Effect of seasonal and geographical differences on skin and effect of treatment with an osmoprotectant: Sorbitol.

Human skin maintains an optimal permeability barrier function in a terrestrial environment that varies considerably in humidity. Cells cultured under hyperosmotic stress accumulate osmolytes including sorbitol. Epidermal keratinocytes experience similar high osmolality under dry environmental conditions because of increased transepidermal water loss (TEWL) and concomitant drying of the skin.

Osmotic stress induces terminal differentiation in cultured normal human epidermal keratinocytes.

The signals for epidermal differentiation and barrier formation are largely unknown. One possible signal is dehydration or osmotic stress. To test this hypothesis, we investigated the effects of osmotic stress on markers of differentiation of normal human keratinocytes in culture.

The cytoprotective effects of exogenous DNA fragments.

Ultraviolet irradiation of normal human keratinocytes induces a cytotoxic effect. The chromophore for this effect is believed to be genomic DNA. However, DNA damage is known to be repaired in UVB irradiated keratinocytes.