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Biomedical subjects

D Dubreuil

Publications and source records attributed to D Dubreuil.

34 records · Page 2Linked to original sources
PubMed1991

Detection and characterization of leptospiral antigens using a biotin/avidin double-antibody sandwich enzyme-linked immunosorbent assay and immunoblot.

A biotin/avidin double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of antigens of Leptospira interrogans serovars in experimentally inoculated bovine urine samples was evaluated. Immunoglobulin G (IgG) from rabbits immunized with L. interrogans serovar hardjo type hardjobovis sonicated, whole cell, and formalinized-heated antigen preparations were purified by a protein A-superose column coupled to fast protein liquid chromatography, and evaluated for species specificity in the ELISA. The ELISA using each specific IgG detected as few as 10(4) leptospires of the homologous serovar hardjo diluted in phosphate-buffered saline solution with Tween 20 (PBSS-Tween 20). On immunoblot analysis of proteinase-K-digested whole cell leptospiral preparations, each IgG revealed the presence of bands specific to serovar hardjo, suggesting the presence of serovar-specific epitopes on the lipopolysaccharide molecules. The minimum number of cells of heterologous serovars pomona, grippotyphosa, bratislava, icterohaemorrhagiae and copenhageni detected by each ELISA was greater, ranging from 10(6) to 10(7). The common antigenic determinants observed on immunoblot analysis were different for each specific IgG, except for a major cross-reacting, possibly flagellar, protein doublet at approximately 36-36.5 kDa. Leptospires were equally well detected by the ELISA in both bovine urine and PBSS-Tween 20.

Animals↗
PubMed1991

Determination of affinity of Pasteurella multocida isolates for porcine respiratory tract mucus, and partial characterization of the receptors.

The ability of 25 Pasteurella multocida isolates to adhere in vitro to porcine respiratory tract mucus was examined. Microplate wells were coated with crude mucus preparation, then bacteria were added. After incubation, unbound bacteria were removed by washing, and the number of mucus-bound bacteria was estimated by quantitation of the adherent colony-forming units and by use of an ELISA. Pasteurella multocida had affinity to respiratory tract mucus, although significant differences were not observed in affinity of capsular type-A and type-D isolates. Preliminary characterization, using ultrafiltration, gel filtration chromatography, electrophoresis, and enzymatic treatments, indicated that the receptors may be a class of protein molecules of low molecular weight (less than 25,000). The origin of these receptors, however, is not known at this time.

Animals↗
PubMed1990

Immunoelectron microscopic demonstration that Renibacterium salmoninarum is encapsulated.

The cell surfaces of four strains of Renibacterium salmoninarum, including the type strain Lea-7-74T, were examined by transmission electron microscopy after immuno-stabilization and staining with ruthenium red. Cells were covered with a layer of capsular material whose thickness varied between 30 to 60 nm. Our results indicate that R. salmoninarum is encapsulated.

Animals↗
PubMed1990

Role of lipopolysaccharides in adherence of Actinobacillus pleuropneumoniae to porcine tracheal rings.

The ability of 17 Actinobacillus pleuropneumoniae isolates, representing serotypes 1, 2, 5, and 7, to adhere to tracheal rings maintained in culture was examined. Porcine tracheal rings were infected, and 8 h after inoculation, adherent bacterial cells were evaluated. A. pleuropneumoniae adhered to tracheal rings, and marked variations were observed between and even within serotypes, suggesting that adherence of this microorganism is not primarily related to the serotype of the isolate. No relationship was found between adherence to porcine tracheal rings and plasmid profiles, virulence in mice, hemagglutination, capsular material thickness, or whole-cell protein profiles. On the other hand, we observed that all isolates of serotypes 1 and 5 had a semirough-type lipopolysaccharide (LPS), whereas isolates of serotypes 2 and 7 had a smooth-type LPS (75%) or a semirough-type LPS (25%). Results showed that 83% of isolates with a smooth-type LPS adhered in large numbers to tracheal rings, whereas 80% of isolates with a semirough-type LPS adhered poorly (P less than 0.007). Our data indicated that the degree of adherence of A. pleuropneumoniae to porcine tracheal rings appeared to be related, at least in part, to LPS profiles. Furthermore, LPS seemed to be the adhesin of A. pleuropneumoniae, since purified LPS blocked adherence of this microorganism to porcine tracheal rings.

