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Topic: Hypoxanthine

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	lesch-nyhan03.html
		Plasma and 24-h urinary concentrations of hypoxanthine, xanthine and uric acid were measured while subjects were on a purine-restricted diet.
		The sensitivity of 24-h urinary hypoxanthine and xanthine excretion rates was 86% and 77%, respectively, and the specificity 100% for both tests.
		An elevated hypoxanthine and/or xanthine excretion rate differentiated most heterozygotes for HPRT deficiency from non-carrier women and thus could be useful for carrier diagnosis.
	www.indiana.edu /~pietsch/lesch-nyhan03.html (2249 words)

	Fetal Plasma Hypoxanthine Level in Growth-Retarded Fetuses Before Labor -- Sawa et al. 82 (12): 4028 -- Journal of ...
		Hypoxanthine is one of the purine nucleotides and is presumed
		hypoxanthine is correlated with fetal hypoxia and acidosis in
		HYPOXANTHINE is one of the intermediates in the degradation
	jcem.endojournals.org /cgi/content/full/82/12/4028 (2419 words)

	[No title]
		Hypoxanthine is released from the muscle into the blood-stream for more than an hour after the termination of short-term intensive exercise which means that there is a net loss of nucleotides from the muscle.
		As HPRT catalyzes the rephosphorylation of hypoxanthine to IMP (Fig.
		As the arterial concentration of hypoxanthine is increased, this purine is extracted by the liver and oxidized to uric acid.
	www.sportsci.org /encyc/drafts/Purines.doc (2977 words)

	eMedicine - Xanthinuria : Article by Sahar Fathallah-Shaykh, MD (Site not responding. Last check: 2007-09-25)
		Hypoxanthine does not accumulate to an appreciable degree because it is recycled through a salvage pathway by the enzyme hypoxanthine guanine phosphoribosyltransferase (HGPRT).
		Xanthine dehydrogenase catalyzes 2 reactions, conversion of hypoxanthine to xanthine and conversion of xanthine to uric acid.
		The accumulation of xanthine is caused by the catabolism of guanine to xanthine by guanase and the lack of a salvage pathway for xanthine.
	www.emedicine.com /ped/topic2452.htm (2911 words)

	Purine salvage to adenine nucleotides in different skeletal muscle fiber types -- Brault and Terjung 91 (1): 231 -- ...
		Adenine and hypoxanthine salvage rates in the plantaris muscle as a function of increasing purine concentration ([purine]) in the perfusate medium (n = 3-5/group).
		Purine synthesis de novo and salvage in hypoxanthine phosphoribosyltransferase-deficient mice.
		Metabolism and salvage of adenine and hypoxanthine by myocytes isolated from mature rat heart.
	jap.physiology.org /cgi/content/full/91/1/231 (4863 words)

	Myocardial release of lactate, inosine and hypoxanthine during atrial pacing and exercise-induced angina -- Kugler 59 ...
		Myocardial release of lactate, inosine and hypoxanthine during atrial pacing and exercise-induced angina -- Kugler 59 (1): 43 -- Circulation
		Myocardial release of lactate, inosine and hypoxanthine during atrial pacing and exercise-induced angina
		increase of arterial inosine and hypoxanthine values was not significant.
	circ.ahajournals.org /cgi/content/abstract/59/1/43 (261 words)

	[No title]
		When, however, hypoxanthine is coupled with PABA it shows a different, more pronounced neurological effect and a decreased immunological effect.
		Hypoxanthine is also actively transported across the blood-brain barrier (BBB) by a saturable transport system (Spector, 1987).
		The ability to be moved across the BBB may be an important role of hypoxanthine in the efficacy of AIT-082.
	www.bio.davidson.edu /biology/student/Cooke/dlcintro.html (1219 words)

	Non-Sensory Assessment of Fish Quality
		The rate of accumulation of hypoxanthine is not the same in all species and this must be remembered when interpreting the results.
		The amount of hypoxanthine present is measured either by an enzymic method that converts hypoxanthine into uric acid, or by separating the hypoxanthine from any remaining ATP and the intermediate compounds by a technique called high pressure liquid chromatography (HPLC).
		Like hypoxanthine, the K value measures the extent of the breakdown of ATP: it is the percentage of the initial ATP present at death that has been converted by enzyme action into hypoxanthine and its immediate precursor, called inosine, in the chain of decomposition of ATP.
	www.fao.org /wairdocs/tan/x5990e/X5990e01.htm (2785 words)

