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At least 19 recordsLinked to original sources
PubMed1978

Superoxide dismutase of the eye: relative functions of superoxide dismutase and catalase in protecting the ocular lens from oxidative damage.

1. Activities of superoxide dismutase (superoxide: superoxide oxidoreductase, EC 1.15.1.1) have been estimated in eye tissues. In rabbit eye, superoxide dismutase is present in corneal epithelium, corneal endothelium, lens, iris, ciliary body and retina. In lens the activity is in capsule epithelium. 2. Copper chelator diethyldithiocarbamate inhibited lens superoxide dismutase in vitro and in vivo in rabbit. 3. H2O2 caused inhibition of superoxide dismutase activity of lens extract, and this inhibition was potentiated by the catalase inhibitor 3-amino-1H-1,2,4-triazole (3-aminotriazole) or NaN3. 3-Aminotriazole or NaN3 had no effect on lens superoxide dismutase. Thus endogenous catalase of lens affords protection to the lens superoxide dismutase from inactivation by H2O2. 4. In rabbit having early cataract (vacuolar stage) induced by feeding-3-aminotriazole, there was a decrease in superoxide dismutase of lens, a fall in ascorbic acid of ocular humors and lens, and a 2--3-Fold increase in H2O2 of aqueous humor and vitreous humor. We conclude that catalase of eye affords protection to the lens from H2O2 and it also protects superoxide dismutase of lens from inactivation by H2O2. Superoxide dismutase, in turn, protects the lens from the superoxide radical, O2.-. It is likely that inhibition of these enzymes may lead to production of the highly reactive oxidant, the hydroxyl radical, under pathological conditions when H2O2 concentration in vivo exceeds physiological limits as in cataract induced by 3-aminotriazole. A scheme of reaction mechanism has been proposed to explain the relative functions of ocular catalase and superoxide dismutase. Such a mechanism may be involved in cataractogenic process in the human.

Amitrole↗
PubMed1977

Subcellular distribution of superoxide dismutases in human neutrophils. Influence of myeloperoxidase on the measurement of superoxide dismutase activity.

We have identified two distinct pools of superoxide dismutase in fractions of human peripheral neutrophils obtained by the isopycnic fractionation of homogenates of the latter with linear sucrose gradients. Superoxide dismutase activity, observed with polyacrylamide gels impregnated with Nitro Blue Tetrazolium, was present in: (1) the mitochondrial fraction [density (rho) 1.169g/ml], containing the high-molecular-weight KCN-resistant enzyme, and (2) the cytoplasm fraction, containing the low-molecular-weight KCN-sensitive enzyme. Superoxide dismutase activity, observed with a quantitative assay involving cytochrome c, was present in: (1) the mitochondria, (2) the cytoplasm, and (3) the azurophil-granule fractions (rho=1.206 and 1.222g/ml). No substantial enzyme activity was observed in specific-granule fractions (rho=1.187g/ml) or in the membranous fraction (rho=1.136g/ml) in either assay. The apparent superoxide dismutase activity observed in the azurophil granules with the cytochrome c assay was attributable not to true superoxide dismutase but to myeloperoxidase, an enzyme found solely in the azurophil granules. In the presence of H(2)O(2), human neutrophil myeloperoxidase oxidized ferrocytochrome c. Thus, in the cytochrome c assay for superoxide dismutase, the oxidation of ferrocytochrome c by myeloperoxidase mimicked the inhibition of reduction of ferricytochrome c by superoxide dismutase. When myeloperoxidase was removed from azurophilgranule fractions by specific immuno-affinity chromatography, both myeloperoxidase and apparent superoxide dismutase activities were removed. It is concluded that there is no detectable superoxide dismutase in either the azurophil or specific granules of human neutrophils. Mitochondrial superoxide dismutase, 15% of the total dismutase activity of the cells, occurred only in fractions of density 1.160g/ml, where isocitrate dehydrogenase and cytochrome oxidase were also observed.

