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Biomedical subjects

E B Bell

Publications and source records attributed to E B Bell.

At least 73 records · Page 4Linked to original sources
PubMed1985

Induction of an auto-anti-IgE response in rats I. Effects on serum IgE concentrations.

With a view to specifically suppressing the IgE isotype, rats of high (BN) and low (PVG.RT1u) IgE-responding phenotypes were immunized with a highly purified rat IgE myeloma (IR2) in an attempt to induce an anto-anti-IgE response. Rat IgE antibodies against epsilon determinants were detected in the serum of IR2-immunized animals using a solid-phase (plate) radioimmunoassay. The auto-anti-IgE antibodies detected were found to bind to IR2, to a second rat IgE myeloma (IR162) and to mouse monoclonal IgE but not rat IgG. The specificity of the anti-epsilon binding was shown by inhibition studies. The raising of an auto-anti-IgE response in PVG.RT1u rats severely depleted the serum level of circulating IgE for at least 8 weeks. In BN rats, immunization with IR2 caused marked fluctuations in serum IgE levels. The rats in both strains remained healthy throughout the experiment. The rate and route of IgE break down was not altered in anti-IgE-producing rats. The relevance of the present model in understanding and possibly controlling allergic disorders is considered.

Animals↗
PubMed1984

Antigen transport II. The significance of the localization of antigen-laden cells in the spleen.

Previous studies have demonstrated that macrophage-like cells transporting antigen, e.g., human serum albumin (HSA) appear in thoracic duct lymph and blood shortly after antigen injection. The in vivo migration of these antigen-laden (Ag-L) cells from the blood stream was examined systematically by transferring Ag-L cells bearing 125I-labelled HSA into syngeneic rats. There was no evidence autoradiographically that Ag-L cells migrated into lymph nodes, but the localization in the spleen followed a defined pattern: within the first hours after transfer, a majority of radiolabelled cells were identified in the marginal zone; by 3 hr and up to 4 days later, 60-80% of labelled cells were resident in the red pulp; Ag-L cells failed to migrate into the white pulp in significant numbers. Ag-L cells which had localized to the spleen, when examined 3 and 18 hr after transfer using combined autoradiography and immunoperoxidase staining, did not express Ia determinants in situ. The ability of Ag-L cells to stimulate an adoptive secondary response was tested in splenectomized, irradiated recipients receiving HSA-specific memory cells. Removal of the spleen before transfer severely reduced the antibody response evoked by Ag-L cells transporting HSA, thus indicating the functional importance of antigen transport to the spleen. Since Ag-L cell migration was primarily into the red pulp, we have considered whether the red pulp may provide a relevant microenvironment for lymphocyte/antigen interaction.

Animals↗
PubMed1983

In vitro antibody synthesis in 20 microliters hanging drops: initiation of secondary responses and a simple method of cloning hybridomas.

An in vitro culture system is described in which antibody synthesis is initiated by 10(5) hapten-primed spleen cells in 20 microliters hanging drops. Plaque-forming cell (PFC) responses to thymus dependent and thymus independent antigens were obtained in drop cultures comparable to the micro Mishell--Dutton system. Antigens could be administered in soluble form or on antigen-pulsed peritoneal cells. The hanging drop method also provides a reliable yet simple procedure for cloning hybridoma cells while permitting direct visualization of the number of cells in each drop.

Animals↗
PubMed1982

Antigen transport. I. Demonstration and characterization of cells laden with antigen in thoracic duct lymph and blood.

Thoracic duct lymph (TDL) of nonimmune rats and mice was examined for the presence of antigen-carrying cells immediately following a single injection of 125I-labelled or fluorescence-labelled serum protein antigens. Small numbers of cells laden with antigen (approximately 1/2000 to 1/5000) were identified in TDL and blood by autoradiography or fluorescence microscopy. The antigen-laden (Ag-L) cells resembled macrophages in that a large number adhered to plastic, they phagocytosed bacteria or a particulate dye, were non-specific esterase positive, radioresistant and could take up more than one antigen at one time in vivo. Surface phenotyping using monoclonal antibodies against rat cell markers established that Ag-L cells did not express Ia determinants. The results suggest the existence of a subpopulation of macrophage-related cells that may be involved in the transport of antigen and in stimulation of antibody responses.

