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D Serra

Publications and source records attributed to D Serra.

78 records · Page 5Linked to original sources
PubMedDate not supplied

Metabolic reduction of chromium, as related to its carcinogenic properties.

At variance with Cr(III), Cr(VI) compounds easily cross cell membranes and exert genotoxic effects. No metabolic oxidation of Cr(III) could be detected, whereas Cr(VI) reduction was observed in the presence of body fluids and subcellular fractions of various tissues from several animal species. The differential efficiency of this process may account for the selection of target tissues in Cr(VI) carcinogenesis. For instance, reduction by saliva and gastric juice may explain a lack of carcinogenicity by the oral route; reduction inside erythrocytes may explain a lack of carcinogenicity at a distance from administration sites; reduction by the epithelial-lining fluid of terminal airways and by alveolar macrophages may be consistent with the occurrence of thresholds in lung carcinogenesis. Liver preparations displayed the top efficiency in reducing Cr(VI), whereas skeletal muscle, i.e., a typical target in experimental Cr(VI) carcinogenesis, had no detectable activity. Bronchial tree and peripheral lung parenchyma preparations from almost 100 individuals reduced Cr(VI) to a variable extent. The efficiency of lung parenchyma and of isolated alveolar macrophages was enhanced in cigarette smokers. In rats, Cr(VI) reduction by lung preparations was significantly stimulated by the repeated i.t. instillation of Cr(VI) itself. Among the electron donors (chiefly GSH) and enzymatic mechanisms responsible for the intracellular Cr(VI) reduction, such as cytochrome P-450 reductase, glutathione reductase, and aldehyde oxidase, an important role can be ascribed to cytosolic DT diaphorase activity, usually catalyzing a 2-electron reduction.

Animals↗
PubMedDate not supplied

Improved respiratory CO2-He analysis for peripheral airways impairment detection. Utilization possibilities of a new computerized system in preventive medicine studies.

The authors illustrate the application possibilities in occupational and preventive medicine of a recently computerized system for the evaluation of peripheral ventilatory non-homogeneities with or without alveolar air trapping. The method consists of an improved individual multiple breath by breath test utilizing the analysis of the respiratory gases CO2 and He. It is based on the results of previous experimental measurements performed simultaneously in different pulmonary sectors an depends on the technical possibility of signalizing out-of-phase expired CO2-He mixtures at the end of the inert gas clearance when in subjects with peripheral respiratory disorders the two gases CO2 and He arrive at the mouth at different times, during the same expiration and cause different, opposite signals. The applied physiological reliability of the measurements was experimentally verified, their technical specificity was recently established. The use of a new computerized system allows actually automatic, on-line measurements under the control of the operator, following a standardized method. The resolution power of the signals is very high. The calculation of the results is performed by the software. The system is easy to transport and can be used in the field for screening on large groups of persons in preventive medicine inquiries and during occupational medicine checks. Quite recently it has been usefully employed during an investigation on 200 subjects, occupationally exposed (policemen of the city traffic department of the town of Bologna).

Breath Tests↗
PubMedDate not supplied

Effects of aminothiols in 2-acetylaminofluorene-treated rats. II. Glutathione cycle and liver cytosolic activities.

Reduced glutathione, enzymes involved in its metabolism and other cytosolic activities were evaluated in liver preparations of Wistar rats fed with a diet supplemented with 2-acetylaminofluorene (0.05%) and/or with glutathione or N-acetyl-L-cysteine (0.1%). The treatment lasted 4 cycles, each composed of 3 weeks of special diet followed by 1 week of standard diet. The carcinogen produced a considerable increase in gamma-glutamyl transpeptidase in liver homogenates at cycles III and IV, with an irreversible trend which was not discontinued even during the weeks of standard diet. Moreover, generally from cycle I, 2-acetylaminofluorene stimulated several enzyme activities in the liver cytosol, such as glutathione S-transferase, glutathione reductase, glucose 6-phosphate dehydrogenase, NADH- and NADPH-dependent diaphorases. Administration of the two aminothiols to untreated rats resulted in a significant enhancement of glutathione peroxidase, glucose 6-phosphate dehydrogenase and diaphorases. In 2-acetylaminofluorene-treated rats, both thiols further stimulated glutathione S-transferase during the last treatment cycles and attenuated gamma-glutamyl transpeptidase activity, which however was not sufficient to thoroughly counteract the liver lesions due to the massive feeding of the carcinogen. Hepatocellular glutathione was enhanced during the last cycle of treatment with 2-acetylaminofluorene, and was further increased by co-administration of exogenous glutathione.

2-Acetylaminofluorene↗