bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Atovaquone and Diospyrin-Based Drugs on Ubiquinone Biosynthesis in
Pneumocystis carinii
Organisms
Authors: Kaneshiro Edna S. , Sul Donggeun , Hazra Banasri 
Published: April 2009

ABSTRACT

The naphthoquinone atovaquone is effective against
Plasmodium
and
Pneumocystis carinii carinii
. In
Plasmodium
, the primary mechanism of drug action is an irreversible binding to the mitochondrial cytochrome
bc
1
complex as an analog of ubiquinone. Blockage of the electron transport chain ultimately inhibits de novo pyrimidine biosynthesis since dihydroorotate dehydrogenase, a key enzyme in pyrimidine biosynthesis, is unable to transfer electrons to ubiquinone. In the present study, the effect of atovaquone was examined on
Pneumocystis carinii carinii
coenzyme Q biosynthesis (rather than electron transport and respiration) by measuring its effect on the incorporation of radiolabeled
p
-hydroxybenzoate into ubiquinone in vitro. A triphasic dose-response was observed, with inhibition at 10 nM and then stimulation up to 0.2 μM, followed by inhibition at 1 μM. Since other naphthoquinone drugs may also act as analogs of ubiquinone, diospyrin and two of its derivatives were also tested for their effects on ubiquinone biosynthesis in
P. carinii carinii
. In contrast to atovaquone, these drugs did not inhibit the incorporation of
p
-hydroxybenzoate into
P. carinii carinii
ubiquinone.
Postantibiotic Effects of Grepafloxacin Compared to Those of Five Other Agents against 12 Gram-Positive and -Negative Bacteria
Authors: Spangler Sheila K. , Bajaksouzian Saralee , Jacobs Michael R. , Appelbaum Peter C. 
Published: April 2009

ABSTRACT
The postantibiotic effect (PAE) (10× the MIC) and the postantibiotic sub-MIC effects (0.125, 0.25, and 0.5× the MIC) were determined for six compounds against 12 strains. Measurable PAEs ranged between 0 and 1.8 h for grepafloxacin, 0 and 2.2 h for ciprofloxacin, 0 and 3.1 h for levofloxacin, 0 and 2.2 h for sparfloxacin, 0 and 2.4 h for amoxicillin-clavulanate and 0 and 4.8 h for clarithromycin. Reexposure to subinhibitory concentrations increased the PAEs against some strains.
Therapeutic Efficacy of Human Macrophage Colony-Stimulating Factor, Used Alone and in Combination with Antifungal Agents, in Mice with SystemicCandida albicansInfection
Authors: Kuhara Tetsuya , Uchida Katsuhisa , Yamaguchi Hideyo 
Published: April 2009

ABSTRACTWe examined the in vivo activity of human macrophage colony-stimulating factor (hM-CSF) against lethalCandida albicansinfection in mice. InC. albicans-infected mice which had been immunosuppressed with cyclophosphamide, treatment with hM-CSF at a daily dose of 8 × 105units/kg of body weight or greater slightly but significantly prolonged survival. Furthermore, the therapeutic efficacy of amphotericin B (AMPH-B) in infected mice was enhanced by its combined use with hM-CSF, while that of fluconazole (FLCZ) was not. The activities of peritoneal macrophages and neutrophils from mice administered hM-CSF plus AMPH-B in combination for inhibition of hyphal growth ofC. albicanscells and intracellular phagocytosis and killing of the cells were greater than those of comparable phagocytic cells from control mice to which hM-CSF plus AMPH-B was not administered. These results suggest that intravenous administration of hM-CSF augments the efficacy of AMPH-B by enhancing the antifungal activities of macrophages and neutrophils. Therefore, it is expected that therapy with the combination AMPH-B and hM-CSF could improve the efficacy of AMPH-B and reduce the therapeutic dose of the antifungal drug that is required.
satG
, Conferring Resistance to Streptogramin A, Is Widely Distributed in
Enterococcus faecium
Strains but Not in Staphylococci
Authors: Haroche Julien , Allignet Jeanine , Aubert Sylvie , Van Den Bogaard Anthony E. , El Solh Névine 
Published: April 2009

