bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exercise training effects on hypoxic and hypercapnic ventilatory responses in mice selected for increased voluntary wheel running
Authors: Kelly Scott A. , Rezende Enrico L. , Chappell Mark A. , Gomes Fernando R. , Kolb Erik M. , Malisch Jessica L. , Rhodes Justin S. , Mitchell Gordon S. , Garland Theodore 
Published: October 2013

New Findings
What is the central question of this study?
We used experimental evolution to determine how selective breeding for high voluntary wheel running and exercise training (7–11 weeks) affect ventilatory chemoreflexes of laboratory mice at rest.
What is the main finding and its importance?
Selective breeding, although significantly affecting some traits, did not systematically alter ventilation across gas concentrations. As with most human studies, our findings support the idea that endurance training attenuates resting ventilation. However, little evidence was found for a correlation between ventilatory chemoreflexes and the amount of individual voluntary wheel running. We conclude that exercise ‘training’ alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.
Ventilatory control is affected by genetics, the environment and gene–environment and gene–gene interactions. Here, we used an experimental evolution approach to test whether 37 generations of selective breeding for high voluntary wheel running (genetic effects) and/or long‐term (7–11 weeks) wheel access (training effects) alter acute respiratory behaviour of mice resting in normoxic, hypoxic and hypercapnic conditions. As the four replicate high‐runner (HR) lines run much more than the four non‐selected control (C) lines, we also examined whether the amount of exercise among individual mice was a quantitative predictor of ventilatory chemoreflexes at rest. Selective breeding and/or wheel access significantly affected several traits. In normoxia, HR mice tended to have lower mass‐adjusted rates of oxygen consumption and carbon dioxide production. Chronic wheel access increased oxygen consumption and carbon dioxide production in both HR and C mice during hypercapnia. Breathing frequency and minute ventilation were significantly reduced by chronic wheel access in both HR and C mice during hypoxia. Selection history, while significantly affecting some traits, did not systematically alter ventilation across all gas concentrations. As with most human studies, our findings support the idea that endurance training (access to wheel running) attenuates resting ventilation. However, little evidence was found for a correlation at the level of the individual variation between ventilatory chemoreflexes and performance (amount of individual voluntary wheel running). We tentatively conclude that exercise ‘training’ alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.
Nonlinear Strain Energy Formulation of a Generalized Bisymmetric Spatial Beam for Flexure Mechanism Analysis
Authors: Sen Shiladitya , Awtar Shorya 
Published: October 2013

Abstract
Analytical load–displacement relations for flexure mechanisms, formulated by integrating the individual analytical models of their building-blocks (i.e., flexure elements), help in understanding the constraint characteristics of the whole mechanism. In deriving such analytical relations for flexure mechanisms, energy based approaches generally offer lower mathematical complexity, compared to Newtonian methods, by reducing the number of unknowns—specifically, the internal loads. To facilitate such energy based approaches, a closed-form nonlinear strain energy expression for a generalized bisymmetric spatial beam flexure is presented in this paper. The strain energy, expressed in terms of the end-displacement of the beam, considers geometric nonlinearities for intermediate deformations, enabling the analysis of flexure mechanisms over a finite range of motion. The generalizations include changes in the initial orientation and shape of the beam flexure due to potential misalignment or manufacturing. The effectiveness of this approach is illustrated via the analysis of a multilegged table flexure mechanism. The resulting analytical model is shown to be accurate using nonlinear finite elements analysis, within a load and displacement range of interest.
A Novel Damping Device for Broadband Attenuation of Low-Frequency Combustion Pulsations in Gas Turbines
Authors: Bothien Mirko R. , Noiray Nicolas , Schuermans Bruno 
Published: October 2013

