bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature Responses to Infrared‐Loading and Water Table Manipulations in Peatland Mesocosms
Authors: Chen Jiquan , Bridgham Scott , Keller Jason , Pastor John , Noormets Asko , Weltzin Jake F. 
Published: September 2010

Abstract We initiated a multi‐factor global change experiment to explore the effects of infrared heat loading (HT) and water table level (WL) treatment on soil temperature (T) in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms (3.34–4.27 °C) but in May for the fen mesocosms (2.32–4.33 °C) over the 2‐year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48–2.03 °C over the 2‐year study period. In contrast, wetter fen mesocosms were generally cooler by 0.16–3.87 °C. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosms. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non‐frozen season.
Effect of growing media and their constituents on fungus gnat, Bradysia sp. nr. coprophila (Lintner) adults
Authors: CLOYD RAYMOND A. , DICKINSON AMY , LARSON RICHARD A. , MARLEY KAREN A. 
Published: September 2010

AbstractThis study was conducted to determine the attractiveness of two growing media, commonly utilized in greenhouses, to fungus gnat, Bradysia sp. nr. coprophila adults. The constituents of the most attractive growing medium tested were determined by gas chromatography analysis using a steam‐distillation procedure. We found that fungus gnat adults were more attracted to the growing medium, SB300 Universal Professional Growing Mix, which contains composted bark, than to another growing medium (Sunshine LC1 Mix) and their components when tested in a series of laboratory experiments using multiple‐choice experimental arenas. A higher percentage of fungus gnat adults were attracted to moist SB300 (92%) than SB300 growing medium that had been oven dried (8%). In addition, fungus gnat adults preferred SB300 although they had been reared on Sunshine LC1 Mix. When comparing the SB300 fresh from the bag to growing medium that had been pasteurized and moistened with water, gas chromatographic‐mass spectroscopic data showed there were declines in several terpenoid constituents as well as an increase in fatty acids and cyclosulfur. The results of this study indicate that B. sp. nr. coprophila adults prefer certain growing media, which may assist greenhouse producers in managing fungus gnats in crop production systems.
Microbiologic and Clinical Implications of Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing
Klebsiella pneumoniae
with or without Plasmid-Mediated AmpC β-Lactamase DHA-1
Authors: Lee Chen-Hsiang , Su Lin-Hui , Li Chia-Chin , Chien Chun-Chih , Tang Ya-Fen , Liu Jien-Wei 
Published: September 2010

ABSTRACT

Bacteremias caused by
Klebsiella pneumoniae
producing extended-spectrum beta-lactamase (ESBL-KP;
n
= 52) and producing both ESBL and AmpC-type DHA-1 beta-lactamase (ESBL-PMABL-KP;
n
= 20) were analyzed. Higher MIC
50
s and MIC
90
s for carbapenems, ciprofloxacin, and piperacillin-tazobactam were observed with ESBL-PMABL-KP than with ESBL-KP. Patients with oxyimino-β-lactam exposure and high modified Pitt bacteremia scores (HMPBSs) were at higher risk, while those with piperacillin-tazobactam and aminoglycoside exposure were at lower risk for ESBL-KP bacteremia. Patients with fluoroquinolone exposure, diabetes mellitus, and HMPBS were at higher risk, while those with aminoglycoside exposure were at lower risk, for ESBL-PMABL-KP bacteremia.
Multiplex Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Quantification in Human Plasma of Fluconazole, Itraconazole, Hydroxyitraconazole, Posaconazole, Voriconazole, Voriconazole-
N
-Oxide, Anidulafungin, and Caspofungin
Authors: Decosterd Laurent Arthur , Rochat Bertrand , Pesse Benoît , Mercier Thomas , Tissot Frédéric , Widmer Nicolas , Bille Jacques , Calandra Thierry , Zanolari Boris , Marchetti Oscar 
Published: September 2010

