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Journal of Applied Physiology

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https://www.readbyqxmd.com/read/28798205/cardiac-output-by-pulse-contour-analysis-does-not-match-the-increase-measured-by-rebreathing-during-human-spaceflight
#1
Richard L Hughson, Sean D Peterson, Nicholas J Yee, Danielle K Greaves
Pulse contour analysis of the non-invasive finger arterial pressure waveform provides a convenient means to estimate cardiac output (Q ̇). The method has been compared to standard methods under a range of conditions but never before during spaceflight. We compared pulse contour analysis with the Modelflow algorithm to estimates of Q ̇ obtained by rebreathing during pre-flight baseline testing and during the final month of long-duration spaceflight in nine healthy male astronauts. By Modelflow analysis, stroke volume was greater in supine baseline than seated baseline or inflight...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798204/imaging-igf-i-uptake-in-growth-plate-cartilage-using-in-vivo-multiphoton-microscopy
#2
Maria A Serrat, Gabriela Ion
Bones elongate through endochondral ossification in cartilaginous growth plates located at ends of primary long bones. Linear growth ensues from a cascade of biochemical signals initiated by actions of systemic and local regulators on growth plate chondrocytes. Although cellular processes are well defined, there is a fundamental gap in understanding how growth regulators are physically transported from surrounding blood vessels into and through dense, avascular cartilage matrix. Intravital imaging using in vivo multiphoton microscopy is one promising strategy to overcome this barrier by quantitatively tracking molecular delivery to cartilage from the vasculature in real time...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798203/peripheral-ventilation-heterogeneity-determines-the-extent-of-bronchoconstriction-in-asthma
#3
Catherine E Farrow, Cheryl M Salome, Benjamin E Harris, Dale L Bailey, Norbert Berend, Gregory G King
In asthma, bronchoconstriction causes topographically heterogeneous airway narrowing, as measured by 3-dimensional ventilation imaging. Computation modelling suggests that peripheral airway dysfunction is a potential determinant of acute airway narrowing measured by imaging. We hypothesised that the development of low ventilation regions measured topographically by 3-dimensional imaging after bronchoconstriction is predicted by peripheral airway function. Fourteen (14) asthmatic subjects underwent ventilation Single Photon Emission Computed Tomography/CT (VSPECT/CT) before and after methacholine challenge...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798202/aerobic-exercise-elevates-markers-of-angiogenesis-and-macrophage-il6-gene-expression-in-the-subcutaneous-adipose-tissue-of-overweight-to-obese-adults
#4
Douglas W Van Pelt, Lisa M Guth, Jeffrey F Horowitz
Alterations in the inflammatory state, metabolic function, and structure of subcutaneous adipose tissue (SAT) can impact the development of insulin resistance in obesity. Exercise can improve metabolic health in obesity, but the effects of exercise on SAT are not well known. The purpose of this study was to examine the effects of acute exercise and habitual exercise training on mRNA expression of markers of lipid metabolism, inflammation, fibrosis, and hypoxia/angiogenesis in SAT, as well as adipocyte cell size...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798201/remote-ischemic-preconditioning-does-not-prevent-acute-mountain-sickness-after-rapid-ascent-to-3450-m
#5
Marc M Berger, Franziska Macholz, Lukas Lehmann, Daniel Dankl, Marcel Hochreiter, Bernhard Bacher, Peter Bärtsch, Heimo Mairbäurl
Remote ischemic preconditioning (RIPC) has been shown to protect remote organs, such as the brain and the lung, from damage induced by subsequent hypoxia or ischemia. Acute mountain sickness (AMS) is a syndrome of non-specific neurologic symptoms and in high altitude pulmonary edema excessive hypoxic pulmonary vasoconstriction (HPV) plays a pivotal role. We hypothesized that RIPC protects the brain from AMS and attenuates the magnitude of HPV after rapid ascent to 3450 m. Forty non-acclimatized volunteers were randomized into 2 groups...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798200/wearable-physiological-monitoring-for-human-thermal-work-strain-optimization
#6
Mark J Buller, Alexander Pearson Welles, Karl E Friedl
Safe performance limits of soldiers and athletes have typically relied on predictive work-rest models of ambient conditions, average work intensity, and characteristics of the population. Bioengineering advances in noninvasive sensor technologies including miniaturization, reduced cost, power requirements, and comfort now make it possible to produce individual predictions of safe thermal-work limits. These precision medicine assessments depend on the development of thoughtful algorithms based on physics and physiology...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798199/human-cerebral-blood-flow-control-during-hypoxia-focus-on-chronic-pulmonary-obstructive-disease-copd-and-obstructive-sleep-apnea-osa
#7
Andrew E Beaudin, Sara E Hartmann, Matiram Pun, Marc J Poulin