Actinobacillus↗
PubMed1990

Production and partial purification of a gonococcal growth inhibitor produced by a strain of Neisseria meningitidis isolated from a homosexual man.

A Neisseria meningitidis strain isolated from the oropharynx of a homosexual man was shown to produce antigonococcal activity in vitro. A production method, on solid medium, was developed which yielded a soluble activity. The activity was detected at the end of logarithmic growth phase and the maximum activity was reached after 24 h of incubation. The antigonococcal substance was purified more than 300 times by ammonium sulphate precipitation, gel filtration on Ultrogel AcA 54, and chromatography on DEAE-Sephacel. The molecular weight of the inhibitory substance, estimated by molecular filtration, was 29 X 10(3) daltons. The partially purified inhibitor showed two major bands, 32 and less than 12.5 X 10(3) daltons by sodium dodecyl-sulphate polyacrylamide electrophoresis. The chemical nature of the inhibitor is probably proteic on the basis of trypsin sensitivity and the absorbance spectrum.

Antibiosis↗
PubMed1985

In vitro inhibition of Neisseria gonorrhoeae growth by a urogenital strain of Streptococcus faecalis.

A strain of Streptococcus faecalis isolated from the urogenital flora was selected for its ability to inhibit the in vitro growth of Neisseria gonorrhoeae. Initially, the inhibitory activity was demonstrated on solid medium only when the inhibitor and the target strains were growing simultaneously, such as in the spot-lawn and flip-flop agar overlay methods. The antigonococcal effect was not due to a shift in the pH or depletion of nutrient in the medium. This activity was not produced in liquid medium nor could it be extracted in a soluble form from either the solid medium or the streptococcal cells. The production of the inhibitory activity could not be enhanced by ultraviolet irradiation or treatment with mitomycin C. The composition of the medium was found to affect the size of the inhibitory zone produced. The inhibitory activity showed a wide antigonococcal spectrum and was susceptible to trypsin and pronase but resistant to alpha- and beta-amylases and catalase. This activity passed through a filtering membrane and was also dialyzable and had an apparent molecular weight of less than 1,000. The addition of bovine serum albumin to solid medium enabled us to show an inhibition even when the producer and the target strains were grown sequentially, thus suggesting that part of the difficulty of studying such inhibitory activity could be due to its instability.

Anti-Bacterial Agents↗
PubMed1984

Inhibition of Neisseria gonorrhoeae growth due to hydrogen peroxide production by urogenital streptococci.

Seven streptococci isolated from the normal urogenital flora were selected for the production of an inhibitory activity toward Neisseria gonorrhoeae on solid medium. This activity was abolished when catalase was added to the medium in the case of Streptococcus mitis isolates 22, 25, 74 and Streptococcus sanguis II isolate 70 suggesting the involvement of hydrogen peroxide. The inhibitory activities produced by the other isolates (Streptococcus faecalis) were trypsin sensitive (isolates 12 and 14) or stable (isolate 59). Hydrogen peroxide production by S. sanguis II was quantitatively evaluated by reference to a standard curve representing the inhibitory effect of various concentrations of commercial H2O2 on N. gonorrhoeae growth. After 22 h of incubation a yield of 5.3 m mol H2O2 I-1 was reached on solid medium while in liquid medium values of 2.8 and 7.3 m mol H2O2 I-1 were obtained, respectively, in non-agitated and agitated cultures after 8 h of incubation.

Humans↗
PubMed1982

In vitro adhesion of Staphylococcus strains to rabbit tissues.

