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https://www.readbyqxmd.com/read/28222581/a-comparison-of-the-physiological-demands-imposed-by-competing-in-a-half-marathon-vs-a-marathon
#1
Juan Del Coso, Juan J Salinero, Beatriz Lara, Javier Abián-Vicén, César Gallo-Salazar, Francisco Areces
BACKGROUND: While there is widespread scientific information about the physiological challenges imposed on elite endurance runners during competitions, the information regarding the amateur population is scarce. The aim of this study was to compare the physical and physiological load imposed by competing in a real half-marathon vs a marathon race. METHODS: From a larger group of participants, we selected 22 experienced runners who were matched in pairs (11 marathoners and 11 half-marathoners) for age and anthropometric data...
February 21, 2017: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/28220058/semg-sensor-using-polypyrrole-coated-nonwoven-fabric-sheet-for-practical-control-of-prosthetic-hand
#2
Yinlai Jiang, Masami Togane, Baoliang Lu, Hiroshi Yokoi
One of the greatest challenges of using a myoelectric prosthetic hand in daily life is to conveniently measure stable myoelectric signals. This study proposes a novel surface electromyography (sEMG) sensor using polypyrrole-coated nonwoven fabric sheet as electrodes (PPy electrodes) to allow people with disabilities to control prosthetic limbs. The PPy electrodes are sewn on an elastic band to guarantee close contact with the skin and thus reduce the contact electrical impedance between the electrodes and the skin...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28218619/muscular-dystrophy-meets-protein-biochemistry-the-mother-of-invention
#3
Steven D Funk, Jeffrey H Miner
Muscular dystrophies result from a defect in the linkage between the muscle fiber cytoskeleton and the basement membrane (BM). Congenital muscular dystrophy type MDC1A is caused by mutations in laminin α2 that either reduce its expression or impair its ability to polymerize within the muscle fiber BM. Defects in this BM lead to muscle fiber damage from the force of contraction. In this issue of the JCI, McKee and colleagues use a laminin polymerization-competent, designer chimeric BM protein in vivo to restore function of a polymerization-defective laminin, leading to normalized muscle structure and strength in a mouse model of MDC1A...
February 20, 2017: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/28214291/segmental-distribution-of-myosin-heavy-chain-isoforms-within-single-muscle-fibers
#4
Ming Zhang, Maree Gould
Despite many studies looking at the distribution of myosin heavy chain (MHC) isoforms across a transverse section of muscle, knowledge of MHC distribution along the longitudinal axis of a single skeletal muscle fiber has been relatively overlooked. Immunocytochemistry was performed on serial sections of rat extensor digitorum longus (EDL) muscle to identify MHC types I, IIA, IIX, IIY and IIB. Sixteen fascicles which contained a total of 362 fibers were randomly and systematically sampled from the 3 EDL muscles...
February 18, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/28213440/muscle-yap-is-a-regulator-of-neuromuscular-junction-formation-and-regeneration
#5
Kai Zhao, Chengyong Shen, Yisheng Lu, Zhihui Huang, Lei Li, Christopher D Rand, Jinxiu Pan, Xiang-Dong Sun, Zhibing Tan, Hongsheng Wang, Guanglin Xing, Yu Cao, Guoqing Hu, Jiliang Zhou, Wen-Cheng Xiong, Lin Mei
Yes-associated protein (Yap) is a major effector of the Hippo pathway that regulates cell proliferation and differentiation during development and restricts tissue growth in adult animals. However, its role in synapse formation remains poorly understood. In this study, we characterized Yap's role in the formation of neuromuscular junction (NMJ). In HSA-Yap(-/-) mice where Yap was mutated specifically in muscle cells, AChR clusters were smaller and were distributed in a broader region in the middle of muscle fibers, suggesting that muscle Yap is necessary for the size and location of AChR clusters...
February 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28211794/test-retest-reliability-of-muscle-fiber-conduction-velocity-and-fractal-dimension-of-surface-emg-during-isometric-contractions
#6
Matteo Beretta-Piccoli, Giuseppe D'Antona, Cristian Zampella, Marco Barbero, Ron Clijsen, Corrado Cescon
The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1-week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays...
