Search PubMed⌕ Search

Biomedical subjects

J Bienvenu

Publications and source records attributed to J Bienvenu.

At least 19 recordsLinked to original sources
PubMed1999

Autoantibodies directed against the ribosomal P proteins are not only directed against a common epitope of the P0, P1 and P2 proteins.

The autoantibodies (aAbs) directed against the ribosomal P proteins (RPP aAbs) are known to react mainly against epitopes localized within the common C-terminal sequence of the three acidic ribosomal P proteins, P0, P1 and P2. In order to investigate the opportunity to select short recombinant peptides of this common C-terminal sequence to detect the RPP-aAbs, the location of the epitopes recognized by ribosomal proteins (RP) aAb(+)sera of systemic lupus erythematosus patients (SLE) was investigated. Immunoblotting and ELISA techniques using extracted or recombinant, entire or cleaved RPP showed that 55% of the RP aAbs were directed against the three ribosomal P0, P1, and P2 proteins. The epitopes recognized by the RPP aAbs are located not only within the C-terminal sequence common to the three proteins but also within the N-terminal sequence of the P2 or P1 protein. The other RP aAbs sera (45%) did not react with all three proteins but with some of them, and showed the following pattern: P0(+)P1(+); P1(+); P2(+); P0(+)and P1(+). They recognized epitopes located in the region of the C-terminal sequence of the protein but not common to the three proteins. In addition two out of the six monoclonal Abs produced by immunization of mice using the P1 protein did not react with the peptide N-65 or N-71 of the P2 protein or with the C-terminal sequence of the three proteins. In conclusion, this study showed that the RPP aAb in SLE patients are not only directed against epitopes within the C-terminal sequence shared by the three acidic ribosomal P proteins. In view of these data it seems necessary to be cautious in using only a C-terminal peptide of ribosomal P proteins in tests performed to detect RPP aAb in human sera.

Amino Acid Sequence↗
PubMed1999

Multicenter evaluation study on a new HEp2 ANA screening enzyme immune assay.

The COBAS Core HEp2 ANA enzyme immune assay (EIA) was evaluated in a precision and a clinical sample study in comparison to indirect immunofluorescence assay (IFA) on HEp2-cells. In the precision study the COBAS Core EIA yielded intraassay coefficient variations (CVs) mostly below 9%, and interassay CVs between 4.7% and 10.4%. When comparing the COBAS Core EIA to IFA, the results corresponded well in healthy subjects, systemic lupus erythematosus, mixed connective tissue disease and rheumatoid arthritis. In the case of Sjögren's syndrome and scleroderma patients the COBAS Core EIA yielded a lower rate of positive results compared to IFA. This discrepancy may be explained by the lack of detection of autoantibodies to nuclear antigens that can be identified only by IFA due to their compartmentalization and higher localized antigen density in HEp2 cells. The discrepancies in the group of dermato/polymyositis patients are due to the fact that the EIA contains mainly nuclear antigens and was able to detect only antibodies against the cytoplasmic Jo1 antigen that was added to the HEp2 nuclear extract. Routine sera were also evaluated; good agreement was found in sera from patients attending tertiary reference centres for autoimmune diseases but a higher number of discrepancies was reported in sera from unselected populations.

Adult↗
PubMed1999

Laboratory data in healthy volunteers: reference values, reference changes, screening and laboratory adverse event limits in Phase I clinical trials.

OBJECTIVE: Laboratory data are key evaluation procedures for Phase I clinical pharmacology for two reasons. Firstly, laboratory data are used within the screening process to exclude subjects with asymptomatic diseases, which could result in increased danger to themselves or confuse interpretation of the study results. Secondly, during study implementation, safety evaluation and in particular maximum tolerated dose determination have to be done by a case-by-case analysis, sometimes using laboratory adverse events (LAEs). Thus, relevant limits are needed to discriminate between a usual common variation and a significant abnormality, which is considered to be a LAE. This report presents laboratory data distribution, reference values and reference changes and, based on previously published new methods, suggests inclusion limits at screening and laboratory adverse event limits for analysis during study implementation. SUBJECTS AND METHODS: Nine hundred and twenty-seven young healthy male volunteers were recruited in one centre (Association de Recherche Thérapeutique). A standard screening process was carried out. Protocols were approved by the local ethics committee. Blood sampling was performed in the same conditions. Reference values (at screening and at baseline) were determined by a non-parametric procedure selecting 2.5% and 97.5% of the distribution of data. Reference changes were also defined as the 2.5-97.5% interval of distribution of the variations between the end of treatment and baseline. Inclusion limit and LAE limit methods of determination used had been specified in previous articles. RESULTS: Detailed results of laboratory data distribution, reference values at screening and at baseline, reference changes, inclusion limits and LAE limits are presented in tables with number of subjects, mean, median, standard deviation, minimal and maximal values and the 2.5-97.5% interval for each laboratory parameter. CONCLUSION: The key aims of this paper are to provide clinical pharmacologists with data, reference values or changes obtained in the real conditions of Phase I study implementation, and to propose relevant limits, either for screening as inclusion limits, or during studies as LAE limits. Thus, these data, reference values and specific limits improve the capacity to screen healthy volunteers and to analyse LAEs during Phase I studies.

