Impact of Long-Wavelength UVA and Visible Light on Melanocompetent Skin (original) (raw)
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Short- and long-term effects of UV radiation on the pigmentation of human skin
The journal of investigative dermatology. Symposium proceedings / the Society for Investigative Dermatology, Inc. [and] European Society for Dermatological Research, 2009
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.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 32-35; doi:10.1038/jidsymp.2009.10.
Visible Light Induces Melanogenesis in Human Skin through a Photoadaptive Response
PLOS ONE, 2015
Visible light (400-700 nm) lies outside of the spectral range of what photobiologists define as deleterious radiation and as a result few studies have studied the effects of visible light range of wavelengths on skin. This oversight is important considering that during outdoors activities skin is exposed to the full solar spectrum, including visible light, and to multiple exposures at different times and doses. Although the contribution of the UV component of sunlight to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology in terms of inflammation, and limited information is available regarding the role of visible light on pigmentation. The purpose of this study was to determine the effect of visible light on the pro-pigmentation pathways and melanin formation in skin. Exposure to visible light in ex-vivo and clinical studies demonstrated an induction of pigmentation in skin by visible light. Results showed that a single exposure to visible light induced very little pigmentation whereas multiple exposures with visible light resulted in darker and sustained pigmentation. These findings have potential implications on the management of photo-aggravated pigmentary disorders, the proper use of sunscreens, and the treatment of depigmented lesions.
Skin pigmentation characterized by visible reflectance measurements
Lasers in Medical Science, 1997
The epidermal melanin content affects most dermatologic treatments involving light, and can limit the therapeutic success significantly. Therefore, knowledge of the optical properties of skin is required. This study investigates how the concentration of melanin influences visible reflectance spectra of skin and the relationship to threshold radiant energy fluence for melanosomal or melanocyte destruction. Reflectance spectra were measured at 28 pigmented human skin sites in vivo. For Asian and Caucasian subjects, measured reflectance values varied over the same range, while significantly lower values were recorded for African individuals. Epidermal melanin absorption coeMcients measured at 694 nm were about 2500 m-1 for African, and 300-1200 m-1 for Caucasian and Asian skin. Twenty-five skin sites were exposed to ruby laser pulses (694 rim), where the pulse duration was long enough to allow heat diffusion between melanosomes. Hypopigmentation occurred, on average, at 12 and 26 J cm 2 for sun-exposed and sun-protected white skin, respectively, while slightly lower threshold values resulted from the measured spectra. As visible reflectance spectra reveal information regarding skin pigmentation and individual threshold doses for melanosomal damage, a use as a diagnostic tool in various dermatological laser treatments is apparent.
The Effect of Long Exposure of Uv Radiation on Erythema and Melanin Index
Berkala kedokteran, 2022
UV radiation are divided into 3, namely UV A (400-315 nm), UV B (315-280 nm), UV C (280-100 nm). UV C radiation have the greatest effect on skin damage compared to UV A and UV B. UV radiation can reach the earth's surface, that can cause burning of the skin with signs such as redness of the skin (erythema), pain, blistering and peeling of the skin. Until now there has been no research on the effect of long exposure of UV C radiation on the erythema and melanin index, so aim this research is know about the effect of long exposure of UV C radiation on the erythema and melanine index. This research was conducted by giving exposure to rat that had been shaved with variations in exposure time, namely 5 minutes, 10 minutes, 15 minutes and 20 minutes. The skin that has been exposed with UV radiation will be photographed for color analysis using a chromometer. The results showed that exposure of UV radiation for 10 minutes caused the greatest increase in the melanin and erythema index
Pigment Cell Research, 2003
The relationship between skin colour and experimental exposure to ultraviolet radiation (UVR) B, with response measured as erythema was studied. Two reflectance methods were used to measure skin colour-tristimulus colorimetry using a Minolta instrument (summarized as the a characteristic angle) and the melanin index based on the Diastron reflectance instrument. As expected both measures are highly correlated (0.91). A dosedependent relationship between skin colour measured as the a characteristic angle and UVR was established, with the gradient increasing from 0.99 at 119 mJ to 2.7 at 300 mJ, with the relevant standard errors being 0.39 and 0.47, respectively. Similarly, for the melanin index (where the scale goes in the opposite direction) the gradient differs between)0.49 for 119 mJ and)0.91 for 300 mJ, with the standard errors being 0.14 and 0.17 respectively. The proportion of variation explained is also greater at higher UVR challenge doses. Studies relating UVR sensitivity and pigmentation need to take account of the dose of UVR administered.
Regulation of human skin pigmentation and responses to ultraviolet radiation
Pigment Cell Research, 2007
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. Melanin is significantly photoprotective and epidermal cells in darker skin incur less DNA damage than do those in lighter skin. This review summarizes current understanding of the regulation of constitutive human skin pigmentation and responses to UV radiation, with emphasis on physiological factors that influence those processes. Further research is needed to characterize the role of skin pigmentation to reduce photocarcinogenesis and to develop effective strategies to minimize such risks.