Abstract
Damping of thermoacoustically induced pressure pulsations in combustion chambers is a major focus of gas turbine operation. Conventional Helmholtz resonators are an excellent means to attenuate thermoacoustic instabilities in gas turbines. Usually, however, the damping optimum is in a narrow frequency band at one operating condition. The work presented here deals with a modification of the basic Helmholtz resonator design overcoming this drawback. It consists of a damper body housing multiple volumes that are connected to each other. Adequate adjustment of the governing parameters results in a broadband damping characteristic for low frequencies. In this way, changes in operating conditions and engine-to-engine variations involving shifts in the combustion pulsation frequency can conveniently be addressed. Genetic algorithms and optimization strategies are used to derive these parameters in a multidimensional parameter space. The novel damper concept is described in more detail and compared with cold-flow experiments. In order to validate the performance under realistic conditions, the new broadband dampers were implemented in a full-scale test engine. Pulsation amplitudes could be reduced by more than 80%. In addition, it is shown that, due to sophisticated damper placement in the engine, two unstable modes can be addressed simultaneously. Application of the damper concept allowed a considerable increase of the engine operating range, thereby reducing NOx emissions by 55%. Predictions obtained with the physics-based model excellently agree with experimental results for all tested damper geometries, bias flows, excitation amplitudes, and most importantly with the measurements in the engine.
Microbial Biotransformation of Gentiopicroside by the Endophytic Fungus Penicillium crustosum 2T01Y01
Authors: Zeng Wen-Liang , Li Wan-Kui , Han Han , Tao Yan-Yan , Yang Li , Wang Zheng-Tao , Chen Kai-Xian 
Published: October 2013

ABSTRACT

Endophytic fungi are symbiotic with plants and possess multienzyme systems showing promising metabolite potency with region selectivity and stereoselectivity. The aim of this study was to use these special microorganisms as an
in vitro
model to mimic the potential mammalian metabolites of a natural iridoid gentiopicroside (GPS, compound 1). The fungi isolated from a medicinal plant,
Dendrobium candidum
Wall. ex Lindl., were screened for their biotransformation abilities with GPS as the substrate, and one strain with high converting potency was identified as
Penicillium crustosum
2T01Y01 on the basis of the sequence of the internal transcribed spacer of the ribosomal DNA region. Upon the optimized incubation of
P. crustosum
2T01Y01 with the substrate, seven deglycosylated metabolites were detected by ultraperformance liquid chromatography/quadrupole time of flight mass spectrometry (UPLC/Q-TOF MS). Preparative-scale biotransformation with whole cells of the endophytic fungus resulted in the production of five metabolites, including three novel ones, 5α-(hydroxymethyl)-6β-methyl-3,4,5,6-tetrahydropyrano[3,4-
c
]pyran-1(8
H
)-one (compound 2), (
Z
)-4-(1-hydroxybut-3-en-2-yl)-5,6-dihydropyran-2-one (compound 3), and (
E
)-4-(1-hydroxybut-3-en-2-yl)-5,6-dihydropyran-2-one (compound 4), along with two known ones, 5α-(hydroxymethyl)-6β-methyl-1
H
,3
H
-5,6-dihydropyrano[3,4-
c
]pyran-1(3
H
)-one (compound 5) and 5α-(hydroxymethyl)-6α-methyl-5,6-dihydropyrano[3,4-
c
]pyran-1(3
H
)-one (compound 6), aided by nuclear magnetic resonance and high-resolution mass spectral analyses. The other two metabolites were tentatively identified by online UPLC/Q-TOF MS as 5-hydroxymethyl-5,6-dihydroisochromen-1-one (compound 7) and 5-hydroxymethyl-3,4,5,6-tetrahydroisochromen-1-one (compound 8), and compound 8 is a new metabolite. To test the metabolic mechanism, the β-glucosidase activity of the fungus
P. crustosum
2T01Y01 was assayed with ρ-nitrophenyl-β-
d
-glucopyranoside as a probe substrate, and the pathway of GPS biotransformation by strain 2T01Y01 is proposed. In addition, the hepatoprotective activities of GPS and metabolite compounds 2, 5, and 6 against human hepatocyte line HL-7702 injury induced by hydrogen peroxide were evaluated.
Toxicity of Bioactive and Probiotic Marine Bacteria and Their Secondary Metabolites in Artemia sp. and Caenorhabditis elegans as Eukaryotic Model Organisms
Authors: Neu Anna Katrin , Månsson Maria , Gram Lone , Prol-García María J. 
Published: October 2013

