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C Mouton

Publications and source records attributed to C Mouton.

At least 19 recordsLinked to original sources
PubMed1998

Post-transcriptional control of c-myc RNA during early development analyzed in vivo with a Xenopus-axolotl heterologous system.

We have set up a heterologous in vivo system to study gene regulation at the post-transcriptional level during early development. This system uses two amphibian species, Xenopus laevis and Ambystoma mexicanum (axolotl), the development of which is three to four times slower than that of X. laevis. The stability of three different synthetic X. laevis c-myc transcripts was followed after injection into fertilized axolotl eggs. One transcript is 2.2 kilobases (kb) long (full-length). The second is 1.5-kb long with most of the 3' untranslated region (3'UTR) removed, and the third corresponds to the 3'UTR (0.7-kb). The behavior of the endogenous axolotl c-myc RNA was compared with the exogenous injected c-myc transcripts. Our results show the existence of several developmental timers controlling degradation of the c-myc molecules. The first is activated at oocyte maturation and affects both the endogenous and exogenous (2.2- and 1.5-kb) transcripts containing the coding regions. A second timer could be linked to the number of cell divisions since fertilization (6th-7th cleavages) and involves the endogenous c-myc RNAs. Another timer could involve the c-myc mRNA molecule itself, because when injected into axolotl eggs, the half-life of the 2.2-kb X. laevis transcript appears to be independent of the axolotl context. After injection into axolotl fertilized eggs, the behavior of this X. laevis full-length c-myc molecule reveals an unexpected increase in the intensity of its autoradiographic signals. This increase occurs independently of events linked to mid-blastula transition and preliminary investigations are discussed.

Amanitins↗
PubMed1998

beta-Lactamase-producing strains in the species Prevotella intermedia and Prevotella nigrescens.

A total of 96 strains were collected that included laboratory strains and clinical isolates classified Prevotella intermedia sensu lato and the type strains of the species P. intermedia sensu stricto and Prevotella nigrescens. Susceptibility to amoxicillin and amoxicillin-clavulanic acid was determined by the Etest. PCR-DNA probe assays were used to speciate each strain as P. intermedia sensu stricto or P. nigrescens. By Etest, 71 strains (74%) were susceptible to both amoxicillin and amoxicillin-clavulanic acid with minimum inhibitory concentrations in the 0.016-0.064 microgram/ml range. In contrast, amoxicillin minimum inhibitory concentrations of 25 strains (26%) were in the range of 1.5-96 micrograms/ml with concomitant amoxicillin-clavulanic acid minimum inhibitory concentrations in the low range 0.016-0.38 microgram/ml, indicating a production of beta-lactamase as confirmed by nitrocefin tests. Of these beta-lactamase-producing strains, 20% (5/25) were identified as P. intermedia sensu stricto by the PCR-DNA probe assay and 72% (18/25) as P. nigrescens. Our results provide support for the major role of P. nigrescens in the failure of therapy using beta-lactam antibiotics.

Anti-Bacterial Agents↗
PubMed1997

Detection of Bacteroides forsythus by immunomagnetic capture and a polymerase chain reaction-DNA probe assay.

The aim of this study was to combine immunomagnetic capture and a polymerase chain reaction (PCR) followed by hybridization with a DNA probe for the detection of Bacteroides forsythus. Magnetic beads were coated with the immunoglobulin G fraction of an antiserum specific for B. forsynthus. Aliquots were incubated with various concentrations of a suspension of B. forsythus or with a suspension containing 16 bacterial species, at a concentration of 10(10) cells/ml, spiked with dilutions of B. forsythus. Beads with bound bacteria were boiled, and the target DNA in the supernatant was amplified to generate a 392-bp PCR fragment specific for B. forsythus. The amplified product was detected by dot-blot hybridization with a digoxigenin-labeled 392-bp probe. The detection limit was determined to be 10 cells/ml using immunocapture on a suspension of B. forsythus and 100 on spiked bacterial suspensions. Subgingival plaque samples were obtained from 39 Bolivian individuals with poor oral hygiene. Each sample was analyzed by the above procedure and by immunofluorescence. The overall prevalence of individuals harboring B. forsythus was 62% by immunofluorescence and 82% by PCR-DNA probe assay. The immunocapture, PCR. DNA-probe procedure should be useful for the detection of B. forsythus, particularly in false-negative samples obtained by less sensitive techniques.