Spectral Responses of Melanin to Ultraviolet A Irradiation
Journal of Investigative Dermatology, 2004
The purpose of this investigation was to study the ultraviolet A-induced effects on melanin pigmentation both in an in vitro model system and in vivo. Ultraviolet-Vis absorbance spectra of L-3,4-dihydroxyphenylalanine-melanin solutions at different concentrations were measured before and after ultraviolet A exposure (10-120 J per cm 2 ). The difference spectra reveal that following ultraviolet A exposure the absorbance increases exponentially from 800 nm to 450 nm accompanied by a prominent decrease of absorbance in the ultraviolet A range. This change of spectral features depends on both ultraviolet A doses and melanin concentrations. The photo-bleaching effect observed in the ultraviolet A range also depends on oxygen. Human subjects were irradiated with ultraviolet A (40-80 J per cm 2 ) on their back and diffuse reflectance spectra were collected at both irradiated and untreated sites. The absorption spectra of ultraviolet A-induced pigment were calculated as the difference of the two. The ultraviolet A-induced pigment in vivo has similar spectral characteristics and dose dependency as the in vitro system. Photo-oxidation of pheomelanin solutions presents distinctively different spectral and dose-response characteristics from eumelanin. After ultraviolet A irradiation pheomelanin absorbance decreases both in the visible and the ultraviolet A range. We conclude that irradiation with ultraviolet A induces significant photochemical alterations in the skin witnessed by increased photoprotection in the visible spectral range and reduced protection in the ultraviolet A range. We suggest that soluble melanin plays an important part in ultraviolet A-induced pigment in skin and two distinct absorption mechanisms of melanin may be involved in ultraviolet A photo-oxidation. We also propose that eumelanin and pheomelanin could be differentiated according to their spectral responses to ultraviolet A irradiation.
Mechanisms of Skin Tanning in Different Racial/Ethnic Groups in Response to Ultraviolet Radiation
Journal of Investigative Dermatology, 2005
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. We measured the distribution of DNA damage that results, as well as the melanin content/distribution and the expression of various melanocyte-specific genes. The density of melanocytes at the epidermal:dermal junction in different types of human skin are remarkably similar and do not change significantly within 1 wk after UV exposure. The expression of melanocyte-specific proteins (including TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), DCT (tyrosinase-related protein 2), MART1 (melanoma antigens recognized by T-cells) gp100 (Pmel17/silver), and MITF (micropthalmia transcription factor)) increased from 0 to 7 d after UV exposure, but the melanin content of the skin increased only slightly. The most significant change, however, was a change in the distribution of melanin from the lower layer upwards to the middle layer of the skin, which was more dramatic in the darker skin. These results provide a basis for understanding the origin of different skin colors and responses to UV within different races.
Effects of Visible Light on the Skin
Photochemistry and Photobiology, 2008
Electromagnetic radiation has vast and diverse effects on human skin. Although photobiologic studies of sunlight date back to Sir Isaac Newton in 1671, most available studies focus on the UV radiation part of the spectrum. The effects of visible light and infrared radiation have not been, until recently, clearly elucidated. The goal of this review is to highlight the effects of visible light on the skin. As a result of advances in the understanding of skin optics, and comprehensive studies regarding the absorption spectrum of endogenous and exogenous skin chromophores, various biologic effects have been shown to be exerted by visible light radiation including erythema, pigmentation, thermal damage and free radical production. It has also been shown that visible light can induce indirect DNA damage through the generation of reactive oxygen species. Furthermore, a number of photodermatoses have an action spectrum in the visible light range, even though most of the currently available sunscreens offer, if any, weak protection against visible light. Conversely, because of its cutaneous biologic effects, visible light is used for the treatment of a variety of skin diseases and esthetic conditions in the form of lasers, intense pulsed light and photodynamic therapy.
Pigmentation effects of solar‐simulated radiation as compared with UVA and UVB radiation
Pigment Cell & Melanoma Research, 2008
SummaryDifferent wavelengths of ultraviolet (UV) radiation elicit different responses in the skin. UVA induces immediate tanning and persistent pigment darkening through oxidation of pre‐existing melanin or melanogenic precursors, while UVB induces delayed tanning which takes several days or longer to develop and requires activation of melanocytes. We compared the effects of a 2‐week repetitive exposure of human skin to solar‐simulated radiation (SSR), UVA or UVB at doses eliciting comparable levels of visible tanning and measured levels of melanins and melanin‐related metabolites. Levels of eumelanin and pheomelanin were significantly higher in the order of SSR, UVB, UVA or unexposed control skin. Levels of free 5‐S‐cysteinyldopa (5SCD) were elevated about 4‐fold in SSR‐ or UVB‐exposed skin compared with UVA‐exposed or control skin. Levels of protein‐bound form of 5SCD tended to be higher in SSR‐ or UVB‐exposed skin than in UVA‐exposed or control skin. Total levels of 5‐hydroxy‐6‐m...