Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018099 (gout)
 5,192 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Unknown concentrations of orotic acid can be measured by competition with a known amount of [carboxyl-14C]orotic acid for reaction with a limiting amount of phosphoribosylpyrophosphate in the presence of orotate phosphoribosyltransferase and orotidine monophosphate decarboxylase. The dilution of the specific radioactivity in the product 14CO2 is a sensitive and accurate measure of the amount of orotic acid present in the sample. Orotidine can also be determined after hydrolytic cleavage to orotic acid. The method was used to measure orotic acid and orotidine in urine samples from newborns, healthy controls and patients with gout or deficiency of hypoxanthine-guanine phosphoribosyltransferase receiving allopurinol. Urinary excretion of orotic acid and orotidine in newborns was similar whether the infants were breast-fed or received milk powder. The excretion of orotidine was increased in all patients receiving allopurinol. After allopurinol administration orotic acid excretion was increased in gouty patients but close to normal values in patients with deficiency of hypoxanthine-guanine phosphoribosyltransferase. The results are discussed in relation to the mechanism by which allopurinol inhibits pyrimidine metabolism.
 ...
PMID:The urinary excretion of orotic acid and orotidine, measured by an isotope dilution assay. 36 97

A method using high-performance liquid chromatography (HPLC) for determination of phosphoribosylpyrophosphate (PRPP) synthetase activity in human erythrocytes has been developed and PRPP synthetase activity on purine and pyrimidine metabolic disorders has been studied. Kinetic properties of erythrocyte PRPP synthetase of patients with gout and of a patient with pyrimidine 5'-nucleotidase deficiency were compared with those of healthy subjects. The mean of PRPP synthetase activity of gouty patients was a little higher (P less than 0.01) than that of healthy subjects. The response of the enzyme for ATP of gouty patients was different from that of healthy subjects. The shapes of activation curve of the enzyme for inorganic phosphate were hyperbolic in gouty patients and in a patient with pyrimidine 5'-nucleotidase deficiency.
 ...
PMID:Phosphoribosylpyrophosphate synthetase in human erythrocytes: assay and kinetic studies using high-performance liquid chromatography. 166 46

Allopurinol (4-hydroxypyrazolo (3,4-d)-pyrimidine) is a potent xanthine oxidase inhibitor which inhibits the oxidation of naturally occurring oxypurines, thus decreasing uric acid formation. The clinical and metabolic effects of this agent were studied in 80 subjects with primary and secondary gout and other disorders of uric acid metabolism. Allopurinol has been universally successful in lowering the serum uric acid concentration and uric acid excretion to normal levels, while not significantly affecting the clearance of urate or other aspects of renal function. Oxypurine excretion increased concomitantly with the fall in urine uric acid. The agent is particularly valuable in the management of problems of gout with azotemia, acute uric acid nephropathy and uric acid urolithiasis. The minor side effects, clinical indications and theoretical complications are discussed.
 ...
PMID:The treatment of gout and disorders of uric acid metabolism with allopurinol. 592 71

There has been an explosion of knowledge in disorders of purine and pyrimidine metabolism during the last 20 years. During this time, more than 10 diseases have been discovered and their metabolic bases studied. Hyperuricemia and gout remain the most common clinical disorder. Rarely these disorders are explainable by an inherited enzyme abnormally, such as hypoxanthine-guanine phosphoribosyltransferase deficiency, phosphoribosyl-pyrophosphate synthetase deficiency, or glucose-6-phosphatase deficiency. The description of immunodeficiency syndromes in association with purine enzyme deficiency has led to a novel area of investigation encompassing the biochemical basis for immune function. Although less information is available concerning the other diseases associated with renal calculi, myopathy, anemia, and central nervous system dysfunction, further research will elucidate important metabolic relationships. These will no doubt expand our understanding of the pathogenesis of these disorders and provide innovative therapeutic approaches.
 ...
PMID:Disorders associated with purine and pyrimidine metabolism. 609 39

A reverse phase partition mode of high pressure liquid chromatography was developed for the estimation of purine, pyrimidine and pyrazolopyrimidine nucleosides and bases. This method has been applied to the investigation of purine and pyrimidine metabolism in subjects with gout and/or renal failure during allopurinol therapy. Plasma levels of hypoxanthine and xanthine were quantitated in all subjects. No significant differences were observed between healthy males and gouty subjects with or without allopurinol medication. There was a significant increase in xanthine levels in patients with gout and renal failure, or renal failure on allopurinol, and plasma levels of oxipurinol were increased, but no correlation with glomerular filtration rate (GFR) was observed. The separation method was also used to examine urines from patients with known abnormalities of purine and pyrimidine metabolism in an attempt to evaluate its usefulness as a urine screening technique.
 ...
PMID:Reverse phase partition HPLC for determination of plasma purines and pyrimidines in subjects with gout and renal failure. 738 5

Disorders in purine and pyrimidine metabolism may be difficult to recognize because their recent description means many are little known. They cover a broad spectrum of illnesses, can present from birth to the 80s, have multiple symptoms and lead to early death. Recognition of new disorders requires skill and serendipity. Often parents of affected children provide valuable clues. These disorders should be suspected, particularly where the history involves siblings, in anaemia, susceptibility to infection, or neurological deficits including autism, delayed development, epilepsy, self-mutilation, muscle weakness and - unusual in children and adolescents - gout. Some patients present with kidney stones, renal failure, alone or with the above, or as an intolerance/sensitivity to therapy (fluorouracil or azathioprine immunosuppression). These disorders can be detected from the abnormal metabolites in body fluids and/or altered enzyme activity. Abnormal cellular nucleotides or renal clearance may sometimes provide the only clue. Diagnosis can be difficult because of genetic heterogeneity and interference by blood transfusion, diet or drugs. Tests incorporating enzyme peak shifts and online diode-array detection are essential. Collaborative research is needed to improve the diagnosis and understanding of the metabolic basis for these sometimes devastating disorders and to apply this knowledge to the more common killers of mankind.
 ...
PMID:When and how does one search for inborn errors of purine and pyrimidine metabolism? 803 39

