bluuebunny/crossref_metadata_2025_split huggingface dataset:
GTPCyclohydrolase I: Purification, Characterization, and Effects ofInhibition on Nitric Oxide Synthase in
Nocardia
Species
Authors: He Aimin , Rosazza John P. N. 
Published: December 2003

ABSTRACT

GTP
cyclohydrolase I (GTPCH) catalyzes the first step in pteridine
biosynthesis in
Nocardia
sp. strain NRRL 5646.
This enzyme is important in the biosynthesis of tetrahydrobiopterin
(BH
4
), a reducing cofactor required for nitric oxide
synthase (NOS) and other enzyme systems in this organism. GTPCH was
purified more than 5,000-fold to apparent homogeneity by a combination
of ammonium sulfate fractionation, GTP-agarose, DEAE Sepharose, and
Ultragel AcA 34 chromatography. The purified enzyme gave a single band
for a protein estimated to be 32 kDa by sodium dodecyl
sulfate-polyacrylamide gel electrophoresis. The molecular mass of the
native enzyme was estimated to be 253 kDa by gel filtration, indicating
that the active enzyme is a homo-octamer. The enzyme follows
Michaelis-Menten kinetics, with a

K
m

for GTP of 6.5μ
M.
Nocardia
GTPCH possessed a unique N-terminal amino
acid sequence. The pH and temperature optima for the enzyme were 7.8
and 56°C, respectively. The enzyme was heat stable and slightly
activated by potassium ion but was inhibited by calcium, copper, zinc,
and mercury, but not magnesium. BH
4
inhibited enzyme
activity by 25% at a concentration of 100 μM.
2,4-Diamino-6-hydroxypyrimidine (DAHP) appeared to competitively
inhibit the enzyme, with a

K
i

of 0.23 mM. With
Nocardia
cultures, DAHP decreased medium levels of
NO
2
−
plus
NO
3
−
. Results suggest that in
Nocardia
cells, NOS synthesis of nitric oxide is indirectly
decreased by reducing the biosynthesis of an essential reducing
cofactor,
BH
4
.
Effect of Food Processing-Related Stresses on AcidTolerance of
Listeriamonocytogenes
Authors: Koutsoumanis Konstantinos P. , Kendall Patricia A. , Sofos John N. 
Published: December 2003

ABSTRACT

Stationary-phase
cells of
Listeria monocytogenes
grown in glucose-free or
glucose-containing media were exposed for 90 min to various stresses,
including acid stress (pH 4.0 to 7.0), osmotic stress (10.5 to
20.5% NaCl), and various temperatures (−5 to
50°C), and were further exposed to pH 3.5. Exposure to a mildly
acidic (pH 5.0 to 6.0) environment provided protection of the pathogen
against acid upon subsequent exposure. This adaptive response, however,
was found to be strongly dependent on other environmental conditions
during the shock, such as temperature or the simultaneous presence of a
second stress factor (NaCl). Growth of
L. monocytogenes
in the
presence of glucose resulted in enhanced survival of the pathogen at pH
3.5. Sublethal stresses other than acidic stresses, i.e., osmotic,
heat, and low-temperature stresses, did not affect the acid resistance
of
L. monocytogenes
(
P
> 0.5). More-severe
levels of these stresses, however, resulted in sensitization of the
pathogen to
acid.
Avian Reservoirs and Zoonotic Potential of theEmerging Human Pathogen
Helicobactercanadensis
Authors: Waldenström Jonas , On Stephen L. W. , Ottvall Richard , Hasselquist Dennis , Harrington Clare S. , Olsen Björn 
Published: December 2003

ABSTRACT

A
polyphasic identification approach was used to investigate the
taxonomic position of
Campylobacter-
like isolates recovered
from barnacle geese (
Branta leucopsis
) and Canada geese
(
Branta candensis
). Seven strains were selected from a
collection of 21 isolates and analyzed by extensive phenotypic testing;
four strains were characterized by 16S rRNA gene sequence analysis. The
results clearly identified the bird isolates as
Helicobacter
canadensis
, recently described as an emerging human pathogen. This
is the first report of an animal reservoir for this organism and of its
presence in Europe and confirms the zoonotic potential of
H.
canadensis
.
Chemoattraction of
Vibrio fischeri
to Serine, Nucleosides, and
N
-Acetylneuraminic Acid, a Component of Squid Light-Organ Mucus
Authors: DeLoney-Marino Cindy R. , Wolfe Alan J. , Visick Karen L. 
Published: December 2003

