bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion of Type 1-Fimbriated
Escherichia coli
to Abiotic Surfaces Leads to Altered Composition of Outer Membrane Proteins
Authors: Otto Karen , Norbeck Joakim , Larsson Thomas , Karlsson Karl-Anders , Hermansson Malte 
Published: July 2002

ABSTRACT

Phenotypic differences between planktonic bacteria and those attached to abiotic surfaces exist, but the mechanisms involved in the adhesion response of bacteria are not well understood. By the use of two-dimensional (2D) polyacrylamide gel electrophoresis, we have demonstrated that attachment of
Escherichia coli
to abiotic surfaces leads to alteration in the composition of outer membrane proteins. A major decrease in the abundance of resolved proteins was observed during adhesion of type 1-fimbriated
E. coli
strains, which was at least partly caused by proteolysis. Moreover, a study of fimbriated and nonfimbriated mutants revealed that these changes were due mainly to type 1 fimbria-mediated surface contact and that only a few changes occurred in the outer membranes of nonfimbriated mutant strains. Protein synthesis and proteolytic degradation were involved to different extents in adhesion of fimbriated and nonfimbriated cells. While protein synthesis appeared to affect adhesion of only the nonfimbriated strain, proteolytic activity mostly seemed to contribute to adhesion of the fimbriated strain. Using matrix-assisted laser desorption ionization–time of flight mass spectrometry, six of the proteins resolved by 2D analysis were identified as BtuB, EF-Tu, OmpA, OmpX, Slp, and TolC. While the first two proteins were unaffected by adhesion, the levels of the last four were moderately to strongly reduced. Based on the present results, it may be suggested that physical interactions between type 1 fimbriae and the surface are part of a surface-sensing mechanism in which protein turnover may contribute to the observed change in composition of outer membrane proteins. This change alters the surface characteristics of the cell envelope and may thus influence adhesion.
Regulatory RNA as Mediator in GacA/RsmA-Dependent Global Control of Exoproduct Formation inPseudomonas fluorescensCHA0
Authors: Heeb Stephan , Blumer Caroline , Haas Dieter 
Published: July 2002

ABSTRACTInPseudomonas fluorescensCHA0, an antagonist of root-pathogenic fungi, the GacS/GacA two-component system tightly controls the expression of antifungal secondary metabolites and exoenzymes at a posttranscriptional level, involving the RNA-binding protein and global regulator of secondary metabolism RsmA. This protein was purified fromP. fluorescens, and RNA bound to it was converted to cDNA, which served as a probe to isolate the corresponding chromosomal locus,rsmZ. This gene encoded a regulatory RNA of 127 nucleotides and a truncated form lacking 35 nucleotides at the 3" end. Expression ofrsmZdepended on GacA, increased with increasing population density, and was stimulated by the addition of a solvent-extractable extracellular signal produced by strain CHA0 at the end of exponential growth. This signal appeared to be unrelated toN-acyl-homoserine lactones. A conserved upstream element in thersmZpromoter, but not the stress sigma factor RpoS, was involved inrsmZexpression. Overexpression ofrsmZeffectively suppressed the negative effect ofgacSandgacAmutations on target genes, i.e.,hcnA(for hydrogen cyanide synthase) andaprA(for the major exoprotease). Mutational inactivation ofrsmZresulted in reduced expression of these target genes in the presence of added signal. Overexpression ofrsmAhad a similar, albeit stronger negative effect. These results support a model in which GacA upregulates the expression of regulatory RNAs, such as RsmZ of strain CHA0, in response to a bacterial signal. By a titration effect, RsmZ may then alleviate the repressing activity of RsmA on the expression of target mRNAs.
Filamentous Phage Active on the Gram-Positive BacteriumPropionibacterium freudenreichii
Authors: Chopin Marie-Christine , Rouault Annette , Ehrlich S. Dusko , Gautier Michel 
Published: July 2002

