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XanthineXanthine DehydrogenasePurine-Pyrimidine Metabolism, Inborn ErrorsXanthinesXanthine OxidaseHypoxanthineHypoxanthinesPteridinesMetabolism, Inborn ErrorsCoenzymesMetalloproteinsKidney CalculiAllopurinolOxypurinolMolybdenumAldehyde OxidaseUric AcidKetone OxidoreductasesMilkSuperoxidesFree RadicalsPurinesTungstenHydroxidesSuperoxide DismutaseOxidation-ReductionElectron Spin Resonance SpectroscopyTungsten CompoundsEncyclopedias as Topic

Uric acidHereditary xanthinuriaDehydrogenaseAllopurinolMolybdenumDeficiencyHypoxanthineInhibitionEnzymeOxidoreductaseRenalIatrogenicNephrolithiasisUrolithiasisMutationsUrinaryOrgansGeneticRareKidneyTreatmentPatientsFormBloodAldehyde oxidaseUrineConcentrations of xanthineOxidaseMutationsStonesUrateMechanismTypeLevelsActivity

Uric acid15

• These enzymes catalyze the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. (wikipedia.org)
• The following chemical reactions are catalyzed by xanthine oxidase: hypoxanthine + H2O + O2 ⇌ xanthine + H2O2 xanthine + H2O + O2 ⇌ uric acid + H2O2 Xanthine oxidase can also act on certain other purines, pterins, and aldehydes. (wikipedia.org)
• hypoxanthine (one oxygen atom) xanthine (two oxygens) uric acid (three oxygens) Because XO is a superoxide-producing enzyme, with general low specificity, it can be combined with other compounds and enzymes and create reactive oxidants, as well as oxidize other substrates. (wikipedia.org)
• In the reaction with xanthine to form uric acid, an oxygen atom is transferred from molybdenum to xanthine, whereby several intermediates are assumed to be involved. (wikipedia.org)
• Because xanthine oxidase is a metabolic pathway for uric acid formation, the xanthine oxidase inhibitor allopurinol is used in the treatment of gout. (wikipedia.org)
• Two inherited forms of xanthinuria principally result from a deficiency of the enzyme xanthine dehydrogenase, which is the enzyme responsible for degrading hypoxanthine and xanthine to uric acid. (medscape.com)
• Iatrogenic xanthinuria can occur during allopurinol therapy, which is used to reduce urine uric acid excretion in conditions with endogenous overproduction of uric acid. (medscape.com)
• We analyzed the changes of the cerebral uric acid level after administration of allopurinol, a specific inhibitor of xanthine oxidase, in rats with cold injury Allopurinol markedly suppressed the increase of uric acid 3 hours after injury. (go.jp)
• These results suggest that in injured brain tissue, uric acid is generated from xanthine or hypoxanthine by xanthine oxidase. (go.jp)
• It can be caused by a deficiency of xanthine oxidase , which is an enzyme necessary for converting xanthine to uric acid . (wikidoc.org)
• Specifically, it inhibits the enzyme which metabolizes the conversion of the purine base xanthine to uric acid. (animalwised.com)
• Pre-and post-prandial plasma concentrations of allopurinol, oxypurinol, xanthine, hypoxanthine and uric acid were established by high performance liquid chromatography in red-tailed hawks (RTH, Buteo jamaicensis) at various time intervals after receiving allopurinol (50 mg/kg SID) or placebo. (umn.edu)
• The usual choice for reducing uric acid levels is allopurinol, because it inhibits xanthine oxidase and can depress new purine synthesis. (yourdictionary.com)
• It is a xanthine oxidase inhibitor and accordingly inhibits the biosynthesis of uric acid. (yourdictionary.com)
• Xanthine dehydrogenase (XDH) is the enzymes responsible for the conversion of xanthine to uric acid. (np-mrd.org)

