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)

The distal articular surface of the femur was surgically removed in 57 dogs. Succinate dehydrogenase and cytochrome oxidase activities were assayed on postoperative days 7, 20, 26, 33 and 70 in the regenerating, chondrifying articular surface and in the granulation tissue adhering to the capsule. In the 70-day samples, the cyanide-induced inhibition of oxygen consumption was determined and enzyme histochemical reactions (cytochrome oxidase, monoamine oxidase, xanthine oxidase, peroxidase and "catalase") were performed. The succinate dehydrogenase activity was the highest in the early postoperative stage in both tissues. This was followed by a definite decrease and a subsequent significant increase in activity when chondrification took place. Measurement of cytochrome oxidase activity could not reveal any convincing result, presumably because of the properties of the tissues studied. The oxygen consumption by the chondrifying articular surface at 70 days was inhibited to about 50% by cyanide, and about 90% inhibition was observed in the tissue adhering to the capsule. The cells of the regenerating articular surface possess cytochrome oxidase and a cyanide- (and sodium azide-) resistant oxidase activity. The enzyme activity of the cartilaginous islets exceeded that of their connective tissue environment. The cytochrome oxidase activity increased in the cells during cartilage differentiation. Presumably, some further cyanide-sensitive and cyanide-resistant oxidases are present in chondroblasts and young chondrocytes.
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PMID:Studies on cartilage formation. XXII. Investigations of certain oxidative metabolic processes in regenerating articular cartilage. 626 95

The effects of dapsone on polymorphonuclear leukocyte functions and lymphocyte mitogen-induced transformation were assessed in vitro and in vivo in normal individuals and in newly diagnosed untreated patients with lepromatous leprosy. The effects of dapsone on the cell-free generation of superoxide by the xanthine: xanthine oxidase system and iodination of bovine serum albumin by horseradish peroxidase were also investigated. In normal individuals dapsone mediated stimulation of polymorphonuclear leukocyte migration in vitro and vivo. Dapsone had no effect on postphagocytic hexose monophosphate shunt activity in vivo. Similar effects were found in patients with lepromatous leprosy. Dapsone also decreased the inhibitory activity of serum from patients with lepromatous leprosy on normal polymorphonuclear leukocyte migration in vitro. Progressive loss of serum-mediated inhibition of migration was observed after ingestion of dapsone by the patients. Further experiments showed that stimulation of polymorphonuclear leukocyte motility was related to inhibition of lymphocyte transformation at high concentrations in vitro, but had slight stimulatory activity on phytohemagglutinin-induced transformation in controls and patients in vivo.
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PMID:In vitro and in vivo effects of dapsone on neutrophil and lymphocyte functions in normal individuals and patients with lepromatous leprosy. 626 48

To explore the susceptibility of the extracellular protozoan, Entamoeba histolytica, to toxic oxygen intermediates, trophozoites were exposed to fluxes of O2, H2O2, and OH. generated enzymatically by the glucose oxidase and xanthine oxidase reactions. HM-1 trophozoites were resistant to O2, but were readily killed by H2O2 alone. OH. and 1O2 were not required for effective amebicidal activity. The addition of peroxidase and halide enhanced trophozoite killing by H2O2. Sonicates of amebae contained virtually no catalase and little glutathione peroxidase activity which may contribute to susceptibility to H2O2. Coupled with our previous studies with Toxoplasma gondii and Leishmania spp. these observations indicate that there is a broad spectrum of susceptibility of intra- and extracellular pathogenic protozoa to killing by oxygen intermediates.
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PMID:Susceptibility of Entamoeba histolytica to oxygen intermediates. 627 8

We describe a one-step kinetic method for the determination of 5'-nucleotidase (EC 3.1.3.5). Inosine is formed by the hydrolysis of inosine 5'-monophosphate which is catalyzed by seric 5'-nucleotidase, and then is converted to hypoxanthine by nucleoside phosphorylase. Two moles of hydrogen peroxide are formed for each mole of hypoxanthine oxidized to urate by xanthine oxidase. The rate formation of hydrogen peroxide is monitored at 510 nm using the oxidation of the chromogenic system 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone in the presence of peroxidase. beta-Glycerophosphate inhibits the unspecific cleavage of the substrate by alkaline phosphatases. Inorganic phosphate is added to improve the reagent stability, and ferrocyanide to reduce bilirubin interference. Automation of the technique requiring 20 microliter of serum on a centrifugal analyzer is also described.
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PMID:A one-step determination of serum 5'-nucleotidase using a centrifugal analyzer. 627 35

