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https://www.readbyqxmd.com/read/28650876/the-role-of-imaging-in-strabismus
#1
Jinali R Patel, Kammi B Gunton
PURPOSE OF REVIEW: To review the most recent literature regarding the clinical experience of imaging modalities in strabismus. RECENT FINDINGS: MRI of extraocular muscles (EOMs) has elucidated the roles of variation in compartmental contraction of EOMs and further evidence of EOM pulley heterotopy in various strabismus patterns, which may contribute to the clinical and surgical management of patients as this mode of imaging becomes more readily available. Ultrasound biomicroscopy (UBM) and anterior-segment optical coherence tomography (AS-OCT) may play a role in determining the location of EOMs which could also aid in devising a preoperative surgical plan, especially in those who have had prior strabismus surgery...
June 24, 2017: Current Opinion in Ophthalmology
https://www.readbyqxmd.com/read/28649969/physics-of-muscle-contraction
#2
Matthieu Caruel, Lev Truskinovsky
We present an overview of the recent attempts to complement the chemistry-centered microscopic models of skeletal muscles by the purely mechanical models. The force generation phenomena of interest can be divided into two classes and their mechanisms are usually modeled in dierent ways. Models in the rst class deal with fast force recovery, which does not require detachment of myosin crossbridges and is believed to be a passive process. It can be viewed as collective folding in the system of interacting bi-stable units and is modeled by equilibrium statistical mechanics and Langevin kinetics...
June 26, 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/28649196/estimation-of-time-varying-intrinsic-and-reflex-dynamic-joint-stiffness-during-movement-application-to-the-ankle-joint
#3
Diego L Guarín, Robert E Kearney
Dynamic joint stiffness determines the relation between joint position and torque, and plays a vital role in the control of posture and movement. Dynamic joint stiffness can be quantified during quasi-stationary conditions using disturbance experiments, where small position perturbations are applied to the joint and the torque response is recorded. Dynamic joint stiffness is composed of intrinsic and reflex mechanisms that act and change together, so that nonlinear, mathematical models and specialized system identification techniques are necessary to estimate their relative contributions to overall joint stiffness...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28648821/caveolae-protect-notochord-cells-against-catastrophic-mechanical-failure-during-development
#4
Ye-Wheen Lim, Harriet P Lo, Charles Ferguson, Nick Martel, Jean Giacomotto, Guillermo A Gomez, Alpha S Yap, Thomas E Hall, Robert G Parton
The embryonic notochord is a flexible structure present during development that serves as scaffold for formation of the vertebrate spine. This rod-like organ is thought to have evolved in non-vertebrate chordates to facilitate locomotion by providing a rigid but flexible midline structure against which the axial muscles can contract. This hydrostatic "skeleton" is exposed to a variety of mechanical forces during oscillation of the body. There is evidence that caveolae, submicroscopic cup-shaped plasma membrane pits, can buffer tension in cells that undergo high levels of mechanical stress...
June 14, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28647868/effects-of-high-altitude-exposure-on-supraspinal-fatigue-and-corticospinal-excitability-and-inhibition
#5
Mathieu Marillier, Pierrick J Arnal, Thibault Le Roux Mallouf, Thomas Rupp, Guillaume Y Millet, Samuel Verges
PURPOSE: While acute hypoxic exposure enhances exercise-induced central fatigue and can alter corticospinal excitability and inhibition, the effect of prolonged hypoxic exposure on these parameters remains to be clarified. We hypothesized that 5 days of altitude exposure would (i) normalize exercise-induced supraspinal fatigue during isolated muscle exercise to sea level (SL) values and (ii) increase corticospinal excitability and inhibition. METHODS: Eleven male subjects performed intermittent isometric elbow flexions at 50% of maximal voluntary contraction to task failure at SL and after 1 (D1) and 5 (D5) days at 4350 m...
