Mitsuyuki Hotta

Global and systematic demonstration for the practical usage of a direct in vivo measurement system to evaluate wrinkles

The global and systematic demonstration for the practical usage of a direct three‐dimensional in vivo measurement system (PRIMOS) to evaluate wrinkles was investigated. Ten repetitive measurements of the corner of the eye of a subject showed that the coefficient of variation (CV)% value was 7.0% in a typical line‐length roughness parameter Ra (the arithmetic mean of roughness), and that the CV% value in a typical surface area roughness parameter Sa was 2.4%. The relationships between the roughness values obtained from the corners of the eye and the age or wrinkle scores of Japanese women aged 10–70 years was examined. The values of several roughness parameters within the evaluation line length or surface area increased with age and showed a good correlation coefficient (r > 0.743). Similar relationships between the wrinkle scores and the values of roughness parameters were observed (r > 0.699). The roughness values were widely distributed even in the same wrinkle score because the measurement areas were limited and the values of skin roughness, including the microreliefs and/or small warts, were included in the calculation. However, changes in roughness values are considerable following treatment with potent active ingredients such as retinoic acid, so that this in vivo evaluation method is sufficient to objectively evaluate wrinkles. We conclude that the direct three‐dimensional analysis of wrinkles in vivo should become a popular method to objectively evaluate wrinkles in clinical tests of wrinkle‐smoothing ingredients or following cosmetic surgery to provide evidence of quantitative results.

Effect of room humidity on the formation of fine wrinkles in the facial skin of Japanese.

Background/purpose: Changes in humidity are commonly known to influence the condition of the skin. Previous studies of the skin dealt with variations in relative humidity (RH) either through statistical analysis or by maintaining room humidity at a constant level; however, the range of humidity and the length of acclimation varied in each study. This study aimed to determine whether the generally used ranges of RH are truly acceptable for studies of human skin.

Gender‐dependent differences in degree of facial wrinkles

This study aimed to reveal gender‐dependent differences in the degree of facial wrinkles.

Developmental alterations of physical properties and components of neonatal-infantile stratum corneum of upper thighs and diaper-covered buttocks during the 1st year of life.

BACKGROUND Although physical properties of neonatal-infantile stratum corneum (SC) change drastically after birth, precise developmental alterations of specific sites have not been fully elucidated. OBJECTIVE To determine the longitudinal alterations of neonatal-infantile SC functions and components of upper thighs and diaper-covered buttocks during the first year of life. The data were compared with those of adults. METHODS Nineteen full-term neonates and their mothers were subjected to the measurements. Skin hydration, water sorption/retention capacity, TEWL were measured. Superficial SC analyses for NMF, ester binding sebum, and free fatty acids were performed by ATR-FTIR spectrometer. Total amount of ceramides (CERs) and CER subclasses were analyzed by NPLC-ESI-MS. RESULTS SC hydration of neonatal thighs was lower than that of their mothers, which rapidly increased during the 1st month. Skin hydration of neonatal buttocks was similar to that of their mothers. This also rapidly increased during the 1st month. The neonatal TEWL was less than those of their mothers indicating more efficient barrier function at both sites, which significantly increased during the 1st year development. This was mostly correlated decreased in the ω-hydroxy fatty acid-esterified CERs. Superficial ester-binding sebum content of neonates was similar to that of their mothers, which significantly decreased during the measurement; the decrease was more marked on buttocks. Neither NMF nor FFA of the superficial SC showed significant alteration during the 1-year development. CONCLUSION Our results indicate that physical functions and components of neonatal-infantile SC show considerable alterations between diaper-covered buttocks and upper thighs during the 1st year development.

The preliminary study of the relationship between facial movements and wrinkle formation

As facial wrinkles develop particularly in areas of the skin that are subject to repeated facial movements, the degree of facial movements may be related to the degree of facial wrinkles, although no data have been reported.

A new method for the visualization and quantification of internal skin elasticity by ultrasound imaging.