Animals↗
PubMed1980

The assay on a defined medium of the effects of beta-2-thienylalanine on the growth of anaerobic bacterial isolates from phenylketonuric patients.

Faecal samples were taken from three diet-managed phenylketonuric children to determine effects of beta-2-thienylalanine (beta-2-t) on indigenous bacteria. From sample swabs, 127 anaerobes were identified and tested for beta-2-t inhibition on a phenylalanine (Phe)-free medium, Anaerobe Inhibition Test (AIT) agar. Of the isolates, 77.9% grew sufficiently to assay reactions on at least 25% of AIT plates. Using Phe-containing Columbia agar, 86.5% of the strains could be assayed. None of 28 Bacteroides cultures was inhibited by beta-2-t on AIT. Of the genera, Bifidobacterium, Eubacterium, Lactobacillus, Peptostreptococcus, and Propionibacterium, no isolates which would grow on AIT were inhibited. At least one isolate of each of the genera Peptococcus, Fusobacterium, and Clostridium was inhibited. Of 127 total isolates, only nine were inhibited by beta-2-t on AIT, and inhibition was abolished on Columbia agar. Thirty-nine "aerobes" were isolated from the same patients. Strains of the genera tested reacted similarly to previously tested strains from non-PKU sources. Also, anaerobically isolated Excherichia coli were inhibited, while Streptococcus faecalis cultures were not, confirming results on aerobically-isolated non-PKU cultures of the same species. These studies, the first dealing with beta-2-t and anaerobic bacteria, suggest that little change in intestinal bacterial populations might be expected during in vivo beta-2-t treatment.

Agar↗
PubMed1980

The architecture of rat lymph nodes. III. The lymph nodes and lymph-borne cells of the congenitally athymic nude rat (rnu).

The lymph nodes (LN) of the congenitally athymic nude rat(rnu) were compared with the LN of non-nude littermates. The mesenteric and coeliac LN were smaller in the rnu rats, but the axillary and the cervical LN were larger. Germinal centres were found in the LN of nude rats. They were scarce and often very small, but some were of normal structure, especially in the cervical LN. The endothelium of post-capillary venules in the LN or normal rats, was seen. The paracortex was extremely depleted of lymphocytes but remained a distinct area occupied predominantly by pale interdigitating cells. In some LN the medullary sinuses were distended and the cords engorged with plasma cells. The predominant cells in thoracic duct lymph were immunoglobulin-positive B lymphocytes. The hourly output of these cells was the same as that in non-nude littermates. However, small numbers of thoracic duct cells were positive for the markers identified by the monoclonal antibodies W3/13 and W3/25, although in normal rats these are not expressed on small B lymphocytes.

Animals↗
PubMed1980

Summary of a project comparing student performance forms.

This paper is a summary of a pilot project designed to provide data which would lead to more effective methods of evaluating field work performance of occupational therapy students in Canada. Three evaluation forms were selected for comparison. A quantitative-descriptive type of research was utilized and a questionnaire to occupational therapy clinicians and students was the method used for data collection. The three major findings were: i) that the American Occupational Therapy Association Field Work Performance Report Form was the most complete form in evaluating student performance in specific skill areas; ii) the Queen's University Occupational Therapy Clinical Training Report Form contained essential components concerning interaction skills; and iii) the Canadian Association of Occupational Therapy Report of Clinical Training was in need of major revisions if its use was to be continued. This paper includes an outline of the results and the major limitations of the pilot project; however, the conclusions and recommendations arising from the project are the main focus of discussion.

