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Biomedical subjects

M J Dupont

Publications and source records attributed to M J Dupont.

At least 19 recordsLinked to original sources
PubMed2005

Reduced litter sizes following 48-h of prenatal exposure to 5 nT to 10 nT,0.5 Hz magnetic fields: implications for sudden infant deaths.

To test the hypothesis that a narrow intensity band of geomagnetic activity contributes to Sudden Infant Death, 32 pregnant rats were exposed for two to three days before expected parturition either to a coil that generated 0.5 Hz sine-wave, 5 to 10 nanoTesla magnetic fields, or to a reference coil (<1 nT) in the same room. The field was off for 30 min every 4 h during the exposure. The orientation of the coils was perpendicular in space and activated alternately in four blocks of experiments. The litters born to the exposed mothers contained significantly fewer pups (M = 14.1,SD= 2.1) than those exposed to the control conditions (M = 16.2, SD = 2.7). There were significantly fewer numbers of males and fewer numbers of females in litters exposed to the fields generated in the east-west and north-south directions, respectively. These results support the hypothesis that a specific temporal configuration of brief periods of geomagnetic activity can produce an increased incidence of nonvital fetuses, neonates, or infants.

Animals↗
PubMed2004

Emergence of spontaneous seizures during the year following lithium/pilocarpine-induced epilepsy and neuronal loss within the right temporal cortices.

Thirty days after the induction of seizures in 16 rats with lithium (3 mEq/kg) and pilocarpine (30 mg/kg), the numbers of episodes of motor seizures (rapid forelimb clonus) during daily 10-minute observational periods were recorded for 11 months. The proportions of neuronal loss were ranked using two methods by light microscopy for all structures between the posterior and anterior commissures. Amounts of damage within the dentate gyrus, hilus (CA4), and CA3 field were most strongly correlated with numbers of seizures per month about 6 months before the brains were removed. The strongest correlations occurred between the amounts of damage within the right temporal cortices, even after the variance associated with damage within the dentate gyrus had been removed, and the numbers of seizures during the last 2 months. These results may explain the greater proportion of spontaneous seizures that begin with left side forelimb clonus and suggest a particular sensitivity of the right side of the brain to either their initiation or their consequences.

Animals↗
PubMed2004

Geophysical variables and behavior: XCIX. Reductions in numbers of neurons within the parasolitary nucleus in rats exposed perinatally to a magnetic pattern designed to imitate geomagnetic continuous pulsations: implications for sudden infant death.

Correlational analyses have shown a moderate strength association between the occurrence of continuous pulsations, a type of geomagnetic activity within the 0.2-Hz to 5-Hz range, and the occurrence of Sudden Infant Deaths. In the present study, rats were exposed continuously from two days before birth to seven days after birth to 0.5-Hz pulsed-square wave magnetic fields whose intensities were within either the nanoTesla or microTesla range. The magnetic fields were generated in either an east-west (E-W) or north-south (N-S) direction. At 21 days of age, the area of the parasolitary nucleus (but not the solitary nucleus) was significantly smaller, and the numbers of neurons were significantly less in rats that had been exposed to the nanoT fields generated in the east-west direction or to the microTesla fields generated within either E-W or N-S direction relative to those exposed to the N-S nanoTesla fields. These results suggest nanoTesla magnetic fields, when applied in a specific direction, might interact with the local geomagnetic field to affect cell migration in structures within the brain stem that modulate vestibular-related arousal and respiratory or cardiovascular stability.

Animals↗
PubMed2003

Clinical and microbiological epidemiology of Streptococcus pneumoniae bacteremia in eight French counties.

