bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid 5′ Nuclease (TaqMan) Assay for Detection of Virulent Strains of
Yersinia enterocolitica
Authors: Vishnubhatla A. , Fung D. Y. C. , Oberst R. D. , Hays M. P. , Nagaraja T. G. , Flood S. J. A. 
Published: July 2002

ABSTRACT

We have developed a rapid procedure for the detection of virulent
Yersinia enterocolitica
in ground pork by combining a previously described PCR with fluorescent dye technologies. The detection method, known as the fluorogenic 5′ nuclease assay (TaqMan), produces results by measuring the fluorescence produced during PCR amplification, requiring no post-PCR processing. The specificity of the chromosomal
yst
gene-based assay was tested with 28 bacterial isolates that included 7 pathogenic and 7 nonpathogenic serotypes of
Y. enterocolitica
, other species of
Yersinia
(
Y. aldovae
,
Y. pseudotuberculosis
,
Y. mollaretti
,
Y. intermedia
,
Y. bercovieri
,
Y. ruckeri
,
Y. frederiksenii
, and
Y. kristensenii
), and other enteric bacteria (
Escherichia
,
Salmonella
,
Citrobacter
, and
Flavobacterium
). The assay was 100% specific in identifying the pathogenic strains of
Y. enterocolitica
. The sensitivity of the assay was found to be ≥10
2
CFU/ml in pure cultures and ≥10
3
CFU/g in spiked ground pork samples. Results of the assay with food enrichments prespiked with
Y. enterocolitica
serotypes O:3 and O:9 were comparable to standard culture results. Of the 100 field samples (ground pork) tested, 35 were positive for virulent
Y. enterocolitica
with both 5′ nuclease assay and conventional virulence tests. After overnight enrichment the entire assay, including DNA extraction, amplification, and detection, could be completed within 5 h.
Construction of a Multihybrid Display System: Flagellar Filaments Carrying Two Foreign Adhesive Peptides
Authors: Tanskanen Jarna , Korhonen Timo K. , Westerlund-Wikström Benita 
Published: July 2002

ABSTRACT

A multivalent, bifunctional flagellum carrying two different adhesive peptides in separate flagellin subunits within a filament was constructed in
Escherichia coli
. The inserted peptides were the fibronectin-binding 115-mer D repeat region of
Staphylococcus aureus
and the 302-mer collagen-binding region of YadA of
Yersinia enterocolitica
. Western blotting, immunoelectron microscopy, and adhesion tests with hybrid flagella from an in
trans
-complemented Δ
fliC E. coli
strain showed that individual filaments consisted of both recombinant flagellins.
Light Conditions Affect the Measurement of Oceanic Bacterial Production via Leucine Uptake
Authors: Morán Xosé Anxelu G. , Massana Ramon , Gasol Josep M. 
Published: July 2002

ABSTRACT

The effect of irradiance in the range of 400 to 700 nm or photosynthetically active radiation (PAR) on bacterial heterotrophic production estimated by the incorporation of
3
H-leucine (referred to herein as Leu) was investigated in the northwestern Mediterranean Sea and in a coastal North Atlantic site, with Leu uptake rates ranging over 3 orders of magnitude. We performed in situ incubations under natural irradiance levels of Mediterranean samples taken from five depths around solar noon and compared them to incubations in the dark. In two of the three stations large differences were found between light and dark uptake rates for the surfacemost samples, with dark values being on average 133 and 109% higher than in situ ones. Data obtained in coastal North Atlantic waters confirmed that dark enclosure may increase Leu uptake rates more than threefold. To explain these differences, on-board experiments of Leu uptake versus irradiance were performed with Mediterranean samples from depths of 5 and 40 m. Incubations under a gradient of 12 to 1,731 μmol of photons m
−2
s
−1
evidenced a significant increase in incorporation rates with increasing PAR in most of the experiments, with dark-incubated samples departing from this pattern. These results were not attributed to inhibition of Leu uptake in the light but to enhanced bacterial response when transferred to dark conditions. The ratio of dark to light uptake rates increased as dissolved inorganic nitrogen concentrations decreased, suggesting that bacterial nutrient deficiency was overcome by some process occurring only in the dark bottles.
Flux Analysis of the Metabolism of
Clostridium cellulolyticum
Grown in Cellulose-Fed Continuous Culture on a Chemically Defined Medium under Ammonium-Limited Conditions
Authors: Desvaux Mickaël , Petitdemange Henri 
Published: July 2002

