bluuebunny/crossref_metadata_2025_split huggingface dataset:
stx
1c
Is the Most Common Shiga Toxin 1 Subtype among Shiga Toxin-Producing
Escherichia coli
Isolates from Sheep but Not among Isolates from Cattle
Authors: Brett Kim N. , Ramachandran Vidiya , Hornitzky Michael A. , Bettelheim Karl A. , Walker Mark J. , Djordjevic Steven P. 
Published: March 2003

ABSTRACT

Unlike Shiga toxin 2 (
stx
2
) genes, most nucleotide sequences of Shiga toxin 1 (
stx
1
) genes from Shiga toxin-producing
Escherichia coli
(STEC),
Shigella dysenteriae
, and several bacteriophages (H19B, 933J, and H30) are highly conserved. Consequently, there has been little incentive to investigate variants of
stx
1
among STEC isolates derived from human or animal sources. However
stx
1OX3
, originally identified in an OX3:H8 isolate from a healthy sheep in Germany, differs from other
stx
1
subtypes by 43 nucleotides, resulting in changes to 12 amino acid residues, and has been renamed
stx
1c
. In this study we describe the development of a PCR-restriction fragment length polymorphism (RFLP) assay that distinguishes
stx
1c
from other
stx
1
subtypes. The PCR-RFLP assay was used to study 378
stx
1
-containing STEC isolates. Of these, 207 were isolated from sheep, 104 from cattle, 45 from humans, 11 from meat, 5 from swine, 5 from unknown sources, and 1 from a cattle water trough. Three hundred fifty-five of the 378 isolates (93.9%) also possessed at least one other associated virulence gene (
ehxA
,
eaeA
, and/or
stx
2
); the combination
stx
1
,
stx
2
, and
ehxA
was the most common (175 of 355 [49.3%]), and 90 of 355 (25.4%) isolates possessed
eaeA
. One hundred thirty-six of 207 (65.7%) ovine isolates possessed
stx
1c
alone and belonged to 41 serotypes. Seventy-one of 136 (52.2%) comprised the common ovine serotypes O5:H
−
, O128:H2, and O123:H
−
. Fifty-two of 207 isolates (25.1%) possessed an
stx
1
subtype; 27 (51.9%) of these belonged to serotype O91:H
−
. Nineteen of 207 isolates (9.2%) contained both
stx
1c
and
stx
1
subtypes, and 14 belonged to serotype O75:H8. In marked contrast, 97 of 104 (93.3%) bovine isolates comprising 44 serotypes possessed an
stx
1
subtype, 6 isolates possessed
stx
1c
, and the remaining isolate possessed both
stx
1c
and
stx
1
subtypes. Ten of 11 (91%) isolates cultured from meat in New Zealand possessed
stx
1c
(serotypes O5:H
−
, O75:H8/H40, O81:H26, O88:H25, O104:H
−
/H7, O123:H
−
/H10, and O128:H2); most of these serotypes are commonly recovered from the feces of healthy sheep. Serotypes containing
stx
1
recovered from cattle rarely were the same as those isolated from sheep. Although an
stx
1c
subtype was never associated with the typical enterohemorrhagic
E. coli
serogroups O26, O103, O111, O113, and O157, 13 human isolates possessed
stx
1c
. Of these, six isolates with serotype O128:H2 (from patients with diarrhea), four O5:H
−
isolates (from patients with hemolytic-uremic syndrome), and three isolates with serotypes O123:H
−
(diarrhea), OX3:H8 (hemolytic-uremic syndrome), and O81:H6 (unknown health status) represent serotypes that are commonly isolated from sheep.
Epidemiologic Analysis of Invasive and Noninvasive Group A Streptococcal Isolates in Hong Kong
Authors: Ho P. L. , Johnson D. R. , Yue A. W. Y. , Tsang D. N. C. , Que T. L. , Beall B. , Kaplan E. L. 
Published: March 2003

