A multicentre study for measuring skin hydration with 349 volunteers was carried out in six different laboratories. The purpose of the study was to investigate physical-, physiological- and product-dependent parameters of three test emulsions (base, base + moisturizer and base + moisturizer + lipids) in a double-blind study. A comparison between analogous and digital sensor technology of the Corneometer CM825 was examined. Here, a clear relationship between both sensor types could be highlighted. A vital point of the study was the division of the test subjects according to their skin type. To get more objective limits for three different skin types - very dry, dry and normal skin - visual expert evaluation, self-assessment and hydration measurements were analysed by means of statistical methods. The moisture-related skin types were determined as follows: very dry skin was characterized with corneometer units below 30, dry skin between 30 and 40 and normal skin higher than 40 a.u. (arbitrary units). The efficacy of the three test emulsions was examined in relation to the mentioned skin types. Analysing the measured data of all test centres, a clear dependency of skin physiology (skin type) and product efficacy became evident. The drier the skin, the higher the increase of hydration. The product performance of the three test emulsions compared to the untreated control resulted in a significant increase of skin hydration in all measuring centres. The evaluation of a product ranking showed a good differentiation between the basic emulsion and the two other products. An increase of efficacy by adding lipids could be observed in four of six centres. The important influence of the skin type of the volunteers on the degree of product performance, as demonstrated in this study, should be especially considered when drawing up guidelines for efficacy testing.
Background/aims: The confocal laser scanning microscope Vivascope (Lucid, Henrietta) allows skin to be studied in real‐time with a resolution of 0.5 µm horizontal and 1.3 µm vertical in vivo. In this study, we present the results of a comparison between the skin of an older and a younger group of volunteers by in vivo histometric measurements. Methods: To investigate changes caused by age, 13 young (18–25 years) and 13 older (> 65 years) volunteers were examined. The following parameters were measured using the Vivascope at the volar forearm: minimal thickness of the epidermis (Emin), size of cells in the granular layer (Agran), thickness of the horny layer (DSC), thickness of the basal layer (DSB) and number of dermal papillae per area (PapI). The image analysis program image tool was used to measure the size of the cells and the thickness of the basal layer. Results: The older group of volunteers showed a significant increase in Emin, no significant change in DSC, a significant decrease in dermal papillae and in the thickness of the basal layer, and an increase in Agran compared to the younger group. Conclusions: Histometric measurements by in vivo confocal laser scanning microscopy are a sensitive and non‐invasive tool for characterizing and quantifying histological changes of the epidermis and papillary dermis due to ageing.
Background/aims: Topometry is one of the most relevant methods for biophysical research on skin in dermatologic and cosmetic science, because it relates very closely to the perceived quality of skin. Taking silicon replicas of skin sites under investigation and measuring those imprints with mechanical or optical profilometers is still the most frequently used method. Direct measurement of the topography of human skin in vivo by active image triangulation avoids the need to make replicas and seems to be a promising alternative. Methods: The introduction of active image triangulation in conjunction with phase‐shift techniques in skin topometry enables a fast and non‐invasive measurement of the skin surface in vivo. The main attribute of the proposed system is the projection of a regular sinusoidal intensity pattern with a sophisticated digital projection device onto the surface of skin under a certain angle of incidence. The height information of the structured surface is coded in the distorted intensity pattern, which is recorded by an appropriate video technique. Results: Successful in vivo measurements of selected body sites and measurements on scar, nevus, wound and wrinkles are presented in this paper. Furthermore, irritation of skin, influence of hydration of skin, and differences between youthful and elderly skin can be detected in the measurement results of the new optical system. Conclusions: For measuring the topog raphy of human skin, active image triangulation is appropriate both for macrotopometry (nevus, scar, wound) and for microtopometry (casts, selected body sites). This new non‐contact technique allows dynamic measurements of alterations in skin topography as a consequence of certain treatments (e.g., application of ingredient, hydration of skin) without removal of corneocytes or scales. Optical three‐dimensional (3D) topometry using active image triangulation appears to offer a significant improvement in speed and flexibility, providing a fast and accurate analysis of skin surface topography.
Background: The influence of ageing on the density of the functional entities of the papillae containing nutritive capillaries, here in terms as the papillary index, and the effect of topically applied vitamin C were investigated by confocal laser scanning microscopy (CLSM) in vivo.
Biochemical and structural changes of the dermal connective tissue substantially contribute to the phenotype of aging skin. To study connective tissue metabolism with respect to ultraviolet (UV) exposure, we performed an in vitro (human dermal fibroblasts) and an in vivo complementary DNA array study in combination with protein analysis in young and old volunteers. Several genes of the collagen metabolism such as Collagen I, III and VI as well as heat shock protein 47 and matrix metalloproteinase-1 are expressed differentially, indicating UV-mediated effects on collagen expression, processing and degradation. In particular, Collagen I is time and age dependently reduced after a single UV exposure in human skin in vivo. Moreover, older subjects display a lower baseline level and a shorter UV-mediated increase in hyaluronan (HA) levels. To counteract these age-dependent changes, cultured fibroblasts were treated with a specific soy extract. This treatment resulted in increased collagen and HA synthesis. In a placebo-controlled in vivo study, topical application of an isoflavone-containing emulsion significantly enhanced the number of dermal papillae per area after 2 weeks. Because the flattening of the dermal-epidermal junction is the most reproducible structural change in aged skin, this soy extract appears to rejuvenate the structure of mature skin.
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