bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring unfractionated heparin therapy in dogs by measuring thrombin generation
Authors: Allegret Virginie , Dunn Marilyn , Bédard Christian 
Published: February 2011

Background: The calibrated automated thrombogram (CAT), an assay that permits measurement of thrombin generation in plasma, may be useful in studying hemostatic disorders and anticoagulant therapy in animals.Objectives: The aims of the study were to measure thrombin generation in healthy Beagle dogs and to evaluate the potential use of the CAT assay for monitoring therapy with unfractionated heparin (UFH).Methods: Individual platelet‐poor plasma samples and a plasma pool from 20 healthy adult Beagles were prepared. Serial UFH plasma dilutions were used to establish an in vitro heparin‐sensitivity curve. The pharmacodynamic effects of heparin in vivo were evaluated in Beagles using the CAT assay to measure thrombin generation with tissue factor at a concentration of 5 pM for initiation.Results: In healthy Beagles, the range of endogenous thrombin potential (ETP) was 238.7–414.0 nM/min (mean ± SD, 340.4 ± 63.1 nM/min). ETP intra‐assay and interassay variations were 7.1% and 12.9%, respectively. In vitro, a UFH concentration ≥0.4 U/mL resulted in total inhibition of thrombin generation. In vivo, the maximal effect of UFH on ETP was observed at 170 ± 36 minutes (range, 120–210 minutes) and resulted in a decrease in ETP of 38.5 ± 7.8% (range, 26.5–50.3%). In 210–420 minutes, ETP returned to baseline in 5 dogs.Conclusion: Our study demonstrates that thrombin generation can be measured in canine plasma and may be useful in assessing the degree of anticoagulation provided by UFH.
Moderately and slightly siderophile element constraints on the depth and extent of melting in early Mars
Authors: RIGHTER Kevin , CHABOT Nancy L. 
Published: February 2011

Abstract–The thermal history of Mars during accretion and differentiation is important for understanding some fundamental aspects of its evolution such as crust formation, mantle geochemistry, chronology, volatile loss and interior degassing, and atmospheric development. In light of data from new Martian meteorites and exploration rovers, we have made a new estimate of Martian mantle siderophile element depletions. New high pressure and temperature metal–silicate experimental partitioning data and expressions are also available. Using these new constraints, we consider the conditions under which the Martian mantle may have equilibrated with metallic liquid. The resulting conditions that best satisfy six siderophile elements—Ni, Co, W, Mo, P, and Ga—and are consistent with the solidus and liquidus of the Martian mantle phase diagram are a pressure of 14 ± 3 GPa and temperature of 2100 ± 200 K. The Martian mantle depletions of Cr and V are also consistent with metal–silicate equilibration in this pressure and temperature range if deep mantle silicate phases are also taken into account. The results are not consistent with either metal–silicate equilibrium at the surface or at the current‐day Martian core–mantle boundary. Recent measurements and modeling have concluded that deep (∼17 GPa or 1350 km) mantle melting is required to explain isotopic data for Martian meteorites and the nature of differentiation into core, mantle, and crust. This is in general agreement with our estimates of the conditions of Martian core formation based on siderophile elements that result in an intermediate depth magma ocean scenario for metal–silicate equilibrium.
How can we enhance girls’ interest in scientific topics?
Authors: Kerger Sylvie , Martin Romain , Brunner Martin 
Published: February 2011

Background. Girls are considerably less interested in scientific subjects than boys. One reason may be that scientific subjects are considered to be genuinely masculine. Thus, being interested in science may threaten the self‐perception of girls as well as the femininity of their self‐image.Aims. If scientific topics that are considered to be stereotypically feminine were chosen, however, this potential threat might be overcome which, in turn, might lead to an increase in girls’ interest in science. This hypothesis was empirically tested by means of two studies.Sample. Participants were 294 (Study 1) and 190 (Study 2) Grade 8 to Grade 9 students.Method. Gender differences in students’ interest in masculine and feminine topics were investigated for a range of scientific concepts (Study 1) as well as for a given scientific concept (Study 2) for four scientific subjects (i.e., biology, physics, information technology, and statistics), respectively.Results. Both studies indicated that the mean level of girls’ scientific interest was higher when scientific concepts were presented in the context of feminine topics and boys’ level of scientific interests was higher when scientific concepts were presented in the context of masculine topics.Conclusion. Girls’ interest in science could be substantially increased by presenting scientific concepts in the context of feminine topics. Gender differences as well as individual differences in the level of interest in scientific topics may be taken into account by creating learning environments in which students could select the context in which a certain scientific concept is embedded.
Achievement goals as mediators of the relationship between competence beliefs and test anxiety
Authors: Putwain David W. , Symes Wendy 
Published: February 2011

