ABSTRACT
Correction for 'A library of action spectra for erythema and pigmentation' by Alois W. Schmalwieser et al., Photochem. Photobiol. Sci., 2012, 11, 251-268, DOI: .
ABSTRACT
Mutations in sunlight-induced melanoma arise from cyclobutane pyrimidine dimers (CPDs), DNA photoproducts that are typically created picoseconds after an ultraviolet (UV) photon is absorbed at thymine or cytosine. We found that in melanocytes, CPDs are generated for >3 hours after exposure to UVA, a major component of the radiation in sunlight and in tanning beds. These "dark CPDs" constitute the majority of CPDs and include the cytosine-containing CPDs that initiate UV-signature CâT mutations. Dark CPDs arise when UV-induced reactive oxygen and nitrogen species combine to excite an electron in fragments of the pigment melanin. This creates a quantum triplet state that has the energy of a UV photon but induces CPDs by energy transfer to DNA in a radiation-independent manner. Melanin may thus be carcinogenic as well as protective against cancer. These findings also validate the long-standing suggestion that chemically generated excited electronic states are relevant to mammalian biology.
Subject(s)
DNA Damage/genetics , DNA/radiation effects , Melanins/metabolism , Melanocytes/radiation effects , Melanoma/genetics , Neoplasms, Radiation-Induced/genetics , Pyrimidine Dimers/metabolism , Skin Neoplasms/genetics , Animals , Cells, Cultured , Cytosine/metabolism , DNA/chemistry , DNA/genetics , Energy Transfer , Humans , Melanins/chemistry , Melanocytes/metabolism , Mice , Mice, Inbred C57BL , Mutagenesis , Mutation , Photons , Receptor, Melanocortin, Type 1/genetics , Sunlight/adverse effects , Thymine/metabolism , Ultraviolet RaysABSTRACT
The first action spectra for erythema and delayed pigmentation in human skin were determined 90 years ago by Karl Hausser and Wilhelm Vahle in Germany, and since then a number of studies have been undertaken to redefine these action spectra. In this paper we give an overview of the action spectra for erythema and pigmentation that have been published during this 90-yr period, as well as indicating their uncertainties and shortcomings.
Subject(s)
Erythema/etiology , Pigmentation/radiation effects , Spectrum Analysis/methods , Ultraviolet Rays/adverse effects , Animals , Dose-Response Relationship, Radiation , Erythema/physiopathology , Humans , Time FactorsABSTRACT
In this study the personal exposure to solar UV radiation in an urban environment was measured. Lifestyle in an urban environment is characterized by staying indoors during most of the day. Furthermore, the ambient UV radiation is mitigated by shadowing by buildings. The aim of the study was to find out activities which may contribute to UV-induced health risk in a low exposure environment. Exposure was measured during typical outdoor activities: shopping, walking, sitting in a sidewalk café, cycling, sightseeing and at an open-air pool (solar elevation: 10 degrees-70 degrees). Measurements were taken with an optoelectronic device which was fixed on the chest. Besides the UV Index we used the sun burn time (SBT) for risk assessments. Generalization of our results was made by calculating ratios of personal exposure to the ambient UV radiation. UV exposure was by far the highest when our study subject stayed at the swimming pool. The SBT was around 30 min for melano-compromised skin type. For all other activities, except shopping, the SBT range up to 1 h. With respect to photodamage we found that at high solar elevation (>45 degrees) photoprotective measures should be applied for certain activities even within a city.