February 17, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28209802/doublet-stimulation-increases-ca-2-binding-to-troponin-c-to-ensure-rapid-force-development-in-skeletal-muscle
#7
Anthony J Bakker, Tanya R Cully, Catherine D Wingate, Christopher J Barclay, Bradley S Launikonis
Fast-twitch skeletal muscle fibers are often exposed to motor neuron double discharges (≥200 Hz), which markedly increase both the rate of contraction and the magnitude of the resulting force responses. However, the mechanism responsible for these effects is poorly understood, likely because of technical limitations in previous studies. In this study, we measured cytosolic Ca(2+) during doublet activation using the low-affinity indicator Mag-Fluo-4 at high temporal resolution and modeled the effects of doublet stimulation on sarcoplasmic reticulum (SR) Ca(2+) release, binding of Ca(2+) to cytosolic buffers, and force enhancement in fast-twitch fibers...
February 16, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28209124/rna-seq-and-metabolomic-analyses-of-akt1-mediated-muscle-growth-reveals-regulation-of-regenerative-pathways-and-changes-in-the-muscle-secretome
#8
Chia-Ling Wu, Yoshinori Satomi, Kenneth Walsh
BACKGROUND: Skeletal muscle is a major regulator of systemic metabolism as it serves as the major site for glucose disposal and the main reservoir for amino acids. With aging, cachexia, starvation, and myositis, there is a preferential loss of fast glycolytic muscle fibers. We previously reported a mouse model in which a constitutively-active Akt transgene is induced to express in a subset of muscle groups leading to the hypertrophy of type IIb myofibers with an accompanying increase in strength...
February 16, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28207742/narciclasine-attenuates-diet-induced-obesity-by-promoting-oxidative-metabolism-in-skeletal-muscle
#9
Sofi G Julien, Sun-Yee Kim, Reinhard Brunmeir, Joanna R Sinnakannu, Xiaojia Ge, Hongyu Li, Wei Ma, Jadegoud Yaligar, Bhanu Prakash Kn, Sendhil S Velan, Pia V Röder, Qiongyi Zhang, Choon Kiat Sim, Jingyi Wu, Marta Garcia-Miralles, Mahmoud A Pouladi, Wei Xie, Craig McFarlane, Weiping Han, Feng Xu
Obesity develops when caloric intake exceeds metabolic needs. Promoting energy expenditure represents an attractive approach in the prevention of this fast-spreading epidemic. Here, we report a novel pharmacological strategy in which a natural compound, narciclasine (ncls), attenuates diet-induced obesity (DIO) in mice by promoting energy expenditure. Moreover, ncls promotes fat clearance from peripheral metabolic tissues, improves blood metabolic parameters in DIO mice, and protects these mice from the loss of voluntary physical activity...
February 2017: PLoS Biology
https://www.readbyqxmd.com/read/28202702/congenital-myopathy-associated-with-the-triadin-knockout-syndrome
#10
Andrew G Engel, Keeley R Redhage, David J Tester, Michael J Ackerman, Duygu Selcen
OBJECTIVE: Triadin is a component of the calcium release complex of cardiac and skeletal muscle. Our objective was to analyze the skeletal muscle phenotype of the triadin knockout syndrome. METHODS: We performed clinical evaluation, analyzed morphologic features by light and electron microscopy, and immunolocalized triadin in skeletal muscle. RESULTS: A 6-year-old boy with lifelong muscle weakness had a triadin knockout syndrome caused by compound heterozygous null mutations in triadin...
February 15, 2017: Neurology
https://www.readbyqxmd.com/read/28202686/simvastatin-pre-treatment-improves-survival-and-mitochondrial-function-in-a-three-day-fluid-resuscitated-rat-model-of-sepsis
#11
Jerome Morel, Iain Hargreaves, David Brealey, Viruna Neergheen, Janne T Backman, Sandro Lindig, Marcus Bläss, Michael Bauer, Daniel F McAuley, Mervyn Singer
Statins may offer protective effects in sepsis through anti-inflammatory, mitochondrial protection and other actions. We thus evaluated the effects of simvastatin on survival, organ and mitochondrial function, tissue and plasma ubiquinone levels and liver transcriptomics in a 3-day rat model of sepsis. Comparisons of rat plasma simvastatin and ubiquinone levels were made against levels sampled in blood from patients with acute lung injury (ALI) enrolled into a trial of statin therapy. Animals received simvastatin by gavage either pre- or post-induction of faecal peritonitis...
