Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0034065 (pulmonary embolism)
 14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new gas-chromatographic mass-spectrometric method for the rapid determination of 11-dehydro-thromboxane B2 in urine, the major metabolite of systemic thromboxane formation, has been developed. Excellent sample clean-up was obtained in a single step by adsorption of 11-dehydro-TXB2 on phenylboronate cartridges, vigorous polar and organic washing and elution with an acidic methanol mixture. Then the pentafluorobenzylester trimethylsilylether derivative of 11-dehydro-TXB2 was formed and quantified in isotope dilution technique by negative chemical ionisation gas-chromatography tandem mass-spectrometry. The daughter fragments m/z 243/247 of the parent ion m/z 511/515 were monitored. Recovery was linear and quantitative over a wide range, accuracy was 95 + 7% and precision was 11% down to the very low pg range in biologic samples. Independent validation of this very fast extraction method with a reference method applying extensive sample purification with consecutive reversed and straight phase extraction, precolumn derivatisation, reversed phase high pressure liquid chromatography and tandem gas-chromatography mass-spectrometry gave excellent agreement of values. Values for 11-dehydro-TXB2 excretion in 8 healthy controls were 501 + 298 (range 231 to 1141) ng/g creatinin. Excretion was suppressed by aspirin, moderately elevated in heavy smokers (range 680 to 1540) and increased in patients with venous thrombosis or pulmonary embolism (2370 to 13350 ng/g creatinin). This rapid extraction method is useful for the highly specific and sensitive determination of 11-dehydro-TXB2 in large sample numbers.
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PMID:A new method using simple solid phase extraction for the rapid gas-chromatographic mass-spectrometric determination of 11-dehydro-thromboxane B2 in urine. 277 21

In human plasma, 11-dehydrothromboxane (TX) B2 is a major long lived metabolite (t1/2 45 min) formed from infused TXB2, the hydration product of biologically active TXA2. Plasma concentrations of TXB2 itself are readily confounded by ex vivo platelet activation and, theoretically, an enzymatic derivative of this compound, not subject to formation in whole blood, would more accurately reflect TXA2 formation in vivo. To address this hypothesis, we developed a sensitive assay for both 11-dehydro-TXB2 and TXB2, using capillary gas chromatography/negative-ion chemical ionization mass spectrometry. We established that whole blood possesses a minor capacity to form 11-dehydro-TXB2, attributable to nonenzymatic formation in erythrocytes. However, the nonenzymatic formation of 11-dehydro-TXB2 was not a practical limitation to its use as an index of TX biosynthesis. Blood was drawn from healthy volunteers (i) via an indwelling catheter at the time of insertion and at 30, 60, 90, 180, and 240 min thereafter and (ii) via separate venipunctures at 0 time and at 90 and 240 min thereafter. Plasma TXB2 drawn via the catheter at baseline (66 +/- 63 pg/ml) was substantially greater than the maximal estimate of endogenous TXB2 (1-2 pg/ml) in plasma [Patrono, C., Ciabattoni, G., Pugliese, F., Perruci, A., Blair, I. A. & FitzGerald, G. A. (1986) J. Clin. Invest. 77, 590-594] and increased in magnitude and variance over time (339 +/- 247 pg/ml at 240 min). By contrast, 11-dehydro-TXB2 did not change significantly in the sequential catheter samples or in the samples drawn by separate venipuncture. Basal plasma concentrations in volunteers were depressed by pretreatment with 325 mg of aspirin. Furthermore, the range of concentrations in patients with severe atherosclerosis in whom urinary 2,3-dinor-TXB2 was increased was significantly higher (5-50 pg/ml, P less than 0.01) than in healthy subjects (0.9-1.8 pg/ml). Concentrations of 11-dehydro-TXB2 were increased in patients who had recently suffered a pulmonary embolism to a greater extent than either the 11-dehydro-13,14-dihydro-15-keto-TXB2 or the 2,3-dinor-TXB2 metabolites in plasma. These results indicate that plasma TXB2 is readily confounded by platelet activation ex vivo. Measurement of enzymatic metabolites of TXB2 minimizes this problem. The 11-dehydro metabolite is the most appropriate analytic target to detect phasic release of TXA2 in the human circulation, such as might occur in human syndromes of platelet activation.
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PMID:11-Dehydrothromboxane B2: a quantitative index of thromboxane A2 formation in the human circulation. 346 63