Wettability of chitosan coating solutions on 'Fuji' apple skin in different surfactant concentration (Tween 80: 0, 10, 100, 1000 ppm) was investigated using the Du Nouy ring method and the sessile-drop method. The surface property of 'Fuji' apple skin as a coated solid surface was characterized by the Zisman plot. The critical surface tension of 'Fuji' apple skin was 18.7 dyne/cm. The surface tension of the chitosan coating solution was too high (61.5 dyne/cm) to wet the apple skin. Tween 80 as surfactant in water-borne coatings reduced the surface tension of the coating solution and enhanced its wettability. Surface morphology of the coated film was observed by scanning electron microscope. Surfactant driven autophilicity improved the adhesive force between coating solution and associative apple skin, and decreased the contact angle of coating solution.

SV40 large T antigen, a viral oncoprotein, is known to immortalize human diploid fibroblast by soaking up cellular RB and p53, but its frequency is extremely low. Additional genetic alteration is necessary for single-step immortalization. We attempted to find out what this alteration is by overexpressing cellular signal mediator genes; c-myc and cyclin D frequently amplified in many cancer cells. Overexpression of cyclin D did not affect the immortalization, but, overexpression of c-myc along with T antigen could immortalize normal human diploid fibroblast. Several cellular markers tested during immortalization process showed that p21, a cyclin-dependent kinase inhibitor and a marker of cellular senescence, disappeared in the life span-extended cells by T antigen and in the immortalized cells by c-myc. p21 was, however, elevated in the senescent cells and in the cells of crisis. Interestingly, p16 was upregulated whenever T antigen is overexpressed. Telomerase activity was also activated only in the immortalized cells. These results suggest that overexpression of c-myc contributes to immortalization of human diploid fibroblast by activating telomerase activity and suppressing p21 activity.

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