, P=0.59 via polyclonal ELISA) and (312 vs. 244 pg/mg creatinine, P=0.11 via LC-MS/MS). Median urine 11-dehydro-TxB2 plus 11-dehydro-2,3-dinor-TxB2, however, was higher in those with vs. those without a diagnosis of atherothrombotic MI (1,035 vs. 606 pg/mg creatinine, P=0.03 via monoclonal ELISA).. Differences in TxA2 production, in the absence of platelet COX-1 activity, between those with vs. without atherothrombotic MI were not observed when TxA2 generation was assessed on 11-dehydro-TxB2 production alone (polyclonal ELISA or LC-MS/MS), but differences were observed when TxA2 generation was assessed using 11-dehydro-TxB2 plus 11-dehydro-2,3-dinor-TxB2 (monoclonal ELISA). These findings highlight important differences between different commercially available assays for TxA2 generation and suggest that 11-dehydro-2,3-dinor-TxB2 may be critical to the biology of atherothrombosis.

Topics: Aged; Aspirin; Blood Platelets; Coronary Artery Disease; Creatinine; Cyclooxygenase 1; Cyclooxygenase Inhibitors; Female; Humans; Male; Middle Aged; Myocardial Infarction; Platelet Aggregation; Thrombosis; Thromboxane A2; Thromboxane B2

To test the hypothesis that selective inhibition of cyclooxygenase (COX)-2 would result in exercise-induced platelet activation by causing a shift in the endogenous thromboxane (TX)/prostacyclin balance, a double blind, randomized study comparing aspirin (300 mg/d) with rofecoxib (25 mg/d) (cross-over design, 14 days washout between treatments) in n = 10 trained healthy volunteers was carried out. Physical exercise resulted only in a minor platelet activation, as reflected by the expression of basal or ADP-stimulated platelet activation markers or basal plasma concentrations of TXB(2). Aspirin significantly reduced TXB(2) in plasma while rofecoxib significantly increased TXB(2) in urine. Although no increase in systemic prostacyclin concentration was observed, there was a significant exercise-related increase in both platelet cAMP and cGMP without any drug-related effects. It is concluded that, in trained healthy volunteers, selective inhibition of COX-1 (aspirin) or COX-2 (rofecoxib) does not affect systemic prostacyclin synthesis after physical exercise. However, our data do not exclude the possibility that in subjects at risk for atherothrombotic complications (e.g. patients with advanced atherosclerotic disease) COX-2 inhibitors may result in platelet activation by inhibiting endothelial prostacyclin formation.

Topics: Adenosine Diphosphate; Adult; Aspirin; Atherosclerosis; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Double-Blind Method; Endothelium; Epoprostenol; Exercise; Humans; Isoenzymes; Lactones; Male; Platelet Activation; Rest; Risk Factors; Sulfones; Thrombosis; Thromboxane B2

This trial evaluated the effect of antioxidant supplementation on the urinary excretion of 11-dehydro TXB(2)/2,3 dinor 6 keto PGF(1alpha) ratio, a marker of the pathogenesis of thrombosis and arteriosclerosis.. This study was a randomised, double-blind, placebo-controlled trial involving 186 presumably healthy volunteers. One hundred received a multi-antioxidant supplementation and 86 a placebo for two years. Blood zinc, selenium, beta-carotene, vitamin C and E and urinary excretion of 11-dehydro TXB(2) and 2,3 dinor 6 keto PGF(1alpha) were measured.. Baseline subject characteristics did not differ between the two groups. Blood zinc, selenium, and beta-carotene concentrations significantly increased between baseline and two years in the multi-antioxidant supplementation group supporting subject compliance (p < 0.05). At two years, the median urinary 11-dehydro TXB(2)/2,3 dinor 6 keto PGF(1alpha) ratio was significantly lower in the multi-antioxidant supplementation group (3.4 versus 2.78, p = 0.015). Serum selenium concentration was the only antioxidant studied that was significantly related to the urinary 11-dehydro TXB(2)/2,3 dinor 6 keto PGF(1alpha) ratio.. These results support the hypothesis that a low-dose multi-antioxidant supplementation may contributes to a reduction in platelet activation which is beneficial for cardiovascular function.

Topics: 6-Ketoprostaglandin F1 alpha; Antioxidants; Arteriosclerosis; beta Carotene; Biomarkers; Dietary Supplements; Dose-Response Relationship, Drug; Double-Blind Method; Female; Humans; Male; Middle Aged; Patient Compliance; Platelet Activation; Prostaglandins I; Selenium; Thrombosis; Thromboxane B2; Thromboxanes; Trace Elements; Vitamins; Zinc

To investigate the effect of dietary saturated fat (SFA) from animal sources on the urine excretion 11-dehydro thromboxane B2 (TXB2) and 6-keto prostaglandin F 1alpha (PGF 1alpha) in 27 healthy free-living male subjects aged 30 to 55 years.. It was a randomized crossover design. Each volunteer was randomly assigned to one of the two diets (high fat and low fat) for a period of 4 weeks, after which each subject resumed his usual diet for 2 weeks as a 'wash-out period', before being assigned to the other diet for an additional 4 weeks.. Serum proportion of 20:4n-6 was 5% lower in the high fat (6.2% of total fatty acid) than in the low fat diet (6.5% of total fatty acid), which was associated with a significantly decreased ratio of the urinary excretion 11-dehydro TXB2 to 6-keto PGF 1alpha (P < 0.05). However, there was no significant fall in the absolute urinary excretion of 11-dehydro TXB2.. Diet rich in SFA from animal sources may influence TXA2 formation via effect on tissue proportion of 20:4n-6.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Arteriosclerosis; Cross-Over Studies; Dietary Fats; Fatty Acids; Humans; Male; Middle Aged; Thrombosis; Thromboxane B2

The pathogenesis of antiphospholipid antibody (aPL) related thrombosis is multifactorial and includes, amongst others, enhanced coagulation activation measured as prothrombin fragment 1 + 2 (F1 + 2), elevated plasma levels of von Willebrand factor (vWF), plasminogen activator inhibitor (PAI) and endothelin-1 (ET-1) as well as heightened thromboxane generation and lipid peroxidation. To evaluate the antioxidant susceptibility of some of the above pathways, probucol (500 mg/d orally, a cholesterol lowering agent bearing antioxidant properties) was administered for a three week period to 14 subjects with aPL and to seven healthy controls. At baseline aPL participants showed higher plasma levels of vWF (P = 0.006), ET-1 (P = 0.0002) and enhanced urinary excretion of 11-dehydro-thromboxane-B2 (TXB2) (P = 0.0004), F2-isoprostanes (marker of lipid peroxidation) (P = 0.02) and albumin (P = 0.04) than controls. In the aPL group baseline IgG anticardiolipin (aCL) titre positively related with urinary TXB2 (r2 = 0.43, P = 0.01) and inversely with urinary NOx (r2 = -0.6, P = 0.005) whereas urinary NOx and TXB2 were negatively correlated (r2 = -0.42, P = 0.01). After the treatment period significant decreases from baseline values were noted for PAI (P = 0.01), ET-1 (P = 0.006), TXB2 (P = 0.02), F2-isoprostanes (P = 0.01) and albuminuria (P = 0.01) in aPL participants but not in controls. These pilot data support oxidative sensitive mechanisms and a potential role for antioxidant treatment in the pathogenesis of aPL induced vasculopathy.

Topics: Adult; Albuminuria; Antibodies, Antiphospholipid; Anticholesteremic Agents; Anticoagulants; Antioxidants; Antiphospholipid Syndrome; Arachidonic Acids; Creatinine; Endothelin-1; Female; Humans; Lipids; Male; Middle Aged; Nitric Oxide; Pilot Projects; Probucol; Prothrombin; Thrombosis; Thromboxane B2; von Willebrand Factor; Warfarin

The interaction between smoking and oral contraceptive (OC) use with respect to thrombogenesis was investigated by studying the effects of OC and smoking on urinary prostacyclin (PGI2) and thromboxane A2 (TxA2) metabolite levels in smokers and nonsmokers. Sixty healthy women, aged 19-32 years, who were not taking any hormonal treatment for at least 3 months before initiating the study, were divided into three equal groups: OC users who smoked (N = 20), OC users who did not smoke (N = 20), and a control group of 10 smokers and 10 nonsmokers. Each OC treatment group was randomized to receive either norethindrone (NET) acetate (1 mg)/ethinyl estradiol (EE2) (35 micrograms) (N = 10) or NET acetate (1 mg)/EE2 (20 micrograms) (N = 10) daily for 3 months. Overnight urine collections and fasting blood samples were obtained at baseline and at the end of the 3-month study. Serum levels of NET and EE2, as well as urinary levels of cotinine and the stable metabolites of PGI2 and TxA2, namely 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane (TxB2), respectively, were measured by specific immunoassays. Analysis of pre- to posttreatment changes in mean urinary 6-keto-PGF1 alpha and TxB2 levels for each subgroup, as determined by smoking status and EE2 dose, showed no statistically significant differences. Also, no significant differences were found in each subgroup with respect to changes in the 6-keto-PGF1 alpha/TxB2 ratios. Large intersubject variability in urinary 6-keto-PGF1 alpha and TxB2 levels were observed in all subgroups. The results of this study indicate that both low-estrogen-dose compounds, when used by smokers or nonsmokers, did not significantly alter the ratio of PGI2 to TXA2 metabolites, compared with pretreatment. However, the small number of subjects and the large intersubject variability in this study make it difficult to determine if there is a significant difference between the 20- and 30-microgram EE2 doses.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Chromatography, High Pressure Liquid; Contraceptives, Oral, Synthetic; Cotinine; Creatinine; Estradiol Congeners; Ethinyl Estradiol; Female; Humans; Immunoenzyme Techniques; Norethindrone; Smoking; Thrombosis; Thromboxane B2

Intravenous acetylsalicylic acid (ASA) and magnesium (Mg) both possess antiplatelet properties and are thus potential inhibitors of the formation of arterial thrombi. Their effect on the dynamic aspects of arterial thrombus formation was investigated following intravenous administration of both substances alone and in combination. A blinded, placebo-controlled, in-vivo study was performed in 71 rats. Thrombus formation was induced by a standardized arteriotomy in the right femoral artery with inversion of the vessel wall during subsequent closure. Thrombus formation was recorded on video tapes and analysed off-line for 30 min. Animals were randomly assigned to one of four groups: 20 mg bolus of ASA followed by 0.3 mmol/h Mg (ASA/Mg group); NaCl followed by 0.3 mmol/h Mg (Mg group); 20 mg bolus of ASA followed by NaCl (ASA group); or NaCl throughout the experiment (control group). In the ASA-treated groups, serum levels of thromboxane B2 were reduced significantly, and the Mg-treated groups reached a serum level of Mg just above 2.0 mmol/l. No significant differences were observed in initial or maximum thrombus area or in mean thrombus area during the study period. In the ASA/Mg group, a trend towards reduced thrombus formation was observed (P = 0.06). In the same group, seven of 22 animals developed an occlusive thrombus (P < 0.01), an unexpected adverse event possibly related to the combined administration of ASA and Mg.

Topics: Animals; Arteriosclerosis; Aspirin; Blood Pressure; Double-Blind Method; Hemorrhage; Magnesium; Male; Rats; Rats, Wistar; Single-Blind Method; Thrombosis; Thromboxane B2

Experimental data suggest that formation of thromboxane A2 may be suppressed during administration of a glycoprotein IIb/IIIa antagonist. We determined the dose of one such compound, fradafiban, required to provide > 80% occupancy of the platelet glycoprotein IIb/IIIa and examined its effects on thromboxane A2 formation in patients undergoing PTCA. The dose response to fradafiban and additional effects of aspirin were explored initially in patients with stable coronary artery disease. Fradafiban induced a dose-dependent inhibition of platelet aggregation that correlated with fibrinogen receptor occupancy and plasma drug concentration. Addition of aspirin 300 mg had no effect on these parameters. At the highest dose, mean fibrinogen receptor occupancy was 89.7 +/- 1.2% (n = 3) at 4 hours and platelet aggregation had decreased by 93.4 +/- 2.7%. Eighteen patients undergoing coronary angioplasty were randomized to receive either aspirin 330 mg or that dose of fradafiban producing > 80% fibrinogen receptor occupancy. Platelet aggregation was suppressed throughout the infusion of fradafiban to a greater extent than with aspirin. However, there was a marked increase in urinary excretion of 11-dehydrothromboxane B2 in patients treated with fradafiban: from 1973 +/- 889 to a peak of 9760 +/- 3509 pg/mg creatinine (P = .0046). Despite this evidence of continued platelet activation in vivo, there were no cases of coronary thrombosis. In conclusion, fradafiban suppresses platelet aggregation and may be a useful alternative to aspirin in the prevention of thrombotic events in patients undergoing PTCA. However, there is continued formation of thromboxane A2, which may continue to exert its effects as a potent vasoconstrictor and vascular smooth muscle mitogen.

Topics: Administration, Oral; Angioplasty, Balloon, Coronary; Anticoagulants; Aspirin; Biphenyl Compounds; Bleeding Time; Cell Division; Coronary Disease; Dose-Response Relationship, Drug; Double-Blind Method; Drug Therapy, Combination; Female; Fibrinogen; Heparin; Humans; Infusions, Intravenous; Male; Middle Aged; Muscle, Smooth, Vascular; P-Selectin; Pilot Projects; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Pyrrolidines; Thrombosis; Thromboxane A2; Thromboxane B2; Vasoconstriction

Our purpose was to investigate the effects of hormone replacement therapy on the reactivity of monocytes and platelets in whole blood, measured by tissue factor activity, tumor necrosis factor-alpha, and thromboxane B2.. Thirty-two women were randomized into either transdermal or oral combined hormone replacement therapy and underwent blood sampling before and after 3 and 12 months of treatment. The tissue factor activity in monocytes was measured both in unstimulated whole blood and after a weak lipopolysaccharide stimulation. Tumor necrosis factor-alpha and thromboxane B2 formation in plasma were measured after a weak lipopolysaccharide stimulation of whole blood.. After 12 months of hormone replacement therapy there were significant reductions of tissue factor activity in both unstimulated and lipopolysaccharide-stimulated monocytes (p < 0.001) and significant reductions in the formation of tumor necrosis factor-alpha (p < 0.03) and thromboxane B2 (p < 0.02). There were no differences in these parameters between the transdermal and the oral groups. No changes were observed after 3 months of therapy.. Twelve months of hormone replacement therapy reduces cellular activation of blood monocytes and platelets; these changes may account for some of the beneficial effects in reducing the risk of cardiovascular disease.

Topics: Administration, Cutaneous; Administration, Oral; Adult; Arteriosclerosis; Blood Platelets; Estradiol; Estrogen Replacement Therapy; Female; Humans; Medroxyprogesterone; Middle Aged; Monocytes; Norethindrone; Thromboplastin; Thrombosis; Thromboxane B2; Tumor Necrosis Factor-alpha

We carried out a pilot study in 15 hemodialysis patients with recurrent vascular access thrombosis to examine whether the combination of low dose aspirin (85 mg once daily) and sulfinpyrazone (200 mg three times daily) is safe and effective in the prevention of vascular access thrombosis. Hemostatic measurements were performed prior to and after four weeks of starting the drug combination. Baseline values for fibrinopeptide A were elevated in all patients while those for platelet factor 4, fibrinogen, antithrombin III and protein C were generally within normal limits. A major reduction in the frequency of vascular access thrombosis from 0.114 per month to 0.04 per month was noted during combined drug treatment (p less than 0.001). Although in vitro platelet aggregation to various stimuli was markedly suppressed and platelet thromboxane B2 formation was almost completely inhibited in patients on aspirin/sulfinpyrazone, this was not associated with a significant further prolongation of the bleeding time. A relatively high rate of complications, particularly mild gastrointestinal bleeding, was noted in patients on aspirin/sulfinpyrazone that could not be predicted on the basis of pre-treatment hemostatic test results.

Topics: Aspirin; Blood Coagulation Tests; Blood Platelets; Catheters, Indwelling; Drug Evaluation; Drug Therapy, Combination; Gastrointestinal Hemorrhage; Humans; Pilot Projects; Platelet Aggregation; Platelet Aggregation Inhibitors; Recurrence; Renal Dialysis; Sulfinpyrazone; Thrombosis; Thromboxane B2

Topics: Adult; Aged; Biocompatible Materials; Humans; Kidneys, Artificial; Membranes, Artificial; Middle Aged; Thrombosis; Thromboxane B2

Enteric coated aspirin was given to eight human volunteers in escalating doses (20, 40, 60, 80, 100 mg daily), each dose being given over two weeks. In addition, to measure the maximum effect of aspirin, each volunteer was given two single doses of 600 mg of soluble aspirin. At the end of each dosing interval we measured platelet aggregation and thromboxane formation in response to four aggregating agents and to whole blood coagulation. The doses of aspirin required to inhibit platelet aggregation in response to various stimuli were: for collagen 60-80 mg, for adenosine diphosphate and adrenaline 60 mg, and for arachidonate 40 mg. For maximum inhibition of thromboxane formation the doses were: for collagen greater than 100 mg, for adenosine diphosphate and adrenaline 60 mg, for arachidonate 80 mg, and for whole blood coagulation 100 mg. Different aspirin doses are required to inhibit the responses to different stimuli. Furthermore, for some stimuli, inhibition of thromboxane generation may require more aspirin than is required for inhibition of aggregation. The clinical implications of these findings are uncertain since we do not know which stimuli are important in arterial thrombosis in man.

Topics: Adult; Aspirin; Dose-Response Relationship, Drug; Female; Humans; Male; Platelet Aggregation; Thrombosis; Thromboxane A2; Thromboxane B2

In a double-blind placebo-controlled crossover study, we investigated in seven healthy male volunteers the effect of a low-dose aspirin regimen (35 mg acetylsalicylate per day for 7 days) on the formation of thromboxane A2 (TxA2) and prostacyclin (PGI2) in blood emerging from a standardized injury of the microvasculature made to determine skin bleeding time. When subjects were treated with placebo, there was rapid and substantial generation of TxA2 and PGI2 at the site of platelet-vessel wall interaction within the first 2 min after vascular injury. This was reflected by a greater than 100-fold and greater than 10-fold increase in thromboxane B2 (TxB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in blood obtained from incisions made to determine bleeding time as compared with the corresponding plasma values. Low-dose aspirin caused a significant inhibition of both TxA2 and PGI2 generation in blood sampled from the skin incisions, represented by a 85% and 92% and 81% and 84% inhibition of TxB2 and 6-keto-PGF1 alpha, respectively, as compared with controls. We therefore conclude that rapid activation of both platelet prostaglandin metabolism and vascular PGI2 biosynthesis occurs at the site of platelet-vessel wall interaction, and low-dose aspirin results in a significant inhibition of both platelet and vascular cyclooxygenase activity. Thus, our data fail to confirm the concept of a differential effect of low-dose aspirin on platelet and vascular prostaglandin synthesis in man in vivo.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aspirin; Bleeding Time; Blood Platelets; Blood Vessels; Double-Blind Method; Epoprostenol; Hemostasis; Humans; Male; Thrombosis; Thromboxane A2; Thromboxane B2

The present study, using patients with Takayasu's disease (pulseless disease), characterized by segmentally affected arterial lesions and stenotic conditions with a nonspecific inflammatory morbid condition, was designed to assess whether or not a low dose of aspirin can practically exert its preventive effect against the aggregation of platelets that have just passed along a rough-surfaced arterial wall. Twenty Japanese women with Takayasu's disease were selected under the following criteria: A unilateral upper extremity was angiographically confirmed to be affected with the disease, while the contralateral limb was almost normal. Systolic blood pressure on the affected side was almost half that on the nonaffected side. The patients showed neither a positive CRP nor an accentuated ESR. In these patients, mean plasma levels of TXB2 and 3 microM ADP-induced platelet aggregation in blood obtained from the affected side were 156.5 +/- 17.7 pg/ml, and 59.5 +/- 6.0%, respectively, which were significantly high as compared with 104.5 +/- 17.6 and 41.7 +/- 8.8%, respectively, in samples from the nonaffected side. Forty and eighty mg of aspirin per day administered to two randomly composed groups, respectively, showed an improvement in platelet aggregability and TXB2 levels on the nonaffected side. In the affected limbs, though 80 mg/day led to significant decreases in TXB2 levels (108.0 +/- 7.8 pg/ml, p less than 0.05) and platelet aggregability (21.3 +/- 7.6%), the 40-mg regimen showed no significant reductions (134.6 +/- 9.4 pg/ml, 35.6 +/- 17.1%). Plasma levels of 6-keto PGF1 alpha revealed no differences between 40- and 80-mg regimens, or between before and after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aortic Arch Syndromes; Arm; Aspirin; Clinical Trials as Topic; Female; Humans; Platelet Aggregation; Random Allocation; Takayasu Arteritis; Thrombosis; Thromboxane B2

Evidence for aspirin efficacy testing in pediatrics is limited, especially outside of cardiology, yet thrombotic events have high morbidity in other areas such as pediatric transplant surgery. Debates about whether thromboembolic events while on aspirin represent "aspirin resistance" or "high on-treatment platelet reactivity" persist, given the poor intertest agreement between testing platforms.. This prospective observational study involved measuring aspirin efficacy using ex vivo testing of platelet aggregation (VerifyNow-Aspirin, VN) and urine 11-dehydrothromboxane B2 (AsprinWorks, UTxB2) contemporaneously at up to three time points after major noncardiac organ transplant surgery. The collection days (CD) were the second and seventh days after stable aspirin dosing and then a convalescent time point 2-9 months later.. Fifty-five participants (age range, 0-21 years) were enrolled, having undergone total pancreatectomy with islet autotransplantation (N = 36), orthotopic liver transplantation (N = 18), and combined liver-kidney transplantation (N = 1). Platelet reactivity measured by VN remained unchanged, whereas UTxB2, which was elevated postoperatively, decreased significantly from CD1 to CD2 and CD3. Discordance in therapeutic efficacy was noted per manufacturer cutoffs, with therapeutic VN results in 86% of tests, whereas 12% of UTxB2 were therapeutic. Age-based stratification of UTxB2 results using previously published pediatric median levels increased overall UTxB2 therapeutic rates (80%) and intertest concordance (67% vs 27% if using adult range). No thrombotic events were observed.. Our data suggest that urine thromboxane production may be an underappreciated reflection of postoperative inflammation. Validation of pediatric normal ranges for UTxB2 is a critical next step.

