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Biomedical subjects

W S Walker

Publications and source records attributed to W S Walker.

At least 109 records · Page 6Linked to original sources
PubMed1986

Erythrocyte homeostasis: antibody-mediated recognition of the senescent state by macrophages.

We tested the hypothesis that the accumulation of bound autologous antibody on a "senescent epitope" identifies aged erythrocytes for phagocytic removal by macrophages. Erythrocytes were collected from mice maintained on a hypertransfusion protocol designed to yield cells of defined age. The mouse erythrocytes were assayed for the presence of bound antibody by measuring their susceptibility to ingestion by macrophages from mouse peritoneal exudates and by flow cytofluorometry. Both assays disclosed that only the oldest mouse erythrocytes bore detectable levels of antibody. Flow cytofluorometric analysis revealed that the frequency distribution of IgG isotypes bound to the cells reflected their levels in normal serum. Finally, treatment with trypsin abolished the ability of the macrophages to ingest erythrocytes aged in vivo. These findings support the hypothesis that antibody mediates the clearance of senescent mouse erythrocytes from the circulation and demonstrate that the presence of a trypsin-sensitive recognition structure on macrophages is an essential requirement in this homeostatic process.

Animals↗
PubMed1986

Plasmid-determined cytotoxicity in Yersinia pestis and Yersinia pseudotuberculosis.

Yersinia pestis KIM5 was found to be cytotoxic for the IC21 and P388D1 mouse macrophage cell lines, as well as for resident peritoneal macrophages from C57BL/6 mice. Affected cells phagocytosed KIM5 inefficiently, became spherical, detached readily from culture dishes, and retained 51Cr poorly. The cytotoxic effect was dependent on the presence of the 75-kilobase plasmid pCD1. Because this plasmid also encodes the low calcium response (LCR), three Mu d1 insertion mutants previously shown to be LCR- and of reduced virulence in mice were examined for cytotoxicity; all were found to be atoxic. The insertions in these mutants lie within three distinct LCR loci (lcrB, C, and D). Like LCR, cytotoxicity was expressed only at 37 degrees C. Unlike LCR, it was not influenced by Ca2+ concentration, indicating that the V and W antigens are probably not involved. Yersinia pseudotuberculosis was found to have a similar plasmid-dependent cytotoxicity. Thus, biological activity observed as cytotoxicity in vitro may well be a common feature contributing to virulence of the yersiniae.

Animals↗
PubMed1986

Avoidance of patent anterior grafts at revisional coronary artery surgery: use of a lateral thoracotomy approach.

The use of a right or left lateral thoracotomy is described as an alternative approach to revisional coronary artery surgery for patients with patent anterior grafts. Five patients underwent successful revisional coronary artery grafting with a total of three internal mammary artery grafts and three saphenous vein grafts. This is a safe technique in patients for whom repeat median sternotomy is potentially hazardous, notably those with patent anterior grafts or close apposition of the heart to the sternal table.

Adult↗
PubMed1985

Diagnosis and management of spontaneous transmural rupture of the oesophagus (Boerhaave's syndrome).

The presentation, diagnosis and management of 14 cases of spontaneous transmural oesophageal rupture have been reviewed. Analysis suggested that the classical triad of vomiting, chest pain and subcutaneous emphysema was rare (1/14) and therefore misleading. Abdominal pain and tenderness obscured the clinical picture; the temporal relationship of pain to vomiting varied and subcutaneous emphysema was uncommon (4/14). Consequently, only two cases were correctly diagnosed on presentation and diagnosis in the others was markedly delayed (average 4 days). Contrast swallow examination, when eventually performed, was diagnostic. Twelve patients underwent repair: four under 24 h, who all survived and eight over 24 h, amongst whom there were one (12.5 per cent) operative and two (25 per cent) late deaths. Conservative management was successful in the remaining two cases. Oesophageal fistula, empyema and incorrect initial surgery were common and serious complications. Management options are reviewed and their relative merits considered.

Adult↗
PubMed1985

Transformation of mouse bone marrow cells by transfection with a human oncogene related to c-myc is associated with the endogenous production of macrophage colony stimulating factor 1.

