Osmotaxis in Escherichia coli.
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Cell Movement↗
Biomedical subjects
Y Qi
Publications and source records attributed to Y Qi.
Tumorigenicity testing of primate cell lines in nude mice, muscle organ culture and for colony formation in soft agarose.
Primate neoplastic and finite cell lines were tested in one in vivo and two in vitro test systems: adult nude mice, muscle organ culture (MOC) and soft agarose (SA). Comparison of the sensitivity of the systems indicated that nude mice were inferior to either in vitro system: WI-38 VA13 (an SV40 transformed cell line) did not cause tumours in these animals yet it behaved as if it were neoplastic in MOC and formed colonies in SA. There was complete correlation between results obtained in MOC and SA. All cell lines which produced tumors in vivo were positive in both in vitro test systems. None of the lines which showed normal patterns in MOC and in SA was tumorigenic in nude mice. Since testing in vitro is simpler, faster, and is thought to be reliable, we recommend SA followed by MOC as the initial assays for determining tumorigenicity of cells.
Animals↗
Radiation therapy of seminoma of the testis.
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Abdominal Neoplasms↗
Divergent effects of leptin in mice susceptible or resistant to obesity.
Consumption of a high-fat diet decreases hypothalamic neuropeptide Y (NPY) and increases proopiomelanocortin (POMC) and brown adipose uncoupling protein (UCP)-1 mRNA in obesity-resistant SWR/J but not obesity-prone C57Bl/6J mice. Although leptin was elevated in both strains in response to a high-fat diet, its role in the development of diet-induced obesity has remained unclear since insulin and other factors that affect similar tissue targets are altered. Thus, we administered recombinant leptin by subcutaneous infusion to chow-fed mice to mimic the changes in plasma leptin across its broad physiologic range. We observed strain differences in responsiveness to reduced and elevated leptin levels. A reduction in leptin during fasting evoked a greater response in C57Bl/6J mice by decreasing energy expenditure and thyroxin, increasing corticosterone and stimulating food intake and weight gain during refeeding. However, C57Bl/6J mice were less responsive to an increase in leptin in the fed state. Conversely, the leptin-mediated response to fasting was blunted in SWR/J mice, whereas an increase in leptin profoundly reduced food intake and body weight in SWR/J mice fed ad libitum. Sensitivity to fasting in C57Bl/6J mice was associated with higher hypothalamic NPY mRNA and reduced POMC and UCP-1 mRNA expression, while the robust response to high leptin levels in SWR/J mice was associated with suppression of NPY mRNA. These results indicate that differences in leptin responsiveness between strains might occur centrally or peripherally, leading to alteration in the patterns of food intake, thermogenesis and energy storage.
Animals↗
Comparison of parenteral nutrition supplemented with L-glutamine or glutamine dipeptides.
Although glutamine is an important fuel used by the intestinal mucosa and other visceral organs, it is not present in any commercially available parenteral amino acid solution. To compare the effects of L-glutamine with glutamine dipeptides, we studied the effects of each in 8 dogs and 60 Wistar rats. In the dog study, three amino acid solutions were compared: standard commercial amino acid solution (control), alanine-glutamine dipeptide-enriched solution (glutamine 3.4%), and glycine-glutamine dipeptide-enriched solution (glutamine 3.6%). Arterial and venous samples were collected to compare the effects of the three solutions on skeletal muscle amino acid exchange. In the rat study, two studies were undertaken: group 1 rats underwent only central venous catheterization; group 2 rats underwent central venous catheterization and a 50% intestinal resection. Within each group, three different solutions were infused: standard amino acid solution (control), glutamine-enriched (1.5% glutamine) solution, or glutamine dipeptide-enriched (1% glutamine) solution. After 7 days of parenteral nutrition, samples of gut, blood, and muscle were collected for determination of mucosal thickness, villus area, serum amino acid profile, liver and renal function tests, and muscle composition. When glutamine or glutamine-dipeptide solutions were administered, the dogs showed increasing serum glutamine concentrations and enhanced glutamine uptake across the hind leg muscle. Similarly, both groups of rats demonstrated significant differences in serum glutamine levels, nitrogen balance, intestinal mucosa thickness, and villus area. We conclude that both glutamine and glutamine-dipeptide infusions increase serum glutamine concentrations and result in regional tissue effects. Both exerted similar metabolic effects with no apparent complications.
