bluuebunny/crossref_metadata_2025_split huggingface dataset:
TEM-80, a Novel Inhibitor-Resistant β-Lactamase in a Clinical Isolate of
Enterobacter cloacae
Authors: Arpin Corinne , Labia Roger , Dubois Véronique , Noury Patrick , Souquet Muriel , Quentin Claudine 
Published: July 2002

ABSTRACT

Enterobacter cloacae
Ecl261 was isolated with
Escherichia coli
Ec257 from the urine of a patient living in a nursing home. Both isolates were resistant to ticarcillin (MICs, 1,024 μg/ml), without significant potentiation of its activity by 2 μg of clavulanate per ml (MICs, 512 μg/ml), and susceptible to naturally active cephalosporins. This inhibitor-resistant phenotype was conferred in both strains by similar conjugative plasmids of 40 kb (Ecl261) and 30 kb (Ec257), which also conveyed resistance to sulfonamides and trimethoprim. Clinical and transconjugant strains produced a β-lactamase with a pI of 5.2 which belonged to the TEM family, as indicated by specific PCR amplification. Compared with TEM-1, this enzyme exhibited lower catalytic efficiencies (14- and 120-fold less for amoxicillin and ticarcillin, respectively), and higher concentrations of β-lactamase inhibitors were required to yield a 50% reduction in benzylpenicillin hydrolysis (750-, 82-, and 50-fold higher concentrations for clavulanate, sulbactam, and tazobactam, respectively). Gene sequencing revealed four nucleotide differences with the nucleotide sequence of
bla
TEM-1A
. The first replacement (T32C), located in the promoter region, was described as being responsible for the increase in the level of β-lactamase production. The three other changes led to amino acid substitutions that define a new inhibitor-resistant TEM (IRT) β-lactamase, TEM-80 (alternate name, IRT-24). Two of them, Met69Leu and Asn276Asp, have previously been related to inhibitor resistance. The additional mutation, Ile127Val, was demonstrated by site-directed mutagenesis to have a very weak effect, at least alone, on the IRT phenotype. This is the first description of an IRT β-lactamase in
E. cloacae
. The horizontal transfer of
bla
TEM-80
may have occurred either from Ec257 to Ecl261 or in the reverse order.
Macrolide and Tetracycline Resistance and Molecular Relationships of Clinical Strains of
Streptococcus agalactiae
Authors: Culebras Esther , Rodriguez-Avial Iciar , Betriu Carmen , Redondo Montserrat , Picazo Juan J. 
Published: July 2002

ABSTRACT

Mechanisms for tetracycline and macrolide resistance in 54 isolates of erythromycin-resistant
Streptococcus agalactiae
were analyzed by PCR. The
erm
(B),
erm
(A), and
mef
(A) genes, either alone or in combination, were detected in all the erythromycin-resistant isolates. The
tet
(M) and
tet
(O) genes were responsible for tetracycline resistance. Random amplification of polymorphic DNA indicated different clonal origins of the isolates.
Synergistic Effect of Ofloxacin and Magnesium Deficiency on Joint Cartilage in Immature Rats
Authors: Lozo Edith , Riecke Kai , Schwabe Rudolf , Vormann Jürgen , Stahlmann Ralf 
Published: July 2002

