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Xanthine

About: Xanthine is a research topic. Over the lifetime, 4046 publications have been published within this topic receiving 129820 citations. The topic is also known as: Xanthine.


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Journal ArticleDOI
26 May 1967-Science
TL;DR: The excretion of oxypurine metabolites in urine of patients with congenital hyperuricosuria exceeds, on a creatinine basis, that observed in any previously recognized metabolic anomaly.
Abstract: The excretion of oxypurine metabolites in urine of patients with congenital hyperuricosuria exceeds, on a creatinine basis, that observed in any previously recognized metabolic anomaly. The ratio of hypoxanthine to xanthine is from 2:1 to 3:1 and results from increased hypoxanthine excretion, in contrast to other hyperuricosuric conditions where ratios of less than one have been reported. Administration of allopurinol (a xanthine-oxidase inhibitor) reduces the excretion of uric acid but results in an equivalent increase in xanthine and hypoxanthine. These features appear to be unique to congenital hyper-uricosuria.

59 citations

Journal ArticleDOI
TL;DR: Organic nitrite is the initial product in the process of XO-mediated organic nitrate biotransformation and is the precursor of NO and nitrosothiols, serving as the link between organic nitrates and sGC activation.

59 citations

Journal ArticleDOI
TL;DR: The results suggested that only capacitated spermatozoa themselves are able to generate O2- which stimulated their capacitation in turn, and it may be possible to utilize the inhibitory effect of SOD on sperm capacitation so as to regulate fertilization.
Abstract: Capacitation of spermatozoa is an essential procedure for fertilization. Capacitated spermatozoa have an in crease in the intracellular cAMP and acrosome reaction (AR) occurs immediately. The effect of exogenous superoxide anion (O−2) on the level of intracellular c AMP and the percentages of both spontaneous AR and lysophosphatidylcholine-induced AR (LPC-AR) were studied using semen samples collected from 10 healthy and fertile volunteers working or studying in Lanzhou Medical College. Spermatozoa were separated by Percoll and incubated at 37°C in Ham's F-10 medium with O−2 generation system: xanthine + xanthine oxidase + catalase + diethylenetriaminepentaacetic acid + sodium formate. The intracellular cAMP was deter mined by (3H)— cAMP radioimmunoassay at 3 h of incubation, and the percentages of AR and LPC-AR were evaluated by the triple-stain technique at 3.5 h of incubation. The effects of SOD with different concentration were also determined. The results showed: the level of intracellular CAMP (pmol...

59 citations

Journal ArticleDOI
TL;DR: Propyl gallate protected hepatocytes against the cascade of oxyradicals produced by xanthine oxidase-hypoxanthine, and approximately halved the amount of lipid conjugated dienes formed in tissues after oxidant damage.

59 citations

Journal ArticleDOI
TL;DR: A good correlation was observed in both subjects between the urinary 1U/1X molar ratio and the ratio of endogenous urate to hypoxanthine + xanthine at the different allopurinol doses, supporting the proposal that the 1U-1Xmolar ratio after caffeine intake provides an in vivo index ofxanthine oxidase activity in man.
Abstract: Caffeine (5 mg kg-1) was administered orally to two healthy, non-smoking subjects on three separate occasions--before, and during therapy with the xanthine oxidase inhibitor allopurinol at doses of either 300 or 600 mg daily. Plasma and urinary levels of methylxanthines, endogenous oxypurines and allopurinol and its metabolite oxypurinol were measured using h.p.l.c. analyses. Allopurinol treatment caused a specific, dose-dependent inhibition of the conversion of the caffeine metabolite 1-methylxanthine (1X) to 1-methyluric acid (1U). A good correlation was observed in both subjects between the urinary 1U/1X molar ratio and the ratio of endogenous urate to hypoxanthine + xanthine at the different allopurinol doses, supporting the proposal that the 1U/1X molar ratio after caffeine intake provides an in vivo index of xanthine oxidase activity in man.

59 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202361
2022108
202157
202060
201961
201869