ABSTRACT

An investigation of cellulose degradation by the nonruminal, cellulolytic, mesophilic bacterium
Clostridium cellulolyticum
was performed in cellulose-fed chemostat cultures with ammonium as the growth-limiting nutrient. At any dilution rate (
D
), acetate was always the main product of the catabolism, with a yield of product from substrate ranging between 37.7 and 51.5 g per mol of hexose equivalent fermented and an acetate/ethanol ratio always higher than 1. As
D
rose, the acetyl coenzyme A was rerouted in favor of ethanol pathways, and ethanol production could represent up to 17.7% of the carbon consumed. Lactate was significantly produced, but with increasing
D
, the specific lactate production rate declined, as did the specific rate of production of extracellular pyruvate. The proportion of the original carbon directed towards phosphoglucomutase remained constant, and the carbon surplus was balanced mainly by exopolysaccharide and glycogen biosyntheses at high
D
values, while cellodextrin excretion occurred mainly at lower ones. With increasing
D
, the specific rate of carbon flowing down catabolites increased as well, but when expressed as a percentage of carbon it declined, while the percentage of carbon directed through biosynthesis pathways was enhanced. The maximum growth and energetic yields were lower than those obtained in cellulose-limited chemostats and were related to an uncoupling between catabolism and anabolism leading to an excess of energy. Compared to growth on cellobiose in ammonium-limited chemostats (E. Guedon, M. Desvaux, and H. Petitdemange, J. Bacteriol. 182:2010–2017, 2000), (i) a specific consumption rate of carbon of as high as 26.72 mmol of hexose equivalent g of cells
−1
h
−1
could not be reached and (ii) the proportions of carbon directed towards cellodextrin, glycogen, and exopolysaccharide pathways were not as high as first determined on cellobiose. While the use of cellobiose allows highlighting of metabolic limitation and regulation of
C. cellulolyticum
under ammonium-limited conditions, some of these events should then rather be interpreted as distortions of the metabolism. Growth of cellulolytic bacteria on easily available carbon and nitrogen sources represents conditions far different from those of the natural lignocellulosic compounds.
Enzymatic Synthesis of Aminoglycoside Antibiotics: Novel Adenosylmethionine:2-Deoxystreptamine
N
-Methyltransferase Activities in Hygromycin B- and Spectinomycin-Producing
Streptomyces
spp. and Uses of the Methylated Products
Authors: Walker James B. 
Published: July 2002

ABSTRACT

Aminocyclitols structurally related to streptamine, a 1,3-diaminocyclitol, are common components of the RNA-binding aminoglycoside antibiotics. The respective aminocyclitol cores of hygromycin B and spectinomycin are
N
3
-methyl-2-deoxy-
d
-streptamine and
N
1
,
N
3
-dimethyl-2-
epi
-streptamine. Adenosyl[
methyl
-
14
C]methionine:2-deoxystreptamine
N
-methyltransferase activities were detected in extracts of early-stationary-phase mycelia of the hygromycin B producer
Streptomyces hygroscopicus
subsp.
hygroscopicus
ATCC 27438 and the spectinomycin producer
Streptomyces flavopersicus
ATCC 19756. Extracts of both strains methylated the N
1
- and N
3
-amino groups of 2-deoxystreptamine, streptamine, and 2-
epi
-streptamine; the N
1
-amino group of
N
3
-methyl-2-deoxy-
d
-streptamine, and the N
3
-amino group of
N
1
-ethyl-2-deoxy-
d
-streptamine, the semisynthetic aminocyclitol of netilmicin. The mono[
14
C]methyl derivatives of 2-deoxystreptamine, streptamine, and 2-
epi
-streptamine were excellent substrates for
l
-glutamine:aminocyclitol aminotransferase and thereby provided a sensitive assay for derepression of this key enzyme, a generic biosynthetic marker that we have shown to be the only enzyme common to the biosyntheses of all major aminoglycoside antibiotics. Other prospective uses for these methyl-labeled 2-deoxystreptamine analogs are also described.
Genetic Characterization of
Cylindrospermopsis raciborskii
(Cyanobacteria) Isolates from Diverse Geographic Origins Based on
nifH
and
cpcBA
-IGS Nucleotide Sequence Analysis
Authors: Dyble Julianne , Paerl Hans W. , Neilan Brett A. 
Published: July 2002

