bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vivo Influenza Virus-Inhibitory Effects of the Cyclopentane Neuraminidase Inhibitor RWJ-270201
Authors: Sidwell Robert W. , Smee Donald F. , Huffman John H. , Barnard Dale L. , Bailey Kevin W. , Morrey John D. , Babu Y. S. 
Published: July 2002

ABSTRACT

The cyclopentane influenza virus neuraminidase inhibitor RWJ-270201 was evaluated against influenza A/NWS/33 (H1N1), A/Shangdong/09/93 (H3N2), A/Victoria/3/75 (H3N2), and B/Hong Kong/05/72 virus infections in mice. Treatment was by oral gavage twice daily for 5 days beginning 4 h pre-virus exposure. The influenza virus inhibitor oseltamivir was run in parallel, and ribavirin was included in studies with the A/Shangdong and B/Hong Kong viruses. RWJ-270201 was inhibitory to all infections using doses as low as 1 mg/kg/day. Oseltamivir was generally up to 10-fold less effective than RWJ-270201. Ribavirin was also inhibitory but was less tolerated by the mice at the 75-mg/kg/day dose used. Disease-inhibitory effects included prevention of death, lessening of decline of arterial oxygen saturation, inhibition of lung consolidation, and reduction in lung virus titers. RWJ-270201 and oseltamivir, at doses of 10 and 1 mg/kg/day each, were compared with regard to their effects on daily lung parameters in influenza A/Shangdong/09/93 virus-infected mice. Maximum virus titer inhibition was seen on day 1, with RWJ-270201 exhibiting the greater inhibitory effect, a titer reduction of >10
4
cell culture 50% infective doses (CCID
50
)/g. By day 8, the lung virus titers in mice treated with RWJ-270201 had declined to 10
1.2
CCID
50
/g, whereas titers from oseltamivir-treated animals were >10
3
CCID
50
/g. Mean lung consolidation was also higher in the oseltamivir-treated animals on day 8. Both neuraminidase inhibitors were well tolerated by the mice. RWJ-270201 was nontoxic at doses as high as 1,000 mg/kg/day. These data indicate potential for the oral use of RWJ-270201 in the treatment of influenza virus infections in humans.
In Vitro Activities of Three Nonfluorinated Quinolones against Representative Bacterial Isolates
Authors: Barry Arthur L. , Fuchs Peter C. , Brown Steven D. 
Published: July 2002

ABSTRACT

In vitro susceptibility tests were performed to document the inhibitory activities of three nonfluorinated quinolone (NFQ) compounds (PGE 9262932, PGE 9509924, and PGE 4175997) compared to those of ciprofloxacin, levofloxacin, and trovafloxacin against 3,030 bacterial isolates. The spectra of the NFQ agents included most gram-positive species as well as quinolone-susceptible
Enterobacteriaceae
. Ciprofloxacin-resistant, methicillin-resistant
Staphylococcus aureus
strains were inhibited by the NFQ series at ≤1.0 μg/ml. The NFQ compounds were not very active against
Pseudomonas aeruginosa
and most other nonfermentative gram-negative bacilli. Against other species, the potency of the NFQ agents was similar to that of trovafloxacin. Continued investigation of the NFQ compounds seems to be warranted.
Prevalence of Single Mutations in Topoisomerase Type II Genes among Levofloxacin-Susceptible Clinical Strains of
Streptococcus pneumoniae
Isolated in the United States in 1992 to 1996 and 1999 to 2000
Authors: Davies Todd A. , Evangelista Alan , Pfleger Sharon , Bush Karen , Sahm Daniel F. , Goldschmidt Raul 
Published: July 2002

