Showing papers on "Catalase published in 1979"
TL;DR: The effect of alloxan appeared paradoxical in that it increased cyanide-resistant respiration without significantly increasing the cell content of the manganese-superoxide dismutase and with only a small effect on the level of catalase.
575 citations
TL;DR: It is demonstrated that release of H2O2 was both necessary and sufficient for cytolysis by BCG-activated macrophages and by granulocytes when pharmacologically triggered, and that lactoperoxidase may have diverted H 2O2 from the oxidation of target cells to oxidation of substances in serum.
Abstract: When deprived of oxygen, Bacille Calmette-Guerin (BCG)-activated macrophages no longer lysed P388 lymphoma cells. Both H2O2 release and cytotoxicity by BCG-activated macrophages and by granulocytes triggered with phorbol myristate acetate (PMA) were markedly inhibited when the glucose concentration in the medium was reduced to 0.03 mM or less, or if glucose were replaced with galactose. Catalase abolished PMA-triggered cytotoxicity by both types of effector cells, whereas superoxide dismutase had no effect. Ferricytochrome C reduced the cytotoxicity of BCG-activated macrophages, an effect which was largely reversed by superoxide dismutase. 10 drugs, thought to quench singlet oxygen and/or scavenge hydroxyl radical, did not affect cytotoxicity in this system. Neither azide nor cyanide reduced cytolysis, but there was marked inhibition by lactoperoxidase and iodide. This suggested that cytotoxicity was not dependent upon myeloperoxidase, and that lactoperoxidase may have diverted H2O2 from the oxidation of target cells to oxidation of substances in serum. Mouse erythrocytes, although sensitive targets, interfered with the cytolysis of lymphoma cells, probably by competition for H2O2. Starch particles with covalently bound glucose oxidase resembled macrophages in their spatial relation to the target cells and in the flux of H2O2 they generated from their surface, but were not expected to produce any other potentially toxic products. Such particles lysed lymphoma cells, and the lysis was prevented by catalase. Neither arginase nor thymidine appeared to be involved in cytolysis by BCG-activated macrophages under the conditions used. These findings demonstrated that release of H2O2 was both necessary and sufficient for cytolysis by BCG-activated macrophages and by granulocytes when pharmacologically triggered.
483 citations
TL;DR: Results are consistent with previous demonstrations of the release of potent oxidants by stimulated PMN, as well as earlier studies from the laboratory showing sensitivity of alpha1-proteinase inhibitor to inactivation by oxidants.
Abstract: Human polymorphonuclear leukocytes (PMN) phagocytosing opsonized antigen-antibody complexes, produce dialyzable species of activated oxygen which are capable of partially suppressing the elastase-inhibiting capacity (EIC) of whole human serum or purified human alpha1-proteinase inhibitor. Serum EIC was partially protially protected by superoxide dismutase, catalase, or mannitol, suggesting that hydroxyl radical, formed by interaction of superoxide radical and hydrogen peroxide, might be responsible for this effect. NaN3 also partly protected EIC, implicating myeloperoxidase-mediated reactions as well. An artificial superoxide rradical-generating system, involving xanthine and xanthine-oxidase, could be substituted for phagocytosing PMN with resultant EIC suppression. These results are consistent with previous demonstrations of the release of potent oxidants by stimulated PMN, as well as earlier studies from our laboratory showing sensitivity of alpha1-proteinase inhibitor to inactivation by oxidants. Oxidative inactivation of proteinase inhibitors in the microenvironment of PMN accumulating at sites of inflammation may allow proteases released from these cells to more readily damage adjacent connective tissue structures.
277 citations
TL;DR: The major antioxidant defense system appears to function by scavenging free radicals and singlet oxygen with vitamin E and superoxide dismutase as discussed by the authors, which is closely related to dietary proteins, lipids, carbohydrates, minerals and vitamins, and all are involved in the cellular antioxidant defense.
257 citations
TL;DR: Results indicate that hydrogen peroxide interacts with reduced sulfhydryl groups which are involved in the light activation of enzymes of the Calvin cycle at the site of fructose- and sedoheptulose bisphophatase, of phosphoribulokinase, as well as in light-inactivation of oxidative pentose phosphate cycle atThe site of glucose-6-phosphate dehydrogenase.
