Medicinal leeches are aquatic predators that inhabit surface waters during daylight and also leave the water where they might be exposed to less screened light. Whereas the leech visual system has been shown to respond to visible light, leeches in the genus Hirudo do not appear to be as negatively phototactic as one might expect in order to avoid potential ultraviolet radiation (UVR)-induced da...

Interactions with ultraviolet radiation (UVR) and chromophores in the skin happen on a daily basis. Photodermatoses, which are abnormal responses to UV exposure, can be classified into subgroups based on pathogenesis. This review will discuss the clinical features, pathogenesis, photobiologic evaluation, prognosis and therapies of the most common photodermatoses.

Protein kinase C epsilon (PKCε), a Ca(2+)-independent phospholipid-dependent serine/threonine kinase, is among the six PKC isoforms (α, δ, ε, η, μ, ζ) expressed in both mouse and human skin. Epidermal PKCε level dictates the susceptibility of PKCε transgenic (TG) mice to the development of cutaneous squamous cell carcinomas (SCC) elicited either by repeated exposure to ultraviolet radiation (UV...

BACKGROUND Reliance on verbal self-report of solar exposure in skin cancer prevention and epidemiologic studies may be problematic if self-report data are not valid due to systematic errors in recall, social desirability bias, or other reasons. METHODS This study examines the validity of self-reports of exposure to ultraviolet radiation (UVR) compared to objectively measured exposure among ch...

Cumulative lifetime ultraviolet radiation (UVR) is an important factor in the development of squamous cell carcinoma. This study examines the impact of UVR exposure pattern on tumor development. Hairless C3.Cg/TifBomTac immunocompetent pigmented mice (n = 351) were irradiated with 12 standard erythema doses (SED)/week, given as 2 SED ×6, 3 SED ×4, 4 SED ×3, or 6 SED ×2 (dose-delivery study) or ...

Six uvr mutants of Saccharomyces cerevisiae with hypersensitivity to ultraviolet (UV) light were isolated after mutagen treatment with ethylmethanesulfonate. UV sensitivity ranges from moderate to extreme, and four of the mutants are also sensitive to nitrous acid. Ranking in terms of UV sensitivity does not parallel ranking in terms of nitrous acid sensitivity. Homozygous diploid mutant strain...

Urocanic acid (UCA), produced in the upper layers of mammalian skin, is a major absorber of ultraviolet radiation (UVR). Originally thought to be a 'natural sunscreen', studies conducted a quarter of a century ago proposed that UCA may be a chromophore for the immunosuppression that follows exposure to UVR. With its intriguing photochemistry, its role in immunosuppression and skin cancer develo...

IntroductIon Sunlight is the primary source of ultraviolet radiation (UVR) to which humans are exposed. Although a portion of the sun’s UVR is absorbed by the ozone layer of the atmosphere, significant UVR penetrates the ozone to strike the surface of the earth. For most people, the total amount of UVR received (the cumulative dose) increases linearly over time.1 Documentation that cumulative s...

Sunscreens are ultraviolet radiation (UVR)-absorbing chemicals that attenuate the amount and nature of UVR reaching viable cells in the skin. They are selected and tested for their ability to prevent erythema. No sunscreen prevents photodamage, as it has been demonstrated that suberythemal doses of UVR cause a variety of molecular changes (including DNA damage) in these cells. Furthermore, the ...

BACKGROUND Antioxidant compounds in green tea may be able to protect against skin carcinogenesis and it is of interest to investigate the mechanisms involved. A study was therefore conducted to determine whether the isolated green tea polyphenol (-)-epigallocatechin gallate (EGCG) could prevent ultraviolet radiation (UVR)-induced DNA damage in cultured human cells. This work was then extended t...