372 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS simulated teeth. Fourteen different brushes with varying designs and textures were evaluated. Cleaning efficiency improved with softer texture and increasing pressure. At similar bristle textures, V-shaped brushes had significantly better cleaning efficiency than straight multitufted toothbrushes. Two new clinical studies supported these laboratory findings. Transepidermal moisture loss iv: the effect of moisturizers on dry skin on the back of the hand Michael Cheney, G. Berube, F. Tranner, P. Miner, Chesebrough-Pond's Inc., Trumbull Industrial Park, Trumbull, CT 06611. A series of studies were conducted to evaluate the difference in transepidermal water loss (TEWL) between normal skin, dry skin, and dry skin treated with different moisturizers. The measurement sys- tem uses a carrier gas to "pick up" moisture from the back of the hand (as opposed to the volar forearm) and deliver it to a dew point analyzer. The carrier gas has been "humidified" to 20% RH, which is more reflective of the "in-use" conditions of moisturizing products. Data from three studies conducted over the last three years showed that the TEWL rates for dry skin (soap enhanced) increase significantly over baseline (normal skin) readings, while product application reduces the TEWL closer to pretreatment values. Supportive data including scanning electron microscope photographs, instru- mental assessments, and visual scoring will be included. The importance of this protocol in direct- ing the formulation and evaluation of skin care products is discussed. Set relaxation of human hair Penelope Diaz, Michael Y.M. Won& Clairol Research Laboratories, 2 Blachley Road, Stamford, CT 06902. Although hair can be effectively set by water, heat, or both, such temporary sets do relax over time. It has been found that the set relaxation process can be adequately described, over a wide range of humidity, by the expression Y = aT b, where Y is the amount of set remaining after an exposure to humidity for a period of time T, and a and b are constants. In fact, the integrated form of this equation can conveniently be used to compare the effectiveness of hair sprays, setting parameters, etc. SYMPOSIUM ON COSMETIC EVALUATION Evaluation of hand and body lotions: correla- tion of objective and subjective responses John P. McCook, Gene R. Berube, Chesebrough- Pond's Inc., Trumbull Industrial Park, Trumbull, CT 06611. Various testing techniques or methodologies are used in the development, screening, selection, and comparative testing of hand and body lotions. These test methods may include in-vitro instru- mental analysis or in-vivo testing. In-vivo human testing can involve laboratory panels, home place- ment, or consumer panels, as well as clinical testing. Measurement of the overall performance of hand and body lotions for relief of dry skin symptoms as well as measurement of aesthetic qualities and consumer acceptance can be accomplished via panel testing and clinical testing. Subjective responses from panelists or consumers as well as objective measurements by trained judges or clini- cians are used to determine efficacy, product accep- tance, and overall performance. This paper presents the results of various panel tests and clinical evalua- tions designed to measure product efficacy and consumer acceptance. Through graphic representa- tion, objective and subjective data are given for various hand and body lotion products. Relative value and correlation of subjective and objective responses are discussed. Results show good corre- lation of subjective and objective assessment of hand and body lotion performance. Radiotracer and autoradiographic studies of cosmetic products Raymond L. Sheath, Ph.D., J.G. Gould, H.T. Fox, The Gillette Company, Gillette Park, Boston, MA 02106. The classic subjective and objective methods are and may continue to be the primary means of evaluating hair care products. However, with increasing frequency, newer techniques are appearing which can provide more detailed infor- mation concerning specific interactions of cos- metic products with hair. During the last twenty years, radioisotopes have been widely used for laboratory evaluation of hair care products. These standard radiotracer techniques have recently been extended to include autoradiographic studies which permit direct visualization of the sites of interaction of cosmetic products with hair fibers. This combination of techniques has proven to be a very accurate measure of substantivity, penetration, and reactivity and also may provide important insights into the mechanism by which products deliver the desired benefit. Numerous cosmetic treatments, including conditioners, have been stud- ied. The results of several conditioner studies provided the basic claim support for a line of products. These and several other radiotracer and autoradiographic studies are discussed.