ABSTRACT

We have previously reported that some strains belonging to the marine
Actinobacteria
class, the
Pseudoalteromonas
genus, the
Roseobacter
clade, and the
Photobacteriaceae
and
Vibrionaceae
families produce both antibacterial and antivirulence compounds, and these organisms are interesting from an applied point of view as fish probiotics or as a source of pharmaceutical compounds. The application of either organisms or compounds requires that they do not cause any side effects, such as toxicity in eukaryotic organisms. The purpose of this study was to determine whether these bacteria or their compounds have any toxic side effects in the eukaryotic organisms
Artemia
sp. and
Caenorhabditis elegans
.
Arthrobacter davidanieli
WX-11,
Pseudoalteromonas luteoviolacea
S4060,
P. piscicida
S2049,
P. rubra
S2471,
Photobacterium halotolerans
S2753, and
Vibrio coralliilyticus
S2052 were lethal to either or both model eukaryotes. The toxicity of
P. luteoviolacea
S4060 could be related to the production of the antibacterial compound pentabromopseudilin, while the adverse effect observed in the presence of
P. halotolerans
S2753 and
V. coralliilyticus
S2052 could not be explained by the production of holomycin nor andrimid, the respective antibiotic compounds in these organisms. In contrast, the tropodithietic acid (TDA)-producing bacteria
Phaeobacter inhibens
DSM17395 and
Ruegeria mobilis
F1926 and TDA itself had no adverse effect on the target organisms. These results reaffirm TDA-producing
Roseobacter
bacteria as a promising group to be used as probiotics in aquaculture, whereas
Actinobacteria
,
Pseudoalteromonas
,
Photobacteriaceae
, and
Vibrionaceae
should be used with caution.
Synthetic Promoters Functional in Francisella novicida and Escherichia coli
Authors: McWhinnie Ralph L. , Nano Francis E. 
Published: October 2013

ABSTRACT

In this work, we describe the identification of synthetic, controllable promoters that function in the bacterial pathogen
Francisella novicida
, a model facultative intracellular pathogen. Synthetic DNA fragments consisting of the tetracycline operator (
tetO
) flanked by a random nucleotide sequence were inserted into a
Francisella novicida
shuttle plasmid upstream of a promoterless artificial operon containing the reporter genes
cat
and
lacZ
. Fragments able to promote transcription were selected for based on their ability to drive expression of the
cat
gene, conferring chloramphenicol resistance. Promoters of various strengths were found, many of which were repressed in the presence of the tetracycline repressor (TetR) and promoted transcription only in the presence of the TetR inducer anhydrotetracycline. A subset of both constitutive and inducible synthetic promoters were characterized to find their induction ratios and to identify their transcription start sites. In cases where
tetO
was located between or downstream of the −10 and −35 regions of the promoter, control by TetR was observed. If the
tetO
region was upstream of the −35 region by more than 9 bp, it did not confer TetR control. We found that three of three promoters isolated in
F. novicida
functioned at a comparable level in
E. coli
; however, none of the 10 promoters isolated in
E. coli
functioned at a significant level in
F. novicida
. Our results allowed us to isolate minimal
F. novicida
promoters of 47 and 48 bp in length.
Microbiomes of Unreactive and Pathologically Altered Ileocecal Lymph Nodes of Slaughter Pigs
Authors: Mann Evelyne , Dzieciol Monika , Metzler-Zebeli Barbara U. , Wagner Martin , Schmitz-Esser Stephan 
Published: October 2013

