Polymer blends were fabricated with poly(lactic acid) (PLA) with better mechanical properties and poly(butylene succinate) (PBSU) with better biodegradable properties to clarify the effect of the blending ratio on the biodegradable and mechanical properties of the blends. The specimens were heat treated to improve the reduction in stiffness due to blending. Hydrolysis and soil burial tests up to 16 weeks were conducted to investigate the biodegradation properties. Young's modulus increased with increasing contents of PLA, whereas tensile strength is lowest in the PLA/PBSU (50/50) polymer blend before biodegradation because of the immiscibility of PLA and PBSU. Young's modulus kept constant up 16 weeks both in the hydrolysis and the soil burial tests. On the other hand, tensile strength decreased remarkably in the hydrolysis tests. The observation results of the specimen surface and the fracture surface indicate that the surface and bulk degradation occur in hydrolysis and soil burial tests, respectively

The effects of various adjuvants on the cytotoxicity of mitomycin C (MMC) were studied in L1210 mouse leukemia cells. Adjuvants examined in this study were sodium glycocholate (Na-GC), sodium deoxycholate (Na-DC), O-n-dodecyl-beta-D-maltopyranoside (LM), and sodium salicylate. Among various additives, bile salts such as Na-GC and Na-DC were the most effective for increasing the cytotoxicity of MMC against L1210 cells. A dose-dependent increase in cytotoxic effect of MMC was observed in the presence of these bile salts. To elucidate a possible mechanism for enhancing the cytotoxic effect of MMC by the bile salts, the cellular uptake of MMC with or without Na-GC was examined using L1210 cells. The cellular concentration of MMC was determined by a reversed-phase HPLC. When Na-GC was coadministered with MMC, the uptake of MMC into L1210 cells was significantly enhanced as compared with MMC alone. Furthermore, the membrane fluidity of L1210 cells, as determined by fluorescence polarization, was increased in the presence of Na-GC. These results suggested that the enhancement of cytotoxicity of MMC by the addition of Na-GC could be attributed to the increasing cellular uptake of MMC due to the increasing membrane fluidity of L1210 cells.

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