Canada↗
PubMed1980

Muriel Driver Memorial Lecture 1980--Directions for the decade.

Following an introductory summary of role theory, this paper examines one element of professional development -- that of ROLE NEGOTIATION. Research findings as outlined which provide evidence of the need for developing role negotiation skills within the occupational therapy profession in Canada. The paper describes four role strategies which can be used to professional advantage, as therapists negotiate their roles. The final emphasis is on the positive professional implications of effective role negotiations in the 80's.

Canada↗
PubMed1979

Lymphocyte traffic within the bone marrow and selective retention of alloreactive cells.

Earlier studies showed that large numbers of isotopically labelled thoracic duct lymphocytes (TDLs) enter the bone marrow (BM) within hours of injection but depart equally as rapidly by 12 to 24 hr. The significance of this rapid flux was investigated further. Early (1/2 to 2 hr) after the i.v. injection of TDLs, BM was shown to contain T cells capable of initiating a graft-versus-host (GVH) reaction in F1 hybrids and in other experiments memory cells against human serum albumin (HSA). Both GVH and memory cell activity had markedly declined in the BM by 12 hr. In contrast to the rapid departure of TDLs from syngeneic BM, F1 hybrid BM retained parental lymphocytes with GVH activity for alloantigens of the opposite parent. F1 hybrid BM under these circumstances supported the transformation and proliferation of lymphocytes activated in situ by alloantigens. These selectively retained T cells also reacted to third-party alloantigens. In addition, TDLs with memory for HSA were retained in the BM of F1 hybrids. The BM is a site in which alloreactive immune responses may be initiated or sustained.

Animals↗
PubMed1977

Cellular events in protein-tolerant inbred rats. IV. The mechanism of immunogen-maintained tolerance.

The ability of immunogens to maintain or extend a state of unresponsiveness was investigated in unbred rats using a human serum albumin (HSA) model of tolerance. Rats initially challenged with immunogen within two weeks of high or low dose tolerance induction by tolerogen (soluble HSA) remained hyporesponsive even a year and a half later and in some cases became less responsive following a subsequent challenge. An inhibitory effect of immunogen on escape from tolerance was formally demonstrated: in comparison with an unchallenged group, tolerant rats which received a second immunogen challenge 6 months after the first, synthesized less antibody; this antibody underwent a gradual decline in affinity after each challenge which suggested that higher avidity B cells were progressively lost. In addition, immunogen-maintained tolerant rats (a) had demonstrable helper T cell activity among their thoracic duct lymphocytes on adoptive transfer, (b) did not produce a significant increase in antibody synthesis after receiving peripheral T cells and (c) provided no evidence that suppressor cells were playing a role. The results suggested that the mechanisms of tolerance induction by tolerogen and tolerance maintenance by immunogen are fundamentally different.

Adjuvants, Immunologic↗
PubMed1977

The adoptive secondary response to human serum albumin under conditions of high antigen pressure. The response of high and low avidity B cell subsets.

Thoracic duct lymphocytes (TDL) from (AS2 x AS)F1 rats previously injected with human serum albumin (HSA) were transferred to 900 r irradiated syngeneic recipients which were challenged with various doses of soluble HSA (s-HSA). TDL from partially tolerant rats, which were deficient in high avidity B cells, produced a maximum PFC response to the largest challenge dose (1 g s-HSA). In contrast, high avidity B cells from primed donors were optimally stimulated by 1 microgram and maximally inhibited by 1 mg s-HSA (day 7 PFC). An additional increase in antigen concentration by 1000 fold failed to diminish the PFC numbers further. Plaque inhibition profiles indicated that these antibody forming cells resisting inhibition were of the same high avidity as those triggered by low doses of antigen. The inability of s-HSA to completely inhibit antibody synthesis is discussed with regard to current views on B cell inactivation. Evidence is also presented which indicates that the standard haemolysis-in-gel test may fail to detect many low avidity antibody forming cells to proteins.

Animals↗