Induction of metallothionein (a Zn-binding protein) was investigated in liver and kidneys of rats under the following stresses: cold environment, hot environment, heat burn, strenuous exercise, and CCl4 intoxication. As markers of metallothionein (MT) synthesis, [14C]cystine and 65Zn were injected parenterally into rats, and MT in liver and kidney supernatants was separated on Sephadex G-75 columns. Among stresses tested, the greatest stimulations of MT synthesis in liver were observed under cold (315%), strenuous exercise (302%), and CCl4 intoxication (543%), as evidenced by increased amount of [14C]cystine and 65Zn incorporation into the MT fraction. In contrast to liver, only small responses were observed in MT synthesis in kidneys. There was a general decline in plasma Zn levels in rats under the stresses employed. However, no great differences were observed in Zn levels in whole liver and kidneys. The present study suggests that various unrelated physiological stresses, which are accompanied with a change in Zn distribution, increase the synthesis of MT in liver of rats.

No abstract

It was expected that the incidence of skin cancer would be related to the known high arsenic levels in water supplies of Lane County, Oregon. Incidence rates were based on all histopathologically confirmed cases among Lane County residents diagnosed during 1958-1971 and were compared to mean water arsenic levels measured during 1968-1974. Basal cell carcinoma had a mean annual incidence rate of 88 per 100,000, a 5:4::M:F sex ratio, and an increasing risk for both sexes in urban areas. Squamous cell carcinoma incidence was 50 per 100,000 and showed 2:1:M:F sex ratio but no urban predilection. Neither type of skin cancer was directly related to the arsenic levels as expected, although sporadic individuals with sufficient exposure could manifest the relationship. Fewer than expected drinking water sources were found to contain high arsenic content, so that the Lane County data do not necessarily contradict previous reports of positive correlation. The basal cell carcinoma pattern suggested that this disease might be potentiated by urban air pollutants.

No abstract

The effects of selenium and vitamin E on blood selenium levels and tissue glutathione peroxidase activities were determined in sheep fed purified and hay diets. A significant increase of blood levels of this element and tissue glutathione peroxidase activities was found in sheep given selenium as compared to those not receiving this element. Of the tissues examined, the highest glutathione peroxidase activity was found in the heart. Vitamin E had no influence on either the blood selenium levels or upon the tissue glutathione peroxidase activity. With hydrogen peroxide as the substrate, tissue glutathione peroxidase activity was not correlated with the incidence of white muscle disease. Evidence is presented to suggest that 0.1 ppm dietary selenium is not sufficient under some conditions to meet the physiological requirements for this element.