[No increased urinary arsenic levels in children living on naturally arsenic-rich soil].

In order to assess the health effect of environmental exposure to arsenic, the urinary arsenic concentrations were determined in 25 children aged 2-5 yr in the De Huet quarter in Doetinchem, an area with an increased amount of naturally occurring arsenic in the upper soil, and in 25 children from the other quarters of Doetinchem. With a questionnaire information was obtained regarding playing outdoors and eating fish (also a source of arsenic intake). There were no statistically significant differences in urinary arsenic concentrations between the subgroups of children.

In vitro study of acute toxic effects of high iodide doses in human thyroid follicles.

The acute effects of increasing doses of sodium iodide were studied on human thyroid follicles isolated from normal paranodular tissue. After 24 h incubation in culture medium, follicles isolated from most thyroids maintained their capacity for 125I accumulation and organification and a normal cellular ultrastructure. 125I accumulation was significantly increased after addition of TSH, whereas 125I organification was not affected.

Correlated morphological and functional study of isolated rat thyroid follicles in suspension culture.

Rat thyroid follicles were isolated by collagenase digestion and cultured in suspension on agarose for 1-12 days with 0-0.1-1 mU/ml thyrotropin (TSH). After a 4 h exposure to Na125I they were processed for light and electron microscopy, autoradiography and biochemical analysis.

Thyroid hormone stimulates expression of 6-phosphofructo-2-kinase in rat liver.

The activity of liver 6-phosphofructo-2-kinase (PFK-2), the enzyme that catalyses the synthesis of fructose 2,6-bisphosphate, was markedly decreased in hypothyroid rats and partially restored after 3 days of treatment with triiodothyronine. The changes in PFK-2 activity were accompanied by parallel changes in enzyme content measured by immunotitration and in PFK-2 mRNA determined by dot blot and Northern blot hybridization with cDNA probes. It is concluded that thyroid hormone stimulates liver PFK-2 gene expression by a pre-translational mechanism.

A new mechanism for the reabsorption of thyroid iodoproteins: selective fluid pinocytosis.

Rat thyroid hemilobes were incubated in presence of exogeneous, heterologous and homologous thyroglobulins. The median density of the thyroglobulin molecules originally added to the medium was compared with that of the molecules remaining at the end of a three-hour incubation period (37 degrees C). A certain degree of specificity in the reabsorption process of thyroglobulin was found: the uptake of homologous molecules (rat) was higher than heterologous (hog) molecules.

Differences in the retinol circulating complex between healthy male and female infants.

The concentration of the three components of the retinol circulating complex demonstrates in healthy male infants, but not in females, a transient elevation culminating at 5-6 months after birth. This trimolecular peak is significantly less elevated in bilateral cryptorchid babies. The rise of the retinol related parameters seems directly induced by the testosterone hypersecretion previously described in male infants at 2-3 months.