Glucocorticoid hormones inhibit DNA synthesis and enhance interferon production in human lymphoid cell line

Although buffy coat leukocytes have been the prime source of human interferon, cells of the Burkitt lymphoma line Namalwa are increasingly used for the large scale production of interferon. On induction with Sendai virus or Newcastle disease virus, Namalwa cells produce a substantial quantity of interferon which contains predominantly the leukocyte antigenic species and minor amounts of fibroblast-type interferon. We have recently demonstrated that inducers of erythropoietic differentiation in Friend cells are able to enhance interferon synthesis in Namalwa cells when added to cultures larger than or equal to 24 h before interferon induction by Sendai virus. The most potent compounds, n-butyrate, stimulated interferon production about 30-fold and has also been independelty described by others. All active compounds inhibited DNA synthesis in Namalwa cells and the extent of inhibition apparently paralleled the stimulatory potency of the respective compound. Induction of differentiation of Friend cells can be antagonised by various steroid hormones, which by themselves have no measurable effects on these cells. In contrast, we report here that glucocorticoid hormones inhibit DNA synthesis in Namalwa cells and augment Sendai virus-induced interferon synthesis.     

Two-dimensional gel electrophoresis analysis of the proteomes expressed in the human hepatoma cell line BEL-7404 and normal liver cell line L-02

Proteome analysis technology has been used extensively in conducting discovery research of biology and has become one of the most essential technologies in functional genomics. The proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 have been separated by high resolution two-dimensional gel electrophoresis (2-DE) with immobilized pH gradient isoelectric focusing (IPG-IEF) in the first dimension and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in the second dimension (IPG-DALT). The resulting images have been analyzed using 2-D analysis software. Quantitative analysis reveals that 7 protein spots are detected only in hepatoma BEL-7404 cells, 14 only in L-02 cells, and 78 protein spots show significant fluctuation in quantity in both cell lines (P< 0.01). These protein spots have been displayed on a proteome differential expression map. Analysis for the reproducibility of 2-DE indicates that the positional variability in the IEF dimension is 0.73 mm, while the variability in the SDS-PAGE dimension is 0.44 mm, and the quantitative variability is 17.6%–19.2%. These results suggest that the reproducibility of 2-DE has been suitable for the study of differential expression of proteomes. Proteome differential expression maps can be useful tools for disease diagnosis, drug-target validation analysis and biological process elucidation.     

UV light-induced immunoglobulin heavy-chain class switch in a human lymphoblastoid cell line

During attempts to select nonsecretory variants from 0.467.3, and Epstein-Barr virus-transformed human lymphoblastoid cell line that secretes small amounts of IgM lambda, we exposed the cells to UV light. Cells that survived the irradiation were subcultured and their supernatants were screened for immunoglobulin production by an enzyme-linked immunosorbent assay (ELISA). Although stable nonsecretory variants were not isolated, we report here that an immunoglobulin class switch occurred in the UV-treated cell population. All survivors were found to produce large quantities of IgG lambda. Some cell cultures also produced the original IgM lambda. The UV-light-induced class switch was regularly reproducible with this target cell line.     

Biosynthesis of the major human red cell sialoglycoprotein, glycophorin A, in a continuous cell line

During biosynthesis of glycophorin A in K562 cells a precursor is rapidly transferred through the endoplasmic reticulum membrane with the COOH-terminal remaining in the cytoplasm. This is glycosylated within the cell and appears at the cell surface after about 30 min. The biosynthetic pathway resembles that described for viral membrane glycoproteins.     

Molecular cloning of a new transforming gene from a chemically transformed human cell line

Molecular cloning of the transforming gene from a chemically transformed human osteosarcoma-derived cell line enables the gene to be mapped to chromosome 7 (7p11.4-7qter) and by this criterion and by direct hybridization to be shown to be unrelated to known oncogenes.     

Expression of a transfected human c-myc oncogene inhibits differentiation of a mouse erythroleukaemia cell line

The Friend-virus-derived mouse erythroleukaemia (MEL) cell lines represent transformed early erythroid precursors that can be induced to differentiate into more mature erythroid cells by a variety of agents including dimethyl sulphoxide (DMSO). There is a latent period of 12 hours after inducer is added, when 80-90% of the cells become irreversibly committed to the differentiation programme, undergoing several rounds of cell division before permanently ceasing to replicate. After DMSO induction, a biphasic decline in steady-state levels of c-myc and c-myb messenger RNAs occurs. Following the initial decrease in c-myc mRNA expression, the subsequent increase occurs in, and is restricted to, the G1 phase of the cell cycle. We sought to determine whether the down-regulation is a necessary step in chemically induced differentiation. Experiments reported here indicate that expression in MEL cells of a transfected human c-myc gene inhibits the terminal differentiation process.     

羟基磷灰石纳米线的可控制备

用P2O5和Ca(NO3)2作为前驱体溶液，将溶胶—凝胶法与氧化铝模板(AAO)技术相结合，大面积制备出结构均匀、晶相一致、彼此平行且高度有序的羟基磷灰石(HAP)纳米线．结果表明，通过控制制备AAO模板的条件，可达到控制HAP形貌的目的．     

Nucleostemin siRNA对结肠癌细胞株HT-29细胞凋亡的影响

利用RNA干扰技术沉默结肠癌细胞株HT-29细胞中Nucleostemin(NS)基因的表达,并分析其对HT-29细胞凋亡的影响,进一步利用半定量RT-PCR和Western blotting技术检测细胞凋亡相关基因caspase-3/9 mRNAs和蛋白的表达.结果表明,NS基因的沉默能明显提高caspase-3/9的活性(P0.05),并诱导细胞发生凋亡,此外,HT-29细胞中NS基因沉默后,caspase-3/9mRNAs和蛋白的表达均明显升高,提示NS基因沉默介导的细胞凋亡与caspase-3/9基因表达的升高密切相关.