What's the difference between hypoxanthin and xanthin?
Hypoxanthin
Definition:
(n.) A crystalline, nitrogenous substance, closely related to xanthin and uric acid, widely distributed through the animal body, but especially in muscle tissue; -- called also sarcin, sarkin.
Example Sentences:
(1) The hprt T-cell cloning assay allows the detection of mutations occurring in vivo in the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene of T-lymphocytes.
(2) The incorporation of inosine or hypoxanthine into the IMP and ITP has been proved.
(3) This method has been used to identify cells with biochemical lesions in the oxidation of propionate, galactose, hypoxanthine and pyruvate; it has allowed us to identify a new variant of methylmalonicaciduria; we believe it can be extended to include other metabolites and pathways.
(4) 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.
(5) Regulation of the uric acid-xanthine transport system and the hypoxanthine-adenine-guanine transport system was studied.
(6) 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.
(7) Only the content of uricogenic bases (adenine and hypoxanthine) varied among the test meals.
(8) 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.
(9) The paired cervical and rectal isolates from one patient with uncomplicated gonorrhea differed only with respect to a requirement for hypoxanthine.
(10) Two apparent types of alterations of this enzyme were distinguished: (1) increased specific activity with a normal half life as in megaloblastic anemia, and (2) a prolonged half life with or without an elevation of specific activity as in the deficiency of hypoxanthine-guanine phosphoribosyltransferase.
(11) Inosine and hypoxanthine release were attenuated at the higher dose of deoxycoformycin.
(12) Recovered hybrid cells produced the chick hypoxanthine phosphoribosyltransferase exclusively, as demonstrated by electrophoretic mobility and immunoprecipitation tests, even though no chick chromosomes or chick cell-surface antigens could be identified in the hybrids.
(13) In synchronous cells, uracil DNA glycosylase and hypoxanthine DNA glycosylase were induced with an extent of induction (5-6-fold) comparable to that observed for normal human cells.
(14) Our aim was to evaluate the sensitivity of human fibroblasts, in comparison with umbilical vein endothelial cells, to two common reactive oxygen metabolites, to superoxide produced by hypoxanthine and xanthine oxidase, and to reagent hydrogen peroxide.
(15) Guanosine greater than inosine = hypoxanthine greater than adenosine were taken up with decreasing initial velocities, respectively; adenine was not transported.
(16) Etheno-NADP+, 3-acetylpyridine-adenine dinucleotide phosphate, and nicotinamide-hypoxanthine dinucleotide phosphate act as alternative coenzymes for the enzyme.
(17) A dramatic increase in the concentrations of adenosine, inosine and hypoxanthine was detected by microdialysis in the dorsal part of hippocampus and in the striatum immediately after 5 min bilateral occlusion of the carotid arteries.
(18) If guanine were to be substituted for hypoxanthine in an isogeometrical molecular structure, additional hydrogen bonds could be made between every N-2 and N-7.
(19) HPLC tracing of radiolabelled purines or purine nucleosides revealed that adenine, adenosine and hypoxanthine are incorporated into adenine nucleotides and IMP through a similar channel while guanine and guanosine are salvaged into guanine nucleotides via another route.
(20) Among the four purine bases, adenine and hypoxanthine have been reported to be more uricogenic than guanine and xanthine.
Xanthin
Definition:
(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).