Adolescent↗
PubMed1997

Evaluation of root canal bacteria and their antimicrobial susceptibility in teeth with necrotic pulp.

This study aimed to evaluate the microbiota of necrotic pulp in teeth without carious lesions where the crown and root were intact and to test the sensitivity of this microbiota to antibiotics in order to improve treatment. The necrotic pulp was sampled from 26 single-rooted teeth in intact pulp chambers. A total of 84 strains were isolated. The number of species isolated per tooth varied from 2 to 8, with a strong component (81%) of anaerobic bacteria. The most commonly represented species were Bacteroides gracilis, Propionibacterium acnes, Fusobacterium nucleatum, Prevotella buccae and Eubacterium lentum. The sensitivity of these organisms to amoxicillin, amoxicillin combined with clavulanate and tetracycline was evaluated by Etest on 38 isolates. For all strains tested, the minimum inhibitory concentration values obtained were low and substantially below effective serum concentrations for these antibiotics. These data enable us to devise suitable treatments for acute development of apical lesions and to prevent dissemination of this source of infection to the rest of the host.

Amoxicillin↗
PubMed1997

Conservation of fimbriae and the hemagglutinating adhesin HA-Ag2 among Porphyromonas gingivalis strains and other anaerobic bacteria studied by epitope mapping analysis.

Monoclonal antibodies characterized as antifimbria and anti-HA-Ag2 were used in immunoblotting to examine the antigenic distribution of fimbriae and HA-Ag2 among a collection of human and animal Porphyromonas strains and human Prevotella and Bacteroides strains. The results showed that fimbrial and HA-Ag2 antigenic structures are peculiar to the species Porphyromonas gingivalis.

Animals↗
PubMed1997

Fimbriae and the hemagglutinating adhesin HA-Ag2 mediate adhesion of Porphyromonas gingivalis to epithelial cells.

The mechanisms by which Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is pathogenic for the periodontium remain largely hypothetical. Invasion of host tissues by P. gingivalis is believed to require adhesion of the bacterium to host cells. The aim of this study was to use monoclonal antibodies (MAbs) to characterize the bacterial cell surface component(s) acting as a ligand binding to a receptor on epithelial cells. Surface antigens of P. gingivalis ATCC 33277 were obtained as a glass bead-EDTA extract (GBE), and antiserum against the GBE was produced in rabbits. Epithelial cell membrane proteins (ECMP) were prepared from a homogenate of the SK-MES-1 cell line with Triton X-100. The antigen/ligand profile of GBE was resolved by crossed immunoaffinity electrophoresis by using ECMP in the first-dimension gel. The migration of one immunoprecipitate (IP) was retarded, indicating a ligand-receptor interaction between a surface antigen of P. gingivalis and a complementary binding site on the epithelial cell membrane. The corresponding IP in the GBE/anti-GBE immunoelectrophoresis profile was excised from replicate gels to immunize mice for production of MAbs specific for the bacterial ligand. Five MAbs were obtained and tested for reactivity with GBE in immunoblots and for inhibition of the interaction between GBE and ECMP. Immunoblots revealed polypeptides at 28, 42, 43, and 49 kDa. Inhibition tests were positive for all five MAbs. These results are conclusive evidence that the MAbs recognize functional epitopes involved in the adherence of P. gingivalis to epithelial cells and that the adhesins are likely associated with fimbriae and the hemagglutinating adhesin HA-Ag2.

Adhesins, Bacterial↗
PubMed1997

PCR-DNA probe assays for identification and detection of Prevotella intermedia sensu stricto and Prevotella nigrescens.

