Stratum corneum drying drives vertical compression and lipid organization and improves barrier function in vitro.

The stratum corneum dehydrates after exogenous hydration due to skincare or bathing. In this study, sheets of stratum corneum were isolated from reconstructed human epidermis and the barrier function and structure of these sheets were assessed during drying with the aim of improving our understanding of skincare. Water diffusion through the sheets of stratum corneum decreased with drying, accompanied by decreased thickness and increased visible light transmission through the sheets. Electron paramagnetic resonance revealed that the order parameter values of stratum corneum lipids increased with drying. X-ray diffraction analysis revealed increases in the diffraction intensity of lamellar structures, with an 11-12 nm periodicity and spacing of 0.42 nm for lattice structures with drying. These results suggest that the drying process improves the barrier function of the stratum corneum by organizing the intercellular lipids in a vertically compressed arrangement.

Comparison of sagging at the cheek and lower eyelid between male and female faces.

BACKGROUND: Facial sagging is a well-known morphological feature associated with aging and reduced dermal elasticity. Its morphological characteristics and mechanism have been studied in females, but it is unclear whether or not there is a gender difference. AIMS: The aim of this study was to clarify the morphological characteristics of sagging and the mechanism of sagging formation in male faces as compared with female faces, focusing on changes in dermal elasticity. METHODS: Faces of 98 healthy Japanese male volunteers, in their 20s-60s, were photographed at an angle of 45°. Upper and lower cheek sagging severity was evaluated by using photograph-based grading criteria. In addition, new photograph-based grading criteria of sagging severity at the lower eyelid were established and used. Dermal elasticity was measured using a non-invasive, in vivo suction skin elasticity meter, Cutometer(®). Furthermore, photographs of 108 healthy Japanese female volunteers in their 20s-60s were used to compare the difference in the morphological characteristics of sagging between males and females. RESULTS: Male facial sagging was prominent at the lower eyelid, upper cheek and lower cheek. Sagging severity in the upper and lower cheek was almost the same between males and females at all ages, whereas sagging at the lower eyelid in males was significantly more severe than that in females after middle age. Although dermal extensibility (U(f)) was not related to age, total deformation recovery (U(a)), -(amount of deformation) -(U(f)-U(a)), overall elasticity of the skin including creep and creep recovery (U(a)/U(f)), net elasticity excluding viscoelastic creep (U(r)/U(e)), ratio of elastic recovery to total deformation (U(r)/U(f)) and -(ratio of viscoelastic to elastic distention) -(U(v)/U(e)) were all significantly negatively related to age in both men and women. Furthermore, as in female faces, male facial sagging was significantly negatively related to dermal elasticity parameters, such as -(U(f)-U(a)), U(a)/U(f), U(r)/U(e) and U(r)/U(f). CONCLUSION: These results indicate that the morphology and areas of sagging in male faces are similar to those in females in the cheek, but sagging at the lower eyelid is more severe in males after middle age. Furthermore, the dermal elasticity of male facial skin decreased with age similar to that of females, and may therefore be associated with the sagging formation in male faces.

Polyoxyethylene/polyoxypropylen dimethyl ether (EPDME) improves the structure of intercellular lipids in SDS-induced dry skin.

The dimethyl ether of an amphiphilic random ethylene oxide/propylene oxide copolymer (EPDME) is useful for the preparation of finely dispersed micro-emulsions. We examined whether EPDME is effective for skin moisturization by means of electron paramagnetic resonance (EPR) studies of ex vivo specimens of stratum corneum (SC) obtained by successive stripping. The values of the order parameter S obtained by EPR measurement indicated that EPDME treatment improved sodium dodecyl sulfate (SDS)-induced disruption of SC lipid structures. This effect appeared to be related to improved hydration of the epidermis, not occlusion by EPDME, since there was no significant change in transepidermal water loss (TEWL).

Depth dependence of stratum corneum lipid ordering: a slow-tumbling simulation for electron paramagnetic resonance.

We investigated the structural ordering of stratum corneum (SC) lipid by means of electron paramagnetic resonance (EPR) slow-tumbling simulation in conjunction with spin probe studies. The SC of human mid-volar forearm was stripped consecutively from three to six times. The EPR probe method detected a characteristic peak of sebaceous matter in the first SC stripping. The order parameter values obtained by the slow-tumbling simulation (S(0)) showed significant differences between each layer compared with those indicated by the conventional order parameter (S) using hyperfine couplings. Although the conventional S values were in the range of 0.56 (outermost layer) to 0.61 (bottom layer), the S(0) values by the simulation changed from 0.22 to 0.96. The present results suggest that the structural ordering of the outermost SC layer is less tight, whereas the structure of inner layers becomes more rigid. Therefore, we concluded that the EPR probe method recognizes sebaceous matters, whereas EPR in conjunction with the simulation allows quantitative evaluation of SC lipid ordering in relation to skin depth.