ABSTRACT

Isolates of the toxic, N
2
-fixing species
Cylindrospermopsis raciborskii
from various geographic locations were analyzed with respect to their genetic diversity based on the
nifH
and
cpcBA
-IGS genes. Gene sequences clustered according to their geographic origin, with the
nifH
sequences separating into European, Australian, and American groups and the
cpcBA
-IGS sequences separating into American and European or Australian groups. PCR primers for both genes were designed to exclusively amplify DNA from
Cylindrospermopsis
species, and an additional primer set for
cpcBA
-IGS was designed to specifically amplify the American
C. raciborskii
strains.
Cocaine Causes Increased Type I Interferon Secretion by both L929 Cells and Murine Macrophages
Authors: Grattendick K. , Jansen D. B. , Lefkowitz D. L. , Lefkowitz S. S. 
Published: July 2002

ABSTRACTCocaine has been demonstrated to have a number of different effects on immune cell functions. We have reported alterations of cellular functions by macrophages (Mφ) exposed to cocaine in vitro, including the inhibition of mouse hepatitis virus replication. Here, we present evidence that cocaine stimulates the secretion of an antiviral product that is neutralized by anti-interferon (anti-IFN). A dose-dependent increase in the secretion of IFN by both Mφ and L929 cells incubated with cocaine, with a concomitant decrease in virus replication, is also reported. The increase in IFN secretion was most pronounced when cells were cultured in the presence of the IFN inducer poly(I·C). The effect of cocaine on IFN production was found to be primarily at the transcript level in both Mφ and L929 cells. These findings further support our previous research demonstrating an antiviral activity of cocaine in vitro. The relevance of this activity to viral infections in general remains to be determined.
Prevalence and Phylogenetic Analysis of TT Virus DNA in Western India
Authors: Arankalle V. A. , Gandhe S. S. , Deshmukh T. M. , Chadha M. S. , Walimbe A. M. 
Published: July 2002

ABSTRACT
In western India, TT virus (TTV) DNA positivity varied from 6.7% (5 of 75) in chronic hepatitis patients to 24.4% (10 of 41) in hemophiliacs; 7.4% (4 of 54) of voluntary blood donors had circulating TTV DNA. Phylogenetic analysis revealed a predominance of genotype 1a. In India, TTV is transmitted mainly by nonparenteral routes and is not an important cause of chronic liver diseases.
Comparison of a Chemiluminescent Immunoassay with Two Microparticle Enzyme Immunoassays for Detection of Hepatitis B Virus Surface Antigen
Authors: Diepersloot Robert J. A. , van Zantvliet-van Oostrom Yvonne , Gleaves Curt A. 
Published: July 2002

ABSTRACT

A comparative evaluation of the following commercial immunoassays for the detection of hepatitis B virus surface antigen (HBsAg) was performed: the Abbott AxSYM, Abbott IMx, and DPC IMMULITE assays. The specificity was 100% for all assays. Twelve samples were identified and were confirmed to be positive for HBsAg by all three methods. One additional sample was identified as reactive and was confirmed to be positive by the Abbott AxSYM assay only. Prior to confirmation testing the DPC IMMULITE assay produced significantly fewer false-positive results than the Abbott AxSYM assay (
P
< 0.05).
Seroepidemiology of Human Group C Rotavirus in Japan Based on a Blocking Enzyme-Linked Immunosorbent Assay
Authors: Kuzuya Mitsutaka , Fujii Ritsushi , Hamano Masako , Ohata Ritsuko , Ogura Hajime , Yamada Masao 
Published: July 2002

