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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thromboxane B2 (TXB2) levels in bleeding time blood and in serum were measured in 13 elderly patients with cardiovascular disease, seven of whom were receiving continuous treatment with low dose acetylsalicylic acid (ASA, 125 mg every second day--250 mg daily) for prevention of stroke. Blood sampling was performed openly, but assays of TXB2 were performed by a blinded investigator. In patients treated with ASA, median serum TXB2-levels were 4% and TXB2-levels in bleeding-time blood were less than 16% of the corresponding levels in patients without ASA (P less than 0.01). The results show that in elderly atherosclerotic patients very low doses of ASA substantially suppress TXB2 formation, not only in serum but also at the site of local haemostasis. The extent of suppression is comparable to that previously reported from young healthy subjects.
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PMID:Low dose acetylsalicylic acid and thromboxane release at the site of plug formation in vivo in elderly patients with cardiovascular disease. 231 26

The relation of brain eicosanoids to progression of cerebral edema was studied in stroke-resistant spontaneously hypertensive rats subjected to incomplete global brain ischemia induced by bilateral occlusion of the common carotid arteries. Thromboxane B2 and 6-keto prostaglandin F1 alpha levels were significantly elevated 5 minutes after reperfusion but returned to control levels by 30 minutes. In contrast, leukotriene C4 levels increased 2 hours after bilateral common carotid artery occlusion and peaked 30 minutes after reperfusion, with higher levels persisting until 60 minutes after reperfusion. Cerebral ischemia was accompanied by cerebral edema early after reperfusion. The edema correlated with increased leukotriene C4 levels. That the increased brain water content was causally related to an increase in leukotriene C4 was supported by results obtained following administration of the 5-lipoxygenase inhibitors ONO-LP-016 and AA-861. Both inhibitors suppressed the increased leukotriene C4 and brain water contents after reperfusion. Our results indicate that leukotriene C4 is closely associated with an induction of ischemic cerebral edema.
Stroke 1988 Mar
PMID:Brain eicosanoid levels in spontaneously hypertensive rats after ischemia with reperfusion: leukotriene C4 as a possible cause of cerebral edema. 335 24

The purpose of our study was to investigate the effects of different doses of acetylsalicylic acid on platelet aggregation. Among inpatients of the National Taiwan University Hospital, 236 cases of completed stroke and seven cases of reversible ischemic neurologic deficit that were diagnosed by computed tomography of the brain and that had not ingested acetylsalicylic acid or acetylsalicylic acidlike drugs for greater than 2 weeks before admission were selected for this study. Thromboxane B2 and 6-keto-PGF1 alpha were measured by radioimmunoassay, threshold concentration of adenosine diphosphate was measured by Born's method, and circulating platelet aggregates were measured by the method of Wu and Hoak. Various single doses of acetylsalicylic acid (75, 300, or 600 mg) or 300 mg acetylsalicylic acid every 6 hours for four doses or one dose of 300 mg acetylsalicylic acid with 75 mg dipyridamole significantly suppressed the mean plasma thromboxane B2 concentrations and elevated the mean adenosine diphosphate threshold concentrations. Abnormal plasma thromboxane B2 concentrations, adenosine diphosphate threshold concentrations, or circulating platelet aggregate ratios were significantly normalized after administration of these regimens. The effects were not significantly different among treatment groups. Forty milligrams of acetylsalicylic acid seemed to have less platelet-inhibitory effect. A single dose of 75 mg acetylsalicylic acid significantly inhibited platelet hyperfunction and effectively corrected the abnormal plasma thromboxane B2 concentrations, adenosine diphosphate threshold concentrations, and circulating platelet aggregate ratios. Higher doses did not enhance the inhibitory effect. In addition, this single dose of acetylsalicylic acid did not significantly suppress plasma 6-keto-PGF1 alpha. We conclude that 75 mg acetylsalicylic acid per day is adequate to inhibit platelet hyperfunction.
Stroke 1988 May
PMID:Inhibitory effect of acetylsalicylic acid on platelet function in patients with completed stroke or reversible ischemic neurologic deficit. 336 89