The brain is a vital organ that relies on a constant and adequate blood flow to match oxygen and glucose delivery with the local metabolic demands of active neurons. Thus, exquisite regulation of cerebral blood flow (CBF) is particularly important under hypoxic conditions to prevent a detrimental decrease in the partial pressure of oxygen within the brain tissues. Cerebrovascular sensitivity to hypoxia, assessed as the change in CBF during a hypoxic challenge, represents the capacity of cerebral vessels to respond to, and compensate for, a reduced oxygen supply, and has been shown to be impaired or blunted in a number of conditions...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798198/wearable-ballistocardiogram-and-seismocardiogram-systems-for-health-and-performance
#8
Mozziyar Etemadi, Omer T Inan
Cardiovascular diseases (CVDs) are prevalent in the US and many forms of CVDs primarily affect the mechanical aspects of heart function. Wearable technologies for monitoring the mechanical health of the heart and vasculature could enable proactive management of CVDs through titration of care based on physiological status, as well as preventative wellness monitoring to help promote lifestyle choices that reduce the overall risk of developing CVDs. Additionally, such wearable technologies could be used to optimize human performance in austere environments...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798197/corp-measurement-of-lung-function-in-small-animals
#9
Jason H T Bates
The measurement of lung function in mice and rats is crucial for understanding how well small animal models of pulmonary disease recapitulate human clinical pathology, but brings with it the challenge of making accurate measurements in animals as small as a mouse. Overcoming these challenges can be achieved in a number of ways, each based on a model idealization of how the lung works as a mechanical system. Accordingly, it is important to understand the theoretical basis on which an assessment of lung function rests in order to interpret experimental measurements appropriately...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798196/the-hypoxia-adenosine-link-during-inflammation
#10
Jessica L Bowser, Jae W Lee, Xiaoyi Yuan, Holger K Eltzschig
Hypoxic tissue conditions occur during a number of inflammatory diseases and are associated with the breakdown of barriers and induction of pro-inflammatory responses. At the same time, hypoxia is also known to induce several adaptive and tissue-protective pathways that dampen inflammation and protect tissue integrity. Hypoxia inducible factors (HIFs) that are stabilized during inflammatory or hypoxic conditions are at the center of mediating these responses. In the past decade, several genes regulating extracellular adenosine metabolism and signaling have been identified as being direct targets of HIFs...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775071/the-acute-effects-of-long-acting-bronchodilators-on-small-airways-detected-in-copd-patients-by-single-breath-n2-test-and-lung-p-v-curve
#11
Matteo M Pecchiari, Pierachille Santus, Dejan Radovanovic, Edgardo Giacomo D'Angelo
Small airways represent the key factor of chronic obstructive pulmonary disease (COPD) pathophysiology. The effect of different classes of bronchodilators on small airways is still poorly understood and difficult to assess. Hence, the acute effects of tiotropium (18 µg) and indacaterol (150 µg) on closing volume (CV) and ventilation inhomogeneity were investigated and compared in 51 stable patients (mean age (SD): 70±7 years; 82% males) with moderate to very severe COPD. Patients underwent body-plethysmography, arterial blood gas-analysis, tidal expiratory flow limitation (EFL), dyspnea assessment, and simultaneous recording of single breath nitrogen test (SBN) and transpulmonary pressure-volume curve (PL-V), before and one hour after drug administration...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775070/elevated-airway-liquid-volumes-at-birth-a-potential-cause-of-transient-tachypnea-of-the-newborn
#12
Erin Victoria McGillick, Katie Lee, Shigeo Yamaoka, Arjan B Te Pas, Kelly J Crossley, Megan J Wallace, Marcus John Kitchen, Robert A Lewis, Lauren T Kerr, Philip DeKoninck, Janneke Dekker, Marta Thio, Annie McDougall, Stuart B Hooper
Excessive liquid in airways and/or in distal lung tissue may underpin the respiratory morbidity associated with transient tachypnea of the newborn (TTN). However, its effects on lung aeration and respiratory function following birth are unknown. We investigated the effect of elevated airway liquid volumes on newborn respiratory function. Near term rabbit kittens (30 days gestation; term ~32 days) were delivered, had lung liquid drained and either had no liquid replaced (Control, n=7) or 30 mL/kg of liquid was re-added to the airways (liquid added; LA, n=7)...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775069/the-effect-of-a-pre-hop-on-the-muscle-tendon-interaction-during-vertical-jumps
#13
Jeroen Aeles, Glen A Lichtwark, Dries Peeters, Christophe Delecluse, Ilse Jonkers, Benedicte Vanwanseele
Many movements use stretch-shortening cycles of a muscle-tendon unit (MTU) for storing and releasing elastic energy. The required stretching of medial gastrocnemius (MG) tendinous tissue during jumps, however, requires large length changes of the muscle fascicles, due to the lack of MTU length changes. This has a negative impact on the force generating capacity of the muscle fascicles. The purpose of this study was to induce a MG MTU stretch prior to shortening by adding a pre-hop to the squat jump. Eleven well-trained athletes specialized in jumping performed a pre-hop squat jump (PHSJ) and a standard squat jump (SSJ)...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775068/active-sleep-unmasks-apnea-and-delayed-arousal-in-infant-rat-pups-lacking-central-serotonin
