Search PubMed⌕ Search

Biomedical subjects

M Cormier

Publications and source records attributed to M Cormier.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Tricalcium phosphate, vector of antibiotics: gentamycin and vancomycin. In vitro physicochemical characterization, study of biomaterial porosity and gentamycin and vancomycin elution].

We have investigated a Vancomycin and Gentamycin loaded macroporous tri-calcium phosphate-type beta-ceramic, Calciresorbr. Elution kinetics of Vancomycin and Gentamycin from spheric implants was studied by varying porosity and initial concentrations; then, the other following parameters, that can be modulated and are likely to be involved in this elution process, were analysed: Antibiotic charge: quantitative analysis (titration). qualitative analysis by scanning electron microscopy. Material's porosity: qualitative analysis: optical and scanning electron microscopy. quantitative analysis by stereology and treatment. This physicochemical characterization would favour correct manufacturing of new macroporous synthetic bioceramics in order to achieve satisfactory elution kinetics and homogenous materials.

Biocompatible Materials↗
PubMed1996

Genes transfected into embryonal carcinoma stem cells are both lost and inactivated at high frequency.

Embryonal carcinoma (EC) cells can be efficiently transfected with cloned DNAs but there is a strong tendency for expression from transfected genes to be lost from stably transformed cells. To investigate the mechanism responsible for this loss of expression, we transfected P19 EC cells with a gene encoding the E. coli beta-galactosidase and examined expression of this gene in clonal populations of cells. Cells that carry and express the beta-galactosidase gene give rise to cells that do not express at a rate of about 0.02 events per cell per cell division. These non-expressing cells were of two types, some had lost the transfected genes while others had inactivated them. In those cells that retained but inactivated the transfected genes, the inactive state was stable and suppression was at the level of transcription initiation but not associated with increased DNA methylation. Because transfected DNAs integrate into the genome as tandem arrays, the gene loss and inactivation seen in EC cells may be analogous to the repeat-induced gene inactivation seen in lower eukaryotes.

Animals↗
PubMed1996

Use of peracetic acid as a disinfectant in a water-treatment plant: effect on the plasmid contents of Escherichia coli strains.

Total thermotolerant coliforms (TTC) and Escherichia coli strains were isolated from sewage from a treatment plant before and after peracetic acid (PAA) disinfection. The plasmid profiles of 120 E. coli strains were analyzed. Although PAA disinfection effectively reduced the number of TTC and E. coli strains, the percentage of E. coli strains containing plasmids was not statistically different among water samples. The sizes of the plasmids found ranged from < 3 kb to > 56 kb, but plasmids of between 3 and 5 kb were encountered most frequently.

Disinfectants↗
PubMed1996

Variations in R-plasmid DNA concentrations of Escherichia coli during starvation in sewage and brackish waters.

Cell culturability and plasmid stability in Escherichia coli containing plasmids RP1, R388 and pUB824 were studied in raw and treated wastewater, and in brackish water. The E. coli strain survived well in the three samples of water employed. Moreover, the three plasmids were maintained under all conditions studied. Interestingly, plasmid DNA concentration of individual plasmids followed the same evolution as the culturable bacteria in the corresponding selective medium when the bacteria grew in raw or treated wastewater. In contrast, in brackish water, the stress due to the oligotrophic and salinity conditions of the medium produced an initial paradoxical increase in plasmid DNA concentration, followed by a decrease in the number of culturable bacteria in the corresponding selective medium. Maintenance of RP1 (56 kbp) and R388 (33 kbp) was markedly influenced by nutritive conditions, which caused a segregation of the plasmids from cells. The results of the present study suggest that variations in plasmid DNA concentrations in an aquatic environment depend on the quality of the water and also on the molecular weight of the plasmid considered.

DNA, Bacterial↗
PubMed1996

Effect of seawater on Escherichia coli beta-galactosidase activity.

An investigation of beta-galactosidase activity of Escherichia coli strain H10407, under different physiological and environmental conditions, e.g. induced and uninduced osmotic stress, light, etc., was undertaken. In this study E. coli was employed as a model for faecal coliforms in waste water. beta-Galactosidase activity was induced by isopropyl-beta-D-thiogalactoside (IPTG). Enzyme activity (U cell-1)/cell for sewage bacteria and for induced E. coli was similar, i.e. log U cell-1 = -8.5 whereas uninduced E. coli yielded log U cell-1 = -12.1. Initial enzyme activity was not dependent on phase of growth of the cell (exponential vs stationary phase) or whether marine or fresh water at the time of initial dilution. However, osmotic change resulted in a decrease in culturable cells, even though enzyme activity remained constant. A significant decrease in the number of culturable bacteria, followed by a decrease in beta-galactosidase activity, was observed after exposure of cells to visible light radiation. It is concluded that beta-galactosidase enzyme is retained in viable but non-culturable E. coli. Furthermore, beta-galactosidase appears to offer a useful and rapid (25 min) measure of the viability of faecal coliforms, and therefore, of the water quality of bathing and shellfishing areas.

