Search PubMed⌕ Search

Biomedical subjects

L A Wilson

Publications and source records attributed to L A Wilson.

At least 181 records · Page 10Linked to original sources
PubMed1971

Characteristics of complement-dependent release of phospholipid from Escherichia coli.

The release of (32)P-labeled bacterial phospholipid from a smooth Escherichia coli by serum components depends on complement activated by antibody. Phospholipid release in excess antibody tends to be proportional to the concentration of complement as does the release of other cellular constituents. Phospholipids are not simply stripped off during cell lysis. Whereas 94% of the total phospholipid freed from E. coli by mechanical lysis sediments at centrifugal forces sufficient to sediment molecules of 10(6) molecular weight, similar centrifugation sediments only 50% of the phospholipid released by antibody-complement. In fact, after mechanical lysis more than 50% of the phospholipid sediments at velocities sufficient to bring down cell envelopes. Although the bulk of the bacterial phospholipid is located in the cell envelopes, isolated (32)P-labeled cell envelopes and phenol-extracted lipopolysaccharide fails to release phospholipids in the presence of antibody-complement. Moreover, ethylenediaminetetraacetic acid, which like antibody-complement causes loss of cellular selective permeability and prepares E. coli cell walls for the action of lysozyme, releases only small amounts of phospholipid from E. coli and these are sedimentable. The most likely mechanism of phospholipid release caused by antibody-complement appears to be the activation directly or indirectly of an enzyme which is present only in the intact cells.

Animals↗
PubMed1968

Molecular and structural damage to Escherichia coli produced by antibody, complement, and lysozyme systems.

The antibacterial action of antibody (normal and hyperimmune), complement, and lysozyme has been studied by correlating the ultrastructural and biochemical changes that they cause in smooth Escherichia coli. Both normal and hyperimmune antibody, in the absence of lysozyme, produced complement-dependent release, into the suspending medium, of 63 to 72% of the (32)P-labeled phospholipid and 74 to 85% of the small molecular bacterial constituents. Macromolecular nucleic acid labeled with (32)P was not released. By phase microscopy, these cells appeared as bacilli but their ultrastructure showed general swelling, with smoothing of the normally wrinkled outer cell wall layers. Cytoplasmic membranes were damaged and the internal cell structure was disorganized. Membranous spherules, apparently from the outermost putatively lipopolysaccharide cell layer, were released into the medium. When lysozyme was added to antibody and complement, (32)P-labeled macromolecular constituents were released from the cells. Damage to ultrastructure then included loss of cell wall rigidity, cell wall breakage, and some spheroplast formation. Characteristic fibrillar fragmentation was seen in cell wall mucopeptide layers. The relationships between antibody-complement dependent release of bacterial phospholipid, loss of selective cell permeability, and increase in sensitivity to lysozyme are discussed.

Antibodies↗