Thyroid hormones have diverse effects on growth and metabolism. Specific “receptor” proteins which bind triiodothyronine and other biologically active analogs and which may be involved in thyroid hormone action have been recently found in nuclei of responsive tissues. This report presents studies of these receptors in rat liver nuclei. Confirming previous reports, a Scatchard analysis of the bi...

IREAD WITH GREAT INTEREST THE PAPER OF Mainwaring and his colleagues concerning the use of supplementation of triiodothyronine following the modified Fontan procedure. The authors found an evident reduction in levels of triiodothyronine in the blood both during and after cardiopulmonary bypass in patients undergoing the Fontan procedure. We have encountered similar findings in 47 consecutive ch...

While 3, 3', 5'-triiodothyronine (reverse T3, rT3) has been detected both in human serum and in thyroglobulin, no quantitative assessment of its metabolic clearance rate (MCR), production rate (PR), or secretion by the thyroid is yet available. This study examines this information in euthyroid subjects and evaluates it in light of similar information about two other iodothyronines in the thyroi...

The deiodination of L-thyroxine to triiodothyronine has been observed in vitro using surviving rat kidney slices (1, 2). Surveys of other rat tissues have not shown consistent deiodination of tlhyroxine, but occasional appearances of trace quantities of triiodothyronine in surviving heart slices and diaphragm (3) have led to the belief that other tissues in the rat convert thyroxine to triiodot...

We have previously demonstrated with radioimmunoassay techniques that physiologic concentrations of thyroid hormone stimulate an increase in growth hormone production in GH1 cells in culture. In this study, with radiolabel techniques and selective immunoprecipitation, we demonstrate that L-triiodothyronine stimulates growth hormonw production solely by inducing an increase in the de novo synthe...

Thyroid hormones have diverse effects on growth and metabolism. Specific “receptor” proteins which bind triiodothyronine and other biologically active analogs and which may be involved in thyroid hormone action have been recently found in nuclei of responsive tissues. This report presents studies of these receptors in rat liver nuclei. Confirming previous reports, a Scatchard analysis of the bi...

Indices of thyroid function were measured in 97 preterm infants at birth and at 5, 10, and 15 days of age. Triiodothyronine uptake, free thyroxine index, thyroxine, free thyroxine, triiodothyronine, reverse triiodothyronine, and thyroxine binding globulin values at birth correlated with gestational age, whereas thyroid stimulating hormone values did not. Treatment with steroids prenatally had n...