thromboxane-b2 and Vascular-Diseases

The body's ability to produce prostacyclin and thromboxane by blood vessels and platelets may be important in hemostatic and thrombotic disorders and in blood pressure regulation. There are limitations to the information that can be derived from measurement of the active substances or metabolites in plasma and urine. Assays for thromboxane and prostacyclin in bleeding time blood reflect production in response to a single standardized vascular injury, and show considerable promise in furthering our understanding of the production of these chemicals in vivo. These assays may improve the assessment of risk of developing thrombotic disorders and improve the ability to monitor treatment. Studies to date have focused largely on the influences of various doses of aspirin on the production of prostacyclin and thromboxane in bleeding time blood, but also suggest that smokers are high thromboxane producers. In addition, individuals who exhibit type A behavior, a behavior pattern characterized by a relatively high level of ambitiousness, hostility, and competitive drive and a chronic sense of urgency appear to be low prostacyclin producers. Diets enriched in sunflower oil were found to diminish thromboxane production, while diets high in canola oil enhanced prostacyclin formation.

Topics: 6-Ketoprostaglandin F1 alpha; Bleeding Time; Humans; Platelet Function Tests; Thromboxane B2; Vascular Diseases

Topics: beta-Thromboglobulin; Blood Platelets; Humans; Platelet Factor 4; Thromboxane B2; Vascular Diseases

To determine whether urinary 11-dehydrothromboxane B2 (d-TXB2) is a marker of aspirin resistance and define the relationship between aspirin dosage and concentrations of this thromboxane metabolite.. Randomized, crossover study.. Two outpatient clinical centers.. Forty-eight patients (mean age 70 yrs) with vascular disease (52% clinical coronary artery disease, 29% cerebrovascular disease, 46% atrial fibrillation).. Levels of serum thromboxane B2 and d-TXB2 were measured after patients were treated initially with aspirin 325 mg/day for 4 weeks, then again after random assignment to receive aspirin 81, 325, or 1300 mg/day for 4 weeks, and then again after resumption of 325 mg/day for 4 weeks.. During treatment with aspirin 325 mg/day, the mean +/- SD serum thromboxane B2 level was 0.9 +/- 1.2 ng/ml and median (interquartile range) was 0.4 (0.2-0.9) ng/ml. Mean urinary d-TXB2 was 16 +/- 7.9 ng/mmol creatinine, with a median of 15 (9.9-23) ng/mmol creatinine with aspirin 325 mg/day. After 4 weeks of aspirin 81 mg/day, levels of serum thromboxane B2 (p<0.01) and urinary d-TXB2 (p=0.04) were both significantly higher compared with aspirin 325 mg/day; for urinary d-TXB2, the median increase was 3.0 ng/mmol creatinine. After 4 weeks of treatment with aspirin 1300 mg/day, levels of serum thromboxane B2 (p<0.01) and urinary d-TXB2 (p<0.01) were both significantly lower compared with aspirin 325 mg/day; the median decrease in urinary d-TXB2 was 4.4 ng/mmol creatinine.. Different aspirin dosages significantly affect serum and urinary markers of thromboxane synthesis.

Topics: Aged; Aspirin; Cross-Over Studies; Dose-Response Relationship, Drug; Female; Humans; Male; Platelet Aggregation Inhibitors; Thromboxane B2; Thromboxanes; Vascular Diseases

