Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.17.3.2 (xanthine oxidase)
8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preexposure to hypoxia increased survival and lung reduced glutathione-to-oxidized glutathione ratios (GSH/GSSG) and decreased pleural effusions in rats subsequently exposed to continuous hyperoxia. In addition, lungs from hypoxia-preexposed rats developed less acute edematous injury (decreased lung weight gains and lung lavage albumin concentrations) than lungs from normoxia-preexposed rats when isolated and perfused with hydrogen peroxide (H2O2) generated by xanthine oxidase (XO) or glucose oxidase (GO). In contrast, when perfused with elastase or exposed to a hydrostatic left atrial pressure challenge, lungs isolated from hypoxia-preexposed rats developed the same acute edematous injury as lungs from normoxia-preexposed rats. The mechanism by which hypoxia preexposure conferred protection against H2O2 appeared to depend on hexose monophosphate shunt (HMPS)-dependent increases in lung glutathione redox cycle activity. First, before perfusion with GO, lungs from hypoxia-preexposed rats had increased glutathione peroxidase and glucose 6-phosphate dehydrogenase (but not catalase or glutathione reductase) activities compared with lungs from normoxia-preexposed rats. Second, after perfusion with GO, lungs from hypoxia-preexposed rats had increased H2O2 reducing equivalents, as reflected by increased GSH/GSSG and NADPH/NADPH+, compared with lungs from normoxia-preexposed rats. Third, pretreatment of rats with an HMPS inhibitor, (6-aminonicotinamide) or a glutathione reductase inhibitor, [1,3-bis(2-chloroethyl)-1-nitrosourea] prevented hypoxia-conferred protection against H2O2-mediated acute edematous injury in isolated lungs. These findings suggest that increased detoxification of H2O2 by glutathione redox cycle and HMPS-dependent mechanisms contributes to tolerance to hyperoxia and resistance to H2O2 of lungs from hypoxia-preexposed rats.
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PMID:Hypoxia increases glutathione redox cycle and protects rat lungs against oxidants. 321 62

The effect of tris-(2-chloroethyl)-amine (HN-3) on RNA and DNA was investigated spectrophotometrically. The shift in the absorbance spectrum caused by the addition of HN-3 was used to test a variety of compounds for their ability to inhibit RNA alkylation. The effect of HN-3 on the activity of several enzymes was also investigated. The activities of ribonuclease A, desoxyribonuclease I, acetylcholinesterase, diaphorase, glutathione reductase, adenosine desaminase, glyoxalase I, 3-hydroxyacyl-CoA-dehydrogenase, xanthine oxidase, glucose-6-phosphate dehydrogenase, hexokinase and the microsomal N-oxygenation of aniline were not changed by HN-3, whereas the activity of cytochrome-c-reductase exhibited a dose dependent diminution in the presence HN-3. Of 105 compounds tested only 14, namely, sodium thiosulfate, dithioxanthine, thiosalicylic acid, 1,2,4-triazole-5-thiol, 2-thiocytosine, 2-thiohistadine, 2,3-dithiosuccinic acid, thioglycolic acid, 3-mercapto-D-valine,6-amino-2-thiouracil, thionicotine amide, dithiothreitol, sodium sulfite, and ergothioneine prevented the alkylation of RNA. All of them also reacted with HN-3 in absence of RNA. No correlation was found between the reaction constant of the reaction compound:HN-3 in the absence of RNA and the concentration of the compound which inhibited RNA alkylation by 50%. The compounds which were effective in vitro were also tested in mice for their ability to reduce HN-3 toxicity in vivo. Only sodium thiosulfate, d-penicillamine, and dithiosuccinic acid were effective. A 3.9fold increase in the LD50 of HN-3 was achieved in mice treated with sodium thiosulfate 3330 mg/kg i.p., a 1.7fold with 2125 mg dithiosuccinic acid/kg, and a 2fold increase with 2500 mg/kg d-penicillamine. The compound tested was injected i.p. 0.5 to 1 min after the s.c. injection of HN-3.
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PMID:Effect of various compounds on the reaction of tris-(2-chloroethyl)amine with ribonucleic acid in vitro and on its toxicity in mice. 617 33

In Glossina morsitans morsitans Westwood the locus for glucose-6-phosphate dehydrogenase, G6pd, was found to be in linkage group I, approximately 35 to 42 map units to the left of ocra, the locus for body color. The locus for midgut alkaline phosphatase, Alkph, was found to be in linkage group II, within 0.41 map units of the locus for xanthine oxidase, Xo. The distance from Xo to the locus for aldehyde oxidase, Ao, was confirmed to be about 42 map units. No evidence for genetical recombination was found in male G. m. morsitans.
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PMID:Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). VII. Location of G6pd in linkage group I, and Alkph in linkage group II. 634 Aug 5

