482 JOURNAL OF COSMETIC SCIENCE lcvcl of the water barrier function (Trans-Epidermal-Water- Loss-TEWL- measurements), which depends directly on the skin hydration state. This intimate linkage of the desquamation process and the water content of the stratum corneum enable us to suggest an indirect assessment of the hydration from a direct study of the desquamation by examining a skin stripping sample (D-Squames ©) by an optical microscope (linked to a computer). Wc will describe this already known technique and mainly its new and unpublished semiological exploitation, named Diagnoskin ©, whose advantages are its simplicity and its reproducibility particularly interesting in thc case of sequential appraisal of dcrmatological or cosmetic treatments. Dielectric Spectroscopy Of Concentrated Cosmetic W/O- Emulsions-Possibilities To Distinguish Product Changes Caused By Coalescence, Sedimentation And Variation of Ingredients change the results for the examined emulsions. Quantitative information about mean droplet size is possible with calibration. Because of their different physical forci, theology and dielectric spcctroscopy complement each other in high scnsitive detection ofcoalcscence. In contrast to the mechanical properties of W/O-cmulsion, dielectric spectroscopy givcs additional information concerning some reasons of change in emulsion structure. Mechanism like sedimentation and coalescence can be distinguished and the phase where changes take place (oil phase or water phase) can be located. The latter is possible by a new parameter - the correlation between maximum of dielectric loss 5"(fR) and the relaxation frequency fR. Their correlation can be described by a simple power law. By coupling theology and dielectric spectroscopy, an improvement in fast emulsion development and production control may be achieved without losing the advantage of a quick and easy measurement procedure. S. Friedrich •*, R. Brummer •, K.-P. Wittern •, B. Hochstein* • Beiersdorf AG, Rheologie/Thermoanalytik, Unnastr. 48, 20245 Hamburg, *Institut fiir Mechanische Verfahrenstechnik und Mcchanik, Universit•it Karlsruhe (TH), Kaiserstr. 12, 76131 Karlsruhe A quick result whether a newly developed cosmetic W/O- emulsion shows constant sensory behavior (stable) or whcther it changes its behavior over time (instable) is an important aspect in cosmetic research. In order to observe changes as quickly as possible, analytic mcthods are used. An established method is theology, a sensitive method that gives direct information on sensory aspects. Additional information concerning the kind of instability allow a more focused improvement of formulation in the case of instabilities. In order to gain this information, an additional analytic method with a more ingredient specific focus is needed. In this articlc the possibilities of using dielectric spectroscopy in order to get additional inlBrmation are discussed. For concentrated W/O-emulsions a dependence of emulsion behavior from volume median droplet diamcter dye0 is visible by both methods: theology and dielectric spectroscopy. A variation of droplet size distribution at constant volumc median droplet diameter dye0 does not Post-Adolescent Acne H. E. Knaggs*, E.J. Wood õ, R.L. Rizer •, O.H. Mills • *Unilever Research, 45 River Road, Edgewater NJ 07087, USA, õ School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, aStephens and Associates, Inc., Colorado Research Center, 5050 Edison Avenue, Suite 202 , Colorado Springs, Colorado 80915, USA, •UMDNJ Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA. Although acne has traditionally been viewed as predominantly affecting adolescents, a significant and growing body of literature suggests an adult (i.e. post- adolescent) form of the disease. This review summarises selected publications on post-adolescent acne, and discusses possible causes and treatment options. Recent epidemiological studics show that there appears to be an increasc in post-adolescent acne, and that the diseasc is lasting longer and is requiri•g treatment well into the mid forties. There is good agreement that, unlike teenage acne, where males tend to show the most severe forms of the disease, post-adolescent acne mainly affccts females (the lesions are f?cquently peri-oral and occur premenstruatly)

ABSTRACTS 483 and that there are two forms of the disease. The terms "persistent" and "late onset" are now generally accepted as describing these two types. The causes of post-adolescent acne remain to be fully elucidated and hormones, colonisation by resistant bacteria and the use of cosmetics have been put forward and debated in the literature. Additionally, some clues to the cause of post-adolescent acne may be gleaned from an individual's response to therapy. Perhaps one of the most intriguing explanations for the increase in this disease is the proposed relationship between increasing stress levels, androgen hormones and increasing levels of acne found in women in fast paced jobs. Amphiphilic Association Structures In A Model Skin Lotion With Hydroxy-Acids *Abeer A1-Bawab, #Stig E. Friberg *Chemistry Department, Faculty of Science, University of Jordan, Amman, Jordan, #Chemistry Department, Faculty of Science, Clarkson University, Potsdam 13699, NY, U.S.A The phase diagrams were determined of lactic and isohexanoic hydroxy- acids as well as salicylic acid with water, a nonionic surt•ctant and a paraffinic oil to outline the influence of the hydroxy-acids on the structure in a model for a skin lotion. The results showed the influence of the acid to be similar to that of the oil, but that the difference in chain length between the two alpha acids had only insignificant influence. The results are discussed from two aspects the structures involved in the lotion as applied and the action of the lotion residue on the skin after the evaporation of the water. Generation Of Volatile Fatty Acids By Axillary Bacteria A.G. James, D. Ityliands and H. Johnston* Unilever R&D Colworth, Colworth House, Shambrook, Bedford MK44 1LQ, U.K. *Current affiliation: University of Abertay, Dundee, UK) Presented in part at the 22 nd IFSCC Congress, Edinburgh 2002 It is generally accepted that short chain (C2-C•) volatile fatty acids (VFAs) are among the causal molecules of axillary malodour. It is also widely acknowledged that malodour generation is attributable to the biotransformation of odourless natural secretions, into volatile odorous products, by axillary bacteria. However, little information is available on the biochemical origins of VFAs on axillary skin. In these studies, assay systems were developed to investigate the generation of VFAs from substrates readily available to the bacteria resident on axillary skin. Propionibacteria and staphylococci were shown to ferment glycerol and lactic acid to the short chain (C2-C3) VFAS, acetic and propionic acid. Furthermore, staphylococci are capable of converting branched aliphatic amino acids, such as leucine, to highly odorous short chain (C4-C•) methyl- branched VFAs, such as isovaleric acid, which are traditionally associated with the acidic note of axillary malodour. However, in vitro kinetic data indicates that these pathways contribute less to axillary VFA levels, than fatty acid biotransformations by a recently defined sub- group of the Corynebacterium genus, corynebacteria (A). The results of these studies provide new understanding on the biochemical origins of VFA-bascd axillary malodour which, in turn, should lead to the development of novel deodorant systems.