Drowning in a river with an average depth of 3 ft: interpreting athletic performance gains
(Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - November 13, 2017 Category: Physiology Authors: Hsia, C. C. W. Tags: EDITORIAL FOCUS Source Type: research
Effects of acute hypoxia on human cognitive processing: a study using ERPs and SEPs
Although hypoxia has the potential to impair the cognitive function, the effects of acute hypoxia on the high-order brain function (executive and/or inhibitory processing) and somatosensory ascending processing remain unknown. We tested the hypothesis that acute hypoxia impairs both motor executive and inhibitory processing and somatosensory ascending processing. Fifteen healthy subjects performed two sessions (sessions 1 and 2), consisting of electroencephalographic event-related potentials with somatosensory Go/No-go paradigms and somatosensory-evoked potentials (SEPs) under two conditions (hypoxia and normoxia) on diffe...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Nakata, H., Miyamoto, T., Ogoh, S., Kakigi, R., Shibasaki, M. Tags: RESEARCH ARTICLE Source Type: research
Skeletal muscle signaling, metabolism, and performance during sprint exercise in severe acute hypoxia after the ingestion of antioxidants
This study showed that the ingestion of antioxidants before sprint exercise in severe acute hypoxia reduced the glycolytic rate and attenuated the increases of the AMP-to-ATP and the reduction of the NAD+-to-NADH.H+ ratios. This resulted in a modified muscle signaling response with a blunted Thr286-CaMKII but similar AMP-activated protein kinase phosphorylation responses in the sprints preceded by the ingestion of antioxidants. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Morales-Alamo, D., Guerra, B., Ponce-Gonzalez, J. G., Guadalupe-Grau, A., Santana, A., Martin-Rincon, M., Gelabert-Rebato, M., Cadefau, J. A., Cusso, R., Dorado, C., Calbet, J. A. L. Tags: RESEARCH ARTICLE Source Type: research
Remote ischemic preconditioning does not prevent acute mountain sickness after rapid ascent to 3,450 m
This study indicates that RIPC, performed immediately before passive ascent to 3,450 m, does not attenuate AMS and the magnitude of high-altitude pulmonary hypertension.
NEW & NOTEWORTHY Remote ischemic preconditioning (RIPC) has been reported to improve neurologic and pulmonary outcome following an acute ischemic or hypoxic insult, yet the effect of RIPC for protecting from high-altitude diseases remains to be determined. The present study shows that RIPC, performed immediately before passive ascent to 3,450 m, does not attenuate acute mountain sickness and the degree of high-altitude pulmonary hypertension. Therefore...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Berger, M. M., Macholz, F., Lehmann, L., Dankl, D., Hochreiter, M., Bacher, B., Bärtsch, P., Mairbäurl, H. Tags: RESEARCH ARTICLE Source Type: research
Is normobaric hypoxia an effective treatment for sustaining previously acquired altitude acclimatization?
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high-altitude (HA) acclimatization-induced improvements in ventilatory and hematologic responses, acute mountain sickness (AMS), and cognitive function during reintroduction to altitude (RA) than no treatment at all. Seventeen sea-level (SL) residents (age = 23 ± 6 yr; means ± SE) completed in the following order: 1) 4 days of SL testing; 2) 12 days of HA acclimatization at 4,300 m; 3) 12 days at SL post-HA acclimatization (Post) where each received either NH (n = 9, FIO2 = 0.122) or Sham (n = 8; FIO2 = 0.207) tre...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Beidleman, B. A., Fulco, C. S., Cadarette, B. S., Cymerman, A., Buller, M. J., Salgado, R. M., Posch, A. M., Staab, J. E., Sils, I. V., Yurkevicius, B. R., Luippold, A. J., Welles, A. P., Muza, S. R. Tags: RESEARCH ARTICLE Source Type: research
Elevated airway liquid volumes at birth: a potential cause of transient tachypnea of the newborn
Excessive liquid in airways and/or 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 their lung liquid-drained, and either had no liquid replaced (control; n = 7) or 30 ml/kg of liquid re-added to the airways [liquid added (LA); n = 7]. Kittens were mechanically ventilated in a plethysmograph. Mea...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: McGillick, E. V., Lee, K., Yamaoka, S., te Pas, A. B., Crossley, K. J., Wallace, M. J., Kitchen, M. J., Lewis, R. A., Kerr, L. T., DeKoninck, P., Dekker, J., Thio, M., McDougall, A. R. A., Hooper, S. B. Tags: RESEARCH ARTICLE Source Type: research
Effects of antenatal melatonin therapy on lung structure in growth-restricted newborn lambs
Oxidative stress arising from suboptimal placental function contributes to a multitude of pathologies in infants compromised by fetal growth restriction (FGR). FGR infants are at high risk for respiratory dysfunction after birth and poor long-term lung function. Our objective was to investigate the contribution of oxidative stress to adverse lung development and the effects of melatonin administration, a powerful antioxidant, on lung structure in FGR lambs. Placental insufficiency and FGR was surgically induced in 13 fetal sheep at ~105 days of gestation by ligation of a single umbilical artery. Maternal intravenous melato...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Polglase, G. R., Barbuto, J., Allison, B. J., Yawno, T., Sutherland, A. E., Malhotra, A., Schulze, K. E., Wallace, E. M., Jenkin, G., Ricardo, S. D., Miller, S. L. Tags: RESEARCH ARTICLE Source Type: research
Peripheral ventilation heterogeneity determines the extent of bronchoconstriction in asthma
In asthma, bronchoconstriction causes topographically heterogeneous airway narrowing, as measured by three-dimensional ventilation imaging. Computation modeling suggests that peripheral airway dysfunction is a potential determinant of acute airway narrowing measured by imaging. We hypothesized that the development of low-ventilation regions measured topographically by three-dimensional imaging after bronchoconstriction is predicted by peripheral airway function. Fourteen asthmatic subjects underwent ventilation single-photon-emission computed tomography/computed tomography scan imaging before and after methacholine challen...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Farrow, C. E., Salome, C. M., Harris, B. E., Bailey, D. L., Berend, N., King, G. G. Tags: RESEARCH ARTICLE Source Type: research
Impact of the localization of dendritic calcium persistent inward current on the input-output properties of spinal motoneuron pool: a computational study
The goal of this study is to investigate how the dendritic Ca-PIC location influences nonlinear input-output properties and depends on the type of motoneurons across the motoneuron pool. A model motoneuron pool consisting of 10 motoneurons was constructed using a recently developed two-compartment modeling approach that reflected key cell type-associated properties experimentally identified. The dendritic excitability and firing output depended systematically on both the PIC location and the motoneuron type. The PIC onset and offset in the current-voltage (I–V) relationship tended to occur at more hyperpolarized volt...