February 15, 2017: Clinical Science (1979-)
https://www.readbyqxmd.com/read/28196035/perivascular-stem-cells-diminish-muscle-atrophy-following-massive-rotator-cuff-tears-in-a-small-animal-model
#12
Claire D Eliasberg, Ayelet Dar, Andrew R Jensen, Iain R Murray, Winters R Hardy, Tomasz J Kowalski, Cameron A Garagozlo, Kyle M Natsuhara, Adam Z Khan, Owen J McBride, Peter I Cha, Benjamin V Kelley, Denis Evseenko, Brian T Feeley, David R McAllister, Bruno Péault, Frank A Petrigliano
BACKGROUND: Rotator cuff tears are a common cause of shoulder pain and often necessitate operative repair. Muscle atrophy, fibrosis, and fatty infiltration can develop after rotator cuff tears, which may compromise surgical outcomes. This study investigated the regenerative potential of 2 human adipose-derived progenitor cell lineages in a murine model of massive rotator cuff tears. METHODS: Ninety immunodeficient mice were used (15 groups of 6 mice). Mice were assigned to 1 of 3 surgical procedures: sham, supraspinatus and infraspinatus tendon transection (TT), or TT and denervation via suprascapular nerve transection (TT + DN)...
February 15, 2017: Journal of Bone and Joint Surgery. American Volume
https://www.readbyqxmd.com/read/28190456/mutations-in-inpp5k-encoding-a-phosphoinositide-5-phosphatase-cause-congenital-muscular-dystrophy-with-cataracts-and-mild-cognitive-impairment
#13
Manuela Wiessner, Andreas Roos, Christopher J Munn, Ranjith Viswanathan, Tamieka Whyte, Dan Cox, Benedikt Schoser, Caroline Sewry, Helen Roper, Rahul Phadke, Chiara Marini Bettolo, Rita Barresi, Richard Charlton, Carsten G Bönnemann, Osório Abath Neto, Umbertina C Reed, Edmar Zanoteli, Cristiane Araújo Martins Moreno, Birgit Ertl-Wagner, Rolf Stucka, Christian De Goede, Tamiris Borges da Silva, Denisa Hathazi, Margherita Dell'Aica, René P Zahedi, Simone Thiele, Juliane Müller, Helen Kingston, Susanna Müller, Elizabeth Curtis, Maggie C Walter, Tim M Strom, Volker Straub, Kate Bushby, Francesco Muntoni, Laura E Swan, Hanns Lochmüller, Jan Senderek
Phosphoinositides are small phospholipids that control diverse cellular downstream signaling events. Their spatial and temporal availability is tightly regulated by a set of specific lipid kinases and phosphatases. Congenital muscular dystrophies are hereditary disorders characterized by hypotonia and weakness from birth with variable eye and central nervous system involvement. In individuals exhibiting congenital muscular dystrophy, early-onset cataracts, and mild intellectual disability but normal cranial magnetic resonance imaging, we identified bi-allelic mutations in INPP5K, encoding inositol polyphosphate-5-phosphatase K...
February 8, 2017: American Journal of Human Genetics
https://www.readbyqxmd.com/read/28187528/ultrastructural-changes-in-human-masseter-muscles-after-botulinum-neurotoxin-a-injection
#14
Fushun Ma, Zhaohui Zhai, Shunwen Zhu, Shengjian Tang
INTRODUCTION: Botulinum neurotoxin A (BoNTA) has long been used as a therapeutic agent and has been widely accepted as a cosmetic agent in recent years. It can inhibit function and induce structural changes in skeletal muscle. METHODS: Specimens of fresh dissected human masseter muscle were used to observe the ultrastructural changes that occurred at 6 and 12 months following BoNTA injection. RESULTS: The findings observed were muscle fiber distortion, sarcomere shortening, mitochondrial vacuolar degeneration, glycogen accumulation, and H and M band disruption in the triad of tubules...
February 10, 2017: Muscle & Nerve
https://www.readbyqxmd.com/read/28181263/alterations-of-intrinsic-tongue-muscle-properties-with-aging
#15
Miranda J Cullins, Nadine P Connor
INTRODUCTION: Age-related decline in the intrinsic lingual musculature could contribute to swallowing disorders, yet the effects of age on these muscles is unknown. We hypothesized reduced muscle fiber size and shifts to slower MyHC fiber types with age. METHODS: Intrinsic lingual muscles were sampled from 8 young-adult (9 months) and 8 old (32 months) Fischer 344/Brown Norway rats. Fiber size and MyHC were determined by fluorescent immunohistochemistry. RESULTS: Age was associated with a reduced abundance of rapidly-contracting muscle fibers, and more slowly-contracting fibers...