June 24, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28647034/muscle-strength-and-control-characteristics-are-altered-by-peripheral-artery-disease
#6
Molly N Schieber, Ryan M Hasenkamp, Iraklis I Pipinos, Jason M Johanning, Nicholas Stergiou, Holly K DeSpiegelaere, Jung H Chien, Sara A Myers
OBJECTIVE: Peripheral artery disease (PAD), a common manifestation of atherosclerosis, is characterized by lower leg ischemia and myopathy in association with leg dysfunction. Patients with PAD have impaired gait from the first step they take with consistent defects in the movement around the ankle joint, especially in plantar flexion. Our goal was to develop muscle strength profiles to better understand the problems in motor control responsible for the walking impairment in patients with PAD...
July 2017: Journal of Vascular Surgery
https://www.readbyqxmd.com/read/28645314/neuromuscular-function-during-knee-extension-exercise-after-cold-water-immersion
#7
Hitoshi Wakabayashi, Titis Wijayanto, Yutaka Tochihara
BACKGROUND: Human adaptability to cold environment has been focused on in the physiological anthropology and related research area. Concerning the human acclimatization process in the natural climate, it is necessary to conduct a research assessing comprehensive effect of cold environment and physical activities in cold. This study investigated the effect of cold water immersion on the exercise performance and neuromuscular function during maximal and submaximal isometric knee extension...
June 23, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/28642711/weekly-time-course-of-neuro-muscular-adaptation-to-intensive-strength-training
#8
Niklas Brown, Dieter Bubeck, Daniel F B Haeufle, Johannes Weickenmeier, Ellen Kuhl, Wilfried Alt, Syn Schmitt
Detailed description of the time course of muscular adaptation is rarely found in literature. Thus, models of muscular adaptation are difficult to validate since no detailed data of adaptation are available. In this article, as an initial step toward a detailed description and analysis of muscular adaptation, we provide a case report of 8 weeks of intense strength training with two active, male participants. Muscular adaptations were analyzed on a morphological level with MRI scans of the right quadriceps muscle and the calculation of muscle volume, on a voluntary strength level by isometric voluntary contractions with doublet stimulation (interpolated twitch technique) and on a non-voluntary level by resting twitch torques...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28642129/fucoxanthin-inhibits-profibrotic-protein-expression-in-vitro-and-attenuates-bleomycin-induced-lung-fibrosis-in-vivo
#9
Sun Young Ma, Won Sun Park, Dae-Sung Lee, Grace Choi, Mi-Jin Yim, Jeong Min Lee, Won-Kyo Jung, Sae Gwang Park, Su-Kil Seo, Sung Jae Park, Il Yong Han, Yung Hyun Choi, Il-Whan Choi
Pulmonary fibrosis, a potentially fatal disease, results from acute and chronic interstitial lung diseases. Fucoxanthin (Fx), a carotenoid found in brown seaweed, shows a wide range of pharmacological activities. In this study, we investigated the antifibrotic effects of fucoxanthin and their underlying molecular mechanisms in transforming growth factor-beta1 (TGF-β1)-stimulated human pulmonary fibroblasts (HPFs). Thus, the effects of Fx on TGF-β1-induced expression of fibrotic factors, such as alpha-smooth muscle actin (α-SMA), type 1 collagen, fibronectin, and interleukin-6 (IL-6), in HPFs were investigated...
June 19, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28641171/electromyographic-analysis-of-rotator-cuff-muscles-in-patients-with-rotator-cuff-tendinopathy-a-systematic-review
#10
REVIEW
Fábio Carlos Lucas de Oliveira, Laurent Julien Bouyer, Amanda L Ager, Jean-Sébastien Roy
The shoulder is inherently an unstable joint which heavily relies on the neuromuscular activation of the rotator cuff (RC) complex for stability during movement. Currently, there is no consensus regarding how the activity of RC muscles is affected among individuals with a RC tendinopathy (RCTe). This study reviewed the evidence of studies comparing the electromyographic (EMG) activity of any RC muscle of shoulders with a symptomatic RCTe to asymptomatic shoulders. Eight databases were searched. Data from 343 participants (201 symptomatic and 209 asymptomatic shoulders) were analyzed from 10 out of 402 included studies...