#14
Jacob O Young, Aron M Geurts, Matthew Robert Hodges, Kevin J Cummings
Sudden Infant Death Syndrome (SIDS), occurring during sleep periods, is highly associated with abnormalities within serotonin (5-HT) neurons, including reduced 5-HT. There is evidence that future SIDS cases experience more apnea and have abnormal arousal from sleep. In rodents, a loss of 5-HT neurons is associated with apnea in early life and, in adulthood, delayed arousal. As the activity of 5-HT neurons changes with vigilance state, we hypothesized that the degree of apnea and delayed arousal displayed by rat pups specifically lacking central 5-HT varies with state...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775067/running-training-experience-attenuates-disuse-atrophy-in-fast-twitch-skeletal-muscles-of-rats
#15
Keisuke Nakamura, Ikumi Ohsawa, Ryo Masuzawa, Ryotaro Konno, Atsuya Watanabe, Fuminori Kawano
Responsiveness to physiological stimuli, such as exercise and muscular inactivation, differs in individuals. However, the mechanisms responsible for these individual differences remain poorly understood. We tested whether a prior experience of exercise training affects the responses of skeletal muscles to unloading. Young rats were assigned to perform daily running training using a treadmill for 8 weeks. After an additional 8 weeks of normal habitation, the rats were hindlimb unloaded by tail suspension for 1 week...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775066/the-interplay-between-iron-and-oxygen-homeostasis-with-a-particular-focus-on-the-heart
#16
Samira Lakhal-Littleton, Peter A Robbins
Iron is subject to tight homeostatic control in mammals. At the systemic level, iron homeostasis is controlled by the liver-derived hormone hepcidin acting on its target ferroportin in the gut, spleen and liver, which form the sites of iron uptake, recycling and storage, respectively. At the cellular level, iron homeostasis is dependent on the iron regulatory proteins IRP1/IRP2. Unique chemical properties of iron underpin its importance in biochemical reactions involving oxygen. As such, it is not surprising that there are reciprocal regulatory links between iron and oxygen homeostasis, operating both at the systemic and cellular levels...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28775065/effect-of-hypoxia-and-hyperoxia-on-exercise-performance-in-healthy-individuals-and-in-patients-with-pulmonary-hypertension-a-systematic-review
#17
Silvia Ulrich, Simon Raphael Schneider, Konrad E Bloch
Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension, exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange and, presumably, these limitations are more pronounced at altitude...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28751375/automated-full-range-pressure-volume-curves-in-mice-and-rats
#18
Annette Robichaud, Liah Fereydoonzad, Nathachit Limjunyawong, Richard Rabold, Benoit Allard, Andrea Benedetti, James G Martin, Wayne Mitzner
Pressure-volume (PV) curves constructed over the entire lung volume range can reliably detect functional changes in mouse models of lung diseases. In the present study, we constructed full-range PV curves in healthy and elastase-treated mice using either a classic manually-operated technique or an automated approach using a computer-controlled piston ventilator (flexiVent FX; SCIREQ Inc, Montreal, Qc, Canada). On the day of the experiment, subjects were anaesthetized, tracheotomized and mechanically ventilated...
July 27, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28751374/associations-between-motor-unit-action-potential-parameters-and-surface-emg-features
#19
Alessandro Del Vecchio, Francesco Negro, Francesco Felici, Dario Farina
The surface interference EMG signal provides some information on the neural drive to muscles. However, the association between neural drive to muscle and muscle activation has long been debated with controversial indications due to the unavailability of motor unit population data. In this study, we clarify the potential and limitations of interference EMG analysis to infer motor unit recruitment strategies with an experimental investigation of several concurrently active motor units and of the associated features of the surface EMG...
July 27, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28751373/heat-shock-protein-90-contributes-to-cutaneous-vasodilation-through-activating-nitric-oxide-synthase-in-young-male-adults-exercising-in-the-heat
#20
Naoto Fujii, Sarah Yan Zhang, Brendan D McNeely, Takeshi Nishiyasu, Glen P Kenny
While the mechanisms underlying the control of cutaneous vasodilation has been extensively studied, there remains a lack of understanding of the different factors that may modulate cutaneous perfusion during an exercise-induced heat stress. We evaluated the hypothesis that heat shock protein 90 (HSP90) contributes to the heat loss response of cutaneous vasodilation via the activation of nitric oxide synthase (NOS) during exercise in the heat. In eleven young males (25±5 years), cutaneous vascular conductance (CVC) was measured at four forearm skin sites that were continuously treated with 1) Lactated Ringers solution (Control), 2) NOS inhibition with 10 mM L-NAME, 3) HSP90 inhibition with 178 μM Geldanamycin, or 4) a combination of 10 mM L-NAME and 178 μM Geldanamycin...
July 27, 2017: Journal of Applied Physiology
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