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Muscle contraction

Mehmet Cemal Kahya, Oğuz Sebik, Kemal S Türker
Painful stimulation of the hand results in an inhibitory response in the hand muscles known as the cutaneous silent period (CSP). In this study, we employed probability- and frequency-based analysis methods to examine the CSP induced by laser stimuli. Subjects were asked to contract their first dorsal interosseous muscle so that selected motor units discharged at a rate of about 8Hz. Laser pulses were delivered to the palm of the hand, and reflex responses were recorded. The stimuli generated CSP in all test subjects...
October 14, 2016: Journal of Electromyography and Kinesiology
Anna Hegsted, Forrest A Wright, SarahBeth Votra, David Pruyne
Formins are regulators of actin filament dynamics. We demonstrate here that two formins, FHOD-1 and EXC-6, are important in the nematode Caenorhabditis elegans for ovulation, during which actomyosin contractions push a maturing oocyte from the gonad arm into a distensible bag-like organ, the spermatheca. EXC-6, a homolog of the disease-associated mammalian formin INF2, is highly expressed in the spermatheca, where it localizes to cell-cell junctions and to circumferential actin filament bundles. Loss of EXC-6 does not noticeably affect the organization the actin filament bundles, and causes only a very modest increase in the population of junction-associated actin filaments...
October 22, 2016: Cytoskeleton
Kenichiro Sato, Noritoshi Arai, Aki Omori, Ayumi Hida, Akio Kimura, Sousuke Takeuchi
PURPOSE: Hyperammonaemia is frequently observed in patients who have experienced convulsive seizures. Although excessive muscle contraction is presumed to be responsible for the elevated levels of ammonia, the underlying mechanism is poorly understood. The present study aimed to identify the independent factors associated with ammonia elevation using large-scale multivariate analysis. METHODS: We conducted a cross-sectional study involving 379 adult patients who had been transported to our emergency department and treated for unprovoked convulsive seizures between August 2010 and September 2015...
October 6, 2016: Seizure: the Journal of the British Epilepsy Association
Ellen L Mintz, Juliana A Passipieri, Daniel Y Lovell, George J Christ
Despite the regenerative capacity of skeletal muscle, permanent functional and/or cosmetic deficits (e.g., volumetric muscle loss (VML) resulting from traumatic injury, disease and various congenital, genetic and acquired conditions are quite common. Tissue engineering and regenerative medicine technologies have enormous potential to provide a therapeutic solution. However, utilization of biologically relevant animal models in combination with longitudinal assessments of pertinent functional measures are critical to the development of improved regenerative therapeutics for treatment of VML-like injuries...
October 7, 2016: Journal of Visualized Experiments: JoVE
Jeffrey J Widrick, Matthew Alexander, Benjamin Sanchez, Devin Gibbs, Genri Kawahara, Alan Beggs, Louis Kunkel
Sapje zebrafish lack the protein dystrophin and are the smallest vertebrate model of Duchenne muscular dystrophy (DMD). Their small size makes them ideal for large-scale drug discovery screens. However, the extent that sapje mimic the muscle dysfunction of higher vertebrate models of DMD is unclear. We used an optical birefringence assay to differentiate affected dystrophic sapje larvae from their unaffected siblings and then studied trunk muscle contractility at 4-7 days post fertilization. Preparation cross-sectional area (CSA) was similar for affected and unaffected larvae, yet tetanic forces of affected preparations were only 30-60% of normal...
October 7, 2016: Physiological Genomics
Ikram Bezrati, Raouf Hammami, Mohamed Kacem Ben Fradj, Domenico Martone, Johnny Padulo, Moncef Feki, Anis Chaouachi, Naziha Kaabachi
Vitamin D is thought to regulate skeletal muscle function and boost physical performance. The aim of this study was to assess the relationship between vitamin D and physical performance in physically active children. This cross-sectional study included 125 children who practice football as a leisure activity. Plasma 25-hydroxyvitamin D (25-OHD) was assessed using a chemiluminescence immunoassay method. Vitamin D inadequacy was defined as 25-OHD < 20 ng/mL. Physical performance testing included measurements of muscle strength (maximal isometric contraction), jumping ability (vertical jump, standing broad jump, triple hop test), linear sprint (10 m and 20 m), and agility (9 × 4-m shuttle run)...
