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Cell growth of rat lens epithelium during galactose-induced cataract formation was examined in the present study using fluorescence cytophotometry or proliferating cell nuclear antigen (PCNA) immunohistochemistry.Six-week old male SpragueDawley rats were divided into 4 dietary groups according to galactose supplementation of the diet: 5%, 10%, 15% and 25% galactose diet groups. Whole-mount preparations of rat lens epithelium were prepared.The nuclear content of epithelial cells was measured using fluorescence cytophotometry, and cells undergoing DNA synthesis (PCNA labeled cells) were detected using the PCNA immunohistochemical staining method.The results of fluorescence cytophotometry showed that cells containing tetraploid nuclei (4C cells) gradually increased in number. In the 5% galactose diet fed rats, the number of 4C cells peaked on the 9th day after the start of dietary galactose supplementation, the 7th day in the 10% galactose diet fed rats and on the 5th day in the 15% and 25% galactose diet fed rats. On each day that 4C cells peaked, a large number of PCNA labeled cells were observed in the central zone of the epithelial cell layer. These results suggest that growth stimulation of lens epithelial cells depends upon the concentration of galactose in the diet and precedes changes in lens fiber.

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Aiming to develop a high performance fiber-reinforced natural rubber (NR), a special technique using electron beam (EB) irradiation-induced graft-polymerization was applied to high-strength polyethylene terephthalate (PET) fibers. Although PET is chemically robust, allyl methacrylate (AMA) could be graft-polymerized onto the PET fiber surface with this special technique. The composite of NR and grafted-PET fibers indicated a linear increase in the initial modulus with the fiber content. At the fiber content of 10%, the initial modulus was improved about five times with respect to that of the pure NR, whereas the breaking strength increased by ca. 35% and the breaking strain decreased by ca. 45%. The fiberreinforced rubber with a good performance was obtained in the system of NR and grafted-PET fibers.