	Product Label
		It is an inhibitor of xanthine oxidase, the enzyme responsible for the conversion of hypoxanthine to xanthine and of xanthine to uric acid, the end product of purine metabolism in man. Allopurinol is metabolized to the corresponding xanthine analogue, oxypurinol (alloxanthine), which also is an inhibitor of xanthine oxidase.
		Reutilization of both hypoxanthine and xanthine for nucleotide and nucleic acid synthesis is markedly enhanced when their oxidations are inhibited by allopurinol and oxypurinol.
		As a result of xanthine oxidase inhibition, the serum concentration of hypoxanthine plus xanthine in patients receiving allopurinol for treatment of hyperuricemia is usually in the range of 0.3 to 0.4 mg/dL compared to a normal level of approximately 0.15 mg/dL.
	www.accessdata.fda.gov /scripts/cder/onctools/labels.cfm?GN=allopurinol (3435 words)

	Purine and Pyrimidine Metabolism Disorders: Inherited Disorders of Metabolism: Merck Manual Professional
		This is a rare, X-linked, recessive disorder caused by deficiency of hypoxanthine-guanine phosphoribosyl transferase (HPRT); degree of deficiency (and hence manifestations) vary with the specific mutation.
		Allopurinol prevents conversion of accumulated hypoxanthine to uric acid; because hypoxanthine is highly soluble, it is excreted.
		Diagnosis is by low plasma uric acid and high urine and plasma hypoxanthine and xanthine.
	www.merck.com /mmpe/print/sec19/ch296/ch296i.html (893 words)

	Incorporation of [14C]hypoxanthine into cardiac adenine nucleotides: effect of aging and post-ischemic reperfusion. (Site not responding. Last check: 2007-09-25)
		In order to investigate whether the 'hypoxanthine salvage' pathway of the cardiac muscle is modified with age, we aerobically perfused isolated hearts of 4-month- and 22-month-old male Wistar rats for 20 min with 0.18 microM [14C]hypoxanthine.
		A second group of hearts was subjected to a 30-min ischemic perfusion (95% reduction of the coronary flow), followed by 20 min of reperfusion.
		Moreover, the content of each labeled adenine nucleotide was significantly higher in aged than young hearts at the end of the aerobic period, whereas the incorporation of the labeled hypoxanthine was not affected by age after 20 min of reperfusion.
	www.arclab.org /medlineupdates/abstract_8422432.html (325 words)

	British Journal of Pharmacology - Interaction of hypoxanthine/xanthine oxidase with nitrergic relaxation in the porcine ...
		Xanthine oxidase (XO) catalyzes the sequential breakdown of hypoxanthine (HX) to xanthine and subsequently to uric acid; in this oxidation process, XO concomitantly generates several reactive oxygen species by reducing molecular oxygen (Kooij, 1994).
		Chemical interactions between reactive oxygen species (such as superoxide, a continuously formed free radical in aerobic cells) and NO are described as near-diffusion limited (Huie and Padmaja, 1993), and are recognized as being of critical importance for modulating the signal transduction actions of NO as well as for oxidative damage (Gross and Wolin, 1995).
		The amplitude of the second phase of the biphasic relaxation appeared to be strongly attenuated by uricase, while the amplitude of the initial phase was unaffected.
	www.nature.com /bjp/journal/v130/n2/full/0703317a.html (5381 words)

	Allopurinol - Allopurinol Side Effects - Allopurinol Information - Canada Pharmacy - Canada Drugs
		Along with its active metabolite, oxypurinol, allopurinol inhibits xanthine oxidase, the enzyme responsible for the conversion of hypoxanthine to xanthine and of xanthine to uric acid.
		Accompanying the decrease in uric acid produced by allopurinol is an increase in serum and urine concentrations of hypoxanthine and xanthine.
		After administration of allopurinol, it is composed of hypoxanthine, xanthine and uric acid.
	www.rxcarecanada.com /Allopurinol.asp (2392 words)

	xanthine oxidase (Site not responding. Last check: 2007-09-25)
		Hypoxanthine is oxidized successively to xanthine and then to uric acid by xanthine oxidase.
		Also oxidizes hypoxanthine, some other purines and pterins, and aldehydes [2].
		Xanthine and hypoxanthine are oxidized at the molybdenum center, the metal being reduced from the VI to the IV valence state; the reducing equivalents are transferred to molecular oxygen at the FAD with the mediation of the iron-sulfur centers [11].
	www.bilkent.edu.tr /~ozgun/biochem/xo.htm (728 words)