July 13, 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Seung-Hyun Yoon, Doo-Hyung Lee, Myung-Chul Jung, Young Uk Park, Seong-Yeon Lim
OBJECTIVE: The aim of this study was to evaluate the activity of rotator cuff (RC) muscles during activities of daily living. DESIGN: Motion analysis was conducted with 14 volunteers. Activation of RC (subscapularis, supraspinatus, and infraspinatus) was assessed using electromyography (EMG). Walking was performed with or without a shoulder immobilizer. Eating was conducted with or without the support of the elbow with the contralateral hand. Washing the hair was simulated while standing or leaning forward; washing the body was simulated while standing or holding the elbow; and washing the face was simulated using both hands while leaning forward...
November 2016: American Journal of Physical Medicine & Rehabilitation
Luca Fusi, Valentina Percario, Elisabetta Brunello, Marco Caremani, Pasquale Bianco, Joseph D Powers, Massimo Reconditi, Vincenzo Lombardi, Gabriella Piazzesi
KEY POINTS: Myosin filament mechanosensing determines the efficiency of the contraction by adapting the number of switched ON motors to the load. Accordingly, the unloaded shortening velocity (V0 ) is already set at the end of the latency relaxation (LR), ∼10 ms after the start of stimulation, when the myosin filament is still in the OFF state. Here the number of actin-attached motors per half-myosin filament (n) during V0 shortening imposed either at the end of LR or at the plateau of the isometric contraction is estimated from the relation between half-sarcomere compliance and force during the force redevelopment after the shortening...
October 20, 2016: Journal of Physiology
Markus Bastir, Daniel García-Martínez, Nicole Torres-Tamayo, Juan Alberto Sanchis-Gimeno, Paul O'Higgins, Cristina Utrilla, Isabel Torres Sánchez, Francisco García Río
The human ribcage expands and contracts during respiration as a result of the interaction between the morphology of the ribs, the costo-vertebral articulations and respiratory muscles. Variations in these factors are said to produce differences in the kinematics of the upper thorax and the lower thorax, but the extent and nature of any such differences and their functional implications have not yet been quantified. Applying geometric morphometrics we measured 402 three-dimensional (3D) landmarks and semilandmarks of 3D models built from computed tomographic scans of thoraces of 20 healthy adult subjects in maximal forced inspiration (FI) and expiration (FE)...
October 19, 2016: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Yan Xiong, Xiangfang Tang, Qingshi Meng, Hongfu Zhang
Ammonia has been considered the contaminant primarily responsible for respiratory disease in poultry. Even though it can cause tracheal lesions, its adverse effects on the trachea have not been sufficiently studied. The present study investigated tracheal changes in Arbor Acres broilers (Gallus gallus) induced by high concentration of ammonia using isobaric tag for relative and absolute quantification (iTRAQ)-based proteome analysis. In total, 3,706 proteins within false discovery rate of 1% were identified, including 119 significantly differentially expressed proteins...
October 17, 2016: Science China. Life Sciences
Riccardo Bientinesi, Cesare Mancuso, Maria Martire, Pier Francesco Bassi, Emilio Sacco, Diego Currò
Voltage-gated type 7 K(+) (KV7 or KCNQ) channels regulate the contractility of various smooth muscles. With this study, we aimed to assess the role of KV7 channels in the regulation of human detrusor contractility, as well as the gene and protein expression of KV7 channels in this tissue. For these purposes, the isolated organ technique, RT-qPCR, and Western blot were used, respectively. XE-991, a selective KV7 channel blocker, concentration-dependently contracted the human detrusor; mean EC50 and Emax of XE-991-induced concentration-response curve were 14...
October 19, 2016: Naunyn-Schmiedeberg's Archives of Pharmacology
Curtis A Fedorchuk, Matthew McCoy, Douglas F Lightstone, David A Bak, Jacque Moser, Brett Kubricht, John Packer, Dustin Walton, Jose Binongo
OBJECTIVE: This study investigates the impact of isometric contraction of anterior cervical muscles on cervical lordosis. METHODS: 29 volunteers were randomly assigned to an anterior head translation (n=15) or anterior head flexion (n=14) group. Resting neutral lateral cervical x-rays were compared to x-rays of sustained isometric contraction of the anterior cervical muscles producing anterior head translation or anterior head flexion. RESULTS: Paired sample t-tests indicate no significant difference between pre and post anterior head translation or anterior head flexion...
September 2016: Journal of Radiology Case Reports
Thomas A Masters, John Kendrick-Jones, Folma Buss
Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer...
