Showing papers on "Catalase published in 1992"
TL;DR: The data suggest that ROS induce a chain of events leading to sperm immobilization, that axonemes are affected, and that limited endogenous repair mechanisms exist to reverse these damages.
Abstract: Mammalian spermatozoa are sensitive to oxygen-induced damages mediated by lipid peroxidation of the cell membrane. The aim of this study was to evaluate whether reactive oxygen species (ROS) could also induce axonemal damage. When Percoll-separated spermatozoa were treated with hydrogen peroxide, or the combination xanthine and xanthine oxidase (X + XO), there was a progressive decrease, leading to a complete arrest, in sperm flagellar beat frequency. Once demembranated in a medium containing magnesium adenosine triphosphate (Mg.ATP), ROS-immobilized spermatozoa still reactivated motility; however, the percentage and duration of motility obtained in these tests gradually decreased to zero in the next hour. In 50% of the cases, motility of intact spermatozoa spontaneously reinitiated after 6 to 24 hours of immobilization due to ROS treatment, although with percentages and beat frequencies lower than those of untreated spermatozoa. Studies using ROS scavengers (such as catalase, superoxide dismutase, and dimethylsulfoxide) indicated that hydrogen peroxide was the most toxic of the ROS involved, but that .O2- and .OH probably also played a role in immobilization of spermatozoa by ROS. The data suggest that ROS induce a chain of events leading to sperm immobilization, that axonemes are affected, and that limited endogenous repair mechanisms exist to reverse these damages.
603 citations
TL;DR: In this paper, the effect of cadmium acetate on the chlorophyll and heme levels of mung bean (Phaseolus vulgaris L. cv. K-16) seedlings was investigated.
Abstract: Germinating seedlings of mung bean (Phaseolus vulgaris L. cv. K-16) were treated with different concentrations of cadmium acetate (10, 50 and 100 μM). Cd2+ lowered the chlorophyll and heme levels. The level of lipid peroxides were higher on day 3 than on day 6. However, Cd2+ treatment significantly enhanced the level of lipid peroxides. Similarly, a dose-dependent induction of lipoxygenase (EC 1.13.11.12) activity was observed with Cd2+ treatment. Further, the activities of antioxidant enzymes such as superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) were decreased. Our results suggest that lipoxygenase-mediated accumulation of lipid peroxides on the one hand and inhibition of free radical scavenging enzymes like superoxide dismutase and catalase on the other caused a pronounced reduction in the chlorophyll and heme levels of the seedlings. The experiments conducted on the effect of Cd2+ on dark-grown seedlings did not conform with the result of light-grown seedlings. Though chlorophyll and heme levels decreased in a dose-dependent manner, no accumulation of lipid peroxides was observed, suggesting that the inhibition of chlorophyll synthesis by Cd2+ is achieved both by reaction with constituent biosynthetic enzymes as well as peroxide-mediated degradation.
509 citations
TL;DR: Hydrogen peroxide was generated in vitro by horseradish peroxidase in the presence of NADH or NADPH and guaiacol was also not oxidized in the absence of either H 2 O 2 or peroxIDase.
Abstract: Hydrogen peroxide was generated in vitro by horseradish peroxidase in the presence of NADH or NADPH. When peroxidase was inactivated by heating (30 min at 100 C) or catalase was added to the reaction mixture, little or no hydrogen peroxide was generated as measured by a guaiacol oxidation assay. In the absence of either H 2 O 2 or peroxidase, guaiacol was also not oxidized. Guaiacol oxidation was also observed when either NADH was replaced by NAD and malate in the presence of malate dehydrogenase or NADPH was replaced by NADP and glucose-6-phosphate in the presence of glucose-6-phosphate dehydrogenase (...)