The purpose of this study was to construct PCR-DNA probe assays specific for Prevotella intermedia sensu stricto and Prevotella nigrescens based on the ability of randomly amplified polymorphic DNA (RAPD) fingerprinting to generate species-specific markers. The strategy included four steps: (i) construction of first-generation DNA probes from a 850-bp RAPD marker for P. intermedia sensu stricto and a 1,300-bp RAPD marker for P. nigrescens, (ii) cloning and sequencing of each RAPD marker, (iii) designing of primer pairs flanking specific internal sequences of 754 bp for P. intermedia sensu stricto and of ca. 1,100 bp for P. nigrescens, and (iv) synthesis (by PCR amplification) and digoxigenin labeling of quantities of DNA probes 754 and ca. 1,100 bp in size. The PCR-DNA probe assays combine either PCR amplification of a 754-bp specific sequence in the genomic DNA of strains of P. intermedia sensu stricto and hybridization with the 754-bp digoxigenin-labeled probe or amplification of a ca. 1,100-bp sequence of P. nigrescens and hybridization with the ca. 1,100-bp probe. Specific hybridization was observed with the amplified DNAs from 25 strains of P. intermedia and 24 strains of P. nigrescens, and no reaction was observed with the PCR products from 20 foreign species. The PCR-DNA probe assays described here should allow a highly specific and sensitive detection of P. intermedia sensu stricto and P. nigrescens in mixed infections.

Bacterial Typing Techniques↗
PubMed1996

A PCR-DNA probe assay specific for Bacteroides forsythus.

Bacteroides forsythus is a fastidious anaerobic Gram-negative organism associated with active periodontal disease. The ability of random amplified polymorphic DNA (RAPD) fingerprinting to generate species-specific markers was exploited towards the construction of a polymerase chain reaction (PCR)-DNA probe assay specific for B. forsythus. The strategy included the four following steps: (1) construction of a first generation DNA probe based on a 507-bp RAPD species-specific marker; (2) cloning and sequencing the 507-bp RAPD marker; (3) design of the primer pair Bf 392-1/Bf 392-2 flanking a 392-bp specific internal sequence; and (4) synthesis of quantities of a 392-bp second generation DNA probe by PCR amplification. The PCR-DNA probe assay includes a PCR amplification of a 392-bp specific sequence in the genomic DNA of B. forsythus strains followed by hybridization with the 392-bp digoxigenin-labelled second generation probe. We observed strong, specific hybridization with the amplified DNAs from 11 stains of B. forsythus and no cross-hybridization with the PCR products from 22 foreign species. The PCR-DNA probe assay must be seen as a highly specific and sensitive method for the detection of B. forsythus in mixed infections.

Bacteroides↗
PubMed1996

[Anaphylactic shock after tourniquet removal in orthopedic surgery].

Case report of six patients who experienced symptoms of severe anaphylactic shock, after tourniquet release at the end of minor orthopaedic surgery of the limbs under regional anaesthesia. The immunological mechanism of the shock was confirmed by prick tests. The causative agent was rifamycin SV used for cleaning the surgical wound prior to its closure. In case of repetitive surgery and/or in allergic patients the use of another antibiotic or the simple cleaning of the wound with normal saline should be considered. In case of surgery using a tourniquet, an iv access should be maintained for 1 hour after tourniquet release and the patient closely monitored in the recovery room. The allergologic assessment should take place 3 to 6 weeks later and include all drugs administered during the 10 minutes preceding the occurrence of shock.

Administration, Topical↗
PubMed1996

Selection and phenotypic characterization of nonhemagglutinating mutants of Porphyromonas gingivalis.

To further investigate the relationship between fimbriae and the hemagglutinating adhesin HA-Ag2 of Porphyromonas gingivalis, three spontaneous mutants of the type strain ATCC 33277 were selected by a hemadsorption procedure. They were characterized for hemagglutination, trypsin-like and lectin-binding activities, and hydrophobicity and for the presence of fimbriae. The presence of the 42-kDa (the fimbrilin subunit) and the 43- and 49-kDa (the HA-Ag2 components) polypeptides was investigated by immunoblotting using polyclonal and monoclonal antibodies directed to fimbriae and to the hemagglutinating adhesin HA-Ag2. Cells from two of the three mutants (M1 and M2) exhibited no or little hemagglutination activity and very low trypsin-like activity and did not show the 43- and 49-kDa polypeptides. Abnormal fimbriation in M1 was deduced from the following observations of cells grown for 18 h: absence of the 42-kDa polypeptide and of a 14-kDa polypeptide and no fimbriae visible on electron micrographs. While the cells of mutant M2, irrespective of the age of the culture, were found to lack the 43- and 49-kDa polypeptides and hemagglutination activity, the supernatants of cultures grown for 72 h had high hemagglutination and trypsin-like activities and revealed the presence of the 42-, 43-, and 49-kDa polypeptides. This suggests that M2 may be missing some molecules which anchor the components to the cell surface. Mutant M3 showed levels of activities similar to those of the parental strain but lacked the 43-kDa polypeptide. Other pleiotropic effects observed for the mutants included loss of dark pigmentation and lower hydrophobicity. The data from this study fuel an emerging consensus whereby fimbriation, hemagglutination, and proteolytic activities, as well as other functions in P. gingivalis, are intricate.

