Search PubMed⌕ Search

Biomedical subjects

M Denis

Publications and source records attributed to M Denis.

At least 19 recordsLinked to original sources
PubMed2004

Nosocomial infections and hospital mortality: a multicentre epidemiology study.

The aim of this study was to evaluate the number of deaths associated with nosocomial infections (NI) and the contribution of these NI to death. A multicentre descriptive study was conducted in 16 tertiary-care hospitals (14 222 beds) in Northern France. Medical records of consecutive patients who died at least 48 h after admission were reviewed for cause of death, NI and disease severity, before admission and before NI onset. The contribution of NI to death was assessed by agreement between two physicians according to a three-category scale of probability. Among the 1945 patients who died during the study, 26.6% had an NI. According to the agreed diagnosis, NI contributed to the deaths of 284 (14.6%) patients(certainly for 6.6% and possibly for 8%), thereby ranking NI as the fourth most frequent cause of death. Considering the deaths that had not been anticipated independently of NI two weeks before they occurred, NI definitely contributed to 2.8% of them. Lower respiratory tract, bloodstream and surgical wound infections were responsible for 39, 20 and 14%, respectively,of all NI in these patients. The impact of NI on in-hospital mortality seems to be lower than had previously been estimated in France based on US data from the 1970s and 1980s. To improve healthcare quality, further studies are needed to elucidate the processes that may contribute to fatal severe NI.

Adolescent↗
PubMed2002

Neural basis of mental scanning of a topographic representation built from a text.

Humans have the ability to build and to inspect an internal visual image of an environment built from a verbal description. We used positron emission tomography (PET) to investigate the brain areas engaged in the mental scanning of a map that subjects built from the reading of a descriptive text. This task engaged a parieto-frontal network known to deal with spatial representations. Additional activations were evidenced in the angular gyrus and in Broca's and Wernicke's areas. In order to examine the neural impact of the learning modality, these PET results were compared to those obtained in another group of six subjects who performed a similar mental scanning task on a topographic representation built from visual inspection of a map. Both scanning tasks engaged the parieto-frontal network. However, the bilateral activation of the angular gyrus as well as the involvement of language areas appeared specific to the mental scanning of the topographic representation built from textual information. On the other hand, the right medial temporal lobe was activated only when a map had been visually learned. These results suggest that although both tasks involved visuo-spatial internal representation, a trace of the learning modality remained present in the brain.

Adult↗
PubMed2001

Risk factors for Campylobacter spp. contamination in French broiler-chicken flocks at the end of the rearing period.

Our objectives were to identify risk factors for contamination of French broiler flocks by Campylobacter. We used 75 broiler farms in western France. A questionnaire was administered to the farmers and samples of fresh droppings were taken to assess the Campylobacter status of the broiler flocks. 42.7% of the flocks were positive for Campylobacter spp. The risk of contamination of the broiler flocks by Campylobacter was increased in summer/autumn, in houses with static air distribution, when two or more people took care of the flock, in poultry farms with three or more houses and when the drinking water for the chickens was acidified. The presence of litter-beetles in the change room also increased the risk of contamination. The administration of an antibiotic treatment following a disease decreased the risk of a flock being contaminated by Campylobacter.

Animals↗
PubMed2001

Phytoplankton group dynamics in the Bay of Marseilles during a 2-year survey based on analytical flow cytometry.

BACKGROUND: The Bay of Marseilles is under the influence of a large urban concentration and its maritime activities. All of them discharge compounds (hydrocarbons, excess nutrients, heavy metals, chemicals, etc.) that can alter the marine ecosystem. To investigate whether ultraphytoplankton (<10 microm) could be used as biosensors for their own ecosystem, a 2-year survey was conducted in the Bay of Marseilles. METHODS: Seven stations monitored water mass and potential anthropic effects in the bay. Seawater samples were collected monthly or bimonthly at three depths, prefiltered, fixed, and kept in liquid nitrogen until flow cytometric analysis. RESULTS: Five categories were created: Prochlorococcus, picoeukaryotes (<2 microm), nanoeukaryotes I (2--6 microm), nanoeukaryotes II (6--10 microm), and Synechococcus (<1.5 microm). Artificial neural network analysis (Kohonen self-organizing maps) produced the same number of clusters as cluster analysis with Winlist software (Verity Software House). CONCLUSIONS: In addition to the wide variabilities in abundance and biomass, there were a strong seasonal signal and sporadic events. Lessons are derived from this study for future monitoring of marine microorganisms.