ABSTRACT

Since the mid-1980s, there has been a resurgence of severe forms of invasive group A streptococcal (GAS) disease in many Western countries. In Hong Kong, a similar increase has also been observed in recent years. One hundred seven GAS isolates collected from 1995 to 1998 from individuals with necrotizing fasciitis, toxic shock syndrome, meningitis, or other type of bacteremic sepsis (invasive group,
n
= 24) as well as from individuals with minor skin and throat infections (noninvasive group,
n
= 83) were characterized through serologic and/or
emm
sequence typing. Thirty-two M protein gene sequence types were identified. Types M1, M4, and M12 were the most prevalent in both the invasive group and the noninvasive group; together they accounted for 70.8 and 37.3% of the isolates, respectively. No clear pattern of skin and throat infection M types was observed. Type M1 was overrepresented in the invasive and pharyngeal isolates. The same pulsed-field gel electrophoresis pattern was shared by most invasive and all pharyngeal M1 isolates. Overall, resistance to erythromycin (32%) and tetracycline (53%) was high, but M1 isolates were significantly less likely to have resistance to either antimicrobial agent than non-M1 isolates. One novel
emm
sequence type,
stHK
, was identified in an isolate from a patient with necrotizing fasciitis. Minor
emm
gene sequence alterations were noted for 31 isolates, and for 13 of these isolates, deletion, insertion, or point mutations were seen in the hypervariable 50 N-terminal residues.
Competitive Enzyme-Linked Immunosorbent Assay Based on Monoclonal Antibody and Recombinant Hemagglutinin for Serosurveillance of Rinderpest Virus
Authors: Renukaradhya G. J. , Suresh K. B. , Rajasekhar M. , Shaila M. S. 
Published: March 2003

ABSTRACT
A competitive enzyme-linked immunosorbent assay (C-ELISA) which detects antibodies unique to rinderpest virus (RPV) has been developed. This test can differentiate antibodies against RPV and those against peste des petits ruminants virus. The recombinant RPV hemagglutinin (H)-protein C-ELISA (recH C-ELISA) is based on the ability of a well-characterized monoclonal antibody (MAb) produced with the soluble, secreted form of the H protein (Sec H protein) of RPV made in a baculovirus expression system to compete with the binding of RPV antibodies in the serum of vaccinated or infected, recovered animals to the Sec H protein. The B-cell epitope recognized by the MAb corresponds to amino acids 575 to 583 on the H protein, which is not present on the antigenically closely related peste des petits ruminants virus hemagglutinin-neuraminidase protein. Initially, a positive-negative threshold cutoff value for percent inhibition of 34 was established with 500 known RPV-negative serum samples. The recH C-ELISA was developed with the enzyme immunoassay software of a commercial RPV C-ELISA kit. Comparative analysis of the test results for 700 serum samples obtained with the commercial kit gave a sensitivity of 112.4% and a specificity of 72.4%. Variations in percent inhibition values were observed for the two assay systems. These variations may have been due to the undefined amount of antigen present in the commercial kit as well as the use of a different MAb. The recH C-ELISA detected more positive serum samples compared to the number detected by the commercial kit, with the results confirmed by a virus neutralization test. Thus, recH C-ELISA is a sensitive tool for RPV serosurveillance in disease eradication programs.
Cost-Effectiveness Analysis of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test as Used Routinely on Smear-Positive Respiratory Specimens
Authors: Dowdy David W. , Maters Amelia , Parrish Nicole , Beyrer Christopher , Dorman Susan E. 
Published: March 2003