Background/purpose: Skin elasticity has been assessed previously only in the surface layer. We developed a new method that uses tissue strain imaging (TSI) technology, and the aim of this study was to test this new method to assess internal skin elasticity.

Loss of contraction force in dermal fibroblasts with aging due to decreases in myosin light chain phosphorylation enzymes

Although there have been many reports about the relationship between force generation by skeletal muscles and aging, no study has investigated the relationship between contraction forces generated by non-muscle cells and aging. In this study, we examined that relationship using fibroblast populating collagen gels and a contraction force detecting system. Fibroblasts at passages 5 to 7 were used as the young group and those at passages 17 to 19 were used as the aged group. The contraction force induced by thrombin or lysophosphatidic acid significantly decreased with age. The expression of myosin light chain kinase (MLCK) and two types of Rho kinases (Rock-1 and Rock-2) decreased with age, but the expression of Rho A and myosin phosphatase (MPPase) did not change at all. The expression of myosin light chain 20k (MLC20) depended on the donor fibroblasts. Fibroblasts from young or aged hairless mice showed similar age-dependent results. Taken together, our data suggest that decreased expressions of MLCK and Rho kinase are critical for loss of force generation by fibroblasts with aging, which suggests new mechanisms of functional deficiencies due to aging.

The effect of eye opening and closing on the result of facial wrinkle assessment.

Background/purpose: Since there is no standard protocol that specifies the opening or closing of eyelids in wrinkle assessment, the eyelid position of subjects at the time of assessment varies from study to study. This study aimed to reveal the effect of eye opening and closing on the result of wrinkle assessment. The study also attempted to analyze the age‐, site‐, and ethnicity‐dependent variations in the effect.

The characteristics of aromatase deficient hairless mice indicate important roles of extragonadal estrogen in the skin

The roles of extragonadal estrogen in the skin are poorly understood, due to the lack of proper animal models. We examined the skin phenotypes of aromatase-knockout hairless (ArKO) mice and wild-type hairless (WT) mice, both of which were obtained through crossbreeding of Ar+/- mice and hairless mice. Differences in the skins of ArKO and WT mice were compared with those of ovariectomized (OVX) and control (Sham) mice. A difference was observed in the skin tone of ArKO mice, which is pale white and differs from the pinkish tone of all other mice. However, both ArKO and OVX mice similarly exhibited deteriorations of skin properties as compared to their respective controls. Furthermore, all the deteriorations were similarly amplified by chronic UVB irradiation in both ArKO and OVX mice as compared to their respective controls. The unique skin phenotype of ArKO mice was observed in sunburn reactions. Specifically, skins of ArKO mice showed no reaction after an acute UVB irradiation at dose intensities caused sunburn in others. However, follow-up observation found delayed reactions associated with brownish skin color and swelling only in ArKO mice, thereby suggesting that the role of extragonadal estrogen may be connected with the protective reactions of skin.

Cyclin-dependent kinase inhibitors, p21waf1/cip1 and p27kip1, are expressed site- and hair cycle-dependently in rat hair follicles

In order to investigate the role of cyclin-dependent kinase (CDK) inhibitors in hair growth, we analyzed the expressions of p21(waf1/cip1) and p27(kip1) during the synchronized hair cycle of rat coat. The mRNAs of both p21(waf1/cip1) and p27(kip1) were detected in anagen hair follicles by reverse transcription and polymerase chain reaction and their localization was clearly demonstrated in the upper half portion of the hair bulb and the cortex by in situ hybridization. The dermal tissue containing hair follicles was then excised from the anterior dorsal skin of the 5-12-week-old rats at 0.5 week intervals and the expressions of p21(waf1/cip1) and p27(kip1) were analyzed by northern blot hybridization. The mRNA of both CDK inhibitors was expressed at relatively high levels during anagen than during telogen, a fact which correlated with the mRNA expression levels of hair differentiation markers, type I hair keratin (Ha3) and high sulfur protein B2. These results imply that CDK inhibitors, p21(waf1/cip1) and p27(kip1), are involved in the differentiation of follicular epithelial cells.