scholarly journals Role of hydrogen peroxide in the cytotoxicity of the xanthine/xanthine oxidase system

1988 ◽  
Vol 249 (2) ◽  
pp. 391-399 ◽  
Author(s):  
E M Link ◽  
P A Riley
Keyword(s):  
Hydrogen Peroxide ◽  
Xanthine Oxidase ◽  
Cytotoxic Effect ◽  
Oxidase System ◽  
H2o2 Decomposition ◽  
Enzymic Reaction ◽  
Single Oxygen ◽  
Phosphate Buffered Saline

1. The survival of mammalian epithelial cells exposed in vitro to the xanthine/xanthine oxidase system in phosphate-buffered saline (PBS) or serum-containing medium (SCMEM) was investigated. 2. The cytotoxic effect observed depended on the composition of the medium in which the enzymic reaction was carried out; a surviving fraction of 5 x 10(-5) was found for cells exposed in PBS and 5.2 x 10(-1) for those in SCMEM. 3. The cytotoxic product(s) formed by the xanthine/xanthine oxidase system was relatively stable in PBS; survival of cells incubated after completion of the enzymic reaction was always less than that found for cells exposed during the reaction in the same system. 4. Superoxide dismutase or mannitol present during the enzymic reaction did not inhibit the cytotoxic effect. 5. NaN3 (a single-oxygen quencher and a catalase inhibitor) added to the system in SCMEM caused a reduction in survival to the level observed for cells exposed to the enzymic reaction in PBS. 6. Catalase completely protected cells, but no protection was observed when both catalase and NaN3 were present in the reaction mixture. 7. A similar cytotoxic effect was produced when cells were treated with H2O2 alone. 8. The rate of H2O2 decomposition in medium was accelerated by the presence of serum, but this was completely inhibited by NaN3. 9. It is concluded that H2O2 is the major cytotoxic product formed by the xanthine/xanthine oxidase system.

The role of reactive oxygen metabolites in lymphocyte-mediated cytolysis

1987 ◽  
Vol 87 (3) ◽  
pp. 473-481
Author(s):  
C.J. Bishop ◽  
C.M. Rzepczyk ◽  
D. Stenzel ◽  
K. Anderson
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Xanthine Oxidase ◽  
Natural Killer ◽  
Reactive Oxygen ◽  
Tumour Cells ◽  
Reactive Oxygen Metabolites ◽  
Oxygen Metabolites

To examine the possible role of reactive oxygen metabolites in lymphocyte-mediated cytolysis, the morphology of cell death following the exposure of cells to reactive oxygen metabolites in vitro was compared with the morphology of cell-mediated killing in vitro of tumour cells by natural killer (NK) cells. Ultrastructural examination of human tumour cells that were dying following incubation for 60 min with the oxygen metabolite generating systems, xanthine-xanthine oxidase or t-butylhydroperoxide, showed that cell death in both instances was exclusively by necrosis. It was unclear which oxygen metabolites were involved in killing. Cell death was not decreased by the addition of superoxide dismutase, a scavenger of the superoxide anion, to the xanthine-xanthine oxidase mixture. Although the cells were not killed by incubation with 1 mM-hydrogen peroxide, the addition of catalase, a scavenger of hydrogen peroxide, to the xanthine-xanthine oxidase mixture significantly reduced cell death. The addition of scavengers for the hydroxyl radical to either the xanthine-xanthine oxidase mixture or t-butylhydroperoxide gave inconsistent protection. In contrast, tumour cell killing mediated by natural killer cells was by apoptosis, a morphologically distinct mode of cell death with a different basic mechanism, indicating that reactive oxygen metabolites are not directly involved in lymphocyte-mediated cytolysis.

