Non-invasive diffuse reflectance measurements of cutaneous melanin content can predict human sensitivity to ultraviolet radiation.

The diversity of human skin phenotypes and the ubiquitous exposure to ultraviolet radiation (UVR) underscore the need for a non-invasive tool to predict an individual's UVR sensitivity. We analysed correlations between UVR sensitivity, melanin content, diffuse reflectance spectroscopy (DR) and UVR-induced DNA damage in the skin of subjects from three racial/ethnic groups: Asian, black or African American and White. UVR sensitivity was determined by evaluating each subject's response to one minimal erythemal dose (MED) of UVR one day after the exposure.

Short- and long-term effects of UV radiation on the pigmentation of human skin.

The incidence of skin cancer, including cutaneous melanoma, has risen substantially in recent years, and epidemiological and laboratory studies show that UV radiation is a major causative factor of this increase. UV damage also underlies photoaging of the skin, and these deleterious effects of UV can be, in part, prevented in skin with higher levels of constitutive pigmentation. We review the clinical studies we have made in recent years regarding the rapid and the long-term responses of the pigmentary system in human skin to UV exposure.

Cyclobutane pyrimidine dimer formation and p53 production in human skin after repeated UV irradiation.

Substantial differences in DNA damage caused by a single UV irradiation were found in our previous study on skin with different levels of constitutive pigmentation. In this study, we assessed whether facultative pigmentation induced by repeated UV irradiation is photoprotective. Three sites on the backs of 21 healthy subjects with type II-III skin were irradiated at 100-600 J/m(2) every 2-7 days over a 4- to 5-week period.

Regulation of human skin pigmentation and responses to ultraviolet radiation.

Pigmentation of human skin is closely involved in protection against environmental stresses, in particular exposure to ultraviolet (UV) radiation. It is well known that darker skin is significantly more resistant to the damaging effects of UV, such as photocarcinogenesis and photoaging, than is lighter skin. Constitutive skin pigmentation depends on the amount of melanin and its distribution in that tissue.

Human skin responses to UV radiation: pigment in the upper epidermis protects against DNA damage in the lower epidermis and facilitates apoptosis.

Melanin plays an important role in protecting the skin against UV radiation, and melanomas and basal/squamous cell carcinomas occur more frequently in individuals with fair/light skin. We previously reported that levels of melanin correlate inversely with amounts of DNA damage induced by UV in normal human skin of different racial/ethnic groups. We have now separately examined DNA damage in the upper and lower epidermal layers in various types of skin before and after exposure to UV and have measured subsequent apoptosis and phosphorylation of p53.

Reduction of the UV burden to indoor tanners through new exposure schedules: a pilot study.

Background: The development of new pigmentation (tan) in human skin after UV exposure requires several days. Once it is developed, the tan can last for weeks. Current recommendations for tanning exposure schedules in the USA (FDA Letter to Manufacturers: Policy on maximum timer interval and exposure schedule for sunlamps, August 21, 1986) allow exposures three times per week for the development of a tan, and one to two times per week for maintenance exposures.

Quantification of UV-induced erythema and pigmentation using computer-assisted digital image evaluation.

Photography has been used in human skin research for some time. With the advent of digital photography in recent years, its use has increased. However, the focus has now turned from documentation to actual analysis and quantification of skin color changes.

Mechanisms of skin tanning in different racial/ethnic groups in response to ultraviolet radiation.

Ultraviolet radiation stimulates pigmentation in human skin, but the mechanism(s) whereby this increase in melanin production (commonly known as tanning) occurs is not well understood. Few studies have examined the molecular consequences of UV on human skin of various racial backgrounds in situ. We investigated the effects of UV on human skin of various races before and at different times after a single 1 minimal erythemal dose UV exposure.

Non-invasive measurements of skin pigmentation in situ.

Objective in situ measurements of skin pigmentation are needed for accurate documentation of pigmentation disorders, in studies of constitutive and induced skin pigmentation, for testing of the efficacy of pro-pigmentation or de-pigmentation agents, etc. Non-invasive instrumental measurements of skin pigmentation have been used for many decades. All are based on the ability of melanin to attenuate light.

Ultrasound measurements of skin thickness after UV exposure: a feasibility study.

High-frequency ultrasound images were used to measure the thickness of the dermis and epidermis of four human subjects. These measurements were performed before and after a single exposure to ultraviolet radiation (UV). Doses ranging from 0.

UV-induced DNA damage and melanin content in human skin differing in racial/ethnic origin.

DNA damage induced by UV radiation is a critical event in skin photocarcinogenesis. However, the role of racial/ethnic origin in determining individual UV sensitivity remains unclear. In this study, we examined the relationships between melanin content and DNA damage induced by UV exposure in situ in normal human skin of different racial/ethnic groups, phototypes, and UV sensitivities.