Topics: Adolescent; Adult; Aspirin; Blood Platelets; Child; Child, Preschool; Humans; Infant; Infant, Newborn; Inflammation; Organ Transplantation; Pediatrics; Platelet Aggregation; Platelet Aggregation Inhibitors; Thrombosis; Thromboxane B2; Young Adult

Topics: Aged; Biomarkers; CD40 Antigens; Coronavirus Infections; COVID-19; Female; Hemoglobins; Humans; Lymphocyte Count; Male; Mean Platelet Volume; Middle Aged; P-Selectin; Pandemics; Platelet Count; Pneumonia, Viral; Thrombosis; Thromboxane B2

To explore the anti-platelet aggregation and anti-thrombotic mechanisms of Trichosanthis Fructus combined with aspirin based on network pharmacology and the validation of arteriovenous by pass model in rats. The databases of Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP),Drug Repositioning and Adverse Drug Reaction Chemical-Protein Interactome(DRAR-CPI),Universal Protein Resource(Uniprot) and the Database for Annotation,Visualization,and Integrated Discovery(DAVID) were used to predict protein targets and analyze biological pathway and signal pathway in the combination of Trichosanthis Fructus with aspirin. The effects of pretreatment with Trichosanthis Fructus pellets,aspirin pellets and their combination on thromboxane B2(TXB2),6-keto prostaglandin F1α(6-keto-PGF1α) and cyclic adenosine monophosphate(c AMP) in rat thrombotic model were studied. Through the study of network pharmacology,12 components of aspirin and Trichosanthis Fructus,including hydroxygenkwanin,quercetin and adenosine,were found to show the anti-platelet aggregation and anti-thrombosis mechanisms through9 common protein targets,such as SRC,RAC1,MAPK14,MAPK1,AKT1,and 14 common signaling pathways,such as VEGF signaling pathway. After the intervention with Trichosanthis Fructus pellets combined with aspirin pellets,the vascular endothslia growth factor(VEGF) signaling pathway can be activated to inhibit platelet aggregation and improve vascular endothelial function,and show the anti-platelet aggregation and anti-thrombosis mechanisms,which verify the results of the network pharmacology,and explain the anti-platelet aggregation and anti-thrombotic mechanisms of the combination of Trichosanthis Fructus pellets with aspirin pellets.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Cyclic AMP; Drugs, Chinese Herbal; Fruit; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Signal Transduction; Thrombosis; Thromboxane B2; Trichosanthes

Zhi-Xiong Capsules (ZXC) involving Hirudo, Ligusticum chuanxiong, Salvia miltiorrhiza, Leonurus artemisia, and Pueraria lobata, is an empirical prescription used in Chinese clinics applied for treating cerebral arteriosclerosis and blood-stasis in clinic. However, the mechanism of its antithrombotic activity has not been investigated until now. The present study was designed to investigate its antithrombotic effects, the mechanism of ZXC on anti-thrombus action and to identify the main chemical composition of ZXC using HPLC-DAD-ESI-IT-TOF-MS. Two animal models were used to evaluate the antithrombotic effect of ZXC, the arterial thrombosis model and a venous thrombosis model. ZXC prolonged the plasma recalcification time (PRT), the activated partial thromboplastin time (APTT), the thrombin time (TT) and the prothrombin time (PT) and clearly reduced the content of fibrinogen (FIB) obviously in the arterial thrombosis model. Furthermore, it markedly suppressed the level of TXB

Topics: Acute Disease; Animals; Anticoagulants; Antithrombins; Aspirin; Blood Coagulation; Capsules; Carotid Arteries; Chlorides; Disease Models, Animal; Drug Evaluation, Preclinical; Drugs, Chinese Herbal; Ferric Compounds; Fibrinolysis; Heparin; Lung; Mice; Platelet Activation; Platelet Aggregation; Prostaglandins F; Pulmonary Embolism; Rabbits; Rats, Sprague-Dawley; Thrombolytic Therapy; Thrombosis; Thromboxane B2

The compounds of Rubus spp. Blackberry (RSB) were isolated and identified by a bioassay-guided method, and their antithrombotic effects and mechanism were investigated with the acute blood stasis rat model. The RSB extract was evaluated by activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT), and fibrinogen (FIB) assays in vitro. Results indicated that RSB extract exhibited anticoagulant activity. In addition to compounds 1 and 6, the other compounds also exhibited anticoagulant activity in vitro. Therefore, the in vivo antithrombosis effects of RSB extract were investigated by measuring whole blood viscosity (WBV), plasma viscosity (PV), APTT, PT, TT, and FIB. Meanwhile, the levels of thromboxane B2 (TXB

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Coagulation; Female; Fibrinolytic Agents; Humans; Male; Partial Thromboplastin Time; Plant Extracts; Prothrombin Time; Rabbits; Rats; Rats, Sprague-Dawley; Rubus; Thrombin Time; Thrombosis; Thromboxane B2

The compounds of Radix Paeoniae Rubra (RPR) were isolated and identified by bioassay-guided method, and antithrombotic effects and mechanism were investigated by the acute blood stasis rat model. The RPR extract was evaluated by APTT, TT, PT, and FIB assays in vitro. Results indicated that RPR extract exhibited the anticoagulant activity. In order to find active compounds, six compounds were isolated and identified, and four compounds, paeoniflorin (Pae), pentagalloylglucose (Pen), albiflorin (Ali), and protocatechuic acid (Pro), exhibited the anticoagulant activity in vitro. Therefore, the antithrombosis effects of RPR extract and four active compounds were investigated in vivo by measuring whole blood viscosity (WBV), plasma viscosity (PV), APTT, PT, TT, and FIB. Meanwhile, the levels of TXB

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anticoagulants; Biological Assay; Bridged-Ring Compounds; Drugs, Chinese Herbal; Endothelin-1; Female; Fibrinolytic Agents; Glucosides; Hydrolyzable Tannins; Hydroxybenzoates; Male; Monoterpenes; Nitric Oxide Synthase Type III; Paeonia; Phytotherapy; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2; Viscosity

Ferulic acid (FA) produces protective effects against cardiovascular dysfunctions. However, the mechanisms of FA is still not known. Here we examined the antithrombotic effects of FA and its potential mechanisms. Anticoagulation assays and platelet aggregation was evaluated in vitro and in vivo. Thromboxane B2 (TXB2), cyclic adenosine monophosphate(cAMP), and cyclic guanosine monophosphate (cGMP) was determined using enzyme immunoassay kits. Nitric oxide (NO) production was measured using the Griess reaction. Protein expression was detected by Western blotting analysis. Oral administration of FA prevented death caused by pulmonary thrombosis and prolonged the tail bleeding and clotting time in mice,while, it did not alter the coagulation parameters, including the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). In addition, FA (50-200 µM) dose-dependently inhibited platelet aggregation induced by various platelet agonists, including adenosine diphosphate (ADP), thrombin, collagen, arachidonic acid (AA), and U46619. Further, FA attenuated intracellular Ca(2)(+) mobilization and TXB2 production induced by the platelet agonists. FA increased the levels of cAMP and cGMP and phosphorylated vasodilator-stimulated phosphoprotein (VASP) while decreased phospho-MAPK (mitogen-activated protein kinase) and phosphodiesterase (PDE) in washed rat platelets, VASP is a substrate of cyclic nucleotide and PDE is an enzyme family responsible for hydrolysis of cAMP/cGMP. These results suggest that antithrombotic activities of FA may be regulated by inhibition of platelet aggregation, rather than through inhibiting the release of thromboplastin or formation of thrombin. The mechanism of this action may involve activation of cAMP and cGMP signaling.

Topics: Animals; Blood Coagulation; Calcium; Cell Adhesion Molecules; Coumaric Acids; Cyclic AMP; Cyclic GMP; Fibrinolytic Agents; Hemorrhage; Intracellular Space; Male; Mice; Microfilament Proteins; Mitogen-Activated Protein Kinases; Nitric Oxide; Phosphoproteins; Phosphoric Diester Hydrolases; Phosphorylation; Rats; Signal Transduction; Superoxides; Thrombosis; Thromboxane B2

In myeloproliferative neoplasms (MPN), aspirin reduces the thrombotic risk. Nevertheless, aspirin resistance may be due to excessive platelet production ("turnover" resistance). Aspirin resistance can also result from a lack of effect of aspirin; this second component is called "intrinsic resistance". Two biological tests are considered reference methods for the assessment of aspirin resistance: TXB2 assay and Light Transmittance Aggregometry (LTA) with arachidonic acid.. We have compared a third method, the Multiple Electrode Aggregometry (MEA), performed with arachidonic acid on the Multiplate® analyzer, with both reference methods. Thirty-six patients with MPN were assessed for aspirin resistance with all three techniques. 30 patients devoid of MPN were used as controls.. The three methods were statistically equivalent: LTA and TXB2 were comparable methods (ROC curve AUC=0.844>0.7; LTA cutoff=67%). At this threshold, LTA had a sensitivity of 73% and a specificity of 96%. MEA (without added aspirin) and TXB2 were also comparable (ROC curve AUC=0.782; MEA cutoff=31U), but at this threshold, 11 patients (30%) were falsely positive with MEA. Last, MEA and LTA were comparable (ROC curve AUC=0.888; MEA cutoff=56U), with a sensitivity of 90% and a specificity of 84.6%. Besides, MEA gave an insight into the mechanism of aspirin resistance (turnover and/or intrinsic).. MEA is both rapid and reliable as compared to reference methods. Clinical correlation with risk of re-thrombosis should definitively validate this method and the best cutoff value.

Topics: Adult; Aged; Aged, 80 and over; Arachidonic Acid; Aspirin; Blood Platelets; Drug Resistance; Electrodes; Female; Humans; Male; Middle Aged; Myeloproliferative Disorders; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Thrombosis; Thromboxane B2; Young Adult

Thrombotic complications are common in adult patients who have had a Fontan operation early in life for treatment of congenital heart disease.. To characterize platelet function and responsiveness to aspirin in relation to thrombogenesis, systemic inflammation, and markers of endothelial function in adults with Fontan circulation (FC).. Thirty-four FC patients (age 18-40years; 62% taking aspirin chronically and 38% not taking aspirin) and 32 age- and sex-matched healthy controls were studied. Platelet function was evaluated by measurement of basal concentrations of thromboxane B2 (TXB2) and sCD40L and ex-vivo generation of TXB2 and sCD40L. Plasma concentrations of thrombin-antithrombin, endothelin-1, vWF, IL-6, IL-8, MCP-1, MIP-1β, TNFα, sVCAM-1, and syndecan-1 also were measured.. Platelet numbers were significantly lower in FC patients than in controls, but the patients had significantly higher platelet activity, as evidenced by higher TXB2 and sCD40L concentrations and higher ex vivo generation of TXB2. Chronic aspirin treatment had no effect on plasma concentrations of TXB2 and sCD40L in FC, but in 52% of aspirin-treated FC subjects, TXB2 concentrations remained elevated at 60min of TXB2 generation, indicating aspirin resistance. In addition, FC patients had increased levels of thrombin-antithrombin, endothelin-1, vWF, IL-8, MCP-1, MIP-1β, TNFα, sVCAM-1, and syndecan-1 but not of IL-6.. Adults with FC had lower platelet numbers but increased platelet activity, increased thrombogenesis, systemic inflammation, and endothelial dysfunction. A significant proportion of aspirin-treated FC adults had aspirin resistance, which may be at least in part responsible for their increased incidence of thrombotic complications.

Topics: Adult; Aspirin; CD40 Antigens; Drug Resistance; Endothelium, Vascular; Female; Fontan Procedure; Heart Defects, Congenital; Humans; Inflammation; Male; Neutrophil Activation; Platelet Activation; Platelet Aggregation Inhibitors; Platelet Count; Postoperative Complications; Thrombosis; Thromboxane B2

Fish oil supplementation (FOS) is known to have cardiovascular benefits. However, the effects of FOS on thrombosis are incompletely understood. We sought to determine if the use of FOS is associated with lower indices of atherothrombotic risk in patients with suspected coronary artery disease (sCAD). This is a subgroup analysis of consecutive patients with sCAD (n=600) enrolled in the Multi-Analyte, Thrombogenic, and Genetic Markers of Atherosclerosis study. Patients on FOS were compared with patients not on FOS. Lipid profile was determined by vertical density gradient ultracentrifugation (n=520), eicosapentaenoic acid+docosahexaenoic acid was measured by gas chromatography (n=437), and AtherOx testing was performed by immunoassay (n=343). Thromboelastography (n=419), ADP- and collagen-induced platelet aggregation (n=137), and urinary 11-dehydrothromboxane B2 levels (n=259) were performed immediately before elective coronary angiography. In the total population, FOS was associated with higher eicosapentaenoic acid+docosahexaenoic acid content (p<0.001), lower triglycerides (p=0.04), total very low-density lipoprotein cholesterol (p=0.002), intermediate-density lipoprotein cholesterol (p=0.02), and AtherOx levels (p=0.02) but not in patients on lipid-lowering therapy. Patients not on lipid-lowering therapy taking FOS had lower very low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, remnant lipoproteins, triglycerides, low-density lipoprotein cholesterol, AtherOx levels, collagen-induced platelet aggregation, thrombin-induced platelet-fibrin clot strength, and shear elasticity (p<0.03 for all). In clopidogrel-treated patients, there was no difference in ADP-induced aggregation between FOS groups. Patients on FOS had lower urinary 11-dehydrothromboxane B2 levels regardless of lipid-lowering therapy (p<0.04). In conclusion, the findings of this study support the potential benefit of FOS for atherothrombotic risk reduction in sCAD with the greatest benefit in patients not receiving lipid-lowering therapy. Future prospective studies to compare FOS with lipid-lowering therapy and to assess the independent effects of FOS on thrombogenicity are needed.

Topics: Aged; Atherosclerosis; Biomarkers; Cholesterol; Coronary Artery Disease; Dietary Supplements; Docosahexaenoic Acids; Eicosapentaenoic Acid; Female; Fish Oils; Humans; Lipoproteins; Male; Middle Aged; Risk Factors; Thrombelastography; Thrombosis; Thromboxane B2; Triglycerides

Ocimum basilicum L. (OBL) is a plant used in traditional Uyghur medicine for the treatment and prevention of cardiovascular disease. In previous studies we had found an antihypertensive and antithrombotic effect suggestive of an effect on prostaglandins, which we attempt to document here.. 6-keto-PGF1α, the metabolite of prostacyclin, and PGE2 were measured in the supernatant of human umbilical vein endothelial cells (HUVEC) and basal or LPS-stimulated mouse coeliac macrophage cultures exposed to OBL ethanol (OBL-E) extracts and petroleum ether, chloroform, ethylacetate and butanol (PE, C, EA, B) fractions. In addition, 6-keto-PGF1α and thromboxane B2 (TXB2) were measured in a rat model of thromboangiitis obliterans exposed or not to OBL.. Short-term exposure to OBL-E dose-dependently increased 6-keto-PGF1α from HUVEC, and long-term (24h) exposure decreased it. OBL-C and OBL-B increased 6-keto-PGF1α, whereas the other fractions tended to decrease it after 24h exposure. The extract and all fractions decreased basal and stimulated PGE2 production, but only OBL-EA and OBL-B reduced PGE2 in stimulated cultures to concentrations below the unstimulated values (P<0.05). In vivo OBL increased 6-keto-PGF1α and decreased TXB2.. OBL and its extracts increased 6-keto-PGF1α and reduced PGE2 and TXB2 production in a dose and time-related manner. This could indicate simultaneous inhibition of COX-2 and stimulation of endothelial COX-1. The butanol fraction seemed most promising in this respect.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cell Line; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Dose-Response Relationship, Drug; Human Umbilical Vein Endothelial Cells; Humans; Macrophages; Male; Medicine, Traditional; Mice; Ocimum basilicum; Plant Extracts; Prostaglandins; Rats; Rats, Sprague-Dawley; Thromboangiitis Obliterans; Thrombosis; Thromboxane B2; Time Factors

Epidemiological studies have shown the prevention of cardiovascular diseases through the regular consumption of vegetables. Eruca sativa Mill., commonly known as rocket, is a leafy vegetable that has anti-inflammatory activity. However, its antiplatelet and antithrombotic activities have not been described.. Eruca sativa Mill. aqueous extract (0.1 to 1 mg/mL), was evaluated on human platelets: (i) P-selectin expression by flow cytometry; (ii) platelet aggregation induced by ADP, collagen and arachidonic acid; (iii) IL-1β, TGF-β1, CCL5 and thromboxane B2 release; and (iv) activation of NF-κB and PKA by western blot. Furthermore, (v) antithrombotic activity (200 mg/kg) and (vi) bleeding time in murine models were evaluated.. Eruca sativa Mill. aqueous extract (0.1 to 1 mg/mL) inhibited P-selectin expression and platelet aggregation induced by ADP. The release of platelet inflammatory mediators (IL-1β, TGF-β1, CCL5 and thromboxane B2) induced by ADP was inhibited by Eruca sativa Mill. aqueous extract. Furthermore, Eruca sativa Mill. aqueous extract inhibited NF-κB activation. Finally, in murine models, Eruca sativa Mill. aqueous extract showed significant antithrombotic activity and a slight effect on bleeding time.. Eruca sativa Mill. presents antiplatelet and antithrombotic activity.

Topics: Adenosine Diphosphate; Animals; Blood Platelets; Brassicaceae; Chemokine CCL5; Disease Models, Animal; Fibrinolytic Agents; Humans; Interleukin-1beta; Mice; Mice, Inbred C57BL; NF-kappa B; P-Selectin; Plant Extracts; Platelet Aggregation; Platelet Aggregation Inhibitors; Thrombosis; Thromboxane B2; Transforming Growth Factor beta1

Soshiho-tang (SH; Chinese name, Xiao-Chai-Hu-Tang; Japanese name, Shosaiko-to) is a traditional Korean, Chinese, and Japanese medicine, which has been used to treat various conditions, including hepatitis, liver cirrhosis, and chronic and acute liver disease. SH consists of seven herbal components, of which Scutellaria baicalensis Georgi and Zingiber officinale Roscoe, are reported to have antithrombotic and antiplatelet activities. We investigated the antithrombotic activity of SH, including S. baicalensis and Z. officinale, as an integrative therapy.. To identify the antithrombotic activity of SH, we used a FeCl3-induced thrombus formation model. The mechanism of SH-mediated antithrombotic activity was assessed by determining platelet aggregation and coagulation times ex vivo, washed platelet aggregation, serotonin secretion, and thromboxane B2 formation.. SH prolonged the occlusion time of thrombus formation when applied in a FeCl3-induced thrombus formation model. SH also inhibited collagen-induced platelet aggregation ex vivo in a concentration-dependent manner; however, it did not affect coagulation. Hence, to identify the antiplatelet effect of SH, we investigated washed platelet aggregations in vitro. SH significantly inhibited various agonist-induced platelet aggregations, and it completely inhibited serotonin secretion and thromboxane B2 formation.. The findings suggest that SH inhibited FeCl3-induced thrombus formation through antiplatelet activity, including inhibition of platelet aggregation, and serotonin and TXB2 production. Thus, SH may be useful as an integrative herbal formula for the treatment of thrombosis.

Topics: Animals; Antithrombins; Blood Coagulation; Drugs, Chinese Herbal; Humans; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2

Platelets are critically important for primary haemostasis and the major players in thrombotic vascular occlusion. Platelets are activated by agonists, such as thrombin and collagen-related peptide as well as second-wave mediators including thromboxane A2 via different intracellular signaling pathways resulting in degranulation, aggregation and thrombus formation. Platelet activation is paralleled by phosphorylation and activation of p38 MAPK. The limited specificity of hitherto known p38 MAPK inhibitors precluded safe conclusions on the precise role of p38 MAPK in the regulation of platelet function. The present study examined the impact of Skepinone-L, a novel and highly selective inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), on platelet activation and thrombus formation.. Experiments were performed in freshly isolated human platelets. Protein phosphorylation was quantified by Western blotting, thromboxane B2 synthesis by enzyme immunoassay, ATP release by ChronoLume luciferin assay, cytosolic Ca(2+) concentration by Fura-2 fluorescence-measurements, platelet aggregation by a light transmissions measurement and in vitro thrombus formation by a flow chamber.. Skepinone-L (1 μM) virtually abrogated the phosphorylation of platelet p38 MAPK substrate Hsp27 following stimulation with CRP (1 μg/ml), thrombin (5 mU/ml) or thromboxane A2 analogue U-46619 (1 μM). Furthermore, Skepinone-L significantly blunted activation-dependent platelet secretion and aggregation following threshold concentrations of CRP, thrombin and thromboxane A2 analogue U-46619. Skepinone-L did not impair platelet Ca(2+) signaling but prevented agonist-induced thromboxane A2 synthesis through abrogation of p38 MAPK-dependent phosphorylation of platelet cytosolic phospholipase A2 (cPLA2). Skepinone-L further markedly blunted thrombus formation under low (500-s) and high (1700-s) arterial shear rates.. The present study discloses a powerful inhibiting effect of p38 MAPK-blocker Skepinone-L on platelet activation and thrombus formation.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenosine Triphosphate; Blood Platelets; Calcium; Carrier Proteins; Dibenzocycloheptenes; Fura-2; HSP27 Heat-Shock Proteins; Humans; p38 Mitogen-Activated Protein Kinases; Peptides; Phospholipases A2; Phosphorylation; Platelet Activation; Platelet Aggregation; Protein Kinase Inhibitors; Shear Strength; Thrombin; Thrombosis; Thromboxane B2

Many circulating haemostatic markers have been investigated in relation to the abdominal aortic aneurysm (AAA) size, growth as well as intraluminal thrombus (ILT) size. However, the results of these studies seem to be uncertain and inconsistent. The first aim of the present study was to compare the haemostatic parameters of fibrinolysis and some of thrombotic markers in patients with AAA and controls. We also examined the relationship between those parameters and both maximum aneurysm diameter and intraluminal thrombus thickness. Tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1), fibrinogen (Fb), D-dimer, prothrombin fragments 1 and 2 (F1+2), thromboxane B2 (TXB2) and lipids profile were measured in 36 patients with AAA and 30 controls. The mean maximum aortic diameter in patients with the AAA was 59±12 mm (range 42-100). The mean ILT thickness was 32±10 mm (range 8-56). Among haemostatic factors, t-PA and D-dimer levels, but not PAI-1, were significantly higher in subjects with the AAA. There was a strong positive correlation between thickness of intraluminal thrombus and maximum aneurysm size (r=0.69, p<0.0001), and the negative relationship between t-PA and ILT thickness (r= -0.53, p=0.001) as well as aneurysm diameter (r= -0.38, p=0.023). Higher plasma concentrations of t-PA and D-dimer support the hypothesis that the secondary fibrinolysis plays an important role in the pathogenesis of the aortic abdominal aneurysm formation. In addition, the negative correlation between t-PA plasma level and ILT thickness suggests that thrombotic/fibrinolysis imbalance may favour accelerated formation of intraluminal thrombus and possibly aneurysm progression.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Biomarkers; Disease Progression; Female; Fibrin Fibrinogen Degradation Products; Fibrinolysis; Humans; Male; Middle Aged; Plasminogen Activator Inhibitor 1; Severity of Illness Index; Thrombosis; Thromboxane B2; Tissue Plasminogen Activator; Tomography, X-Ray Computed

To investigate the effects of Qushuanling Capsule ( QSLC) on thrombus formation and platelet aggregation in rats.. Arteriovenous bypass, venous thrombosis, and middle cerebral artery thrombosis models were used in rats to investigate the anti-thrombotic effects of QSLC, a compound of nine Chinese herbs. The platelet aggregation induced by adenosine diphosphate (ADP), thrombin or arachidonic acid (AA), as well as the contents of thromboxane B(2) (TXB(2)) and 6-keto-prostaglandin F1α (6-keto-PGF1α) in rat plasma and aortic walls, were determined to investigate the possible mechanisms of the anti-thrombotic effects of QSLC.. After oral administration with QSLC for 7 days, arteriovenous bypass thrombosis was obviously suppressed compared with the model group, venous thrombosis was also obviously suppressed, rat behaviors were obviously improved, and brain infarct size as well as water content were also reduced. The platelet aggregation induced by ADP or thrombin was inhibited by QSLC, but the drug had no effect on AA-induced platelet aggregation and content of TXB(2) and 6-keto-PGF1α in plasma and the aortic wall.. These results suggest that QSLC can be used in the prevention and treatment of thrombotic diseases, and that its mechanism of action may be related to inhibition of platelet aggregation.

Topics: 6-Ketoprostaglandin F1 alpha; Adenosine Diphosphate; Animals; Aorta; Cerebral Infarction; Drugs, Chinese Herbal; Male; Middle Cerebral Artery; Platelet Aggregation; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2; Venous Thrombosis

Previous studies have demonstrated that statin can reduce the risk of acute coronary syndrome. In order to explore the mechanism, we observed the effects of pravastatin on plaque stability in atherosclerotic rabbits. Sixteen male rabbits were fed with a high fat diet following their damaged abdominal aortic endothelium by using catheter. Eight of them were administered with pravastatin (10 mg·kg(-1)·d(-1)) for 4 weeks. Then the rabbit atherosclerotic plaque rupture and thrombosis were triggered by injection of viper venom and histamine. Compared with model group, the thrombus area on aorta in pravastatin-treated group was reduced. Fibre cap on plaque was more thick and integrant, and inflammatory cell infiltration was also decreased. Serum total cholesterol, triglyceride, low density lipoprotein-cholesterol and contents of cholesterol in abdominal aorta were decreased. 6-Keto-prostaglandin F(1α) (6-keto-PGF(1α)) level and ratio of 6-keto-PGF(1α)/thromboxane B(2) (TXB(2)) in aorta were significantly increased. These results suggested that pravastatin could increase plaque stability and inhibit thrombosis through both lipid-dependent and lipid-independent way.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anticholesteremic Agents; Aorta; Aorta, Abdominal; Atherosclerosis; Cholesterol; Cholesterol, LDL; Diet, High-Fat; Disease Models, Animal; Histamine; Hyperlipidemias; Male; Plaque, Atherosclerotic; Pravastatin; Rabbits; Thrombosis; Thromboxane B2; Triglycerides; Viper Venoms

Anti-platelet therapy with aspirin is the cornerstone of treatment after coronary artery bypass grafting (CABG). Aspirin resistance describes the clinical observation of the inability of aspirin to prevent thrombotic complications or the laboratory phenomenon of absence of the effect of aspirin on platelet inhibition tests. Off-pump CABG (OPCAB) is associated with reduced platelet activation and turnover compared to on-pump surgery which may indicate that aspirin is more effective after OPCAB. Our aim was to evaluate the efficacy of aspirin and incidence of aspirin resistance in patients undergoing OPCAB.. A total of 331 patients was recruited, of which 111 underwent primary OPCAB (group A) and 220 controls with ischaemic heart disease received medical therapy. Arachidonic acid-induced platelet aggregation and urinary 11-dehydro thromboxane B2 (11-dehydroTxB2) were measured at baseline and following aspirin administration on days 1, 4 and 10. A 6-month follow-up was completed in patients who developed aspirin resistance.. On the first postoperative day, 78 patients (70.3%) were aspirin sensitive (AS) and 33 (29.7%) were aspirin resistant (AR). Of the latter, 18 (16.2%) and five (4.5%) patients remained resistant on days 4 and 10, respectively. AR patients had significantly greater platelet aggregation and urinary 11-dehydroTxB2 levels at all time points than those in the AS group. All patients in the AR group were AS by 6 months. All controls were sensitive to aspirin with similar platelet aggregation and 11-dehydroTxB2 to those in the AS group.. Aspirin resistance is a transient phenomenon during the early postoperative period in approximately 30% of patients undergoing OPCAB.

