Skin physiology in men and women: <i>in vivo</i> evaluation of 300 people including <scp>TEWL</scp>,<scp> SC</scp> hydration, sebum content and skin surface pH

“…While the surface pH of normal RHS in our study slightly exceeded the pH of other normal RHS [20] and normal skin in humans [37], the NMSC models captured a clear trend to increased pH values. The surface pH of the cSCC-ED model was very close to the extracellular pH 6.7-6.9 of solid tumors [38] and resulted from poorly differentiated SCC-12 cells [15].…”

“…Lipid esters were elevated following treatment with the test emollient; however, their penetration was limited. Sebum is a source of triglycerides (lipid esters) on the skin surface, and its production was found to decline in women with advancing age [52]. The level of total lipids, which includes non-physiological lipids (of white soft paraffin and liquid paraffin), increases significantly following treatment with both topical emollients.…”

“…The biological process of wrinkle development largely depends on an age-related increase in TEWL and a decrease in sebum secretion (21). It is suggested that both an increase in stratum corneum hydration and a reduction of TEWL contribute to these effects.…”