Background. Previous work suggests that the expectation of failure is related to higher test anxiety and achievement goals grounded in a fear of failure.Aim. To test the hypothesis, based on the work of Elliot and Pekrun (2007), that the relationship between perceived competence and test anxiety is mediated by achievement goal orientations.Sample. Self‐report data were collected from 275 students in post‐compulsory education following courses in A Level Psychology.Results. Competence beliefs were inversely related to the worry and tension components of test anxiety, both directly and indirectly through a performance‐avoidance goal orientation. A mastery‐avoidance goal orientation offered an indirect route from competence beliefs to worry only.Conclusion. These findings provide partial support for Elliot and Pekrun's (2007) model. Although significant mediating effects were found for mastery‐avoidance and performance‐avoidance goals, they were small and there may be other mechanisms to account for the relations between competence beliefs and test anxiety.
Multiple Approaches To Enhance the Cultivability of Bacteria Associated with the Marine Sponge
Haliclona
(
gellius
) sp
Authors: Sipkema Detmer , Schippers Klaske , Maalcke Wouter J. , Yang Yu , Salim Sina , Blanch Harvey W. 
Published: February 2011

ABSTRACT

Three methods were examined to cultivate bacteria associated with the marine sponge
Haliclona
(
gellius
) sp.: agar plate cultures, liquid cultures, and floating filter cultures. A variety of oligotrophic media were employed, including media with aqueous and organic sponge extracts, bacterial signal molecules, and siderophores. More than 3,900 isolates were analyzed, and 205 operational taxonomic units (OTUs) were identified. Media containing low concentrations of mucin or a mixture of peptone and starch were most successful for the isolation of diversity, while the commonly used marine broth did not result in a high diversity among isolates. The addition of antibiotics generally led to a reduced diversity on plates but yielded different bacteria than other media. In addition, diversity patterns of isolates from agar plates, liquid cultures, and floating filters were significantly different. Almost 89% of all isolates were
Alphaproteobacteria
; however, members of phyla that are less commonly encountered in cultivation studies, such as
Planctomycetes
,
Verrucomicrobia
, and
Deltaproteobacteria
, were isolated as well. The sponge-associated bacteria were categorized into three different groups. The first group represented OTUs that were also obtained in a clone library from previously analyzed sponge tissue (group 1). Furthermore, we distinguished OTUs that were obtained from sponge tissue (in a previous study) but not from sponge isolates (group 2), and there were also OTUs that were not obtained from sponge tissue but were obtained from sponge isolates (group 3). The 17 OTUs categorized into group 1 represented 10 to 14% of all bacterial OTUs that were present in a large clone library previously generated from
Haliclona
(
gellius
) sp. sponge tissue, which is higher than previously reported cultivability scores for sponge-associated bacteria. Six of these 17 OTUs were not obtained from agar plates, which underlines that the use of multiple cultivation methods is worthwhile to increase the diversity of the cultivable microorganisms from sponges.
Parameters Affecting Spore Recovery from Wipes Used in Biological Surface Sampling
Authors: Da Silva Sandra M. , Filliben James J. , Morrow Jayne B. 
Published: February 2011

ABSTRACT

The need for the precise and reliable collection of potential biothreat contaminants has motivated research in developing a better understanding of the variability in biological surface sampling methods. In this context, the objective of this work was to determine parameters affecting the efficiency of extracting
Bacillus anthracis
Sterne spores from commonly used wipe sampling materials and to describe performance using the interfacial energy concept. In addition, surface thermodynamics was applied to understand and predict surface sampling performance. Wipe materials were directly inoculated with known concentrations of
B. anthracis
spores and placed into extraction solutions, followed by sonication or vortexing. Experimental factors investigated included wipe material (polyester, cotton, and polyester-rayon), extraction solution (sterile deionized water [H
2
O], deionized water with 0.04% Tween 80 [H
2
O-T], phosphate-buffered saline [PBS], and PBS with 0.04% Tween 80 [PBST]), and physical dissociation method (vortexing or sonication). The most efficient extraction from wipes was observed for solutions containing the nonionic surfactant Tween 80. The increase in extraction efficiency due to surfactant addition was attributed to an attractive interfacial energy between Tween 80 and the centrifuge tube wall, which prevented spore adhesion. Extraction solution significantly impacted the extraction efficiency, as determined by statistical analysis (
P
< 0.05). Moreover, the extraction solution was the most important factor in extraction performance, followed by the wipe material. Polyester-rayon was the most efficient wipe material for releasing spores into solution by rank; however, no statistically significant difference between polyester-rayon and cotton was observed (
P
> 0.05). Vortexing provided higher spore recovery in H
2
O and H
2
O-T than sonication, when all three wipe materials and the reference control were considered (
P
< 0.05).
Validation of a
Clostridium
Endospore Viability Assay and Analysis of Greenland Ices and Atacama Desert Soils
Authors: Yang Wan-Wan , Ponce Adrian 
Published: February 2011

