Increased insulin receptor binding in erythrocytes from growth hormone-deficient children

Adult vs childhood onset GHD: is there a real clinical difference?

As growth hormone (GH) secretion and insulin-like growth factor I (IGF-I) levels decrease with age, it is important to have reliable age- and sex-specific control data for both GH stimulation tests and circulating IGF-I levels. This is particularly true for elderly patients with a history of pituitary disease but with normal production of the anterior pituitary hormones other than GH. The potential impact of these factors on GH deficiency (GHD) has led to a need for the development of reliable, sensitive and specific tests to assess GH reserve. Before starting treatment with recombinant human GH in adults with suspected GHD, it is important to differentiate between adults with childhood onset GHD (CO-GHD) and those with adult onset GHD (AO-GHD). Adults with untreated CO-GHD have significantly lower values for body weight, body mass index, lean body mass and height than those with AO-GHD, while patients with AO-GHD show a more pronounced deviation from normal in psychosocial distress. Following treatment with GH, 12.5 microg/kg/day s.c., patients with AO-GHD showed a decrease in waist/hip ratio and low-density lipoprotein. Quality of life, as measured using the Nottingham Health Profile, changed significantly in both patient groups after 18 months of therapy, though these results were only consistent in subjects with AO-GHD. Improvements were also reported in physical mobility and energy. Side-effects were mainly reported in patients with AO-GHD, and this may have been due to the GH dosage being too high for older patients. In conclusion, CO-GHD in adults appears to be a developmental disorder in patients who have not attained full somatic maturation. The hormonal/metabolic balance and lifestyle of these individuals have adapted to their condition. AO-GHD is a metabolic disorder characterized by a hormonal imbalance affecting the health status, physical condition and quality of life of previously normal adults.

Modulation by dexamethasone of insulin binding and insulin receptor mRNA levels in U-937 human promonocytic cells

Treatment with 5 x 10(-6) M dexamethasone stimulated insulin binding in human promonocytic U-937 cells. When curvilinear Scatchard plots were examined according to the one-site model, only changes in affinity, but not in receptor numbers, were observed. However, when the two-site model was applied, an increase in both the affinity and the number of the high affinity-low capacity sites was observed, with maximum values at 15 h. By contrast, the low affinity-high capacity sites did not undergo significant alterations. Northern blot assays revealed two insulin receptor-related mRNAs of approximately 11 and 7 kb in size. Dexamethasone increased the levels of these RNAs, following similar kinetics to those of high affinity receptor expression. This suggests that the 11 and 7 kb species carry information for high affinity insulin receptors, and that in U-937 cells the expression of this receptor subclass is primarily regulated at the mRNA level.