Search

Background/purpose Existing skin mechanical testing devices focus on measuring skin elasticity and are not tailored to assess the dynamic behavior of skin. Additionally, the mathematical techniques used in existing devices are often not optimal. Methods A new dynamic mechanical device that measures the linear dynamics of skin was developed and tested. The mechanical properties of skin were evaluated in experiments in which stiffness and damping parameters were measured (i) at different locations on the arm and hand, (ii) when stratum corneum hydration was varied by controlled changes in environmental humidity, and (iii) following the application of film-forming polymers. Parallel measurements were made with the Cutometer® so that the two devices could be compared. Results The findings revealed that reliable and valid measurements of skin mechanical properties can be obtained from the device. The stiffness of the skin was shown to vary significantly as a function of skin site, changes in stratum corneum hydration and following application of the polymer films. Changes in the damping parameter were less consistently associated with varying the condition of the skin. Conclusion The high reliability and speed of measurement make this device and analytic procedure an attractive option for testing skin mechanics.

Background Oxidative stress is an important factor in the pathology of age-related hearing loss. Recent animal studies have reported that ultraviolet radiation in sunlight is related to systemic induction of oxidative stress. Chronic sun exposure leads to photodamaged skin, which is manifested as facial skin wrinkling and hyperpigmentation. We hypothesized that sunlight exposure, as assessed by the severity of facial skin photodamage, might be associated with hearing impairment through an oxidative stress mechanism. To examine this, we performed a cross-sectional analysis by using the baseline data from a community-based cohort study of older Japanese. Methods A total of 805 residents (342 men and 463 women) aged 65 years or older living in Kurabuchi Town, Gunma prefecture, Japan, were examined between 2005 and 2006. Facial skin condition was quantified by image analysis of standardized facial images. Hearing impairment was defined as a failure to hear a 30-dB signal at 1 kHz and a 40-dB signal at 4 kHz in the better ear in pure-tone audiometric tests. Results In men, facial wrinkle was positively associated with hearing impairment (for highest vs lowest: multivariate-adjusted odds ratio, 2.16; 95% confidence interval, 1.00-4.66; p for trend = .01). Stratified analysis by age, educational level, smoking status, sunscreen or foundation use, and diabetes showed results similar to those for men as a whole. This association was particularly pronounced in men with the low levels of antioxidants and without occupational noise exposure. We observed no apparent association in women. Conclusions The results support the hypothesis that chronic sun exposure is a risk factor of hearing impairment.

Background Acne vulgaris is a common skin disease with a large quality of life impact, characterized by comedones, inflammatory lesions, secondary dyspigmentation and scarring. There are few large objective studies comparing acne epidemiology between racial and ethnic groups. Objective This study aimed to define the prevalence and subtypes of acne in women of different racial groups from four ethnicities. Methods The sample consisted of 2895 (384 African American, 520 Asian, 1295 Caucasian, 258 Hispanic and 438 Continental Indian) women ranging in age from 10 to 70 years. Photographs of subjects were graded for acne lesions, scars, dyspigmentation, and measurements taken of sebum excretion and pore size. Results Clinical acne was more prevalent in African American and Hispanic women (37%, 32% respectively) than in Continental Indian, Caucasian and Asian (23%, 24%, 30% respectively) women. All racial groups displayed equal prevalence of both subtypes of acne with the exception of Asians, for whom inflammatory acne was more prevalent than comedonal (20% vs. 10%) acne, and in Caucasians, for whom comedonal acne was more prevalent than inflammatory (14% vs. 10%) acne. Hyperpigmentation was more prevalent in African American and Hispanic (65%, 48% respectively) than in Asian, Continental Indian and Caucasian (18%, 10%, 25% respectively) women. Dyspigmentation and atrophic scarring were more common in African American and Hispanic women than in all other ethnicities. There was a negative correlation between pore size and skin lightness for all ethnicities. Sebum production was positively correlated with acne severity in African American, Asian and Hispanic women, and pore size was positively correlated with acne in African American, Asian and Continental Indian women, (for all above results, P

