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https://www.readbyqxmd.com/read/28188199/back-to-the-future-revisiting-the-physiological-cost-of-negative-work-as-a-team-based-activity-for-exercise-physiology-students
#1
Matthew A Kilgas, Steven J Elmer
We implemented a team-based activity in our exercise physiology teaching laboratory that was inspired from Abbott et al.'s classic 1952 Journal of Physiology paper titled "The physiological cost of negative work." Abbott et al. connected two bicycles via one chain. One person cycled forward (muscle shortening contractions, positive work) while the other resisted the reverse moving pedals (muscle lengthening contractions, negative work), and the cost of work was compared. This study was the first to link human whole body energetics with isolated muscle force-velocity characteristics...
March 1, 2017: Advances in Physiology Education
https://www.readbyqxmd.com/read/28182797/can-real-time-visual-feedback-during-gait-retraining-reduce-metabolic-demand-for-individuals-with-transtibial-amputation
#2
Elizabeth Russell Esposito, Harmony S Choi, Benjamin J Darter, Jason M Wilken
The metabolic demand of walking generally increases following lower extremity amputation. This study used real-time visual feedback to modify biomechanical factors linked to an elevated metabolic demand of walking in individuals with transtibial amputation. Eight persons with unilateral, traumatic transtibial amputation and 8 uninjured controls participated. Two separate bouts of real-time visual feedback were provided during a single session of gait retraining to reduce 1) center of mass sway and 2) thigh muscle activation magnitudes and duration...
2017: PloS One
https://www.readbyqxmd.com/read/28174436/cardiovascular-response-to-bouts-of-exercise-with-blood-flow-restriction
#3
Kestutis Bunevicius, Arturas Sujeta, Kristina Poderiene, Birute Zachariene, Viktoras Silinskas, Rimantas Minkevicius, Jonas Poderys
[Purpose] Occlusion training with low-intensity resistance exercises and blood flow restriction increases muscle cross-sectional area and strength. This form of training is used in rehabilitation; therefore, the aim of this study was to examine the effect of one occlusion training session on the cardiovascular response to bouts of exercise. [Subjects and Methods] Two groups took part: a control group without blood flow restriction and an experimental group with blood flow restriction. A single training session was used with the exercise intensity set at 40% of the one repetition maximum...
December 2016: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28168870/annotation-of-functional-impact-of-voltage-gated-sodium-channel-mutations
#4
Valérie Hinard, Aurore Britan, Mathieu Schaeffer, Monique Zahn-Zabal, Urs Thomet, Jean-Sébastien Rougier, Amos Bairoch, Hugues Abriel, Pascale Gaudet
Voltage-gated sodium channels are pore-forming transmembrane proteins that selectively allow sodium ions to flow across the plasma membrane according to the electro-chemical gradient thus mediating the rising phase of action potentials in excitable cells and playing key roles in physiological processes such as neurotransmission, skeletal muscle contraction, heart rhythm and pain sensation. Genetic variations in the nine human genes encoding these channels are known to cause a large range of diseases affecting the nervous and cardiac systems...
February 7, 2017: Human Mutation
https://www.readbyqxmd.com/read/28168695/forensic-considerations-in-cases-of-myotonic-dystrophy-at-autopsy
#5
Kimberley J Omond, Roger W Byard
Myotonic dystrophy (DM) is a chronic, slowly progressive, autosomal-dominant disorder with delayed muscle relaxation after contraction, distal skeletal muscle weakness, and atrophy. It has a reduced life expectancy due predominantly to respiratory failure or sudden cardiac death. The mortality rate is approximately 7.3 times greater than the general population with a mean age at death of 53 years. Degeneration of the cardiac conduction system causes atrioventricular block, arrhythmias, and ventricular failure...
February 7, 2017: Journal of Forensic Sciences
https://www.readbyqxmd.com/read/28143820/cardiac-electrophysiology-normal-and-ischemic-ionic-currents-and-the-ecg
#6
REVIEW
Richard E Klabunde
Basic cardiac electrophysiology is foundational to understanding normal cardiac function in terms of rate and rhythm and initiation of cardiac muscle contraction. The primary clinical tool for assessing cardiac electrical events is the electrocardiogram (ECG), which provides global and regional information on rate, rhythm, and electrical conduction as well as changes in electrical activity associated with cardiac disease, particularly ischemic heart disease. This teaching review is written at a level appropriate for first- and second-year medical students...