ABSTRACT

A microscopy-based endospore viability assay (micro-EVA) capable of enumerating germinable
Clostridium
endospores (GCEs) in less than 30 min has been validated and employed to determine GCE concentrations in Greenland ices and Atacama Desert soils. Inoculation onto agarose doped with Tb
3+
and
d
-alanine triggers
Clostridium
spore germination and the concomitant release of ∼10
8
molecules of dipicolinic acid (DPA) per endospore, which, under pulsed UV excitation, enables enumeration of resultant green Tb
3+
-DPA luminescent spots as GCEs with time-gated luminescence microscopy. The intensity time courses of the luminescent spots were characteristic of stage I
Clostridium
spore germination dynamics. Micro-EVA was validated against traditional CFU cultivation from 0 to 1,000 total endospores/ml (i.e., phase-bright bodies/ml), yielding 56.4% ± 1.5% GCEs and 43.0% ± 1.0% CFU. We also show that
d
-alanine serves as a
Clostridium
-specific germinant (three species tested) that inhibits
Bacillus
germination of spores (five species tested) in that endospore concentration regime. Finally, GCE concentrations in Greenland ice cores and Atacama Desert soils were determined with micro-EVA, yielding 1 to 2 GCEs/ml of Greenland ice (versus <1 CFU/ml after 6 months of incubation) and 66 to 157 GCEs/g of Atacama Desert soil (versus 40 CFU/g soil).
Characterization of
Actinoplanes missouriensis
Spore Flagella
Authors: Uchida Kaoru , Jang Moon-Sun , Ohnishi Yasuo , Horinouchi Sueharu , Hayakawa Masayuki , Fujita Nobuyuki , Aizawa Shin-Ichi 
Published: February 2011

ABSTRACT

Actinoplanes missouriensis
spores swim with a tuft of flagella. Flagella of newborn spores are wrapped with a membranous sheath. When the sheath is unwrapped, spores start swimming. Flagellar length is kept short, at around 1.9 μm, which covers half the circumference of the spore.
Antibacterial Activity and Mechanism of Action of Zinc Oxide Nanoparticles against
Campylobacter jejuni
Authors: Xie Yanping , He Yiping , Irwin Peter L. , Jin Tony , Shi Xianming 
Published: February 2011

ABSTRACT

The antibacterial effect of zinc oxide (ZnO) nanoparticles on
Campylobacter jejuni
was investigated for inhibition and inactivation of cell growth. The results showed that
C. jejuni
was extremely sensitive to treatment with ZnO nanoparticles. The MIC of ZnO nanoparticles for
C. jejuni
was determined to be 0.05 to 0.025 mg/ml, which is 8- to 16-fold lower than that for
Salmonella enterica
serovar Enteritidis and
Escherichia coli
O157:H7 (0.4 mg/ml). The action of ZnO nanoparticles against
C. jejuni
was determined to be bactericidal, not bacteriostatic. Scanning electron microscopy examination revealed that the majority of the cells transformed from spiral shapes into coccoid forms after exposure to 0.5 mg/ml of ZnO nanoparticles for 16 h, which is consistent with the morphological changes of
C. jejuni
under other stress conditions. These coccoid cells were found by ethidium monoazide-quantitative PCR (EMA-qPCR) to have a certain level of membrane leakage. To address the molecular basis of ZnO nanoparticle action, a large set of genes involved in cell stress response, motility, pathogenesis, and toxin production were selected for a gene expression study. Reverse transcription-quantitative PCR (RT-qPCR) showed that in response to treatment with ZnO nanoparticles, the expression levels of two oxidative stress genes (
katA
and
ahpC
) and a general stress response gene (
dnaK
) were increased 52-, 7-, and 17-fold, respectively. These results suggest that the antibacterial mechanism of ZnO nanoparticles is most likely due to disruption of the cell membrane and oxidative stress in
Campylobacter
.
Development of an O-Antigen Serotyping Scheme for
Cronobacter sakazakii
Authors: Sun Yamin , Wang Min , Liu Hongbo , Wang Jingjing , He Xin , Zeng Jing , Guo Xi , Li Kun , Cao Boyang , Wang Lei 
Published: February 2011

