Search PubMed⌕ Search

Biomedical subjects

W S Walker

Publications and source records attributed to W S Walker.

144 records · Page 8Linked to original sources
PubMed1977

Mediation of macrophage cytolytic and phagocytic activities by antibodies of different classes and class-specific Fc-receptors.

The classes of antibodies that mediate the phagocytosis and cytolysis of 51Cr-labeled chicken erythrocytes by IC-21 macrophages, an established line of mouse peritoneal macrophages, were identified. The phagocytic activity of IC-21 macrophages, as determined by a functional inhibition assay with mouse myeloma proteins, depended mainly on IgM and IgG2a antibodies and to a lesser extent on IgG2b antibodies. Extracellular cytolysis of target cells was mediated solely by IgG2b antibodies. These results correlate with the previously documented specificities of discrete Fc-receptors for IgG2a and IgG2b immunoglobulins on IC-21 cells. Thus, phagocytosis and cytolysis appear to be mediated by antibodies of different classes operating through separate and distinct sites on the surface of IC-21 macrophages.

Antibody Specificity↗
PubMed1976

Separate Fc-receptors for immunoglogulins IgG2a and IgG2b on an established cell line of mouse macrophages.

The specificity of Fe-receptors on IC-21 cells, an established line of mouse peritoneal macrophages with antibody-dependent effector cell activity has been examined. Only IgG2a and IgG2b myeloma proteins bound readily to IC-21 Fc-receptors, the former in nonaggregated as well as aggregated form, the latter only as aggregated complexes. Thus, IgG2a bound in a manner characteristic of classically defined cytophilic antibody, whereas the binding of IgG2b appeared to be mediated by Fc-receptors for antigen-antibody complexes. Evidence is presented in support of the view that IC-21 macrophages possess separate and distinct Fc-receptor sites for these two immunoglobulins.

Animals↗
PubMed1975

Antibody-dependent cytolysis of chicken erythrocytes by an in vitro-established line of mouse peritoneal macrophages.

An in vitro-established line of mouse peritoneal macrophages (IC-21) was tested for its ability to mediate the cytolysis of 51chromiun-labeled chicken erythrocytes. In the presence of specific antibody, but independently of complement, the macrophages phagocytized and lysed labeled erythrocytes. The phagocytic process proved to be functionally distinct from the cytolytic reaction as demonstrated by enhanced cytolysis in the presence of iodoacetate, an inhibitor of phagocytosis. This cell line, because of its effector activity in antibody-dependent cell-mediated immune reactions, will be useful in characterizing the mechanism(s) involved in macrophage-mediated cytolysis.

Animals↗
PubMed1973

Consequent intrafamilial immunization for DL-A haplotyping in canines.

A procedure of intrafamilial immunization is described for production of antisera recognizing DL-A haplotypes. In a colony consisting of 1 sire, 6 bitches, and 67 offspring all haplotypes could be accurately allocated. In the colony the observed reaction frequencies of the antisera are in agreement with mendelian codominant inheritance. Mixed lymphocyte culture tests confirmed the accuracy of the serologic typing and the presence of homozygous individuals within the colony. Further evidence is presented supporting the presence of two or more subloci within the DL-A system. Colonies of canines such as the one described should provide a sensitive system for evaluating interaction between serologic DL-A typing, MLC reactivity, and immune response genetics in a nonrodent species which is not highly inbred.

Animals↗
PubMed1969

Isolation and partial characterization of a staphylococcal leukocyte cytotaxin.

A factor which attracts rabbit polymorphonuclear leukocytes both in vitro and in vivo was isolated from the culture filtrate of a strain of Staphylococcus aureus. The activity of the chemotactic factor was independent of fresh serum and it was nondialyzable. Incubation of the factor with heat-inactivated human serum markedly inhibited its chemotactic property. The factor was heat-labile (80 C, 10 min) in the crude culture filtrate but was heat-stable when partially purified.

