Keratinocytes, cosmetics

Studies carried out with complete cells in vivo, cell membranes and other cell fractions point to the selective oxidation of phosphatidylserine (26) to a hydroperoxide (PS-OOH) on oxidative stress caused by toxic agents such as H2O2, t-BuOOH and cumyl hydroperoxide (27). Formation of PS-OOH is observed during apoptosis. These phenomena are important because of the cytotoxic effects of various peroxides used in commercial products coming into direct contact with the human body, as is the case of epidermal keratinocytes in contact with cosmetic formulations" ". The toxic effects of f-BuOOH are associated with vasoconstriction and damage to the vascular smooth muscles ". Global determination methods for primary lipid oxidation products are discussed in Section IV.B. 

Keratinocytes, cosmetics, 613 a-Ketoalkyl radicals, 252 y-Ketoalkyl radicals, 252 of-Keto esters, benzylic oxidation, 518 2-Ketoglutarate, hydrogen peroxide determination, 655... 

True hair is found only in mammals, and there is no such thing as a completely hairless mammal. Hair itself is dead, but is produced in hair follicles by specialized keratinocytes at the base of the hair. The outermost layer of hair is a cuticle, and most hairs have a cortex in which the dead keratinized cells are very densely packed, and an iimer medulla in which they are not as densely packed. The pigmentation in hair, like that of skin, comes from melanocytes. Hair exposure to some chemicals may produce hair discoloration, for example, green hair from copper in water or cosmetics, or blue hair in cobalt workers. 

Skin lipids of humans differ markedly from those of other animals (Nicolaides etaL, 1968). Comments in this section relate to humans. Lipogenesis stems from two skin cell types - sebocytes in the sebaceous glands and the keratinocytes in the keratinizing epidermis. The lipids of the two cell types are quite different and may fulfil separate physiological functions (Nicolaides, 1965). In humans total surface lipids are, therefore, derived from the sebaceous glands, the keratinizing epidermis and external sources such as soaps, cosmetics or atmospheric pollutants (Burton, 1979). 

CN and their derivatives can be used in cosmetic dermatology to modulate the skin barrier activity and bettering the turnover of keratinocytes and fibroblasts. Moreover, their natural origin gives to CN a particular safeness and efficacy avoiding any kind of side effects. 

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