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Biomedical subjects

I Mavelli

Publications and source records attributed to I Mavelli.

50 records · Page 3Linked to original sources
PubMed1982

Superoxide dismutase, glutathione peroxidase and catalase in developing rat brain.

The specific activities of Cu,Zn- and Mn-superoxide dismutases, of glutathione peroxidase and of catalase, the enzymes considered to be specifically involved in the defence of the cell against the partially reduced forms of oxygen, were determined as the function of postnatal age in the early (up to 60 days) period of rat brain development. The enzymes were assayed in the cytoplasmic fraction, in the crude mitochondrial fraction including peroxisomes, and in the mitochondria. The results show that the temporal changes of these enzymes cannot be correlated with each other, thus indicating that they do not concertedly parallel the increasing activity of aerobic brain metabolism during development. Specifically the cytoplasmic fraction shows a gradual increase of the Cu,Zn-superoxide dismutase activity with age, whereas the glutathione peroxidase activity is constant from birth. Furthermore the increase of the mitochondrial Mn-superoxide dismutase as a function of postnatal age is more remarkable than that of the cytoplasmic Cu,Zn-enzyme. Higher activities of catalase in adult animals are detectable only in the subcellular fraction containing peroxisomes, because of the modest catalase activity of the brain. These results indicate independent regulation of the expression of these enzyme activities in the process of brain differentiation and point to a relative deficiency of enzymic protection of the brain differentiation and point to a relative deficiency of enzymic protection of the brain against potentially toxic oxygen derivatives. This situation is similar to the pattern already described in the rat heart and in rat and mouse ascites-tumour cells, at variance with the much more efficient enzyme pattern present in rat hepatocytes.

Aging↗
PubMed1981

Differential cytotoxicity of daunomycin in tumour cells is related to glutathione-dependent hydrogen peroxide metabolism.

Addition of 0.5mm-daunomycin, a quinone anti-cancer drug, causes severe inhibition of respiration in Ehrlich ascites cells, whereas Yoshida ascites cells were almost as resistant as rat hepatocytes. An inverse relationship appears to exist in the two types of tumour cells (which are both catalase-deficient) between the extent of cellular damage brought about by intracellular formation of superoxide anion occurring on reaction with O(2) of the drug free radical and the efficiency of the glutathione-mediated H(2)O(2)-detoxifying system.

Animals↗
PubMed1979

Differential sensitivity of tumor cells to externally generated hydrogen peroxide. Role of glutathione and related enzymes.

(1) Oxygen uptake and lactate production of different strains of ascites tumor cells were assayed after exposure to an extracellular photochemical system known to produce reactive oxygen derivatives. The various cells tested showed differential sensitivity to the treatment, ranging from nearly full inactivation of Ehrlich cells to nearly full resistance of Yoshida cells. (2) Glucose plus succinate added after the treatment reestablished basal oxygen uptake capacity suggesting that the cell membrane was the primary site of damage. This was confirmed by dye-permeabilization and protein leakage in sensitive cells. (3) H2O2 was shown to be the only relevant oxygen derivative in the production of cell damage: catalase was the only externally added agent that protected sensitive cells, and H2O2 (congruent to 10(-3) M) had the same effects as the photochemical treatment. (4) While the absence of catalase is a feature common to all tumors tested, sensitivity to H2O2 appears to be related to cellular levels of glutathione peroxidase and of its subsidiary enzymes glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione synthetase.

Animals↗
PubMed1977

Protoporphyrin IX sensitized photohemolysis: stoichiometry of the reaction and repair by reduced glutathione.

Protoporphyrin IX acts as a sensitizer in the photohemolysis of bovine erythrocytes by binding to a limited number of membrane sites. The cholesterol-specific antibiotic lucensomycin competes with protoporphyrin in binding to the membranes. The possibility of cholesterol peroxidation as a primary event in photohemolysis is supported by the repairing effect of exogenous cholesterol and by the increased susceptibility of the photosensitized erythrocytes to lucensomycin. Glutathione, if present within the erythrocyte, postpones the onset of lysis; if added after irradiation, it may repair the membrane damage and prevent hemolysis. This effect appears to be related to a redox reaction (possibly involving glutathione peroxidase) between reduced glutathione and the cholesterol peroxide molecules.

Animals↗
PubMed1976

Enzyme defense against reactive oxygen derivatives. II. Erythrocytes and tumor cells.

The enzymatic destruction of oxidizing products produced during metabolic reduction of oxygen in the cell (such as singlet oxygen, H2O2 and OH radical) involves the concerted action of superoxide dismutase-which removes O-2 and yields H2O2-and H2O2 removing enzymes such as catalase and glutathione peroxidase. A difference in distribution or ratio of these enzymes in various tissues may result in a different reactivity of oxygen radicals. It was found that in red blood cells superoxide dismutase and catalase are extracted in the same fraction as hemoglobin, while glutathione peroxidase appears to be "loosely" bound to the cellular structure. This suggests that in red blood cells catalase acts in series with superoxide dismutase against bursts of oxygen radicals formed from oxyhemoglobin, while glutathione & peroxidase may protect the cell membrane against low concentrations of H2O2. On the other hand, catalase activity is absent in various types of ascites tumor cells, while glutathione peroxidase and superoxide dismutase are found in the cytoplasm. However, the peroxidase/dismutase ratio is lower than in liver cells, and this may provide an explanation for the higher susceptibility of tumor cells to treatments likely to involve oxygen radicals.

Acetylcholinesterase↗
PubMedDate not supplied

Liposome-mediated increase of the superoxide dismutase content in human erythrocytes: characterization by electron spin resonance.

Room temperature electron spin resonance (ESR) spectroscopy, together with enzyme activity measurements, have been used to study the liposome-mediated enrichment of human red blood cells with superoxide dismutase. The ESR technique was found to be useful not only for qualitative and quantitative determinations, but also for demonstration of enzyme activity inside intact cells. The molecular properties of superoxide dismutase in relation to pharmacological and biotechnological applications are reviewed.

Drug Carriers↗
PubMedDate not supplied

Melatonin and oxidative damage in mice liver induced by the prooxidant antitumor drug, adriamycin.

Antioxidant properties have been attributed to melatonin; it seemed therefore worthwhile to determine its effects in relation to the prooxidant action of adriamycin, which contributes to its toxic and therapeutic effects. Melatonin effectively acts as a direct free radical scavenger in the concentration range of 20-100 microM as determined in vitro, using Fenton reaction as a source of free radicals that were determined by EPR using spin trapping method. Following the administration of a single i.v. dose of 28 mg/Kg or of 3 repeated i. p. doses of 5 mg/Kg adriamycin to CBA mice, glutathione levels in the liver cells were significantly reduced. When the treatment with adriamycin was preceded by the s.c. administration of 2 mg/Kg melatonin, the decrease in total and reduced glutathione concentrations was significantly prevented. A significant increase in lipid peroxidation was observed in liver cells after a single administration of adriamycin which was not attenuated by pretreatment with melatonin. These results indicate that further examination of the possible protective action of melatonin on the toxic effects of prooxidant antitumor drugs on normal and neoplastic tissues would be of interest also in relation to their chronotoxicological properties.

Animals↗