PubMed Health⌕ Search

Biomedical subjects

I Bernard

Publications and source records attributed to I Bernard.

At least 19 recordsLinked to original sources
PubMed2001

Cellular and genetic factors involved in the difference between Brown Norway and Lewis rats to develop respectively type-2 and type-1 immune-mediated diseases.

The understanding of the mechanisms of immune tolerance and the unravelling of the pathophysiology of autoimmune diseases rely on animal models. In this respect, BN and LEW rats represent models of choice to study immune-mediated diseases from the cellular and genetic points of view. Indeed, BN and LEW rats are extremes with respect to their polarisation of the immune response as well as their susceptibility to autoimmune diseases. LEW rats are susceptible to Th1-mediated autoimmune diseases while BN rats are highly susceptible to Th2-mediated autoimmune disease. Comparison of the T cell compartment between LEW and BN rats revealed several important differences. 1) A MHC-dependent quantitative difference that is due to a defect in the CD8 T cell compartment in BN rats. 2) A qualitative MHC-independent difference that is related to a high frequency of CD45RClow CD4 and CD8 T cell subsets, producing IL-4, IL-13, IL-10 and TGF-beta in BN rats as compared to LEW rats. 3) Interestingly, the genetic studies showed that susceptibility to Th1-mediated experimental autoimmune encephalomyelitis, and to Th2-mediated disorders triggered by gold salts as well as the difference in the CD4SRChigh/CD45RClow ratio between LEW and BN rats are genetically determined by regions on chromosomes 9, 10 and 20.

Animals↗
PubMed2001

Essential role of TGF-beta in the natural resistance to experimental allergic encephalomyelitis in rats.

Experimental allergic encephalomyelitis (EAE) is a T cell-mediated autoimmune disease induced in susceptible rat strains by a single immunization with myelin basic protein (MBP). The Lewis (LEW) strain is susceptible to disease induction while the Brown Norway (BN) strain is resistant. This resistance involves non-MHC genes since congenic BN-1L rats, with LEW MHC on a BN-derived background, are also resistant. In the present study we show that, upon immunization with MBP, the non-MHC-encoded resistance to develop clinical EAE in BN-1L rats is associated with a decreased production of IFN-gamma. This may be due to a difference between LEW and BN-1L rats in their ability to produce regulatory cytokines such as IL-4, IL-10 and TGF-beta. In comparison to LEW rats, immune lymph node cells from BN-1L rats express an increased amount of IL-4 mRNA but produce less IL-10. Furthermore, the sera from BN-1L rats contain higher amounts of active TGF-beta1. Therefore, we have investigated the involvement of IL-4 and TGF-beta in the resistance of BN-1L rats to develop EAE using neutralizing mAb. Neutralization of TGF-beta, but not IL-4, renders BN-1L rats susceptible to clinical EAE without affecting the proliferation or the cytokine repertoire of immune lymph node cells. With respect to the origin of the endogenous TGF-beta production, we excluded the involvement of CD8 T cells and discuss a possible role of platelets and of CD4 T cells exhibiting the CD45RC(low) phenotype.

Animals↗
PubMed2000

[Impact of an information booklet on patient satisfaction in anesthesia].

OBJECTIVE: The aim of this study was to evaluate the satisfaction of adult surgical patients before and after an information booklet concerning anaesthetic techniques and complications, and postoperative management has been proposed during preanaesthetic visits. STUDY DESIGN: Survey. METHOD: Three surveys have been performed using an anonymous questionnaire of 25 items with graduated answers (very good, good, bad, very bad, no opinion) concerning patient satisfaction on structure, physician behavior, information and well being. As the results of the first two surveys were not significantly different, an information booklet was proposed to patients during preanaesthetic visits, then a third survey ("After") was realized. The results of this survey were compared to the combined results of the first two surveys ("Before"). RESULTS: In the "before" survey, 60 to 76% of the patients were satisfied (very good and good) of the information delivered during preanaesthetic visits. The proportion of patients satisfied of the information concerning anaesthetic techniques, transfusion and recovery were significantly higher in the "after" survey (P < 0.05). CONCLUSION: An information booklet on anaesthesia increases patient satisfaction on information provided during preanaesthetic visits.

