UNLABELLED In order to examine the significance of differences in the triiodothyronine/thyroxine (T3/T4) ratio in the achievement of euthyroidism and in different thyroidal diseases, we studied 1050 subjects: 233 were euthyroid (Eu), 239 hypothyroid (Hypo) with initial TSH levels >15 mU/L, 273 hypothyroid on substitution therapy with L-thyroxine alone and TSH values of 0.35-3.5 mU/L, (hypoRx), ...

It is known that some nutrients can have both negative and positive effects on some populations of insects. To test this, the Logrank test and the Interval Overlap Test were evaluated for two crop cycles (February-May and May-August) of the 7705 tomato hybrid, and the effect on the psyllid, Bactericera cockerelli (Sulc.) (Hemiptera: Triozidae), was examined under greenhouse conditions. Tomato p...

The present study was undertaken to define the source of endogenous triiodothyronine (T3) production responsible for maintaining serum T3 levels in euthyroid subjects with depressed serum thyroxine (T4) values. After withdrawal from 4 wk of exogenous T3 administration, a 22% decline in serum T3 values (from 129 +/- 6 to 99 +/- 4 ng/dl) was observed in six euthyroid subjects, despite a twofold r...

Editor—We read with great interest the article by Nitahara and colleagues showing concentration-dependent inhibitory effects of sevoflurane on neuromuscular transmission in myasthenia gravis (MG) patients which was more prominent in patients with a pre-anaesthetic T4/T1,0.9. In their study, T4/T1 returned to baseline value in all patients at the end of anaesthesia. The importance of monitoring ...

Several influences modulate biochemical responses to a weight-adjusted levothyroxine (l-T4) replacement dose. We conducted a secondary analysis of the relationship of l-T4 dose to TSH and free T3 (FT3), using a prospective observational study examining the interacting equilibria between thyroid parameters. We studied 353 patients on steady-state l-T4 replacement for autoimmune thyroiditis or af...

It is over 40 years since the original demonstration that thyroxine (T4), the principal secretory product of the thyroid, is deiodinated, to 3,5,3'-tri-iodothyronine (T3) in peripheral mammalian tissues. Subsequently it was shown that the antithyroid drug propylthiouracil (PTU) also blocked the metabolic effects of administered T4 in proportion to its inhibition of T4 to T3 conversion, indicati...

A new method for the estimation of the maximal T4-binding capacity of TBG (max. TBG) in serum (dextran-coated charcoal-triosorb method) was devised. Thyroxine (T4) concentration in test sera were determined by the Tetrasorb method and then T3 resin sponge uptake (T3 RSU) was determined after extraction of 70% of the endogenous T4 with dextran-coated charcoal. The binding capacity of unsaturate...

BACKGROUND Total or near-total thyroidectomy is increasingly used to treat benign thyroid conditions. Lifelong treatment with thyroxine (T4) is then required, but the optimal dose is difficult to predict. This study investigated factors that might predict the ideal T4 dose, with the aim of reducing delays in achieving normal thyroid function after surgery. METHODS Data on 98 patients who unde...

Thyroid hormones (THs) play a vital role in vertebrate neural development, and, together with the beta isoform of the thyroid hormone receptor (TRβ), the development and differentiation of cone photoreceptors in the vertebrate retina. Rainbow trout undergo a natural process of cone cell degeneration during development and this change in photoreceptor distribution is regulated by thyroxine (T4; ...