bluuebunny/crossref_metadata_2025_split huggingface dataset:
PGC1‐α over‐expression prevents metabolic alterations and soleus muscle atrophy in hindlimb unloaded mice
Authors: Cannavino Jessica , Brocca Lorenza , Sandri Marco , Bottinelli Roberto , Pellegrino Maria Antonietta 
Published: August 2014

Key points
Oxidative stress is widely considered a major cause of muscle loss not only in disuse but also in most chronic diseases, triggering carbonylation of proteins and activation of catabolic pathways involved in their degradation.
Here we show that administration of an antioxidant prevents redox imbalance, but does not prevent activation of catabolic pathways and muscle atrophy.
We indicate that alterations of oxidative metabolism, occurring in slow soleus muscle, are not just a consequence of disuse, but a major cause of activation of catabolic pathways and loss of mass.
This conclusion is confirmed by the observation that muscle‐specific overexpression of PGC‐1α, a master regulator of mitochondrial biogenesis, prevents activation of catabolic systems and disuse muscle atrophy.
These findings contribute to a better mechanistic understanding of disuse muscle loss.
AbstractProlonged skeletal muscle inactivity causes muscle fibre atrophy. Redox imbalance has been considered one of the major triggers of skeletal muscle disuse atrophy, but whether redox imbalance is actually the major cause or simply a consequence of muscle disuse remains of debate. Here we hypothesized that a metabolic stress mediated by PGC‐1α down‐regulation plays a major role in disuse atrophy. First we studied the adaptations of soleus to mice hindlimb unloading (HU) in the early phase of disuse (3 and 7 days of HU) with and without antioxidant treatment (trolox). HU caused a reduction in cross‐sectional area, redox status alteration (NRF2, SOD1 and catalase up‐regulation), and induction of the ubiquitin proteasome system (MuRF‐1 and atrogin‐1 mRNA up‐regulation) and autophagy (Beclin1 and p62 mRNA up‐regulation). Trolox completely prevented the induction of NRF2, SOD1 and catalase mRNAs, but not atrophy or induction of catabolic systems in unloaded muscles, suggesting that oxidative stress is not a major cause of disuse atrophy. HU mice showed a marked alteration of oxidative metabolism. PGC‐1α and mitochondrial complexes were down‐regulated and DRP1 was up‐regulated. To define the link between mitochondrial dysfunction and disuse muscle atrophy we unloaded mice overexpressing PGC‐1α. Transgenic PGC‐1α animals did not show metabolic alteration during unloading, preserving muscle size through the reduction of autophagy and proteasome degradation. Our results indicate that mitochondrial dysfunction plays a major role in disuse atrophy and that compounds inducing PGC‐1α expression could be useful to treat/prevent muscle atrophy.
Catecholamine exocytosis during low frequency stimulation in mouse adrenal chromaffin cells is primarily asynchronous and controlled by the novel mechanism of Ca2+ syntilla suppression
Authors: Lefkowitz Jason J. , DeCrescenzo Valerie , Duan Kailai , Bellve Karl D. , Fogarty Kevin E. , Walsh John V. , ZhuGe Ronghua 
Published: August 2014