Twenty-four patients with subarachnoid hemorrhage due to rupture of a supratentorial aneurysm underwent surgery within 72 hours after subarachnoid hemorrhage. Immediately after clipping of the aneurysm the patients were treated with intravenous nimodipine for at least 7 days and then received the drug orally for another week. Nine patients had a documented or probable intake of aspirin or other nonsteroid anti-inflammatory drug during the days preceding admission. In all patients there was a gradual increase in serum thromboxane B2 concentration from low to normal levels during the treatment period, the increase being most pronounced in patients with prior nonsteroid anti-inflammatory drug intake. Thromboxane B2 concentrations were similar to those of four control patients not receiving nimodipine. In three patients who developed delayed ischemic dysfunction despite "therapeutic" nimodipine plasma concentrations, the thromboxane B2 levels were low or normal. Our present results do not support the idea that nimodipine exerts an effect on platelet function in patients with aneurysmal subarachnoid hemorrhage.
Stroke 1988 May
PMID:Thromboxane B2 levels in serum during continuous administration of nimodipine to patients with aneurysmal subarachnoid hemorrhage. 336 1

Three different levels of global forebrain ischemia were induced in rats and their plasma levels of Thromboxane B2 (TXB2) and 6 Keto PGF1 alpha were determined to investigate the relation between severity of ischemia and eicosanoid production. Ischemia stimulates the activity of cellular lipase whose actions cause deacylation of brain phospholipids and release of free fatty acids. Arachidonic acid (A.A.) is one of the predominant fatty acids which is liberated in brain after ischemia. A.A. is the primary substrate for the synthesis of prostaglandins (PGs), Thromboxane A2 (TXA2) and Prostacyclin (PGI2), which play an important role in regulation of platelet aggregation and vasotonus. Thromboxane is a potent platelet aggregator and vasoconstrictor. On the other hand, PGI2 has the opposite nature. Therefore it can be considered that PGs and moreover, the balance of TXA2 and PGI2 may have an intimate relation to the development of cerebral ischemia. Three different levels of ischemia were produced by bilateral carotid artery ligation (BLCL) using three kinds of rats with different blood pressure ranges, namely, SHRSP (Stroke-prone spontaneously hypertensive rats), SHRSR (Stroke-resistant spontaneously hypertensive rats) and WKY (Wistar kyoto rats). It is known that higher pressure groups suffer severe ischemia by BLCL procedure. Hypertensive rats (SHRSP, SHRSR) were originally produced from WKY. The experimental animals used were about 300 gr and 16 weeks old male rats. The plasma and brain TXB2 and 6 Keto-PGF1 alpha, stable metabolites of TXA2 and PGI2 were measured by radioimmunoassay. The chronological changes of brain and plasma PGs levels after ischemia using SHRSR were also investigated.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Effect of bilateral common carotid artery ligation on prostaglandin levels (TXA2, PGI2) in spontaneously hypertensive rats (SHRSP, SHRSR) and normotensive rats (WKY)]. 352 27

Thromboxane B2 (TXB2) is the stable metabolite of thromboxane A2 (TXA2), a potent vasoconstrictor which induces irreversible platelet aggregation. The inhibition of TXA2 by aspirin and other agents has been associated with improved outcome following cerebral ischemia in clinical and laboratory studies. To investigate the relation of TXA2 production to cerebral ischemia, we measured the urinary excretion of TXA2 metabolites in 30 patients with acute cerebral ischemia. Urinary immunoreactive TXB2 for this group of ischemic patients was elevated compared to normals, 1818 +/- 344 pg/mg Cr (mean +/- SE) vs 880 +/- 122 pg/mg Cr (p less than .05). Among various subsets of the ischemic patients, those with severe stroke (2108 +/- 536 pg/mg Cr), large vessel disease (1646 +/- 335 pg/mg Cr), and cardiogenic stroke (2712 +/- 1045 pg/mg Cr) were all significantly elevated. Of the stroke patients, only the males demonstrated this significant elevation. These elevations of urinary immunoreactive TXB2 are consistent with a role for increased platelet activation in the pathogenesis of some forms of cerebral ischemia and suggest that gender differences in arachidonate metabolism may exist for stroke patients.
Stroke
PMID:Increased excretion of immunoreactive thromboxane B2 in cerebral ischemia. 396 51