March 1, 2017: Advances in Physiology Education
https://www.readbyqxmd.com/read/28132643/comparative-transcriptomics-of-elasmobranchs-and-teleosts-highlight-important-processes-in-adaptive-immunity-and-regional-endothermy
#7
Nicholas J Marra, Vincent P Richards, Angela Early, Steve M Bogdanowicz, Paulina D Pavinski Bitar, Michael J Stanhope, Mahmood S Shivji
BACKGROUND: Comparative genomic and/or transcriptomic analyses involving elasmobranchs remain limited, with genome level comparisons of the elasmobranch immune system to that of higher vertebrates, non-existent. This paper reports a comparative RNA-seq analysis of heart tissue from seven species, including four elasmobranchs and three teleosts, focusing on immunity, but concomitantly seeking to identify genetic similarities shared by the two lamnid sharks and the single billfish in our study, which could be linked to convergent evolution of regional endothermy...
January 30, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28123178/clinical-roles-of-calcium-channel-blockers-in-ischemic-heart-diseases
#8
REVIEW
Daisuke Sueta, Noriaki Tabata, Seiji Hokimoto
Calcium (Ca) channel blockers (CCBs) inhibit Ca(2+) channels in the myocardium or vascular smooth muscle cells, inhibit myocardium contraction, inhibit the impulse conduction system (anti-arrhythmias) and cause vasodilation. New classifications based on subtypes of Ca channels and α1 subunits have been proposed. Moreover, CCBs have pleiotropic effects on coronary spastic angina (CSA), including variant angina, myocardial infarction (MI) and stent thrombosis (ST). Although the roles of CCBs in clinical situations remain unknown, further studies in this field are expected to broaden our understanding...
January 26, 2017: Hypertension Research: Official Journal of the Japanese Society of Hypertension
https://www.readbyqxmd.com/read/28119150/vascular-katp-channels-mitigate-severe-muscle-o2-delivery-utilization-mismatch-during-contractions-in-chronic-heart-failure-rats
#9
Clark T Holdsworth, Scott K Ferguson, Trenton D Colburn, Alexander J Fees, Jesse C Craig, Daniel M Hirai, David C Poole, Timothy I Musch
The vascular ATP-sensitive K(+) (KATP) channel is a mediator of skeletal muscle microvascular oxygenation (PO2mv) during contractions in health. We tested the hypothesis that KATP channel function is preserved in chronic heart failure (CHF) and therefore its inhibition would reduce PO2mv and exacerbate the time taken to reach the PO2mv steady-state during contractions of the spinotrapezius muscle. Moreover, we hypothesized that subsequent KATP channel activation would oppose the effects of this inhibition. Muscle PO2mv (phosphorescence quenching) was measured during 180s of 1-Hz twitch contractions (∼6V) under control, glibenclamide (GLI, KATP channel antagonist; 5mg/kg) and pinacidil (PIN, KATP channel agonist; 5mg/kg) conditions in 16 male Sprague-Dawley rats with CHF induced via myocardial infarction (coronary artery ligation, left ventricular end-diastolic pressure: 18±1mmHg)...
January 22, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28107665/a-%C3%AF-%C3%AF-conjugation-containing-soft-and-conductive-injectable-polymer-hydrogel-highly-efficiently-rebuilds-cardiac-function-after-myocardial-infarction
#10
Rui Bao, Baoyu Tan, Shuang Liang, Ning Zhang, Wei Wang, Wenguang Liu
Previous studies suggested that a stiffer hydrogel system exhibited a better performance to promote heart function after myocardial infarction (MI). However, the nature of myocardium, a tissue that alternately contracts and relaxes with electrical impulses, leads us to hypothesize that a soft and conductive hydrogel may be in favor of mechanical and electrical signals transmission to enhance heart function after MI. In this work, π-π conjugation interaction was first employed to produce a soft injectable hydrogel with conductive property...
