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Biomedical subjects

W S Walker

Publications and source records attributed to W S Walker.

At least 127 records · Page 7Linked to original sources
PubMed1983

Selective induction of enhanced complement receptor 3 activity on murine macrophages.

A high proportion of murine resident peritoneal macrophages bear complement receptors 1 and 3 (CR1, CR3) which bind C3b and iC3b components of complement, respectively. By contrast, macrophages derived from bone marrow, blood, and the elicited peritoneal exudate are predominantly CR1+3. To determine if the microenvironment of the normal peritoneal cavity influences CR3 phenotype, we studied the effects of lavage from the cavity on cultures of primary peritoneal exudate macrophages, and on macrophages derived from progenitors in the bone marrow, blood, and peritoneal exudate. The cell-free peritoneal lavage (CFPL), after 24 hr of culture, induced CR3 on primary and culture-derived populations of peritoneal exudate macrophages but had no effect on the CR3 phenotype of macrophages derived from bone marrow or blood. The CR3-inducing activity in CFPL was abolished by heating at 70 degrees C for 30 min and by trypsin, and was not affected by adsorption with EA(IgM)iC3b indicator cells, demonstrating that it is not soluble CR3. Finally, exudate macrophages exposed to CFPL required at least 24 hr before they expressed CR3; such macrophages regenerated CR3 after the receptors were removed by trypsin. The selective effect of the activity in CFPL for peritoneal exudate macrophages indicates that the local microenvironment of the peritoneal cavity can influence the expression of CR3.

Animals↗
PubMed1983

Dynamics of cytochemically distinct subpopulations of macrophages in elicited rat peritoneal exudates.

Qualitative and quantitative changes in rat peritoneal macrophage (M phi) subpopulations, differing in their ultrastructural peroxidatic staining characteristics were followed over the course of a thioglycollate (TG) broth-induced inflammatory response. In addition, selected functional features of the normal steady-state and 4-day TG-induced populations of M phi were compared. The steady-state population consisted primarily of M phi with peroxidatic staining limited to the nuclear envelope (NE) and rough endoplasmic reticulum (RER); such cells are called resident M phi. Within hours of TG injection, there was an influx of monocyte-derived exudate M phi, the number of which reached a maximum, by 24 hr. During the next 24 hr, the proportion of exudate M phi decreased with a concomitant increase in peroxidatic activity (PA)-negative M phi. These two cell types continued to predominate for the next 48 hr during which there was a gradual increase in resident M phi and so-called "exudate-resident" M phi, the latter of which exhibits both exudate and resident PA patterns. Thus, the 4-day TG-induced population consisted of four cytochemically distinct M phi subpopulations: approximately 50% PA-negative M phi, approximately 25% exudate M phi, approximately 15% resident M phi, and approximately 10% exudate-resident M phi. Differences in Fc receptors and complement receptors 1 and 3 were noted between the two populations in the presence of progenitors that give rise to colonies of M phi in liquid culture in response to murine-derived colony-stimulating factor 1. The implications of these results in regard to the origin(s) of M phi diversity are discussed.

Animals↗
PubMed1983

Isolation and characterization of cell cycle-enriched subpopulations of a murine macrophage cell line by centrifugal elutriation.

The cell cycle of the P388D 1 murine macrophage line was delineated and suspensions of exponentially growing cells were separated by centrifugal elutriation into subpopulations enriched in the various phases of the cycle. Analysis of both growth and labelled mitoses curves disclosed that the doubling and cell-cycle times were essentially identical (18.4 and 18.3 h), indicating that all cells were in cycle. In addition, G1 + 1/2M was 4.3 h, whereas S phase and G2 + 1/2M lasted about 12 and 1.5 h. The most homogeneous subpopulations of phase-enriched cells obtained by elutriation were cells in G1 and S, where purities (estimated by both labelling indices and analyses of DNA histograms obtained by flow cytometry) exceeded 80%. Isolation of G2 + M-phase cells was not as efficient, although the purity of these subpopulations was consistently greater than of 50%, an approx. 10-fold enrichment over unseparated suspensions of cells. Comparison of IgG2a-Fc-receptor-mediated phagocytic activities among the phase-enriched subpopulations showed that cells in G2 had appreciably enhanced activity.