Abstract: Hydrogen peroxide (6x10-4 M) causes a 90% inhibition of CO2-fixation in isolated intact chloroplasts. The inhibition is reversed by adding catalase (2500 U/ml) or DTT (10 mM). If hydrogen peroxide is added to a suspension of intact chloroplasts in the light, the incorporation of carbon into hexose- and heptulose bisphosphates and into pentose monophosphates is significantly increased, whereas; carbon incorporation into hexose monophosphates and ribulose 1,5-bisphosphate is decreased. At the same time formation of 6-phosphogluconate is dramatically stimulated, and the level of ATP is increased. All these changes induced by hydrogen peroxide are reversed by addition of catalase or DTT. Additionally, the conversion of [14C]glucose-6-phosphate into different metabolites by lysed chloroplasts in the dark has been studied. In presence of hydrogen peroxide, formation of ribulose-1,5-bisphosphate is inhibited, whereas formation of other bisphosphates,of triose phosphates, and pentose monophosphates is stimulated. Again, DTT has the opposite effect. The release of 14CO2 from added [14C]glucose-6-phosphate by the soluble fraction of lysed chloroplasts via the reactions of oxidative pentose phosphate cycle is completely inhibited by DTT (0.5 mM) and re-activated by comparable concentrations of hydrogen peroxide. These results indicate that hydrogen peroxide interacts with reduced sulfhydryl groups which are involved in the light activation of enzymes of the Calvin cycle at the site of fructose- and sedoheptulose bisphophatase, of phosphoribulokinase, as well as in light-inactivation of oxidative pentose phosphate cycle at the site of glucose-6-phosphate dehydrogenase.
249 citations
TL;DR: Observations suggest that H2O2 may act as a "second messenger" for the observed effects of insulin and suggest that insulin stimulation of intracellular H 2O2 production is linked to glucose metabolism.
232 citations
TL;DR: The acetaldehyde-xanthine oxidase system which like phagocytosing PMNs generates superoxide (O.2-) and hydrogen peroxide, is bactericidal both in the presence and absence of myeloperoxidase (MPO) and chloride.
Abstract: The acetaldehyde-xanthine oxidase system in the presence and absence of myeloperoxidase (MPO) and chloride has been employed as a model of the oxygen-dependent antimicrobial systems of the PMN. The unsupplemented xanthine oxidase system was bactericidal at relatively high acetaldehyde concentrations. The bactericidal activity was inhibited by superoxide dismutase (SOD), catalase, the hydroxyl radical (OH.) scavengers, mannitol and benzoate, the singlet oxygen (1O2) quenchers, azide, histidine, and 1,4-diazabicyclo[2,2,2]octane (DABCO) and by the purines, xanthine, hypoxanthine, and uric acid. The latter effect may account for the relatively weak bactericidal activity of the xanthine oxidase system when purines are employed as substrate. A white, carotenoid-negative mutant strain of Sarcina lutea was more susceptible to the acetaldehyde-xanthine oxidase system than was the yellow, carotenoid-positive parent strain. Carotenoid pigments are potent 1O2 quenchers. The xanthine oxidase system catalyzes the conversion of 2,5-diphenylfuran to cis-dibenzoylethylene, a reaction which can occur by a 1O2 mechanism. This conversion is inhibited by SOD, catalase, azide, histidine, DABCO, xanthine, hypoxanthine, and uric acid but is only slightly inhibited by mannitol and benzoate. The addition of MPO and chloride to the acetaldehyde-xanthine oxidase system greatly increases bactericidal activity; the minimal effective acetaldehyde concentration is decreased 100-fold and the rate and extent of bacterial killing is increased. The bactericidal activity of the MPO-supplemented system is inhibited by catalase, benzoate, azide, DABCO, and histidine but not by SOD or mannitol. Thus, the acetaldehyde-xanthine oxidase system which like phagocytosing PMNs generates superoxide (O.2-) and hydrogen peroxide, is bactericidal both in the presence and absence of MPO and chloride. The MPO-supplemented system is considerably more potent; however, when MPO is absent, bactericidal activity is observed which may be mediated by the interaction of H2O2 and O.2- to form OH. and 1O2.
