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

In the present study, the ocular inflammatory response to intravitreally injected endotoxin and xanthine oxidase was studied and the cellular response of the anterior and posterior segments was contrasted. There was a clear dose response relationship to both compounds in aqueous humor protein concentration and aqueous and vitreous humor white cell number. Xanthine oxidase and low doses of endotoxin (0.25 and 1.0 ng) produce a mainly mononuclear response in the anterior segment. Higher doses of endotoxin (10 and 100 ng) produced a predominantly neutrophilic response. Cellular infiltration into the posterior segment differed qualitatively and quantitatively from the anterior segment in response to the same stimuli. Myeloperoxidase (MPO) activity (a marker for neutrophils) of the iris-ciliary body was increased only in those eyes with a large neutrophilic response and thus is not recommended for use as a definitive index of the ocular inflammatory response, but may be a useful adjunct for such studies.
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PMID:Cellular response to intravitreal injection of endotoxin and xanthine oxidase in rabbits. 152 15

Xanthine oxidase (XaO) was injected into the anterior chamber of rabbit eyes by a closed circuit perfusion system. Doses of 1.5 milliunits (mU) or greater produced a maximal leucocyte accumulation after 4 hr, with an initial elevation of ocular pressure in the first 15 min. Similar experiments on rats with intravitreal injections of 0.1-1.5 mU of XaO resulted in a significant accumulation of leucocytes after 5 hr which, at the highest dose of XaO, was partly due to traces of bacterial endotoxin in the XaO. However, in endotoxin-desensitized rats the response to 1.5 milliunits XaO was seven-fold greater than the response to endotoxin alone. Simultaneous administration of xanthine (Xa) substrate with XaO was not required to elicit cell infiltration into the anterior chamber. Dialyzed enzyme was also effective but boiling abolished the response. Addition of XaO to rabbit aqueous humor in vitro decreased the ascorbate content, consistent with the generation of superoxide from an endogenous substrate. The results suggest that enzymatically active XaO, which can cause intraocular generation of superoxide from an XaO substrate present in aqueous humor, initiates the chemotactic response. A chemotactic agent may be generated from superoxide reacting with endogenous precursors in aqueous humor or by selective activation of the lipoxygenase pathway of arachidonic acid metabolism in adjacent tissues.
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PMID:Ocular responses to superoxide generated by intraocular injection of xanthine oxidase. 299 48

The potential of ascorbic acid acting against the toxic effects of active oxygen species on the lens has been studied. The active species of oxygen were generated by the action of xanthine oxidase on xanthine. Rat lenses incubated in medium containing xanthine and xanthine oxidase were physiologically damaged, as evidenced by the decrease in the ability of the tissue to accumulate rubidium or alpha-aminoisobutyric acid against a concentration gradient. The pressure of ascorbate in the medium protected against the tissue damage. One of the functions of high ascorbate in the aqueous humor of many primates including human beings may, therefore, be to protect the lens and other surrounding tissues against the toxic effects of active oxygen derivatives produced in situ under ambient, as well as under photochemical, conditions.
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PMID:In vitro damage to rat lens by xanthine-xanthine oxidase: protection by ascorbate. 381 25