We recently derived a series of transformed cell lines by transfecting mouse bone marrow cells highly enriched for macrophage progenitors with a newly described human gene, R-myc, which has homology to the c-myc oncogene. In this report, we show that these lines share some features characteristic of cells of the mononuclear phagocyte lineage. Specifically, all cell lines had macrophage- or monocytelike morphology, contained nonspecific esterase, were phagocytic for latex beads, secreted lysozyme, bore the Mac-1 antigen, and contained a minority of cells with Fc receptors. However, only a single monocytelike clone had appreciable numbers of cells which bore complement receptor 1, and none were phagocytic for antibody or complement-coated particles, or constitutively secreted Interleukin-1. All these cell lines secreted a growth factor capable of supporting the in vitro proliferation of bone marrow macrophages. Radioimmunoassay and receptor binding studies indicate that this factor is colony stimulating factor 1.

Animals↗
PubMed1985

Human splenic sinusoidal lining cells express antigens associated with monocytes, macrophages, endothelial cells, and T lymphocytes.

The antigenic and functional properties of splenic sinusoidal lining cells (SLC) have not been studied extensively. Some investigators have suggested that SLC are actively phagocytic, and thus part of the mononuclear phagocyte system. Others dispute this and assign the functions of endothelial cells to the SLC. During studies in situ of phenotypic subpopulations of human splenic macrophages (M phi), we found that SLC share membrane antigens (HLA-DR and OKM5), an enzyme (lysozyme), and histochemical properties (nonspecific esterases) with monocytes and M phi. In addition, we showed that LSC, like endothelial cells, synthesize factor VIII of the clotting system and also bear the receptor for transferrin. Our previous studies found that SLC express the antigens found on helper/inducer (OKT4, Leu-3a,b) and suppressor/cytotoxic (OKT8, Leu-2a) T lymphocyte subsets. We have confirmed these observations, and have shown by means of preincubation with soluble complexes of anti-human IgG-human IgG that the detection of T cell and other antigens on SLC is not due to nonspecific binding of antibodies by Fc receptors. By using techniques designed to isolate and purify splenic M phi, we were able to obtain SLC in suspension and to demonstrate that they retain the antigens detected in situ. Thus, the human splenic SLC expresses a unique combination of antigens, histochemical properties, and cell products in common with monocytes, M phi, and T lymphocytes.

Antigens, Surface↗
PubMed1985

Monoclonal antibodies to human platelet glycoprotein IIb beta that initiate distinct platelet responses.

Hybridomas secreting monoclonal antibodies (MoAbs) to human platelet membrane glycoprotein IIb (GPIIb) were prepared by fusing cells of a mouse myeloma line to spleen cells from a BALB/c mouse immunized with purified GPIIb. Six of the hybridomas secreted MoAbs that recognized epitopes on the 23,000-dalton, disulfide-linked subunit of GPIIb, GPIIb beta. All six of these MoAbs agglutinated platelets in the absence of calcium. The agglutination titers of three of the MoAbs, however, were enhanced between 2 and 6 log2 dilutions when titrated in the presence of mmol/L of calcium. The enhancement in titer was the result of MoAb-induced platelet activation followed by platelet aggregation, a reaction that could also be initiated by the monovalent Fab fragments prepared from one of the MoAbs. The MoAbs did not significantly agglutinate platelets from patients with Glanzmann's thrombasthenia, confirming biochemical evidence that there is a paucity of GPIIb beta in the membranes of these cells. Our results show that MoAbs to epitopes on GPIIb beta initiate distinct platelet responses; therefore, they should be useful for studying the ways in which regions of surface glycoproteins are involved in platelet-platelet interactions. In addition, these reagents may prove of value in diagnosing and typing patients with Glanzmann's thrombasthenia.

Antibodies, Monoclonal↗
PubMed1984

Some fixation reagents reduce or abolish the detectability of Ia-antigen and HLA-DR on cells.