Chloramphenicol↗
PubMed1996

Retention of enteropathogenicity by viable but nonculturable Escherichia coli exposed to seawater and sunlight.

The effect of natural sunlight on culturability and persistence of pathogenicity of Escherichia coli was examined in the field, i.e., in the Morlaix Estuary, France, using an enterotoxigenic strain of Escherichia coli H10407. Results showed that E. coli responds to the estuarine diurnal solar cycle by entering the viable but nonculturable state upon exposure to sunlight. That is, direct counts of viable cells remained stable without significant change, but E. coli cells remained fully culturable only when exposed to seawater in control chambers in the dark, i.e., without solar irradiation. The effect of sunlight on the pathogenicity of E. coli H10407 was studied, using both the rabbit intestinal loop assay and ganglioside-enzyme-linked immunosorbent assay (GM1-ELISA), a sensitive procedure for testing for production of enterotoxin. Results of the GM1-ELISA demonstrated that strains of E. coli, after exposure to sunlight and entering the viable but nonculturable state, as well as culturable E. coli, retained pathogenicity, i.e., produced enterotoxin. The GM1-ELISA is concluded to be more sensitive than the rabbit intestinal loop assay for analysis of enterotoxin in natural water samples.

Animals↗
PubMed1996

Influence of peracetic acid on Escherichia coli H10407 strain in laboratory microcosms.

The bactericidal properties of peracetic acid (PAA) were tested using Escherichia coli H10407, in sterilized artificial seawater, sewage effluent water, and distilled water microcosms. No LT enterotoxin synthesis was detected by GM1 enzyme-linked immunosorbent assay of the water supernatants, but a specific fragment of the eltB gene was always amplified by polymerase chain reaction for 21 days after PAA treatment. The resuscitation capacity of starved cells was assayed in rich medium and their inability to overcome the effects of PAA stress was observed, despite the emergence of viable but nonculturable cells in microcosms 24 or 48 h after treatment. Moreover, no obvious differences in response were obtained, concerning enterotoxigenesis, between bacteria subjected to osmotic and (or) nutrient starvation-induced stress with or without PAA treatment.

Artifacts↗
PubMed1996

[Tricalcium phosphate and gentamycin. In vitro and in vivo antibiotic diffusion, rehabilitation in bone site in sheep].

Several different materials have been proposed as vectors to carry antibiotics to bone tissue. No material currently available satisfies all the prerequisites for the treatment of chronic osteitis with a simple procedure. The aim of this study was to assess the antibiotic releasing capacity of gentamycin-loaded beta tricalcium phosphate in vitro and in vivo in a sheep model. Experimental results showed that beta tricalcium phosphate can release a large percentage of its antibiotic load and that the kinetics of antibiotic release can be modulated by changing the volume and porosity of the blocks. This material is also well tolerated by the host and has the advantage of being porous and resorbable. Use of these properties would appear to be a major progress in the treatment of chronic bone infections.

Animals↗
PubMed1995

Conjugal transfer of natural plasmids between Escherichia coli strains in sterile environmental water.

Seven antibiotic-multiresistant Escherichia coli strains, possessing three or four plasmids, capable of transferring their resistance marker at a high frequency, were selected among a total of 300 antibiotic-resistant E. coli strains isolated from natural water--raw and treated wastewater, and brackish water (collected 1 km downstream). These strains were mated with E. coli K-12 C600 nalr, both in sterilized natural water and LB medium at 25 degrees C. Conjugation did occur in all the systems tested, although fewer transconjugants were recovered from raw and treated wastewater experiments. In contrast, in brackish and seawater, the transfer frequency did not significantly decrease in spite of salt contents. In 100% of the cases, transfer of the high-molecular-weight plasmids (> or = 20 kb) was observed, but the small plasmids (2.6-7.5 kb) were only cotransferred in raw or treated wastewater and in brackish water. Moreover, genotypic variation occurred more frequently in natural water than in LB medium.

