Discussion of biomarkers of aging.
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Biomedical subjects
Publications and source records attributed to R B McGandy.
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This report describes studies in which diets have been developed which when fed to rats commonly result in the formation of primary urinary bladder calculi. The bladder walls of most of these rats but not those without urinary stones were grossly hypertrophied. Microscopic examinations in one of the studies indicated that about a quarter of the bladders containing stones showed histological changes consistent with those characterized as grade I to II transitional cell carcinomas. In all cases animals showing these histological abnormalities consumed vitamin A-deficient diets in which the carbohydrate was supplied mostly by lactose.
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Benzo(a)pyrene and 210Po were administered both simultaneously and sequentially by intratracheal instillations to Syrian golden hamsters in experiments designed to identify any synergistic interactions between these carcinogens. Their effects were additive after simultaneous administration. A significant synergistic interaction between the two agents appeared to occur when benzo(a)pyrene exposure followed 4 months after 210Po exposure. Most of this effect could be ascribed, however, to a potentiating effect of subsequent 0.9% NaCl solution instillations on 210Po carcinogenesis. These results emphasize the fact that seemingly innocuous stimuli may significantly potentiate lung carcinogenesis. The implications of these findings in terms of the interactions between alpha-radiation and cigarette smoke in human populations are discussed.
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Lung cancers have been induced in 9 to 53 percent of hamsters given multiple intratracheal instillations of polonium-210 in amounts yielding lifetime exposures of 15 to 300 rads to the lungs. Cigarette smokers have previously been estimated to receive 20 rads to areas of the bronchial epithelium from deposited polonium-210. This finding thus supports the hypothesis that alpha radiation resulting from the polonium-210 or lead-210 present in cigarette smoke may be a significant causative factor in human lung cancer.
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