The binding characteristics of transcortin, thyroxine binding globulin and pre-albumin in Jamaicans

The binding characteristics of Thyroxine Binding Globulin(TBG) Pre-albumin (TBPA) and Transcortin in Jamaicans were found to be similar to those described elsewhere. The previously reported diminution in adrenocortical and thyroidal function associated with normal plasma cortisol and thyroxine levels cannot therefore be ascribed to an increase in the plasma protein binding of these hormones (AU)

Thyroid function in euthyroid Jamaicans

Thyroid function has been investigated in 32 hospitalized euthyroid Jamaicans. The in vivo investigations performed were measurement of 2«, 4 and 24 hr thyroidal uptake of 131I, thyroidal and renal clearances of radioiodide, absolute iodide uptakes and, in 6 subjects, radiothyroxine turnover studies. Thyroxine binding globulin and prealbumin capacities were measured in a small number of cases. Results obtained in all these investigations agreed well with those found in temperate climates and are at variance with previous finding of low 24 hr thyroidal uptakes of 131I in euthyroid Jamaicans, associated with a normal serum protein-bound iodine.(AU)

Plasma insulin responses to oral glucose in normal and diabetic Jamaicans

The plasma insulin reponses to oral glucose have been determined in 96 normal and diabetic Jamaican subjects during standard oral glucose tolerance tests. The results are discussed with respect to: (a) possible aetiological factors causing diabetes in Jamaica and (b) the existence or not of racially determined differences in metabolic responses (AU)

Thyroxine turnover studies in Jamaicans

Radioactively labelled thyroxine (T4 - 125 I) has been used to carry out studies on thyroxine turnover in Jamaicans subjects. The decrease in plasma radioactivity following intravenous injection of labelled T4 has two components. The slow component lasting from 1 to 10 days post injection may be mathematically analysed to give the following data: (a) thyroxine distribution space; (b) total extra thyroidal thyroxine; (c) fractional turnover rate of the hormone and (d) thyroxine secretion rate. The results obtained in six normal Jamaican subjects agree well with those found by workers in North America and Europe. The fast component (10 minutes to 4 hours post injection) has been analysed in 8 normal, 2 hypothyroid and 1 thyrotoxic subjects using simultaneously injected albumen 125I and thyroxine 131I. This technique has previously been used by Oppenheimer et al (1967). It has until recently been thought that the cellular uptake of thyroxine was dependent on the concentration of diffusible (non protein bound) thyroxine in plasma. The results presented here show cellular uptake values 100 times greater than can be explained on this basis. These data have been analysed by a computer programme designed by Dr. J. B. Shepherd, Department of Physics, U.W.I. (AU)

Reassessment of thyroid function in euthyroid Jamaicans

In 1964 Goldberg et. a.l reported the results of a thyroid function study in a large group of normal Jamaicans. Very low 24 hour thyroidal uptakes of I131 were obtained, the mean being 13.8 percent of the dose. In view of these findings thyroid function was reassessed in 32 euthyroid Jamaican subjects. Investigations performed included, estimation of plasma inorganic iodide, 2, 4, and 24 hour thyroidal uptakes of radio iodide, absolute thyroidal iodide uptake and thyroidal and renal clearances of plasma iodide. Results obtained in all these investigations agreed well with those found in temperate climates and are at variance with the findings of Goldberg et al (AU)