thromboxane-b2 and Diabetes-Mellitus

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

Thromboxane A2 (TxA2), the predominant cyclooxygenase product of human platelets, is a potent vasoconstrictor and platelet agonist. Although its biological properties are readily appreciable in vitro, it has been difficult to define its biological importance in vivo. To a large extent this reflected the problems associated with efforts to monitor biosynthesis of this eicosanoid and the lack of selective pharmacological probes that prevented the synthesis of TxA2 or antagonized its biological action in vivo. Recently the analysis of urinary metabolites of TxB2 has become simplified so that the methodology is readily applicable to clinical studies. This provides a noninvasive, time-integrated index of Tx biosynthesis. Although one cannot definitively establish a tissue of origin for metabolites measured in urine, indirect evidence suggests that urinary TxB2 derives primarily from the kidney whereas its dinor metabolite predominantly reflects platelet biosynthesis under physiological conditions. Although plasma concentrations of TxB2 are readily confounded by platelet activation ex vivo, the enzymatic metabolites formed from TxB2 have recently been identified and appear to bypass this problem. Combined analysis of long-lived (e.g., 11-dehydro-TxB2) and short-lived (e.g., 2,3-dinor-TxB2) metabolites in plasma promise to more accurately localize phasic increases in the biosynthesis of TxA2 and have been paralleled by the development of antagonists of the TxA2/prostaglandin endoperoxide receptor and their study of humans. The use of such specific probes in conditions characterized by abnormal biosynthesis of TxA2 promises to define the biological role of this mediator for humans.

Topics: Arachidonic Acid; Arachidonic Acids; Blood Platelets; Cardiovascular Diseases; Diabetes Mellitus; Female; Humans; Liver; Male; Prostaglandin Endoperoxides; Thromboxane A2; Thromboxane B2

The alterations in the metabolism of arachidonic acid to prostaglandin I2 (prostacyclin), a vasodilator antiaggregatory substance, and thromboxane A2, a vasoconstrictor proaggregatory substance, in diabetes mellitus are reviewed in this article. When tested in vitro, platelet aggregation is enhanced in some patients with diabetes mellitus. The synthesis of thromboxane B2, the stable metabolite of thromboxane A2, by platelets is increased in patients with diabetes mellitus compared with control subjects. This increased synthesis appears to play a role in the enhanced platelet aggregation since the latter can be reversed by aspirin treatment and in vitro by the thromboxane receptor-antagonist 13-azaprostanoic acid. Vascular prostacyclin synthesis is decreased in both patients and experimental animals with diabetes mellitus. Treatment of experimental animals with insulin reverses the decreased synthesis of prostacyclin. The etiology of the altered arachidonic acid metabolism remains uncertain but appears to be multifactorial and includes alterations in metabolic control and circulating immune complexes. The increased ratio of thromboxane A2 to prostacyclin, which favors an enhanced thrombotic state, may play a role in the accelerated vascular disease of diabetes mellitus.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Arthritis, Rheumatoid; Aspirin; Blood Platelets; Diabetes Mellitus; Epoprostenol; Humans; Insulin; Platelet Aggregation; Thromboxane A2; Thromboxane B2

There is an abundance of information suggesting that prostaglandins are involved in the development and clinical expression of atherosclerosis. Many studies demonstrate a relationship between prostaglandins and the risk factors for peripheral and coronary artery disease. Thus, part of the mechanism by which hyperlipidemia, diabetes mellitus, smoking, hypertension, sex hormones, age, heredity, emotional stress and diet contribute to the development and progression of atherosclerosis may be through an imbalance between thromboxane A2 and prostaglandin I2. Recent studies show a temporal relationship between acute ischemic events (specifically, unstable angina) and a transcardiac increase in thromboxane B2, while others demonstrate a salutary effect of disaggregatory and vasodilatory prostaglandins in such patients. If prostaglandins and thromboxane prove important in ischemic vascular disease, attention will be directed at the correction of their pathologic imbalance. This may be accomplished by dietary manipulation as well as by the development of prostaglandin receptor antagonists or inhibitors of specific prostaglandin pathways.

Topics: Age Factors; Arteriosclerosis; Coronary Disease; Diabetes Mellitus; Diet; Epoprostenol; Gonadal Steroid Hormones; Humans; Hyperlipidemias; Hypertension; Prostaglandin Antagonists; Prostaglandins; Receptors, Prostaglandin; Risk; Smoking; Stress, Physiological; Thromboxane A2; Thromboxane B2

Aspirin is widely used for cardioprotection with its antiplatelet effects due to the blocking of thromboxane A2 production. However, it has been suggested that platelet abnormalities in those with diabetes prevent adequate suppression with once daily aspirin.. In the ASCEND randomized double-blind trial of aspirin 100 mg once daily versus placebo in participants with diabetes but no history of cardiovascular disease, suppression was assessed by measuring 11-dehydro-thromboxane B2 excretion in urine (U-TXM) in a randomly selected sample of 152 participants (76 aspirin arm, 74 placebo arm), plus 198 (93 aspirin arm, 105 placebo arm) adherent to study drugs and selected to maximize the numbers ingesting their last tablet 12-24 h before urine sampling. U-TXM was assayed using a competitive ELISA assay in samples mailed a mean of 2 years after randomization, with time since taking last aspirin/placebo tablet recorded at the time of sample provision. Effective suppression (U-TXM < 1500 pg/mg creatinine) and percentage reductions in U-TXM by aspirin allocation were compared.. In the random sample, U-TXM was 71% (95% CI 64-76%) lower among aspirin vs placebo-allocated participants. Among adherent participants in the aspirin arm, U-TXM was 72% (95% CI 69-75%) lower than in the placebo arm and 77% achieved effective suppression overall. Suppression was similar among those who ingested their last tablet more than 12 h before urine sampling with levels in the aspirin arm 72% (95% CI 67-77%) lower than in the placebo arm and 70% achieving effective suppression.. Daily aspirin significantly reduces U-TXM in participants with diabetes, including at 12-24 h after ingestion.. ISRCTN ISRCTN60635500. Registered on 1 Sept 2005; ClinicalTrials.gov NCT00135226. Registered on 24 Aug 2005.

Topics: Aspirin; Cardiovascular Diseases; Diabetes Mellitus; Humans; Thromboxane B2

Laropiprant, an antagonist of the PGD(2) receptor, DP1, is effective in reducing the flushing symptoms associated with extended-release (ER) niacin and thereby improves the tolerability of niacin therapy for dyslipidemia. Because PGD(2) has been reported to inhibit platelet aggregation in vitro, it has been speculated that antagonism of DP1 may enhance platelet reactivity. Three clinical studies evaluated the potential effect of laropiprant, with or without coadministration of ER niacin, on in vivo platelet function in healthy subjects and hypercholesterolemic or diabetic subjects by measuring urinary levels of 11-dehydrothromboxane B(2) (11-dTxB(2)), a marker of in vivo platelet activation. Following 7 days of multiple-dose administration, coadministration of laropiprant with ER niacin did not increase urinary 11-dTxB(2) levels compared to ER niacin alone in healthy, hypercholesterolemic, or diabetic subjects. In hypercholesterolemic and diabetic subjects, laropiprant did not increase urinary 11-dTxB(2) levels compared to placebo. These results demonstrate that laropiprant does not enhance in vivo platelet reactivity, either alone or in combination with niacin.