ABSTRACT

A decision analysis was conducted to evaluate the cost-effectiveness of programs in which the Amplified Mycobacterium Tuberculosis Direct test (MTD) (Gen-Probe) is used to rapidly exclude
Mycobacterium tuberculosis
complex as a cause of disease in smear-positive respiratory specimens. MTD sensitivity, specificity, and probability of inhibition for smear-positive specimens were estimated from literature reports. Costs and laboratory performance characteristics were determined from review of records and practices at an urban hospital in the mid-Atlantic United States. In the base case, 31.4% of smear-positive specimens were assumed to be culture positive for
M. tuberculosis
. Under these conditions, the marginal cost of the MTD testing program was estimated as $338 per smear-positive patient, or $494 per early exclusion of tuberculosis based on negative MTD results. By comparison, the cost of respiratory isolation ($27.77/day) and drugs ($5.66/day) averted by MTD testing was estimated at $201 per early tuberculosis exclusion. MTD testing was therefore not cost-effective in this scenario. Sensitivity analysis revealed that cost-effectiveness estimates are sensitive to the number of smear-positive specimens processed annually, the relative prevalence of
M. tuberculosis
in smear-positive specimens, and the marginal daily cost of respiratory isolation. A decision tool is therefore presented for assessing the cost-effectiveness of MTD under various combinations of those three variables. While routine MTD testing of smear-positive specimens is not expected to be cost-saving for most individual hospitals, centralized reference laboratories may be able to implement MTD in a cost-effective manner across a wide range of situations.
Use of Fourier-Transform Infrared Spectroscopy for Typing of
Candida
albicans
Strains Isolated in Intensive Care Units
Authors: Sandt C. , Sockalingum G. D. , Aubert D. , Lepan H. , Lepouse C. , Jaussaud M. , Leon A. , Pinon J. M. , Manfait M. , Toubas D. 
Published: March 2003

ABSTRACT

Comparative studies of
Candida
albicans
strains are essential for proving cross-infections in epidemiological investigations. Typing of
C
.
albicans
strains is mainly based on genotypic methods. Fourier-transform infrared (FTIR) spectroscopy is described in this study as a novel phenotypic approach to the typing of
C
.
albicans
. The first step in the approach was the standardization of sample preparation (culture conditions and sampling parameters) and acquisition and classification parameters (spectral acquisition, spectral window selection, classification algorithm, and heterogeneity threshold). The second step consisted of validating the established parameters with a set of 79 strains of
C
.
albicans
isolated over 4 months from nine patients hospitalized in two intensive care units. Strains were isolated from multiple anatomical sites with repeated sampling. FTIR spectroscopy results were compared to randomly amplified polymorphic DNA (RAPD) results; this analysis showed that the amplification patterns of strains isolated from a given patient were identical and that different patients had different profiles. FTIR spectroscopy data were analyzed by hierarchical clustering performed with the second-derivative spectra. This classification revealed nine groups, one per patient. Only one spectrum out of 79 was misclassified by the FTIR spectroscopy method. RAPD and FTIR spectroscopy results were in good agreement, showing that, when nosocomial candidiasis transmission is suspected and urgent information is needed, this technique may be useful as a quick identification tool to give solid clues before confirmation by a genotypic method.
Interaction between Porcine Reproductive-Respiratory Syndrome Virus and Bacterial Endotoxin in the Lungs of Pigs: Potentiation of Cytokine Production and Respiratory Disease
Authors: Van Gucht Steven , Van Reeth Kristien , Pensaert Maurice 
Published: March 2003

