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Biomedical subjects

D Chenoweth

Publications and source records attributed to D Chenoweth.

At least 55 records · Page 3Linked to original sources
PubMed1987

Pulmonary leukosequestration without hypoxemia during hemodialysis.

Dialysis-associated hypoxemia is frequently of clinically significant magnitude and is incompletely understood. In order to investigate the hypoxemia directly we labelled a patient's white blood cells with 111Indium-oxine prior to hemodialysis with acetate or bicarbonate baths. Both dialysate buffers were associated with similar degrees of early peripheral neutropenia, complement activation and elevation of lactoferrin levels, with simultaneous lung localization of radionuclide activity. However, there was not widening of the alveolar to arterial oxygen gradient, or increased wasted ventilatory fraction during this early time period. Significant hypoxemia occurred later in the dialysis, was associated with a decreased respiratory exchange ratio and only occurred with the acetate dialysate buffer. Thus, initial pulmonary leukosequestration was documented but did not have an adverse impact on gas exchange. Hypoxemia during acetate dialysis occurred instead as a consequence of alveolar hypoventilation.

Humans↗
PubMed1986

A derivative of wheat germ agglutinin specifically inhibits formyl-peptide-induced polymorphonuclear leukocyte chemotaxis by blocking re-expression (or recycling) of receptors.

We examined the mechanism of action of a derivative of wheat germ agglutinin (WGA-D) which specifically and irreversibly inhibits N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced polymorphonuclear leukocyte (PMN) chemotaxis. At a concentration that completely inhibited PMN chemotaxis, WGA-D had no effect on either the uptake or release of [3H]-FMLP by PMN. Similarly, WGA-D did not affect either the short-term binding to, or internalization by, PMN of a fluoresceinated FMLP analog. WGA-D did interfere, however, with the re-expression (or recycling) of FMLP receptors by PMN that had been preincubated with 1 microM FMLP for 10 min at 4 degrees C. This effect was specific for WGA-D, because it was not observed when concanavalin A was used. Scatchard plot analysis of FMLP binding to PMN after receptor re-expression demonstrated that WGA-D-treated PMN had a significant diminution in the number of high affinity receptors. WGA-D-mediated inhibition of FMLP receptor re-expression was associated with inhibition of FMLP-induced PMN chemotaxis, but had no effect on either FMLP-induced PMN superoxide anion generation or degranulation. Studies using [125I]-WGA-D demonstrated that PMN did not internalize WGA-D spontaneously. PMN did internalize [125I]-WGA-D, however, when stimulated with FMLP. Internalization of WGA-D by FMLP-stimulated PMN was rapid, dependent on the concentration of FMLP, and specific. Internalization of [125I]-WGA-D by PMN did not occur when highly purified human C5a, instead of FMLP, was used as a stimulus. Subcellular fractionation studies demonstrated that [125I]-WGA-D and [3H]-FMLP were co-internalized by PMN, and segregated to a compartment co-migrating with Golgi markers. Western blot analysis, using PMN plasma membranes, demonstrated that WGA-D bound to a single membrane glycoprotein that migrated with an apparent m.w. of 62,000. The data indicate that WGA-D, perhaps by binding to the FMLP receptor, inhibits FMLP-induced PMN chemotaxis by blocking the re-expression (or recycling) of a population of receptors required for continuous migration.

Adult↗
PubMed1986

Preparation and characterization of a derivative of wheat germ agglutinin which specifically inhibits polymorphonuclear leukocyte chemotaxis to the synthetic chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine.

A nonagglutinating derivative of wheat germ agglutinin (WGA), prepared by treating the native lectin with cyanogen bromide and formic acid and purified by affinity chromatography on an N-acetyl-D-glucosamine column, inhibited human polymorphonuclear leukocyte (PMN) chemotaxis to the synthetic chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). The WGA derivative (WGA-D) did not influence either the ability of PMN to migrate randomly or their chemotactic response to the complement-derived peptide C5a. Similarly, WGA-D had no effect on either FMLP-induced PMN polarization or other FMLP-induced PMN functions (i.e., selective discharge of lysosomal enzymes from cytochalasin B-treated cells, generation of superoxide anion). The inhibition of FMLP-induced PMN chemotaxis by WGA-D could not be reversed by washing the cells, or by incubating lectin-treated PMN at 37 degrees C for 20 min. The inhibitory effect of WGA-D was mediated by its specific binding to N-acetyl-D-glucosamine residues on the cell surface. WGA-D did not alter the specific binding of [3H]-FMLP to its receptor(s) on the PMN membrane. The data presented here suggest that WGA-D inhibits FMLP-induced PMN chemotaxis at a step distal to stimulus recognition.

Adult↗