Previous studies relating increased thromboxane (TX) biosynthesis to cardiovascular risk factors do not answer the question whether platelet activation is merely a consequence of more prevalent atherosclerotic lesions or reflects the influence of metabolic and hemodynamic disturbances on platelet biochemistry and function.. We examined 64 patients with large-vessel peripheral arterial disease and 64 age- and sex-matched control subjects. TXA2 biosynthesis was investigated in relation to cardiovascular risk factors by repeated measurements of the urinary excretion of its major enzymatic metabolite, 11-dehydro-TXB2, by radioimmunoassay. Urinary 11-dehydro-TXB2 was significantly (P = .0001) higher in patients with peripheral arterial disease (57 +/- 26 ng/h) than in control subjects (26 +/- 7 ng/h). Seventy percent of patients had metabolite excretion > 2 SD above the normal mean. However, 11-dehydro-TXB2 excretion was enhanced only in association with cardiovascular risk factors. Multivariate analysis showed that diabetes, hypercholesterolemia, and hypertension were independently related to 11-dehydro-TXB2 excretion. During a median follow-up of 48 months, 8 patients experienced major vascular events. These patients had significantly (P = .001) higher 11-dehydro-TXB2 excretion at baseline than patients who remained event free.. The occurrence of large-vessel peripheral arterial disease per se is not a trigger of platelet activation in vivo. Rather, the rate of TXA2 biosynthesis appears to reflect the influence of coexisting disorders such as diabetes mellitus, hypercholesterolemia, and hypertension on platelet biochemistry and function. Enhanced TXA2 biosynthesis may represent a common link between such diverse risk factors and the thrombotic complications of peripheral arterial disease.

Topics: Adult; Aged; Aspirin; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Female; Follow-Up Studies; Humans; Hypercholesterolemia; Hypertension; Male; Middle Aged; Multivariate Analysis; Platelet Activation; Prospective Studies; Reproducibility of Results; Risk Factors; Smoking; Thromboxane A2; Thromboxane B2; Vascular Diseases

This double-blind study was designed to examine and compare the effects of supplementing the existing diet with fish oil or olive oil on lipids and cell function in patients with peripheral vascular disease. Thirty-two patients with symptomatic and angiographically demonstrated peripheral vascular disease were screened, matched, and randomly allocated to take either 15 g/d fish oil or olive oil for 4 weeks. Fish oil reduced serum triglyceride levels by 26%, but increased total cholesterol levels due to a significant increase in both low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein-2 cholesterol (HDL2-C). There was a nonsignificant decrease in HDL3-C levels. Olive oil reduced total cholesterol levels, accountable to a significantly decrease in LDL-C levels. Serum thromboxane B2 (TXB2) levels remained unchanged following fish oil, but were significantly increased by olive oil. Urinary excretion of TXB2 and 6-keto-PGF1 alpha was unaffected by either oil supplement. Platelet aggregation, which was measured in platelet-rich plasma in response to two doses of collagen or platelet-activating factor (PAF), was significantly reduced after fish oil, but was increased by olive oil. Following fish oil, there was a significant increase in eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) levels and a decrease in arachidonic acid content of platelet phospholipids. The platelet fatty acid composition after olive oil was unchanged. Fish oil decreased neutrophil leukotriene B4 (LTB4) generation following calcium ionophore stimulation by 33%, while leukotriene B5 levels increased significantly. Neutrophil PAF production and plasma lyso-PAF were unaffected by either oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Administration, Oral; Aged; Blood Platelets; Cholesterol, HDL; Cholesterol, LDL; Dietary Fats, Unsaturated; Docosahexaenoic Acids; Double-Blind Method; Eicosapentaenoic Acid; Fish Oils; Food, Fortified; Humans; Leukotriene B4; Lipids; Male; Middle Aged; Neutrophils; Olive Oil; Plant Oils; Thromboxane B2; Triglycerides; Vascular Diseases

In a double-blind placebo controlled study, 25 male patients (age range: 48-67 years) suffering from peripheral vascular disease were treated daily for 4 weeks with either 2 g of calcium dobesilate (n = 13) or placebo (n = 12). Different platelet and prostaglandin parameters were examined before and at the end of therapy. The number of circulating endothelial cells decreased significantly (4.9 +/- 2.9 to 2.0 +/- 1.9; p less than 0.0004). In addition, a decrease in serum TXB2 was noted (p less than 0.0001), but no significant change in plasma TXB2. The fibrinogen half-life was shortened (p less than 0.0001) and the platelet half-life was prolonged (p less than 0.04). The level of beta TG was decreased (p less than 0.006), but PF4 was unchanged. No alteration in the conversion of exogenous 14C-arachidonic acid by platelets to eicosanoids was observed. These observations indicate that calcium dobesilate is able to exert a favourable effect on some parameters of platelet function and prostaglandin synthesis which are important in the regulation of the hemostatic process. It is suggested that these pharmacological actions might explain, at least in part, the beneficial clinical effect of the drug.