Hereditary xanthinuria3

• Hereditary xanthinuria is a rare autosomal recessive disorder of purine metabolism caused by mutations in xanthine dehydrogenase (Type I) or molybdenum cofactor sulfarase (Type II) genes, and causes xanthine uroliths. (urolithcenter.org)
• Consider candidate gene (xanthine dehydrogenase and molybdenum cofactor sulfurase) sequencing for hereditary xanthinuria. (urolithcenter.org)
• Isoxanthopterin is very low in some cases of hereditary xanthinuria (OMIM 278300 ) and molybdenum cofactor deficiency (OMIM 252150 ). (np-mrd.org)

Dehydrogenase12

• The same protein, which in humans has the HGNC approved gene symbol XDH, can also have xanthine dehydrogenase activity (EC 1.17.1.4). (wikipedia.org)
• Most of the protein in the liver exists in a form with xanthine dehydrogenase activity, but it can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. (wikipedia.org)
• Deficiency of xanthine dehydrogenase results in plasma accumulation and excess urinary excretion of the highly insoluble xanthine, which may lead to arthropathy, myopathy, crystal nephropathy, urolithiasis, or renal failure. (medscape.com)
• Classic xanthinuria type I is the result of an isolated deficiency of xanthine dehydrogenase. (medscape.com)
• Type II xanthinuria is characterized by a deficiency of xanthine dehydrogenase and a related enzyme, aldehyde oxidase. (medscape.com)
• The distinction between the 2 types is based on the ability or inability to oxidize allopurinol, a substrate for xanthine dehydrogenase and aldehyde oxidase. (medscape.com)
• This condition is inherited recessively and is caused by a congenital defect of a molybdenum-containing cofactor essential for the function of 3 distinct enzymes (ie, xanthine dehydrogenase, aldehyde oxidase, sulfite oxidase). (medscape.com)
• Inhibition of xanthine dehydrogenase by allopurinol may lead to accumulation and urinary excretion of xanthine. (medscape.com)
• Eliminate Xanthine dehydrogenase inhibitors (e.g. allopurinol) as a cause. (urolithcenter.org)
• Discontinue or reduce xanthine dehydrogenase inhibitors. (urolithcenter.org)
• Its etiology may have a genetic origin or may be due to an iatrogenic xanthine-dehydrogenase inhibition that finally results in urolithiasis. (unileon.es)
• Here is some fragment output from a query designed to find complete coding regions for genes encoding xanthine dehydrogenase. (yourdictionary.com)

Allopurinol5

• Since xanthine oxidase is involved in the metabolism of 6-mercaptopurine, caution should be taken before administering allopurinol and 6-mercaptopurine, or its prodrug azathioprine, in conjunction. (wikipedia.org)
• Type II xanthinuria may result from a failure of the mechanism which inserts sulfur into the active sites of xanthine oxidase and aldehyde oxidase, a related enzyme with some overlapping activities (such as conversion of allopurinol to oxypurinol). (wikipedia.org)
• Patients with Lesch-Nyhan syndrome or patients with partial HGPRT deficiency have developed xanthine nephropathy, acute kidney failure, and stones following treatment with allopurinol. (medscape.com)
• [ 3 ] A few incidents of xanthine nephropathy and renal failure have been reported in patients treated with allopurinol during chemotherapy for malignancy. (medscape.com)
• 1991). Xanthine-containing urinary calculi in dogs given allopurinol. (unileon.es)

Molybdenum2

• The other inherited form of xanthinuria, termed molybdenum cofactor deficiency, presents in the neonatal period with microcephaly, hyperreflexia, and other CNS manifestations. (medscape.com)
• Dive into the research topics of 'Rare cause of xanthinuria: a pediatric case of molybdenum cofactor deficiency B'. Together they form a unique fingerprint. (wustl.edu)

Deficiency4

• Classic xanthinuria is one form of xanthinuria that is divided into 2 types based on the enzyme deficiency. (medscape.com)
• Xanthinuria is only a marker in this setting because (1) the clinical presentation is overshadowed by neurologic manifestations and (2) death in the first year of life is caused by the deficiency of sulfite oxidase, which is the final step in cysteine metabolism. (medscape.com)
• Xanthinuria , also known as xanthine oxidase deficiency , is a rare genetic disorder causing the accumulation of xanthine . (wikidoc.org)
• It is caused by a deficiency of the enzyme xanthine oxidase . (wikidoc.org)