ABSTRACT

A gene almost identical to
satG
was isolated from an
Enterococcus faecium
strain. This gene was transferred to a
Staphylococcus aureus
recipient strain where it conferred resistance to streptogramin A.
satG
was found to be widely distributed among
E. faecium
strains but not detected among staphylococci.
Sequence Analysis of ARI-1, a Novel OXA β-Lactamase, Responsible for Imipenem Resistance in
Acinetobacter baumannii
6B92
Authors: Donald Helen M. , Scaife Wendy , Amyes Sebastian G. B. , Young Hilary-Kay 
Published: April 2009

ABSTRACT

The sequence of the
bla
ARI-1
gene from imipenem-resistant
Acinetobacter baumannii
6B92 has been determined. The structural gene encodes a 273-amino-acid protein which is most related to the OXA class D β-lactamases. The conserved S-T-F-K and K-T-G motifs were identified in the ARI-1 protein sequence, also named OXA-23, but significantly, a point mutation (Y→F) was identified in the Y-G-N conserved motif, also known to function in the active site.
Δ
12
-Prostaglandin J
2
Is a Potent Inhibitor of Influenza A Virus Replication
Authors: Pica Francesca , Palamara Anna Teresa , Rossi Antonio , De Marco Alessandra , Amici Carla , Santoro M. Gabriella 
Published: April 2009

ABSTRACT

9-Deoxy-Δ
9
,Δ
12
-13,14-dihydro-prostaglandin D
2
(Δ
12
-PGJ
2
), a natural cyclopentenone metabolite of prostaglandin D
2
, is shown to possess therapeutic efficacy against influenza A virus A/PR8/34 (H1N1) infection in vitro and in vivo. The results indicate that the antiviral activity is associated with induction of cytoprotective heat shock proteins and suggest novel strategies for treatment of influenza virus infection.
Bioavailability of Aciclovir after Oral Administration of Aciclovir and Its Prodrug Valaciclovir to Patients with Leukopenia after Chemotherapy
Authors: Steingrimsdottir Hlif , Gruber Astrid , Palm Carina , Grimfors Gunnar , Kalin Mats , Eksborg Staffan 
Published: April 2009

ABSTRACT
The median bioavailabilities of aciclovir after administration of aciclovir and its prodrug valaciclovir were 21.5 and 70.1%, respectively, in 12 patients with malignant hematological diseases with leukopenia after chemotherapy. The interindividual variations of the bioavailability were 48.5 and 21.0% after administration of aciclovir and valaciclovir, respectively. Neither the bioavailability nor the interindividual variation of area under the concentration-time curve of oral aciclovir or valaciclovir differed from that reported in healthy volunteers.
Complete Sequence of a β-Lactamase-Encoding Plasmid in
Neisseria meningitidis
Authors: Bäckman Anders , Orvelid Paula , Vazquez Julio A. , Sköld Ola , Olcén Per 
Published: April 2009

ABSTRACT

Identical β-lactamase-encoding (TEM-1) plasmids were found in two different clinical
Neisseria meningitidis
strains. They were completely sequenced (5,597 bp) and designated pAB6. The plasmid is almost identical to
Neisseria gonorrhoeae
plasmid pJD5 (5,599 kb) and may have been picked up from a gonococcus in vivo.
A Novel Integron in
Salmonella enterica
Serovar Enteritidis, Carrying the
bla
DHA-1
Gene and Its Regulator Gene
ampR
, Originated from
Morganella morganii
Authors: Verdet Charlotte , Arlet Guillaume , Barnaud Guilene , Lagrange Philippe H. , Philippon Alain 
Published: April 2009

ABSTRACT

The genetic organization of the gene coding for DHA-1 and the corresponding
ampR
gene was determined by PCR mapping. These genes have been mobilized from the
Morganella morganii
chromosome and inserted into a complex
sulI
-type integron, similar to In6 and In7. However, they are not themselves mobile cassettes. This integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for
bla
CMY-1
and
bla
MOX-1
.
Penetration of Rufloxacin into the Cerebrospinal Fluid in Patients with Inflamed and Uninflamed Meninges
Authors: Moretti Maria Vittoria , Pauluzzi Sergio , Cesana Marina 
Published: April 2009