Role of superoxide and hydrogen peroxide in cell lysis during irradiation in vitro of Ehrlich ascitic carcinoma cells in the presence of melanin

1985 ◽  
Vol 63 (4) ◽  
pp. 278-283 ◽  
Author(s):  
I. Aravindakshan Menon ◽  
Surujdeen Persad ◽  
Narendranath S. Ranadive ◽  
Herbert F. Haberman
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Lysis ◽  
Carcinoma Cells ◽  
Dark Reaction ◽  
Oxidase System ◽  
Red Hair ◽  
Ehrlich Ascitic Carcinoma ◽  
Per Se

The reactive species involved in the cell lysis during ultraviolet irradiation of Ehrlich ascitic carcinoma cells in the presence of red hair melanin (RHM) were investigated by determining 51Cr release from labeled cells. Cysteine at 1 mM in the presence of RHM increased the cell lysis during the incubation in the dark as well as during irradiation; this lysis was enhanced by superoxide dismutase (SOD). Catalase abolished the dark reaction and inhibited the cysteine-induced increase of cell lysis during irradiation. The cell lysis by the superoxide-generating xanthine oxidase system was not significantly increased by SOD, but was significantly decreased by nitroblue tetrazolium and completely abolished by catalase. The cell lysis induced by the supernatants obtained from the suspensions of RHM either irradiated alone or with cysteine was abolished by catalase. Sediments of irradiated RHM when incubated in the dark with the cells did not release 51Cr. Irradiation of the cells in the presence of the same sediments produced lysis which was not inhibited by catalase. These studies suggest that superoxide per se is not toxic to the cells, but the H2O2 formed by dismutation of superoxide produces cell lysis either directly or by generating ∙OH through Fenton-type reactions. A large part of the cell lysis seen during irradiation of cells in the presence of RHM is not due to H2O2, but may possibly be due to the melanin free radicals formed during irradiation.

The role of hydrogen peroxide in the in vitro cytotoxicity of 3-hydroxykynurenine

1990 ◽  
Vol 15 (11) ◽  
pp. 1101-1107 ◽  
Author(s):  
Clifford L. Eastman ◽  
Tomas R. Guilarte
Keyword(s):  
Hydrogen Peroxide ◽  
In Vitro Cytotoxicity

Hyperoxia and self- or neutrophil-generated O2 metabolites inactivate xanthine oxidase

1988 ◽  
Vol 65 (5) ◽  
pp. 2349-2353 ◽  
Author(s):  
L. S. Terada ◽  
C. J. Beehler ◽  
A. Banerjee ◽  
J. M. Brown ◽  
M. A. Grosso ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Xanthine Oxidase ◽  
Superoxide Anion ◽  
Hypochlorous Acid ◽  
Control Mechanism ◽  
Xanthine Dehydrogenase ◽  
Biological Processes ◽  
Lung Endothelial Cells ◽  
Cellular Control

Xanthine oxidase (XO) and xanthine dehydrogenase (XD) activities decreased in lungs isolated from rats and cultured lung endothelial cells that had been exposed to hyperoxia. Purified XO activity also decreased after addition of a variety of chemically generated O2 metabolite species (superoxide anion, hydrogen peroxide, hydroxyl radical, or hypochlorous acid), hypoxanthine, or stimulated neutrophils in vitro. XO inactivation by chemically, self-, or neutrophil-generated O2 metabolites was decreased by simultaneous addition of various O2 metabolite scavengers but not their inactive analogues. Since XO appears to contribute to a variety of biological processes and diseases, hyperoxia- or O2 metabolite-mediated decreases in XO activity may be an important cellular control mechanism.

scholarly journals Absorption of Hemoglobin Iron: The Role of Xanthine Oxidase in the Intestinal Heme-Splitting Reaction

Blood ◽  
1970 ◽  
Vol 35 (1) ◽  
pp. 94-103 ◽  
Author(s):  
R. BEN DAWSON ◽  
SHEILA RAFAL ◽  
LEWIS R. WEINTRAUB
Keyword(s):  
Epithelial Cell ◽  
Xanthine Oxidase ◽  
Intestinal Epithelial Cell ◽  
Oxidase Inhibitor ◽  
Small Intestinal Mucosa ◽  
Intestinal Epithelial ◽  
Sephadex Column ◽  
Xanthine Oxidase Inhibitor