ABSTRACT

Therapeutic drug monitoring (TDM) may contribute to optimizing the efficacy and safety of antifungal therapy because of the large variability in drug pharmacokinetics. Rapid, sensitive, and selective laboratory methods are needed for efficient TDM. Quantification of several antifungals in a single analytical run may best fulfill these requirements. We therefore developed a multiplex ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method requiring 100 μl of plasma for simultaneous quantification within 7 min of fluconazole, itraconazole, hydroxyitraconazole, posaconazole, voriconazole, voriconazole-
N
-oxide, caspofungin, and anidulafungin. Protein precipitation with acetonitrile was used in a single extraction procedure for eight analytes. After reverse-phase chromatographic separation, antifungals were quantified by electrospray ionization-triple-quadrupole mass spectrometry by selected reaction monitoring detection using the positive mode. Deuterated isotopic compounds of azole antifungals were used as internal standards. The method was validated based on FDA recommendations, including assessment of extraction yields, matrix effect variability (<9.2%), and analytical recovery (80.1 to 107%). The method is sensitive (lower limits of azole quantification, 0.01 to 0.1 μg/ml; those of echinocandin quantification, 0.06 to 0.1 μg/ml), accurate (intra- and interassay biases of −9.9 to +5% and −4.0 to +8.8%, respectively), and precise (intra- and interassay coefficients of variation of 1.2 to 11.1% and 1.2 to 8.9%, respectively) over clinical concentration ranges (upper limits of quantification, 5 to 50 μg/ml). Thus, we developed a simple, rapid, and robust multiplex UPLC-MS/MS assay for simultaneous quantification of plasma concentrations of six antifungals and two metabolites. This offers, by optimized and cost-effective lab resource utilization, an efficient tool for daily routine TDM aimed at maximizing the real-time efficacy and safety of different recommended single-drug antifungal regimens and combination salvage therapies, as well as a tool for clinical research.
LmrS Is a Multidrug Efflux Pump of the Major Facilitator Superfamily from
Staphylococcus aureus
Authors: Floyd Jody L. , Smith Kenneth P. , Kumar Sanath H. , Floyd Jared T. , Varela Manuel F. 
Published: September 2010

ABSTRACT

A multidrug efflux pump designated LmrS (lincomycin resistance protein of
Staphylococcus aureus
), belonging to the major facilitator superfamily (MFS) of transporters, was cloned, and the role of LmrS in antimicrobial efflux was evaluated. The highest relative increase in MIC, 16-fold, was observed for linezolid and tetraphenylphosphonium chloride (TPCL), followed by an 8-fold increase for sodium dodecyl sulfate (SDS), trimethoprim, and chloramphenicol. LmrS has 14 predicted membrane-spanning domains and is homologous to putative lincomycin resistance proteins of
Bacillus
spp.,
Lactobacillus
spp., and
Listeria
spp.
Gene Therapeutic Approach for Inhibiting Hepatitis C Virus Replication Using a Recombinant Protein That Controls Interferon Expression
Authors: Joo Chul Hyun , Lee Uk , Nam Young Ran , Jung Jae U. , Lee Heuiran , Cho Young Keol , Kim Yoo Kyum 
Published: September 2010

ABSTRACT

The hepatitis C virus (HCV) is a continuing threat to public health. The systemic administration of interferon alpha with ribavirin is the only currently approved treatment. However, this treatment is associated with a wide spectrum of systemic side effects that limits its effectiveness; thus, there is an urgent need for new treatment modalities. In this study, we describe a novel anti-HCV strategy employing a recombinant transcription factor that we have engineered in such a way that NS3/4a viral protease controls its intracellular localization, thereby restoring interferon secretion specifically in cells infected with HCV. Proof-of-concept experiments validated the strategy, showing that the recombinant transcription factor was triggered to stimulate interferon promoter by NS3/4A and remained inactive in cells without NS3/4a. Using an adenovirus-associated viral vector delivery system, we found that the recombinant transcription factor inhibited HCV replication effectively
in vitro
in cultured cells.
Colistin Resistance in
Acinetobacter baumannii
Is Mediated by Complete Loss of Lipopolysaccharide Production
Authors: Moffatt Jennifer H. , Harper Marina , Harrison Paul , Hale John D. F. , Vinogradov Evgeny , Seemann Torsten , Henry Rebekah , Crane Bethany , St. Michael Frank , Cox Andrew D. , Adler Ben , Nation Roger L. , Li Jian , Boyce John D. 
Published: September 2010

