Biomedical subjects

D Riochet

Publications and source records attributed to D Riochet.

7 recordsLinked to original sources

PubMed2006

Role of hospital stay and antibiotic use on Pseudomonas aeruginosa gastrointestinal colonization in hospitalized patients.

The prospective cohort study presented here assessed the risk factors associated with Pseudomonas aeruginosa gastrointestinal colonization (PAGIC) in 933 patients hospitalized in five different wards in a French university hospital. A total of 195 patients were colonized. By logistic regression, hospitalization in an intensive care unit and length of hospital stay were independent risk factors. A significant association was observed between fluoroquinolone use and PAGIC caused by an ofloxacin-resistant strain (p < 0.0001), imipenem use and PAGIC caused by an imipenem-resistant strain (p < 0.0002) and ceftazidime use and PAGIC caused by a ceftazidime-resistant strain (p < 0.02). The ecological impact of antibiotic use is of great clinical relevance and clinicians should consider antimicrobial resistance in order to limit the development and dissemination of resistant microorganisms.

Aged↗

PubMed2006

Risk-factors for gastrointestinal colonisation with resistant Enterobacteriaceae among hospitalised patients: a prospective study.

This study assessed the incidence of gastrointestinal colonisation by resistant Enterobacteriaceae among hospitalised patients, and identified risk-factors for ceftazidime and ofloxacin resistance. A prospective cohort study was performed in five wards in a French teaching hospital during a 2-year period. Patients hospitalised for > 48 h were enrolled between 17 April 2000 and 30 April 2002. A rectal swab was taken at admission, then once-weekly and/or on the day of discharge. In total, 933 patients were investigated and 585 amoxycillin-resistant isolates were obtained. Resistance rates for ceftazidime and ofloxacin were 9.4% and 4.8%, respectively. Multivariate analysis indicated that previous hospitalisation (p < 0.004) and exposure to amoxycillin-clavulanate (p < 0.003) and ceftriaxone (p < 0.002) were associated significantly with ceftazidime resistance. Hospitalisation in the urology ward (p < 0.02) and previous exposure to fluoroquinolones (p < 0.01) were the two independent risk-factors associated with ofloxacin resistance. The results of the study confirmed that antibiotic use selected resistant Enterobacteriaceae from the gut flora. Resistance was observed mostly in patients with previous antibiotic exposure and previous hospitalisation in wards with a high antibiotic selection pressure.

Adolescent↗

PubMed1998

Adult KCNE1-knockout mice exhibit a mild cardiac cellular phenotype.

The KCNE1 gene encodes a channel regulator IsK which in association with the KvLQT1 K+ channel protein determines the slow component of the cardiac delayed rectifier current. We have investigated the cellular electrophysiological characteristics of adult KCNE1-knockout mouse hearts by means of the standard microelectrode technique. Action potential parameters from the ventricular endocardium of KCNE1 -/- mice were indistinguishable from those of KCNE1 +/+ animals. In particular, KCNE1 -/- hearts did not exhibit prolonged repolarization. E-4031, a specific blocker of erg K+ channels consistently prolonged repolarization in KCNE1 +/+ but not in KCNE1 -/- hearts. By contrast, the chromanol compound 293B, a specific blocker of KvLQT1 K+ channel produced comparable effects on repolarization in KCNE1 -/- and KCNE1 +/+ mice. We conclude that invalidation of the mouse KCNE1 gene by homologous recombination leads to a mild cardiac phenotype at the cellular level.

Action Potentials↗

PubMed1998

Hyperexpression of recombinant CFTR in heterologous cells alters its physiological properties.

We investigated whether high levels of expression of the cystic fibrosis transmembrane conductance regulator (CFTR) would alter the functional properties of newly synthesized recombinant proteins. COS-7, CFPAC-1, and A549 cells were intranuclearly injected with a Simian virus 40-driven pECE-CFTR plasmid and assayed for halide permeability using the 6-methoxy-N-(3-sulfopropyl)quinolinium fluorescent probe. With increasing numbers of microinjected pECE-CFTR copies, the baseline permeability to halide dose dependently increased, and the response to adenosine 3',5'-cyclic monophosphate (cAMP) stimulation decreased. In cells hyperexpressing CFTR, the high level of halide permeability was reduced when a cell metabolism poisoning cocktail was applied to decrease intracellular ATP and, inversely, was increased by orthovanadate. In CFPAC-1 cells investigated with the patch-clamp technique, CFTR hyperexpression led to a time-independent nonrectifying chloride current that was not sensitive to cAMP stimulation. CFPAC-1 cells hyperexpressing CFTR exhibited no outward rectifying chloride current nor inward rectifying potassium current either spontaneously or under cAMP stimulation. We conclude that hyperexpression of recombinant CFTR proteins modifies their properties inasmuch as 1) CFTR channels are permanently activated and not susceptible to cAMP regulation and 2) they lose their capacity to regulate heterologous ionic channels.

Animals↗

PubMed1992

Synthesis of new hydrophilic microspheres: optimized carriers for microparticle-enhanced nephelometric immunoassays.

To optimize antigen-antibody reactions, we have synthesized chemically well-defined hydrophilic microspheres. Proteins or haptens were covalently linked to these carriers. When the microsphere conjugates were agglutinated by the corresponding antiserum, the size of the complex artificially increased during the immunological reaction. After optimizing various parameters such as the hydrophilic character, repulsion charges, and amount of antigen coupled to the microspheres, we developed a rapid and sensitive immunoassay based on laser light scattering by the complexes.

Animals↗

PubMed1991

Polyacrylic microspheres as a solid phase for microparticle enhanced nephelometric immunoassay (NEPHELIA (R)) of transferrin.

Polyfunctional hydrophilic microspheres (MS) can be produced by copolymerisation with gamma-irradiation of acrylic monomers. Transferrin (TRF) can be covalently bound to these MS by reaction between aldehyde groups of the MS and primary amino groups of the protein. MS-TRF conjugates thus obtained are agglutinated by specific antiserum and this agglutination is inhibited by free TRF. Agglutination and inhibition are quantified by measurement of the light scattered by MS-TRF conjugate clusters with a specially designed nephelometer, a process designated as microparticle enhanced nephelometric immunoassay (NEPHELIA (R)) for TRF. Recovery, correlation and reproducibility studies, simultaneously performed in three different laboratories, show that this TRF immunoassay is accurate for a large concentration range. NEPHELIA (R) may appear as an alternative method for a large variety of molecules.

Humans↗

PubMed1991

Microparticle-enhanced nephelometric immunoassay (Nephelia) for immunoglobulins G, A, and M.

Covalent binding of gamma chains of IgG, whole IgA, and mu chains of IgM on polyfunctional hydrophilic microspheres (MS) yields MS-Ig conjugates, usable as reagents in new microparticle-enhanced nephelometric immunoassays (Nephelia). The principle of the assays is inhibition by free analyte (IgG, IgA, and IgM) of agglutination of the MS-Ig conjugate with specific antiserum, the light scattered by the aggregates being measured with a nephelometer. The immunoglobulin assays developed are easy to perform (single-step assays, no washing or phase separation) and sensitive (high dilution of biological samples to exclude interferences and pretreatment). Analytical recovery results (95.4-101.2%) and correlations with generally used commercial assays (r = 0.86-0.98) indicate that the assays are accurate for large concentration ranges of immunoglobulins. Precision study gives CVs = 2.8-9.6%. Nephelia appears to be useful for quantifying a large variety of biological molecules.

Humans↗