Topics: Aged; Benzenesulfonates; beta-Thromboglobulin; Blood Platelets; Calcium Dobesilate; Double-Blind Method; Endothelium; Fibrinogen; Half-Life; Humans; Male; Middle Aged; Platelet Factor 4; Prostaglandins; Thromboxane B2; Vascular Diseases

Current evidence supports the positive association between the consumption of plant foods and health. In this work, we assessed the effect of consuming a half-serving (30 g) or one serving (60 g) of broccoli sprouts on the urinary concentrations of biomarkers of oxidative stress (isoprostanes) and inflammation (prostaglandins and thromboxanes). Twenty-four volunteers participated in the project. A quantitative determination of sulforaphane and its mercapturic derivatives, eicosanoids, and total vitamin C in urine was performed. The intake of broccoli sprouts produced an increase in the urinary concentrations of sulforaphane metabolites and vitamin C. Among the 13 eicosanoids analyzed, tetranor-PGEM and 11β-PGF2α as well as 11-dehydro-TXB2 showed a significant decrease in their urinary concentrations after the ingestion of broccoli sprouts. Therefore, the consumption of broccoli sprouts modulated the excretion of biomarkers linked to inflammation and vascular reactions without exerting a significant influence on the oxidation of phospholipids in vivo.

Topics: Adult; Ascorbic Acid; Biomarkers; Brassica; Chromatography, High Pressure Liquid; Cross-Over Studies; Female; Glucosinolates; Healthy Volunteers; Humans; Imidoesters; Inflammation; Isoprostanes; Isothiocyanates; Male; Middle Aged; Oxidative Stress; Oximes; Plant Extracts; Prostaglandins; Sulfoxides; Tandem Mass Spectrometry; Thromboxane B2; Vascular Diseases; White People; Young Adult

To observe the effect of Zhuang-medical thread moxibustion combined with needle-pricking on vascular oxidative stress injury in oxidative stress injury rats.. Eighty Wistar rats were randomly allocated to normal control, sham operation (sham), model, and combined treatment groups (n=20 in each group). The oxidative stress injury model was established by ligation of the left sciatic nerve to induce chronic constriction injury (CCI) pain stress stimulation. Zhuang-medical thread moxibustion was applied to bilateral "Zusanli" (ST 36), once a day for 3 weeks. Needle-pricking was applied to left "Yanglingquan" (GB 34) and left "Huantiao" (GB 30), once a day for 3 weeks except Sundays. Plasma 6-keto-PGF 1α, thromboxane B 2 (TXB 2), NO and ET contents were assayed by radioimmunoassay. COX-2 immunoactivity of the femoral artery was determined by immunohistochemistry, and pathological changes of the femoral artery were detected by H. E. staining.. Compared with the control group, the levels of plasma 6-keto-PGF 1α and NO in the model group were significantly reduced (P<0.05), while those of plasma TXB 2 and ET and COX-2 expression in the femoral artery were obviously increased in the model group (P<0.01). After moxibustion plus needle-pricking treatment, CCI-induced decrease of plasma 6-keto-PGF 1α and NO contents, and increase of plasma TXB 2 and ET and COX-2 expression levels were obviously reversed (P<0.05, P<0.01). The tubal wall of the femoral artery in rats of the model group got thicker, while that of the combined treatment group was relatively thinner, suggesting an inhibition of vascular intimal hyperplasia after the treatment.. Zhuang-medical thread moxibustion combined with needle-pricking of ST 36, GB 34 and GB 30 can reduce the expression of femoral artery COX-2 and regulate the balance of both plasma PGI 2/TXA 2 and plasma NO/ET in CCI-induced oxidative stress rats, which may contribute to its effect in suppressing oxidative stress-induced vascular intimal hyperplasia.