417 citations
TL;DR: Assay conditions for Se-GPX and total GPX activities were determined which optimized the difference between the non-enzymic and enzymic rates of reaction, andCatalase properties were consistent with a catalase, rather than aCatalase-peroxidase, and the pH-dependence and temperature-dependency of GPX activity were different with H2O2 or CHP as substrate, and these and other observations indicate the existence of a distinct Se
Abstract: Antioxidant enzymes function to remove deleterious reactive oxygen species, including the superoxide anion radical and H2O2. Subcellular distributions and optimal and other properties of catalase (EC. 1.11.1.6), superoxide dismutase (SOD; EC. 1.15.1.1), selenium-dependent glutathione peroxidase (Se-GPX; EC. 1.11.1.9) and total glutathione peroxidase (GPX) activities were determined in the digestive gland of the common musselMytilus edulis L. by spectrophotometric and cytochemical/electron microscopic (catalase) techniques. Assay conditions for Se-GPX and total GPX activities were determined which optimized the difference between the non-enzymic and enzymic rates of reaction. General peroxidase activity (guaiacol as substrate) (EC. 1.11.1.7) was not detectable in any subcellular fraction. Catalase was largely, if not totally, peroxisomal, whereas SOD and GPX activities were mainly cytosolic. Distinct mitochondrial (Mn-SOD) and cytosolic (CuZn-SOD) SOD forms were indicated. Catalase properties were consistent with a catalase, rather than a catalase-peroxidase. The pH-dependence and temperature-dependence of GPX activity were different with H2O2 or CHP as substrate, and these and other observations indicate the existence of a distinct Se-GPX. Under saturating or optimal (GPX) assay conditions, the apparent Michaelis constantsKm (mM) were: catalase, 48 to 68 (substrate, H2O2); Se-GPX, 0.11 (H2O2) and 2.0 (glutathione); and total GPX, 2.2 (eumene hydroperoxide) and 1.2 (glutathione). Calculated catalase activity was 2 to 4 orders of magnitude greater than Se-GPX activity over an [H2O2] of 1 to 1000 μM. The results are discussed in relation to theoretical calculations of in vivo oxyradical production and phylogenetic differences in antioxidant enzyme activities.
321 citations
TL;DR: Immunoblotting assays indicated that in light, but not in darkness, steady-state levels of catalase and of the D1 protein strongly declined during treatments with salt, heat shock, or translation inhibitors that block repair synthesis.
Abstract: The enzyme catalase (EC 11116) is light sensitive and subject to a rapid turnover in light, similar to the D1 reaction center protein of photosystem II After 3 h of preadaptation to darkness or to different light intensities (90 and 520 μmol m−2 s−1 photosynthetic photon flux density), sections of rye leaves (Secale cereale L) were labeled for 4 h with l-[35S]methionine From leaf extracts, catalase was immunoprecipitated with an antiserum prepared against the purified enzyme from rye leaves Both incorporation into catalase and degradation of the enzyme polypeptide during a subsequent 16-h chase period increased with light intensity At a photon flux density of 520 μmol m−2 s−1, the apparent half-time of catalase in rye leaves was 3 to 4 h, whereas that of the D1 protein was much shorter, about 15 h Exposure to stress conditions, such as 06 m NaCl or a heat-shock temperature of 40°C, greatly suppressed both total protein synthesis and incorporation of the label into catalase and into the D1 protein Immunoblotting assays indicated that in light, but not in darkness, steady-state levels of catalase and of the D1 protein strongly declined during treatments with salt, heat shock, or translation inhibitors that block repair synthesis Because of the common property of rapid photodegradation and the resulting dependence on continuous repair, declines in catalase as well as of the D1 protein represent specific and sensitive indicators for stress conditions that suppress the translational activities of leaves
237 citations
TL;DR: It is suggested that the release of active oxygen species from cultured spruce cells triggered by cell-wall-derived fungal elicitors depends on external Ca2+ and a protein-kinase activity.
Abstract: Cell-wall components from the ectomycorrhizal fungi Amanita muscaria and Hebeloma crustuliniforme and from the spruce pathogen Heterobasidion annosum elicited a transient release of active oxygen species from cultured spruce cells (Picea abies (L.) Karst.). Since the detection of active oxygen was suppressed by catalase, H2O2 was assumed to be the prevailing O2 species. On the other hand, superoxide dismutase enhanced the concentration of detectable H2O2 indicating that the superoxide anion was formed before dismutating to H2O2. The elicitors induced the formation of active oxygen in a dose-dependent manner. Interestingly, elicitors from mycorrhizal fungi had a lower H2O2-inducing activity than equal amounts of cell-wall preparations from the pathogen H. annosum. In Ca2+-depleted medium the production of active oxygen by elicitor-treated spruce cells was suppressed. Additionally, the ionophore A 23187 induced active oxygen formation in a medium with Ca2+ but not in a Ca2+-depleted medium. Furthermore, the protein-kinase inhibitor staurosporine inhibited the oxidative burst. At a concentration of 34 nM the effect was diminished to 50%. From these results it is suggested that the release of active oxygen species from cultured spruce cells triggered by cell-wall-derived fungal elicitors depends on external Ca2+ and a protein-kinase activity. In these respects the effect shows similarities with the well-studied respiratory burst of mammalian neutrophils.
