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https://www.readbyqxmd.com/read/28445763/myosin-rod-hypophosphorylation-and-cb-kinetics-in-papillary-muscles-from-a-tnc-a8v-ki-mouse-model
#1
Masataka Kawai, Jamie R Johnston, Tarek Karam, Li Wang, Rakesh K Singh, Jose R Pinto
The cardiac troponin C (TnC)-A8V mutation is associated with hypertrophic and restrictive cardiomyopathy (HCM and RCM) in human and mice. The residue affected lies in the N-helix, a region known to affect Ca(2+)-binding affinity to the N-terminal domain. Here we report on the functional effects of this mutation in skinned papillary muscle fibers from homozygous knock-in TnC-A8V mice. Muscle fibers from left ventricle were activated at 25°C under the ionic conditions of working cardiomyocytes. The pCa-tension relationship showed a 3× increase in Ca(2+)-sensitivity and a decrease (0...
April 25, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28436394/sarcomere-dysfunction-in-nemaline-myopathy
#2
Josine M de Winter, Coen A C Ottenheijm
Nemaline myopathy (NM) is among the most common non-dystrophic congenital myopathies (incidence 1:50.000). Hallmark features of NM are skeletal muscle weakness and the presence of nemaline bodies in the muscle fiber. The clinical phenotype of NM patients is quite diverse, ranging from neonatal death to normal lifespan with almost normal motor function. As the respiratory muscles are involved as well, severely affected patients are ventilator-dependent. The mechanisms underlying muscle weakness in NM are currently poorly understood...
April 19, 2017: Journal of Neuromuscular Diseases
https://www.readbyqxmd.com/read/28436080/genotype-specific-pathogenic-effects-in-human-dilated-cardiomyopathy
#3
Ilse Ae Bollen, Maike Schuldt, Magdalena Harakalova, Aryan Vink, Folkert W Asselbergs, Jose R Pinto, Martina Krüger, Diederik Wd Kuster, Jolanda van der Velden
BACKGROUND: Dilated cardiomyopathy (DCM) can be caused by mutations in sarcomeric and non-sarcomeric genes. In this study we defined the pathogenic effects of three DCM causing mutations: the sarcomeric mutations in genes encoding cardiac troponin I (TNNI3p.98truncation ) and cardiac troponin T (TNNT2p.K217deletion ; also known as the K210del) and the non-sarcomeric gene mutation encoding lamin A/C (LMNAp.R331Q ). METHODS: We assessed sarcomeric protein expression and phosphorylation and contractile behaviour in single membrane-permeabilized cardiomyocytes in human left ventricular heart tissue...
April 24, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28433388/magnetic-resonance-and-diffusion-tensor-imaging-analyses-indicate-heterogeneous-strains-along-human-medial-gastrocnemius-fascicles-caused-by-submaximal-plantar-flexion-activity
#4
Agah Karakuzu, Uluç Pamuk, Cengizhan Ozturk, Burak Acar, Can A Yucesoy
Sarcomere length changes are central to force production and excursion of skeletal muscle. Previous modeling indicates non-uniformity of that if mechanical interaction of muscle with its surrounding muscular and connective tissues is taken into account. Hence, quantifying length changes along the fascicles of activated human muscle in vivo is crucial, but this is lacking due to technical complexities. Combining magnetic resonance imaging deformation analyses and diffusion tensor imaging tractography, the aim was to test the hypothesis that submaximal plantar flexion activity at 15% MVC causes heterogeneous length changes along the fascicles of human medial gastrocnemius (GM) muscle...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28428253/twitchin-kinase-inhibits-muscle-activity
#5
Yohei Matsunaga, Hyundoo Hwang, Barbara Franke, Rhys Williams, McKenna Penley, Hiroshi Qadota, Hong Yi, Levi T Morran, Hang Lu, Olga Mayans, Guy M Benian
Muscle sarcomeres contain giant polypeptides composed of multiple immunoglobulin and fibronectin domains and one or two protein kinase domains. Although binding partners for a number of this family's kinase domains have been identified, the catalytic necessity of these kinase domains remains unknown. In addition, various members of this kinase family are suspected pseudokinases with no, or little, activity. Here, we address catalytic necessity for the first time using the prototypic invertebrate representative twitchin (UNC-22) from C...
April 20, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28428008/force-development-and-intracellular-ca-2-in-intact-cardiac-muscles-from-gravin-mutant-mice
#6
Zhitao Li, Sonal Singh, Santosh V Suryavanshi, Wengang Ding, Xiaoxu Shen, Cori S Wijaya, Wei Dong Gao, Bradley K McConnell
Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β2-adrenergic receptor (β2-AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β2-AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca(2+) transient ([Ca(2+)]i) were measured...
