We have recently shown that it is not possible to restore euthyroidism completely in all tissues of thyroidectomized rats infused with T4 alone. The present study was undertaken to determine whether this is achieved when T3 is added to the continuous sc infusion of T4. Thyroidectomized rats were infused with placebo or T4 (0.80 and 0.90 microgram/100 g BW.day), alone or in combination with T3 (...

In order to compare the effect of 3,5,3'-triiodothyroacetic acid (TRIAC) with those of triiodothyronine (T3) and thyroxine (T4), severely hypothyroid rats (n=56) were infused over 13 days with 1, 2 or 4 nmol/100 g body weight (BW) per day of T3 or 2, 4 or 8 nmol/100 g BW per day of T4 or TRIAC. The 8 nmol/100 g BW per day of T4 or TRIAC induced the same increase in resting metabolic rate, yet 4...

PURPOSE We compared the results from a video-assisted thoracoscopic sympathectomy (VTS) at the T4 denervation level with those from a VTS at the T3 level for the treatment of palmar hyperhydrosis (PH). METHODS Seventy patients with PH were prospectively followed for VTS at the T3 or T4 denervation levels for 6 months. The end points of this study were: absence of PH, compensatory hyperhydrosi...

Experimental and clinical observations suggest that thyroid hormone [L-thyroxine (T4) and 3,5,30-triiodo-Lthyronine (T3)] can support cancer cell proliferation. T3 and T4 promote both tumor cell division and angiogenesis by activating mitogen-activated protein kinase (MAPK) via binding to a hormone receptor on the avb3 integrin, overexpressed on many cancer cells. We have studied the responsive...

Maintenance of normal maternal thyroxinemia prevents severe triiodothyronine (T3) deficiency of the fetus with primary thyroid failure (1). We have studied whether thyroxine (T4) would also protect the fetal brain when maternal hypothyroxinemia is caused by nonthyroidal illnesses. We have used the streptozotocin-induced diabetes mellitus pregnant rat as a model of maternal nonthyroidal illness....

We compared the specificities of transport mechanisms for uptake and efflux of thyroid hormones in cells of the human choriocarcinoma cell line, JAR, to determine whether triiodothyronine (T3), thyroxine (T4) and reverse T3 (rT3) are carried by the same transport mechanism. Uptake of 125I-T3, 125I-T4 and 125I-rT3 was saturable and stereospecific, but not specific for T3, T4 and rT3, as unlabell...

Thyroxine (T4) 5'-monodeiodinating activity in rat pituitary was studied, using paper chromatography. Rat anterior pituitary homogenates were incubated with 125I-T4, dithiothreitol and unlabeled L-T4 at 37 degrees C. The incubation mixture was extracted by ethanol and the extracts were subjected to descending paper chromatography. The conversion ratio of T4 to 3, 5, 3'L-triodothyronine (T3) was...

The local conversion of thyroxine (T4), which is an important source of intracellular 3,5,3'-triiodothyronine (T3) in several rat tissues, has been subject of recent investigations. In the present study the regulation of this phenomenon in vivo was investigated in various peripheral tissues of the rat. Intact euthyroid and radiothyroidectomized (Tx) rats received a continuous intravenous infusi...

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), ...