Abstract Heme from ingested hemoglobin—59Fe is taken into the epithelial cell of the small intestinal mucosa of the dog and the 59Fe subsequently appears in the plasma bound to transferrin. A substance was demonstrated in homogenates of the mucosa which releases iron from a hemoglobin substrate in vitro. Thus: (1) The addition of catalase to the mucosal homogenate reduces the "heme-splitting" reaction. In contrast, sodium azide, a catalase inhibitor, potentiates the reaction. This suggests that a peroxide generating system participates in the "heme-splitting" reaction. (2) Xanthine oxidase, an enzyme present in the intestinal epithelial cell, produces H2O2 by oxidation of its substrate. The addition of allopurinol, a xanthine oxidase inhibitor, to the intestinal mucosal homogenate diminishes the "heme-splitting" reaction. (3) Fractionation of the 50,000 Gm. supernatant of the mucosal homogenate on a G-200 Sephadex column shows the "heme-splitting" activity to have the same elution volume as xanthine oxidase, indicating a similar molecular weight. (4) The addition of a mucosal homogenate to a xanthine substrate results in the production of uric acid. These data suggest that xanthine oxidase in the intestinal epithelial cell is important in the release of iron from absorbed heme. The enzyme mediates the "heme-splitting" reaction by the generation of peroxides which, in turn, oxidize the alpha-methene bridge of the heme ring releasing iron and forming biliverdin.

The formation of choleglobin and the role of catalase in the erythrocyte

1949 ◽  
Vol 136 (884) ◽  
pp. 435-448 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Catalase Activity ◽  
Acid Oxidase ◽  
Small Decrease ◽  
Amino Acid Oxidase ◽  
Oxidase System ◽  
Inverse Proportion

In haemolysates of non-nucleated erythrocytes there is an inverse proportion between catalase activity and rate of choleglobin formation on addition of ascorbic acid. In the intact erythrocytes catalase protects haemoglobin against oxidation and further destruction by the hydrogen peroxide generated by the D-amino-acid oxidase system or by physiological concentrations of ascorbic acid and glutathione. Acid destromatization of haemolyzed horse erythrocytes causes a small decrease in the catalase activity and an increased rate of inactivation of the remaining catalase by ascorbic acid. The liberation of copper from haemocuprein is quantitatively insufficient to explain the decreased stability of the catalase. Exposing duck oxyhaemoglobin, but not reduced haemoglobin, to a pH of 5⋅5 to 5⋅8, causes an alteration which is apparent from the increase of the rate of choleglobin formation. The mechanism of this alteration is discussed. It partly explains the 'stroma effect', at least in duck erythrocytes. In addition, in the latter, there is a true stroma effect. Choleglobin formation in the presence of ascorbic acid is accelerated by a variety of substances. Some of these perturb haemoglobin, while others increase the formation of hydrogen peroxide from ascorbic acid. The implications of our findings on the mechanism of choleglobin formation and on the role of catalase in the erythrocyte are discussed.

IL-10 deficiency increases superoxide and endothelial dysfunction during inflammation

2000 ◽  
Vol 279 (4) ◽  
pp. H1555-H1562 ◽  
Author(s):  
Carol A. Gunnett ◽  
Donald D. Heistad ◽  
Daniel J. Berg ◽  
Frank M. Faraci
Keyword(s):  
Endothelial Function ◽  
Xanthine Oxidase ◽  
Carotid Arteries ◽  
Interleukin 10 ◽  
Vehicle Injection ◽  
Endothelium Dependent Relaxation ◽  
Deficient Mice ◽  
Lps Treatment