ABSTRACTS 373 Evaluation of facial care products Michael S. Christensen, Ph.D., Vick Divisions Research Development, One Far Mill Crossing, Shelton, CT 06484. The facial skin of many individuals is excessively oily or excessively dry. Skin care products thus need to be compatible with either oily or dry skin. This holds true whether the formulations are for cosmetic purposes only or for delivery of thera- peutic (acne) or prophylactic (sunscreen) agents to the skin. Formulating such compatible products requires accurate, objective assessment of oiliness in-vivo. Oiliness is assessed by measuring skin surface friction this characteristic varies on dif- ferent parts of the face and it may be altered by product application. Dryness is assessed by measur- ing the tautness of the stratum corneum which may result, for example, from ordinary washing with soap and water, or from application of products which have a drying effect on the skin. In this assessment, we use a gas-bearing electrodynamom- eter suitably adapted for measurements on the face. These objective measurements correlate well with clinical appraisals of oiliness and dryness, and the comparison has shown that differences that can be perceived by product users are easily measured by our instrumentation. SOCIETY OF COSMETIC CHEMISTS FRONTIERS OF SCIENCE LECTURE H. Gobind Khorana, Ph.D., Massachusetts Insti- tute of Technology, Cambridge, MA 02139. This lecture contains four parts. 1) Origins of Nucleic Acids. Since the discovery of nucleic acids in 1869, work progressed for about 80 years on the develop- ment of their chemical structures: the chemistry of pyrimidines and purines, nucleosides and nucleo- tides. This culminated in the elucidation of the polynucleotidic structures in 1953 and this, in turn, led to the Watson-Crick model. A second indepen- dent development relates to the biological func- tions of the nucleic acids and in particular their role as genetic material and the participation of a variety of nucleotide intermediates in intermediary meta- bolism. 2) The Synthesis of Nucleic Acids. Work on the chemical synthesis of nucleic acids began in the 50's and 60's and the main steps in the development are reviewed. 3) The Genetic Code. A combination of biochemical methods and chemical synthesis led to the elucidation of this central biological problem. A brief review of the solution to this problem is given. 4) Total Synthesis of Genes and IVork on Recombinant DNA. In more recent years, methods have been developed for the total synthesis of genes as well as for the sequence determination of nucleic acids. The two together have led to exciting new developments in the work on recombinant DNA. The last part of the lecture is devoted to principles of some of the current work involving techniques of recombinant DNA. SYMPOSIUM ON LIPIDS Stratum corneum lipids Peter M. Elias, M.D., Veterans Administration Medical Center, 4150 Clement Street, San Francis- co, CA 94121. Evidence from freeze-fracture replicas of several mammalian stratified squamous epithelia provides the first solid clue that the stratum corneum is a two-compartment system of lipid-depleted cells embedded in multi-lamellar lipid domains. Rela- tively complete lipid biochemical data are now available from human, pig, and neonatal mouse stratum corneum all suggest that the stratum corneum is devoid of phospholipids, but enriched in several neutral lipids and sphingolipids. During progression from the inner to the outer stratum corneum, additional changes in composition prob- ably occur cholesterol sulfate is desulfated to cholesterol, and glycolipids are deglycosylated to ceramides. Specific enzymes that catabolize both of these processes have been found in the outer epidermis. Evidence is growing that these biochem- ical transitions are important for the formation of a water-resistant barrier and for stratum corneum cohesion desquamation. The two-compartment model also has other important implications for pathways of percutaneous transport, reservoir effects, vehicle delivery systems, and the water- holding capacity of the stratum corneum that are discussed. The structure and physiological role of lipids in the epidermal barrier to percutaneous water loss Donald T. Downing, Ph.D., Philip W. Wertz, Ph.D., University of Iowa College of Medicine, Iowa City, IA 52242. It has long been recognized that the epidermal barrier to water lbss possessed by terrestrial verte- brates is dependent upon the lipids of the stratum corneum. Studies have shown that the lipids exist principally in the spaces between horny cells and consist predominantly of highly polar, non-phos- phorus-containing structures. The stratum corneum lipids consist of cholesterol, free fatty acids, ceram- ides and gangliosides. In the living cells of the epidermis there is in addition a series of glucosyl- ceramides. The authors have now determined the structures and detailed composition of each of the series of ceramides and glucosylceramides from pig epidermis. As a result, the structure and location of