April 17, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28423017/auxotonic-to-isometric-contraction-transitioning-in-a-beating-heart-causes-myosin-step-size-to-down-shift
#7
Thomas P Burghardt, Xiaojing Sun, Yihua Wang, Katalin Ajtai
Myosin motors in cardiac ventriculum convert ATP free energy to the work of moving blood volume under pressure. The actin bound motor cyclically rotates its lever-arm/light-chain complex linking motor generated torque to the myosin filament backbone and translating actin against resisting force. Previous research showed that the unloaded in vitro motor is described with high precision by single molecule mechanical characteristics including unitary step-sizes of approximately 3, 5, and 8 nm and their relative step-frequencies of approximately 13, 50, and 37%...
2017: PloS One
https://www.readbyqxmd.com/read/28421035/antiepileptic-drugs-impair-shortening-of-isolated-cardiomyocytes
#8
Johanna Hulbert, Christian E Elger, Rainer Meyer, Rainer Surges
BACKGROUND: Most antiepileptic drugs (AEDs) inhibit seizure generation by acting on voltage-dependent ion channels. Voltage-dependent sodium and calcium channels are commonly expressed in brain and heart, suggesting that AEDs may have considerable cardiodepressive effects, thereby facilitating sudden cardiac death as a potential cause of sudden unexpected death in epilepsy. Here, we investigated the effects of carbamazepine (CBZ), lamotrigine (LTG), and levetiracetam (LEV) alone and in combination on the shortening properties of isolated ventricular cardiomyocytes of wild-type mice...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28420666/prevalence-and-clinical-implication-of-double-mutations-in-hypertrophic-cardiomyopathy-revisiting-the-gene-dose-effect
#9
Dana Fourey, Melanie Care, Katherine A Siminovitch, Adaya Weissler-Snir, Waseem Hindieh, Raymond H Chan, Michael H Gollob, Harry Rakowski, Arnon Adler
BACKGROUND: Available data suggests that double mutations in patients with hypertrophic cardiomyopathy are not rare and are associated with a more severe phenotype. Most of this data, however, is based on noncontemporary variant classification. METHODS AND RESULTS: Clinical data of all hypertrophic cardiomyopathy patients with 2 rare genetic variants were retrospectively reviewed and compared with a group of patients with a single disease-causing variant. Furthermore, a literature search was performed for all studies with information on prevalence and outcome of patients with double mutations...
April 2017: Circulation. Cardiovascular Genetics
https://www.readbyqxmd.com/read/28416588/association-between-mutation-status-and-left-ventricular-reverse-remodelling-in-dilated-cardiomyopathy
#10
Matteo Dal Ferro, Davide Stolfo, Alessandro Altinier, Marta Gigli, Martina Perrieri, Federica Ramani, Giulia Barbati, Alberto Pivetta, Francesca Brun, Lorenzo Monserrat, Mauro Giacca, Luisa Mestroni, Marco Merlo, Gianfranco Sinagra
OBJECTIVE: To explore the genetic landscape of a well selected dilated cardiomyopathy (DCM) cohort, assessing the possible relation between different genotypes and left ventricular reverse remodelling (LVRR). METHODS: A cohort of 152 patients with DCM from the Heart Muscle Disease Registry of Trieste has been studied by next-generation sequencing (NGS). Patients were grouped into different 'gene-clusters' with functionally homogeneous genetic backgrounds. LVRR was defined by left ventricular ejection fraction normalisation or increase ≥10% associated with normalisation in indexed left ventricular end-diastolic diameter or relative decrease ≥10% at 24 months follow-up...
April 17, 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28416349/cytoplasmic-body-pathology-in-severe-acta1-related-myopathy-in-the-absence-of-typical-nemaline-rods
#11
Sandra Donkervoort, Sophelia H S Chan, Leslie H Hayes, Nathaniel Bradley, David Nguyen, Meganne E Leach, Payam Mohassel, Ying Hu, Mathula Thangarajh, Diana Bharucha-Goebel, Amanda Kan, Ronnie S L Ho, Christine A Reyes, Jessica Nance, Steven A Moore, A Reghan Foley, Carsten G Bönnemann
Mutations in ACTA1 cause a group of myopathies with expanding clinical and histopathological heterogeneity. We describe three patients with severe ACTA1-related myopathy who have muscle fiber cytoplasmic bodies but no classic nemaline rods. Patient 1 is a five-year-old boy who presented at birth with severe weakness and respiratory failure, requiring mechanical ventilation. Whole exome sequencing identified a heterozygous c.282C>A (p.Asn94Lys) ACTA1 mutation. Patients 2 and 3 were twin boys with hypotonia, severe weakness, and respiratory insufficiency at birth requiring mechanical ventilation...
