pinecone/core-2020-05-10-deduplication huggingface dataset:
Airway obstruction, dynamic hyperinflation, and breathing pattern during incremental exercise in COPD patients

Ventilatory capacity is reduced in chronic obstructive pulmonary disease
(COPD) patients. Tidal volume (VT) is lower and breathing frequency higher
at a given ventilation (VE) compared to healthy subjects. We examined
whether airflow limitation and dynamic hyperinflation in COPD patients were
related to breathing pattern. An incremental treadmill exercise test was performed
in 63 COPD patients (35 men), aged 65 years (48–79 years) with a
mean forced expiratory volume in 1 sec (FEV1) of 48% of predicted
(SD = 15%). Data were averaged over 20-sec intervals. The relationship
between VE and VT was described by the quadratic equation VT =
a + bVE + cVE² for each subject. The relationships between the curve parameters
b and c, and spirometric variables and dynamic hyperinflation measured
as the difference in inspiratory capacity from start to end of exercise, were
analyzed by multivariate linear regression. The relationship between VE and
VT could be described by a quadratic model in 59 patients with median R2 of
0.90 (0.40–0.98). The linear coefficient (b) was negatively (P = 0.001) and the
quadratic coefficient (c) positively (P < 0.001) related to FEV1. Forced vital
capacity, gender, height, weight, age, inspiratory reserve volume, and dynamic
hyperinflation were not associated with the curve parameters after adjusting
for FEV1. We concluded that a quadratic model could satisfactorily describe
the relationship between VE and VT in most COPD patients. The curve
parameters were related to FEV1. With a lower FEV1, maximal VT was lower
and achieved at a lower VE. Dynamic hyperinflation was not related to breathing
pattern when adjusting for FEV1
Catalyzing role of erythropoietin on the nitric oxide central pathway during the ventilatory responses to hypoxia

International audienceThe N‐Methyl‐d‐Aspartate (NMDA) receptors – neuronal nitric oxide synthase (nNOS) pathway is involved in the ventilatory response to hypoxia. The objective was to assess the possible effect of erythropoietin deficiency and chronic exposure to hypoxia on this pathway during ventilatory response to acute hypoxia. Wild‐type (WT) and erythropoietin‐deficient (Epo‐TAgh) male mice were exposed (14 days) either to hypobaric hypoxia (Pb = 435 mmHg) or to normoxia. The ventilation was measured at 21% or 8% O2 after injection of vehicle (NaCl), nNOS inhibitor (SMTC) or NMDA receptor antagonist (MK‐801). Nitric oxide production and the expression of NMDA receptor and nNOS were assessed by real‐time RT‐PCR and Western blot analyses in the medulla. At rest, Epo‐TAgh mice displayed normal ventilatory parameters at 21% O2 but did not respond to acute hypoxia despite a larger expression of NMDA receptors and nNOS in the medulla. Ventilatory acclimatization to hypoxia was observed in WT but was absent in Epo‐TAgh mice. nNOS inhibition blunted the hypoxic ventilatory acclimatization of WT mice without any effect in Epo‐TAgh mice. Acute hypoxic ventilatory response (HVR) was increased after chronic hypoxia in WT but remained unchanged in Epo‐TAgh mice. Ventilatory response to acute hypoxia was modified by MK‐801 injection in WT and Epo‐TAgh mice. The results confirm that adequate erythropoietin level is necessary to obtain an appropriate HVR and a significant ventilatory acclimatization to hypoxia. Furthermore, erythropoietin plays a potential catalyzing role in the NMDA‐NO central pathway during the ventilatory response and acclimatization to hypoxia
Experimental peripheral arterial disease: new insights into muscle glucose uptake, macrophage, and T-cell polarization during early and late stages.