ABSTRACTPorcine reproductive-respiratory syndrome virus (PRRSV) is a key agent in multifactorial respiratory disease of swine. Intratracheal administration of bacterial lipopolysaccharides (LPSs) to PRRSV-infected pigs results in markedly enhanced respiratory disease, whereas the inoculation of each component alone results in largely subclinical disease. This study examines whether PRRSV-LPS-induced respiratory disease is associated with the excessive production of proinflammatory cytokines in the lungs. Gnotobiotic pigs were inoculated intratracheally with PRRSV and then with LPS at 3, 5, 7, 10, or 14 days of infection and euthanatized 6 h after LPS inoculation. Controls were inoculated with PRRSV or LPS only or with phosphate-buffered saline. Virus titers, (histo)pathological changes in the lungs, numbers of inflammatory cells, and bioactive tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), and IL-6 levels in bronchoalveolar lavage fluids were examined. All pigs inoculated with PRRSV-LPS developed severe respiratory disease, whereas the controls that were inoculated with PRRSV or LPS alone did not. PRRSV infection significantly enhanced cytokine production in response to LPS. Peak TNF-α, IL-1, and IL-6 titers were 10 to 100 times higher in the PRRSV-LPS-inoculated pigs than in the pigs inoculated with PRRSV or LPS alone; and the titers correlated with the respiratory signs. The levels of neutrophil infiltration and the pathological changes detected in the lungs of PRRSV-LPS-inoculated pigs resembled those detected when the effects of PRRSV and LPS inoculated alone are combined, but with no synergistic effects between PRRSV and LPS. These data demonstrate a synergism between PRRSV and LPS in the induction of proinflammatory cytokines and an association between induction of these cytokines and disease.
Blastocystis
Isolates from a Pig and a Horse Are Closely Related to
Blastocystis hominis
Authors: Thathaisong Umaporn , Worapong Jeerapun , Mungthin Mathirut , Tan-Ariya Peerapan , Viputtigul Kwanjai , Sudatis Apichart , Noonai Adisak , Leelayoova Saovanee 
Published: March 2003

ABSTRACT

Blastocystis
has a widespread distribution in a variety of animals, which is a potential source of infection for humans. However, the contribution of zoonotic transmission remains unclear due to the absence of molecular proof of these organisms being identical to those found in humans. We report herein the similar subgroup of
Blastocystis
isolates from humans, pigs, and a horse using a restriction fragment length polymorphism (RFLP) analysis of partial small-subunit ribosomal DNA (ssu rDNA). Additionally, sequence and phylogenic analysis of partial ssu rDNA of
Blastocystis
from a human, a pig, and a horse sharing a common subgroup shows that
Blastocystis
isolates from a pig and a horse were monophyletic and closely related to
B. hominis
, with 92 to 94% identity. These results suggest the possibility of zoonotic potential of
Blastocystis
.
Heterogeneity of
cag
Genotypes in
Helicobacter
pylori
Isolates from Human Biopsy Specimens
Authors: Tomasini Maria Luisa , Zanussi Stefania , Sozzi Michele , Tedeschi Rosamaria , Basaglia Giancarlo , De Paoli Paolo 
Published: March 2003

ABSTRACT

The
Helicobacter
pylori
chromosomal cluster of genes known as the cytotoxin-associated gene (
cag
) island may have different compositions in infecting strains. In this study, we analyzed 150 single colonies obtained from gastric biopsy specimens from 10 patients infected with
cagA
-positive
H
.
pylori
strains and sweep isolates (isolates harvested with sweep in different points of the plate) from 6 patients infected with
cagA
-negative strains. Three loci in the
cag
island (
cagA
,
cagE
, and
virB11
) and the conserved gene
glmM
(
ureC
) were investigated by PCR. The levels of anti-
H
.
pylori
and anti-CagA antibodies in patient sera were also measured. For subjects infected with
cagA
-negative strains, all sweep isolates were also negative for
cagE
and
virB11
, suggesting the complete absence of the
cag
island. For subjects infected with
cagA
-positive strains, most of the isolates were positive for all three genes studied, whereas 24.7% of the isolates had a partial or total deletion of the
cag
island.
cagA
,
cagE
, and
virB11
were, respectively, present in 87.3, 77.3, and 90% of the colonies. The deletion of
virB11
was always associated with the deletion of
cagA
and/or
cagE
.
H
.
pylori
colonies with different
cag
genotypes were isolated within a single gastric biopsy specimen from 3 of the 10 patients and were further characterized by random amplified polymorphic DNA (RAPD) analysis and by sequencing of an arbitrarily selected gene segment. Although the colonies had different
cag
genotypes, their RAPD profiles were highly similar within each patient, and the nucleotide sequences of the selected gene segment were identical. All of the patients had detectable antibodies against
H
.
pylori
, and 9 of 10 had anti-CagA antibodies. In conclusion, we show that a single infecting
H
.
pylori
strain may include variable proportions of colony subtypes with different
cag
genotypes. The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between
cag
genotypes and clinical outcomes of
H
.
pylori
infections.
Molecular Epidemiological Analysis of
Cryptosporidium
Isolates from Humans and Animals by Using a Heteroduplex Mobility Assay and Nucleic Acid Sequencing Based on a Small Double-Stranded RNA Element
Authors: Leoni Francesca , Gallimore Chris I. , Green Jonathan , McLauchlin Jim 
Published: March 2003