ABSTRACT
A novel blocking enzyme-linked immunosorbent assay (BL-ELISA) was developed for detection of antibodies to human group C rotavirus (CHRV). The specificity of the BL-ELISA was confirmed by using animal sera hyperimmunized to group A and group C rotaviruses and paired sera from five patients with acute CHRV gastroenteritis. Furthermore, there was concordance between the BL-ELISA and a neutralization assay for CHRV in 226 (95%) of 238 samples. By using the BL-ELISA, we determined the seroprevalence of CHRV in 704 serum samples obtained from nine different age groups of inhabitants of Okayama Prefecture, Japan, in 1992, 1994, and 1996. As a result, 211 sera (30%) were found to be positive for CHRV antibodies. The seroprevalence gradually increased with age and reached 52.7% in the oldest individuals. A further analysis of the youngest age group suggested that CHRVs predominantly prevail in persons older than 3 years of age in Japan. When comparing the three sampling years, a larger percentage of antibody-positive sera was detected in 1994 than in either 1992 or 1996 in individuals between 6 and 15 years of age, reflecting the occurrence of a CHRV outbreak among children during the winter of 1992 to 1993 that was previously documented. These results indicate that CHRV infections may occur more frequently in spite of the relatively low detection rate of the virus.
Analysis of
Chlamydia pneumoniae
Growth in Cells by Reverse Transcription-PCR Targeted to Bacterial Gene Transcripts
Authors: Haranaga Shusaku , Ikejima Hideaki , Yamaguchi Hiroyuki , Friedman Herman , Yamamoto Yoshimasa 
Published: July 2002

ABSTRACT

Chlamydia pneumoniae
is an obligate intracellular bacterium and has a unique development cycle consisting of an elementary body (EB) and reticular body (RB). EBs survive in extracellular environments as well as infect susceptible host cells. However, EBs display no measurable metabolic activity. In contrast, RBs are metabolically active and can replicate in a host cell but are noninfectious. Therefore, analysis of
C. pneumoniae
growth in infected cells by conventional bacterial culture may not permit sufficient information about growth of the bacteria in cells. In this study, therefore, we examined the usefulness of the reverse transcription (RT)-PCR method for analysis of bacterial transcripts to evaluate
C. pneumoniae
growth in HEp-2 cells because the levels of bacterial gene transcripts are known to show the metabolic activity of bacteria. The transcripts for the
C. pneumoniae hsp60
gene and 16S rRNA in the cells were easily detected just after infection, followed by a marked increase. In contrast,
pyk
and
omcB
transcripts slowly increased after a latent period. The hydrocortisone treatment of
C. pneumoniae
-infected cells induced an increase of all bacterial transcripts tested compared with the control group. The treatment of the infected cells with the antibiotic minocycline showed a selective inhibition of bacterial gene transcripts, even though the complete inhibition of EB production determined by the bacterial culture assay was evident. These results indicate that the determination of bacterial gene transcripts by RT-PCR might be a powerful method to analyze in detail growth of
C. pneumoniae
in host cells, particularly altered bacterial growth caused by agents such as antimicrobials.
Immunocytochemical Method for Early Laboratory Diagnosis of Tuberculous Meningitis
Authors: Sumi M. G. , Mathai A. , Reuben S. , Sarada C. , Radhakrishnan V. V. 
Published: July 2002

