bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat stress does not augment ventilatory responses to presyncopal limited lower body negative pressure
Authors: Pearson J. , Ganio M. S. , Lucas R. A. I. , Babb T. G. , Crandall C. G. 
Published: April 2013

New Findings
What is the central question of this study?Simulated haemorrhage increases ventilation prior to presyncope, possibly increasing venous return through the respiratory pump. Heat stress alone also increases ventilation. It is unknown whether this increased ventilation would be greater with combined heat stress and simulated haemorrhage.
What is the main finding and its importance?Our data suggest that the increased ventilation during simulated haemorrhage induced via lower body negative pressure is not altered in heat‐stressed humans. These findings have implications for individuals who are often heat stressed and at a higher risk of haemorrhagic injury. During a hypotensive challenge whilst heat stressed, these individuals are unlikely to realize benefits of a heightened respiratory pump relative to when they are normothermic.
Simulated haemorrhage, e.g. lower body negative pressure (LBNP), reduces central blood volume and mean arterial pressure, while ventilation increases. Passive whole‐body heat stress likewise increases ventilation. The objective of this project was to test the hypothesis that ventilatory responses to reductions in central blood volume and arterial pressure during simulated haemorrhage are enhanced when individuals are heat stressed rather than normothermic. Eight healthy men (34 ± 9 years old, 176 ± 6 cm tall and 80.2 ± 4.2 kg body weight) underwent a simulated haemorrhagic challenge via LBNP until presyncope on two separate occasions, namely normothermic control and whole‐body heat‐stress trials. Baseline ventilation and core and mean skin temperatures were not different between trials (all P > 0.05). Prior to LBNP, heat stress increased core (from 36.8 ± 0.2 to 38.2 ± 0.2°C, P < 0.05) and mean skin temperatures (from 33.9 ± 0.5 to 38.1 ± 0.6°C, P < 0.05), as well as minute ventilation (from 8.01 ± 2.63 to 13.68 ± 6.68 l min‐1, P < 0.01). At presyncope, mean arterial pressure and middle cerebral artery blood velocity decreased in both trials (P < 0.05). At presyncope, ventilation increased to 23.22 ± 6.78 (P < 0.01) and 25.88 ± 10.16 l min‐1 (P < 0.01) in the normothermic and hyperthermic trials, respectively; however, neither the increase in ventilation from the pre‐LBNP period nor the absolute ventilation was different between normothermic and hyperthermic trials (P > 0.05). These data suggest that the increase in ventilation during simulated haemorrhage induced via LBNP is not altered in heat‐stressed humans.
Resolution of hyposmotic stress in isolated mouse ventricular myocytes causes sealing of t‐tubules
Authors: Moench I. , Meekhof K. E. , Cheng L. F. , Lopatin A. N. 
Published: April 2013

New Findings
What is the central question of this study?The t‐tubules of ventricular myocytes are critical elements in excitation–contraction coupling. They become disorganized or even lost in various cardiac pathologies. However, the mechanisms leading to disruption of t‐tubules are essentially unknown. This study was designed to identify physiologically relevant processes that underlie remodelling of t‐tubules.
What is the main finding and its importance?We show that the resolution of physiologically relevant hyposmotic swelling, not the application of osmotic shock itself, leads to dramatic t‐tubular remodelling, including the sealing of individual t‐tubules. The results point to an important and probably general mechanism of acute and fast stress‐induced t‐tubular remodelling that may underlie various relevant pathologies of the heart.
It has recently been shown that various stress‐inducing manipulations in isolated ventricular myocytes may lead to significant remodelling of t‐tubules. Osmotic stress is one of the most common complications in various experimental and clinical settings. This study was therefore designed to determine the effects of a physiologically relevant type of osmotic stress, hyposmotic challenge, to the integrity of the t‐tubular system in mouse ventricular myocytes using the following two approaches: (1) electrophysiological measurements of membrane capacitance and inward rectifier (IK1) tail currents originating from K+ accumulation in t‐tubules; and (2) confocal microscopy of fluorescent dextrans trapped in sealed t‐tubules. Importantly, we found that removal of ‘0.6 Na’ (60% NaCl) hyposmotic solution, but not its application to myocytes, led to a ∼27% reduction in membrane capacitance, a ∼2.5‐fold reduction in the amplitude of the IK1 tail current and a ∼2‐fold reduction in the so‐called IK1‘inactivation’ (due to depletion of t‐tubular K+) at negative membrane potentials; all these data were consistent with significant detubulation. Confocal imaging experiments also demonstrated that extracellularly applied dextrans become trapped in sealed t‐tubules only upon removal of hyposmotic solutions, i.e. during the shrinking phase, but not during the initial swelling period. In light of these data, relevant previous studies, including those on excitation–contraction coupling phenomena during hyposmotic stress, may need to be reinterpreted, and the experimental design of future experiments should take into account the novel findings.
Physiological Characterization of an Anaerobic Ammonium-Oxidizing Bacterium Belonging to the “Candidatus Scalindua” Group
Authors: Awata Takanori , Oshiki Mamoru , Kindaichi Tomonori , Ozaki Noriatsu , Ohashi Akiyoshi , Okabe Satoshi 
Published: April 2013