ABSTRACT

Two extrachromosomal double-stranded RNA (dsRNA) elements occur in
Cryptosporidium
parvum
. A heteroduplex mobility assay (HMA) was developed for the rapid characterization of sequence diversity in a 173-bp fragment of the small dsRNA element of
Cryptosporidium
with either a natural sequence from
Cryptosporidium
meleagridis
or a synthetic sequence as reference DNA. The 173-bp fragment was generated from 265 samples of whole feces (242 from humans and 18 from livestock with
C
.
parvum
genotype 1 or 2, 4 from humans with
Cryptosporidium
felis
, and 1 from a human with
C
.
meleagridis
). The HMA method identified 21 patterns in
C
.
parvum
(8 in genotype 1, 12 in genotype 2, and a type common to both genotypes), 4 patterns in
C
.
felis
, and 1 pattern in
C
.
meleagridis
. All patterns were confirmed as distinct by DNA sequencing. For genotype 1, a single HMA type was found in 89% of samples: 64 of 65 cases from three waterborne outbreaks, all 16 cases from eight intrafamilial outbreaks, and 17 of 28 sporadic cases. Among the remaining 11 sporadic cases due to genotype 1, seven other HMA types were detected. For genotype 2, a single HMA type was found in 72% of samples: 36 of 43 cases from three waterborne outbreaks, 11 of 15 cases from seven intrafamilial outbreaks, 44 of 75 sporadic cases, and all 18 samples from livestock. Within the intrafamilial outbreaks, two other HMA types were identified: the same HMA type was detected in samples from cases within the same outbreak. Among the sporadic cases due to genotype 2, 10 additional HMA types were detected.
Rapid Detection of
rpoB
Gene Mutations in Rifampin-Resistant
Mycobacterium tuberculosis
Isolates in Shanghai by Using the Amplification Refractory Mutation System
Authors: Fan Xiao-Yong , Hu Zhong-Yi , Xu Fan-Hong , Yan Zhi-Qiang , Guo Sheng-Qi , Li Zhong-Ming 
Published: March 2003

ABSTRACT

Rapid detection of drug resistance in
Mycobacterium tuberculosis
is essential for efficient treatment and control of this pathogen. The amplification refractory mutation system (ARMS) was used to detect mutations in the rifampin resistance-determining region of the
rpoB
gene. A total of 39 rifampin-resistant
M. tuberculosis
isolates in Shanghai were analyzed by this assay, resulting in 92.3% sensitivity (36 of 39) and 87.2% concordance (34 of 39) relative to DNA sequencing, by which 41 mutations of 11 different types, including 9 point mutations and 2 deletions, were identified in the
rpoB
gene. The most frequent mutations were those associated with codon 531 (21 of 39 [53.8%]) and codon 526 (9 of 39 [23.1%]). The results suggest that the ARMS assay is rapid and simple to implement and could be performed for detection of rifampin resistance in
M. tuberculosis
to complement conventional culture-based methods.
Performance Characteristics of Human Immunodeficiency Virus Type 1 (HIV-1) Genotyping Systems in Sequence-Based Analysis of Subtypes Other than HIV-1 Subtype B
Authors: Jagodzinski Linda L. , Cooley John D. , Weber Mark , Michael Nelson L. 
Published: March 2003

