Biomedical subjects

G A Shibao

Publications and source records attributed to G A Shibao.

3 recordsLinked to original sources

PubMed1990

Metals inhibit riboflavin-catalyzed generation of superoxide anion in vitro.

We found that addition of cationic metals inhibited flavin-catalyzed superoxide anion (O2-.) production in vitro. Inhibition of O2-. generation by metals appeared to relate to the ability of metal ions to chelate or complex with amine groups, altering their electronegativity. Metal inhibition of O2-. production has important implications for biological systems involving O2-. radical production, as well as for assays requiring the generation of O2-. in vitro.

Catalysis↗

PubMed1988

Small increases in pH decrease uptake of Escherichia coli by human neutrophils in vitro.

Increases in pH from 7.4 to 7.8 decreased the ability of human neutrophils in serum to ingest and kill Escherichia coli ATCC 29552 in vitro. In contrast, similar increases in pH did not decrease the bactericidal activity of neutrophils in serum against Staphylococcus aureus 502A. Increases in pH did not alter opsonization of E. coli by serum or the growth of E. coli but rather appeared to alter neutrophil uptake of bacteria by a direct effect on the neutrophil.

Escherichia coli↗

PubMed1988

Variable effect of toxic shock toxins from different sources on neutrophil function in vitro.

Toxic shock syndrome toxins (TSST) are 23-30 kD proteins that have been isolated from incubation media of strains of Staphylococcus aureus cultured from patients with toxic shock syndrome (TSS). Injection of TSST into animals produces many of the symptoms that characterize TSS including shock, fever, and multiple organ failure. We found that addition of increasing concentrations of TSST-1-VP1035-16A, but not TSST-PEC, TSST-SEC, staphylococcal enterotoxin A or B, progressively decreased human neutrophil bactericidal activity against S. aureus, 502A in vitro. TSST-1-VP1035-16A, but not the other toxins, also decreased superoxide anion and hydrogen peroxide concentrations in mixtures containing neutrophils and phorbol myristate acetate (PMA) in vitro. The results indicate that various preparations of TSST have different effects on neutrophil function in vitro and, accordingly, may have different effects in other in vitro and in vivo models of TSS.

Bacterial Toxins↗