Effect of Ultra-violet Irradiation on Skin Collagen

Journal/Book: Reprinted from Nature Vol. 211 No. 5044 Pp. 97-98 July 2 1966. 1966;

Abstract: EVA BOTTOMS Department of Dermatology Royal Victoria Infirmary Newcastle upon Tyne. C. W. CATER British Leather Manufacturers Research Association Milton Park Egham Surrey. SAM SHUSTER Department of Dermatology Royal Victoria Infirmary Newcastle Upon Tyne. Bottoms and Shuster1 have shown that when hairless mouse skin is exposed to ultra-violet irradiation in vitro there is a decrease in the saline and citrate soluble collagen fractions; however the insoluble collagen remains unchanged. At the same time there is an increase in the toughness of the pelts. It was suggested that these effects of ultra-violet irradiation were due to increased cross-linkage between the collagen fibrils. In the experiments described here we attempted to measure the degree of cross-linkage of mouse skin and kangaroo tail tendon collagen before and after ultra-violet irradiation. Harwell homozygous hairless albino mice were used throughout. Their necks were broken and after a longi-tudinal incision made dorsally and ventrally the approxi-mately equal half-pelts were removed to the paws snout and tail. Subcutaneous fat was dissected away; the skin was dried with filter paper and weighed. One half-pelt was exposed to ultra-violet irradiation - the other half from the same mouse served as the control. Salt-extracted acetone-dehydrated kangaroo tail tendons2 were given by the Research Station Department of Agriculture and Stock Warwick Queensland Australia. They were re-hydrated by soaking in distilled water for 24 h and in 0·9 per cent sodium chloride for a further 24 h. The tendons were then divided into two equal lengths one half being exposed to ultra-violet irradiation and the other half of the same tendon being used as control. The tendons and skins were placed in glass dishes such that the epidermis of the skin was uppermost. In some experiments the tendons and skins were placed directly on the glass in other experiments they were placed on a filter paper. The rims of the dishes were layered with silicone grease in order to make an airtight joint when they were covered by a quartz plate. The dishes containing the control tissues were covered with black paper to exclude the ultra-violet irradiation. Irradiation was carried out in a refrigerator so as to minimize bacterial decomposition the dishes being placed at the bottom of a refrigerator at -20° C. The ultra-violet source was from a medium pressure mercury are (Hanovia lamp ultra-violet S.220 arc tube type 504/4) and it was directed downwards from a point 24 in. above the pelts and tendons. Exposures were for 19 or 44 h. At the end of the exposure the temperature adjacent to the tissues was never > - 4° C. ___MH

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