ABSTRACT

The phylogenetic affiliation and physiological characteristics (e.g.,

K
s

and maximum specific growth rate [μ
max
]) of an anaerobic ammonium oxidation (anammox) bacterium, “
Candidatus
Scalindua sp.,” enriched from the marine sediment of Hiroshima Bay, Japan, were investigated. “
Candidatus
Scalindua sp.” exhibits higher affinity for nitrite and a lower growth rate and yield than the known anammox species.
Effects of Experimental Exclusion of Scavengers from Carcasses of Anthrax-Infected Herbivores on Bacillus anthracis Sporulation, Survival, and Distribution
Authors: Bellan Steve E. , Turnbull Peter C. B. , Beyer Wolfgang , Getz Wayne M. 
Published: April 2013

ABSTRACTScavenging of anthrax carcasses has long been hypothesized to play a critical role in the production of the infectious spore stage ofBacillus anthracisafter host death, though empirical studies assessing this are lacking. We comparedB. anthracisspore production, distribution, and survival at naturally occurring anthrax herbivore carcasses that were either experimentally caged to exclude vertebrate scavengers or left unmanipulated. We found no significant effect of scavengers on soil spore density (P> 0.05). Soil stained with terminally hemorrhaged blood and with nonhemorrhagic fluids exhibited high levels ofB. anthracisspore contamination (ranging from 103to 108spores/g), even in the absence of vertebrate scavengers. At most of the carcass sites, we also found that spore density in samples taken from hemorrhagic-fluid-stained soil continued to increase for >4 days after host death. We conclude that scavenging by vertebrates is not a critical factor in the life cycle ofB. anthracisand that anthrax control measures relying on deterrence or exclusion of vertebrate scavengers to prevent sporulation are unlikely to be effective.
Identification of Potentially Diarrheagenic Atypical Enteropathogenic Escherichia coli Strains Present in Canadian Food Animals at Slaughter and in Retail Meats
Authors: Comery Raven , Thanabalasuriar Ajitha , Garneau Philippe , Portt Andrea , Boerlin Patrick , Reid-Smith Richard J. , Harel Josï¿½e , Manges Amee R. , Gruenheid Samantha 
Published: April 2013

ABSTRACT

This study identified and characterized enteropathogenic
Escherichia coli
(EPEC) in the Canadian food supply. Eighteen of 450
E. coli
isolates from food animal sources were identified as atypical EPEC (aEPEC). Several of the aEPEC isolates identified in this study possessed multiple virulence genes, exhibited adherence and attaching and effacing (A/E) lesion formation, disrupted tight junctions, and were coclassified with the extraintestinal pathogenic
E. coli
(ExPEC) and enterotoxigenic
E. coli
(ETEC) pathotypes.
Bacterial Communities Associated with Subsurface Geochemical Processes in Continental Serpentinite Springs
Authors: Brazelton William J. , Morrill Penny L. , Szponar Natalie , Schrenk Matthew O. 
Published: April 2013