Adult↗
PubMed1999

Profiles and prognostic values of LDH isoenzymes in patients with non-Hodgkin's lymphoma.

Serum lactic dehydrogenase (LDH) is an important prognostic factor in patients with non-Hodgkin's lymphoma (NHL). We have examined the LDH isoenzyme content in serum and CSF of patients with NHL, at diagnosis and at relapse. In patients with increased serum LDH at diagnosis, the percentage of isoenzyme 2 was increased in 52% of patients and the absolute value of isoenzyme 3 was increased in 64% of patients. In relapsing patients these values were respectively 69% and 65%. Conversely in patients with increased serum LDH due to myeloid regeneration after chemotherapy, isoenzymes 4 and 5, but not isoenzymes 2 or 3, were increased. High absolute values of isoenzyme 3 were correlated with an altered performance status, advanced tumor stage, and aggressive histology whereas high isoenzyme 2 percentages were correlated with altered performance status only. Among patients with high total serum LDH, a high content of isoenzyme 2 and a high absolute value of isoenzyme 3 were correlated with high serum levels of TNFalpha and TNF receptor p75. Analysis of total LDH and LDH isoenzyme profiles in CSF did not reveal any correlation with meningeal involvement by lymphoma. High isoenzyme 2 percentages and high absolute values of isoenzyme 3 in serum were both significantly associated with a shorter freedom-from-progression and overall survival. Isoenzyme 3 remained a prognostic factor for survival even when considering only patients with high total serum LDH at diagnosis. We conclude that there are some characteristic serum LDH isoenzyme profiles in patients with NHL and that some of these specific alterations may help refine the prognostic value of total serum LDH.

Adolescent↗
PubMed1999

Detection of allergen-induced basophil activation by expression of CD63 antigen using a tricolour flow cytometric method.

In the field of allergy diagnosis, most in vitro functional tests are focused on basophils. Nevertheless, the very small number of circulating basophils limits these experiments and their clinical benefit remains controversial. As flow cytometry is a valuable tool for identifying cell populations, even at low concentrations, we developed a tricolour flow cytometric method for the study of allergen-induced basophil activation. Identification of cells was based both on CD45 expression and on the presence of IgE on the cell surface, since basophils express high-affinity receptors for IgE (Fc epsilon RI). Cell activation upon allergen challenge was assessed by the expression of CD63 antigen on the plasma membrane. Basophil isolation and activation (with the chemotactic peptide formyl-methionyl-leucyl-phenylalanine) were validated in 32 non-allergic patients. In 12 allergic patients, basophil stimulation by a relevant allergen was in most cases positive (10/12). Furthermore a concentration-dependent hook effect was observed. Of the allergic and non-allergic patients, none showed non-specific activation with an irrelevant allergen (specificity 100%). Overall, our preliminary results, even in a small population, suggest that this is a reliable and valuable method for the diagnosis of allergies complementing specific allergen IgE and skin test results. Obviously, additional clinical studies are needed to validate these first results.

Adolescent↗
PubMed1999

Fas and Fas ligand expression in cystic fibrosis airway epithelium.

BACKGROUND: Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and defective expression of CFTR protein in epithelial cells. The main cause of mortality in CF is linked to chronic inflammatory and infectious airway processes. Recent studies have suggested perturbations in the apoptotic process in CF cell lines and enterocytes. A study was undertaken to investigate the expression of Fas and Fas ligand (FasL) in CF bronchial epithelium and CF tracheal cell lines. METHODS: Immunohistochemical staining for Fas (alkaline phosphatase anti-alkaline phosphatase) and FasL (immunoperoxidase) was performed in eight CF bronchial epithelial samples and four controls and immunohistochemical DNA fragmentation (TUNEL) was carried out in four CF patients and four controls. Immunofluorescence staining and flow cytometric analysis of Fas and FasL expression was performed in two human tracheal epithelial cell lines (HTEC) with normal and CF genotype. The dosage of serum soluble FasL was examined in 21 patients with CF and 14 healthy volunteers. RESULTS: FasL expression was markedly increased in patients with CF in both the ciliated and submucosal glandular bronchial epithelium compared with controls; Fas was similarly expressed in bronchial samples from controls and CF patients in both the ciliated epithelium and submucosal glands. High levels of DNA fragmentation were observed in CF but with some epithelial cell alterations. Serum concentrations of soluble FasL were frequently undetectable in patients with CF. In vitro, HTEC expressed Fas and FasL in both genotypes. A higher mean fluorescence intensity for FasL expression was noted in CF genotype HTEC with median (range) for six experiments of 74 (25-101) for CF cells and 42 (21-70) for non-CF cells. CONCLUSION: Fas/FasL interaction is probably implicated in the human CF airway apoptotic pathway. The mechanisms of induction of FasL expression and its role in inducing tissue damage or remodelling or in controlling local inflammatory cell apoptosis remain to be determined.