1. Iron-dependent free radical damage to DNA and deoxyribose results in the formation of thiobarbituric acid (TBA) reactive intermediates. 2. These intermediates have been compared chromatographically and spectrophotometrically after incubation with the enzymes xanthine oxidase and peroxidase. 3. Loss of TBA-reactivity occurred in the bleomycin-iron(II) derived products incubated with xanthine oxidase and in a standard solution of sodium malondialdehyde incubated with peroxidase.
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PMID:Iron-dependent free radical damage to DNA and deoxyribose. Separation of TBA-reactive intermediates. 629 Feb 80

Effects of protizinic acid (PRT) on prostaglandins (PG) and the production of oxygen radicals were compared with those of other non-steroidal anti-inflammatory agents. Oral administration of 30 mg/kg of PRT, indomethacin (IM), or ibuprofen (IB) significantly inhibited arachidonic acid-induced erythema in guinea pigs. Although 30 mg/kg of PRT significantly inhibited PGE2-induced erythema, IM and IB did not significantly inhibit it. PRT inhibited phospholipase A2 (PLA2) activity, and the IC50 value was 2.1 X 10-4 M. On the other hand, IM and IB exerted no effect on the PLA2 activity at 3 X 10-4 M. These results suggest that PRT possesses a broader pharmacological activity on the PG system than IM and IB. As for effects on the production of oxygen radicals, in order of relative inhibitory potency was PRT greater than metiazinic acid (MA) = IM greater than IB = phenylbutazone (PB) in the xanthine oxidase assay, PB great than IM greater than PRT greater than MA = IB in the rabbit neutrophil myeloperoxidase assay, and IM greater than PB greater than PRT greater than MA greater than IB in the guinea pig macrophage assay. In the rabbit neutrophil and aggregated IgG-bound micropore filter assay, the order was PRT greater than MA greater than PB greater than IM = IB. Thus, the inhibitory effects of PRT was verified in all experiments on the production of oxygen radicals in contrast to IB. In particular, it could be especially meaningful that PRT showed the most potent activity in the aggregated IgG-bound micropore filter assay which has been reported to be a good model for studying the pathogenesis of inflammatory diseases believed to be caused by immune complexes.
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PMID:[Effects of protizinic acid on the prostaglandins system and the production of oxygen radicals]. 629 Mar 56

Our previous studies established that human neutrophils could damage and probably kill hyphae of Aspergillus fumigatus and Rhizopus oryzae in vitro, primarily by oxygen-dependent mechanisms active at the cell surface. These studies were extended, again quantitating hyphal damage by reduction in uptake of (14)C-labeled uracil or glutamine. Neither A. fumigatus nor R. oryzae hyphae were damaged by neutrophils from patients with chronic granulomatous disease, confirming the importance of oxidative mechanisms in damage to hyphae. In contrast, neutrophils from one patient with hereditary myeloperoxidase deficiency damaged R. oryzae but not A. fumigatus hyphae. Cell-free, in vitro systems were then used to help determine the relative importance of several potentially fungicidal products of neutrophils. Both A. fumigatus and R. oryzae hyphae were damaged by the myeloperoxidase-hydrogen peroxide-halide system either with reagent hydrogen peroxide or enzymatic systems for generating hydrogen peroxide (glucose oxidase with glucose, or xanthine oxidase with either hypoxanthine or acetaldehyde). Iodide with or without chloride supported the reaction, but damage was less with chloride alone as the halide cofactor. Hydrogen peroxide alone damaged hyphae only in concentrations >/=1 mM, but 0.01 mM hypochlorous acid, a potential product of the myeloperoxidase system, significantly damaged R. oryzae hyphae (a 1 mM concentration was required for significant damage to A. fumigatus hyphae). Damage to hyphae by the myeloperoxidase system was inhibited by azide, cyanide, catalase, histidine, and tryptophan, but not by superoxide dismutase, dimethyl sulfoxide, or mannitol. Photoactivation of the dye rose bengal resulted in hyphal damage which was inhibited by histidine, tryptophan, and 1,4-diazobicyclo(2,2,2)octane. Lysates of neutrophils or separated neutrophil granules did not affect A. fumigatus hyphae, but did damage R. oryzae hyphae. Similarly, three preparations of cationic proteins purified from human neutrophil granules were more active in damaging R. oryzae than A. fumigatus hyphae. This damage, as with the separated granules and whole cell lysates, was inhibited by the polyanion heparin. Damage to R. oryzae hyphae by neutrophil cationic proteins was enhanced by activity of the complete myeloperoxidase system or by hydrogen peroxide alone in subinhibitory concentrations. These data support the importance of oxidative products in general and the myeloperoxidase system in particular in damage to hyphae by neutrophils. Cationic proteins may also contribute significantly to neutrophil-mediated damage to R. oryzae hyphae.
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PMID:Damage to Aspergillus fumigatus and Rhizopus oryzae hyphae by oxidative and nonoxidative microbicidal products of human neutrophils in vitro. 629 3

