Biomedical subjects

P Tian

Publications and source records attributed to P Tian.

23 records · Page 2Linked to original sources

PubMed1994

The nonstructural glycoprotein of rotavirus affects intracellular calcium levels.

Rotavirus infection of monkey kidney cells has been reported to result in a significant increase in the concentration of intracellular calcium. This increase in intracellular calcium was associated with viral protein synthesis and cytopathic effects in infected cells. We tested the effect of individual rotavirus proteins on intracellular calcium concentrations in insect Spodoptera frugiperda (Sf9) cells. Insect cells were infected with wild-type baculovirus or baculovirus recombinants that contained an individual rotavirus gene. The cells were harvested at different times postinfection, and the intracellular calcium concentration was measured by using fura-2 as a fluorescent calcium indicator. We found that the concentration of intracellular calcium was increased nearly fivefold in infected Sf9 cells that expressed the nonstructural glycoprotein (NSP4) of group A rotavirus, and this increase in intracellular calcium concentration coincided with NSP4 expression. A similar result was observed in insect cells expressing NSP4 from a group B rotavirus, suggesting the conservation of this function among rotavirus groups. Expression of the other 10 rotavirus proteins or of wild-type baculovirus proteins in Sf9 cells did not significantly increase intracellular calcium levels. These results suggest that the nonstructural glycoprotein NSP4 is responsible for the increase in cytosolic calcium observed in rotavirus-infected cells.

Animals↗

PubMed1994

Antitumor activity of immunoconjugates composed of boanmycin and monoclonal antibody.

Boanmycin (bleomycin A6, BM), an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.

Adenocarcinoma↗

PubMed1991

[Ultrastructural study and localization of duck hepatitis B virus in the livers of experimentally infected ducks].

An electron microscopic study was performed to investigate the occurrence and localization of duck hepatitis B virus (DHBV) in the livers of infected Beijing ducks. DHBV-DNA was found in trace amounts in liver extract on 9th hours after infection by Southern blot hybridization and was found in serum on the 4th day of infection. Virus particles were recognized in the hepatocytes as early as the 3rd day of infection. Many incomplete virus particles, (50 to 80 nm in diameter), and a few complete virus particles, (45-65 nm in diameter), were seen in cisternae of rough and smooth endoplasmic reticula of hepatocytes, clusters or scattered core particles, (35-38 nm in diameter), were seen in the cytoplasm, some core particles were found in nuclei of liver cells where core assembly might be occur. The similarities and differences of the localizations of DHBV and HBV in duck liver cells are discussed.

Animals↗

PubMed1990

[Biosynthests of glutathione in yeasts].

From 3091 strains of yeast, a strain of Candida sp K11 was selected which can produce 18 mg glutathione (GSH) by one gram of the dried cells in the presence of L-CySH in the culture medium. The original strain K11 was subjected to mutagenesis by ultraviolet irradiation and a strain of analogue-antimetabolic mutant K11 UE 126 was selected on the plate of GSH metabolic analogue ethionine. The content of GSH in the K11 UE 126 cells increased by 49.7% over the original strain K11 even without adding L-CySH in the culture medium.

Candida↗

PubMed1982

Mechanism of soft X-ray radiation damage on glycine by XPS.

This paper reports the behaviour of radiation damage of solid glycine in a XPS spectrometer equipped with Mg and Al X-ray sources. The main results are as follows: (i) the kinetics of the damage process obeys the first-order rate law, (ii) decarboxylation can be deduced, and (iii) deamination does not occur, but the nitrogen atoms in original molecules are transformed into a new chemical form with higher electron density by photo-reduction.

Deamination↗