ABSTRACT

Newlyhatched juveniles of the Hawaiian squid
Euprymna scolopes
rapidly become colonized by the bioluminescent marine bacterium
Vibrio fischeri
. Motility is required to establish the
symbiotic colonization, but the role of chemotaxis is unknown. In this
study we analyzed chemotaxis of
V. fischeri
to a number of
potential attractants. The bacterium migrated toward serine and most
sugars tested.
V. fischeri
also exhibited the unusual ability
to migrate to nucleosides and nucleotides as well as to

N

-acetylneuraminic acid, a component of squid
mucus.
Detection of a
Salmonella enterica
SerovarCalifornia Strain Spreading in Spanish Feed Mills and GeneticCharacterization with DNAMicroarrays
Authors: Alvarez Juan , Porwollik Steffen , Laconcha Idoia , Gisakis Vassilis , Vivanco Ana Belén , Gonzalez Iratxe , Echenagusia Susana , Zabala Nieves , Blackmer Felisa , McClelland Michael , Rementeria Aitor , Garaizar Javier 
Published: December 2003

ABSTRACT

We
performed an epidemiological study on
Salmonella
isolated from
raw plant-based feed in Spanish mills. Overall, 32
different
Salmonella
serovars were detected. Despite its rare
occurrence in humans and animals,
Salmonella enterica
serovar California was found to be the predominant serovar in Spanish
feed mills. Different typing techniques showed that isolates of this
serovar were genetically closely related, and comparative genomic
hybridization using microarray technology revealed 23
S
.
enterica
serovar Typhimurium LT2 gene clusters that are absent
from serovar
California.
Application of Genome-Wide Expression Analysis ToIdentify Molecular Markers Useful in MonitoringIndustrialFermentations
Authors: Higgins Vincent J. , Rogers Peter J. , Dawes Ian W. 
Published: December 2003

ABSTRACT

Genome-wide
expression analysis of an industrial strain of
Saccharomyces
cerevisiae
identified the
YOR387c
and
YGL258w
homologues as highly inducible in zinc-depleted
conditions. Induction was specific for zinc deficiency and was
dependent on Zap1p. The results indicate that these sequences may be
valuable molecular markers for detecting zinc deficiency in industrial
fermentations.
Prevalence of Cholera Toxin Genes (
ctxA
and
zot
) among Non-O1/O139
Vibrio cholerae
Strainsfrom Newport Bay,California
Authors: Jiang Sunny , Chu Weiping , Fu Wuxia 
Published: December 2003

ABSTRACT

The
examination of 137 non-O1/O139
Vibrio cholerae
isolates from
Newport Bay, California, indicated the presence of diverse genotypes
and a temporal succession. Unexpectedly, the cholera toxin gene
(
ctxA
) was found in 17% of the strains, of which
one-third were also positive for the
zot
gene. This suggests
that
ctxA
is prevalent in the region of nonepidemicity and is
likely to have an environmental
origin.
Case Study of the Distribution of Mucosa-Associated
Bifidobacterium
Species,
Lactobacillus
Species, andOther Lactic Acid Bacteria in the HumanColon
Authors: Nielsen D. S. , Møller P. L. , Rosenfeldt V. , Pærregaard A. , Michaelsen K. F. , Jakobsen M. 
Published: December 2003