ABSTRACT

Given the diversity of human immunodeficiency virus type 1 (HIV-1) subtypes and the emergence of subtypes other than HIV-1 subtype B in the United States, genotypic assays must be capable of delivering sequence data on diverse HIV-1 subtypes. We evaluated the performance of Visible Genetics TRUGENE
HIV-1
genotyping kit and Applied Biosystems ViroSeq HIV-1 genotyping system on a panel of 34 well-characterized HIV-1 viral stocks (subtypes A through H). Both assays perform well on diverse HIV-1 subtypes despite being designed for HIV-1 subtype B. The TRUGENE assay produced sequence data for 31 isolates but not for one C and two G isolates. The TRUGENE assay using prototype 1.5 RT-PCR primers and the ViroSeq assay were both successful for all variants tested, although five isolates lacked double-strand sequence coverage in the ViroSeq assay. The availability of standardized HIV-1 genotyping kits that perform reliably with all HIV subtypes will facilitate broad implementation of HIV-1 resistance testing.
NUMERICAL SIMULATION OF THE VAPOR FILM COLLAPSE BEHAVIOR AT VAPOR EXPLOSION WITH THREE-DIMENSIONAL LATTICE GAS THERMAL-HYDRAULIC AUTOMATA METHOD
Authors: TOCHIO DAISUKE , ABE YUTAKA , MATSUKUMA YOSUKE , NARIAI HIDEKI 
Published: March 2003

In order to clarify the dominant driving force of complex vapor film collapse behavior, numerical simulation is performed with three-dimensional fifteen-velocity lattice gas automata method. As the result, numerical result is qualitatively different from the experimental result. On the other hand, numerical simulation of vapor film collapse behavior is performed with three-dimensional fifteen-velocity lattice gas automata method including phase-change effect. As the result, numerical result is qualitatively similar to the experimental results. Comparison between the experimental result and the numerical result confirms that experimentally observed vapor film collapse behavior is dominated not by fluid motion but by phase change.
Is Breakdown of the Blood-Brain Barrier Responsible for Lacunar Stroke, Leukoaraiosis, and Dementia?
Authors: Wardlaw J.M. , Sandercock P.A.G. , Dennis M.S. , Starr J. 
Published: March 2003

Background—The pathogenesis of and relationship between small deep (lacunar) infarcts, cerebral white matter disease (leukoaraiosis or white matter hyperintensities), and progressive cognitive impairment or dementia are much debated.Summary of Comment—We hypothesize that cerebral small-vessel endothelial (ie, blood-brain barrier) dysfunction, with leakage of plasma components into the vessel wall and surrounding brain tissue leading to neuronal damage, may contribute to the development of 3 overlapping and disabling cerebrovascular conditions: lacunar stroke, leukoaraiosis, and dementia. This hypothesis could explain the link between ischemic cerebral small-vessel disease and several apparently clinically distinct dementia syndromes. This hypothesis is supported by pathological, epidemiological, and experimental studies in lacunar stroke and leukoaraiosis and observations on the blood-brain barrier with MRI. We suspect that the potential significance of blood-brain barrier failure as a pathogenetic step linking vascular disease with common, disabling brain diseases of insidious onset has been overlooked. For example, lipohyalinosis, which has a pathological appearance of uncertain origin and is possibly responsible for some discrete lacunar infarcts, may be one end of a clinical spectrum of illness manifested by blood-brain barrier failure.Conclusions—Proof that blood-brain barrier failure is key to these conditions could provide a target for new treatments to reduce the effects of vascular disease on the brain and prevent cognitive decline and dementia.