Regulation of retinoic acid receptor expression in dermal fibroblasts.

Retinoic acid (RA) is known to exert profound effects on growth and differentiation in a variety of cell types in the skin. In vitro studies have also shown that RA modulates gene expression in both fibroblasts and keratinocytes. Recently, three nuclear receptors specific for retinoic acid (RAR alpha, RAR beta, and RAR gamma) have been cloned and all are members of a large multigene family of ligand-inducible transcription enhancer factors.

Cultured human melanocytes express the intermediate filament vimentin.

Human melanocytes are neural crest-derived cells that synthesize the pigment melanin. These cells migrate from a central location to the dermal-epidermal junction early in gestation and situate themselves between keratinocytes of the basal layer of the epidermis, extending thin dendritic processes upwards into the epidermis. In vitro, neonatal melanocytes can assume a variety of morphologies, depending on the culture conditions.

Clonal origin of dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is a malignant tumor originating in the dermis. Although it is known to be locally aggressive, it only rarely metastasizes and will recur unless completely excised. The exact cell responsible for the development of a DFSP has been a matter of controversy for several decades; however, most histochemical and electron microscopic studies support a fibroblastic origin, with the tumor cells staining uniformly for vimentin and containing active endoplasmic reticulum synthesizing collagen.

[Determination of water soluble silicon from herbal drugs].

This article has set up a method for silicon determination by ammonium molybdate-ferrous sulfate-sodium carbonate spectrophotometry. The method is simple, convenient, quick, effective and free of the influence of phosphate ion and reducing agents such as vitamin C and so on. By this method water soluble silicon has been determined in 38 herbal drugs.