Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P30044 (antioxidant enzyme)
 8,037 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although the effects of cigarette smoking on a variety of diseases, from cancer through emphysema and cardiovascular illness are well documented, direct effects on the levels of macro- and micronutrients in the body are reported less frequently. In fact, imbalances in these nutrients may have a role in many of the pathological conditions attributed to smoking. Tobacco smoke contains numerous compounds emitted as gases and condensed tar particles, many of them being oxidants and prooxidants, capable of producing free radicals thus enhancing lipid peroxidation in biological membranes. Vitamin E, vitamin C, B-carotene and selenium are involved in the overall cellular anti-oxidant defense against deleterious effects of reactive oxygen species. Smoking has been shown to lower the level of vitamin C and B-carotene in plasma. Cadmium, naturally found in tobacco, decreases the bioavailability of selenium and acts antagonistically to zinc, a cofactor for the antioxidant enzyme, superoxide dismutase. Vitamin E, the principle lipid-soluble antioxidant, may be at suboptimal levels in tissues of smokers. In addition, tobacco constituents have been shown to reduce levels of several vitamins of the B-complex. Nutritional status in smokers may be further compromised by an inadequate diet. Data from the Second National Health and Nutrition Examination Survey indicates that smokers are less likely to consume fruits and vegetables, particularly those high in vitamin C and carotenes. Cessation of smoking is the obvious solution to ending cigarette-related problems. In the world as it is, however, the medical community should be responsible for making recommendations to lower the risk in smokers to tobacco related diseases. Nutritionists could have a role in this process. There exists a lively debate as to where levels of nutrients should be set. Additional vitamin C has already been recommended for smokers. Should other antioxidants also be increased? Arguments for the against are considered.
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PMID:Cigarette smoking-nutritional implications. 178 36

Lipid peroxidation induced by metals at sub-lethal levels, alter physiological and biochemical characteristics of biological systems. To counter the detrimental effects of the prooxidant activity of metals, a group of antioxidant enzyme systems function in the organisms. The present study was performed to investigate into the lipid peroxidation product formation due to the exposure to effects of the metals namely aluminium, lead and cadmium at sub-lethal concentrations and the biological response through protective antioxidant enzyme activity in the marine mussels, Perna viridis Lin.. This organism is a known bioindicator and bioconcentrator of metals in the environment. The results of the present study were: (a) accumulation of lead showed a definite linear increase during the period of exposure whereas aluminium and cadmium showed fluctuations. Mantle and gill tissues showed greater accumulation of metals when compared to digestive gland; (b) lead and aluminium induced lipid peroxidation was greater in tissues than the peroxidation induced by cadmium. Cadmium induced peroxidation was observed only after the day 7 of the exposure; (c) anti-oxidant enzymes activity levels were significantly higher in digestive gland and mantle than gills; (d) mantle was observed to significantly contribute to the organismal response to lipid peroxidation as indicated by high activity levels of anti-oxidant enzymes.
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PMID:Modulations in antioxidant enzymes in different tissues of marine bivalve Perna viridis during heavy metal exposure. 756 39

Peroxidative tissue damage has been reported to contribute to several pathological disorders. Despite high exposure to both exogenous and endogenous oxidant stress, the strong cell defence mechanism of the gastric mucosa protects mucosal epithelial cells against these noxious stimuli. However, some environmental factors involved in lipid peroxidation (such as cadmium), which disrupt gastric mucosal protection, may impair the mucosal barrier and facilitate the occurrence of gastric ulcers. In an experimental study to investigate this hypothesis, the level of cadmium-induced lipid peroxidation products (TBARS) and an antioxidant enzyme (SOD) were investigated. The mucin content (P < 0.01) and prostaglandin levels (P < 0.05) of mucosa as components of the gastric mucosal barrier were found to be significantly reduced in rats exposed to 15 ppm of cadmium in water for 30 days when compared with those of unexposed controls. TBARS levels in blood (P < 0.05) and mucosa (P < 0.001) increased markedly in cadmium-exposed animals whereas blood SOD levels remained unchanged. The significant correlation between TBARS and mucosal cadmium (r = 0.664, P < 0.01), as well as between cadmium and PGE2 (r = -0.719, P < 0.01), led to the conclusion that cadmium-induced lipid peroxidation is involved in the increased vulnerability of gastric mucosa to injurious stimuli in rats. This susceptibility may be responsible for the high incidence of stress-induced gastric ulcer in the population.
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PMID:Role of lipid peroxidation in cadmium-induced impairment of the gastric mucosal barrier. 792 76