Hypoxanthine2

• Xanthine continues to accumulate, despite the recycling of hypoxanthine, because of the metabolism of guanine to xanthine by the enzyme guanase (see image below). (medscape.com)
• Markedly elevated plasma concentrations of oxypurinol, xanthine and hypoxanthine were seen in experimental birds. (umn.edu)

Inhibition2

• Bovine xanthine oxidase (from milk) was originally thought to have a binding site to reduce cytochrome c with, but it has been found that the mechanism to reduce this protein is through XO's superoxide anion byproduct, with competitive inhibition by carbonic anhydrase. (wikipedia.org)
• Inhibition of xanthine oxidase has been proposed as a mechanism for improving cardiovascular health. (wikipedia.org)

Enzyme4

• Xanthine oxidase (XO, sometimes 'XAO') is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. (wikipedia.org)
• Xanthine oxidase is defined as an enzyme activity (EC 1.17.3.2). (wikipedia.org)
• Xanthine oxidase is a superoxide-producing enzyme found normally in serum and the lungs, and its activity is increased during influenza A infection. (wikipedia.org)
• when purine bases are degraded by the corresponding enzyme, xanthine is created. (animalwised.com)

Oxidoreductase1

• It is suggested that xanthine oxidoreductase, along with other enzymes, participates in the conversion of nitrate to nitrite in mammalian tissues. (wikipedia.org)

Renal4

• Xanthinuria is a rare genetic disorder where the lack of xanthine oxidase leads to high concentration of xanthine in blood and can cause health problems such as renal failure. (wikipedia.org)
• Sufferers have unusually high concentrations of xanthine in their blood and urine, which can lead to health problems such as renal failure and xanthine kidney stones, one of the rarest types of kidney stones. (wikidoc.org)
• Irritation of the tubular epithelium by xanthine crystals results in hematuria, whereas renal tissue deposits induce an inflammatory reaction and consequent interstitial nephritis. (medscape.com)
• Xanthinuria was considered to be the cause of the observed renal function disorder. (umn.edu)

Iatrogenic1

• This discussion focuses on the classic and iatrogenic forms of xanthinuria in children. (medscape.com)

Nephrolithiasis1

• Bilateral xanthine nephrolithiasis in a dog. (unileon.es)

Urolithiasis4

• The present work reports two cases of xanthine urolithiasis in European Shorthair unrelated male and female cats. (unileon.es)
• 2003). Feline xanthine urolithiasis: A newly recognized cause of feline lower urinary tract disease. (unileon.es)
• Xanthine urolithiasis in a Dachshund. (unileon.es)
• 1997). Naturally occurring xanthine urolithiasis in a domestic shorthair cat. (unileon.es)

Mutations1

• Type I xanthinuria has been traced directly to mutations of the XDH gene which mediates xanthine oxidase activity. (wikipedia.org)

Urinary1

• Xanthinuria is a descriptive term for excess urinary excretion of the purine base xanthine. (medscape.com)

Organs1

• The primary organs affected in xanthinuria are the kidney and, to a lesser extent, skeletal muscle and joints. (medscape.com)

Genetic1

• Stones related to genetic pathologies were identified in 7 (0,9%) patients, 5 of cystine and 2 of xanthine, allowing the definitive diagnosis of cystinuria and xanthinuria, respectively. (una.py)

Rare1

• Xanthinuria is a very rare disease in cats. (unileon.es)

Kidney1

• Kidney complications are initiated by the formation of xanthine crystals in the tubules, leading to parenchymal deposition and/or radiolucent stone formation. (medscape.com)

Treatment1

• Particular caution is advised in severe asthma, as this effect may be potentiated by concomitant treatment with xanthine derivatives, steroids and diuretics. (yourdictionary.com)

Patients1

• Thus, patients with volume depletion who have xanthinuria are at particular risk of forming xanthine crystals. (medscape.com)