Key points
Although the importance of asynchronous exocytosis is becoming clearer, not enough is known about its roles and mechanisms.
Here we describe the nature of exocytosis in mouse adrenal chromaffin cells during low frequency physiological stimulation, i.e. 0.5 Hz, providing new views.
We report that less than 10% of all catecholaminergic exocytosis during low frequency stimulation is synchronized to a simulated action potential (sAP), i.e. the dominant phase is asynchronous.
This asynchronous phase of exocytosis does not require Ca2+ influx, requires the ryanodine receptor, RyR2, and comprises exocytic events with characteristics similar to those of spontaneous events.
We propose a novel mechanism of disinhibition wherein APs inhibit Ca2+ syntillas, relieving their inhibition of spontaneous exocytosis, which leads to an increase in the asynchronous phase of elicited exocytosis.
The work has the specific physiological implication that basal sympathetic tone associated with the ‘rest and digest’ state is set in part by Ca2+ syntillas. Furthermore, there is evidence that this regulation of exocytosis by Ca2+ syntillas may be a general mechanism that extends to neurons.
AbstractAdrenal chromaffin cells (ACCs), stimulated by the splanchnic nerve, generate action potentials (APs) at a frequency near 0.5 Hz in the resting physiological state, at times described as ‘rest and digest’. How such low frequency stimulation in turn elicits sufficient catecholamine exocytosis to set basal sympathetic tone is not readily explained by the classical mechanism of stimulus–secretion coupling, where exocytosis is synchronized to AP‐induced Ca2+ influx. By using simulated action potentials (sAPs) at 0.5 Hz in isolated patch‐clamped mouse ACCs, we show here that less than 10% of all catecholaminergic exocytosis, measured by carbon fibre amperometry, is synchronized to an AP. The asynchronous phase, the dominant phase, of exocytosis does not require Ca2+ influx. Furthermore, increased asynchronous exocytosis is accompanied by an AP‐dependent decrease in frequency of Ca2+ syntillas (i.e. transient, focal Ca2+ release from internal stores) and is ryanodine sensitive. We propose a mechanism of disinhibition, wherein APs suppress Ca2+ syntillas, which themselves inhibit exocytosis as they do in the case of spontaneous catecholaminergic exocytosis.
Plasticity in the brainstem vagal circuits controlling gastric motor function triggered by corticotropin releasing factor
Authors: Browning Kirsteen N. , Babic Tanja , Toti Luca , Holmes Gregory M. , Coleman F. Holly , Travagli R. Alberto 
Published: August 2014

Key points
The prototypical stress hormone, corticotropin releasing factor (CRF), and the prototypical anti‐stressor hormone, oxytocin (OXT), are known to modulate brainstem neurocircuits involved in visceral reflexes.
We demonstrated recently that the brainstem neurocircuits through which OXT exerts its actions are modulated by vagal afferent fibres; however, it is unknown whether the OXT‐induced modulation of brainstem vagal neurocircuits is also regulated differentially by CRF.
Here we elucidate the cellular mechanisms and the effects on gastric tone of OXT following exposure of vagal brainstem neurones to CRF and report that CRF induces short‐term plastic changes in OXT‐sensitive vagal neurocircuits.
The results presented may represent a possible mechanism through which stress alters the central regulation of gastrointestinal functions and may reflect the vagal dysregulation occurring as a consequence of stress‐exacerbated functional dyspepsia.
AbstractStress impairs gastric emptying, reduces stomach compliance and induces early satiety via vagal actions. We have shown recently that the ability of the anti‐stress neuropeptide oxytocin (OXT) to modulate vagal brainstem circuits undergoes short‐term plasticity via alterations in cAMP levels subsequent to vagal afferent fibre‐dependent activation of metabotropic glutamate receptors. The aim of the present study was to test the hypothesis that the OXT‐induced gastric response undergoes plastic changes in the presence of the prototypical stress hormone, corticotropin releasing factor (CRF). Whole cell patch clamp recordings showed that CRF increased inhibitory GABAergic synaptic transmission to identified corpus‐projecting dorsal motor nucleus of the vagus (DMV) neurones. In naive brainstem slices, OXT perfusion had no effect on inhibitory synaptic transmission; following exposure to CRF (and recovery from its actions), however, re‐application of OXT inhibited GABAergic transmission in the majority of neurones tested. This uncovering of the OXT response was antagonized by pretreatment with protein kinase A or adenylate cyclase inhibitors, H89 and di‐deoxyadenosine, respectively, indicating a cAMP‐mediated mechanism. In naive animals, OXT microinjection in the dorsal vagal complex induced a NO‐mediated corpus relaxation. Following CRF pretreatment, however, microinjection of OXT attenuated or, at times reversed, the gastric relaxation which was insensitive to l‐NAME but was antagonized by pretreatment with a VIP antagonist. Immunohistochemical analyses of vagal motoneurones showed an increased number of oxytocin receptors present on GABAergic terminals of CRF‐treated or stressed vs. naive rats. These results indicate that CRF alters vagal inhibitory circuits that uncover the ability of OXT to modulate GABAergic currents and modifies the gastric corpus motility response to OXT.
Different fixational eye movements mediate the prevention and the reversal of visual fading
Authors: McCamy Michael B. , Macknik Stephen L. , Martinez‐Conde Susana 
Published: August 2014

