The effects of physical exercise on nonmotor symptoms and on neuroimmune RAGE network in experimental parkinsonism
This study newly shows that physical exercise (PE) corrects nonmotor symptoms of the intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of experimental parkinsonism. Additionally, we show that suppression of neuroimmune receptor for advanced glycation end products (RAGE) network occurs in frontal cortex on chemical (MPTP) and physical (PE) interventions. Finally, PE normalizes frontal cortical RAGE transcriptomics and upregulates the neuroprotective DJ-1 gene in the intranasal MPTP model of experimental parkinsonism. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - July 18, 2017 Category: Physiology Authors: Viana, S. D., Pita, I. R., Lemos, C., Rial, D., Couceiro, P., Rodrigues-Santos, P., Caramelo, F., Carvalho, F., Ali, S. F., Prediger, R. D., Fontes Ribeiro, C. A., Pereira, F. C. Tags: RESEARCH ARTICLE Source Type: research
Mild aerobic exercise blocks elastin fiber fragmentation and aortic dilatation in a mouse model of Marfan syndrome associated aortic aneurysm
In this study, we investigated the effects of voluntary (cage-wheel) or forced (treadmill) aerobic exercise at different intensities on aortic function and structure in a mouse model of Marfan syndrome. Four-week-old Marfan and wild-type mice were subjected to voluntary and forced exercise regimens or sedentary lifestyle for 5 mo. Thoracic aortic tissue was isolated and subjected to structural and functional studies. Our data showed that exercise improved aortic wall structure and function in Marfan mice and that the beneficial effect was biphasic, with an optimum at low intensity exercise (55–65% Vo2max) and taperin...
Source: Journal of Applied Physiology - July 18, 2017 Category: Physiology Authors: Gibson, C., Nielsen, C., Alex, R., Cooper, K., Farney, M., Gaufin, D., Cui, J. Z., van Breemen, C., Broderick, T. L., Vallejo-Elias, J., Esfandiarei, M. Tags: RESEARCH ARTICLE Source Type: research
Measurement of the distribution of ventilation-perfusion ratios in the human lung with proton MRI: comparison with the multiple inert-gas elimination technique
We report a comparison of a new proton MRI technique to measure regional VA/Q ratio against the multiple inert gas elimination technique (MIGET). The study reports good relationships between measures of heterogeneity derived from MIGET and those derived from MRI. Although currently limited to a single slice acquisition, these data suggest that single sagittal slice measures of VA/Q ratio provide an adequate means to assess heterogeneity in the normal lung. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - July 18, 2017 Category: Physiology Authors: Sa, R. C., Henderson, A. C., Simonson, T., Arai, T. J., Wagner, H., Theilmann, R. J., Wagner, P. D., Prisk, G. K., Hopkins, S. R. Tags: RESEARCH ARTICLE Source Type: research
Sex differences in sympathetic vasoconstrictor responsiveness and sympatholysis
Sex differences in the neurovascular control of blood pressure and vascular resistance have been reported. However, the mechanisms underlying the modulatory influence of sex have not been fully elucidated. Nitric oxide (NO) has been shown to inhibit sympathetic vasoconstriction in resting and contracting skeletal muscle, and estrogen modulates NO synthase (NOS) expression and NO bioavailability. Therefore NO-mediated inhibition of sympathetic vasoconstriction may be enhanced in females. Thus the purpose of the present study was to investigate the hypothesis that sympathetic vasoconstrictor responsiveness would be blunted a...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Just, T. P., DeLorey, D. S. Tags: RESEARCH ARTICLE Source Type: research
Raising the pressure: Hemodynamic effects of splanchnic nerve stimulation
We present the first analysis into the hemodynamic changes with splanchnic nerve stimulation and explore potential mechanisms of the hyperdynamic state. Our analysis presents the first human report of splanchnic nerve stimulation to induce hypertension and volume redistribution, introducing the splanchnic nerves as a key component of cardiovascular regulation.