The effect of complement activation on the pulmonary vascular system and on right ventricular function was studied in sheep (n = 12) by injection of cobra venom factor. Animals were instrumented for measurement of pulmonary flow, mean pulmonary artery pressure, right ventricular stroke work, arterial blood gases, and systemic vascular resistance. Blood was sampled from the left atrium and pulmonary artery to measure thromboxane B2, the metabolite of thromboxane A2, by radioimmunoassay. After baseline measurements, animals were randomly assigned to receive a selective thromboxane receptor antagonist SQ30741 as a 10 mg/kg bolus with an infusion of 10 mg/kg per hour or else to receive vehicle. Cobra venom factor was then injected (30 U/kg) in all animals, and data were recorded at 15, 30, 60, 90, and 120 minutes. In control animals there was a 2.4-fold increase in mean pulmonary artery pressure and a 76% increase in right ventricular stroke work at 15 minutes from baseline (p < 0.05); these values remained elevated for 30 minutes and returned to baseline by 1 hour with no change in systemic vascular resistance. Arterial oxygenation decreased by 124% at 15 minutes and remained depressed through the experiment, but in treated animals oxygen tension remained unchanged from baseline. Thromboxane B2 increased 95% from baseline in the control group and 1.5 fold in treated animals and followed a similar time course as the functional measurements (p < 0.05). A pulmonary vascular thromboxane B2 gradient of approximately 1000 pg/ml was measured at 15 and 30 minutes in both control and treated groups. (p < 0.05) We conclude that after complement activation in this model pulmonary hypertension and decreased oxygen tension are mediated by thromboxane release from the pulmonary vascular bed. This increased afterload causes a stress on the right ventricle as demonstrated by the increased right ventricular stroke work. Selective thromboxane receptor antagonism may be a beneficial therapy for pulmonary hypertension in patients after cardiopulmonary bypass.
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PMID:Prevention of complement-induced pulmonary hypertension and improvement of right ventricular function by selective thromboxane receptor antagonism. 812 9

The aim of this study was to assess the association between "aspirin non responsiveness" in patients with coronary artery diseases (CAD) and the risk of major adverse cardiovascular events (MACE). 204 patients with CAD receiving aspirin (250 mg/d) were included. Both Collagen/Epinephrine Closure Time (CEPI-CT) and urinary Thromboxane B2 (uTxB2) concentration was used to determine the patients aspirin responsiveness. The clinical primary endpoint was the occurrence of MACE including: cardiovascular death, MI, stroke or transient ischemic attack. The secondary endpoint was the occurrence of Recurrent Acute Vascular Event (RAVE: MI, stroke or transient ischemic attack). After 1-year follow-up, no responders diagnosed by CEPI-CT had a trend for higher risk of MACE (13% vs 7.4%; P = 0.22) and significant higher risk of RAVE (OR = 2.1; 95%CI: 1.7-2.4; P = 0.01) when compared to good responders. Multivariate analysis showed that CEPI-CT < 143 s was the only independent predictor of RAVE (OR = 6.3; 95% CI: 1.2-32.2; P = 0.026). Aspirin non-responsiveness, diagnosed by the uTxB2, was not associated with an increased risk of either MACE or RAVE. Our results, reinforce the importance of being able to diagnose laboratory "aspirin non responsiveness", and extend the evidence that aspirin non responsiveness may explain in part the occurrence of RAVE.
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PMID:Response variability to aspirin and one-year prediction of vascular events in patients with stable coronary artery disease. 1938 50