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Biomedical subjects

M Denis

Publications and source records attributed to M Denis.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency.

Genes have a major role in the control of high-density lipoprotein (HDL) cholesterol (HDL-C) levels. Here we have identified two Tangier disease (TD) families, confirmed 9q31 linkage and refined the disease locus to a limited genomic region containing the gene encoding the ATP-binding cassette transporter (ABC1). Familial HDL deficiency (FHA) is a more frequent cause of low HDL levels. On the basis of independent linkage and meiotic recombinants, we localized the FHA locus to the same genomic region as the TD locus. Mutations in ABC1 were detected in both TD and FHA, indicating that TD and FHA are allelic. This indicates that the protein encoded by ABC1 is a key gatekeeper influencing intracellular cholesterol transport, hence we have named it cholesterol efflux regulatory protein (CERP).

ATP Binding Cassette Transporter 1↗
PubMed1999

Soluble CD44: quantification and molecular repartition in plasma of patients with colorectal cancer.

Based on the important role of CD44 in tumour progression and metastasis, we evaluated, in a prospective study, plasma-soluble CD44 (sCD44) as a serum marker in colorectal cancer. Blood plasma specimens from 89 patients with colorectal neoplasm, 22 patients with a gastrointestinal disease and 23 healthy donors were analysed for quantitation (ELISA assay) and purification of sCD44. The concentration of sCD44, indicating the concentration of all isoforms, was significantly higher in patients with colorectal cancer and intestinal disease than in normal individuals, but no significant differences were found between the two groups. We found no association between plasma levels and staging of the colorectal cancer patients according to Astler and Coller. A two-step batch purification combining ion exchange and immunoaffinity chromatography, followed by Western blot analysis, revealed a complex pattern with a major band corresponding to the standard form of CD44 and minor bands that may correspond to larger variant forms. No particular sCD44 isoform was clearly associated with anatomopathological or biological information.

Aged↗
PubMed1999

Molecular characterization of the diversity of Campylobacter spp. isolates collected from a poultry slaughterhouse: analysis of cross-contamination.

Investigations of a free-range broiler flock during the rearing period and at the slaughterhouse by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the flagellin (flaA) gene (flaA typing) have shown that poultry carcasses are contaminated by Campylobacter spp. strains which were previously present in the poultry faces. Moreover, the investigation of the previous and the following batches in the processing plant using flaA typing have shown that cross-contamination between batches coming from different flocks occurs and is also a risk factor for the presence of Campylobacter spp. on poultry carcasses.

Abattoirs↗
PubMed1999

Development of a m-PCR assay for simultaneous identification of Campylobacter jejuni and C. coli.

Multiplex PCR assay (m-PCR) with three sets of primers was developed for simultaneous identification of Campylobacter jejuni and C. coli. Poultry faecal samples were enriched in Preston broth for 24 h and streaking on selective media was performed before and after enrichment. m-PCR was applied on bacterial cultures harvested from media plates. The data showed a selective effect of Preston broth which favoured the growth of C. coli. Identification of the species by the hippurate hydrolysis test and by the m-PCR was performed on 294 isolates of Campylobacter. The efficiency of the identification by the biochemical test is only 34% in comparison to 100% efficiency with the PCR. The use of our m-PCR in combination with the culture method allowed reliable detection and identification of C. jejuni and C. coli within 3-4 d.

Animals↗
PubMed1999

Susceptibility of bovine antigen-presenting cells to infection by bovine herpesvirus 1 and in vitro presentation to T cells: two independent events.

The aim of the present study was to develop an in vitro system for presentation of bovine herpesvirus 1 (BHV-1) antigens to bovine T lymphocytes and to characterize the antigen-presenting cells (APC) which efficiently activate CD4(+) T cells. Two approaches were used to monitor the infection of APC by BHV-1 as follows: (i) detection of viral glycoproteins at the cell surface by immunofluorescence staining and (ii) detection of UL26 transcripts by reverse transcription-PCR. The monocytes were infected, while dendritic cells (DC) did not demonstrate any detectable viral expression. These data suggest that monocytes are one site of replication, while DC are not. The capacities of monocytes and DC to present BHV-1 viral antigens in vitro were compared. T lymphocytes (CD2(+) or CD4(+)) from BHV-1 immune cattle were stimulated in the presence of APC previously incubated with live or inactivated wild-type BHV-1. DC stimulated strong proliferation of Ag-specific T cells, while monocytes were poor stimulators of T-cell proliferation. When viral attachment to the surface of the APC was inhibited by virus pretreatment with soluble heparin, T-cell proliferation was dramatically decreased. Unexpectedly, incubation of DC and monocytes with the deletion mutant BHV-1 gD-/-, which displays impaired fusion capacity, resulted in strong activation of T lymphocytes by both APC types. Collectively, these results indicate that presentation of BHV-1 antigens to immune T cells is effective in the absence of productive infection and suggest that BHV-1 gD-/- mutant virus could be used to induce virus-specific immune responses in cattle.