217 citations
TL;DR: The inhibition of this system's microbicidal activity by scavengers of O2- (superoxide dismutase) and H2O2 (catalase) indicated that although neither O1- nor H1O2 were toxoplasmacidal, their interaction was required for parasite killing.
Abstract: A sensitive method for evaluating extracellular parasite viability was used to determine the in vitro susceptibility of virulent Toxoplasma gondii to selected oxygen intermediates. By acridine orange fluorescent staining criteria, toxoplasmas were resistant to up to either 10(-3) M reagent H2O2 or H2O2 generated by glucose-glucose oxidase. In keeping with a lack of sensitivity to H2O2, toxoplasmas contained endogenous catalase (5.7 x 10(-4) Baudhuin units/10(6) organisms). The addition of a peroxidase and halide, however, markedly accelerated killing and lowered the H2O2 requirement by 1,000-fold. In contrast, toxoplasmas were promptly killed after exposure to products generated by xanthine (1.5 x 10(-4) M) and xanthine oxidase (50 micrograms). The inhibition of this system's microbicidal activity by scavengers of O2- (superoxide dismutase) and H2O2 (catalase) indicated that although neither O2- nor H2O2 were toxoplasmacidal, their interaction was required for parasite killing. Quenching OH. and 1O2, presumed products of O2--H2O2 interaction, by mannitol, benzoate, diazabicyclooctane, and histidine, also inhibited toxoplasma killing by xanthine-xanthine oxidase. These findings suggested that O2- and H2O2 functioned in precursor roles and that OH. and 1O2 were toxoplasmacidal. The capacity of normal peritoneal macrophages to pinocytose an oxygen intermediate scavenger, soluble catalase, was also demonstrated. Appreciable extraphagosomal concentrations of catalase were achieved by exposing macrophages to 1 mg/ml of the enzyme for 3 h. Maintenance of high intracellular levels required constant exposure because interiorized catalase was rapidly degraded.
171 citations
Journal Article•
TL;DR: Experiments were done to determine whether the respiratory burst of superoxide anion (O2-) production in polymorphonuclear leukocytes (PMN) is triggered during antibody-dependent killing of tumor cells and whether O2- production is essential for cytotoxicity.
Abstract: Experiments were done to determine 1) whether the respiratory burst of superoxide anion (O2-) production in polymorphonuclear leukocytes (PMN) is triggered during antibody-dependent killing of tumor cells and 2) whether O2- production is essential for cytotoxicity. Three parameters of the respiratory burst (1-14C-glucose oxidation, oxygen consumption, and O2- release) were increased 2.5- to 7.3-fold during killing of antibody-primed tumor cells by human PMN. Added catalase and superoxide dismutase did not inhibit lysis, possibly because these enzymes were unable to diffuse into the inter-plasma-membrane space between killer and target cells. Evidence for an O2- requirement for cytotoxicity was the fact that concentrations of amobarbital or phenylbutazone sufficient to inhibit the cyanide-insensitive respiration of PMN also inhibited cytotoxicity. Also, hypoxic conditions inhibited cytotoxicity from 29 to 73%. The requirement for oxygen was most likely related to O2- generation and not mitochondrial respiration since cyanide and azide, which inhibit mitochon drial respiration, increased cytotoxicity.
145 citations
TL;DR: Results indicate a singlet oxygen-mediated process that generates upon irradiation with near ultraviolet light reactive oxygen species on which the in vitro nematicidal activity depends.
143 citations
TL;DR: The level of thiobarbituric acid-reactive products and the specific activities of catalase and glutathione reductase were significantly higher in muscles from patients with major forms of muscular dystrophies over those of control subjects.
TL;DR: C. fetus is more sensitive to exogenous superoxide anions and hydrogen peroxide than are aerotolerant bacteria, despite the occurrence of superoxide dismutase and catalse activities in C. fetus.