Centrifugation, Isopycnic↗
PubMed1979

Superoxide production in pulmonary alveolar macrophages and killing of BCG by the superoxide-generating system with or without catalase.

The superoxide production of BCG-infected and noninfected alveolar macrophages was measured by superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The cells were incubated with or without cell-free bronchial lavage fluid (pulmonary washings). When control alveolar macrophages were infected by BCG, superoxide production was decreased markedly, probably due to bacterial cytotoxic factors. In contrast, the production of superoxide in alveolar macrophages exposed to pulmonary washings was increased and not appreciably influenced by BCG infection. Superoxide production by alveolar macrophages was dependent on time and on the protein concentration in the pulmonary washings. In controls, it was inversely proportional to the infecting dose of BCG. We observed previously that alveolar macrophages activated by pulmonary washings inhibited intracellular growth of BCG. We now present evidence that enhanced production of superoxide contributes to such inhibition, especially in the presence of catalase at acid pH. These findings are pertinent to the defense of inflamed lungs, where serum and serum immunoglobulin G transuded from blood into alveolar spaces probably induce such activation on alveolar macrophages.

Animals↗
PubMed1992

Osteoclastic superoxide generation: taking control of bone resorption using modulators of superoxide concentrations.

We have examined the role of superoxide in bone resorption by stimulating defective superoxide production and bone resorption in patients with osteopetrosis and inhibiting superoxide production and bone resorption in murine calvarial explants. Interferon gamma treatment did stimulate superoxide generation and bone resorption in patients with osteopetrosis as evidenced by a reduction in bone volume and an increase in biochemical markers of bone resorption. Further, lowering the superoxide concentrations within calvarial osteoclasts using a scavenger, desferal manganese, decreased bone resorption. We conclude that superoxide generation by osteoclasts is necessary for normal osteoclastic function.

Animals↗
PubMed1979

Effects of superoxide radicals on transport (Na + K) adenosine triphosphatase and protection by superoxide dismutase.

Membrane (Na +K)ATPase isolated from rat brain was preincubated in a medium in which superoxide radicals were generated enzymatically. Exposure to superoxide radicals caused an irreversible inactivation, which could be prevented by further addition of superoxide dismutase. (Na + K)ATPase was also protected by addition of allopurinol, a xanthine oxidase inhibitor, during preincubation. The K-activated nitrophenylphosphatase associated with (Na + K)ATPase was also found to be inactivated by preincubation with superoxide radicals, which could be prevented by superoxide dismutase.

Allopurinol↗
PubMed1992

Rickettsia rickettsii induces superoxide radical and superoxide dismutase in human endothelial cells.

Human endothelial cells infected with Rickettsia rickettsii, the etiological agent of Rocky Mountain spotted fever, undergo striking morphological changes to the endoplasmic reticulum-outer nuclear envelope complex. These changes are accompanied by concurrent accumulation of intracellular peroxides. Both of these findings are consistent with the notion that cells undergo some form of oxidative stress. Since oxidant injury is often initiated or mediated through oxygen radicals, we examined superoxide radical generation when endothelial cells were exposed to R. rickettsii. We also examined the levels of superoxide dismutase, an enzyme induced in response to increased superoxide formation. The levels of both superoxide and superoxide dismutase increased when endothelial cells were exposed to R. rickettsii. These results, together with our previous findings, support our hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury that may eventually contribute to cell death.

Cells, Cultured↗
PubMed1975

Bactericidal activity of superoxide anion and of hydrogen peroxide: investigations employing dialuric acid, a superoxide-generating drug.

