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J Raymond

Publications and source records attributed to J Raymond.

At least 37 records · Page 2Linked to original sources
PubMed2003

Glutamate transporters in the guinea-pig cochlea: partial mRNA sequences, cellular expression and functional implications.

In the cochlea, glutamate plays a major role in synaptic transmission between the inner hair cell and the primary auditory neurons. Extracellular glutamate concentration must be regulated to prevent excitotoxicity. This regulation is mediated by excitatory amino acid transporters, membrane proteins that remove glutamate from the synaptic cleft. In this study, we investigated the distribution and activity of three excitatory amino acid transporters subtypes in the guinea-pig cochlea: glutamate aspartate transporter, glutamate transporter and excitatory amino acid carrier. A partial messenger ribonucleic acid sequence was determined for each of these transporters, by polymerase chain reaction with degenerate primers, using guinea-pig brain complementary deoxyribonucleic acid as the template. Primers specific for each transporter were then designed and used to screen a dissected organ of Corti complementary deoxyribonucleic acid library. The cellular distribution of each transporter was examined by immunocytochemistry. We investigated the functional consequences of inhibiting glutamate uptake by recording cochlear potentials during intracochlear perfusion with either l-trans-pyrrolidine-2,4-dicarboxylic acid or dihydrokainate. At the end of the electrophysiological session, cochleas were processed for electron microscopy. Only the glutamate aspartate transporter messenger ribonucleic acid was detected in the organ of Corti. Consistently, glutamate aspartate transporter protein was detected in the inner hair cell-supporting cells and in the ganglion of Corti satellite cells. Glutamate transporter and excitatory amino acid carrier were found in the afferent auditory neurons. Only intracochlear perfusions with l-trans-pyrrolidine-2,4-dicarboxylic acid resulted in a dose-dependent decrease in the amplitude of the cochlear compound action potential, leaving cochlear microphonic potential unaffected. After l-trans-pyrrolidine-2,4-dicarboxylic acid perfusion, cochleas displayed a swelling of the afferent endings typical of excitotoxicity. [(-)1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-4,5-dihydro-3-methylcarbamyl-2,3-benzodiazepine], a selective alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist protects the cochlea against l-trans-pyrrolidine-2,4-dicarboxylic acid effect.

Afferent Pathways↗
PubMed2003

Evaluation of a novel monoclonal enzyme immunoassay for detection of Helicobacter pylori antigen in stool from children.

BACKGROUND: Reliable non-invasive methods for detection of Helicobacter pylori infection are required to investigate the incidence, transmission, and clearance of infection in childhood. AIM: To evaluate a new monoclonal enzyme immunoassay (EIA) (FemtoLab H pylori Cnx) for detection of H pylori antigen in stool in a large cohort of children compared with invasive diagnostic methods and the (13)C urea breath test. PATIENTS AND METHODS: A total of 302 symptomatic previously untreated children (aged 0.5-18.7 years; 148 girls) were recruited at three centres. H pylori status was defined by results of culture, histology, the rapid urease test, and the (13)C urea breath test. Stool samples were investigated locally by the EIA using two different production lots. According to the manufacturer's recommendations, an optical density (OD) of 0.150 was used as a cut off value. RESULTS: OD values clearly differentiated between the 92 H pylori infected and the 210 non-infected children (median (5th-95th percentiles) 2.729 (0.232->4.000) v 0.021 (0.009-0.075)). Only two false positive and two false negative results occurred, giving a sensitivity, specificity, positive predictive value, and negative predictive value of 98%, 99%, 98%, and 99%, respectively. No significant relation was found between age and OD values in infected or non-infected children. CONCLUSIONS: The monoclonal stool antigen EIA was excellent in diagnosing H pylori infection in symptomatic children. Accuracy was independent of the laboratory, production lot used, or the child's age. Because only 18/116 children <6 years of age were infected with H pylori, further validation of the test is needed in young infected children.

Adolescent↗
PubMed2002

Distribution of the forces produced by motor unit activity in the human flexor digitorum profundus.