OBJECTIVE: To describe the incidence of pneumococcal bacteremia not associated with infection of the central nervous system, investigate the susceptibility of bacterial isolates to beta-lactams, evaluate risk factors for antibiotic resistance, and determine factors predicting patient outcome. METHODS: Over a period of 1 year, 919 Streptococcus pneumoniae isolates were collected from 919 patients with bacteremia in eight French counties. Their clinical and microbiological features were recorded. Univariate and multivariate analyses were used to determine risk factors for penicillin-non-susceptible pneumococcal bacteremia and predictors of fatal outcome. RESULTS: Of the 919 patients in the study, 27% were infected with penicillin-non-susceptible pneumococci (PNSP): 17.8% of the isolates were intermediate to penicillin, 7.2% were resistant to penicillin, 16% were intermediate to amoxicillin, and 11% were intermediate to cefotaxime; no PNSP were resistant to either of the last two antibiotics. The most common PNSP serotypes isolated were 14 (41%) and 23 (24%). A statistically significant relationship between PNSP infection and age below 5 years or above 60 years in the different counties was observed by univariate and multivariate analysis. Gender, origin of bacteremia, co-morbidity, immunodeficiency, previous hospitalization and nosocomial infection were not predisposing factors associated with PNSP. The mortality rate was 20.6%: there was no increase in mortality among patients with PNSP bacteremia. Age was the strongest risk factor for mortality, but immunodeficiency also seemed to have had an impact on mortality. Clinical outcome was more closely related to clinical conditions than to the susceptibility status of S. pneumoniae. CONCLUSION: Among cases of bacteremia, 27% were caused by PNSP, but this level varies according to the counties and the age of the patients. Infection-related mortality was high, but there was no increase related to penicillin G non-susceptibility of the infecting strain.

Adolescent↗
PubMed2002

Change of pneumococcal resistance to antibiotics in adults between 1995 and 1997: a study in eight French counties.

The main object of this study was to describe the evolution of antibiotic resistance in pneumococci from adults, in eight French counties of France between 1995 and 1997. Despite the high and increasing prevalence (23-35%) of pneumococci with diminished susceptibility to penicillin G (PSDP), resistance to amoxycillin (0.8-0.5%) and to cefotaxime (0-0.3%) was rare in both 1995 and 1997 respectively. The percentage of pneumococci resistant to penicillin G (PRP, minimum inhibitory concentration >1 mg/l) remained stable between the two periods. PSDP showed increased resistance to macrolides (30-41%), to cotrimoxazole (28-34%) and to tetracycline (19-25%). These figures are lower than those obtained over the same periods and the same regions in children. The distribution of PSDP serotypes isolated in adults was the same as that seen in children: by descending order serotypes 23, 14, 9 and 6. This study by the Regional Pneumococcal Observatories confirms the high prevalence and the main characteristics of antibiotic resistance among pneumococci with variations in levels of resistance with the age of patients, with the site of sampling and from one Observatory to another.

Adolescent↗
PubMed2000

Antibiotic susceptibility and genotypic characterization of Haemophilus influenzae strains isolated from nasopharyngeal specimens from children in day-care centers in eastern France.

OBJECTIVE: To determine the overall carriage rate for Haemophilus influenzae in young children in day-care centers, the frequency of resistance to various classes of antibiotic, and the clonal relationship between isolates of the various resistant phenotypes. METHODS: Nasopharyngeal (NP) specimens were obtained and cultured on chocolate agar with bacitracin. Antibiotic susceptibility testing and serotyping were performed for all isolates. The genetic polymorphism of ampicillin-susceptible and beta-lactamase-producing isolates was studied by pulsed-field gel electrophoresis using SmaI. RESULTS: Of the 596 NP secretion cultures, 152 (25.5%) were positive for H. influenzae. Sixty-four (42.1%) isolates produced beta-lactamase and two (1.3%) were ampicillin resistant but did not produce beta-lactamase. We were unable to serotype 150 isolates; one isolate belonged to capsular serotype e and one to serotype f. Forty-six major DNA patterns were identified among 76 randomized isolates. beta-lactamase producing isolates more frequently showed EP than ampicillin-susceptible isolates P < 10(-4). The frequency of isolates with EP was significantly lower in day-care centers attended by less than 20 children than in those attended by more than 20 children (P = 0.020). CONCLUSIONS: Resistance due to beta-lactamase production has disseminated in some day-care centers, mostly by person-to-person spread but also via the possible conjugal transfer of large plasmids between strains. The size of day-care centers may affect the risk of transmission.

