Marshall W. Parrott

The induction of tumors in the rat by astatine-211.

Exposure of rats to sublethal amounts of At/sup 211/ results in the early appearance of large numbers of mammary tumors, many of them malignant, and in the production of an altered functional state simulating menopause. It is evident that the tumor induction is not yet tested for its association with radiation exposure separately from the endocrine disturbance. (auth)

Accumulation of Astatine211 by Thyroid Gland in Man.

Summary 1. Accumulation of At211 by thyroid gland in patients suffering from various disorders of that organ has been demonstrated. 2. Accumulation of At211 by thyroid glands of these patients appears to be relatively higher than has been observed in experiments employing rats. 3. There may be a correlation between the uptake of At211 and stable iodine in thyroid tissue. 4. One patient with papillary adenocarcinoma showed no discernible accumulation of At211 in metastases present in cervical lymph nodes.

Effects of Thyroxine and KSCN on Capacity of Rat Thyroid Gland to Accumulate Astatine211.

Summary 1. The administration of thyroxine to the intact female Sprague-Dawley rat resulted in a lowered thyroidal accumulation of both At211 and I131. Since it is known that thyroxine inhibits production of TSH by the pituitary gland, it is suggested that a reduced pituitary function resulted in a reduced thyroidal accumulation of both halogens. It is further indicated that the thyroidal accumulation of At211 is under pituitary control. 2. It has been demonstrated that thiocyanate blocks the thyroidal accumulation of astatide, and that since thiocyanate can discharge At211 from the thyroid gland, At211 probably is not organically bound in a manner similar to the organic binding of I131.

Evidence for function of aberrant thyroid tissue in thymus of rats.

Summary Aberrant thyroid follicles have been found in the thymi of female Sprague-Dawley rats. The accumulation of I131 by such follicles, shown autoradiographically, indicated their functional nature.

Effect of Pretreatment with Propyl Thiouracil on Accumulation of Astatine211 by Thyroid Gland of the Rat

Summary A study has been made of the accumulation of I131 and At211 in normal and propyl thiouracil-treated rats. A very marked enhancement of the accumulation of At211 in the thyriod gland has been observed following administration of propyl thiouracil. This is in contrast to the diminution of the uptake of I131 by the thyroid glands of the rats receiving propyl thiouracil.

Serum calcium levels in thyroid-ablated rats.

Summary Serum calcium levels have been measured in adult female Sprague-Dawley rats whose thyroid glands had been removed either with I131 or by surgery. The mean serum C– level of rats whose thyroids had been completely ablated with 5 μC/g body weight of I131 was within normal limits, 9.3 ± 0.02 mg 100 ml. Complete destruction of the parathyroids, as well as the thyroid gland, was effected by a dosage of 50 μC/g I131.