In humans, the flexor digitorum profundus (FDP), which is a multi-tendoned muscle, produces forces that flex the four distal interphalangeal joints of the fingers. We determined whether the force associated with activity in a single motor unit in the FDP was confined to a single finger or distributed to more than one finger during a natural grasp. The discharge of single low-threshold motor units (n = 69) was recorded at sites across the muscle during weak voluntary grasping involving all fingers and spike-triggered averaging of the forces under each of the finger pads was used to assess the distribution pattern. Spike-triggered averaging revealed that time-locked changes in force occurred under the 'test' finger (that finger on which the unit principally acted) as well as under the 'non-test' fingers. However, for the index-, middle- and ring-finger units, the changes in force under non-test fingers were typically small (< 20 % of those under the test finger). For little-finger units, the mean changes in force under the adjacent ring finger were large (>50 % of those under the test finger). The distribution of forces by little-finger units differed significantly from that for each of the other three fingers. Apart from increases in force under non-test fingers, there was occasional unloading of adjacent fingers (22/267 combinations), usually affecting the index finger. The increases in force under the test finger correlated significantly with the background force for units acting on the middle, ring and little fingers. During a functional grasp, the activity of single units in the FDP allows for a relatively selective control of forces at the tips of the index, middle and ring fingers, but this is limited for little-finger units.

Adult↗
PubMed2002

[Acquisition of secondary resistance after failure of a first treatment of Helicobacter pylori infection in children].

AIMS: To assess the frequency of acquisition of secondary Helicobacter pylori resistant-strains after a first course of antimicrobial treatment. PATIENTS AND METHODS: A retrospective study was performed during the 1994-2000 period, in 15 girls and eight boys, mean age 10.9 +/- 4.8 years (1.4-17 years), with Helicobacter pylori gastritis (culture and antimicrobial susceptibility) presenting a failure of first course treatment, with during one week a proton pump inhibitor and amoxicillin together with either clarithromycin (n = 14) or metronidazole (n = 9). Two endoscopies were performed, the first at the time of diagnosis and the second after the failure of bacterial eradication demonstrated by a positive 13C urea breath test six weeks after the end of treatment. Antimicrobial susceptibility of all Helicobacter pylori strains was tested after each endoscopy and before starting a second course of the treatment. RESULTS: Comparison of antimicrobial susceptibility before and after the first course of treatment showed that Helicobacter pylori strains were all sensitive to amoxicillin, clarithromycin-resistant in eight children (34.7%) before treatment vs 12 (52.1%) after treatment, p = 0.42, ns, metronidazole-resistant in 13 (56.5%) vs 12 (52.1%), p = 0.80, ns, and both clarithromycin and metronidazole-resistant in four (17.3%) vs seven (30.4%), p = 0.63, ns. Among the 14 children treated by a triple therapy including clarithromycin, three (21.4%) developed a secondary resistance to clarithromycin and in one metronidazole resistance was no more detected. Among the nine children treated with a triple therapy including metronidazole, none developed a secondary resistance to metronidazole and one developed a secondary resistance to clarithromycin. CONCLUSION: This study shows the absence of amoxicillin-resistant strains, a high initial clarithromycin-resistant strains level (primary resistance), increasing after a first course of treatment, and for metronidazole a high initial level of resistance not influenced by treatment. Secondary clarithromycin-resistance of Helicobacter pylori strains following the first course of treatment could account for failure of bacterial eradication and suggests the importance of antimicrobial susceptibility.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

[Hospitalization for acute community-acquired rotavirus gastroenteritis: a 4-year survey].

OBJECTIVE: To evaluate the number of hospitalizations due to community-acquired rotavirus acute gastroenteritis in a general pediatric unit during a four-year survey. RESULTS: From January 1997 to December 2000, 725 patients were admitted for acute gastro-enteritis to the general paediatric unit of a Parisian children hospital (nosocomial diarrhoea excluded) and 706 (97.5%) of these patients had had a stool microbiologic examination. Diarrhoea was caused by rotavirus in 359 patients (50.89%) and Salmonella sp in 61 (8.6%). Children and infants hospitalized for rotavirus acute gastroenteritis were younger (26% had three months or less, and 50.03% had six months or less) than in other European studies. CONCLUSION: This study is the first in France reporting a systematic survey of hospitalized gastroenteritis during four years. More than half of hospitalized community-acquired gastroenteritis were due to rotavirus in this Parisian area. The young age of patients should be investigated in other French areas, searching for risk factors and rotavirus strains.

Acute Disease↗
PubMed2002

[Procalcitonin and viral meningitis: reduction of unnecessary antibiotics by measurement during an outbreak].

