Enhancement of cell growth by intracellularly expressed herpes simplex virus thymidine kinase

A recombinant cell line (NIH3T3:pLtkSN) was made by infecting parental cells (NIH3T3) with a recombinant retrovirus (pLtkSN) encoding herpes simplex virus thymidine kinase (HSVtk) gene. The cells expressing HSVtk (NIH3T3:pLtkSN) grew 2.3 times more than the parental cells (NIH3T3) in Dulbecco's Modified Eagles Media containing 10% (v/v) horse serum. The NIH3T3:pLtkSN cells also showed a significant enhancement in the maximal cell concentration and the specific growth rate even at 2.5% serum concentration. The specific O2 uptake rate of NIH3T3 was 2.1 times greater than that of NIH3T3:pLtkSN. Under both O2-limited and O2-unlimited conditions, it appears that HSVtk plays an important role in enhancing the growth characteristics of animal cells.     

Inhibitory Effect of Glycerin on Vibrio parahaemolyticus and Salmonella

In a study of the effect of glycerin in transport media on Vibrio parahaemolyticus and Salmonella, it was found that a concentration of 30% glycerin was highly inhibitory for V. parahaemolyticus and to a lesser degree for Salmonella. The incorporation of peptone or human feces in media did not reduce the inhibitory effect of glycerin. In media with 15% glycerin, viable counts of V. parahaemolyticus and Salmonella increased after 24 hr of incubation both in the presence and absence of feces. Due to the concurrent increase in the total bacterial count in the media containing feces, no enrichment effect was noted.     

Stable ester conjugate between the Saccharomyces cerevisiae RAD6 protein and ubiquitin has no biological activity.

The RAD6 gene of Saccharomyces cerevisiae, which encodes a ubiquitin-conjugating enzyme, is required for DNA repair, DNA damage-induced mutagenesis and sporulation. To evaluate the biological relevance of the thioester adduct between RAD6 protein and ubiquitin, formed as an obligatory, transient intermediate during ubiquitin conjugation to substrates, we altered cysteine 88 in RAD6 to serine. Esterification with ubiquitin occurs at serine 88 in the mutant protein, but conjugation of ubiquitin to the test substrate histone H2A is inactivated. Phenotypically, strains harboring the rad6 Ser88 allele are indistinguishable from rad6 deletion (rad6 delta) mutant cells. These findings argue against ligation of ubiquitin at cysteine 88 acting as a functional switch of a cryptic biochemical activity in RAD6.     

Selection and proliferation of rapid growing cell lines from embryo derived cell cultures of yew tree (Taxus cuspidata Sieb. et Zucc)

Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14 elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth.     

Association of viral and plasmid DNA with the nuclear matrix during productive infection

The association of simian virus 40 (SV40) DNA or plasmid DNA in subcellular fractions from either infected or transfected cells was examined. In lytically infected cells, approx. 25% of viral specific DNA during the infection cycle was retained in nuclei after washing with low ionic strength buffer and 1% Triton X-100. Viral replicating DNA found in the nuclear matrix was capable of performing limited DNA synthesis by the endogenous DNA polymerase in vitro. Viral DNA synthesized in vitro hybridized preferentially to SV40 Hind-III B and C fragments which are in proximity to the origin of replication. In plasmid-transfected COS-7 cells (SV40-transformed cells), the amount of plasmid DNA found in the nuclear matrix was related to its replication efficiency in cells. More than 80% of the plasmid DNA was tightly associated with subnuclear structures. Little or no plasmid DNA was found in the cytoplasmic fraction. The results suggest that, in extrachromosomal model systems, the association of DNA with nuclear matrix is important for the regulation of DNA replication.     

The formation and characteristics of China's existing system

Conclusion To sum up, the character of China's existing system is basically all-embracing totalitarianism formed by the combination of the old tradition of feudal-despotism and the new tradition of Stalinism. This system is the basic source of all the social evils in China.The ultimate aim of the democratic movement is to transform the old, allembracing totalitarian system and to establish a democratic, free, humane, and rational new system. The present ruling group is the beneficiary and defender of the existing system. The contradictions and conflicts between reformers who want to transform the old system and the hardliners who want to protect the old system formed the crux of the struggle of the 1989 democratic movement. Because the democratic movement lacked preparation in theory, organization, tactics and strategy, and because the ruling group controls the means of dictatorship — especially the army —military force was used to suppress the democratic movement with brutal bloodshed. In order to promote the democratic movement, we should sum up some lessons and experiences. First, we should study in depth the existing system and oppose feudaldespotism and Stalinism through effective propaganda and education. Second, we should arouse the democratic consciousness of the broad masses of the people, uniting with them and the healthy elements inside the Party, government, and army to struggle for the smashing of the old system and the establishment of a new system.Su Shaozhi is former Director of the Institute for the Study of Marxism-Leninism and Mao Zedong Thought, Chinese Academy of Social Sciences, Beijing, and currently Visiting Professor at the Bradley Institute for Democracy and Public Values, Marquette University, Milwaukee, Wisconsin     

Insulin suppresses hepatitis B surface antigen expression in human hepatoma cells

The human hepatoma Hep3B cells contain integrated hepatitis B viral genome and continually secret hepatitis B surface antigen (HBsAg). The production of HBsAg (but not alpha-fetoprotein) was suppressed by addition of low concentrations (0.1-1 nM) of insulin into serum-free medium. In addition, the suppression of HBsAg production by insulin was paralleled with the decrease in HBsAg mRNA abundance. Insulin also cause a rapid rate of disappearance of HBsAg mRNA (t 1/2, 2 h) in Hep3B cells. The Hep3B cells carry specific receptor with high affinity for insulin (Kd = 1.8 nM). The receptor showed an insulin-dependent protein tyrosine kinase activity. The half-maximal insulin concentration for the activation of the receptor kinase was about 5 nM. Only very high concentrations of insulin-like growth factor I and human proinsulin can compete for the insulin receptor binding and suppress HBsAg production, this suggests that insulin may act through its receptor binding to suppress HBsAg expression in human hepatoma Hep3B cells.     

Certain aspects of so-called post cholecystectomy syndrome

The study involved 126 patients with cholelithiasis. Set of biochemical, radiological, endoscopic, and ultrasound examinations was carried out in these patients. Potential coincidence of clinical symptoms and causes of so-called postcholecystectomy syndrome was the purpose of a 1-year follow-up studies. The significance of the results are discussed.