ABSTRACTWe present the first description of a single-stranded DNA filamentous phage able to replicate in a gram-positive bacterium. Phage B5 infectsPropionibacterium freudenreichiiand has a genome consisting of 5,806 bases coding for 10 putative open reading frames. The organization of the genome is very similar to the organization of the genomes of filamentous phages active on gram-negative bacteria. The putative coat protein exhibits homology with the coat proteins of phages PH75 and Pf3 active onThermus thermophilusandPseudomonas aeruginosa, respectively. B5 is, therefore, evolutionarily related to the filamentous phages active on gram-negative bacteria.
Measles Virus-Specific Immunoglobulin G Isotype Immune Response in Early and Late Infections
Authors: Isa Marı́a Beatrı́z , Martı́nez Laura , Giordano Miguel , Zapata Marta , Passeggi Carlos , De Wolff Marı́a Cristina , Nates Silvia 
Published: July 2002

ABSTRACT

A total of 154 human serum samples (32 acute-phase and 22 convalescent-phase serum samples obtained within a week and between days 8 and 26 after the onset of rash, respectively, and 100 samples drawn from healthy immune adults) were processed by an immunofluorescence assay for the detection of immunoglobulin M (IgM), total immunoglobulin G (IgG), IgG1, IgG2, IgG3, and IgG4 measles virus-specific antibodies. In the acute phase, IgG1 was seen first, followed by IgG2, IgG3, and IgG4 responses, the mean seropositivity of which gradually increased during convalescence, reaching 100% (standard deviation [SD], 84 to 100%), 57% (SD, 34 to 80%), 86% (SD, 66 to 100%), and 86% (SD, 66 to 100%), respectively. IgG2 rose and fell in connection with IgG3 subclass antibodies, showing a rate of detection of IgG2 and/or IgG3 subclass antibodies of 95.5% (range, 100 to 86.5%) in the convalescent phase of infection. The mean percentage of measles IgG2 and IgG3 seropositivity dropped significantly during the memory phase, to 2% (range, 2 to 6%) and 3% (range, 3 to 7%), respectively (
P
< 0.05); meanwhile IgG1 and IgG4 subclass responses remained relatively unmodified in samples obtained years after infection (mean 100% [SD, 96 to 100%] and 86% [SD, 79 to 93%], respectively). Results obtained defined two highly different immune isotypic response patterns. One pattern is restrictive to IgG2 and/or IgG3 in the convalescent phase and is kinetically similar to the IgM antibody response, so its detection could be referred to as a recent viral activity. On the other hand, IgG1 and IgG4 were detected in both the convalescent and memory phases of the immune response, but their isolated occurrence without IgG2 and IgG3 could be related to the long-lasting immunity.
Characterization of
Salmonella
Associated with Pig Ear Dog Treats in Canada
Authors: Clark Clifford , Cunningham Jane , Ahmed Rafiq , Woodward David , Fonseca Kevin , Isaacs Sandy , Ellis Andrea , Anand Chandar , Ziebell Kim , Muckle Anne , Sockett Paul , Rodgers Frank 
Published: July 2002

ABSTRACT

In the summer of 1999, the incidence of
Salmonella enterica
serotype Infantis infections in Alberta rose dramatically. Subsequent laboratory and epidemiological investigations established that an outbreak of human disease caused by this organism was occurring across Canada and was associated with pet treats for dogs produced from processed pig ears. Laboratory investigations using phage typing and pulsed-field gel electrophoresis (PFGE) established that isolates of
Salmonella
serotype Infantis from pig ear pet treats and humans exposed to pig ear pet treats comprised a well-defined subset of all isolates analyzed. Of the 53 subtypes of
Salmonella
serotype Infantis obtained around the time of the outbreak as defined by PFGE and phage typing, only 6 subtypes were associated with both human infection and isolation from pig ears. Together with information from epidemiological studies, these investigations established pig ear pet treats as the cause of the
Salmonella
serotype Infantis outbreak. The results are consistent with a model in which contaminated pig ear pet treats constitute a long-term, continuing vehicle for infection of the human population rather than causing temporally delimited point-source outbreaks. During the course of this outbreak, several other
Salmonella
serotypes were also isolated from pet treats, suggesting these products may be an important source of enteric infection in both humans and dogs. Though isolates of
Salmonella
serotypes other than
Salmonella
serotype Infantis from pet treats were also subjected to PFGE and phage typing, no link with human disease could be definitively established, and the contribution of pig ear pet treats to human disease remains unclear. Elimination of bacterial contamination from pet treats is required to reduce the risk of infection from these products.
Polymorphic Internal Transcribed Spacer Region 1 DNA Sequences Identify Medically Important Yeasts
Authors: Chen Yi-Ching , Eisner Jessica D. , Kattar Mireille M. , Rassoulian-Barrett Sara L. , Lafe Karen , Bui Uyen , Limaye Ajit P. , Cookson Brad T. 
Published: July 2002

