PubMed Health⌕ Search

Biomedical subjects

M Cormier

Publications and source records attributed to M Cormier.

At least 19 recordsLinked to original sources
PubMed2003

Influence of peracetic acid on adhesion/invasion of Salmonella enterica serotype typhimurium LT2.

The influence of peracetic acid (PAA) disinfectant on Salmonella enterica serotype Typhimurium LT2 in sewage effluent was examined by studying its ability to adhere to and invade HeLa cells in vitro. Although the disinfectant produced a decrease of about 5 log units, the bacteria kept their adhesive and invasive abilities. Scanning microscopic observations of the PAA-treated bacteria revealed that PAA caused a loss of external microfilaments and an alteration of membrane structure. Nevertheless, electron-microscopic observations showed that PAA-treated bacteria were still able to adhere to and invade HeLa cells despite the fact that the bacteria seemed to have undergone some structural modifications. With confocal microscopy, the use of anti-actin antibody showed that the contact between the bacteria (with or without PAA treatment) and the HeLa cells activated actinopolymerization of the HeLa cell cytoskeleton.

Bacterial Adhesion↗
PubMed2000

Proteins variations in Listeria monocytogenes exposed to high salinities.

Listeria monocytogenes Scott A grown in the minimal chemically defined medium M6LT was challenged to a concentration of either 35 or 65 g l(-1) of NaCl for 1 h in the presence of a [35S]cysteine-[35S]methionine labelling mix. The protein patterns were analysed by 2D-electrophoresis in the two conditions and isoosmotic condition (5 g l(-1) of NaCl in M6LT). A great number of proteins which were synthesized under isoosmotic conditions were either completely repressed or expressed at a reduced level, at 65 g l(-1) and to a lesser extent at 35 g l(-1) of NaCl. At 35 g l(-1) of NaCl, six proteins were up-regulated, five proteins showed no change in expression level and five were repressed. Among the proteins up-regulated at 35 g l(-1) of NaCl, a single one (18.7 kDa, pI 5.05) was up-regulated at 65 g l(-1) too. We observed 21 proteins which were repressed at 65 g l(-1) of NaCl, among which 11 completely disappeared. Some of the up-regulated proteins have characteristics of molecular weight and isoelectric point close to those of stress proteins reported elsewhere: the protein induced both at 35 and 65 g l(-1) might correspond to a previously proposed universal stress protein of Listeria. Some proteins which were repressed at 65 g l(-1) have molecular weights close to those of virulence proteins.

Bacterial Proteins↗
PubMed2000

In vitro susceptibilities of Capnocytophaga isolates to beta-lactam antibiotics and beta-lactamase inhibitors.

The susceptibilities of 43 pharyngeal isolates of Capnocytophaga to beta-lactam antibiotics, alone or in combination with beta-lactamase inhibitors, were tested by an agar dilution method. The 34 beta-lactamase-positive strains were highly resistant to beta-lactams, but the intrinsic activities of clavulanate, tazobactam, and sulbactam against Capnocytophaga, even beta-lactamase producers, indicates that these beta-lactamase inhibitors could be used for empirical treatment of neutropenic patients with oral sources of infection.

Anti-Bacterial Agents↗
PubMed2000

Osmotic stress-induced genetic rearrangements in Escherichia coli H10407 detected by randomly amplified polymorphic DNA analysis.

Randomly amplified polymorphic DNA (RAPD) analysis is a DNA polymorphism assay commonly used for fingerprinting genomes. After optimizing the reaction conditions, samples of Escherichia coli H10407 DNA were assayed to determine the influence of osmotic and/or oligotrophic stress on variations in RAPD banding patterns. Genetic rearrangements or DNA topology variations could be detected as changes in agarose gel electrophoresis banding profiles. A new amplicon generated using DNA extracted from bacteria prestarved by an osmotic stress and resuscitated in rich medium was observed. Enrichment improved recovery of mutator cells and allowed them to be detected in samples, suggesting that DNA modifications, such as stress-induced alterations and supercoiling phenomena, should be taken into consideration before beginning RAPD analyses.