Conjugation, Genetic↗
PubMed1994

Detection of enterotoxigenic Escherichia coli in water by polymerase chain reaction amplification and hybridization.

Enterotoxigenic Escherichia coli was studied in waste water, river water, and seawater from six locations along the west coast of Normandy by using the polymerase chain reaction (PCR) to amplify the heat labile (LT) gene. Cellular DNA was extracted from centrifugation pellets and amplified using PCR. The PCR products were detected by gel electrophoresis and confirmed by hybridization assay, using an 850 base pair HindIII DNA fragment probe from pEWD299 conjugated to digoxigenin and specific for the LT gene. Results of the PCR amplification were compared with those of GM1 enzyme-linked immunosorbent assay, latex agglutination, and colony hybridization. The PCR method was found to be more precise and less time consuming, especially when compared with methods requiring culture of isolates for enumeration of enterotoxigenic E. coli in water.

Base Sequence↗
PubMed1993

Two-dimensional electrophoresis method used for determination of plasmid profiles of Escherichia coli isolated from a sewage treatment plant.

The plasmid contents of 306 strains of Escherichia coli isolated from raw and treated sewage from a treatment plant as well as from the water 1 km downstream were determined. The number and molecular weight of plasmids isolated from a representative sample of these strains were also measured. It was observed that biological treatment did not significantly alter these parameters. In contrast, statistically significant differences in plasmid number and size were observed when strains from sewage (raw and treated) were compared with strains isolated from brackish water. In raw and treated sewage, more than 96% of the strains contained plasmids, compared with 85% in brackish water. Nine to 13% of the strains from sewage contained plasmids with more than 56 kilobases, while only 5% of the strains from brackish water reached this size.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1992

Synergistic effect of flavones and flavonols against herpes simplex virus type 1 in cell culture. Comparison with the antiviral activity of propolis.

The in vitro activity against herpes simplex virus type 1 of the major flavonoids identified in propolis was investigated. Flavonols were found to be more active than flavones, the order of importance being galangin, kaempferol, and quercetin. The efficacy against HSV-1 of binary flavone-flavonol combinations has been also investigated. The synergy demonstrated by all combinations could explain why propolis is more active than its individual compounds.

Animals↗
PubMed1991

Occult neurovesical dysfunction in children with imperforate anus and its variants.

Neurovesical dysfunction (NVD) is frequently encountered in children with imperforate anus and its variants. Such functional urologic problems are often compounded by associated anatomic urologic abnormalities that in combination may profoundly alter the course and prognosis of children with imperforate anus. Herein, we report 16 such cases. Management of NVD in children with imperforate anus offers several unique challenges that require important alterations in management. Specific recommendation are presented.

Anus, Imperforate↗
PubMed1991

In vitro cutaneous biotransformation of propranolol.

The metabolism of propranolol by human skin and by several cell preparations has been investigated in vitro. The major metabolites produced by human skin in organ culture and by keratinocytes were N-desisopropylpropranolol (DIP), propranolol glycol (GLY), and naphthoxylactic acid (NLA). Formation of GLY and NLA was linear with incubation time up to 6 d and was directly proportional to propranolol concentration. Fibroblasts and melanocytes also produced GLY and NLA, but appeared to have lower propranolol-biotransforming activity than keratinocytes. The three metabolites detected arise from side-chain oxidation of propranolol, and the use of specific enzyme inhibitors determined that monoamine oxidase and cytochrome P450 isozymes are involved in their formation. Aldehyde and alcohol dehydrogenases are also probably involved in the formation of NLA and GLY, but attempts to inhibit these enzyme systems were inconclusive, possibly due to the chemical instability of the intermediate aldehyde resulting from monoamine oxidase activity. No evidence was found for conjugation or ring oxidation by the skin or isolated cells. Induction of keratinocyte differentiation with Ca++ or phorbol ester treatment resulted in an increase of overall biotransformation and the NLA/GLY ratio.

Adult↗
PubMed1991

[Adaptation to the Biomek 1000 workstation (Beckman) of the MHA-TP technique (Ames)].

The microhemagglutination-Treponema pallidum (MHA-TP) was automated with the Biomek 1000 workstation (Beckman). 3,000 serum specimens were studied with manual and automated procedures. Thirty nine serum specimens were found positive by both techniques, neither false positive nor false negative results were observed with the Biomek 1000 workstation. The statistical analyse showed no differences between the two procedures, variations were observed only with low titer sera. In conclusion, time saving and augmentation of productivity obtained by automation of this method could be interesting for a microbiology laboratory.

Diagnosis, Computer-Assisted↗