Plasma glutathione peroxidase

Plasma glutathione peroxidase Human Catalyse reduction of H202 by glutathione thus... 

Yao JK, Reddy RD, van Kammen DP. 1999. Human plasma glutathione peroxidase and symptom severity in schizophrenia. Biol Psychiatry 45 1512-1515. 

Modified expression of plasma glutathione peroxidase and manganese superoxide dismutase in human renal cell carcinoma. Electrophoresis 20,... 

Plasma from mammalia contains a selenoprotein that carries more than 50% of the selenium present. In rat, about 8% of the total selenium content is associated with this protein, selenoprotein P. A change in the selenium status of the rat leads to a rapid change of the selenium level attached to selenoprotein P, preferential to changes of other selenoproteins such as plasma glutathione peroxidase. ... 

Both cGPx and plasma glutathione peroxidase (pGpx) are widely used to monitor the selenium status in human... 

In the previous section, we have described some of the mechanisms that may lead to the fijrmation of lipid hydroperoxides or peroxyl radicals in lipids. If the peroxyl radical is formed, then this will lead to propagation if no chain-breaking antioxidants are present (Scheme 2.1). However, in many biological situations chain-breaking antioxidants are present, for example, in LDL, and these will terminate the peroxyl radical and are consumed in the process. This will concomitandy increase the size of the peroxide pool in the membrane or lipoprotein. Such peroxides may be metabolized by the glutathione peroxidases in a cellular environment but are probably more stable in the plasma comjxutment. In the next section, the promotion of lipid peroxidation if the lipid peroxides encounter a transition metal will be considered. 

Reduced scavenger capacity is deduced from studies demonstrating low plasma and cellular levels of antioxidants such as glutathione, vitamin E, thiols, magnesium and ascorbic acid, as well as reduced levels of scavenger enzymes such as neutrophil glutathione peroxidase and red cell superoxide dismutase (Lyons, 1991 Sinclair /., 1992). 

Kaji, H., Kurasaki, M., Ito, K., Saito, T., Saito, K., Niioka, T., Kojima, Y., Ohsaki, Y., Ide, H., Tsuji, M., Kondo, T. and Kawakami, Y. (1985). Increased lipoperoxide value and glutathione peroxidase activity in blood plasma of type II (non-insulin-dependent) diabetic women. Klin. Wochenschr. 63, 765-8. 

Other examples of possible damaging effects of radio frequency MFs on humans are the MF effects on cellular phones. Moustafa et al. [216] suggested that acute exposure to the MFs of commercially available cellular phones for 1, 2, or 4 h significantly increased plasma lipid peroxidation and decreased the activities of SOD and glutathione peroxidase in erythrocytes. 

Glutathione peroxidases catalyze the reductive decomposition of H202 or of organic peroxides by glutathione (G-SH) according to Eq. 15-58. At least three isoenzyme forms have been identified in mammals a cellular form,531 535-537 a plasma form, and a... 

Homocysteine decreases the bioavailability of nitrous oxide (NO) via a mechanism involving glutathione peroxidase (37). Tawakol et al. (38) reported that hyperhomocysteinemia is associated with impaired endothelium-dependent vasodilation in humans. Homocysteine impairs the NO synthase pathway both in cell culture (39) and in monkeys with hyperhomocysteinemia, by increasing the levels of asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor (40). Elevation of ADMA may mediate endothelial dysfunction during experimental hyperhomocysteinemia in humans (41). However, Jonasson et al. (42) did not find increased ADMA levels in patients with coronary heart disease and hyperhomocysteinemia, nor did vitamin supplementation have any effect on ADMA levels in spite of substantial plasma tHcy reduction,... 

In STZ-diabetic rat livers, the levels of mRNA of 1-gulonolactone oxidase, catalase, and glutathione peroxidase were decreased at 6 weeks, as well as that of plasma alpha 1 proteinase inhibitor 3.562 AA synthesis enzyme and recycling enzyme mRNAs were also decreased, as was the level of AA itself. It seems that the antioxidative defence system had been severely damaged. 

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