Topics: Adolescent; Adult; Aged; Biomarkers; Blood Platelets; Cross-Over Studies; Delayed-Action Preparations; Diabetes Mellitus; Double-Blind Method; Epoprostenol; Female; Humans; Hypercholesterolemia; Indoles; Male; Middle Aged; Niacin; Platelet Activation; Prostaglandin D2; Receptors, Immunologic; Receptors, Prostaglandin; Thromboxane B2; Young Adult

The methylenetetrahydrofolate reductase (MTHFR) 677 C→T polymorphism may be associated with elevated total homocysteine (tHcy) levels, an independent risk factor for cardiovascular disease. It was the study objective to evaluate in vivo lipid peroxidation and platelet activation in carriers of the MTHFR 677 C→T polymorphism and in non-carriers, in relation to tHcy and folate levels. A cross-sectional comparison of urinary 8-iso-prostaglandin (PG)F(2α) and 11-dehydro-thromboxane (TX)B(2) (markers of in vivo lipid peroxidation and platelet activation, respectively) was performed in 100 carriers and 100 non-carriers of the polymorphism. A methionine-loading test and folic acid supplementation were performed to investigate the causal relationship of the observed associations. Urinary 8-iso-PGF(2α) and 11-dehydro-TXB(2) were higher in carriers with hyperhomocysteinaemia than in those without hyperhomocysteinaemia (p<0.0001). Hyperhomocysteinaemic carriers had lower folate levels (p=0.0006), higher urinary 8-iso-PGF(2α) (p<0.0001) and 11-dehydro-TXB(2) (p<0.0001) than hyperhomocysteinaemic non-carriers. On multiple regression analysis, high tHcy (p<0.0001), low folate (p<0.04) and MTHFR 677 C→T polymorphism (p<0.001) independently predicted high rates of 8-iso-PGF(2α) excretion. Methionine loading increased plasma tHcy (p=0.002), and both urinary prostanoid metabolites (p=0.002). Folic acid supplementation was associated with decreased urinary 8-iso-PGF(2α) and 11-dehydro-TXB2 excretion (p<0.0003) in the hyperhomocysteinaemic group, but not in the control group, with substantial inter-individual variability related to baseline tHcy level and the extent of its reduction. In conclusion, hyperhomocysteinaemia due to the MTHFR 677 C→T polymorphism is associated with enhanced in vivo lipid peroxidation and platelet activation that are reversible, at least in part, following folic acid supplementation. An integrated biomarker approach may help identifying appropriate candidates for effective folate supplementation.

Topics: Biomarkers; Cardiovascular Diseases; Comorbidity; Cross-Sectional Studies; Diabetes Mellitus; Dinoprost; Dyslipidemias; Folic Acid; Homocystinuria; Humans; Hyperhomocysteinemia; Lipid Peroxidation; Methionine; Methylenetetrahydrofolate Reductase (NADPH2); Muscle Spasticity; Oxidative Stress; Platelet Activation; Polymorphism, Single Nucleotide; Psychotic Disorders; Smoking; Thromboxane B2

The phenomenon called aspirin resistance is being intensively discussed.. To evaluate the biochemical aspirin response, the method of urinary 11-dehydro TXB2 levels measurement was used. Quantitative detection of TXB2 in urine was determined by competitive enzyme immunoassay, using human Thromboxane B2 ELISA-kit. We investigated the urine samples from 69 patients.. The mean urinary levels of 11-dehydro TXB2 were significantly lower in patients in the primary and secondary types of aspirin prevention comparing with the control group of patients not taking aspirin. The difference in thromboxane concentrations between the two groups of patients taking aspirin did not reach statistical significance. Our results did not show significant differences in the biochemically measured aspirin response when comparing diabetics with non-diabetics. Similarly, the observed tendency to higher thromboxane levels in women did not show to be significantly different from men.. Our pilot study did not show any significant differences among patients at different cardiovascular risk. Since there is currently no standard laboratory method to detect aspirin non-responders available, the term aspirin resistance remains controversial and requires further research. Every effort should be done to improve patients' compliance and to prevent clinically relevant interactions of aspirin with ibuprofen. The elimination of these two factors as was the case in our study may provide better efficacy of the antithrombotic prevention by aspirin (Fig. 2, Tab. 4, Ref. 19). Full Text (Free, PDF) www.bmj.sk.

Topics: Aged; Aspirin; Cardiovascular Diseases; Diabetes Mellitus; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Platelet Aggregation Inhibitors; Risk; Thromboxane B2

The antiplatelet effect of aspirin varies individually. This study evaluated whether the antiplatelet effect of aspirin associates with polymorphisms in the genes coding for cyclo-oxygenase-1 (COX-1) and several platelet glycoprotein (GP) receptors in patients with stable coronary artery disease (CAD). Blood samples were collected from 101 aspirin-treated (mean 100 mg/d) patients. Compliance to treatment was assessed by plasma salicylate measurement. Platelet functions were assessed by two methods: 1) Response to arachidonic acid (AA, 1.5 mmol/L in aggregometry, and 2) PFA-100, evaluating platelet activation under high shear stress in the presence of collagen and epinephrine (CEPI). Aspirin non-response was defined as: 1) slope steeper than 12%/min in AA-aggregations, and 2) by closure time shorter than 170 s in PFA-100. The methods used detected different individuals as being aspirin non-responders. Five and 21 patients, respectively, were non-responders according to AA-induced aggregation and PFA-100. Increased plasma thromboxane B2 levels correlated with poor aspirin-response measured with both AA-induced aggregations and PFA-100 (P = 0.02 and P = 0.003, respectively). Of the non-responders detected by AA, 3 of 5 (60%) carried the rare G allele for the -A842G polymorphism of COX-1 in contrast to 16 of 96 (17%) responders (P = 0.016). Diabetes was associated with poor response. Aspirin non-response detected by PFA-100 associated with C13254T polymorphism of GP VI and female gender (P = 0.012 and P = 0.019, respectively). Although two patients were possibly non-compliant, this did not effect present conclusions. Evaluation of aspirin efficacy by AA-induced aggregation and PFA-100 detected different individuals, with different genotypic profiles, as being aspirin non-responders.

Topics: Adult; Aged; Aged, 80 and over; Arachidonic Acid; Aspirin; Coronary Artery Disease; Cyclooxygenase 1; Diabetes Mellitus; Female; Genotype; Humans; Male; Middle Aged; Pharmacogenetics; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Platelet Membrane Glycoproteins; Polymorphism, Single Nucleotide; Sex Factors; Thromboxane B2