Topics: Aged; Aspirin; Biomarkers; Case-Control Studies; Coronary Artery Bypass, Off-Pump; Drug Administration Schedule; Drug Resistance; Female; Humans; Male; Middle Aged; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Count; Postoperative Care; Postoperative Period; Thrombosis; Thromboxane B2

The pharmacological activity of 2NTX-99 ([4-methoxy-N1-(4-trans-nitrooxycyclohexyl)-N3-(3-pyridinylmethyl)-1,3-benzenedicarboxamide]) was investigated in vitro in the intact, rat pulmonary vasculature and in guinea pig airways. Rat lungs were perfused at constant flow and changes in vascular tone recorded. Challenge with the TXA₂ analogue 9,11-dideoxy-9α11α-methanoepoxy ProstaglandinF₂ (U46619, 0.5 μM) increased vessel tone (32.48±1.5 vs 13.13±0.56 mmHg; n=12). 2NTX-99 (0.1-100 μM; n=5), caused a concentration-dependent relaxation, prevented by 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 10 μM, n=4), an inhibitor of soluble guanylate cyclase. Acetylcholine (0.1-10 μM; n=3) and a reference NO-donor, isosorbide-5-mononitrate (5-100 μM; n=4), were ineffective. Intraluminal perfusion of washed human platelets (2 × 10⁸ cells/ml) increased intravascular pressure after challenge with arachidonic acid (AA, 2 μM; n=5), an increase abolished by acetylsalicylic acid and significantly reduced by 2NTX-99 (40 μM; n=5). TXB₂ in the lung perfusate was detected after platelet activation, 2NTX-99 inhibited TXA₂ synthesis (6.45±0.6 and 1.10±0.2 ng/ml, respectively). 2NTX-99 did not alter central or peripheral airway responsiveness to Histamine (0.001-300 μM; n=6), U46619 (0.001-3 μM, n=3) or LTD₄ (1 pM-1 μM; n=6). 2NTX-99 vasodilates the pulmonary vasculature via the release of nitric oxide (NO) and reduces intraluminal, AA-induced, TXA₂ formation. The combined activity of 2NTX-99 as an NO-donor and a TXA₂-synthesis inhibitor provides strong support for its potential therapeutic use in pathologies of the pulmonary vascular bed (e.g. pulmonary hypertension).

Topics: Animals; Benzamides; Blood Platelets; Guinea Pigs; Humans; In Vitro Techniques; Lung; Male; Muscle Contraction; Muscle, Smooth; Perfusion; Rats; Thrombosis; Thromboxane B2; Trachea

Morus alba (white mulberry) has been used in traditional Chinese medicine as an anti-headache, diuretic, expectorant, and anti-diabetic agent. In previous studies, extracts of Morus alba demonstrated favorable biological properties, such as antioxidant activity, suppression of lipoxygenase (LOX)-1, cytotoxicity against cancer cells, and inhibition of the invasion and migration of cancer cells.. This study further evaluated the effects of morusinol, a flavonoid derived from Morus alba root bark, on platelet aggregation and thromboxane B(2) (TXB(2) formation in vitro and thrombus formation in vivo.. The antiplatelet potential of morusinol was measured using in vitro rabbit platelet aggregation and TXB(2) formation assays. Arterial thrombus formation was investigated using an in vivo ferric chloride (FeCl(3)-induced thrombosis model.. Morusinol significantly inhibited collagen- and arachidonic acid-induced platelet aggregation and TXB(2) formation in cultured platelets in a concentration-dependent manner. Thrombus formation was reduced by 32.1, 42.0, and 99.0% for collagen-induced TXB(2) formation, and 8.0, 24.1, and 29.2% for arachadonic acid-induced TXB(2) formation, with 5, 10, and 30 µg/mL morusinol, respectively. Moreover, oral morusinol (20 mg/kg) or aspirin (20 mg/kg) for three days significantly increased the time to occlusion in vivo by 20.3±5.0 or 6.8±2.9 min, respectively, compared with the control (1% CMC, carboxymethyl cellulose).. Taken together, these results indicate that morusinol may significantly inhibit arterial thrombosis in vivo due to antiplatelet activity. Thus, morusinol may exert beneficial effects on transient ischemic attacks or stroke via the modulation of platelet activation.

Topics: Animals; Arteries; Blood Platelets; Cardiovascular Diseases; Electron Spin Resonance Spectroscopy; Flavonoids; Magnetic Resonance Spectroscopy; Male; Molecular Structure; Morus; Plant Extracts; Plant Roots; Platelet Activation; Platelet Aggregation; Rabbits; Thrombosis; Thromboxane B2

Methionine ingestion (100mg/kg) identifies subjects in whom fasting total homocysteine (tHcy) may be normal but the post-methionine load (PML) tHcy is abnormally high.. In 96 subjects [54 M/42 F, 40.4 ± 12.3 yrs old; 28 with the 68 bp844 ins of the cystathionine-β-synthase gene (CBSins+); 20 homozygotes for the C677T mutation of the methylene-tetrahydrofolate reductase gene (MTHFR++); 13 with the combination of the two, and 35 without any of them], we have evaluated in vivo oxidative stress and platelet activation, as reflected by urinary excretions of 8-iso-PGF(2α) and of 11-dehydro-TXB(2) respectively, before and after a methionine load test (PML). A history of early-onset thrombosis (18 arterial, 32 venous, 2 both) was present in 52/96 of them.. Baseline; tHcy was highest in MTHFR++ carriers (p < 0,05); 8-iso-PGF(2α) and 11-dehydro-TXB(2) levels were independent of sex, MTHFR++ and/or CBSins + (p > 0.05). PML; The ~3-fold increase (p < 0.01 vs baseline) in tHcy reached a plateau within 6-8 hrs. Mean PML tHcy was maximal in MTHFR++ carriers (p = 0.000). 8-iso-PGF(2α) and 11-dehydro-TXB(2) increase reached a maximum within 4 hrs. 11-dehydro-TXB(2) increase was highest (p = 0.023 vs baseline) in subjects with a history of thrombosis. Baseline 11-dehydro-TXB(2) and a history of thrombosis independently predicted PML 11-dehydro-TXB(2) (β = 0.287, p = 0.000 and β = 0.308, p = 0.026, respectively).The PML increase in 8-iso-PGF(2α) or in 11-dehydro-TXB(2) were comparable in the different genotypes (p > 0.05).. Regardless genotypes associated with moderate hyperhomocysteinemia, following a methionine loading test, in vivo oxidative stress and platelet activation occur, being the latter maximal in subjects with a history of early-onset thrombosis.

Topics: Adult; Age of Onset; Analysis of Variance; Biomarkers; Case-Control Studies; Chi-Square Distribution; Cystathionine beta-Synthase; Dinoprost; Female; Homocysteine; Homozygote; Humans; Hyperhomocysteinemia; Italy; Linear Models; Male; Methionine; Methylenetetrahydrofolate Reductase (NADPH2); Middle Aged; Mutation; Oxidative Stress; Phenotype; Platelet Activation; Platelet Function Tests; Thrombosis; Thromboxane B2; Time Factors

To observe the influence of the plasma thromboxane B2 (TXB2), 6-keto-PGF1alpha, CD62P and PAC-1 and Thrombus in patients with primary thrombocytosis (ET). To observe the effect of sodium ozagrel to prevent and treat thrombosis in patients with ET.. The subjects including 48 patients with ET. All patients were measured the plasma TXB2, 6-keto-PGF1alpha, CD62P and PAC-1 before and after treatment with or without sodium ozagrel.. The plasma levels of CD62P, PAC-1, TXB2, 6-keto-PGF1alpha and TXA2/PGI2 in the patients with ET were significantly higher than the normal people (P < 0.01). The levels of CD62P, PAC-1, TXB2, TXB2/6-keto-PGF1alpha in patients with treatment of sodium ozagrel were higher than patients without treatment of sodium ozagrel (P < 0.01). The plasma levels of CD62P, PAC-1 and TXA2/PGI2 in patients with treatment of sodium ozagrel and that in normal people had no significant distinction (P < 0.01). All the index of conventional therapy group were higher than normal people (P < 0.01) but had no significant distinction with the patients before conventional treating. The incidence of thrombus in patients treated with sodium ozagrel was lower than patients treated without sodium ozagrel (P < 0.05).. With the treatment of sodium ozagrel in patients with ET, the CD62P, PAC-1, TXB2 and TXA2/PGI2 of plasma could be decreased. And the incidence of thrombus was decreased.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Antibodies, Monoclonal; Blood Platelets; Female; Humans; Male; Methacrylates; Middle Aged; P-Selectin; Receptors, Fibrinogen; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; Thrombocythemia, Essential; Thrombosis; Thromboxane A2; Thromboxane B2

Aspirin is often used to prevent thrombosis in pediatric cardiac surgery. The primary study aim was to assess aspirin resistance in this context. Secondary aims were to evaluate (1) the relationship between elevated inflammatory markers and thrombosis and (2) aspirin's effect on these levels.. This was a prospective observational study of children undergoing cardiac surgery managed with and without aspirin. Aspirin response was assessed using the VerifyNow system and urinary 11-dehydrothromboxane B2 (uTxB2) measurements. Laboratory studies of inflammation were also obtained.. 101 subjects were studied; 50 received aspirin. Six subjects (5.9%), 5 aspirin-treated, experienced symptomatic thrombosis. When measured by VerifyNow resistance was 43% after aspirin suppositories and 14% after additional days of oral aspirin. There was no correlation with thrombosis. Upper quartile post-operative day (POD) #5 uTxB2 was correlated with thrombosis in aspirin treated subjects (p<0.01). High risk aspirin-treated subjects who experienced thrombosis had higher POD#5 uTxB2. This finding did not reach statistical significance (p=0.07). Elevated pre-operative C-reactive protein (CRP) was independently associated with thrombosis (p<0.02) in all subjects and in high risk subjects (p=0.01). Inflammatory markers were not affected by aspirin.. Aspirin inhibited ex-vivo platelet function with a low incidence of resistance. Elevated POD#5 uTxB2 and pre-operative CRP were correlated with thrombosis in aspirin treated subjects. Further studies are needed to determine whether children with high levels of uTxB2 despite aspirin therapy and/or those with elevated preoperative CRP are at increased risk for thrombosis.

Topics: Administration, Oral; Administration, Rectal; Aspirin; Biomarkers; C-Reactive Protein; Cardiac Surgical Procedures; Drug Resistance; Fibrinolytic Agents; Heart Defects, Congenital; Humans; Infant; Infant, Newborn; Inflammation Mediators; Logistic Models; New York; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Prospective Studies; Risk Assessment; Risk Factors; Suppositories; Thrombosis; Thromboxane B2; Time Factors; Treatment Outcome; Up-Regulation

This study sought to evaluate the platelet response to aspirin and the immature platelet fraction in patients with previous stent thrombosis (ST).. ST is a potentially fatal complication of coronary stenting. A reduced platelet response to aspirin increases the risk of cardiovascular events.. We included 117 patients previously undergoing percutaneous coronary intervention. A total of 39 patients had suffered ST and 78 patients served as controls matched at a 1:2 ratio with respect to age, sex, stent type, and percutaneous coronary intervention indication. All patients were treated with aspirin 75 mg once daily. Platelet function was assessed by multiple electrode aggregometry in citrated and hirudinized blood and by VerifyNow Aspirin Assay (Accumetrics, San Diego, California). Flow cytometric determination of the immature platelet fraction was performed to evaluate platelet turnover. Platelet activation was evaluated by soluble serum P-selectin. Compliance was confirmed by serum thromboxane B(2).. All patients were fully compliant, which was confirmed by suppressed levels of serum thromboxane B(2). Platelet aggregation was increased in patients with previous ST when assessed by multiple electrode aggregometry induced by collagen (p(citrated blood) = 0.003; p(hirudinized blood) < 0.0001) and by arachidonic acid (p(citrated blood) = 0.16; p(hirudinized blood) = 0.04), respectively. Similarly, platelet aggregation assessed by VerifyNow was higher in ST cases (p = 0.12). A trend toward an increased immature platelet fraction among cases was seen (p = 0.13), whereas P-selectin levels (p = 0.56) did not differ between groups.. Overall, patients with previous ST had a reduced antiplatelet effect of aspirin, which might be explained by an increased platelet turnover.

Topics: Aged; Angioplasty, Balloon, Coronary; Aspirin; Biomarkers; Blood Platelets; Case-Control Studies; Chi-Square Distribution; Coronary Artery Disease; Denmark; Drug Resistance; Female; Flow Cytometry; Humans; Linear Models; Male; Medication Adherence; Middle Aged; P-Selectin; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Count; Platelet Function Tests; Retrospective Studies; Stents; Thrombosis; Thromboxane B2; Time Factors; Treatment Outcome

Selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) increase the incidence of cardiovascular and cerebrovascular events. Complete disruption of the murine gene encoding COX-2 (Ptgs2) leads to renal developmental problems, as well as female reproductive anomalies and patent ductus arteriosus of variable penetrance in newborns, thus rendering this genetic approach difficult to compare with coxib administration. Here, we created hypomorphic Ptgs2 (COX-2(Neo/Neo)) mice in which COX-2 expression is suppressed to an extent similar to that achieved with coxibs, but not eliminated, in an attempt to circumvent these difficulties. In LPS-challenged macrophages and cytokine-stimulated endothelial cells obtained from COX-2(Neo/Neo) mice, COX-2 expression was reduced 70-90%, and these mice developed a mild renal phenotype compared with COX-2 mice possessing an active site mutation (COX-2(Y385F/Y385F)), with minimal signs of renal dysfunction as measured by FITC-inulin clearance and blood urea nitrogen. These COX-2 knockdown mice displayed an increased propensity for thrombogenesis compared with their wild-type (COX-2(+/+)) littermates observed by intravital microscopy in cremaster muscle arterioles upon ferric chloride challenge. Measurement of urinary prostanoid metabolites indicated that COX-2(Neo/Neo) mice produced 50% less prostacyclin but similar levels of PGE(2) and thromboxane compared with COX-2(+/+) mice in the absence of any blood pressure and ex vivo platelet aggregation abnormalities. COX-2(Neo/Neo) mice, therefore, provide a genetic surrogate of coxib therapy with disrupted prostacyclin biosynthesis that predisposes to induced arterial thrombosis.

Topics: Animals; Blood Pressure; Blood Urea Nitrogen; Cardiovascular System; Cells, Cultured; Chlorides; Cyclooxygenase 1; Cyclooxygenase 2; Cytokines; Dinoprostone; Disease Models, Animal; Endothelial Cells; Epoprostenol; Ferric Compounds; Glomerular Filtration Rate; Heart Rate; Kidney; Macrophages, Peritoneal; Membrane Proteins; Mice; Mice, Knockout; Microscopy, Video; Thrombosis; Thromboxane B2; Time Factors

Diclofenac, like selective cyclooxygenase-2 inhibitors, which alter vascular levels of platelet active prostaglandins, has been reported to increase rates of acute myocardial infarction.. The study was performed to investigate, in an animal model of arterial thrombosis in vivo, whether diclofenac differentially influences platelet activation and thrombosis in vessels under non-stimulated conditions or during acute systemic inflammation, such as induced by tumor necrosis factor-alpha (TNF-alpha).. Platelet-vessel wall interaction (PVWI), firm platelet adhesion and arterial thrombosis following vessel injury were analyzed by intravital microscopy in arterioles of hamsters in the dorsal skinfold chamber model. Prostacyclin [prostaglandin I(2) (PGI(2))] and thromboxane A(2) (TxA(2)) metabolites were measured. In vitro, endothelial adhesion molecule expression in cultured human microvascular endothelial cells was analyzed.. Under non-stimulated conditions, diclofenac (1 mg kg(-1)) enhanced PVWI, which was not mediated by increased adhesion molecule expression, but by decreased systemic PGI(2) levels. Following ferric chloride-induced endothelial injury, diclofenac accelerated thrombotic vessel occlusion time, an effect that was reversed by the stable PGI(2) analog iloprost. TNF-alpha, through induction of endothelial adhesion molecule expression, also enhanced PVWI, firm adhesion, and arterial thrombosis, but simultaneous treatment with TNF-alpha and diclofenac did not have an additive effect.. By decreasing levels of PGI(2) without, at the same time, altering prothrombotic TxA(2) levels, diclofenac can exert prothrombotic effects. However, this is not the case when an inflammatory situation is created by TNF-alpha treatment. These data may explain the enhanced risk of acute myocardial infarction observed in patients taking diclofenac.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arterioles; Cells, Cultured; Chlorides; Cricetinae; Cyclooxygenase Inhibitors; Diclofenac; Endothelium, Vascular; Ferric Compounds; Humans; Mesocricetus; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Platelet Activation; Platelet Adhesiveness; Skin Window Technique; Thromboplastin; Thrombosis; Thromboxane B2; Tumor Necrosis Factor-alpha

To investigate the relations of platelet phospholipid fatty acids to thrombotic risk factors in the middle-aged and geriatric patients with hyperlipidemia in the metropolitan area of Hangzhou, Zhejiang province.. A questionnaire survey was conducted among 81 patients with hyperlipidemia, 50 males and 31 females, aged (57 +/- 8), and 65 healthy controls, 43 males and 22 females, aged (58 +/- 9) to collect the data about height, weight, and diet. Peripheral venous blood samples were collected to examine the total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), homocysteine (Hcy), 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)), and thromboxane B(2) (TXB(2)) were examined by standard methods. Serum thrombotic risk factors including homocysteine and Thromboxane B(2) were determined by standard methods. Platelet phospholipid fatty acids were examined by gas chromatography. The correlation between the serum thrombotic risk factors (Hcy, TXB(2), and 6-keto-PG F1a) was analyzed by multivariate linear regression.. There were no significant differences in platelet phospholipid fatty acids between the patients with hyperlipidemia and the healthy controls. Serum Hcy was significantly negatively correlated with docosahexaenoic acid (DHA) and the ratio of n-3 PUFA (polyunsaturated fatty acids)/n-6 PUFA (r = -0.277 and -0.231, both P < 0.01). The level of serum TXB(2) was significantly positively correlated with arachidonic acid (r = 0.176, P < 0.05), and significantly negatively correlated with DHA (r = -0.209, P < 0.01), eicosapentaenoic acid (EPA) (r = -0.194, P < 0.05), and n-3 PUFA/n-6 PUFA (r = -0.238, P < 0.01).. Increasing the ratio of n-3 PUFA/n-6 PUFA in platelet phospholipid may potentially decrease the thrombotic risks such as Hcy and TXB(2) and provide a reference for diet selection.

Topics: 6-Ketoprostaglandin F1 alpha; Aged; Arachidonic Acid; Blood Platelets; Cholesterol; Dietary Fats; Fatty Acids; Female; Homocysteine; Humans; Hyperlipidemias; Linear Models; Male; Middle Aged; Multivariate Analysis; Phospholipids; Risk Factors; Surveys and Questionnaires; Thrombosis; Thromboxane B2

The inability of aspirin (acetylsalicylic acid [ASA]) to adequately suppress platelet function is associated with future risk of myocardial infarction, stroke, and cardiovascular death. Genetic variation is a proposed but unproved mechanism for insufficient ASA responsiveness.. We examined platelet ASA responsiveness in 1880 asymptomatic subjects (mean age, 44+/-13 years; 58% women) recruited from 309 white and 208 black families with premature coronary heart disease. Ex vivo platelet function was determined before and after ingestion of ASA (81 mg/d for 2 weeks) with the use of a panel of measures that assessed platelet activation in pathways directly and indirectly related to cyclooxygenase-1, the enzyme inhibited by ASA. The proportion of phenotypic variance related to CHD risk factor covariates was determined by multivariable regression. Heritability of phenotypes was determined with the use of variance components models unadjusted and adjusted for covariates. ASA inhibited arachidonic acid-induced aggregation and thromboxane B2 production by > or = 99% (P<0.0001). Inhibition of urinary thromboxane excretion and platelet activation in pathways indirectly related to cyclooxygenase-1 was less pronounced and more variable (inhibition of 0% to 100%). Measured covariates contributed modestly to variability in ASA response phenotypes (r2=0.001 to 0.133). Phenotypes indirectly related to cyclooxygenase-1 were strongly and consistently heritable across races (h2=0.266 to 0.762; P<0.01), but direct cyclooxygenase-1 phenotypes were not.. Heritable factors contribute prominently to variability in residual platelet function after ASA exposure. These data suggest a genetic basis for the adequacy of platelet suppression by ASA and potentially for differences in the clinical efficacy of ASA.

Topics: Adult; Arachidonic Acid; Aspirin; beta-Thromboglobulin; Black or African American; Blood Platelets; Cardiovascular Diseases; Coronary Disease; Cyclooxygenase 1; Cyclooxygenase Inhibitors; Drug Resistance; Dyslipidemias; Female; Genetic Heterogeneity; Genetic Predisposition to Disease; Genetic Variation; Humans; Hyperglycemia; Hypertension; Male; Membrane Proteins; Middle Aged; Phenotype; Platelet Activation; Platelet Aggregation; Platelet Aggregation Inhibitors; Prospective Studies; Risk Factors; Sex Characteristics; Smoking; Thrombophilia; Thrombosis; Thromboxane B2; White People

Caffeic acid phenethyl ester (CAPE), which is derived from the propolis of honeybee hives, has been demonstrated to possess multiple pharmacological activities. In the present study, CAPE (6-25 microM) specifically inhibited collagen-induced platelet aggregation and the ATP release reaction in platelet suspensions.. Platelet aggregation, flow cytometric analysis, immunoblotting, and electron spin resonance (ESR) were used to assess the anti-platelet activity of CAPE. Fluorescein sodium-induced platelet thrombi in mesenteric microvessels of mice were used for an in vivo study.. CAPE (15-100 microM) produced a concentration-related rightward displacement of the collagen concentration-response curve, and the Schild plot gave pA(2) and pA(10) values of 4.28+/-0.07 and 3.14+/-0.73, respectively, with a slope of -0.83+/-0.16, indicating specific antagonism. CAPE (25 microM) also inhibited platelet aggregation stimulated by the glycoprotein VI agonist, convulxin, and the alpha(2)beta(1) integrin agonist, aggretin. CAPE (25 microM) also markedly interfered with FITC-collagen binding to platelet membranes. CAPE (15 and 25 microM) concentration-dependently inhibited collagen-induced platelet activation accompanied by [Ca(+2)](i) mobilization, phosphoinositide breakdown, activation of protein kinase C and mitogen-activated protein kinases (i.e., ERK2, JNK, and p38 MAPK), Akt phosphorylation, and thromboxane A(2) formation. In the ESR study, CAPE (15 and 25 microM) markedly reduced hydroxyl radical (OH) formation in collagen-activated platelets. In an in vivo study, CAPE (5 mg/kg) significantly prolonged the latency in inducing platelet plug formation in mesenteric venules of mice.. The most important findings of this study suggest that CAPE specifically inhibits collagen-induced platelet activation. Thus, CAPE treatment may represent a novel approach to lowering the risk of or improving function in thromboembolism-related disorders.

Topics: Animals; Biological Assay; Blood Platelets; Caffeic Acids; Collagen; Crotalid Venoms; Depression, Chemical; Dose-Response Relationship, Drug; Flow Cytometry; Humans; Hydroxyl Radical; Immunoblotting; Integrin alpha2beta1; Lectins, C-Type; Mesenteric Arteries; Mice; Phenylethyl Alcohol; Platelet Aggregation Inhibitors; Platelet Membrane Glycoproteins; Spectrometry, Fluorescence; Thrombosis; Thromboxane B2; Viper Venoms

Variations in platelet function among individuals may be related to differences in platelet-related genes. The major goal of our study was to estimate the contribution of inheritance to the variability in platelet function in unaffected individuals from white and African American families with premature coronary artery disease.. Platelet reactivity, in the absence of antiplatelet agents, was assessed by in vitro aggregation and the platelet function analyzer closure time. Heritability was estimated using a variance components model.. Both white (n = 687) and African American (n = 321) subjects exhibited moderate to strong heritability (h(2)) for epinephrine- and adenosine diphosphate-induced aggregation (0.36-0.42 for white and >0.71 for African American subjects), but heritability for collagen-induced platelet aggregation in platelet-rich plasma was prominent only in African American subjects. Platelet lag phase after collagen stimulation was heritable in both groups (0.47-0.50). A limited genotype analysis demonstrated that the C825T polymorphism of GNB3 was associated with the platelet aggregation response to 2 muM epinephrine, but the effect differed by race.. Considering the few and modest genetic effects reported to affect platelet function, our findings suggest the likely existence of undiscovered important genes that modify platelet reactivity, some of which affect multiple aspects of platelet biology.