Little is known about the role of interleukin-10 (IL-10), an anti-inflammatory cytokine, in blood vessels. We used IL-10-deficient mice (IL-10 −/−) to examine the hypothesis that IL-10 protects endothelial function after lipopolysaccharide (LPS) treatment. The responses of carotid arteries were studied in vitro 6 h after injection of a relatively low dose of LPS (10 μg ip). In IL-10 −/− mice, the maximum relaxation to ACh (3 μM) was 56 ± 6% (means ± SE) after LPS injection and 84 ± 4% after vehicle injection ( P < 0.05). Thus endothelium-dependent relaxation was impaired in carotid arteries from IL-10 −/− mice after LPS injection. In contrast, this dose of LPS did not alter relaxation to ACh in vessels from wild-type (IL-10 +/+) mice. Relaxation to nitroprusside and papaverine was similar in arteries from both IL-10 −/− and IL-10 +/+ mice after vehicle or LPS injection. Because inflammation is associated with increased levels of reactive oxygen species, we also tested the hypothesis that superoxide contributes to the impairment of endothelial function by LPS in the absence of IL-10. Results using confocal microscopy and hydroethidine indicated that levels of superoxide are elevated in carotid arteries from IL-10 −/− mice compared with IL-10 +/+ mice after LPS injection. The impaired relaxation of arteries from IL-10 −/− mice after LPS injection was restored to normal by polyethylene glycol-suspended superoxide dismutase (50 U/ml) or allopurinol (1 mM), an inhibitor of xanthine oxidase. These data provide direct evidence that IL-10 protects endothelial function after an acute inflammatory stimulus by limiting local increases in superoxide. The source of superoxide in this model may be xanthine oxidase.

Role of cementoenamel junction on the radicular penetration of 30% hydrogen peroxide during intracoronal bleaching in vitro

1996 ◽  
Vol 12 (3) ◽  
pp. 146-150 ◽  
Author(s):  
E. Koulaouzidou ◽  
T. Lambrianidis ◽  
P. Beltes ◽  
K. Lyroudia ◽  
C. Papadopoulos
Keyword(s):  
Hydrogen Peroxide

scholarly journals Cleavage of folates during ethanol metabolism. Role of acetaldehyde/xanthine oxidase-generated superoxide

1989 ◽  
Vol 257 (1) ◽  
pp. 277-280 ◽  
Author(s):  
S Shaw ◽  
E Jayatilleke ◽  
V Herbert ◽  
N Colman
Keyword(s):  
Superoxide Dismutase ◽  
Xanthine Oxidase ◽  
Folinic Acid ◽  
Folate Deficiency ◽  
Ethanol Metabolism

Although folate deficiency and increased requirements for folate are observed in most alcoholics, the possibility that acetaldehyde generated from ethanol metabolism may increase folate catabolism has not been previously demonstrated. Folate cleavage was studied in vitro during the metabolism of acetaldehyde by xanthine oxidase, measured as the production of p-aminobenzoylglutamate from folate using h.p.l.c. Acetaldehyde/xanthine oxidase generated superoxide, which cleaved folates (5-methyltetrahydrofolate greater than folinic acid greater than folate) and was inhibited by superoxide dismutase. Cleavage was increased by addition of ferritin and inhibited by desferrioxamine (a tight chelator of iron), suggesting the importance of catalytic iron. Superoxide generated from the metabolism of ethanol to acetaldehyde in the presence of xanthine oxidase in vivo may contribute to the severity of folate deficiency in the alcoholic.

In vitro toxicity of hydrogen peroxide against normal vs. tumor rat hepatocytes: Role of catalase and of the glutathione redox cycle

Hepatology ◽  
1988 ◽  
Vol 8 (6) ◽  
pp. 1673-1678 ◽  
Author(s):  
Philippe Mavier ◽  
Bernard Guigui ◽  
Anne-Marie Preaux ◽  
Jean Rosenbaum ◽  
Marie-Claude Lescs ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rat Hepatocytes ◽  
In Vitro Toxicity ◽  
Redox Cycle ◽  
Glutathione Redox Cycle ◽  
Glutathione Redox
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