Diabetes mellitus (DM) is associated with enhanced lipid peroxidation and persistent platelet activation. We tested the hypothesis that the in vivo formation of the F2-isoprostane 8-iso-prostaglandin (PG)F2alpha, a bioactive product of arachidonic acid peroxidation, is enhanced in DM and contributes to platelet activation.. Urine samples were obtained from 85 diabetic patients and 85 age- and sex-matched healthy subjects for measurement of immunoreactive 8-iso-PGF2alpha and 11-dehydro-thromboxane B2 (TXM), an in vivo index of platelet activation. Sixty-two had non-insulin-dependent (NID)DM, and 23 had insulin-dependent (ID) DM. Vitamin E supplementation, metabolic control, and cyclooxygenase inhibitors were used to investigate the mechanisms of formation of 8-iso-PGF2alpha in this setting. Urinary 8-iso-PGF2alpha excretion was significantly higher (P=0.0001) in NIDDM patients (419+/-208 pg/mg creatinine; range 160 to 1014) than in age-matched control subjects (208+/-92; 41 to 433). Urinary 8-iso-PGF2alpha was linearly correlated with blood glucose and urinary TXM. 8-iso-PGF2alpha excretion was also significantly (P=0. 0001) higher in IDDM patients (400+/-146; 183 to 702) than in control subjects (197+/-69; 95 to 353). Vitamin E supplementation (600 mg/d for 14 days) was associated with a statistically significant reduction in both urinary 8-iso-PGF2alpha (by 37%) and TXM (by 43%) in 10 NIDDM patients. Improved metabolic control was associated with a significant (P=0.0001) reduction in 8-iso-PGF2alpha and TXM excretion by 32% and 41%, respectively, in 21 NIDDM patients. 8-iso-PGF2alpha was unchanged after 2-week dosing with aspirin and indobufen despite profound suppression of TXM excretion.. We conclude that DM is associated with increased formation of F2-isoprostanes, as a correlate of impaired glycemic control and enhanced lipid peroxidation. This may provide an important biochemical link between impaired glycemic control and persistent platelet activation. These results provide a rationale for dose-finding studies of antioxidant treatment in diabetes.

Topics: Adult; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Dinoprost; F2-Isoprostanes; Female; Humans; Lipid Peroxidation; Male; Middle Aged; Platelet Activation; Thromboxane B2; Vitamin E

Levels of the stable urinary metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 (11-dehydro-TXB2) and 2,3-dinor-6-keto-prostaglandin F1alpha (2,3-dinor-6-keto-PGF1alpha) were measured in diabetics to elucidate the relation between the thromboxane A2/prostacyclin (TX/PGI) balance and pathological states of diabetes mellitus. 11-Dehydro-TXB2 and 2,3-dinor-6-keto-PGF1alpha were derivatized to methyl ester-propylamide-dimethylisopropylsilyl ether and methyl ester-methoxime-dimethylisopropylsilyl ether derivatives, respectively, and applied to a gas chromatography/selected ion monitoring. The TX/PGI ratios of diabetics were higher than those of healthy volunteers, suggesting the hypercoagulative states of this disease. The ratios showed positive correlations with the levels of blood glucose. The levels of hemoglobin A1c and triglyceride were correlated weakly with the ratio. Some of the patients who had relatively low levels of blood glucose also showed high TX/PGI ratios. Furthermore, the ratio increased in the order of the groups 1, 2, and 3; group 1 contained patients who did not take medicine for diabetes, group 2 contained those who took oral hypoglycemic agents, and group 3 contained those who received insulin therapy. These observations indicate that the TX/PGI ratio reflects the pathological conditions of diabetes and is a useful marker, having few different features from other markers that are presently used.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Biomarkers; Blood Glucose; Diabetes Mellitus; Diet Therapy; Epoprostenol; Exercise; Female; Gas Chromatography-Mass Spectrometry; Hemoglobin A; Humans; Hypoglycemic Agents; Male; Middle Aged; Prostaglandins F; Thromboxane A2; Thromboxane B2; Triglycerides

1. The obese fa/fa Zucker rat is a genetic model of obesity and insulin resistance which develops a number of metabolic and endocrine features of non-insulin-dependent diabetes, including hypertension, proteinuria and glomerular sclerosis. 2. We have investigated the urinary excretion of the metabolites of thromboxane (thromboxane B2) and prostacyclin (6-keto prostaglandin F1 alpha), and of endothelin and cyclic GMP as markers for changes in the balance of renal haemodynamic factors in the obese Zucker rat. 3. Obese fa/fa Zucker rats were hypertensive compared with their lean counterparts (161 +/- 3 and 138 +/- 3 mmHg respectively, P < 0.01); obese animals were also markedly proteinuric (16.7 +/- 6.7 versus 1.1 +/- 0.1 mg/ml) and albuminuric (8.3 +/- 2.9 versus 0.4 +/- 0.25 mg/ml) and excreted less creatinine than lean animals (all P < 0.01). Urinary excretion of endothelin was greater in obese rats (123 +/- 24 versus 62 +/- 10 pg/15 h, P < 0.05) as was the level of pre-proendothelin mRNA, but excretion of cyclic GMP was depressed (12.5 +/- 1.6 versus 27.2 +/- 3.1 nmol/ 15 h, P < 0.01). Histological examination of kidneys from obese animals showed evidence of focal glomerulosclerosis and cortical tubular damage. 4. These results show that increased urinary endothelin is associated with proteinuria and early stage nephropathy in this animal model of non-insulin-dependent diabetes mellitus. This finding, coupled with a decreased excretion of cyclic GMP, suggests that these increased renal vasoconstrictor/vasodilator forces might contribute to the renal functional changes in non-insulin-dependent diabetes mellitus.

Topics: 6-Ketoprostaglandin F1 alpha; Albuminuria; Animals; Cyclic GMP; Diabetes Mellitus; Diabetes Mellitus, Type 2; Endothelin-1; Immunohistochemistry; Kidney; Male; Obesity; Rats; Rats, Zucker; RNA, Messenger; Statistics, Nonparametric; Thromboxane B2

Using fura-2, a fluorescence indicator, we evaluated the changes of platelet cytosolic free calcium concentration ([Ca2+]i) and its role in regulation of thromboxane B2 (TXB2) synthesis in patients with diabetes mellitus (DM group, n = 27) and in healthy subjects (control group, n = 15). The A23187-evoked elevation of [Ca2+]i and TXB2 production were higher in the DM group than in the control group (P < 0.01 respectively). The rise in [Ca2+]i was correlated positively with TXB2 production. In contrast, stimulation with arachidonic acid, TXB2 production was unaltered between the groups, although arachidonate-induced [Ca2+]i was higher in the DM group than in the control group (P < 0.05). The results suggested that changes in platelets [Ca2+]i in diabetic subjects may contribute to increase in TXB2 synthesis, involved libration of free arachidonate from membrance phospholipids by the action of phospholipases. Since no significant difference was found between the diabetic patients with microangiopathy (n = 13) and without microangiopathy (n = 14), the results above may be involved in the development of diabetic microangiopathy.

Topics: Biological Transport, Active; Blood Platelets; Calcium; Diabetes Mellitus; Diabetic Angiopathies; Female; Humans; Male; Thromboxane B2

Platelets of patients with diabetes and no evidence of macroangiopathy produce normal amounts of thromboxane (Tx) B2 in vivo, whereas they usually show increased production in vitro. Since in vitro studies have been usually performed in citrated PRP, we tested the hypothesis that the discrepancy between in vivo and in vitro studies is due to the low concentration of plasma ionized calcium ([Ca2+]o) that is present in citrated PRP. In fact, low [Ca2+]o artifactually potentiates the platelet TxB2 production in vitro. Forty patients with diabetes mellitus and 37 matched controls were studied. Blood was anticoagulated with citrate, the thrombin inhibitor D-phenylalanyl-l-prolyl-l-chloromethylketone (PPACK) or both anticoagulants. Platelet aggregation, release of 14C-serotonin and TxB2 production were induced in platelet rich plasma (PRP) by several agonists. The following results were obtained: i) Citrated PRP: Arachidonic acid induced aggregation (p < 0.01) and TxB2 production (p < 0.02) were significantly greater in patients than in controls. No statistically significant differences were found with other agonists. ii) PPACK PRP: No statistically significant difference was found between diabetic platelets and controls. iii) PPACK plus citrate PRP: The results were not different from those obtained with citrate alone. Therefore, our results show that diabetic platelets produce normal amounts of TxB2 in vitro when the [Ca2+]o is physiological.