Adolescent↗
PubMed1999

Evaluation of an automated immunoassay method for cytokine measurement using the Immulite Immunoassay system.

Cytokines are key mediators in cell regulation and communication. The concentration of these proteins can rapidly and importantly increase during severe clinical situations. However, current techniques are not adapted to stat measurement, thus making their clinical use limited. In this context, the commercialization of five new kits for cytokine measurement interleukin ((IL)-1, IL-6, IL-8, tumor necrosis factor (TNF)-alpha and IL-2R) on an automated immunoanalyzer, the Immulite, seems to be a new approach for the determination of these markers. We report here the evaluation of the performance of these tests. The technique is based on a solid phase (bead) two site chemiluminescent enzyme immunometric assay. The analysis is performed within 60 to 90 minutes and the calibration is stable for 15 days. The values of the between-run imprecision study were similar to those from the within-run study with coefficients of variation (CV) ranging from 2% (low values of IL-8) to 11.5% for intermediate concentrations of IL-6 (500 pg/ml). CVs were usually around 5%. The accuracy was determined by a linearity study using standards (except for IL-2R) provided by the National Institute for Biological Standards and Control (NIBSC). Slopes obtained during this study were close to 1 (r2 = 0.99), except for IL-6, for which the slope was 1.55. TNF-alpha values were close to those expected. IL-1 results were about 20% higher. IL-6 values were over estimated above 100 pg/ml and under estimated below this value. IL-8 study seemed to be impaired by the poor stability of this molecule in the NIBSC preparation. Correlation study with standard laboratory techniques gave variable results: for IL-1 (n = 43) the slope was 0.77 (study carried out using cell culture media), for IL-6 (n = 54) the slope was 0.78, for IL-8 (n = 37) the slope was 1.64, for TNF-alpha (n = 40) the slope was 0.33 and the slope for IL-2R (n = 51) was 5.1. For the last cytokine, the unit in Immulite assay was different from the one used in our comparison technique. Cross-calibration results were consistent with these data and show that the bias is probably linked to a calibration problem. The study demonstrated excellent practicality of the system, and good stability of the calibration curve (15 days). However, the sample volume required (350 microl for the IL-6 and the TNF-alpha) could constitute a limitation for pediatric measurements.

Cytokines↗
PubMed1999

[Biological diagnosis of immediate drug allergy. Comparative study of histamine liberation tests and CD63 expression by flow cytometry (preliminary results)].

The diagnosis of drug allergy is mainly based upon a detailed clinical history, positive skin tests (ST) and detection of specific IgE. In case of discrepant results, in vitro investigations to identify the responsible drug are needed. The histamine release test (HR) is usually performed. Nevertheless, its clinical benefit remains controversial. Flow cytometric methods (FCM) for the study of allergen induced basophil activation have been recently described. We assessed their usefulness in the diagnosis of drug allergy in comparison to HR results. Eighteen patients were included and 24 drugs (mainly antibiotics and muscle relaxant drugs) were tested. On the basis of clinical signs, 15 patients were classified as allergic (18 drugs). Sensitivity of biological investigations were found as follows: 71% (ST), 71% (FCM) and 24% (HR). This suggests performing FCM rather than HR. In addition, HR is more costly in terms of both reagents and laboratory technician time. Thus, CD63 detection by FCM seems to be a more reliable method in the clinical immunology laboratory. Additional data are needed to validate these preliminary results (sensitivity and specificity, especially in atopic patients) and to assess the interest of the method to investigate drug allergy due to other types of molecules.

Antigens, CD↗
PubMed1998

Genetic polymorphisms in the tumor necrosis factor locus influence non-Hodgkin's lymphoma outcome.