Animals↗
PubMed1983

Macrophage cell cycling: influence on Fc receptors and antibody-dependent phagocytosis.

The influence of cell cycling on the density and binding properties of IgG2a Fc receptors and their associated antibody-dependent phagocytic activity was investigated with the P388D1 murine macrophage cell line. Unseparated macrophages and subpopulations of elutriated macrophages, enriched for cells in G1, S, and G2 + M phases were compared to detect possible differences in IgG2a-dependent phagocytosis. Suspensions of G2 + M phase cells were appreciably enhanced in phagocytic activity over G1-phase cells, which were less phagocytic than unseparated macrophage populations. An analysis of the binding of 125I-IgG2a myeloma protein disclosed that the IgG2a Fc receptor avidity remained essentially unchanged during cell cycle traverse, whereas the number of IgG2a Fc receptors more than doubled as cells cycled from G1 to G2 + M (1.5 X 10(5) vs 3.4 X 10(5) receptors per cell). With their increased size relative to G1 cells, and the resultant increase in receptor number, G2 phase cells should have more productive collisions with the antibody-coated target cells and greater phagocytic capacity.

Animals↗
PubMed1983

Macrophage subpopulations and the murine F1 x parent mixed leukocyte reaction.

The ability of subpopulations of murine spleen cells enriched for macrophages to function as stimulator cells in the F1 x parent-hybrid mixed leukocyte reaction (F1 x P MLR) was assessed. Suspensions of F1 splenic adherent cells--depleted of T cells, B cells, and dendritic cells--were separated into four density-dependent subpopulations on discontinuous gradients of Percoll, and the cells were examined for macrophage characteristics, the presence of la antigen, and their ability to stimulate in the F1 x P MLR. The least dense subpopulation was the most highly enriched with nonspecific esterase-positive (NSE+), phagocytic, and Fc and complement receptor-bearing cells, by comparison with the denser subpopulations. All subpopulations contained similar proportions of Ia+ cells. When the MLR stimulatory activity of the subpopulations was tested with suspensions of parental responder cells, the level of stimulation was directly proportional to the content of NSE+la+ cells in the subpopulations. The densest subpopulation contained no NSE+ cells but did contain la+ cells, which did not induce a MLR. Thus, although necessary for an MLR, la-bearing splenocytes were not by themselves adequate to stimulate the reaction. Rather, cells had to be both NSE+ and la+, indicating that a NSE+ cell-derived factor is involved in this in vitro correlate of cell-mediated immunity. For MLR stimulatory activity, the subpopulations of NSE+la+ cells appear to be functionally homogeneous.

Animals↗
PubMed1983

Does cell density correlate with red cell age?

We have examined age-related changes in red cells by employing a serial hypertransfusion protocol to generate populations of in vivo-aged mouse red cells. Studies of these old cells have revealed alterations in membrane components; namely, a conversion of band 4.1b to 4.1a and an increase in the amount of membrane-associated, Triton-insoluble globin. Furthermore, we have found that the erythrocyte does change in density, but only during the earliest stages of its life-span. As the cell continues to age, there is no longer a correlation between age and density.

Animals↗
PubMed1982

Preoperative intraparietal (intra-incisional) cefoxitin in abdominal surgery.

The effect of preoperative intraparietal (intra-incisional) injection of cefoxitin along the site of the intended incision on the incidence of wound infection has been investigated by a randomized prospective study of 181 consecutive patients undergoing abdominal surgery. A significant reduction in wound infection was evident in the cefoxitin-treated group (4.4 per cent) when compared with controls (16.7 per cent) (chi 2 = 6; P = 0.02). Administration of antibiotic by this route did not delay wound healing or produce any undesirable sequelae.

Abdomen↗
PubMed1982

Complement receptor phenotypes of culture-derived murine macrophages.

The distribution of complement receptors CR1 and CR3 among macrophages derived from cultures of bone marrow, blood, and elicited or normal peritoneal cell populations was studied. Cells and colonies from the first three sources had a common phenotype, CR1+3-, whereas those from the normal peritoneal populations had either CR1+3- or CR1+3+. The former phenotype characterized spindle-shaped as well as epithelial-like macrophages; the latter was essentially restricted to colonies made up of the epithelioid cells. Both morphologic features and the CR phenotypes remained stable throughout the culture period. These phenotypic differences might be explained by the presence of at least two clonally derived types of macrophages.

