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The anterior pituitary contains abundant type II iodothyronine 5'-deiodinase (D2). The role of this enzyme in mediating thyroid hormone action in the pituitary has been proven only for thyrotropes, although there is evidence that it exists in other cell types, including somatotropes and lactotropes. Here we investigated the potential of D2 to mediate thyroid hormone regulation of growth hormone (GH). Using GH mRNA as an end point, we demonstrate that in hyperthyroid states GH mRNA levels are stimulated by triiodothyronine (T(3)) generated via D1, whereas in hypothyroidism, when D2 activity is markedly increased, GH mRNA is more responsive to tetraiodothyronine (T(4)) in a propylthiouracil-insensitive, reverse T(3)-suppressible manner. Under short-term hyperthyroid conditions, GH levels correlate with plasma T(3); in contrast, the correlation is not observed in hypothyroidism, a condition in which plasma T(3) levels are too low to account for the response. These results add support to the concept that D2 is present in the pituitary and that the enzyme plays an important role in mediating stimulation of GH by thyroid hormones, particularly in hypothyroid states in which they could alleviate the impact of hypothyroxinemia on GH secretion., (Copyright 2001 S. Karger AG, Basel)

Growth hormone (GH) gene expression was examined in male Wistar rats (200 g) subjected to different manipulations of thyroid status. Thyroidectomy followed by 10 days of treatment with 0.03% methimazole added to drinking water caused a marked decrease in GH mRNA levels estimated by Northern Blot analysis. T3 administration (100 micrograms/100 g body weight, ip, twice daily) to euthyroid rats for one week caused a substantial increase in GH mRNA levels. In another set of experiments, thyroidectomized methimazole-treated rats were killed at different times after a single T3 injection (100 micrograms/100 g body weight, ip). T3 induced a prompt response in GH gene expression by 15 min that reached a maximum after 1 h, remaining so up to 4 h. We conclude that in the rat, GH gene expression is highly dependent on thyroid hormones. Because of the rapidity of the response, the effect is probably mediated by a transcriptional mechanism.

In the present communication there are exposed the treatment modalities of health carriers. The difficulties of action depends primarily on scarcity of health education and of adequate structures and manufacturing equipment in the places of work.

Provisional data on selected sanitary events which took place at Seveso after July 10 1976 are reported. 187 cases of chloracne, mostly in children, were detected, 50 just after the accident, the others within a year. Most polluted area (zone A) provided almost all "early" and most severe cases, but the territorial distribution of chloracne prevalence rates showed some inconsistencies with the soil TCDD pollution map; interpretations for such findings are discussed. Thirty-eight birth defects were detected in 1977 (none in zones A and B), more than in previous years, but still less than expected in a well controlled "normal" population: no clustering around a given type was observed. Spontaneous abortions, evaluated both as abortion rates and as pregnancy loss rates, showed scattered and statistically non-significant variations, inconsistent with the pollution map. No differences in birth and death rates compared to surrounding areas were observed. Data on ad hoc cytogenetic, neurological and immunological surveys are commented. Limitations of the presently available data are discussed and further research lines are anticipated.

The results of a seroepidemiological prevalence survey on the immune status against tetanus of steelmill workers (who, limited to the new work call ups, had to be vaccinated since 1968) are reported. We did not observe remarkable differences in protection against tetanus among those who had begun work before 1968 (46.4% protected) and after 1968 (53.5% protected). In both cases, the protective values were the result of immunization procedures that were performed exclusively in consequence of the military service and/or on the occasion of industrial accident and/or road accident or of accidents of other kinds. It appears, moreover, that the protection of workers against this disease is, nowadays, too often relying on serum prophylaxis, which was the only preventive measure adopted for over half of the workers. In the light of the reported data we need to enforce the existing legislative measures.