172 JOURNAL OF COSMETIC SCIENCE types in diameters, ellipticity, bending stiffness and friction. The results lead to conclude that 'handle' is perceived as inferior when the hair is thick and bending stiffness thus high. For such hair differences in handle rating are related to differences in friction, namely in the tip region. For thin and th11 'soft' hair fihre friction seems to play only a minor role. A Method for the Determination of N- nitrosodiethanolamine in Personal Care Producl'I - Collaboratively Evaluated by the CTPA Nitrosamines . Working Group C. Flower4', S. Cartert, A Earlst, R Fowlert, S. Hewlins§, S. Lalljie\ M. Lefebvre••, J. Mavro .. , D. Smalltt and N. Volpett A procedure for the determination of N- nitrosodiethanolamine (NDELA) in personal care products was evaluated in collaborative studies by member organizations of the United Kingdom's Cosmetic Toiletry and Perfumery Association (CTPA) and LGC Limited, formerly known as the Laboratory of the Government Chemist (LGC). Samples were prepared depending on the matrix of the cO!lmetic product: aqueous samples were prepared by diluting in water followed by solid-phase extraction emulsions, oils and solid materials were dissolved in dichloromethane and extracted with water. NDELA was separated from the sample matrix using reverse-phase liquid chromatography. The N-nitroso bond was cleaved by photolysis to give nitrite, which was colorimetrically quantified. The nitrite functional group reacted with sulphanilamide in an acid medium to form a diazonium ion which was then coupled with N-(1- naphthyl)ethylenediamine dihydrochloride according to the Griess reaction to give a purple-coloured azo dye that absorbed at 540 run. Compared with other published methods for NDELA, the method described here is quick and easy to use. It has the required sensitivity and specificity, and can accurately and reliably quantify NDELA in a wide range of personal care product matrices. Nitrosodiethanolamine in Personal Care Producl'I - Collaboratively Evaluated by the CTPA Nitrosamines Working Group IJCS 28 (1) 21-34 (2006) C. Flower4', S. Cartert, A. F.arlst, R Fowlert, S. Hewlins§, S. Lalljie\ M. Lefehvre••, J. Mavro••, D. Smalltt and N. Volpett A procedure for the determination of N- nitrosodiethanolamine (NDELA) in personal care producl'I was evaluated in collaborative studies by member organizations of the United Kingdom's Cosmetic Toiletry and Perfumery Association (CTPA) and LGC Limited, formerly known as the Laboratory of the Government Chemist (LGC). Samples were prepared depending on the matrix of the cosmetic product: aqueous samples were prepared hy diluting in water followed hy solid-phase extraction emulsions, oils and solid materials were dissolved in dichloromethane and extracted with water. NDELA was separated from the sample matrix using reverse-phase liquid chromatography. The N-nitroso bond was cleaved by photolysis to give nitrite, which was colorimetrically quantified. The nitrite functional group reacted with sulphanilamide in an acid medium to form a diazonium ion which was then coupled with N-(1- naphthyl)ethylenediamine dihydrochloride according to the Griess reaction to give a purple-coloured azo dye that ahsorbed at 540 nm. Compared with other published methods for NDELA, the method described here is quick and easy to use. It has the required sensitivity and specificity, and can accurately and reliably quantify NDELA in a \\ide range of personal care product matrices. The Suppressive Effect of Apricot Kernel Extract on Sn- Androst-16-en-3-one Generated hy Microbial Metabolism• S. Mikoshiha, H. Takenaka, T. Ol-'l..lmura, K. Someya and M. Ohdera Body odours are generated from dead skin cells and secreted materials, such as sweat and sehum, through the metabolism of microorganisms living on the skin. Volatile steroids, key compounds in body odours, are also generated through the metaholism of microorganisms. These volatile steroids strengthen the intensity of the overall body malodour and are sensed differently by males and females. Females are more sensitive than males to volatile steroids, especially Sn-androst-16-en-3-one (androstenone). To regulate body odours that are especially unpleasant for women, we devised an androstenone-generation model using the metabolism ofCorynehacterium xerosis, which is one of the bacteria living on the axillary skin. Using this model, we studied the suppressive effect of plant extracl on the generation of androstenone. We found that apricot kernel extract (AKE) had the most positive effect among the plant extracl'I to which we applied the model. However, although AKE did suppress androstenone generation, it did not show any bactericidal effect. Using the cell-free system, AKE also suppressed the generation of androstenone. In conclusion, we found that AKE suppressed the generation of androstenone, which is especially unpleasant for women, and the mechanism was not hactericidal but metabolic inhibition. The resull of these studies provide new understanding of the regulation of androstenone, which, in tum, should lead to the development of novel deodorant systems. Studies of Compounds that Enhance Sphingolipid Metabolism in Human Keratinocytes1 I. Popa•t, K. Bennaceur", N. Abdul-Malakt, E. Peniert, D. Schmitt• and J. Portoukalian• Several producl'I are known to inhibit the hiosynthesis of ceramides and glucosylceramides, hut very few stimulate this process. We studied the influence of a hydrolysate of potato proteins (Lipidessence\'J) in vitro on the sphingolipid metabolism of normal human epidermal keratinocytes. By measuring growth with the thymidine uptake assay, it was seen that Lipidessence\'J, added in the culture medium up to an 8% concentration, did not change significantly the proliferation rate of keratinocytes, hut beyond this

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.