bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of Macrolide Resistance in Clinical Group B Streptococci Isolated in France
Authors: Fitoussi Frederic , Loukil Chawki , Gros Isabelle , Clermont Olivier , Mariani Patricia , Bonacorsi Stephane , Le Thomas Isabelle , Deforche Dominique , Bingen Edouard 
Published: July 2002

ABSTRACT

Macrolide susceptibility was investigated in clinical group B streptococci obtained from neonates or pregnant women in 2000 in France. Of 490 consecutive isolates, 18% were resistant to erythromycin. The
erm
(B),
erm
(A) subclass
erm
(TR), and
mef
(A) genes were harbored by 47, 45, and 6% of these strains, respectively. Two isolates did not harbor
erm
or
mef
genes.
Interference between D30N and L90M in Selection and Development of Protease Inhibitor-Resistant Human Immunodeficiency Virus Type 1
Authors: Sugiura Wataru , Matsuda Zene , Yokomaku Yoshiyuki , Hertogs Kurt , Larder Brendan , Oishi Tsuyoshi , Okano Aiko , Shiino Teiichirou , Tatsumi Masashi , Matsuda Masakazu , Abumi Hanae , Takata Noboru , Shirahata Satoshi , Yamada Kaneo , Yoshikura Hiroshi , Nagai Yoshiyuki 
Published: July 2002

ABSTRACT

We studied the evolutionary relationships between the two protease inhibitor (PI) resistance mutations, D30N and L90M, of human immunodeficiency virus type 1 (HIV-1). The former is highly specific for nelfinavir resistance, while the latter is associated with resistance to several PIs, including nelfinavir. Among patients with nelfinavir treatment failure, we found that D30N acquisition was strongly suppressed when L90M preexisted. Thus, D30N/L90M double mutations not only were detected in a very limited number of patients but also accounted for a minor fraction within each patient. In the disease course, the D30N and L90M clones readily evolved independently of each other, and later the D30N/L90M double mutants emerged. The double mutants appeared to originate from the D30N lineage but not from the L90M lineage, or were strongly associated with the former. However, their evolutionary pathways appeared to be highly complex and to still have something in common, as they always contained several additional polymorphisms, including L63P and N88D, as common signatures. These results suggest that D30N and L90M are mutually exclusive during the evolutionary process. Supporting this notion, the D30N/L90M mutation was also quite rare in a large clinical database. Recombinant viruses with the relevant mutations were generated and compared for the ability to process p55

gag

and p160

pol

precursor proteins as well as for their infectivity. L90M caused little impairment of the cleavage activities, but D30N was detrimental, although significant residual activity was observed. In contrast, D30N/L90M demonstrated severe impairment. Thus, the concept of mutual antagonism of the two mutations was substantiated biochemically and functionally.
Evolution of Primary Protease Inhibitor Resistance Mutations during Protease Inhibitor Salvage Therapy
Authors: Kantor Rami , Fessel W. Jeffrey , Zolopa Andrew R. , Israelski Dennis , Shulman Nancy , Montoya Jose G. , Harbour Michael , Schapiro Jonathan M. , Shafer Robert W. 
Published: July 2002

ABSTRACTIn order to track the evolution of primary protease inhibitor (PI) resistance mutations in human immunodeficiency virus type 1 (HIV-1) isolates, baseline and follow-up protease sequences were obtained from patients undergoing salvage PI therapy who presented initially with isolates containing a single primary PI resistance mutation. Among 78 patients meeting study selection criteria, baseline primary PI resistance mutations included L90M (42% of patients), V82A/F/T (27%), D30N (21%), G48V (6%), and I84V (4%). Despite the switching of treatment to a new PI, primary PI resistance mutations present at the baseline persisted in 66 of 78 (85%) patients. D30N persisted less frequently than L90M (50% versus 100%, respectively;P< 0.001) and V82A/F/T (50% versus 81%, respectively;P= 0.05). HIV-1 isolates from 38 (49%) patients failing PI salvage therapy developed new primary PI resistance mutations including L90M, I84V, V82A, and G48V. Common combinations of primary and secondary PI resistance mutations after salvage therapy included mutations at amino acid positions 10, 82, and 46 and/or 54 in 16 patients; 10, 90, and 71 and/or 73 in 14 patients; 10, 73, 84, 90, and 46 and/or 54 in 5 patients; 10, 48, and 82 in 5 patients; and 30, 88 and 90 in 5 patients. In summary, during salvage PI therapy, most HIV-1 isolates with a single primary PI resistance mutation maintained their original mutations, and 49% developed additional primary PI resistance mutations. The persistence of L90M, V82A/F/T, G48V, and I84V during salvage therapy suggests that these mutations play a role in clinical resistance to multiple PIs.
Hemofiltrate CC Chemokine 1[9-74] Causes Effective Internalization of CCR5 and Is a Potent Inhibitor of R5-Tropic Human Immunodeficiency Virus Type 1 Strains in Primary T Cells and Macrophages
Authors: Münch Jan , Ständker Ludger , Pöhlmann Stefan , Baribaud Frédéric , Papkalla Armin , Rosorius Olaf , Stauber Roland , Sass Gabriele , Heveker Nikolaus , Adermann Knut , Escher Sylvia , Klüver Enno , Doms Robert W. , Forssmann Wolf-Georg , Kirchhoff Frank 
Published: July 2002