Topics: Adult; Blood Platelets; Coronary Artery Disease; Family Health; Female; Fibrinogen; Genotype; Humans; Male; Middle Aged; Platelet Aggregation; Polymorphism, Genetic; Thrombosis; Thromboxane B2; von Willebrand Factor

To study the mechanism involved in the potentially beneficial effect of ultra low dose aspirin (ULDA) in prehepatic portal hypertension, rats were pretreated with selective COX 1 or 2 inhibitors (SC-560 or NS-398 respectively), and subsequently injected with ULDA or placebo.. Portal hypertension was induced by portal vein ligation. Platelet activity was investigated with an in-vivo model of laser induced thrombus production in mesenteric circulation and induced hemorrhagic time (IHT). Platelet aggregation induced by ADP and dosing of prostanoid products 6-keto-PGF1alpha, TXB2, PGE2 and LTB4 were also performed.. The portal hypertensive group receiving a placebo showed a decreased in vivo platelet activity with prolonged IHT, an effect that was normalized by ULDA. SC-560 induced a mild antithrombotic effect in the normal rats, and an unmodified effect of ULDA. NS-398 had a mild prothrombotic action in portal hypertensive rats, similar to ULDA, but inhibited a further effect when ULDA was added. An increased 6-keto-PGF1alpha was observed in portal hypertensive group that was normalised after ULDA administration. TXA2 level after ULDA, remained unchanged.. These results suggest that the effect of ULDA on platelet activity in portal hypertensive rats, could act through a COX 2 pathway more than the COX 1, predominant for aspirin at higher doses.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Blood Platelets; Cyclooxygenase Inhibitors; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Hypertension, Portal; Lasers; Leukotriene B4; Male; Nitrobenzenes; Platelet Activation; Pyrazoles; Rats; Rats, Wistar; Sulfonamides; Thrombosis; Thromboxane B2

Thrombotic events still occur in aspirin-treated patients with coronary artery disease.. To better understand aspirin "resistance," serum thromboxane B2 (TXB2) and flow cytometric measures of arachidonic acid-induced platelet activation (before and after the ex vivo addition of aspirin and indomethacin) were analyzed in 700 consecutive aspirin-treated patients undergoing cardiac catheterization. In 680 of 682 evaluable patients, serum TXB2 concentrations were reduced compared with nonaspirinated healthy donors. Twelve patients had serum TXB2 that was lower than nonaspirinated healthy donors but >10 ng/mL. Arachidonic acid stimulated greater platelet activation in patients with high serum TXB2 (>10 ng/mL) than in patients with low serum TXB2. Addition of ex vivo aspirin reduced arachidonic acid-induced platelet activation to similar levels regardless of serum TXB2 concentrations, which suggests that patients with high residual serum TXB2 concentrations were either noncompliant or underdosed with aspirin. Among the remaining 98% of patients, ex vivo administration of either aspirin or indomethacin failed to prevent platelet activation across all degrees of arachidonic acid-induced platelet activation and aspirin doses. Although the patients were not randomized with respect to clopidogrel treatment, multivariate analysis showed that arachidonic acid-induced platelet activation was less in patients receiving clopidogrel.. There is a residual arachidonic acid-induced platelet activation in aspirin-treated patients that (1) is caused by underdosing and/or noncompliance in only approximately 2% of patients and (2) in the remaining patients, occurs via a cyclooxygenase-1 and cyclooxygenase-2 independent pathway, in direct proportion to the degree of baseline platelet activation, and is mediated in part by adenosine diphosphate-induced platelet activation.

Topics: Adenosine Diphosphate; Arachidonic Acid; Aspirin; Clopidogrel; Coronary Artery Disease; Cyclooxygenase 1; Cyclooxygenase 2; Dose-Response Relationship, Drug; Drug Resistance; Female; Flow Cytometry; Humans; Male; Middle Aged; Multivariate Analysis; Platelet Activation; Platelet Aggregation; Platelet Aggregation Inhibitors; Recurrence; Signal Transduction; Thrombosis; Thromboxane B2; Ticlopidine; Time Factors; Treatment Refusal

Inosine is a naturally occurring nucleoside degraded from adenosine. Recent studies have demonstrated that inosine has potent immunomodulatory and neuroprotective effects. In the present study, we further investigated the inhibitory effects of inosine on platelet activation in vitro and in vivo, as well as in attenuating middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia in rats.. Inosine concentration-dependently (0.5 to 6.0 mmol/L) inhibited platelet aggregation stimulated by agonists. Inosine (1.5 and 3.0 mmol/L) inhibited phosphoinositide breakdown, [Ca+2]i, and TxA2 formation in human platelets stimulated by collagen (1 microg/mL). In addition, inosine (1.5 and 3.0 mmol/L) markedly increased levels of cyclic guanylate monophosphate (GMP) and cyclic GMP-induced vasodilator-stimulated phosphoprotein Ser157 phosphorylation. Rapid phosphorylation of a platelet protein of molecular weight 47,000 (P47), a marker of protein kinase C activation, was triggered by collagen (1 microg/mL). This phosphorylation was markedly inhibited by inosine (3.0 mmol/L). Inosine (1.5 and 3.0 mmol/L) markedly reduced hydroxyl radical in collagen (1 microg/mL)-activated platelets. In in vivo studies, inosine (400 mg/kg) significantly prolonged the latency period of inducing platelet plug formation in mesenteric venules of mice, and administration of 2 doses (100 mg/kg) or a single dose (150 mg/kg) of inosine significantly attenuated MCAO-induced focal cerebral ischemia in rats.. Platelet aggregation contributes significantly to MCAO-induced focal cerebral ischemia. The most important findings of this study suggest that inosine markedly inhibited platelet activation in vitro and in vivo, as well as cerebral ischemia. Thus, inosine treatment may represent a novel approach to lowering the risk of or improving function in thromboembolic-related disorders and ischemia-reperfusion brain injury.

Topics: Animals; Brain Ischemia; Calcium; Cell Adhesion Molecules; Collagen; Contrast Media; Cyclic AMP; Cyclic GMP; Fluorescein; Free Radical Scavengers; Humans; Infarction, Middle Cerebral Artery; Inosine; Male; Mice; Microcirculation; Microfilament Proteins; Phosphatidylinositols; Phosphoproteins; Phosphorylation; Platelet Aggregation; Platelet Aggregation Inhibitors; Protein Kinase C; Rats; Rats, Wistar; Thrombosis; Thromboxane B2

The protective role of folate in vascular disease has been related to antioxidant effects. In 45 patients with previous early-onset (at age <50 years) thrombotic episodes and the 677TT methylenetetrahydrofolate reductase genotype, we evaluated the effects of a 28 d-course (15 mg/d) of 5-methyltetrahydrofolate (MTHF) on homocysteine metabolism and on in vivo generation of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha), a reliable marker of oxidative stress. At baseline, patients' fasting total homocysteine (tHcy) was 11.5 micromol/l (geometric mean) and urinary excretion of 8-iso-PGF2alpha was 304 pg/mg creatinine, with the highest metabolite levels in the lowest quartile of plasma folate distribution (P < 0.05). After 5-MTHF supplementation, plasma folate levels increased approximately 13-fold (P < 0.0001 versus baseline); tHcy levels (6.7 micromol/l, P < 0.0001) and urinary 8-iso-PGF2alpha (254 pg/mg creatinine, P < 0.001) were both significantly lowered, their reduction being proportional to baseline values (r = 0.98 and r = 0.77, respectively) and maximal in patients with the lowest pre-supplementation folate levels (P < 0.05). The effects on folate (P < 0.0001) and tHcy (P = 0.0004) persisted for at least up to 2 months after withdrawing 5-MTHF. In parallel with long-lasting tHcy-lowering effects, a short-course 5-MTHF supplementation reduces in vivo formation of 8-iso-PGF2alpha in this population, supporting the antioxidant protective effects of folate in vascular disease.

Topics: Adult; Age of Onset; Case-Control Studies; Dietary Supplements; Dinoprost; Female; Homocysteine; Humans; Linear Models; Male; Methylenetetrahydrofolate Reductase (NADPH2); Middle Aged; Mutation; Oxidative Stress; Tetrahydrofolates; Thrombosis; Thromboxane B2

Lycopene is a natural carotenoid antioxidant that is present in tomatoes and tomato products. The pharmacologic function of lycopene in platelets is not yet understood. Therefore, in this study we sought to systematically examine the effects of lycopene in the prevention of platelet aggregation and thrombus formation. We found that lycopene concentration-dependently (2-12 micromol/L) inhibited platelet aggregation in human platelets stimulated by agonists. Lycopene (6 and 12 micromol/L) inhibited phosphoinositide breakdown in platelets labeled with tritiated inositol, intracellular Ca+2 mobilization in Fura-2 AM-loaded platelets, and thromboxane B2 formation stimulated by collagen. In addition, lycopene (6 and 12 micromol/L) significantly increased the formations of cyclic GMP and nitrate but not cyclic AMP in human platelets. Rapid phosphorylation of a protein of 47,000 Da (P47), a marker of protein kinase C activation, was triggered by PDBu (60 nmol/L). This phosphorylation was markedly inhibited by lycopene (12 micromol/L) in phosphorus-32-labeled platelets. In an in vivo study, thrombus formation was induced by irradiation of mesenteric venules in mice pretreated with fluorescein sodium. Lycopene (5, 10, and 20 mg/kg) significantly prolonged the latency period for the induction of platelet-plug formation in mesenteric venules. These results indicate that the antiplatelet activity of lycopene may involve the following pathways: (1) Lycopene may inhibit the activation of phospholipase C, followed by inhibition of phosphoinositide breakdown and thromboxane B2 formation, thereby leading to inhibition of intracellular Ca+2 mobilization. (2) Lycopene also activated the formations of cyclic GMP/nitrate in human platelets, resulting in the inhibition of platelet aggregation. The results may imply that tomato-based foods are especially beneficial in the prevention of platelet aggregation and thrombosis.

Topics: Animals; Antioxidants; Blood Platelets; Blood Proteins; Carcinogens; Carotenoids; Cyclic AMP; Cyclic GMP; Humans; In Vitro Techniques; Lycopene; Mice; Microcirculation; Nitrates; Phorbol 12,13-Dibutyrate; Phosphatidylinositols; Phosphoproteins; Phosphorylation; Platelet Activation; Platelet Glycoprotein GPIIb-IIIa Complex; Thrombosis; Thromboxane B2

To observe the effect of phenolic alkaloids of Menispermum dauricum (PAMD) on thrombosis and platelet aggregation, and to explore its mechanism of action.. Thrombosis was observed with arteriovenous shunt thrombus model in rat; platelet aggregation was determined by Born's method; ultrastructure of platelet was observed by transmission electron microscope; TXB2 or 6-keto-PGF1alpha levels were assessed by radioimmunoassay; and NO was determined by colorimetric method.. PAMD dose-dependently inhibited experimental thrombus formation, platelet aggregation induced by ADP, AA and THR in vivo and ultrastructure changes stimulated by THR; PAMD increased the generation of 6-keto-PGF1alpha in thoracic aortae and NO level in plasma; and had no influence on TXB2 release (P > 0.05).. PAMD inhibited thrombosis and platelet aggregation, and its mechanism might be due to the increase of PGI2 and NO level.

Topics: 6-Ketoprostaglandin F1 alpha; Alkaloids; Animals; Aorta, Thoracic; Benzylisoquinolines; Blood Platelets; Dose-Response Relationship, Drug; Epoprostenol; Male; Menispermum; Nitric Oxide; Plants, Medicinal; Platelet Aggregation; Rabbits; Rats; Rats, Sprague-Dawley; Rhizome; Tetrahydroisoquinolines; Thrombosis; Thromboxane B2

Vein graft failure within the first month after bypass surgery is largely because of thrombosis. However, systemic study of thrombus formation in vein grafts is still lacking, and few effective techniques are available to prevent this event. Herein, we analyzed the kinetics of thrombosis and tested the effectiveness of locally applied aspirin on prevention of the disease in a mouse model. En face analysis of vein grafts revealed that 67+/-12% and 54+/-17% of the surface areas were covered by microthrombi at 1 and 3 days, respectively. Thrombus generation was also identified by labeling of platelets and fibrin, which occurred in 35 grafts examined at 1 and 3 days and 1, 2, 4, and 8 weeks. In a fifth of grafts, the thrombus occluded the vessel lumen by > or =1/4. Furthermore, a significant loss of endothelial cells was evidenced by beta-gal staining for vein grafts in transgenic mice expressing LacZ gene controlled by TIE2-endothelial specific gene promoter. Following thrombosis, neointimal lesions were significantly increased by 4-fold 2 weeks after the operation. When vein grafts were treated locally with aspirin in pluronic gel-127, the thrombus area was significantly reduced (P<0.005) at 1, 4, and 8 weeks. Interestingly, neointimal lesions were markedly reduced in the local, but not oral, aspirin-treated group at 4 and 8 weeks by 50% to 70% (P<0.005). The mechanism of reduced lesions by locally applied aspirin involved the protection of vein graft endothelium. Thus, we provide strong evidence that thrombus formation occurs before the development of neointimal lesions in vein grafts and that local aspirin treatment successfully reduces vein graft arteriosclerosis through endothelial protection, resulting in reduction of thrombosis.

Topics: Animals; Arteriosclerosis; Aspirin; Blood Vessel Prosthesis Implantation; Carotid Arteries; Disease Models, Animal; Endothelium, Vascular; Fibrinolytic Agents; Graft Occlusion, Vascular; Hyperplasia; Mice; Mice, Knockout; Mice, Transgenic; Platelet Aggregation Inhibitors; Postoperative Complications; Receptor, TIE-2; Thrombosis; Thromboxane B2; Tunica Intima; Venae Cavae

To study thrombosis and its significance after acute experimental pulmonary thromboembolism.. The acute pulmonary thromboembolism (PTE) model of rabbits was established by intravenous injection of autologous blood clots (0.04 g/kg) which were stabilized in temperature-controlled (70 degrees C) distilled water for 10 min. The process of thrombosis was observed grossly and microscopically. The Quick's method was used to examine the coagulability of blood and radioimmunoassay was employed to measure the level of plasma thromboxane A(2) and endothelin.. Thrombotic propensity was observed at 1 h, fresh thrombus started to form and the blood coagulation system was activated at 24 h following clots infusion. Emboli were completely or partly dissolved at 5 d and appeared to organize at both 10 d and 14 d after clots were infused. Venous plasma thromboxane A(2) concentration began to increase at 5 min (2489.59 +/- 714.68 ng/L) and reached its maximum at 15 min (2545.46 +/- 590.58 ng/L) then declined at 60 min after clot infusion (P < 0.001, respectively, vs 626.59 +/- 510.02 ng/L of pre-clot). The level of endothelin in both arterial and venous blood increased at 5 d post-clot infusion (840.74 +/- 154.19 ng/L, 230.35 +/- 52.39 ng/L, respectively) compared to the one before infusion (602.66 +/- 453.26 ng/L, 148.01 +/- 53.28 ng/L, respectively, P < 0.05).. Thrombosis occurs after autologous-blood-clot-induced PTE. The interactions between thrombus formation, fibrinolysis and organization determines the consequences of emboli. Abnormalities of endothelin metabolism and the increment of thromboxane A(2) may play an important role in PTE.

Topics: Animals; Blood Coagulation; Endothelins; Lung; Pulmonary Embolism; Rabbits; Thrombosis; Thromboxane B2

D-003 is a mixture of higher primary aliphatic saturated acids purified from sugarcane wax, with antiplatelet and antithrombotic effects experimentally demonstrated. Octacosanoic acid is the main component of D-003, followed by triacontanoic, dotriacontanoic, and tetracontanoic acids, while other acids are minor components. This work investigates the effects of combination therapy D-003+aspirin (ASA) on arachidonic acid (AA)-induced sudden death in mice and bleeding time in rats. In addition, the effects of D-003 on serum levels of two metabolites of AA: thromboxane A(2) and prostacyclin, assessed through the measurement of their stable metabolites: thromboxane B(2) (TxB(2)) and 6 keto PgF1alpha by radioimmunoassay kits, were also investigated. Combination therapy of D-003 (50mg/kg) and ASA (3mg/kg) significantly increased bleeding time in rats in a synergistic manner compared with D-003 or ASA alone. Moreover, the combined treatment of D-003 (200mg/kg) and ASA (5mg/kg) in mice protected against AA-induced sudden death (83% survivors) in a synergistic manner which was compared with each treatment alone (33% survivors). These results indicate that antiplatelet effects of D-003 are not mediated by a cyclooxygenase inhibition. D-003 and ASA monotherapies reduced serum TxB(2) levels, whereas D-003, but not ASA, significantly increased 6 keto PgF1alpha levels.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Aspirin; Death, Sudden; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Drug Therapy, Combination; Fatty Acids; Mice; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2

Diabetes mellitus (DM) is associated with enhanced lipid oxidation and persistent platelet activation. We investigated whether oxidant stress (OS) also affects circulating proteins and is associated with an abnormal coagulative pattern. In 72 type 2 DM (T2DM) patients, urinary 8-iso-prostaglandin (PG) F2alpha and 11-dehydro-thromboxane B2 (TXM) were measured as markers of lipid peroxidation and platelet activation, respectively. The carbonyl content of plasma proteins (PCARB) was measured as global index of protein oxidation. 8-Iso-PGF2alpha and PCARB levels were higher in DM patients than in controls (P < 0.05). Likewise, both TXM and prothrombin F1+2 levels were higher in diabetics (P < 0.05). By contrast, anticoagulant markers, such as activated protein C, protein C activation peptide, and soluble thrombomodulin (TM) were depressed in T2DM (P < 0.05). In conclusion, OS in T2DM involves circulating proteins and is associated with an unbalanced promotion of procoagulant reactions. These effects in concert with platelet activation may contribute to atherothrombotic complications in T2DM.

Topics: Aged; Aged, 80 and over; Biomarkers; Blood Proteins; Case-Control Studies; Diabetes Mellitus, Type 2; Dinoprost; F2-Isoprostanes; Female; Hemostasis; Humans; Lipid Peroxidation; Male; Middle Aged; Oxidation-Reduction; Oxidative Stress; Platelet Activation; Thrombosis; Thromboxane B2

The aim of this study was to compare the effects of a new thromboxane synthase inhibitor, camonagrel, on platelet aggregation and platelet-subendothelium interaction under flow conditions, in comparison with a standard thromboxane synthase inhibitor (dazoxiben) and a cyclooxygenase inhibitor (acetylsalicylic acid). With respect to platelet aggregation in whole blood, the 50% inhibitory concentrations (IC(50)) of camonagrel were between 318 and 797 micromol/l after induction with collagen and adenosine 5'-diphosphate, respectively. For inhibition of thromboxane B(2) synthesis, the IC(50) values were 868 +/- 68 micromol/l; prostaglandin E(2) was inhibited only by acetylsalicylic acid (IC(50) for camonagrel >2,000 micromol/l), and the leukocyte 6-keto-PGF(1alpha) level was increased by camonagrel. The greatest reduction in percentage subendothelial surface occupied by platelets (mainly in the thrombi) after blood perfusion was seen after incubation with camonagrel in the range of concentrations that inhibited collagen-induced platelet aggregation. In conclusion, camonagrel reduced platelet-subendothelium interaction under flow conditions, showing this effect in a range of concentrations lower than in inhibition of platelet aggregation.

Topics: Adolescent; Adult; Animals; Aspirin; Blood Platelets; Dose-Response Relationship, Drug; Humans; Imidazoles; Indans; Male; Middle Aged; Platelet Aggregation; Prostaglandins; Prostaglandins E; Rabbits; Thrombosis; Thromboxane B2; Thromboxane-A Synthase; Tunica Intima

To investigate associations between structural, functional and circulatory placental changes in pregnancies complicated by impaired glucose metabolism.. Umbilical artery (UA) blood flow resistance was measured by Doppler velocimetry in 21 gravidae with diabetes/impaired glucose tolerance (IGT) and 10 healthy gravidae. Umbilical and placental vessel segments were incubated for determination of prostacyclin and thromboxane synthesis, and tissues histologically examined. Non-parametric statistical tests at a two-tailed P<0.05 were used.. Placental lesions were more common in diabetes/IGT and, although not being an uniform finding, in general associated with a higher vascular synthesis of thromboxane and/or lower prostacyclin/thromboxane synthesis ratio. As an exception, ischemic villitis was associated with a higher ratio and higher UA flow resistance.. Placental lesions are associated with an altered vascular prostanoid synthesis in diabetes/IGT, but not until structural signs of ischemia develop is a rise of UA blood flow resistance detected.

Topics: 6-Ketoprostaglandin F1 alpha; Diabetes Mellitus, Type 2; Diabetes, Gestational; Female; Glucose Intolerance; Humans; Infarction; Ischemia; Placenta; Placenta Diseases; Pregnancy; Pregnancy in Diabetics; Thrombosis; Thromboxane B2; Umbilical Arteries; Vascular Resistance

Topics: Aspirin; Biomarkers; Cyclooxygenase Inhibitors; Drug Resistance; Humans; Platelet Aggregation; Platelet Aggregation Inhibitors; Predictive Value of Tests; Risk; Thrombosis; Thromboxane B2; Thromboxanes

Because shikimic acid is the key intermediate in the shikimate pathway in plants and microorganisms, shikimic acid and its derivatives have been described as herbicides and anti-microbial agents. Triacetylshikimic acid (TSA) is an acetylate derivative of shikimic acid. The possible anti-platelet activity and anti-thrombotic efficacy of TSA were evaluated and its effect on arachidonic acid (AA) metabolism and second messengers including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) was evaluated. After oral pretreatment with TSA, adenosine diphosphate (ADP)-, collagen-, and AA-induced rat platelet aggregation was inhibited ex vivo in a dose-dependent manner. In an arteriovenous-shunt thrombosis model, oral administration of TSA resulted in a dose-dependent inhibition of thrombus growth. TSA markedly increased the cAMP level and showed no effect on the cGMP level in rat platelets. Also, no significant changes in ADP-induced thromboxane B2 formation in rat platelets or 6-keto-prostaglandin F 1alpha production from the abdominal aorta were observed after oral administration of low and medium doses of TSA (12.5 and 50 mg/kg). Additionally, prothrombin time, activated partial thromboplastin time, and thrombin time were unchanged at effective anti-platelet doses of TSA. These results demonstrate that TSA exerts oral anti-platelet and anti-thrombotic efficacy without perturbation of systemic hemostasis in rats, which was partially concerned with the elevation of cAMP in platelets.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aorta, Abdominal; Aspirin; Blood Platelets; Cyclic AMP; Cyclic GMP; Male; Partial Thromboplastin Time; Platelet Aggregation Inhibitors; Prothrombin Time; Radioimmunoassay; Rats; Rats, Wistar; Shikimic Acid; Thrombin Time; Thrombosis; Thromboxane B2

Recent studies have shown that patients with antiphospholipid antibodies (aPL) have increased lipid peroxidation. We evaluated the urinary excretion of 11-dehydro thromboxane B2 (11-DH-TXB(2) and isoprostane F(2alpha)III (IPF(2alpha)III), reflecting platelet activation and lipid peroxidation in vivo, and plasma soluble markers of endothelial cell, platelet and blood coagulation activation: soluble vascular cell adhesion molecule-1 (sVCAM-1), P- and E-selectin (sPsel and sEsel), F1 + 2 fragment of prothrombin (F1 + 2), thrombin-antithrombin complexes (TAT) and D-Dimer (DD). We studied 79 patients with aPL (47 with previous thrombosis), 45 healthy volunteers (normal controls, NC), 12 patients with systemic lupus erythematosus (SLE) without aPL and a thrombosis control group (TCG) without thrombophilia (n = 16). Urinary levels (mean, range) of eicosanoids and isoeicosanoids were significantly increased in 39 patients with aPL compared with 25 NC, 11-DH-TXB(2) 164.0 ng/mmol creatinine (9.5-1162.8) versus 43.4 ng/mmol creatinine (4.2-87.6), P < 0.001; IPF(2alpha)III 56.9 pg/mg creatinine (5.5-388.7) versus 27.0 pg/mg creatinine (4.6-87.6), P = 0.03. Both metabolites were significantly correlated (rho = 0.49, P = 0.014), but none correlated with any clinical manifestation or antibody profile. The aPL group presented increased levels of sPsel, sEsel, sVCAM-1, TAT, F1 + 2 and DD, but any soluble marker correlated with IPF2alphaIII. Urinary 11-DH-TXB(2) correlated with sPsel (rho = 0.39, P = 0.04). Compared with SLE controls, the SLE group with aPL had higher levels of F1 + 2. Plasma levels of F1 + 2 and DD were significantly increased and a trend to higher sPsel was found in aPL patients with thrombosis compared with the TCG. Platelet activation, lipid peroxidation and blood coagulation activation seem to be important in the pathophysiology of antiphospholipid syndrome.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Antithrombins; Biomarkers; Blood Coagulation; Case-Control Studies; Chi-Square Distribution; Child; Child, Preschool; E-Selectin; Endothelium, Vascular; Female; Fibrin Fibrinogen Degradation Products; Humans; Isoprostanes; Lipid Peroxidation; Lupus Erythematosus, Systemic; Male; Middle Aged; P-Selectin; Platelet Activation; Prothrombin; Statistics, Nonparametric; Thrombosis; Thromboxane B2; Vascular Cell Adhesion Molecule-1

Magnesium (Mg) has been shown to reduce platelet aggregation both in vitro and ex vivo, and this antiplatelet effect may be advantageous in the prevention of arterial thrombosis. Previous animal studies have shown an antithrombotic effect of Mg also in vivo, but mainly with higher Mg concentrations ( approximately 3.0-4.0 mM). The objectives of the present study were to evaluate the antithrombotic effect of (1) intravenous Mg at a lower and clinically more relevant concentration and (2) topically applied Mg. The study comprised 30 male rats, randomly assigned into 3 groups: (1) placebo group, (2) intravenous Mg group, and (3) topical Mg group. A thrombogenic lesion was established by making a standardised arteriotomy in the right femoral artery. The vessel was transilluminated and thrombus formation was visualised dynamically by in vivo microscopy and recorded on videotapes. Thrombus area was measured after ended experiment by computer-assisted image analysis. Intravenously administered Mg, elevating the S-Mg level to 2.2 mmol/L, significantly reduced the mean thrombus area (p<0.05) compared to the control group. Topically applied Mg significantly decreased the maximum thrombus area, without any increase in S-Mg level (p<0.05). The Mg-treated groups showed no increase in bleeding complications. A transient fall in blood pressure was seen in the systemic Mg group, but blood pressures were not significantly different between any of the groups at the end of the experiment. In conclusion, topically as well as intravenously infused Mg reduce arterial thrombus formation in this in vivo rat model without compromising haemostasis.