235 citations
TL;DR: The skin-damaging effects of UVA appear to result from type II, oxygen-mediated photodynamic reactions in which UVA or near-UV radiation in the presence of certain photosensitizing chromophores leads to the formation of reactive oxygen species.
Abstract: In this paper, the role of reactive oxygen species in photoaging is presented. Many photosensitizing agents are known to generate reactive oxygen species (singlet oxygen (1O2), superoxide anion (O2.-) and .OH radicals). Although photoaging (dermatoheliosis) of human skin is caused by UVB and UVA radiation, the hypothesis tested here in the pathogenesis of photoaging of human skin is the free radical theory involving the generation of reactive oxygen species by UVA (320-400 nm) radiation and their damaging oxidative effects on cutaneous collagen and other model proteins. The UVA-generated reactive oxygen species cause cross-linking of proteins (e.g. collagen), oxidation of sulfydryl groups causing disulfide cross-links, oxidative inactivation of certain enzymes causing functional impairment of cells (fibroblasts, keratinocytes, melanocytes, Langerhans cells) and liberation of proteases, collagenase and elastase. The skin-damaging effects of UVA appear to result from type II, oxygen-mediated photodynamic reactions in which UVA or near-UV radiation in the presence of certain photosensitizing chromophores (e.g., riboflavin, porphyrins, nicotinamide adenine dinucleotide phosphate (NADPH), etc.) leads to the formation of reactive oxygen species (1O2, O2.-, .OH). Four specific observations are presented to illustrate the concept: (1) the production of 1O2 and O2.- by UVB, UVA and UVA plus photosensitizing agents (such as riboflavin, porphyrin and 3-carbethoxypsoralens) as a function of UV exposure dose, the sensitizer concentration and the pH of the irradiated solution; (2) the formation of protein cross-links in collagen, catalase and superoxide dismutase by 1O2 and O2.- (.OH) and the resulting denaturation of proteins and enzyme activities as a function of UVA exposure dose; (3) the protective role of selective quenchers of 1O2 and O2.- (e.g. alpha-tocopherol acetate, beta-carotene, sodium azide, ascorbic acid, etc.) against the photoinactivation of enzymes and the prevention of the protein cross-linking reaction; (4) the possible usefulness of certain antioxidants or quenchers that interact with the UVA-induced generation of reactive oxygen species in the amelioration of the process of photoaging.
222 citations
TL;DR: In this article, the authors reviewed several reactions pertinent to remediating contaminated groundwaters via hydrogen peroxide (H2O2) addition, including microbial catalase and several inorganic catalysts such as iron oxide species.
210 citations
TL;DR: The effective low-temperature ranges inducing photoinactivation of catalase differed significantly for chilling-tolerant and chilling-sensitive plants and preferential and rapid declines are generally to be expected in light whenever translation is suppressed by stress actions.
Abstract: Severe photoinactivation of catalase (EC 1.11.1.6) and a decline of variable fluorescence (Fv), indicating photoinhibition of photosynthesis, were observed as rapid and specific symptoms in leaves exposed to a high heat-shock temperature of 40°C as well as in leaves exposed to low chilling temperatures in white light of only moderately high photosynthetic photon flux density of 520 μE m−2 s−1. Other parameters, such as peroxidase (EC 1.11.1.7), glycolate oxidase (EC 1.1.3.1), glutathione reductase (EC 1.6.4.2), or the chlorophyll content, were hardly affected under these conditions. At a compatible temperature of 22°C, the applied light intensity did not induce severe photoinactivations. In darkness, exposures to high or low temperatures did not affect catalase levels. Also, decline of Fv in light was not related to temperature sensitivity in darkness. The effective low-temperature ranges inducing photoinactivation of catalase differed significantly for chilling-tolerant and chilling-sensitive plants. In leaves of rye (Secale cereale L.) and pea (Pisum sativum L.), photoinactivation occurred only below 15°C, whereas inactivation occurred at 15°C in cucumber (Cucumis sativus L.) and maize (Zea mays L.). The behavior of Fv was similar, but the difference between chilling-sensitive and chilling-tolerant plants was less striking. Whereas the catalase polypeptide, although photoinactivated, was not cleaved at 0 to 4°C, the D1 protein of photosystem II was greatly degraded during the low-temperature treatment of rye leaves in light. Rye leaves did not exhibit symptoms of any major general photodamage, even when they were totally depleted of catalase after photoinactivation at 0 to 4°C, and catalase recovered rapidly at normal temperature. In cucumber leaves, the decline of catalase after exposures to bright light at 0 to 4°C was accompanied by bleaching of chlorophyll, and the recovery observed at 25°C was slow and required several days. Similar to the D1 protein of photosystem II, catalase differs greatly from other proteins by its inactivation and high turnover in light. Inasmuch as catalase and D1 protein levels depend on continuous repair synthesis, preferential and rapid declines are generally to be expected in light whenever translation is suppressed by stress actions, such as heat or chilling, and recovery will reflect the repair capacity of the plants.