Abstract: The addition of bovine superoxide dismutase to Brucella broth or Brucellar agar greatly echanced the oxygen tolerance of Campylobacter fetus subsp. jejuni strain H840 (ATCC 29428). Catalase also enhanced oxygen tolerance, but to a lesser extent. These enzymes must act externally to the bacteria. All of the diverse compounds which enhance oxygen tolerance of C. fetus, including nor-epinephrine and a combination of ferrous sulfate, sodium metabisulfite, and sodium pyruvate, share the ability to quench either superoxide anions or hydrogen peroxide. On the basis of these and other data, we propose that C. fetus is more sensitive to exogenous superoxide anions and hydrogen peroxide than are aerotolerant bacteria, despite the occurrence of superoxide dismutase and catalse activities in C. fetus. Compounds that enhance oxygen tolerance in C. fetus appear to act by quenching superoxide anions and hydrogen peroxide which occur spontaneously in the culture medium.
TL;DR: Heterogeneity of peroxisome enzyme content is in accord with reports from biochemical studies of brain, where several nervous system cell types that contain relatively numerous catalase-positive bodies, contain none with detectable D-AAO.
Abstract: A recently developed procedure for the localization of D-amino acid oxidase (D-AAO) has been used to investigate the distribution of this enzyme in rat nervous tissue. Initial studies were carried out on kidney to validate the methods. The cytochemically demonstrable enzyme in kidney is inhibited by kojic acid, a known competitive D-AAO inhibitor. Omission of the catalase inhibitor, aminotriazole, from the cytochemical medium produces a marked diminution of n-AAO reaction product in kidney peroxisomes. This would be expected if catalase and D-AAO are present in the same particles. In brain, kojic acid-inhibitable D-AAO is demonstrable in numerous bodies within astrocytes especially in the cerebellum, a brain region known from biochemistry to contain particularly high levels of the oxidase. In preparations incubated for catalase, far fewer positive bodies are seen in the cerebellum. Moreover, omission of aminotriazole has little evident effect on the D-AAO reaction. Thus, the oxidase-containing cerebellar bodies may be relatively poor in catalase. In contrast, several nervous system cell types that contain relatively numerous catalase-positive bodies, contain none with detectable D-AAO. Such heterogeneity of peroxisome enzyme content is in accord with reports from biochemical studies of brain.
TL;DR: The results imply that guanylate cyclase responses to activators that can form NO are determined by both the stimulatory activity of the endogenous heme acceptors of NO and the relative inhibitory effects of the unliganded heme proteins present, which may explain the more pronounced decline in the rate of cGMP generation in air in the presence of NO.
TL;DR: Results indicated that hydrogen peroxide was formed in the dilution blank solution in a metal ion-catalyzed autoxidation of cysteine and that hydrogenperoxide was toxic to P. anaerobius VPI 4330-1 in a reaction also catalyzed by metal ions.
Abstract: Peptostreptococcus anaerobius VPI 4330-1 was exposed to atmospheric oxygen in a dilution bland (0.2% gelatin, salts, resazurin) solution. The organisms were rapidly killed when the solution contained cysteine. The organisms were effectively protected by catalase and horseradish peroxidase as well as by the metal ion-chelating agents 8-hydroxyquinoline and 2,2'-bipyridine. Superoxide dismutase increased the rate of killing of the organisms, whereas singlet oxygen quenchers and scavengers of hydroxyl free radicals did not protect the organisms from the toxic effect of cysteine. Hydrogen peroxide was formed when cysteine was exposed to oxygen in the dilution blank solution, and the reaction was inhibited by metal ion-chelating agents. The organisms were rapidly killed by 20 microM hydrogen peroxide in anaerobic dilution blank solution. The toxic effect of hydrogen peroxide in anaerobic dilution blank solution. The toxic effect of hydrogen peroxide was completely abolished by catalase and metal ion-chelating agents. These results indicated that hydrogen peroxide was formed in the dilution blank solution in a metal ion-catalyzed autoxidation of cysteine and that hydrogen peroxide was toxic to P. anaerobius VPI 4330-1 in a reaction also catalyzed by metal ions.
