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Biomedical subjects

B Dupont

Publications and source records attributed to B Dupont.

At least 181 records · Page 10Linked to original sources
PubMed1992

Review of nocardial infections in France 1987 to 1990.

On the basis of the numbers of Nocardia strains referred to the National Reference Center for Mycoses and Antifungal Agents (NRC), Institut Pasteur, Paris, in the period from 1987 to 1990, it was estimated that between 150 and 250 cases of nocardiosis are diagnosed in France each year. A total of 63 clinical isolates were referred to the NRC and identified as Nocardia asteroides (66.7%), Nocardia farcinica (23.8%), Nocardia brasiliensis (3.2%), Nocardia otitidiscaviarum (4.8%) and Nocardia carnea (1.5%). Nocardia asteroides accounted for 71.4% of pulmonary infections, 80.0% of central nervous system infections and 80.0% of systemic infections. Patients infected with Nocardia farcinica died in 57.1% of cases, compared with 17.6% of patients infected with Nocardia asteroides. Corticosteroid therapy represented a significant factor in mortality. Isolates of Nocardia asteroides revealed variable resistance, whereas isolates of Nocardia farcinica were resistant to most antimicrobial agents. Only amoxicillin/clavulanic acid, imipenem, cefoxitin, kanamycin, amikacin, minocycline and vancomycin showed activity against both species. Nocardiosis caused by Nocardia farcinica may be a growing problem because of the relatively high incidence in AIDS patients and the resistance of this species to most antimicrobial agents.

Adult↗
PubMed1992

Cytotoxic and proliferative allospecific T-cell clones contain perforin and mediate anti-CD3-induced cytotoxicity.

Some in vitro-generated allospecific T-cell clones can kill target cells bearing specific antigen, whereas others can only proliferate in response to that antigen. The mechanism of target lysis by clones that exhibit antigen-specific cytotoxicity is thought to involve the exocytosis of lytic granules, which contain the pore-forming protein perforin. Here, CD4+, CD8+, and CD4-8- T-cell clones, positive for CD3 and the alpha/beta T-cell receptor, were tested for their ability to lyse the mouse-anti-human CD3 hybridoma OKT3; this hybridoma has been shown to trigger the cytolytic mechanism in cytotoxic T cells regardless of their clonal specificity. We found that all in vitro-generated allospecific T-cell clones can efficiently lyse the OKT3 targets whether or not they can kill alloantigen-bearing lymphoblastoid B-cell line targets. Furthermore, all tested clones contained perforin. The OKT3 hybridoma was not lysed by perforin-negative, CD3+ leukemic T-cell lines or by CD3- NK clones. Thus, the presence of perforin in T-cell clones correlated with their ability to lyse OKT3 targets, but not with their ability to lyse alloantigen-bearing targets. These results demonstrate that T-cell clones that are nonlytic when activated by specific antigen nevertheless contain a complete lytic mechanism and also support the proposed central role in perforin in that mechanism.

Animals↗
PubMed1992

Cryptococcal meningitis associated with acquired immunodeficiency syndrome (AIDS) in African patients: treatment with fluconazole.

Cryptococcal meningitis associated with acquired immunodeficiency syndrome (AIDS) is particularly common in tropical Africa. This could be explained by the dramatic increase in the number of human immunodeficiency virus (HIV) infections and the high prevalence of Cryptococcus neoformans var. neoformans in the domestic and general environment of HIV-positive and AIDS patients Meningoencephalitis is the usual and dominant clinical feature of cryptococcal infection in AIDS patients and 'slim disease', tuberculosis and candidiasis are the most common opportunistic infections associated with cryptococcal meningitis. In a group of 64 African patients with AIDS and cryptococcosis treatment with a daily dose of 400 mg fluconazole (FCA) during the acute phase showed a clinical cure in 63% of the evaluable patients. Mycological response to treatment with negative culture was found in 76% of our patients (at day 60-90). The overall tolerance of FCA was excellent. This treatment was also used successfully for relapse of cryptococcal meningitis.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Cytolytic effector function is present in resting peripheral T lymphocytes.

Antigen-specific cytotoxic killer lymphocytes (CTLs) represent one of the major effector functions of the immune system. It is well established that, as a consequence of TCR recognition of the antigen-bearing target cell, resting T lymphocytes develop into fully active antigen-specific CTLs. In contrast, natural killer (NK) cells are immediately lytic upon contact with an appropriate target cell. The lytic machinery of CTLs and NK cells is thought to include the contents of their cytoplasmic granules, in particular the pore-forming protein perforin. Here we report direct cytolytic activity by resting peripheral CD3+CD8+ T cells as a result of TCR-CD3 binding to the target cell; the murine OKT3 hybridoma (anti-human CD3) was used as a target. The cytotoxicity was more pronounced in the CD8+CD45RO+ population, which contains 'memory' T cells, than in the reciprocal CD8+CD45RA+ subset; CD8+CD4- mature thymocytes were non-cytotoxic. The cytolytic potential of these populations correlated with the presence or absence of perforin. The results demonstrate that the cytolytic machinery of T cells develops post-thymically and can be immediately triggered by TCR-CD3 stimulation.

Antibodies, Monoclonal↗
PubMed1992

A co-stimulatory role for CD28 in the activation of CD4+ T lymphocytes by staphylococcal enterotoxin B.

