[Influence of selenium-rich rice on transformation of umbilical blood B lymphocytes by Epstein-Barr virus and Epstein-Barr virus early antigen expression].

BACKGROUND & OBJECTIVE: Selenium (Se), an antioxidant, is an essential trace element to human body. It can be used as an anti-aging agent and a tumor cell proliferation inhibitor. To further investigate the effect of selenium in cancer prevention, the authors observed the influence of Se-rich rice extract on the transformation of umbilical blood B lymphocytes stimulated by Epstein-Barr virus (EBV) and expression of EBV early antigen(EBV-EA) in Raji cells. METHODS: (1) Se-rich rice and general rice extract (dilution of 1:4 or 1:8) were added to mixture of EBV, and then umbilical blood mononuclear cells were added. Lymphoblasts transformation test was then performed. The inhibition rate of B lymphocytes transformation was calculated. (2) Raji cells stimulated by butyrate and croton oil were incubated with Se-rich rice extract. The EBV-EA positive expression rate and the inhibition rate were counted using indirect immunological flurescence method. RESULTS: The transformation of umbilical blood B lymphocytes stimulated by EBV was significantly inhibited by Se-rich rice extract at a concentration of 0.11 g/ml (1:8 diluted). The inhibition rate was 83.4% (P < 0.01), which was significantly higher than that of the control rice (63.1%) (P < 0.05). Se-rich rice extract showed significant inhibition on EBV-EA in Raji cells. As the extract concentration was at 0.016 microgram/ml, 0.078 g/ml, and 0.388 microgram/ml, the inhibition rates of EA were 2.85%, 12.88%, and 20.75%, respectively. CONCLUSION: The transformation of umbilical blood B lymphocytes stimulated by EB virus and expression of EBV-EA in Raji cells may be significantly inhibited by Se-rich rice extract, suggesting that Se-rich rice can be used for preventing nasopharyngeal carcinoma.

[A method to detect gene transfection efficacy by flow cytometry].

BACKGROUND & OBJECTIVE: Analysis of gene transfer and expression is conventionally inferred from the percentage of positive cells expressing reporter gene in total cells, referred as transfection rate, by investigators counting under a microscope or fluoroscope, which was called as manual counting. But in many cases, it is not accurate and easily influenced by the subjectivity of observer. This study was designed to seek a convenient method to assess objectively and accurately the efficacy of gene transfer and expression. METHODS: Hepatocellular carcinoma(HCC) HepG2 cells were infected with a recombinant adenovirus expressing green fluorescent protein(AdCMV/GFP) at a series of multiplicities of infection(MOIs). 24 h later, the transfection rates were assessed by manual counting under fluorescent microscope. Meanwhile, besides transfection rates, fluorescent indices(FIs) which indicated the efficiency of gene transfer and expression were analyzed by flow cytometry (FCM). Transfection efficiencies of AdCMV/GFP to HCC Hep3B, Bel7402, SMMC7721 cells and nasopharyngeal carcinoma CNE-2 cells were also tested by FCM. RESULTS: Although transfection rates by FCM were slightly higher than that by manual counting, both were logarithmic correlative with vector doses. The stirring was that FIs by FCM showed compellent linear correlation with vector doses (r = 0.9984, P < 0.001). The efficiency of gene transfer in other cells by FCM were similar to that in HepG2. CONCLUSION: The efficiency of gene transfer and expression in mammalian cells can be easily analyzed by flow cytometry, which is more sensitive, objective, and accurate than manual counting, especially in assessing the efficiency of multiple gene transfer (multi-copies per cell) and expression.