Base Sequence↗
PubMed1999

Effect of transdermal iontophoresis codelivery of hydrocortisone on metoclopramide pharmacokinetics and skin-induced reactions in human subjects.

The effects of transdermal iontophoresis (IP) codelivery of hydrocortisone (HC) on metoclopramide hydrochloride (MCP) pharmacokinetics and on skin-induced reactions were evaluated in a randomized, crossover clinical study. MCP, an antiemetic, low molecular weight, cationic drug intended for systemic delivery, was delivered from the anode of IP systems at a constant current of 100 microA/cm(2). HC, a neutral endogenous antiinflammatory agent, was codelivered from the same electrode, primarily by electroosmotic processes. Each subject (n = 7) wore two identical IP systems (MCP alone or MCP plus HC), each supplying 500 microA, one on each upper arm for 4 h. One week later, each subject repeated the procedure with the alternate type of MCP system. HC did not change the pharmacokinetics of MCP: There were no statistically significant differences in MCP plasma concentrations, half-life, area under the curve (AUC), or rate of absorption between the two treatment groups. However, HC significantly decreased erythema and edema scores produced by the IP of MCP. In both groups, a steady-state MCP flux of about 100 microg/(cm(2) x h) was achieved after only 1 h of transport, and input rate dropped dramatically immediately after removal of the system. In vitro, HC flux through human epidermis from an MCP plus HC formulation was 2.8 +/- 1.1 microg/(cm(2) x h) after 4 h transport at 100 microA/cm(2), suggesting negligible systemic exposure to hydrocortisone. These data indicate that MCP input rate and its clearance from the skin are unaltered by HC and that the codelivery of HC by IP is an effective strategy for inhibition of local reactions resulting from the transdermal delivery of drugs.

Administration, Cutaneous↗
PubMed1999

Nanomolar levels of dimethylsulfoniopropionate, dimethylsulfonioacetate, and glycine betaine are sufficient to confer osmoprotection to Escherichia coli.

We combined the use of low inoculation titers (300 +/- 100 CFU/ml) and enumeration of culturable cells to measure the osmoprotective potentialities of dimethylsulfoniopropionate (DMSP), dimethylsulfonioacetate (DMSA), and glycine betaine (GB) for salt-stressed cultures of Escherichia coli. Dilute bacterial cultures were grown with osmoprotectant concentrations that encompassed the nanomolar levels of GB and DMSP found in nature and the millimolar levels of osmoprotectants used in standard laboratory osmoprotection bioassays. Nanomolar concentrations of DMSA, DMSP, and GB were sufficient to enhance the salinity tolerance of E. coli cells expressing only the ProU high-affinity general osmoporter. In contrast, nanomolar levels of osmoprotectants were ineffective with a mutant strain (GM50) that expressed only the low-affinity ProP osmoporter. Transport studies showed that DMSA and DMSP, like GB, were taken up via both ProU and ProP. Moreover, ProU displayed higher affinities for the three osmoprotectants than ProP displayed, and ProP, like ProU, displayed much higher affinities for GB and DMSA than for DMSP. Interestingly, ProP did not operate at substrate concentrations of 200 nM or less, whereas ProU operated at concentrations ranging from 1 nM to millimolar levels. Consequently, proU(+) strains of E. coli, but not the proP(+) strain GM50, could also scavenge nanomolar levels of GB, DMSA, and DMSP from oligotrophic seawater. The physiological and ecological implications of these observations are discussed.

Amino Acid Transport Systems↗
PubMed1998

Absence of p53-dependent cell cycle regulation in pluripotent mouse cell lines.

We examined the expression of p53 in three lines of pluripotent embryonal carcinoma (EC) and ES cells. p53 mRNA and protein levels were constitutively high in two lines but absent from one. In the P19 line of EC cells neither p53 protein nor mRNA was detected. The first intron of the p53 gene in these cells had been invaded by a murine leukemia virus and there was extensive hypermethylation of the p53 gene accompanying its inactivation. In all three cell lines, irradiation resulted in arrest of the cells in the G2 but not in the G1 phase of the cell cycle despite the induction of p21cip1 in the cell lines expressing p53. Thus, the chromosomal stability of EC and ES cells appears to be not dependent on the p53 protein and we interpret our results to suggest that these cells may require the deletion of p53 dependent cell cycle regulation in order to become immortalized.

