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Muscle physiology

Karlien Mul, Chad Heatwole, Katy Eichinger, Nuran Dilek, William B Martens, Baziel G M van Engelen, Rabi Tawil, Jeffrey M Statland
INTRODUCTION: Electrical impedance myography (EIM) is a non-invasive technique for measuring muscle composition and a potential physiological biomarker for facioscapulohumeral muscular dystrophy (FSHD). METHODS: Thirty-two genetically confirmed and clinically affected FSHD participants underwent EIM in 7 muscles bilaterally. Correlations between EIM and baseline clinical measures were used to select EIM parameters of interest in FSHD, and EIM and clinical measures were followed for 1 year...
March 15, 2018: Muscle & Nerve
Daniel Langer, Casey E Ciavaglia, Azmy Faisal, Katherine A Webb, J Alberto Neder, Rik Gosselink, Sauwaluk Dacha, Marko Topalovic, Anna Ivanova, Denis E O'Donnell
Among patients with COPD, those with the lowest maximal inspiratory pressures experience greater breathing discomfort (dyspnea) during exercise. In such individuals, inspiratory muscle training (IMT) may be associated with improvement of dyspnea but the mechanisms for this are poorly understood. Therefore, we aimed to identify physiological mechanisms of improvement in dyspnea and exercise endurance following inspiratory muscle training (IMT) in patients with COPD and low maximal inspiratory pressure (Pi,max)...
March 15, 2018: Journal of Applied Physiology
Yiran Ao, Qin Zhao, Kai Yang, Gang Zheng, Xiaoqing Lv, Xiaoli Su
Clock genes are the core of the circadian rhythms in the human body and are important in regulating normal physiological functions. To date, research has indicated that the clock gene, period circadian clock 2 ( PER2 ), is downregulated in numerous types of cancer, and that it is associated with cancer occurrence and progression via the regulation of various downstream cell cycle genes. However, it remains unclear whether the decreased expression of PER2 influences the expression of other clock genes in cancer cells...
April 2018: Oncology Letters
Robert T Mankowski, Victor M Niemeijer, Jasper P Jansen, Lotte Spraakman, Henk J Stam, Stephan F E Praet
Purpose: It is still equivocal whether oxygen uptake recovery kinetics are limited by oxygen delivery and can be improved by supplementary oxygen. The present study aimed to investigate whether measurements of muscle and pulmonary oxygen uptake kinetics can be used to assess oxygen delivery limitations in healthy subjects. Methods: Sixteen healthy young adults performed three sub-maximal exercise tests (6 min at 40% Wmax ) under hypoxic (14%O2 ), normoxic (21%O2 ) and hyperoxic (35%O2 ) conditions on separate days in randomized order...
June 2017: Journal of Exercise Science and Fitness
Adam J Chicco, Catherine H Le, Erich Gnaiger, Hans C Dreyer, Jonathan B Muyskens, Angelo D'Alessandro, Travis Nemkov, Austin D Hocker, Jessica E Prenni, Lisa M Wolfe, Nathan M Sindt, Andrew T Lovering, Andrew W Subudhi, Robert C Roach
Metabolic responses to hypoxia play important roles in cell survival strategies and disease pathogenesis in humans.  However, the homeostatic adjustments that balance changes in energy supply and demand to maintain organismal function under chronic low oxygen conditions remain incompletely understood, making it difficult to distinguish adaptive from maladaptive responses in hypoxia-related pathologies.  We integrated metabolomic and proteomic profiling with mitochondrial respirometry and blood gas analyses to comprehensively define the physiological responses of skeletal muscle energy metabolism to 16 days of high-altitude hypoxia (5260 m) in healthy volunteers from the AltitudeOmics project...
March 14, 2018: Journal of Biological Chemistry
Seth W Holwerda, Rachel E Luehrs, Allene L Gremaud, Nealy A Wooldridge, Amy K Stroud, Jess G Fiedorowicz, Francois M Abboud, Gary L Pierce
Relative burst amplitude of muscle sympathetic nerve activity (MSNA) is an indicator of augmented sympathetic outflow and contributes to greater vasoconstrictor responses. Evidence suggests anxiety-induced augmentation of relative MSNA burst amplitude in patients with panic disorder, thus we hypothesized that acute stress would result in augmented relative MSNA burst amplitude and vasoconstriction in individuals with chronic anxiety. Eighteen participants with chronic anxiety (ANX, 8 men/10 women, 32{plus minus}2 years) and 18 healthy controls with low/no anxiety (CON, 8 men/10 women, 39{plus minus}3 years) were studied...