Glutathione has been implicated to function in cytoprotection against cadmium toxicity. The mechanism by which glutathione plays this role has not been well understood. Because glutathione is an important antioxidant and several studies have shown that cadmium induces oxidative stress, this study was undertaken to determine whether development of cadmium resistance is linked to enhanced antioxidant activities. A cadmium-resistant subpopulation of human lung carcinoma A549 cells, which was developed by repeatedly exposing the cells to step-wise increased cadmium concentrations, was compared to a cadmium-sensitive one. The acquired cadmium resistance resulted from neither decreased cadmium uptake nor enhanced cellular metallothionein synthesis. Glutathione content, however, was markedly elevated in the cadmium-resistant cells. In contrast, the activities of the glutathione redox cycle related enzymes, glutathione peroxidase and reductase, were unchanged. Two other antioxidant enzymes, superoxide dismutase and catalase, were also not altered. The results suggest that the development of cadmium resistance in A549 cells unlikely results from enhanced antioxidant enzyme activities, although it is associated with elevated cellular glutathione levels. In addition, measurement of the mRNA and DNA levels for gamma-glutamylcysteine synthetase, the rate-limiting enzyme for glutathione biosynthesis, revealed that enhanced expression of the enzyme but not gene amplification is likely responsible for the elevation of cellular glutathione levels.
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PMID:Cadmium resistance in A549 cells correlates with elevated glutathione content but not antioxidant enzymatic activities. 858 53

Cross-resistance presents an obstacle in cancer chemotherapy. Cadmium is a potential carcinogen whose exposure has been shown in epidemiological and laboratory experiments to cause lung cancer. Cadmium also induces various forms of resistance in human lung carcinoma cells. This resistance may be shared by antineoplastic agents, which should be a concern for chemotherapy of cadmium-induced lung cancer. In the present study, two subpopulations of human lung carcinoma A549 cells with a different magnitude of resistance to cadmium toxicity were shown to have a parallel resistance to the cytotoxic action of Adriamycin (ADR), an important anticancer drug. Several factors were examined to investigate the mechanism(s) for the cross-resistance, including cellular metallothionein and glutathione (GSH) concentrations, glutathione S-transferase activity, mdr1 expression, and antioxidant enzyme activities including superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Only cellular GSH content was elevated consistently in the cadmium/ADR-resistant cells relative to the cadmium/ADR-sensitive cells. Treatment with buthionine sulfoximine, a specific inhibitor of GSH synthesis sensitized both cell lines to ADR only when the cellular GSH levels were depleted to about 5% of control. This BSO treatment, however, did not affect cell viability. Further study revealed that the cadmium/ADR-resistant cells have a greater capacity in recovery of cellular GSH content following BSO treatment. The results demonstrate that cross-resistance to ADR exists in cadmium-resistant human lung carcinoma A549 cells, and enhanced GSH synthesis capacity, rather than elevated levels of cellular GSH, may be related to this resistance.
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PMID:Decreased sensitivity to adriamycin in cadmium-resistant human lung carcinoma A549 cells. 911 95

The effect of cadmium ion (Cd) and ascorbic acid (Asc) on the induction of oxidative DNA damage and on the activities of antioxidant enzymes were investigated in human lymphoblastoid cells (AHH-1 TK+/-). Cd at low concentrations of 5-35 microM induced the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and caused nuclear DNA strand breaks. The formation both of 8-OHdG and of DNA strand breaks was dose-dependent at the low Cd concentration; both parameters were linearly correlated with each other (R = 0.932 and P = 0.0209). 8-OHdG formation by Cd plateaued at a Cd concentration of 50 microM. Asc also induced 8-OHdG formation, but it had no synergistic effect with Cd on the formation of 8-OHdG or DNA strand breaks. Cd at the concentration of 50 microM induced the nuclear activity of the antioxidant enzymes, catalase and superoxide dismutase (SOD). Furthermore, Cd caused a decrease in the concentration of reduced glutathione (GSH) and an increase in concentration of the oxidized form (GSSG). While Asc had no observable effect on SOD activity, it did increase nuclear catalase activity in cells. This effect on catalase was synergistic with that of Cd. The linear correlation between 8-OHdG and DNA strand breaks induced by Cd at the lower Cd concentrations (< or = 50 microM), suggested that the extent of formation of DNA strand breaks induced by Cd may be offset by their induction of the formation of 8-OHdG and antioxidant enzyme activities.
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PMID:Cadmium-induced 8-hydroxydeoxyguanosine formation, DNA strand breaks and antioxidant enzyme activities in lymphoblastoid cells. 914 17

The mechanism of cadmium-mediated hepatotoxicity has been the subject of numerous investigations, principally in hepatocytes. Although, some uncertainties persist, sufficient evidence has emerged to provide a reasonable account of the toxic process in parenchymal cells. However, there is no information about the effect of cadmium in other hepatic cell types, such as stellate cells (fat storing cells, Ito cells, perisinusoidal cells, parasinusoidal cells, lipocytes). Hepatic stellate cells (HSC) express a quiescent phenotype in a healthy liver and acquire an activated phenotype in liver injury. These cells play an important role in the fibrogenic process. The objective of this study was to investigate the effect of a 24 h treatment of low Cd concentrations in glutathione content, lipid peroxidation damage, cytosolic free Ca, antioxidant enzyme activities: glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase along with the capacity of this heavy metal to induce metallothionein II and alpha(1)collagen (I) in an hepatic stellate cell line (CFSC-2G). Cd-treated cells increased lipid peroxidation and the content of cytosolic free calcium, decreased glutathione content and superoxide dismutase, glutathione peroxidase and catalase activity. Cd was able to induce the expression of the metallothionein II and alpha(1)collagen (I) gene, that was not described in this cell type. Cadmium may act as a pro-fibrogenic agent in the liver probably by inducing oxidative damage by enhancing lipid peroxidation and altering the antioxidant system of the cells. Although, the exact role metallothionein induction plays in this process is unknown, it probably, provides a cytosolic pool of potential binding sites to sequester ionic Cd, thereby decreasing its toxicity.
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PMID:Cadmium induces alpha(1)collagen (I) and metallothionein II gene and alters the antioxidant system in rat hepatic stellate cells. 1175 84