August 2017: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/28640883/an-artificial-emg-generation-model-based-on-signal-dependent-noise-and-related-application-to-motion-classification
#11
Akira Furui, Hideaki Hayashi, Go Nakamura, Takaaki Chin, Toshio Tsuji
This paper proposes an artificial electromyogram (EMG) signal generation model based on signal-dependent noise, which has been ignored in existing methods, by introducing the stochastic construction of the EMG signals. In the proposed model, an EMG signal variance value is first generated from a probability distribution with a shape determined by a commanded muscle force and signal-dependent noise. Artificial EMG signals are then generated from the associated Gaussian distribution with a zero mean and the generated variance...
2017: PloS One
https://www.readbyqxmd.com/read/28640448/overview-of-the-muscle-cytoskeleton
#12
Christine A Henderson, Christopher G Gomez, Stefanie M Novak, Lei Mi-Mi, Carol C Gregorio
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments...
June 18, 2017: Comprehensive Physiology
https://www.readbyqxmd.com/read/28640447/role-of-serca-pump-in-muscle-thermogenesis-and-metabolism
#13
Muthu Periasamy, Santosh Kumar Maurya, Sanjaya Kumar Sahoo, Sushant Singh, Sanjaya Kumar Sahoo, Felipe C G Reis, Naresh Chandra Bal
In muscle cells, the sarcoplasmic reticulum (SR) not only acts as a Ca2+ store, but also regulates the contractile characteristics of the muscle. Ca2+ release from the SR is the primary mechanism for activating muscle contraction and reuptake of Ca2+ by the sarcoplasmic reticulum Ca2+ ATPase (SERCA) pump causes muscle relaxation. The SERCA pump isoforms are encoded by three genes, SERCA 1, 2, and 3, which are differentially expressed in muscle and determine SR Ca2+ dynamics by affecting the rate and amount of Ca2+ uptake, thereby affecting SR store and release of Ca2+ in muscle...
June 18, 2017: Comprehensive Physiology
https://www.readbyqxmd.com/read/28639940/genetic-specification-of-left-right-asymmetry-in-the-diaphragm-muscles-and-their-motor-innervation
#14
Camille Charoy, Sarah Dinvaut, Yohan Chaix, Laurette Morlé, Isabelle Sanyas, Muriel Bozon, Karine Kindbeiter, Bénédicte Durand, Jennifer M Skidmore, Lies De Groef, Motoaki Seki, Lieve Moons, Christiana Ruhrberg, James F Martin, Donna M Martin, Julien Falk, Valerie Castellani
The diaphragm muscle is essential for breathing in mammals. Its asymmetric elevation during contraction correlates with morphological features suggestive of inherent left-right (L/R) asymmetry. Whether this asymmetry is due to L versus R differences in the muscle or in the phrenic nerve activity is unknown. Here, we have combined the analysis of genetically modified mouse models with transcriptomic analysis to show that both the diaphragm muscle and phrenic nerves have asymmetries, which can be established independently of each other during early embryogenesis in pathway instructed by Nodal, a morphogen that also conveys asymmetry in other organs...
June 22, 2017: ELife
https://www.readbyqxmd.com/read/28639137/the-frank-starling-law-a-jigsaw-of-titin-proportions
#15
REVIEW
Vasco Sequeira, Jolanda van der Velden
The Frank-Starling Law dictates that the heart is able to match ejection to the dynamic changes occurring during cardiac filling, hence efficiently regulating isovolumetric contraction and shortening. In the last four decades, efforts have been made to identify a common fundamental basis for the Frank-Starling heart that can explain the direct relationship between muscle lengthening and its increased sensitization to Ca(2+). The term 'myofilament length-dependent activation' describes the length-dependent properties of the myofilaments, but what is(are) the underlying molecular mechanism(s) is a matter of ongoing debate...