Topics: Adult; Amino Acid Chloromethyl Ketones; Anticoagulants; Antithrombins; Blood Platelets; Calcium; Citrates; Citric Acid; Diabetes Mellitus; Humans; In Vitro Techniques; Middle Aged; Platelet Count; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Diabetes Mellitus; Diabetic Retinopathy; Humans; Thromboxane B2

Platelet aggregation, platelet cAMP levels and thromboxane B2 (TXB2) synthesis had been investigated in 40 diabetics (20 with microangiopathy and 20 without) and 24 normal controls. The washed platelets, but not platelet rich plasma (PRP), from the diabetics show greater sensitivity to aggregation in response to thrombin, collagen and arachidonic acid than controls (P less than 0.05). Platelets from the diabetics contain the significantly decreased cAMP levels (P less than 0.01) and synthesize the significantly greater amount of TXB2 (P less than 0.01) when induced by thrombin or collagen. Conversion of exogenously added arachidonic acid to TXB2 remained unchanged (P greater than 0.05). cAMP levels in platelets from the diabetics exhibited a significant negative linear correlation with thrombin- and collagen-induced TXB2 synthesis. There was no significant difference in platelet aggregation, platelet cAMP levels and platelet TXB2 synthesis between the diabetics with and without microangiopathy. It was suggested that in the diabetic platelets: The observed increase in platelet thromboxane A2 (TXA2) synthesis should be due to the increased activity of arachidonic acid-metabolizing system, most likely at phospholipase site; the elevated platelet TXA2 levels should inhibit platelet membrane-associated adenylate cyclase which lowered the cAMP levels in platelets; and this alternation should be the mechanism of platelet hyperaggregability, which might contribute in some way to diabetic microangiopathy.

Topics: Adult; Blood Platelets; Cyclic AMP; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Female; Humans; Male; Middle Aged; Platelet Aggregation; Thromboxane B2

The effects of smoking, aspirin ingestion, and sex differences on bleeding times and bleeding time thromboxane B2 and 6-keto-prostaglandin (PG)F1 alpha production were examined. Nonsmoking men produced more thromboxane B2 (3.99 +/- 0.76 ng/ml) than nonsmoking women (2.13 +/- 0.24 ng/ml). Female smokers produced more thromboxane B2 (5.01 +/- 0.97 ng/ml) than nonsmoking women. Twenty-four hours after a single dose of 600 mg aspirin, in vitro production of thromboxane B2 in response to collagen fell by 95%, whereas in vivo production of thromboxane B2 and 6-keto-PGF1 alpha in bleeding time blood fell by 87% and 66%, respectively. Subjects with the lowest absolute levels of thromboxane B2 24 hours after aspirin were also those with the longest postaspirin bleeding times. Recovery of 6-keto-PGF1 alpha production was faster than recovery of thromboxane B2 production, but 6-keto-PGF1 alpha production for most subjects was still below basal 72 hours after aspirin. The influence of two different doses of long-term aspirin (80 mg every other day and 325 mg daily) on the in vivo production of thromboxane B2 and 6-keto-PGF1 alpha was studied in normals and diabetics. After 14 days of 80 mg aspirin every other day, thromboxane B2 and 6-keto-PGF1 alpha production were both substantially inhibited (93% and 78%, respectively). After 14 days of 325 mg aspirin daily, thromboxane B2 production was similarly substantially inhibited (93%), whereas 6-keto-PGF1 alpha was significantly less affected (only 45% inhibition). Study of a second group of five normal subjects confirmed that 6-keto-PGF1 alpha production was significantly inhibited 24 hours after the first dose of 325 mg aspirin but was not significantly less than basal after 14 days of 325 mg aspirin. The results suggest that 325 mg aspirin daily is more antithrombotic compared with 80 mg every other day due to the superior preservation of prostacyclin production.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aspirin; Bleeding Time; Diabetes Mellitus; Dose-Response Relationship, Drug; Female; Humans; Male; Middle Aged; Sex Characteristics; Smoking; Thromboxane B2; Time Factors

Topics: Adolescent; Adult; Aged; Cyclic AMP; Diabetes Mellitus; Diabetic Angiopathies; Female; Humans; Male; Middle Aged; Platelet Aggregation; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Aged; Angina Pectoris; Animals; Diabetes Mellitus; Female; Humans; Hypercholesterolemia; Male; Middle Aged; Pre-Eclampsia; Pregnancy; Rabbits; Radioimmunoassay; Rats; Rats, Inbred Strains; Thromboxane B2

To elucidate the bleeding tendency that follows the administration of ticlopidine, we investigated the skin bleeding time and some ex vivo functions of platelets from nine patients with insulin-dependent diabetes before and 2 weeks after daily doses of 500 mg ticlopidine. Ticlopidine significantly prolonged bleeding time and reduced platelet reactivity to fixed, relatively high concentrations of aggregating agents, without interfering with thromboxane B2 formation. We used a rotating probe device at a relatively low shear rate (570 sec-1) to measure platelet adhesion to human subendothelium. This system was able to detect an impairment of platelet adhesion dependent on glycoprotein (GP) Ib defect (Bernard Soulier syndrome) or on low platelet von Willebrand factor content, but was insensitive to platelet GPIIb-IIIa defect (Glanzmann's thrombasthenia). In our patients, platelet adhesion was consistently reduced after the administration of ticlopidine. We conclude that ticlopidine is an inhibitor of platelet function that modulates the interaction between platelets. The drug also appears to interfere with mechanisms that modulate platelet-subendothelium interaction at relatively low shear rates. This double action could be relevant in the prevention of vasculopathy in patients with diabetes.

Topics: Adult; Bleeding Time; Diabetes Mellitus; Diabetes Mellitus, Type 1; Endothelium, Vascular; Female; Fibronectins; Humans; Male; Middle Aged; Platelet Adhesiveness; Platelet Aggregation; Thromboxane B2; Ticlopidine

The in vivo synthesis of thromboxane A2 and prostacyclin was estimated in 23 diabetics through measurements of the major urinary metabolites 2,3-dinor-thromboxane B2 and 2,3-dinor-6-keto-PGF 1 alpha utilizing gas chromatography-mass spectrometry. Mean excretion was similar to that in non-diabetic subjects. The possible influence of hyperglycemia on the excretion of 2,3-dinor-thromboxane B2 and 2,3-dinor-6-keto-PGF 1 alpha was evaluated in three ways: by measuring excretion before and during an acute 9-h normalization of hyperglycemia through an artificial pancreas (Biostator) as well as by comparing excretion before and 7-12 days or 40-180 days after the initiation of insulin treatment. Despite significant reducing effects on hyperglycemia or on levels of hemoglobin A 1c, no effects on the excretion of the thromboxane and prostacyclin metabolites could be found. Abnormal formation of thromboxane or prostacyclin is not a generalized feature of the diabetic state.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Blood Glucose; Diabetes Mellitus; Female; Glycated Hemoglobin; Humans; Insulin; Male; Middle Aged; Thromboxane B2

