Klaus-Peter Wilhelm

Elastic properties of human skin: relation to age, sex, and anatomical region

SummaryUsing a recently developed noninvasive, in vivo suction device for measuring skin elasticity, we evaluated age, sex, and regional differences in the viscoelastic properties of skin. A total of 33 volunteers participated in the study consisting of (a) 8 young females, (b) 9 old females, (c) 8 young males and (d) 8 old males. Measurements were performed on 11 anatomical regions; three different loads were applied: 100,200, and 500 mbar. The parameters used were: immediate distension (Ue); delayed distension (Uv); immediate retraction (Ur); and, final deformation (Uf). To compare between subjects and anatomical regions, relative parameters independent of skin thickness were calculated: Uv/Ue, the ratio between the viscoelastic properties of skin and immediate distension, and Ur/Uf, which measures the ability of the skin to regain its initial position after deformation. Generally, Uv/Ue increased while Ur/Uf decreased with aging. Responses were variable with respect to load applied. Variability within anatomical regions was also noted. However, differences between the sexes were not statistically significant for most regions. These findings are in congruence with earlier studies suggesting the differences are mainly attributable to alterations in the elastic fiber network. This procedure provides a simple, quantitative assessment of elastic properties of the skin. Its application may help in future investigations of other connective tissue disorders.

Cumulative irritation in older and younger skin : a comparison

Changes in stratum corneum properties due to sodium lauryl sulfate cumulative irritation were determined as a function of age. We irritated the backs of 7 younger (27.7 +/- 4.6 years, mean +/- standard deviation) and 10 older (69.8 +/- 5.5 years) volunteers on 5 consecutive days with open application of a 7.5% aqueous sodium lauryl sulfate solution. Water- and untreated skin served as controls. Transepidermal water loss, stratum corneum capacitance, Desquamation Index, and skin roughness parameters were evaluated on 5 days of the 1st week, and on 3 days of the 2nd week. All parameters revealed a delayed and decreased reaction of older compared to younger skin and recovery appeared to be prolonged. We conclude that under these test conditions irritancy to repetitive sodium lauryl sulfate exposure of older versus younger skin resembled that previously observed after single occlusive exposure. In neither age group was the recovery effect reduced by repeated irritation, demonstrating sufficient skin barrier and recovery function.

In Vivo Study on Age-Related Elastic Properties of Human Skin

The skin performs numerous functions vital to the maintenance of homeostasis. Faced with a variety of extrinsic factors, such as physical trauma from the sun, wind, temperature changes, microorganisms, and the dynamic movements of the body, as well as the intrinsic aging processes, its integrity is well preserved by a complex interaction of the three layers: epidermis, dermis, and subcutaneous tissue.