OBJECTIVE: Viral meningitis are often treated with antibiotics in emergency because routine analysis of CSF is not always efficient for distinguishing between viral and bacterial infection. The aim of the study was to evaluate the usefulness of procalcitonin (PCT) to reduce antibiotic treatments. METHODS AND RESULTS: A blood PCT level < 0.5 ng/mL was prospectively used for the diagnosis of viral origin of meningitis in 58 patients (two months-14 years), in which enterovirus was isolated by culture or PCR during an outbreak (May-June 2000). CSF cells range was 10 to 2800/mL (m: 244), PMN 5 to 2464/mL and CSF proteins range was 0.19 to 0.92 mg/dL (m: 0.37). Seventeen patients received antibiotic therapy in admission. In nine patients, PCT (dosage was routinely measured 3/week) result < 0.5 ng/mL was obtained in 24 h and in 48 h in six: treatment was then stopped and children led hospital. In two patients, PCT was > 1 ng/mL because of bacterial coinfection. CSF and PCT values were similar to those of an already published control group. CONCLUSION: PCT dosage allowed to shorten hospitalization of 4.47 (controls) to 2.06 (patients) days in patients receiving unnecessary antibiotic treatments. During this outbreak, PCT dosage allowed to reduce 40 days of hospitalization.

Adolescent↗
PubMed2002

[Nosocomial bacteremias in pediatrics].

OBJECTIVES: To identify pathogenic microorganisms responsible for hospital-acquired bloodstream infections and to evaluate the associated risk factors in pediatric units, in a case-control study over 30 months from January 1st 1997 to June 30th 1999. RESULTS: Forty-six of 855 (5.4%) positive blood cultures were attributed to nosocomial infections. They were related to 32 infectious episodes in 28 patients hospitalized for more than 48 hours. The incidence rate was 0.11 per 100 admissions. Gram-positive cocci (n = 14; 38.8%) were the most frequently isolated pathogens (7 cases of Staphylococcus aureus, 5 of coagulase-negative staphylococci), followed by enterobacteria (n = 9; 25%), Pseudomonas aeruginosa (n = 5; 13.8%) and yeasts (n = 5; 13.8%). The major risk factors for hospital-acquired bloodstream infections were: length of stay before positive blood culture (32 +/- 51 days in cases vs 15 +/- 43 days in controls, p < 0.01), presence of central venous catheter [odds ratio (OR): 6.05, 95% confidence interval (CI): 1.87-20.42], number of days with central venous catheter (p < 0.001) and parenteral nutrition (OR: 9.44, 95% CI: 2.03-50.05). CONCLUSION: Central venous catheter use, length of stay, parenteral nutrition and particularly intravenous lipids are major risk factors for the acquisition of bloodstream infection in hospitalized children.

Age Factors↗
PubMed2002

External power output changes during prolonged cycling with electrical stimulation.

This study analysed external power output and physiologic responses in 5 individuals with paraplegia during 40 minutes of electrical stimulation leg cycle exercise. Cycling was performed on a motor-driven isokinetic ergometer that enabled precise determinations of power output. Electrical stimulation was increased to 120-140 mA within the first 5 minutes and remained constant thereafter. Power output increased to 10.7 +/- 3.0 W after 2 minutes, dropped to 5.3 +/- 1.8 W after 6 minutes and subsequently recovered to 8.2 +/- 2.2 and 6.1 +/- 2.3 W after 19.5 and 40 minutes, respectively. Oxygen consumption increased to 0.47 +/- 0.09 l/min after 6 minutes and declined during the second half of the exercise bout. Gross mechanical efficiency after 19.5 minutes was elevated compared with the value after 6 minutes. Heart rate was significantly increased at the end of the trial. The time-dependent variability of power output and physiological responses question the concept of steady state for this form of exercise.

Adult↗
PubMed2002

Validation of diffusion methods for macrolide susceptibility testing of Helicobacter pylori.