February 9, 2017: Muscle & Nerve
https://www.readbyqxmd.com/read/28179228/dietary-nitrate-does-not-reduce-oxygen-cost-of-exercise-or-improve-muscle-mitochondrial-function-in-mitochondrial-myopathy-patients
#16
Miranda Nabben, Joep P J Schmitz, Jolita Ciapaite, Carlijn M P Le Clercq, Natal A van Riel, Harm R Haak, Klaas Nicolay, Irenaeus F de Coo, Hubert J M Smeets, Stephan F Praet, Luc J C van Loon, Jeanine J Prompers
Muscle weakness and exercise intolerance negatively affect the quality of life of mitochondrial myopathy patients. Short-term dietary nitrate supplementation has been shown to improve exercise performance and reduce oxygen cost of exercise in healthy humans and trained athletes. We investigated if 1 week of dietary inorganic nitrate supplementation decreases the oxygen cost of exercise and improves mitochondrial function in mitochondrial myopathy patients. Ten mitochondrial myopathy patients (40 ± 5 years, maximal whole-body oxygen uptake = 21...
February 8, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28177529/a-central-mesencephalic-reticular-formation-projection-to-medial-rectus-motoneurons-supplying-singly-and-multiply-innervated-extraocular-muscle-fibers
#17
Martin O Bohlen, Susan Warren, Paul J May
We recently demonstrated a bilateral projection to the supraoculomotor area from the central mesencephalic reticular formation (cMRF), a region implicated in horizontal gaze changes. C-group motoneurons, which supply multiply innervated fibers in the medial rectus muscle, are located within the primate supraoculomotor area, but their inputs and function are poorly understood. Here we tested whether C-group motoneurons in Macaca fascicularis monkeys receive a direct cMRF input by injecting this portion of the reticular formation with anterograde tracers in combination with injection of retrograde tracer into the medial rectus muscle...
February 8, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28177129/role-of-parp-activity-in-lung-cancer-induced-cachexia-effects-on-muscle-oxidative-stress-proteolysis-anabolic-markers-and-phenotype
#18
Alba Chacon-Cabrera, Mercè Mateu-Jimenez, Klaus Langohr, Clara Fermoselle, Elena García-Arumí, Antoni L Andreu, Jose Yelamos, Esther Barreiro
Strategies to treat cachexia are still at its infancy. Enhanced muscle protein breakdown and ubiquitin-proteasome system are common features of cachexia associated with chronic conditions including lung cancer (LC). Poly(ADP-ribose) polymerases (PARP), which play a major role in chromatin structure regulation, also underlie maintenance of muscle metabolism and body composition. We hypothesized that protein catabolism, proteolytic markers, muscle fiber phenotype, and muscle anabolism may improve in respiratory and limb muscles of LC-cachectic Parp-1-deficient (Parp-1(-/-) ) and Parp-2(-/-) mice...
February 8, 2017: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/28176871/the-earliest-molecular-response-to-stretch-of-insect-flight-muscle-as-revealed-by-fast-x-ray-diffraction-recording
#19
Hiroyuki Iwamoto
Small insects drive their flight muscle at frequencies up to 1,000 Hz. This remarkable ability owes to the mechanism of stretch activation. However, it remains unknown as to what sarcomeric component senses the stretch and triggers the following force generation. Here we show that the earliest structural change after a step stretch is reflected in the blinking of the 111 and 201 reflections, as observed in the fast X-ray diffraction recording from isolated bumblebee flight muscle fibers. The same signal has also been observed in live bumblebee...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28176462/hormonal-treatment-ffects-on-the-cross-sectional-area-of-pubococcygeus-muscle-fibers-after-denervation-and-castration-in-male-rats
#20
Miguel Lara-García, Mayvi Alvarado, Estela Cuevas, Omar Lara-Garcia, Dale R Sengelaub, Pablo Pacheco
We explore the interaction of muscle innervation and gonadal hormone action in the pubococcygeus muscle (Pcm) after castration and hormone replacement. Male Wistar rats were castrated and the Pcm was unilaterally denervated; after 2 or 6 weeks, the cross-sectional area (CSA) of Pcm fibers was assessed. Additional groups of castrated rats were used to examine the effects of hormone replacement. At 2 weeks post surgeries, rats were implanted with Silastic capsules containing either dihydrotestosterone (DHT), estradiol benzoate (EB) or both hormones, and the CSA of Pcm fibers was assessed after 4 weeks of hormone treatment...
February 8, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
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