ABSTRACT

A simple immunocytochemical method was standardized for the direct demonstration of mycobacterial antigen in cerebrospinal fluid (CSF) specimens of patients with tuberculous meningitis (TBM). CSF-cytospin smears were prepared from 22 patients with a clinical diagnosis of TBM and also from an equal number of patients with nontuberculous neurological diseases (disease control). Immunocytological demonstration of mycobacterial antigens in the cytoplasm of monocytoid cells was attempted, by using rabbit immunoglobulin G to
Mycobacterium tuberculosis
as the primary antibody. Of the 22 CSF-cytospin smears from TBM patients, 16 showed positive immunostaining, while all of the CSF-cytospin smears from the disease control showed negative immunostaining for mycobacterial antigen. The technical aspects of this immunocytological method for the demonstration of mycobacterial antigens are simple, rapid, and reproducible, as well as specific, and therefore can be applied for the early diagnosis of TBM, particularly in patients in whom bacteriological methods did not demonstrate the presence of
M. tuberculosis
in the CSF.
Generation of Female Genital Tract Antibody Responses by Local or Central (Common) Mucosal Immunization
Authors: Wu Hong-Yin , Abdu Samira , Stinson Dana , Russell Michael W. 
Published: July 2002

ABSTRACTGenital antibody responses were compared in female mice immunized intravaginally (i.vag.) or intranasally (i.n.) with a bacterial protein antigen (AgI/II ofStreptococcus mutans) coupled to the B subunit of cholera toxin. Serum and salivary antibodies were also evaluated as measures of disseminated mucosal and systemic responses. Although i.vag. immunization induced local vaginal immunoglobulin A (IgA) and IgG antibody responses, these were not disseminated to a remote secretion, the saliva, and only modest levels of serum antibodies were generated. In contrast, i.n. immunization was substantially more effective at inducing IgA and IgG antibody responses in the genital tract and in the circulation, as well as at inducing IgA antibodies in the saliva. Moreover, mucosal and systemic antibodies induced by i.n. immunization persisted for at least 12 months. Analysis of the molecular form of genital IgA indicated that the majority of both total IgA and specific IgA antibody was polymeric, and likely derived from the common mucosal immune system.
The
Legionella pneumophila iraAB
Locus Is Required for Iron Assimilation, Intracellular Infection, and Virulence
Authors: Viswanathan V. K. , Edelstein Paul H. , Pope C. Dumais , Cianciotto Nicholas P. 
Published: July 2002

ABSTRACT

Legionella pneumophila
, a facultative intracellular parasite of human alveolar macrophages and protozoa, causes Legionnaires' disease. Using mini-Tn
10
mutagenesis, we previously isolated a
L. pneumophila
mutant that was hypersensitive to iron chelators. This mutant, NU216, and its allelic equivalent, NU216R, were also defective for intracellular infection, particularly in iron-deficient host cells. To determine whether NU216R was attenuated for virulence, we assessed its ability to cause disease in guinea pigs following intratracheal inoculation. NU216R-infected animals yielded 1,000-fold fewer bacteria from their lungs and spleen compared to wild-type-130b-infected animals that had received a 50-fold-lower dose. Moreover, NU216R-infected animals subsequently cleared the bacteria from these sites. While infection with 130b resulted in high fever, weight loss, and ruffled fur, inoculation with NU216R did not elicit any signs of disease. DNA sequence analysis revealed that the transposon insertion in NU216R lies in the first open reading frame of a two-gene operon. This open reading frame (
iraA
) encodes a 272-amino-acid protein that shows sequence similarity to methyltransferases. The second open reading frame (
iraB
) encodes a 501-amino-acid protein that is highly similar to di- and tripeptide transporters from both prokaryotes and eukaryotes. Southern hybridization analyses determined that the
iraAB
locus was largely limited to strains of
L. pneumophila
, the most pathogenic of the
Legionella
species. A newly derived mutant containing a targeted disruption of
iraB
showed reduced ability to grow under iron-depleted extracellular conditions, but it did not have an infectivity defect in the macrophage-like U937 cells. These data suggest that
iraA
is critical for virulence of
L. pneumophila
while
iraB
is involved in a novel method of iron acquisition which may utilize iron-loaded peptides.
Dominant Nonresponsiveness toHelicobacter pyloriInfection Is Associated with Production of Interleukin 10 but Not Gamma Interferon
Authors: Sutton Philip , Kolesnikow Tassia , Danon Stephen , Wilson John , Lee Adrian 
Published: July 2002