Peripheral arterial disease (PAD) is a common disease with increasing prevalence, presenting with impaired walking ability affecting patient's quality of life. PAD epidemiology is known, however, mechanisms underlying functional muscle impairment remain unclear. Using a mouse PAD model, aim of this study was to assess muscle adaptive responses during early (1 week) and late (5 weeks) disease stages. Unilateral hindlimb ischemia was induced in ApoE(-/-) mice by iliac artery ligation. Ischemic limb perfusion and oxygenation (Laser Doppler imaging, transcutaneous oxygen pressure assessments) significantly decreased during early and late stage compared to pre-ischemia, however, values were significantly higher during late versus early phase. Number of arterioles and arteriogenesis-linked gene expression increased at later stage. Walking ability, evaluated by forced and voluntary walking tests, remained significantly decreased both at early and late phase without any significant improvement. Muscle glucose uptake ([18F]fluorodeoxyglucose positron emission tomography) significantly increased during early ischemia decreasing at later stage. Gene expression analysis showed significant shift in muscle M1/M2 macrophages and Th1/Th2 T cells balance toward pro-inflammatory phenotype during early ischemia; later, inflammatory state returned to neutrality. Muscular M1/M2 shift inhibition by a statin prevented impaired walking ability in early ischemia. High-energy phosphate metabolism remained unchanged (31-Phosphorus magnetic resonance spectroscopy). Results show that rapid transient muscular inflammation contributes to impaired walking capacity while increased glucose uptake may be a compensatory mechanisms preserving immediate limb viability during early ischemia in a mouse PAD model. With time, increased ischemic limb perfusion and oxygenation assure muscle viability although not sufficiently to improve walking impairment. Subsequent decreased muscle glucose uptake may partly contribute to chronic walking impairment. Early inflammation inhibition and/or late muscle glucose impairment prevention are promising strategies for PAD management
Differential psychophysiological interactions of insular subdivisions during varied oropharyngeal swallowing tasks

Abstract The insula is a highly integrated cortical region both anatomically and functionally. It has been shown to have cognitive, social–emotional, gustatory, and sensorimotor functions. Insular involvement in both normal and abnormal swallowing behavior is well established, yet its functional connectivity is unclear. Studies of context‐dependent connectivity, or the connectivity during different task conditions, have the potential to reveal information about synaptic function of the insula. The goal of this study was to examine the functional connectivity of specific insular regions (ventral anterior, dorsal anterior, and posterior) with distant cortical regions during four swallowing conditions (water, sour, e‐stim, and visual biofeedback) using generalized psychophysiological interactions (gPPI). In 19 healthy adults, we found that the visual biofeedback condition was associated with the most and strongest increases in functional connectivity. The posterior insula/rolandic operculum regions had the largest clusters of increases in functional connectivity, but the ventral anterior insula was functionally connected to a more diverse array of cortical regions. Also, laterality assessments showed left lateralized increases in swallowing functional connectivity. Our results are aligned with reports about the insula's interconnectivity and extensive involvement in multisensory and cognitive tasks
EPO-receptor is present in mouse C2C12 and human primary skeletal muscle cells but EPO does not influence myogenesis.

Abstract The role and regulation of the pleiotropic cytokine erythropoietin (EPO) in skeletal muscle are controversial. EPO exerts its effects by binding its specific receptor (EPO-R), which activates intracellular signaling and gene transcription in response to internal and external stress signals. EPO is suggested to play a direct role in myogenesis via the EPO-R, but several studies have questioned the effect of EPO treatment in muscle in vitro and in vivo. The lack of certainty surrounding the use of nonspecific EPO-R antibodies contributes to the ambiguity of the field. Our study demonstrates that the EPO-R gene and protein are expressed at each stage of mouse C2C12 and human skeletal muscle cell proliferation and differentiation and validates a specific antibody for the detection of the EPO-R protein. However, in our experimental conditions, EPO treatment had no effect on mouse C2C12 and human muscle cell proliferation, differentiation, protein synthesis or EPO-R expression. While an increase in Akt and MAPK phosphorylation was observed, we demonstrate that this effect resulted from the stress caused by changing medium and not from EPO treatment. We therefore suggest that skeletal muscle EPO-R might be present in a nonfunctional form, or too lowly expressed to play a role in muscle cell function
Tactile gating in a reaching and grasping task