January 12, 2017: Biomaterials
https://www.readbyqxmd.com/read/28100834/soft-robotic-sleeve-supports-heart-function
#11
Ellen T Roche, Markus A Horvath, Isaac Wamala, Ali Alazmani, Sang-Eun Song, William Whyte, Zurab Machaidze, Christopher J Payne, James C Weaver, Gregory Fishbein, Joseph Kuebler, Nikolay V Vasilyev, David J Mooney, Frank A Pigula, Conor J Walsh
There is much interest in form-fitting, low-modulus, implantable devices or soft robots that can mimic or assist in complex biological functions such as the contraction of heart muscle. We present a soft robotic sleeve that is implanted around the heart and actively compresses and twists to act as a cardiac ventricular assist device. The sleeve does not contact blood, obviating the need for anticoagulation therapy or blood thinners, and reduces complications with current ventricular assist devices, such as clotting and infection...
January 18, 2017: Science Translational Medicine
https://www.readbyqxmd.com/read/28097776/molecular-mechanisms-underlying-deoxy-adp-pi-activation-of-pre-powerstroke-myosin
#12
Sarah G Nowakowski, Michael Regnier, Valerie Daggett
Myosin activation is a viable approach to treat systolic heart failure. We previously demonstrated that striated muscle myosin is a promiscuous ATPase that can use most nucleoside triphosphates as energy substrates for contraction. When 2-deoxy ATP (dATP) is used, it acts as a myosin activator, enhancing cross-bridge binding and cycling. In vivo, we have demonstrated that elevated dATP levels increase basal cardiac function and rescues function of infarcted rodent and pig hearts. Here we investigate the molecular mechanism underlying this physiological effect...
January 18, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28090140/influence-of-warm-up-duration-and-recovery-interval-prior-to-exercise-on-anaerobic-performance
#13
M Frikha, N Chaâri, N Mezghanni, N Souissi
The purpose of the study was to determine the impact of different active warm-up (AWU) durations and the rest interval separating it from exercise on anaerobic performance. Eleven male physical education students (22.6 ± 2.52 years; 179.2 ± 4.3 cm; 82.5 ± 9.7 kg; mean ± SD) participated in a cross-over randomized study, and they all underwent the Wingate test after three AWU durations: 5 min (AWU5), 15 min (AWU15) and 20 min (AWU20), with recovery (WREC) or without a recovery interval (NREC) separating the AWU and anaerobic exercise performance...
December 2016: Biology of Sport
https://www.readbyqxmd.com/read/28077597/muscle-developmental-defects-in-heterogeneous-nuclear-ribonucleoprotein-a1-knockout-mice
#14
Ting-Yuan Liu, Yu-Chia Chen, Yuh-Jyh Jong, Huai-Jen Tsai, Chien-Chin Lee, Ya-Sian Chang, Jan-Gowth Chang, Yung-Fu Chang
Heterogeneous ribonucleoprotein A1 (hnRNP A1) is crucial for regulating alternative splicing. Its integrated function within an organism has not, however, been identified. We generated hnRNP A1 knockout mice to study the role of hnRNP A1 in vivo The knockout mice, hnRNP A1(-/-), showed embryonic lethality because of muscle developmental defects. The blood pressure and heart rate of the heterozygous mice were higher than those of the wild-type mice, indicating heart function defects. We performed mouse exon arrays to study the muscle development mechanism...
January 2017: Open Biology
https://www.readbyqxmd.com/read/28068381/impairment-of-excitation-contraction-coupling-in-right-ventricular-hypertrophied-muscle-with-fibrosis-induced-by-pulmonary-artery-banding
#15
Yoichiro Kusakari, Takashi Urashima, Daisuke Shimura, Erika Amemiya, Genki Miyasaka, Shunsuke Yokota, Yoshitaka Fujimoto, Toru Akaike, Takahiro Inoue, Susumu Minamisawa
Interstitial myocardial fibrosis is one of the factors responsible for dysfunction of the heart. However, how interstitial fibrosis affects cardiac function and excitation-contraction coupling (E-C coupling) has not yet been clarified. We developed an animal model of right ventricular (RV) hypertrophy with fibrosis by pulmonary artery (PA) banding in rats. Two, four, and six weeks after the PA-banding operation, the tension and intracellular Ca2+ concentration of RV papillary muscles were simultaneously measured (n = 33)...
