Use of Cutometer area parameters in evaluating age-related changes in the skin elasticity of the cheek.

BACKGROUND/AIM: The decrease of skin elasticity on the cheek is a major concern to woman. The Cutometer has been widely used to evaluate skin elasticity and its change with aging. Cutometer parameters derived from one suction have been traditionally used to evaluate skin elasticity, and few reports describe the use of multiple suctions to obtain parameters to assess the skin elasticity of the cheek. To find the most suitable Cutometer parameter that reflects age-related changes in the elasticity of cheek skin using multiple suctions. METHODS: The cheeks of 32 healthy Japanese women (mean age, 42.3 years) were assessed using the Cutometer MPA580 by measuring the skin mechanical parameters R0-R9, F2 and F3. Parameters F2 and F3 were obtained by the multiple suction method. The relationship between age and these parameters were then examined. RESULTS: Significant negative correlations were found between the age of subjects and R2, R3, R7, R8 and F3. Of these, the correlation coefficient was best between age and F3 (r = -0.641), followed R8 (r = -0.603). CONCLUSION: Although R parameters have been used to evaluate skin elasticity, our study showed that F3 parameters derived from multiple suctions appear to be suitable for evaluating the elasticity of cheek skin, since this parameter is less influenced by environmental factors compared with R parameters.

Melanin and facial skin fluorescence as markers of yellowish discoloration with aging.

BACKGROUND: Although one clinical sign of aging and/or photoaging is a yellowish discoloration of the facial skin, little is known about the cause of this change. In addition to the increase in the epidermal melanin content, it has been suggested that advanced glycation end products (AGEs), which are known to accumulate in photoaged skin, may affect this discoloration. AIM: The objective of this pilot study was to non-invasively investigate the roles of melanin and AGEs in this yellowish discoloration of the facial skin. METHODS: We examined the spectral reflectance at the cheek in 40 healthy Japanese women of various ages (mean age, 38.1 years) using a reflectance spectrophotometer and a spectrofluorimeter. The degree of yellowish tint was evaluated in terms of b(*). The amount of melanin in the skin was evaluated by calculating the melanin index (MI) A(640)-A(670) [A(lambda): log(10) (1/reflectance) at a wavelength of lambda]. The amount of AGEs was roughly evaluated using the AGEs index, which is thought to linearly correlate with the amount of intrinsic fluorescence markers irrespective of the concentration of melanin and is defined as follows: AGEs index=I(5)/SQR (I(1)xI(2)). In this equation, the intensities of reflectance are I(1) at an excitation wavelength of 335 nm, I(2) at an emission wavelength of 390 nm and I(5) at 390 nm under an excitation wavelength of 335 nm. RESULTS: Both b(*) and the AGEs index were significantly correlated with subject age (r=0.34, P<0.05 and r=0.68, P<0.0001, respectively). Significant correlations were also observed between MI and b(*) (r=0.63, P<0.0001) and between the AGEs index and b(*) (r=0.53, P<0.0005). However, no significant correlations were seen between MI and the AGEs index. CONCLUSION: The AGEs index does not appear to be influenced by the amount of melanin and may be utilized as an indicator of the amount of AGEs in the skin. AGEs are likely to play a role in the yellowish discoloration of skin with aging.

Effects of vitamin C on dark circles of the lower eyelids: quantitative evaluation using image analysis and echogram.

BACKGROUND/AIMS: The pathogenesis of dark circles of the lower eyelid (DCLE) has been considered to involve stasis and hyperpigmentation of the eyelids. We have already reported that dermal thickness of lower eyelid skin may represent another factor that affects the appearance of DCLE. The aim of this study was to evaluate the efficacy of vitamin C, which is known to increase collagen, on DCLE through a clinical trial. METHODS: Fourteen subjects with DCLE applied either 10% sodium ascorbate (ANa) or ascorbic acid glucoside (AG) lotion in split-face fashion (opposite side: vehicle only) for 6 months. Melanin index (MI), erythema index (EI), thickness and echogenicity of the dermis at bilateral lower eyelids was measured during this trial. RESULTS: Change in EI was significantly smaller on the ANa-treated side than on the vehicle-treated side. Dermal thickness tended to be thicker for the ANa-treated side than for the vehicle-treated side, although no significant difference was seen. Both EI and dermal thickness tended to change in parallel manner. On the other hand, no significant differences in changes of EI, MI, and dermal thickness were found between AG- and vehicle-treated sides. CONCLUSION: ANa may improve DCLE by thickening the eyelid dermis and concealing dark coloration due to congested blood.

Objective evaluation of the efficacy of daily topical applications of cosmetics bases using the hairless mouse model of atopic dermatitis.