ABSTRACT

Microbe-laden dendritic cells are shifted to ileocecal lymph nodes (ICLNs), where microbes are concentrated and an adequate immune response is triggered. Hence, ICLNs are at a crucial position in immune anatomy and control processes of the local immune system. Pathological alterations in ICLNs, such as reactive hyperplasia,
lymphadenitis purulenta
, or
granulomatosa
, can harbor a multitude of pathogens and commensals, posing a potential zoonotic risk in animal production. The aim of this study was to characterize the microbial diversity of unreactive ICLNs of slaughter pigs and to investigate community shifts in reactive ICLNs altered by enlargement, purulence, or granulomatous formations. Pyrosequencing of 16S rRNA gene amplicons from 32 ICLNs yielded 175,313 sequences, clustering into 650 operational taxonomic units (OTUs). OTUs were assigned to 239 genera and 11 phyla. Besides a highly diverse bacterial community in ICLNs, we observed significant shifts in pathologically altered ICLNs. The relative abundances of
Cloacibacterium
- and
Novosphingobium
-associated OTUs and the genus
Faecalibacterium
were significantly higher in unreactive ICLNs than in pathologically altered ICLNs. Enlarged ICLNs harbored significantly more
Lactobacillus
- and
Clostridium
-associated sequences. Relative abundances of
Mycoplasma
,
Bacteroides
,
Veillonella
, and
Variovorax
OTUs were significantly increased in granulomatous ICLNs, whereas abundances of
Pseudomonas
,
Escherichia
, and
Acinetobacter
OTUs were significantly increased in purulent ICLNs (
P
< 0.05). Correlation-based networks revealed interactions among OTUs in all ICLN groups, and discriminant analyses depicted discrimination in response to pathological alterations. This study is the first community-based survey in ICLNs of livestock animals and will provide a basis to broaden the knowledge of microbe-host interactions in pigs.
Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome
bc
1
Complex
Authors: Hopkins Adam , Buchanan Grant , Palmer Tracy 
Published: October 2013

ABSTRACT

The cytochrome
bc
1
-cytochrome
aa
3
complexes together comprise one of the major branches of the bacterial aerobic respiratory chain. In actinobacteria, the cytochrome
bc
1
complex shows a number of unusual features in comparison to other cytochrome
bc
1
complexes. In particular, the Rieske iron-sulfur protein component of this complex, QcrA, is a polytopic rather than a monotopic membrane protein. Bacterial Rieske proteins are usually integrated into the membrane in a folded conformation by the twin arginine protein transport (Tat) pathway. In this study, we show that the activity of the
Streptomyces coelicolor
M145 cytochrome
bc
1
complex is dependent upon an active Tat pathway. However, the polytopic Rieske protein is still integrated into the membrane in a Δ
tatC
mutant strain, indicating that a second protein translocation machinery also participates in its assembly. Difference spectroscopy indicated that the cytochrome
c
component of the complex was correctly assembled in the absence of the Tat machinery. We show that the intact cytochrome
bc
1
complex can be isolated from
S. coelicolor
M145 membranes by affinity chromatography. Surprisingly, a stable cytochrome
bc
1
complex containing the Rieske protein can be isolated from membranes even when the Tat system is inactive. These findings strongly suggest that the additional transmembrane segments of the
S. coelicolor
Rieske protein mediate hydrophobic interactions with one or both of the cytochrome subunits.
ExsA and LcrF Recognize Similar Consensus Binding Sites, but Differences in Their Oligomeric State Influence Interactions with Promoter DNA
Authors: King Jessica M. , Schesser Bartra Sara , Plano Gregory , Yahr Timothy L. 
Published: October 2013

ABSTRACT

ExsA activates type III secretion system (T3SS) gene expression in
Pseudomonas aeruginosa
and is a member of the AraC family of transcriptional regulators. AraC proteins contain two helix-turn-helix (HTH) DNA binding motifs. One helix from each HTH motif inserts into the major groove of the DNA to make base-specific contacts with the promoter region. The amino acids that comprise the HTH motifs of ExsA are nearly identical to those in LcrF/VirF, the activators of T3SS gene expression in the pathogenic yersiniae. In this study, we tested the hypothesis that ExsA/LcrF/VirF recognize a common nucleotide sequence. We report that
Yersinia pestis
LcrF binds to and activates transcription of ExsA-dependent promoters in
P. aeruginosa
and that plasmid-expressed ExsA complements a
Y. pestis lcrF
mutant for T3SS gene expression. Mutations that disrupt the ExsA consensus binding sites in both
P. aeruginosa
and
Y. pestis
T3SS promoters prevent activation by ExsA and LcrF. Our combined data demonstrate that ExsA and LcrF recognize a common nucleotide sequence. Nevertheless, the DNA binding properties of ExsA and LcrF are distinct. Whereas two ExsA monomers are sequentially recruited to the promoter region, LcrF binds to promoter DNA as a preformed dimer and has a higher capacity to bend DNA. An LcrF mutant defective for dimerization bound promoter DNA with properties similar to ExsA. Finally, we demonstrate that the activators of T3SS gene expression from
Photorhabdus luminescens
,
Aeromonas hydrophila
, and
Vibrio parahaemolyticus
are also sensitive to mutations that disrupt the ExsA consensus binding site.
The γ-Aminobutyrate Permease GabP Serves as the Third Proline Transporter of Bacillus subtilis
Authors: Zaprasis Adrienne , Hoffmann Tamara , Stannek Lorena , Gunka Katrin , Commichau Fabian M. , Bremer Erhard 
Published: October 2013