Flow Cytometry↗
PubMed2001

Campylobacter contamination in French chicken production from farm to consumers. Use of a PCR assay for detection and identification of Campylobacter jejuni and Camp. coli.

AIMS: Campylobacter contamination in French chicken production from the farm to the consumer was determined using a PCR assay for bacteria detection and identification. METHODS AND RESULTS: Samples were bird droppings from poultry houses, neck skins, livers, hearts, gizzards, wings, legs and escalopes from slaughterhouses and gizzards, legs, drumstick, breast and escalopes from a supermarket. Bacterial DNA extraction was performed after an enrichment step in a broth and was followed by PCR. An internal control (IC) was used for both DNA extraction and PCR. Campylobacter were detected in 79.2% of poultry houses. Of the 303 samples, 201 were Campylobacter-positive (i.e. 66.3%) including 43.2% faecal samples, 5.6% slaughterhouse samples and 17.5% supermarket samples. There was no significant difference between the molecular method and the conventional culture technique for Campylobacter detection whatever the samples. The sensitivity was 5 UFC g(-1) of samples and 1.5 x 10(3) UFC ml(-1) of enrichment broth. The use of IC revealed PCR inhibition in 13 samples and problems in the DNA extraction in five samples. CONCLUSION: Significant Campylobacter contamination affects all stages of French chicken production. SIGNIFICANCE AND IMPACT OF THE STUDY: The understanding of Campylobacter contamination at different levels of chicken production and the determination of the best place(s) for intervention are important for significantly decreasing Campylobacteriosis. Our technique is rapid and can be used on different chicken samples for Campylobacter detection and identification.

Abattoirs↗
PubMed2001

Resolution of viable and membrane-compromised bacteria in freshwater and marine waters based on analytical flow cytometry and nucleic acid double staining.

The membrane integrity of a cell is a well-accepted criterion for characterizing viable (active or inactive) cells and distinguishing them from damaged and membrane-compromised cells. This information is of major importance in studies of the function of microbial assemblages in natural environments, in order to assign bulk activities measured by various methods to the very active cells that are effectively responsible for the observations. To achieve this task for bacteria in freshwater and marine waters, we propose a nucleic acid double-staining assay based on analytical flow cytometry, which allows us to distinguish viable from damaged and membrane-compromised bacteria and to sort out noise and detritus. This method is derived from the work of S. Barbesti et al. (Cytometry 40:214-218, 2000) which was conducted on cultured bacteria. The principle of this approach is to use simultaneously a permeant (SYBR Green; Molecular Probes) and an impermeant (propidium iodide) probe and to take advantage of the energy transfer which occurs between them when both probes are staining nucleic acids. A full quenching of the permeant probe fluorescence by the impermeant probe will point to cells with a compromised membrane, a partial quenching will indicate cells with a slightly damaged membrane, and a lack of quenching will characterize intact membrane cells identified as viable. In the present study, this approach has been adapted to bacteria in freshwater and marine waters of the Mediterranean region. It is fast and easy to use and shows that a large fraction of bacteria with low DNA content can be composed of viable cells. Admittedly, limitations stem from the unknown behavior of unidentified species present in natural environments which may depart from the established permeability properties with respect to the fluorescing dyes.

Bacteria↗
PubMed2001

Prognostic value of tyrosinase reverse-transcriptase polymerase chain reaction in metastatic melanoma.

BACKGROUND: Circulating tumor cells can now be identified in subjects with metastatic melanoma by using the reverse-transcriptase polymerase chain reaction (RT-PCR) to detect the messenger RNA of tyrosinase, a key enzyme of melanogenesis. AIM AND METHODS: The aim of this study was to determine whether the detection of positive tyrosinase cells in patients at metastatic stage was associated with a worse evolution. 32 patients were included with metastatic melanoma (AJCC IV). RESULTS: 66% had a positive tyrosinase RT-PCR and a shorter survival compared with patients with a negative RT-PCR, but this difference is not statistically significant. However, a positive test could appear indicative of rapid progression and poor prognosis. CONCLUSION: The prognostic value of this method could be improved by combining it with PCR of other melanoma markers (Melan A, Mage 3) or assays of serum markers (S 100 protein or lactate dehydrogenase).