This is the final version of the article. It first appeared from Wiley / American Physiological Society via http://dx.doi.org/10.1002/phy2.267Abstract A multitude of events bombard our sensory systems at every moment of our lives. Thus, it is important for the sensory cortex to gate unimportant events. Tactile suppression is a well-known phenomenon defined as a reduced ability to detect tactile events on the skin before and during movement. Previous experiments found detection rates decrease just prior to and during finger abduction, and decrease according to the proximity of the moving effector. This study examined how tactile detection changes during a reach to grasp. Fourteen human participants used their right hand to reach and grasp a cylinder. Tactors were attached to the index finger, the fifth digit, and the forearm of both the right and left arm and vibrated at various epochs relative to a "go" tone. Results showed that detection rates at the forearm decreased before movement onset; whereas at the right index finger, right fifth digit and at the left index finger, left fifth digit, and forearm sites did not decrease like in the right forearm. These results indicate that the task affects gating dynamics in a temporally- and contextually dependent manner and implies that feed-forward motor planning processes can modify sensory signals.The authors thank the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation (CFI), and the British Columbia Knowledge Development Fund (BCKDF) for supporting this research
Influence of CO2 on neurovascular coupling: interaction with dynamic cerebral autoregulation and cerebrovascular reactivity

Abstract PaCO2 affects cerebral blood flow (CBF) and its regulatory mechanisms, but the interaction between neurovascular coupling (NVC), cerebral autoregulation (CA), and cerebrovascular reactivity to CO2 (CVR), in response to hypercapnia, is not known. Recordings of cerebral blood flow velocity (CBFv), blood pressure (BP), heart rate, and end-tidal CO2 (EtCO2) were performed in 18 subjects during normocapnia and 5% CO2 inhalation while performing a passive motor paradigm. Together with BP and EtCO2, a gate signal to represent the effect of stimulation was used as input to a multivariate autoregressive-moving average model to calculate their separate effects on CBFv. Hypercapnia led to a depression of dynamic CA at rest and during stimulation in both hemispheres (P < 0.02) as well as impairment of the NVC response, particularly in the ipsilateral hemisphere (P < 0.01). Neither hypercapnia nor the passive motor stimulation influenced CVR. Dynamic CA was not influenced by the motor paradigm during normocapnia. The CBFv step responses to each individual input (BP, EtCO2, stimulation) allowed identification of the influences of hypercapnia and neuromotor stimulation on CA, CVR, and NVC, which have not been previously described, and also confirmed the depressing effects of hypercapnia on CA and NVC. The stability of CVR during these maneuvers and the lack of influence of stimulation on dynamic CA are novel findings which deserve further investigation. Dynamic multivariate modeling can identify the complex interplay between different CBF regulatory mechanisms and should be recommended for studies involving similar interactions, such as the effects of exercise or posture on cerebral hemodynamics.Peer-reviewedPublisher Versio
Effect of simvastatin in the autonomic system is dependent on the increased gain/sensitivity of the baroreceptors

A number of mechanisms have been proposed to explain the pleiotropic effect of statin therapy to reduce sympathetic outflow in cardiovascular disease. We tested the hypothesis that statin treatment could improve baroreflex gain-sensitivity triggered by morphological adaptations in the mechanoreceptor site, thus reducing sympathetic activity, regardless of arterial pressure (AP) level reduction. Male spontaneously hypertensive rats (SHR) were divided into control (SHR, n = 8) and SHR-simvastatin (5 mg/kg/day, for 7 days) (SHR-S, n = 8). After treatment, AP, baroreflex sensitivity (BRS) in response to AP-induced changes, aortic depressor nerve activity, and spectral analyses of pulse interval (PI) and AP variabilities were performed. Internal and external carotids were prepared for morphoquantitative evaluation. Although AP was similar between groups, sympathetic modulation, represented by the low frequency band of PI (SHR: 6.84 ± 3.19 vs. SHR-S: 2.41 ± 0.96 msec2) and from systolic AP variability (SHR: 3.95 ± 0.36 vs. SHR-S: 2.86 ± 0.18 mmHg2), were reduced in treated animals. In parallel, simvastatin induced an increase of 26% and 21% in the number of elastic lamellae as well as a decrease of 9% and 25% in the carotid thickness in both, external and internal carotid, respectively. Moreover, improved baroreceptor function (SHR: 0.78 ± 0.03 vs. SHR-S: 1.06 ± 0.04% mv/mmHg) was observed in addition to a 115% increase in aortic depressor nerve activity in SHR-S rats. Therefore, our data suggest that the reduction of sympathetic outflow in hypertension by simvastatin treatment may be triggered by structural changes in the carotid arteries and increased BRS in response to an improvement of the baroreceptors discharge and consequently of the afferent pathway of the baroreflex arch.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP- 01/00,009-0; 2012/20,141-5)Fundação E.J. ZerbiniConselho Nacional de Pesquisa e Desenvolvimento (CNPq
Human muscle response to sprint exercise and nutrient supply with focus on factors related to protein metabolism