June 21, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28638230/role-of-three-dimensional-endoanal-ultrasound-in-assessing-the-anal-sphincter-morphology-of-female-patients-with-chronic-proctalgia
#16
Ya-Hong Xue, Shu-Qing Ding, Yi-Jiang Ding, Li-Qun Pan
AIM: To assess the role of three-dimensional endoanal ultrasound (3D-EAUS) for morphological assessment of the anal sphincter of female patients with chronic proctalgia (CP). METHODS: In this unmatched case control study, 30 consecutive female patients with CP and 25 normal women (control group) were enrolled. 3D-EAUS was performed in all subjects. Thickness and length of internal anal sphincter (IAS), thickness of puborectalis muscle (PR), length of the external anal sphincter (EAS) plus PR, and puborectalis angle were measured and compared between the two groups...
June 7, 2017: World Journal of Gastroenterology: WJG
https://www.readbyqxmd.com/read/28638211/psychogenic-blepharospasm-a-diagnostic-dilemma
#17
Soumitra DAS, Roopchand Pandrantil Sreedharan, Prasanth Sudhakaran Remadevi, Cheruvallil Velayudhan Saji
Blepharospasm is an uncontrolled spasmodic contraction of the orbicularis muscles of the eye resulting in an abnormal tic or twitch of eyes. It usually lasts for seconds to minutes but in severe cases eyes may be closed for hours. It may be essentially benign or secondary due to a lesion in basal ganglia, pyramidal tract, and trauma, local pathology in the eyes or drug induced. Here we are presenting a case of psychogenic blepharospasm. A 65 year old woman presented with a history of episodic inability of opening her eyes for the past 6 months...
December 25, 2016: Shanghai Archives of Psychiatry
https://www.readbyqxmd.com/read/28637983/repeatability-of-measurements-of-surface-electromyographic-variables-during-maximum-voluntary-contraction-of-temporalis-and-masseter-muscles-in-normal-adults
#18
Yeong-Gwan Im, Sang-Ho Han, Ji-Il Park, Hae-Soon Lim, Byung-Gook Kim, Jae-Hyung Kim
This study evaluated the intraexaminer repeatability of measurements of surface electromyography (EMG) variables and functional indices of the myoelectric signals from the masseter and temporalis muscles bilaterally in 15 healthy men. The test was repeated on two different days without templates. The resting muscle activity was recorded once, and two kinds of maximum voluntary contraction (MVC) tasks were performed and recorded three times. The two MVC tasks involved clenching the teeth and biting down on two cotton rolls bilaterally with the posterior teeth...
2017: Journal of Oral Science
https://www.readbyqxmd.com/read/28637788/the-effects-of-neuromodulation-in-a-novel-obese-prone-rat-model-of-detrusor-underactivity
#19
Eric J Gonzalez, Warren M Grill
Obesity is a global epidemic associated with an increased risk for lower urinary tract dysfunction. Inefficient voiding and urinary retention may arise in late-stage obesity when the expulsive force of the detrusor smooth muscle cannot overcome outlet resistance. Detrusor underactivity (DUA) and impaired contractility may contribute to the pathogenesis of non-obstructive urinary retention. We used cystometry and electrical stimulation of peripheral nerves (pudendal and pelvic n.) to characterize and improve bladder function in urethane-anesthetized obese-prone (OP) and obese-resistant (OR) rats following diet-induced obesity (DIO)...
June 21, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28637599/isokinetic-clinical-assessment-of-rotator-cuff-strength-in-subacromial-shoulder-impingement
#20
Helen Land, Susan Gordon, Kerrianne Watt
BACKGROUND: Current conservative management of subacromial shoulder impingement (SSI) includes generic strengthening exercises, especially for internal (IR) and external (ER) shoulder rotators. However, there is no evidence that the strength or the ratio of strength between these muscle groups is different between those with SSI (cases) and an asymptomatic population (controls). OBJECTIVE: To identify if isokinetic rotator cuff strength or the ratio of strength is significantly different between cases and controls...
February 2017: Musculoskeletal Science & Practice
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