TL;DR: It is concluded that singlet oxygen, or something with similar reactivity, was generated from O2- plus H2O2 and contributed significantly to the observed autoinactivation.
TL;DR: Liver microsomes from control and phenobarbital-induced mice have been used to study the effect of paraquat (PQ) on oxygen reduction and malondialdehyde formation, and lipid peroxidation as measured by MDA formation was not increased but rather inhibited by concentrations of PQ lower than those needed to stimulate oxygen uptake and to inhibit p -nitroanisole- O -demethylation.
TL;DR: Data indicate a remarkable susceptibility of newborn larvae of T. spiralis to the hydrogen peroxide generated by neutrophil and eosinophil leukocytes.
Abstract: Eosinophil and/or neutrophil leukocytes appear to have important roles in host defense against invasive, migratory helminth infestations, but the mechanisms of larval killing by leukocytes are uncertain. This study examines killing of newborn (migratory phase) larvae of Trichinella spiralis during incubation with granule preparations of human eosinophils or neutrophils and generators of hydrogen peroxide (glucose-glucose oxidase) (G-GO) or superoxide and hydrogen peroxide (xanthine-xanthine oxidase). Larvae were killed by either hydrogen peroxide-generating system in a concentration-dependent manner. Direct enumeration of surviving larvae after incubation in microtiter wells containing the appropriate reagents was used in assess larval killing. Verification of the microplate assay was demonstrated by complete loss of larval ability to incorporate [(3)H]deoxyglucose and loss of infectivity after incubation in comparable concentrations of G-GO. Larvae were highly sensitive to oxidative products; significant killing occurred after incubation with 0.12 mU glucose oxidase and complete killing occurred with 0.5 mU. Comparable killing of bacteria required over 60 mU glucose oxidase. At 5 mU glucose oxidase, killing was complete after 6 h of incubation. Killing by G-GO was inhibited by catalase but not by boiled catalase or superoxide dismutase and was enhanced by azide. Addition of peroxidase in granule pellet preparations of eosinophils or neutrophils did not enhance killing by G-GO. These data indicate a remarkable susceptibility of newborn larvae of T. spiralis to the hydrogen peroxide generated by neutrophil and eosinophil leukocytes.
TL;DR: The observations indicate that there are several options for the localization of catalase depending on the fixation and incubation conditions, and these conditions should be selected according to the tissue and the purpose of the study.
Abstract: The influence of various parameters of fixation and incubation upon the oxidation of DAB by catalase have been analyzed. Crystalline beef liver catalase was fixed with different concentrations of glutaraldehyde and peroxidatic activity was determined spectrophotometrically using DAB as hydrogen donor. Although aldehyde fixation appeared to be important in elicitation of the peroxidatic activity of catalase, the final pigment production after 60 min incubation was optimal with the lowest concentration of glutaraldehyde (1%), after the shortest fixation period (30 min), and at the lowest temperature (5° C) tested. Similarly cytochemical studies with rat kidney sections incubated for 10 min confirmed that the staining of peroxisomes in proximal tubules was strongest after the “mildest” fixation conditions. The pH and the temperature of incubation were closely interrelated, so that at room temperature (25° C) the maximal pigment production was obtained at pH 10.5 but incubation at 45° C gave the strongest staining at pH 8.5. The production of pigment increased with higher DAB concentrations which required larger amounts of H2O2 in the incubation medium. Cytochemical studies on renal peroxisomes were in agreement with these biochemical findings. The observations indicate that there are several options for the localization of catalase depending on the fixation and incubation conditions. Hence, these conditions should be selected according to the tissue and the purpose of the study. Examples for such selective applications are presented.
TL;DR: The view that the redox cycling of nitrofurantoin in lung microsomes in the presence of oxygen results in the consumption of NADPH and the production of activated oxygen species, emphasizing some in vitro metabolic similarities with the lung-toxic herbicide, paraquat, is consistent.