The overall aim of the present thesis was to study the muscular response to repeated bouts of
30-s sprint exercise. This type of exercise gives rise to a profound metabolic perturbation that
might counteract an exercise-induced stimulation of muscle protein synthesis. Special focus
was paid upon nutritional supply and how it can direct the muscular response towards
activation of amino acid sensors, cell signalling pathway and muscle protein synthesis. Some
questions were analysed by gender.

It was hypothesised that: Amino acids decrease and ammonia increases following sprint
exercise and more so in males than females.

Activation of mTOR signalling increases more in females than males in skeletal muscle
following sprint exercise. Oral ingestion of essential amino acids and carbohydrates increases
the amino acid sensor Vps34 activity, the amino acid transporter and sensor SNAT2,
Akt/mTOR signalling and consequently enhances the rate of muscle protein synthesis in
skeletal muscle following sprint exercise.

It is concluded that: Plasma leucine decreased and plasma and muscle ammonia increased
following sprint exercise and more so in in males than females. Such changes might
counteract a possible sprint exercise-induced stimulation of muscle protein synthesis. There
was some activation of mTOR signalling in skeletal muscle following sprint exercise and
more so in females than males. The larger increase in serum insulin and lower decrease in
plasma leucine in females might have contributed to the enhanced signalling response in
females. Oral ingestion of essential amino acids and carbohydrates, as compared to placebo,
resulted in a markedly higher activation of Akt/mTOR signalling in skeletal muscle following
sprint exercise. In contrast to the hypothesis, an oral ingestion of essential amino acids and
carbohydrates did not result in an increased activation of hVps34 in skeletal muscle.
However, this does not exclude the permissive role of hVps34 in mediating the amino acidinduced activation of Akt/mTOR signalling and skeletal muscle protein synthesis. The
interaction between the condition (nutrients or placebo) and correlation between increase in
Vps34 activity and increase plasma glucose may reflect the dual role of Vps34, i.e. sensing a
nutrient-rich condition and activate mTOR or sensing a nutrient-poor condition and activate
autophagy in order to counteract low levels of amino acids. Oral ingestion of essential amino
acids and carbohydrates resulted in a higher SNAT2 expression, a higher activation of
Akt/mTOR signalling and higher rate of muscle protein synthesis following sprint exercise.
Thus, nutrients have a potential to stimulate muscle protein synthesis and related pathways
after sprint exercise, in spite of the profound metabolic perturbation
The spontaneous electrical activity of neurons in leech ganglia

Using the newly developed voltage-sensitive dye VF2.1.Cl, we monitored simultaneously the spontaneous electrical activity of ∼80 neurons in a leech ganglion, representing around 20% of the entire neuronal population. Neurons imaged on the ventral surface of the ganglion either fired spikes regularly at a rate of 1-5 Hz or fired sparse spikes irregularly. In contrast, neurons imaged on the dorsal surface, fired spikes in bursts involving several neurons. The overall degree of correlated electrical activity among leech neurons was limited in control conditions but increased in the presence of the neuromodulator serotonin. The spontaneous electrical activity in a leech ganglion is segregated in three main groups: neurons comprising Retzius cells, Anterior Pagoda, and Annulus Erector motoneurons firing almost periodically, a group of neurons firing sparsely and randomly, and a group of neurons firing bursts of spikes of varying durations. These three groups interact and influence each other only weakly
Hypovolemia explains the reduced stroke volume at altitude

