Influence of skin extension upon the epidermal morphometry, an in vivo study.

Background: The Dermal-Epidermal Junction (DEJ) is characterized by undulations whose apices are called papillae. With aging, epidermis becomes thinner, together with a flattening of the DEJ, leading to a decreased density of papillae. The causes of these modifications are likely as multiple as uncertain.

Influence of Stratum Corneum on the entire skin mechanical properties, as predicted by a computational skin model.

Background/purpose: Skin mechanical properties are globally well described. The aim of this paper is to evaluate, by means of a numerical model, the influence of Stratum Corneum (SC) on skin folding resulting from an in-plane compression.

Methods: A computational skin model was developed where skin is divided into three layers (SC, epidermis and upper dermis, and deep dermis) of different thicknesses and elastic moduli.

Longitudinal study of skin aging: from microrelief to wrinkles.

Aim: To study the changes in skin microrelief and periocular wrinkles during the aging process.

Methods: Replicas of the crow's feet area of volunteers were recorded in 1987 and 2008 and observed comparatively. Characteristic features were quantified by image analysis.

Photoaging of the chest analyzed by capacitance imaging.

Objective: Capacitance imaging is a new technique using sensors based on silicon technology developed to record fingerprints for security reasons. Applying such a sensor onto the skin surface gives the capacitance (hydration) map of the skin surface with a two-dimensional resolution of 50 microm. This method was used to characterize skin of the chests of 64 women with various grades of skin photoaging.

A new technique to in vivo study the corneocyte features at the surface of the skin.

Purpose Of The Study: To design, develop and validate a new device allowing the features of corneocytes at the surface of the skin to be visualized in vivo and objectively characterized.

Materials And Methods: Monochromatic light is focused at the proximal end of a coherent bundle of optical fibres. Fluorescence of skin, stained with fluorescein, is then captured by the same fibre bundle and displayed, through a dichroic mirror, by a CCD camera.

Influence of age and hormone replacement therapy on the functional properties of the lips.

Aims: To investigate the influence of age and hormonal status on some functional properties of the lips of women.

Methods: Lips properties were measured and compared through four groups of women (young with normal menses, aged with normal menses, aged and menopaused, aged, menopaused receiving hormonal replacement therapy). The following parameters were recorded: sebum excretion rate on the forehead.

Remote in vivo imaging of human skin corneocytes by means of an optical fiber bundle.

Human corneocytes forming the outermost layer of the epidermis (stratum corneum) were imaged in vivo by epifluorescence through a coherent optical fiber bundle. A very simple and rapid method to remotely visualize the cells forming this protective layer of the skin is presented. After the topical application of fluorescein, the distal face of an optical fiber bundle is gently applied perpendicularly onto the labeled skin (contact mode).

The use of hydroxy acids on the skin: characteristics of C8-lipohydroxy acid.

The hydroxy acids are widely used in skin creams because of their exfoliating and rejuvenating effect on photoaged skin. As a member of this family, the salicylic acid derivative known in the literature as 2-hydroxy-5-octanoyl benzoic acid or beta-lipohydroxy acid has also been proposed as an exfoliant and as a treatment of photoaged skin and acne. This article reviews the effects of the hydroxy acids and compares them to those of the salicylic acid derivative.

Skin capacitance imaging, a new technique for investigating the skin surface.

Thanks to the recently introduced silicone image sensor technology, skin capacitance imaging has now been made possible. The dedicated device is called SkinChip. This method is easy to handle and provides information about the skin microrelief, the level of stratum corneum hydration and the sweat gland activity.

Early use of PbS nanotechnology for an ancient hair dyeing formula.

Lead-based chemistry was initiated in ancient Egypt for cosmetic preparation more than 4000 years ago. Here, we study a hair-dyeing recipe using lead salts described in text since Greco-Roman times. We report direct evidence about the shape and distribution of PbS nanocrystals that form within the hair during blackening.

Capacitance imaging of the skin surface.

Background/aims: A new device allowing recording capacitance images of the skin surface was recently presented. Parameters, extracted from the gray-level histogram of the images, are tested for a new approach of skin surface hydration measurement in comparison with the classical capacitance method. Illustration of the interest of having both images and parameters for studying the homogeneity and the level of skin surface hydration are presented.

Silicon image sensor technology for in vivo detection of surfactant-induced corneocyte swelling and drying.

Background: Several instrumental methods can indirectly assess some specific aspects of cutaneous irritation at the level of the stratum corneum (SC).

Objective: There is a need for developing more sensitive approaches in this field.

Methods: We assessed a recently introduced innovative tool (SkinChip) based on capacitive pixel-sensing technology in its potential to detect early discrete manifestations of skin irritation.

A computational skin model: fold and wrinkle formation.

This paper presents a computational model for studying the mechanical properties of skin with aging. In particular, attention is given to the folding capacity of skin, which may be manifested as wrinkles. The simulation provides visual results demonstrating the form and density of folds under the various conditions.

SkinChip, a new tool for investigating the skin surface in vivo.

Background/aims: Non-invasive methods used for characterizing skin micro-relief and skin surface hydration were developed in the 1980s. Although they allowed some progress in the knowledge of skin properties, they are not completely satisfactory in many aspects. Today, new technologies are emerging that may address such issues.

The "Haptic Finger"- a new device for monitoring skin condition.

Background/aims: Touching the skin is of great importance for the Clinician for assessing roughness, softness, firmness, etc. This type of clinical assessment is very subjective and therefore non-reproducible from one Clinician to another one or even from time to time for the same Clinician. In order to objectively monitor skin texture, we developed a new sensor, placed directly on the Clinician's finger, which generate some electric signal when slid over the skin surface.

EEMCO guidance for the measurement of skin microcirculation.

The blood supply to the skin is provided by a network of arterioles, capillaries and venules organized into a superficial and a deep plexus. The assessment of skin microcirculation is of valuable interest in cosmetology in the quantification of the sun protection factor, skin irritation and efficacy of antiredness treatments. Skin microcirculation can be measured by means of different techniques, based mainly on the quantification of optical and thermal properties of the skin which are modified by the amount of blood perfusion.

Structure and function of human stratum corneum under deformation.

Background: The stratum corneum (SC) has an important barrier function. The effect of a mechanical stress applied to the SC is controversial on this important physiological parameter.

Objectives And Methods: To assess both in vitro and in vivo the structure and function of human SC submitted to controlled strains, we measured the transepidermal water loss (TEWL), in vivo, on human skin submitted to controlled strains ranging from 0 to 20% extension imposed by a Densi-score device.

Influence of age on the wrinkling capacities of skin.

Background: Comparisons of clinical assessment with measurement of physical parameters are rare.

Objective: To standardize the horizontal wrinkling of the skin in order to define a reference chart of the different wrinkling grades and to propose an interpretation of the clinical pattern in terms of skin layers thickness and mechanical parameters.

Methods: A device allowing reproducible wrinkling of the skin was made.