	Nucleobase - Wikipedia, the free encyclopedia
		A base covalently bound to the 1' carbon of a ribose or deoxyribose is called a nucleoside, and a nucleoside with one or more phosphate groups attached at the 5' carbon is called a nucleotide.
		Hypoxanthine and Xanthine are created through Mutagen presence, through De-amination (replacement of the Amine-Group with a Hydroxyl-Group).
		Hypoxanthine is produced from Adenine, Xanthin from Guanin and Uracil from Cytosine.
	en.wikipedia.org /wiki/Nucleobase (266 words)

	Fetal Plasma Hypoxanthine Level in Growth-Retarded Fetuses Before Labor -- Sawa et al. 82 (12): 4028 -- Journal of ...
		Fetal Plasma Hypoxanthine Level in Growth-Retarded Fetuses Before Labor -- Sawa et al.
		however, whether plasma hypoxanthine concentration is a useful
		venous plasma hypoxanthine concentration was found to be increased
	jcem.endojournals.org /cgi/content/abstract/82/12/4028 (249 words)

	Incision at hypoxanthine residues in DNA by a mammalian homologue of the Escherichia coli antimutator enzyme ...
		Incision at hypoxanthine residues in DNA by a mammalian homologue of the Escherichia coli antimutator enzyme endonuclease V -- Moe et al.
		Incision at hypoxanthine residues in DNA by a mammalian homologue of the Escherichia coli antimutator enzyme endonuclease V
		Deamination of adenine to hypoxanthine induces AT to GC transitions
	nar.oxfordjournals.org /cgi/content/full/31/14/3893 (4222 words)

	Substrate inhibition in a human variant of hypoxanthine-guanine phosphoribosyltransferase -- Steyn and Harley 259 (1): ...
		activity was susceptible to substrate inhibition by hypoxanthine and
		hypoxanthine were 26 +/- 10 microM, 1761 +/- 382 microunits/mg of protein,
		inhibition, as seen on a plot of 1/v versus hypoxanthine concentration, was
	www.jbc.org /cgi/content/abstract/259/1/338 (296 words)

	For Biol 461: Hypoxanthine-guanine phosphoribosyl transferase
		The gene coding for HGPRT, or Hypoxanthine guanine phosphoribosyltransferase is found on the long arm of the X chromosome, q26-q27.2.
		Novel nonsense mutation in the hypoxanthine guanine phosphoribosyltransferase gene and nonrandom X-inactivation causing Lesch-Nyhan syndrome in a female patient.
		Postnatal expression of hypoxanthine guanine phosphoribosyltransferase in the mouse brain.
	publish.uwo.ca /~amerkxja/biology/hgprt.html (1851 words)

	Purines inhibit poly(ADP-ribose) polymerase activation and modulate oxidant-induced cell death -- VIRÁG and ...
		Effect of hypoxanthine on caspase activation and DNA fragmentation in peroxynitrite (ONOO) -treated thymocytes.
		Harkness, R. (1988) Hypoxanthine, xanthine and uridine in body fluids, indicators of ATP depletion.
		Mei, D. A., Gross, G. J., Nithipatikom, K. (1996) Simultaneous determination of adenosine, inosine, hypoxanthine, xanthine, and uric acid in microdialysis samples using microbore column high-performance liquid chromatography with a diode array detector.
	www.fasebj.org /cgi/content/full/15/1/99 (5554 words)

	Purine Nucleobase Transport in Amastigotes of Leishmania mexicana: Involvement in Allopurinol Uptake -- Al-Salabi and ...
		hypoxanthine analogue, was apparently taken up by the same transporter.
		H]hypoxanthine over 60 s was inhibited by the indicated concentrations of unlabeled hypoxanthine, with an IC of 0.81 µM for this experiment.
		Hypoxanthine uptake through a purine-selective nucleobase transporter in Trypanosoma brucei brucei procyclic cells is driven by protonmotive force.
	aac.asm.org /cgi/content/full/49/9/3682 (3977 words)