Topics: Administration, Topical; Animals; Arterial Occlusive Diseases; Blood Pressure; Disease Models, Animal; Hemorrhage; Infusions, Intravenous; Magnesium; Male; Rats; Rats, Wistar; Thrombosis; Thromboxane B2

Microvascular thrombosis plays a significant role in the pathophysiology of ischaemic reperfusion injury. A fish oil-supplemented diet containing n-3 polyunsaturated fatty acids (PUFA) reduces thromboxane A(2) (TxA(2)) synthesis and, thus, vasoconstriction and platelet aggregation. The aim of this study was to elucidate whether n-3 PUFA in a porcine model of ischaemia and reperfusion injury 1) inhibit accumulation of platelets and fibrinogen in ischaemia-reperfusion injured tissue, 2) prolong the bleeding time, and 3) inhibit TxA(2) synthesis. Nine pigs were fed a standard diet supplemented with 7 g n-3 PUFA/day for 3 weeks. Nine pigs on the standard diet served as controls. Unilateral myocutaneous flaps were exposed to ischaemia for a period of 6 hours. Contralateral flaps were nonischaemic. Tissue contents of radioactive-labelled platelets and fibrinogen were measured after 4 hours of reperfusion. Platelet count, serum TxB(2), and the cutaneous bleeding time were measured before and after 3 weeks of diet. In the fish oil group, the accumulation of platelets was significantly reduced in all the myocutaneous flaps, except in the ischaemic skin part, when compared to control animals. Fibrinogen was significantly reduced in nonischaemic flaps, but not in ischaemic flaps. After the feeding period, the level of TxB(2) was significantly lowered in the fish oil group (p<0.01). No difference in the bleeding time was observed. Thus, dietary supplementation with n-3 PUFA inhibits the formation of microvasculatory thrombosis in this model.

Topics: Animals; Bleeding Time; Dietary Fats, Unsaturated; Disease Models, Animal; Fatty Acids, Omega-3; Fibrinogen; Fish Oils; Microcirculation; Platelet Count; Reperfusion Injury; Swine; Thrombosis; Thromboxane B2

An effective in vitro protocol for the investigation of thrombogenicity can provide many advantages in the development of mechanical circulatory assist devices. Strict avoidance of air contact with blood recently was proposed for reliable in vitro evaluation. This study was performed to confirm the necessity of avoidance of air contact for the in vitro test of thrombogenicity in a rotary pump. Two sets of mock circuits with the same rotary blood pumps, reservoirs, and connecting tubes were made. In one system, blood came in contact with air while the other did not. The test blood was heparinized at the dose of 1 IU per 1 ml of blood. The tests were terminated at an activated coagulation time of 1.5 times the control value. The levels of hematocrit, platelet, factors VIII and XII, fibrinogen, thromboxane B2, and plasma-free hemoglobin were measured during the procedures. After the experiments, the thrombi formed were observed, measured, and compared with those formed in in vivo circumstances. The tests were repeated 12 times. There were no statistically significant differences between the 2 groups in hematologic parameters and the amounts of thrombi formed. The thrombi observed in both groups showed the same pathologic findings as those formed in vivo with the exception of intermittent multiple air bubbles found in thrombi of the air-contact group. In conclusion, the effect of air contact in the in vitro investigation of thrombogenicity was negligible while the proposed in vitro test models of thrombogenesis in the mechanical circulatory assist device proved to be reliable.

Topics: Air; Anticoagulants; Assisted Circulation; Blood; Blood Coagulation; Equipment Design; Factor VIII; Factor XII; Fibrinogen; Hematocrit; Hemoglobins; Heparin; Humans; Platelet Count; Reproducibility of Results; Thrombosis; Thromboxane B2; Whole Blood Coagulation Time

We have shown previously that fresh garlic extract is effective in reducing thromboxane formation by platelets both in vivo and in vitro animal models of thrombosis. In the present study, the effect of different concentrations of a single dose of aqueous extracts of garlic and onion were evaluated on serum thromboxane-B(2)synthesis in rabbits. Different concentrations of garlic and onion were administered as single doses in the ear vein of rabbits. Rabbits were bled before and at different intervals after the infusion of garlic or onion extracts. Venous blood was collected and allowed to clot at 37 degrees C for 1 h. Thromboxane-B(2)level was measured in the serum by radioimmunoassay. It was observed that garlic inhibits the thrombin-induced platelet synthesis of TXB(2)in a dose-and time-dependent manner. Maximum inhibition of TXB(2)occurred between 0.5 h and 6 h at 25 and 100 mg kg(-1)garlic. At 24 h post-garlic infusion TXB(2)inhibition was reduced to 15% of the control and TXB(2)levels were comparable to that of the control values at 72 h pots-garlic infusion. Infusion of 100 mg kg(-1)onion extract did not elicit any inhibitory effect on TXB(2)synthesis in the serum of rabbit during the treatment period. The rapid recovery of platelet cyclooxygenase activity after infusion of a single dose of garlic suggests that garlic should be taken more frequently in order to achieve beneficial effects in the prevention of thrombosis.

Topics: Animals; Antithrombins; Blood Coagulation; Blood Platelets; Dose-Response Relationship, Drug; Female; Garlic; Injections, Intravenous; Onions; Phytotherapy; Plant Extracts; Plants, Medicinal; Platelet Aggregation Inhibitors; Prostaglandin-Endoperoxide Synthases; Rabbits; Radioimmunoassay; Thrombosis; Thromboxane B2; Time Factors

Olive oil is the main source of dietary fatty acids in the Mediterranean region. The objective of this study was to evaluate the effect of dietary supplementation with virgin olive oil in an experimental model with rabbits fed an atherogenic diet (saturated fat 48% of total fat). Four different groups of 10 animals each were studied: (1) normolipemic diet (NLD), (2) atherogenic diet or saturated fatty acid-enriched diet (SFAED), (3) NLD with 15% olive oil (NLD+OLIV), and (4) SFAED with 15% virgin olive oil (SFAED+OLIV). The animals were fed the experimental diets for 6 weeks, after which we determined serum lipid profile (total cholesterol, HDL-cholesterol, and triglycerides), platelet aggregation, platelet thromboxane B(2), aortic prostacyclin, and platelet and vascular lipid peroxidation. Scanning electron microscopic images of the vascular endothelium were studied, as were morphometric parameters in the arterial wall and thrombogenicity of the subendothelium (annular perfusion chamber). Animals fed the SFAED showed platelet hyperactivity and increased subendothelial thrombogenicity. Animals fed the SFAED+OLIV showed, compared with the SFAED group, an improved lipid profile with decreased platelet hyperactivity and subendothelial thrombogenicity and less severe morphological lesions of the endothelium and vascular wall. We conclude that supplementation of the SFAED with 15% olive oil reduced vascular thrombogenicity and platelet activation in rabbits. Although the percentage of olive oil in the diet was higher than the amount in the human diet, these results may be helpful in determining the effect of olive oil in the human thrombogenic system.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aorta; Arteriosclerosis; Cholesterol; Diet, Atherogenic; Disease Models, Animal; Drug Evaluation, Preclinical; Endothelium, Vascular; Fatty Acids; Fatty Acids, Unsaturated; Fibrinolytic Agents; Hyperlipidemias; Lipids; Male; Malondialdehyde; Microscopy, Electron, Scanning; Olive Oil; Plant Oils; Platelet Aggregation; Rabbits; Stress, Mechanical; Thrombosis; Thromboxane B2

The aim of this study was to assess thrombosis tendency in subjects who were habitual meat-eaters compared with those who were habitual vegetarians.. Cross-sectional comparison of habitual meat-eaters and habitual vegetarians.. Free living subjects.. One hundred and thirty-nine healthy male subjects (vegans n = 18, ovolacto vegetarians n = 43, moderate-meat-eaters n = 60 and high-meat-eaters n = 18) aged 20-55 y who were recruited in Melbourne.. Dietary intake was assessed using a semi-quantitative Food Frequency Questionnaire. The parameters of thrombosis were measured by standard methods.. Saturated fat and cholesterol intakes were significantly higher and polyunsaturated fat (PUFA) was significantly lower in the meat-eaters compared with vegetarians. In the meat-eaters, the platelet phospholipids AA levels were significantly higher than in the vegetarians, but there was no increase in ex vivo platelet aggregation and plasma 11-dehydro thromboxane B2 levels. Vegetarians, especially the vegans, had a significantly increased mean collagen and ADP stimulated ex vivo whole blood platelet aggregation compared with meat-eaters. The vegan group had a significantly higher mean platelet volume than the other three dietary groups. However, meat-eaters had a significantly higher cluster of cardiovascular risk factors compared with vegetarians, including increased body mass index, waist to hip ratio, plasma total cholesterol (TC), triacylglycerol and LDL-C levels, ratio of TC/HDL-C and LDL-C/HDL-C and plasma factor VII activity.. Consumption of meat is not associated with an increased platelet aggregation compared with vegetarian subjects.

Topics: Adult; Blood Coagulation Factors; Cross-Sectional Studies; Diet, Vegetarian; Fatty Acids; Feeding Behavior; Humans; Lipoproteins; Male; Meat; Middle Aged; Platelet Aggregation; Risk Factors; Thrombosis; Thromboxane B2

Because of the association of oral contraceptives (OC) and cigarette smoking with an increased thrombotic risk, we evaluated thromboxane (TX) and prostacyclin urinary (u) metabolites, as in vivo indices of platelet-vessel wall interactions, in women assigned to third generation OC. Twenty-eight women (15 smokers) underwent a 6-month trial of 30 microg ethinylestradiol plus 0.150 mg desogestrel. Cotinine plasma levels were elevated only in persons classified as smokers and serum TXB2 determination confirmed the absence of cyclooxygenase inhibition throughout the study. u-TXB2 and 11-dehydro-TXB2 were higher in smokers than in non-smokers. OC decreased u-11-dehydro-TXB2 both in smokers (from (pg/micromol creatinine) 35.1+/-6.9 to 15.8+/-2.8; P<0.025) and non-smokers (from 31.7+/-9.8 to 20.6+/-4.8, P = N.S.). u-6-keto-prostaglandin(PG)F1alpha excretion, also higher in smokers compared to non-smokers, was also reduced after OC in smokers (from (pg/micromol creatinine) 24.3+/-5.2 to 14.8+/-2.3; P<0.05). Smokers also had a trend to higher u-2,3-dinor-6-keto-PGF1alpha, marginally reduced by OC. Thus, the OC regimen used here improves - if anything - platelet vessel wall interactions as assessed by prostanoid production in vivo. The prothrombotic tendency associated with the use of OC in smokers does not appear to be mediated by changes in platelet-vessel wall interactions.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Blood Platelets; Blood Vessels; Contraceptives, Oral; Female; Humans; Risk Factors; Smoking; Thrombosis; Thromboxane B2

Thrombus formation in the carotid artery is one of the common causes of transient ischemic attacks and stroke. Platelet aggregation seems to be an essential component in these processes. The present study was conducted to determine the ability of cilostazol, a phosphodiesterase III inhibitor, to prevent formation of totally occlusive thrombus in a porcine carotid artery, in comparison with ticlopidine. Castrated male Yorkshire pigs were allocated to control (n=8), cilostazol (30 mg/kg, twice a day [b.i.d] for 2 days, n=8), and ticlopidine (50 mg/kg, b.i.d. for 3 days, n=7) groups. The endothelium of the right common carotid artery was injured with electrical stimulation (150 microA) without constriction and blood flow in this region was monitored by Doppler flow probe. Arterial blood was sampled during electrical stimulation for the measurement of platelet aggregation. Total occlusion rates within 240 minutes were 87.5% (7:8), 37.5% (3:8), and 85.7% (6:7) in the control, cilostazol, and ticlopidine groups, respectively. Compared with the control group, the time to total occlusion was significantly prolonged in the cilostazol group, but not in the ticlopidine group. Consistently, platelet aggregation was significantly inhibited only in the cilostazol group. Because ticlopidine increases blood flow in the intact carotid artery before injury to a greater extent than cilostazol, direct antiplatelet action is thought to be responsible for cilostazol's beneficial effect in preventing thrombotic occlusion. These results suggest that cilostazol may be useful for the inhibition of the thrombus formation in the carotid artery and for the prevention of cerebral ischemic events.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Animals; Carotid Arteries; Cilostazol; Cyclic Nucleotide Phosphodiesterases, Type 3; Disease Models, Animal; Electric Stimulation; Endothelium, Vascular; Hemodynamics; Male; Orchiectomy; Platelet Aggregation; Serotonin; Swine; Tetrazoles; Thrombosis; Thromboxane B2; Ticlopidine

To evaluate the mechanisms of thrombosis in the early stage of electrical injury.. Endothelin-1(ET-1), prostacylin(PGI2), platelet alpha-granule membrane protein (Gmp-140), thromboxane (TXB2), and plasminogen(PLG-A) were measured in 26 patients with electrical injury.. It was found that GMP-140 and ET-1 increased significantly(P < 0.01), PLG-A showed a significant change 2 weeks after the injury, while there was an imbalance between TXB2 and PGI2.. It is believed that change in one or several mediators mentioned above may trigger thrombosis after electrical injury.

Topics: Adolescent; Adult; Burns, Electric; Endothelin-1; Epoprostenol; Female; Humans; Male; Middle Aged; P-Selectin; Thrombosis; Thromboxane B2

We describe variations of 11-dehydrothromboxane B2(11-dehydro-TXB2) levels in human urine samples. Retinal vein occlusion (RVO) is a thrombotic disease in which the retinal vein is blocked by blood aggregations. We considered the possibility that 11-dehydro-TXB2 plays an important role in the formation of RVO. Thus, we determined the 11-dehydro-TXB2 levels in patients with RVO using gas chromatography/selected ion monitoring (GC/SIM) and compared them with those of healthy volunteers. The thromboxane levels in patients with RVO, who did not also have diabetes, were significantly higher than those in healthy volunteers. One cause of RVO may be the variation of thromboxane production. Furthermore, this GC/SIM method can be applied to the prevention and treatment of not only RVO, but also of general thrombosis.

Topics: Adult; Aged; Chromatography, Gas; Female; Humans; Male; Middle Aged; Retinal Vein Occlusion; Thrombosis; Thromboxane B2

Dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were compared for their effects on arterial thrombus formation in vivo using a well validated rat model. Platelet aggregation (triggered by collagen or adenosine diphosphate in whole hirudinized blood), thromboxane formation (TxB2) and platelet phospholipid fatty acid composition were measured also. Animals fed diets containing hydrogenated coconut oil or sunflower seed oil served as pro- and anti-thrombotic controls, respectively. In a first study, rats were fed a mixture of EPA and DHA ethyl esters (MIX) in increasing amounts and results indicated that 4% of n-3 fatty acids had an optimum reducing effect on thrombosis tendency. Dietary administration of MIX further resulted in a dose-dependent promotion of disaggregation after collagen-induced aggregation, which significantly correlated with the reduction in platelet TxB2 formation. In a subsequent comparative study, both EPA and DHA ethyl esters affected thrombosis tendency, platelet aggregation and TxB2 formation to a similar extent. In addition, both polyenes increased the apparent thromboxane A2-sensitivity of platelets, which appeared negatively related to arterial thrombosis tendency. We conclude that EPA and DHA have similar reducing effects on arterial thrombogenesis in vivo in rats and have comparable effects on the selected platelet functions in vitro.

Topics: Animals; Aorta, Abdominal; Collagen; Dietary Fats, Unsaturated; Disease Models, Animal; Docosahexaenoic Acids; Eicosapentaenoic Acid; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Thrombosis; Thromboxane B2

The effects of intragastric and intraduodenal copper-aspirin complex on rabbit platelet aggregation were observed by Born's method. Myers's method was used to evaluate the antithrombotic effect of copper-aspirin complex in mice. In-vitro copper-aspirin complex selectively inhibited arachidonic acid-induced platelet aggregation with an IC50 value (concentration resulting in 50% inhibition) of 13.2 microM (95% confidence limits 9.1-16.8 microM). Copper-aspirin complex (10 mg kg(-1) given intragastrically or intraduodenally) was more potent than aspirin in inhibiting arachidonic acid-induced platelet aggregation. Copper-aspirin complex (10 mg kg(-1)) had a stronger inhibitory effect and a longer duration of action when given intragastrically than when given intraduodenally. It was shown by radioimmunoassay that copper-aspirin complex significantly reduced the level of thromboxane B2 in plasma while markedly increasing that of 6-ketoprostaglandin F1alpha (6keto-PGF1alpha). Copper-aspirin complex (10 mg kg(-1) given intragastrically for 7 days) significantly reduced mouse mortality caused by intravenous injection of arachidonic acid. The results suggest that both in-vitro and in-vivo copper-aspirin complex is more potent in selectively inhibiting arachidonic acid-induced platelet aggregation than aspirin. When given intragastrically the complex has a more potent antiplatelet effect and a longer duration of action than when given intraduodenally. The antithrombotic effect of the complex was more potent than that of aspirin.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Aspirin; Copper; Drug Combinations; Female; In Vitro Techniques; Intubation, Gastrointestinal; Male; Mice; Molecular Structure; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Radioimmunoassay; Random Allocation; Thrombosis; Thromboxane B2

This animal study was designed to compare a collagen coated heparin bonded vascular graft (CHG) versus a collagen coated vascular graft (CG) regarding intraoperative blood loss and healing process. 24 polyester vascular grafts (12 CHG and 12 CG) of 6 mm in diameter and 5 mm in length were implanted between the common iliac and external iliac artery in 12 adult dogs. The grafts were explanted between the first and the sixth months which followed the implantations. The healing process was observed by gross examination, microscopic and scanning electron microscopic examination. Prostaglandin PGE2, TXB2, 6 keto PGF1 alpha and PGF2 alpha were measured by radioimmunologic assay from samples retrieved from the medium part of the graft. During implantation, there was no notable difference in blood loss through the graft. At the time of explantation, 20 grafts were patent (10 CHG, 10 CG). In both grafts, the healing process developed progressively between 2 and 6 months and 90% of the internal surface of the grafts were covered with endothelial like cells. At 6 months, the internal layer was thinner in heparinized graft. PGI2 secretion was found with the two types of grafts. In conclusion, the present study showed no difference in the blood loss or healing characteristic of CHG and CG except for a potentially thinner internal layer with CHG. Comparative studies in humans are necessary to evaluate the potential benefit of heparin bonded graft in clinical practice.

Topics: 6-Ketoprostaglandin F1 alpha; Anastomosis, Surgical; Animals; Blood Loss, Surgical; Blood Vessel Prosthesis; Collagen; Dinoprost; Dinoprostone; Dogs; Epoprostenol; Graft Occlusion, Vascular; Heparin; Iliac Artery; Microscopy, Electron, Scanning; Polyesters; Radioimmunoassay; Thrombosis; Thromboxane B2; Vascular Patency

Prostaglandin (PG) E1 has been shown to improve thromboresistance. This experiment was designed to examine whether an effect on the arterial wall or the platelets is responsible for this phenomenon. Using a cross-perfusion model, the aortic and iliac artery endothelium of rabbits was removed by a balloon catheter before being perfused with blood of donor rabbits. Donor and/or receiver animals were treated with 20 microg PGE1 or vehicle (cyclodextrin) intravenously daily for 1 week. After the last administration of PGE1 or its vehicle, the animals were killed and native blood from a donor rabbit was recirculated (30 ml/min) via a deendothelialized segment of a receiver rabbit. The contact (C) and spread (S) platelets as well as the denuded surface covered with platelet aggregates (> 5 microm in height) were quantified by morphometry. Deposition of (111)In-oxine labeled autologous platelets was quantitatively determined per surface unit. In addition, PGI(2)- and TXB2-formation by the denuded aortic and iliac artery segments was determined. Pretreatment of receiver rabbits with PGE1 resulted in morphometrically assessed decreased platelet adhesion and aggregation, even when the donor rabbit was vehicle-treated. A vehicle-treated receiver rabbit, in contrast, shows platelet deposition comparable to controls, even if the donor rabbit was PGE1-pretreated. Treatment of donor animals with PGE1 did not result in a reduction in thrombogenicity. The beneficial in vivo PGE1 action of decreased arterial thrombogenicity is thus mediated by an effect on the vascular wall rather than on circulating platelets.

Topics: 6-Ketoprostaglandin F1 alpha; Alprostadil; Animals; Arteries; Blood Platelets; Endothelium, Vascular; Epoprostenol; Male; Organometallic Compounds; Oxyquinoline; Perfusion; Platelet Adhesiveness; Platelet Aggregation; Rabbits; Thrombosis; Thromboxane B2

Improved cardiovascular morbidity and mortality have been observed in several clinical studies of dietary supplementation with coenzyme Q10 (CoQ10, ubiquinone). Several mechanisms have been proposed to explain the effects of CoQ10. One attractive theory links ubiquinone with the inhibition of platelets. The effect of CoQ10 intake on platelet surface antigens, and certain hemostatic parameters was examined in 15 humans and 10 swine. Study participants received 100 mg of CoQ10 twice daily in addition to their usual diet for 20 days resulting in a three-fold increase of total serum CoQ10 level. We observed a decline in plasma fibronectin (-20.2%), thromboxane B2 (-20.6%), prostacyclin (-23.2%), and endothelin-1 (-17.9%) level. Significant inhibition of vitronectin receptor expression was observed consistently throughout ubiquinone treatment. Inhibition of the platelet vitronectin receptor is a direct evidence of a link between dietary CoQ10 intake, platelets, and hemostasis. These findings may contribute to the observed clinical benefits by a diminished incidence of thrombotic complications in such patients.

Topics: Animals; Coenzymes; Down-Regulation; Endothelin-1; Epoprostenol; Female; Fibronectins; Hemostasis; Humans; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Membrane Glycoproteins; Receptors, Vitronectin; Swine; Thrombosis; Thromboxane B2; Ubiquinone

Topics: Humans; Myeloproliferative Disorders; Platelet Activation; Syndrome; Thrombosis; Thromboxane B2

We previously identified a receptor for granulocyte colony-stimulating factor (G-CSFR) on platelet membranes, and reported that G-CSF enhanced ADP-induced platelet aggregation. Here, we investigated the priming effect of G-CSF on the hemostatic system in healthy volunteers given G-CSF. Following the administration of rhG-CSF (10 micrograms/kg for 30 min div) to 10 healthy volunteers, we found a significant elevation in the maximum platelet aggregation rate induced by ADP or collagen, thromboxane B2 level and amount of thrombin-antithrombin III complex. The D-D dimer and plasminogen activator inhibitor-1 showed no significant changes. These observations indicate that G-CSF administration may induce hypercoagulability in susceptible subjects. Therefore, patients or donors at risk of thrombosis or hypercoagulable state should be followed carefully after G-CSF administration.