TL;DR: Simple methods have been developed using the specific inhibitor, 3-amino-1,2,4-triazole, for the direct analysis of rates of synthesis and degradation of the Cat(+) gene product and it is suggested that these techniques can be readily applied to an examination of mutants that control the expression of the structural gene for catalase in Drosophila.
Abstract: A screen for allelic variants of the enzyme catalase indicated that the Cat + locus is essentially monomorphic in D. melanogaster . Segmental aneuploidy was used to screen the genome for a dosage-sensitive region for catalase activity. One region, 75D-78A on the polytene chromosome map of 3L, exhibited a hyperploid/euploid ratio of enzyme activity of 1.5. Further dissection localized the region to 75D-76A. We suggest that this region contains the structural locus for catalase in D. melmogaster . Simple methods have been developed using the specific inhibitor, 3-amino-1,2,4-triazole, for the direct analysis of rates of synthesis and degradation of the Cat + gene product. Based on kinetic studies of catalase synthesis in flies aneuploid and euploid for region 75D-76B, we suggest that these techniques can be readily applied to an examination of mutants that control the expression of the structural gene for catalase in Drosophila.
Journal Article•
TL;DR: The view that catalase is the first line of defense against the oxidative stress of Cl02 in rat and chicken erythrocytes is supported, as activity was decreased in rat treated with Cl0-2 and at the same time that GSH was decreased.
Abstract: Chlorine dioxide (Cl02) has been proposed as an alternative disinfectant to chlorine to avoid formation of organohalides. Cl02 and metabolites, chlorite (Cl0-2) and chlorate (Cl0-3) in drinking water produced decreases in rat and chicken blood GSH. The GSH dependent system was studied in rat and chicken blood after chronic treatment for 6 months with CL02 (0, 1, 10, 100, 1000 MG/L), Cl0-2 or Cl0-3 (10, 100 mg/l) in drinking water. There was a 60% increase in GSH reductase in the Cl02 treatment groups of rats and chickens. A similar increase was shown in rats treated with Cl0-2 but with Cl0-3 no change was observed. GSH peroxidase was without change in rat but chickens drinking 1000 mg/l Cl02 had decreased activity. Catalase was significantly higher than control in rat and chicken in the 1000 mg/l groups. However, catalase activity was decreased in rat treated with Cl0-2 and at the same time that GSH was decreased. These studies support the view that catalase is the first line of defense against the oxidative stress of Cl02 in rat and chicken erythrocytes.
Journal Article•
TL;DR: The effects of chronic intake of dietary ethanol upon catalase, an enzyme capable of metabolizing ethanol, as well as upon myocardial morphology and hemodynamics, were studied in the rat to explore the possibility of catal enzyme playing a metabolic and potentially protective role in rat myocardium chronically exposed to ethanol.
Abstract: The effects of chronic intake of dietary ethanol upon catalase, an enzyme capable of metabolizing ethanol, as well as upon myocardial morphology and hemodynamics, were studied in the rat. Ethanol, comprising 36% of dietary calories, administered to rats for 5 weeks, was associated with increased myocardial catalase of 45.9 +/- 3.7 IU/mg protein, compared to 21.0 +/- 1.8 IU/mg protein in pair-fed controls. The enzyme activity remained significantly elevated after 18 weeks of ethanol. Hepatic catalase did not differ in these groups. Parallel cytochemical studies confirmed the increase in myocardial catalase by demonstrating an increase in peroxisomes. Gross and light-microscopic examinations revealed no abnormalities at either 5 or 18 weeks. Remarkably few ultrastructural abnormalities were seen in this material fixed by vascular perfusion. Hemodynamic studies after 5 weeks of ethanol revealed decreased left ventricle systolic pressure and decreased mean arterial pressure but no change in ventricular filling pressure. The possibility of catalase playing a metabolic and potentially protective role in rat myocardium chronically exposed to ethanol is discussed.
TL;DR: The evidence presented shows that the aggregation of streptococcal cells by their hyaluronic acid capsule provides this organism with a novel means to avoid self-destruction by oxygen metabolites--cells are shielded from oxygen.