Erythrocytes from young and old rats were separated into four age fractions by density-gradient centrifugation. The specific activities per cell were determined for glucose-6-phosphate dehydrogenase (EC 1.1.1.49), glutathione peroxidase (EC 1.11.1.9), glutathione reductase (EC 1.6.4.2) and catalase (EC 1.11.1.6). Decreased specific activities were observed with increasing cell age for all four enzymes in both young and old animals. In addition, significant differences in the activities of these enzymes were observed between cells of the same age fraction from young and old donors. Susceptibility of fractionated erythrocytes to oxidative attack in vitro generated by incubation with xanthine/xanthine oxidase increased with both cell and animal age. The amount of membrane-lipid peroxidation also increased with cell and animal aging, as measured by both thiobarbituric acid and fluorescent chromolipid assays. Increases of 2-3-fold in the contents of lipid peroxides were observed between the youngest and oldest age fractions of young rats. Lipid peroxide contents in young cells of old animals were equal to those in old erythrocytes from young rats and increased by 30% with cell aging in the old donors. These results suggest that the extent of enzymic protection against oxidative and peroxidative damage decreases with erythrocyte aging. More importantly, enzymic protection in cells of old rats is considerably decreased already in the early stages of their lifespan.
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PMID:Decreased enzymic protection and increased sensitivity to oxidative damage in erythrocytes as a function of cell and donor aging. 671 29

The reactive oxygen species, hydrogen peroxide (H2O2) and superoxide anion (O2o-), were generated with a xanthine-xanthine oxidase system and their effect on human sperm function was studied. The action of reactive oxygen species on selected human spermatozoa resulted in a decreased capacity for ionophore-induced acrosome reaction, a decrease in sperm motility, an increase in the concentration of lipid hydroperoxides and a loss of membrane polyunsaturated fatty acids. H2O2 was the key intermediate of the deleterious effects exerted by the xanthine and xanthine oxidase. Among these parameters, the acrosome reaction appeared most susceptible to the reactive oxygen species generated by the xanthine-xanthine oxidase system, and was decreased without sperm motility being affected. Treatment with H2O2 was shown to inactivate several enzymatic activities involved in the antioxidant defence of spermatozoa: glutathione peroxidase, superoxide dismutase and glucose-6-phosphate dehydrogenase. H2O2 and O2o- were shown to be involved in the lipid alterations triggered by the xanthine-xanthine oxidase system. Singlet oxygen is proposed to intervene in the lipoperoxidation process. The inefficacy of mannitol in protecting spermatozoa suggests that hydroxyl radicals were not produced in the extracellular medium.
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PMID:Reactive oxygen species, lipid peroxidation and enzymatic defence systems in human spermatozoa. 770 95

Oxygen radicals have been proposed to be involved in the induction of liver cell damage during reperfusion after ischemia. The role of xanthine oxidase in this process and the potential of the antioxidant system have been studied in a model of in vivo ischemia of rat liver followed by 1 h reperfusion by the use of enzyme histochemistry. Based on decreased lactate dehydrogenase activity in certain areas of liver parenchyma, cell damage could already be detected at 1 h reperfusion after ischemia. Incubations performed on serial sections showed that the same areas contained decreased activities of xanthine oxidoreductase, xanthine oxidase, catalase and glucose-6-phosphate dehydrogenase. Some individual cells in the undamaged liver parenchyma expressed a very high glucose-6-phosphate dehydrogenase, which suggests that these cells have a good defence against oxidative stress. It is concluded that oxygen radicals derived from xanthine oxidase do not play a decisive role in the induction of cell damage immediately at reperfusion after ischemia. However, it cannot be excluded that xanthine oxidase present in the blood stream can give rise to the development of additional damage later on.
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PMID:The role of xanthine oxidase in ischemia/reperfusion damage of rat liver. 775 31

We have previously reported that hyberbaric oxygen (HBO) improved the survival rate of experimental free flaps. The purpose of this study was to evaluate the effects of combined hypothermia and HBO administered during storage on free flaps and on the xanthine oxidase system in rats. Epigastric skin flaps were stored cold for 48 and 72 hours either in room air or under HBO (2.9 atmospheres absolute, 100% oxygen) before free flap transfer. The success rates of free flaps were 80% (8/10) after 48 hours and 20% (2/10) after 72 hours of cold storage in room air. HBO produced no effect after 48 hours but significantly increased the success rate to 70% (7/10) after 72 hours of cold storage. Tissue hypoxanthine (plus xanthine) levels increased to 210% of normal after 48 hours of cold storage in room air and to 176% in HBO. Elevated hypoxanthine levels returned toward normal by 72 hours of cold storage in room air, while the increased levels remained under HBO. Xanthine oxidase activities significantly increased by 60 to 80% during 72 hours of room air storage. HBO treatment inhibited xanthine oxidase activity to 48% of normal by 72 hours of storage. Free flaps exhibited no significant alterations in GR and G6PDH activity after 48 hours of cold storage in room air or HBO. After 72 hours of cold storage, the room air control displayed a trend of decreasing GR activity and a significant 20% decrease in G6PDH activity, while HBO groups showed no significant alterations in both GR and G6PDH activity compared to normal. Protection of the antioxidative enzymes by hypothermia and inhibition of the xanthine oxidase activity by HBO appear to be one of the mechanisms of improved skin flap survival in free flaps.
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PMID:Effects of combined cold and hyperbaric oxygen storage on free flap survival. 784 94