ABSTRACT
Species-specific polymorphisms in the noncoding internal transcribed spacer 2 (ITS2) region of the rRNA operon provide accurate identification of clinically significant yeasts. In this study, we tested the hypothesis that ITS1 noncoding regions contain diagnostically useful alleles. The length of ITS1 region PCR products amplified from 40 species (106 clinical strains, 5 reference strains, and 30 type strains) was rapidly determined with single-base precision by automated capillary electrophoresis. Polymorphisms in the PCR product length permitted 19 species to be distinguished by ITS1 alone, compared with 16 species distinguished by using only ITS2. However, combination of both ITS alleles permitted identification of 30 species (98% of clinical isolates). The remaining 10 species with PCR products of similar sizes contained unique ITS alleles distinguishable by restriction enzyme analysis. DNA sequence analysis of amplified ITS1 region DNA from 79 isolates revealed species-specific ITS1 alleles for each of the 40 pathogenic species examined. This provided identification of unusual clinical isolates, and 53 diagnostic ITS1 sequences were deposited in GenBank. Phylogenetic analyses based on ITS sequences showed a similar overall topology to 26S rRNA gene-based trees. However, different species with identical 26S sequences contained distinct ITS alleles that provided species identification with strong statistical support. Together, these data indicate that the analysis of ITS polymorphisms can reliably identify 40 species of clinically significant yeasts and that the capacity for identifying potentially new pathogenic species by using this database holds significant promise.
Differentiation of
Candida albicans
and
Candida dubliniensis
by Fluorescent In Situ Hybridization with Peptide Nucleic Acid Probes
Authors: Oliveira Kenneth , Haase Gerhard , Kurtzman Cletus , Hyldig-Nielsen Jens Jo/rgen , Stender Henrik 
Published: July 2002

ABSTRACT

The recent discovery of
Candida dubliniensis
as a separate species that traditionally has been identified as
Candida albicans
has led to the development of a variety of biochemical and molecular methods for the differentiation of these two pathogenic yeasts. rRNA sequences are well-established phylogenetic markers, and probes targeting species-specific rRNA sequences have been used in diagnostic assays for the detection and identification of microorganisms. Peptide nucleic acid (PNA) is a DNA mimic with improved hybridization characteristics, and the neutral backbone of PNA probes offers significant advantages in whole-cell in situ hybridization assays. In this study, we developed PNA probes targeting the rRNAs of
C. albicans
and
C. dubliniensis
and applied them to a fluorescence in situ hybridization method (PNA FISH) for differentiation between
C. albicans
and
C. dubliniensis
. Liquid cultures were smeared onto microscope slides, heat fixed, and then hybridized for 30 min. Unhybridized PNA probe was removed by washing, and smears were examined by fluorescence microscopy. Evaluation of the PNA FISH method using smears of 79
C. dubliniensis
and 70
C. albicans
strains showed 100% sensitivity and 100% specificity for both PNA probes. We concluded that PNA FISH is a powerful tool for the differentiation of
C. albicans
and
C. dubliniensis
.
Influence of Glucose Supplementation and Inoculum Size on Growth Kinetics and Antifungal Susceptibility Testing of
Candida
spp
Authors: Cuenca-Estrella Manuel , Dı́az-Guerra Teresa M. , Mellado Emilia , Rodrı́guez-Tudela Juan L. 
Published: July 2002