ABSTRACT

Infections caused by multidrug-resistant (MDR) Gram-negative bacteria represent a major global health problem. Polymyxin antibiotics such as colistin have resurfaced as effective last-resort antimicrobials for use against MDR Gram-negative pathogens, including
Acinetobacter baumannii
. Here we show that
A. baumannii
can rapidly develop resistance to polymyxin antibiotics by complete loss of the initial binding target, the lipid A component of lipopolysaccharide (LPS), which has long been considered to be essential for the viability of Gram-negative bacteria. We characterized 13 independent colistin-resistant derivatives of
A. baumannii
type strain ATCC 19606 and showed that all contained mutations within one of the first three genes of the lipid A biosynthesis pathway:
lpxA
,
lpxC
, and
lpxD
. All of these mutations resulted in the complete loss of LPS production. Furthermore, we showed that loss of LPS occurs in a colistin-resistant clinical isolate of
A. baumannii
. This is the first report of a spontaneously occurring, lipopolysaccharide-deficient, Gram-negative bacterium.
Effect of Host Cells on Low- and Medium-Pressure UV Inactivation of Adenoviruses
Authors: Guo Huiling , Chu Xiaona , Hu Jiangyong 
Published: September 2010

ABSTRACT

UV disinfection is highly effective against most pathogens, with the exception of the adenoviruses (AD). To date, many studies have focused on low-pressure (LP) UV inactivation of AD, but little is known about the effect of medium-pressure (MP) UV inactivation of AD. Despite numerous studies of LP UV inactivation of AD, extreme variabilities in the LP UV dose requirements of AD had been observed because of differing experimental conditions used, such as the types of cell lines used for AD enumeration. This study therefore investigates the effect of three different host cell lines (PLC/PRF/5, human embryonic kidney 293 [HEK293], and XP17BE) on the LP and MP UV dose requirements of AD serotype 5 (AD5), AD40, and AD41 under similar experimental settings. Results showed that for 4-log inactivation of AD, LP UV and MP UV doses needed to be in the ranges of 123 to 182 mJ/cm
2
and 65 to 90 mJ/cm
2
, respectively, when HEK293 and PLC/PRF/5 cells were used for enumeration. The UV doses required for MP UV inactivation of AD were significantly lower than those required for LP UV inactivation (
P
value < 0.05). When different cell lines were used for enumeration, UV dose requirements for AD differed. AD were portrayed to be most susceptible to UV (LP UV doses of <57 mJ/cm
2
and MP UV doses of <42 mJ/cm
2
for 4-log AD inactivation) when the XP17BE cells were used as the host cell. The use of different cell lines for AD enumeration affected LP UV dose results more significantly than MP UV dose results (
P
value < 0.05). Cell line variability factors for LP UV disinfection (CL
LP
) and MP UV disinfection (CL
MP
) for AD5, AD40, and AD41 enumerated with HEK293, PLC/PRF/5, and XP17BE cells were in the ranges of 1.0 to 3.2 and 1.0 to 2.5, respectively.
Changes in Ultrastructure and Fourier Transform Infrared Spectrum of
Salmonella enterica
Serovar Typhimurium Cells after Exposure to Stress Conditions
Authors: Alvarez-Ordóñez A. , Prieto M. 
Published: September 2010

ABSTRACT

The effect of exposure to acid (pH 2.5), alkaline (pH 11.0), heat (55°C), and oxidative (40 mM H
2
O
2
) lethal conditions on the ultrastructure and global chemical composition of
Salmonella enterica
serovar Typhimurium CECT 443 cells was studied using transmission electron microscopy and Fourier transform infrared spectroscopy (FT-IR) combined with multivariate statistical methods (hierarchical cluster analysis and factor analysis). Infrared spectra exhibited marked differences in the five spectral regions for all conditions tested compared to those of nontreated control cells, which suggests the existence of a complex bacterial stress response in which modifications in a wide variety of cellular compounds are involved. The visible spectral changes observed in all of the spectral regions, together with ultrastructural changes observed by transmission electron microscopy and data obtained from membrane integrity tests, indicate the existence of membrane damage or alterations in membrane composition after heat, acid, alkaline, and oxidative treatments. Results obtained in this study indicate the potential of FT-IR spectroscopy to discriminate between intact and injured bacterial cells and between treatment technologies, and they show the adequacy of this technique to study the molecular aspects of bacterial stress response.
Dispersion of TiO
2
Nanoparticle Agglomerates by
Pseudomonas aeruginosa
Authors: Horst Allison M. , Neal Andrea C. , Mielke Randall E. , Sislian Patrick R. , Suh Won Hyuk , Mädler Lutz , Stucky Galen D. , Holden Patricia A. 
Published: September 2010