The effect of paraformaldehyde (PF), glutaraldehyde (GT), methanol (ME), ethanol (ET) and acetone (AC) fixation on the detectability of Ia antigens on murine and rat peritoneal exudate (PE) and resident peritoneal (RP) macrophages (M phi), and on detectability of HLA-DR antigens on human blood leukocytes (HBL) and human splenic M phi (HSM phi) was examined. Ia-antigen on Mø from H-2k mice was detected by a rosetting assay using erythrocytes (E) to which a monoclonal antibody (MoAb) reactive to Ia.2 (E anti-Ia.2) had been coupled, and by the direct binding of 125I-labeled anti-Ia.2. The antigen was detected on Wistar/Furth (W/Fu) rat RPMø splenocytes (SC) by rosetting with E coupled with a MoAb to the murine determinate Ia.17, which cross-reacts with an Ia-like molecule on cells from the W/Fu strain. HLA-DR framework determinants were detected on HBL and HSMø by the binding of 125I-labeled MoAb and by an avidin-biotinylated peroxidase procedure. Exposure of murine PEMø or RPMø to 1% PF or 0.5% GT for 15 min at room temperature reduced 125I-anti-Ia.2 binding and E anti-Ia.2 rosetting by at least 60%; the radioimmunoassay was more affected by the fixatives than was the rosetting assay. Further, PEMø were more sensitive to the effect of PF fixation than were RPMø. Treatment of freshly isolated RPMø with 1% PF reduced the proportion of Ia-bearing cells detected by the rosetting assay by greater than 50%. Culturing alone did not affect the detectability of Ia on RPMø as assessed by the rosetting test, but cultured RPMø were more sensitive to the effects of FX fixation than fresh cells except when lymphokine from Con A-stimulated murine SC was included in the culture medium. Similar losses of HLA-DR were recorded when HBL and HSMø were exposed to PF, GT, ME or ET, but brief (less than 20 s) treatment with cold AC did not appreciably reduce antigen detectability. Procedures in which fixation takes place after the primary antibody binding step did not result in an appreciable loss of detectable Ia. Thus, commonly used fixatives affect the detectability of Ia and Ia-like antigens on a variety of cells. Results obtained from assays on cells treated prior to the primary antibody binding step, therefore, must be interpreted with caution.

Animals↗
PubMed1984

Isolation of human splenic macrophages and lymphocytes by countercurrent centrifugal elutriation.

Certain tissues, such as the spleen, are rich sources of mononuclear phagocytes (MP); however, separating the phagocytes from tissues and removing the contaminating cells have been difficult. We report here a method for the extraction and purification of human splenic MP that employs gentle homogenization of splenic fragments with a Tenbroeck tissue homogenizer, controlled digestion with purified collagenase to free MP from splenic stroma, incubation with DNase to dissociate cell clumps and purification by countercurrent centrifugal elutriation (CCE). With homogenization and enzymatic digestion most of the splenic nonspecific-esterase-positive cells are freed into suspension as determined by morphometric analysis of 2 micron sections from plastic embedded spleen stained for alpha-naphthyl butyrate esterase (ANB). Overall cell recovery after homogenization and enzyme treatment is 56 +/- 7%; no selective cell loss occurs as determined by differential cell counts at each purification step. CCE of up to 3 X 10(9) treated spleen cells results in recovery of 63 +/- 6% of the elutriated cells and separates nearly 50% of the recovered MP into enriched fractions. These MP are morphologically intact as determined by light and electron microscopy and are actively phagocytic. Highly purified (96%) autologous splenic lymphocytes are a useful by-product of this separation technique.

Cell Count↗
PubMed1984

3AE8: monoclonal antibody defining inflammatory macrophages in three species.

A mouse monoclonal antibody (MAb 3AE8) of the IgG1 isotype was prepared against rabbit splenocytes and was found by indirect immunofluorescence and direct binding assays to react, in the rabbit, primarily with oil-induced peritoneal exudate macrophages (PEM phi). This MAb did not bind to rabbit T cells, B cells, polymorphonuclear leukocytes, or resident alveolar or peritoneal M phi but it did bind to a subpopulation of rabbit splenocytes with surface characteristics of null cells. The antibody also recognized mouse and rat PEM phi as well as the murine M phi cell lines P388D1 and IC-21. Consistent with findings in the rabbit, it did not bind to M phi obtained from the peritoneal cavities of rats or mice. The addition of MAb 3AE8 to mouse PEM phi caused a marked enhancement in the phagocytic uptake of erythrocyte target cells sensitized with a mouse antierythrocyte antiserum.

Animals↗
PubMed1984

Preferential phagocytosis of in vivo aged murine red blood cells by a macrophage-like cell line.

The ability of an established line of mouse macrophages (IC-21) to ingest red blood cells (RBC) aged in vivo was assessed. RBC populations of increasing age were prepared in mice by serial hypertransfusion, a procedure that inhibits erythropoiesis. Mouse RBC with a mean age of about 58 d (normal RBC life span, 60 d) had a circulating half-life of less than 1 d when transfused into normal mice. IC-21 macrophages ingested the in vivo aged RBC in preference to RBC from normal mice (mean RBC age, 30 d). RBC isolated from mice 10 d after being released from one red blood cell lifespan (60 d) of inhibited erythropoiesis (mean RBC age 5 d) were ingested significantly less than RBC from normal mice. The IC-21 macrophage line used with in vivo aged RBC affords a highly defined model system for identifying the mechanism(s) of macrophage-mediated homeostasis.