ABSTRACT

Single high oral doses of fluoroquinolones (e.g., 1,200 mg of ofloxacin/kg of body weight) are chondrotoxic in juvenile rats. Characteristic cartilage lesions are detectable as early as 12 h after treatment. Since this dosing regimen does not reflect the therapeutic situation, we studied the effects of a 5- or 7-day treatment with ofloxacin at lower oral doses (10, 30, and 100 mg/kg twice a day [b.i.d.]) on joint cartilage in 4-week-old rats. We additionally investigated whether the effects of ofloxacin under these conditions are enhanced in animals kept on a magnesium-deficient diet during treatment. Knee joints were examined histologically. The concentrations of ofloxacin and magnesium were determined in plasma and cartilage. The lowest ofloxacin dose at which cartilage lesions occurred in animals on a standard diet was 100 mg/kg b.i.d. for 5 days. Peak plasma ofloxacin levels were approximately 10 mg/liter in these rats and thus were in the same range as the levels in the plasma of humans during therapy with high doses of ofloxacin. Treatment with 30 mg of ofloxacin/kg b.i.d. for 7 days caused no cartilage lesions in rats on a standard diet, but lesions did occur in 10 of 12 rats that were simultaneously fed a magnesium-deficient diet. Magnesium concentrations in bone, plasma, and cartilage from animals on an Mg
2+
-deficient diet were significantly lower than those in the controls. The concentration in plasma from animals on an Mg
2+
-deficient diet was 0.27 ± 0.03 mmol/liter, whereas it was 0.88 ± 0.08 mmol/liter in plasma from rats on a standard diet (means ± standard deviations). Ofloxacin treatment did not change the total magnesium concentrations in tissues, as determined with ashed samples. The incidence of ofloxacin-induced lesions was higher in the magnesium-deficient animals, suggesting a synergistic effect. These results must be taken into account for a benefit-risk evaluation if ofloxacin is considered for use in the pediatric population.
Reducing Mortality in
Salmonella enterica
Serovar Typhimurium-Infected Mice with a Tripeptidic Serum Fraction
Authors: Parker Todd A. , Willeford Kenneth O. , Parker Suzanne , Buddington Karyl 
Published: July 2002

ABSTRACT
Salmonellosis-induced mortality in female Swiss Webster mice decreased significantly when tripeptidic immunostimulant (TPI) was administered prophylactically. Prophylactic benefits developed in a dose-dependent manner wherein 15 mg of TPI given 1 day before challenge reduced mortality by 70%.
Antisense Silencing of the
creA
Gene in
Aspergillus nidulans
Authors: Bautista L. Fernando , Aleksenko Alexei , Hentzer Morten , Santerre-Henriksen Anne , Nielsen Jens 
Published: July 2002

ABSTRACT

Antisense expression of a portion of the gene encoding the major carbon catabolite repressor CREA in
Aspergillus nidulans
resulted in a substantial increase in the levels of glucose-repressible enzymes, both endogenous and heterologous, in the presence of glucose. The derepression effect was approximately one-half of that achieved in a null
creA
mutant. Unlike results for that mutant, however, growth parameters and colony morphology in the antisense transformants were not affected.
The Autoproteolysis of
Lactococcus lactis
Lactocepin III Affects Its Specificity towards β-Casein
Authors: Flambard Benedicte , Juillard Vincent 
Published: July 2002

ABSTRACT

The effect of autoproteolysis of
Lactococcus lactis
lactocepin III on its specificity towards β-casein was investigated. β-Casein degradation was performed by using either an autolysin-defective derivative of
L. lactis
MG1363 carrying the proteinase genes of
L. lactis
SK11, which was unable to transport oligopeptides, or autoproteolyzed enzyme purified from
L. lactis
SK11. Comparison of the peptide pools by high-performance liquid chromatography analysis revealed significant differences. To analyze these differences in more detail, the peptides released by the cell-anchored proteinase were identified by on-line coupling of liquid chromatography to mass spectrometry. More than 100 oligopeptides were released from β-casein by the cell-anchored proteinase. Analysis of the cleavage sites indicated that the specificity of peptide bond cleavage by the cell-anchored proteinase differed significantly from that of the autoproteolyzed enzyme.
Quantification of Siderophore and Hemolysin from
Stachybotrys chartarum
Strains, Including a Strain Isolated from the Lung of a Child with Pulmonary Hemorrhage and Hemosiderosis
Authors: Vesper Stephen J. , Dearborn Dorr G. , Elidemir Okan , Haugland Richard A. 
Published: July 2002

ABSTRACT

A strain of
Stachybotrys chartarum
was recently isolated from the lung of a pulmonary hemorrhage and hemosiderosis (PH) patient in Texas (designated the Houston strain). This is the first time that
S. chartarum
has been isolated from the lung of a PH patient. In this study, the Houston strain and 10 strains of
S. chartarum
isolated from case (
n
= 5) or control (
n
= 5) homes in Cleveland were analyzed for hemolytic activity, siderophore production, and relatedness as measured by random amplified polymorphic DNA analysis.
Reactions Involved in the Lower Pathway for Degradation of 4-Nitrotoluene by
Mycobacterium
Strain HL 4-NT-1
Authors: He Zhongqi , Spain Jim C. 
Published: July 2002