Adult↗
PubMed1999

A dominant role for the thymus and MHC genes in determining the peripheral CD4/CD8 T cell ratio in the rat.

During their development, immature CD4CD8 double positive thymocytes become committed to either the CD4 or CD8 lineage. The final size of the peripheral CD4 and CD8 T cell compartments depends on thymic output and on the differential survival and proliferation of the respective T cell subsets in the periphery. Our results reveal that the development of the distinct peripheral CD4/CD8 T cell ratio between Lewis and Brown Norway rats originates in the thymus and, as shown by the use of radiation bone marrow chimeras, is determined by selection on radio-resistant stromal cells. Furthermore, this difference is strictly correlated with the MHC haplotype and is the result of a reduction in the absolute number of CD8 T cells in Brown Norway rats. These data suggest that the distinct CD4/CD8 T cell ratio between these two rat strains is the consequence of differential interactions of the TCR/CD8 coreceptor complex with the respective MHC class I haplotypes during selection in the thymus.

Animals↗
PubMed1999

Experimental autoimmune myasthenia gravis may occur in the context of a polarized Th1- or Th2-type immune response in rats.

Experimental autoimmune myasthenia gravis (EAMG) is a T cell-dependent, Ab-mediated autoimmune disease induced in rats by a single immunization with acetylcholine receptor (AChR). Although polarized Th1 responses have been shown to be crucial for the development of mouse EAMG, the role of Th cell subsets in rat EAMG is not well established. In the present work we show that while the incidence and severity of EAMG are similar in Lewis (LEW) and Brown-Norway (BN) rats, strong differences are revealed in the immune response generated. Ag-specific lymph node cells from LEW rats produced higher amounts of IL-2 and IFN-gamma than BN lymph node cells, but expressed less IL-4 mRNA. IgG1 and IgG2b anti-AChR isotype predominated in BN and LEW rats, respectively, confirming the dichotomy of the immune response observed between the two strains. Furthermore, although IL-12 administration or IFN-gamma neutralization strongly influenced the Th1/Th2 balance in BN rats, it did not affect the disease outcome. These data demonstrate that a Th1-dominated immune response is not necessarily associated with disease severity in EAMG, not only in rats with disparate MHC haplotype but also in the same rat strain, and suggest that in a situation where complement-fixing Ab can be generated as a consequence of either Th1- or Th2-mediated T cell help, deviation of the immune response will not be an adequate strategy to prevent this Ab-mediated autoimmune disease.

Animals↗
PubMed1999

Peripheral myelin modification in CMT1B correlates with MPZ gene mutations.

Morphological modifications were investigated in the peripheral nerve of three unrelated patients with CMT1B. In two patients, molecular genetic analysis showed an Arg98His mutation in the extracellular domain of MPZ, associated with irregularly uncompacted lamellae. This observation confirms previous studies of a well-defined correlation between mutations and morphological phenotypes. In the third patient, a de novo Asp109Asn mutation was associated with abnormally thick myelin sheaths. This adds to the known list of MPZ gene mutations associated with this morphological phenotype.

Adult↗
PubMed1999

Pleuro-pulmonary tumours detected by clinical and chest X-ray analyses in rats transplanted with mesothelioma cells.