Catalase, Mn-superoxide dismutase (MnSOD) and Cu,Zn-superoxide dismutase (CuZnSOD) activities were studied in rat liver and kidney 6-48 h after CdCl(2) intraperitoneal administration or 10-30 days daily oral CdCl(2) intake in drinking water. This approach provided some indications as to the sensitivity of each enzyme to cadmium toxicity. These experiments showed that the formation of thiobarbituric acid reactive substance (TBARS) did not strictly depend on how well the antioxidant enzyme worked. From in vitro experiments it appeared that TBARS removal by vitamin E did not restore the three enzyme activities at all. As for cadmium's inhibitory mechanism on catalase activity, our data, obtained in the pH range 6.0-8.0, are a preliminary indication that the negative effect of this metal is probably due to imidazole residue binding of His-74 which is essential in the decomposition of hydrogen peroxide. Cadmium inhibition of liver mitochondrial MnSOD activity was completely removed by Mn(2+) ions, suggesting that the reducing effect on this enzyme is probably due to the substitution of cadmium for manganese. We also observed the antioxidant capacity of Mn(2+) ions, since they were able to normalize the increased TBARS levels occurring when liver mitochondria were exposed to cadmium. The reduced activity of CuZnSOD does not seem to be due to the replacement of Zn by Cd, nor to the peroxides formed. As this enzyme activity was almost completely recovered after 48 h, we hypothesize that the momentary inhibition is imputable to a cadmium/enzyme interaction. This causes some perturbation in the enzyme topography which is critical for its catalytic activity. The pathological implications linked to antioxidant enzyme disorders induced by cadmium toxicity are discussed.
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PMID:Molecular inhibitory mechanisms of antioxidant enzymes in rat liver and kidney by cadmium. 1220 41

Salicylic acid (SA) plays a key role in plant disease resistance and hypersensitive cell death but is also implicated in hardening responses to abiotic stressors. Cadmium (Cd) exposure increased the free SA contents of barley (Hordeum vulgare) roots by a factor of about 2. Cultivation of dry barley caryopses presoaked in SA-containing solution for only 6 h or single transient addition of SA at a 0.5 mM concentration to the hydroponics solution partially protected the seedlings from Cd toxicity during the following growth period. Both SA treatments had little effect on growth in the absence of Cd, but increased root and shoot length and fresh and dry weight and inhibited lipid peroxidation in roots, as indicated by malondialdehyde contents, in the presence of Cd. To test whether this protection was due to up-regulation of antioxidant enzymes, activities and transcript levels of the H(2)O(2)-metabolizing enzymes such as catalase and ascorbate peroxidase were measured in control and SA-treated seedlings in the presence or absence of 25 microM Cd. Cd stress increased the activity of these enzymes by variable extent. SA treatments strongly or completely suppressed the Cd-induced up-regulation of the antioxidant enzyme activities. Slices from leaves treated with SA for 24 h also showed an increased level of tolerance toward high Cd concentrations as indicated by chlorophyll a fluorescence parameters. The results support the conclusion that SA alleviates Cd toxicity not at the level of antioxidant defense but by affecting other mechanisms of Cd detoxification.
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PMID:Salicylic acid alleviates the cadmium toxicity in barley seedlings. 1274 32

Saccharomyces cerevisiae mutant strains deficient in superoxide dismutase (Sod), an antioxidant enzyme, were used to analyze cadmium absorption and the oxidation produced by it. Cells lacking the cytosolic Sod1 removed twice as much cadmium as the control strain, while those deficient in the mitochondrial Sod2 exhibited poor metal absorption. Interestingly, the sod1 mutant did not become more oxidized after exposure to cadmium, as opposed to the control strain. We observed that the deficiency of Sod1 increases the expression of both Cup1 (a metallothionein) and Ycf1 (a vacuolar glutathione S-conjugate pump), proteins involved with protection against cadmium. Furthermore, when sod1 cells were exposed to cadmium, the ratio glutathione oxidized/glutathione reduced did not increase as expected. We propose that a high level of metallothionein expression would relieve glutathione under cadmium stress, while an increased level of Ycf1 expression would favor compartmentalization of this metal into the vacuole. Both conditions would reduce the level of glutathione-cadmium complex in cytosol, contributing to the high capacity of absorbing cadmium by the sod1 strain. Previous results showed that the glutathione-cadmium complex regulates cadmium uptake. These results indicate that, even indirectly, metallothionein also regulates cadmium transport.
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PMID:The effect of superoxide dismutase deficiency on cadmium stress. 1499 74


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