Abstract: Unencapsulated variants of encapsulated, M-protein-positive group A streptococci are oxygen sensitive and secrete inhibitory concentrations of hydrogen peroxide when grown in aerated broth cultures. The organisms were equally sensitive to hydrogen peroxide, and neither exhibited catalase or peroxidase activity, suggesting that differences in oxygen sensitivity reflect dissimilarity in oxygen uptake. The encapsulated parental culture was found to grow in aggregates that take up oxygen more slowly than unencapsulated, oxygen-sensitive derivatives. Moreover, the latter grow in an unaggregated, homogenous suspension. The enzyme hyaluronidase was able to disrupt aggregates of the encapsulated strain increase the rate that these cells take up oxygen, and cause the accumulation of toxic concentrations of hydrogen peroxide earlier in their growth cycle. The evidence presented shows that the aggregation of streptococcal cells by their hyaluronic acid capsule provides this organism with a novel means to avoid self-destruction by oxygen metabolites--cells are shielded from oxygen. The reduced surface-to-volume ratio and limited diffusion of oxygen into the interior of aggregates are proposed as the protective mechanism.
TL;DR: A mechanism of paraquat- and diquat-initiated lipid peroxidation independent of superoxide and peroxide generation is proposed, and the stimulatory effects of Paraquat anddiquat on lung microsomal lipidperoxidation are discussed in relation to the lipid per oxidation hypothesis of paraaquat lung toxicity.
TL;DR: Modification of the activity of the pulmonary antioxidant defense systems provides a plausible mechanism in explaining pharmacological alteration of oxygen-induced pulmonary injury.
TL;DR: The results imply that the enzyme activity of the nucleoids of rat liver peroxisomes is not exclusively due to urate oxidase, and may contain a variety of other enzymes that may be more or less loosely associated with the insoluble components of these structures.
Abstract: The distribution of catalase, amino acid oxidase, α-hydroxy acid oxidase, urate oxidase and alcohol oxidase was studied cytochemically in rat hepatocytes. The presence of catalase was demonstrated with the conventional diaminobenzidine technique. Oxidase activities were visualized with methods based on the enzymatic or chemical trapping of the hydrogen peroxide produced by these enzymes during aerobic incubations. All enzymes investigated were found to be present in peroxisomes. Catalase activity was found in the peroxisomal matrix, but also associated with the nucleoid. After staining for oxidase activities the stain deposits occurred invariably in the peroxisomal matrix as well as in the nucleoids. In all experiments the activity of both catalase and the oxidases was confined to the peroxisomes. The presence of a hydrogen peroxide-producing alcohol oxidase was demonstrated for the first time in peroxisomes in liver cells. The results imply that the enzyme activity of the nucleoids of rat liver peroxisomes is not exclusively due to urate oxidase. The nucleoids obviously contain a variety of other enzymes that may be more or less loosely associated with the insoluble components of these structures.
TL;DR: It is concluded from these studies that human amidophosphoribosyltransferase is an iron-sulfur protein and oxidation of this structure may be responsible for the marked lability of this enzyme in vitro.
TL;DR: It is suggested that H2O2 produced from O2− is decomposed to form OH· by the action of Fe-EDTA complex in the lipid peroxidation system and that OH· is a trigger of lipidperoxidation.
TL;DR: Agents which are believed to scavenge the hydroxyl radical (.OH), sodium benzoate, and mannitol, as well as scavengers of superoxide anion (O2-) or hydrogen peroxide, decreased C2H4 production, implicaing .OH as the oxidizing radical.
Abstract: Stimulated human alveolar macrophages were demonstrated to oxidize B-methyl proprionaldehyde (methional) or 2-keto-4-thiomethylbutyric acid to ethylene (C2H4). Agents which are believed to scavenge the hydroxyl radical (.OH), sodium benzoate, and mannitol, as well as scavengers of superoxide anion (O2-) or hydrogen peroxide, decreased C2H4 production, implicaing .OH as the oxidizing radical. Differences in C2H4 rpoduction, as well as oxygen uptake and O2- release between human alveolar macrophages and polymorphonuclear leukocytes, were also documented.