Key points
Fixational eye movements (microsaccades, drift and tremor) are thought to improve visibility during fixation by thwarting neural adaptation to unchanging stimuli, but how the different fixational eye movements influence this process is a matter of debate.
Previous studies confounded the reversal of fading (where vision is restored after fading) with its prevention (where fading is blocked before it happens). We found that, whereas microsaccades are most important to reversing fading, both microsaccades and drift help to prevent it.
Drift's contribution to preventing fading is potentially larger than that of microsaccades, but microsaccades prevent fading with higher efficacy than drift.
Microsaccades prevent foveal and peripheral fading in an equivalent fashion, and microsaccadic efficacy does not depend on microsaccade size, number, or direction; further, faster drift may prevent fading better than slower drift.
These combined findings help reconcile the long‐standing controversy concerning the roles of microsaccades and drift in visibility during fixation.
AbstractFixational eye movements (FEMs; including microsaccades, drift and tremor) are thought to improve visibility during fixation by thwarting neural adaptation to unchanging stimuli, but how the different FEM types influence this process is a matter of debate. Attempts to answer this question have been hampered by the failure to distinguish between the prevention of fading (where fading is blocked before it happens in the first place) and the reversal of fading (where vision is restored after fading has already occurred). Because fading during fixation is a detriment to clear vision, the prevention of fading, which avoids visual degradation before it happens, is a more desirable scenario than improving visibility after fading has occurred. Yet previous studies have not examined the role of FEMs in the prevention of fading, but have focused on visual restoration instead. Here we set out to determine the differential contributions and efficacies of microsaccades and drift to preventing fading in human vision. Our results indicate that both microsaccades and drift mediate the prevention of visual fading. We also found that drift is a potentially larger contributor to preventing fading than microsaccades, although microsaccades are more effective than drift. Microsaccades moreover prevented foveal and peripheral fading in an equivalent fashion, and their efficacy was independent of their size, number, and direction. Our data also suggest that faster drift may prevent fading better than slower drift. These findings may help to reconcile the long‐standing controversy concerning the comparative roles of microsaccades and drift in visibility during fixation.
Determination of cable parameters in skeletal muscle fibres during repetitive firing of action potentials
Authors: Riisager Anders , Duehmke Rudy , Nielsen Ole Bækgaard , Huang Christopher L. , Pedersen Thomas Holm 
Published: August 2014

Key points
Current methods for determination of the resting membrane conductance in active, action potential‐firing muscle fibres are based on the assumptions that the volume and the cytosolic composition of the fibres remain constant during activity.
Here, we present a microelectrode‐based method that without such assumptions measures a range of cable parameters including the resting membrane conductance together with action potential characteristics of individual fibres during intermittent action potential firing.
The method can be used to study the role of activity‐induced regulation of the resting membrane conductance for action potential excitation and propagation in active muscles.
AbstractRecent studies in rat muscle fibres show that repetitive firing of action potentials causes changes in fibre resting membrane conductance (Gm) that reflect regulation of ClC‐1 Cl− and KATP K+ ion channels. Methodologically, these findings were obtained by inserting two microelectrodes at close proximity in the same fibres enabling measurements of fibre input resistance (Rin) in between action potential trains. Since the fibre length constant (λ) could not be determined, however, the calculation of Gm relied on the assumptions that the specific cytosolic resistivity (Ri) and muscle fibre volume remained constant during the repeated action potential firing. Here we present a three‐microelectrode technique that enables determinations of multiple cable parameters in action potential‐firing fibres including Rin and λ as well as waveform and conduction velocities of fully propagating action potentials. It is shown that in both rat and mouse extensor digitorum longus (EDL) fibres, action potential firing leads to substantial changes in both muscle fibre volume and Ri. The analysis also showed, however, that regardless of these changes, rat and mouse EDL fibres both exhibited initial decreases in Gm that were eventually followed by a ∼3‐fold, fully reversible increase in Gm after the firing of 1450–1800 action potentials. Using this three‐electrode method we further show that the latter rise in Gm was closely associated with excitation failures and loss of action potential signal above −20 mV.
X-Ray Diffraction Analysis of Kraft Lignins and Lignin-Derived Carbon Nanofibers
Authors: Goudarzi Azadeh , Lin Li-Ting , Ko Frank K. 
Published: August 2014