ABSTRACTProteolytic processing of the abundant plasmatic human CC chemokine 1 (HCC-1) generates a truncated form, HCC-1[9-74], which is a potent agonist of CCR1, CCR3, and CCR5; promotes calcium influx and chemotaxis of T lymphoblasts, monocytes, and eosinophils; and inhibits infection by CCR5-tropic human immunodeficiency virus type 1 (HIV-1) isolates. In the present study we demonstrate that HCC-1[9-74] interacts with the second external loop of CCR5 and inhibits replication of CCR5-tropic HIV-1 strains in both primary T cells and monocyte-derived macrophages. Low concentrations of the chemokine, however, frequently enhanced the replication of CCR5-tropic HIV-1 isolates but not the replication of X4-tropic HIV-1 isolates. Only HCC-1[9-74] and HCC-1[10-74], but not other HCC-1 length variants, displayed potent anti-HIV-1 activities. Fluorescence-activated cell sorter analysis revealed that HCC-1[9-74] caused up to 75% down-regulation of CCR5 cell surface expression, whereas RANTES (regulated on activation, normal T-cell expressed and secreted) achieved a reduction of only about 40%. Studies performed with green fluorescent protein-tagged CCR5 confirmed that both HCC-1[9-74] and RANTES, but not full-length HCC-1, mediated specific internalization of the CCR5 HIV-1 entry cofactor. Our results demonstrate that the interaction with HCC-1[9-74] causes effective intracellular sequestration of CCR5, but they also indicate that the effect of HCC-1[9-74] on viral replication is subject to marked cell donor- and HIV-1 isolate-dependent variations.
Molecular Mechanisms of Fluconazole Resistance in
Candida dubliniensis
Isolates from Human Immunodeficiency Virus-Infected Patients with Oropharyngeal Candidiasis
Authors: Perea Sofia , López-Ribot José L. , Wickes Brian L. , Kirkpatrick William R. , Dib Olga P. , Bachmann Stefano P. , Keller Suzanne M. , Martinez Marcos , Patterson Thomas F. 
Published: July 2002

ABSTRACT

Candida dubliniensis
is a newly identified species of
Candida
that is phenotypically similar to but genetically distinct from
C. albicans
. This organism has been recovered with increasing frequency from the oral cavities of human immunodeficiency virus (HIV)-infected and AIDS patients and has been implicated as a causative agent of oral candidiasis and systemic disease. In the present study we characterized the molecular mechanisms of resistance to fluconazole (FLC) in
C. dubliniensis
clinical isolates from two different HIV-infected patients with oropharyngeal candidiasis. Isolates were identified to the species level by phenotypic and genotypic tests. DNA-typing techniques were used to assess strain identity. Antifungal susceptibility testing was performed by NCCLS techniques. Northern blotting analysis was used to monitor the expression of genes encoding lanosterol demethylase (
ERG11
) and efflux transporters (
CDR
and
MDR1
) in matched sets of
C. dubliniensis
-susceptible and -resistant isolates by using probes generated from their homologous
C. albicans
sequences. In addition,
ERG11
genes were amplified by PCR, and their nucleotide sequences were determined in order to detect point mutations with a possible effect in the affinity for azoles. Decreasing susceptibilities to FLC were detected in
C. dubliniensis
isolates recovered from both patients during the course of treatment. FLC-resistant
C. dubliniensis
isolates from one patient demonstrated combined upregulation of the
MDR1
,
CDR1
, and
ERG11
genes. Among the isolates from the second patient, all isolates showing decreased susceptibility to FLC demonstrated upregulation of
MDR1
, whereas the levels of mRNA for the
ERG11
genes remained constant and the expression of
CDR
genes was negligible. Fourteen point mutations were found in the
ERG11
genes of the isolates with decreased susceptibility to FLC. These data demonstrate that the development of azole resistance in
C. dublinensis
clinical isolates from HIV-infected patients treated with FLC is mediated by multiple molecular mechanisms of resistance, similar to the observations found in the case of
C. albicans
.
Potent In Vivo Antiviral Activity of the Herpes Simplex Virus Primase-Helicase Inhibitor BAY 57-1293
Authors: Betz Ulrich A. K. , Fischer Rüdiger , Kleymann Gerald , Hendrix Martin , Rübsamen-Waigmann Helga 
Published: July 2002

