Oncogenic ras genes relate to the development of human cancers. In this study, we used a plasmid-mediated short-hairpin RNA (shRNA) targeting N-ras gene to combine with clinical drug vincristine (VCR) for the treatment of human hepatoma cells. Our results showed that anti-N-Ras shRNA expression vector (pCSH1-shNR) knocked down the target mRNA and protein. Higher efficacy on growth inhibition was observed when pCSH1-shNR was combined with VCR. This synergistic effect was associated with abrogation of VCR-induced overexpressions of P-glycoprotein and multidrug resistance-associated protein 1 by pCSH1-shNR through downregulations of N-Ras and total Ras. Western blot analysis showed that pCSH1-shNR-induced downregulations of N-Ras and total Ras were potentiated by VCR. Following Ras downregulation, phosphorylations of ERK1/2 and Akt were dramatically inhibited by combinatory treatment. The data showed that pCSH1-shNR-induced inhibition of nuclear factor-kB was enhanced by VCR. In addition, the combination of pCSH1-shNR and VCR synergistically inhibited the growth of human hepatoma HepG2 in vivo. Our findings suggested that combination of gene-specific therapeutics and appropriate chemotherapeutic agents might be a promising approach for the treatment of human hepatocellular carcinoma.

Non-ferrous debris in oil sample provide important information about the wear condition of a wear couple containing non-ferrous metal components. In order to collect wear debris of non-ferrous metal material more effectively and deposit them on a ferrogram in a stable depositing ratio, the method of employing magnetic fluid as a magnetization agent to collect non-ferrous wear debris in ferrography was attempted. Magnetic fluid constituting Fe 3 O 4 magnetic particles was prepared using a precipitation reaction. Tetrachloroethylene was used as a carrier liquid to ensure that magnetic fluid can be easily mixed with lubricant oil sample. Oleic acid was used as a surfactant, which enables magnetic particles to adhere to the surface of non-ferrous wear debris. Then the non-ferrous wear debris was magnetized and deposited on a ferrogram in a stable depositing ratio. Copper debris was chosen as an example of non-ferrous debris to illustrate the magnetization effect of the magnetic fluid. With the help of magnetic fluid, the ferrographic analyst will achieve the operating condition of the machine more accurately.