Thromboxane and prostacyclin metabolite determinations (radioimmunoassay) were performed in obliterative atherosclerosis and in diabetes mellitus with microangiopathy. The shift of these metabolites to the thromboxane side could have been documented in both diseases. This phenomenon calls attention to an increased platelet activation and endothelial cell damage. In a third group patients received aspirin (500 mg on alternative days) which caused a marked inhibition of both thromboxane and prostacyclin production, measured this way. The possible role of altered balance of these two prostanoids in atherogenesis and diabetic angiopathy is discussed.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Arteriosclerosis; Aspirin; Diabetes Mellitus; Epoprostenol; Female; Humans; Male; Middle Aged; Prostaglandin-Endoperoxide Synthases; Thromboxane A2; Thromboxane B2

Although several investigators have attempted to measure the plasma levels of prostacyclin (PGI2) and thromboxane A2 (TXA2) in diabetes and normal subjects, their results have been controversial. In this study, we measured plasma PGI2 and TXA2 levels in diabetic patients and normal subjects. The plasma PGI2 and TXA2 were determined by RIA as 6-keto-PGF1 alpha and TXB2, respectively. The plasma levels of 6-keto-PGF1 alpha were significantly reduced in diabetics with microangiopathy (52.5 +/- 18.9 pg/ml, mean +/- SE, p less than 0.05) compared with those of normal subjects. Diabetics as a whole also showed lower levels of 6-keto-PGF1 alpha than normal subjects (57.8 +/- 26.1 vs. 70.2 +/- 20.7 pg/ml), though this was not significant statistically. The plasma 6-keto-PGF1 alpha levels did not significantly correlate with either age of the patients or duration of diabetes in diabetics. Interestingly, however, hemoglobin A1c significantly correlated inversely with 6-keto-PGF1 alpha levels in diabetics without microangiopathy (r = -0.60, p less than 0.05). The plasma levels of TXB2 in diabetics were significantly higher than those of normal subjects (155.2 +/- 69.5 vs. 108.0 +/- 30.0 pg/ml, p less than 0.05). These data suggest that an imbalance of circulating PGI2 and TXA2 may contribute to the development of diabetic microangiopathy.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Blood Glucose; Diabetes Mellitus; Diabetic Retinopathy; Epoprostenol; Glycated Hemoglobin; Humans; Middle Aged; Thromboxane A2; Thromboxane B2

Thromboxane (TX) A2 is a potent vasoconstrictor as well as a proaggregator of platelets. Augmented TXB2 platelet synthesis and attenuated vascular prostacyclin formation have been demonstrated in diabetes mellitus. We undertook to establish a simple method of extracting urinary TXB2 (UTXB2) and to elucidate the pathophysiologic role of renal TXA2 in diabetes mellitus. One-step extraction of UTXB2 with an octadecylsilyl-silica column was sufficient as pretreatment for TXB2 radioimmunoassay because recovery of UTXB2 was good, the eluate was parallel with the dose-response curve, and the value coincided with that obtained by the conventional method. When platelet TXA2 synthesis was completely suppressed by administration of 100 mg aspirin, urinary TXB2 excretion (UTXB2V) declined to 41% of the initial levels, suggesting that renal TXA2 formation contributes significantly to UTXB2V. UTXB2V was 94.5 +/- 14.0 ng/day or 108.8 +/- 17.3 ng/gm creatinine in controls. Approximately half of the patients with diabetes demonstrated a UTXB2 level higher than the mean + 2 SD level of controls. Although UTXB2V did not show a significant correlation with protein excretion, UTXB2V in patients with diabetes with proteinuria greater than 100 mg/day was augmented (224.4 +/- 30.5 ng/day) compared with that in patients with diabetes without proteinuria greater than 100 mg/day. Furthermore, UTXB2V correlated negatively with the p-aminohippuric acid clearance rate, but not with the creatinine clearance rate. The results suggest that renal TXA2 synthesis may be augmented in diabetic nephropathy and may play a pathophysiologic role in renal hemodynamics as well as in protein excretion.

Topics: Adult; Aspirin; Blood Platelets; Diabetes Mellitus; Female; Glomerular Filtration Rate; Humans; Kidney; Male; p-Aminohippuric Acid; Platelet Aggregation; Thromboxane A2; Thromboxane B2

Coagulation parameters, platelet aggregation, and thromboxane production as well as metabolic parameters were measured in 31 diabetic patients, 12 without and 19 with clinically manifest late complications, and in 14 healthy control subjects. Spontaneous in vitro aggregation as well as ADP, collagen, and arachidonic acid induced aggregation were higher in both groups of diabetic patients, without an increase in thromboxane B2 production. In diabetic patients with late complications an increase in fibrinogen, fibrinogen cyanogen bromide peptide, factor VIII related antigen, C1-esterase inhibitor, and antithrombin III was observed in comparison to healthy subjects. Fibrinogen, C1-esterase inhibitor, and factor VIII related antigen were already elevated in diabetic patients without clinically manifest late vascular complications. No strict correlations were found between serum glucose, glycosylated hemoglobin, and glycosylated albumin, on the one hand, and coagulation promoting or inhibiting factors, aggregation or thromboxane B2 production, on the other, in either control or diabetic subjects. Also no correlations existed between the coagulation parameters and the aggregation results. In vitro incubation of pooled normal plasma with different glucose concentrations had no influence on the methods by which the coagulation parameters were measured. These data indicate that rather early in the diabetic state many changes take place in different phases of the thrombostatic process, all resulting in an increased hemostatic diathesis.

Topics: Adult; Antithrombin III; Blood Coagulation Tests; Blood Glucose; Complement C1 Inactivator Proteins; Diabetes Mellitus; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Fibrinogen; Humans; Platelet Aggregation; Thromboxane B2

Topics: Adult; Aged; Animals; Coronary Disease; Diabetes Mellitus; Endotoxins; Escherichia coli; Female; Humans; Male; Middle Aged; Pre-Eclampsia; Pregnancy; Radioimmunoassay; Rats; Rats, Inbred Strains; Thromboxane B2; Toxemia

The discovery of a group of spontaneously diabetic rats has made it possible to examine changes in diabetic animals in the absence of possible confounding toxic effects of diabetogenic agents. The responses of washed platelets to adenosine diphosphate (ADP), thrombin, or collagen have been compared with platelets from spontaneously diabetic rats (these rats were hyperglycemic), their nondiabetic littermates (normoglycemic), and control rats from the same colony. Platelets from the diabetic rats aggregated more extensively in response to ADP than did platelets from the nondiabetic littermates or control animals. In contrast, platelet aggregation and release of granule contents in response to a low thrombin concentration (0.05 U/ml) were greater with platelets from diabetic rats and nondiabetic littermates than with platelets from control rats. A similar effect of collagen on the release of platelet serotonin was observed. Except at low concentrations of thrombin, the enhanced sensitivity to thrombin-induced aggregation and release of granule contents from platelets from diabetic rats or their nondiabetic littermates could not be inhibited by creatine phosphate-creatine phosphokinase (CP/CPK) and aspirin (CP/CPK used at concentrations that inhibited aggregation induced by ADP [10 mumol/L] and aspirin at concentrations that inhibited thromboxane B2 production induced by thrombin [1 U/ml] by 99%). Loss of radioactivity from platelets labeled with 3H-arachidonic acid and the amount of thromboxane B2 formed in response to high concentrations of thrombin (1 U/ml) was greater from platelets from the diabetic rats or their nondiabetic littermates than from control animals. Thus the effect of diabetes on this aspect of arachidonate metabolism is not primarily determined by blood glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Diphosphate; Animals; Arachidonic Acid; Arachidonic Acids; Blood Glucose; Blood Platelets; Collagen; Creatine Kinase; Diabetes Mellitus; Phosphocreatine; Platelet Aggregation; Rats; Thrombin; Thromboxane B2

