ABSTRACTS 173 concentration a progressive dose-dependent inhibition of grnwth was noticeable. Following incubation of cells with the product at 5% and I 0% concentrations for 2 days, the lipids were extracted. The different lipid classes were separated by fractionation on columns of aminopropyl silica gel and anal yz ed by high-performance thin-layer chromatography. When keratinocytes were cultivated in the presence of Lipidessence\'J, the biosynthesis of cholesterol, phosphatidylcholine, phosphatidylserine and gangliosides was stimulated, and a major increase was noticeable in the biosynthesis of free fatty acids, free ceramides, glucosylceramide and sphingomyelin. Radioactive f14Cl- serine was used as a precursor of sphingoid bases to study sphingolipid biosynthesis. After migration of lipid fractions on thin-layer plates, autoradiography showed that free ceramides and glucosylceramide were labeled, thu.'i suggesting that de novo biosynthesis was accounting for the increased cellular content in sphingolipids. Adaptive Response of the Skin to lNR Damage: Role of the p53 Protein L. Verschooten1, L. Declercq2 and M. Garmyn1 Different adapt.ltion mechanisms like heat shock response, cell cycle arrest and DNA repair, melanin pigmentation and thickening of the epidermis are presentation and thickening of the adverse effects of solar lN irradiation. When ON A damage is beyond repair, cells undergo apoptosis to prevent their replication. We discuss the current knowledge on these different adaptation mechanisms to lNB damage, the most energetic fraction of solar lN that reaches the skin. As p53 protein, the guardian of the genome, plays a key role in protective response to genotoxic damage, iL'I role in this adaptive response of the skin to lN will be further discussed.

J. Cosmet. Sci.J 57, 174-176 (March/April 2006) Abstracts IFSCC Magazine Vol. 9, No. 1, 2006* Ethnic Skin Types: Are there Differences in Skin Structure and Function? Author: Anthony V. Rawlings A VR Consulting Ltd., Kingsmead, Northwich, Cheshire CW98FH, UK People with skin of color comprise the majority of the world's population and Asian subjects comprise more than half of the total population of the earth. Even so, the literature on the characteristics of subjects with skin of color is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin color, which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes among the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally, Caucasians have an earlier onset of and greater skin wrinkling and sagging signs than other skin types, and in general increased pi gm entary problems are seen in subjects with skin of color although one large study reported that East Asians living in the USA had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease- activated receptor-2, which together with its activating protease is increased in the epidermis of subjects with skin of color. Changes in skin biophysical properties with age demonstrate that the more darkly pi gm ented subjects retain younger skin properties compared with the more lightly pi gm ented groups. However, despite having a more compact stratum comeum there are conflicting reports on barrier function in these subject . Nevertheless, upon a chemical or mechanical challenge the stratum corneum (SC) barrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to that of Caucasian skin and similar ceramide levels but upon mechanical challenge it has the weakest barrier function. Differences in intercellular cohesion are obviously apparent. In contrast, reduced stratum comeum natural moisturizing factor (NMF) levels have been reported compared with Caucasian and African American skin. These differences will contribute to differences in desquamation but very little data is available. One recent study has shown reduced epidermal cathepsin L2 levels in darker skin types which if it also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms, as the desquamatory enzymes are extruded with the lamellar granules, subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sebum secretion and skin surface microflora occur in Negroid subject . Equally, increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups but the stimuli for its induction show subtle differences. Nevertheless, several studies indicate that Asian skin may be more sensitive to exogenous chemicals, probably due to a thinner stratum corneum and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types but clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types. Fluorescence and Scanning Electron Microscopic Characterization of Cuticle Erosion in Human Hair Sigrid B. Ruetsch and Yash K. Karnath TRI/Princeton, 601 Prospect Ave., Princeton, NJ 08542, USA Environmental and natural grooming damage of hair were investigated by the microfluorometric method using Rhodamine B as the fluorescent tracer. An increase in fluorescence intensity of tracer-tagged hair as we moved from the root to middle section and tip end is indicative of weathering and progressive mechanical damage. The locus of Rhodamine B penetration and interaction occurs at the scale edge in the root end, changing to the scale face and scale edge * These abstracts appear as they were originally published. They have not been edited by the Journal of Cosmetic Science. 174