ABSTRACTForty-four patients scheduled for lumbar puncture (LP) were recruited to determine the level of penetration of orally administered rufloxacin into cerebrospinal fluid (CSF). The patients were divided into three clinical groups: those with normal CSF (groups A1dand A7d), those with aseptic meningitis (group B), and those with bacterial meningitis (group C). Members of group A1dreceived a single 400-mg rufloxacin dose, while group A7d, B, and C constituents had a multiple-dose regimen (one 400-mg dose, followed by one 200-mg dose daily for 6 days). LP was performed on group A1dmembers 5 h after they had received treatment, while for group A7dit was undertaken 5 h after administration of the last dose. For group B, LP was performed 5 h after the first and the last doses, whereas for group C it was undertaken after the first, fourth, and last doses. Concentrations of rufloxacin in simultaneously collected CSF and plasma samples were determined. Mean CSF/plasma rufloxacin concentration ratios ranged from 0.57 to 0.84, depending on the study group. A higher, but not statistically significant, degree of penetration into CSF was observed in patients with bacterial meningitis than in those with normal CSF or aseptic meningitis. These data indicate that rufloxacin diffuses efficiently into the CSF of patients with either inflamed or uninflamed meninges.
Removal of Nitrate from Groundwater by Cyanobacteria: Quantitative Assessment of Factors Influencing Nitrate Uptake
Authors: Hu Qiang , Westerhoff Paul , Vermaas Wim 
Published: April 2009

ABSTRACT

The feasibility of biologically removing nitrate from groundwater was tested by using cyanobacterial cultures in batch mode under laboratory conditions. Results demonstrated that nitrate-contaminated groundwater, when supplemented with phosphate and some trace elements, can be used as growth medium supporting vigorous growth of several strains of cyanobacteria. As cyanobacteria grew, nitrate was removed from the water. Of three species tested,
Synechococcus
sp. strain PCC 7942 displayed the highest nitrate uptake rate, but all species showed rapid removal of nitrate from groundwater. The nitrate uptake rate increased proportionally with increasing light intensity up to 100 μmol of photons m
−2
s
−1
, which parallels photosynthetic activity. The nitrate uptake rate was affected by inoculum size (i.e., cell density), fixed-nitrogen level in the cells in the inoculum, and aeration rate, with vigorously aerated, nitrate-sufficient cells in mid-logarithmic phase having the highest long-term nitrate uptake rate. Average nitrate uptake rates up to 0.05 mM NO
3
−
h
−1
could be achieved at a culture optical density at 730 nm of 0.5 to 1.0 over a 2-day culture period. This result compares favorably with those reported for nitrate removal by other cyanobacteria and algae, and therefore effective nitrate removal from groundwater using this organism could be anticipated on large-scale operations.
Genetic Diversity of Clinical and Environmental Isolates of
Vibrio cholerae
Determined by Amplified Fragment Length Polymorphism Fingerprinting
Authors: Jiang Sunny C. , Matte Maria , Matte Glavur , Huq Anwar , Colwell Rita R. 
Published: April 2009

ABSTRACT

Vibrio cholerae
, the causative agent of major epidemics of diarrheal disease in Bangladesh, South America, Southeastern Asia, and Africa, was isolated from clinical samples and from aquatic environments during and between epidemics over the past 20 years. To determine the evolutionary relationships and molecular diversity of these strains, in order to understand sources, origin, and epidemiology, a novel DNA fingerprinting technique, amplified fragment length polymorphism (AFLP), was employed. Two sets of restriction enzyme-primer combinations were tested for fingerprinting of
V. cholerae
serogroup O1, O139, and non-O1, O139 isolates. Amplification of
Hin
dIII- and
Taq
I-digested genomic DNA produced 30 to 50 bands for each strain. However, this combination, although capable of separating environmental isolates of O1 and non-O1 strains, was unable to distinguish between O1 and O139 clinical strains. This result confirmed that clinical O1 and O139 strains are genetically closely related. On the other hand, AFLP analyses of restriction enzyme
Apa
I- and
Taq
I-digested genomic DNA yielded 20 to 30 bands for each strain, but were able to separate O1 from O139 strains. Of the 74 strains examined with the latter combination, 26 serogroup O1 strains showed identical banding patterns and were represented by the O1 El Tor strain of the seventh pandemic. A second group, represented by O139 Bengal, included 12 strains of O139 clinical isolates, with 7 from Thailand, 3 from Bangladesh, and 2 from India. Interestingly, an O1 clinical isolate from Africa also grouped with the O139 clinical isolates. Eight clinical O1 isolates from Mexico grouped separately from the O1 El Tor of the seventh pandemic, suggesting an independent origin of these isolates. Identical fingerprints were observed between an O1 environmental isolate from a river in Chile and an O1 clinical strain from Kenya, both isolated more than 10 years apart. Both strains were distinct from the O1 seventh pandemic strain. Two O139 clinical isolates from Africa clustered with environmental non-O1 isolates, independent of other O139 strains included in the study. These results suggest that although a single clone of pathogenic
V. cholerae
appears responsible for many cases of cholera in Asia, Africa, and Latin America during the seventh pandemic, other cases of clinical cholera were caused by toxigenic
V. cholerae
strains that appear to have been derived locally from environmental O1 or non-O1 strains.
Oxygen Activation during Oxidation of Methoxyhydroquinones by Laccase from
Pleurotus eryngii
Authors: Guillén Francisco , Muñoz Carmen , Gómez-Toribio Víctor , Martínez Angel T. , Jesús Martínez María 
Published: April 2009

