Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0032463 (polycythemia vera)
 3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increased thromboxane (TX) production and modified aspirin sensitivity has been detected in vitro in platelets isolated from patients with polycythemia vera. To verify the relevance of these capacity-related measurements to the actual rate of TXA2 biosynthesis in vivo and its suppression by oral aspirin, we have investigated the urinary excretion of major enzymatic metabolites of TXB2 in 17 patients with polycythemia vera and 23 gender- and age-matched controls. Urinary 11-dehydro-TXB2 and 2,3-dinor-TXB2 were measured by previously validated radioimmunoassays. In addition, urinary immunoreactive leukotriene (LT) E4 was measured to explore the 5-lipoxygenase pathway of arachidonate metabolism. Polycythemic patients had significantly (P < .001) higher excretion rates of both 11-dehydro-TXB2 (1,033 +/- 1,050 v 117 +/- 45 pmol/mmol creatinine; mean +/- SD) and 2,3-dinor-TXB2 (725 +/- 676 v 82 +/- 43 pmol/mmol creatinine) than controls. In contrast, urinary LTE4 was not significantly different. Enhanced metabolite excretion did not correlate with the platelet count or with the hematocrit value, and was not related to the current treatment or to a clinical history of thrombotic complications. Platelet TX receptor studies did not show any significant changes in the binding characteristics of two different ligands. A platelet-selective regimen of aspirin therapy (50 mg/d for 7 to 14 days) was associated with greater than 80% suppression in metabolite excretion in nine patients. These results are consistent with abnormal stimuli operating in polycythemia vera to induce a selective enhancement in the platelet biosynthesis of TXA2 without changes in receptor binding. This in vivo abnormality in platelet biochemistry can be largely suppressed by low doses of aspirin.
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PMID:Increased thromboxane biosynthesis in patients with polycythemia vera: evidence for aspirin-suppressible platelet activation in vivo. 835 96

The arachidonate metabolism by leukocytes and platelets was studied in 14 patients with myeloproliferative disorders including 7 patients with chronic myeloid leukemia (CML), 5 with polycythemia vera (PV) and 2 with essential thrombocythemia (ET). When the leukocytes were incubated with arachidonate and A23187, leukotriene B4 and hydroxyeicosatetraenoic acids (HETEs) were constantly detected using reversed-phase high-performance liquid chromatography in normal subjects, while selective deficiency of 5-lipoxygenase products (leukotriene B4 and 5-HETE) was found in 4 patients with CML. this novel abnormality of the leukocytes seemed to be derived from the possible deficiency of 5-lipoxygenase in these patients' polymorphonuclear neutrophils (PMNNs). The formation of 15-HETE appeared to be almost normal in all the patients. Platelet 12-lipoxygenase deficiency was detected in 2 patients with PV and 2 with CML in whom one was associated with the deficiency of 5-lipoxygenase products. These bicellular abnormalities of the arachidonate metabolism might contribute to understand dysfunctions of PMNNs and platelets in some patients with myeloproliferative disorders.
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PMID:Altered arachidonate metabolism by leukocytes and platelets in myeloproliferative disorders. 631 27