Summary Background While cumulative lifetime sun exposure is well recognized as having an important role in the progression of facial wrinkling, the role of facial expression has largely been overlooked, in part due to the lack of comprehensive longitudinal data on the change in both expression lines and persistent wrinkles with age. Objectives To track the detailed pattern of facial wrinkling in the same group of people over several years and to verify that expression lines evolve into persistent wrinkles. In addition, to identify factors predictive of a faster or slower rate of wrinkling. Methods Standardized images were captured at baseline and at 8 years of 122 women (ages 10–72 years, skin types I–VI) with and without a smiling expression. The wrinkle pattern with expression at baseline was compared with the pattern without expression at 8 years. Severity of facial wrinkling was quantified using computer-based image analysis. Skin colour, hydration, sebum and pH were measured at baseline. A structured questionnaire captured demographic and lifestyle data at baseline and at 8 years. Results Each subject’s unique pattern of persistent facial wrinkling observed without expression at year 8 was predicted by the pattern of lines observed with a smiling expression at baseline. Having a drier, more alkaline stratum corneum, a lighter complexion, being middle-aged (40s) or becoming menopausal were associated with faster persistent wrinkling. Conclusions Repeated skin flexure during facial expression causes persistent wrinkles. The pattern of expression lines predicts the pattern of future persistent wrinkles. Certain intrinsic and extrinsic factors are not causative, but influence the rate, of facial wrinkling.

BACKGROUND: The number of studies that use objective and quantitative methods to evaluate facial skin aging in elderly people is extremely limited, especially in Japan. Therefore, in this cross-sectional study we attempted to characterize the condition of facial skin (hyperpigmentation, pores, texture, and wrinkling) in Japanese adults aged 65 years or older by using objective and quantitative imaging methods. In addition, we aimed to identify lifestyle factors significantly associated with these visible signs of aging. METHODS: The study subjects were 802 community-dwelling Japanese men and women aged at least 65 years and living in the town of Kurabuchi (Takasaki City, Gunma Prefecture, Japan), a mountain community with a population of approximately 4800. The facial skin condition of subjects was assessed quantitatively using a standardized facial imaging system and subsequent computer image analysis. Lifestyle information was collected using a structured questionnaire. The association between skin condition and lifestyle factors was examined using multivariable regression analysis. RESULTS: Among women, the mean values for facial texture, hyperpigmentation, and pores were generally lower than those among age-matched men. There was no significant difference between sexes in the severity of facial wrinkling. Older age was associated with worse skin condition among women only. After adjusting for age, smoking status and topical sun protection were significantly associated with skin condition among both men and women. CONCLUSIONS: Our study revealed significant differences between sexes in the severity of hyperpigmentation, texture, and pores, but not wrinkling. Smoking status and topical sun protection were significantly associated with signs of visible skin aging in this study population.

Aim: To study the relationship between age-related maculopathy (ARM) and exposure to sunlight using an objective method. Methods: In a case–control study of Japanese men aged ⩾50 years (67 controls without ophthalmic disease and 148 with ARM), those with ARM were separated into groups of early (n = 75) and late (n = 73) ARM. Facial wrinkle length and area of hyperpigmentation, which are considered to be associated with exposure to sun, were measured using imaging with computer-based image analysis. Skin tone was also measured on the upper inner arm, which is not exposed to sun. Early and late ARM association with skin measurements was then evaluated. Results: Significantly more facial wrinkling (p = 0.047, odds ratio 3.8; 95% CI 1.01 to 13.97) and less facial hyperpigmentation (p = 0.035, odds ratio 0.3; 95% CI 0.08 to 0.92) was present in late ARM cases. The relationship between skin tone and ARM risk was not statistically significant. Conclusions: This objective method showed that lifetime exposure to sunlight is an important factor in the progression of late ARM. An individual’s reaction to sunlight exposure may have a role in ARM progression in addition to total lifetime exposure to sunlight.