New strategies for cancer therapy must be developed, especially in severe neoplasms such as malignant pleural mesothelioma. Animal models of cancer, as close as possible to the human situation, are needed to investigate novel therapeutical approaches. Orthotopic transplantation of cancer cells is then relevant and efforts should be made to follow up tumour evolution in animals. In the present study, we developed a method for the orthotopic growth of mesothelioma cells in the pleural cavity of Fischer 344 and nude rats, along with a procedure for clinical survey. Two mesothelioma cell lines, of rat and human origin, were inoculated by transthoracic puncture. Body weight determination and chest X-ray analyses permitted the follow-up of tumour evolution by identifying different stages. Autopsies showed that tumours localized on the whole pleural cavity (diaphragm, parietal pleura), mediastinum and pericardium. Tumour morphology and antigenic characteristics were consistent with those of the inoculated cells and were similar in both types of rats inoculated with the same cell type. These results demonstrate that mesothelioma formation in rats can be followed up by clinical and radiographic survey after gentle intrathoracic inoculation of mesothelioma cells, thus allowing the definition of stages of interest for further experimental trials.

Animals↗
PubMed1998

Flow cytometric analysis of intracellular interferon-gamma synthesis in rat CD4 T cells.

To date the techniques used to analyse cytokine expression by rat T cells do not give information about the simultaneous production of different cytokines from individual cells. Recently, a method for analysing the intracellular production of cytokines at the single cell level using flow cytometry has been developed. It is well established that the most critical requirement for successful intracellular cytokine staining is the availability of appropriate antibodies. In rat, it is possible to stain for intracellular IL-4 and IL-10 (Th2 cytokines) using the commercially available antibodies but not for Th1 cytokines. In the present work, we show that DB1, a mouse anti-rat IFN-gamma monoclonal antibody, could be used for intracytoplasmic staining of IFN-gamma producing rat CD4 T cells. The specificity of the staining was confirmed using a molar excess of unlabelled antibodies or recombinant cytokine. Finally, intracellular staining for IFN-gamma correlates with cytokine production in culture supernatant as evaluated by ELISA analysis.

Animals↗
PubMed1997

Transforming growth factor beta (TGF-beta)-dependent inhibition of T helper cell 2 (Th2)-induced autoimmunity by self-major histocompatibility complex (MHC) class II-specific, regulatory CD4(+) T cell lines.

Autoreactive anti-MHC class II T cells are found in Brown Norway (BN) and Lewis (LEW) rats that receive either HgCl2 or gold salts. These T cells have a T helper cell 2 (Th2) phenotype in the former strain and are responsible for Th2-mediated autoimmunity. In contrast, T cells that expand in LEW rats produce IL-2 and prevent experimental autoimmune encephalomyelitis, a cell-mediated autoimmune disease. The aim of this work was to investigate, using T cell lines derived from HgCl2-injected LEW rats (LEWHg), the effect of these autoreactive T cells on the development of Th2-mediated autoimmunity. The five LEWHg T cell lines obtained protect against Th2-mediated autoimmunity induced by HgCl2 in (LEW x BN)F1 hybrids. The lines produce, in addition to IL-2, IFN-gamma and TGF-beta, and the protective effect is TGF-beta dependent since protection is abrogated by anti-TGF-beta treatment. These results identify regulatory, TGF-beta-producing, autoreactive T cells that are distinct from classical Th1 or Th2 and inhibit both Th1- and Th2-mediated autoimmune diseases.

Adoptive Transfer↗
PubMed1997

Hemostasis parameters during ovarian stimulation for in vitro fertilization: results of a prospective study.

OBJECTIVE: To evaluate the effect of IVF-ET on the hemostatic system. DESIGN: Prospective clinical study. SETTING: Apparently healthy age-matched women of the hospital staff at various stage of the menstrual cycle. PATIENT(S): Twenty-five women involved in a IVF-ET program at the Department of Obstetrics and Gynecology, Montpellier University Hospital. INTERVENTION(S): Twenty-six hemostasis parameters evaluated repeatedly in patients undergoing IVF-ET. MAIN OUTCOME MEASURE(S): Blood cell-dependent hemostasis parameters and plasmatic coagulation factors, determined at pituitary desensitization, maximal E2 level, and P plateau. RESULT(S): Activation of the hemostatic system is evidenced at the P plateau, when D-dimers and fragments 1 + 2 of the prothrombin levels rose dramatically. At E2 peak, no significant modification of hemostasis markers was noted. CONCLUSION(S): The present results indicate that ovarian hyperstimulation may induce hemostasis activation at the P plateau. The role of supraphysiologic sex hormone levels on the hemostatic system requires further investigation.