Topics: Acupuncture Points; Acupuncture Therapy; Animals; Blood Vessels; Combined Modality Therapy; Cyclooxygenase 2; Female; Humans; Male; Moxibustion; Oxidative Stress; Rats; Rats, Wistar; Thromboxane B2; Vascular Diseases

Raynaud's phenomenon has been suggested as a predisposing factor for pulmonary vasospasm which may lead to pulmonary hypertension, but the occurrence of cold stimulus-induced pulmonary vasospasm has been inconsistent. Such inconsistent pulmonary vascular responses may be caused by differences in the production of endogenous vasodilators and vasoconstrictors among patients. Fourteen patients with Raynaud's phenomenon associated with mixed connective tissue disease (n=10) or systemic sclerosis (n=4) participated in the study. Right heart catheterization was performed before and after a cold pressor test, immersing a hand in cold water (15 degrees C) for 5 min. Plasma levels of 6-keto prostaglandin (PG)F1alpha, thromboxane (TX)B2 and endothelin (ET)-1 in the mixed venous blood were measured. Mean pulmonary artery pressure increased after the cold pressor test in five of 14 patients, and the patients were divided into those with pulmonary vasospasm (responders) and those without vasospasm (nonresponders). After the cold pressor test, levels of 6-keto PGF1alpha increased significantly in nonresponders (p<0.01) and decreased significantly in responders (p<0.05). The ratios of 6-keto PGF1alpha to TXB2 significantly increased in nonresponders (p<0.01) but not in responders and the difference between responders and nonresponders after the cold pressor test was also statistically significant (p<0.05). No significant change in plasma ET-1 levels occurred in either responders or nonresponders. The results suggest that an impaired production of prostaglandin I2 and an imbalance between prostaglandin I2 and thromboxane A2 are associated with the occurrence of pulmonary vasospasm induced by Raynaud's phenomenon.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Cold Temperature; Endothelin-1; Female; Hemodynamics; Humans; Male; Middle Aged; Pulmonary Artery; Pulmonary Veins; Raynaud Disease; Respiratory Function Tests; Spasm; Thromboxane B2; Vascular Diseases

Plasma levels of 6-keto-prostaglandin F1 alpha (6kPGF1 alpha) and thromboxane (Tx) B2 have been assessed in sickle cell disease (SCD) with discrepant results. Inasmuch as direct measurement of plasma prostanoids is fraught with the problem of interfering substances, we assessed plasma 6kPGF1 alpha and TxB2 levels in patients with SCD by RIA after extraction of eicosanoids and separation by HPLC. We demonstrate that the 6kPGF1 alpha and TxB2 levels in children with SCD in steady state as well as in vaso-occlusive crisis (VOC) are significantly lower when compared with those from age-matched controls. The VOC plasma 6kPGF1 alpha and TxB2 levels were, however, significantly elevated when compared with those from children in steady state. Changes similar to those noted with unpaired plasma samples were also observed when paired steady state and VOC plasmas from the same patients were assessed. The ratio of TxB2 to 6kPGF1 alpha was, however, significantly elevated in patients with SCD in crisis when compared with eicosanoid ratios obtained during steady state. In an attempt to understand whether the abnormality in 6kPGF1 alpha was due to an impairment in endothelial cell prostacyclin-regenerating ability, we compared the ability of plasma from controls and children with SCD to activate arachidonic acid (AA) release and prostacyclin production by [14C]AA-prelabeled bovine aortic endothelial cells. Our results suggest that the decreased 6kPGF1 alpha levels in plasma from children with SCD was not due to an effect on substrate AA release but rather a modulatory effect of sickle plasma components on endothelial cell cyclooxygenase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Anemia, Sickle Cell; Animals; Arachidonic Acid; Case-Control Studies; Cattle; Cells, Cultured; Child; Child, Preschool; Chromatography, High Pressure Liquid; Constriction, Pathologic; Endothelium, Vascular; Epoprostenol; Humans; Thromboxane B2; Vascular Diseases; Vasoconstrictor Agents; Vasodilator Agents