Ampicillin↗
PubMed1996

Pulsed-field gel electrophoresis as an epidemiological tool for clonal identification of Aeromonas hydrophila.

Pulsed-field gel electrophoresis (PFGE) was used to characterize Aeromonas hydrophila strains isolated from a cluster of hospital-acquired infections that occurred over approximately 1 month in a French hospital. Five isolates from patients and 10 isolates from the water supply were characterized by biotyping and antibiotic susceptibility patterns and compared with 10 epidemiologically unrelated strains isolated from patients and rivers, by PFGE of digests of chromosomal DNA. Five environmental and four clinical isolates belonged to the same biotype and antibiotic susceptibility pattern type. The endonucleases XbaI, SpeI and SwaI gave satisfactory profiles whereas DraI did not. The profiles were stable, reproducible and discriminatory. The 10 epidemiologically unrelated strains exhibited 10 different patterns after digestion with XbaI, the least expensive, suitable endonuclease. PFGE is a rapid and discriminatory technique for the typing of Aeromonas hydrophila where a common origin of infection is suspected.

Aeromonas hydrophila↗
PubMed1995

[Listeriosis in patients with malignant hemopathy. 3 cases in the same hospital ward].

During the listeriosis epidemic which occurred in France in the summer 1992, three patients with malignant haematopathies hospitalized in our service contracted the disease. Although the retrospective investigations were hindered by the variable incubation period and the impossibility of examining the foods eaten at the time of infection, there was a high probability that two of the patients had been infected by cooked ham and dairy products at home. The third patient was apparently infected in hospital with well-cooked food found to be contaminated. The hypothesis of coinfection has been raised.

Aged↗
PubMed1995

Effect on Pseudomonas aeruginosa alginate expression of direct plating and culture of fresh cystic fibrosis sputum on to pseudomonas isolation agar containing subinhibitory concentrations of roxithromycin and rifampicin.

The effects of subinhibitory concentrations of roxithromycin (16 mg/L) or rifampicin (16 mg/L) on alginate production by Pseudomanas aeruginosa were investigated. The weight of purified alginate from antibiotic-free cultures was significantly greater (52.5 +/- 24.0 mg, range 22.4-109.5), compared with alginate from cultures bacteria exposed to sub-MIC of roxithromycin (21.9 +/- 17.0, 0.0-42.1 (P < or = 0.037)) and to sub-MIC of rifampicin (28.6 +/- 15.0, 2.9-47.5 (P < or = 0.038)). Chromatographic analysis of hydrolysed and chemically transformed sub-units of alginate revealed that the presence and the molar ratio of D-mannuronic acid and L-guluronic acid were not affected in the remnant alginate exposed to sub-MIC of roxithromycin in contrast to that in the remnant alginate exposed to sub-MIC of rifampicin.

Alginates↗
PubMed1993

[Bacterial contamination of the anterior chamber and cataract surgery].

The authors report the results of bacteriologic cultures of the anterior chamber aspirate after cataract surgery. The results were positive for 15 cases (24%). Nine cultures were positive for 27 eyes operated by phacoemulsification and 6 cultures were positive for 35 eyes operated by extracapsular cataract extraction. The origin of these organisms is the normal bacterial flora of the conjunctiva and the inoculum size is very small. The most commonly identified organisms are coagulase-negative staphylococcus and propionibacterium acnes.

Anterior Chamber↗
PubMed1990

Quantitative effect of roxithromycin and rifampicin on mucoid cultures from directly plated sputum of cystic fibrosis patients chronically colonized with Pseudomonas aeruginosa.