ABSTRACT

Oxygen activation during oxidation of the lignin-derived hydroquinones 2-methoxy-1,4-benzohydroquinone (MBQH
2
) and 2,6-dimethoxy-1,4-benzohydroquinone (DBQH
2
) by laccase from
Pleurotus eryngii
was examined. Laccase oxidized DBQH
2
more efficiently than it oxidized MBQH
2
; both the affinity and maximal velocity of oxidation were higher for DBQH
2
than for MBQH
2
. Autoxidation of the semiquinones produced by laccase led to the activation of oxygen, producing superoxide anion radicals (Q
·−
+ O
2
↔ Q + O
2
·−
). As this reaction is reversible, its existence was first noted in studies of the effect of systems consuming and producing O
2
·−
on quinone formation rates. Then, the production of H
2
O
2
in laccase reactions, as a consequence of O
2
·−
dismutation, confirmed that semiquinones autoxidized. The highest H
2
O
2
levels were obtained with DBQH
2
, indicating that DBQ
·−
autoxidized to a greater extent than did MBQ
·−
. Besides undergoing autoxidation, semiquinones were found to be transformed into quinones via dismutation and laccase oxidation. Two ways of favoring semiquinone autoxidation over dismutation and laccase oxidation were increasing the rate of O
2
·−
consumption with superoxide dismutase (SOD) and recycling of quinones with diaphorase (a reductase catalyzing the divalent reduction of quinones). These two strategies made the laccase reaction conditions more natural, since O
2
·−
, besides undergoing dismutation, reacts with Mn
2+
, Fe
3+
, and aromatic radicals. In addition, quinones are continuously reduced by the mycelium of white-rot fungi. The presence of SOD in laccase reactions increased the extent of autoxidation of 100 μM concentrations of MBQ
·−
and DBQ
·−
from 4.5 to 30.6% and from 19.6 to 40.0%, respectively. With diaphorase, the extent of MBQ
·−
autoxidation rose to 13.8% and that of DBQ
·−
increased to 39.9%.
Artificial and Solar UV Radiation Induces Strand Breaks and Cyclobutane Pyrimidine Dimers in
Bacillus subtilis
Spore DNA
Authors: Slieman Tony A. , Nicholson Wayne L. 
Published: April 2009

ABSTRACT

The loss of stratospheric ozone and the accompanying increase in solar UV flux have led to concerns regarding decreases in global microbial productivity. Central to understanding this process is determining the types and amounts of DNA damage in microbes caused by solar UV irradiation. While UV irradiation of dormant
Bacillus subtilis
endospores results mainly in formation of the “spore photoproduct” 5-thyminyl-5,6-dihydrothymine, genetic evidence indicates that an additional DNA photoproduct(s) may be formed in spores exposed to solar UV-B and UV-A radiation (Y. Xue and W. L. Nicholson, Appl. Environ. Microbiol. 62:2221–2227, 1996). We examined the occurrence of double-strand breaks, single-strand breaks, cyclobutane pyrimidine dimers, and apurinic-apyrimidinic sites in spore DNA under several UV irradiation conditions by using enzymatic probes and neutral or alkaline agarose gel electrophoresis. DNA from spores irradiated with artificial 254-nm UV-C radiation accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, while DNA from spores exposed to artificial UV-B radiation (wavelengths, 290 to 310 nm) accumulated only cyclobutane pyrimidine dimers. DNA from spores exposed to full-spectrum sunlight (UV-B and UV-A radiation) accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, whereas DNA from spores exposed to sunlight from which the UV-B component had been removed with a filter (“UV-A sunlight”) accumulated only single-strand breaks and double-strand breaks. Apurinic-apyrimidinic sites were not detected in spore DNA under any of the irradiation conditions used. Our data indicate that there is a complex spectrum of UV photoproducts in DNA of bacterial spores exposed to solar UV irradiation in the environment.
Natural Transformation of
Acinetobacter
sp. Strain BD413 with Cell Lysates of
Acinetobacter
sp.,
Pseudomonas fluorescens
, and
Burkholderia cepacia
in Soil Microcosms
Authors: Nielsen Kaare M. , Smalla Kornelia , van Elsas Jan D. 
Published: April 2009

