38 JOURNAL OF THE SOCIETY. OF COSMETIC CHEMISTS stand the reasons for the glycol-lipid synergy, however, physical characterization of the lotions will be required, especially in situ on the skin surface after evaporation of excess water. In conclusion, glycerol-based lotions, with bilayer-forming lipids, phospholipid, cho- lesterol, and stearic acid, restored xerotic skin conditions to normal more rapidly com- pared to those with petrolatum, cholesterol, and stearic acid. Such lotions, through their ability to optimally restore stratum corneum moisturization by enhancing barrier func- tion and improving humectancy, should permit or reestablish normal desquamation, thereby facilitating the rapid alleviation of skin xerosis. ACKNOWLEDGMENTS We wish to thank Miss A. van den Berg of the School of Pharmacy, Medunsa, Ms Joan Lane, and Mrs Helen McArthur of Unilever Research, Colworth Labs, for assistance with logistical arrangements and assessment and statistical analysis. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) A. V. Rawlings, I. R. Scott, C. R. Harding, and P. A. Bowser, Stratum corneum moisturization at the molecular level, J. Invest. Dermatol., 103, 731-740 (1994). R. O. Potts and M. L. Francoeur, The influence of stratum corneum morphology on water perme- ability. J. Invest. Dermatol., 96, 495-499 (1991). P.M. Elias and D. S. Friend, The permeability barrier in human epidermis, J. Cell Biol., 65, 180- 191 (1975). P. W. Wertz, Epidermal lipids, Semin. Dermatol., 11, 106-113 (1992). S. A. Long, P. W. Wertz, J. S. Strauss, and D. T. Downing, Human stratum corneum lipids and desquamation, Arch. Dermatol. Res. 277, 284-287 (1985). A. V. Rawlings, J. Rogers, and J. M. Mayo, Changes in lipids in the skin aging process, Biocosmet. Skin Aging, 1, 31-45 (1993). A. V. Rawlings, J. M. Mayo, J. Rogers, and I. R. Scott. Aging and the seasons influence on stratum corneum lipid levels,J. Invest. Der matol., 101, 483 (1993). S. Motte, S. Mellesi, and M. Sesana, Study of interlamellar lipids in psoriatic scales, Proceedings of the 18th World Congress of Dermatology, Abstract 159 (1992). P. W. Wertz, K. C. Madison, and D. T. Downing, Covalently bound lipids of human stratum corneum, J. Invest. Dermatol., 92, 109-111 (1989). A. Yamamoto, S. Srizawa, M. Ito, and Y. Sato, Stratum corneum lipid abnormalities in atopic derma- titis, Arch. Dermatol. Res., 283, 219-223 (1991). Y. Werner, M. Lindberg, and B. Forslind, Membrane-coating granules in "dry" non-eczematous skin of patients with atopic dermatitis, Acta Derm. Venereol., 67, 385-390 (1987). M. L. Williams, "Lipids in Normal and Pathological Desquamation," in Advances in Lipid Research, P.M. Elias, Ed. (Academic Press, New York, 1991), pp. 211-262. D. Saint-Leger, A.M. Francois, J. L. Leveque, T. K. Stoudemayer, A.M. Kligman, and G. Grove, Stratum corneum lipids in winter xerosis, Dermatologica, 178, 151-155 (1989). A. V. Rawlings, J. Hope, J. Rogers, A.M. Mayo, and I. R. Scott, Mechanisms of desquamation: New insights into dry flaky skin conditions, Proceedings of the 17th IFSCC, 2, 865-880 (1992). A. V. Rawlings, A. Watkinson, J. Rogers, A.M. Mayo, J. Hope, and I. R. Scott, Abnormalities in stratum corneum structure, lipid composition, and desmosome degradation in soap-induced winter xerosis, J. Soc. Cosmet. Chem., 45, 203-220 (1994). J. L. Levelque, J. C. Garson, and J. De Rigal, Transepidermal water loss from dry and normal skin, J. Soc. Cosmet. Chem., 30, 333-343 (1979). T. Egelrud, Purification and characterization of stratum corneum chymotryptic enzyme. A protease that may be involved in desquamation, J. Invest. Dermatol., 101, 200-204 (1993).

EFFECT OF LIPIDS ON SKIN XEROSIS 39 (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) Y. Suzuki, J. Nonura, J. Hori, J. Koyama, M. Takahashi, and I. Horri, Detection and character- ization of endogenous protease associated with desquamation of stratum corneum, Arch. Dermatol. Res., 285, 372-337 (1993). A. V. Rawlings, J. Hope, A. W. Watkinson, C. R. Harding, and T. Egelrud, The biological effect of glycerol, J. Invest. Dermatol., 100, 526 (1993). A. V. Rawlings, C. R. Harding, A. Watkinson, J. Banks, C. Ackerman, and R. Sabin, The effect of glycerol and humidity on desmosome degradation in the stratum corneum, Arch. Dermatol. Res., 287, 457-464 (1995). M. M. Reiger and D. S. Deem, Skin moisturizers II: The effect of cosmetic ingredients on human stratum corneum, J. Soc, Cosmet, Chem., 25, 253-262 (1974). E. K. Boisits, G. E. Nole, and M. Cheney, The refined regression method, J. Cut. Aging Cosmet. Derm., 1, 155-165 (1989). D. L. Bissett andJ. F. McBride, Skin conditioning with glycerol,J. Soc. Cosmet. Chem., 35, 345-350 (1984). K. Laden, The role of glycerol in skin hydration, J. Soc. Cosmet. Chem., 13, 455-458 (1962). C. L. Froebe, F. A. Simion, H. Ohlmeyer, L. D. Rhein, J. Mattai, R. H. Cagan, and S. E. Friberg, Prevention of stratum corneum lipid phase transition by glycerol--An alternative mechanism for skin moisturization, J. Soc. Cosmet. Chem., 41, 51-65 (1990). J. Mattai, C. L. Froebe, L. D. Rhein, F. A. Simon, H. Ohlmeyer, D. T. Su, and S. E. Friberg, Prevention of model stratum corneum lipid phase transitions in vitro by cosmetic additives-- Differential scanning, calorimetry, optical microscopy, and water evaporation studies, J. Soc. Cosmet. Chem., 44, 89-100 (1993). R. Ghadially, L. Halkier-Sorensen, and P. M. Elias. Effects of petrolatum on stratum corneum structure and function, J. Am. Acad. Dermatol., 26, 387-396 (1992). M. Man, K. R. Feingold, and P. M. Elias, Exogenous lipids influence permeability barrier recovery in acetone-treated murine skin, Arch. Dermatol., 129, 728-738 (1993). G. Imokawa, S. Akasaki, Minematsu, and M. Kawai, Importance of intercellular lipids in water retention properties of the stratum corneum: Induction and recovery study of surfactant dry skin, Arch. Dermatol. Res., 281, 45-51 (1989). G. Imokawa, S. Akasaki, K. Kawamata, S. Yano, and N. Takaishi, Water-retaining properties in the stratum corneum and its recovery properties by synthetic pseudoceramides, J. Soc. Cosmet. Chem., 40, 273-285 (1989). G. Imokawa, H. Kuno, and M. Kawai, Stratum corneum lipids serve as bound water modulator, J. Invest. Dermatol., 96, 845-851 (1991).