Thromboxane A2 is a potent vasoconstrictor and a stimulus of platelet aggregation, which may contribute to hypercoagulability. The prostacyclin, prostaglandin I2, has exactly the opposite effect. Measurement of the major urinary metabolites, 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha (prostaglandin F1 alpha) by radioimmunoassay can accurately reflect in vivo the biosynthesis of thromboxane A2 and prostaglandin I2, respectively. Group 1 consisted of 60 patients less than 50 years old. The mean urinary 11-dehydro-thromboxane B2 level of 3 patients with arteriogenic impotence was significantly greater than that of the 57 control volunteers: 2.66 +/- 0.65 versus 1.74 +/- 0.56 (plus or minus standard deviation) ng./mg. creatinine (p = 0.008). The prostaglandin F1 alpha levels for the patients and controls were 32.74 +/- 8.45 and 37.58 +/- 16.55 ng./mg. creatinine, respectively, which was not significantly different (p greater than 0.05). Group 2 consisted of 96 patients 50 years old or older. The 11-dehydro-thromboxane B2 concentration in the urine was 1.83 +/- 0.58, 2.54 +/- 1.12 and 1.91 +/- 0.73 ng./mg. creatinine in the 47 normal control volunteers, 20 patients with arteriogenic impotence and 29 with arteriogenic impotence plus intracavernous injection of 20 micrograms prostaglandin E1, respectively. The arteriogenic impotence group showed the significantly highest level among the 3 groups (p = 0.0025). Also, the urinary prostaglandin F1 alpha levels in these patients were 45.71 +/- 36.3, 57.71 +/- 35.53 and 59.30 +/- 45.08 ng./mg. creatinine, respectively, which was not significantly different (p greater than 0.05). For the 13 patients with arteriogenic impotence (group 3) we compared the urinary 11-dehydro-thromboxane B2 and prostaglandin F1 alpha levels before and after intracavernous injection of prostaglandin E1 by using a paired t test. The results showed that the change in 11-dehydro-thromboxane B2 levels was 2.78 +/- 1.09 versus 1.99 +/- 0.75 ng./mg. creatinine, which was significantly different (p = 0.005), whereas that for prostaglandin F1 alpha was 62.30 +/- 40.41 versus 58.86 +/- 44.26 ng./mg. creatinine, with no significant difference (p greater than 0.05). Our findings suggest that urinary 11-dehydro-thromboxane B2 may have an important role in the diagnosis and treatment of arteriogenic impotence.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Aged; Blood Flow Velocity; Erectile Dysfunction; Humans; Male; Middle Aged; Penile Erection; Penis; Thromboxane B2; Vascular Diseases

