Impact of water exposure on skin barrier permeability and ultrastructure.

BACKGROUND: Skin occlusion caused by the use of diapers or sanitary napkins often results in irritant contact dermatitis. Furthermore, prolonged occlusion and exposure to body fluids are known to increase skin hydration and permeability, thus leading to irritant contact dermatitis. OBJECTIVE: To investigate the effects of water exposure on the skin and its barrier functions, in order to obtain more insights into the mechanisms of irritant contact dermatitis. METHODS: Water patches were applied to the volar forearm skin of 10 human subjects for 3 hours. Permeability of the stratum corneum (SC) was examined with methyl nicotinate (MN). Alterations in the hydration and ultrastructure of the SC were measured with Raman spectroscopy and multiphoton microscopy, respectively. RESULTS: Water profiles found with Raman spectroscopy showed notable increases in water content throughout the SC and skin surface. Multiphoton microscopy showed morphological changes in the intercellular space of the SC. Emerged pools seemed to contribute to increased MN absorption. CONCLUSION: Excessive skin hydration leading to changes in the SC ultrastructure might result in increased skin permeability to skin irritants and allergens.

Ethnic differences in stratum corneum functions between Chinese and Thai infants residing in Bangkok, Thailand.

BACKGROUND/OBJECTIVES: Ethnic and racial differences in infant skin have not been well characterized. The purpose of this study was to establish whether there are ethnic differences and similarities in the stratum corneum (SC) functions of Thai and Chinese infants. METHODS: Healthy infants 6 to 24 months of age (N = 60; 30 Thai, 30 Chinese) who resided in Bangkok, Thailand, were enrolled. Transepidermal water loss (TEWL) and SC hydration (capacitance) on the thigh, buttock, and upper arm were measured. Ceramide content was determined in the SC on the upper arm. RESULTS: SC hydration was not remarkably different between the two ethnicities at any site measured, but TEWL was significantly higher in Chinese infants than in Thai infants at all sites. Hydration of the SC was not significantly correlated with age in either ethnicity. TEWL had significant but weak correlations with age on the thigh and upper arm in Thai infants. Ceramide content was significantly higher in Chinese SC than in Thai SC. No relationship between ceramide content and TEWL or hydration was observed in either ethnicity. CONCLUSION: The significant differences in TEWL and ceramide contents between Chinese and Thai infant skin could prove useful in designing skin care and diapering products that are best suited for each ethnicity.

Characterization of vulvar skin of healthy Thai women: influence of sites, age and menopause.

Although the physiological characteristics of vulvar skin have been characterized in Caucasians, little is known about the vulvar skin of Asian women. This study assessed the moisture content, transepidermal water loss (TEWL) and pH of vulvar skin of 99 healthy Asian women residing in Bangkok, aged 20-69 years, during their non-menstrual period, including 39 post-menopausal women. Skin pH was acidic at all sites, and the pH of the vulvar areas was significantly higher than the control sites (inner thigh, inner forearm). Skin moisture was slightly, but significantly, lower around the vulvar area and the thigh than around the forearm. TEWL was significantly higher in vulvar areas than control sites. Ageing and menopause did not cause notable alterations in most properties of vulvar skin. In conclusion, the vulvar skin of Asian women has similar properties to that of Caucasians.

A novel method to investigate the relationship between facial movements and wrinkle formation using particle image velocimetry.

BACKGROUND: The possible relationship between the direction of wrinkles and the movement of facial skin has not previously been reported. Therefore, we characterized that relationship using particle image velocimetry (PIV) analysis. METHOD: Twenty-one healthy Japanese women aged in their 20s (n = 7) or 50s (n = 14) were recruited for this study. Moving images of facial skin motions (closing the eyes tightly, raising the eyebrows) were captured using a single infrared camera under infrared ray irradiation of the skin. PIV analysis was then carried out using Flow-Vec32 software to determine the velocity and the direction of skin surface movements. RESULTS: All skin movements caused by those motions were finished within 0.20 s. During the motion of closing the eyes, skin at the eye periphery did not move in a superior-inferior direction, but did move toward the center of the eye (pupilla) with complex flows. There was no significant difference between either age group of subjects. During the motion of raising the eyebrows, the forehead skin moved upwards (direction to parietal) with relatively uniform flows. The velocity of movement at the top was lower than at the bottom, and that difference is likely to cause a deformation on the skin surface. A significant difference between the two age groups in the velocity was observed. CONCLUSION: The results show that the deformation of older skin on the forehead is greater than that in younger skin. The PIV analysis method is a useful tool to investigate some aspects of the relationship between facial skin movements and wrinkle formation.

Gender-dependent differences in degree of facial wrinkles.

BACKGROUND/PURPOSE: This study aimed to reveal gender-dependent differences in the degree of facial wrinkles. METHODS: Subjects comprised 173 Japanese men and women, divided into four groups according to age. Photographs were taken from nine facial regions and used to classify the intensity of wrinkles into five grades. In addition, replicas were taken from five facial sites and used to measure surface roughness. Data were compared between men and women within each age group. RESULTS: In all age groups, men showed increased forehead wrinkles compared with women. In contrast, no gender-dependent differences were found in upper eyelid wrinkles. Other facial wrinkles were greater in men than in women in all except the oldest group (age, 65-75 years), in which wrinkles in women were greater than or equal to those in men. CONCLUSION: Our results showed that gender-dependent differences exist in the degree of facial wrinkles. In general, men tend to have more severe wrinkles than women. This tendency disappeared or was reversed in some regions of the face and in individuals more than 60 years old.