Humans↗
PubMed2000

Monophosphoryl lipid A and QS21 increase CD8 T lymphocyte cytotoxicity to herpes simplex virus-2 infected cell proteins 4 and 27 through IFN-gamma and IL-12 production.

We have shown previously that IFN-gamma pretreatment of human epidermal cells (ECs) cultured in vitro partially reverses down-regulation of surface MHC class I by HSV infection, allowing recognition by CD8 CTLs, and that HSV immediate early (IE)/early (E) proteins are the predominant targets for CD8 CTLs. In this study of 25 subjects, CD8 CTLs recognized the HSV-2 IE infected cell protein 27 (ICP27) (expressed in autologous IFN-gamma-pretreated, Vaccinia virus recombinant-infected ECs) in all subjects studied, ICP4 in 89%, and ICP0 in 11%. The main hierarchy of recognition was ICP27 > ICP4. ICP27 was the dominant target in 89% of subjects but showed great individual variability in the degree of cytotoxicity. CD8 cytotoxicity specific for HSV-2 IE proteins was enhanced by 48-67% when CD8 CTLs were coincubated with the combination of monophosphoryl lipid A and QS21 adjuvants at the time of Ag presentation. These adjuvants also significantly enhanced IL-12 and IFN-gamma production from nonadherent mononuclear cells stimulated by HSV-2-infected ECs. Addition of IL-12 and IFN-gamma at the time of initial Ag presentation enhanced CD8 cytotoxicity to levels comparable with those stimulated by the adjuvants. Addition of neutralizing Abs to IL-12 or IFN-gamma inhibited CD8 T cell cytotoxicity up to 95% when a combination of the Abs were added at the time of initial Ag presentation. Therefore, the mechanism for the enhancement of CD8 T cell cytotoxicity by adjuvants in this system appears to be via increased levels of IL-12 and IFN-gamma.

Adjuvants, Immunologic↗
PubMed2000

Survival and recovery of viable but noncultivable forms of Campylobacter in aqueous microcosm.

Previous studies suggesting that the persistence of thermotolerant Campylobacter in water, especially as a viable but non-cultivable form (VNC), was involved in human campylobacteriosis, the capacities of survival and resuscitation of a significant collection of 85 strains in aqueous microcosms were investigated. Two-thirds of these strains (68%) were not detectable on agar medium after a stay of 14-21 days, whereas 21% reached this state before 14 days and 11% were non-cultivable after a stay of 21 days. Some strains remained cultivable after 35 days in a shaken aqueous microcosm and beyond 60 days without shaking. After 30 days, 51% of the non-detectable strains by conventional culture were recovered after injection in 9-day fertilised chicken eggs. A kinetic study showed that the age of the viable but non-cultivable forms and characteristics of the strains could explain the variations of recovery. These results suggest that viable but non-cultivable forms of Campylobacter could be a potential risk of colonisation of human or animals and that an embryonic factor seems to be essential to allow resuscitation.

Animals↗
PubMed2000

Neural correlates of topographic mental exploration: the impact of route versus survey perspective learning.

There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietofrontal network composed of the intraparietal sulcus, the superior frontal sulcus, the middle frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.

Adult↗
PubMed2000

Functional anatomy of high-resolution visual mental imagery.

This study had two purposes. First, in order to address the controversy regarding activation of the primary visual area (PVA) during visual mental imagery, regional cerebral blood flow (rCBF) was recorded while subjects performed a task that required high-resolution visual mental imagery. Second, in order to discover whether verbal descriptions can engage visual mechanisms during imagery in the same way as visual stimuli, subjects memorized 3D scenes that were visually presented or were based on a verbal description. Comparison of the results from the imagery conditions to a non-imagery baseline condition revealed no activation in PVA for imagery based on a verbal description and a significant decrease of rCBF in this region for imagery based on visual learning. The pattern of activation in other regions was very similar in the two conditions, including parietal, midbrain, cerebellar, prefrontal, left insular, and right inferior, temporal regions. These results provide strong evidence that imagery based on verbal descriptions can recruit regions known to be engaged in high-order visual processing.