208 citations
TL;DR: Data suggest that H. pylori-activated neutrophils promote gastric mucosal cell injury and that monochloramine plays a unique and important role in this process.
Abstract: The role of neutrophil and its chlorinated oxidant were investigated in Helicobacter pylori-induced gastric mucosal injury in vitro. Luminol-dependent chemiluminescence (ChL) was used to detect neutrophil-derived oxidants. ChL activity was significantly elevated when neutrophils were incubated in H. pylori, indicating that H. pylori actually elicits oxidative burst of neutrophils. To assess whether H. pylori-activated neutrophils exert the cytotoxicity for gastric mucosal cells, rabbit gastric mucosal cell was monolayered in culture wells and labeled with a fluorescence dye, 2',7'-bis(2-carboxyethyl)-5(6)carboxy-fluorescein, which is retained in the intracellular space as long as the cell membrane is intact. Labeled cells were coincubated with neutrophils and H. pylori. We inferred from the cytotoxicity index (specific %cytotoxicity), which was calculated from fluorometrical measurements of supernatant and lysate, that the mucosal cells were significantly damaged by H. pylori-activated neutrophils. This injury was largely attenuated by eliminating urea from the incubation mixture or by acetohydroxamic acid, a potent urease inhibitor. Additionally, the scavengers of neutrophil-derived oxidants, including taurine, methionine, and catalase, also attenuated this injury. Cultured mucosal cells that were exposed to the solution containing monochloramine (an oxidant yielded by reaction of hypochlorous acid and ammonia) were highly damaged compared with cells exposed to hypochlorous acid or hydrogen peroxide at physiological concentrations. These data suggest that H. pylori-activated neutrophils promote gastric mucosal cell injury and that monochloramine plays a unique and important role in this process.
207 citations
TL;DR: A new aspect of interactions among insect herbivores and defensive chemistry of plants in the regulation of oxygen toxicity exerted by pro-oxidant allelochemicals is described in this paper.
TL;DR: Observations suggest that the diabetic rat aorta releases more spontaneous EDRF than controlAorta; however, the activity of EDRf on vascular smooth muscle tone is masked by increased destruction by oxygen-derived free radicals.
Abstract: The interaction of endothelium-derived relaxing factor (EDRF) and oxygen-derived free radicals may potentially play an important role in the pathophysiology of complications associated with diabetes. In the present study, we investigated spontaneous EDRF release in diabetic rat aorta that is unmasked by the addition of superoxide dismutase (SOD). SOD produced a significantly greater relaxation in diabetic aorta compared with control aorta using both aortic ring and bioassay preparations. This relaxation was unaltered by pretreatment with catalase or indomethacin. Removal of the endothelium or pretreatment with either NG-monomethyl-L-arginine or methylene blue eliminated SOD-induced relaxation in both control and diabetic rings. Measurement of antioxidant enzymes revealed an elevation in catalase in diabetic aorta, with no difference in the SOD or glutathione peroxidase activity. The increase in catalase activity suggests increased exposure of diabetic aorta to hydrogen peroxide. Pretreatment of rings with the catalase inhibitor, 3-amino-1,2,4-triazole, attenuated the SOD-induced relaxation in diabetic aortic rings but had no effect in control aortic rings. In summary, our observations suggest that the diabetic rat aorta releases more spontaneous EDRF than control aorta; however, the activity of EDRF on vascular smooth muscle tone is masked by increased destruction by oxygen-derived free radicals.
