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R. C. Turner, B. Schneeloch and P. Paterson

ABSTRACT

Plasma immunoreactive insulin and growth hormone of 20–24 weeks' gestation human foetuses were assayed in serial samples following delivery by hysterotomy. The mean umbilical cord plasma growth hormone concentration was 71 ng/ml (range 13–120 ng/ml) and the mean plasma insulin was 5 μU/ml (range 2–8 μU/ml). Following delivery the growth hormone levels increased, but there was no significant change in plasma insulin concentration. The hypothalamic-hypophyseal axis controlling growth hormone secretion appears to be developed by 20 weeks' gestation, and »stress« appears to be a provocative stimulus.

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R. C. Turner, E. Harris, M. Ounsted and C. Ponsford

ABSTRACT

To characterize the defect of insulin secretion in diabetes, the response to different iv glucose loads has been studied in women who have had gestational diabetes and are, by definition, latent diabetic (LD). Women who have produced a large-for-dates baby, but who were not known to have been diabetic (LFD), have been investigated to determine if they have abnormal metabolism. Both groups were found to have raised fasting plasma glucose concentrations. Only the LD had glucose intolerance, which was associated with a reduced first phase insulin response to all glucose loads with a decreased maximal secretory capacity (low V max). The LFD women appeared to include a distinct abnormality in which the β cells had decreased sensitivity to glucose (high Km), with diminished secretory response to small but normal response to large loads. Whereas the LD probably have disordered μ cell function, some of the LFD women may represent the upper end of the normal range of the glucose "set" of β cell function. Neither group had insulin resistance, as measured by the hypoglycaemic response to an iv insulin bolus. A woman who has produced a LFD, but who was not known to be diabetic, does not necessarily have a diabetic tendency.

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J. D. M. Albano, R. P. Ekins, G. Maritz and R. C. Turner

ABSTRACT

A radioimmunoassay method for the measurement of plasma insulin is described relying on activated charcoal for the separation of free and bound fractions. The technique illustrates the application of theoretical precepts designed to maximise assay precision in all radioimmunoassay and other saturation assay techniques.

In addition, because particular emphasis has been placed on ensuring that, as far as is possible, all incubation mixtures are similar as possible other than in hormone concentration, non-specific effects appear to have been essentially eliminated. The technique yields a mean normal fasting value of 5.3μU/ml (range 2–14 μU/ml). Its sensitivity is such that 10 μl samples of serum (or plasma) may be assayed.

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J. G. Herndon, M. S. Blank, D. R. Mann, D. C. Collins and J.J. Turner

Abstract. Suppression of luteinizing hormone (LH) by sc implanted oestradiol-17ß (E2) pellets was examined in 4 ovariectomized female rhesus monkeys during the breeding season, the non-breeding season and during the transition between the breeding and non-breeding season. Immunoreactive LH was suppressed to 58, 78 and 75% of untreated levels for the respective seasonal conditions. Bioactive LH was suppressed to 29, 49 and 33% of baseline. Bioactive LH (determined by testoster-one release from rat interstital cells) was significantly correlated (r = 0.84) with immunoactive LH from the same samples. It is concluded that E2 treatment of ovariectomized female rhesus monkeys results in suppressed levels of LH, regardless of the time of year.