ABSTRACT

The
distribution of mucosa-associated bacteria, bifidobacteria and
lactobacilli and closely related lactic acid bacteria, in biopsy
samples from the ascending, transverse, and descending parts of the
colon from four individuals was investigated by denaturing gradient gel
electrophoresis (DGGE). Bifidobacterial genus-specific,
Lactobacillus
group-specific, and universal bacterial primers
were used in a nested PCR approach to amplify a fragment of the 16S
rRNA gene. DGGE profiles of the bifidobacterial community were
relatively simple, with one or two amplicons detected at most sampling
sites in the colon. DGGE profiles obtained with
Lactobacillus
group-specific primers were complex and varied with host and sampling
site in the colon. The overall bacterial community varied with host but
not sampling
site.
A Newly DiscoveredVerotoxin Variant, VT2
g
, Produced by Bovine Verocytotoxigenic
Escherichiacoli
Authors: Leung P. H. M. , Peiris J. S. M. , Ng W. W. S. , Robins-Browne R. M. , Bettelheim K. A. , Yam W. C. 
Published: December 2003

ABSTRACT

A
new verotoxin (VT) variant, designated
vt2g
, was identified
from a bovine strain of verocytotoxigenic
Escherichia coli
(VTEC) serotype O2:H25. When
vt2g
was aligned with published
sequences of
vt2
and
vt
variants, it exhibited the
highest DNA sequence homology with
vt2
and
vt2c
.
However,
vt2g
was not detected by
vt2-
specific
primers and probes, although it was partially neutralized by an
antiserum to the VT2A subunit. VT2g was cytotoxic for Vero and HeLa
cells and was not activated by mouse intestinal mucus. The
vt2g
gene was detected in 3 of 409 (0.7%) bovine VTEC
strains, including serotypes O2:H25, O2:H45 and
Ont:H
−
.
Antifungal 3-Hydroxy Fatty Acids from
Lactobacillus plantarum
MiLAB14
Authors: Sjögren Jörgen , Magnusson Jesper , Broberg Anders , Schnürer Johan , Kenne Lennart 
Published: December 2003

ABSTRACT

We
report the identification and chemical characterization of four
antifungal substances, 3-(
R
)-hydroxydecanoic acid,
3-hydroxy-5-
cis
-dodecenoic acid,
3-(
R
)-hydroxydodecanoic acid and
3-(
R
)-hydroxytetradecanoic acid, from
Lactobacillus
plantarum
MiLAB 14. The concentrations of the 3-hydroxy fatty
acids in the supernatant followed the bacterial growth. Racemic
mixtures of the saturated 3-hydroxy fatty acids showed antifungal
activity against different molds and yeasts with MICs between 10 and
100 μg
ml
−1
.
Construction of a Genetically Modified Wine YeastStrain Expressing theAspergillus aculeatus rhaAGene,Encoding an α-l-Rhamnosidase ofEnologicalInterest
Authors: Manzanares Paloma , Orejas Margarita , Gil José Vicente , de Graaff Leo H. , Visser Jaap , Ramón Daniel 
Published: December 2003

ABSTRACTTheAspergillus aculeatus rhaAgene encoding anα -l-rhamnosidase has been expressed in both laboratory and industrial wine yeast strains. Wines produced in microvinifications, conducted using a combination of the genetically modified industrial strain expressingrhaAand another strain expressing a β-glucosidase, show increased content mainly of the aromatic compound linalool.
Genetic Characterization of the CarotenoidBiosynthetic Pathway in
Methylobacterium extorquens
AM1 andIsolation of a ColorlessMutant
Authors: Van Dien Stephen J. , Marx Christopher J. , O'Brien Brooke N. , Lidstrom Mary E. 
Published: December 2003

ABSTRACT

Genomic
searches were used to reconstruct the putative carotenoid biosynthesis
pathway in the pink-pigmented facultative methylotroph
Methylobacterium extorquens
AM1. Four genes for putative
phytoene desaturases were identified. A colorless mutant was obtained
by transposon mutagenesis, and the insertion was shown to be in one of
the putative phytoene desaturase genes. Mutations in the other three
did not affect color. The tetracycline marker was removed from the
original transposon mutant, resulting in a pigment-free strain with
wild-type growth properties useful as a tool for future
experiments.
Characterization ofSalmonella entericaSerotype Newport Isolated from Humans and Food Animals
Authors: Zhao S. , Qaiyumi S. , Friedman S. , Singh R. , Foley S. L. , White D. G. , McDermott P. F. , Donkar T. , Bolin C. , Munro S. , Baron E. J. , Walker R. D. 
Published: December 2003

