Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

After ischemic exercise tests, performed to detect glycogenoses or myoadenylate deaminase (EC 3.5.4.6) deficiency, the increases in serum lactate and ammonia usually are measured. Determination of hypoxanthine instead of ammonia can also be used to show myoadenylate deaminase deficiency, but HPLC of hypoxanthine is time-consuming. As a substitute, we developed an indirect enzymatic equilibrium method for hypoxanthine based on coupling the chromogenic system 3,5-dichloro-2-hydroxy-benzenesulfonic acid/4-aminophenazone with formation of hydrogen peroxide by xanthine oxidase (EC 1.1.3.22). The pH optimum is at 7.8 and the absorbance maximum at 510 nm. The calibration curve is linear from 0 to 100 mumol/L and the detection limit is 0.9 mumol/L. Analytical variability (CV) was 1.5% to 3.6% within-run, 4.5% to 8.5% between-run. The assay can be performed with a standard spectrophotometer or a centrifugal analyzer. The coefficient of correlation was 0.68 between hypoxanthine and ammonia increases in plasma from controls who performed the exercise test.
 ...
PMID:Rapid determination of the hypoxanthine increase in ischemic exercise tests. 272 Sep 97

McArdle disease (MD) is a metabolic myopathy due to myophosphorylase deficiency, which leads to a severe limitation in the rate of adenosine triphosphate (ATP) resynthesis. Compensatory flux through the myoadenylate deaminase > > xanthine oxidase pathway should result in higher oxidative stress in skeletal muscle; however, oxidative stress and nuclear factor erythroid 2-related factor 2 (Nrf2) mediated antioxidant response cascade in MD patients have not yet been examined. We show that MD patients have elevated muscle protein carbonyls and 4-hydroxynonenal (4-HNE) in comparison with healthy, age and activity matched controls (P < 0.05). Nuclear abundance of Nrf2 and Nrf2-antioxidant response element (ARE) binding was also higher in MD patients compared with controls (P < 0.05). The expressions of Nrf2 target genes were also higher in MD patients vs. controls. These observations suggest that MD patients experience elevated levels of oxidative stress, and that the Nrf2-mediated antioxidant response cascade is up-regulated in skeletal muscle to compensate.
 ...
PMID:Oxidative stress and Nrf2 signaling in McArdle disease. 2390 80