The mechanism of allopurinol [4-hydroxypyrazolo(3,4-d)pyrimidine] transport into human erythrocytes was investigated with an inhibitor stop assay. Allopurinol transport could be resolved into two components: (1) a saturable system and (2) a non-saturable process, which most likely represents non-facilitated diffusion. Allopurinol transport had a Km of 268 mumol/L and a Vmax of 28 pmol/microL intracellular volume/sec; the non-saturable component was 0.0195/sec. Mutual inhibition studies showed that the competitive Ki values of hypoxanthine and adenine on allopurinol transport were 120 and 3 mumol/L, respectively. These Ki values as well as the IC50 values of 100-150 mumol/L for hypoxanthine and 3-10 mumol/L for adenine were similar to the corresponding transport Km values of these bases, which are 128 and 8 mumol/L, respectively. The Ki of allopurinol on hypoxanthine transport was 274 mumol/L and thus nearly identical to its Km. Thus in erythrocytes the uricostatic agent allopurinol is an alternative substrate for the purine transport system, but lacks the exceptional high affinity it has for xanthine oxidase. This could explain the paradoxical clinical side effect of allopurinol, namely that it can provoke an attack of gout. Theophylline, a methylated purine, inhibited allopurinol transport with an IC50 of 200-400 mumol/L. Oxypurinol [4,6-dihydroxypyrazolo(3,4-d)pyrimidine], the main metabolite of allopurinol, also inhibited allopurinol transport with an IC50 of 20-40 mumol/L. This is noteworthy, since allopurinol and oxypurinol do not share the same transport system in the kidney.
 ...
PMID:Allopurinol transport in human erythrocytes. 845 64

Phosphoribosylpyrophosphate(PRPP) synthetase(PRS) catalyzes the formation of PRPP from ATP and ribose-5-phosphate. PRPP is an important substrate for the synthesis of purine, pyrimidine, and pyridine dinucleotides. Human PRS exists as complex aggregates composed of the 34 kDa catalytic subunits(PRS1 and PRS2) and other 39 kDa component designated PRPP synthetase-associated protein (PAP39). PRS superactivity is an X-chromosome linked disorder, characterized by gout and uric acid overproduction resulting from accelerated synthesis of PRPP and purine nucleotides. Among the nearly 30 affected families identified to date, there are several families in which PRS superactivity with purine nucleotide feedback resistance are associated with neurodevelopmental abnormalities in addition to hyperuricemia and gout. Different nucleotide substitutions in the PRPS1 gene encoding PRS1 have identified in six unrelated affected families with purine nucleotide feedback-resistant PRS superactivity.
 ...
PMID:[PRPP synthetase superactivity]. 897 11

When to suspect and thus investigate for inborn errors of purine and pyrimidine metabolism is a dilemma for even the most observant investigator. Often parents of affected children, or a history involving siblings, can provide valuable clues. The recognition of new purine and pyrimidine disorders requires skill and serendipity. But even identifying known disorders can prove difficult, since they cover a broad spectrum of illnesses, can have more than one symptom, or lead to early death. This problem is compounded by the fact that they are relatively recently described and therefore often little known, either in the clinic or laboratory. The considerable heterogeneity in clinical expression within families as well as between families means that asymptomatic homozygotes may not be recognized or can present at any time from early childhood through adolescence up to their eighth decade. Consequently, all siblings should be screened. These disorders should be suspected in any case of unexplained anaemia, failure to thrive, susceptibility to recurrent infection, or neurological deficits with no current diagnosis, including autism, cerebral palsy, delayed development, deafness, epilepsy, self-mutilation, muscle weakness, the inability to walk or talk, and-unusual in children and adolescents-gout, sometimes with renal disease. Some disorders present with radiolucent kidney stones, in acute or chronic renal failure, alone or with any of the above, or as an intolerance/sensitivity to therapy (e.g. 5-fluorouracil in malignancies or azathioprine immunosuppression in organ transplantation), often with life-threatening consequences. Several parameters need to be evaluated to ensure correct diagnosis. Pitfalls which can mask diagnosis using only a single test are renal failure, blood transfusion, diet or drugs.
 ...
PMID:When to investigate for purine and pyrimidine disorders. Introduction and review of clinical and laboratory indications. 921 Nov 94

To investigate whether allopurinol and benzbromarone affect the concentration of uridine in plasma, allopurinol or benzbromarone were administered to patients with gout for 3 to 6 months. Allopurinol decreased the concentrations of uridine and uric acid in plasma and the urinary excretion of uric acid, but increased the plasma concentration and urinary excretion of oxypurines and orotidine. Benzbromarone decreased the concentration of uric acid in plasma and increased the excretion of uric acid in urine. However, it did not affect the plasma concentration of uridine or oxypurines or the urinary excretion of oxypurines or orotidine. These results suggest that orotidilytic decarboxylase was inhibited by allopurinol and oxypurinol ribonucleotides and/or that phosphoribosyl pyrophosphate (PRPP) was consumed by conversion from hypoxanthine, allopurinol, and oxypurinol to the respective ribonucleotides, resulting in a decrease in the de novo synthesis of pyrimidine leading to the decreased concentration of uridine in plasma. Furthermore, it was suggested that benzbromarone did not affect the de novo synthesis of pyrimidine or purine.
 ...
PMID:Effect of allopurinol and benzbromarone on the concentration of uridine in plasma. 943 46


1 2 3 Next >>