ABSTRACT

Levofloxacin resistance in
Streptococcus pneumoniae
is rare, requiring at least two mutations in the quinolone resistance-determining region (QRDR) of topoisomerase IV and DNA gyrase. The prevalence of single QRDR mutations in these genes is unknown. Of 9,438 levofloxacin-susceptible pneumococci from the TRUST 4 surveillance study (1999–2000), 528 strains (MICs of 0.5 to 2.0 μg/ml) were selected for analysis. For comparison, 214 levofloxacin-susceptible strains (MICs of 0.5 to 1 μg/ml) isolated between 1992 and 1996 were analyzed. Oligonucleotide probe assay and DNA sequencing were used to detect QRDR mutations leading to changes at Ser79 and Asp83 in ParC, Ser81 in GyrA, and Asp435 in ParE, the most frequently found substitutions among levofloxacin-resistant strains. Among the 1992 to 1996 isolates only one strain (levofloxacin MIC, 1 μg/ml) had a mutation (Ser79 to Phe in ParC). No single mutations were found among 270 TRUST 4 strains with levofloxacin MICs of 0.5 μg/ml. Among 244 strains for which levofloxacin MICs were 1 μg/ml, 15 strains (6.1%) had a
parC
mutation and 3 strains (1.2%) had a
parE
mutation. Of 14 strains for which levofloxacin MICs were 2 μg/ml, 10 strains (71%) had a
parC
mutation; no
parE
mutations were found. No
gyrA
mutations were detected. It was estimated that 4.5% of the 9,438 levofloxacin-susceptible TRUST 4 isolates (MICs, ≤0.06 to 2 μg/ml) had a single
parC
or
parE
QRDR mutation. Although there has been an increase in the prevalence of single-step mutants, the increase may have been overestimated due in part to differences in geographical distribution for the two sets of isolates.
In Vitro Microbicidal Activities of Cecropin Peptides D2A21 and D4E1 and Gel Formulations Containing 0.1 to 2% D2A21 against
Chlamydia trachomatis
Authors: Ballweber L. M. , Jaynes J. E. , Stamm W. E. , Lampe M. F. 
Published: July 2002

ABSTRACT

Topically applied microbicides that eradicate pathogens at the time of initial exposure represent a powerful strategy for the prevention of sexually transmitted infections. To aid in the further development of an effective topical microbicide, we assessed the minimum cidal concentration (MCC) of two cecropin peptides, D2A21 and D4E1, and gel formulations containing 0.1 to 2% D2A21 against
Chlamydia trachomatis
in vitro. The MCC of peptide D2A21was 5 μM (18.32 μg/ml), and that of peptide D4E1 was 7.5 μM (21.69 μg/ml). The MCC of gel formulations containing 2% D2A21 was 0.2 mM (0.7 mg/ml), and that of gel formulations containing 0.5% D2A21 was 0.2 mM (0.7 mg/ml). There was no significant variation in the results when two different
C. trachomatis
strains were tested, and the addition of 10% human blood did not significantly alter the MCCs. pH values above and below 7 reduced the activity of the D2A21 peptide alone, but the MCC of the 2% D2A21 gel formulation was only slightly altered at the various pHs tested. Ultrastructural studies indicated that
C. trachomatis
membranes were disrupted after D2A21 exposure, resulting in leakage of the cytoplasmic contents. These in vitro results suggest that these cecropin peptides may be an effective topical microbicide against
C. trachomatis
and support the need for further evaluation.
Combination of Quinupristin-Dalfopristin (Synercid) and Rifampin Is Highly Synergistic in Experimental
Staphylococcus aureus
Joint Prosthesis Infection
Authors: Saleh-Mghir Azzam , Ameur Nourdine , Muller-Serieys Claudette , Ismael Farid , Lemaitre Françoise , Massias Laurent , Feger Céline , Bléton Rémy , Crémieux Anne-Claude 
Published: July 2002

ABSTRACT

We compared the efficacies of quinupristin-dalfopristin (Q-D; 30 mg/kg of body weight every 8 h) and vancomycin (60 mg/kg twice daily), alone or in combination with rifampin (10 mg/kg twice daily), in a rabbit model of methicillin-resistant
Staphylococcus aureus
knee prosthesis infection. In contrast to vancomycin, Q-D significantly reduced the mean log
10
CFU per gram of bone versus that for the controls. The combination of rifampin with either Q-D or vancomycin was significantly more effective than monotherapy.
Amphotericin B Formulations Exert Additive Antifungal Activity in Combination with Pulmonary Alveolar Macrophages and Polymorphonuclear Leukocytes against
Aspergillus fumigatus
Authors: Roilides Emmanuel , Lyman Caron A. , Filioti Joanna , Akpogheneta Onome , Sein Tin , Lamaignere Cristina Gil , Petraitiene Ruta , Walsh Thomas J. 
Published: July 2002

ABSTRACT

Deoxycholate amphotericin B (DAMB) and amphotericin B lipid complex (ABLC) additively augmented the fungicidal activity of pulmonary alveolar macrophages against the conidia of
Aspergillus fumigatus
. DAMB, ABLC, and liposomal amphotericin B similarly displayed additive effects with polymorphonuclear leukocytes in damaging the hyphal elements of
A. fumigatus
.
Sulfur Regulation of the Sulfate Transporter Genes
sutA
and
sutB
in
Penicillium chrysogenum
Authors: van de Kamp Mart , Schuurs Theo A. , Vos Arnold , van der Lende Ted R. , Konings Wil N. , Driessen Arnold J. M. 
Published: July 2002