ABSTRACTHelicobacter pylori-induced gastritis is an essential precursor lesion for the development of peptic ulcers or gastric adenocarcinoma. We demonstrate that nonresponsiveness toH. pyloriSS1 infection is dominantly inherited in mice. F1hybrid crosses between a nonresponder mouse and three responder strains all possessed the nonresponder phenotype. Secretion of interleukin-10 but not gamma interferon was associated with nonresponsiveness to infection.
Diminished Diarrheal Response to
Vibrio cholerae
Strains Carrying the Replicative Form of the CTXΦ Genome instead of CTXΦ Lysogens in Adult Rabbits
Authors: Faruque Shah M. , Rahman M. Mostafizur , Hasan A. K. M. Mahbub , Nair G. Balakrish , Mekalanos John J. , Sack David A. 
Published: July 2002

ABSTRACT

Toxigenic
Vibrio cholerae
strains are lysogens of CTXΦ, a filamentous bacteriophage which encodes cholera toxin (CT). Following infection of recipient
V. cholerae
cells by CTXΦ, the phage genome either integrates into the host chromosome at a specific attachment site (
att
RS) or exists as a replicative-form (RF) plasmid. We infected naturally occurring
att
RS-negative nontoxigenic
V. cholerae
or attenuated (CTX
−
att
RS negative) derivatives of wild-type toxigenic strains with CTXΦ and examined the diarrheagenic potential of the strains carrying the RF of the CTXΦ genome using the adult rabbit diarrhea model. Under laboratory conditions, strains carrying the RF of CTXΦ produced more CT than corresponding lysogens as assayed by a G
M1
-based enzyme-linked immunosorbent assay and by fluid accumulation in ligated ileal loops of rabbits. However, when tested for diarrhea in rabbits, the
att
RS-negative strains (which carried the CTXΦ genome as the RF) were either negative or produced mild diarrhea, whereas the
att
RS-positive strains with integrated CTXΦ produced severe fatal diarrhea. Analysis of the strains after intestinal passage showed that the
att
RS-negative strains lost the phage genome at approximately a fivefold higher frequency than under in vitro conditions, and 75 to 90% of cells recovered from challenged rabbits after 24 h were CT negative. These results suggested that strains carrying the RF of CTXΦ are unable to cause severe disease due to rapid loss of the phage in vivo, and the gastrointestinal environment thus provides selection of toxigenic strains with an integrated CTXΦ genome. These results may have implications for the development of live
V. cholerae
vaccine candidates impaired in chromosomal integration of CTXΦ. These findings may also contribute to understanding of the etiology of diarrhea occasionally associated with nontoxigenic
V. cholerae
strains.
DNA Immunization byPlasmodium falciparumLiver-Stage Antigen 3 Induces Protection againstPlasmodium yoeliiSporozoite Challenge
Authors: Sauzet Jean-Pierre , Perlaza Blanca-Liliana , Brahimi Karima , Daubersies Pierre , Druilhe Pierre 
Published: July 2002

ABSTRACTDNA-based immunization of mice byPlasmodium falciparumliver-stage antigen 3 (PfLSA3), a novel highly conservedP. falciparumpreerythrocytic antigen, was evaluated. Animals developed a dominant Th1 immune response (high gamma interferon T-cell responses and predominance of immunoglobulin G2a) to each of three recombinant proteins spanning the molecule. We have exploited the immunological cross-reactivity of PfLSA3 with its putative homologue on sporozoites of the rodent parasitePlasmodium yoelii, and we show for the first time that responses induced by PfLSA3 in mice significantly protect against a heterologous challenge byP. yoeliisporozoites. These results support a significant effect of DNA-induced immune responses on preerythrocytic stages.