Endothelial cell damage is considered to be the initial step in the genesis of thrombosis and atherosclerosis. Recently, the adhesion of erythrocytes from patients with diabetes or sickle cell anemia to endothelial cells was found to be increased and correlated with the severity of vascular complications. We have measured by radioimmunoassay the release of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) as an index of prostacyclin (PGI2) production, during red cell adhesion to endothelial cells in culture. The amount of 6-keto-PGF1 alpha released after incubation with normal red cells was similar to that observed with buffer (1.07 +/- 0.32 nmol/10(6) endothelial cells). However, after the adhesion of erythrocytes from patients with diabetes or sickle cell anemia, the amount of 6-keto-PGF1 alpha produced was significantly increased (P less than 0.01) and was correlated with the extent of erythrocyte adhesion (P less than 0.05). Tritium-labeled PGI2 was found to bind to erythrocytes, and the binding was time and concentration dependent. PGI2 release was inhibited by the cyclooxygenase inhibitor (flurbiprofen), whereas red cell adhesion remained unchanged. Fibrinogen potentiated erythrocyte adhesion and PGI2 production. The increase in PGI2 production after the adhesion of red cells from patients with diabetes or sickle cell anemia to endothelial cells indicates that endothelium may be damaged by abnormal erythrocyte adhesion.

Topics: 6-Ketoprostaglandin F1 alpha; Adenosine Diphosphate; Adenosine Triphosphate; Adult; Anemia, Sickle Cell; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Blood Proteins; Blood Vessels; Cell Adhesion; Cells, Cultured; Cyclooxygenase Inhibitors; Diabetes Mellitus; Endothelium; Epoprostenol; Erythrocytes; Fibrinogen; Flurbiprofen; Humans; Leukocytes; Middle Aged; Plasma; Prostaglandins F; Thromboxane B2

We compared the ability of aspirin to suppress platelet aggregation and thromboxane synthesis in ten normal subjects and ten patients with diabetic angiopathy and high rate of entry of new platelets into the circulation. When single doses of 100 to 1,000 mg aspirin were ingested daily for 1 month, there were time gaps between doses in which platelets from diabetics and normals aggregated and formed thromboxane ex vivo in response to the combination of arachidonic acid plus collagen. Similar gaps were also found for diabetics, but not for normals, following four daily doses (every six hours) of 25 or 100 mg. Our data show that dose schedules of aspirin which may suffice in normals are not effective in patients with diabetic angiopathy, presumably because these patients have a high rate of entry of new platelets into the circulation. We suggest that continual suppression of platelet thromboxane synthesis and aggregation by low-dose, "slow-release" preparations of aspirin would be an ideal long-term approach for the prevention of thrombosis in patients with a high rate of entry of new platelets into the circulation.

Topics: Adenosine Triphosphate; Adult; Arachidonic Acid; Arachidonic Acids; Aspirin; Blood Platelets; Collagen; Diabetes Mellitus; Diabetic Angiopathies; Drug Administration Schedule; Female; Humans; Male; Malondialdehyde; Middle Aged; Platelet Aggregation; Thromboxane B2

Topics: Adult; Aged; Blood Coagulation; Blood Glucose; Diabetes Mellitus; Female; Glycated Hemoglobin; Humans; Hypoglycemic Agents; In Vitro Techniques; Insulin; Male; Middle Aged; Thromboxane A2; Thromboxane B2

To determine whether platelet prostaglandin production in patients with liver cirrhosis was as impaired as platelet aggregation, serum thromboxane production was studied in 52 patients with liver cirrhosis; 12 patients had consumed more than 80 gr of alcohol/day, for more than ten years; 13 patients had also had diabetes mellitus for more than two years. A reduced thromboxane synthesis by platelets of liver disease patients was observed; the parallel decrease of both platelet thromboxane and serum PGE2 formation may also suggest a decrease in arachidonic acid availability for prostaglandin and thromboxane production. A smaller reduction of thromboxane and PGE2 formation in cirrhotics with diabetes mellitus or chronic alcohol intake was also observed.

Topics: Adult; Aged; Blood Platelets; Diabetes Complications; Diabetes Mellitus; Dinoprostone; Female; Humans; Liver Cirrhosis; Liver Cirrhosis, Alcoholic; Male; Middle Aged; Platelet Aggregation; Prostaglandins E; Thromboxane B2; Thromboxanes

Renal functional abnormalities, occurring before overt renal disease and possibly due to abnormal vascular control mechanisms, have been described in diabetes mellitus. We used intravenous (i.v.) furosemide, which stimulates renal prostaglandin (PG) synthesis and renin release, to compare these vasoactive systems in 14 diabetic and 23 normal control subjects. Using urine thromboxane B2 (TXB2) as an index of renal synthesis of the vasoconstrictor prostanoid TXA2, and urine 6keto-PGF1 alpha for the vasodilator PGI2, we found evidence of increased renal TXA2 synthesis in diabetic subjects in response to furosemide. The increased TXA2 synthesis did not occur at the expense of PGI2 synthesis, as urine 6keto-PGF1 alpha was not reduced. Increased TXB2 excretion in diabetic subjects was particularly marked in the first 10 min after i.v. furosemide. During this time, diabetic males excreted 31 +/- 6 ng of TXB2 compared with 10 +/- 1 ng for normal males (P less than 0.05), while diabetic females excreted 15 +/- 3 ng compared with 7 +/- 1 ng for normal females (P less than 0.05). Also, 6keto-PGF1 alpha excretion at 10 min was increased in diabetic subjects: males, 29 +/- 3 ng versus 19 +/- 3 (P less than 0.05); females, 33 +/- 8 versus 16 +/- 3 (P less than 0.05). The ratio of TXB2 to 6keto-PGF1 alpha tended to be higher in diabetic males.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Diabetes Mellitus; Epoprostenol; Female; Furosemide; Humans; Kidney; Male; Middle Aged; Prostaglandins; Renin; Thromboxane A2; Thromboxane B2

Investigations on the platelet function in diabetes mellitus were performed on 28 patients with insulin-dependent diabetes and in 33 healthy controls of similar age. In the diabetic patients it was possible to induce 50% of maximal aggregation by lower concentrations of adenosine diphosphate or arachidonic acid than in the controls. In the presence of N-ethyl maleimide, platelets from diabetic patients produced significantly more malondialdehyde than those from normal controls. After addition of arachidonic acid the platelets from the diabetic patients also synthesized more thromboxane B2. This synthesis of thromboxane was inversely correlated to the minimal concentration of arachidonic acid necessary to induce 50% platelet aggregation. Circulating platelet aggregates were more common in the diabetic patients than in the controls. Plasma levels of beta-thromboglobulin and platelet factor 4 were raised in parallel in the diabetic patients and correlated with the increased production of thromboxane B2 by the platelets from the same patients. Platelets from patients with diabetes thus demonstrated signs of hyperreactivity both in vivo and in vitro. This may be of clinical importance for the development of vascular complications in this disease.