Differences in the in vitro adhesion of Staphylococcus strains on rabbit tissues were evaluated by viable unit counts and radio-labeling. Among coagulase-positive strains, two freshly isolated strains and the Cowan I strain adhered much more than the Wood 46 strain especially to peritoneum. In addition, the Smith strain, which is coagulase-positive and encapsulated, showed on rabbit peritoneum a degree of adhesion smaller than that of the Cowan I strain and similar to that of the Wood 46 strain. These quantitative results were corroborated by examination of the bacteria on thin sections of peritoneum or on whole mesentery samples with fluorescence microscopy. With fluorochroming either with acridine orange or fluorescent homologous antibodies, we could detect a preferential localization of the bacteria on the epithelium and also on fibers of the mesentery. Even if the Cowan I strain produces Protein A, this substance does not seem to have been involved in the adhesion of this strain to rabbit tissues, since IgG did not affect the degree of its adhesion. Treatment by Na metaperiodate of the peritoneum had an inhibitory effect of about 50% on the degree of adhesion; several other known inhibitors had no effect. The higher affinity of the Cowan I strain for the peritoneum or the mesentery, when compared with the Wood 46 strain, is an observation which could contribute to the study and understanding of adhesion, presumably an element of the experimental pathogenicity of Staphylococcus.

Animals↗
PubMed1977

[The morphologic relation between the temporomandibular joint and other components of the masticatory apparatus in catarrhine simians and humans].

The articular temporo-mandibular structures and their osseous and dental environment were studied in some catarhinians Simians (Cynomorphs and Anthropomorphs) and some representatives of the human lineage. The study of measurable and descriptive characters showed a relative stability of the temporo-mandibular joint compared to the dynamism of the other components of the masticatory system. The functional specificity of the actual human temporo-mandibular joint seemed to be tightly associated to the main processes leading toward human evolution (facial regression, increase of the cranial capacity). On the other hand, this study casts some doubts regarding the utilization of Primates for experiments in this field.

Animals↗
PubMed1976

[Acquisition of masticatory structures in mammalian reptiles (preliminary study].

Possession of the masticatory function and apparatus appears as essential for the passage from Reptiles to Mammals. The present study, based on material of the Museum of d'Histoire Naturelle of Paris and on the literature, tries to distinguish the different stages of modification and specialization of feeding device in the cynodont theriodonts, leading to the mammalian stomatognathic system. The relationship between bone components (lateral skull and lower jaw), teeth and muscles are discussed. Induction of these changes comes from the external adductor muscular system in which the transformation from a primitive mass to mammalianlike masticatory muscles, directs this evolution. The conditions of feeding specialization of the Gomphodonts are discussed, as well as their evolutionary failure. Lastly, without taking up the quarrel about the double jaw-joint, it seems for the authors that the jaw-joint transformation appears as the most determinative element for assigning mammalian origins to the Cynodonts.

Animals↗
PubMedDate not supplied

Synthesis of thiaazaheterocycle nucleoside analogues.

The syntheses of thiazinone, thiazinedione and thiazolinone base modified nucleoside analogues have been discussed in both the deoxy- and ribosyl series. Both inter- and intramolecular N-glycosylations were evaluated.

Glycosylation↗
PubMedDate not supplied

In vitro inhibition of growth of Neisseria gonorrhoeae by Neisseria meningitidis isolated from the pharynx of homosexual men.

Despite the high prevalence of pharyngeal gonorrhea and of meningococcal carriage among homosexual men, Neisseria gonorrhoeae and Neisseria meningitidis are rarely co-isolated from the throat. Forty-seven meningococcal isolates from the pharynx of homosexual men were examined, by a lawn-spotting method, for their ability to inhibit N. gonorrhoeae in vitro. Eight (17%) of the meningococcal isolates were inhibitory when tested against gonococci from the same patient, while 31 (66%) were inhibitory when tested against N. gonorrhoeae strain 650 (T1). The colonial type T1 of a given strain was, in all cases tested, more sensitive to the inhibitory activities than the corresponding T4 type. Since the meningococci co-isolated from the throat with gonococci were at least as inhibitory in vitro as those isolated without gonococci, the natural resistance to gonococcal pharyngitis cannot be explained on the basis of the inhibitory activities produced by the meningococci in vitro. The inhibitory strains of N. meningitidis were identified in decreasing importance as: nonserogroupable, W135, C, B, 29E, and X. The addition of trypsin to the solid medium removed the inhibition produced by the meningococci, an observation suggesting the involvement of protein inhibitors.

Animals↗