Significance of alterations in hepatic antioxidant enzymes. Primacy of glutathione peroxidase

Simmons, Thomas W.; Jamall, Ijaz S.

doi:10.1042/bj2510913

Cited by 57 publications

(20 citation statements)

References 31 publications

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“…during birth or artificial ventilation, the formation of reactive oxygen species may overwhelm the pulmonary antioxidant enzyme system. A pivotal role of GPX in protection against oxidant injury is supported by the finding that tissues can tolerate loss of catalase activity during oxidative stress, but not loss of GPX activity (44,45). In that respect, the present finding of a decrease in pulmonary GPX activity after artificial ventilation may indicate that the CDH rat neonate is at risk to develop oxygen-related lung damage.…”

Section: --~supporting

confidence: 69%

Nitrofen-Induced Diaphragmatic Hernias in Rats: Pulmonary Antioxidant Enzyme Activities

et al. 1992

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ABSTRACT. We developed an experimental rat model of sive care and artificial ventilation (I). Mortality still remains at congenital diaphragmatic hernia (CDH) to elucidate the 50% as a result of pulmonary hypoplasia with or without peretiology and pathogenesis of this serious congenital anom-sistent pulmonary hypertension (2). Those infants with severe aly in humans and in particular to study the effects of a respiratory compromise need maximal ventilatory support and short period of artificial ventilation on the CDH lung in are often subjected to high inflation pressures and high percentrelation to antioxidant defense mechanisms. CDH was ages of oxygen. The side effects of respiratory treatment are well induced in about 60% of the offspring by maternal exposure known, (3) and the clinical picture of bronchopulmonary dysplato 2,4-dichlorophenyl-pnitrophenylether (Nitrofen) during sia has become one of the major sequelae of neonatal intensive pregnancy. This herbicide resembles thyroid hormone in care (4). Only a few reports describe defense mechanisms against chemical structure. The lungs of fetal rats (d 19, 20, 21, oxidative stress in the human neonatal lung (5). Most experiand 22) were examined for protein and DNA content and mental studies on the development of AOA have been done in activity of superoxide dismutase, catalase, and glutathione small rodents (6, 7). The effect of artificial ventilation on the peroxidase (GPX). The same parameters were assessed in lung has been studied only in larger animals such as the baboon tracheotomized newborn rats after pressure-controlled ar-(8). tificial ventilation with either room air or pure oxygen We described a model in which CDH was induced in fetal during a short period of 5 h. In both CDH rats and controls, Sprague-Dawley rats by maternal exposure to a single dose of wet lung weight increased during gestation. At term, CDH 2,4-dichlorophenyl-pnitrophenylether (Nitrofen, Wako Chemirats had significantly lower mean lung weights than con-cals, Neuss, Germany) during pregnancy (9, 10). The incidence trols. Neither group differed in protein and DNA content of CDH in the treatment group was up to 60%. The diaphragper mg lung or superoxide dismutase, catalase, and GPX matic defect was mainly right-sided with severe hypoplasia of the activity before and at birth. After artificial ventilation of lung as reflected by decreased lung weight/body weight ratios. neonates with air and pure oxygen, superoxide dismutase No correlation was found between the size of the defect and the activity tended to decrease, whereas catalase activity re-ipsilateral and contralateral lung weights (9). Without artificial mained virtually unchanged in the CDH lung. However, ventilation, more than 80% of the CDH animals died within 2 GPX activity in the CDH lung was reduced to 80% of h after birth as a result of severe respiratory insufficiency. initial activity at term after ventilation with air and to 70%In the present study, we report 1 )

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confidence: 69%

Nitrofen-Induced Diaphragmatic Hernias in Rats: Pulmonary Antioxidant Enzyme Activities

et al. 1992

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“…In addition to this, the intracellular replenishment of GSH was hampered further because we found this time, as well as previously, that γ-GT, the enzyme responsible for GSH influx from extracellular sources, was again diminished in oesophageal cancer (Hunter et al, 1992). GSH-peroxidase, one of the GSH-depleting enzymes, is a more efficient metabolizer of hydrogen peroxide than catalase (CAT) (Simmons and Jamall, 1988). GS-Px is more important than either superoxide dismutase (SOD) or CAT in preventing peroxidation.…”