Two large colonies, originating from allopatric populations of Glossina pallidipes Austen, in the Shimba Hills and Nguruman, Kenya, which differ biologically and with respect to vectorial competence, were compared at fourteen enzyme loci using polyacrylamide gel electrophoresis. The colonies had similar levels of genetic diversity with approximately half of the loci being polymorphic, an average of 1.6-1.7 alleles per locus, and a mean heterozygosity per locus of approximately 18.4%. However, the colonies differed significantly in allele frequencies at the loci for phosphoglucomutase, glucose-6-phosphate dehydrogenase, xanthine oxidase, octanol dehydrogenase and phosphoglucose isomerase. The results were compared with earlier studies on this species and no evidence was found for selection of specific alleles during establishment or maintenance of colonies of G. pallidipes, nor were specific chromosomes, or marker genes, associated with the biological differences between the two colonies.
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PMID:Genetics of two colonies of Glossina pallidipes originating from allopatric populations in Kenya. 802 20

Metastases in rat liver were generated experimentally by intraportal injection of colon cancer cells to investigate the effects of cancerous growth on the metabolism of surrounding liver tissue. Maximum activities (capacity) of glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, lactate dehydrogenase, succinate dehydrogenase, alkaline phosphatase, 5'-nucleotidase, xanthine oxidoreductase, purine nucleoside phosphorylase and adenosine triphosphatase have been determined. Two types of metastases were found, a small type surrounded by stroma and a larger type in direct contact with hepatocytes. Both types affected the adjacent tissue in a similar way suggesting that the interactions were not mediated by stroma. High capacity of the degradation pathway of extracellular purines released from dead cells of either tumours or host tissue was found in stroma and sinusoidal cells. Metastases induced both an increase in the number of Kupffer cells and proliferation of hepatocytes. The distribution pattern in the liver lobulus of most enzymes investigated did not change distinctly. However, activity of alkaline phosphatase, succinate dehydrogenase and phosphogluconate dehydrogenase was increased in hepatocytes directly surrounding metastases. These data imply that the overall metabolic zonation in liver lobuli is not dramatically disturbed by the presence of cancer cells despite the fact that various metabolic processes in liver cells are affected.
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PMID:Experimentally induced colon cancer metastases in rat liver increase the proliferation rate and capacity for purine catabolism in liver cells. 822 8

Freeze-substituted rat liver embedded in glycol methacrylate (GMA) has been used to demonstrate the activities of several enzymes. The following enzymes could be detected in GMA-sections by the indicated histochemical procedure(s): 5'-nucleotidase (lead salt, cerium-diaminobenzidine), alkaline phosphatase (indoxyl-tetrazolium salt), catalase (diaminobenzidine), acid phosphatase (diazonium salt), lactate dehydrogenase (tetrazolium salt) and glutamate dehydrogenase (tetrazolium salt). The activities of all these enzymes were dramatically decreased compared with the activities demonstrated in unfixed cryostat sections, with the exception of catalase. The activities of the following enzymes could not be detected in GMA-sections: glucose-6-phosphate dehydrogenase (tetrazolium salt), xanthine oxidoreductase (tetrazolium salt), D-amino acid oxidase (cerium-diaminobenzidine-cobalt-hydrogen peroxide) and glucose-6-phosphatase (cerium-diaminobenzidine). The possible role of restricted penetration of reagents into the resin was studied by measuring cytophotometrically the enzyme activities in GMA-sections of 3 and 6 microns in thickness. For all the enzymes that could be detected, the 6 microns:3 microns ratio varied from 1.4 to 2.7. An eventual retarded penetration of reagents into the resin was investigated by measuring cytophotometrically the amount of final reaction product during incubation for acid phosphatase and glutamate dehydrogenase activities. In both cases linear relationships without a lag phase were found for the specific enzyme activities with incubation time. Chemical denaturation of proteins or masking of active sites in proteins due to embedding in the resin monomer may be considered to be the main cause of decreased enzyme activities.
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PMID:Quantitative aspects of enzyme histochemistry on sections of freeze-substituted glycol methacrylate-embedded rat liver. 827 44


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