ABSTRACT

In spite of the variety of initial reactions, the aerobic biodegradation of aromatic compounds generally yields dihydroxy intermediates for ring cleavage. Recent investigation of the degradation of nitroaromatic compounds revealed that some nitroaromatic compounds are initially converted to 2-aminophenol rather than dihydroxy intermediates by a number of microorganisms. The complete pathway for the metabolism of 2-aminophenol during the degradation of nitrobenzene by
Pseudomonas pseudoalcaligenes
JS45 has been elucidated previously. The pathway is parallel to the catechol extradiol ring cleavage pathway, except that 2-aminophenol is the ring cleavage substrate. Here we report the elucidation of the pathway of 2-amino-4-methylphenol (6-amino-
m
-cresol) metabolism during the degradation of 4-nitrotoluene by
Mycobacterium
strain HL 4-NT-1 and the comparison of the substrate specificities of the relevant enzymes in strains JS45 and HL 4-NT-1. The results indicate that the 2-aminophenol ring cleavage pathway in strain JS45 is not unique but is representative of the pathways of metabolism of other
o
-aminophenolic compounds.
Modification of Sorbitol MacConkey Medium Containing Cefixime and Tellurite for Isolation of
Escherichia coli
O157:H7 from Radish Sprouts
Authors: Fujisawa Tomohiko , Sata Shin , Aikawa Katsuhiro , Takahashi Takanori , Yamai Shiro , Shimada Toshio 
Published: July 2002

ABSTRACT

A modified version of sorbitol MacConkey medium containing cefixime and tellurite (CT-SMAC medium) was produced by adding salicin and 4-methylumbelliferyl-β-
d
-galactopyranoside to CT-SMAC medium; this medium was designated CT-SSMAC medium and was used to isolate
Escherichia coli
O157:H7 from radish sprouts. Of 101 non-
E. coli
bacteria isolated from radish sprouts that produced colorless colonies similar to colonies of
E. coli
O157:H7 grown on CT-SMAC medium, 92 (91%) formed colonies that were red to pink or were β-galactosidase negative and colorless on CT-SSMAC medium. On the other hand, colonies of
E. coli
O157:H7 strains were colorless and β-galactosidase positive on CT-SSMAC medium. Our results suggest that CT-SSMAC medium is more selective than CT-SMAC medium for isolating
E. coli
O157:H7.
The α-Helix 4 Residue, Asn135, Is Involved in the Oligomerization of Cry1Ac1 and Cry1Ab5
Bacillus thuringiensis
Toxins
Authors: Tigue Natalie J. , Jacoby Juliette , Ellar David J. 
Published: July 2002

ABSTRACT

The insecticidal Cry toxins produced by the bacterium
Bacillus thuringiensis
are comprised of three structural domains. Domain I, a seven-helix bundle, is thought to penetrate the insect epithelial cell plasma membrane through a hairpin composed of α-helices 4 and 5, followed by the oligomerization of four hairpin monomers. The α-helix 4 has been proposed to line the lumen of the pore, whereas some residues in α-helix 5 have been shown to be responsible for oligomerization. Mutation of the Cry1Ac1 α-helix 4 amino acid Asn135 to Gln resulted in the loss of toxicity to
Manduca sexta
, yet binding was still observed. In this study, the equivalent mutation was made in the Cry1Ab5 toxin, and the properties of both wild-type and mutant toxin counterparts were analyzed. Both mutants appeared to bind to
M. sexta
membrane vesicles, but they were not able to form pores. The ability of both N135Q mutants to oligomerize was also disrupted, providing the first evidence that a residue in α-helix 4 can contribute to toxin oligomerization.
The Effect of the
Agrobacterium tumefaciens attR
Mutation on Attachment and Root Colonization Differs between Legumes and Other Dicots
Authors: Matthysse Ann G. , McMahan Susan 
Published: July 2002