Adult↗
PubMed2000

Assessment of ribozyme cleavage efficiency using reverse transcriptase real-time PCR.

Real-time PCR is a novel technology recently described to perform quantitative analysis of amplified products. Unlike classical quantitative PCR, this method is easy to standardize, does not required extensive manipulation, and is not reagent intensive, so that the risk of contamination is minimized. Therefore, we have chosen reverse transcriptase real-time PCR to quantitate CD95 (Fas) transcripts to test the cleavage efficiency of anti-Fas ribozymes in the mouse insulinoma cell line beta TC-3. Based on the melting-curve analysis of the amplified products, we determined the temperature at which to collect the fluorescent data used for quantification. After constructing a standard curve by plotting the log of the standards' copy number versus their fractional cycle number, the copy numbers of the unknown samples were automatically determined by interpolation of this curve. As we illustrate in this study, it is important, particularly while setting up the technique, to validate the melting-curve profile with standard gel electrophoresis analysis, achieved by matching melting temperature and size of the amplified product. The method is fast and reproducible: Excluding the isolation of RNA and synthesis of cDNA, the results can be obtained in less than 1 hr. The coefficient of variance is 15% in the range of 10(4)-10(6) gene copies. Accordingly, reverse transcriptase (RT) real-time PCR is a technique suitable for screening a large number of ribozymes.

Animals↗
PubMed1999

Mutations in the ABC1 gene in familial HDL deficiency with defective cholesterol efflux.

BACKGROUND: A low concentration of HDL cholesterol is the most common lipoprotein abnormality in patients with premature atherosclerosis. We have shown that Tangier disease, a rare and severe form of HDL deficiency characterised by a biochemical defect in cellular cholesterol efflux, is caused by mutations in the ATP-binding-cassette (ABC1) gene. This gene codes for the cholesterol-efflux regulatory protein (CERP). We investigated the presence of mutations in this gene in patients with familial HDL deficiency. METHODS: Three French-Canadian families and one Dutch family with familial HDL deficiency were studied. Fibroblasts from the proband of each family were defective in cellular cholesterol efflux. Genomic DNA of each proband was used for mutation detection with primers flanking each exon of the ABC1 gene, and for sequencing of the entire coding region of the gene. PCR and restriction-fragment length polymorphism assays specific to each mutation were used to investigate segregation of the mutation in each family, and to test for absence of the mutation in DNA from normal controls. FINDINGS: A different mutation was detected in ABC1 in each family studied. Each mutation either created a stop codon predicted to result in truncation of CERP, or altered a conserved aminoacid residue. Each mutation segregated with low concentrations of HDL-cholesterol in the family, and was not observed in more than 500 control chromosomes tested. INTERPRETATION: These data show that mutations in ABC1 are the major cause of familial HDL deficiency associated with defective cholesterol efflux, and that CERP has an essential role in the formation of HDL. Our findings highlight the potential of modulation of ABC1 as a new route for increasing HDL concentrations.

ATP Binding Cassette Transporter 1↗
PubMed1999

Visual and mental exploration of visuo-spatial configurations: behavioral and neuroimaging approaches.

Do mental imagery and perception involve common processing mechanisms? Imagery researchers have devoted a great deal of effort to establishing the functional and structural similarities between images and perceptual events. Recent studies have focused on the comparison of images that are reconstructions of previous perceptual experience and images constructed from verbal descriptions. This article reports the findings of a research program based on the mental scanning paradigm; they reveal the similarities and differences between the two kinds of mental images. Neuroimaging studies have also provided evidence that the parieto-occipital cortex is involved in the processing of visual images, whether they are based on perceptual experience or constructed from linguistic inputs. However, the PET studies conducted by our research groups provide no evidence that the primary visual cortex is engaged in the generation of visual images. As there is contradictory evidence about this, further research is needed to clarify the role of the early visual areas in mental visual imagery.

Brain Mapping↗
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↗