The addition of dialuric acid (a superoxide-generating drug) to a suspension of resting human neutrophils resulted in a stimulation of cellular hexose monophosphate shunt activity. Measurement of oxygen consumption demonstrated a rapid rate of oxygen uptake by the drug alone in aqueous solution. The subsequent addition of catalase (but not of superoxide dismutase) resulted in a substantial release of oxygen, indicating that H(2)O(2) was accumulating in the media. The generation of O(2) (-) by the drug was verified by measuring the rate of reduction of cytochrome c by the drug in the presence and absence of authentic superoxide dismutase. The growth of Escherichia coli B and Staphylococcus aureus was inhibited in vitro by addition of the drug to a suitable culture media; the degree of inhibition was dose dependent. This inhibition of bacterial growth could be completely reversed by the addition of as little as 5 mug of purified catalase, but was not affected by concentrations of superoxide dismutase that were 2,000-fold higher. These results suggest that the dialuric acid-induced stimulation of hexose monophosphate shunt activity in neutrophils is due to accumulated H(2)O(2). Further, the contribution of superoxide to the bactericidal activity towards E. coli and S. aureus is probably minimal compared with that of H(2)O(2).

Barbiturates↗
PubMedDate not supplied

Cyanide insensitive iron superoxide dismutase in Euglena gracilis. Comparison of the reliabilities of different test systems for superoxide dismutases.

Two proteins (P1 and P2, with weights of 57,500 and 27,500 respectively) were isolated from Euglena gracilis. Both proteins show cyanide-insensitive superoxide dismutase activity in the "classical" superoxide dismutase assay, using xanthine-xanthine oxidase as O2.- generator. If O2.- is generated chemically (autoxidation of reduced anthraquinone), photochemically (illuminated riboflavine) or pulse radiolytically, only protein P1 but not P2 shows SOD activity. Protein P1 contains 1 g atom (determined: 0.82) iron (no Mn or Cu) per mole protein and may thus be defined as iron-superoxide dismutase. Protein P2, showing the spectral properties of a flavoprotein, exhibits the activities of ferredoxin-NADP-oxidoreductase and "diaphorase". The cyanide-insensitive SOD-activity of this Diaphorase" in the xanthine oxidase-assay for superoxide dismutase makes this classical and commonly used test unreliable for assay cyanide insensitive SOD activities. The existence of the "prokaryote-type" of superoxide dismutase (Fe-SOD) in Euglena gracilis is exceptional for an eukaryotic, autotrophically grown organisms.

2,6-Dichloroindophenol↗
PubMed1992

Effects of the superoxide radical scavenger superoxide dismutase, and of the hydroxyl radical scavenger mannitol, on reperfusion injury in isolated rabbit hearts.

Hydroxyl radical formation, secondary to superoxide radical generation, has been advocated as the actual mechanism of oxygen radical-mediated damage in biological systems. The present study was designed to compare the efficacy of administration of the hydroxyl radical scavenger mannitol vs. that of the superoxide radical scavenger superoxide dismutase (SOD) in reducing myocardial reperfusion injury, and to test whether combined treatment with both agents would confer better tissue protection compared with either intervention alone. Rabbit hearts perfused within a 31P nuclear magnetic resonance (31P-NMR) spectrometer were subjected to 30 minutes of total global ischemia at 37 degrees C. At reflow, 12 hearts in each group received either (a) a bolus of standard perfusion buffer, followed by 45 minutes of reperfusion (controls); (b) the superoxide radical scavenger recombinant human SOD (h-SOD, as a 60,000 U bolus followed by a 100 U/ml infusion for 15 minutes); (c) the hydroxyl radical scavenger mannitol (50 mM bolus followed by 15 minutes of 50 mM infusion; or (d) a combination of both agents. All treated hearts were switched to standard buffer for the remaining 30 minutes of reperfusion. Treatment with h-SOD alone was associated with a significant improvement in the recovery of cardiac contractility and coronary flow, as well as of ATP content, compared to control hearts. In contrast, mannitol treatment resulted in a small, nonsignificant improvement in these parameters. The addition of mannitol to h-SOD did not result in further significant improvement of contractility and ATP recovery compared to h-SOD alone. These data demonstrate that under our experimental conditions significant protection against reperfusion injury can be achieved by the administration of h-SOD alone, without the need for additional hydroxyl radical scavenger therapy with mannitol. These results do not exclude that significant tissue protection may be achieved by different doses of mannitol or by other agents. However, they suggest that under definite experimental conditions prevention of hydroxyl radical formation, rather than attempts to minimize hydroxyl radical toxicity, might be a more efficient method to prevent oxygen radical-mediated reperfusion injury in isolated hearts.