ABSTRACT

Infections of wound sites on dicot plants by
Agrobacterium tumefaciens
result in the formation of crown gall tumors. An early step in tumor formation is bacterial attachment to the plant cells. AttR mutants failed to attach to wound sites of both legumes and nonlegumes and were avirulent on both groups of plants. AttR mutants also failed to attach to the root epidermis and root hairs of nonlegumes and had a markedly reduced ability to colonize the roots of these plants. However, AttR mutants were able to attach to the root epidermis and root hairs of alfalfa, garden bean, and pea. The mutant showed little reduction in its ability to colonize these roots. Thus,
A. tumefaciens
appears to possess two systems for binding to plant cells. One system is AttR dependent and is required for virulence on all of the plants tested and for colonization of the roots of all of the plants tested except legumes. Attachment to root hairs through this system can be blocked by the acetylated capsular polysaccharide. The second system is AttR independent, is not inhibited by the acetylated capsular polysaccharide, and allows the bacteria to bind to the roots of legumes.
Comparison of Statistical Methods for Identification of
Streptococcus thermophilus,
Enterococcus faecalis,
and
Enterococcus faecium
from Randomly Amplified Polymorphic DNA Patterns
Authors: Moschetti Giancarlo , Blaiotta Giuseppe , Villani Francesco , Coppola Salvatore , Parente Eugenio 
Published: July 2002

ABSTRACT

Thermophilic streptococci play an important role in the manufacture of many European cheeses, and a rapid and reliable method for their identification is needed. Randomly amplified polymorphic DNA (RAPD) PCR (RAPD-PCR) with two different primers coupled to hierarchical cluster analysis has proven to be a powerful tool for the classification and typing of
Streptococcus thermophilus
,
Enterococcus faecium
, and
Enterococcus faecalis
(G. Moschetti, G. Blaiotta, M. Aponte, P. Catzeddu, F. Villani, P. Deiana, and S. Coppola, J. Appl. Microbiol. 85:25–36, 1998). In order to develop a fast and inexpensive method for the identification of thermophilic streptococci, RAPD-PCR patterns were generated with a single primer (XD9), and the results were analyzed using artificial neural networks (Multilayer Perceptron, Radial Basis Function network, and Bayesian network) and multivariate statistical techniques (cluster analysis, linear discriminant analysis, and classification trees). Cluster analysis allowed the identification of
S. thermophilus
but not of enterococci. A Bayesian network proved to be more effective than a Multilayer Perceptron or a Radial Basis Function network for the identification of
S. thermophilus
,
E. faecium
, and
E. faecalis
using simplified RAPD-PCR patterns (obtained by summing the bands in selected areas of the patterns). The Bayesian network also significantly outperformed two multivariate statistical techniques (linear discriminant analysis and classification trees) and proved to be less sensitive to the size of the training set and more robust in the response to patterns belonging to unknown species.
Characterization of a Heme-Dependent Catalase from
Methanobrevibacter arboriphilus
Authors: Shima Seigo , Sordel-Klippert Melanie , Brioukhanov Andrei , Netrusov Alexander , Linder Dietmar , Thauer Rudolf K. 
Published: July 2002

ABSTRACT

Recently it was reported that methanogens of the genus
Methanobrevibacter
exhibit catalase activity. This was surprising, since
Methanobrevibacter
species belong to the order
Methanobacteriales
, which are known not to contain cytochromes and to lack the ability to synthesize heme. We report here that
Methanobrevibacter arboriphilus
strains AZ and DH1 contained catalase activity only when the growth medium was supplemented with hemin. The heme catalase was purified and characterized, and the encoding gene was cloned. The amino acid sequence of the catalase from the methanogens is most similar to that of
Methanosarcina barkeri
.
Decrease in
Cryptosporidium parvum
Oocyst Infectivity In Vitro by Using the Membrane Filter Dissolution Method for Recovering Oocysts from Water Samples
Authors: Carreno Ramon A. , Pokorny Nicholas J. , Weir Susan C. , Lee Hung , Trevors Jack T. 
Published: July 2002

