Editorial: Postheparin lipoprotein lipases

Relationship between plasma insulin levels and high density lipoprotein cholesterol levels in healthy men

Insulin and high density lipoproteins are considered to play a role in the development of atherosclerosis. In order to study whether there was a relationship between endogenous plasma insulin response and high density lipoproteins, an acute intravenous glucose tolerance test (0.5 g glucose/kg body weight) was performed in 94 healthy men, aged 20-49 years. Cholesterol and triglyceride levels were measured in very low density lipoproteins, low density lipoproteins and high density lipoproteins isolated from fasting serum by preparative ultracentrifugation. The subjects were divided into quartiles according to their fasting and post-glucose load plasma insulin and high density lipoprotein cholesterol levels. The results obtained in the subjects of the upper quartiles were compared with the results obtained in the subjects of the lower quartiles. The mean glucose disappearance rates were within the normal range and did not differ between the upper and lower quartiles. Subjects with high fasting plasma insulin had lower high density lipoprotein cholesterol levels (1.11 +/- 0.34 mmol/l, p = 0.01) than men with low fasting plasma insulin (1.40 +/- 0.37 mmol/l). Higher mean post-glucose plasma insulin was associated with lower high density lipoprotein cholesterol levels (1.18 +/- 0.32 mmol/l, p less than 0.05) and increased high density lipoprotein triglyceride levels (0.14 +/- 0.07) mmol/l, p less than 0.01) when compared with the men with low post-glucose plasma insulin (1.40 +/- 0.36 mmol/l and 0.09 +/- 0.03 mmol/l respectively). These observations reflect the close relationship between endogenous insulin and lipoprotein metabolism.

Substrate mobilization: a new hypothesis for the aetiology of the idiopathic respiratory distress syndrome

This hypothesis for the aetiology of the idiopathic respiratory distress syndrome of the newborn (IRDS) proposes that, although the aetiology is multifactorial, the factor of prime importance is the mobilization of substrate for surfactant synthesis. All factors known to influence the incidence, treatment, and prognosis of the IRDS can be shown to be associated with the mobilization of substrate and thereafter its continued availability for the synthesis of adequate surfactant. Thus factors which promote an antenatal increase in the breakdown of energy stores will be associated with a reduced incidence of the IRDS. On the other hand, despite adequate mobilization, factors associated with a lack of substrate secondary to poor transport of substrate, a reduction in pulmonary circulation or an alteration in fetal or neonatal metabolism which involves an increased utilization of substrate to provide energy, will be associated with an increased incidence of the IRDS.