During acute altitude exposure tachycardia increases cardiac output (Q) thus preserving systemic O2 delivery. Within days of acclimatization, however, Q normalizes following an unexplained reduction in stroke volume (SV). To investigate whether the altitude-mediated reduction in plasma volume (PV) and hence central blood volume (CBV) is the underlying mechanism we increased/decreased CBV by means of passive whole body head-down (HDT) and head-up (HUT) tilting in seven lowlanders at sea level (SL) and after 25/26 days of residence at 3454 m. Prior to the experiment on day 26, PV was normalized by infusions of a PV expander. Cardiovascular responses to whole body tilting were monitored by pulse contour analysis. After 25/26 days at 3454 m PV and blood volume decreased by 9 ± 4% and 6 ± 2%, respectively (P < 0.001 for both). SV was reduced compared to SL for each HUT angle (P < 0.0005). However, the expected increase in SV from HUT to HDT persisted and ended in the same plateau as at SL, albeit this was shifted 18 ± 20° toward HDT (P = 0.019). PV expansion restored SV to SL during HUT and to an ∼8% higher level during HDT (P = 0.003). The parallel increase in SV from HUT to HDT at altitude and SL to a similar plateau demonstrates an unchanged dependence of SV on CBV, indicating that the reduced SV during HUT was related to an attenuated CBV for a given tilt angle. Restoration of SV by PV expansion rules out a significant contribution of other mechanisms, supporting that resting SV at altitude becomes reduced due to a hypovolemia
Effect of synthesis parameters on the electrical conductivity of polypyrrole-coated poly(ethylene terephthalate) fabrics

The effects of pyrrole, anthraquinone-2-sulphonic acid (AQSA) and iron(III) chloride (FeCl3) concentrations, reaction time and temperature on the electrical conductivity of polypyrrole (PPy) - coated poly(ethylene terephthalate) (PET) fabrics were investigated. With an increase in both the AQSA and FeCl3 concentrations, resistivity decreased to a point beyond which higher concentrations led to increased surface resistivity. Erosion of the polymer coating, in dynamic synthesis from continual abrasion, manifested as an exponential increase in the resistance of the coated textile substrate. This was not encountered in static synthesis conditions. Temperature affected the degree of surface and bulk polymerisation. The effect of polymerisation temperature on conductivity was negligible. Conductive polymer coating on textiles through chemical polymerisation enabled a smooth coherent film to encase individual fibres, which did not affect the tactile properties of the host substrate. The optimum FeCl3/pyrrole and AQSA FeCl3/pyrrole molar ratios were found to be 2.22 and 0.40 respectively. <br /
Calorimetric and rheological characterization of a high-performance epoxy curable at low temperatures

Curing and gelation of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane (TGDDM-Araldite MY721), in the presence of an anhydride hardener mixture was studied by calorimetric and dynamic rheological measurements. Cure kinetics of the homogeneous and low temperature curable epoxy-system were evaluated from 40oC to 140oC and apparent activation energies of the curing reaction were calculated from different thermokinetic models. By comparison of different calorimetric and rheological methods, it was found that the results from the isothermal calorimetric measurements are in a good agreement with the results obtained from isothermal rheological experiments, while the kinetic parameter calculations based on dynamic calorimetric measurements are not reliable results. These differences mainly arise from the fact that dynamic measurements have many underlying assumptions and do not consider the equilibrium condition
Curing kinetics and thermomechanical behaviour of co-anhydride cured aminoglycidyl epoxy resins

Curing behaviour and thermo-mechanical properties of a technical grade of N,N,N’,N’-tetraglycidyl-4,4’-diamino-diphenylmethane (TGDDM-Araldite MY721), cured in the presence of an anhydride hardener mixture consisting of maleic anhydride (MA) and pyromellitic acid dianhydride (PMDA) was studied by calorimetric and dynamic mechanical analysis. Cure kinetics and the influence of varying stoichiometric anhydride to epoxy ratios were evaluated and the apparent activation energy was calculated according to Barrett’s method. High extents of conversion from DSC studies of the MY721-resin were reached after a room temperature cure, without an added catalyst, for 24 hours followed by a post-curing step of 1 hour at 90°C. Ultimate glass transition temperatures for the molar anhydride/epoxy ratio, r=0.8 were close to the decomposition temperature and indications were obtained that the network structure consists of two independent sub-networks. It is suggested that two separate mechanisms contribute to the curing reaction at room temperature. First the tertiary amine structure, intrinsic to aminoglycidyl-resins, may act as an internal catalyst for the anhydride ring opening, and secondly, the unsaturated bond of MA participates in the curing reaction by nucleophilic attack, such as from tertiary amines or carboxylate or alkoxide anions. From a study of a range of different amino-glycidyl resins, this low-temperature curing behaviour is found to be a general phenomenon