Sunburn and mechanisms of protection 43 52 pathak, M. A. and Stratton, K. Free radicals in human skin before and after exposure to light. Arch. Blochem. 123 468 (1968). 53 Dubouloz, P. and Dumas, J. Sur la formation de peroxydes lipidique dans la peau sous l'action des radiations. In: Proc. I Intern. Congr. Photobiol. 247 (1954) M. Veenman & Zonen, Wageningen. 54 Meffert, H. and Lohrisch, I. Hemmung der Atmung von epidermiszellen und fibroblasten durch Produkte der Lipidperoxydation. Dermatol. Monatsschr. 157 793 (1971). 55 Black, H. S. and Douglas, D. R. Formation of a carcinogen of natural origin in the etiology of ultraviolet light-induced carcinogenesis. Cancer Res. 33 2094 (1973). 56 Setlow, R. B. The photochemistry, photobiology and repair of polynucleotides. In: Davidson, J. N. and Cohn, W. E. Advances in Nucleic Acid Research and Molecular Biology vol. 8, 257 (1968) Academic Press, London. 57 Smith, K. C. and Hanawalt, P. C. Molecular Photobiology (1969) Academic Press, London. 58 Rauth, A.M. Effects of ultraviolet light on mammalian cells in culture. In: Ebert, M. and Howard, R. Current Topics in Radiation Research vol. 6, 193 (1970) North Holland. 59 Howard-Flanders, p. DNA repair and recombination. Brit. Med. Bull. 29 226 (1973). 60 Lehmann, A. R. Postreplication repair of DNA in mammalian cells. Life Sci. 15, 2005 (1974). 61 Cook, J. S. Photoreactivation in animal cells. In: Giese, A. C. Photophysiology vol. 5, 191 (1970) Academic Press, London. 62 Sutherland, Betsy. Photoreactivating enzyme from human leukocytes. Nature 248 109 (1974). 63 Fukuyama, K., Epstein, W. L. and Epstein, J. H. Effect of ultraviolet light on RNA and protein synthesis in differentiated epidermal cells. Nature 216 1031 (1967). 64 Epstein, J. H., Fukuyama, K. and Epstein, W. L. U.V.L. induced stimulation of DNA synthesis in hairless mouse epidermis. J. Invest. Dermatol. 51 445 (1968). 65 Ticknet, A. Changes in the phospholipids of mouse skin after ultraviolet irradiation in vitro. Blochem. J. 88 80 (1963). 66 Baden, H. P. and Pearlman, C. The effect of ultraviolet light on Protein and nucleic acid synthesis in the epidermis. J. Invest. Dermatol. 42 71 (1964). 67 Kraemer, D. M., Pathak, M. A., Kornhauser, A. and Wiskemann, A. Effect of ultraviolet irradiation on biosynethesis of DNA in Guinea Pig skin in vivo. J. Invest. Dermatol. 62 388 (1974). 68 Pathak, M. A., Kraemer, D. M. and Gungerich, U. Formation of thymine dimers in epidermis by ultraviolet (290--320 nm) radiation in vivo. J. Invest. Dermatol. 54 351 (1970). 69 Pathak, M. A., Kraemer, D. M, and Gungerich, U. Formation of thymine dimers in mammalian skin by ultraviolet radiation in vivo. Photochem. Photobiol. 15 177 (1972). 70 Bowden, G. T., Trosko, J. E., Shapas, B. G. and Boutwell, R. K. Excision of pyrimidine dimers from epidermal DNA and non-semiconservative epidermal DNA synthesis following ultraviolet irradiation of mouse skin. Cancer Res. 35 3599 (1975). 71 Cooke, A. and Johnson, B. E. Dose response, wavelength dependence and rate of excision of ultra- violet radiation-induced pyrimidine dimers in mouse skin DNA. Biochem. Biophys. Acta. in press. 72 Cleaver, J. E. Defective repair replication of DNA in Xeroderma pigmentosum. Nature, 218 652 (1968). 73 Lehmann, A. R., Kirk-Bell, S., Arlett, C. F., Paterson, F. C., Lohman, p., deWeerd-Kastelein, E. A. and Bootsma, D. Xeroderma Pigmentosum cells with normal levels of excision repair have a defect in DNA synthesis after uv-irradiation. Proc. Nat. Acad. Sci. U.S. 72 219 (1975). 74 Lehmann, A. R., Kirk-Bell, S., Arlett, C. F., Harcourt, S. A., de Weerd-Kastelein, E. A., Keijzer, W. and Hall-Smith, P. Repair of ultraviolet light damage in a variety of human fibroblast cell strains. Cancer Res. 37 904 (1977). 75 Musajo, L. and Rodighiero, (3. Mode of photosensitizing action of furocoumarins. In: Giese, A. C. Photophysiology vol. 7, 115 (1972) Academic Press, London. 76 Pathak, M. A., Kraemer, D. M. and Fitzpatrick, T. B. Photobiology and photochemistry of furo- coumarins (psoralens). In: Ftizpatrick, F. B. Sunlight and Man 335 (1974) University of Tokyo Press. 77 Ichihashi, M. and Ramsay, C. A. Excision repair of DNA in some photodermatoses. Brit. J. Dermatol. 95 13 (1976). 78 Winder, C. V., Wax, J., Burr, V., Been, M. and Rosiere, C. E. A study of pharmacological influences on ultraviolet erythema in Guinea Pigs. Arch. Internat. Pharm. Dyn. 116 261 (1958). 79 Logan, G. and Wilhelm, D. L. The inflammatory reaction in ultraviolet injury. Brit. J. Exp. Path. 47 286 (1966).