Amino Acids↗
Comparison of the biological activities of human immunodeficiency virus 1 P24 and GP41 expressed in Spodoptera frugiperda cells by use of bac-to-bac system.
Recombinant transposing plasmids pFH24 and pFH41 were constructed by cloning the human immunodeficiency virus 1 (HIV-1) p24 and gp41 genes, respectively, into the transposing vector pFastBacHTa. Recombinant bacmids rBH24 and rBH41 were obtained by transposing pPolh/p24 and pPolh/gp41 expression cassettes from recombinant plasmids pFH24 and pFH41, respectively. Recombinant viruses rAcH24 and rAcH41 were generated by transfection of the Spodoptera frugiperda (Sf9) cells with the DNAs of plasmids rBH24 and rBH41, respectively. Analysis of the expressed p24 or gp41 proteins with an antiserum to HIV-1 (HIV-1 antiserum) by an enzyme-linked immunosorbent assay (ELISA) and dot blot assay showed high biological activity of these proteins; p24 was more active than gp41. Also a Western blot analysis showed stronger bands for p24 than for gp41. The high reactivities of p24 and gp41 with the HIV-1 antiserum suggest that these proteins could also be used as specific standard antigens in HIV-1 diagnostics.
Animals↗
Nucleocapsid protemn gene of Chinese isolate of Bombyx mori nucleopolyhedrovirus.
The nucleocapsid protein gene (vp39) of a Chinese isolate of Bombyx mori nucleopolyhedrovirus (BmNPV-Ch), namely an open reading frame (ORF) of 1050 bp that codes for a polypeptide of 39 K (VP39) consisting of 350 amino acids was sequenced. The homology of the nucleotide (nt) and amino acid sequences of vp39 and VP39, respectively, of BmNPV-Ch and a Japanese isolate of BmNPV (BmNPV-Ja) were found to be 97.5% and 97.1%, respectively. The BmNPV-Ch vp39 is nine nucleotides longer than that of BmNPV-Ja vp39 due to insertion of CGA at nt 625 and GTCGGC at nt 985 910. There are differences in 17 nucleotides causing a few substitutions of amino acids which slightly modify the secondary structure of BmNPV-Ch. It indicates that the main part of the secondary structure of VP39 is a folded structure containing high proportion of beta-sheet and beta-turn units. A dot blot hybridization analysis revealed the existence of a homologous transcript of BmNPV-Ch vp39 in Sf9 cells infected with Autographa californica multiple nucleocapsid nucleopolyhedrovirus (AcMNPV).
Amino Acid Sequence↗
Inhibition of established tumor growth in syngeneic mice by local inoculation of engineered mouse myeloma cells secreting a recombinant fusion protein RM4/TNF.
Mouse myeloma cell line VKCK/RM4-TNF secreting the recombinant fusion protein RM4/TNF was used to study the relationship between tumor necrosis factor (TNF) secretion of tumor cells and its tumorigenicity, and to study the potential mechanisms responsible for the antitumor immune response. To evaluate tumorigenicity, 5 x 10(5) viable TNF-secreting VKCK/RM4-TNF and non-TNF-secreting VKCK tumor cells were subcutaneously injected into BALB/c mice. Tumor progression or regression was evaluated 2 weeks after tumor inoculation. Our animal studies showed that RM4/TNF secretion by VKCK/RM4-TNF tumor cells curtailed its tumorigenicity in BALB/c mice and induced a long-term, protective immune response against a subsequent challenge of the parental VKCK tumor cells. Our animal studies in T-cell subset-depleted BALB/c mice and in T-cell-deficient nude mice demonstrated that both CD4+ and CD8+ T cells play a major role in the reduction of tumorigenicity. In addition, our results further showed that local inoculation of irradiated VKCK/RM4-TNF cells secreting TNF was able to significantly inhibit the established VKCK tumors in syngeneic mice. This study thus highlights the potential utility of engineered tumor cells secreting RM4/TNF in cancer gene therapy.
Animals↗