AbstractLignin is a renewable material and it is abundantly available as low priced industrial residue. Lignin-based carbon fibers are economically attractive and sustainable. In addition, remarkably oxidized molecule of the lignin decreases the required time and temperature of the thermostabilization process compared to other carbon fiber precursors such as polyacrylonitrile (PAN); and thus, decreases the processing cost of carbon fiber production. The fraction 4 of softwood Kraft lignin (SKL-F4) was previously shown to be spinnable via electrospinning to produce carbon nanofibers. In this paper, we characterized different Kraft lignin powders through X-ray diffraction (XRD) analysis to measure the mean size of the ordered domains in different fractionations of softwood and hardwood samples. According to our results, SKL-F4 has largest ordered domains among SKLs and highest hydroxyl content according to Fourier transform infrared (FTIR) analysis. In addition, variations in the XRD patterns during carbon nanofiber formation were studied and the peak for (101) plane in graphite was observed in the carbon nanofiber carbonized at 1000 °C.
Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session
Authors: Callewaert Chris , De Maeseneire Evelyn , Kerckhof Frederiek-Maarten , Verliefde Arne , Van de Wiele Tom , Boon Nico 
Published: August 2014

ABSTRACT

Clothing textiles protect our human body against external factors. These textiles are not sterile and can harbor high bacterial counts as sweat and bacteria are transmitted from the skin. We investigated the microbial growth and odor development in cotton and synthetic clothing fabrics. T-shirts were collected from 26 healthy individuals after an intensive bicycle spinning session and incubated for 28 h before analysis. A trained odor panel determined significant differences between polyester versus cotton fabrics for the hedonic value, the intensity, and five qualitative odor characteristics. The polyester T-shirts smelled significantly less pleasant and more intense, compared to the cotton T-shirts. A dissimilar bacterial growth was found in cotton versus synthetic clothing textiles. Micrococci were isolated in almost all synthetic shirts and were detected almost solely on synthetic shirts by means of denaturing gradient gel electrophoresis fingerprinting. A selective enrichment of micrococci in an
in vitro
growth experiment confirmed the presence of these species on polyester. Staphylococci were abundant on both cotton and synthetic fabrics. Corynebacteria were not enriched on any textile type. This research found that the composition of clothing fibers promotes differential growth of textile microbes and, as such, determines possible malodor generation.
Strain Diversity of CTX-M-Producing Enterobacteriaceae in Individual Pigs: Insights into the Dynamics of Shedding during the Production Cycle
Authors: Hansen Katrine Hartung , Bortolaia Valeria , Damborg Peter , Guardabassi Luca 
Published: August 2014

ABSTRACT

The aim of this study was to evaluate the population dynamics of CTX-M-producing
Enterobacteriaceae
in individual pigs on a farm positive for CTX-M-14-producing
Escherichia coli
. Fecal samples were collected once around the farrowing time from five sows and four times along the production cycle from two of their respective offspring. Multiple colonies per sample were isolated on cefotaxime-supplemented MacConkey agar with or without prior enrichment, resulting in 98 isolates identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry and tested for
bla
CTX-M
. CTX-M-positive isolates (
n
= 86) were typed by pulsed-field gel electrophoresis (PFGE). Plasmids harboring
bla
CTX-M
were characterized in 22 representative isolates by replicon typing and restriction fragment length polymorphism. Based on the PFGE results, all individuals shed unrelated CTX-M-14-producing
E. coli
strains during the course of life. Concomitant shedding of CTX-M-2/97-producing
Proteus mirabilis
or
Providencia rettgeri
was observed in two sows and two offspring. At least two genetically unrelated CTX-M-producing
E. coli
strains were isolated from approximately one-fourth of the samples, with remarkable differences between isolates obtained by enrichment and direct plating. A clear decrease in strain diversity was observed after weaning. Dissemination of
bla
CTX-M-14
within the farm was attributed to horizontal transfer of an IncK plasmid that did not carry additional resistance genes and persisted in the absence of antimicrobial selective pressure. Assessment of strain diversity was shown to be influenced by the production stage from which samples were collected, as well as by the isolation method, providing useful information for the design and interpretation of future epidemiological studies of CTX-M-producing
Enterobacteriaceae
in pig farms.
Analysis of the
xplAB
-Containing Gene Cluster Involved in the Bacterial Degradation of the Explosive Hexahydro-1,3,5-Trinitro-1,3,5-Triazine
Authors: Chong Chun Shiong , Sabir Dana Khdr , Lorenz Astrid , Bontemps Cyril , Andeer Peter , Stahl David A. , Strand Stuart E. , Rylott Elizabeth L. , Bruce Neil C. 
Published: August 2014