Animals↗
PubMed1999

Osteoarthritis caused by Neocosmospora vasinfecta.

We report the case of a patient who developed an ankle osteoarthritis due to the Ascomycete Neocosmospora vasinfecta, following accidental multiple trauma to his legs in whilst in Africa. Antifungal susceptibility testing was performed. Despite a low amphotericin B minimal inhibitory concentration, parenteral antifungal therapy failed and amputation was required to resolve the osteoarthritis. Possible reasons for the failure of this antifungal treatment are examined.

Adult↗
PubMed1998

Cortical anatomy of mental imagery of concrete nouns based on their dictionary definition.

The functional anatomy of the interactions between spoken language and visual mental imagery was investigated with PET in eight normal volunteers during a series of three conditions: listening to concrete word definitions and generating their mental images (CONC), listening to abstract word definitions (ABST) and silent REST. The CONC task specifically elicited activations of the bilateral inferior temporal gyri, of the left premotor and left prefrontal regions, while activations in the bilateral superior temporal gyri were smaller than during the ABST task, during which an additional activation of the anterior part of the right middle temporal gyrus was observed. No activation of the occipital areas was observed during the CONC task when compared either to the REST or to the ABST task. The present study demonstrates that a network including part of the bilateral ventral stream and the frontal working memory areas is recruited when mental imagery of concrete words is performed on the basis of continuous spoken language.

Adult↗
PubMed1998

Development of a PCR-based method coupled with a microplate colorimetric assay for the detection of Porcine Parvovirus and application to diagnosis in piglet tissues and human plasma.

A new method for Porcine Parvovirus (PPV) diagnosis was developed. The method is based on polymerase chain reaction (PCR) amplification followed by hybridization and colorimetric detection of PCR products in microwell plates. A highly specific and sensitive amplification step was ensured by primers carefully selected in the VP2 structural gene and optimized PCR conditions. Uracyl-DNA-Glycosylase (UDG) in combination with dUTP was used to avoid false-positive results, and 100 copies of internal control (IC) were added to each PCR reaction to reveal any false-negative samples. Biotinylated amplified fragments were hybridized on specific capture probes covalently linked to microwell plates. Finally, the detection of hybridized PCR products was performed by means of a colorimetric reaction, which was automated. The method permitted the detection of 10(3) copies (6 fg) of replicative form DNA (RF-DNA) in 20 mg of lung sample, and 500 copies (3 fg) in 100 microl of plasma. It was used to analyse 24 field piglet tissue samples, and 35 human plasma or serum specimens collected from patients treated with porcine Factor VIII concentrates.

Animals↗
PubMed1998

Reopening the mental imagery debate: lessons from functional anatomy.

Over the past few years, the neural bases of mental imagery have been both a topic of intense debate and a domain of extensive investigations using either PET or fMRI that have provided new insights into the cortical anatomy of this cognitive function. Several studies have in fact demonstrated that there exist types of mental imagery that do not rely on primary/early visual areas, whereas a consensus now exists on the validity of the dorsal/ventral-route model in the imagery domain. More importantly, these studies have provided evidence that, in addition to higher order visual areas, mental imagery shares common brain areas with other major cognitive functions, such as language, memory, and movement, depending on the nature of the imagery task. This body of recent results indicates that there is no unique mental imagery cortical network; rather, it reflects the high degree of interaction between mental imagery and other cognitive functions.

Brain Mapping↗
PubMed1998

Humoral and cell-mediated immune responses of beef and dairy cattle experimentally infested with Psoroptes ovis.

OBJECTIVE: To compare cellular and humoral immune responses of beef (Belgian White and Blue [BWB]) and dairy (Friesian-Holstein [FH]) cattle to Psoroptes ovis infestation and to determine whether P ovis infestation impaired immune responses to infectious bovine rhinotracheitis virus (IBR) vaccine or an immunogenic protein (keyhole-limpet hemocyanin [KLH]). ANIMALS: 19 BWB and 6 FH 1-year-old calves. PROCEDURE: 2 trials were performed. In each trial, 7 (trial 1) or 6 (trial 2) BWB calves and 3 FH calves were experimentally infested with P ovis and 3 BWB calves were maintained as uninfested controls. Animals were inoculated with KLH and IBR virus vaccine twice; 3 BWB calves in each trial were treated with ivermectin. Serum antibody responses to KLH, IBR virus, and P ovis were measured by use of ELISA. A lymphocyte transformation assay was used to determine nonspecific responses to 3 mitogens and specific lymphocyte reactivity to P ovis antigen. RESULTS: In each trial, 3 BWB and 3 FH calves developed clinical signs of psoroptic mange and mites could be recovered. Infested and control animals developed similar antibody titers to KLH and IBR virus. Antibodies to P ovis were detected early in some infested calves, and this was correlated with a marked cell-mediated immune response. Lymphocyte responsiveness to the 3 mitogens was not significantly different among groups. CONCLUSIONS: In these calves, infestation with P ovis induced a marked humoral and cell-mediated immune response. Immunosuppression was not evident.

