30 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS cacodylate buffer) for 15 minutes. The cold buffer rinse and soak procedure above was then repeated. The stratum corneum was dehydrated by soaking in acetone solutions (25%, 50%, 70%, 95%, 100%, 100%, 100%) for 15 minutes each. The stratum corneum was then infiltrated with Spurr resin:acetone solutions (50:50 v/v for 18 hours 70:30 for 3 hours 90:10 for 30 minutes 100:0 for 30 minutes 100:0 for 18 hours). After cutting the stratum corneum from the nylon mesh, the stratum corneum was embedded in fresh Spurr resin and cured at 60øC for approximately 72 hours. Sections were cut (500-600 angstroms), stained with uranyl acetate and lead citrate, and viewed using the JEOL 1200EX electron microscope. IN VIVO DRY SKIN STUDIES Panelist screening criteria. Each study group was comprised of Caucasian women aged over 25, who are susceptible to dry skin and could therefore be expected to show the clearest response to moisturization treatment. None of the panelists took part in any other study for the duration of these studies. All of the panelists were healthy and free of any medical or physiological condition that might affect the assessment of skin or its reaction to the treatment plan. The panelists were not regularly taking drugs or medication and were not nursing or knowingly pregnant. All panelists gave written and witnessed informed consent. Experimental design. These were double-blind, fully randomized clinical trials. All treat- ments and assessments were conducted on the dorsal aspect of the hands. The same protocol was used in each trial and consisted of the following three phases: (1) seven-day "dry-down" (2) 14 days of treatment (3) five days of regression. During the dry-down phase all panelists washed the back of their hands between two and four times a day with soap to induce dryness. The treatment phase consisted of twice- daily product application (am and pm) with continued soap washing (two times per day). During the regression phase, panelists ceased all product application, but contin- ued with the twice-daily soap washing. In addition, all panelists abstained from using any other moisturizer on or near the hand during all phases. In each study group, 75 panelists who underwent the dry-down had their hands visually assessed for dryness on Day 1 of the study, using a seven-point hand dryness scale (see Table I for grading scale). The grading was carried out using an Optivisor © with a number 10 lens (mag. x 3.5) and an Anglepoise © lamp with a 60-watt daylight bulb. The 66 panelists that best met the dryness criterion of grade-5 dryness score on Day 1 were selected to continue with the treatment and regression phases. Each panelist was randomly assigned to a pair of treatments, and one treatment was tested on each hand. The treatments were allocated such that each treatment was tested on 11 hands of 11 panelists, balanced for right and left hands. Treatment products were packed for individual panelist use, in containers fitted with dispensers that delivered 0.5-ml aliquots, with each panelist receiving approximately 100 g of each of the two formulations assigned to her. Panelists were shown how to dispense and apply the product (0.5 ml per application, two times per day). To enable comparison between studies, two control treatments were included in each study. These were an untreated control (negative control) and a standard commer- cial moisturizer (positive control). The skin condition of the backs of the hands was visually assessed as described above on Days 3, 5, 8, 10, and 12 of the treatment phase, and on'Days 15, 17, and 19 of the

EFFECT OF LIPIDS ON SKIN XEROSIS 31 Table I Skin Dryness Grading Scale Grade Description Normal, moist skin. Dermatoglyphics present as bunched or stacked triangles, plump and evenly spaced. Skin tone even and uniform with a slight shine. Individual dermatoglyphics more visible due to whitening borders. Isolated small flakes of dry skin and slight wrinkling may appear. Broad white borders to dermatoglyphics, in which corners or small portions have started to lift and peel. Small dry skin flakes give a "light powdery" appearance. Skin puckering may occur, as well as small red dots. Entire sides of dermatoglyphics lift and peel back to create large dry skin flakes and rough appearance. Redness more evident. Almost all dermatoglyphics lift and demonstrate flaking, with flakes anchored at one end to produce an alligator skin appearance. Uneven, rough appearance is obvious. Uniform redness looks like mild sunburn. Dermatoglyphics disappear completely to produce flaking, cracking, and a dry, powdery appearance, with deep furrows and redness below, more like a moderate sunburn. Skin looks abraded. Intense flaking and scaling give a chalky or crusty appearance, with cracking, fissuring, extreme redness, and possibly open abrasions and bleeding. regression phase. All assessments were made prior to the morning product application (treatment phase) and at least one hour after washing. Product treatment comparisons. The treatment effects of the particular formulations that will be compared in this paper contained the following actives: 1. Glycerol (1%) 2. Phospholipid, cholesterol, and stearic acid (4%, 1:2:1) 3. Phospholipid, cholesterol, and stearic acid (4%, 1:2:1) and glycerol (1%) 4. Phospholipid, cholesterol, and stearic acid (4%, 1:2:1) and glycerol (5%) 5. Vaseline © Petroleum Jelly, cholesterol, and stearic acid (4%, 1:2:1) and glycerol (5%). The above products were prepared as aqueous, thickened (xanthan gum, 1%) and preserved (DMDM hydantoin, 0.2%) lotions adjusted to pH 7 (sodium hydroxide, hydrochloric acid). Statistical analysis. All comparisons were performed using repeated Wilcoxon rank sum tests. The critical significance level was adjusted to maintain an overall level of 5%. RESULTS ELECTRON MICROSCOPY OF STRATUM CORNEUM In the electron micrographs of normal stratum corneum that has not undergone the delipidization treatment described earlier, the typical lameilar lipid structure can be seen in the intercellular spaces of the stratum corneum (Figure 1A). In comparison, the intercellular lipids are clearly removed in the delipidized stratum corneum treated only with the vehicle (Figure lB). Comparison of the effect of the two lipid treatments on delipidized stratum corneum indicates that phospholipid-cholesterol-stearic acid treat-