We describe the expression pattern of Sox8, Sox9 and Sox10 during the development of the chick embryo heart. These Sox genes constitute the group E of the large Sox family of transcription factors. We show that the expression of Sox8, Sox9 and Sox10 in the developing heart correlates with heart septation and with the differentiation of the connective tissue of the valve leaflets. Sox10 appears also as a specific marker of developing heart nerves. These findings fit with the occurrence of morphological and functional anomalies of the heart reported in humans deficient for Sox9 and Sox10.

In 158 obese children, aged from three months to 15 years, blood glucose, immunoreactive insulin, and free fatty acid levels were measured during a standard oral glucose tolerance test carried out prior to treatment. The results were analyzed for the total sample as well as for three age groups: 0-5 years, 6-10 years, and 11-15 years and compared with those of 70 normal-weight children matched for age and sex. Glucose tolerance is normal in the obese children. It is different from the controls only two hours after glucose loading, when a slight but significant elevation is found. The glucose levels at one and two hours are significantly higher in the obese children of group III than in the younger ones. Fasting F.F.A. levels are similar in normal and obese children, but the F.F.A. decrease following glucose absorption is significantly diminished in the obese. The F.F.A. levels of the youngest obese are significantly higher than those of the older ones. A constant and important hyperinsulinism, fasting and postabsorptive, is demonstrated in obese children of all ages, even before five years and at the beginning of obesity. Age- and sex-related differences in insulin secretion are much more marked in the obese than in normal children. The degree of hyperinsulinemia is related to the degree of obesity, but not to its duration. The results suggest that hyperinsulinism is associated with obesity from its onset rather than being a long-term consequence of overweight. However, the origin of hyperinsulinism in obesity and the mechanism of insulin resistance still remain obscure.

In 70 healthy children aged from three months to 15 years, blood glucose, immunoreactive insulin, and free fatty acids were measured during a three-hour glucose tolerance test. The results are presented for the whole group as well as for three age groups: three months-five years, six-10 years, and 11-15 years. It is demonstrated that (1) glucose levels are significantly lower in young children (younger than five years); (2) there are no significant age-related changes in free fatty acid concentration; (3) insulin levels are increasing constantly and significantly with age, the most strikingly at the age of onset of puberty; the absence of notable changes in glucose tolerance results in a rise of the I/G ratio as well. The causes for the increase of insulin secretion with age, whether of peripheral or pancreatic order, are still speculative.

No abstract