ABSTRACT

Exposure of
Cryptosporidium parvum
oocysts to solutions used for cellulose acetate membrane (CAM) dissolution filtration reduced their infectivity in HCT-8 cells. Ethanol (95% [vol/vol] and 70% [vol/vol]) alone and short exposure times to acetone decreased infectivity. These findings contrast with similar experiments using excystation assays and infectivity in mice.
Transformation of 2,2′-Bimorphine to the Novel Compounds 10-α-
S
-Monohydroxy-2,2′-Bimorphine and 10,10′-α,α′-
S
,
S
′-Dihydroxy-2,2′-Bimorphine by
Cylindrocarpon didymum
Authors: Stabler Peter J. , Holt Peter J. , Bruce Neil C. 
Published: July 2002

ABSTRACT

Whole-cell suspensions of
Cylindrocarpon didymum
were observed to transform 2,2′-bimorphine to the compounds 10-α-
S
-monohydroxy-2,2′-bimorphine and 10,10′-α,α′-
S
,
S
′-dihydroxy-2,2′-bimorphine. Mass spectrometry and
1
H nuclear magnetic resonance spectroscopy confirmed the identities of these new morphine alkaloids.
Mapping Microbial Biodiversity
Authors: Stoner Daphne L. , Geary Micah C. , White Luke J. , Lee Randy D. , Brizzee Julie A. , Rodman Ann C. , Rope Ronald C. 
Published: July 2002

ABSTRACT
We report the development of a prototype database that “maps” microbial diversity in the context of the geochemical and geological environment and geographic location. When it is fully implemented, scientists will be able to conduct database searches, construct maps containing the information of interest, download files, and enter data over the Internet.
Salmonella enterica
Serotype Bredeney: Antimicrobial Susceptibility and Molecular Diversity of Isolates from Ireland and Northern Ireland
Authors: Cormican Martin , DeLappe Niall , O’Hare Colette , Doran Geraldine , Morris Dearbhaile , Corbett-Feeney Geraldine , Fanning Séamus , Daly Mairead , Fitzgerald Margaret , Moore John 
Published: July 2002

ABSTRACT

Salmonella enterica
serotype Bredeney has emerged as the third most commonly identified serotype among human clinical isolates referred to the Irish National Salmonella Reference Laboratory in the years 1998 to 2000. A collection of 112 isolates of
S. enterica
serotype Bredeney collected during the period 1995 to 1999 from animal, food, and human sources from both Ireland and Northern Ireland were studied. Antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and DNA amplification fingerprinting (DAF) were performed on all isolates. Plasmid profiles were examined on a subset of 33 isolates. A high proportion (74%) of isolates were susceptible to all antimicrobial agents tested. Resistance to both sulfonamide and trimethoprim was observed in 21% of isolates, and resistance to multiple (five) antimicrobial agents was observed in a single isolate (0.9%). Eight different PFGE patterns were obtained, with 87% of isolates grouping as PFGE type A. PFGE type A was predominant in animals, food, and humans. There was good overall concordance between the groups identified by PFGE and DAF. Overall results indicate that most
S. enterica
serotype Bredeney isolates in Ireland and Northern Ireland from animal and human sources are clonally related.
Electrochemical Regeneration of Fe(III) To Support Growth on Anaerobic Iron Respiration
Authors: Ohmura Naoya , Matsumoto Norio , Sasaki Kazuhiro , Saiki Hiroshi 
Published: July 2002

ABSTRACT

Here we describe artificial help for the respiratory electron flow supporting anaerobic growth of
Thiobacillus ferrooxidans
through exogenous electrolysis. Flux between H
2
and a anode through cells was accomplished with electrochemical regeneration of iron. The electrochemical help resulted in a 12-fold increase in yield compared with the yield observed in its absence.
Effects of Temperature, Water Activity, and Syrup Film Composition on the Growth of
Wallemia sebi
: Development and Assessment of a Model Predicting Growth Lags in Syrup Agar and Crystalline Sugar
Authors: Vindeløv Jannik , Arneborg Nils 
Published: July 2002