ABSTRACT

Cronobacter sakazakii
is an opportunistic pathogen that can cause severe infections. Serotyping provides a basis for the categorization of bacterial strains and is an important tool for epidemiological and surveillance purposes. In this study, of the 135
Cronobacter
strains tested initially, 119 were identified as
C. sakazakii
and used. A serotyping scheme for
C. sakazakii
that classifies strains based on their different O antigens was developed. Seven antisera that exhibited high agglutinin titers (>640) were produced. O2 and O6 antisera were specific for their homologous strains, O4 and O7 antisera gave heterologous titers with O1 and O6 antigens, respectively, and O1, O3, and O5 antisera cross-reacted with each other and require preabsorption with the other two antigens. All of these 119
C. sakazakii
strains were clearly assigned to these seven serotypes. O1 and O2 are the dominant serotypes, comprising 69.7% of the isolates. We also characterized the O-antigen gene clusters using restriction fragment length polymorphism (RFLP). The grouping of
C. sakazakii
strains based on their RFLP banding patterns correlated well with the grouping of strains based on our serotyping scheme. The serotype scheme presented here could prove to be a useful tool for serotyping
C. sakazakii
isolates.
Diversity of and Selection Acting on Cylindrospermopsin
cyrB
Gene Adenylation Domain Sequences in Florida
Authors: Yilmaz Mete , Phlips Edward J. 
Published: February 2011

ABSTRACT

Aphanizomenon ovalisporum
is the only confirmed cylindrospermopsin producer identified in the United States to date. On the other hand,
Cylindrospermopsis raciborskii
is a prominent feature of many lakes in Florida and other regions of the United States. To see the variation in cylindrospermopsin
cyrB
gene adenylation domain sequences and possibly discover new cylindrospermopsin producers, we collected water samples for a 3-year period from 17 different systems in Florida. Positive amplicons were cloned and sequenced, revealing that approximately 92% of sequences were
A. ovalisporum
-like (>99% identity). Interestingly, 6% of sequences were very similar (>99% identity) to
cyrB
sequences of
C. raciborskii
from Australia and of
Aphanizomenon
sp. from Germany. Neutrality tests suggest that
A. ovalisporum
-like
cyrB
adenylation domain sequences are under purifying selection, with abundant low-frequency polymorphisms within the population. On the other hand, when compared between species by codon-based methods, amino acids of CyrB also seem to be under purifying selection, in accordance with the one proposed amino acid thought to be activated by the CyrB adenylation domain.
Mutacins from
Streptococcus mutans
UA159 Are Active against Multiple Streptococcal Species
Authors: Hossain Mohammad Shahnoor , Biswas Indranil 
Published: February 2011

ABSTRACT

Streptococcus mutans
UA159, whose genome is completely sequenced, produces two nonlantibiotic mutacins, mutacin IV (encoded by
nlmAB
) and mutacin V (encoded by
nlmC
). In this study, we investigated the contribution of
nlmA
and
nlmB
to mutacin IV activity and demonstrated by performing genetic studies as well as by using semipurified molecules that, in contrast to a previous report, both of these genes are required for optimum mutacin IV activity. We also showed that mutacin IV is active against multiple
Streptococcus
species. In contrast, mutacin V displayed a narrower inhibitory range than mutacin IV. Our results suggest that mutacin IV and mutacin V may act synergistically to inhibit various organisms.
The Centromere Site of the Segregation Cassette of Broad-Host-Range Plasmid RA3 Is Located at the Border of the Maintenance and Conjugative Transfer Modules
Authors: Kulińska Anna , Cao Yunhong , Macioszek Małgorzata , Hayes Finbarr , Jagura-Burdzy Grażyna 
Published: February 2011