ABSTRACT

Penicillium chrysogenum
uses sulfate as a source of sulfur for the biosynthesis of penicillin. Sulfate uptake and the mRNA levels of the sulfate transporter-encoding
sutB
and
sutA
genes are all reduced by high sulfate concentrations and are elevated by sulfate starvation. In a high-penicillin-yielding strain,
sutB
is effectively transcribed even in the presence of excess sulfate. This deregulation may facilitate the efficient incorporation of sulfur into cysteine and penicillin.
Expression of a Heterologous Glutamate Dehydrogenase Gene in
Lactococcus lactis
Highly Improves the Conversion of Amino Acids to Aroma Compounds
Authors: Rijnen Liesbeth , Courtin Pascal , Gripon Jean-Claude , Yvon Mireille 
Published: July 2002

ABSTRACT

The first step of amino acid degradation in lactococci is a transamination, which requires an α-keto acid as the amino group acceptor. We have previously shown that the level of available α-keto acid in semihard cheese is the first limiting factor for conversion of amino acids to aroma compounds, since aroma formation is greatly enhanced by adding α-ketoglutarate to cheese curd. In this study we introduced a heterologous catabolic glutamate dehydrogenase (GDH) gene into
Lactococcus lactis
so that this organism could produce α-ketoglutarate from glutamate, which is present at high levels in cheese. Then we evaluated the impact of GDH activity on amino acid conversion in in vitro tests and in a cheese model by using radiolabeled amino acids as tracers. The GDH-producing lactococcal strain degraded amino acids without added α-ketoglutarate to the same extent that the wild-type strain degraded amino acids with added α-ketoglutarate. Interestingly, the GDH-producing lactococcal strain produced a higher proportion of carboxylic acids, which are major aroma compounds. Our results demonstrated that a GDH-producing lactococcal strain could be used instead of adding α-ketoglutarate to improve aroma development in cheese.
Metabolic Activity of Permafrost Bacteria below the Freezing Point
Authors: Rivkina E. M. , Friedmann E. I. , McKay C. P. , Gilichinsky D. A. 
Published: July 2002

ABSTRACT

Metabolic activity was measured in the laboratory at temperatures between 5 and −20°C on the basis of incorporation of
14
C-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5°C) to 20 days (−10°C) to ca. 160 days (−20°C). The curves reached the stationary phase at different levels, depending on the incubation temperature. We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature.
Changes in the Carriage of
Campylobacter
Strains by Poultry Carcasses during Processing in Abattoirs
Authors: Newell D. G. , Shreeve J. E. , Toszeghy M. , Domingue G. , Bull S. , Humphrey T. , Mead G. 
Published: July 2002

ABSTRACT

The recent development of simple, rapid genotyping techniques for
Campylobacter
species has enabled investigation of the determinative epidemiology of these organisms in a variety of situations. In this study we have used the technique of
fla
typing (PCR-restriction fragment length polymorphism analysis of the
flaA
and
flaB
genes) to identify the sources of strains contaminating the carcasses of five campylobacter-positive and two campylobacter-negative broiler flocks during abattoir processing. The results confirmed that, in the United Kingdom, individual broiler flocks are colonized by a limited number of subtypes of
Campylobacter jejuni
or
C. coli
. In some but not all cases, the same subtypes, isolated from the ceca, contaminated the end product as observed in carcass washes. However, the culture methodology, i.e, use of direct plating or enrichment, affected this subtype distribution. Moreover, the number of isolates analyzed per sample was limited.
fla
typing also indicated that some campylobacter subtypes survive poultry processing better than others. The extent of resistance to the environmental stresses during processing varied between strains. The more robust subtypes appeared to contaminate the abattoir environment, surviving through carcass chilling, and even carrying over onto subsequent flocks. From these studies it is confirmed that some campylobacter-negative flocks reach the abattoir but the carcasses from such flocks are rapidly contaminated by various campylobacter subtypes during processing. However, only some of these contaminating subtypes appeared to survive processing. The sources of this contamination are not clear, but in both negative flocks, campylobacters of the same subtypes as those recovered from the carcasses were isolated from the crates used to transport the birds. In one case, this crate contamination was shown to be present before the birds were loaded.
Analysis of the Role of OpuC, an Osmolyte Transport System, in Salt Tolerance and Virulence Potential of
Listeria monocytogenes
Authors: Sleator Roy D. , Wouters Jeroen , Gahan Cormac G. M. , Abee Tjakko , Hill Colin 
Published: July 2002