Topics: Adenosine Diphosphate; Adult; Antithrombin III; Collagen; Filgrastim; Granulocyte Colony-Stimulating Factor; Hemostasis; Humans; Male; Middle Aged; Peptide Hydrolases; Platelet Aggregation; Recombinant Proteins; Thrombosis; Thromboxane B2

The experiment was conducted with SD male rats. After they had been each given an intravenous injection of high molecular weight dextran (0.8 ml/100 g body wt) once a day for 4 days, they were brought under the observation of ECG and mesentery microcirculation. Microthrombi were found in the venules and capillaries of each rat of the experimental group, while in the microcirculation of the control group rats, no microthrombi were found. No changes were found in the ECGs of the rats (n = 6) in the control group after the injections, while the rats in the subject group all suffered a rise in the S-T segment of ECG, an indication of myocardial injuries. The rise was significantly in positive correlation to the increase in microthrombi in number (r = 0.944, P < 0.01). The erythrocytes of the rats in the subject group clustered to become rouleau-like, and platelets aggregated by tens and hundreds to form microthrombi. Their blood also showed a significant decrease in number of platelets. The degree of platelet aggregation and the scores of the rise on ECG were significantly in positive correlation as shown by the results: y = 20 + 94x, r = 0.94, P < 0.01. The plasma TXB2 of the subject group increased obviously but the change of 6-K-PGF1 alpha in the blood was not significant. The content of plasma TXB2 and the scores that indicated the rise in the S-T segment of the ECG showed significantly a positive correlation by the analysis of linear regression equation: y = 109.997 +/- 116.25x, r = 0.889, P < 0.05. The activity of Na(+)-K(+)-ATPase on the myocardial cell membranes of the rats with microthrombi was significantly reduced as compared with that of the rats in the control group (P < 0.01). The activity of the Na(+)-K(+)-ATPase was significantly in negative correlation to the rise in the S-T segment of ECG (P < 0.05). This study demonstrates that the above changes are the causes of myocardial injuries in rats with circulatory thrombi.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Dextrans; Electrocardiography; Erythrocyte Aggregation; Heart Diseases; Male; Microcirculation; Myocardium; Rats; Sodium-Potassium-Exchanging ATPase; Thrombosis; Thromboxane B2

Antiphospholipid antibodies, particularly anticardiolipin antibodies (aCL) are autoantibodies frequently detected in the serum of patients with systemic lupus erythematosus (SLE) and the primary antiphospholipid antibody syndrome (PAPS). These patients commonly suffer from thrombosis, recurrent fetal loss and thrombocytopenia. Since platelet aggregation is pivotal in the genesis of thrombosis, we tested the hypothesis that perturbation of platelet membrane by aCL/beta 2-glycoprotein (aCL/beta 2GP) complex could trigger the biosynthesis of TXA2, a proaggregatory metabolite of AA. The preincubation of 14C-arachidonic acid (14C-AA)-labeled platelet pellets (14C-PP) from normal individuals with aCL alone followed by incubation with thrombin, resulted in a moderate increase in platelet thromboxane B2 (14C-TXB2) biosynthesis when compared to controls (without aCL). Similar incubations with beta 2GP-I alone resulted in negligible 14C-TXB2 biosynthesis. In contrast, the preincubations of normal 14C-PP with aCL/beta 2GP-I complex resulted in marked thrombin-induced TXB2 biosynthesis, underscoring the requirement of beta 2GP-I in aCL-induced platelet TXB2 biosynthesis. Taken together, these results are consistent with the view that aCL/beta 2GP-I platelet interactions do play a role, at least in part, in platelet hyperactivity and thrombosis in antiphospholipid antibody syndrome.

Topics: Adult; Antibodies, Anticardiolipin; Antiphospholipid Syndrome; Aorta; beta 2-Glycoprotein I; Blood Platelets; Chromatography, Affinity; Chromatography, Ion Exchange; Dose-Response Relationship, Drug; Drug Synergism; Female; Glycoproteins; Humans; Nerve Tissue Proteins; Thrombin; Thrombosis; Thromboxane A2; Thromboxane B2

Prostacyclin (PGI2) and thromboxane A2 (TXA2) play an important role in the pathophysiology of various cardiovascular diseases. The balance between PGI2 and TXA2 regulates the interaction between platelets and the vessel wall in vivo. In this study we measured PGI2 and TXA2 synthesis by analysing their urinary index metabolites 2,3-dinor-6-keto-PGF1 alpha and 11-dehydro-TXB2, respectively, in acute (10 patients) and chronic (10 patients) lower limb ischaemia. Both PGI2 and TXA2 synthesis were increased about two-fold in patients with acute lower limb ischaemia compared to chronic lower limb ischaemia. However, the PGI2/TXA2 ratio was more or less the same in acute and chronic lower limb ischaemia. In patients with acute lower limb ischaemia caused by thrombotic occlusion, PGI2 and TXA2 formation were about two times higher than in patients with acute lower limb ischaemia caused by embolic occlusion. Elevation of PGI2 and TXA2 synthesis in acute lower limb ischaemia may reflect increased platelet-vascular wall interactions without changing the PGI2/TXA2 ratio.

Topics: 6-Ketoprostaglandin F1 alpha; Aged; Aged, 80 and over; Chronic Disease; Creatinine; Epoprostenol; Extremities; Female; Humans; Ischemia; Male; Middle Aged; Thrombosis; Thromboxane A2; Thromboxane B2

The effect of the consumption of a fresh clove of garlic on platelet thromboxane production was examined. A group of male volunteers in the age range 40-50 years participated in the study. Each volunteer consumed one clove (approximately 3 g) of fresh garlic daily for a period of 16 weeks. Each participant served as his own control. Thromboxane B2 (TXB2, a stable metabolite of thromboxane A2), cholesterol and glucose were determined in serum obtained after blood clotting. After 26 weeks of garlic consumption, there was an approximately 20% reduction of serum cholesterol and about 80% reduction in serum thromboxane. No change in the level of serum glucose was observed. Thus, it appears that small amounts of fresh garlic consumed over a long period of time may be beneficial in the prevention of thrombosis.

Topics: Adult; Blood Glucose; Blood Platelets; Cholesterol; Garlic; Humans; Male; Middle Aged; Plants, Medicinal; Thrombosis; Thromboxane B2

The effects of neferine (Nef), taurine (Tau) and Nef + Tau on platelet aggregation and generation of thrombosis were investigated in rats. Using turbidimetry Nef and Tau were found to inhibit platelet aggregation induced by adenosine diphosphate (ADP), collagen or thrombin. Both drugs reduced the wet weight of experimental thrombosis. But the drugs showed no obvious effect on fibrinogen content and euglobulin lysis time. Thromboxane A2 (TXA2) production induced by ADP and prostacyclin (PGI2) were studied by enzyme immunoassay in rats. TXA2 generation in platelet rich plasma from rats treated with Nef and Nef + Tau obviously decreased. While the plasma PGI2 was not affected. Nef + Tau iv in 30 min significantly decreased the level of total cholesterin in serum. The results suggest that Nef has inhibitory effect on platelet aggregation and thrombosis formation. The combination of both drugs was found to be more potent than either one alone. The mechanism may be related to its reduction of TXA2 formation.

Topics: 6-Ketoprostaglandin F1 alpha; Alkaloids; Animals; Benzylisoquinolines; Blood Platelets; Cholesterol; Drug Synergism; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Sprague-Dawley; Taurine; Thrombosis; Thromboxane B2

Anti-Cerebral Thromboembolism Injection (ACTI), applied intravenously in Cattaneo's animal model of arterial thrombosis, could significantly reduce the weight of thrombus, blood viscosities, plasma TXB2 level and delay the prothrombin time, compared to control group (P < 0.05). From this trial, it was indicated that ACTI's reducing thrombosis action was the result of inhibiting aggregation and releasing of platelets through reducing whole blood viscosities and TXB2 level.

Topics: Animals; Blood Viscosity; Drugs, Chinese Herbal; Female; Fibrinolytic Agents; Male; Prothrombin Time; Rabbits; Thrombosis; Thromboxane B2

Disorders in arterial production of PGI2 and NO occur in atherosclerosis. Exogenous PGI2 and NO are capable of interacting pharmacologically. We claim that no such direct interactions occur between endogenous endothelial PGI2 and NO. Studying mechanisms of cardiac reactive hyperemia in guinea pigs and of thrombolysis in cats, we surmise that in vivo vascular intima releases PGI2 intraluminally while NO is secreted abluminally and thus these two ephemeral mediators do not see each other. Hence, in any disease, the disturbances in endothelial generation of PGI2 or NO have to be scrutinized separately. It may well be that endogenous PGI2 maintains endothelial thromboresistance while NO controls arterial myocytes and tissues in which microcirculation is embedded. These responsibilities remain unshared. Interactions between PGI2 and NO are confined to pharmacological domains.

Topics: Animals; Arteriosclerosis; Blood Pressure; Cats; Coronary Disease; Cyclic GMP; Epoprostenol; Guinea Pigs; Hyperemia; In Vitro Techniques; Male; Myocardium; Nitric Oxide; Thrombosis; Thromboxane B2

We investigated whether the vessel wall or platelets are primarily responsible for the decreased thrombogenicity induced by the calcium channel blocker isradipine after endothelium removal. In a cross-perfusion model, rabbit aorta and iliac artery endothelium of receiver animals were removed by balloon catheter before being perfused with the blood of the blood donor rabbits. Donor and/or receiver animals were treated with 0.3 mg/kg isradipine intravenously (i.v.) daily for 1 week or with 10 mg acetylsalicylic acid (ASA) in addition. The other animals received vehicle only or ASA. The animals were divided into four groups (I-IV, total n = 24) consisting of four subgroups of 6 animals each. In all, 96 rabbits were examined. Immediately after the last administration of the respective drug, native blood from a donor rabbit was circulated (30 ml/min) through a deendothelialized segment of a receiver rabbit. The contract (C) and spread (S) platelets as well as the denuded surface covered with platelet aggregates (> 5 microns high) were quantified by morphometry. Deposition of [111In]oxine-labeled platelets was quantitatively determined per surface unit. In addition, prostaglandin I2 (PGI2) formation by the denuded aortic and iliac artery segment was determined. In group I, receiver rabbit pretreatment with isradipine exhibited decreased adhesion and aggregation of platelets, even when the donor rabbit was treated with solvent or ASA. In group II, concomitant treatment of donor animals with ASA and isradipine had no significant effect, whereas ASA isradipine treatment of receiver animals enhanced thrombogenicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Arteries; Aspirin; Blood Platelets; Endothelium, Vascular; Epoprostenol; Humans; In Vitro Techniques; Indium Radioisotopes; Isradipine; Male; Perfusion; Rabbits; Thrombosis; Thromboxane B2

24 model rabbits with femoral arterial thrombosis were divided into two groups: the treatment group consisting of 12 rabbits which received API0134, and the control group composed of another 12 rabbits. 2 hours after recanalization by urokinase thrombolysis, reocclusion occurred only in 1/12 vessel (8%) with incomplete occlusion in the treated group, but in 8/12 (67%) with complete occlusion in the control group as assessed by angiograsphy. Pathological examination of specimen taken 24 hours after thrombolysis showed that 6/12 (50%) of the treated group gave the evidence of thrombus occlusion, and milder intimal injury and less adhered blood cells than in the control group, 83% of which had thrombus occlusion. In comparision with the control group, the function of platelet in the treated group demonstrated lower platelet aggregation rate (PAgR) and plasma thromboxane A2 (TXA2) level, higher prostacyclin (PGI2) and plasminogen activator (PA) activity as well as lower plasminogen activator inhibitor (PAI) activity. From the above it may be concluded that the preventive effect of API0134 on reocclusion might be due to inhibition of platelets aggregation and promotion of fibrinolysis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Drugs, Chinese Herbal; Femoral Artery; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Thrombolytic Therapy; Thrombosis; Thromboxane B2; Urokinase-Type Plasminogen Activator

This study was designed to determine whether dietary linoleate and all-rac-alpha-tocopheryl acetate (vitamin E) interact to affect serum thromboxane A2 (TXA2) and prostacyclin (PGI2) status and therefore, thrombogenic potential. 6 groups of 12 weanling male Sprague-Dawley rats were fed semipurified diets containing 11 or 18% of energy from linoleate and 0, 100 or 5000 mg vitamin E/kg diet for 10 weeks. Platelet and serum alpha-tocopherol concentrations increased logarithmically with increasing dietary vitamin E. Serum TXA2, measured as TXB2, platelet arachidonate and thiobarbituric acid reactive substances were significantly greater in the vitamin E deficient groups than in groups receiving vitamin E (p < 0.05). Serum PGI2 levels, determined as 6-keto-PGF1 alpha, were not affected by diets. No interaction was found between dietary linoleate and vitamin E. However, vitamin E supplementation produced significantly less serum TXB2 than did vitamin E deficient diets (p < 0.05). Vitamin E deficiency may be prothrombogenic by increasing platelet arachidonate, lipid peroxidation and serum TXA2 levels while vitamin E supplementation at levels used in this study may decrease such effects.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Blood Platelets; Epoprostenol; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Male; Rats; Rats, Sprague-Dawley; Thiobarbituric Acid Reactive Substances; Thrombosis; Thromboxane A2; Thromboxane B2; Vitamin E; Vitamin E Deficiency

Tetrahydroberberine (THB), an alkaloid extracted from Corydalis ambigua, inhibited the rabbit platelet aggregation triggered by arachidonic acid (AA), ADP, and collagen with IC50 of 0.86, 1.31, and 1.10 mmol.L-1, respectively. THB reduced the thromboxane B2 (TXB2) generation in rabbit platelet-rich plasma triggered by AA. THB 30 mg.kg-1.d-1 ip for 3 or 5 d restrained the ADP-induced platelet aggregation in rats. THB 30 mg.kg-1.d-1 ip for 1, 3, or 5 d inhibited the AA-induced platelet aggregation in rats. THB 15-30 mg.kg-1 iv showed an inhibition of venous thrombosis in rats. The results show that THB is a potent inhibitor of platelet aggregation in vitro and in vivo and is a promising antithrombotic drug.

Topics: Adenosine Diphosphate; Animals; Arachidonic Acids; Berberine; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2

We have recently demonstrated that contact activation of the intrinsic coagulation cascade in vitro is accompanied not only by thromboxane (TX) B2 generation but also by the formation of 5-lipoxygenase-derived cysteinyl-leukotrienes (LT). In our present study we have investigated the effects of the vascular wall on the eicosanoid formation by whole human blood. Incubation of whole human blood in clamped segments of autologous umbilical veins incubated in oxygenated Tyrode solution led to a time-dependent generation of cysteinyl-LT and TXB2 in the blood samples. A clear dissociation in the time-dependent production profiles was observed with cysteinyl-LT practically reaching a plateau phase at 60 min while TXB2 levels increased up to 90 min. In blood samples incubated in glass tubes for 60 min TXB2 production was about 13 times higher and cysteinyl-LT formation only about half as much as in the umbilical vein segments indicating a differential stimulation of both the cyclooxygenase and 5-lipoxygenase pathway of arachidonic acid metabolism in these experiments. By reverse phase HPLC the immunoreactive cysteinyl-LT were identified as a mixture of LTC4, LTD4 and LTE4. Since the data were suggestive of intravascular cysteinyl-LT formation in thrombotic vessels, thrombus specimens from patients with acute deep vein thrombosis of the lower limb were analysed for these compounds by combined reverse phase HPLC and specific radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Arachidonate 5-Lipoxygenase; Blood Coagulation; Constriction; Humans; Infant, Newborn; Leukotriene C4; Leukotriene D4; Leukotriene E4; Thrombophlebitis; Thrombosis; Thromboxane B2; Umbilical Veins

The principal causes of failure of a pancreas transplant are rejection and vascular thrombosis. There is an unusually high attrition rate for pancreas transplants, but study models have been difficult to develop. In a rat model that allows study of acute rejection to the exclusion of nonspecific effects of transplant surgery on the pancreas, in vitro synthesis of prostacyclin (PGI2) and thromboxane A2 (TXA2) by transplanted pancreas and the blood vessels transplanted with it was measured using an RIA for their stable hydrolysis products 6-keto-prostaglandin F1 alpha and thromboxane B2 (TXB2). TXB2 synthesis was significantly greater in allotransplanted pancreas than isotransplanted pancreas from the 5th day after transplantation. Rejection was complete in the allografted group 7-9 days after transplantation. 6-Keto-prostaglandin F1 alpha synthesis was similar in the pancreas for both allografts and isografts. Similar changes were seen in aorta, celiac artery, superior mesenteric artery, and portal vein transplanted with the pancreas. In the transplanted aorta, TXB2 was significantly greater in the allograft group from the third posttransplant day. A group of CsA-treated allografts sampled after 9 days had transplanted pancreatic parenchymal and vascular prostanoid synthesis in the isograft range. The changes in PGI2 and TXA2 synthesis that accompany cellular rejection may mediate vascular failure in rejecting pancreas transplants, and changes in PGI2 and TXA2 synthesis in blood vessels transplanted with the pancreas could promote early vascular thrombosis.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Disease; Animals; Aorta; Celiac Artery; Cyclosporine; Epoprostenol; Graft Rejection; Male; Mesenteric Artery, Superior; Pancreas; Pancreas Transplantation; Rats; Rats, Inbred Strains; Thrombosis; Thromboxane A2; Thromboxane B2; Transplantation, Homologous; Transplantation, Isogeneic; Vena Cava, Inferior

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested for its effects in vitro on dog platelet function and in vivo on femoral arterial thrombus formation in dogs. KRDS inhibited ADP (8 microM)-induced platelet aggregation (IC50: 350 microM) and arachidonic acid (2 mM)-induced thromboxane B2 generation (IC50: 175 microM). In addition, the thrombin (0.2 U/ml)-induced serotonin release was inhibited by KRDS (IC50: 525 microM) and the expression of alpha-granule membrane protein (GMP-140) was also inhibited (IC50: 350 microM). The results show that KRDS is an inhibitor for platelet aggregation and secretion to which the inhibition is more potent. Meanwhile, in the experiment of arterial thrombosis in dogs, KRDS (5 microM/kg) and 125I-SZ-51 (a monoclonal antibody against GMP-140) were injected before operation and immediately after the thrombus formation, respectively. In the KRDS group, the weight of removed thrombi was reduced to 50% of that in controls and the radioactivity per mg of labeled thrombi to 33.3% while in blood the radioactivity increased 2 times that in controls at the 4th hour after the injection of 125I-SZ-51. The radioactivity ratio between removed thrombi and blood was only 16% of that in controls. These results indicate that KRDS can inhibit thrombus formation in vivo and is a promising antithrombotic agent.

Topics: Amino Acid Sequence; Animals; Blood Platelets; Dogs; Fibrinolytic Agents; Lactoferrin; Molecular Sequence Data; P-Selectin; Peptide Fragments; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Membrane Glycoproteins; Serotonin; Thrombosis; Thromboxane B2

The effects of a new antithrombotic compound, PCA-4230, versus ticlopidine were investigated using an experimental thrombosis and vascular endothelial injury model in rats. Both PCA-4230 and ticlopidine protected rat arteries from the formation of prominent thrombi and most of microthrombi without modifying the formation of a first platelet monolayer. Neither coagulation parameters nor fibrinolysis were modified by these antithrombotic drugs. Neither PCA-4230 nor ticlopidine affected thromboxane A2 production in rats, whereas unlike PCA-4230, ticlopidine inhibited ex vivo fibrinogen binding to the fibrinogen receptor found on the platelet membrane. In conclusion, PCA-4230 and ticlopidine inhibited thrombus formation in vivo by a platelet-dependent mechanism which may be different for one or the other drug in spite of the fact that the protective effect measured in this thrombosis model is quite similar for either PCA-4230 or ticlopidine. The above-mentioned results clearly show that PCA-4230 is a new potent agent with both antivascular-damaging and antiplatelet activities, and devoid of effects on coagulation and fibrinolytic systems.

Topics: Animals; Blood Platelets; Carotid Arteries; Dihydropyridines; Fibrinogen; Fibrinolytic Agents; Male; Platelet Membrane Glycoproteins; Rats; Rats, Sprague-Dawley; Thrombosis; Thromboxane B2; Ticlopidine

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aspirin; Blood Platelets; Disease Susceptibility; Female; Humans; Male; Random Allocation; Thrombosis; Thromboxane B2; Time Factors

Platelet aggregation (PA) induced by ADP, collagen and epinephrine, plasma levels of beta-thromboglobulin (beta TG) and thromboxane B2 (TXB2) and serum TXB2 generation were studied in 11 patients with primary thrombocytosis (7 with essential thrombocythaemia and 4 with polycythaemia vera) and compared with 16 healthy subjects. 5 patients suffered from peripheral vascular ischaemia and another 3 had venous thrombosis, but none had bleeding complications. The patients showed an abnormal pattern of platelet function and of thromboxane generation distinct from the healthy subjects in three aspects. a) Shape change was 5-26 times greater, the lag-time of collagen PA was 2.3-2.9 times longer and the extent of epinephrine PA was nil or very low. ADP- or collagen-induced PA was also reduced (p less than 0.02). b) Plasma TXB2 generation (corrected to a normal platelet concentration) stimulated by the three PA inducers was within the range of the healthy subjects in spite of the reduced extent of PA. c) Plasma beta TG level and serum TXB2 generation (both corrected to a normal platelet concentration) were 2.9-7.1 times higher (p less than 0.001) indicating enhanced in vivo platelet activation and possibly increased thrombin generation. These abnormalities were not detected in another 4 patients with secondary thrombocytosis. The abnormal pattern of platelet function and thromboxane generation can be a useful laboratory method in the evaluation of patients with primary thrombocytosis. It might also explain the thrombotic complications which occurred in 8 of the patients in a manner such that increased or normal TXB2 generation overcomes the reduced extent of PA. In this respect, the pronounced serum TXB2 synthesis might be a marker of intravascular thrombosis.

Topics: beta-Thromboglobulin; Female; Humans; Ischemia; Male; Middle Aged; Platelet Aggregation; Thrombocytosis; Thrombosis; Thromboxane B2

The aim of this study is to prove the existence of a major tendency of platelet aggregation in elderly patients compared to medium-aged adults and, also, to detect whether it is affected by the presence of diabetes mellitus. Plasmatic concentrations of B2 thromboxane (TXB2) and antithrombin III (AT III) were determined in 73 elderly patients of both sexes; 56 without metabolic disease known (Group a) and 17 diabetic patients, 7 type I (Group bI) and 10 of type II (Group bII); and 12 healthy adults (control group). Medium plasmatic concentration of TXB2 was significantly higher (p less than 0.001) in Group a (55 +/- 14 ng/ml) compared to the control group (37 +/- 9 ng/ml) and there was no difference between Group bI (53 +/- 19 ng/ml) and bII (57 +/- 15 ng/ml). No variations were noted in ATIII concentration between the adults (27.4 +/- 2.3 mg/dl) and elderly patients (a = 29.6 +/- 4.4, bI = 29 +/- 2.6, bII = 31.2 +/- 5.9 mg/dl). In elderly patients, there appears to be a state of platelet pro-aggregation without influence of any risk factor, such as diabetes. This could explain the thrombogenic tendency of this age group.

Topics: Aged; Antithrombin III; Female; Humans; Male; Platelet Aggregation; Thrombosis; Thromboxane B2

Rhyncophylline (Rhy) produced a potent inhibition of rat platelet aggregation in ex vivo. TXA2 generation in platelet rich plasma from rats treated with Rhy obviously decreased in the collagen-induced group, but was not altered in the AA-induced group. These results suggest that Rhy suppressed the release of AA from platelet phospholipids stimulated by collagen, and this may be one of the mechanisms related to its action on platelet aggregation. Pretreatment with ASA, but not Rhy, reduced plasma PGI2 in rats. In the in vitro system, the PGI2 synthesis in rat aorta was shown to be inhibited by ASA but was not by Rhy. Rhy significantly reduced the number of mice died due to thrombosis by platelet aggregates. ASA prevented collagen plus adrenaline induced thrombotic death while Rhy prevented both ADP and collagen plus adrenaline induced thrombotic death.