ABSTRACT

Reactions associated with the geochemical process of serpentinization can generate copious quantities of hydrogen and low-molecular-weight organic carbon compounds, which may provide energy and nutrients to sustain subsurface microbial communities independently of the photosynthetically supported surface biosphere. Previous microbial ecology studies have tested this hypothesis in deep sea hydrothermal vents, such as the Lost City hydrothermal field. This study applied similar methods, including molecular fingerprinting and tag sequencing of the 16S rRNA gene, to ultrabasic continental springs emanating from serpentinizing ultramafic rocks. These molecular surveys were linked with geochemical measurements of the fluids in an interdisciplinary approach designed to distinguish potential subsurface organisms from those derived from surface habitats. The betaproteobacterial genus
Hydrogenophaga
was identified as a likely inhabitant of transition zones where hydrogen-enriched subsurface fluids mix with oxygenated surface water. The
Firmicutes
genus
Erysipelothrix
was most strongly correlated with geochemical factors indicative of subsurface fluids and was identified as the most likely inhabitant of a serpentinization-powered subsurface biosphere. Both of these taxa have been identified in multiple hydrogen-enriched subsurface habitats worldwide, and the results of this study contribute to an emerging biogeographic pattern in which
Betaproteobacteria
occur in near-surface mixing zones and
Firmicutes
are present in deeper, anoxic subsurface habitats.
Susceptibility of Murine Norovirus and Hepatitis A Virus to Electron Beam Irradiation in Oysters and Quantifying the Reduction in Potential Infection Risks
Authors: Praveen Chandni , Dancho Brooke A. , Kingsley David H. , Calci Kevin R. , Meade Gloria K. , Mena Kristina D. , Pillai Suresh D. 
Published: April 2013

ABSTRACT

Consumption of raw oysters is an exposure route for human norovirus (NoV) and hepatitis A virus (HAV). Therefore, efficient postharvest oyster treatment technology is needed to reduce public health risks. This study evaluated the inactivation of HAV and the NoV research surrogate, murine norovirus-1 (MNV-1), in oysters (
Crassostrea virginica
) by electron beam (E-beam) irradiation. The reduction of potential infection risks was quantified for E-beam irradiation technology employed on raw oysters at various virus contamination levels. The E-beam dose required to reduce the MNV and HAV titer by 90% (D
10
value) in whole oysters was 4.05 (standard deviations [SD], ï¿½0.63) and 4.83 (SD, ï¿½0.08) kGy, respectively. Microbial risk assessment suggests that if a typical serving of 12 raw oysters was contaminated with 10
5
PFU, a 5-kGy treatment would achieve a 12% reduction (from 4.49 out of 10 persons to 3.95 out of 10 persons) in NoV infection and a 16% reduction (from 9.21 out of 10 persons to 7.76 out of 10 persons) in HAV infections. If the serving size contained only 10
2
PFU of viruses, a 5-kGy treatment would achieve a 26% reduction (2.74 out of 10 persons to 2.03 out of 10 persons) of NoV and 91% reduction (2.1 out of 10 persons to 1.93 out of 100 persons) of HAV infection risks. This study shows that although E-beam processing cannot completely eliminate the risk of viral illness, infection risks can be reduced.
Comparative Transcription Profiling and In-Depth Characterization of Plasmid-Based and Plasmid-Free Escherichia coli Expression Systems under Production Conditions
Authors: Mairhofer Juergen , Scharl Theresa , Marisch Karoline , Cserjan-Puschmann Monika , Striedner Gerald 
Published: April 2013

ABSTRACTPlasmid-basedEscherichia coliBL21(DE3) expression systems are extensively used for the production of recombinant proteins. However, the combination of a high gene dosage with strong promoters exerts extremely stressful conditions on producing cells, resulting in a multitude of protective reactions and malfunctions in the host cell with a strong impact on yield and quality of the product. Here, we provide in-depth characterization of plasmid-based perturbations in recombinant protein production. A plasmid-free T7 system with a single copy of the gene of interest (GOI) integrated into the genome was used as a reference. Transcriptomics in combination with a variety of process analytics were used to characterize and compare a plasmid-free T7-based expression system to a conventional pET-plasmid-based expression system, with both expressing human superoxide dismutase in fed-batch cultivations. The plasmid-free system showed a moderate stress response on the transcriptional level, with only minor effects on cell growth. In contrast to this finding, comprehensive changes on the transcriptome level were observed in the plasmid-based expression system and cell growth was heavily impaired by recombinant gene expression. Additionally, we found that the T7 terminator is not a sufficient termination signal. Overall, this work reveals that the major metabolic burden in plasmid-based systems is caused at the level of transcription as a result of overtranscription of the multicopy product gene and transcriptional read-through of T7 RNA polymerase. We therefore conclude that the presence of high levels of extrinsic mRNAs, competing for the limited number of ribosomes, leads to the significantly reduced translation of intrinsic mRNAs.
Quantifying the Responses of Mixed Rumen Microbes to Excess Carbohydrate
Authors: Hackmann Timothy J. , Diese Leanne E. , Firkins Jeffrey L. 
Published: April 2013

