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K Bernard

Publications and source records attributed to K Bernard.

At least 37 records · Page 2Linked to original sources
PubMed1996

Multiplex messenger assay: simultaneous, quantitative measurement of expression of many genes in the context of T cell activation.

The hybridization signature approach, using colony filters and labeled complex probes, can provide high throughput measurement of gene activity. We describe here the implementation of this method to follow the expression levels of 47 genes in resting and activated T cells, as well as in epithelial cells. Using 4-fold spotting of colonies, imaging plate detection and various correction and normalization procedures, the technique is sensitive enough to quantify expression levels for sequences present at 0.005% abundance in the probe. Comparison with Northern blotting shows good consistency between the two methods. Upon activation of a T cell clone by an anti-CD3 antibody variations ranging from 2- to 20-fold are measured, some of which had not been reported previously. This 'multiplex messenger assay' method, performed using available commercial apparatus, can be used in many cases where simultaneous assessment of mRNA levels for many genes is of interest.

Animals↗
PubMed1996

Antimicrobial susceptibility pattern of Corynebacterium striatum.

The in vitro activities of 16 antimicrobial agents against 86 strains of Corynebacterium striatum were evaluated by microdilution using cation-adjusted Mueller-Hinton broth. MICs at which 90% of strains were inhibited were 0.06 microgram/ml for teicoplanin, 1 microgram/ml for vancomycin, 0.03 to 8 micrograms/ml for beta-lactams, 8 micrograms/ml for sparfloxacin, 16 micrograms/ml for ciprofloxacin, 16/304 micrograms/ml for co-trimoxazole (trimethoprim-sulfamethoxazole), 64 micrograms/ml for tetracycline, 128 micrograms/ml for gentamicin, and > 128 micrograms/ml for amikacin, erythromycin, and rifampin.

Anti-Bacterial Agents↗
PubMed1996

Isolation and characterization of a new bacterium carboxylating phenol to benzoic acid under anaerobic conditions.

A consortium of spore-forming bacteria transforming phenol to benzoic acid under anaerobic conditions was treated with antibiotics to eliminate the four Clostridium strains which were shown to be unable to accomplish this reaction in pure culture and coculture. Clostridium ghonii was inhibited by chloramphenicol (10 micrograms/ml), whereas Clostridium hastiforme (strain 3) and Clostridium glycolicum were inhibited by clindamycin (20 micrograms/ml), without the transformation of phenol being affected. Electron microscopic observations of resulting liquid subcultures revealed the presence of two different bacilli: a dominant C hastiforme strain (strain 2) (width, 1 micron) and an unidentified strain 6 (width, 0.6 micron) which was not detected on solid medium. Bacitracin (0.5 U/ml) changed the ratio of the strains in favor of strain 6. C hastiforme 2 was eliminated from this culture by dilution. The isolated strain 6 transformed phenol to benzoic acid and 4-hydroxybenzoic acid to phenol and benzoic acid in the presence of proteose peptone. Both of these activities are inducible. This strain is a gram- variable, flagellated rod with a doubling time of 10 to 11 h in the presence of phenol. It has a cellular fatty acid composition like that of C. hastiforme. However, strain 6 does not hydrolyze gelatin or produce indole. The 16S rRNA sequence of strain 6 was found to be most similar to that of some Clostridium species, with homology ranging from 80 to 86%. Tbe evolutionary relationships of strain 6 to different groups of Clostridium and Clostridium-related species revealed that it does not emerge from any of these groups. Strain 6 most likely belongs to a new species closely related to Clostridium species.

Anaerobiosis↗
PubMed1995

Differential gene expression in the murine thymus assayed by quantitative hybridization of arrayed cDNA clones.

High-throughput measurement of hybridization signatures obtained using complex probes prepared from poly(A)+ RNA and high-density cDNA colony filters is described. The performance of the system, elimination of artifacts, and verification of the validity of the data are discussed. cDNAs corresponding to sequences present at levels of approximately 0.01% in the complex probe can be detected. Good correlation is observed between expression profiles determined by this method and by Northern blotting. The method is applied to a preliminary investigation of differential expression in three cell types present in the murine thymus.

Animals↗
PubMed1995

An analysis of co-circulating serotypes for bluetongue-17 virulence markers.

We have recently identified two markers associated with virulent strains of bluetongue virus serotype 17. These differences are an altered antigenic structure of the outer capsid protein VP2 and an increased electrophoretic mobility of the RNA segment 3 that codes for an inner core protein. We did not observe these markers in confirmed avirulent strains of bluetongue virus serotype 17. We hypothesized that these virulence-associated markers may have been acquired by bluetongue-17 through genetic interaction with other circulating serotypes of the virus. To test this hypothesis, we studied all isolates of other BLU serotypes obtained from the same sentinel cattle herds in Central America and the Caribbean on the same days as BLU-17 isolates. We looked for evidence of common epitopes on VP2 or an RNA segment 3 of identical mobility to that of the virulent strains of BLU-17. We found no evidence to indicate that genetic interaction with other co-circulating serotypes gave rise to these two specific virulence-associated markers of BLU-17.

Animals↗
PubMed1995

Further Evidence that the N(inf2)-Fixing Endophytic Bacterium from the Intercellular Spaces of Sugarcane Stems Is Acetobacter diazotrophicus.

Nitrogen-fixing bacteria, isolated from the sugar solution in intercellular spaces of sugarcane stems, were compared with the type strain of Acetobacter diazotrophicus (PAL-5) and found to be congruent with it in all characters studied. These characters were 37 morphological and biochemical tests, cellular fatty acid composition, and nitrogenase activity. The nitrogenase activity was measured by acetylene reduction and H(inf2) evolution and found to be unusual in that the H(inf2) evolution was suppressed much less than expected by high concentrations of acetylene.