ABSTRACT
BAY 57-1293 belongs to a new class of antiviral compounds and inhibits replication of herpes simplex virus (HSV) type 1 and type 2 in the nanomolar range in vitro by abrogating the enzymatic activity of the viral primase-helicase complex. In various rodent models of HSV infection the antiviral activity of BAY 57-1293 in vivo was found to be superior compared to all compounds currently used to treat HSV infections. The compound shows profound antiviral activity in murine and rat lethal challenge models of disseminated herpes, in a murine zosteriform spread model of cutaneous disease, and in a murine ocular herpes model. It is active in parenteral, oral, and topical formulations. BAY 57-1293 continued to demonstrate efficacy when the onset of treatment was initiated after symptoms of herpetic disease were already apparent.
Genetic Analysis of Type E Botulinum Toxin-Producing
Clostridium butyricum
Strains
Authors: Wang Xingmin , Maegawa Tsuneo , Karasawa Tadahiro , Kozaki Shunji , Tsukamoto Kentaro , Gyobu Yotaku , Yamakawa Kiyotaka , Oguma Keiji , Sakaguchi Yoshihiko , Nakamura Shinichi 
Published: July 2002

ABSTRACT

Type E botulinum toxin (BoNT/E)-producing
Clostridium butyricum
strains isolated from botulism cases or soil specimens in Italy and China were analyzed by using nucleotide sequencing of the
bont
/E gene, random amplified polymorphic DNA (RAPD) assay, pulsed-field gel electrophoresis (PFGE), and Southern blot hybridization for the
bont
/E gene. Nucleotide sequences of the
bont
/E genes of 11 Chinese isolates and of the Italian strain BL 6340 were determined. The nucleotide sequences of the
bont
/E genes of 11
C. butyricum
isolates from China were identical. The deduced amino acid sequence of BoNT/E from the Chinese isolates showed 95.0 and 96.9% identity with those of BoNT/E from
C. butyricum
BL 6340 and
Clostridium botulinum
type E, respectively. The BoNT/E-producing
C. butyricum
strains were divided into the following three clusters based on the results of RAPD assay, PFGE profiles of genomic DNA digested with
Sma
I or
Xho
I, and Southern blot hybridization: strains associated with infant botulism in Italy, strains associated with food-borne botulism in China, and isolates from soil specimens of the Weishan lake area in China. A DNA probe for the
bont
/E gene hybridized with the nondigested chromosomal DNA of all toxigenic strains tested, indicating chromosomal localization of the
bont
/E gene in
C. butyricum
. The present results suggest that BoNT/E-producing
C. butyricum
is clonally distributed over a vast area.
Genetic Variation among Endosymbionts of Widely Distributed Vestimentiferan Tubeworms
Authors: Di Meo Carol A. , Wilbur Ami E. , Holben William E. , Feldman Robert A. , Vrijenhoek Robert C. , Cary S. Craig 
Published: July 2002

ABSTRACT
Vestimentiferan tubeworms thriving in sulfidic deep-sea hydrothermal vents and cold seeps are constrained by their nutritional reliance on chemoautotrophic endosymbionts. In a recent phylogenetic study using 16S ribosomal DNA, we found that endosymbionts from vent and seep habitats form two distinct clades with little variation within each clade. In the present study, we used two different approaches to assess the genetic variation among biogeographically distinct vestimentiferan symbionts. DNA sequences were obtained for the noncoding, internal transcribed spacer (ITS) regions of the rRNA operons of symbionts associated with six different genera of vestimentiferan tubeworms. ITS sequences from endosymbionts of host genera collected from different habitats and widely distributed vent sites were surprisingly conserved. Because the ITS region was not sufficient for distinguishing endosymbionts from different habitats or locations, we used a DNA fingerprinting technique, repetitive-extragenic-palindrome PCR (REP-PCR), to reveal differences in the distribution of repetitive sequences in the genomes of the bacterial endosymbionts. Most of the endosymbionts displayed unique REP-PCR patterns. A cladogram generated from these fingerprints reflected relationships that may be influenced by a variety of factors, including host genera, geographic location, and bottom type.
Simultaneous Detection and Differentiation of
Escherichia coli
Populations from Environmental Freshwaters by Means of Sequence Variations in a Fragment of the β-
d
-Glucuronidase Gene
Authors: Farnleitner Andreas H. , Kreuzinger Norbert , Kavka Gerhard G. , Grillenberger Sonja , Rath Johannes , Mach Robert L. 
Published: July 2002