3T3 Cells↗
PubMed1998

Pharmacokinetics, uses, and limitations of vancomycin-loaded bone cement.

We have studied the mechanical and pharmacokinetic characteristics of an industrially-prepared bone cement containing 3 g of vancomycin per 60 g cement. A low viscosity cement was selected, to increase contact between the antibiotic and the infected surfaces. Resistance of compression (95 mPa) was well above the required standard (70 mPa) and similar to that of other cements with or without gentamicin. The concentrations in blood, urine and bone were measured in mg/l and mg/kg, and compared to the break point (BP) of susceptibility tests, which must be obtained to achieve control of infection. Diffusion tests were conducted in vitro (elution in saline from rods), and in 30 sheep femora implanted with the cement in vivo. In the animal study, bone levels during the first three months were three-fold higher than the BP (i.e., were > or = 12 mg/l) in 92% of specimens from all areas of bone studied and at all times since implantation; they exceeded five times the BP in 56% of specimens and were never lower than twice the BP. The mean level was four times the BP after six months and fell sharply during the next six months. A pharmacokinetic study in ten patients who had a primary total hip arthroplasty with vancomycin-loaded cement as prophylactic antibiotic therapy showed that blood levels were lower than 3 micrograms/ml, i.e., 30 times lower than the toxic threshold (90 micrograms/ml). Vancomycin was undetectable in urine after the tenth day. The levels in drainage fluids were five times the BP after 24 h and equal to it after four days. None of the ten patients treated prophylactically with vancomycin-loaded cement developed evidence of allergy, toxicity, intolerance or loosening during a two year period. No adverse events were recorded in 17 other patients treated with a vancomycin (2 g) plus gentamicin (0.8 g) loaded cement as adjuvant therapy for severe prosthetic infection.

Animals↗
PubMed1998

A role for RNA processing in regulating expression from transfected genes.

We have examined the expression of cloned genes following their stable integration into the genome of pluripotent embryonal carcinoma stem cells. Transfected genes integrate into the genome as tandem arrays. Expression of reporter genes from these tandem arrays in embryonal carcinoma cells is inefficient probably because genes are subject to repeat-induced gene silencing. We found that expression of reporter genes was significantly enhanced if co-transfected with cloned fragments derived from the murine Pgk-1 gene. The enhanced expression required (a) that the Pgk-1 fragment carries an active promoter, (b) that the promoter drives transcription through a region of more than 12 kbp, and (c) that this transcribed region contains both introns and exons. Reporter gene activity did not require specific Pgk-1 DNA sequences suggesting that the coupled processes of transcription and RNA processing conferred activity on neighboring genes probably by influencing local chromatin structure. Consistent with this idea, the effect of the Pgk-1 gene could be mimicked by exposing cells to butyrate or trichostatin A, inhibitors of histone deacetylase. Thus, the effect of the co-transfected Pgk-1 gene is to inhibit the process of gene inactivation possibly by functioning like an insulator or boundary element in the chromatin.

Animals↗
PubMed1998

Incidence of Listeria spp. in Breton live shellfish.

Live shellfish samples (120) were collected from nine littoral sites in Brittany (western France). They were screened for Listeria spp. and a count of faecal coliforms was carried out. Analysis of the results revealed Listeria spp. in 55% of samples, a much higher rate than the previous, infrequent, recorded data. Furthermore, the study demonstrated that the frequency of Listeria spp. in winter was more important than in summer (P < 0.001), and underlined a significant relationship between the occurrence of these bacteria and the concentration of faecal coliforms (P < 0.001). Finally, comparison of the official and Gen-Probe methods revealed the limits of the standardized technique in the search for L. monocytogenes in shellfish.

Incidence↗
PubMed1997

Reverse iontophoresis: monitoring prostaglandin E2 associated with cutaneous inflammation in vivo.