ABSTRACT

PutP and OpuE serve as proline transporters when this imino acid is used by
Bacillus subtilis
as a nutrient or as an osmostress protectant, respectively. The simultaneous inactivation of the PutP and OpuE systems still allows the utilization of proline as a nutrient. This growth phenotype pointed to the presence of a third proline transport system in
B. subtilis
. We took advantage of the sensitivity of a
putP opuE
double mutant to the toxic proline analog 3,4-dehydro-
dl
-proline (DHP) to identify this additional proline uptake system. DHP-resistant mutants were selected and found to be defective in the use of proline as a nutrient. Whole-genome resequencing of one of these strains provided the lead that the inactivation of the γ-aminobutyrate (GABA) transporter GabP was responsible for these phenotypes. DNA sequencing of the
gabP
gene in 14 additionally analyzed DHP-resistant strains confirmed this finding. Consistently, each of the DHP-resistant mutants was defective not only in the use of proline as a nutrient but also in the use of GABA as a nitrogen source. The same phenotype resulted from the targeted deletion of the
gabP
gene in a
putP opuE
mutant strain. Hence, the GabP carrier not only serves as an uptake system for GABA but also functions as the third proline transporter of
B. subtilis
. Uptake studies with radiolabeled GABA and proline confirmed this conclusion and provided information on the kinetic parameters of the GabP carrier for both of these substrates.
Exploring the relationship between baseline physical activity levels and mortality reduction associated with increases in physical activity: a modelling study
Authors: Minton Jonathan , Dimairo Munyaradzi , Everson-Hock Emma , Scott Emma , Goyder Elizabeth 
Published: October 2013

BackgroundIncreasing physical activity (PA) levels among the general adult population of developed nations is important for reducing premature mortality and the burdens of preventable illness. Assessing how effective PA interventions are as health interventions often involves categorising participants as either ‘active’ or ‘sedentary’ after the interventions. A model was developed showing that doing this could significantly misestimate the health effect of PA interventions.MethodsA life table model was constructed combining evidence on baseline PA levels with evidence indicating the non-linear relationship between PA levels and all-cause mortality risks. PA intervention scenarios were modelled which had the same mean increase in PA but different levels of take-up by people who were more active or more sedentary to begin with.ResultsThe model simulations indicated that, compared with a scenario where already-active people did most of the additional PA, a scenario where the least active did the most additional PA was around a third more effective in preventing deaths between the ages of 50 and 60 years. The relationship between distribution of PA take-up and health effect was explored systematically and appeared non-linear.ConclusionsAs the health gains of a given PA increase are greatest among people who are most sedentary, smaller increases in PA in the least active may have the same health benefits as much larger PA increases in the most active. To help such health effects to be assessed, PA studies should report changes in the distribution of PA level between the start and end of the study.
Increases in HIV screening in primary care clinics through an electronic reminder: an interrupted time series
Authors: Avery Ann K , Del Toro Michelle , Caron Aleece 
Published: October 2013

Objective aimIdentify and eliminate barriers to HIV testing in primary care and to decrease the rates of patients never being tested, and limit unnecessary repeat testing.SettingPrimary care clinics within an urban publicly funded safety net hospital and community health system in Cleveland, Ohio. Reported HIV prevalence among male Cleveland residents is 1193.5/100 000.DesignA time series analysis using statistical process control was used.MethodsPrimary care encounters of patients aged 13–64 years from selected sites were reviewed throughout the initiative for HIV testing prior to the visit and associated with the visit.ResultsRun charts of the proportion of men and women never tested for HIV demonstrated marked improvement and special cause variation with six sequential quarters falling outside of the trend lines. Evaluation of encounters associated with a first HIV test confirmed testing occurring within primary care rather than elsewhere in the health system.ConclusionsImplementing an electronic medical record-based reminder effectively increased HIV testing among primary care patients not previously tested, while education and practice feedback alone did not.