Topics: 6-Ketoprostaglandin F1 alpha; Alkaloids; Animals; Drugs, Chinese Herbal; Indole Alkaloids; Oxindoles; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Inbred Strains; Thrombosis; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Dogs; Pancreas Transplantation; Platelet Aggregation; Thrombophlebitis; Thrombosis; Thromboxane B2; Time Factors

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Dogs; Epoprostenol; Organ Preservation; Pancreas; Pancreas Transplantation; Regional Blood Flow; Splenic Artery; Thrombosis; Thromboxane A2; Thromboxane B2

The authors investigated the pathological mechanism of thromboxane A2 in alkaline burn of the eye. Thromboxane B2 (metabolic product of thromboxane A2) in aqueous humor of the burned eye significantly increased in 30 minutes after the burn. The pathological change was the formation of thrombosis 2 hours after the alkaline burn, especially in the anterior segment. The role of thromboxane A2 in alkaline burn of the eye was ascertained.

Topics: Alkalies; Animals; Anterior Eye Segment; Aqueous Humor; Burns, Chemical; Eye Burns; Male; Rabbits; Thrombosis; Thromboxane A2; Thromboxane B2

This study was performed to determine the relationship between plasma concentration of thromboxane B2 (TXB2), 6-keto-prostaglandin F1a and atrial thrombosis in patients with mitral stenosis (MS). By radioimmunoassay and pathological examination, peripheral plasma TXB2 level was remarkably higher in patients with MS and persistent atrial fibrillation (AF) than in patients with MS but without AF (P less than 0.01). Plasma TXB2 level was significantly higher in patients with than in those without atrial thrombosis (P less than 0.05). There was no significant difference in plasma 6-keto-PGF1 alpha, plasma prostanoids level in peripheral venous blood correlated closely with that in left atrial blood. Patients with high plasma TXB2 level had a greater incidence of microthrombosis.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Atrial Fibrillation; Female; Heart Diseases; Humans; Male; Middle Aged; Mitral Valve Stenosis; Rheumatic Heart Disease; Thrombosis; Thromboxane B2

To investigate if low-dose acetylsalicylic acid (ASA), 4 mg/kg b.w., infused peroperatively or 10 hours preoperatively has antithrombotic effects, the central arteries of rabbit ears were prepared and 32P-labeled platelets injected. Arteriotomy and intimectomy were performed and blood flow was restored. Bleeding times at the sites of arteriotomy/intimectomy, in vivo accumulations of isotope-labeled platelets, amounts of red thrombotic material, and patency were recorded. Bleeding times following arterial puncture and the effect of ASA on thromboxane production were studied separately. Ten hours after ASA administration, bleeding times were shortened at the sites of arteriotomy/intimectomy but were prolonged following arterial puncture. Platelet accumulations were lower in patent vessels in this group than in an untreated control group. Peroperative ASA treatment increased but treatment 10 hours prior to blood flow restoration did not significantly affect the number of occlusions. Thromboxane production in ASA-treated rabbits is largely inhibited even 14 hours after administration.

Topics: Animals; Arteries; Aspirin; Blood Coagulation; Blood Platelets; Ear, External; Female; Male; Microscopy, Electron, Scanning; Platelet Adhesiveness; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Thrombosis; Thromboxane B2; Time Factors; Vascular Patency

The aim of this work was to monitor concentrations of prostanoids affecting platelet aggregation, namely prostacyclin and thromboxane A2, in the plasma and prostacyclin in the endothelium of vessel wall after whole-body irradiation of rats by the doses 5, 10, 50, 100 and 250 Gy (source 60Co) in the early stage of irradiation up to 24 hours. Stable metabolites of the prostanoids - 6-keto PGF1 alpha and TxB2 were determined by a RIA technique. The 6-keto PGF1 alpha plasma concentration increased after irradiation by the 50 Gy dose between 3rd and 24th hours and at all sampling times after the 100 and 250 Gy doses. A rise in prostanoid concentrations was noted after low doses of irradiation in the first sampling intervals only. The TxB2 level increased after the same doses (5 and 10 Gy) up to the 6th hour and then decreased. The thromboxane concentration increased after 50 Gy at the 90th minute, 12th and 24th hours, after 100 Gy at the 24th hour and after 250 Gy at the 90th minute, 3rd and 24th hours.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Endothelium, Vascular; Male; Rats; Rats, Inbred Strains; Thrombosis; Thromboxane B2; Whole-Body Irradiation

Topics: Angina Pectoris; Arachidonic Acids; Chromatography, High Pressure Liquid; Humans; Myocardial Infarction; Radioimmunoassay; Reference Values; Thrombosis; Thromboxane B2

Using the standard turbidimetric method of platelet aggregation and quantitation of platelet secretion with 14C-Serotonin, we have examined the responsiveness of the platelets of mongrel dogs to arachidonic acid (AA), and the thromboxane agonist U46619 in the presence and absence of a subthreshold concentration of epinephrine. In response to stimulation with 750 microM AA, the platelets of 18 dogs produced irreversible aggregation (Group I), the platelets of 22 dogs showed, at most, reversible aggregation (Group II), while the platelets of 8 dogs demonstrated no aggregatory response (Group III). In the presence of AA and a subthreshold concentration of epinephrine (0.5 microM), the platelets of all three groups demonstrated enhanced aggregatory and secretory responses although the extent of 14C-Serotonin secretion differed significantly between all three groups. These in vitro differences in platelet aggregation correlate with the in vivo deposition of platelets onto synthetic vascular grafts and the maintenance of graft patency. When stimulated with 0.5 microM U46619 and a subthreshold concentration of epinephrine, the platelets of 97% Group I dogs and 75% of Group II dogs exhibited irreversible aggregation, while the platelets of all Group III dogs showed only reversible aggregation. In addition, significant differences in the extent of 14C-Serotonin secretion to this combination of agonists were observed between groups. Further examination of the specific effects of U46619 on canine platelets revealed that although the aggregatory and secretory responses to U46619 vary between the different canine platelet populations, the threshold concentration of U46619 required to produce platelet shape change is identical among all groups. Quantitation of the stable metabolite of AA produced via the cyclooxygenase pathway, thromboxane B2 (TxB2), revealed no significant differences in the production of TxB2 by the platelets of these different populations upon stimulation with AA. Our results suggest that the mechanisms underlying the differences in responsiveness of canine platelets to AA, are likely due to differences in sensitivity of canine platelets to TxA2, and may be localized to the mechanism responsible for mediating platelet aggregation and secretion in response to TxA2.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Dogs; Female; Graft Occlusion, Vascular; In Vitro Techniques; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Prostaglandin Endoperoxides, Synthetic; Serotonin; Thrombosis; Thromboxane B2

In vitro tests were carried out on Dacron samples differently knitted and on Dacron vascular prostheses coated with various urethanes. All the materials were put in contact with human platelet-rich plasma; the subsequent assay of three platelet released substances, i.e. beta-thromboglobulin, platelet factor 4 and thromboxane B2, as well as the quantification of platelet retention, were used to establish the degree of thrombogenicity of the material itself. In some cases Dacron-urethanes composites showed better thromboresistance than any other materials conventionally used in vascular surgery.

Topics: beta-Thromboglobulin; Biocompatible Materials; Blood Platelets; Blood Vessel Prosthesis; Materials Testing; Platelet Adhesiveness; Platelet Count; Platelet Factor 4; Polyethylene Terephthalates; Polyurethanes; Thrombosis; Thromboxane B2

An in vitro model of platelet adhesion, the annular perfusion chamber, was utilized to test the effects of Interleukin 1 on vascular thrombogenicity for platelets. De-endothelialized, everted human umbilical arteries were placed in cell culture media with or without Interleukin 1. The arteries were later perfused with citrated human blood and then fixed. Platelet adhesion and aggregate formation on artery segments was quantified by blinded morphometric analysis. A monolayer of contact platelets was seen on control artery segments, but arteries exposed to 100 Units/ml Interleukin 1 for 2-20 hours had increased numbers and size of platelet aggregates. Ultrastructurally, intact endothelial cells were not present on any segment. Both prostacyclin and thromboxane were released by vascular cells in the artery segments, but the quantity and ratio of these eicosanoids was not altered by artery exposure to Interleukin 1. Arterial thrombogenicity is modulated by non-endothelial vascular cells in response to Interleukin 1, and this does not appear to be mediated by changes in vascular production of thromboxane or prostacyclin.

Topics: 6-Ketoprostaglandin F1 alpha; Arterial Occlusive Diseases; Humans; In Vitro Techniques; Interleukin-1; Perfusion; Platelet Aggregation; Thrombosis; Thromboxane B2; Umbilical Arteries

Topics: Arrhythmias, Cardiac; Blood Viscosity; Coronary Disease; Dinoprost; Heart Conduction System; Humans; Nucleotides, Cyclic; Platelet Aggregation; Prognosis; Thrombosis; Thromboxane B2

Studies were performed to determine the cross-reaction rate of the heparin-dependent antibody with Org 10172, a new low molecular weight heparinoid, and to investigate the effect of Org 10172 on platelet activation induced by the antibody. The plasmas of 17 patients with thrombocytopenia induced by standard heparin were shown, by platelet aggregation studies, to contain the heparin-dependent antibody. Of these 17 patient plasmas, only three cross-reacted with the heparinoid, producing a cross-reaction rate of 18%. When Org 10172 was added to a reaction mixture containing normal platelet-rich plasma, patient plasma, and standard heparin with non-cross-reacting plasmas, it inhibited platelet aggregation and thromboxane B2 production induced by the antibody, provided that the ratio of Org 10172 concentration (anti-Xa U/mL) to standard heparin concentration (IU/mL) exceeded 2.5 to 5.0. This inhibitory effect was observed only with platelet activation mediated by the antibody, but not by collagen (2 micrograms/mL) or ADP (5.0 mumol/L). Additionally, three of 17 patients with serious thrombosis, whose plasma showed no cross-reaction with the heparinoid, received Org 10172 treatment with a good response in each case. These findings suggest that Org 10172 may be a useful drug for the treatment of heparin-induced thrombocytopenia.

Topics: Antigen-Antibody Reactions; Blood Platelets; Chondroitin Sulfates; Cross Reactions; Dermatan Sulfate; Glycosaminoglycans; Heparin; Heparitin Sulfate; Humans; In Vitro Techniques; Molecular Weight; Platelet Aggregation Inhibitors; Thrombocytopenia; Thrombosis; Thromboxane B2

The arachidonic acid metabolites produced by human peripheral blood monocytes were studied to determine which metabolites could have a role in thrombogenesis. Monocytes were found to be free of platelets by scanning electron microscopy and by measurement of 12-HETE. Human peripheral blood monocytes produce thromboxane as their major metabolite. Thromboxane levels reached a plateau at 12-16 hours of culture. Monocytes produced relatively little prostaglandin E2 or F2. In contrast to our control platelet preparation, neither A23187 (1-10 microM) nor exogenous arachidonic acid (0-40 microM) caused an increase in monocyte thromboxane B2. On the other hand, lipopolysaccharide (20 micrograms per ml), collagen (2.5 mg per 10(7) cells), and thrombin (5-10 units per ml) caused a two- to fivefold increase in monocyte thromboxane B2 in most donors but had no effect on prostaglandin F1 alpha levels. Blockage of thromboxane synthase by 1-benzylimidazole abolished thromboxane B2 production but did not increase prostaglandin F1 alpha. Finally, aspirin-treated platelets from a volunteer donor, which were refractory to 30 microM arachidonate, could be aggregated by isolated blood monocytes. Our data indicate that monocytes are capable of producing thromboxane in large amounts. The regulation of this increase, however, appears to be quite different from platelets. We postulate that monocytes may have a role in hemostasis by virtue of their ability to adhere at sites of vascular injury and release thromboxane, which may enhance platelet aggregation and thrombus formation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 6-Ketoprostaglandin F1 alpha; Arachidonic Acids; Blood Physiological Phenomena; Blood Platelets; Cell Separation; Cells, Cultured; Humans; Hydroxyeicosatetraenoic Acids; Imidazoles; Monocytes; Platelet Aggregation; Stimulation, Chemical; Thrombosis; Thromboxane B2; Time Factors

New-Breviscapine is an anti-platelet compound with some kinds of salts extracted from a Chinese herb Erigeron breviscapus. In aortic thrombus formation in rabbits, the platelet 5-HT release reaction and platelet destruction could be reduced by the compound, meanwhile aortic thrombosis was inhibited with a clear correlation between drug dosage and its efficacy. It was shown that new-breviscapine could inhibit the production of TXB2 and 6-keto-PGF1 alpha by platelets and endothelial cells respectively. The data suggest that new-breviscapine has a significant inhibitory effect on thrombus formation in vivo through suppression of platelet functions.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anticoagulants; Blood Platelets; Drugs, Chinese Herbal; Flavonoids; Male; Rabbits; Thrombosis; Thromboxane B2

RS-5186, sodium 6-[2-[1-(1H)-imidazolyl]methyl-4,5-dihydrobenzo[b]thiophene]- carboxylate, inhibited platelet thromboxane A2 (TXA2) synthetase with IC50 values of 6 nM and 13 nM for human and rabbit microsomes, respectively. It had a selectivity for TXA2 synthetase 10(5)-fold greater than that for cyclooxygenase, PGI2 synthetase, 5-lipoxygenase and phospholipase A2. When administered orally or intravenously to dogs at 1 mg/kg, RS-5186 suppressed serum TXB2 levels almost completely with sustained duration of action: the suppression during 0.5 hr to 8 hr after dosing was more than 90%, and was 70-80% at 24 hr. Similar suppression of serum TXB2 levels was observed in rats and rabbits. Such suppression by RS-5186 was more potent than that by OKY-046 and CV-4151. Serial administration of RS-5186 (0.1 mg/kg/day p.o.) to dogs for 7 days decreased the serum TXB2 levels constantly during the medication, and no rebound phenomenon was observed after the medication was stopped. In a thrombotic model induced by sodium arachidonate injection in rabbits, RS-5186 at 1 mg/kg p.o. completely protected against sudden death (ED50 = 0.12 mg/kg, 1 hr after dosing) and this protective effect extended over 8 hr. All these results show that RS-5186 is a potent and highly selective TXA2 synthetase inhibitor with a long duration of action, and suggest that the compound could be useful in diseases where TXA2 is involved.

Topics: Animals; Arachidonic Acids; Blood Platelets; Dogs; Female; Humans; In Vitro Techniques; Male; Microsomes; Platelet Count; Prostaglandins; Rabbits; Rats; Rats, Inbred Strains; Thiophenes; Thrombosis; Thromboxane B2; Thromboxane-A Synthase

We describe here an experimental model of peripheral arterial thrombosis and the effect of several drugs which are known to affect vessel and platelet biological functions. A similar method has been previously applied by us and others on dog coronary arteries. Male Beagle dogs, under pentobarbital anesthesia, were instrumented to measure arterial pressure, heart rate, ECG, femoral blood flow and expired CO2. A segment of the femoral artery was squeezed with forceps to damage the endothelium, and a plastic cylinder was placed around the vessel in the area of the damage. The cylinders had a length of 2 mm and an internal diameter of 1.6-1.8 mm. Under these circumstances blood flow in the stenosed artery was reduced by about 60-70% from control value and showed cyclic blood flow variations (CBFV). CBFV eventually led either to a total occlusion of the vessel (documented by blood flow measurement and by angiographic analysis), or to a spontaneous partial restoration of flow, followed by another decrease, in a repetitive fashion. Drug effect was monitored by observing the changes in frequency and amplitude of CBFV. Ketanserin (0.25 mg/kg), dazmegrel (0.5 mg/kg), and chlorpromazine (0.5 mg/kg), abolished or greatly reduced CBFV in all the experiments, while acetylsalycilic acid (ASA, 10 mg/kg) reduced or abolished CBFV in 60% of the treated dogs. Heparin (50 I.U./kg), dipyridamole (1.0 mg/kg) and prazosin (0.1 mg/kg) did not change CBFV. These results emphasize the importance of serotonin and thromboxane as mediators of vascular occlusion in this particular experimental model. This approach provides a reproducible in vivo preparation to study the pharmacological control of peripheral arterial thrombosis.

Topics: Angiography; Animals; Blood Pressure; Blood Vessels; Dogs; Femoral Artery; Heart Rate; Imidazoles; In Vitro Techniques; Ketanserin; Male; Regional Blood Flow; Thrombosis; Thromboxane B2; Thromboxane-A Synthase

The in vivo production of thromboxane and prostacyclin was studied by measurements of their major urinary metabolites in eight patients undergoing total hip arthroplasty. Specific methods based on gas chromatography-mass spectrometry were used to measure the urinary excretion of 2,3-dinor-TxB2 and 2,3-dinor-6-keto-PGF1 alpha. The excretion of these metabolites increased about 10-fold during the intra and immediate postoperative period and 4 days after surgery was still higher than during the preoperative period. The increased thromboxane formation reflects probable activation of platelets whereas the increased prostacyclin could be part of a vascular defense against induced thrombotic activity. These findings may have pathophysiological implications.

Topics: 6-Ketoprostaglandin F1 alpha; Aged; Female; Gas Chromatography-Mass Spectrometry; Hip Prosthesis; Humans; Male; Thrombosis; Thromboxane B2

Urinary thromboxane B2 levels increased threefold to 20-fold in infants with neonatal necrotizing enterocolitis compared with healthy infants and infants with benign causes of heme-positive stools. Increased urinary thromboxane B2 levels were detected coincidently with the initial signs of necrotizing enterocolitis, and values paralleled the course of the illness. Infants with serious illnesses other than necrotizing enterocolitis had increased urinary thromboxane B2 levels but with lower values than those of infants with necrotizing enterocolitis. Indomethacin therapy appeared to reduce urinary thromboxane B2 levels and reduce their usefulness as a marker of illness. Another product of platelet activation, beta-thromboglobulin, was increased in the urine of infants with necrotizing enterocolitis. Decreased platelet counts in infants with necrotizing enterocolitis correlated inversely with urinary thromboxane. Results of beta-thromboglobulin and platelet studies are consistent with the concept that platelet consumption due to ischemic thrombosis was the source of enhanced thromboxane excretion.

Topics: beta-Thromboglobulin; Enterocolitis, Pseudomembranous; Humans; Indomethacin; Infant, Newborn; Infant, Premature; Occult Blood; Platelet Count; Prospective Studies; Risk; Thrombosis; Thromboxane B2

We have evaluated the possible role of platelet functional abnormalities as a contributory cause of thrombosis during pregnancy and to the increased fetal mortality and morbidity among women who smoke. Fifty-three pregnant women were enrolled and evaluated on two separate prenatal visits held between the 20th and 36th week of pregnancy and, when possible, post partum. Smoking status was evaluated by personal statement and alveolar carbon monoxide levels. Women in the smoking group deliberately avoided cigarettes for at least 20 minutes before sampling. Plasma levels of beta-thromboglobulin, thromboxane B2, and 6-Keto PGF1 alpha were evaluated. A significant increase in 6-Keto PGF1 alpha was noted among smoking women as pregnancy advanced. 6-Keto PGF1 alpha levels decreased among non-smoking women while beta-thromboglobulin increased significantly between the 20th and 33rd week of pregnancy in non-smokers. Platelet aggregation, both in platelet rich plasma and in whole blood (by impedance aggregometry), was evaluated by five different parameters and four different aggregating agents. Significant differences between the non-smoking and smoking pregnant women were noted for selected age cohorts and aggregating agents. An increase in platelet reactivity among smokers was observed in whole blood by impedance aggregometry with adenosine diphosphate and in two age cohorts using platelet rich plasma. In two groups in which aggregation was significantly accelerated among non-smokers, epinephrine was used as the aggregating agent.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; beta-Thromboglobulin; Blood Platelets; Female; Humans; Infant, Newborn; Platelet Aggregation; Pregnancy; Pregnancy Complications, Cardiovascular; Smoking; Thrombosis; Thromboxane B2

We have previously demonstrated an in vivo model of deep vein thrombosis which suggests that the neutrophil promotes vascular injury and thrombosis following blood flow stasis. Since leukotrienes are potent mediators of vascular injury and neutrophil (PMN) chemotaxis, we wished to determine if in vivo inhibition of 5-lipoxygenase would reduce neutrophil mediated events in our model. Lipoxygenase was inhibited in vivo with 2,3-diethyl-4-methoxy,1-naphthalenol acetate (U-66,855). The in vivo activity of U-66,855 was demonstrated in 4 cats. Each animal was treated with 5 mg/kg of U-66,855 intravenously. Blood cell leukotriene B4 (LTB4) and thromboxane A2, via its metabolite thromboxane B2 (TBX2) was assessed before and 30, 60, and 120 min after dosing. Blood cell LTB4 and TBX2 production was stimulated by A23187 (24 microM) and assayed by radioimmunoassay. We exposed and isolated a 3-cm segment of the jugular veins from 10 additional cats 5 of which were treated with U-66,855 (5 mg/kg, iv). In order to assess the effect of stasis, the jugular veins were ligated at the thoracic inlet for 2 hr after which the veins were perfused, fixed in 2.5% glutaraldehyde, and prepared for electron microscopy. U-66,855 reduced LTB4 production significantly (P less than 0.01), but not TBX2. In untreated cats, PMNs adhered to and migrated underneath the venous endothelium. Additionally, platelets, fibrin and formed thrombi were found on the basement membrane exposed by the migrating neutrophils. In contrast, we observed significantly reduced PMN adhesion as well as no fibrin deposition in veins obtained from cats treated with U-66,855. The results suggest that 5-lipoxygenase inhibition can significantly reduce undesirable neutrophil/vessel wall interactions.

Topics: Animals; Arachidonate Lipoxygenases; Cats; Cell Adhesion; Cell Movement; Endothelium; Jugular Veins; Leukocytes; Leukotriene B4; Lipoxygenase Inhibitors; Microscopy, Electron; Microscopy, Electron, Scanning; Naphthols; Neutrophils; Thrombosis; Thromboxane A2; Thromboxane B2

1-(3-Benzyloxy-1[E]octenyl)imidazole (CBS-645) is a specific inhibitor of thromboxane synthetase. It inhibits the platelet enzyme in human and rabbit at micromolar concentrations. At a dose of 12.5 mg kg-1 in rabbits, CBS-645 displays a prolonged inhibitory effect on the formation of thromboxane (Tx) B2 induced by blood coagulation in vitro. In human volunteers, an oral dose of 50 mg leads to an average 70% inhibition of TxB2 formation. CBS-645 administered at a dose of 25 mg kg-1 p.o. in the rat, significantly increases bleeding time. In another test in which platelet interaction with the vessel wall is involved, i.e. in vivo platelet deposition onto desendothelialized aorta in the rabbit, the drug shows antithrombotic activity after a single oral administration of 5 mg kg-1. CBS-645 could be of interest in the treatment of the various diseases in which the pathological role of thromboxane A2 is suspected.

Topics: Adult; Animals; Arachidonic Acid; Arachidonic Acids; Bleeding Time; Blood Platelets; Dinoprostone; Humans; Imidazoles; In Vitro Techniques; Male; Middle Aged; Prostaglandins E; Rabbits; Rats; Rats, Inbred Strains; Thrombosis; Thromboxane B2; Thromboxane-A Synthase

The purpose of this study was to compare the effects of dazoxiben (DAZ), UK 38,485 (UK) and aspirin (ASA) in the prevention of thrombotic sudden death in rabbits. In anesthetized male rabbits, sudden death was produced by intravenous administration of 0.75 mg/kg arachidonic acid (AA). AA increased plasma TxB2 levels from 0.20 +/- 0.10 ng/ml to 8.75 +/- 1.79 ng/ml and produced a 42% reduction in the number of circulating platelets. Death occurred in all animals within 5 minutes. Administration of DAZ (8.6 mumole/kg) 15 min before AA prevented the increase in plasma TxB2, the thrombocytopenia and sudden death while pretreatment with DAZ 2 hr before AA did not. The administration of UK (8.6 mumole/kg) 15 min. 4 hrs or 8 hrs before AA resulted in 100%, 67% and 33% survival, respectively. ASA (110 mumole/kg) administered 2 or 24 hrs before AA inhibited the increase in plasma TxB2 and prevented the fall in platelet counts. All animals pretreated with ASA survived. These data demonstrate that DAZ and UK have only a short to moderate duration of action in preventing AA-induced increases in plasma Tx levels and thrombocytopenia.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Arachidonic Acids; Aspirin; Imidazoles; Male; Rabbits; Thrombocytopenia; Thrombosis; Thromboxane B2; Time Factors

Despite successful thrombolysis of occluded prosthetic grafts, rethrombosis remains a problem. We investigated the efficacy of aspirin in maintaining patency of polytetrafluoroethylene grafts (3 mm X 3.5 cm) in canine femoral arteries after thrombolytic therapy. After induction of thrombosis, either tissue-type plasminogen activator (t-PA) or urokinase (UK) was infused just proximal to the thrombus (4000 U/min) until complete thrombolysis was achieved. Five of the 10 UK-treated dogs and five of the 10 t-PA-treated dogs received aspirin immediately after recanalization, and aspirin was continued (325 mg/day) for 4 weeks or until occlusion occurred. A systemic aspirin effect was confirmed by marked depression of serum thromboxane B2 and absent platelet aggregation. Only two of the 10 grafts in the aspirin-free group remained patent for 4 weeks. The remaining eight grafts had all reoccluded by 2 weeks. None of the 10 grafts in the aspirin-treated group reoccluded during the 4 weeks. This significantly improved patency (p less than .001) in the aspirin-treated group was observed equally in grafts treated with t-PA or UK. Thus aspirin is a potent agent in preventing rethrombosis after thrombolytic recanalization of prosthetic grafts.

