Biomedical subjects

Ming Yan

Publications and source records attributed to Ming Yan.

57 records · Page 4Linked to original sources

PubMed1998

In vitro Inhibition of Human Melanoma Cells by Immunotoxin Luffin B-Ng76.

Luffin B, a plan single-chain ribosome inactivating protein, was purified from seeds of Luffa cylindrica by Blue Sepharose CL-6B affinity chromatography. An immunotoxin was constructed with luffin B and Ng76, a monoclonal antibody to human melanoma cell M(21). Luffin B-Ng76 showed 4 000-fold more cytotoxic to target melanoma cells than free luffin B. The IC(50) of luffin B-Ng76 for M(21) cells and non-target HeLa cells was 2.5x10(-11) mol/L and 3.0x10(-8) mol/L, respectively. The results suggest that luffin B is a new potent immunotoxin effector.

Journal Article↗

PubMedDate not supplied

Effects of molybdenum, silicon and nickel on alpha1-adrenoceptor-induced constriction of rat isolated aorta.

1. To determine the effects of trace elements on alpha1-adrenoceptor-mediated vasoconstriction, we studied the effects of molybdenum (Mo), silicon (Si) and nickel (Ni) on vasoconstrictor response to an alpha1-adrenoceptor agonist in rat aorta. 2. Cumulative concentration-contraction curves were obtained for phenylephrine (1 nmol/L-10 micromol/L) in the absence and presence of Mo, Si and Ni (0.3, 1 and 3 micromol/L) in rat aorta rings. Increasing the concentration of Mo and Si from 0.3 to 3 micromol/L shifted the cumulative concentration-contraction curve to the right, but did not reduce the maximal contractile response to phenylephrine. In contrast, Ni at 1 and 3 micromol/L shifted the cumulative concentration-contraction curve to the right and, at 3 micromol/L, reduced the maximum contractile response to phenylephrine. 3. We conclude that micromolar concentrations of Mo, Si and Ni affected alpha1-adrenoceptor-induced vasoconstriction and that Ni significantly inhibited the maximal contractile response to phenylephrine in rat isolated aorta.

Animals↗

PubMedDate not supplied

Characterization of dominant-negative forms of anthrax protective antigen.

Certain mutations within the protective antigen (PA) moiety of anthrax toxin endow the protein with a dominant-negative (DN) phenotype, converting it into a potent antitoxin. Proteolytically activated PA oligomerizes to form ring-shaped heptameric complexes that insert into the membrane of an acidic intracellular compartment and promote translocation of bound edema factor and/or lethal factor to the cytosol. DN forms of PA co-oligomerize with the wild-type protein and block the translocation process. We prepared and characterized 4 DN forms: a single, a double, a triple, and a quadruple mutant. The mutants were made by site-directed mutation of the cloned form of PA in Escherichia coli and tested by various assays conducted on CHO cells or in solution. All 4 mutant PAs were competent for heptamerization and ligand binding but were defective in the pH-dependent functions: pore formation, ability to convert to the SDS-resistant heptamer, and ability to translocate bound ligand. The single mutant (F427K) showed less attenuation than the others in the pH-dependent functions and lower DN activity in a CHO cell assay. The quadruple (K397D + D425K + F427A + 2beta2-2beta3) deletion showed the most potent DN activity at low concentrations but also gave indications of low stability in a urea-mediated unfolding assay. The double mutant (K397D + D425K) and the triple (K397D + D425K + F427A) showed strong DN activity and slight reduction in stability relative to the wild-type protein. The properties of the double and the triple mutants make these forms worthy of testing in vivo as a new type of antitoxic agent for treatment of anthrax.

Animals↗