SummaryBackground Cutaneous hyperpigmentation occurs in multiple conditions. In addition, many Asian women desire a lighter skin colour. Thus, there is a need for the development of skin lightening agents. Niacinamide is a possible candidate. Objectives To investigate the effects of niacinamide on melanogenesis in vitro and on facial hyperpigmentation and skin colour in vivo in Japanese women. Methods Melanin production was measured in a purified mushroom tyrosinase assay, cultured melanocytes, a keratinocyte/melanocyte coculture model, and a pigmented reconstructed epidermis (PREP) model. The clinical trials included 18 subjects with hyperpigmentation who used 5% niacinamide moisturizer and vehicle moisturizer in a paired design, and 120 subjects with facial tanning who were assigned to two of three treatments: vehicle, sunscreen and 2% niacinamide + sunscreen. Changes in facial hyperpigmentation and skin colour were objectively quantified by computer analysis and visual grading of high-resolution digital images of the face. Results Niacinamide had no effect on the catalytic activity of mushroom tyrosinase or on melanogenesis in cultured melanocytes. However, niacinamide gave 35–68% inhibition of melanosome transfer in the coculture model and reduced cutaneous pigmentation in the PREP model. In the clinical studies, niacinamide significantly decreased hyperpigmentation and increased skin lightness compared with vehicle alone after 4 weeks of use. Conclusions The data suggest niacinamide is an effective skin lightening compound that works by inhibiting melanosome transfer from melanocytes to keratinocytes.

Background/aims: The aim of this study was to quantify and confirm the efficacy of cosmetic formulations for hyperpigmented spots over a wide area of the face using a high quality digital imaging system that we developed. Methods: A total of 120 Japanese female volunteers aged 25–60 years with solar lentigines were treated for 6 months with a skin lightening moisturizer (SLM, thereafter) containing 3% magnesium ascorbyl phosphate on one side of the face and vehicle on the other side. During the course of the study, facial images were collected by the image analysis to measure facial skin colour and the total area of hyperpigmented spots. The evaluation was also conducted by visual grading. Measurements were made before and 1, 3, and 6 months after starting the application, and again 6 months after discontinuing the treatment. Three similar clinical studies using the same protocol were repeated for up to one-month to confirm the reproducibility of the results and to examine seasonal variation. Results: SLM significantly reduced the total area of hyperpigmented spots (P

Image analysis and biophysical methods were used to compare the skin condition of a group of females ranging in age from 5 to 65 years who had lived all of their lives in either Kagoshima (n=300), located in southern Japan, or Akita (n=302), located in northern Japan. Kagoshima annually receives approximately 1.5 times more solar UVB radiation than Akita. The methods used and corresponding skin parameters reported in this survey were: high resolution digital imaging followed by computer analysis of facial images for facial skin wrinkling and hyperpigmentation; silicone skin replicas followed by Moiré interferometry for facial skin surface roughness (texture); the Minolta Chromameter for skin color (L*a*b*) on sun-exposed (forehead) and sun-protected (upper inner arm) skin sites; the Corneometer for skin capacitance (hydration) on the cheek and ventral forearm; the Sebumeter for sebum excretion rate on the forehead; and the Minolta Spot Thermometer for skin temperature on the upper cheek. Compared with Japanese women living in Akita, Japanese women living in Kagoshima had significantly longer facial wrinkles, higher number of wrinkles, larger hyperpigmented spots, higher number of spots, rougher facial skin texture, more yellow foreheads and upper inner arms, darker foreheads, and less stratum corneum hydration in the cheeks and arms. When compared on an age-for-age basis, the average 40-year-old Kagoshima women has the same level of facial wrinkling as a 48-year-old Akita women, a delay of 8 years for living in the northern latitude. For facial hyperpigmentation, the delay is 16 years; the average 40-year-old Kagoshima women has the same level of facial hyperpigmentation as a 56-year-old Akita women. The results further testify to the skin damaging effects of sun exposure and may be useful in public health education to promote everyday sun protection.