Topics: Arachidonic Acid; Arachidonic Acids; beta-Thromboglobulin; Blood Platelets; Diabetes Mellitus; Factor VIII; Humans; Platelet Aggregation; Platelet Factor 4; Thromboxane B2

Platelet aggregation is known to be increased in diabetes mellitus, and the enhanced thromboxane production has been shown to be one of the causes of such abnormal platelet function. To investigate which step is activated in diabetic prostaglandin metabolism, three specific inhibitors of prostaglandin synthetases were used in this study, which were mepacrine, indomethacin and imidazole. Platelet aggregation induced by collagen was significantly increased accompanying enhanced thromboxane production in diabetics with proliferative retinopathy compared with age matched controls. Platelet aggregation in diabetics with proliferative retinopathy was less inhibited by the addition of each inhibitor compared with controls. However, there was no difference in inhibitory pattern of platelet aggregation among the three inhibitors. In addition, thromboxane production during aggregation in diabetics with proliferative retinopathy was significantly greater than that in controls by the addition of each inhibitor. Inhibitory patterns of thromboxane production did not differ among the addition of three inhibitors. It is concluded that enhanced thromboxane production resulting in enhanced platelet aggregation would be related to diabetic vascular complications. This abnormal prostaglandin production can be due to the activation of general steps in prostaglandin metabolism in diabetic platelets, not of a specific enzyme.

Topics: Adult; Diabetes Mellitus; Diabetic Retinopathy; Female; Humans; Imidazoles; Indomethacin; Male; Middle Aged; Platelet Aggregation; Quinacrine; Thromboxane B2; Thromboxanes

Quantitation of 2,3-dinor-thromboxane B2 (2,3-dinor-TxB2) was performed by gas chromatography-mass spectrometry. Under normal conditions the urinary excretion of 2,3-dinor-TxB2 was relatively constant in the same individual from day to day but during a 24-hour period a somewhat higher excretion rate was found during the first few hours after awakening. A pronounced reduction of the urinary excretion of 2,3-dinor-TxB2 was found after oral administration of 500 mg of aspirin or 50 mg of indomethacin, while 500 mg of paracetamol did not affect the urinary excretion. Increased excretion of 2,3-dinor-TxB2 was found in normal pregnancies and in diseases such as diabetes mellitus and homocysteinuria in comparison to the urinary excretion in normal healthy subjects. We also report one case, where the urinary excretion of 2,3-dinor-TxB2 was increased for a short period following the first symptoms of a myocardial infarction and those data indicate that thromboxane A2 (TxA2) may be of pathophysiological importance in human myocardial infarction. The results strongly indicate that measurements of the urinary excretion of 2,3-dinor-TxB2 should be meaningful as a tool for investigation of the involvement of thromboxane in various pathophysiological processes in vivo in man.

Topics: Acetaminophen; Adult; Amino Acid Metabolism, Inborn Errors; Aspirin; Circadian Rhythm; Diabetes Mellitus; Female; Humans; Indomethacin; Male; Myocardial Infarction; Physical Exertion; Pregnancy; Reference Values; Thromboxane B2; Thromboxanes

As an initial step to investigate the possibility that abnormal polymorphonuclear leukocyte (PMNL) function in diabetes might be related to abnormalities of arachidonic acid metabolism, product of the cyclooxygenase pathway were assayed in PMNL from 27 insulin-treated diabetic subjects and 27 age- and sex-matched nondiabetic subjects. It was found that the major prostanoid products formed were thromboxane B2 (TxB2) and prostaglandin E (PGE). Production of both these substances was greatly enhanced in PMNL from control and diabetic subjects by exposure to a killed preparation of Staphylococcus aureus (S. aureus) or to zymosan. There was a marked reduction in the production of TXB2 by PMNL from diabetic subjects in response to stimulation by both S. aureus [670 +/- 98 (SE) versus 1010 +/- 76 pg/10(6) PMNL/90 min, P less than 0.01] and zymosan (583 +/- 53 versus 1034 +/- 46 pg/10(6) PMNL/90 min, P less than 0.001). Similarly, production of PGE was significantly reduced in diabetics in response to both S. aureus (145 +/- 29 versus 232 +/- 16 pg/10(6) PMNL/90 min, P less than 0.05) and zymosan (181 +/- 21 versus 271 +/- 27 pg/10(6) PMNL/90 min, P less than 0.01). There was no relation between the plasma glucose at the time of the test and the production of either prostanoid. Diminished production of cyclooxygenase products of arachidonic acid metabolism should be added to the known abnormalities of PMNL in diabetes. In view of the demonstrated or inferred effects of cyclooxygenase products on aspects of PMNL function, this observation may be important in understanding the pathogenesis of PMNL dysfunction in diabetes.

Topics: Arachidonic Acids; Blood Glucose; Blood Platelets; Cell Separation; Diabetes Mellitus; Female; Humans; Insulin; Male; Middle Aged; Neutrophils; Prostaglandins E; Staphylococcus aureus; Thromboxane B2; Thromboxanes; Zymosan

TxB2 formation in PRP after thrombin stimulus, serum TxB2 and platelet sensitivity to prostacyclin and the correlation with ambient fasting plasma glucose and lipoproteins were determined in 20 insulin-independent diabetics (IID) with macroangiopathy, 10 insulin-dependent diabetics (IDD) with microangiopathy and 30 matched controls. Platelets obtained from insulin-independent diabetics synthetize significantly higher amounts of TxB2 than those of insulin-dependent diabetics and matched controls. IDD and IID patients required significantly higher concentrations of prostacyclin (p less than 0.001) for a similar degree of platelet aggregation inhibition. The amount of prostacyclin required for 50% platelet aggregation inhibition was correlated with fasting plasma glucose (r = 0.64, p less than 0.001) and HbA1% (r = 0.48, p less than 0.01) in all diabetic subjects. We conclude that: 1) only PRP, obtained from some insulin-independent diabetics with a concomitant macroangiopathy, shows an increased synthesis of TxB2; 2) platelet sensitivity to prostacyclin is highly dependent on the fasting ambient plasma glucose.

Topics: Adult; Blood Platelets; Diabetes Mellitus; Epoprostenol; Female; Glucose Tolerance Test; Humans; Insulin; Lipoproteins; Male; Middle Aged; Prostaglandins; Thromboxane B2; Thromboxanes

In our ongoing studies of the interrelationship between platelets and the vascular wall we found that an accurate estimate could be made of the clinical condition and more effective therapy prescribed when we monitored alterations in the plasma levels of TXB2. For this purpose we devised a radioimmunoassay with I125-TXB2-Tyramide. Patients with ischemic heart disorders, cerebral apoplexy, diabetes mellitus, Buerger's disease, Takayasu disease etc., all had statistically high levels of TXB2 as compared with healthy controls. In particular, patients with myocardial infarction, cerebral thrombosis and/or hemorrhage all revealed increases in levels of TXB2 and these levels increased in parallel with a worsening of the clinical condition, and there was always a re-increase in TXB2 level before a recurrence of an attack. As plasma TXB2 levels clearly reflect thrombogenic disorders, the assessment of these levels on a routine basis, enables a more accurate diagnosis, an indication of possible recurrences, and more effective chemotherapy and rehabilitation.