ABSTRACT

We investigated the effects of temperature, water activity (a
w
), and syrup film composition on the CFU growth of
Wallemia sebi
in crystalline sugar. At a high a
w
(0.82) at both high (20°C) and low (10°C) temperatures, the CFU growth of
W. sebi
in both white and extrawhite sugar could be described using a modified Gompertz model. At a low a
w
(0.76), however, the modified Gompertz model could not be fitted to the CFU data obtained with the two sugars due to long CFU growth lags and low maximum specific CFU growth rates of
W. sebi
at 20°C and due to the fact that growth did not occur at 10°C. At an a
w
of 0.82, regardless of the temperature, the carrying capacity (i.e., the cell concentration at
t
= ∞) of extrawhite sugar was lower than that of white sugar. Together with the fact that the syrup film of extrawhite sugar contained less amino-nitrogen relative to other macronutrients than the syrup film of white sugar, these results suggest that CFU growth of
W. sebi
in extrawhite sugar may be nitrogen limited. We developed a secondary growth model which is able to predict colony growth lags of
W. sebi
on syrup agar as a function of temperature and a
w
. The ability of this model to predict CFU growth lags of
W. sebi
in crystalline sugar was assessed.
Energy Generation by Extracellular Aldose Oxidation in N
2
-Fixing
Gluconacetobacter diazotrophicus
Authors: Luna María F. , Bernardelli Cecilia E. , Mignone Carlos F. , Boiardi José L. 
Published: July 2002

ABSTRACT

Gluconacetobacter diazotrophicus
PAL3 was grown in a chemostat with N
2
and mixtures of xylose and gluconate. Xylose was oxidized to xylonate, which was accumulated in the culture supernatants. Biomass yields and carbon from gluconate incorporated into biomass increased with the rate of xylose oxidation. By using metabolic balances it is demonstrated that extracellular xylose oxidation led N
2
-fixing
G. diazotrophicus
cultures to increase the efficiency of energy generation.
Thermodynamic Analysis of Growth Temperature Dependence in the Adhesion of
Candida parapsilosis
to Polystyrene
Authors: Gallardo-Moreno Amparo M. , González-Martín M. Luisa , Pérez-Giraldo Ciro , Garduño Eugenio , Bruque José M. , Gómez-García Antonio C. 
Published: July 2002

ABSTRACT

The purpose of this work was to study the adhesion to polystyrene of two
Candida parapsilosis
strains, grown at 22 and 37°C, in terms of hydrophobicity, surface charge, and interaction free energy. Growth temperature changed the surface properties of microorganisms, yielding a good correlation between thermodynamic predictions and adhesion behavior.
Hemoglobin in
Frankia
, a Nitrogen-Fixing Actinomycete
Authors: Tjepkema John D. , Cashon Robert E. , Beckwith Jason , Schwintzer Christa R. 
Published: July 2002

ABSTRACT

Frankia
strain CcI3 grown in culture produced a hemoglobin which had optical absorption bands typical of a hemoglobin and a molecular mass of 14.1 kDa. Its equilibrium oxygen binding constant was 274 nM, the oxygen dissociation rate constant was 56 s
−1
, and the oxygen association rate constant was 206 μM
−1
s
−1
.
Comparison of Polymorphonuclear Cells from Healthy Donors and Differentiated HL-60 Cells as Phagocytes in an Opsonophagocytic Assay Using Antigen-Coated Fluorescent Beads
Authors: Guy Bruno , Testart Catherine , Gimenez Sophie , Sanchez Violette , Lheritier Philippe , Rossin Danielle , Mignon Michèle , Danve Bernard , Trannoy Emanuelle 
Published: July 2002

ABSTRACT

Polymorphonuclear cells (PMNs) from healthy donors and differentiated HL-60 cells were compared in an opsonophagocytic assay using fluorescent latex beads coated with
Streptococcus pneumoniae
polysaccharide conjugates. Serum-specific phagocytosis was efficiently mediated by both sources of cells, as measured by flow cytometry, but the mean number of beads ingested per cell was three- to fivefold higher when PMNs were used than when HL-60 cells were used. Nevertheless, differentiated HL-60 cells could be a convenient and standardized source of cells to evaluate the functionality of specific antibodies to vaccine candidates as a coating on fluorescent beads.