Helicobacter pylori resistance to macrolides is increasing, and the need for susceptibility testing has become crucial. The only standardized method is agar dilution, which is not adapted to clinical practice. The present work aimed: (1) to optimize the technical conditions and to assess the reproducibility of the E-test and disk diffusion method for macrolides susceptibility testing of H. pylori, and (2) to assess the performances of these two phenotypic methods in detecting strains harboring a resistance mechanism to macrolides. We used 191 isolates collected in nine centers of France and Belgium. Phenotypic tests were performed on Mueller-Hinton agar supplemented with 10% horse blood, inoculated with a 2-day-old H. pylori suspension (10(8) CFU/ml), and incubated for 72 hr at 37 degrees C under microaerophilic conditions. The reproducibility studied on two randomly selected strains was better for disk diffusion than for the E-test for both clarithromycin and erythromycin. For a subset of 10 strains, the MICs of erythromycin and clarithromycin did not differ from more than one two-fold dilution when determined by E-test or agar dilution method. The breakpoints were for MICs: 1 mg/L for both clarithromycin and erythromycin and for inhibition diameters, 22 mm for clarithromycin and 17 mm for erythromycin. There was a 100% concordance between susceptibility to erythromycin and clarithromycin. However, the susceptible and resistant populations were better separated by testing erythromycin. Of 34 resistant strains, two lacked the A2142G and A2143G point mutations in 23S rRNA by PCR-RFLP. None of 15 tested sensitive strains were positive for one of these two point mutations. For clinical practice, we recommend to assess macrolide susceptibility of H. pylori by using one of these two phenotypic methods under the described technical conditions.

Anti-Bacterial Agents↗
PubMed2002

Helicobacter pylori seroprevalence in asymptomatic pregnant women in France.

The purpose of our study was to evaluate the incidence of Helicobacter pylori seropositivity in two different populations of asymptomatic pregnant women from different geographic origins during two separate time periods. A retrospective study of consecutive sera obtained from 169 and 302 asymptomatic pregnant women in 1990 and 1999, respectively, was carried out. The global H. pylori seroprevalences for 1990 and 1999 were 21.3 and 21.5% (where P is nonsignificant), respectively. For both periods the H. pylori seroprevalences were significantly higher in non-French pregnant women (66.6 and 50.6%) than in French pregnant women (18.7 and 11.2%) (P = 0.01 and 0.001, respectively). H. pylori seroprevalence in French pregnant women decreased significantly from the first period (18.7%) to the second one (11.2%) (P = 0.03).

Adult↗
PubMed2001

Development of the rat efferent vestibular system on the ground and in microgravity.

We investigated whether plastic changes occurred in the organization of the vestibular efferent network in the rat utricle during a 17-day episode of microgravity, from postnatal (PN) day 8 to PN23, and on return to earth on PN25. We also determined the normal pattern of efferent development from birth to PN25. Immunofluorescence experiments were performed with a specific biochemical marker of the efferent system, the calcitonin gene-related peptide (CGRP), and vibratome sections of the utricles were analyzed by laser scanning confocal microscopy. At birth, a few efferent fibers were detected beneath the sensory epithelium. These then massively invaded the epithelium between PN2 and PN4. At the time of launch, PN8, most fiber paths in the utricular epithelium, after following transient courses (towards the epithelial surface for example) returned to the base and were stabilized in the lower part of the epithelium, in which they established synaptic contacts with sensory cells, except at a few immature locations. The main difference between this stage (on PN8) and subsequent more mature stages was the lower density of fibers and synapses in the utricle. The maturation of the vestibular efferent system was similar in microgravity and on the ground. Thus, maturation of the efferent system between PN8 and PN23 was not sensitive to a change in gravitational environment. These results suggest that periods of microgravity at earlier stages are required to identify critical periods in peripheral vestibular system development.

Animals↗
PubMed2001

Cardiovascular responses during arm exercise and orthostatic challenge in individuals with paraplegia.