BACKGROUND/AIMS: Dry skin (xerosis) is a characteristic change associated with atopic dermatitis (AD) and has often been treated with topical petrolatum applications despite its unfavorable feel. Recently, various therapeutically effective skin-care products with better feel have been introduced. To elucidate the mechanisms underlying the clinical effectiveness of these newer treatments, we used our recently established hairless mouse model of AD. METHODS: We produced AD-like skin lesions in hairless mice with repeated applications of 2,4,6-trinitro-1-chrolobenzene (TNCB) in acetone for 36 days as reported previously. Groups of five mice with AD-like skin were treated once daily with an emollient-type cream containing petrolatum, a moisturizer-type cream containing 10% glycerin, a solution of 0.01% dexamethasone in acetone, or were left untreated. Over the duration of these treatments, we conducted non-invasive measurements of skin surface condition with biophysical instruments and electron microscopic evaluation of the surface area size and density of rear surface villi of superficial corneocytes. We also obtained skin biopsy samples and blood samples at each time point for histopathological evaluation and to assess serum IgE levels, respectively. RESULTS: After cessation of topical TNCB applications, AD-like skin underwent spontaneous resolution with normalization of skin appearance. A similar reduction in skin fold thickness was observed in the cream-treated mice and in the untreated mouse group, whereas a significant decrease in skin thickness was observed in the dexamethasone-treated mice. Transepidermal water loss, a measure of stratum corneum barrier function, rapidly normalized in all groups, without any statistical differences noted among groups. In comparison with untreated skin, skin surface hydration markedly improved after repeated applications of the moisturizer-type cream, whereas it consistently remained low in dexamethasone-treated skin. The skin treated with emollient-type cream appeared similar to skin that received no treatment. Reduced corneocyte surface area size resulting from repeated applications of TNCB returned to control size with cream treatments, while the corneocyte surface area size became much larger following dexamethasone treatment. In addition, the density of villi on the rear surface of corneocytes decreased with application of the creams or dexamethasone. By contrast, no changes were observed in the number of leukocytes in the epidermis or in serum IgE levels among the different treatment groups. In all treatment groups, even after 32 days of treatment, reapplication of TNCB resulted in early-stage skin swelling, but only in the steroid-treated animals did this swelling show a remarkably prolonged time course. CONCLUSIONS: Our present results indicate that the efficacy of skin-care products containing no active ingredients in treating atopic xerosis can be objectively evaluated using the hairless mouse model of AD.

Establishment of an atopic dermatitis-like skin model in a hairless mouse by repeated elicitation of contact hypersensitivity that enables to conduct functional analyses of the stratum corneum with various non-invasive biophysical instruments.

BACKGROUND/AIMS: Pathogenesis of atopic dermatitis (AD) has been studied in animal models such as the NC/Nga mouse strain or Balb/C mice that are repeatedly treated with 2,4,6-trinitro-1-chrolobenzene (TNCB). These mice exhibit features of chronic contact dermatitis, including an intensified early type skin reaction, increased number of mast cells and elevated serum IgE levels with a shift of cutaneous cytokine expression from a type 1 to type 2 profile. However, it is difficult to investigate the unique skin changes of AD such as dry skin, barrier dysfunction, and increased turnover of the stratum corneum (SC) in these animals with biophysical instruments because of the presence of their fur coats. In this study, we succeeded in establishing a mouse model of AD in hairless mice that are suitable for various functional analyses of the SC as well as for examining the immunological characteristics of human AD by treating TNCB-contact sensitized hairless mice with 1% TNCB every other day for 36 days. METHODS: In hairless animals treated with TNCB every 2 days for 36 days, we measured time courses of skin swelling induced by contact hypersensitivity reaction on days 0, 6, 20 and 36. During the time course, non-invasive measurements for skin surface condition with biophysical instruments were conducted, and the area size and the rear surface villi of corneocytes obtained were measured. Also skin samples and blood samples were taken at each time point for histology and measurement of serum IgE level. RESULTS: A gradual intensification of an early type contact hypersensitivity reaction was observed over the treatment period. These mice exhibited reduced SC hydration, heightened trans-epidermal water loss, and increased skin thickness. These mice also showed a decrease in the surface area size of each corneocytes and marked villus formation on their rear surface. Histologically, there was an increase in the number of CD4 and CD8 positive T cells in the epidermis. Also observed was a marked increase in the number of dermal mast cells and eosinophils, which correlated with elevated serum IgE levels induced by TNCB treatments. CONCLUSIONS: From the results obtained we conclude that repeated treatments of TNCB-sensitized hairless mice with TNCB provides a useful means by which to study the pathological characteristics of AD skin lesions as well as their immunological characteristics.