TL;DR: The specificity of the IF-induced cell responses is demonstrated and the possibility that active oxygen species were involved in the initial host reaction to these elicitors are confirmed.
Abstract: Intercellular fluid (IF) obtained from tomato (Lycopersicon esculentum L.) leaflets colonized by Cladosporium fulvum Cooke contains specific elicitors that induce necrosis in tomato cultivars resistant to the race of C. fulvum used to produce the IF. The responses of cell-suspension cultures produced from tomato lines near-isogenic for resistance genes Cf 4 and Cf 5 to IF produced from leaves infected by races 4 (virulent on Cf 4 but not Cf 5 plants), 2.4.5, and 2.4.5.9 (both virulent on Cf 4 and Cf 5 plants) were used to investigate the possibility that active oxygen (AO) species were involved in the initial host reaction to these elicitors. Concurrently, the same assays were used to determine if the cell lines retained the elicitor specificity of the original plants. An IF/cell combination that gives an incompatible reaction in leaves (race 4 IF and Cf 5 cells) showed reduced oxygen uptake and increases in malonaldehyde (a product of lipid peroxidation); cytochrome c reducing activity, which was inhibited by superoxide dismutase (SOD) (an assay for superoxide); luminol-dependent chemiluminescence (an assay for several AO species); activity of extracellular peroxidases; and extracellular phenolic compounds. In contrast, compatible combinations (IF from races 2.4.5 or 2.4.5.9 and Cf 4 or Cf 5 cells; race 4 IF and Cf 4 cells) did not exhibit any of these changes. The addition of catalase, SOD, ascorbate (a scavenger of superoxide), mannitol (a scavenger of the hydroxyl radical), KCN, or salicyl hydroxamic acid (both inhibitors of peroxidases) prior to IF treatment reduced the IF-induced increases in malonaldehyde and extracellular phenolics. Catalase was an effective inhibitor of the IF-induced changes in oxygen uptake and cytochrome c reducing activity. These results demonstrate the specificity of the IF-induced cell responses and confirm that AO species are involved in the initial cell response.
TL;DR: The data of both studies increase support for the notion that acetaldehyde is produced directly in the brain and that it may be the agent mediating some of the psychopharmacological properties of ethanol and be one of the factors determining the propensity of an animal to voluntarily consume ethanol.
TL;DR: Enhanced levels of catalase did not prolong the life span of flies, nor did they provide improved protection against oxidative stress induced by hyperoxia or paraquat treatment, however, enhanced resistance to hydrogen peroxide was observed in the overexpressors.
TL;DR: Active oxygen species such as H2O2 may have an important role in the initiation of carcinogenesis within the target cell population of rats with a single carcinogenic dose of CdCl2.
Abstract: Treatment of rats with a single carcinogenic dose of CdCI2 (i.e., 30 nmol/kg) caused severe hemorrhagic damage in the testis within the first 12 h after the metal. Subsequently, atrophy with calcification developed in the next 2–3 mo. Atrophied tissues regenerated during the 1 yr after exposure. Twelve hours after exposure to the Cd treatment, lipid peroxidation levels, Fe content, and cellular production of H2O2 were remarkably elevated in testicular Leydig cells, the target cell population for Cd carcin‐ogenesis. At the same time, glutathione peroxidase activity rose, glutathione reduc‐tase and catalase activities were reduced, and superoxide dismutase activity was unchanged. Xanthine oxidase activity in Leydig cells was also elevated at 6 and 9 h after the Cd treatment. Reduced glutathione in testes was decreased and oxidized glutathione was increased 12 h after exposure to the metal. These facts suggest that the carcinogenic doses of Cd induced oxidative stress while compromising cellular defense mech...
TL;DR: In this paper, a structure-activity study of fourteen chemically related flavonoids was conducted to evaluate their abilities to inhibit glutathione reductase (GR) in a N 2 atmosphere, which implicates a role for oxygen in the mechanism of inhibition.
TL;DR: It is shown, for the first time, that long-term intraventricular administration of NGF significantly increases in old animals the activity of key enzymes involved in the metabolic degradation of superoxide radicals and hydrogen peroxide.
TL;DR: Cisplatin does not directly increase lipid peroxidation in vitro; therefore, the increase of lipid peroxide in the kidneys of these rats treated with cisplatin can be attributed to a decrease in the activities of lipidperoxide-protecting enzymes.
TL;DR: In this article, the effect of drought on alfalfa leaves was investigated and the potential of the leaves to produce ethylene was shown to increase with the severity of the stress.
