The electrochemical response of thyroxine (T4) at a carbon paste electrode (CPE) in the presence of cetyltrimethylammonium bromide (CTAB) was investigated. It gave a well-defined oxidation peak at 0.80 V and a sensitive reduction peak at 0.40 V. Compared with the indiscernible signal in the absence of CTAB, the reduction current of T4 at CPE was greatly enhanced in the presence of CTAB, due to ...

Thyroid hormones regulate adipogenic differentiation, lipogenic and lipolytic metabolism, and mitochondrial activity in adipose tissue. Triiodothyronine (T3) levels in tissues are regulated by the deiodinase enzymes. The objective was to study the activity and messenger RNA (mRNA) expression of the 5' outer-ring deiodinases (type 1 [D1] and type 2 [D2] deiodinase) and thyroid hormone concentrat...

Thyroxine (T4), triiodothyronine (T3) and reverse triodothyronine (rT3) concentrations in human milk were measured by radioimmunoassay in 114 samples obtained from 1 week to 8 months postpartum. Several assay systems applied for the determination of serum thyroid hormone concentration were proved to be unsuitable for human milk, and the method of separating free and antibody-bound hormone by po...

Since Gordon and his colleagues' (1) description of the association of thyroxine (T4) with an a-globulin [later termed "thyroxine-binding globulin" (TBG) ] in 1952, thyroid hormone transport has been the subject of intense study. The demonstration of "thyroxine-binding prealbumin" (TBPA) by Ingbar (2) in 1958 provided further understanding of the binding of T4 by the plasma proteins. It has als...

Reverse triiodothyronine (rT3), triiodothyronine (T3), thyroxine (T4), thyroxine binding globulin (TBG), and thyrotrophin (TSH) were measured in sera from placental cord blood in an unselected series of 272 deliveries. In this series the concentrations of rT3 (mean 3 *33 nmol/l, 95 % confidence limits 1 *67 .0 nmol/l), were log normally distributed and did not overlap the adult normal range (O ...

The interaction with iodine metabolism following ingestion of Allium cepa (onion) and Allium sativum (garlic) by albino Wistar rats have been studied. The determination of the effect of the oral administration of onion and garlic extract on thyroid hormones (triidothyronine,T3, thyroxine,T4 were studied. The mean values of triiodothyronine (T3) for the experimental animals were 1.23 ± 0.09ng/ml...

The performance characteristics of assays is reported for thyroxine (T4), triiodothyronine (T3), and T3-uptake (T3U) using the GAMMAFLOTM Automated Assay System. A comparison of calculated free thyroxine index (FTI) values is also presented. This automated radioimmunoassay (RIA) system utilizes a combination of continuous-flow methodology and chromatographic separation techniques. The T4 assay ...

Thyroxine-binding prealbumin (TBPA) in normal human serum has been shown in a polyacrylamide gel electrophoresis system to bind 7-9% of tracer level purified [(125)I]triiodothyronine (T3), and more than 30% of T3 in serum deficient in thyroxinebinding globulin (TBG). The T3-TBPA interaction has been confirmed at pH 9.0 and pH 7.4 in this electrophoretic demonstration of TBPA binding of T3 in se...

The physiologic effects of triiodothyronine (T3) on metabolic rate are well-documented; however, the effects of thyroxine (T4) are less clear despite its wide-spread use to treat thyroid-related disorders and other non-thyroidal conditions. Here, we investigated the effects of acute (3-day) T4 supplementation on energy expenditure at rest and during incremental exercise. Furthermore, we used a ...