March 14, 2018: Journal of Neurophysiology
Katsuhito Matsuki, Daiki Kato, Masashi Takemoto, Yoshiaki Suzuki, Hisao Yamamura, Susumu Ohya, Hiroshi Takeshima, Yuji Imaizumi
Physiological functions of type 3 ryanodine receptors (RyR3) in smooth muscle (SM) tissues are not well understood, in spite of their wide expression. However, the short isoform of RyR3 is known to be a dominant negative variant (DN-RyR3), which may negatively regulate functions of both RyR2 and full length (FL)-RyR3 by forming hetero-tetramers. Here, functional roles of RyR3 in the regulation of Ca2+ signaling in mesenteric artery SM cells (MASMCs) were examined using RyR3 homozygous knockout mice (RyR3-/- )...
March 14, 2018: American Journal of Physiology. Cell Physiology
Nicole Schulz, Arne Güssow, Natali Bauer, Andreas Moritz
Magnesium is the second most abundant intracellular cation after potassium. It plays a vital role in almost every metabolic process in the body and is important for bone mineralization, muscle contraction and relaxation, and neuronal signal transduction. Because of its expanding role in intensivecare medicine, there has been a significant increase in knowledge during recent years regarding the functions of magnesium in the body, problems leading to magnesium disorders, and limitations of laboratory testing...
February 2018: Tierärztliche Praxis. Ausgabe K, Kleintiere/Heimtiere
Ifigeneia Kalampouka, Angel van Bekhoven, Bradley T Elliott
Ageing is associated with a general reduction of physiological function and a reduction of muscle mass and strength. Endocrine factors such as myostatin, activin A, growth and differentiation factor 11 (GDF-11) and their inhibitory peptides influence muscle mass in health and disease. We hypothesised that myocytes cultured in plasma from older and younger individuals would show an ageing effect, with reduced proliferation and differentiation in older environments. C2C12 myoblasts were grown as standard and stimulated with media conditioned with 5% plasma from healthy male participants that were either younger ( n = 6, 18-35 years of age) or older ( n = 6, >57 years of age)...
2018: Frontiers in Physiology
Stephen Brimijoin, Yang Gao, Liyi Geng, Vicky P Chen
Butyrylcholinesterase (BChE), a plasma enzyme that hydrolyses the neurotransmitter, acetylcholine relatively well, with far lower efficiency than acetylcholinesterase (AChE) but with the capability to degrade a broad range of bioactive esters. AChE is universally understood as essential to cholinergic neurotransmission, voluntary muscle performance, and cognition, among other roles, and its catalytic impact is essential for life. A total absence of BChE activity, whether by enzyme inhibition or simple lack of enzyme protein is not only compatible with life, but does not lead to obvious physiologic disturbance...
2018: Frontiers in Pharmacology
Val A Fajardo, John S Mikhaeil, Cameron F Leveille, A Russell Tupling, Paul J LeBlanc
BACKGROUND: An increase in phosphatidylcholine:phosphatidylethanolamine (PC:PE) and a decrease in fatty acyl chain length, monounsaturated:polyunsaturated (MUFA:PUFA) fatty acyl ratio reduces SERCA activity in liposomes and in mouse models of obesity and muscular dystrophy. We have previously shown that maximal SERCA activity is significantly reduced in mechanically overloaded (OVL) plantaris, however, whether changes in PC:PE ratio or fatty acyl composition may contribute to the alterations in maximal SERCA activity remain unknown...
March 13, 2018: Lipids in Health and Disease
F Andrea Sass, Michael Fuchs, Matthias Pumberger, Sven Geissler, Georg N Duda, Carsten Perka, Katharina Schmidt-Bleek
Soft tissue trauma of skeletal muscle is one of the most common side effects in surgery. Muscle injuries are not only caused by accident-related injuries but can also be of an iatrogenic nature as they occur during surgical interventions when the anatomical region of interest is exposed. If the extent of trauma surpasses the intrinsic regenerative capacities, signs of fatty degeneration and formation of fibrotic scar tissue can occur, and, consequentially, muscle function deteriorates or is diminished. Despite research efforts to investigate the physiological healing cascade following trauma, our understanding of the early onset of healing and how it potentially determines success or failure is still only fragmentary...
March 13, 2018: International Journal of Molecular Sciences
Liwei Xie, Amelia Yin, Anna S Nichenko, Aaron M Beedle, Jarrod A Call, Hang Yin
The remarkable regeneration capability of skeletal muscle depends on coordinated proliferation and differentiation of satellite cells. The self-renewal of satellite cells is critical for long-term maintenance of muscle regeneration potential. Hypoxia profoundly affects the proliferation, differentiation, and self-renewal of cultured myoblasts. However, the physiological relevance of hypoxia and hypoxia signaling in satellite cells in vivo remains largely unknown. Here, we report that satellite cells are in an intrinsic hypoxic state in vivo and express hypoxia-inducible factor 2A (HIF2A)...