Journal Article↗
PubMed1995

Phenotypic characteristics of 31 strains of Corynebacterium striatum isolated from clinical samples.

During a 34-month period (January 1991 to October 1993), 31 Corynebacterium striatum stains recovered from clinical samples from 24 patients were characterized. Twenty (64%) strains were isolated from wound exudates, 5 (16%) were isolated from bronchial aspirates, 2 (7%) were isolated from urine, 2 (7%) were isolated from endotracheal tubes, 1 (3%) was isolated from a catheter, and 1 (3%) was isolated from empyema. The organisms were identified by conventional culture and phenotypic characterization, the API CORYNE system, and cellular fatty acid composition analyses. The colonies of C. striatum could be confused with those of coagulase-negative staphylococci upon primary isolation from clinical material. A consistent phenotypic pattern was observed: all strains reduced nitrate, hydrolyzed tyrosine, and produced acid from glucose, fructose, and sucrose but not from maltose. API CORYNE profile numbers were 3100105 (28 strains) and 3000105 (3 strains). Susceptibility testing of C. striatum was performed by disk diffusion. All strains were susceptible to both imipenem and vancomycin and resistant to fosfomycin; most strains were susceptible to ampicillin and cephalosporins and resistant to clindamycin, erythromycin, and tetracycline. Performing a Gram stain of fosfomycin-resistant "Staphylococcus-like" colonies was critical in order to identify C. striatum.

Anti-Bacterial Agents↗
PubMed1994

Early recognition of atypical Francisella tularensis strains lacking a cysteine requirement.

Seven cultures referred to in our laboratories as unidentified gram-negative bacilli or Haemophilus species were identified as atypical strains of Francisella tularensis lacking a requirement for cysteine or enriched medium for growth. The use of cellular fatty acid composition analysis facilitated early recognition of this pathogen and prompt implementation of appropriate biosafety measures.

Containment of Biohazards↗
PubMed1994

Cellular fatty acid composition and phenotypic and cultural characterization of CDC fermentative coryneform groups 3 and 5.

Seventy strains of fermentative, asporogenous, gram-positive coccobacilli or short rods form two closely related groups which have been designated CDC fermentative coryneform groups 3 (32 strains, xylose fermenters) and 5 (38 strains, xylose nonfermenters). The two taxa are otherwise similar to each other phenotypically and culturally and by a distinctive Staphylococcus-like odor and by cellular fatty acid (CFA) composition. CDC group 3 and CDC group 5 strains have been isolated from clinical sources (blood, abscesses, and wounds but not urine or respiratory specimens) in Canada and the United States and among referrals from Belgium, Sweden, and Spain. Coryneform CDC group 3 strains were phenotypically similar to CDC coryneform group A-3 but were distinguishable by their inability to reduce nitrate and by their lack of motility. Coryneform CDC group 5 isolates were phenotypically somewhat similar to Actinomyces viscosus and Rothia dentocariosa, except that none of this group reduced nitrate. Both CDC groups could be differentiated from these similar bacteria by the ability to decarboxylate lysine and ornithine. The CFA compositions of CDC group 3 and 5 strains were similar to each other, were distinctive from those of other coryneforms, and were of the branched-chain type. API CORYNE codes were consistent for both CDC group 3 and CDC group 5 bacteria, suggesting that this method could be useful as an identification method.

Actinomycetales↗
PubMed1992

Fatal Legionella maceachernii pneumonia in Canada.

A case of pneumonia and acute tubular necrosis was caused by an initially unknown species of Legionella. The organism was later identified as Legionella maceachernii by a combination of cultural, biochemical, and serological methods along with a gas-liquid chromatographic profile.

Canada↗
PubMed1991

Use of chemotaxonomy as an aid to differentiate among Capnocytophaga species, CDC group DF-3, and aerotolerant strains of Leptotrichia buccalis.

Four strains of fastidious gram-negative rods, thought to be Capnocytophaga species (formerly CDC group DF-1 or Bacteroides ochraceus) or CDC group DF-3 on the basis of conventional phenotypic criteria, were also analyzed for cellular fatty acid (CFA) composition. It was found that the CFA compositions of these strains were qualitatively incorrect for those taxa. Subsequently, it was determined that all four bacteria were in fact aerotolerant strains of Leptotrichia buccalis, based on biochemical reactions, CFA composition, and lactic acid as the major end product of glucose fermentation. It is recommended that, in addition to conventional cultural and biochemical criteria, all strains of Capnocytophaga or CDC group DF-3 should also be tested for metabolic end products of fermentation and CFA composition as essential adjuncts for identification.

Bacteroidaceae↗
PubMed1987

False positivity of Legionella serology in patients with cystic fibrosis.

Respiratory deterioration accounts for the morbidity and mortality observed in patients with cystic fibrosis. The role of Legionella in this deterioration was determined in a 2-year prospective study of 49 patients with cystic fibrosis and 19 sibling controls. Sera were obtained from participants on enrollment and at quarterly intervals. Legionella antibodies were measured in parallel using an indirect fluorescent assay. No seroconversions were observed. Eleven of 49 patients with cystic fibrosis (22%) were seropositive compared to none of 19 siblings (P less than 0.05). Six of the 11 patients demonstrated high titers (greater than or equal to 1:512) that persisted throughout the study. Absorption with pools of various Pseudomonas species reduced the antibody titers such that only 3 remained positive after absorption. Legionella was not found to be an important cause of clinical deterioration during this study. The results of the absorption studies suggest that high titers to Legionella in this population are due to cross-reacting antibodies.

Antibodies, Bacterial↗