A previous study has shown that non-anti-Pseudomonas aeruginosa antibiotics can modify the mucoid character, a major virulence factor in cystic fibrosis P. aeruginosa. The purpose of the present study was to investigate further this phenomenon using a quantitative approach on fresh sputum. A total of 0.1 to 0.5 ml of sputum were homogenized, decimally diluted, plated on three series of Difco Pseudomonas isolation agar containing no antibiotics, roxithromycin (16.0 microgram/ml) or Rifampicin (16.0 microgram/ml) and incubated at 35 degrees C. In each of the three series, the cfus of PA by ml of sputum were evaluated after 24h, and the entire culture of plates with confluent growth was harvested after 96h and weighed on an analytical scale according to the correlation observed between the mucosity and the density of the culture. To date, 36 sputa from twenty-nine cystic fibrosis patients known to be chronically colonized by mucoid P. aeruginosa have been submitted to the protocol; the mean weight of control, roxithromycin and rifampicin cultures was respectively 3.12 +/- 1.62, 1.90 +/- 1.67 (p less than or equal to 0.0005) and 1.83 +/- 1.24 g (p less than or equal to 0.005) in parallel with mean cfu/ml of 2.24 +/- 6.45 x 10(8) (p less than 0.03) and 1.65 +/- 4.42 x 10(8) (p greater than 0.05); a more constant reduction (greater than or equal to 20%) of mucosity (expressed as the ratio of weight of antibiotic culture/control culture x 100) was observed with rifampicin (29 vs. 23/36 sputa), whereas a more drastic reduction (greater than or equal to 80%) was observed with roxithromycin (12 vs. 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Capnocytophaga septicemia during bone marrow transplantation. Apropos of 2 cases].

Two cases of septicemia due to Capnocytophaga in pediatric bone marrow recipients are reported. These gram negative rods, which are part of the normal buccal flora, cause periodontitis and localized or systemic infections, usually in immunocompromised hosts. Severe, prolonged neutropenia and mucitis due to chemotherapy and/or radiotherapy are risk factors for this opportunistic infection. Recovery can be achieved with most of the drug combinations including a beta-lactam used in hematology.

Bone Marrow Diseases↗
PubMed1988

[Purulent pleurisy caused by anaerobic bacteria. A retrospective study of 19 cases].

A retrospective clinical, biological, radiological and evolutive study of 19 cases of pleural empyema caused by anaerobic organisms diagnosed between 1980 and 1986 was carried out. These 19 cases accounted for 30.6 p. 100 of all cases of pleural empyema diagnosed during the same period. A local or general contributory factor was found in all patients; false passage, gastrointestinal pathology and buccal or dental diseases were the most frequent aetiological circumstances. The clinical picture was rather torpid, with a body temperature below 38 degrees C in 42 p. 100 of the cases, which delayed the diagnosis: the mean time interval between onset and diagnosis was 20 days. In nearly one half of the cases, blood stained expectoration was present and air-fluid levels were visualized at standard radiography and computerized tomography, which is the best exploratory method to evaluate the size and appearance of the pleural lesion, to guide percutaneous drainage and later to assess possible sequelae. The predominant anaerobic flora consisted of Gram-positive cocci and Bacteroides spp; in 70 p. 100 of the cases the anaerobic organism(s) was (were) sensitive to penicillin G. The course of the disease was favourable in all patients. Surgery was performed in 3 of the 19 patients on account of chest wall gangrene due to Clostridium perfringens in 1 case and of the presence of multiple fluid pockets making drainage ineffective in 2 cases.

Adult↗
PubMed1988

[Elimination of various virulence plasmids by antibiotics].

The pathogenicity of some enterobacteria is due to a plasmid encoding for outer membrane proteins or for toxins. The elimination of the plasmid gives a non-virulent strain. We have tried to eliminate plasmids encoding for the thermostable toxin of Escherichia coli (plasmid pCSltl) or for the enteroinvasive property of Shigella (plasmids pWR24, pHW401, pWR110), of Salmonella (plasmid pSD6) and of Yersinia (plasmids pYL4 and P4). The loss of plasmid was confirmed by agarose gel electrophoresis of a crude lysate. Fourteen antibiotics belonging to different chemical families were used at subinhibitory concentration. A control experiment without antibiotic was carried out to detect spontaneous loss of plasmids. No antibiotic was able to eliminate plasmids pCSltl, pHW401, pSD6, pYL4. Novobiocin eliminated pWR24 and pWR110, rifampicin eliminated pWR110 and P4. Three other antibiotics gave a cure of bacteria harbouring plasmids pWR110 and P4 but the percentage of cure was too low for a therapeutical interest.

Anti-Bacterial Agents↗