Adenosine Triphosphate↗
PubMed1979

Generation of superoxide radicals in alkaline solutions of hydrogen peroxide and the effect of superoxide dismutase on this system.

Superoxide radicals in high concentrations were generated from alkaline H2O2 without using catalysts or irradiation. The dependence of the intensity and parameters of the superoxide radical EPR spectrum on pH, temperature, viscosity and H2O2 concentration were studied. The observed changes are explained on the base of matrix effects. The addition of superoxide dismutase to alkaline H2O2 led initially to a drop in the EPR spectrum intensity, followed by an increase in the concentration of superoxide radicals.

Electron Spin Resonance Spectroscopy↗
PubMed1992

Vascular bound recombinant extracellular superoxide dismutase type C protects against the detrimental effects of superoxide radicals on endothelium-dependent arterial relaxation.

Extracellular superoxide dismutase type C (EC-SOD C) is a secretory SOD isoenzyme that, in vivo, is bound to heparan sulfate proteoglycans in the glycocalyx of various cell types (e.g., endothelial cells) and in the connective tissue matrix. The aim of this study was to investigate the efficacy of vascular bound EC-SOD C in protecting arterial relaxation mediated by endothelium-derived relaxing factor (EDRF) against the inhibitory effects of superoxide radicals. For comparison, the effect of CuZn SOD was also studied. This SOD isoenzyme lacks affinity toward heparan sulfate and does not bind to cell surfaces. Rings from rabbit aorta were mounted in an organ bath and acetylcholine-induced endothelium-dependent relaxation was then studied in preparations precontracted with phenylephrine. Pyrogallol (10(-4) M), used to generate superoxide radicals, reduced the maximal relaxant effect of acetylcholine from about 65% to 25%. When present in the buffer throughout the experiment, CuZn SOD and EC-SOD C caused a concentration-dependent prevention of the pyrogallol effect on EDRF-mediated relaxation, with a half-maximal effect at about 100 units/ml (KO2 assay). In a second set of experiments, the arterial rings were preincubated with 8,000 units/ml CuZn SOD (50 micrograms/ml) or EC-SOD C (69 micrograms/ml) during 30 minutes, followed by washing, before the effect of pyrogallol on EDRF-mediated relaxation was studied in SOD-free buffer.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMedDate not supplied

[Role of superoxide anion-radicals and superoxide dismutase in the lipid photoperoxidation reactions of isolated chloroplasts].

Exogenous superoxide dismutase (SOD, erythrocuprein) inhibits the chlorophyll bleaching and photoperoxidation of polyunsaturated lipids in pea isolated chloroplasts. As SOD did not produce this effect in tris-HCl buffer, it is suggested that peroxidation is mediated by the OH radicals which may appear in illuminated chloroplasts with the participation of superoxide radicals and hydrogen peroxide. The physiological role of SOD is discussed in relation to the stability of cells photosynthesizing organisms towards light and oxygen effect.

Chloroplasts↗
PubMed1978

Effects of superoxide dismutase, dithiothreitol and formate ion on the inactivation of papain by hydroxyl and superoxide radicals in aerated solutions.

Losses in enzyme activity and sulphydryl content have been studied in aerated papain solutions containing formate, superoxide dismutase and dithiothreitol. Both formate and dithiothreitol converted .OH to .O2-, whereas superoxide dismutase completely suppressed the inactivation by .O2-. Using results from all three systems, the fraction of .O2- reactions with papain that caused inactivation of the enzyme was 0.33 +/- 0.07. The results also showed that the fraction of .OH reactions, which cause inactivation of papain, is significantly higher in aerated than in oxygen-free solutions.