In response to topical application of irritants, increased concentrations of prostaglandin E2 (PGE2) are found in human skin exudate and in cultured dermal fibroblasts. In this study, PGE2 generated in response to transdermal delivery of irritant drug compounds was monitored in hairless guinea pig (HGP) by a non-invasive method, reverse iontophoresis. Reverse iontophoresis is the movement of molecules from the skin under the influence of an applied electric field. Irritant drug compounds were applied with iontophoresis (electrotransport), and reverse iontophoresis of PGE2 from skin was monitored by radioimmunoassay (RIA) after extraction from the delivery system. Chlorpromazine was used as a model drug irritant. When chlorpromazine and saline were applied over a range of current densities from 0 to 200 microA/cm2, visual scores of erythema and edema yielded a correlation with measured skin efflux of PGE2 (r = 0.86). Delivery of chlorpromazine resulted in greater efflux of PGE2 than delivery of non-irritant saline controls under the same delivery conditions. Five drug compounds, chloroquine, promazine, chlorpromazine, tetracaine, metoclopramide, and saline were applied to hairless guinea pig skin. The 6 agents were similarly rank ordered by visual erythema/edema scores and by PGE2 efflux, indicating that the quantity of PGE2 effluxed reflects the intensity of skin irritation. In contrast, vasoconstriction or vasodilation produced by the local delivery of vasoactive agents did not correlate with PGE2 skin efflux, indicating that this measurement is specific for an inflammatory response. In summary, PGE2 generated in response to transdermally applied drug irritants can be monitored non-invasively in vivo by reverse iontophoresis.

Amebicides↗
PubMed1997

Antiflammin 1 peptide delivered non-invasively by iontophoresis reduces irritant-induced inflammation in vivo.

The potential of an anti-inflammatory peptide (antiflammin 1) to reduce irritation when delivered transdermally by iontophoresis was examined. A model drug irritant, chlorpromazine, was co-delivered with and without antiflammin 1 by iontophoresis to hairless guinea pigs transdermally. Quantitative skin irritation measurements were obtained by monitoring erythema by skin color reflectance with the Minolta Chromameter. Antiflammin 1 delivered by iontophoresis significantly decreased, but did not eliminate, the erythema associated with co-delivery of an irritating drug compound. Lesion formation was also reduced in the presence of antiflammin 1. In vitro flux across hairless guinea pig skin demonstrated no significant differences in flux of the irritant compound in the presence or absence of antiflammin 1. In vivo generation and efflux of the inflammation mediator Prostaglandin E2 increased during 24-h application of irritant and was unchanged in the presence of antiflammin 1. This result is discussed with respect to recent evidence that antiflammins may act on the lipo-oxygenase pathway. In summary, antiflammin 1, an anti-inflammatory peptide, can be delivered transdermally by iontophoresis with retention of its biological activity in vivo.

Administration, Cutaneous↗
PubMed1997

Molecular epidemiological survey of rotaviruses in sewage by reverse transcriptase seminested PCR and restriction fragment length polymorphism assay.

Rotavirus double-stranded RNA was detected directly in sewage treatment plant samples over a 1-year period by reverse transcription followed by PCR amplification of the VP7 gene and Southern blot hybridization. The presence of naturally occurring rotaviruses was demonstrated in 42% of raw sewage samples and in 67% of treated effluent samples. Amplified viral sequences were analyzed by restriction enzymes. Ten different restriction profiles were characterized, most of which were found in treated effluent samples. A mixture of restriction profiles was observed in 75% of contaminated effluent samples. The profiles were compared with those obtained from human rotavirus isolates involved in infections in children from the same area (six different profiles were detected). Five identical viral sequences were detected in both environmental and clinical samples. Restriction profiles were also compared to profiles from known genomic sequences of human and animal viruses. Both human and animal origins of rotavirus contamination of water seemed likely.

Animals↗
PubMed1997

Development of an enzyme-linked immunosorbent assay for measurement of serum-associated ALX40-4C.