Animals↗
PubMedDate not supplied

Effects of the cessation of training on left ventricular function in the racing greyhound. Serial studies in a model of cardiac hypertrophy.

Exercise-induced cardiac hypertrophy has been associated with normal resting left ventricular function and, after cessation of training, variable degrees of regression. The racing greyhound is an animal with cardiac hypertrophy said to be part congenital and part exercise-induced. Racing greyhounds underwent serial cardiac catheterization three times during an 8-month period after cessation of racing/training to determine the functional consequences of the cessation of training. At the end of 8 months of inactivity the animals' hearts were excised and weighed in order to compare heart weight/body weight (HW/BW) ratios with those obtained in a group of racing greyhounds killed within one month, 19 +/- 16 days (mean +/- SD), of the cessation of training. Comparison of HW/BW ratios failed to reveal a significant difference between the serially studied group, 12.1 +/- 1.9 g/kg (mean +/- SD), and the more recently exercising group, 12.7 +/- 1.4 g/kg (mean +/- SD) of dogs. After 2 months of inactivity, 9 of 12 greyhounds in the serially studied group showed increases in max dP/dt and dP/dt normalized to a pressure of 50 mmHg. Modified pre-ejection period and peak negative dP/dt also increased significantly (p less than .004) during this same period. No further changes in these variables were found at the final 8-month study. Our failure to demonstrate a difference in HW/BW ratios between these two groups of dogs suggests that the exercise-induced component of cardiac hypertrophy in the trained racing greyhound is probably very small and, if it exists, regresses very early (less than 1 month). Changes in contractility indices that were observed occurred after this time period (between 1 and 2 months) and are therefore probably not due to regression of cardiac hypertrophy.

Animals↗
PubMedDate not supplied

Wound colonisation following cardiac surgery. Reduction by adjuvant use of preincisional, presternal antibiotic infiltration: a double blind prospective randomised study.

In a double blind, prospective, randomised study of 100 patients undergoing elective cardiac surgery, a significant (p less than 0.01) reduction in wound colonisation, defined as positive culture of any wound discharge irrespective of wound appearance, occurred in those receiving preincisional presternal antibiotic infiltration (2%) as compared to a control group who received a similar volume of normal saline by the same route (24%). Both groups received, in addition, the same conventional intravenous regimen of broad spectrum antibiotic. A comparable concurrent group of patients, not entered into the study, demonstrated a wound colonisation rate similar to the trial control group (22%), thus excluding an adverse bias from the control saline infiltration. Analysis of control cases demonstrated a significant (p less than 0.001) discriminant effect in the degree of preoperative haemodilution with haematocrit falling on bypass by a mean of 25% in those who developed wound colonisation as compared to 13% in those who did not.

Anti-Bacterial Agents↗
PubMedDate not supplied

Continued experience with thoracoscopic major pulmonary resection.

Between April 1992 and March 1995, 83 patients underwent video-assisted (VATS) thoracoscopic major pulmonary resection (lobectomy: 72, bilobectomy: 4, or pneumonectomy: 7). Conversion to open thoracotomy was required in a further 21 cases (rate=20.2%). There was no in unit mortality; 2 patients died within 30 days (1.9% overall). Analysis (median values) of the VATS lobectomy cases demonstrated; operation time - 135 minutes; blood loss - 80 mls; High Dependency stay - 38 hours; total postoperative stay - 7 days. Comparison between 70 VATS lobectomies and a simultaneous group of 110 open thoracotomy cases confirmed reduced postoperative morphine consumption (83 mg open vs 57 mg VATS; p<0.001). One pneumonectomy patient exhibited a transient sympathetic dysaesthesia and one lobectomy patient developed a mild post thoracotomy pain syndrome. Long-term follow-up of VATS lobectomy for patients with primary bronchogenic carcinoma (49) revealed 1 bronchogenic cancer related death during an overall mean follow-up of 16.5 months.

Adult↗