Arg-Gly-Asp (RGD) sequence conjugated in a synthetic copolymer bearing a sugar moiety for improved culture of parenchymal cells (hepatocytes)

A copolymer, including a Gly-Arg-Gly-Asp-Ser (GRGDS) sequence and sugar moieties, was synthesized for the culturing of parenchymal cells (hepatocytes). Hepatocyte cells attached to poly[N-p-vinylbenzyl-d-maltonamide-co-6-(p-vinylbenzamido)-hexanoic acid-GRGDS] [poly(VMA-co-VBRGD)]-coated dishes grew approximately 60% better than on other polymer-coated surface for 12 h. Also, about 80% greater albumin secretion (0.38 pg ml^–1) and about 70% greater urea synthesis (0.495 pg ml^–1) from hepatocytes were produced in this matrix as compared with unstimulated cells. The behaviour of hepatocytes on poly(VMA-co-VBGRGDS)-coated dishes was not distinct from those attached to a collagen. The conjugation of the adhesion molecules of the RGD peptide in the poly(VMA-co-VBGRGDS) copolymer therefore specifically interacts with integrin families on the hepatocyte cell membrane.     

A Yersinia pseudotuberculosis protein which cross-reacts with HLA-B27

The most-debated question in the investigation of the spondyloarthropathies has been whether there is molecular mimicry between host HLA-B27 antigens and the arthritis-causing pathogens. We have generated a monoclonal anti-HLA-B27 antibody in our laboratory and have used a radioimmunoassay to screen a panel of bacterial species. Two strains of Yersinia pseudotuberculosis were found to be highly reactive. The cross-reactive Yersinia component was identified by Western blot to be a 19,000 component. A preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis chromatography apparatus was constructed to isolate milligram quantities of this component. To verify that the component carried the HLA-B27-specific epitope, rabbits were hyperimmunized with the purified materials. Affinity-purified antibodies from one of the immunized rabbits indeed carried anti-HLA-B27 activity. Last, antibodies generated against synthetic peptides derived from the HLA-B27.1 amino acid sequence were tested against the Yersinia component. Positive reactivity was found with antibodies generated against a peptide spanning residues 69-83 of the HLA-B27.1 protein. Since this resides in the segment responsible for the allotypic specificity of the antigen, these experiments establish the presence of molecular mimicry to a high degree of confidence.     

Enhanced production of laccase in Trametes vesicolor by the addition of ethanol

In a medium containing 40 g ethanol l^–1, laccase production by Trametes versicolor was 2.6 unit per ml of the supernatant, which was over 20 times higher than that without ethanol. Laccase activity with ethanol was quite comparable to that with the well-known inducers such as veratryl alcohol, xylidine and guaiacol. With other white-rot fungi, Coriolus hirsutus and Grifola frondosa, ethanol had a similar stimulatory effect on laccase production.     

Extracellular secretion of levansucrase from Zymomonas mobilis in Escherichia coli

Secretion of levansucrase from Zymomonas mobilis in Escherichiacoli by glycine supplement was investigated. A significant amount of levansucrase (about 25% of total activity) was found in intact whole-cells. Cell fractionation experiments showed that levansucrase was found both in the periplasmic space and in the cytoplasmic fraction of E. coli. None or only trace amounts of levansucrase was detected in the extracellular culture broth at 24 h of cultivation and it accrued with the increasing concentration of glycine in the culture medium and duration of the culture period. Optimal glycine concentration for the maximum secretion of levansucrase was in the range of 0.8-1%, in which approximately 20-50% of levansucrase was released into the extracellular fraction at 24 h of cultivation, although glycine retarded the bacterial growth.     

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.     

Murine Cytomegalovirus m02 Gene Family Protects against Natural Killer Cell-Mediated Immune Surveillance

The murine cytomegalovirus m02 gene family encodes putative type I membrane glycoproteins named m02 through m16. A subset of these genes were fused to an epitope tag and cloned into an expression vector. In transfected and murine cytomegalovirus-infected cells, m02, m04, m05, m06, m07, m09, m10, and m12 localized to cytoplasmic structures near the nucleus, whereas m08 and m13 localized to a filamentous structure surrounding the nucleus. Substitution mutants lacking the m02 gene (SMsubm02) or the entire m02 gene family (SMsubm02-16) grew like their wild-type parent in cultured cells. However, whereas SMsubm02 was as pathogenic as the wild-type virus, SMsubm02-16 was markedly less virulent. SMsubm02-16 produced less infectious virus in most organs compared to wild-type virus in BALB/c and C57BL/6J mice, but it replicated to wild-type levels in the organs of immunodeficient gamma(c)/Rag2 mice, lacking multiple cell types including natural killer cells, and in C57BL/6J mice depleted of natural killer cells. These results argue that one or more members of the m02 gene family antagonize natural killer cell-mediated immune surveillance.     

Artifacts following gold staining of Western-blotted membranes

Protein samples were separated by sodium dodecyl-sulfate-polyacrylamide gel electrophoresis, electrophoretically transferred to nitrocellulose membranes, and stained with colloidal gold. Three artifact bands appeared demonstrating apparent molecular weights of 58,000, 63,000, and 65,000. The appearance of these bands was due to oxidized dithiothreitol used to denature the proteins prior to electrophoresis. The appearance of the artifact bands could be avoided by the addition of excess iodoacetamide to the denatured protein sample and by limiting staining time to 1.5 h at 13 V/cm.