ALX40-4C is an antiretrovirus agent that has been found to have some inhibitory properties against human immunodeficiency virus (HIV) replication in vitro. The compound was designed as a competitor of the HIV Tat protein for TAR binding. In addition to its anti-HIV properties, it has demonstrated the ability to inhibit in vitro replication of herpes simplex virus types 1 and 2 as well as human cytomegalovirus. Subsequently, in vivo pharmacokinetic evaluation of ALX40-4C necessitated the establishment of a detection system for the measurement of ALX40-4C in subject serum. For this purpose, an indirect-competition enzyme-linked immunosorbent assay with generated rabbit anti-ALX40-4C antiserum was developed. The original assay took 12 h to complete and required many manipulations. Herein, we describe alterations to the system that resulted in the overall reduction in assay time and manipulation. We demonstrate that our alterations do not affect the specificity or sensitivity of the assay compared to that of the original system. ALX40-4C levels in spiked serum samples as well as drug levels from patient samples were used to validate the assay.

Animals↗
PubMed1997

Quantification of human immunodeficiency virus type 1 RNA from dried plasma spots collected on filter paper.

To assess dried plasma spots (DPSs) as a source of material for virus quantification, human immunodeficiency virus type 1 (HIV-1) RNA levels were quantified in matched DPS and liquid plasma samples from 73 infected patients, including 5 neonates and 4 adult patients with acute HIV-1 infection. Quantifications were performed by commercially available assays (NASBA [nucleic acid sequence-based amplification] or Amplicor, or both). There was a strong correlation between HIV-1 RNA levels in plasma and DPSs. More importantly, there was no decline in HIV-1 RNA levels in DPSs stored for as long as 2 weeks at 20 degrees C. Similarly, storage of DPSs for 3 days at 37 degrees C resulted in no decrease in viral RNA levels. For patients with primary infection, the DPS method allowed for the measurement of RNA levels in plasma during the initial spike in the level of viremia and in the subsequent period of suppressed viral replication. DPS quantification was equally informative in the neonatal setting, with all five newborns showing HIV-1 RNA loads of greater than 4.991 log10 copies/ml. We conclude that the viral RNA levels in DPSs are equivalent to those measured in fresh-frozen plasma. The ease and economy of DPS sampling, the minute volumes required, and the unexpected stability of dried RNA suggest that the use of DPSs will be particularly valuable for small-volume neonatal samples and large, population-based studies in which cold storage and transportation present special problems, as is often the case in developing countries. The ability to measure viral changes during primary infection suggests that the method will be useful for assessing vaccine efficacy in large field trials.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Survival of Escherichia coli exposed to visible light in seawater: analysis of rpoS-dependent effects.

We investigated the effect of visible light on Escherichia coli in seawater microcosms. Escherichia coli lost its ability to form colonies in marine environments when exposed to artificial continuous visible light. Survival of illuminated bacteria during the stationary phase was drastically reduced in the absence of the sigma factor (RpoS or KatF) that regulates numerous genes induced in this phase. In the stationary phase, double catalase mutants katE katG and mutants defective in the protein Dps (both catalase and Dps are involved in resistance to hydrogen peroxide (H2O2)), were more sensitive to light. In the exponenital phase, a mutation in oxyR, the regulatory gene of the adaptive response to H2O2, increased sensitivity to light, further suggesting that deleterious effects might be associated with H2O2 production. However, in the stationary phase, the katE katG dps mutant was considerably more resistant to visible light than the rpoS mutant, suggesting rpoS-dependent protection against deleterious effects other than those related to H2O2. The deleterious action of visible light was less important when the salinity decreased. In freshwater, rpoS and katE katG dps mutants did not show a drastic difference in sensitivity to light suggesting that osmolarity sensitizes E. coli to those deleterious effects of visible light that are unrelated to H2O2.

Bacterial Proteins↗
PubMed1997

Production of Escherichia coli group I-like heat-labile enterotoxin by Enterobacteriaceae isolated from environmental water.

Strains of Klebsiella oxytoca (2), Citrobacter freundii (2), Enterobacter cloacae (1) and Escherichia coli (1) isolated from environmental water were identified as heat-labile enterotoxin (LT) producing strains by immunological methods and polymerase chain amplification. A 322 bp amplified fragment was obtained with specific primers LTR and LTL, and hybridized to a digoxigenin-labelled LTB probe only under low stringency conditions, and not with a cholera toxin probe. These results suggest that Enterobacteriaceae may produce a LT-like toxin antigenically and genetically related to the LT enterotoxin of E. coli.

Bacterial Toxins↗