ABSTRACT

To elucidate the biological significance of dead bacterial cells in soil to the intra- and interspecies transfer of gene fragments by natural transformation, we have exposed the kanamycin-sensitive recipient
Acinetobacter
sp. strain BD413(pFG4) to lysates of the kanamycin-resistant donor bacteria
Acinetobacter
spp.,
Pseudomonas fluorescens
, and
Burkholderia cepacia
. Detection of gene transfer was facilitated by the recombinational repair of a partially (317 bp) deleted kanamycin resistance gene in the recipient bacterium. The investigation revealed a significant potential of these DNA sources to transform
Acinetobacter
spp. residing both in sterile and in nonsterile silt loam soil. Heat-treated (80°C, 15 min) cell lysates were capable of transforming strain BD413 after 4 days of incubation in sterile soil and for up to 8 h in nonsterile soil. Transformation efficiencies obtained in vitro and in situ with the various lysates were similar to or exceeded those obtained with conventionally purified DNA. The presence of cell debris did not inhibit transformation in soil, and the debris may protect DNA from rapid biological inactivation. Natural transformation thus provides
Acinetobacter
spp. with an efficient mechanism to access genetic information from different bacterial species in soil. The relatively short-term biological activity (e.g., transforming activity) of chromosomal DNA in soil contrasts the earlier reported long-term physical stability of DNA, where fractions have been found to persist for several weeks in soil. Thus, there seems to be a clear difference between the physical and the functional significance of chromosomal DNA in soil.
Dehalogenation of Haloalkanes byMycobacterium tuberculosisH37Rv and Other Mycobacteria
Authors: Jesenská Andrea , Sedlác̆ek Ivo , Damborský Jir̆í 
Published: April 2009

ABSTRACTHaloalkane dehalogenases convert haloalkanes to their corresponding alcohols by a hydrolytic mechanism. To date, various haloalkane dehalogenases have been isolated from bacteria colonizing environments that are contaminated with halogenated compounds. A search of current databases with the sequences of these known haloalkane dehalogenases revealed the presence of three different genes encoding putative haloalkane dehalogenases in the genome of the human parasiteMycobacterium tuberculosisH37Rv. The ability ofM. tuberculosisand several other mycobacterial strains to dehalogenate haloaliphatic compounds was therefore studied. Intact cells ofM. tuberculosisH37Rv were found to dehalogenate 1-chlorobutane, 1-chlorodecane, 1-bromobutane, and 1,2-dibromoethane. Nine isolates of mycobacteria from clinical material and four strains from a collection of microorganisms were found to be capable of dehalogenating 1,2-dibromoethane. Crude extracts prepared from two of these strains,Mycobacterium aviumMU1 andMycobacterium smegmatisCCM 4622, showed broad substrate specificity toward a number of halogenated substrates. Dehalogenase activity in the absence of oxygen and the identification of primary alcohols as the products of the reaction suggest a hydrolytic dehalogenation mechanism. The presence of dehalogenases in bacterial isolates from clinical material, including the species colonizing both animal tissues and free environment, indicates a possible role of parasitic microorganisms in the distribution of degradation genes in the environment.
Sources of
Escherichia coli
in a Coastal Subtropical Environment
Authors: Solo-Gabriele Helena M. , Wolfert Melinda A. , Desmarais Timothy R. , Palmer Carol J. 
Published: April 2009

ABSTRACT

Sources of
Escherichia coli
in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in
E. coli
concentrations as well as experiments conducted under laboratory-controlled conditions.
E. coli
from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high
E. coli
levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that
E. coli
entered the river in a large pulse during storm conditions. After the storm,
E. coli
levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of
E. coli
concentrations between storm events was caused by the growth of
E. coli
within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil
E. coli
concentrations. The ability of
E. coli
to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of
E. coli
to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of
E. coli
was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems,
E. coli
concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of
E. coli
as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments.