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https://www.readbyqxmd.com/read/29655446/practical-anatomy-of-the-neuromuscular-junction-in-health-and-disease
#1
REVIEW
Hiroshi Nishimune, Kazuhiro Shigemoto
Neuromuscular junctions (NMJs) form between nerve terminals of spinal cord motor neurons and skeletal muscles, and perisynaptic Schwann cells and kranocytes cap NMJs. One muscle fiber has one NMJ, which is innervated by one motor nerve terminal. NMJs are excitatory synapses that use P/Q-type voltage-gated calcium channels to release the neurotransmitter acetylcholine. Acetylcholine receptors accumulate at the postsynaptic specialization called the end plate on the muscle fiber membrane, the sarcolemma. Proteins essential for the organization of end plates include agrin secreted from nerve terminals, Lrp4 and MuSK receptors for agrin, and Dok-7 and rapsyn cytosolic proteins in the muscle...
May 2018: Neurologic Clinics
https://www.readbyqxmd.com/read/29651539/skeletal-muscle-stem-cell-characteristics-and-myonuclei-content-in-patients-with-rheumatoid-arthritis-a-cross-sectional-study
#2
Rasmus Jentoft Boutrup, Jean Farup, Kristian Vissing, Michael Kjaer, Ulla Ramer Mikkelsen
To investigate satellite cells (SCs) and myonuclei characteristics in patients with rheumatoid arthritis (RA). Resting biopsies from m. vastus lateralis were obtained from thirteen RA patients and thirteen matched healthy controls (CON). Muscle biopsies were immunohistochemically stained and analyzed for fiber type specific content of SCs (Pax7+ ), proliferating SCs (Pax7+ /MyoD+ ) and differentiating SCs (myogenin+ ). Furthermore, we quantified fiber type specific content of myonuclei and myofiber cross-sectional area (CSA)...
April 12, 2018: Rheumatology International
https://www.readbyqxmd.com/read/29650754/reduced-non-bicarbonate-skeletal-muscle-buffering-capacity-in-mice-with-the-mini-muscle-phenotype
#3
Jarren C Kay, Jocelyn Ramirez, Erick Contreras, Theodore Garland
Muscle pH decreases during exercise, which may impair function. Endurance training typically reduces muscle buffering capacity due to changes in fiber type composition, but existing comparisons of species that vary in activity level are ambiguous. We hypothesized that High Runner (HR) lines of mice from an experiment that breeds for voluntary wheel running would have altered muscle buffering capacity as compared with their non-selected control counterparts. We also expected that six days of wheel access, as used in the selection protocol, would reduce buffering capacity, especially for HR mice...
April 12, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29625576/skeletal-cardiac-and-respiratory-muscle-function-and-histopathology-in-the-p448lneo-mouse-model-of-fkrp-deficient-muscular-dystrophy
#4
Qing Yu, Melissa Morales, Ning Li, Alexander G Fritz, Ren Ruobing, Anthony Blaeser, Ershia Francois, Qi-Long Lu, Kanneboyina Nagaraju, Christopher F Spurney
BACKGROUND: Fukutin-related protein (FKRP) mutations are the most common cause of dystroglycanopathies known to cause both limb girdle and congenital muscular dystrophy. The P448Lneo- mouse model has a knock-in mutation in the FKRP gene and develops skeletal, respiratory, and cardiac muscle disease. METHODS: We studied the natural history of the P448Lneo- mouse model over 9 months and the effects of twice weekly treadmill running. Forelimb and hindlimb grip strength (Columbus Instruments) and overall activity (Omnitech Electronics) assessed skeletal muscle function...
April 6, 2018: Skeletal Muscle
https://www.readbyqxmd.com/read/29625438/changes-in-myosin-heavy-chain-isoforms-along-the-length-of-orbital-fibers-in-rabbit-extraocular-muscle
#5
Christine A Lucas, Hannah S M Rhee, Joseph F Y Hoh
Purpose: Extraocular muscles express 10 myosin heavy chain (MyHC) isoforms that cater for a wide range of contractile speeds. We aim to characterize the variations in MyHC expression along the length of singly (SIFs) and multiply innervated fibers (MIFs) in the orbital layer of rabbit superior rectus muscle. Methods: Monospecific antibodies to nine MyHCs, including an anti-slow-tonic antibody characterized here were used to immunohistochemically map variations in MyHC distribution in serial sections along the muscle's full length...