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

BACKGROUND: 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. METHODS: Wrinkles were graded on the faces of Japanese female subjects when they made strong voluntary facial movements (eyes closed tightly, raised eyebrows, and frowns) and also when they were at rest using a set of photos (a photo scale) obtained from subjects with different degrees of wrinkles in the static and dynamic states. Scores obtained were compared between the dynamic and static states, and were analyzed in relation to age and to facial region. RESULTS: We found that the levels of wrinkles in both states showed a significant positive correlation with age. Further, the distribution of wrinkles in the dynamic state was found to be similar to those in the static states. Finally, the correlations between static and dynamic wrinkles in the same facial sites were higher than those in different facial sites. CONCLUSION: Facial movements cause wrinkling in both the dynamic and the static states and also that static wrinkles may work at the kinetic origins of dynamic wrinkles.

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. METHODS: Using a pressure device with a 12 MHz ultrasound transducer, constant and linear compressions were applied to the cheek skin of 35 volunteers (aged: 20-60 years). The elasticity of each layer (dermis, subcutaneous and muscle) was measured and analyzed using the TSI application software incorporated into the Toshiba Aplio(™) XV ultrasound system. A skin tissue-equivalent phantom, which is a block of material with the acoustic velocity (1530 m/s) of human skin, was collaboratively developed by OST Inc. This phantom was placed between the skin and the transducer as a reference material. RESULTS: Skin elasticity was clearly visualized and quantified in each layer of the skin. Age-dependent decreases in elasticity were determined in all layers of the skin. Among the three internal skin layers, the highest elasticity was determined in the subcutaneous layer followed by the muscle layer. CONCLUSION: These findings support the validity and sensitivity of the TSI method to assess the elasticity of various layers of skin.

Relationship between the echogenicity of subcutaneous tissue and the depth of eye corner wrinkles.

BACKGROUND/PURPOSE: A close relationship was found between the internal structure of subcutaneous tissue and wrinkle depth in our previous study of human forehead. The present study examined the relationship in the eye corner. METHODS: One hundred and seventy-three Japanese subjects were divided into four age groups (21-28 years, 35-41 years, 47-59 years and 65-75 years). The maximum wrinkle depth (Rmax) of an eye corner wrinkle was obtained. On an ultrasound image, which was captured by scanning perpendicular to the wrinkle, we set a 12.5-mm-wide region of interest (ROI) by aligning the deepest point of the wrinkle at its center and then obtained the ratio of the area exceeding an echogenicity threshold to the total area as the echogenicity. RESULTS: No correlation was found between the Rmax and echogenicity. The relationship was further analyzed by dividing the ROI into two: one above and the other below the deepest point of the wrinkle. A negative correlation was detected in the lower ROI of the oldest group. The difference in echogenicity between the upper and the lower ROIs of the oldest group showed a positive correlation with the Rmax. CONCLUSION: These results suggest that the subcutaneous tissue structure is related to wrinkle depth.

Relationship between the echogenicity of subcutaneous tissue and the depth of forehead wrinkles.

BACKGROUND/PURPOSE: Subcutaneous tissue is rarely studied in research on wrinkles. We used diagnostic ultrasonography to produce images of subcutaneous tissue of the forehead, one of the areas where age-related wrinkles form. We quantified the resulting echogenicity and investigated its relationship with wrinkle depth. METHODS: One hundred and seventy-three Japanese subjects were divided into four age groups (21-28 years, 35-41 years, 47-59 years, 65-75 years). Maximum wrinkle depth (Rmax) was measured in the forehead. On an ultrasound image, which was captured by scanning perpendicular to the deepest wrinkle, we set a 12.5-mm-wide region of interest by aligning the deepest point of the wrinkle at its center and then obtained the ratio of the area exceeding this threshold to the total area as the echogenicity. RESULTS: R max increased and the echogenicity decreased with age. A negative correlation was found in the oldest group but was not found in other groups, presumably due to individual differences in the echogenicity among younger subjects. CONCLUSION: This study suggests that the internal structure of subcutaneous tissue, as observed by ultrasonography, is related to wrinkle depth. The relationship between wrinkle depth and echogenicity of subcutaneous tissue is particularly pronounced in the elderly.

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. METHODS: Open- and closed-eyed photographs were obtained from 87 Japanese women of ages ranging from 21 to 73 years, and also from 80 American women comprising of Asians, Caucasians, Africans and Hispanics in their 30s. Their wrinkle intensities were scored separately at nine facial sites using a five-point photo scale. The obtained scores were compared between open- and closed-eyed photographs. The differences were then compared across age- and ethnic-groups. RESULTS: In Japanese subjects, a significant difference was found at the forehead wrinkle in all age groups, and also at the glabella, nasal root and eye corner in the middle and old age groups. In American subjects, significant differences were found at the forehead, nasal root, eye-corner, and upper and lower eyelids. The differences were more prominent in the Hispanic and Caucasian Americans than in the Asian and African Americans. CONCLUSION: These results suggest that the eyelid position should be considered as a variable in wrinkle assessment.