Animals↗
PubMed1997

Purification and characterization of bovine dendritic cells from peripheral blood.

Optimal activation of T lymphocytes depends on TCR interaction with peptide/MHC complexes in conjunction with costimulatory signals, which are delivered by specialized cells called antigen-presenting-cells (APC). The population of APC is heterogeneous and includes dendritic cells, B cells and macrophages. The family of dendritic cells (DC) is widely distributed in tissues and plays a major role in the induction of primary T-dependent immune responses. The aim of this paper was to isolate and characterize dendritic cells from cattle. Two methods are described that have been used to isolate dendritic cells from bovine peripheral blood. One method involves sequential depletion of other cells, adherence and isolation of low buoyant density cells on Metrizamide column. The second involves enrichment of cells displaying receptors for plasma fibronectin, followed by adherence and separation on Metrizamide. Both preparations were characterized morphologically by flow cytometry and functionally. Both procedures produced enriched populations that did not express molecules typical of T cells (CD3, CD4, CD8, WC1), B cells (sIg, CD21) and monocytes (CD14, Fc gamma 2R). Procedure 2 yielded cells with a typical veiled DC morphology that were highly effective at stimulating allogeneic T cells. Procedure 1 yielded cells that did not have the veiled morphology and were less effective in the MLR which may represent a more immature stage.

Animals↗
PubMed1997

Detection of disseminated tumor cells in peripheral blood of colorectal cancer patients.

All cancer staging systems seek to identify clinical and pathological features that can predict outcome or guide therapy. In particular, a non-invasive method for the early detection of disseminating disease would be of great interest. We investigated the use of cytokeratin genes expression to detect blood metastases from colorectal tumors. Epithelial tumor cells were isolated from whole blood using the monoclonal antibody (MAb) BerEP4 and magnetic beads, and detected by reverse transcription-polymerase chain reaction using oligonucleotides derived from the cDNA sequences of cytokeratins 8, 19 and 20. The sensitivity of this assay was determined by spiking SW620 colon carcinoma cells in normal blood. Using cytokeratin 19 expression we were able to detect 1 epithelial tumor cell in 1 ml of whole blood. The clinical applicability of this technique was explored by evaluating patients with a colorectal carcinoma. Epithelial cells were detected in the blood of 12 out of 23 patients, 2 (20%) of 10 with Astler-Coller stage A or B, and 10 (77%) of 13 with stage C or D cancer. In conclusion, this test is a non-invasive, sensitive, and specific assay for detecting circulating epithelial cells in blood. It may be useful for the early diagnosis of disseminating disease, to determine whether the presence of micrometastatic cells at the time of surgery is correlated with an early relapse and for monitoring adjuvant therapeutic trials.

Adult↗
PubMed1997

Optimization of murine CD8+ cytotoxic T-lymphocyte responses to pseudorabies virus.

The aim of this work was to optimize the procedures used to elicit a cellular immune response to pseudorabies virus (PrV) in mice, using various immunization schedules and routes. An Eu-labeling-based cytotoxic T-lymphocyte (CTL) test was developed to measure the response. This necessitated optimization of numerous steps. In suspension, Eu labeling required high concentrations of dextran-sulfate (DXS) and Eu with a 30-min labeling time at room temperature. For anchored cells, the labeling time was 1 to 48 h, and the labeling efficiency depended strongly on the Eu concentration, but only marginally on the DXS concentration. In vivo and in vitro stimulation protocols were also optimized for the CTL test. For in vitro stimulation, spleen cells were cultured in T-25 flasks at a multiplicity of infection (m.o.i.) of 2. The CTL test was validated by specific depletion of CD8+ CTL, FACS analysis, and by comparing Eu and 51 Cr labeling. Then groups of mice were vaccinated once or twice by various routes (intraperitoneal (i.p.), intravenous (i.v.), subcutaneous (s.c.) and in the rear footpads (FP)) and according to different time schedules. CTL activity was detected only in boosted animals immunized FP, i.p. or i.v. That the cellular immune response contributes to protection was further suggested by the observation that i.p. immunization conferred better protection against challenge than s.c. immunization.

3T3 Cells↗
PubMed1997

Mental navigation along memorized routes activates the hippocampus, precuneus, and insula.

Positron emission tomography was used to investigate the functional anatomy of mental simulation of routes (MSR) in five normal volunteers. Normalized regional cerebral blood flow was measured while subjects mentally navigated between landmarks of a route which had been previously learned by actual navigation. This task was contrasted with both static visual imagery of landmarks (VIL) and silent Rest. MSR appears to be subserved by two distinct networks: a non-specific memory network including the posterior and middle parts of the hippocampal regions, the dorsolateral prefrontal cortex and the posterior cingulum, and a specific mental navigation network, comprising the left precuneus, insula and medial part of the hippocampal regions.

Adult↗