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D R Shaw

Publications and source records attributed to D R Shaw.

69 records · Page 4Linked to original sources
PubMed1982

Thioglycollate-elicited mouse peritoneal macrophages are less efficient than resident macrophages in antibody-dependent cell-mediated cytolysis.

Peritoneal macrophages (M phi) obtained after i.p. injection of Brewer thioglycollate medium (TG) were substantially less efficient than resident (R) M phi in an assay of antibody-dependent cell-mediated cytolysis (ADCC) in which 51Cr-labeled sheep erythrocytes were used as target cells. The TG-M phi did not display any generalized functional defects, and indeed were "activated" relative to R-M phi by several morphologic, biochemical, and functional criteria. The ADCC deficiency was observed with TG-M phi from four strains of mice, and was not altered by the use of different types of target cells or different sensitizing IgG antibodies. Treatments that significantly enhanced R-M phi ADCC activity, either inhibition of phagocytosis by tosyl lysine chloromethyl ketone or stimulation of M phi enzyme secretion and O2- production, resulted in only a modest enhancement of TG-M phi ADCC. The effect of i.p. TG injection on M phi ADCC activity was not mimicked by in vitro exposure of R-M phi to TG. In vivo experiments demonstrated that agar, a component of TG, was sufficient to elicit M phi that resembled TG-M phi morphologically and functionally. We discuss the possibility that the ADCC deficiency of TG-M phi may be a characteristic of cells involved in the subsidence of an acute inflammatory response.

Animals↗
PubMed1981

Phagocytosis requires repeated triggering of macrophage phagocytic receptors during particle ingestion.

The phagocytic functions of polymorphonuclear leukocytes and mononuclear phagocytes are crucial elements in host defence against a variety of invading microorganisms. Phagocytosis is a highly selective process, requiring specific interactions between the surface of the particle to be ingested and the plasma membrane of the phagocytic cell. The phagocyte can therefore discriminate between 'ingestible' and 'non-ingestible' particles even when the different particles are located in close proximity on the plasma membrane of the phagocytic cell. Previous work has demonstrated that these specific interactions between particle and phagocyte are required not only for the initiation of phagocytosis--that is, attachment of the particle to the phagocytic cells and generation of a signal to trigger phagocyte pseudopod extension--but also for the subsequent progression of pseudopods over the entire surface of the particle. We present evidence here that the continued interactions between phagocyte plasma membrane receptors and particle-bound ligands do not function merely to direct otherwise random phagocyte pseudopod movement, but instead are required for the repeated generation of intracellular phagocytic signals during the entire ingestion process.

Animals↗
PubMed1980

Different divalent cation requirements for binding IgM complexes to lymphocytes and macrophages.

We have found that Mg++ supports IgM complex binding to mouse lymphocytes but not to macrophages. In contrast, Ca++ supports IgM complex binding to macrophages but not lymphocytes. IgG complex binding to both lymphocytes and macrophages is divalent cation independent. These findings allow one to distinguish IgG from IgM binding and macrophage from lymphocyte IgM complex binding by their differential divalent cation requirements.

Animals↗
PubMed1980

R-plasmid transfer frequencies from environmental isolates of Escherichia coli to laboratory and fecal strains.

Multiple-drug-resistant strains of Escherichia coli were isolated from the water at an estuarine site. They represented about 8.3% of the total E. coli population. Fifty-five strains, representing each of the 32 resistance patterns identified, were mated with an E. coli K-12 F- strain. Matings were performed on membrane filters, and the cells were washed to remove any colicins produced by the donors. Thirty-one strains, about 5% of the mean E. coli density in the samples, transferred drug resistance and, hence, posessed conjugative R plasmids. Of these, 80% transferred drug resistance at a frequency of about 10(-4) or less. Nine environmental R+ strains were mated with three fecal recipients. The R-plasmid transfer frequencies to the fecal strains from the environmental donors correlated well with those from a derepressed K-12 R+ laboratory donor. The R+ X K-12 F- lac- transconjugants from 16 environmental strains were "backcrossed" to a lac+ K-12 F- strain. All transfer frequencies were higher in the backcrosses than in the original matings from the environmental donor. Furthermore, 7 of 13 different transconjugants, which accepted plasmids at repressed frequencies of less than 10(-3), donated them at frequencies greater than 10(-2). This suggests that these were derepressed plasmids in a repressed host.