2017: PloS One
https://www.readbyqxmd.com/read/28057868/glucocorticoid-receptor-alters-isovolumetric-contraction-and-restrains-cardiac-fibrosis
#16
Rachel Richardson, Emma Batchen, Adrian Thomson, Rowan Darroch, Xinlu Pan, Eva Rog-Zielinska, Wiktoria Wyrzykowska, Kathleen Scullion, Emad A S Al-Dujaili, Mary Diaz, Carmel Moran, Chris J Kenyon, Gillian A Gray, Karen Chapman
Corticosteroids directly affect the heart and vasculature and are implicated in the pathogenesis of heart failure. Attention has focussed upon the role of the mineralocorticoid receptor (MR) in mediating pro-fibrotic and other adverse effects of corticosteroids upon the heart. In contrast, the role of the glucocorticoid receptor (GR) in the heart and vasculature is less well understood. We addressed this in mice with cardiomyocyte and vascular smooth muscle deletion of GR (SMGRKO mice). Survival of SMGRKO mice to weaning was reduced compared with littermate controls...
January 5, 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28006945/neonatal-capsaicin-administration-impairs-postnatal-development-of-the-cardiac-chronotropy-and-inotropy-in-rats
#17
J Kuncová, A Jirkovská, J Švíglerová, M Marková, D Meireles, M Čedíková
The present study evaluated the impact of neonatal administration of capsaicin (neurotoxin from red hot pepper used for sensory denervation) on postnatal development of the heart rate and ventricular contractility. In the rats subjected to capsaicin administration (100 mg/kg) on postnatal days 2 and 3 and their vehicle-treated controls at the ages of 10 to 90 days, function of the sympathetic innervation of the developing heart was characterized by evaluation of chronotropic responses to metipranolol and atropine, norepinephrine concentrations in the heart, and norepinephrine release from the heart atria...
December 22, 2016: Physiological Research
https://www.readbyqxmd.com/read/28006942/propofol-induced-mitochondrial-and-contractile-dysfunction-of-the-rat-ventricular-myocardium
#18
M Grundmanová, D Jarkovská, A Süß, Z Tůma, M Marková, Z Grundman, A El-Kadi, M Čedíková, M Štengl, J Kuncová
Propofol is a short-acting hypnotic agent used in human medicine for sedation and general anesthesia. Its administration can be associated with serious cardiovascular side-effects that include decrease in arterial blood pressure and cardiac output. The aim of the present study was to evaluate propofol effects on mitochondrial respiration, myocardial contractility and electrophysiology in the same samples isolated from the heart ventricles of adult rats. Mitochondrial oxygen consumption was measured in permeabilized samples dissected from free walls of both ventricles using high-resolution respirometry...
December 22, 2016: Physiological Research
https://www.readbyqxmd.com/read/27990123/brief-rewarming-blunts-hypothermia-induced-alterations-in-sensation-motor-drive-and-cognition
#19
Marius Brazaitis, Henrikas Paulauskas, Albertas Skurvydas, Henning Budde, Laura Daniuseviciute, Nerijus Eimantas
Background: It is well known that cold exposure experienced during occupational or recreational activities may adversely affect motor, cognitive performance, and health. Most research has used prolonged passive external rewarming modalities and focused on the direct effects on the kinetics of physiological and psychological responses in hypothermic subjects. However, the brief whole body rewarming effects on physiological and psychological responses in parallel with functional consequences on cognitive and neurophysiological functions have not been investigated...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27984313/electrical-stimulation-of-artificial-heart-muscle-a-look-into-the-electrophysiological-and-genetic-implications
#20
Mohamed A Mohamed, Jose F Islas, Robert J Schwartz, Ravi K Birla
Development of tissue-engineered hearts for treatment of myocardial infarction or biological pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. In order to further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously...
December 13, 2016: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
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