March 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29621305/biomarkers-associated-with-low-moderate-and-high-vastus-lateralis-muscle-hypertrophy-following-12-weeks-of-resistance-training
#6
Christopher B Mobley, Cody T Haun, Paul A Roberson, Petey W Mumford, Wesley C Kephart, Matthew A Romero, Shelby C Osburn, Christopher G Vann, Kaelin C Young, Darren T Beck, Jeffrey S Martin, Christopher M Lockwood, Michael D Roberts
We sought to identify biomarkers which delineated individual hypertrophic responses to resistance training. Untrained, college-aged males engaged in full-body resistance training (3 d/wk) for 12 weeks. Body composition via dual x-ray absorptiometry (DXA), vastus lateralis (VL) thickness via ultrasound, blood, VL muscle biopsies, and three-repetition maximum (3-RM) squat strength were obtained prior to (PRE) and following (POST) 12 weeks of training. K-means cluster analysis based on VL thickness changes identified LOW [n = 17; change (mean±SD) = +0...
2018: PloS One
https://www.readbyqxmd.com/read/29615874/structural-and-molecular-properties-of-insect-type-ii-motor-axon-terminals
#7
Bettina Stocker, Christina Bochow, Christine Damrau, Thomas Mathejczyk, Heike Wolfenberg, Julien Colomb, Claudia Weber, Niraja Ramesh, Carsten Duch, Natalia M Biserova, Stephan Sigrist, Hans-Joachim Pflüger
A comparison between the axon terminals of octopaminergic efferent dorsal or ventral unpaired median neurons in either desert locusts ( Schistocerca gregaria ) or fruit flies ( Drosophila melanogaster ) across skeletal muscles reveals many similarities. In both species the octopaminergic axon forms beaded fibers where the boutons or varicosities form type II terminals in contrast to the neuromuscular junction (NMJ) or type I terminals. These type II terminals are immunopositive for both tyramine and octopamine and, in contrast to the type I terminals, which possess clear synaptic vesicles, only contain dense core vesicles...
2018: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/29609262/-multiple-factors-analysis-of-early-postpartum-pelvic-floor-muscles-injury-in-regenerated-parturients
#8
M Li, J Shi, Q P Lü, F H Wei, T Z Gai, Q Feng
Objective: To investigate the risk factors for multiparous pelvic floor muscles injury during 6-8 weeks after delivery. Method: From June 2015 to April 2017, 1917 women (1 523 primigravidas and 294 multiparas) were accepted postpartum pelvic floor function screening during 6-8 weeks after delivery in Beijing Hospital.Pelvic examination and pelvic floor muscle strength testing were carried out in these women.All the data were analyzed with multivariate logistic regression method to explore the related factors for postpartum pelvic floor muscle injury...
March 20, 2018: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/29605618/progressive-myoclonus-epilepsy-without-renal-failure-in-a-chinese-family-with-a-novel-mutation-in-scarb2-gene-and-literature-review
#9
Wo-Tu Tian, Xiao-Li Liu, Yang-Qi Xu, Xiao-Jun Huang, Hai-Yan Zhou, Ying Wang, Hui-Dong Tang, Sheng-Di Chen, Xing-Hua Luan, Li Cao
PURPOSE: To describe the clinical and genetic features of a Chinese progressive myoclonus epilepsy (PME) patient related with SCARB2 mutation without renal impairment and review 27 SCARB2-related PME patients from 11 countries. METHODS: The patient was a 27-year-old man with progressive action myoclonus, ataxia, epilepsy, dysarthria and absence of cognitive deterioration. Renal functional test was normal. Electroencephalography (EEG) showed progressively slowed background activity and sporadic generalized spike-and-wave discharges...
March 14, 2018: Seizure: the Journal of the British Epilepsy Association
https://www.readbyqxmd.com/read/29600773/source-sink-mismatch-causing-functional-conduction-block-in-re-entrant-ventricular-tachycardia
#10
REVIEW
Edward J Ciaccio, James Coromilas, Andrew L Wit, Nicholas S Peters, Hasan Garan
Ventricular tachycardia (VT) caused by a re-entrant circuit is a life-threatening arrhythmia that at present cannot always be treated adequately. A realistic model of re-entry would be helpful to accurately guide catheter ablation for interruption of the circuit. In this review, models of electrical activation wavefront propagation during onset and maintenance of re-entrant VT are discussed. In particular, the relationship between activation mapping and maps of transition in infarct border zone thickness, which results in source-sink mismatch, is considered in detail and supplemented with additional data...
January 2018: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29598837/effects-of-cochlear-synaptopathy-on-middle-ear-muscle-reflexes-in-unanesthetized-mice
#11
Michelle D Valero, Kenneth E Hancock, Stéphane F Maison, M Charles Liberman
Cochlear synaptopathy, i.e. the loss of auditory-nerve connections with cochlear hair cells, is seen in aging, noise damage, and other types of acquired sensorineural hearing loss. Because the subset of auditory-nerve fibers with high thresholds and low spontaneous rates (SRs) is disproportionately affected, audiometric thresholds are relatively insensitive to this primary neural degeneration. Although suprathreshold amplitudes of wave I of the auditory brainstem response (ABR) are attenuated in synaptopathic mice, there is not yet a robust diagnostic in humans...
March 13, 2018: Hearing Research
https://www.readbyqxmd.com/read/29593557/3-5-diiodo-l-thyronine-affects-structural-and-metabolic-features-of-skeletal-muscle-mitochondria-in-high-fat-diet-fed-rats-producing-a-co-adaptation-to-the-glycolytic-fiber-phenotype
#12
Elena Silvestri, Federica Cioffi, Rita De Matteis, Rosalba Senese, Pieter de Lange, Maria Coppola, Anna M Salzano, Andrea Scaloni, Michele Ceccarelli, Fernando Goglia, Antonia Lanni, Maria Moreno, Assunta Lombardi
Hyperlipidemic state-associated perturbations in the network of factors controlling mitochondrial functions, i. e., morphogenesis machinery and metabolic sensor proteins, produce metabolic inflexibility, insulin resistance and reduced oxidative capacity in skeletal muscle. Moreover, intramyocellular lipid (IMCL) accumulation leads to tissue damage and inflammation. The administration of the naturally occurring metabolite 3,5-diiodo-L-thyronine (T2) with thyromimetic actions to high fat diet (HFD)-fed rats exerts a systemic hypolipidemic effect, which produces a lack of IMCL accumulation, a shift toward glycolytic fibers and amelioration of insulin sensitivity in gastrocnemius muscle...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29579934/in-vitro-protein-digestion-of-pork-cuts-differ-with-muscle-type
#13
Xiaoyu Zou, Guanghong Zhou, Xiaobo Yu, Yun Bai, Chong Wang, Xinglian Xu, Chen Dai, Chunbao Li
Porcine trapezius, longissimus dorsi and biceps femoris muscles have been shown to contain different types of muscle fibers. Little is known about the differences in digestibility among cooked pork cuts. In this study, we compared the protein losses of porcine trapezius, longissimus dorsi and biceps femoris muscles under in vitro digestion conditions. Meat samples were cooked in 72°C water bath to center temperature of 70°C. Then meat samples were homogenized and incubated with pepsin alone or followed by trypsin...
April 2018: Food Research International
https://www.readbyqxmd.com/read/29579075/effects-of-pharmacologic-sclerostin-inhibition-or-testosterone-administration-on-soleus-muscle-atrophy-in-rodents-after-spinal-cord-injury
#14
Ean G Phillips, Luke A Beggs, Fan Ye, Christine F Conover, Darren T Beck, Dana M Otzel, Payal Ghosh, Anna C F Bassit, Stephen E Borst, Joshua F Yarrow
Sclerostin is a circulating osteocyte-derived glycoprotein that negatively regulates Wnt-signaling after binding the LRP5/LRP6 co-receptors. Pharmacologic sclerostin inhibition produces bone anabolic effects after spinal cord injury (SCI), however, the effects of sclerostin-antibody (Scl-Ab) on muscle morphology remain unknown. In comparison, androgen administration produces bone antiresorptive effects after SCI and some, but not all, studies have reported that testosterone treatment ameliorates skeletal muscle atrophy in this context...
2018: PloS One
https://www.readbyqxmd.com/read/29577406/quantifying-myofiber-integrity-using-diffusion-mri-and-random-permeable-barrier-modeling-in-skeletal-muscle-growth-and-duchenne-muscular-dystrophy-model-in-mice
#15
Kerryanne V Winters, Olivier Reynaud, Dmitry S Novikov, Els Fieremans, Sungheon Gene Kim
PURPOSE: To measure the microstructural changes during skeletal muscle growth and progressive pathologies using the random permeable model with diffusion MRI, and compare findings to conventional imaging modalities such as three-point Dixon and T2 imaging. METHODS: In vivo and ex vivo DTI experiments with multiple diffusion times (20-700 ms) were completed on wild-type (n = 22) and muscle-dystrophic mdx mice (n = 8) at various developmental time points. The DTI data were analyzed with the random permeable model framework that provides estimates of the unrestricted diffusion coefficient (D0 ), membrane surface-to-volume ratio (S/V), and membrane permeability (κ)...