ABSTRACT

Engineered nanoparticles are increasingly incorporated into consumer products and are emerging as potential environmental contaminants. Upon environmental release, nanoparticles could inhibit bacterial processes, as evidenced by laboratory studies. Less is known regarding bacterial alteration of nanoparticles, including whether bacteria affect physical agglomeration states controlling nanoparticle settling and bioavailability. Here, the effects of an environmental strain of
Pseudomonas aeruginosa
on TiO
2
nanoparticle agglomerates formed in aqueous media are described. Environmental scanning electron microscopy and cryogenic scanning electron microscopy visually demonstrated bacterial dispersion of large agglomerates formed in cell culture medium and in marsh water. For experiments in cell culture medium, quantitative image analysis verified that the degrees of conversion of large agglomerates into small nanoparticle-cell combinations were similar for 12-h-growth and short-term cell contact experiments. Dispersion in cell growth medium was further characterized by size fractionation: for agglomerated TiO
2
suspensions in the absence of cells, 81% by mass was retained on a 5-μm-pore-size filter, compared to only 24% retained for biotic treatments. Filtrate cell and agglomerate sizes were characterized by dynamic light scattering, revealing that the average bacterial cell size increased from 1.4 μm to 1.9 μm because of nano-TiO
2
biosorption. High-magnification scanning electron micrographs showed that
P. aeruginosa
dispersed TiO
2
agglomerates by preferential biosorption of nanoparticles onto cell surfaces. These results suggest a novel role for bacteria in the environmental transport of engineered nanoparticles, i.e., growth-independent, bacterially mediated size and mass alterations of TiO
2
nanoparticle agglomerates.
The Spatial Factor, Rather than Elevated CO
2
, Controls the Soil Bacterial Community in a Temperate Forest Ecosystem
Authors: Ge Yuan , Chen Chengrong , Xu Zhihong , Oren Ram , He Ji-Zheng 
Published: September 2010

ABSTRACT

The global atmospheric carbon dioxide (CO
2
) concentration is expected to increase continuously over the next century. However, little is known about the responses of soil bacterial communities to elevated CO
2
in terrestrial ecosystems. This study aimed to partition the relative influences of CO
2
, nitrogen (N), and the spatial factor (different sampling plots) on soil bacterial communities at the free-air CO
2
enrichment research site in Duke Forest, North Carolina, by two independent techniques: an entirely sequencing-based approach and denaturing gradient gel electrophoresis. Multivariate regression tree analysis demonstrated that the spatial factor could explain more than 70% of the variation in soil bacterial diversity and 20% of the variation in community structure, while CO
2
or N treatment explains less than 3% of the variation. For the effects of soil environmental heterogeneity, the diversity estimates were distinguished mainly by the total soil N and C/N ratio. Bacterial diversity estimates were positively correlated with total soil N and negatively correlated with C/N ratio. There was no correlation between the overall bacterial community structures and the soil properties investigated. This study contributes to the information about the effects of elevated CO
2
and soil fertility on soil bacterial communities and the environmental factors shaping the distribution patterns of bacterial community diversity and structure in temperate forest soils.
Persistence of
Bacteroides
Species Populations in a River as Measured by Molecular and Culture Techniques
Authors: Ballesté Elisenda , Blanch Anicet R. 
Published: September 2010

