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Studies were performed to ascertain the effect of various levels of chronic iodine intake and varying doses of iodide [0.002–100 μmoles KI/100 g body weight (BW)] given acutely on the rat thyroid metabolism of [ 35 S]methimazole ([ 35 S]MMI, 8.76 μmoles/kg BW). Variations in both acute and chronic iodine intake were associated with as much as four-fold changes in thyroid levels of total 35 S and unchanged [ 35 S]MMI. Chronic low iodine intake resulted in a considerable reduction in the thyroid uptake of [ 35 S]MMI (40% decrease) from high or normal chronic iodine intake. Unlike [ 35 S]PTU studies, the effect of increasing acute iodide dosage produced a biphasic response in the thyroid uptake of [ 35 S]MMI only in low chronic iodine intake. In these animals 0.1 μmoles KI/100 g BW produced the maximum uptake of [ 35 S]MMI (300% increase) but had no effect on high or normal chronic iodine intake. In these latter groups of rats, thyroidal total 35 S increased to plateau levels with increasing acute iodide dosage in the range of 0.1–1 μmoles/100 g BW which were unaffected by increased iodide up to 100 μmoles/100 g BW. In low chronic iodine intake rats also, the thyroid 35 S level seen at 1 μmole/100 g was unaffected by increased iodide dosage up to 100 μmoles/100 g. The steady thyroid 35 S levels seen in this acute iodide dose range in low, normal and high chronic iodine rats were 100, 70 and 110% respectively greater than their control values. Unlike [ 35 S]PTU studies, in general, an increase in thyroid total 35 S achieved by varying acute or chronic iodine intake was found to be associated with a large increase in the percentage thyroid 35 S occurring as free inorganic sulphate with a consequent effect on thyroid unchanged [ 35 S]MMI. In chronic low iodine intake animals treated with acute radioidide, in agreement with [ 35 S]PTU studies, no direct correlation was found between thyroid uptake or oxidation of [ 35 S]MMI and thyroidal total iodine, the accumulation or organification of acute [ 125 I]iodide, the occurrence of the Wolff-Chaikoff effect or saturation of thyroid iodide transport.

Translumbar renal puncture is a long established and generally accepted method for the radiological investigation of renal masses, particularly those that are asymptomatic, avascular and transonic (Jeans, Penry and Roylance, 1972). Hydatid cyst, however is exceptional in that, while it may meet all these criteria, its puncture is held to carry a considerable risk of promoting local dissemination (Wright, 1972), and of causing serious anaphylaxis. In order to avoid inadvertent puncture, prior Casoni testing of patients with calcified renal masses (Jeans et al., 1972) and of patients from areas with a notable incidence of the disease (Sherwood and Stevenson, 1971) has been advocated. A case is presented in which these precautions were inadequate to prevent puncture of an unsuspected renal hydatid cyst. The examination had no untoward effects and enabled the diagnosis to be established before definitive therapy had been planned. N.C., a 42-year-old English District Nurse was admitted to hospital one week aft...

Serial studies of iodine metabolism were carried out in 8 obese patients before and during total deprivation of food. Evidence of decreasing thyroid function was suggested by a fall in uptake of both radioactive and stable iodine by the gland and by a fall in serum protein-bound iodine. The renal clearance and urinary excretion of iodine also fell. The amount of thyroid hormone deiodinated was calculated as 45.5 and 39.5 μg. of hormonal iodine daily.

Radioactivity was found bound to follicular thyroglobulin after administration of 35S-propylthiouracil (PTU) to rats. Denaturation of the thyroglobulin using various procedures could not separate the 35S from the protein; it was concluded that the 35S is bound to thyroglobulin covalently. Fractionation of saline-soluble thyroid proteins was performed by ultracentrifugation on sucrose gradients. The PTU-sulphur/thyroglobulin (S/Tg) molar ratio was calculated in all fractions. One hour after the injection of PTU the S/Tg molar ratio was the same for 19S thyroglobulin from rats on stock diet and 18S thyroglobulin from rats on low iodine diet. Injection of KI to the animals before administration of 35S-PTU significantly reduced the ratio. The highest S/Tg ratio 1.10 was noted at 19S thyroglobulin, 17 h after a single injection of PTU. Daily injection of PTU for six days increased the S/Tg ratio to 3.3. Inverse relationship between dose of PTU and S/Tg ratio was noted at one hour. In animals injected with large dose of 35S-PTU and sacrificed several hours later the S/Tg was higher at the 12S subunits than at the 19S protein. The amount of PTU bound to 3–8S subunits was minimal. Sulphite liberated 64 % of the 35S bound to thyroglobulin which appeared as four compounds on thin layer chromatography plates. The main 35S compound liberated by sulphite was sulphate. In vitro incubation of 35S-PTU or 35S-sulphate with bovine thyroglobulin showed that sulphate does not bind to thyroglobulin, while PTU or more probably an unknown metabolite of PTU (which contaminates even an oxygen free water solution of PTU) is attached to thyroglobulin by covalent bond. It is concluded that the 35S of PTU or of an unknown metabolite of PTU different from sulphate binds to follicular thyroglobulin in vivo. The 35S of PTU is accepted by disulphide bonds of the thyroglobulin molecule.