	Yeast GMP Kinase Mutants Constitutively Express AMP Biosynthesis Genes by Phenocopying a Hypoxanthine-Guanine ...
		for hypoxanthine were determined in the absence of GMP and in the presence of either 50, 100, or 200 µ
		In vivo hypoxanthine utilization is affected in the guk1-2 mutant.
		Transformants were grown on SC medium or on the same medium supplemented with 8AG, adenine (Ade), or hypoxanthine (Hyp).
	www.genetics.org /cgi/content/full/156/3/953 (4616 words)

	Renal interstitial adenosine metabolism during ischemia in dogs -- Nishiyama et al. 280 (2): 231 -- AJP - Renal ...
		For the determination of renal interstitial concentrations of adenosine, inosine, and hypoxanthine, we used a microdialysis
		significantly decreased inosine and hypoxanthine to 0.17 ± 0.07
		Figure 4 shows the changes in renal interstitial concentrations of inosine and hypoxanthine during ischemia.
	ajprenal.physiology.org /cgi/content/full/280/2/F231 (4587 words)

	HPRT1 - Genetics Home Reference
		Specifically, this enzyme helps convert the purine hypoxanthine into inosine monophosphate and the purine guanine into guanosine monophosphate.
		These conversions are necessary steps in the process of recycling purines to ensure that cells have a plentiful supply of building blocks for the production of DNA and RNA.
		Mutations in the HPRT1 gene are responsible for HPRT-related gout (arthritis caused by uric acid in the joints) previously known as Kelley-Seegmiller syndrome.
	ghr.nlm.nih.gov /gene=hprt1 (606 words)

	Lesch-Nyhan Syndrome
		The enzyme catalyzes the conversion of hypoxanthine to inosinic acid (IMP) and guanine to guanylic acid (GMP) in the presence of phosphoribosylpyrophosphate.
		Duan J, Nilsson L, Lambert B (2004) Structural and functional analysis of mutations at the human hypoxanthine phosphoribosyl transferase (HPRT1) locus.
		Gibbs RA, Nguyen PN, Edwards A, Civitello AB, Caskey CT (1990) Multiplex DNA deletion detection and exon sequencing of the hypoxanthine phosphoribosyltransferase gene in Lesch-Nyhan families.
	www.geneclinics.org /profiles/lns/details.html (5130 words)

	UniProtKB/Swiss-Prot entry P00492 [HPRT_HUMAN] Hypoxanthine-guanine phosphoribosyltransferase
		Wilson J.M. Tarr G.E. Kelley W.N. "Human hypoxanthine (guanine) phosphoribosyltransferase: an amino acid substitution in a mutant form of the enzyme isolated from a patient with gout.";
		Davidson B.L. Pashmforoush M. Kelly W.N. Palella T.D. "Genetic basis of hypoxanthine guanine phosphoribosyltransferase deficiency in a patient with the Lesch-Nyhan syndrome (HPRTFlint).";
		Burgemeister R. Roetzer E. Gutensohn W. Gehrke M. Schiel W. "Identification of a new missense mutation in exon 2 of the human hypoxanthine phosphoribosyltransferase gene (HPRTIsar): a further example of clinical heterogeneity in HPRT deficiencies.";
	ca.expasy.org /uniprot/HPRT_HUMAN (1330 words)

	Hypoxanthine
		Hypoxanthine is a base found in an intermediate of purine nucleotide biosynthesis.
		In addition, hypoxanthine can be converted back to IMP in purine nucleotide salvage biosynthesis (by the enzyme HGPRT).
		Allopurinol, which is similar to hypoxanthine (see here), is used to treat gout because it inhibits xanthine oxidase, leading to accumulation of hypoxanthine and xanthine, both of which are more soluble and more readily excreted than uric acid, the chemical that causes gout.
	greatvistachemicals.com /proteins-sugars-nucleotides/hypoxanthine.html (208 words)

	Characterization of in vivo Somatic Mutations at the Hypoxanthine Phosphoribosyltransferase Gene of a Human Control ... (Site not responding. Last check: 2007-09-25)
		The ability to recognize a change in mutation spectrum after an exposure to a toxic substance and then relate that exposure to health risk depends on the knowledge of mutations that occur in the absence of exposure.
		Toward this end, we have been studying both the frequency and molecular nature of mutations of the hypoxanthine phosphoribosyltransferase (hprt) gene in peripheral blood lymphocytes as surrogate reporters of genetic damage.
		Methylation of the hypoxanthine phosphoribosyltransferase locus on the human X chromosome: Implications of X-chromosome inactivation.
	www.ehponline.org /members/1993/101-1/burkhart-full.html (5498 words)

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