(n.) A crystalline nitrogenous body closely related to both uric acid and hypoxanthin, present in muscle tissue, and occasionally found in the urine and in some urinary calculi. It is also present in guano. So called from the yellow color of certain of its salts (nitrates).
(n.) A yellow insoluble coloring matter extracted from yellow flowers; specifically, the coloring matter of madder.
(n.) One of the gaseous or volatile decomposition products of the xanthates, and probably identical with carbon disulphide.
Example Sentences:
(1) The role of O2 free radicals in the reduction of sarcolemmal Na+-K+-ATPase, which occurs during reperfusion of ischemic heart, was examined in isolated guinea pig heart using exogenous scavengers of O2 radicals and an inhibitor of xanthine oxidase.
(2) Initial exposure of cells to low concentrations of either H2O2 or xanthine oxidase resulted in a transient increase in membrane potential relative to control cells (P less than 0.001), followed by an exponential decline in potential (P less than 0.001).
(3) The hepatotoxicity was demonstrated by the elevation in the serum activity of xanthine oxidase, a highly sensitive marker for acute liver damage.
(4) At hypothyroid patients there is an ADP excess which is degenerated to xanthine, the substrate of xanthine oxidase resulting in toxic anion superoxide and UA.
(5) Increased purine degradation, possibly associated with a shift from the dehydrogenase to the xanthine oxidase pathway (secondary to nicotinamide adenine dinucleotide [reduced form]-mediated inhibition of xanthine dehydrogenase activity) is proposed as a possible mechanism for ethanol-stimulated free radical production.
(6) An automated enzymatic method is described for the determination of Cu,Zn-superoxide dismutase (SOD) in plasma or erythrocytes using the xanthine-xanthine oxidase and cytochrome C coupled assay.
(7) In contrast, the location of the receptor labeled with the antagonist [3H]xanthine amine congener [( 3H]XAC) varied in the different types of samples.
(8) Here we report that phenol hydroxylation to hydroquinone is also catalyzed by human myeloperoxidase in the presence of a superoxide anion radical generating system, hypoxanthine and xanthine oxidase.
(9) However, xanthine oxidase has not any significance for the differentiation of tumor types among each others.
(10) The effect of the xanthine oxidase inhibitor, allopurinol, on myocardial ultrastructure after left circumflex coronary artery occlusion (40 min) with or without reperfusion (60 min) was examined in rabbits.
(11) The enzyme xanthine oxidase is involved not only in the conversion of xanthine to uric acid but also in that of retinol to its more toxic metabolite, retinoic acid.
(12) Regulation of the uric acid-xanthine transport system and the hypoxanthine-adenine-guanine transport system was studied.
(13) The oxidation of vitamin E-deficient rat red blood cells (RBCs) induced by the hypoxanthine-xanthine oxidase (HX-XOD) system has been performed in an aqueous suspension.
(14) We applied a sensitive, precise liquid-chromatographic method of analysis for inosine, hypoxanthine, and xanthine to the study of fructose metabolism in humans and in rats.
(15) The current findings show that xanthine oxidase-dependent oxidative stress and the resultant cell death during low-flow hypoxia are spatially restricted in the intermediate zone between the periportal and pericentral regions.
(16) No marked changes of activities of superoxide dismutase, glutathione peroxidase and catalase were observed, but the activity of xanthine oxidase which is strong superoxide generator increased in vitamin E-deficient rat liver.
(17) Xanthine dehydrogenase (XDH) is the initial enzyme in the purine catabolic pathway of N. crassa.
(18) Our results demonstrate that propranolol not only protects cardiac-membrane lipid from peroxidative damage, but also acts as a simple, reversible XOD inhibitor, noncompetitive with xanthine substrate.
(19) Neither xanthine oxidase present in rat brain nor circulating in plasma appears to be the primary source of oxygen radicals that contributes to infarction in focal cerebral ischemia.
(20) For direct measurement of the ESR signal of superoxide anion (O2-) produced in biological samples, O2- generated at a physiological pH was trapped in alkaline media instead of by a rapid freezing method, and then its signal was measured by ESR spectroscopy at 77 K. A reaction mixture for O2- generation, such as xanthine oxidase-xanthine and neutrophils, was incubated at a physiological pH (pH 7.0-7.5) for a suitable reaction period (30s), then an aliquot (300 microliters) was pipetted out and squirted into 600 microliters of 0.5 M NaOH to stabilize O2- (pH-jump).