Urinary immunoreactive thromboxane (irTXB2) has been found helpful in acute settings with altered renal, but also extrarenal thromboxane formation. As only trace amounts of systemically formed thromboxane are excreted unmetabolized, the nature of urinary irTXB2 was explored. The two most abundant metabolites of systemic thromboxane, 2,3-dinor-TXB2 and 11-dehydro-TXB2, crossreacted about 70% and less than 1%, respectively, with a widely used thromboxane antiserum. After solid-phase extraction of urine samples and separation on reversed-phase HPLC, the bulk of immunoreactivity always eluted as one peak shown to correspond to 2,3-dinor-TXB2. Much less was found in fractions where TXB2 eluted. Therefore, urines were read against calibration curves constructed with 2,3-dinor-TXB2. This direct estimation gave good recoveries for standard 2,3-dinor-TXB2 and correlated well, both in healthy controls and in patients at increased risk or with overt vascular disease, to values obtained after solid phase extraction, purification on reversed-phase HPLC and quantitation by either gas-chromatography mass-spectrometry or radioimmunoassay. Patients with multiple cardiovascular risk factors but free from detectable vascular disease excreted significantly more irTXB2 than age-matched controls with non-vascular conditions or normals. Therefore, urinary irTXB2 measured with this antiserum represents 2,3-dinor-TXB2, reflecting the systemic formation of TXB2. This simple approach is feasible for screening thromboxane formation in large series of patients. Its acumen in detecting the early development of vascular disease and its relation to established risk factors deserves large-scale prospective testing.

Topics: Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Humans; Radioimmunoassay; Risk Factors; Thromboxane B2; Vascular Diseases

1. Aggregation of diluted whole blood (impedance method) and thromboxane B2 production during aggregation were measured in cigarette smokers and non-smokers, aged 41-68 years, with (n = 14) and without (n = 15) major symptomatic peripheral vascular disease. The plasma level of the lyso derivative of platelet activating factor (lyso-PAF) was also measured using a bioassay with 14C-serotonin labelled rabbit platelets, after extraction and acetylation to active PAF. 2. Aggregation to ADP and collagen was significantly less in non-smokers without vascular disease (n = 8) than in the other three groups (P less than 0.01; ANOVA). Thromboxane B2 production was not significantly different between the groups. There was no significant difference in plasma lyso-PAF between groups. No change was found in any variable after smokers smoked two cigarettes. 3. In these older age subjects, both vascular disease and the smoking habit were associated with greater whole blood aggregation. However, current smoking and the smoking of two cigarettes did not affect aggregation in subjects with vascular disease and plasma lyso-PAF levels were not consistently related to either smoking or vascular disease.

Topics: Adenosine Diphosphate; Adult; Aged; Arteriosclerosis; Cell Aggregation; Collagen; Humans; Male; Middle Aged; Platelet Activating Factor; Smoking; Thromboxane B2; Vascular Diseases

The levels of 6-keto-PGF1 alpha and TXB2 were determined by the RIA method in Blackfoot disease which is an endemic disease of the peripheral vascular system found in the southwest coast of Taiwan. The level of TXB2 was normal, but that of 6-keto-PGF2 alpha concentration was 30% lower than the normal. The activity of 15-hydroxyprostaglandin dehydrogenase was higher in patients' blood plasma than in the normal. Patient's vascular endothelium was also found to have lower prostacyclin synthase activity. These results suggest that the reduced prostacyclin production in vascular endothelium contributes to the pathogenesis of Blackfoot disease.

Topics: 6-Ketoprostaglandin F1 alpha; Arteries; Cytochrome P-450 Enzyme System; Endothelium, Vascular; Epoprostenol; Humans; Hydroxyprostaglandin Dehydrogenases; Intramolecular Oxidoreductases; Isomerases; Prostaglandin Endoperoxides, Synthetic; Prostaglandin H2; Prostaglandins H; Thromboxane B2; Vascular Diseases

Topics: Aspirin; Humans; Thromboxane B2; Thromboxanes; Vascular Diseases

Topics: Animals; Calcium; Capillary Permeability; Cytotoxins; Eicosanoic Acids; In Vitro Techniques; Membrane Lipids; Phospholipids; Prostaglandins; Pseudomonas aeruginosa; Pulmonary Circulation; Rabbits; Staphylococcal Toxoid; Thromboxane B2; Vascular Diseases; Vasoconstriction