Anti-Bacterial Agents↗
PubMed1980

Sodium azide inhibition of complement-mediated functions.

Moderate concentrations of sodium azide (0.1-0.2%) significantly inhibited guinea-pig and human complement-mediated lysis of both IgM- and IgG-sensitized sheep erythrocytes. The reduction in cytolysis was not attributable to non-specific ionic effects, to inactivation of native complement components by azide, or to irreversible interactions of azide with sensitized erythrocytes. Mouse complement-dependent opsonization of sensitized erythrocytes, as judged by macrophage complement receptor-mediated attachment and phagocytosis of the erythrocytes, was comparably inhibited by sodium azide, suggesting that azide acted within the sequence of the first four components of the classical complement pathway.

Animals↗
PubMed1971

Nature and origins of phosphorus compounds in isolated cell walls of Staphylococcus aureus.

Preparations of purified cell walls from Staphylococcus aureus were shown to contain small amounts of phospholipid and glycerol teichoic acid. Since these are components of the cell membrane, it is probable that the wall itself contains no lipid, but does retain fragments of membrane because of physical connections between wall and membrane. In walls of S. aureus strain 52A5, which completely lacks ribitol teichoic acid, the only phosphorylated compound identified as a genuine wall component was a phosphorylated derivative of murein that gave rise to muramic acid phosphate on acid hydrolysis. Muramic acid phosphate was also identified in hydrolysates of walls from S. aureus H and strain 52A2.

Acyltransferases↗
PubMedDate not supplied

Direct quantitation of IgG subclasses 1, 2, and 3 bound to red cells by Rh1 (D) antibodies.

The authors developed quantitative radioimmunoassays to allow direct measurement of total human IgG and individual IgG subclasses among antibodies bound to cell surfaces. The assays use four mouse monoclonal radioiodinated antibodies, one that reacts equally well with all four human IgG subclasses and three that are specific for human IgG subclasses 1, 2, or 3. The assays were used to analyze IgG subclass composition in 21 high-titer anti-D samples from Rh-negative volunteers immunized for Rh immunoglobulin production. Anti-D activity was restricted primarily to the IgG1 and IgG3 subclasses. Eleven of 21 sera demonstrated red cell antibodies with a marked predominance of IgG1 (87 +/- 3.6% of total IgG antibody, +/- SEM) and low levels of IgG3 (1.4 +/- 0.73%). In the remaining 10 sera, IgG3 made up a greater proportion of total IgG antibody (32 +/- 3.8%), although IgG1 was still predominant (61 +/- 4.1%). This observed dichotomy in the IgG subclass profiles of different anti-D sera may be a consideration in the selection of anti-D sera for the production of the immunoglobulin used in the prophylaxis of Rh-incompatible pregnancies.

Adult↗
PubMedDate not supplied

X-ray appearance and clinical significance of left atrial wall calcification.

Ten patients with calcifications of the left atrium are reported with review of the literature. Calcification of the left atrium is frequently associated with history of rheumatic fever, longstanding congestive heart failure, atrial fibrillation, mural thrombus and embolization. Early recognition of such lesions is essential for the management of the patients, particularly when surgical intervention is contemplated. A practical classification of left atrial calcification is proposed according to the dominant lesion in each group: (a) Calcification of the left atrial appendage alone (Mitral stenosis). (b) cacification of all 3 component lesions of the left atrium, i.e., the left atrial appendage, the free wall, and the mitral valve (Severe mitral stenosis). (c) Calcification of the left atrium in MacCallum's patch alone (Mitral insufficiency).

Adult↗