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Biomedical subjects

A Azzi

Publications and source records attributed to A Azzi.

At least 235 records · Page 13Linked to original sources
PubMed1975

Superoxide radicals and hydrogen peroxide formation in mitochondria from normal and neoplastic tissues.

Mitochondria from beef heart, Morris hepatoma 3924A and Ehrlich ascites tumor (Lettré mutant) have been studied with respect to hydrogen peroxidase and superoxide radical formation and the presence of superoxide dismutase activity (EC 1.15.1.1, superoxide:superoxide oxidoreductase). The generation of superoxide radicals and hydrogen peroxide occurs at the level of the membrane, being present also in mitochondrial fragments. Hepatoma and ascites mitochondria have little or no superoxide dismutase activity. Superoxide radicals appear to be precursors of hydrogen peroxide formation, the reaction being catalyzed by superoxide dismutase.

Animals↗
PubMed1975

Molecular interactions of adenosine triphosphatase with the mitochondrial membrane as revealed by a spin label study.

Mitochondrial ATPase complex has been spin-labeled in the membrane using the inhibitor N-(2,2,6,6-tetramethylpeperidyl-1-OXYL)-N(cyclohexyl)carbodiimide (nccd). the amount of NCCD bound to mitochondrial fragments is 0.5 nmol/mg and cannot be dialyzed or extracted with ether, chloroform, or methanol. The electron paramagnetic resonance spectrum of NCCD bound to fragments is pH-sensitive, a greater label immobilization occurring at pH values lower or higher than 7. Ether extraction removes the ATPase inhibition by NCCD without detaching the label. This effect appears to be the consequence of the dislocation of some components of the ATPase complex. Removal of F1 natural inhibitor or of F1 does not affect the spectrum of NCCD bound to fragments, while the removal of oligomycin sensitivity-conferring protein produces an increase in the extreme splitting. Oligomycin sensitivity-conferring protein may thus interact with the NCCD binding component of the membrane. The isolation of the NCCD-binding proteolipid results in a large increase in the mobility of the label, but addition of dipalmitoyllecithin decreases the mobility of the label to the original level. Phospholipids are thus necessary to keep the NCCD-binding proteolipid in the native conformation.

Adenosine Triphosphatases↗
PubMed1975

On the formation of hydrogen peroxide and oxygen radicals in heart mitochondria.

The mitochondrial respiratory chain has been shown to produce H2O2 under certain conditions (Loschen, Flohe, and Chance, 1971; Boveris, Oshino, and Chance, 1972; Loschen, Azzui, and Flohe, 1973; Boveris and Chance, 1973). At least 1 percent of the total oxygen uptake in State 4 (Chance and Williams, 1956) in the presence of succinate is caused by H2O2 formation (Boveris et al., 1972). It was shown that the component responsible for mitochondrial H2O2 formation is located between the sites of the antimycin and rotenone inhibition (Loschen et al., 1971; Boveris et al., 1972). The possible physiological consequences of a respiratory chain-linked H2O2 formation is not yet understood. It would therefore be of significance to know whether oxygen radicals are involved in this process or not. It was recently suggested by Rotilio et al. (1973) that enzyme systems producing H2O2 via oxygen radicals are always closely associated with a superoxide dismutase. Thus, the existence of a mitochondrial superoxide dismutase located in the matrix space (Weisiger and Fridovich, 1973) prompted us to look for oxygen radicals as possible intermediates in the mechanism of the formation of mitochondrial H2O2. In the present communication we show that, under the same conditions in which H2O2 is formed in the mitochondrial respiratoy chain, oxygen radical formation can be demonstrated also. A possible relationship of this finding with lipid peroxidation and the toxic effects of hyperbaric oxygen is likely.

Animals↗
PubMed1974

[Drug hypersensitivity].

During a drug treatment we must keep in mind the possibility of adverse effects; therefore it would be useful to look for a satisfactory test, which can be carried out safely on patients to determine their reactivity. We have found satisfactory the blastic transformation test of sensitized lymphocytes, with the pharmacological agent. The research was carried out on the blood of patients hospitalized in the Department of Infectious Diseases (Ospedale Maggiore--Verona), with skin diseases and pretreated with drugs.

Aminopyrine↗