Effects of Skin Temperature on UV-induced Erythema and pigmentation in Human Skin in Vivo / 대한피부과학회지

BACKGROUND: Skin temperature at UV radiation exposure influences acute skin reaction such as erythema and pigmentation. As most biochemical systems are affected by temperature, thermal change preceding or following UV exposure could influence the responses in the way to cause vascular blood flow and change the inflammatory response OBJECTIVE: To investigate the influence of thermal change on UV-induced erythema and pigmentation by using objective and quantitative method METHODS: A sunlight fluorescent sunlamp (Waldmann UV 800) was used as a UV light source. Multiple sites of the lower back were irradiated with an increasing doses of UV, which were preceded or followed by heating or cooling. With a reflectance spectrophotometer, we assessed erythema and melanin indices at control, 0.1, 0.5, 1.0 and 2.0 MED dose-exposed sites. RESULTS: Compared with the only UV-exposed group, skin warming or cooling groups generally showed elevated acute erythema reaction with higher erythema indices. However, thermal changes preceding or following UV exposure had little effect on pigmentation except the post-warming group with UV exposure of 2 MED dose after 2 weeks. Our results indicate that altering the skin temperature modulates the degree of UV-induced erythema, but generally not skin pigmentation. CONCLUSION: The results in this study show that environmental factors such as heat or cooling have modulating effects on UV-induced skin reaction. These interactions should be considered when dealing with the effects of natural sun exposure or phototherapy.

A Study of Skin Color by Melanin Index according to Sex, Age, Site and Skin Phototype in Koreans

BACKGROUND: Skin color is determined by many factors including melanin and nonmelanin pigments like hemoglobin and extraneous chemicals. Various factors such as race, sex, and age have been reported to have an influence on skin color. METHODS: Measurement of malanin index (M-index) was made by reflectance spectropho-tometer at three different sites including forehead, abdomen and forearm in total 800 healthy subjects consisting of 100 males and 100 females of neonates (three days after birth) and children (male:8.08±0.84, female:8.03±0.80, total :8.06±0.82 years of age), ado-lescence (mate:13.89± 0.76, female:13.96±0.79, total:13.93±0.78 years of age), and adults(male:24.26±0.82, female:24.40±0.89, total:24.33±0.86 years of age). We also investigated the change of M-index by each skin phototype of college students determined by Fitzpatrick classification. RESULTS: From the birth to the puberty, sex difference of melanin index was generally not not-ed, but adult females showed lower levels of melanin index in all sites measured. M-index in-creased from birth to adolescence, and decreased after adulthood. Forehead showed highest melanin index compared with other sites. Increase of M-index was noted as skin phototype goes from III to V. CONCLUSIONS: Factors including sex, age, body sites and skin phototype have a significant in-fluence on the changes of skin color in humans.

Erythema and Melanin Index According to UVB Radiation Doses by Use of a Reflectance Spectrophotometer in Korean Young Adults / 대한피부과학회지

BACKGROUND: Methods of estimating the erythema and pigmentation reactions, such as MPE (Minimal Perceptible Erythema), ME(Minimal Erythema Dose) and MMD(Minimal Melanogenic Dose), are vulnerable to the variations of subjective visual measurements. OBJECTIVE: By using objective and quantitative methods, the erythema and pigmentaton responses were investigated. METHODS: A sunlight, fluorescent lamp(Waldmann UV 800) was used as a UVB light source. Multiple sites of the lower back were irradiated with an increasing dose by a constant amount, With a reflectance spectrophotometer (DermaSpectrometer(R)), erythema and melanin indices at control, MPE, MED, MMD sites were assessed. The dose-response angle of erythema and pigmentation were calculated. RESULTS: The erythema and pigmetation indices at the control, MPE, MED and MMD sites were 8.7+/-2.0AU/30.5+/-2.6AU, 10.5+/-2.7AU/32.6+/-3.6AU, 13.2+/-3.5AU/32.6+/-3.3AU, and 10.4+/-3.0AU/ 33.5+/-2.7AU, respectively. The calculated dose-response angle accurately measured the response of skin to UVB irradiation. CONCLUSION: In this study, use of a reflectance spectrophotometer appeared to be a more sensitive and effective method than visual assessment, in addition, dose-response angles may be an objective index for determination of skin responses to UVB irradiation.