ABSTRACT

A PCR-based denaturing-gradient gel electrophoresis (DGGE) approach was applied to a partial sequence of the β-
d
-glucuronidase gene (
uidA
) for specific detection and differentiation of
Escherichia coli
populations according to their
uidA
sequence variations. Detection of sequence variations by PCR-DGGE and by PCR with direct sequencing correlated perfectly. Screening of 50
E. coli
freshwater isolates and reference strains revealed 11 sequence types, showing nine polymorphic sites and an average number of pairwise differences between alleles of the
uidA
gene fragments (screened fragment length, 126 bp) of 2.3%. Among the analyzed strains a range of dominating to more rarely and/or uniquely observed
E. coli
sequence types was revealed. PCR-DGGE applied to fecally polluted river water samples simultaneously detected
E. coli
and generated a fingerprint of the mixed populations by separating the polymorphic
uidA
amplicons. No significant differences between non-cultivation-based and cultivation-based profiles were observed, suggesting that at least some members of all occurring sequence types could be cultivated. As
E. coli
is frequently used as a fecal indicator, this work is considered an important step towards a new, practical tool for the differentiation and tracing of fecal pollution in all kinds of waters.
Use of a Single, Triplicate Arbitrarily Primed-PCR Procedure for Molecular Fingerprinting of Lactic Acid Bacteria
Authors: Cusick Sean M. , O'Sullivan Daniel J. 
Published: July 2002

ABSTRACT

Arbitrarily primed (AP)-PCR can be used to generate characteristic DNA fingerprint patterns. However, small changes in reaction conditions can cause band irreproducibility. In this study, a single methodology encompassing triplicate reactions, which were intentionally exposed to three different annealing temperatures, enabled bands that were reproducibly generated to be recognized. A single triplicate AP-PCR (TAP-PCR) procedure, using an 18-mer primer, was developed and used to fingerprint representative isolates from the major genera of lactic acid bacteria and
Bifidobacterium
to the strain level.
Use of Repetitive DNA Sequences and the PCR To Differentiate
Escherichia coli
Isolates from Human and Animal Sources
Authors: Dombek Priscilla E. , Johnson LeeAnn K. , Zimmerley Sara T. , Sadowsky Michael J. 
Published: July 2002

ABSTRACT

The rep-PCR DNA fingerprint technique, which uses repetitive intergenic DNA sequences, was investigated as a way to differentiate between human and animal sources of fecal pollution. BOX and REP primers were used to generate DNA fingerprints from
Escherichia coli
strains isolated from human and animal sources (geese, ducks, cows, pigs, chickens, and sheep). Our initial studies revealed that the DNA fingerprints obtained with the BOX primer were more effective for grouping
E. coli
strains than the DNA fingerprints obtained with REP primers. The BOX primer DNA fingerprints of 154
E. coli
isolates were analyzed by using the Jaccard band-matching algorithm. Jackknife analysis of the resulting similarity coefficients revealed that 100% of the chicken and cow isolates and between 78 and 90% of the human, goose, duck, pig, and sheep isolates were assigned to the correct source groups. A dendrogram constructed by using Jaccard similarity coefficients almost completely separated the human isolates from the nonhuman isolates. Multivariate analysis of variance, a form of discriminant analysis, successfully differentiated the isolates and placed them in the appropriate source groups. Taken together, our results indicate that rep-PCR performed with the BOX A1R primer may be a useful and effective tool for rapidly determining sources of fecal pollution.
Spatial Patterns in Antibiotic Resistance among Stream Bacteria: Effects of Industrial Pollution
Authors: McArthur J Vaun , Tuckfield R. Cary 
Published: July 2002