ABSTRACT

The success of
Listeria monocytogenes
as a food-borne pathogen owes much to its ability to survive a variety of stresses, both in the external environment prior to ingestion and subsequently within the animal host. Growth at high salt concentrations and low temperatures is attributed mainly to the accumulation of organic solutes such as glycine betaine and carnitine. We utilized a novel system for generating chromosomal mutations (based on a lactococcal pWVO1-derived Ori
+
RepA
−
vector, pORI19) to identify a listerial OpuC homologue. Mutating the operon in two strains of
L. monocytogenes
revealed significant strain variation in the observed activity of OpuC. Radiolabeled osmolyte uptake studies, together with growth experiments in defined media, linked OpuC to carnitine and glycine betaine uptake in
Listeria
. We also investigated the role of OpuC in contributing to the growth and survival of
Listeria
in an animal (murine) model of infection. Altering OpuC resulted in a significant reduction in the ability of
Listeria
to colonize the upper small intestine and cause subsequent systemic infection following peroral inoculation.
Cross-Resistance and Stability of Resistance to
Bacillus thuringiensis
Toxin Cry1C in Diamondback Moth
Authors: Liu Yong-Biao , Tabashnik Bruce E. , Meyer Susan K. , Crickmore Neil 
Published: July 2002

ABSTRACT

We tested toxins of
Bacillus thuringiensis
against larvae from susceptible, Cry1C-resistant, and Cry1A-resistant strains of diamondback moth (
Plutella xylostella
). The Cry1C-resistant strain, which was derived from a field population that had evolved resistance to
B. thuringiensis
subsp.
kurstaki
and
B. thuringiensis
subsp.
aizawai
, was selected repeatedly with Cry1C in the laboratory. The Cry1C-resistant strain had strong cross-resistance to Cry1Ab, Cry1Ac, and Cry1F, low to moderate cross-resistance to Cry1Aa and Cry9Ca, and no cross-resistance to Cry1Bb, Cry1Ja, and Cry2A. Resistance to Cry1C declined when selection was relaxed. Together with previously reported data, the new data on the cross-resistance of a Cry1C-resistant strain reported here suggest that resistance to Cry1A and Cry1C toxins confers little or no cross-resistance to Cry1Bb, Cry2Aa, or Cry9Ca. Therefore, these toxins might be useful in rotations or combinations with Cry1A and Cry1C toxins. Cry9Ca was much more potent than Cry1Bb or Cry2Aa and thus might be especially useful against diamondback moth.
Purification and Characterization of a Dimethoate-Degrading Enzyme of
Aspergillus niger
ZHY256, Isolated from Sewage
Authors: Liu Yu-Huan , Chung Ying-Cheng , Xiong Ya 
Published: July 2002

ABSTRACT

A dimethoate-degrading enzyme from
Aspergillus niger
ZHY256 was purified to homogeneity with a specific activity of 227.6 U/mg of protein. The molecular mass of the purified enzyme was estimated to be 66 kDa by gel filtration and 67 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point was found to be 5.4, and the enzyme activity was optimal at 50°C and pH 7.0. The activity was inhibited by most of the metal ions and reagents, while it was induced by Cu
2+
. The Michaelis constant (
K

m

) and
V
max
for dimethoate were 1.25 mM and 292 μmol min
−1
mg of protein
−1
, respectively.
Transformation of Chlorinated Benzenes and Toluenes by
Ralstonia
sp. Strain PS12
tecA
(Tetrachlorobenzene Dioxygenase) and
tecB
(Chlorobenzene Dihydrodiol Dehydrogenase) Gene Products
Authors: Pollmann Katrin , Beil Stefan , Pieper Dietmar H. 
Published: July 2002