March 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29572832/when-muscle-ca-2-channels-carry-monovalent-cations-through-gating-pores-insights-into-the-pathophysiology-of-type-1-hypokalemic-periodic-paralysis
#16
Bruno Allard, Clarisse Fuster
Patients suffering from type 1 hypokalemic periodic paralysis (HypoPP1) experience attacks of muscle paralysis associated with hypokalemia. The disease arises from missense mutations in the gene encoding the α1 subunit of the dihydropyridine receptor (DHPR), a protein complex anchored in the tubular membrane of skeletal muscle fibres which controls the release of Ca2+ from sarcoplasmic reticulum and also functions as a Ca2+ channel. The vast majority of mutations consist in the replacement of one of the outer arginines in S4 segments of the α1 subunit by neutral residues...
March 23, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29572802/hair-follicle-associated-pluripotent-hap-stem-cells-in-gelfoam-%C3%A2-histoculture-for-use-in-spinal-cord-repair
#17
Fang Liu, Robert M Hoffman
The stem cell marker, nestin, is expressed in the hair follicle, both in cells in the bulge area (BA) and the dermal papilla (DP). Nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells of both the BA and DP have been previously shown to be able to form neurons, heart muscle cells, and other non-follicle cell types. The ability of the nestin-expressing HAP stem cells from the BA and DP to repair spinal cord injury was compared. Nestin-expressing HAP stem cells from both the BA and DP grew very well on Gelfoam® ...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29570537/myocellular-responses-to-concurrent-flywheel-training-during-70-days-of-bed-rest
#18
Kevin A Murach, Kiril Minchev, Greg J Grosicki, Kaleen Lavin, Ryan K Perkins, Jeffrey W Ryder, Jessica Scott, Lori Ploutz-Snyder, Todd A Trappe, Scott Trappe
PURPOSE: This investigation evaluated myocellular responses to an integrated resistance and aerobic training program (SPRINT) during 70 days of bed rest. METHODS: Training was six days per week on a small-footprint gravity-independent flywheel resistance and aerobic device (FLY); three days of maximal flywheel supine quadriceps and calf exercises with continuous rowing separated by 4-6 hours, and three days of interval rowing. Vastus lateralis (VL) and soleus (SOL) muscle biopsies were obtained from eight healthy males (age=28±4 y, BMI=25±3 kg•m, VO2max=42±6 ml•kg•min) before and after 6° head-intrdown tilt bed rest...
March 22, 2018: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29565774/muscle-hypertrophy-following-blood-flow-restricted-low-force-isometric-electrical-stimulation-in-rat-tibialis-anterior-role-for-muscle-hypoxia
#19
Toshiaki Nakajima, Seiichiro Koide, Tomohiro Yasuda, Takaaki Hasegawa, Tatsuya Yamasoba, Syotaro Obi, Shigeru Toyoda, Fumitaka Nakamura, Teruo Inoue, David C Poole, Yutaka Kano
Low force exercise training with blood flow restriction (BFR) elicits muscle hypertrophy. We investigated the effects of microvascular hypoxia (i.e., low microvascular O2 partial pressures, PmvO2 ) during contractions on hypertrophic signaling, growth response and key muscle adaptations for increasing exercise capacity. Wistar rats were fitted with a cuff placed around the upper thigh and inflated to restrict limb blood flow. Low force isometric contractions (30 Hz) were evoked via electrical stimulation of the tibialis anterior (TA) nerve...
March 22, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29562315/the-protective-effect-of-melatonin-against-age-associated-sarcopenia-dependent-tubular-aggregates-formation-lactate-depletion-and-mitochondrial-changes
#20
Ramy K A Sayed, Marisol Fernández-Ortiz, María E Diaz-Casado, Iryna Rusanova, Ibtissem Rahim, Germaine Escames, Luis C López, Doaa M Mokhtar, Darío Acuña-Castroviejo
To gain insight into the mechanism of sarcopenia and the protective effect of melatonin, the gastrocnemius muscles of young (3-4 months), early-aged (12 months), and old-aged (24 months) wild type C57BL/6J female mice, were examined by magnetic resonance and microscopy. Locomotor activity, lactate production and nuclear apoptosis were also assessed. The results support the early onset of sarcopenia at 12 months of age, with reduction of muscle fibers' number, muscle weight/body weight ratio, lactate, and locomotor activity...
March 19, 2018: Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
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