Objective:To study the antimicrobial effect of polymethylmethacrylate (PMMA) denture base with silver-containing antimicrobial agents of nanometer level against Streptococcus mutans and Candida albicans in vitro. Methods:Minimum inhibitory concentration (MIC) of the silver-containing antimicrobial agent against S. mutans and C. albicans was examined. According to the MIC, 4 concentrations(1,2,5 and 10 mg/ml) of the agent were selected for the preparation of antimicrobial PMMA resin base. Then, the antimicrobial effect of the resin base was examined by in vitro bacteria culture and the most probable number(MPN) counting. Results:The MICs of the agent against S. mutans and C. albicans were 0.1 mg/ml and 1 mg/ml respectively. With the agent at 1, 2, 5 and 10 mg/ml, the inhibition ratios of the base against S.mutans were 67.4%,71.3%,99.0 and 99.5% respectively, that against C. albicans were 25.8%,54.8%,90.3% and 93.0%, respectively. Conclusion:The polymethylmethacrylate resin base with silver-containing antimicrobial agent of nanometer level at 5 mg/ml has ideal antimicrobial activity against S. mutans and C. albicans.

Objective: To study the durability of the antimicrobial effect of polymethylmethacrylate (PMMA) denture base containing silver-supported antimicrobial agents of nanometer level against Streptococcus mutans and Candida albicans in vitro. Methods:The antimicrobial PMMA resin bases with the antimicrobial agent STR-1 at concentration of 5 mg/ml were prepared. Then the samples were divided into 4 groups: positive control group, the group immersed in distilled water at 57 ℃ for 14 days, the group irradiated by ultraviolet for 8 hours, and the group irradiated by ultraviolet for 8 hours after immersed in distilled water at 57 ℃ for 14 days. Then the inhibition ratios of the 4 groups against Streptococcus mutans and Candida albicans in vitro were tested. Results:The inhibition ratios of the 4 groups against Streptococcus mutans were 99%, 96%, 98%, and 90% in turn. The inhibition ratios of the 4 groups against Candida albicans were 91%, 82%, 90%, and 80% respectively. Conclusion: The antimicrobial effect of PMMA denture base containing silver-supported antimicrobial agents STR-1 of nanometer level at concentration of 5 mg/ml against Streptococcus mutans and Candida albicans in vitro is durable.

Objective: To evaluate the biocompatibility of polymethylmethacrylate(PMMA) denture base resin containing silver-supported antimicrobial agent STR-1 of nanometer level in vitro. Methods: According to the national standards for biological evaluation of dental materials, the cytotoxicity of denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was examined by molecular filtrating method, and the hemolysis of STR-1, denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was also surveyed. Results: The control denture base resin without containing STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were not cytotoxic to L929 cells. Two hours and 24 hours after cell culturing, the filter membranes of the control and experimental groups were stained evenly with blue color. The staining intensity was not decreased and the fading areas were 0 mm~2 during the culturing. The cytotoxicity grades were 0. The hemolysis rates of the antimicrobial agent STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were 1.7%, 3.5% and 3.7% respectively. They were less than the national guild standard 5% which represent no hemolysis. Conclusion: The PMMA denture base resins containing silver-supported antimicrobial agents STR-1 of nanometer level at concentrations of 5 g/L and 10 g/L exhibit good biocompatibility.

Human acute leukemia (AL) is a clonal malignancy with abnormal hematopoietic stem cells. Clinically, AL is very difficult to cure due to its sudden onset and short course of disease progression. Previous studies have shown that eukaryotic initiation factor 4B (eIF4B) plays a critical role in the development of chronic leukemia. However, the involvement of eIF4B in human acute leukemia is still largely unknown. Therefore, we studied eIF4B function and its regulatory mechanism in human acute leukemia. We found that phosphorylation levels of eIF4B in acute leukemia cells were significantly reduced in response to treatment with either LY294002 (PI3K inhibitor), AKTi (AKT inhibitor) or SMI-4A (Pim inhibitor). Co-treatment with inhibitors targeting JAK/STAT5/Pim and PI3K/AKT/mTOR signaling dramatically promoted apoptosis of acute leukemia cells by downregulating eIF4B phosphorylation. Furthermore, in vitro and in vivo functional experiments showed that eIF4B played an important anti-apoptosis role in the acute leukemia cells by regulating the expression of anti-apoptotic proteins Bcl-2 and Bcl-XL. In contrast, silencing eIF4B inhibited the growth of acute leukemia cells as engrafted tumors in nude mice. Taken together, our results indicate the synergistic role of JAK/STAT5/Pim and PI3K/AKT/mTOR signaling pathways in regulating eIF4B phosphorylation in acute leukemia, and highlight eIF4B as a candidate therapeutic target for treatment of acute leukemia.
Animals ; Apoptosis ; Cell Line, Tumor ; Leukemia ; Mice ; Mice, Nude ; Phosphatidylinositol 3-Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; STAT5 Transcription Factor/metabolism*