Section: Resultsmentioning

confidence: 99%

Glutathione-linked enzymes in benign and malignant oesophageal tissue

et al. 1999

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Oxyradicals are involved in multiple mutational events and can contribute to the conversion of healthy cells to cancer cells. Glutathione (GSH) and the GSH-replenishing enzymes keep the antioxidant status of normal cells at a level where they can avert oxyradical derived mutations. The aim of this study was to determine whether in cancer cells the GSH-replenishing, GSH antioxidant and GSH-depleting enzymes were not at appropriate levels and therefore not able to protect cancer cells adequately against oxyradical-induced mutations. Cancer of the oesophagus was chosen since it is the most common gastrointestinal malignancy in South African Blacks. Biopsies and blood from 31 patients with cancer of the oesophagus and 29 non-cancer patients were assessed for these enzymes. The mean activity of the antioxidant and depleting enzyme GSH-peroxidase was elevated significantly by twofold in the cancer tissue compared to normal tissue. However, the activity of the replenishing enzyme GSSG-reductase and the level of the depleting enzyme GSH-s-transferase P1-isoenzyme were significantly reduced by 23% and 33% respectively. As in a previous paper we found that GSH was depleted and γ-glutamine transpeptidase was diminished in oesophageal cancer. There can be two reasons for GSH depletion. Firstly, elevated GSH–peroxidase will use more GSH in an attempt to cope with the excessive production of oxyradicals as revealed by elevated lipid peroxidation; this was, as shown by us before, elevated sixfold in oesophageal cancer. Secondly, if little replenishment of GSH occurred the level of GSH would become lower. This was confirmed by our findings that the activities of the replenishing enzymes were significantly diminished in oesophageal cancer tissue. Contrary to what was expected, the other depleting enzyme GSH-s-transferase P1 was not elevated in cancer tissue but was significantly lower. However, in the blood of the same patients it was significantly elevated. An explanation for this phenomenon is that, although the production of GST-P1 was enhanced in cancer, it did not show because it was rapidly extruded into the blood by an unknown mechanism operational only in cancer cells. © 1999 Cancer Research Campaign

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“…However, these enzymes differ considerably in their Michaelis constants (K M ) and thus in the affinity for this substrate. Peroxidase is located in the cytosol and mitochondria of the cell and acts when H 2 O 2 concentrations are low (of the order of micromoles), whereas CAT is found mainly in peroxisomes and acts when the concentration of this peroxide is high (of the order of millimoles) (Simmons and Jamall, 1988). Therefore, both enzymes are used when hydrogen peroxide concentration in the cell is high.…”

Section: Discussionmentioning

confidence: 99%

Activity of antioxidant enzymes in the liver of wild boars (Sus scrofa) from aselenium-deficient area depending on sex, age, and season of the year

Jankowiak¹,

Pilarczyk²,

Drozd³

et al. 2015

Turk J Biol

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superoxide dismutase (SOD, EC 1.5.1.1) is the primary enzyme that protects cells against the effects of free radicals. This enzyme catalyzes the dismutation of the superoxide radical anion to hydrogen peroxide (H 2 O 2 ). While not being a free radical, this molecule is the main source of hydroxyl radical (•OH), which is highly reactive and toxic to cellular macromolecules (Limón-Pacheco and Gonsebatt, 2009). Hydrogen peroxide is reduced to water and molecular oxygen due to glutathione peroxidase (GSH-Px, EC 1.11.1.9) and/or catalase (CAT, EC 1.11.1.6) (Lykkesfeldt and Svendsen, 2007). GSH-Px has a greater affinity for H 2 O 2 than does CAT, eliminating H 2 O 2 at its already low concentrations in the cell in contrast to CAT, which acts when H 2 O 2 concentrations are high (Simmons and Jamall, 1988). Glutathione peroxidases are glutathionedependent enzymes. Both selenium-dependent (Se-GSH-Px, EC 1.11.1.9) and nonselenium-dependent (non-Se-

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Significance of alterations in hepatic antioxidant enzymes. Primacy of glutathione peroxidase

Cited by 57 publications

References 31 publications

Nitrofen-Induced Diaphragmatic Hernias in Rats: Pulmonary Antioxidant Enzyme Activities

Nitrofen-Induced Diaphragmatic Hernias in Rats: Pulmonary Antioxidant Enzyme Activities

Glutathione-linked enzymes in benign and malignant oesophageal tissue

Activity of antioxidant enzymes in the liver of wild boars (Sus scrofa) from aselenium-deficient area depending on sex, age, and season of the year

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