Adhesins, Bacterial↗
PubMed1995

Antigenic, structural, and functional relationships between fimbriae and the hemagglutinating adhesin HA-Ag2 of Porphyromonas gingivalis.

While the adhesive properties of Porphyromonas gingivalis are known to allow colonization of the subgingival tissues, the roles of fimbriae and adhesin molecules in hemagglutination remain unclear. The purpose of this study was to analyze the antigenic, structural, and functional relationships of these two components. Five populations of monoclonal antibodies were produced against (i) the hemagglutinating adhesin HA-Ag2 resolved by crossed immunoelectrophoresis (CIE), (ii) native fimbriae, and (iii) each of the three immunoprecipitates, Ag8a, Ag8b, and Ag8c, that define fimbriae by CIE. The tests used for characterization of the monoclonal antibodies included immunoblot reactivity, inhibition of hemagglutination, capacity to dissociate immunoprecipitates by CIE, localization of recognized epitopes by immunoelectron microscopy, and epitope mapping by competition enzyme-linked immunosorbent assay. The results from the different immunochemical tests clearly showed a close antigenic relationship between fimbriae and the hemagglutinating adhesin HA-Ag2. We were able to establish that the epitopic domain H1 of HA-Ag2 is hemagglutinin specific and that domain F2 is fimbria specific. Our data indicate that the polymeric structural unit of fimbriae must be complexed to HA-Ag2, the adhesin, to confer hemagglutination activity to the bacterial cells.

Animals↗
PubMed1995

Clonal diversity of the taxon Porphyromonas gingivalis assessed by random amplified polymorphic DNA fingerprinting.

A total of 97 strains of the periopathogen Porphyromonas gingivalis were collected. This collection included laboratory strains and clinical isolates of human origin with diverse clinical and geographical origins. Biological diversity was further increased by including 32 strains isolated from the oral cavities of nine different animal species. Genomic fingerprints of the 129 strains were generated as random amplified polymorphic DNAs (RAPDs) by the technique of PCR amplification with a single primer of arbitrary sequence. Four nonameric oligonucleotides were used as single primers, and the banding patterns of the DNA products separated on agarose gels were compared after ethidium ethidium bromide staining. Distance coeffients based on the positions of the major DNA fragments were calculated, and dendrograms were generated. We identified 102 clonal types (CTs) that could be assembled into three main groups by cluster analysis by the unweighted pair group method with mathematic averages. Group I (n = 79 CTs) included all 97 human strains and 6 monkey isolates. The strains in group II (n = 22 CTs) and III (n = 1 CT) were strongly differentiated from those in group I and included only strains of animal origin; they likely represent two cryptic species within the present P. gingivalis taxon. We observed that strains from Old World monkeys clustered together with the human genotype, whereas strains from New World monkeys clustered with the animal genotype. Our results with human strains also indicated that (i) the population structure is basically clonal, (ii) no dominant or widespread CT could be observed, and (iii) no relationship could be established between specific clusters of CTs and the periodontal status of the host. Our results corroborate previous findings by B. G. Loos, D. W. Dyer, T. S. Whittam, and R. K. Selander (Infect. Immun. 61:204-212, 1993) and suggest that P. gingivalis should be considered a commensal of the oral cavity acting as an opportunistic pathogen. Our results are not consistent with the hypothesis that only a few virulent clones of P. gingivalis are associated with disease.

