THE DERMOSTRATION OF HYDROXYSTEROID DEHYDROGENASE ACTIVIY IN HUMAN FOETAL SKIN IN THE FIRST 32 WEEKS OF GESTATION

SUMMARY.— Specimens of skin of 25 human foetuses from 8 to 32 weeks gestation were incubated to demonstrate the presence of hydroxysteroid dehydrogenases by histochemical methods. 17β-HSD was demonstrated at 16 weeks gestation, when fully differentiated sebaceous glands were first visualized. 3β-HSD and 16β-HSD were recognized at a later stage. These enzymes were found only in sebaceous glands and in no other appendages. A comparison between the human foetal and adult pattern of enzyme activity has been drawn, and the significance of the results discussed.     

Some Innovating Models in Teratogenicity: Correlating Pharmacokinetics and Teratogenic Endpoints

Correlating Pharmacokinetics and Teratogenic Endpoints. Kimmel,C.A. and Young, J.F. (1983). Fundam. Appl. Toxicol. 3: 250–255.The use of pharmacokinetics can improve the extrapolation ofanimal teratology data for human risk evaluation. Before onecan extrapolate between species, however, the pharmacokineticmodel must be predictable within the species for which it wasdeveloped. This article summarizes an approach being used forcorrelating pharma.     

The performance of ultraviolet lights used to polymerize fissure sealants

The performances of ultraviolet (uv) lights used to initiate polymerization in fissure sealant systems were studied with a view to establishing recommendations for improving clinical results. The relationship between the setting time of an uv polymerized sealant (Nuva-seal) and the intensity of radiation applied was first established. This was compared with the intensity and distribution of radiation from seven Nuva-lites and one Quartzlite. It was found that some of the Nuva-lites did not produce an average intensity of uv radiation sufficient to completely polymerize Nuva-seal within the manufacturer's recommended exposure times. It is suggested that this may be a factor contributing to the large variation in sealant retention found in the different clinical trials with Nuva-seal. Finally, a number of recommendations are made to ensure that sufficient uv radiation is applied to all sealant surfaces when the Nuva-seal system is used.