October 19, 2016: Handbook of Experimental Pharmacology
Kenton M Sanders, Sean M Ward, Grant W Hennig
Motility patterns of the gastrointestinal tract are important for efficient processing of nutrients and waste. Peristalsis and segmentation are based on rhythmic electrical slow waves that generate the phasic contractions fundamental to gastrointestinal motility. Slow waves are generated and propagated actively by interstitial cells of Cajal (ICC), and these events conduct to smooth muscle cells to elicit excitation-contraction coupling. Extracellular electrical recording has been utilized to characterize slow-wave generation and propagation and abnormalities that might be responsible for gastrointestinal motility disorders...
October 19, 2016: Nature Reviews. Gastroenterology & Hepatology
A D Wibawa, N Verdonschot, J P K Halbertsma, J G M Burgerhof, R L Diercks, G J Verkerke
This study focused on comparing muscle activities predicted by the Musculoskeletal Modeling System with EMG from ten healthy subjects who performed normal walking, one-legged forward hopping and side jumping. Eight EMG electrodes measured the activity of eight right leg muscles. Specific thresholds per muscle were applied on the EMG prior comparison. These thresholds were determined by equalizing the duration of EMG to AMS muscle activity. Three graph variables, number of onsets, offsets and hills were used to quantify the level of agreement by using Cohen׳s kappa analysis...
October 6, 2016: Journal of Biomechanics
Josef Donnerer, Ingrid Liebmann
Allyl isothiocyanate (AITC, mustard oil, 50-200 µmol/l), depending on specific dosages, inhibited the cholinergic twitch response in the longitudinal muscle-myenteric plexus (LMMP) strip of the guinea-pig ileum. AITC also induced short-lasting contractile responses, and decreases of the basal tone of the LMMP strip at low concentrations and increases at high concentrations. Hexamethonium, a blocker of nicotinic ganglionic transmission, was able to prevent the AITC-evoked inhibitory effect, an effect that was also observed with the opioid antagonist naloxone...
October 19, 2016: Pharmacology
Zhenzhen Yan, Bin Hu, Zhigang Huang, Ling Zhong, Xiying Guo, Anxi Weng, Feng Xiao, Wenping Zeng, Yan Zhang, Jiuping Ding, Panpan Hou
Large-conductance Ca2+- and voltage-activated potassium (BK) channels are widely expressed in tissues. As a voltage and calcium sensor, BK channels play significant roles in regulating the action potential frequency, neurotransmitter release, and smooth muscle contraction. After associating with the auxiliary β2 subunit, mammalian BK(β2) channels (mouse or human Slo1/β2) exhibit enhanced activation and complete inactivation. However, how the β2 subunit modulates the Drosophila Slo1 channel remains elusive...
2016: PloS One
Cory M Smith, Terry J Housh, Nathaniel D M Jenkins, Ethan C Hill, Kristen C Cochrane, Amelia A Miramonti, Richard J Schmidt, Glen O Johnson
The purposes of the present study were to apply a unique method for the identification of the time course of changes in neuromuscular responses and to infer the motor unit activation strategies used to maintain force during a fatiguing, intermittent isometric workbout. Eleven men performed 50, 6 s intermittent isometric muscle actions of the leg extensors, each separated by 2 s of rest at 60% maximal voluntary isometric contraction (MVIC). Electromyographic (EMG) and mechanomyographic (MMG) amplitude (root mean square; RMS) and frequency (mean power frequency; MPF) were obtained from the vastus lateralis (VL) every 5 of the 50 repetitions and normalized as a percent of the initial repetition...
October 18, 2016: Physiological Measurement
Nivan Weerakkody, Trevor Allen
The impact that muscle fatigue and taping have on proprioception in an applied sporting context remains unclear. The purpose of this study was to investigate disturbances in position sense at the shoulder joint, and asses the effectiveness of adhesive tape in preventing injury and improving performance, after a bout of cricket fast bowling. Among amateur cricket players (N = 14), shoulder position sense, maximum voluntary contraction (MVC) force and bowling accuracy was assessed before and immediately after a fatiguing exercise bout of fast bowling...
October 18, 2016: Journal of Sports Sciences
Zhanna Kobalava
The burden of cardiovascular diseases (CVD) in general and heart failure (HF) in particular continues to increase worldwide. CVD are major contributors to death and morbidity and recognized as important drivers of healthcare expenditure. Chronic overactivity of the renin-angiotensin-aldosterone system (RAAS) plays a key role in human hypertension and HF pathophysiology. RAAS is fundamental in the overall regulation of cardiovascular homeostasis through the actions of hormones, which regulate vascular tone, and specifically blood pressure through vasoconstriction and renal sodium and water retention...
September 2016: Journal of Hypertension
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