Cigarette smoking is associated with increased mortality from cardiovascular disease that declines after cessation. This study extends the evidence regarding the effects of chronic smoking on platelets and the vessel wall in vivo. Excretion of a major urinary thromboxane metabolite, 2,3-dinor-thromboxane B2, is significantly (p less than .01) elevated in apparently healthy chronic smokers (20 cigarettes daily) compared with that in nonsmoking control subjects. This difference in excretion of 2,3-dinor-thromboxane B2 was abolished by the administration of 20 mg aspirin twice daily, a dose shown to selectively inhibit platelet cyclooxygenase. After aspirin, the return of the excretion of 2,3-dinor-thromboxane B2 to pretreatment levels paralleled the recovery of platelet cyclooxygenase. These findings indicate that excessive thromboxane A2 generation in chronic smokers predominantly derives from platelets. The urinary excretion of the prostacyclin metabolite 2,3-dinor-6-keto-prostaglandin F1 alpha also is increased during chronic cigarette smoking, as is the case with other diseases associated with accelerated interaction of platelets with the vessel wall. We have found evidence of platelet and vascular dysfunction in vivo in chronic cigarette smokers before the manifestation of overt cardiovascular disease. The results would also be consistent with the hypothesis that in chronic smokers, the platelet defect is largely reflective of smoking-induced vascular injury.

Topics: Adult; Blood Platelet Disorders; Blood Platelets; Cotinine; Epoprostenol; Humans; Male; Middle Aged; Nicotine; Platelet Aggregation; Smoking; Thromboxane B2; Thromboxanes; Vascular Diseases

The influence of hypoxia on the spontaneous platelet aggregation (SPA) and thromboxane formation was studied. The analysis of aggregation curve was carried out according to Breddin. The hypoxia enhanced the aggregability from Q2norm = 2.46 +/- 0.40 (normoxia) to Q2hyp = 4.39 +/- 0.39 (hypoxia), n = 52, p less than 0.001. 10 samples of those showed no SPA under equilibration with air but the hypoxic stimulus provoked SPA (Q2norm = 0, Q2hyp = 1.19 +/- 60, n = 10, p less than 0.001). When the results were arranged according to the degree of the stimulation of SPA, two groups could be separated with low and high response to hypoxia. The hypoxia caused also an augmentation of the TXB2 level in comparison to normoxia. The stronger enhancement of the TXB2 formation during the incubation under hypoxic conditions was independent of the fact whether SPA took place or not. The present study suggests that hypoxic conditions alone may be a reason for a stimulated TXA2 formation of the platelets and that the enhanced TXA2 formation caused by hypoxia is possibly inducing or reinforcing the SPA.

Topics: Adult; Aged; Blood Platelets; Humans; Hydrogen-Ion Concentration; Hypoxia; Middle Aged; Oxygen; Platelet Aggregation; Thromboxane A2; Thromboxane B2; Vascular Diseases

One year aged rabbits were exposed to a single dose of 100, 500 or 1000 rd (1.0, 5.0 or 10 Gy) to the abdominal aorta. The non-irradiated thoracic aortic segment served as control. The animals were killed between one and 336 hours after the irradiation. Four animals were examined in each group. The prostacyclin formation was assessed by means of a radioimmunoassay against its stable breakdown 6-oxo-PGF1 alpha, the thromboxane A2-formation using a radioimmunoassay for thromboxane B2. Local irradiation causes a temporary increase of both the compounds. In contrast to thromboxane B2, the 6-oxo-PGF1 alpha exhibits a long-lasting depression. The higher the radiation dose, the more intensive the increase and the long-lasting depression of 6-oxo-PGF1 alpha. The liberation of eicosanoids and subsequent hemostatic dysregulation at different intervals after irradiation might contribute to an important extent to the radiation induced vasculopathy.