ABSTRACT

The influences of inoculum size and glucose supplementation on the growth kinetics of 60
Candida
spp. clinical isolates (
Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, Candida krusei
, and
Candida lusitaniae
[10 isolates each]) are assessed. The combined influence of growth and reading method (visual or spectrophotometric) on the determination of the MICs of amphotericin B, flucytosine, fluconazole, itraconazole, ketoconazole, and voriconazole is also analyzed, and the MICs are compared with those determined by the National Committee for Clinical Laboratory Standards standard microdilution method (NCCLS document M27-A). Glucose supplementation and inoculum size had a significant influence on the growth cycles of these yeasts, and a statistically significant denser growth (optical density at 540 nm) was seen for both incubation periods, 24 and 48 h (
P
< 0.01). A longer exponential phase and shorter lag phase were also observed. The
A
540
values at 24 h of incubation with medium containing glucose and an inoculum of 10
5
CFU/ml were >0.4 U for all species, with the exception of that for
C. parapsilosis
(
A
540
= 0.26 ± 0.025). The MICs at 24 h determined by testing with 2% glucose and an inoculum of 10
5
CFU/ml showed the strongest agreement (96.83%) with MICs determined by the reference method. MICs were not falsely elevated, and good correlation indexes were obtained. The reproducibility of results with this medium-inoculum combination was high (intraclass correlation coefficient, 0.955). The best agreement and reproducibility of results for spectrophotometric readings were achieved with endpoints of 50% growth inhibition for flucytosine and azoles and 95% for amphotericin B. Supplementation of test media with glucose and an inoculum size of 10
5
CFU/ml yielded a reproducible technique that shows elevated agreement with the reference procedures and a shorter incubation period for obtaining reliable MIC determinations. The spectrophotometric method offers an advantage over the visual method by providing a more objective and automated MIC determination.
Quantitative Detection of Hepatitis C Virus RNA by Light Cycler PCR and Comparison with Two Different PCR Assays
Authors: Schröter Matthias , Zöllner Bernhard , Schäfer Peter , Laufs Rainer , Feucht Heinz-Hubert 
Published: July 2002

ABSTRACT
The new Light Cycler technology was adapted to the detection of hepatitis C virus (HCV) RNA in clinical samples. Sera from 81 patients were tested by Light Cycler PCR, AMPLICOR HCV Monitor assay, and in-house PCR. Our data demonstrate that Light Cycler is a fast and reliable method for the detection and quantitation of HCV RNA.
Relationship between Susceptibility to Hemolytic-Uremic Syndrome and Levels of Globotriaosylceramide in Human Sera
Authors: Watarai Shinobu , Yokota Kenji , Tana  , Kishimoto Takumi , Kanadani Tomohosa , Taketa Kazuhisa , Oguma Keiji 
Published: July 2002

ABSTRACT

The relationship between differential susceptibility to hemolytic-uremic syndrome (HUS) and levels of globotriaosylceramide (Gb3) in serum was studied in patients infected with verotoxin-producing
Escherichia coli
(VTEC). The serum Gb3 levels in patients with HUS were lower than these in diarrheal patients without subsequent HUS or in patients without clinical symptoms, indicating that individuals with a lower content of serum Gb3 show a higher incidence of HUS following VTEC infection.
Phenotypic Methods for Determining Genomovar Status of the
Burkholderia cepacia
Complex
Authors: Henry Deborah A. , Mahenthiralingam Eshwar , Vandamme Peter , Coenye Tom , Speert David P. 
Published: July 2002

ABSTRACT

Recent taxonomic advances have demonstrated that
Burkholderia cepacia
is a cluster of at least seven closely related genomic species (or genomovars) collectively referred to as the
B. cepacia
complex, all of which may cause infections among cystic fibrosis patients and other vulnerable individuals. Thus, it is important for clinical microbiologists to be able to differentiate genomovars. Prior to this study, 361
B. cepacia
complex isolates and 51 isolates easily confused with
B. cepacia
complex previously had been identified using a polyphasic approach, and in this study, a comparison of phenotypic and biochemical tests was carried out. It was determined that
Burkholderia multivorans
and
Burkholderia stabilis
could reliably be separated from other members of the
B. cepacia
complex by phenotypic methods. A combination of phenotypic and molecular tests such as
recA
PCR and 16S rRNA RFLP are recommended for differentiation among the genomovars of the
B. cepacia
complex. A biochemical reaction scheme for the identification of
B. gladioli
, Pandoraea species, and
Ralstonia pickettii
and the differentiation of these species from the
B. cepacia
complex is also presented.
Resistance of
Pseudomonas aeruginosa
Isolates to Hydrogel Contact Lens Disinfection Correlates with Cytotoxic Activity
Authors: Lakkis Carol , Fleiszig Suzanne M. J. 
Published: July 2002