NEW & NOTEWORTHY Our case series provides the first detailed description of human hemodynamic effects with splanchnic nerve stimulation. Splanchnic nerve stimulation results in profound hemodynamic alteration with rapid onset of hypertension and blood mobilizatio...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Fudim, M., Yalamuri, S., Herbert, J. T., Liu, P. R., Patel, M. R., Sandler, A. Tags: RESEARCH ARTICLE Source Type: research
Assessment of tongue mechanical properties using different contraction tasks
In conclusion, the tongue is more prone to fatigue during the elevation task and in patients with moderate OSA. Obesity appeared to prevent alteration of tongue mechanical properties in patients with OSA. Baseline strength stability and endurance were related, illustrating the role of central neuromuscular output in tongue resistance to fatigue.
NEW & NOTEWORTHY To our knowledge, this is the first study to assess and compare tongue function using both elevation and protrusion tasks with repetitive isometric fatiguing contractions in subjects with different OSA status. Tongue mechanical performance seemed to differ betw...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Li, W.-Y., Gakwaya, S., Saey, D., Series, F. Tags: RESEARCH ARTICLE Source Type: research
Sympathetic nervous system activation reduces contraction-induced rapid vasodilation in the leg of humans independent of age
We examined whether the age-related reduction in contraction-induced vasodilation in the leg is also due to a sympathetic vasoconstrictive mechanism. Thirteen young (24 ± 1 yr) and twelve older adults (67 ± 1 yr) performed single-leg knee extension at 20 and 40% of work-rate maximum (WRmax) during control and cold-pressor test (CPT) conditions. Femoral artery diameter and blood velocity were measured using Doppler ultrasound. Vascular conductance (VC; ml·min–1·mmHg–1) was calculated using blood flow (ml/min) and mean arterial pressure (mmHg). Peak (VC from baseline) and total VC were...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Hughes, W. E., Kruse, N. T., Casey, D. P. Tags: RESEARCH ARTICLE Source Type: research
Muscle length-dependent contribution of motoneuron Cav1.3 channels to force production in model slow motor unit
Persistent inward current (PIC)-generating Cav1.3 channels in spinal motoneuron dendrites are thought to be actively recruited during normal behaviors. However, whether and how the activation of PIC channels influences force output of motor unit remains elusive. Here, building a physiologically realistic model of slow motor unit I demonstrated that force production induced by the PIC activation is much smaller for short than lengthened muscles during the regular firing of the motoneuron that transitions from the quiescent state by either a brief current pulse at the soma or a brief synaptic excitation at the dendrites. By ...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Kim, H. Tags: RESEARCH ARTICLE Source Type: research
Evidence for age-dependent air-space enlargement contributing to loss of lung tissue elastic recoil pressure and increased shear modulus in older age
In this study, we use a structure-based mechanics analysis to elucidate the contributions of age-related air-space enlargement and redistribution of elastin and collagen to loss of lung elastic recoil pressure and increase in tissue elastic moduli. Our results show that age-related geometric changes can result in reduction of elastic recoil pressure and increase in shear and bulk moduli, which is consistent with published experimental data. All elastic moduli were sensitive to the distribution of stiffness (representing elastic fiber density) in the alveolar wall, with homogenous stiffness near the duct and through the sep...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Subramaniam, K., Kumar, H., Tawhai, M. H. Tags: RESEARCH ARTICLE Source Type: research
Effect of acute physiological free fatty acid elevation in the context of hyperinsulinemia on fiber type-specific IMCL accumulation
It is well described that increasing free fatty acids (FFAs) to high physiological levels reduces insulin sensitivity. In sedentary humans, intramyocellular lipid (IMCL) is inversely related to insulin sensitivity. Since muscle fiber composition affects muscle metabolism, whether FFAs induce IMCL accumulation in a fiber type-specific manner remains unknown. We hypothesized that in the setting of acute FFA elevation by lipid infusion within the context of a hyperinsulinemic-euglycemic clamp, IMCL will preferentially accumulate in type 1 fibers. Normal-weight participants (n = 57, mean ± SE: age 24 ± 0.6 yr, BM...
