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The uptake and distribution of Zn/sup 65/ were measured in three rams serially sacrificed at 5, 10, or 20 days following single administration; in two rams 20 days after single oral administration; and in three ewes in advanced pregnancy (with their fetuses) and in one ram fed Zn/sup 65/ daily for 2 weeks. Direct measurements with Victoreen pocket dosimeters were taken in the major tissues following sacri fice of one of the ewes and the ram fed Zn/sup 65/ daily. Data on the rams indicated that between 10 and 20% ingested radiozinc was absorbed from the gastrointestinal tract. Turnover rates of radiozinc were estimated at between 10 and 30% for most tissues and less than 2% per day for voluntary muscle and bone. In the ewes and ram fed Zn/sup 65/ for 2 weeks, the highest concentrations were found in the liver, kidney cortex, mammary tissue, pancreas, and spleen, respectively. There was a 3-day lag before appreciable uptake was observed in the blood cells. The fetuses contained concentrations from one-tenth to one-half those in comparable tissues of the ewes. Total body was observed to be the critical organ for the ram and ewe used for the doserate measurements. (auth)

The close association of people and an assortment of animals is depicted in early cave paintings and revealed in archeological diggings. This relationship or bond has contributed to the well-being of people by contributing to their nutrition, clothing, housing, security, comfort, sense of humor, health, wealth, and overall well-being. With regard to their health and well-being, experiments on animals have contributed greatly to the control, cure, and prevention of a myriad of diseases. And the animals have in many cases benefited remarkably from this research [1–3].

The toxicity of Pu was investigated in miniature swine. Results are summarized from studies of blood concentra, tion, organ burden, and excretion patterns following various routes of Pu administration, the toxicity of Pu as compared to some other bone-seeking nuclides, and the penetration and removal of Pu from skin when injected or applied topically. (C.H.)

Blood values for protein-bound iodine, creatinine, phosphorus, urea nitrogen, cholesterol, calcium, leukocytes, hemoglobin, and hematocrit in surgically thyroidectomized Suffolk sheep were compared with control animals' levels for 1 year. Serum protein-bound iodine values were found to decrease and creatinine to increase immediately after surgical thyroidectomy. Lymphopenia developed during the second postsurgical month, and inorganic phosphorus was elevated during the last part of the experimental period. No significant changes occurred in calcium, hemoglobin, hematocrit, or neutrophil values.

Early studies by Carlson et al. (1, 2) indicated that individually caged, highly inbred male rats exposed to low levels of daily irradiation for one year paradoxically manifested an increased life expectancy. Other workers (3-5) have also found that some rodent colonies appear to have an increased life span after exposure to low levels of irradiation as well as other paradoxical responses, including a reduced mortality early in life (3, 4, 6), increased resistance to acute challenge doses of irradiation (6-11), and development of an adapted or resistant cell population in certain organs (12, 13). In order to observe these effects on an animal that could be handled singly, but in larger numbers more conveniently than rats, a series of studies was performed on individually caged hybrid male mice.

chronically fed plutonium was determined as 0.0026 =0.0004 %. This value was obtained in experiments with rats, employing plutonium solutions ranging in concentration from 10-6 to 3 X 10-5 ig/ml. We have now extended these studies to cover the concentration range from 10-4 to 1 ;g/ml. Because of the uncertainties involved in extrapolating from rat to man, data were sought from a larger animal more closely akin to the human. Results are reported comparing the gastrointestinal absorption of acutely administered plutonium in pigs and rats. Data are also presented comparing the gastrointestinal absorption of plutonium fed to rats as solutions of different pH and valence state, and with nitrate or citrate present as the anion in solution. Based on these results, a re-evaluation of the maximum permissible concentration of plutonium in water for human consumption has led to an increase in this limit from the previous value of 1.5 X 10-6 ~c/ml (2) to a less restrictive value of 6 X 10-6 Mc/ml (3).