ABSTRACT

The spatial distribution of antibiotic resistance to streptomycin and kanamycin was examined in natural bacterial communities of two streams. The proportion of resistant bacteria was substantially higher (
P
< 0.05) in the midreaches of an industrially perturbed stream, but no such pattern was apparent in an undisturbed reference stream. The highest relative frequency of resistance was found at the confluence of a tributary draining a nuclear reactor and industrial complex. Antibiotic resistance increased with distance upstream from the confluence and was positively correlated (
r
2
= 0.54,
P
= 0.023) with mercury concentrations in the sediments. When the data for two years were compared, this pattern was stable for streptomycin resistance (paired
t
test,
P
< 0.05) but not for kanamycin resistance (
P
> 0.05). Our results imply that heavy metal pollution may contribute to increased antibiotic resistance through indirect selection.
Exposure of Workers to Airborne Microorganisms in Open-Air Swine Houses
Authors: Chang C. W. , Chung H. , Huang C. F. , Su H. J. J. 
Published: July 2002

ABSTRACT

This study quantified the levels of airborne microorganisms in six swine farms with more than 10,000 pigs in subtropical Taiwan. We evaluated breeding, growing, and finishing stalls, which were primarily open-air buildings, as well as partially enclosed farrowing and nursery piggeries. Airborne culturable bacteria, gram-negative bacteria, and fungi were placed on appropriate media by using an all-glass impinger or single-stage Andersen microbial sampler. Results showed that mean concentrations of culturable bacteria and gram-negative bacteria were 3.3 × 10
5
and 143.7 CFU/m
3
, respectively. The concentration of airborne culturable fungi was about 10
3
CFU/m
3
, with
Cladosporium
the predominant genus. The highest airborne levels of culturable bacteria and gram-negative bacteria were identified in the finishing units. The air of the nursery stalls was the least contaminated with culturable and gram-negative bacteria. Irregular and infrequent cleaning, high pig density, no separation of wastes from pen floors, and accumulation of water as a result of the processes for cleaning and reducing pig temperature possibly compromise the benefits of the open characteristic of the finishing units with respect to airborne bacterial concentration.
Requirement of DNA Repair Mechanisms for Survival of
Burkholderia cepacia
G4 upon Degradation of Trichloroethylene
Authors: Yeager Chris M. , Bottomley Peter J. , Arp Daniel J. 
Published: July 2002

ABSTRACT

A Tn
5
-based mutagenesis strategy was used to generate a collection of trichloroethylene (TCE)-sensitive (TCS) mutants in order to identify repair systems or protective mechanisms that shield
Burkholderia cepacia
G4 from the toxic effects associated with TCE oxidation. Single Tn
5
insertion sites were mapped within open reading frames putatively encoding enzymes involved in DNA repair (UvrB, RuvB, RecA, and RecG) in 7 of the 11 TCS strains obtained (4 of the TCS strains had a single Tn
5
insertion within a
uvrB
homolog). The data revealed that the
uvrB
-disrupted strains were exceptionally susceptible to killing by TCE oxidation, followed by the
recA
strain, while the
ruvB
and
recG
strains were just slightly more sensitive to TCE than the wild type. The
uvrB
and
recA
strains were also extremely sensitive to UV light and, to a lesser extent, to exposure to mitomycin C and H
2
O
2
. The data from this study establishes that there is a link between DNA repair and the ability of
B. cepacia
G4 cells to survive following TCE transformation. A possible role for nucleotide excision repair and recombination repair activities in TCE-damaged cells is discussed.
Regulation of Fumonisin B
1
Biosynthesis and Conidiation in
Fusarium verticillioides
by a Cyclin-Like (C-Type) Gene,
FCC1
Authors: Shim Won-Bo , Woloshuk Charles P. 
Published: July 2002

ABSTRACT

Fumonisins are a group of mycotoxins produced in corn kernels by the plant-pathogenic fungus
Fusarium verticillioides
. A mutant of the fungus, FT536, carrying a disrupted gene named
FCC1
(for
Fusarium
cyclin C1) resulting in altered fumonisin B
1
biosynthesis was generated.
FCC1
contains an open reading frame of 1,018 bp, with one intron, and encodes a putative 319-amino-acid polypeptide. This protein is similar to UME3 (also called SRB11 or SSN8), a cyclin C of
Saccharomyces cerevisiae
, and contains three conserved motifs: a cyclin box, a PEST-rich region, and a destruction box. Also similar to the case for C-type cyclins,
FCC1
was constitutively expressed during growth. When strain FT536 was grown on corn kernels or on defined minimal medium at pH 6, conidiation was reduced and
FUM5
, the polyketide synthase gene involved in fumonisin B
1
biosynthesis, was not expressed. However, when the mutant was grown on a defined minimal medium at pH 3, conidiation was restored, and the blocks in expression of
FUM5
and fumonisin B
1
production were suppressed. Our data suggest that
FCC1
plays an important role in signal transduction regulating secondary metabolism (fumonisin biosynthesis) and fungal development (conidiation) in
F. verticillioides
.