Legionella pneumophila was susceptible to the antimicrobial action of oxygen metabolites generated by both the myeloperoxidase-H(2)O(2)-halide and the xanthine oxidase systems.
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PMID:Effect of oxygen-dependent antimicrobial systems on Legionella pneumophila. 629 60

Chemotactic factors, which are important in attracting neutrophils to inflammatory sites, have also been shown to stimulate oxidative metabolism, resulting in increased chemiluminescence and release of superoxide anion (O2-). We observed a unique bimodal chemiluminescence pattern upon stimulation with either the complement-derived factor C5a or formyl-methionyl-leucyl-phenylalanine. A sharp peak of activity occurred within 1 to 2 min, and a second more extended peak was seen between 3 and 6 min. Enhancement of both peaks occurred when the cells were pretreated with cytochalasin B. Expression of both peaks was found to be related to cell density, and expression of the second peak was not dependent upon extracellular metabolites released during the first peak. Cells preincubated in luminol and then thoroughly washed responded with only a single peak coincident with the second peak. Together these findings indicate that the first peak is extracellular in origin, whereas the second peak is cell associated. Studies with scavengers of oxygen intermediates and inhibitors of myeloperoxidase for the oxidation of luminol, which may occur in part through the formation of HOCl as well as through a non-HOCl-mediated mechanism. Evidence for a non-HOCl-mediated mechanism comes from experiments in which luminol, myeloperoxidase, and O2- generated by xanthine-xanthine oxidase produce luminescence in the absence of chloride ion. These studies provide further insight into the sequence of events which occur during the stimulation of neutrophils with chemotactic factors and the nature of neutrophil chemiluminescence.
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PMID:Analysis of the bimodal chemiluminescence pattern stimulated in human neutrophils by chemotactic factors. 630 58

The ability of human polymorphonuclear cells (PMN) to take up and destroy intracellular forms of Trypanosoma cruzi (AMA) was investigated as a part of our efforts to elucidate the mechanisms of clearing of these parasites from infected tissues. PMN were found to take up AMA and destroyed parasites were seen after 30 min of cell-parasite interaction. Under our experimental conditions, the rate of uptake of AMA by PMN was maximal during the first 30 min of interaction. AMA were found to be located and destroyed inside the phagolysosomal vacuoles of PMN. The parasite was never found outside these vacuoles despite electron microscopic examination of numerous preparations derived from several experiments. Intracellular destruction of AMA by PMN was visible by electron microscopy and could be monitored by measuring the release of 3H-labeled substances by PMN that had ingested radiolabeled AMA. PMN incubated after removal of unbound parasites destroyed over 90% of the ingested organisms within 3 hr and close to 99% after 12 hr. In cellfree systems, 44% of the AMA were destroyed in the presence of 10(-4) M H2O2 and all of the parasites died at 10(-3) M. Addition of lactoperoxidase and iodide resulted in 100% killing at 10(-5) M H2O2. These mechanisms appeared to be involved in the lysis of AMA by PMN since both H2O2 and peroxidase activity were demonstrated to be present in PMN vacuoles containing the parasite. Addition of NaN3, KCN (inhibitors of myeloperoxidase activity) or catalase (to decompose H2O2) caused a marked reduction in the extent of AMA killing by PMN. Xanthine oxidase was toxic for the AMA in the presence of acetaldehyde. This microbicidal activity was inhibited by catalase but not by heat-inactivated catalase or by reagents that scavenge the intermediate products of reduction of molecular oxygen, O - X 2, X OH, and 1O2. These results suggest that PMN have the potential of clearing AMA liberated in infected chagasic tissues and that parasite killing within the phagolysosomal vacuoles is mediated by myeloperoxidase activity and H2O2.
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PMID:Role of polymorphonuclear cells in Chagas' disease. I. Uptake and mechanisms of destruction of intracellular (amastigote) forms of Trypanosoma cruzi by human neutrophils. 630 64


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