Biomedical subjects

A D O'Brien

Publications and source records attributed to A D O'Brien.

111 records · Page 7Linked to original sources

PubMed1976

Inhibition of water absorption in the intestine by Staphylococcus aureus delta-toxin.

Water absorption in intestinal segments was monitored by measuring the concentration of polyethylene glycol, a nonabsorbable reference marker, in a balanced salt solution continuously perfused through the lumen. Staphylococcus aureus delta-toxin inhibited water absorption in rabbit jejunum and ileum perfused in vivo and in guinea pig ileum perfused in vitro. Cholera toxin also interfered with water absorption in guinea pig ileum maintained in vitro, but S. aureus enterotoxin B had no demonstrable effect on this tissue.

Animals↗

PubMed1976

Increased cyclic adenosine 3',5'-monophosphate content in guinea pig ileum after exposure to Staphylococcus aureus delta-toxin.

To compare Staphylococcus aureus delta-toxin with cholera toxin, which is known to increase cellular cyclic adenosine 3',5'-monophosphate (cAMP), studies were undertaken to determine the effect of delta-toxin on the cAMP content of guinea pig ileum maintained in vitro. Concentrations of delta-toxin as low as 0.40 mug/ml increased cAMP levels in guinea pig ileum after 2 h of incubation. Histological damage was seen in ileum exposed for 2 h to delta-toxin concentrations of 100 mug/ml. As little as 3 mug of delta-toxin increased vascular permeability in guinea pig skin. Permeability changes became evident within 5 min and were maximal within 6 h, whereas those produced by cholera toxin required 24 h to become maximal. Benadryl did not interfere with the ability of these toxins to alter vascular permeability. Purified egg lecithin reduced the effectiveness of delta-toxin in the skin but did not inhibit cholera toxin. Delta-toxin in concentrations as low as 0.1 mug/ml caused dislodgement of HeLa cells in tissue cultures. Therefore, delta-toxin appears unique in being the only bacterial toxin, currently known to alter water absorption in the ileum, that is capable of both increasing cAMP levels and being cytotoxic. These findings suggest a possible role for delta-toxin in the pathogenesis of staphylococcal enteritis.

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PubMedDate not supplied

Bacterial toxins: friends or foes?

Many emerging and reemerging bacterial pathogens synthesize toxins that serve as primary virulence factors. We highlight seven bacterial toxins produced by well-established or newly emergent pathogenic microbes. These toxins, which affect eukaryotic cells by a variety of means, include Staphylococcus aureus alpha-toxin, Shiga toxin, cytotoxic necrotizing factor type 1, Escherichia coli heat-stable toxin, botulinum and tetanus neurotoxins, and S. aureus toxic-shock syndrome toxin. For each, we discuss the information available on its synthesis and structure, mode of action, and contribution to virulence. We also review the role certain toxins have played in unraveling signal pathways in eukaryotic cells and summarize the beneficial uses of toxins and toxoids. Our intent is to illustrate the importance of the analysis of bacterial toxins to both basic and applied sciences.

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