Topics: Animals; Aorta, Abdominal; Blood Vessels; Dose-Response Relationship, Radiation; Epoprostenol; Male; Prostaglandins F; Rabbits; Radiation Injuries, Experimental; Thromboxane A2; Thromboxane B2; Vascular Diseases

To evaluate the role of arachidonate metabolites in regulating pulmonary vascular tone, we performed multiple studies on a 17-month-old girl with idiopathic pulmonary hypertension, systemic arterial hypoxemia (due to ventilation-perfusion mismatching), and an elevated thromboxane A2 (TXA2) to prostacyclin (PGI2) ratio due to increased TXA2 (measured as their stable metabolites, TXB2 and 6-keto-PGF1 alpha, respectively). Intravenous infusions of PGI2 reduced mean pulmonary arterial pressure (from 80 to 47 mmHg), increased cardiac output (from 3.43 to 3.97 L/min), increased systemic arterial oxygen saturation (from 60 to 72 percent), and decreased the TXB2 to 6-keto-PGF1 alpha ratio (from 5.9 to 0.2); mean systemic arterial pressure was unchanged. Pharmacologically decreasing the TXB2 to 6-keto-PGF1 alpha ratio with administration of nifedipine or diltiazem also reduced pulmonary hypertension and increased systemic arterial oxygen saturation in this patient. Nifedipine and diltiazem decreased the ratio by decreasing TXB2. Prostacyclin decreased the ratio by increasing 6-keto-PGF1 alpha. These studies support the hypothesis that the balance between TXA2 and PGI2 is an important influence on pulmonary vascular tone.

Topics: 6-Ketoprostaglandin F1 alpha; Aging; Arachidonic Acid; Arachidonic Acids; Blood Pressure; Diltiazem; Epoprostenol; Female; Hemodynamics; Humans; Infant; Nifedipine; Pulmonary Artery; Pulmonary Circulation; Thromboxane B2; Vascular Diseases; Vasodilation

Pure acetylcholine esterase from Electrophorus Electricus has been covalently coupled to different prostaglandins or thromboxanes. The corresponding conjugates have been tested using microtiter plates with 96 wells coated with a second antibody. The minimal detectable concentrations were 10 pg/ml. We suggest that this procedure which has been extended to non icosanoid molecules may serve as a general technique for enzyme immunoassay.

Topics: 6-Ketoprostaglandin F1 alpha; Arachidonic Acid; Arachidonic Acids; Child, Preschool; Chromatography, Gas; Dinoprost; Dinoprostone; Humans; Hydroxyeicosatetraenoic Acids; Immunoenzyme Techniques; Infant, Newborn; Mass Spectrometry; Prostaglandins; Prostaglandins E; Prostaglandins F; Thromboxane B2; Thromboxanes; Vascular Diseases

We have previously demonstrated that platelets obtained from patients with anorexia nervosa or severe peripheral vascular disease are hyperaggregable. Since conventional heparins are known to activate platelets in vitro and occasionally induce thrombosis and consumptive thrombocytopenia in vivo, we have investigated the direct effect of a conventional heparin on platelets obtained from patients with anorexia nervosa or severe peripheral vascular disease. Heparin at therapeutic concentrations was found to induce platelet aggregation of such platelets in vitro. In contrast, a recently developed low molecular weight heparinoid (Org 10172), at therapeutic concentrations, had no effect on these hyperaggregable platelets. We conclude that: heparin may be potentially harmful to patients with hyperaggregable platelets; thrombocytopenia and thrombosis associated with heparin therapy may be mediated through a direct effect of heparin on platelets; it is unlikely that heparin induced thrombocytopenia is always mediated by classical immunological mechanisms, especially in patients with hyperaggregable platelets; and low molecular weight heparinoids may be safer anticoagulants in patients with platelet hyperaggregability.

Topics: Adolescent; Adult; Aged; Anorexia Nervosa; Blood Platelets; Chondroitin Sulfates; Collagen; Dermatan Sulfate; Epinephrine; Female; Glycosaminoglycans; Heparin; Heparitin Sulfate; Humans; Immunoglobulin G; In Vitro Techniques; Male; Middle Aged; Platelet Aggregation; Thrombocytopenia; Thromboembolism; Thromboxane B2; Vascular Diseases