Topics: Animals; Aspirin; Blood Vessel Prosthesis; Dogs; Graft Occlusion, Vascular; Platelet Aggregation; Polytetrafluoroethylene; Thrombosis; Thromboxane B2; Time Factors; Tissue Plasminogen Activator; Urokinase-Type Plasminogen Activator

Interest in the antithrombotic potential of low-dose aspirin is based on its ability to inhibit thromboxane (Tx)A2-related platelet function with concomitant sparing of vascular prostacyclin (PGI2) production. The aim of this study was to investigate the effect of low-dose aspirin (20 mg daily for 7 days) on the increase in fibrinolytic activity in healthy volunteers after venous occlusion. We also tested the effect of high-dose aspirin (650 mg X 2), of salicylate (569 mg X 2) and of indobufen (200 mg X 2), a new cyclo-oxygenase inhibitor unrelated to salicylates. Low-dose aspirin reduced serum TxB2 generation by about 90% and suppressed arachidonate-induced platelet aggregation. In contrast, fibrinolytic activity, measured by the euglobulin lysis area and the euglobulin lysis time, was not significantly affected. Both high-dose aspirin and indobufen significantly inhibited TxB2 generation and the rise in fibrinolytic activity induced by venous occlusion, without affecting the pre-occlusion values. Salicylate did not significantly affect any parameter studied. Besides offering a favorable solution to the "aspirin dilemma" related to the TxA2/PGI2 balance, low-dose aspirin might leave intact the fibrinolytic capacity of the vessel wall.

Topics: 6-Ketoprostaglandin F1 alpha; Analysis of Variance; Aspirin; Fibrinolysis; Hematocrit; Humans; Isoindoles; Phenylbutyrates; Thrombosis; Thromboxane B2

Visualization and analysis of mural thrombogenesis on collagen-coated glass, polyurethane and nylon was discussed. Epi-fluorescent video microscopy was used to visualize thrombotic events at a protein or polymer surface in contact with flowing whole blood. Digital image processing was used to analyse the real-time microscopic images obtained, resulting in measurements of morphological features and the number of platelets that compose each thrombus. The three-dimensional structures of the thrombi were also estimated. A photodiode was used to measure integrated end-point platelet accumulation at different axial positions along the surface. Additionally, the convection-diffusion equations were solved to estimate the concentrations of adenosine diphosphate, thromboxane A2, and thrombin generated by activated platelets at the blood-contacting surface.

Topics: Adenosine Diphosphate; Biocompatible Materials; Blood Platelets; Collagen; Humans; In Vitro Techniques; Microscopy, Fluorescence; Nylons; Polyurethanes; Signal Processing, Computer-Assisted; Thrombin; Thrombosis; Thromboxane B2

Topics: Animals; Aspirin; Blood Platelets; Femoral Artery; Platelet Aggregation; Prostaglandins; Rabbits; Thrombosis; Thromboxane B2

Topics: Animals; Coronary Disease; Dogs; Epoprostenol; Fatty Acids, Monounsaturated; Fatty Acids, Unsaturated; Pyridines; Rats; Thrombosis; Thromboxane B2; Thromboxane-A Synthase

To study interactions between platelets and the fibrinolytic system, we examined the effects of human plasmin on human platelets washed by gel filtration. Plasmin concentrations that did not affect platelet shape change, release, or aggregation (less than 1.0 caseinolytic units [CU]/ml) caused a dose- and time-dependent inhibition of platelet aggregation in response to thrombin, ionophore A23187, and collagen. Complete loss of aggregation occurred at 0.1-0.5 CU/ml of plasmin. In a parallel dose-dependent manner, plasmin likewise inhibited thrombin, ionophore, and collagen-stimulated thromboxane B2 production. In contrast, neither aggregation nor thromboxane B2 formation induced by arachidonate was inhibited by plasmin pretreatment of the platelets. Plasmin blocked the thrombin-induced release of [3H]arachidonic acid from platelet membrane phospholipids and the thrombin-induced platelet oxygen burst. However, plasmin did not inhibit the arachidonate-induced oxygen burst. Inhibition of arachidonic acid release by plasmin was not mediated by increase in platelet cyclic AMP. These results suggest that plasmin inhibits platelet function, at least in part, by blocking the mobilization of arachidonic acid from membrane phospholipid pools. The effects of plasmin on platelets may contribute to the hemostatic abnormalities seen in pathologic and pharmacologic fibrinolysis.

Topics: Arachidonic Acid; Arachidonic Acids; Blood Platelets; Calcimycin; Collagen; Fibrinolysin; Fibrinolysis; Humans; In Vitro Techniques; Platelet Aggregation; Thrombin; Thrombosis; Thromboxane B2

The effect of a selective inhibitor of thromboxane synthesis (dazoxiben) was evaluated in different acute models for thrombosis and hemostasis. Dazoxiben significantly reduced the thrombogenicity of the modified human umbilical vein (Dardik Biograft) inserted in the carotid artery position in sheep. The effect was evident concerning patency, thrombus weight and platelet accumulation at the distal anastomosis. This paralleled a decreased production of thromboxane in both anastomoses and the midgraft region. Dazoxiben did not reduce either the frequency of jugular vein thrombosis (induced by a combination of endothelial damage and flow restriction) or arteriolar microembolism after laser injury in rabbits. Neither did it influence initial hemostasis as evaluated by measuring the hemostatic plug formation in the rabbit mesenteric microcirculation. It is concluded that thromboxane synthesis inhibition may be of value when attempting to improve the performance of small diameter vascular prostheses, the data obtained indicating a low risk for hemorrhagic complications.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Platelets; Carotid Arteries; Female; Hemostasis; Humans; Imidazoles; Jugular Veins; Male; Oxidoreductases; Rabbits; Sheep; Thrombosis; Thromboxane B2; Thromboxane-A Synthase; Umbilical Veins

We have investigated the relevance of some laboratory tests of platelet function in predicting conditions of thrombotic tendency. For this purpose, we studied platelet survival, platelet aggregation in response to different stimuli, TxB2 and 6-keto-PGF1 alpha production in serum of rats bearing a nephrotic syndrome induced by adriamycin. These animals show a heavy predisposition to the development of both arterial and venous thrombosis. The mean survival time was normal in nephrotic rats in comparison to controls. As to aggregation tests, a lower aggregating response was found in ADR-treated rats using ADP or collagen as stimulating agents. With arachidonic acid (AA) we observed similar aggregating responses at lower AA concentrations, whereas at higher AA concentrations a significantly lower response was found in nephrotic rats, despite their higher TxB2 production. Also TxB2 and 6-keto-PGF1 alpha levels in serum of nephrotic rats were significantly higher than in controls. No consistent differences were found in PGI2-activity generated by vessels of control or nephrotic rats. These data show that platelet function may appear normal or even impaired in rats with a markedly increased thrombotic tendency. On the other hand, the significance of high TxB2 levels in connection with mechanisms leading to thrombus formation remains a controversial issue.

Topics: 6-Ketoprostaglandin F1 alpha; Adenosine Diphosphate; Animals; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Cell Survival; Collagen; Doxorubicin; Epoprostenol; In Vitro Techniques; Male; Platelet Aggregation; Rats; Thrombosis; Thromboxane B2

Bleeding time, thromboxane production and inhibition of platelet aggregation were studied before and during administration of acetylsalicylic acid in doses of 50, 100, 325 an 1000 mg daily in eighteen patients with cerebrovascular disease. Inhibition of thromboxane production and platelet aggregation was almost complete at 50 mg acetylsalicylic acid daily, and median bleeding time had increased significantly from 5.5 to 6.5 min at this dose and reached a maximum of 7.5 min at 100 mg daily. Further increase of the dose resulted in a slight decrease in bleeding time. It appears that a strong effect on platelet function can be achieved by small doses of acetylsalicylic acid, and that higher doses might be less effective.

Topics: Adult; Aged; Aspirin; Bleeding Time; Brain Ischemia; Cerebrovascular Disorders; Dose-Response Relationship, Drug; Female; Humans; In Vitro Techniques; Male; Middle Aged; Platelet Aggregation; Thrombosis; Thromboxane B2

This article examines the relationship of platelet deposition to thromboxane and prostacyclin (PGI2) production in arterial autografts (n = 8), para-anastomotic native artery (n = 40), nonseeded control (n = 6), and endothelial cell-seeded (n = 17) small-diameter Dacron grafts implanted in the carotid and femoral arteries of dogs. Platelet deposition was measured by a dual-isotope subtraction platelet-imaging technique that expresses platelet deposition as percent indium excess (%IE). PGI2 and thromboxane assays were performed with the use of an immunoreactive assay. The %IE in the nonseeded grafts was significantly higher than in the seeded prostheses (p less than 0.001). Arterial autografts accumulated significantly less platelets than did seeded grafts (p less than 0.05) or nonseeded grafts (p less than 0.001). The thromboxane A2 (TXA2) production in nonseeded grafts was significantly higher than in seeded grafts (p less than 0.001), arterial autografts (p less than 0.001), or in para-anastomotic native artery (p less than 0.001). The PGI2 production by the arterial autografts was significantly higher than by the nonseeded grafts (p less than 0.005), seeded grafts (p less than 0.001), or para-anastomotic native artery (p less than 0.025). The PGF1 alpha/TXB2 ratio was significantly higher in the arterial autografts when compared with the nonseeded grafts (p less than 0.001), endothelial cell-seeded grafts (p less than 0.001), or para-anastomotic native artery (p less than 0.025). We conclude that platelet deposition can be significantly decreased by endothelial cell seeding of small-diameter grafts. The transmural production of TXA2 by native arteries and prosthetic grafts may have an important influence on platelet deposition and patency.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Arteries; Blood Platelets; Blood Vessel Prosthesis; Cells, Cultured; Dogs; Endothelium; Epoprostenol; Indium; Polyethylene Terephthalates; Prostaglandins; Radioisotopes; Thrombosis; Thromboxane A2; Thromboxane B2

BM 13.177 (4-[2-(benzenesulfonamido)-ethyl]-phenoxyacetic acid) is a representative of a new class of sulfonamidophenylcarboxylic acids which possess platelet-inhibitory and anti-thrombotic activity and inhibits the contraction of rabbit aorta stimulated by PG endoperoxides and TXA2. BM 13.177 5 mg/kg body weight p.o. protected rabbits from arachidonate-induced sudden death and greater than or equal to 10 mg/kg dose-dependently reduced the experimental thrombus formation induced in the rabbit aorta by perivascular administration of silver nitrate. In guinea-pigs, the collagen-induced bronchoconstriction was inhibited in a dose- and time-dependent fashion. The formation of TXA2 and the TXA2-induced platelet aggregation and smooth muscle contraction are probably crucial events in these experimental models. The protective effect of BM 13.177 may, therefore, be due to the TXA2-antagonizing effect of BM 13.177, which has been conclusively demonstrated in human platelets (PATSCHEKE and STEGMEIER, Thrombosis Res., 33, 277-288 (1984). The antagonism of TXA2 is supported by the observation that BM 13.177 also specifically inhibits the contraction of isolated arterial strips from rabbits which were stimulated with the thromboxane A2 mimetic U 46619. Schild-plot with a slope close to unity suggests a competitive type of antagonism. BM 13.177 exhibited neither anti-inflammatory nor ulcer-inducing activity of cyclooxygenase inhibitors. Furthermore it did not block the TXB2 formation in spontaneously clotting blood from rabbits and did not inhibit the release of prostacyclin-like activity from rabbit aortas. The lack of toxicological effects in long-term toxicity studies in rat and dog, together with the absence of objective and subjective side effects in the first human studies have encouraged us to initiate clinical trials in order to evaluate the therapeutic benefit of this new approach in humans.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Epoprostenol; Female; Fibrinolytic Agents; Guinea Pigs; Male; Muscle Contraction; Muscle, Smooth, Vascular; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Rabbits; Sulfonamides; Thrombosis; Thromboxane A2; Thromboxane B2; Thromboxanes

Platelet aggregation was studied in vitro with human platelets and in vivo in guinea pigs and rabbits. L-640,035 and its acetic acid metabolite, L-636,499, significantly inhibited human platelet aggregation induced by arachidonic acid, collagen and a prostaglandin endoperoxide analog (U44069) but not ADP. In guinea pigs, circulating platelets labeled with 111indium were monitored with probes in the lung and abdominal regions. Platelet aggregation was indicated by an increase in the ratio of gamma-radiation of the lung vs. the abdominal region, as aggregates of platelets accumulate in the microvascular network in the lung. L-640,035 (1 and 3 mg/kg i.v.) inhibited platelet aggregation induced in this model by U-44069 but not by ADP. In rabbits acute thrombosis was induced in the carotid artery by local electrical stimulation and platelet accumulation at the stimulus site was quantitated using 111indium-labeled autologous platelets. L-640,035 (1 and 3 mg/kg i.v.) significantly reduced electrically evoked platelet accumulation. It is concluded that L-640,035 is a novel and selective antagonist of platelet aggregation induced by thromboxane A2 or prostaglandin endoperoxides and that it may have utility as an antiplatelet drug.

Topics: Adenosine Diphosphate; Animals; Arachidonic Acid; Arachidonic Acids; Collagen; Dibenzothiepins; Electric Stimulation; Female; Guinea Pigs; Humans; Male; Platelet Aggregation; Prostaglandin Endoperoxides, Synthetic; Rabbits; Thrombosis; Thromboxane A2; Thromboxane B2; Thromboxanes

Electrical stimulation in the presence of ADP of arterioles of the hamster cheek pouch caused endothelial damage and white thrombus formation. The thrombus formation was inhibited by cyclo-oxygenase inhibitors aspirin and sulphinpyrazone and its thioether derivative G 25671. Thromboxane synthetase inhibitors N-(7-carboxyheptyl) imidazole and butylimidazole failed to inhibit thrombus formation, although in the same doses both compounds inhibited serum levels of thromboxane. These results indicate that thromboxane is not important in thrombus formation in the hamster, but that prostaglandin endoperoxides are more significant. However, it is possible that the inhibition of white thrombus formation by aspirin, sulphinpyrazone and G 25671 may be mediated by a different mechanism altogether.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Aspirin; Cheek; Cricetinae; Cyclooxygenase Inhibitors; Dipyridamole; Epoprostenol; Male; Mesocricetus; Microscopy, Electron; Platelet Aggregation; Sulfinpyrazone; Thrombosis; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Thromboxanes

Umbilical vein grafts were placed in the carotid arteries of sheep and removed after 10 or 90 days for determination of in vitro production of 6-keto-PGF1 alpha and thromboxane B2 (TxB2) in the anastomoses and in the middle of the grafts. At both intervals the grafts produced much more TxB2 than carotid arteries, but no significant difference in production of 6-keto-PGF1 alpha was found between grafts and carotid arteries. The strongly decreased 6-keto-PGF1 alpha/TxB2 ratio indicates a low resistance to platelet adhesion and aggregation, which may be a contributory cause of the thrombogenicity of vascular grafts and may possibly be involved in the pathogenesis of neointimal fibrous hyperplasia.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Female; Humans; Male; Sheep; Thrombosis; Thromboxane B2; Thromboxanes; Umbilical Veins

Topics: Animals; Arteriosclerosis; Blood Platelets; Diet, Atherogenic; Dietary Fats; Disease Models, Animal; Epoprostenol; Fatty Acids; Liver; Phospholipids; Prostaglandins; Rabbits; Rats; Thrombosis; Thromboxane B2; Thromboxanes

It has been suggested that aspirin (ASA) would be more effective as an antithrombotic agent if employed in a dose which inhibits platelet thromboxane synthesis selectively, sparing vascular synthesis of prostaglandin I2 (PGI2). We have studied the effect of ASA concentration on rabbit platelet and aortic cyclooxygenase activity in vitro and the effect of administration of varying doses of ASA to rabbits on the cyclooxygenase activity of these tissues ex vivo. We also measured plasma levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) after infusion of arachidonic acid into rabbits pretreated with varying doses of ASA. Concentrations or doses of ASA required for 50% inhibition were about 10 times greater for the arterial enzyme than for the platelet enzyme in the in vitro and ex vivo studies. However, the dose required for complete inhibition of the platelet enzyme was 1 mg/kg and this dose inhibited the vascular enzyme by 62%. We conclude that meaningful selective inhibition of cyclooxygenase activity of the two tissues is difficult to achieve in the rabbit. Since doses of ASA which are antithrombotic appear to be high enough to almost totally inhibit vascular PGI2 synthesis, PGI2 synthesis may be a relatively unimportant mechanism for prevention of thrombosis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aorta; Arachidonic Acid; Arachidonic Acids; Aspirin; Blood Platelets; Cyclooxygenase Inhibitors; Epoprostenol; Female; In Vitro Techniques; Rabbits; Thrombosis; Thromboxane B2

To elucidate the role of thromboxane A2 in the development of endotoxin shock following administration of endotoxin, the effects of three thromboxane A2 synthetase inhibitors, (E)-3-(4-(1-imidazolyl)phenyl)-2-propenoic acid hydrochloride monohydrate (OKY-046), sodium (E)-3-(4-(3-pyridylmethyl)phenyl)-2-methylacrylate (OKY-1581) and imidazole were examined. Intravenous administration of E. Coli endotoxin (3 mg/kg) produced shock and all rats died within ten hours. Pretreatment with thromboxane A2 synthetase inhibitors markedly improved the survival rates. The untreated endotoxin shock group showed marked increase in thromboxane B2 levels in the venous blood, while no such changes were seen in the pretreated groups. There were no statistically significant differences in 6-keto prostaglandin F1 alpha levels in the venous blood. In the untreated shock group, microthrombi were observed in 64% of the glomeruli in the kidneys two hours after endotoxin injection. In the groups pretreated with OKY-046, OKY-1581 and imidazole, microthrombi were seen only in 22, 19 and 24%, respectively. Thus, thromboxane A2 plays an important role in the development of endotoxin shock and thromboxane A2 synthetase inhibitors, in particular OKY-046 and -1581, are prophylactic.

Topics: Animals; Fibrinogen; Glucuronidase; Kidney; Male; Methacrylates; Oxidoreductases; Platelet Count; Rats; Rats, Inbred Strains; Shock, Septic; Thrombosis; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Thromboxanes

1 Acute thrombosis was induced in the carotid arteries of anaesthetized rabbits by local electrical stimulation (1 mA for 2 min) of the vessel wall. Histological findings confirmed the platelet-rich composition of the thrombus. Platelet accumulation at the stimulus site was quantitated with 111Indium-labelling of autologous platelets. 2 In rabbits injected intravenously with either the thromboxane synthetase inhibitor dazoxiben 2 mg/kg or aspirin 10 mg/kg, accumulation of labelled platelets was considerably reduced. Animals which received vehicle injection only, showed no such reduced thrombus formation. 3 In separate experiments in anaesthetized rabbits, the levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha in clotting blood were measured in blood samples taken from animals which had received the above drug treatments. Aspirin markedly reduced the production of both arachidonate metabolites. In contrast, dazoxiben almost totally inhibited TXB2 production but caused a 3.5-fold increase in the levels of 6-keto PGF1 alpha. 4 These findings demonstrate an antithrombotic effect and confirm the mechanistic selectivity of a thromboxane synthetase inhibitor.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Blood Platelets; Electric Stimulation; Imidazoles; Indium; Male; Oxidoreductases; Rabbits; Radioisotopes; Thrombosis; Thromboxane B2; Thromboxane-A Synthase

The mechanism of thrombus formation in hyperlipidemia was studied. Attempts at artificial creation of an arterial thrombus in control rabbits stenosing the femoral artery by ligature were not successful unless ellagic acid was administered by injection. However, in rabbits with hyperlipidemia, mere creation of stenosis in the femoral artery resulted in a high percentage of thrombus formation. In rabbits with hyperlipidemia, both thromboxane (Tx) A2 biosynthesis in platelets and prostacyclin (PGI2) biosynthesis in the aorta were increased and these changes were noted at the level of cyclooxygenase in the arachidonic acid metabolic pathway. Therefore, these results suggest that thrombi are likely to be formed in hyperlipidemia and that such thrombus formation is due largely to platelet hyperfunction.

Topics: Animals; Aorta, Thoracic; Arachidonic Acid; Arachidonic Acids; Blood Coagulation; Blood Platelets; Femoral Artery; Hyperlipidemias; Male; Partial Thromboplastin Time; Platelet Aggregation; Prostaglandins F; Prostaglandins H; Prothrombin Time; Rabbits; Thrombosis; Thromboxane B2

A study of platelet aggregation and MDA production after an oral dose of 300 mg aspirin indicated that partial recovery of platelet function occurred when approximately one third of the circulating platelets had been replaced by new (uninhibited) platelets. In vitro studies on mixtures of normal and aspirin inhibited platelets indicated partial restoration of platelet aggregation and thromboxane B2 production with as little as 10% of normal platelets in some subjects. Restoration of full function required a higher proportion of normal platelets. There was considerable variation between subjects. These data suggest that complete suppression of platelet functions in all normal subjects requires daily administration of the drug.

Topics: Adenosine Diphosphate; Aspirin; Cell Survival; Collagen; Depression, Chemical; Dose-Response Relationship, Drug; Epinephrine; Humans; Malondialdehyde; Platelet Aggregation; Platelet Function Tests; Thrombosis; Thromboxane B2

Cultured bovine endothelial cells produce an extensive underlying extracellular matrix (ECM) which closely resemble the vascular subendothelial basal lamina in its organization and chemical composition. This naturally produced ECM was used to study the interaction of platelets with the subendothelium when exposed or covered with vascular endothelial cells. Incubation of platelet rich plasma with the ECM induced a rapid and massive platelet adherence, aggregation, thromboxane formation and release reaction. These were demonstrated using phase and scanning electron microscopy, Indium-111 or (14C)-serotonin labelled platelets, and a radioimmunoassay for thromboxane B2. In contrast to the ECM no platelet activation was induced either by uncoated plastic dishes or ECM covered with a confluent endothelial cell monolayer. Aspirinized platelets failed to undergo aggregation and degranulation, when incubated with the ECM. Culture dishes coated with characteristic constituents of the basal lamina such as collagen type IV and type V or fibronectin induced a much lower platelet reactivity as compared with ECM coated dishes. Digestion of ECM components (collagen, fibronectin, hyaluronic acid, and chondroitin sulphate) by specific enzymes was not associated with a substantial decrease in its platelet reactivity. Furthermore, exposure of ECM to sodium dodecyl sulphate or sodium periodate, or freezing and thawing did not decrease its biological activity. In contrast, platelet activation was completely abolished following heat denaturation or glutaraldehyde fixation of the ECM. The availability of a naturally produced ECM provides an appropriate model to study the interaction of platelets with the subendothelium in a controlled system which is isolated from other components of the vessel wall.

Topics: Animals; Basement Membrane; Blood Platelets; Blood Vessels; Cattle; Cells, Cultured; Collagen; Endothelium; Fibronectins; In Vitro Techniques; Models, Biological; Platelet Aggregation; Thrombosis; Thromboxane B2

Prostacyclin is a potent but unstable vasodilator, and inhibitor of platelet aggregation, which is produced by blood vessel walls. Platelet aggregability may be constantly conditioned in vivo by local or circulating prostacyclin. Prostacyclin is important in the maintenance of vascular homeostasis and may be implicated in certain disease states. The use of prostacyclin in antithrombotic therapy appears logical, considering its action in increasing platelet cyclic AMP and reducing aggregation; its potential in antithrombotic therapy is presently being explored.

Topics: Arteriosclerosis; Blood Coagulation; Epoprostenol; Extracorporeal Circulation; Heparin; Humans; Lipid Peroxides; Platelet Aggregation; Prostaglandins; Thrombosis; Thromboxane B2

Topics: Cardiopulmonary Bypass; Fibrinogen; Fibrinopeptide A; Humans; Platelet Activation; Radioimmunoassay; Thrombosis; Thromboxane B2