UVA radiation (95–97% of the UVR that reaches Earth’s surface) penetrates deeply into the skin, where it can contribute to skin cancer indirectly via generation of DNA-damaging molecules such as hydroxyl and oxygen radicals. Most public health messages of the past century have focused on the hazards of too much sun exposure. Today’s scientists have come to a similarly dichotomous recognition that exposure to the ultraviolet radiation (UVR) in sunlight has both beneficial and deleterious effects on human health. For the ancient Greeks and Romans, Apollo was the god of medicine and healing as well as of sun and light-but Apollo could bring sickness as well as cure. Marks, R.) 66–73 (Blackwell Scientific, Oxford, 1994).Each day, Apollo’s fiery chariot makes its way across the sky, bringing life-giving light to the planet. in Retinoids in Cutaneous Malignancy (ed. Pathophysiology of premature skin aging induced by ultraviolet light. Retinoic acid inhibits induction of c-Jun protein by ultraviolet radiation that occurs subsequent to activation of mitogen-activated protein kinase pathways in human skin in vivo. Molecular basis of sun-induced premature skin ageing and retinoid antagonism.

Treatment of photodamage with topical tretinoin: An overview. Vitamin D: New horizons for the 21st century. in Le Temps Chanel (Le Chene/Grasset, Paris, 1980 ).

in Phototherapy (Edward Arnold Publishing, London, 1901 ).

Ultra irradiation of human skin causes functional vitamin A deficiency, preventable by all- trans retinoic acid pre-treatment.

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