Maturation of organs and tissues in human newborns, a role for thyroid hormones and uncoupling protein 2. A clinically oriented study performed within the scope of the grant project "Role of triiodothyronine formation in brown adipose tissue of human neonates and molecular mechanisms" (IGA MH CR No. Z629-3) was carried out in cooperation with the Department of Biology of Adipose Tissue of this Institute. In this study we have characterized the thyroid status in very pre-term infants from birth through day 14. Moreover, in infants who died within 16 days of delivery, the thyroid status was also correlated with metabolism of thyroid hormones in peripheral tissues (brain, liver, kidney, different depots of adipose tissue, and skeletal muscle). In all post mortem tissue samples activities of the three iodothyronine deiodinase isoenzymes of type I, II, and III were detected. All activities were in liver, and differed considerably in other tissues. Lack of correlation between the type I 5'-deiodinase activity in liver, and plasma levels of thyroid hormones suggested that the thyroid was the primary source of circulating triiodothyronine. On the other hand, correlations between activity of the deiodinases and plasma iodothyronine levels were found in brain which suggested a complex control by the thyroid hormones of their own metabolism.

Interference of bromine from the environment with iodine metabolism in the thyroid gland and other tissues of the rat and humans: Within the framework of the grant projects "Biological significance of the interaction of bromine with iodine from the standpoint of changes in their environmental concentration", "The influence of an excess of bromine and/or iodine deficiency on the metabolism of thyroid hormones in tissues" and "Interference of bromide from the environment with iodine metabolism in the thyroid gland and other tissues" we have studied mechanisms of the bromine interference with iodine metabolism in the rat thyroid gland as a model of the action of goitrogenic substances from the environment on risk population groups. We found that the biological behaviour of bromine in the rat thyroid, contrary to other organs, is not similar to the behaviour of chlorine, but rather to that of iodine. The biological halflife of bromine in the rat thyroid (110 h) was found to be identical with the biological halflife of iodine, and was essentially different from the whole-body half-life of chlorine (325 h). The rat thyroid responded very sensitively to a relatively small increase in bromine intake by a marked decrease in the concentration ratio [I]/[Br]. In addition, we tested the hypothesis that an enhanced bromine intake in the organism at simultaneous insufficient iodine supply intensifies the negative consequences of hypothyroidism and that under these conditions, bromine not only can seriously interfere with the biosynthesis of thyroid hormones in the thyroid but it also can influence the peripheral tissues metabolism of the thyroid hormones. From the practical point of view, the most important finding was above all the confirmation of the fact that the biological behaviour of bromine, and therefore also its toxicity, depends on the state of iodine supply to the organism (i.e., the thyrotoxic effects of bromine compounds are more pronounced under conditions of iodine deficiency).

The influence of antidepressant administration on thyroid hormones metabolism in brain and other tissues: experimental studies in rats. In cooperation with the Institute of Endocrinology, Prague and the IIIrd Clinic of Internal Medicine, 1st Medical Faculty, Charles University, Prague we carry out a study within the scope of the grant project "The influence of antidepressant administration on the hypothalamuspituitarythyroid axis: An experimental study of the relationship between the thyroid function and mental disorders" (IGA MH CR No. 42043), the aim of which is to learn about the relations between the thyroid and mental disorders and about interactions between antidepressants and thyroid hormones in peripheral tissues.