Systemic release of tumor necrosis factor (TNF) and lymphotoxin-alpha (LTalpha) has been found to contribute to the severity of non-Hodgkin's lymphoma (NHL). We investigated whether genetic polymorphisms in the TNF locus, previously shown to influence TNF and LTalpha genes expression, might contribute to these cytokines production and to the clinical course of NHL. Genomic DNA from 273 lymphoma patients was typed for TNF (-308) polymorphism using an allele-specific polymerase chain reaction (PCR) and for LTalpha (+252) polymorphism with a PCR-based restriction fragment length polymorphism. The presence of the TNF allele involved in increased TNF gene transcription was associated with higher plasma levels of this cytokine at the time of lymphoma diagnosis (chi2 test, P = .013). An extended haplotype analysis showed that the presence of at least two TNF or LTalpha high-producer alleles constituted a risk factor for first-line treatment failure (chi2 test, P = .021), shorter progression-free survival (log-rank test, P = .0007), and overall survival (log-rank test, P = .012). In the subgroup of 126 patients with diffuse large-cell lymphoma, the presence of two or more TNF/LTalpha high producing alleles contributed significantly to a higher rate of relapse and progression (log-rank test, P = .045 and P = .027). In multivariate Cox regression models including the variables of the International Prognostic Index, the TNF/LTalpha haplotype status was found to be an independent risk factor for progression-free survival (relative risk 2.33, 95% confidence interval [1.17 to 4.64], P = . 0053) and overall survival (relative risk 1.92, 95% confidence interval [0.63 to 5.80], P = .081) of large-cell lymphoma patients. These results indicate that genetic polymorphism leading to increased TNF production influences the outcome of NHL and suggest a pathophysiological role for the genetic control of the immune response in lymphoid malignancies.

Adult↗
PubMed1998

Increased production of a Th2 cytokine profile by activated whole blood cells from rheumatoid arthritis patients.

T cells produce regulatory cytokines which control inflammation. In rheumatoid arthritis (RA), a Th1 cytokine profile has been described in the synovium. In order to assess the Th1/Th2 cytokine balance in blood, a one step culture-immunoassay procedure was used to measure the ex vivo production of IFN gamma and IL-4 by whole blood cells from 26 RA patients and 25 controls. For comparison, the same cytokines were measured by ELISA in supernatants of activated whole blood cells. The direct whole blood assay was 10-fold more sensitive than standard ELISA to measure IL-4 levels. IL-4 production was higher in RA patients than in controls, whereas that of IFN gamma was lower. Accordingly, the IL-4/IFN gamma ratio, which reflects the Th2/Th1 cytokine balance in blood, was higher in RA patients (P < 0.0001). The present findings indicate a Th2-over-Th1 cytokine balance profile in RA blood. These results are in contrast with the Th1-over-Th2 pattern previously found in the joint, indicating that the two compartments appear to be differently regulated.

Adolescent↗
PubMed1998

Plasma levels of tumour necrosis factor and its soluble receptors correlate with clinical features and outcome of Hodgkin's disease patients.

A prospective study was performed to assess the use of plasma measurement of tumour necrosis factor (TNF), lymphotoxin alpha (LT alpha) and their soluble receptors (p55 and p75) for prognostic risk assignment in 61 patients with Hodgkin's disease. Plasma levels of TNF, p55 and p75, but not of LT alpha, were higher in Hodgkin's disease patients than in healthy controls. Plasma levels of TNF, p55 and p75 were associated with several prognostic factors for Hodgkin's disease, including those related to the host (age, performance status) and to the tumour (disease stage, extranodal site involvement, bulky tumour, serum levels of LDH and beta2-microglobulin, histology). Elevated plasma levels of TNF, p55 and p75 were also associated with several parameters reflecting an immune activation, including the presence of B symptoms, elevated serum levels of gammaglobulins, alkaline phosphatase and fibrinogen, as well as peripheral monocytosis, anaemia and low serum albumin levels. Finally, elevated TNF ligand receptor plasma markers were associated with a lower incidence of complete response to therapy and predicted shorter free-from-progression survival and overall survival of the patients. These results indicate that the plasma levels of TNF and its soluble receptors correlate with clinical features and outcome of patients with Hodgkin's disease.

Adolescent↗
PubMed1998

Multicenter evaluation of the Paragon CZE 2000 capillary zone electrophoresis system for serum protein electrophoresis and monoclonal component typing.

Serum protein electrophoresis and typing of monoclonal components (MCs) are routine but time-consuming and technically demanding assays. We evaluated capillary electrophoresis (Paragon CZE 2000) for automation of the two assays. CZE and cellulose acetate electrophoresis gave similar data on 794 samples. Within-run and between-run CVs were < 2% for albumin and gamma-globulins and 4-7% for alpha 1-, alpha 2-, and beta-globulins. Bilirubin, hemoglobin, triglycerides, and fibrinogen were found not to interfere. No carryover by capillaries was detected. The detection limit for MC was < 0.5 g/L. MC assessment by immunosubtraction on 403 samples identified the monoclonal type in all samples with peak concentrations > 10 g/L; only 50% of MCs that could not be quantified by densitometric scan were typed.

Antibodies, Monoclonal↗