Cobalt Radioisotopes↗
PubMed1979

Influence of superoxide generating system, vitamin E, and superoxide dismutase on radiation consequences.

During studies of the mechanism by which hemolysis is induced in irradiated human erythrocytes in vitro, several inducements of membrane lipid peroxidation and protective effects of vitamin E (V.E) and superoxide dismutase (SOD) were investigated. Findings were: (1) Before hemolysis, K+ release from erythrocytes induced by radiation stimulated hemolysis but was inhibited by V.E or SOD. (2) Lipid peroxidation of mitochondria induced by Fe3+, ADP, and superoxide (O2-) generating system, and lipid peroxidation of microsome induced by O2- generating system, were also inhibited by V.E or SOD. (3) X-ray or 60Co gamma-ray radiation stimulated lipid peroxidation of liver homogenate, microsome, and liposome. Some of this peroxidation was inhibited by V.E. or SOD. These results suggest that O2- and/or OH formation by radiation induces membrane lipid peroxidation, which causes deterioration of membrane resulting in change of ion permeability and consequent hemolysis.

Adenosine Diphosphate↗
PubMedDate not supplied

Superoxide dismutases: defence against endogenous superoxide radical.

Attempts to measure the rate of O2- production, in whole cells or in intact subcellular organelles, are frustrated by the endogenous superoxide dismutase (SOD). Streptococcus faecalis contains a single manganese-SOD which was isolated and used as an antigen in the rabbit. A precipitating and inhibiting antibody was obtained and used to suppress the SOD in crude lysates of S. faecalis. It allowed the demonstration that 17% of the total oxygen uptake by such lysates, in the presence of NADH, was associated with O2- production. O2- attacks unsaturated lipids and breaches the integrity of membranes. When the membranes are free of lipid hydroperoxides, then both O2- and H2O2 are required and singlet oxygen appears to be the proximal attacking species. When the membrane contains some lipid hydroperoxide, then O2- is itself sufficient and seems to generate an alkoxy radical, by reacting with the lipid hydroperoxide. It appears likely that attack on membranes is one of the reasons for the cytotoxicity of O2-. In Escherichia coli the manganese-SOD is derepressed by O2-. This enzyme is not made in the absence of oxygen and in aerobic conditions any change which results in enhanced production of O2- calls forth an increased synthesis of this enzyme. Increased levels of SOD, however achieved, correlate with greater resistance towards oxygen toxicity. It is generally true that respiring cells contain more SOD than non-respiring cells. Among obligate anaerobes there is a correlation between SOD-content and tolerance towards oxygen. It is not known whether the SOD in obligate anaerobes is a retained primitive characteristic or one recently acquired by plasmid transfer. There is an exception to the rule that copper-zinc-SOD is found in eukaryotes but not in prokaryotes, and that is the symbiotic bacterium Photobacterium leiognathi. This symbiont may have obtained the Cu-ZnSOD gene from the host fish.

Animals↗
PubMed1978

Superoxide generation by digitonin-stimulated guinea pig granulocytes. A basis for a continuous assay for monitoring superoxide production and for the study of the activation of the generating system.

Stimulation of guinea pig granolocytes by digitonin results in superoxide (O-2) generation. A continuous assay shows that there is a lag between the addition of digitonin and the onset of O-2 production. The rate of activation of the O-2 generating system is dependent upon the concentration of digitonin and the temperature. The final linear rate of O-2 production is affected by the concentration of digitonin, temperature, pH, and the presence of exogenous reduced pyridine nucleotides. Thus, factors which alter either the activation process or the activity of the O-2 generating system can affect O-2 production by stimulated granolocytes.

Animals↗