Insulin antagonist of pituitary origin in plasma of normal and diabetic subjects

Studies on ultrafiltrates of the plasma of normal and diabetic subjects have shown that a polypeptide of similar characteristics to the growth-hormone-derived polypeptide In-G is present in higher concentrations in diabetic subjects, thus indicating a possible role in the pathogenesis of diabetes mellitus. The polypeptide is absent from the plasma of hypophysectomized diabetic patients.

A long-term effect of insulin on collagen synthesis by newborn rat bone in vitro

In order to further characterize the effects of insulin on collagen synthesis by newborn rat bone in vitro, the time course of insulin action on incorporation of proline as proline and as hydroxyproline has been studied. In an incubation system, there was no stimulation by insulin at either three or six hours. In a flowing organ culture system, no significant effect of insulin could be observed at six hours; a small but significant effect on incorporation of proline as proline (but not as hydroxyproline) was seen at eighteen hours; and a highly significant effect on the incorporation of proline as both proline and hydroxyproline was observed at forty-two hours. Possible explanations for the delayed onset of insulin activity are discussed and the pattern contrasted with the rapid effect of insulin on collagen synthesis by skin of newborn rats.

Potentiation of insulin action in normal subjects by a pituitary polypeptide

A pituitary polypeptide, acceleratory polypeptide-growth hormone (ACG), has been found to increase the sensitivity of fasting normal people to intravenous insulin. It is suggested that diminished activity of this polypeptide-or increased activity of another polypeptide, inhibitory polypeptide-growth hormone (ING)-may have a role in the genesis of diabetes mellitus.

Actions of insulin and growth hormone on colagen and chondroitin sulfate synthesis in bone organ cultures

1. The effects of insulin and growth hormone have been studied on collagen and chondroitin sulfate synthesis in bones growing in a steady state achieved by a continuous-flow bone culture system.

2. It is seen that insulin, but not growth hormone, has a significant effect on the synthesis of collagen and a marginal effect on the synthesis of chondroitin sulfate.

3. The significance of these findings is discussed.

Pituitary polypeptide with hypoglycaemic action in diabetes mellitus

A polypeptide isolated by the hydrolysis of growth hormone, studied in five patients with diabetes mellitus, has been shown able to produce hypoglycaemia, presumably by modifying the anti-insulin action of pituitary growth hormone. Possibly this substance may be suitable for treating cases of insulin resistance or when a circulating inhibitor of glucose uptake is present.