Kukizo Miyamoto

Quantitative evaluation of skin condition in an epidemiological survey of females living in northern versus southern Japan

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.

Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin1

Previous clinical testing of topical niacinamide (vitamin B3) has revealed a broad array of improvements in the appearance of aging facial skin. The study reported here was done to confirm some of those previous observations and to evaluate additional end points such as skin anti‐yellowing. Caucasian female subjects (n = 50, aged 40–60 years) participated in a 12‐week, double‐blind, placebo‐controlled, split‐face, left–right randomized clinical study assessing two topical products: moisturizer control product versus the same moisturizer product containing 5% niacinamide. Niacinamide was well tolerated by the skin and provided significant improvements versus control in end points evaluated previously: fine lines/wrinkles, hyperpigmentation spots, texture, and red blotchiness. In addition, skin yellowing (sallowness) versus control was significantly improved. The mechanism by which this array of benefits is achieved with niacinamide is discussed.

Reduction in the appearance of facial hyperpigmentation by topical N-acetyl glucosamine.

Glucosamine has been reported to inhibit melanin production in melanocyte culture. It thus has a potential to reduce hyperpigmentation via topical use. Due to stability limitations of glucosamine, we chose to clinically evaluate the stable derivative N‐acetyl glucosamine (NAG). Based on in vitro Franz cell testing, NAG is a good skin penetrant. In an 8‐week, double‐blind, placebo‐controlled, left‐right randomized, split‐face clinical test, topical 2% NAG reduced the appearance of facial hyperpigmentation. In a second clinical study involving the topical combination of 2% NAG with 4% niacinamide, an agent previously shown to be clinically active, the effect on hyperpigmentation was greater. Both of these agents are well tolerated by the skin. This high tolerance coupled with relative ease of formulation and stability in solution make NAG, especially in combination with niacinamide, a suitable cosmetic ingredient for use in skin care products dealing with issues of skin hyperpigmentation.

Comparison of the epidemiology of acne vulgaris among Caucasian, Asian, Continental Indian and African American women.

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.

Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topical niacinamide and N‐acetyl glucosamine: results of a randomized, double‐blind, vehicle‐controlled trial

Background  Topical niacinamide and N‐acetyl glucosamine (NAG) each individually inhibit epidermal pigmentation in cell culture. In small clinical studies, niacinamide‐containing and NAG‐containing formulations reduced the appearance of hyperpigmentation.

Acne Vulgaris in Women: Prevalence Across the Life Span

BACKGROUND Acne vulgaris is a common skin disease with a large quality of life impact, characterized by comedones, inflammatory lesions, secondary dyspigmentation, and scarring. Although traditionally considered a disease of adolescence, reports suggest it is also a disease of adults, especially adult women. Our objectives were to determine acne prevalence in a large, diverse group of women and to examine acne by subtype and in relation to other skin findings, measurements, and lifestyle factors. METHODS We recruited 2895 women aged 10-70 from the general population. Photographs were graded for acne lesions, scars, and dyspigmentation. Measurements were taken of sebum excretion and pore size, and survey data were collected. RESULTS Of the women studied, 55% had some form of acne: 28% had mild acne, and 27% had clinical acne, 14% of which was primarily inflammatory and 13% of which was primarily comedonal. Acne peaked in the teenage years, but 45% of women aged 21-30, 26% aged 31-40, and 12% aged 41-50 had clinical acne. Women with inflammatory acne were younger than those with comedonal acne (p≤0.001), and postmenopausal women had less acne than age-matched peers (p<0.0001). Acne was associated with facial hirsutism (p=0.001), large pores (p=0.001), and sebum excretion (p=0.002). Smokers had more, primarily comedonal, acne than nonsmokers. CONCLUSIONS The cross-sectional design precludes conclusions about progression of acne with age. Participation was restricted to women. The photographic nature of the study imposes general limitations. Techniques used in this study were not sufficiently sensitive to identify cases of subclinical acne. More than a quarter of women studied had acne, which peaked in the teens but continued to be prevalent through the fifth decade.

Development of a digital imaging system for objective measurement of hyperpigmented spots on the face.

Background/aims: There are few available methods that can be used to quantify hyperpigmented spots on a wide area of the face. The objective of this study was to develop such a method through the use of specialized image analysis technologies.

Ultrasound enhanced skin‐lightening effect of vitamin C and niacinamide

Background/purpose: Cutaneous hyperpigmentation occurs in multiple conditions. There is a strong need for the improvement of hyperpigmentation especially among Asian women. However, the effect of existing skin‐lightening agents is not sufficient. One reason attributes to the limited capability of active agents to be delivered transepidermally. Ultrasound is one promising approach to enhance transepidermal transport. In this work, we investigate the effect of the use of high‐frequency ultrasound together with coupling gel containing skin‐lightening agents (ascorbyl glucoside and niacinamide) on facial hyperpigmentation in vivo in Japanese women.

Lifestyle Factors and Visible Skin Aging in a Population of Japanese Elders

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.

Utilization of a high-resolution digital imaging system for the objective and quantitative assessment of hyperpigmented spots on the face

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.