Abstract: Exchange rates of CO2 and H2O and metabolism of hydrogen peroxide have been measured in leaves of alfalfa ev. Aragon) under drought stress. The inhibitory effect of drought upon photosynthesis depended on the severity of the stress treatment. Leaf water potential (Ψleaf) down to,-2.8 MPa reduced CO2 availability due to stomatal closure and inhibited the rate of photosynthesis. Leaf water potential lower than,-2.8 MPa directly affected CO2 fixation, although CO2 was not limiting. Transpiration was more affected by stornatal closure than photosynthesis, which led to am apparent improvement in WUE (water use efficiency). Alfalfa leaves with Ψleaf lower than,-2.0 MPa had an increased quantum requirement, probably due to the severe stress effect on photoenergetic reactions.
Ethylene evolution from alfalfa leaves increased when they were subjected to Ψleaf of,- 1.6 MPa. Under more severe stress, the leaves showed low or almost no ethylene production. In parallel with the increase in ethyiene production, alfalfa leaves exhibited an increased membrane lipid peroxidation index (maloridialdehyde content) and an increased peroxide content. Superoxide disinutase activity (SOD; EC 1.15.1.1) was not affected by drought stress. Catalase (EC 1.11.1.6) was inhibited at slight stress, but significantly increased at a Ψleaf of -2.0 MPa. Peroxidase (EC 1.11.1.7) was progressively inhibited as drought stress developed. The possible implication of reactive O2 intermediates in drought stress-induced senescence of alfalfa leaves is discussed in the light of the pattern of enzymatic scavenging systems.
TL;DR: The study of the bacterial response to hydrogen peroxide has given general insights into how cells defend against deleterious oxidants, suggesting that direct oxidation of the OxyR protein brings about a conformation change by which OxyR senses an oxidative stress signal and then activates the expression of defense activities.
Abstract: The study of the bacterial response to hydrogen peroxide has given general insights into how cells defend against deleterious oxidants. Treatment of Salmonella typhimurium and Escherichia coli cells with low doses of hydrogen peroxide results in the induction of 30 proteins and resistance to killing by higher doses of hydrogen peroxide. The expression of nine of the hydrogen peroxide-inducible proteins, including the antioxidant enzymes catalase, glutathione reductase and an alkyl hydroperoxide reductase, is controlled by the positive regulator oxyR. Strains carrying deletions of the oxyR gene are hypersensitive to hydrogen peroxide and have increased levels of spontaneous mutagenesis during aerobic growth. The OxyR protein is homologous to the LysR-NodD family of bacterial regulatory proteins and binds to the promoters of oxyR-regulated genes. The oxidized, but not the reduced, form of the OxyR protein activates transcription of oxyR-regulated genes in vitro, suggesting that direct oxidation of the OxyR protein brings about a conformation change by which OxyR senses an oxidative stress signal and then activates the expression of defense activities.
TL;DR: expression of the catalase gene was studied in rat and human hepatoma cell lines and in rat liver, which was used as a control with high activity to understand the molecular basis of the marked decrease inCatalase activity of various tumor cells.
Abstract: For an understanding of the molecular basis of the marked decrease in catalase activity of various tumor cells, expression of the catalase gene was studied in rat and human hepatoma cell lines and in rat liver, which was used as a control with high activity. RNA blot hybridization profiles and run-on assays indicated that the decrease in catalase activity was due to depression of catalase gene transcription. Chloramphenicol acetyltransferase (CAT) assays for the fragments with various lengths of the 5'-flanking region (up to -4.5 kb from the ATG codon) of the catalase gene revealed the presence of several cis-acting elements involved in the negative regulation of transcription. The most-upstream element with the strongest activity (-3504 to -3364 bp), when linked to the catalase promoter region (-126 bp) of the CAT construct and subjected to an in vitro transcription assay, did not yield transcripts in experiments with the hepatoma nuclear extract, whereas the unlinked template did yield transcripts. A gel shift competition assay using hepatoma nuclear extract showed the core sequence of the silencer element to be 5'-TGGGGGGAG-3'. A homology search found that the same core sequence was also present in 5'-flanking regions of the albumin gene and of some other liver enzyme genes, the expression of which has been reported to be down regulated in some hepatoma cells. Southwestern (DNA-protein) analysis demonstrated that an approximately 35-kDa nuclear protein bound to the silencer element was present in hepatoma cells but not in rat liver cells.