ABSTRACT

The
tecB
gene, located downstream of
tecA
and encoding tetrachlorobenzene dioxygenase, in
Ralstonia
sp. strain PS12 was cloned into
Escherichia coli
DH5α together with the
tecA
gene. The identity of the
tecB
gene product as a chlorobenzene dihydrodiol dehydrogenase was verified by transformation into the respective catechols of chlorobenzene, the three isomeric dichlorobenzenes, as well as 1,2,3- and 1,2,4-trichlorobenzenes, all of which are transformed by TecA into the respective dihydrodihydroxy derivatives. Di- and trichlorotoluenes were either subject to TecA-mediated dioxygenation (the major or sole reaction observed for the 1,2,4-substituted 2,4-, 2,5-, and 3,4-dichlorotoluenes), resulting in the formation of the dihydrodihydroxy derivatives, or to monooxygenation of the methyl substituent (the major or sole reaction observed for 2,3-, 2,6-, and 3,5-dichloro- and 2,4,5-trichlorotoluenes), resulting in formation of the respective benzyl alcohols. All of the chlorotoluenes subject to dioxygenation by TecA were transformed, without intermediate accumulation of dihydrodihydroxy derivatives, into the respective catechols by TecAB, indicating that dehydrogenation is no bottleneck for chlorobenzene or chlorotoluene degradation. However, only those chlorotoluenes subject to a predominant dioxygenation were growth substrates for PS12, confirming that monooxygenation is an unproductive pathway in PS12.
Carbon Isotope Fractionation during Aerobic Biodegradation of Trichloroethene by
Burkholderia cepacia
G4: a Tool To Map Degradation Mechanisms
Authors: Barth Johannes A. C. , Slater Greg , Schüth Christoph , Bill Markus , Downey Angela , Larkin Mike , Kalin Robert M. 
Published: July 2002

ABSTRACT

The strain
Burkholderia cepacia
G4 aerobically mineralized trichloroethene (TCE) to CO
2
over a time period of ∼20 h. Three biodegradation experiments were conducted with different bacterial optical densities at 540 nm (OD
540
s) in order to test whether isotope fractionation was consistent. The resulting TCE degradation was 93, 83.8, and 57.2% (i.e., 7.0, 16.2, and 42.8% TCE remaining) at OD
540
s of 2.0, 1.1, and 0.6, respectively. ODs also correlated linearly with zero-order degradation rates (1.99, 1.11, and 0.64 μmol h
−1
). While initial nonequilibrium mass losses of TCE produced only minor carbon isotope shifts (expressed in per mille δ
13
C
VPDB
), they were 57.2, 39.6, and 17.0‰ between the initial and final TCE levels for the three experiments, in decreasing order of their OD
540
s. Despite these strong isotope shifts, we found a largely uniform isotope fractionation. The latter is expressed with a Rayleigh enrichment factor, ε, and was −18.2 when all experiments were grouped to a common point of 42.8% TCE remaining. Although, decreases of ε to −20.7 were observed near complete degradation, our enrichment factors were significantly more negative than those reported for anaerobic dehalogenation of TCE. This indicates typical isotope fractionation for specific enzymatic mechanisms that can help to differentiate between degradation pathways.
Comparative and Prospective Study of Different Immune Parameters in Healthy Subjects at Risk for Tuberculosis and in Tuberculosis Patients
Authors: Portales-Pérez Diana P. , Baranda Lourdes , Layseca Esther , Fierro Nora Alma , de la Fuente Hortensia , Rosenstein Yvonne , González-Amaro Roberto 
Published: July 2002

ABSTRACTIt has not been fully elucidated which of the components of the immune response againstMycobacterium tuberculosisis indicative of resistance or susceptibility. The aim of this study was to identify an immune parameter that could be indicative of either resistance or susceptibility toM. tuberculosisinfection. We prospectively studied (three determinations, at months 0, 8, and 12) 15 patients with chronic pulmonary tuberculosis and 42 healthy individuals with a recent and frequent contact with tuberculosis patients. Peripheral blood mononuclear cells were stimulated with a whole-protein extract or the 30-kDa antigen ofM. tuberculosisfor 6 days, and several immune parameters were determined. No consistent differences between tuberculosis patients and healthy controls were detected in most immune parameters studied, including the expression of different activation antigens, cytokine secretion, lymphocyte proliferation, and nitric oxide production. However, the synthesis of tumor necrosis factor alpha, the intracellular detection of gamma interferon, and the apoptosis of monocytes under certain culture conditions tended to show clear-cut differences in cells from patients and controls (P< 0.05 in all cases for most determinations). Nevertheless, when results were analyzed on an individual basis, it was evident that a significant degree of overlapping of values from patients and controls occurred for all parameters studied. We conclude that although the immune parameters tested do not allow the identification of individuals susceptible toM. tuberculosis, the specificity and sensitivity of some of them could be improved through future studies.