ABSTRACTSalmonella entericaserotype Newport isolates resistant to at least nine antimicrobials (including extended-spectrum cephalosporins), known as serotype Newport MDR-AmpC isolates, have been rapidly emerging as pathogens in both animals and humans throughout the United States. Resistance to extended-spectrum cephalosporins is associated with clinical failures, including death, in patients with systemic infections. In this study, 87Salmonellaserotype Newport strains were characterized by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing and examined for the presence of class 1 integrons andblaCMYgenes. Thirty-five PFGE patterns were observed withXbaI, and three of these patterns were indistinguishable among isolates from humans and animals. Fifty-three (60%)Salmonellaserotype Newport isolates were identified as serotype Newport MDR-AmpC, including 16 (53%) of 30 human isolates, 27 (93%) of 29 cattle isolates, 7 (70%) of 10 swine isolates, and 3 (30%) of 10 chicken isolates. However, 28 (32%)Salmonellaserotype Newport isolates were susceptible to all 16 antimicrobials tested. TheblaCMYgene was present in all serotype Newport MDR-AmpC isolates. Furthermore, the plasmid-mediatedblaCMYgene was transferable via conjugation to anEscherichia colistrain. The transconjugant showed the MDR-AmpC resistance profile. Thirty-five (40%) of the isolates possessed class 1 integrons. Sequence analyses of the integrons showed that they containedaadA, which confers resistance to streptomycin, oraadAanddhfr, which confer resistance to trimethoprim-sulfamethoxazole. One integron from a swine isolate contained thesat-1gene, which encodes resistance to streptothricin, an antimicrobial agent that has never been approved for use in the United States. In conclusion,Salmonellaserotype Newport MDR-AmpC was commonly identified amongSalmonellaserotype Newport isolates recovered from humans and food animals. These findings support the possibility of transmission of this organism to humans through the food chain.
Gene Sequence-Based Criteria for Identification of NewRickettsiaIsolates and Description ofRickettsia heilongjiangensissp. nov
Authors: Fournier Pierre-Edouard , Dumler J. Stephen , Greub Gilbert , Zhang Jianzhi , Wu Yimin , Raoult Didier 
Published: December 2003

ABSTRACTWe propose genetic guidelines for the classification of rickettsial isolates at the genus, group, and species levels by using sequences of the 16S rRNA (rrs) gene and four protein-coding genes, thegltA,ompA, andompBgenes and gene D. To be classified as a member of the genusRickettsia, an isolate should exhibit degrees ofrrsandgltAhomology with any of the 20Rickettsiaspecies studied of ≥98.1 and ≥86.5%, respectively. A member of the typhus group should fulfill at least two of the following four criteria: pairwise nucleotide sequence homologies withrrs,gltA,ompB, and gene D of eitherRickettsia typhiorRickettsia prowazekiiof ≥99.4, ≥96.6, ≥92.4, and ≥91.6%, respectively. A member of the spotted fever group should either possess theompAgene or fulfill at least two of the following four criteria: pairwise nucleotide sequence homologies withrrs,gltA,ompB, and gene D of any member of this group of ≥98.8, ≥92.7, ≥85.8, and ≥82.2%, respectively. The existence of a distinct “ancestral” group should be questioned. To be classified as a newRickettsiaspecies, an isolate should not exhibit more than one of the following degrees of nucleotide similarity with the most homologous validated species: ≥99.8 and ≥ 99.9% for therrsandgltAgenes, respectively, and, when amplifiable, ≥98.8, ≥99.2, and ≥99.3% for theompAandompBgenes and gene D, respectively. By use of our classification scheme, “Rickettsia heilongjiangii” belongs to a new species for which we officially propose the nameRickettsia heilongjiangensissp. nov.
Comparison of the Susceptibilities of
Candida
spp. to Fluconazole and Voriconazole in a 4-Year Global Evaluation Using Disk Diffusion
Authors: Hazen Kevin C. , Baron Ellen Jo , Colombo Arnaldo Lopes , Girmenia Corrado , Sanchez-Sousa Aurora , del Palacio Amalia , de Bedout Catalina , Gibbs David L. 
Published: December 2003