March 13, 2018: Journal of Clinical Investigation
Alberto A Castro, Theodore Garland
We have used selective breeding with house mice to study coadaptation of morphology and physiology with the evolution of high daily levels of voluntary exercise. Here, we compared hindlimb bones and muscle masses from the 11th generation of four replicate High Runner (HR) lines of house mice bred for high levels of voluntary wheel running with four non-selected control (C) lines. Mass, length, diameter, and depth of the femur, tibia-fibula, and metatarsal bones, as well as masses of gastrocnemius and quadriceps muscles, were compared by analysis of covariance with body mass or body length as the covariate...
March 13, 2018: Journal of Morphology
Sofía Pestoni, Federico Javier Degrange, Claudia Patricia Tambussi, María Manuela Demmel Ferreira, Germán Alfredo Tirao
The cranio-mandibular complex is an important structure involved in food capture and processing. Its morphology is related to the nature of the food item. Jaw muscles enable the motion of this complex and their study is essential for functional and evolutionary analysis. The present study compares available behavioral and dietary data obtained from the literature with novel results from functional morphological analyses of the cranio-mandibular complex of the Guira cuckoo (Guira guira) to understand its relationship with the zoophagous trophic habit of this species...
March 13, 2018: Journal of Morphology
Anne-Sophie Poinsard, Iona Mathieson, Olivier Balland
OBJECTIVE: The aim of our work was to study the potential of tarsomarginal grafting technique, in canine. ANIMAL STUDIED: All dogs included in this study had tumors of the upper or lower eyelid. Furthermore, resection of the tumor necessitated excision of the eyelid margin comprising 1/4 and 2/3. PROCEDURE: Harvesting of the graft with the length of half the length of the tumor, including its free margins was performed via a full-thickness incision on the ipsilateral healthy eyelid...
March 13, 2018: Veterinary Ophthalmology
Gali Epstein Shochet, Lutz Wollin, David Shitrit
BACKGROUND AND OBJECTIVE: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. Activated fibroblasts are the key effector cells in fibrosis, producing excessive amounts of collagen and extracellular matrix (ECM) proteins. Whether the ECM conditioned by IPF fibroblasts determines the phenotype of naïve fibroblasts is difficult to explore. METHODS: IPF-derived primary fibroblasts were cultured on Matrigel and then cleared using ammonium hydroxide, creating an IPF-conditioned matrix (CM)...
March 12, 2018: Respirology: Official Journal of the Asian Pacific Society of Respirology
Kenji Kuzuhara, Kanako Katai, Tatsuya Hojo, Yoshihiko Fujisawa, Misaka Kimura, Yasuyoshi Yanagida, Yosuke Yamada, Junta Iguchi
Well-controlled seasonal distribution of training intensity appears to be an important variable for endurance athletes' success as competitors and/or for avoidance of overtraining. The aim of this study was to examine the interrelationships of training distribution, body composition, energy intake/expenditure, and rowing ergometer performance throughout the 2012-2013 season. In the present study of 15 collegiate male rowers, most of whom started rowing during their time at the university, we divided the 2012-2013 season (total 37 weeks) into 3 phases (off-season, December to mid-March, 16 weeks; pre-season, late March to April, 5 weeks; and in-season, May to August, 16 weeks) and analyzed the transition of 2000-m rowing ergometer time, training intensity/volume, body composition (body weight and body fat) and energy intake/expenditure in each phase...
March 6, 2018: Journal of Strength and Conditioning Research
Michela Lizier, Alessandra Castelli, Cristina Montagna, Franco Lucchini, Paolo Vezzoni, Francesca Faggioli
There is wide agreement that cell fusion is a physiological process in cells in mammalian bone, muscle and placenta. In other organs, such as the cerebellum, cell fusion is controversial. The liver contains a considerable number of polyploid cells: They are commonly believed to originate by genome endoreplication, although the contribution of cell fusion to polyploidization has not been excluded. Here, we address the topic of cell fusion in the liver from a historical point of view. We discuss experimental evidence clearly supporting the hypothesis that cell fusion occurs in the liver, specifically when bone marrow cells were injected into mice and shown to rescue genetic hepatic degenerative defects...
February 27, 2018: World Journal of Hepatology
Rafael Barona-de-Guzmán, Claudio Krstulovic-Roa, Elena Donderis-Malea, Luz Barona-Lleó
INTRODUCTION AND OBJECTIVES: The emotional evaluation of the causes of vertigo is made using the clinical records and several subjective questionnaires. The aim of the present study is to evaluate the emotional response objectively, in normal subjects, during an induced vertigo crisis. MATERIAL AND METHOD: A caloric vestibular test with cold water was performed on 30 healthy subjects. The following physiological parameters were monitored during the 60seconds prior to and the 60seconds after the stimulation: Skin Conductivity, Peripheral Pulse Volume, Body Temperature, Muscle Contraction, Heart Rate, and Respiratory Rate...
March 8, 2018: Acta Otorrinolaringológica Española
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