Animals↗
PubMed1984

Successful cardiopulmonary bypass in diabetics with anaphylactoid reactions to protamine.

Two insulin dependent diabetics with previous anaphylactic like (anaphylactoid) reactions to protamine underwent successful cardiopulmonary bypass for coronary artery surgery. Platelet concentrates instead of protamine were used to neutralise their systemic heparinisation. In both cases the anaphylactoid reactions first became apparent after administration of protamine sulphate at the end of cardiac catheterisation. These cases show that adverse reactions to protamine need not be a contraindication to cardiopulmonary bypass and cardiac surgery and emphasise that this condition should be considered in all patients with a history of previous protamine exposure or one which may be associated with anaphylactoid reactions to protamine.

Adult↗
PubMed1984

Extreme hypernatraemia in association with renal failure following caecocystoplasty.

A case of extreme hypernatraemia (serum sodium 212 mmol/l) occurring in association with renal failure following a caecocystoplasty procedure is reported. The causative factors in extreme hypernatraemia are reviewed and an unusual reabsorptive mechanism via the transposed intestinal segment is proposed to explain the degree of hypernatraemia present in this case.

Acute Kidney Injury↗
PubMed1984

Wound prophylaxis in thoracic surgery: a new approach.

A prospective double blind, randomised study was performed in 100 patients undergoing major elective thoracic surgery to assess a new method of prophylaxis of wound infection using one preincisional intraparietal infiltration of cefuroxime sodium along the line of proposed incision as the sole protection against wound infection. A significant (p less than 0.01) reduction in the incidence of wound infection occurred in the antibiotic treated group (2%) compared with the control group (20%), who received by the same route the same volume of saline only. The groups were comparable with respect to age, sex, pathological condition, and operative variables. The use of additional antibiotics was significantly greater in the control group (p less than 0.01), largely owing to a much greater incidence of postoperative pulmonary infection in the control group (60%) than in the antibiotic treated group (40%). No morbidity was associated with this technique. The organisms found in oesophageal and bronchial operative luminal specimens did not correlate with postoperative wound or pulmonary infection or with organisms causing these infections. Reductions in wound and pulmonary infection rates equivalent to those produced by conventional multiple dose parenteral regimens were achieved by this technique.

Aged↗
PubMed1984

Exocytosis and macrophage-mediated antibody-dependent cellular cytotoxicity: a cautionary note.

The appearance of soluble radioisotope from macrophages (M phi) that previously had ingested 51Cr-labelled antibody-coated sheep erythrocytes (51Cr-EA) was assessed to determine if exocytosis contributed to the pool of radioactivity used to measure antibody-dependent cellular cytotoxicity (ADCC). M phi preloaded for 60 min with 51Cr-EA lost the majority of the ingested 51Cr over a subsequent 3 hr incubation period. The exocytotic rate was independent of the number of 51Cr-EA ingested, but was temperature dependent with no appreciable release of 51Cr observed at 4 degrees. The exocytotic process was unaffected by sodium azide (10 mM) but was markedly enhanced in the presence of iodoacetate (50 mM), cytochalasin B (20 micrograms/ml) or lidocaine (0.5 mM). The results show that M phi rapidly digest engulfed target cells and that exocytosis can contribute sufficient soluble radioactivity to the extracellular pool to lead to misinterpretation of putative ADCC activity.

Animals↗
PubMed1983

Persistent expression of Ia-antigen on a subpopulation of murine resident peritoneal macrophages.

The stability of Ia-antigen expression on murine resident peritoneal macrophages was assessed during the course of in vitro culture. Contrary to published findings with radioimmunoassays and immunofluorescence assays, the cultured cells bore Ia-antigen, as shown by their rosetting with sheep erythrocytes coupled with anti-Ia.2 monoclonal antibody. In support of this finding, cultured cells presented the copolymer of glutamine, alanine, and tyrosine (GAT) to GAT-primed T lymphocytes in an Ia-dependent manner. Thus, functional Ia antigen is present on cultured macrophages. Disappearance of the antigen after fixation of macrophages with either glutaraldehyde or paraformaldehyde, a routine procedure in the radioimmunoassays and immunofluorescence assays, explains its presumed absence on cultured cells.

Animals↗