ABSTRACT

The aim of this study was to determine if a mixed microbial community from the bovine rumen would respond to excess carbohydrate by accumulating reserve carbohydrate, energy spilling (dissipating excess ATP energy as heat), or both. Mixed microbes from the rumen were washed with N-free buffer and dosed with glucose. Total heat production was measured by calorimetry. Energy spilling was calculated as heat production not accounted by (i) endogenous metabolism (heat production before dosing glucose) and (ii) synthesis of reserve carbohydrate (heat from synthesis itself and reactions yielding ATP for it). For cells dosed with 5 mM glucose, synthesis of reserve carbohydrate and endogenous metabolism accounted for nearly all heat production (93.7%); no spilling was detected (
P
= 0.226). For cells dosed with 20 mM glucose, energy spilling was not detected immediately after dosing, but it became significant (
P
< 0.05) by approximately 30 min after dosing with glucose. Energy spilling accounted for as much as 38.7% of heat production in one incubation. Nearly all energy (97.9%) and carbon (99.9%) in glucose were recovered in reserve carbohydrate, fermentation acids, CO
2
, CH
4
, and heat. This full recovery indicates that products were measured completely and that spilling was not a methodological artifact. These results should aid future research aiming to mechanistically account for variation in energetic efficiency of mixed microbial communities.
Prebiotic Content of Bread Prepared with Flour from Immature Wheat Grain and Selected Dextran-Producing Lactic Acid Bacteria
Authors: Pepe Olimpia , Ventorino Valeria , Cavella Silvana , Fagnano Massimo , Brugno Rachele 
Published: April 2013

ABSTRACT

In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type “0 America” wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB),
Leuconostoc lactis
A95 and
Lactobacillus curvatus
69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ï¿½ 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ï¿½ 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as
L. lactis
,
L. curvatus
, and
Pediococcus acidilactici
. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ï¿½ 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ï¿½ 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages of fructo-oligosaccharides. These data support the use of immature wheat grain flour, and exopolysaccaride-producing lactic acid bacteria in formulating functional prebiotic baked goods whose nutritional value can be suitably improved.
Molecular Characterization of CTX-M β-Lactamase and Associated Addiction Systems in Escherichia coli Circulating among Cattle, Farm Workers, and the Farm Environment
Authors: Tamang Migma Dorji , Nam Hyang-Mi , Gurung Mamata , Jang Geum-Chan , Kim Su-Ran , Jung Suk-Chan , Park Yong Ho , Lim Suk-Kyung 
Published: April 2013

ABSTRACT

A total of 84 extended-spectrum β-lactamase (ESBL)-producing
Escherichia coli
isolates from cattle, farm workers, and the farm environment isolated from February to September 2008 in the Republic of Korea were investigated. All 84 ESBL-producing isolates carried
bla
CTX-M
genes that belonged to the CTX-M-1 (
n
= 35) or CTX-M-9 (
n
= 49) family. The most predominant CTX-M type identified was CTX-M-14 (
n
= 49), followed by CTX-M-32 (
n
= 26). The
bla
CTX-M
genes were identified most commonly in
E. coli
isolates from feces (
n
= 29), teats (
n
= 25), and milk (
n
= 14). A
bla
CTX-M-14
gene was also detected in an
E. coli
isolate from a farmer's hand. Transfer of the
bla
CTX-M
gene from 60
bla
CTX-M
-positive
E. coli
isolates to the recipient
E. coli
J53 strain by conjugation was demonstrated. Plasmid isolation from
bla
CTX-M
-positive transconjugants revealed a large (95- to 140-kb) conjugative plasmid. Almost all (82/84)
bla
CTX-M
genes possessed an insertion sequence, IS
Ecp1
, upstream of the
bla
CTX-M
gene. Only in the case of the CTX-M-14 genes was IS
903
downstream of the gene. The
bla
CTX-M
genes were associated with seven kinds of addiction systems. Among them,
pndAC
,
hok-sok
, and
srnBC
were the most frequently identified addiction systems in both wild strains and transconjugants. The spread of
bla
CTX-M
genes was attributed to both clonal expansion and horizontal dissemination. Our data suggest that a combination of multiple addiction systems in plasmids carrying
bla
CTX-M
genes could contribute to their maintenance in the host cells. To our knowledge, the
bla
CTX-M-32
gene has not previously been reported in animal isolates from the Republic of Korea.
Characterization of Site-Specific Mutations in a Short-Chain-Length/Medium-Chain-Length Polyhydroxyalkanoate Synthase:
In Vivo
and
In Vitro
Studies of Enzymatic Activity and Substrate Specificity
Authors: Chuah Jo-Ann , Tomizawa Satoshi , Yamada Miwa , Tsuge Takeharu , Doi Yoshiharu , Sudesh Kumar , Numata Keiji 
Published: April 2013