The clinical characteristics of photodamaged skin, such as coarse and fine wrinkling, can not be quantitatively evaluated from ordinary photographic records. The purpose of this study was to assess the efficacy of glycolic acid (GA) peeling on facial wrinkling, using computer assisted image analysis. This was accomplished with reproducible imaging techniques, which allowed precise repositioning of the subject's face in front of the camera. Two parameters, the change in wrinkle number and the change in wrinkle length were assessed. Although the clinical improvement of wrinkles correlated with both parameters, wrinkle length more precisely reflected the degree of clinical wrinkles, because the wrinkle number appeared to increase as some shallow wrinkles divided into multiple smaller wrinkles during their improvement. Comparison of responses by different age groups showed that the reduction of total wrinkle length was observed in the order of: 50s>30s and 40s>60s>over 70>under 30. The lack of response by subjects over 70 might be due to the nature of their wrinkles being mainly coarse wrinkles rather than fine ones. We next compared the effect of GA by concentration (35, 50 or 70%), but found no significant differences. As the concentration of GA used for treatment was determined by each subject's erythema reaction, our present result suggests that erythema elicited by GA correlates with improvement of wrinkles and that these two phenomena can be induced by a common pathway of GA treatment. This quantitative analysis clearly shows the efficacy and limitation of GA treatment of wrinkles, and might help to disclose the precise mechanisms of GA effects on the skin structure and function.

In order to better understand the effect of chronic sun exposure on facial skin photo-aging and to identify the factors affecting it, we planned a study in two areas in Japan, Akita and Kagoshima, which correspond to the low and high sun exposure environments, respectively. As a first step, we conducted a pilot study in the two areas, examining 195 subjects. Hyper-pigmentation and wrinkling were measured with a high-resolution digital video imaging system. As expected, people in Kagoshima had darker skin, higher visual grades of facial hyper-pigmentation, and more facial wrinkles than people in Akita, reflecting the difference of UV exposure levels in the two areas. Both the grades of hyper-pigmentation and number of wrinkles increased in a roughly linear fashion with the advancement of age. On the other hand, the effect of gender was different in those two skin photo-aging parameters. Women had higher hyper-pigmentation grades (P = 0.012) and less wrinkles (P = 0.004) than men. Interestingly, post-menopausal women had higher grades of hyper-pigmentation than pre-menopausal women. Neither sun exposure index for darkness nor wrinkling showed any significant differences by menopausal status. In this pilot study, we collected information on various factors, including life-styles. The results of detail analysis will be presented elsewhere. In the present analysis, we found that the grade of hyper-pigmentation was not related to total hours spent outside in life but was affected by various factors, including toe-nail zinc levels. On the other hand, the number of wrinkles was significantly related to total hours spent outside in life. The most important risk factors of non-melanoma skin cancer are chronic sun exposure, age and male sex. All of them are strongly related to higher levels of UV exposure. The present study confirmed that chronic sun exposure, age and male sex were strong risk factors of the wrinkle number. The number of wrinkles was significantly related to total hours of sun exposure in life, increased in a roughly linear fashion with the advancement of age, and was larger in men than in women. In epidemiological studies of UV-related skin cancer, the number of wrinkles, which can be easily measured with a high-resolution digital video imaging system as shown in this study, may be a good marker of total sun exposure in life.

The fidelity of E. coli DNA polymerase I in the presence of Mg2+ vs Mn2+ was examined at many positions along natural DNA templates, by use of an electrophoretic assay of misincorporation. Although there was an overall greater tendency for misincorporation to occur in Mn2+-activated chain elongation, some specific sites on the template were more prone to misincorporation with Mg2+ and others with Mn2+. This sequence-dependent effect was seen in spite of the finding that the relative rate of incorporation of the correct nucleotide at different positions on the template was essentially the same with Mg2+ and Mn2+. In agreement with previous studies, the fidelity of E. coli pol I was higher at activating, than at inhibiting, concentrations of Mg2+. The results reveal new complexities regarding the role of divalent cation in the control of fidelity in DNA synthesis and attest to the dynamic nature of interactions between DNA polymerase, its substrates and divalent metal activator during the course of polymerization on natural templates.