In this study the cardiorespiratory responses during arm crank ergometry (ACE) performed at two submaximal intensities (30% and 50% of heart rate reserve) and moderate orthostatic challenge were investigated in individuals with paraplegia (PARA). The effect of concurrent electrical stimulation (ES)-induced leg muscle contractions on the responses to ACE during orthostatic challenge was also investigated. Eight PARA (T5-T12) and eight able-bodied (AB) individuals participated in this study, however only seven subjects from each group completed all tests and were used in subsequent data analyses. Oxygen uptake (VO2), heart rate (fc), stroke volume (SV) and cardiac output (Qc) were assessed during (1) ACE alone, (2) ACE and lower body negative pressure (ACE + LBNP), and, in PARA only, (3) ACE + LBNP with ES (ACE + LBNP+ ES). In both PARA and AB, ACE + LBNP decreased SV (by 13-18% and 20-23%, respectively) and increased fc (by 13-15% and 16%, respectively) compared to ACE alone. The decrease in SV was greater in AB than in PARA (significant group x trial interaction; both ACE intensities pooled), but there was no difference in the magnitude of increase in fc between groups. ES-induced leg muscle contractions increased SV (up to 16%) but did not change VO2 or Qc. The smaller reduction in SV from ACE to ACE + LBNP in PARA may indicate a mechanism by which adequate central blood volume can be maintained in the face of orthostatic challenge, despite the absence of supraspinal control below the spinal cord lesion. With ES-induced leg muscle contractions, the decrease in SV, which occurred during ACE + LBNP, was reversed via reactivation of the lower limb muscle pump and augmented venous return.

Adult↗
PubMed2001

[Impact of bacterial resistance on severe infections].

Since many years, the antimicrobial resistance increases as well as for community-acquired as for nosocomial infections. Antibiotic-resistant pneumococci are neither more nor less virulent susceptible strains. Except for immunocompromised patients, the outcome of penicillin-resistant pneumococcal infections have been similar to those in patients who are infected by susceptible ones. Current levels of S. pneumoniae resistance to penicillin and cephalosporin are not associated to an increase in mortality in children with meningitis if adequate doses of antibiotics are given. Because empiric therapy has changed, antibiotic resistance has not been associated with increased mortality. This statement can be extended to Meningococcus, for which 32 to 50% of the strains have a decreased susceptibility to penicillin. For nosocomial infections, S. aureus is the main studied pathogen. Several studies report that in patients with severe diseases (bacteremia or pneumonia) methicillin resistance of S. aureus had no significant impact on patient outcome after adjustment for different confounders. The main risk factor for mortality is the severe underlying diseases rather than the resistance as well for methicillin--resistant S. aureus, as for vancomycin resistant enterococci, Klebsiella with extended spectrum beta lactamase and Enterobacters. Recommendations for controlling epidemiologic surveillance, using barrier precautions and limiting the use of antibiotics as well in the hospital as in the community must be undertaken.

Anti-Bacterial Agents↗
PubMed2001

Nasopharyngeal colonization by Haemophilus influenzae in children living in an orphanage.

AIM: To study colonization and transmission of Haemophilus influenzae in a cohort of children <2 years old living in the unique epidemiologic conditions of a closed community of an orphanage. METHODS: Fifty-three children, ages 0 to 24 months, were followed for 1 year. All children >2 months were vaccinated against H. influenzae serotype b. Nasopharyngeal cultures were collected monthly or, in children <6 months of age, every 2 weeks. Antibiotic susceptibility, serotype, biotype and genotype (pulsed field gel electrophoresis) of each isolate were determined. As control, 39 H. influenzae isolates were recovered from various regions in France. RESULTS: The mean monthly rate of carriage was 45% ranging from 17 to 70%. Most isolates belonged to biotype II (62%), 4 isolates to serotype f (3.6%) and none to serotype b, and 60% of the 111 isolates produced beta-lactamase. A complete concordance was found among biotype, serotype, pulsotype and antimicrobial susceptibility. On average children were sequentially colonized by 3 different isolates. The mean duration of carriage for a given isolate was approximately 1.4 months. In younger children the mean age of primary colonization was 2 months. Contrasting with the high genetic heterogeneity of 39 control isolates, most isolates (82%) belonged to only 5 pulsotypes. Three main H. influenzae clones rapidly spread in the community and colonized children in waves. CONCLUSION: During early life nasopharyngeal colonization by H. influenzae is a dynamic phenomenon with sequential carriage of various clones spreading in the community.

Carrier State↗
PubMed2001

Clarithromycin resistance and eradication of Helicobacter pylori in children.

Outcome of Helicobacter pylori infection was analyzed in 61 children treated with a triple therapy including clarithromycin. Bacterial eradication was obtained in all children with clarithromycin-susceptible strains but not in children with clarithromycin-resistant ones (P = 0.0001). H. pylori antimicrobial susceptibility is mandatory before choosing a treatment, and clarithromycin should be avoided in case of resistance.

Adolescent↗