Topics: Adolescent; Adult; Arteriosclerosis; Arteriosclerosis Obliterans; Child; Chromatography, Gel; Circadian Rhythm; Coronary Disease; Diabetes Mellitus; Dinoprost; Female; Humans; Intracranial Embolism and Thrombosis; Male; Middle Aged; Prostaglandins F; Takayasu Arteritis; Thromboangiitis Obliterans; Thromboxane B2; Thromboxanes

Concentrations of the stable antiaggregatory prostacyclin metabolite 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and of the proaggregatory thromboxane A2 metabolite thromboxane B2 were measured by radioimmunoassay in plasma from 53 diabetics. In 33 of these patients the ability of platelets to produce thromboxane B2 during spontaneous clotting was also studied. Plasma 6-keto-PGF1 alpha concentrations were higher (p less than 0.05) in the diabetics (mean 107.7 +/- SE 7.6 ng/l) than in non-diabetic controls matched for age and sex (87.5 +/- 4.7 ng/l), and diabetics with microangiography (n = 28) and higher (p less than 0.01) concentrations (124.3 +/- 10.8 ng/l) than those without microangiography (n = 25; 89.2 +/- 9.3 ng/l). Plasma thromboxane B2 concentrations were also higher (p less than 0.01) in the diabetics (mean 218.5 +/- SE 25.3 ng/l) than in the controls (127.7 +/- 9.8 ng/l), but this increase was not related to microangiography. The ability of platelets to generate thromboxane B2 did not differ between the diabetics (181.4 +/- 16.4 microgram/l) and controls (195.8 +/- 11.8 microgram/l). Platelets of diabetics with microangiopathy or taking oral hypoglycaemic agents (n = 19), however, produced decreased amounts of thromboxane B2 during clotting. Plasma concentrations of 6-keto-PGF1 alpha and thromboxane B2 were not related to concentrations of glucose, haemoglobin A1, high-density lipoprotein cholesterol, cholesterol, triglycerides, magnesium, or creatinine. These results suggest that in diabetics with microangiopathy a balance between prostacyclin and thromboxane A2 is shifted to dominance by prostacyclin.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Aged; Blood Coagulation; Blood Platelets; Diabetes Mellitus; Diabetic Angiopathies; Female; Humans; Hypoglycemic Agents; Male; Middle Aged; Thromboxane B2; Thromboxanes

Platelets obtained from some diabetic patients show enhanced in vitro platelet aggregation. This study sought to determine if platelet obtained from insulin-dependent diabetic subjects synthesize increased quantities of the labile aggregating substance, thromboxane A2 (TXA2), and if it may play a role in the enhanced platelet aggregation. Arachidonic acid (1 mM)-stimulated TXA2 synthesis, as determined via radioimmunoassay of its stable metabolite TXB2, was significantly greater (P less than 0.01, N = 12) in platelet-rich plasma obtained from diabetics compared with matched controls. Arachidonic acid-stimulated TXB2 synthesis in the diabetic platelet-rich plasma was positively correlated with the ambient fasting plasma glucose (r = 0.61, P less than 0.02, N = 15). Platelet aggregation induced by arachidonic acid (0.4-0.8 mM) was inhibited significantly less by 13-azaprostanoic acid (P less than 0.04, N = 14), a competitive antagonist of the actions of prostaglandin H2 or TXA2 on platelets, compared with matched controls. The results support the notion that platelets obtained from some insulin-dependent diabetic subjects manifest increased synthesis of TXA2, which may contribute to the enhanced platelet aggregation.

Topics: Arachidonic Acid; Arachidonic Acids; Blood Glucose; Blood Platelets; Diabetes Mellitus; Epinephrine; Humans; Kinetics; Platelet Aggregation; Prostanoic Acids; Thromboxane B2

Circulating basal levels of prostanoids were measured in non-insulin dependent diabetics (NIDDs) who showed chlorpropamide alcohol flushing (CPAF), with and without diabetic complications, and in non-diabetic controls. Prostanoids were also measured during CPAF in those diabetics in whom CPAF is or is not blocked by indomethacin and also in CPAF-negative patients. There was no significant difference in circulating prostanoids between diabetics with and without severe vascular disease. The level of prostaglandin F, however, was significantly higher in the diabetic than in the non-diabetic subjects (mean +/- SEM PGFM 521 +/- 23 v. 414 +/- 18 pmol/l respectively P less than 0.01). In the group in whom CPAF could be blocked by indomethacin there was a significant rise in thromboxane during CPAF when compared with basal values (mean +/- SEM 905 +/- 48 v. 688 +/- 46 pmol/l respectively P less than 0.01) which was abolished by prior administration of indomethacin. There was no significant rise in prostacyclin or PGF. The group in which CPAF could not be blocked by indomethacin and the CPAF negative group showed no rise in any of the prostanoids measured. These findings support the concept of at least two different groups of CPAF positive NIDDs, one in which prostanoids are involved in CPAF and one in which they are not. It is the group in which prostanoids are involved in CPAF who seem to be highly protected against vascular disease.

Topics: 6-Ketoprostaglandin F1 alpha; Alcoholic Beverages; Chlorpropamide; Diabetes Mellitus; Face; Female; Humans; Hyperemia; Indomethacin; Male; Middle Aged; Prostaglandins; Prostaglandins F; Thromboxane B2

Platelets obtained from some diabetic patients show enhanced in vitro platelet aggregation. This study sought to determine whether platelets obtained from diabetic subjects synthesize increased quantities of the labile aggregating substance. TXA2, and whether it may play a role in the enhanced platelet aggregation. Arachidonic acid (1 mM)-stimulated TXA2 synthesis, as determined via radioimmunoassay of its stable metabolite TXB2, was significantly greater (p < 0.01, n = 12) in platelet-rich plasma obtained from diabetic patients than in matched controls. Arachidonic acid-stimulated TXB2 synthesis in the diabetic platelet-rich plasma was positively correlated with the ambient fasting plasma glucose (r = 0.61, p < 0.02, n = 15). Platelet aggregation induced by arachidonic acid (0.4 to 0.8 mM) was inhibited significantly less than in matched controls by imidazole, a thromboxane synthetase inhibitor (p < 0.01, n = 11), and 13-azaprostanoic acid, an antagonist of the actions of PGH2 or TXA2 on platelets (p < 0.04, n = 14). We conclude that platelets obtained from some diabetic subjects manifest increased synthesis of TXA2, which may contribute to the enhanced platelet aggregation.

Topics: Adult; Blood Platelets; Diabetes Mellitus; Female; Humans; Imidazoles; Male; Platelet Aggregation; Prostanoic Acids; Thromboxane A2; Thromboxane B2; Thromboxanes

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aorta; Arachidonic Acids; Blood Platelets; Diabetes Mellitus; Prostaglandins; Prostaglandins E; Prostaglandins F; Rats; Thromboxane B2

Topics: Adult; Aged; Arachidonic Acids; Blood Platelets; Collagen; Diabetes Mellitus; Fatty Acids, Nonesterified; Female; Half-Life; Humans; Male; Middle Aged; Platelet Aggregation; Prostaglandins; Thromboxane A2; Thromboxane B2; Thromboxanes

Topics: Adolescent; Adult; Diabetes Mellitus; Diabetes Mellitus, Type 1; Epoprostenol; Humans; Keto Acids; Male; Prostaglandins F; Thromboxane B2; Thromboxanes