Adult↗
PubMed1996

Human lymphocytes shed a soluble form of CD21 (the C3dg/Epstein-Barr virus receptor, CR2) that binds iC3b and CD23.

We report on a soluble (s) form of CD21 (the C3dg/Epstein-Barr virus receptor, CR2) that is spontaneously released by B and T lymphocytes. Immunoprecipitation with anti-CD21 mAb of culture supernatants of surface and biosynthetically labeled B and T cell lines revealed a single band with an apparent molecular mass of 135 kDa. The molecule exhibited a molecular mass 10 kDa lower than that of membrane CD21. The release of soluble CD21 (sCD21) was time dependent and correlated with a parallel decrease in the expression of the membrane-associated molecule. The protein was also found in culture supernatants of tonsillar B cells and normal human thymocytes. Epitopic analysis using combinations of anti-CD21 monoclonal antibodies (mAb) indicated that sCD21 and membrane CD21 were similarly recognized by mAb directed against short consensus repeats (SCR) 1-2, SCR 4-5 and SCR 9-11. Affinity-purified sCD21 was capable of binding to purified human iC3b and to human recombinant CD23, as assessed by enzyme-linked immunosorbent assay and by using the BIAcore technology. In addition, normal human serum was found to contain a soluble form of CD21 that exhibited a similar molecular mass to that of the molecule shed by B and T cells in culture. The serum form of CD21 was recognized by all anti-CD21 mAb that we tested and showed a high reactivity with mAb directed against SCR 1-2. Our observations suggest that B and T cells shed the extracellular portion of CD21 and release a soluble molecule that retains the ligand-binding properties of CD21, thus having a potential role in immunoregulation.

B-Lymphocytes↗
PubMed1993

[Metastases in the cauda equina in visceral cancers. Apropos of 2 cases].

Two new cases of cauda equina metastases from visceral cancers are reported. This diagnosis is only infrequently considered in patients with intra-dural lesions visualized by magnetic resonance imaging or saccoradiculography. The diagnosis is especially difficult in patients with no known primary cancer. Diagnosis rests on surgery during which only a biopsy is performed. Treatment is symptomatic and focuses on relieving pain. Prognosis is bleak.

Adenocarcinoma↗
PubMed1992

[Therapy of stomach ulcer--a comparison between the low dosage antacid hydrotalcite and ranitidine--results of a randomized multicenter double-blind study. Talcivent Study Group].

In a 8 week double-blind randomized multicenter trial in 159 patients with benign gastric ulcer the efficacy of hydrotalcite vs. ranitidine in expediting ulcer healing and in achieving pain relief was determined. 79 patients received hydrotalcite 1000 mg q.i.d. as tablets equalling a total neutralizing capacity of 111.2 mval and 80 patients received ranitidine (300 mg at night). Endoscopically controlled healing rates after 4 weeks of therapy amounted to 41.8% with hydrotalcite and 53.8% with ranitidine. After 8 weeks both regimen showed significant equivalent healing rates (hydrotalcite: 81.0%, ranitidine: 78.8%, p < 0.003). Ulcer pain decreased parallel in both groups. By the end of therapy 92.4% of the patients treated with hydrotalcite and 86.3% of those receiving ranitidine were free of pain. Incidence of helicobacter pylori in antral mucosal biopsies was not influenced by both treatments. We conclude that an 8-week treatment with low dose hydrotalcite therapy is as effective as ranitidine in healing benign gastric ulcers and achieving pain relief.

Adult↗
PubMed1977

[Treatment of the menopause].

The immediate complications of the menopause should be treated. These symptoms must be due to the menopause and the treatment should be without side effects. The object is above all to obtain a sense of well-being. More important than the immediate signs are the later trophic disorders, whether local or general. Thus a long term substitution treatment may be considered under strict supervision.

Estrogens↗