ABSTRACT

From June 1997 to December 2001, results of in vitro susceptibility tests of yeast isolates from 35 countries were collected. For 2001 alone, fluconazole results were reported for 22,111 yeast isolates from 77 institutions in 30 countries. Of these isolates, 18,569 were also tested for susceptibility to voriconazole. All study sites tested clinical yeast isolates by recently endorsed NCCLS disk diffusion method M44-P. Disk test plates were automatically read and results were recorded with the BIOMIC Image Analysis System. Species, drug, zone diameter, susceptibility category, MIC, and quality control results were electronically submitted by e-mail quarterly for analysis. Duplicate test results (same patient and same species with same sensitivity-resistance profile and biotype results during any 7-day period) and uncontrolled test results were eliminated from this analysis. The proportion of
Candida albicans
isolates decreased from 69.7% in 1997 to 1998 to 63.0% in 2001, and this decrease was accompanied by a concomitant increase in C.
tropicalis
and
C. parapsilosis
. The susceptibility (susceptible [S]or susceptible-dose dependent [S-DD]) of
C. albicans
isolates to fluconazole was virtually unchanged, from 99.2% in 1997 to 99% in 2001; the
C. glabrata
response to fluconazole was unchanged, from 81.5% S or S-DD in 1997 to 81.7% in 2001, although the percentage of resistant isolates from blood and upper respiratory tract samples appeared to increase over the study period; the percentage of S
C. parapsilosis
isolates decreased slightly, from 98% S or S-DD in 1997 to 96% in 2001; and the percentage of S isolates of
C. tropicalis
increased slightly, from 95.7% in 1997 to 96.9% in 2001. The highest rate of resistance to fluconazole among
C. albicans
isolates was noted in Ecuador (7.6%,
n
= 250). Results from this investigation indicate that the susceptibility of yeast isolates to fluconazole has changed minimally worldwide over the 4.5-year study period and that voriconazole demonstrated 10- to 100-fold greater in vitro activity than fluconazole against most yeast species.
New Methods To Assess Susceptibilities of
Aspergillus
Isolates to Caspofungin
Authors: Imhof Alexander , Balajee S. Arunmozhi , Marr Kieren A. 
Published: December 2003

ABSTRACT

Echinocandins are a group of antifungal agents that target 1,3-β-glucan synthase, causing disruption of mold growth at cells compromising tips and branch points. In part because echinocandins do not induce clear growth inhibition end points using broth dilution techniques, methods to test susceptibility have not yet been standardized. We developed a novel susceptibility assay that measures growth of
Aspergillus
species on solid agar media that contain serial dilutions of caspofungin (agar dilution). Results of agar dilution testing of multiple isolates were compared to results obtained by broth microdilution (MIC), microscopic evaluation (minimal effective concentration [MEC]), and a new method to measure fungal burden, quantification of secreted hyphal antigen. MICs obtained by the agar dilution method were within 1 dilution of MECs for 85% of the
Aspergillus
isolates; the highest agreement was observed for isolates of
Aspergillus niger
(95%), which were particularly susceptible to caspofungin. Agar dilution MICs were also consistent with those obtained by quantifying antigen secretion. MICs obtained by broth microdilution were different than MICs by any other method. Several
Aspergillus
isolates with decreased susceptibility to caspofungin were identified. Agar dilution is simple and reproducible, and results were consistent with the results of more technically demanding techniques. This method may be appropriate for use in the clinical laboratory.
Highly Resistant Metabolically Deficient Dwarf Mutant of
Escherichia coli
Is the Cause of a Chronic Urinary Tract Infection
Authors: Trülzsch Konrad , Hoffmann Harald , Keller Christiane , Schubert Sören , Bader Lutz , Heesemann Jürgen , Roggenkamp Andreas 
Published: December 2003