ABSTRACT

Repeated use of the explosive compound hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) on military land has resulted in significant soil and groundwater pollution. Rates of degradation of RDX in the environment are low, and accumulated RDX, which the U.S. Environmental Protection Agency has determined is a possible human carcinogen, is now threatening drinking water supplies. RDX-degrading microorganisms have been isolated from RDX-contaminated land; however, despite the presence of these species in contaminated soils, RDX pollution persists. To further understand this problem, we studied RDX-degrading species belonging to four different genera (
Rhodococcus
,
Microbacterium
,
Gordonia
, and
Williamsia
) isolated from geographically distinct locations and established that the
xplA
and
xplB
(
xplAB
) genes, which encode a cytochrome P450 and a flavodoxin redox partner, respectively, are nearly identical in all these species. Together, the
xplAB
system catalyzes the reductive denitration of RDX and subsequent ring cleavage under aerobic and anaerobic conditions. In addition to
xplAB
, the
Rhodococcus
species studied here share a 14-kb region flanking
xplAB
; thus, it appears likely that the RDX-metabolizing ability was transferred as a genomic island within a transposable element. The conservation and transfer of
xplAB
-flanking genes suggest a role in RDX metabolism. We therefore independently knocked out genes within this cluster in the RDX-degrading species
Rhodococcus rhodochrous
11Y. Analysis of the resulting mutants revealed that XplA is essential for RDX degradation and that XplB is not the sole contributor of reducing equivalents to XplA. While XplA expression is induced under nitrogen-limiting conditions and further enhanced by the presence of RDX, MarR is not regulated by RDX.
Characterization of Novel Polycyclic Aromatic Hydrocarbon Dioxygenases from the Bacterial Metagenomic DNA of a Contaminated Soil
Authors: Chemerys Angelina , Pelletier Eric , Cruaud Corinne , Martin Florence , Violet Fabien , Jouanneau Yves 
Published: August 2014

ABSTRACT

Ring-hydroxylating dioxygenases (RHDs) play a crucial role in the biodegradation of a range of aromatic hydrocarbons found on polluted sites, including polycyclic aromatic hydrocarbons (PAHs). Current knowledge on RHDs comes essentially from studies on culturable bacterial strains, while compelling evidence indicates that pollutant removal is mostly achieved by uncultured species. In this study, a combination of DNA-SIP labeling and metagenomic sequence analysis was implemented to investigate the metabolic potential of main PAH degraders on a polluted site. Following
in situ
labeling using [
13
C]phenanthrene, the labeled metagenomic DNA was isolated from soil and subjected to shotgun sequencing. Most annotated sequences were predicted to belong to
Betaproteobacteria
, especially
Rhodocyclaceae
and
Burkholderiales
, which is consistent with previous findings showing that main PAH degraders on this site were affiliated to these taxa. Based on metagenomic data, four RHD gene sets were amplified and cloned from soil DNA. For each set, PCR yielded multiple amplicons with sequences differing by up to 321 nucleotides (17%), reflecting the great genetic diversity prevailing in soil. RHDs were successfully overexpressed in
Escherichia coli
, but full activity required the coexpression of two electron carrier genes, also cloned from soil DNA. Remarkably, two RHDs exhibited much higher activity when associated with electron carriers from a sphingomonad. The four RHDs showed markedly different preferences for two- and three-ring PAHs but were poorly active on four-ring PAHs. Three RHDs preferentially hydroxylated phenanthrene on the C-1 and C-2 positions rather than on the C-3 and C-4 positions, suggesting that degradation occurred through an alternate pathway.