TL;DR: Oxygen, redox-active metal ions, catalase, superoxide dismutase and the pharmacological agent aminoguanidine are expected to be influential on the rate and fate of fructosamine degradation.
Abstract: The degradation of fructosamines, formed from the non-enzymic glycation of proteins under physiological conditions, to advanced glycation end products was investigated by studying the model peptide fructosamine N epsilon-(1-deoxy-D-fructos-1-yl)hippuryl-lysine (DHL). At pH 7.4 and 37 degrees C in aerobic phosphate buffer, DHL degraded to form N epsilon-carboxymethyl-hippuryl-lysine, and hippuryl-lysine over a 29-day incubation period. The expected N epsilon-(3-lactato)hippuryl-lysine and 'hippuryl-lysylpyrraline' derivatives were not found. Superoxide radicals and hydrogen peroxide were formed during the degradation of DHL but were also both consumed during the degradation reaction. Reversal of the Amadori rearrangement was not a major fate of the fructosamine. The formation of N epsilon-carboxymethyl-hippuryl-lysine was decreased by desferrioxamine, catalase, superoxide dismutase, catalase with superoxide dismutase, anaerobic conditions and aminoguanidine. The formation of hippuryl-lysine was decreased by desferrioxamine, catalase and catalase with superoxide dismutase, but was increased by the addition of aminoguanidine. N epsilon-Carboxymethyl-serine and unmodified lysine residues are major peptide-based end products in the degradation of lysyl-fructosamine under physiological conditions. Oxygen, redox-active metal ions, catalase, superoxide dismutase and the pharmacological agent aminoguanidine are expected to be influential on the rate and fate of fructosamine degradation.
TL;DR: The recent development of enzyme-linked immunoassays for Cu, Zn- SOD, and Mn-SOD has facilitated accurate and reproducible determination of the protein levels of these enzymes in serum and other tissues.
Abstract: Publisher Summary This chapter discusses the clinical significance of immunoreactive Cu, Zn-SOD (superoxide dismutases)—widely distributed in the cytosol of tissues and Mn-SOD isozymes—with respect to diabetes, aging, cancer, and ischemia. SOD, catalase, and glutathione peroxidase comprise a major defense system against oxygen toxicity. Most aerobic cells have an enzyme system to eliminate active oxygen species because some of these active species are toxic. General properties of the mammalian isozymes are also described in the chapter. When conventional enzymatic assays are used to determine SOD activities in tissues, nonspecific reactions because of other proteins or low-molecular weight compounds possessing SOD-like activities in the tissues can cause erroneous results. Compared to enzymatic methods, immunochemical assay methods for SODs are more reliable and reproducible because the determinations are specific to the protein moiety and immunogenicity is not changed in the presence of inhibitors or activators of SOD in the tissues. The recent development of enzyme-linked immunoassays for Cu, Zn- SOD, and Mn-SOD has facilitated accurate and reproducible determination of the protein levels of these enzymes in serum and other tissues.
TL;DR: It is suggested that the vaginal flora of spermicide users could be depleted of hydrogen peroxide-producing lactobacilli, possibly increasing susceptibility to urogenital infection.
Abstract: Facultative anaerobic lactobacilli were recovered from the vaginas of 96.8% of 63 nonpregnant, healthy, premenopausal women. The predominant species were Lactobacillus jensenii, Lactobacillus acidophilus, and Lactobacillus casei. Of the women, 74.6% had hydrogen peroxide-producing lactobacilli, 22.2% had non-hydrogen peroxide-producing lactobacilli, and 3.2% had no lactobacilli. None of the 68 isolates had catalase activity. Some 68.2% of the isolates were inhibited by concentrations of less than or equal to 1% (wt/vol) of nonoxynol-9 (bactericidal for 73.3% of isolates, bacteriostatic for 26.7%). The remaining 31.8% could grow in all concentrations to 25% (wt/vol) of nonoxynol-9. All of the lactobacilli that were sensitive to nonoxynol-9 produced hydrogen peroxide whereas only 3 of 21 resistant strains were hydrogen peroxide producers. A significant correlation (P less than .001, chi 2 test) was found between hydrogen peroxide production and sensitivity to nonoxynol-9. It is suggested that the vaginal flora of spermicide users could be depleted of hydrogen peroxide-producing lactobacilli, possibly increasing susceptibility to urogenital infection.