44 B. E. Johnson 80 Lewis, T. The blood vessels of the human skin and their responses (1927) Shaw, London. 81 Partington, M. W. The vascular response of the skin to ultraviolet light. Clin. Sci. 13 425 (1954). 82 Lloyd, J. and Johnson, B. E. Triprolidine and the response of skin to ultraviolet radiation. Brit. J. Dermatol. 77 244 (1965). 83 Claesson, S., Juhlin, L. and Wettermark, G. The action of ultraviolet light on skin with and without horny layer the effect of 48/80 and methotrimeprazine. Acta Derre. Vener. 39 3 (1959). 84 Greaves, M. W. Personal communication (1976). 85 Epstein, J. H. and Winkelmann, R. K. Ultraviolet light-induced kinin formation in human skin. Arch. Dermatol. 95 532 (1967). 86 Greaves, M. W. and Sondergaard, J. Phatmacologic agents released in ultraviolet inflammation studied by continuous skin perfusion. J. Invest. Dermatol. 54 365 (1970). 87 Mathur, G. P. and Gandhi, V. M. Prostaglandin in human and albino rat skin. J. Invest. Dermatol. 58 291 (1972). 88 Snyder, D. S. and Eaglstein, W. H. Topical indomethacin and sunburn. Brit. J. Dermatol. 90 91 (1974). 89 Synder, D. S. Cutaneous effects of topical indomethacin, an inhibitor of prostaglandin synthesis, on uv-damaged skin. J. Invest. Dermatol. 64 322 (1975). 90 Kaidbey, K. H. and Kurban, A. K. The influence of corticosteroids and topical indomethacin on sunburn erythema. J. Invest. Dermatol. 66 153 (1976). 91 Blum, H. F. Carcinogensis by ultraviolet light (1959) Princeton University Press. 92 Epstein, J. H. Ultraviolet carcinogenesis. In: Geise, A. C. Photophysiologyvol. 5, 235 (1970)Academic Press, London. 93 Urbach, F., Epstein, J. H. and Forbes, P. D. Ultraviolet carcinogenesis: experimental, global and genetic aspects. In: Fitzpatrick, T. B. Sunlight and Man 259 (1974) University of Tokyo Press. 94 Mathews-Roth, M. M., Pathak, M. A., Pmrish, J. A., Fitzpatrick, T. B., Kass, E. H., Toda, K. and Clemens, W. A clinical trial of the effects of oral beta-carotene on the responses of human skin to solar radiation. J. Invest. Dermatol. 59 349 (1972). 95 Miescher, G. Die Schutzfunktionen der Haut gegeniiber Lichtstrahlen. Strahlentherapie 39 601 (1931). 96 Zenisek, A., Kral, J. A. and Hais, I. M. Sun-screening effect of urocanic acid. Blochim. Biophys. Acta 18 589 (1955). 97 Everett, M. A., Anglin, J. H. and Bever, A. T. Ultraviolet induced biochemical alterations in skin. I. Urocanic acid. Arch. Dermatol. 84 717 (1961). 98 Baden, H. P. and Pathak, M. A. Urocanic acid in keratinizing tissue. Biochim. Biophys. Acta 104• 200 (1965). 99 Baden, H. P. and Pathak, M. A. The metabolism and function of urocanic acid in skin. J. Invest. Dermatol. 48 11 (1967). 100 Hais, I. M. and Strych, A. Increase in urocanic acid content in human epidermis following in- solation. Collection Czechoslov. Chem. Commun. 34 649 (1969). 101 Quevedo, W. C., Jr., Bienieki, T. C., McMorris, F. A. and Hepinstall, M. J. Environmental and genetic influences on radiation-induced tanning of murine skin. In: Montagna, W. and Hu, F. Advances in Biology of Skin, vol. 8, The Pigmentary System 361 (1967) Pergamon Press, Oxford. 102 Szabo, G. Photobiology of melanogenesis: cytological aspects with special reference to differences in racial coloration. In: Montagna W. and Hu, F. Advances in Biology of Skin, vol. 8, The Pig- mentary System 379 (1967) Pergamon Press, Oxford. 103 Pathak, M. A. Photobiology of melanogenesis: biophysical aspects. In: Montagna, W. and Hu, F. Advances in Biology of Skin, vol. 8, The Pigmentary System 397 (1967) Pergamon Press, Oxford. 104 Loomis, W. F. Vitamin D, sunlight and natural selection. Science 159 653 (1968). 105 Daniels, F., Jr., Post, P. W. and Johnson, B. E. Theories of the role of pigment in the evolution of human races. In: Riley, V. Pigmentation, its genesis and biologic control 13 (1972) Appleton- Century-Crofts, New York. 106 Thomson, M. L. Relative efficiency of pigment and horny layer thickness in protecting the skin of Europeans and Africans against solar ultraviolet radiation. J. Physiol. 127 236 (1955). 107 Pathak, M. A. and Fitzpatrick, T. B. The role of natural photoprotective agents in human skin. In: Fitzpatrick, T. B. Sunlight and Man 725 (1974) University of Tokyo Press. 108 Kligman, A.M. Comments on the stratum corneum. In: Urbach, F. The Biologic Effects of Ultra- violet Radiation 165 (1969) Pergamon Press, Oxford.