Source: Journal of Applied Physiology - July 6, 2017 Category: Physiology Authors: Chow, L. S., Mashek, D. G., Wang, Q., Shepherd, S. O., Goodpaster, B. H., Dube, J. J. Tags: RESEARCH ARTICLE Source Type: research
Increased cerebral blood volume pulsatility during head-down tilt with elevated carbon dioxide: the SPACECOT Study
Astronauts aboard the International Space Station (ISS) have exhibited hyperopic shifts, posterior eye globe flattening, dilated optic nerve sheaths, and even optic disk swelling from spaceflight. Elevated intracranial pressure (ICP) consequent to cephalad fluid shifts is commonly hypothesized as contributing to these ocular changes. Head-down tilt (HDT) is frequently utilized as an Earth-based analog to study similar fluid shifts. Sealed environments like the ISS also exhibit elevated CO2, a potent arteriolar vasodilator that could further affect cerebral blood volume (CBV) and cerebral blood flow, intracranial compliance...
Source: Journal of Applied Physiology - July 1, 2017 Category: Physiology Authors: Strangman, G. E., Zhang, Q., Marshall-Goebel, K., Mulder, E., Stevens, B., Clark, J. B., Bershad, E. M. Tags: RESEARCH ARTICLE Source Type: research
Low-frequency blood pressure oscillations and inotrope treatment failure in premature infants
In this study, hypotensive infants who require inotropes have decreased low-frequency variability at baseline compared with normotensive infants, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure.
NEW & NOTEWORTHY In this study, we examine patterns of low-frequency oscillations in blood pressure variability across regulatory components of vascular tone in normotensive and hypotensive infants exposed to inotropic medications. We found that hyp...
Source: Journal of Applied Physiology - July 1, 2017 Category: Physiology Authors: Vesoulis, Z. A., Hao, J., McPherson, C., El Ters, N. M., Mathur, A. M. Tags: RESEARCH ARTICLE Source Type: research
Impaired popliteal artery flow-mediated dilation caused by reduced daily physical activity is prevented by increased shear stress
We recently showed that 5 days of reduced daily physical activity impair popliteal artery, but not brachial artery, flow-mediated dilation (FMD). However, the mechanisms by which physical inactivity causes leg vascular dysfunction are unclear. We reason that a reduction in leg blood flow-induced shear stress is a primary underlying mechanism by which reduced daily physical activity impairs popliteal artery FMD. Thus the purpose of this study was to determine whether increased leg blood flow and shear stress during inactivity prevent the reduction in popliteal artery FMD. Bilateral popliteal artery FMD measures were perform...
Source: Journal of Applied Physiology - July 1, 2017 Category: Physiology Authors: Teixeira, A. L., Padilla, J., Vianna, L. C. Tags: RESEARCH ARTICLE Source Type: research
Prosthetic model, but not stiffness or height, affects the metabolic cost of running for athletes with unilateral transtibial amputations
Running-specific prostheses enable athletes with lower limb amputations to run by emulating the spring-like function of biological legs. Current prosthetic stiffness and height recommendations aim to mitigate kinematic asymmetries for athletes with unilateral transtibial amputations. However, it is unclear how different prosthetic configurations influence the biomechanics and metabolic cost of running. Consequently, we investigated how prosthetic model, stiffness, and height affect the biomechanics and metabolic cost of running. Ten athletes with unilateral transtibial amputations each performed 15 running trials at 2.5 or...
Source: Journal of Applied Physiology - July 1, 2017 Category: Physiology Authors: Beck, O. N., Taboga, P., Grabowski, A. M. Tags: RESEARCH ARTICLE Source Type: research
Optical clearing: impact of optical and dielectric properties of clearing solutions on pulmonary tissue mechanics
Optical clearing allows tissue visualization under preservation of organ integrity. Optical clearing of organs with a physiological change in three-dimensional geometry (such as the lung) would additionally allow visualization of macroscopic and microscopic tissue geometry. A prerequisite, however, is the preservation of the native tissue mechanics of the optically cleared lung tissue. We investigated the impact of optical and dielectric properties of clearing solutions on biomechanics and clearing potency in porcine tissue strips of healthy lungs. After fixation, bleaching, and rehydration, four methods of optical clearin...
Source: Journal of Applied Physiology - July 1, 2017 Category: Physiology Authors: Schwenninger, D., Priebe, H.-J., Schneider, M., Runck, H., Guttmann, J. Tags: RESEARCH ARTICLE Source Type: research