ABSTRACT

Given the interest in
Bacteroides
species as microbial source tracking (MST) markers, and the limited knowledge of the survival of
Bacteroides
species in the environment, here we examine the survival of
Bacteroides fragilis
,
B. thetaiotaomicron
, and environmental species of
Bacteroides
by use of culture techniques and molecular tools. Two kinds of experiments were performed: (i) on-site experiments, in which bacteria were exposed to changes in the levels of several environmental parameters in a river, and (ii) microcosm assays in the laboratory, with controlled temperatures. On-site experiments showed different survival patterns for the cultivable
Bacteroides
strains.
B. fragilis
die-off rate was strongly affected by the combined effect of high temperatures and grazing predators, which were more active under warmer conditions. However, the survival rates of cultivable
B. thetaiotaomicron
and environmental
Bacteroides
spp. were more affected by dissolved oxygen (DO) concentration in water. Environmental
Bacteroides
strains survived longer than either type strain, due to better adaptation to environmental conditions. However, the period of their survival was shorter than that observed for fecal coliforms and enterococci, suggesting
Bacteroides
species as markers of recent fecal pollution. The total
Bacteroides
species were detected by molecular techniques throughout the experiment in winter, but they were detected on only two or three days in the summer. This indicates that temperature is the main factor affecting DNA degradation, regardless of species. The use of microcosms in the laboratory also pointed to temperature as the main factor affecting
Bacteroides
survival, regardless of species. However, the conditions in the laboratory may mask the effects of the environmental factors and their interactions. The observed variability in die-off rate as a function of the species analyzed, the experimental conditions, and the methodology used should be taken into consideration in future persistence studies.
Detection of Protozoan Hosts for
Legionella pneumophila
in Engineered Water Systems by Using a Biofilm Batch Test
Authors: Valster Rinske M. , Wullings Bart A. , van der Kooij Dick 
Published: September 2010

ABSTRACT

Legionella pneumophila
proliferates in aquatic habitats within free-living protozoa, 17 species of which have been identified as hosts by using
in vitro
experiments. The present study aimed at identifying protozoan hosts for
L. pneumophila
by using a biofilm batch test (BBT). Samples (600 ml) collected from 21 engineered freshwater systems, with added polyethylene cylinders to promote biofilm formation, were inoculated with
L. pneumophila
and subsequently incubated at 37°C for 20 days. Growth of
L. pneumophila
was observed in 16 of 18 water types when the host protozoan
Hartmannella vermiformis
was added. Twelve of the tested water types supported growth of
L. pneumophila
or indigenous
Legionella anisa
without added
H. vermiformis
. In 12 of 19 BBT flasks
H. vermiformis
was indicated as a host, based on the ratio between maximum concentrations of
L. pneumophila
and
H. vermiformis
, determined with quantitative PCR (Q-PCR), and the composition of clone libraries of partial 18S rRNA gene fragments. Analyses of 609 eukaryotic clones from the BBTs revealed that 68 operational taxonomic units (OTUs) showed the highest similarity to free-living protozoa. Forty percent of the sequences clustering with protozoa showed ≥99.5% similarity to
H. vermiformis
. None of the other protozoa serving as hosts in
in vitro
studies were detected in the BBTs. In several tests with growth of
L. pneumophila
, the protozoa
Diphylleia rotans
,
Echinamoeba thermarum
, and
Neoparamoeba
sp. were identified as candidate hosts.
In vitro
studies are needed to confirm their role as hosts for
L. pneumophila
. Unidentified protozoa were implicated as hosts for uncultured
Legionella
spp. grown in BBT flasks at 15°C.
Functionality of Sortase A in
Lactococcus lactis
Authors: Dieye Yakhya , Oxaran Virginie , Ledue-Clier Florence , Alkhalaf Walid , Buist Girbe , Juillard Vincent , Lee Chang Won , Piard Jean-Christophe 
Published: September 2010

ABSTRACT

Lactococcus lactis
IL1403 harbors a putative sortase A (SrtA) and 11 putative sortase substrates that carry the canonical LPXTG signature of such substrates. We report here on the functionality of SrtA to anchor five LPXTG substrates to the cell wall, thus suggesting that SrtA is the housekeeping sortase in
L. lactis
IL1403.