ABSTRACTRA3 is a low-copy-number, broad-host-range (BHR) conjugative plasmid of the IncU incompatibility group isolated originally fromAeromonasspp. A 4.9-kb fragment of RA3 is sufficient to stabilize an otherwise unstable replicon inEscherichia coli. This fragment specifies thekorA-incC-korB-orf11operon coding for an active partition system related to the central control operon of IncP-1 plasmids and found also in BHR environmental plasmids recently classified as the PromA group. All four genes in the cassette are necessary for segregation. IncC and KorB of RA3 belong to the ParA and ParB families of partitioning proteins, respectively. In contrast with IncP-1 plasmids, neither KorB nor IncC are involved in transcriptional autoregulation. Instead, KorA exerts transcriptional control of the operon by binding to a palindromic sequence that overlaps the putative −35 promoter motif of the cassette. The Orf11 protein is not required for regulation, but its absence decreases the stabilization potential of the segregation module. A region discontiguous from the cassette harbors a set of unrelated repeat motifs distributed over ∼300 bp. Dissection of this region identified the centromere sequence that is vital for partitioning. The ∼300-bp fragment also encompasses the origin of conjugative transfer,oriT, and the promoter that drives transcription of the conjugative transfer operon. A similar set ofcis-acting motifs are evident in the PromA group of environmental plasmids, highlighting a common evolutionary origin of segregation and conjugative transfer modules in these plasmids and members of the IncU group.
Enhancing Isoprene Production by Genetic Modification of the 1-Deoxy-
d
-Xylulose-5-Phosphate Pathway in
Bacillus subtilis
Authors: Xue Junfeng , Ahring Birgitte K. 
Published: February 2011

ABSTRACT

To enhance the production of isoprene, a volatile 5-carbon hydrocarbon, in the Gram-positive spore-forming rod-shaped bacterium
Bacillus subtilis
, 1-deoxy-
d
-xylulose-5-phosphate synthase (Dxs) and 1-deoxy-
d
-xylulose-5-phosphate reductoisomerase (Dxr) were overexpressed in
B. subtilis
DSM 10. For the strain that overexpresses Dxs, the yield of isoprene was increased 40% over that by the wild-type strain. In the Dxr overexpression strain, the level of isoprene production was unchanged. Overexpression of Dxr together with Dxs showed an isoprene production level similar to that of the Dxs overproduction strain. The effects of external factors, such as stress factors including heat (48°C), salt (0.3 M NaCl), ethanol (1%), and oxidative (0.005% H
2
O
2
) stress, on isoprene production were further examined. Heat, salt, and H
2
O
2
induced isoprene production; ethanol inhibited isoprene production. In addition, induction and repression effects are independent of SigB, which is the general stress-responsive alternative sigma factor of Gram-positive bacteria.
Effect of Spatial Differences in Microbial Activity, pH, and Substrate Levels on Methanogenesis Initiation in Refuse
Authors: Staley Bryan F. , de los Reyes Francis L. , Barlaz Morton A. 
Published: February 2011

ABSTRACT

The initiation of methanogenesis in refuse occurs under high volatile fatty acid (VFA) concentration and low pH (5.5 to 6.25), which generally are reported to inhibit methanogenic
Archaea
. One hypothesized mechanism for the initiation of methanogenesis in refuse decomposition is the presence of pH-neutral niches within the refuse that act as methanogenesis initiation centers. To provide experimental support for this mechanism, laboratory-scale landfill reactors were operated and destructively sampled when methanogenesis initiation was observed. The active bacterial and archaeal populations were evaluated using RNA clone libraries, RNA terminal restriction fragment length polymorphism (T-RFLP), and reverse transcription-quantitative PCR (RT-qPCR). Measurements from 81 core samples from vertical and horizontal sections of each reactor showed large spatial differences in refuse pH, moisture content, and VFA concentrations. No pH-neutral niches were observed prior to methanogenesis. RNA clone library results showed that active bacterial populations belonged mostly to
Clostridiales
, and that methanogenic
Archaea
activity at low pH was attributable to
Methanosarcina barkeri
. After methanogenesis began, pH-neutral conditions developed in high-moisture-content areas containing substantial populations of
M. barkeri
. These areas expanded with increasing methane production, forming a reaction front that advanced to low-pH areas. Despite low-pH conditions in >50% of the samples within the reactors, the leachate pH was neutral, indicating that it is not an accurate indicator of landfill microbial conditions. In the absence of pH-neutral niches, this study suggests that methanogens tolerant to low pH, such as
M. barkeri
, are required to overcome the low-pH, high-VFA conditions present during the anaerobic acid phase of refuse decomposition.