In this study we investigated the differential effect of the co-stimulatory receptor ligand molecules CD2/LFA-3, LFA-1/ICAM-1, and CD28/B7 on microbial superantigen mediated activation of CD4+ T cells. Highly purified CD4+ T cells, depleted of antigen presenting cells (APCs), do not proliferate in response to the superantigen, staphylococcal enterotoxin B (SEB). However, CD4+ T cells do respond to SEB in the presence of the LFA-3, ICAM-1, and B7 positive erythroleukemic cell line K562, murine L cells, human B7 transfected L cells or CD28 mAb. The K562 plus SEB induced response can be inhibited by combinations of mAbs to CD2 and LFA-1, and to LFA-3, ICAM-1, and B7. Addition of CD28 mAb to the CD2 and LFA-1 inhibited cultures could restore the response. Furthermore, soluble CD28 mAb alone is able to synergize with SEB to induce a proliferative CD4+ T cell response. CD4+ T cells depleted of APCs could also be activated by a pool of four mAbs directed to the V beta 5, V beta 6, V beta 8, and V beta 12 region of the TCR when a co-stimulatory signal was provided by the CD28 mAb, while the V beta mAbs alone or in combination are unable to activate CD4+ T cells in the absence of APCs. In contrast, addition of soluble mAbs to CD2 and LFA-1 molecules failed to co-stimulate SEB activated CD4+ T lymphocytes. The kinetics of the different modes of activation are distinct. SEB induced proliferation is most efficient in the presence of autologous APCs with maximal proliferation at a log4 lower SEB concentration than when CD28 mAbs were used. SEB plus K562 activation peaks on day 7, while SEB plus CD28 mAb induced proliferative responses do not peak until day 9. Thus, superantigen mediated activation of CD4+ T cells requires co-stimulatory signals, among which CD28 has distinct and unique effects.

Adult↗
PubMed1992

Standardized susceptibility testing of fluconazole: an international collaborative study.

An international collaborative study of broth dilution (MIC) and disk diffusion susceptibility testing of fluconazole was conducted by using a chemically defined medium (High-Resolution Antifungal Assay Medium; Oxoid Ltd., Basingstoke, United Kingdom) and standard test methods performed in eight reference laboratories. Ten yeast isolates were tested by each test method in duplicate on each of 3 separate days. The intralaboratory reproducibility of the MIC test was excellent; 95.7% of the replicate tests (n = 220) were within 2 doubling dilutions of the other values in the set for the eight laboratories. The intralaboratory reproducibility of the disk test was also good, with 91% of the replicate tests (n = 234) agreeing with each other within an arbitrarily chosen value of 4 mm. Interlaboratory agreement of MIC test results was acceptable, with 84% of the MICs agreeing within 2 doubling dilutions. In contrast, the interlaboratory agreement of the disk test was not good, with only 59% of test results agreeing within 4 mm. Comparison of the rank order of MICs obtained in each laboratory with the reference rank order gave an agreement of 70 to 80% (median, 80%) with the MIC test and 70 to 90% (median, 80%) with the disk test. These preliminary results are encouraging for the development of standardized testing methods for testing fluconazole.

Culture Media↗
PubMed1992

The B7/BB1 antigen provides one of several costimulatory signals for the activation of CD4+ T lymphocytes by human blood dendritic cells in vitro.

T cells respond to peptide antigen in association with MHC products on antigen-presenting cells (APCs). A number of accessory or costimulatory molecules have been identified that also contribute to T cell activation. Several of the known accessory molecules are expressed by freshly isolated dendritic cells, a distinctive leukocyte that is the most potent APC for the initiation of primary T cell responses. These include ICAM-1 (CD54), LFA-3 (CD58), and class I and II MHC products. Dendritic cells also constitutively express the accessory ligand for CD28, B7/BB1, which has not been previously identified on circulating leukocytes freshly isolated from peripheral blood. Dendritic cell expression of both B7/BB1 and ICAM-1 (CD54) increases after binding to allogeneic T cells. Individual mAbs against several of the respective accessory T cell receptors, e.g., anti-CD2, anti-CD4, anti-CD11a, and anti-CD28, inhibit T cell proliferation in the dendritic cell-stimulated allogeneic mixed leukocyte reaction (MLR) by 40-70%. Combinations of these mAbs are synergistic in achieving near total inhibition. Other T cell-reactive mAbs, e.g., anti-CD5 and anti-CD45, are not inhibitory. Lymphokine secretion and blast transformation are similarly reduced when active accessory ligand-receptor interactions are blocked in the dendritic cell-stimulated allogeneic MLR. Dendritic cells are unusual in their comparably higher expression of accessory ligands, among which B7/BB1 can now be included. These are pertinent to the efficiency with which dendritic cells in small numbers elicit strong primary T cell proliferative and effector responses.

Antigen-Presenting Cells↗
PubMed1992

[Stimulation of the prostate growth in rats by milk casomorphins].

Thymidine kinase activity of the ventral prostate from adult rats could be stimulated by administration to the animal of casomorphin or casomorphin (morphiceptin). On the other hand addition of both drugs to the culture medium of prostatic cells from immature rats enhanced the cells growth. In both cases, morphiceptin was more efficient than casomorphin. These results suggest than casomorphins have other properties than their morphinomimetic effects previously described.

Animals↗