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In the Antarctica during mid-summer being appropriate for a severe environment of UV-rays, the authors surveyed the protective effect of UV-cut materials against UV-rays, using a collagen sheet (hereafter "collagen artificial skin") that was covered with a UV-cut film and subjected to exposure outdoors. First, exposure of the laminated, collagen artificial skin not covered with any film to UV-rays caused the extracts from the 1st layer, i.e. the utmost outerlayer, of the collagen artificial skin to increase the terminal amino group concentration up to as high as 3.20 nmol/ml, since the collagen molecular chain was largely cut. On the other hand, for the 2nd and 3rd layers of the said sheet, the terminal amino group concentrations were found to have decreased in order, and for the 4th layer and onward, the concentrations were shown to have decreased down to 0.22 nmol/ml, which were nearly equal to the level before the exposure. Although the bands of three molecular chains of &alpha-, β-, and γ-chains in all samples after exposure to UV-rays were disappeared, it was also shown that the more a layer was inside, the less the collagen molecular chain was not dissolved. In addition, when the collagen artificial skin covered with a UV-blocking, zinc oxide-added film was exposed to the sunlight, it was demonstrated that the more the addition of zinc oxide in the film increased, the lower the terminal amino group concentration in the extracts from the exposed, collagen artificial skin was observed. At the time when the added quantity of zinc oxide reached 0.40v%, the concentration was maintained almost at the same level as observed prior to the exposure. Also in comparison with UV-protecting agents, it was shown that the film added with an organic compound acting as a UV-absorbing agent reduced most the damages sustained by UV-rays. As described above, the evaluation method using a collagen artificial skin could be effectively employed in outdoor exposure for examining the protective effect of UV-cut materials to the skin against the UV-rays in the Antarctica. [ABSTRACT FROM AUTHOR]

For preventing damages on the skin by UV-rays, various UV-cut materials have been developed. In the present study, the authors made a collagen sheet (hereafter "collagen artificial skin") to imitate the human skin on an experimental basis and, after having covered this sheet with a film added with various UV-protecting agents, subjected it artificially to UV-irradiation. Under such condition, the skin protective effect of each kind of UV-cut materials against UV rays was examined, and the various methods to evaluate damages on the sheet caused by UV rays were also reviewed. First, the UV-rays were applied to the collagen artificial skin that was not covered with the film, and the extracts were obtained from the sheet after irradiation. The analysis of the extracts by electrophoresis revealed that the bands of three molecular chains such as α-, β, and γ-chains of polypeptides were disappeared under UV-irradiation even only for 15 minutes (UV-Energy : 7.58x104J/m², at 310nm). When the irradiation time reached 25 hours (UV-Energy: 7.58x106J/m², at 310nm), hydrolysates from the collagen in the sheet started to appear, and when the irradiation time exceeded further 200 hours (UV-Energy: 6.06x1077J/m², at 310nm), a considerable amount of hydrolysates was recognized. Also it was found that the longer the irradiation time of UV-rays, the higher the concentration of the terminal amino group in the extracts from the collagen was observed. Then, the UV-rays were irradiated to the collagen artificial skin added with various UV-scattering agents. As a result, addition of UV-scattering agents to the film of any of the materials reduced scission of the collagen molecular chains caused by UV-rays, resulting in reduction of the increase of the terminal amino group concentration. From the above results, it was suggested that the use of a collagen artificial skin was one of the effective measures as a method for examining the protective effect against UV-rays. [ABSTRACT FROM AUTHOR]