Background and Objectives: Evidence suggests the importance of skin biophysical properties in predicting diseases and in developing appropriate skin care. The results to date of studies on skin surface pH, stratum corneum (SC) hydration and sebum content in both genders and at various ages have been inconclusive, which was in part due to small sample size. Additionally, little is known about the skin physical properties of Asian, especially Chinese, subjects. In the present study, we assess the difference in skin surface pH, sebum content and SC hydration at various ages and in both genders in a large Chinese population without skin diseases. Methods: 713 subjects (328 males and 385 females) aged 0.5–94 years were enrolled in this study. The subjects were divided by age into 5 groups, i.e., 0–12, 13–35, 36–50, 51–70 and over 70 years old. A multifunctional skin physiology monitor was used to measure SC hydration, skin surface pH and sebum content on both the forehead and the forearms. Results: In males, the highest sebum content was found on the forearm and the forehead in the age groups 36–50 (93.47 ± 10.01 μg/cm²) and 51–70 years (9.16 ± 1.95 μg/cm²), while in females, the highest sebum content was found on the forearm and the forehead in the age groups 13–35 (61.91 ± 6.12 μg/cm²) and 51–70 years (7.54 ± 2.55 μg/cm²). The forehead sebum content was higher in males aged 13–70 years than in age-matched females; the sebum content on the forehead in both males and females was higher than that on the forearm. Skin surface pH on the forehead of both males and females over the age of 70 years was higher than that in younger groups. SC hydration on the forehead in both males and females was lower above the age of 70, and the one in males aged 13–35 was higher than that in females (43.99 ± 1.88 vs. 36.38 ± 1.67 AU, p < 0.01). SC hydration on the forehead in both males and females did not significantly differ from that on the forearm. Conclusions: In a large Chinese cohort, the skin surface pH, sebum content and SC hydration vary with age, gender and body site.

Aged skin commonly is afflicted by inflammatory skin diseases or xerosis/eczema that could be triggered or exacerbated by impaired epidermal permeability barrier homeostasis. This defect is linked to reduced epidermal lipid synthesis in humans and in mice of advanced age (i.e., >75 years in human or >18-24 months in mice). We now report that barrier defects in moderately aged humans (50-80 years) or analogously aged mice (12-15 months) are linked instead to defective stratum corneum (SC) acidity. In moderately aged mouse epidermis, we find that abnormal acidification, in turn, is linked to decreased Na+/H+ antiporter (NHE1) expression. Decreased NHE1 levels lead to increased SC pH, which results in defective lipid processing and delayed maturation of lamellar membranes, due to suboptimal activation of the pH-sensitive essential, lipid-processing enzyme, beta-glucocerebrosidase. Conversely, impaired SC integrity in moderately aged mice is due to increased pH-dependent activation of serine proteases, leading to premature degradation of corneodesmosomes. These abnormalities were normalized by exogenously acidifying the SC, suggesting a basis for the well-known acidification therapies that are widely used to treat the pathologic xerosis/eczema seen in moderately aged humans.

Background/objectives-One phenomenon of skin aging is loss of cutaneous elasticity. Measurement of cutaneous resonance running time (CRRT) is a method to assess skin elasticity. Yet, information regarding directional changes of CRRT associated with age, body sites and gender is not yet available. In the present study, we assessed whether changes in CRRT vary with age, body sites and gender in a normal Chinese population.

Cigarette smoking is associated with various cutaneous disorders with defective permeability. Yet, whether cigarette smoking influences epidermal permeability barrier function is largely unknown. Here, we measured skin biophysical properties, including permeability barrier homeostasis, stratum corneum (SC) integrity, SC hydration, skin surface pH, and skin melanin/erythema index, in cigarette smokers. A total of 99 male volunteers were enrolled in this study. Smokers were categorized as light-to-moderate (<20 cigarettes/day) or heavy smokers (≥20 cigarettes/day). An MPA5 was used to measure SC hydration and skin melanin/erythema index on the dorsal hand, forehead, and cheek. Basal transepidermal water loss (TEWL) and barrier recovery rates were assessed on the forearm. A Skin-pH-Meter pH900 was used to measure skin surface pH. Our results showed that heavy cigarette smokers exhibited delayed barrier recovery after acute abrogation (1.02% ± 13.06 versus 16.48% ± 6.07), and barrier recovery rates correlated negatively with the number of daily cigarettes consumption (p = 0.0087). Changes in biophysical parameters in cigarette smokers varied with body sites. In conclusion, heavy cigarette smokers display compromised permeability barrier homeostasis, which could contribute, in part, to the increased prevalence of certain cutaneous disorders characterized by defective permeability. Thus, improving epidermal permeability barrier should be considered for heavy cigarette smokers.

BackgroundWe previously showed that the number of publications in dermatology is increasing year by year, and positively correlates with improved economic conditions in mainland China, a still developing Asian country. However, the characteristics of publications in dermatology departments in more developed Asian countries such as Japan and South Korea are unknown.MethodsIn the present study, publications from 2003 through 2012 in dermatology in Japan, South Korea and mainland China were characterized. All data were obtained from http://www.pubmed.com.ResultsDermatology departments in Japan published 4,094 papers, while mainland China and South Korea published 1528 and 1,758 articles, respectively. 48% of articles from dermatology in Japan were original research and 36% were case reports; The number of publications in Japan remained stable over time, but the overall impact factors per paper increased linearly over the last 10 year period (p < 0.05). In mainland China, 67% of articles from dermatology were original research, while 19% were case reports; The number of publications and their impact factors per paper increased markedly. In South Korea, 65% of articles from dermatology were original research and 20% were case reports. The impact factors per paper remained unchanged, despite of the fact that the number of publications increased over the last 10 year period (r2 = 0.6820, p = 0.0032). Only mainland China showed a positive correlation of the number of publications with gross domestic product per capita during this study period.ConclusionsThese results suggest that the total number of publications in dermatology correlates with economic conditions only in developing country, but not in more developed countries in Asia. The extent of economic development could determine both the publication quantity and quality.