Animals↗
PubMed1995

Immunomagnetic PCR and DNA probe for detection and identification of Porphyromonas gingivalis.

The aim of the study that we describe was to combine an immunomagnetic separation and a PCR followed by dot blot hybridization with a DNA probe for the detection and identification of Porphyromonas gingivalis. Immunomagnetic particles were coated with monoclonal antibody specific for P. gingivalis and were incubated with a suspension containing seven oral bacterial species spiked with various dilutions of P. gingivalis. Beads with their load of bound bacterial were boiled in water, and the target DNA in the supernatant was amplified with a primer pair to generate a 593-bp PCR fragment specific for P. gingivalis. Finally, the product of amplification was detected by dot blot hybridization with a digoxigenin-labeled 593-bp probe. The detection limit was determined to be 100 bacterial cells per ml. The immunomagnetic-PCR/DNA probe procedure described here should be useful for the rapid, specific, and sensitive detection and identification of P. gingivalis in clinical samples.

Antibodies, Bacterial↗
PubMed1995

Isolation of Porphyromonas gingivalis strain from tubal-ovarian abscess.

An unusual case of involvement of Porphyromonas gingivalis is described. Two anaerobic isolates, identified as Fusobacterium nucleatum and P. gingivalis, were recovered from the pus of a tubal-ovarian abscess in a 35-year-old woman. Identification of the P. gingivalis isolate was confirmed by randomly amplified polymorphic DNA fingerprinting.

Abscess↗
PubMed1995

Serum antibodies to Porphyromonas gingivalis in children.

Serum samples from 41 periodontally healthy children aged 1 to 16 years were examined by ELISA for the presence of antibodies against a glass bead-EDTA cell surface extract (GBE) and LPS of Porphyromonas gingivalis strain ATCC 33277. P. gingivalis was detected by immunofluorescence, using a species-specific monoclonal antibody, in 41% (17/41) of the children, and isolated from a single subject (2.4%). IgM, IgG, and IgA against GBE were detected in respectively 39/41 (95%), 41/41 (100%), and 27/41 (66%) of the sera. In 22/39 sera, the IgG titer was below 50% that of a reference pool of adult sera (RP). In 13/41, the IgM titer was higher than that of the RP, mostly in the deciduous dentition group. Detectable IgA titers were always below 67% that of the RP. A polarized distribution of the children appeared, separating 21 non- and low IgA responders (IgA titer below 10% that of the RP) from the remaining 20 subjects. Anti-LPS IgG, IgM, and IgA were detected in 41/41 (100%), 39/41 (95%), and 23/38 (61%) respectively of the children. In 32/41 sera, the anti-LPS IgG titer was below 50% that of the RP, while in 20/39 sera, IgM titers were higher. A clearcut dichotomy in IgA response was observed, allowing us to distinguish non-IgA responders (39%) and IgA responders to LPS (61%). Our results indicate that serum antibodies to P. gingivalis are highly prevalent in children, suggesting that an active primary immune response and a secondary immune response are well underway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

[A study of the use of simulation in clinical instruction at the Ann Latsky Nursing College].

Simulation gives the student the opportunity for creativity while experimenting under simulated circumstances. Simulation provides an area where complex objectives can be achieved and potentially dangerous procedures can be practised in a risk-free area. Students can also repeat aspects of a complicated procedure until they reach the required competency level and gain the necessary self confidence of function in the work situation. Where learning experiences are lacking in the practical area, simulation could be used. An effective simulation facility should present the practical situation of the ward.

Clinical Competence↗
PubMed1994

Polymerase chain reaction using arbitrary primer for the design and construction of a DNA probe specific for Porphyromonas gingivalis.

In this work, we used a novel approach for the design and construction of DNA probes which requires no knowledge of target DNA sequence. We demonstrated that species-specific genetic markers, identified as such among monomorphic, randomly amplified DNA segments generated by the polymerase chain reaction with arbitrary primer can be labelled to yield so-called "anonymous probes". We report here on the construction of such an anonymous probe, 1146 bp long, specific for the Gram-negative anaerobe Porphyromonas gingivalis, a suspected major etiologic agent of chronic periodontitis in adults.

Animals↗