ABSTRACT

We present the case of a 68-year-old diabetic woman who has been suffering from chronic urinary tract infections, recurring over a period of at least 5 years, caused by a slowly growing metabolically deficient dwarf mutant (MDD) of
Escherichia coli.
This MDD strain was auxotrophic for histidine, was resistant to multiple antibiotics, and showed atypical growth behavior. Colonies were tiny on routine media but were able to revert to normal growth after extended incubation. This strain was identified as
E. coli
by 16S ribosomal DNA sequencing, and virulence factor profiles were determined by PCR. Seven MDD isolates collected over the 5-year period were grown from midstream urine to significant colony counts and shown to belong to the same clonal group by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus PCR. These MDDs were repeatedly misidentified by biochemical methods due to their slow growth and atypical colony morphology. This case highlights the importance of recognizing MDDs of
Enterobacteriaceae
in patients with chronic infections. To our knowledge this is the first report of an MDD of
E. coli
causing a chronic urinary tract infection.
Determinants of Acquisition and Carriage ofStaphylococcus aureusin Infancy
Authors: Peacock Sharon J. , Justice Anita , Griffiths D. , de Silva G. D. I. , Kantzanou M. N. , Crook Derrick , Sleeman Karen , Day Nicholas P. J. 
Published: December 2003

ABSTRACTNasal carriage ofStaphylococcus aureusis a major risk factor for invasiveS. aureusdisease. The aim of this study was to define factors associated with carriage. We conducted a prospective, longitudinal community-based study of infants and their mothers for a period of 6 months following delivery. The epidemiology of carriage was examined for 100 infant-mother pairs. Infant carriage varied significantly with age, falling from 40 to 50% during the first 8 weeks to 21% by 6 months. Determinants of infantS. aureuscarriage included maternal carriage, breastfeeding, and number of siblings. Bacterial typing ofS. aureuswas performed by pulsed-field gel electrophoresis and multilocus sequence typing. The majority of individuals carried a single strain ofS. aureusover time, and the mother was the usual source for colonizing isolates in infants. The effect of other components of the normal nasal flora on the development ofS. aureuscarriage was examined in 157 consecutive infants. Negative associations (putative bacterial interference) betweenS. aureusand other species occurred early in infancy but were not sustained. An increasing antistaphylococcal effect observed over time was not attributable to bacterial interference.S. aureuscarriage in infants is likely to be determined by a combination of host, environmental, and bacterial factors, but bacterial interference does not appear to be an ultimate determinant of carrier status.
Molecular Comparison of Isolates of
Burkholderia multivorans
from Patients with Cystic Fibrosis in the United Kingdom
Authors: Turton Jane F. , Kaufmann Mary E. , Mustafa Nazim , Kawa Sonia , Clode Fiona E. , Pitt Tyrone L. 
Published: December 2003

ABSTRACT

Burkholderia multivorans
strains from 47 cystic fibrosis (CF) patients in 28 hospitals were compared by pulsed-field gel electrophoresis (PFGE) and flagellin (
fliC
) PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. A considerable degree of genetic variation was evident, with each patient harboring a strain with a unique PFGE profile. Four sizes of
fliC
amplicons were produced, and these amplicons gave 13 RFLP types with restriction enzyme
Msp
I.
B. multivorans
did not appear to spread between patients, suggesting that most CF patients acquire the organism from the natural environment.
Evaluationof the Mandibular Third Molar Pericoronitis Flora and ItsSusceptibility to Different Antibiotics PrescribedinFrance
Authors: Sixou Jean-Louis , Magaud Christophe , Jolivet-Gougeon Anne , Cormier Michel , Bonnaure-Mallet Martine 
Published: December 2003

ABSTRACT
This
work assessed the polymicrobial flora of mandibular third molar
pericoronitis. Obligate anaerobes were found in almost all cases (32 of
35). Amoxicillin and pristinamycin were the most effective against the
flora, particularly aerobic organisms. Metronidazole alone or combined
with spiramycin was the most effective drug against obligate
anaerobes.