Mapping, in vivo, the uniformity of two skin properties alongside the human face by a 3D virtual approach.

OBJECTIVE: To determine the homogeneity in the distribution of two cutaneous functions (hydration and elasticity) along the entire human face. MATERIAL AND METHODS: The half faces (right or left, randomly chosen) of two groups of Caucasian women were measured on 24 different small sites (elasticity) and 41 others (hydration), by instruments of small-sized probes (Cutometer® and Corneometer® , respectively). Hydration of the face was recorded at different times (up to 24 h), post application of a highly hydrating product. The recorded values (left and right half faces) were further gathered and digitally positioned on a virtual feminine face and their intensity was illustrated through a colored white (lower values)-blue (higher values) scale. RESULTS: The reconstitution of the mapping of the two measured parameters (from the left and right sides of different subjects), shows a perfect symmetry vis à vis the nose axis. However, both parameters present slightly variable but significant values along the human face. Sites from the temple are less elastic than chin or forehead. The upper and lower parts of the forehead show slight disparities in their elasticity values. Cheeks are significantly less prone at retaining their imparted hydration status (lost 2 h after application of a hydrating product) as compared to sub-ocular regions or chin that retain their hydration up to 24 h. Attempts to establish a mutual relationship between the two skin properties unsurprisingly failed. CONCLUSION: The two studied skin properties show a slight but highly symmetric disparity along the entire human face.

Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages.

The facial skin of 354 women, aged 18-80, living in Shanghai, was investigated over two successive 6-month periods, summer and winter. Results from clinical assessments indicate that aging signs, such as wrinkling and sagging, are unaffected over such period. However, physical measurements revealed alterations in some functional criteria of the skin, such as sebum output, skin colour, melanin content of pigmented spots, skin hydration, all being increased during summer. The relationships between all criteria, as well as technical or applied inferences/consequences from this study, are discussed.

Skin responses to topical dehydroepiandrosterone: implications in antiageing treatment?

BACKGROUND: Although low dehydroepiandrosterone (DHEA) is suspected to have a role in skin ageing, little information is available on the mechanisms potentially involved. OBJECTIVES: To obtain information on androgen receptor (AR) and procollagen expression in ageing skin during DHEA treatment. METHODS: A placebo-controlled, randomized, prospective study was performed with 75 postmenopausal women aged 60-65 years. The women were treated twice daily for 13 weeks with 3·0 mL of placebo or 0·1%, 0·3%, 1% or 2% DHEA cream applied on the face, arms, back of hands, upper chest and right thigh where 2-mm biopsies were collected before and after treatment. RESULTS: Although the overall structure of the epidermis was not significantly affected at the light microscopy level, AR expression examined by immunocytochemistry was markedly increased by DHEA treatment. In the dermis, the expression levels of procollagen 1 and 3 mRNA estimated by in situ hybridization were increased by DHEA treatment. In addition, the expression of heat shock protein (HSP) 47, a molecule believed to have chaperone-like functions potentially affecting procollagen biosynthesis, was also found by immunocytochemistry evaluation to be increased, especially at the two highest DHEA doses. CONCLUSION: These data suggest the possibility that topical DHEA could be used as an efficient and physiological antiageing skin agent.

Importance of sunscreen products spreading protocol and substrate roughness for in vitro sun protection factor assessment.

The purpose of this study was to evaluate the impact of substrate roughness and of product spreading method on in vitro sun protection factor (SPF) measurement and to define the experimental conditions most appropriate to reach the best level of correlation to in vivo SPF. In vitro SPF assessment was carried out on 13 products (including different formulation types with SPF from 20 to 75) using various in vitro SPF protocols and comparing related predictive potential regarding in vivo SPF. In the first part, two spreading methods were compared on two types of PMMA (Polymethyl methacrylate plate with different roughness. The impact of a second spreading step after product drying was also evaluated. From the various investigated parameters, it was shown that (i) a higher roughness (Ra = 4, 5 microm) was preferred for O/W formulations (ii) using a defined sequence of light linear and circular strokes was more adequate than monitoring product spreading in terms of time and pressure (iii) both correlation to in vivo SPF and results variability were improved when a second spreading step was added. The altered protocol showed a good predictive potential regarding in vivo SPF values for O/W formulations (correlation coefficient 0.92, correlation curve slope 0.98) and coefficient of variation of in vitro results (14% of the mean SPF value) close to what is usually obtained in vivo. The repeatability of the protocol was also demonstrated. In the second part, we evaluated the impact of PMMA plate pre-treatment with paraffinum liquidum before spreading the product to get a better correlation between in vivo and in vitro SPF values for W/O formulations. This allowed us to define a protocol suitable for both O/W and W/O formulations.