Source: Journal of Applied Physiology - November 9, 2017 Category: Physiology Authors: Kim, H. Tags: RESEARCH ARTICLE Source Type: research
Blood pressure and leg deoxygenation are exaggerated during treadmill walking in patients with peripheral artery disease
The purpose of this study was to investigate blood pressure (BP) and leg skeletal muscle oxygen saturation (Smo2) during treadmill walking in patients with peripheral artery disease (PAD) and healthy subjects. Eight PAD patients (66 ± 8 yr, 1 woman) and eight healthy subjects (65 ± 7 yr, 1 woman) walked on a treadmill at 2 mph (0.89 m/s). The incline increased by 2% every 2 min, from 0 to 15% or until maximal discomfort. BP was measured every 2 min with an auscultatory cuff. Heart rate (HR) was recorded continuously with an ECG. Smo2 in the gastrocnemius muscle was measured on each leg using near-infrared spe...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Miller, A. J., Luck, J. C., Kim, D. J.-K., Leuenberger, U. A., Proctor, D. N., Sinoway, L. I., Muller, M. D. Tags: RESEARCH ARTICLE Source Type: research
Aerobic exercise elevates markers of angiogenesis and macrophage IL-6 gene expression in the subcutaneous adipose tissue of overweight-to-obese adults
In conclusion, exercise initiates increases in factors related to angiogenic processes and may promote alterations in macrophage inflammation in SAT.
NEW & NOTEWORTHY Acute exercise in overweight/obese adults increased subcutaneous adipose tissue (SAT) mRNA expression of VEGFA, an important regulator of angiogenesis and capillary growth. In addition, subjects that regularly exercise had elevated SAT CD31 mRNA expression and elevated IL-6 mRNA in adipose tissue macrophages compared with nonexercisers. This study demonstrates that aerobic exercise may alter processes related to whole body metabolic outcomes in obesity, s...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Van Pelt, D. W., Guth, L. M., Horowitz, J. F. Tags: RESEARCH ARTICLE Source Type: research
Cardiac output by pulse contour analysis does not match the increase measured by rebreathing during human spaceflight
This study demonstrated that pulse contour analysis of finger arterial blood pressure to estimate cardiac output failed to track the 46% increase measured by a rebreathing method. These results strongly suggest that alternative methods not dependent on pulse contour analysis are required to track cardiac function in spaceflight. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Hughson, R. L., Peterson, S. D., Yee, N. J., Greaves, D. K. Tags: RESEARCH ARTICLE Source Type: research
Lower body negative pressure reduces optic nerve sheath diameter during head-down tilt
The microgravity ocular syndrome (MOS) results in significant structural and functional ophthalmic changes during 6-mo spaceflight missions consistent with an increase in cerebrospinal fluid (CSF) pressure compared with the preflight upright position. A ground-based study was performed to assess two of the major hypothesized contributors to MOS, headward fluid shifting and increased ambient CO2, on intracranial and periorbital CSF. In addition, lower body negative pressure (LBNP) was assessed as a countermeasure to headward fluid shifting. Nine healthy male subjects participated in a crossover design study with five head-d...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Marshall-Goebel, K., Terlevic, R., Gerlach, D. A., Kuehn, S., Mulder, E., Rittweger, J. Tags: RESEARCH ARTICLE Source Type: research
Sexually dimorphic skeletal muscle and cardiac dysfunction in a mouse model of limb girdle muscular dystrophy 2i
The fukutin-related protein P448L mutant mouse replicates many pathologies common to limb girdle muscular dystrophy 2i (LGMD2i) and is a potentially strong candidate for relevant drug screening studies. Because striated muscle function remains relatively uncharacterized in this mouse, we sought to identify metabolic, functional and histological metrics of exercise and cardiac performance. This was accomplished by quantifying voluntary exercise on running wheels, forced exercise on respiratory treadmills and cardiac output with echocardiography and isoproterenol stress tests. Voluntary exercise revealed few differences betw...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Maricelli, J. W., Kagel, D. R., Bishaw, Y. M., Nelson, O. L., Lin, D. C., Rodgers, B. D. Tags: RESEARCH ARTICLE Source Type: research
Feedback modulation of surrounding pressure determines the onset of negative effort dependence in a collapsible tube bench model of the pharyngeal airway
We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V; 0–5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0–5 cmH2O (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu – Pd), maximum airflow (Vmax), and chamber pressure (Pc) were measured at 0–50% longitudinal strain. NED occ...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Lambeth, C., Kolevski, B., Amis, T., Kairaitis, K. Tags: RESEARCH ARTICLE Source Type: research