TL;DR: The principal antioxidant enzyme, superoxide dismutase, was most sensitive to cryptorchidism, the activity in the abdominal testes being 74% or 85% (per gram of tissue or per whole testis, respectively); after impairment of the reactive oxygen detoxifying capacity, lipid peroxidation was increased in the abdomen testis by 46% on postoperative Day 7.
Abstract: The effect of experimental cryptorchidism on the level of oxidative stress and antioxidant functions in rat testis was studied. Adult male Sprague-Dawley rats were rendered unilaterally cryptorchid (by suturing one testis to the abdominal wall) and killed 1, 3, or 7 days after the operation. As an indicator of oxidative stress, lipid peroxidation was measured by the diene conjugation method in testis homogenates. The activities of the antioxidant enzymes were determined either in the 10,000 x g supernatant fraction (glutathione [GSH] peroxidase, GSH transferase, hexose monophosphate shunt) or in crude testis homogenates (superoxide dismutase, catalase). An expected reduction (48%) in weight of the abdominal testes was evident by postoperative Day 7. The catalytic activities per testis of superoxide dismutase (Cu/Zn form) and catalase were found to decrease in cryptorchidism. The effect was seen on the first postoperative day and was most profound on Day 7 after surgery. The principal antioxidant enzyme, superoxide dismutase, was most sensitive to cryptorchidism, the activity in the abdominal testes being 74% or 85% (per gram of tissue or per whole testis, respectively; p less than 0.01). After impairment of the reactive oxygen detoxifying capacity, lipid peroxidation was increased in the abdominal testis by 46% (p less than 0.01) on postoperative Day 7. Slight concomitant increases were detected in the activities of GSH-peroxidase (p less than 0.01), GSH-transferase (p less than 0.001), and the hexose monophosphate shunt (p less than 0.001). This effect was seen only when calculated per gram of tissue, not per whole testis.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The results suggest that the immunosuppressive effect of emodin may be partly mediated through hydrogen peroxide generated from semiquinone and regulated by arachidonic acid metabolites or byproducts.
TL;DR: The results demonstrate that the susceptibility of murine brains to lipid peroxidation increases with aging, which is consistent with the notion that reactive oxygen species may contribute to the aging process in mammalian brains.
TL;DR: The amount of MDA recovered after 30 min incubation with stimulated cells, as determined by MDA-thiobarbituric acid assay, was 25% lower than that recovered with resting cells, indicating that measurements of Mda production in living systems, in the presence of reactive oxygen species, could be underestimated.
TL;DR: The present results indicate that, in addition to displaying marked increases in the levels of brain CuZn‐SOD activity, SOD‐transgenic mice also exhibit increases in other enzymes that scavenge oxygen‐based radicals.
Abstract: Copper/zinc-superoxide dismutase (CuZn-SOD) transgenic mice overexpress the gene for human CuZn-SOD. To assess the effects of the overexpression of CuZn-SOD on the brain scavenging systems, we have measured the activities of manganese-SOD (Mn-SOD), catalase, and glutathione peroxidase (GSH-Px) in various regions of the mouse brain. In nontransgenic mice, cytosolic CuZn-SOD activity was highest in the caudate-putamen complex; this was followed by the brainstem and the hippocampus. The lowest activity was observed in the cerebellum. In transgenic mice, there were significant increases of cytosolic CuZn-SOD activity in all of these regions, with ratios varying from a twofold increase in the brainstem to 3.42-fold in the cerebellum in comparison with nontransgenic mice. Particulate Mn-SOD was similarly distributed in all brain regions, and its levels also were significantly increased in superoxide dismutase (SOD)-transgenic mice. In the brains of nontransgenic mice, cytosolic catalase activity was similar in all brain regions except the cortex, which showed less than 50% of the activity observed in the other regions. In transgenic mice, cytosolic catalase activity was significantly increased, with the cortex showing the greatest changes (133%) in comparison with nontransgenic mice. The smallest increases were observed in the hippocampus (34%). In contrast to what was observed for SOD and catalase, there were no significant changes in cytosolic GSH-Px activity in any of the brain regions examined. The present results indicate that, in addition to displaying marked increases in the levels of brain CuZn-SOD activity, SOD-transgenic mice also exhibit increases in other enzymes that scavenge oxygen-based radicals.(ABSTRACT TRUNCATED AT 250 WORDS)