Form1

• Another reaction catalyzed by xanthine oxidase is the decomposition of S-nitrosothiols (RSNO), a class of reactive nitrogen species, to nitric oxide (NO), which reacts with a superoxide anion to form peroxynitrite under aerobic conditions. (wikipedia.org)

Blood1

• During severe liver damage, xanthine oxidase is released into the blood, so a blood assay for XO is a way to determine if liver damage has happened. (wikipedia.org)

Aldehyde oxidase6

• Type I xanthinuria involves XOR deficiency due to genetic defect of XOR, whereas type II xanthinuria involves dual deficiency of XOR and aldehyde oxidase (AO, a molybdoflavo enzyme similar to XOR) due to genetic defect in the molybdenum cofactor sulfurase. (nih.gov)
• Patients with classic xanthinuria type I are deficient in xanthine dehydrogenase, whereas patients with type II have a dual deficiency of xanthine dehydrogenase and aldehyde oxidase. (medscape.com)
• Xanthine oxidase/dehydrogenase (XDH) and aldehyde oxidase (AO) compete with TPMT to inactivate AZA. (medscape.com)
• Xanthinuria is an autosomal recessive disease that is caused by either xanthine dehydrogenase deficiency (xanthinuria type I) or xanthine dehydrogenase and aldehyde oxidase deficiency (xanthinuria type II). (healthincode.com)
• Sulfation of molybdenum is essential for xanthine dehydrogenase (XDH) and aldehyde oxidase (ADO) enzymes in which molybdenum cofactor is liganded by 1 oxygen and 1 sulfur atom in active form. (nih.gov)
• This gene encodes an enzyme that sulfurates the molybdenum cofactor which is required for activation of the xanthine dehydrogenase (XDH) and aldehyde oxidase (AO) enzymes. (nih.gov)

Urine5

• Human diseases associated with genetically determined dysfunction of XOR are termed xanthinuria, because of the excretion of xanthine in urine. (nih.gov)
• Affected people have unusually high concentrations of xanthine in their blood and urine, which can lead to health problems such as renal failure and xanthine kidney stones, one of the rarest types of kidney stones. (wikipedia.org)
• If xanthinuria is suspected, identify a laboratory that can accurately measure urine xanthine and hypoxanthine. (medscape.com)
• Xanthine and hypoxanthine levels in the urine in healthy individuals are less than 0.01 µmol per millimole of creatinine. (medscape.com)
• Urine xanthine levels can approach 1 µmol per millimole of creatinine. (medscape.com)

Concentrations of xanthine1

• In general, plasma concentrations of xanthine and hypoxanthine in healthy individuals are less than 1 µmol and less than 5 µmol, respectively. (medscape.com)

Oxidase1

• The other two pathways, thiopurine methyltransferase (TPMT) and xanthine oxidase/dehydrogenase ( XDH ) both produce metabolites which are thought to be inactive and are the first steps in eliminating thiopurines from the body. (medscape.com)

Mutations2

• Xanthinuria type I, is caused by mutations in the XDH gene. (healthincode.com)
• Xanthinuria type II is due to mutations in the MOCOS gene, which codes for molybdenum cofactor sulfarase. (healthincode.com)

Stones1

• Xanthine stones are radiolucent and are not routinely revealed on KUB testing. (medscape.com)

Urate1

• Certain dog breeds are predisposed to developing specific types of urolith, particularly in relation to urate, cystine and xanthine calculi. (royalcanin.com)

Mechanism1

• Mechanism of Substrate and Inhibitor Binding of Rhodobacter capsulatus Xanthine Dehydrogenase. (nih.gov)

Type1

• Xanthinuria is classified into two subtypes, type I and type II. (nih.gov)

Levels1

• The possible range of xanthine plasma levels is 10-40 µmol in classic xanthinuria. (medscape.com)

Activity1

• however, measurement of xanthine dehydrogenase activity is not usually necessary to make the diagnosis of classic xanthinuria. (medscape.com)