Animals↗
PubMed1982

Oral verapamil for paroxysmal supraventricular tachycardia: a long-term, double-blind randomized trial.

The effectiveness and safety of orally administered verapamil was tested in 11 patients with frequent paroxysmal supraventricular tachycardia. In a 4-month randomized, double-blind, placebo-controlled trial, the frequency of paroxysmal supraventricular tachycardia fell from 0.3 +/- 0.3 (mean +/- SD) to 0.1 +/- 0.1 episodes per day by patient diary (p less than 0.05) and from 0.7 +/- 0.7 to 0.3 +/- 0.5 episodes per day by Holter monitor (p less than 0.05) for placebo and verapamil treatment periods, respectively. Verapamil caused a decrease in the duration of paroxysmal supraventricular tachycardia (in minutes per day): placebo 27 +/- 51 by dairy, 67 +/- 111 by Holter; verapamil, 3 +/- 3 by diary, 1 +/- 2 by Holter (p less than 0.05). Five patients required a total of 35 pharmacologic cardioversions for sustained tachycardia: two during verapamil and 33 during placebo (p less than 0.001). No verapamil treatment period was shortened due to unacceptable paroxysmal supraventricular tachycardia, but five of 22 placebo treatment periods were shortened (p equal to 0.02). Verapamil was well-tolerated, causing mild constipation in five patients and headache in one. Oral verapamil is both safe and effective in the long-term treatment of patients with paroxysmal supraventricular tachycardia.

Administration, Oral↗
PubMed1982

The use of doxapram in the prevention of postoperative pulmonary complications.

A prospective, double-blind, randomized controlled clinical trial has been conducted to assess the effect of doxapram hydrochloride infusions on pulmonary complications in patients undergoing extensive abdominal operations. For the purposes of this study, a pulmonary complication was defined as the production of purulent sputum or the presence of any abnormal clinical or roentgenologic chest signs. Of the 53 control patients, 41 had chest problems develop by these criteria, whereas the same was true of only 20 of the 40 patients receiving doxapram. The average duration of hospitalization was one day less for those receiving the drug.

Clinical Trials as Topic↗
PubMed1982

Interaction of a mouse macrophage cell line with homologous erythrocytes.

The interaction of the IC-21 murine macrophage cell line and homologous red blood cells (RBC) was assessed in the absence of exogenous opsonins. These results were used to evaluate this system as a potential model for macrophage-mediated clearance of old or damaged RBC. The binding and ingestion of density-separated and unseparated RBC by IC-21 cells were quantitated in assays that involved both 51Cr-labeled RBC and direct microscopy. The number of unseparated RBC that bound to IC-21 macrophages depended on the number of RBC added. Macrophages phagocytized an appreciable proportion of RBC within 3 hours with the ratio of RBC:macrophage of 10, a point at which the RBC-binding was not rate limiting. The mouse RBC were separated into dense- and less-dense fractions which are presumably enriched for old and young cells, respectively. When these RBC fractions were incubated with the IC-21 macrophage, significantly more of these dense cells were phagocytized. These results show that IC-21 macrophage cell line is a useful model for defining the processes whereby aged or damaged RBC are recognized and removed from circulation by macrophages.

Animals↗
PubMed1977

Macrophage-induced thymic lymphocyte maturation.

Guinea-pig peritoneal macrophages were found to influence the functional maturation of thymic lymphocytes. Autologous thymic lymphocytes obtained from macrophage co-cultures responded to three different mitogens and were reduced in their ability to reassociate spontaneously with macrophages. Neither of these properties were found in thymic lymphocytes that had not been cultured with macrophages. These functional changes appeared to be specific for macrophages since thymic lymphocytes incubated with skin fibroblasts failed to respond to the test mitogens. Furthermore, they were not the result of either the inactivation, by macrophages, of a putative suppressor thymocyte or a soluble macrophage product. In addition to influencing the functional maturation of thymic lymphocytes, macrophages also appeared to play a direct role in inducing the mitogen response of functionally mature cells.

Animals↗