ABSTRACT

One of the most common pathogens in infection of hydrogel contact lens wearers is
Pseudomonas aeruginosa
, which can gain access to the eye via contamination of the lens, lens case, and lens care solutions. Only one strain per species is used in current regulatory testing for the marketing of chemical contact lens disinfectants. The aim of this study was to determine whether
P. aeruginosa
strains vary in their susceptibility to hydrogel contact lens disinfectants. A method for rapidly screening bacterial susceptibility to contact lens disinfectants was developed, based on measurement of the MIC. The susceptibility of 35
P. aeruginosa
isolates to two chemical disinfectants was found to vary among strains. MICs ranged from 6.25 to 100% for both disinfectants at 37°C, and a number of strains were not inhibited by a 100% disinfectant concentration in the lens case environment at room temperature (22°C). Resistance to disinfection appeared to be an inherent rather than acquired trait, since some resistant strains had been isolated prior to the introduction of the disinfectants and some susceptible
P. aeruginosa
strains could not be made more resistant by repeated disinfectant exposure. A number of
P. aeruginosa
strains which were comparatively more resistant to short-term disinfectant exposure also demonstrated the ability to grow to levels above the initial inoculum in one chemical disinfectant after long-term (24 to 48 h) disinfectant exposure. Resistance was correlated with acute cytotoxic activity toward corneal epithelial cells and with
exsA
, which encodes a protein that regulates cytotoxicity via a complex type III secretion system. These results suggest that chemical disinfection solutions may select for contamination with cytotoxic strains. Further investigation of the mechanisms and factors responsible for resistance may also lead to strategies for reducing adverse responses to contact lens wear.
Fluconazole Disk Diffusion Test with Methylene Blue- and Glucose-Enriched Mueller-Hinton Agar for Determining Susceptibility of
Candida
Species
Authors: Lee Sai-Cheong , Fung Chang-Phone , Lee Ning , See Lai-Chu , Huang Jen-Seng , Tsai Chi-Jen , Chen Kuo-Su , Shieh Wen-Ben 
Published: July 2002

ABSTRACT

A 25-μg fluconazole disk diffusion test using a Mueller-Hinton agar plate containing 2% glucose and 5 μg of methylene blue/ml (GM-MH) was compared to the macrodilution reference method for 210
Candida
species. The GM-MH agar plate was read at 24 h. The predictive values of disks with susceptible, intermediate, and resistant results on the GM-MH agar plate at 24 h were 97.1, 56.3, and 76.5%, respectively.
Monoclonal Antibody-Based Competitive Enzyme-Linked Immunosorbent Assay for Detection of Morbillivirus Antibody in Marine Mammal Sera
Authors: Saliki Jeremiah T. , Lehenbauer Terry W. 
Published: July 2002

ABSTRACT

A competitive enzyme-linked immunosorbent assay (cELISA), using two monoclonal antibodies (MAbs), was developed and compared with the standard virus neutralization test (VNT) for detecting antibodies against canine distemper virus (CDV) and phocine distemper virus (PDV) in sera from dogs and various species of marine mammals. The test depends on the blocking of MAb binding to solid-phase antigen in the presence of positive serum. Test conditions were optimized by using control VNT-negative and -positive sera specific for CDV and PDV. A positive cutoff value of 30% inhibition, which represents the mean cutoff of a VNT-negative population (
n
= 623) plus 2 standard deviations, was adopted for the test. A total of 736 serum samples were tested by the new cELISA and by the VNT as the “gold standard.” An unexpected but useful finding was the ability of this CDV- and PDV-specific cELISA to also detect antibodies against the related pair dolphin morbillivirus and porpoise morbillivirus. Based on a subpopulation of 625 sera used in statistical analyses, the overall sensitivity and specificity of cELISA relative to those of the VNT were 94.9 and 97.7%, respectively. Because the cELISA proved to be nearly as sensitive and specific as the VNT while being simpler and more rapid, it would be an adequate screening test for suspect CDV or PDV cases and would also be useful for epidemiological surveillance of morbilliviral infections in marine mammal populations.
Phylogenetic Characterization of Genotype 4 Hepatitis C Virus Isolates from Argentina
Authors: Alfonso Victoria , Flichman Diego , Sookoian Silvia , Mbayed Viviana Andrea , Campos Rodolfo Héctor 
Published: July 2002

ABSTRACT
Among 114 patients infected with hepatitis C virus, three genotype 4 isolates, unusual in Argentina, were detected by phylogenetic analysis over different genomic regions. The patients were not related. One sample was associated with Egyptian sequences, and the others were associated with a Zairean isolate, a fact which reinforces the idea that they are from independent sources.