ABSTRACT

Saturation point mutagenesis was carried out at position 479 in the polyhydroxyalkanoate (PHA) synthase from
Chromobacterium
sp. strain USM2 (PhaC
Cs
) with specificities for short-chain-length (SCL) [(
R
)-3-hydroxybutyrate (3HB) and (
R
)-3-hydroxyvalerate (3HV)] and medium-chain-length (MCL) [(
R
)-3-hydroxyhexanoate (3HHx)] monomers in an effort to enhance the specificity of the enzyme for 3HHx. A maximum 4-fold increase in 3HHx incorporation and a 1.6-fold increase in PHA biosynthesis, more than the wild-type synthase, was achieved using selected mutant synthases. These increases were subsequently correlated with improved synthase activity and increased preference of PhaC
Cs
for 3HHx monomers. We found that substitutions with uncharged residues were beneficial, as they resulted in enhanced PHA production and/or 3HHx incorporation. Further analysis led to postulations that the size and geometry of the substrate-binding pocket are determinants of PHA accumulation, 3HHx fraction, and chain length specificity.
In vitro
activities for polymerization of 3HV and 3HHx monomers were consistent with
in vivo
substrate specificities. Ultimately, the preference shown by wild-type and mutant synthases for either SCL (C
4
and C
5
) or MCL (C
6
) substrates substantiates the fundamental classification of PHA synthases.
Identification of Mutations Involved in the Requirement of Potassium for Growth of Typical Melissococcus plutonius Strains
Authors: Takamatsu Daisuke , Arai Rie , Miyoshi-Akiyama Tohru , Okumura Kayo , Okura Masatoshi , Kirikae Teruo , Kojima Atsuko , Osaki Makoto 
Published: April 2013

ABSTRACT

Melissococcus plutonius
is a fastidious honeybee pathogen, and the addition of KH
2
PO
4
to culture medium is required for its growth. Using genome sequences and a newly developed vector, we showed that mutations in genes encoding Na
+
/H
+
antiporter and cation-transporting ATPase are involved in the potassium requirement for growth.
Insights into the Ropy Phenotype of the Exopolysaccharide-Producing Strain Bifidobacterium animalis subsp.
lactis
A1dOxR
Authors: Hidalgo-Cantabrana Claudio , Sï¿½nchez Borja , Moine Deborah , Berger Bernard , de los Reyes-Gavilï¿½n Clara G. , Gueimonde Miguel , Margolles Abelardo , Ruas-Madiedo Patricia 
Published: April 2013

ABSTRACT

The proteome of the ropy strain
Bifidobacterium animalis
subsp.
lactis
A1dOxR, compared to that of its nonropy isogenic strain, showed an overproduction of a protein involved in rhamnose biosynthesis. Results were confirmed by gene expression analysis, and this fact agreed with the high rhamnose content of the ropy exopolysaccharide.
Construction of Mobilizable Mini-Tn
7
Vectors for Bioluminescent Detection of Gram-Negative Bacteria and Single-Copy Promoter
lux
Reporter Analysis
Authors: Damron F. Heath , McKenney Elizabeth S. , Barbier Mariette , Liechti George W. , Schweizer Herbert P. , Goldberg Joanna B. 
Published: April 2013

ABSTRACT

We describe the construction of mini-Tn
7
-based broad-host-range vectors encoding
lux
genes as bioluminescent reporters. These constructs can be mobilized into the desired host(s) by conjugation for chromosomal mini-Tn
7-lux
integration and are useful for localization of bacteria during infections or for characterizing regulation of promoters of interest in Gram-negative bacteria.
Prevalence and Relatedness of Escherichia coli O157:H7 Strains in the Feces and on the Hides and Carcasses of U.S. Meat Goats at Slaughter
Authors: Jacob M. E. , Foster D. M. , Rogers A. T. , Balcomb C. C. , Sanderson M. W. 
Published: April 2013

ABSTRACT

We determined the prevalences of
Escherichia coli
O157:H7 in feces, hide, and carcasses of meat goats at a U.S. processing plant. Prevalences were 11.1%, 2.7%, and 2.7%, respectively. Sixteen pulsed-field gel electrophoresis (PFGE) subtypes were identified among 49
E. coli
O157:H7 isolates, some of which were present on multiple sample types or collection days.