March 2, 2017: Neuromuscular Disorders: NMD
https://www.readbyqxmd.com/read/28413576/timing-and-targeting-of-treatment-in-left-ventricular-hypertrophy
#12
Deokhwa Nam, Erin L Reineke
In most clinical cases, left ventricular hypertrophy (LVH) occurs over time from persistent cardiac stress. At the molecular level, this results in both transient and long-term changes to metabolic, sarcomeric, ion handling, and stress signaling pathways. Although this is initially an adaptive change, the mechanisms underlying LVH eventually lead to maladaptive changes including fibrosis, decreased cardiac function, and failure. Understanding the regulators of long-term changes, which are largely driven by transcriptional remodeling, is a crucial step in identifying novel therapeutic targets for preventing the downstream negative effects of LVH and treatments that could reverse or prevent it...
January 2017: Methodist DeBakey Cardiovascular Journal
https://www.readbyqxmd.com/read/28410273/up-regulation-of-intracellular-calcium-handling-underlies-the-recovery-of-endotoxemic-cardiomyopathy-in-mice
#13
Justin C Morse, Joanne Huang, Natasha Khona, Edward J Miller, Deborah A Siwik, Wilson S Colucci, Ion A Hobai
BACKGROUND: In surviving patients, sepsis-induced cardiomyopathy is spontaneously reversible. In the absence of any experimental data, it is generally thought that cardiac recovery in sepsis simply follows the remission of systemic inflammation. Here the authors aimed to identify the myocardial mechanisms underlying cardiac recovery in endotoxemic mice. METHODS: Male C57BL/6 mice were challenged with lipopolysaccharide (7 μg/g, intraperitoneally) and followed for 12 days...
April 14, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28409012/enhancing-the-diagnosis-of-fabry-disease-in-cardiology-with-a-targeted-information-a-before-after-control-impact-study
#14
Anne-Louise Savary, Remy Morello, Carole Brasse-Lagnel, Paul Milliez, Soumeya Bekri, Fabien Labombarda
BACKGROUND: Cardiac complications in Fabry disease are frequent and dominated by a high frequency of left ventricular hypertrophy; therefore, cardiologists may have an essential role in screening for this disease. Providing cardiologists with targeted information on Fabry disease would be valuable and could reduce both diagnostic and therapeutic delays. The aim of this study was to evaluate the efficiency of such strategy for Fabry screening. METHODS: We conducted a before-after control-impact study by comparing observations made before and after targeted information on Fabry disease among cardiologists...
2017: Open Heart
https://www.readbyqxmd.com/read/28408708/nonfamilial-hypertrophic-cardiomyopathy-prevalence-natural-history-and-clinical-implications
#15
Jodie Ingles, Charlotte Burns, Richard D Bagnall, Lien Lam, Laura Yeates, Tanya Sarina, Rajesh Puranik, Tom Briffa, John J Atherton, Tim Driscoll, Christopher Semsarian
BACKGROUND: Yield of causative variants in hypertrophic cardiomyopathy (HCM) is increased in some probands, suggesting different clinical subgroups of disease occur. We hypothesized that a negative family history and no sarcomere mutations represent a nonfamilial subgroup of HCM. We sought to determine the prevalence, natural history, and potential clinical implications of this nonfamilial subgroup of HCM. METHODS AND RESULTS: Four hundred and thirteen unrelated probands with HCM seen in a specialized HCM center between 2002 and 2015 and genetic testing performed were included in this retrospective cohort study...
April 2017: Circulation. Cardiovascular Genetics
https://www.readbyqxmd.com/read/28402037/atrial-electrophysiological-and-molecular-remodelling-induced-by-obstructive-sleep-apnoea
#16
Devika Channaveerappa, Jacob C Lux, Kelly L Wormwood, Timothy A Heintz, Meredith McLerie, Jacqueline A Treat, Hannah King, Donia Alnasser, Robert J Goodrow, Glenn Ballard, Robert Decker, Costel C Darie, Brian K Panama
Obstructive sleep apnoea (OSA) affects 9-24% of the adult population. OSA is associated with atrial disease, including atrial enlargement, fibrosis and arrhythmias. Despite the link between OSA and cardiac disease, the molecular changes in the heart which occur with OSA remain elusive. To study OSA-induced cardiac changes, we utilized a recently developed rat model which closely recapitulates the characteristics of OSA. Male Sprague Dawley rats, aged 50-70 days, received surgically implanted tracheal balloons which were inflated to cause transient airway obstructions...
April 12, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28400398/multi-imaging-method-to-assay-the-contractile-mechanical-output-of-micropatterned-human-ipsc-derived-cardiac-myocytes
#17
Alexandre J Ribeiro, Olivier Schwab, Mohammad A Mandegar, Yen-Sin Ang, Bruce R Conklin, Deepak Srivastava, Beth L Pruitt
Rationale: During each beat, cardiac myocytes generate the mechanical output necessary for heart function through contractile mechanisms that involve shortening of sarcomeres along myofibrils. Human induced pluripotent stem cells can be differentiated into cardiac myocytes that model cardiac contractile mechanical output more robustly when micropatterned into physiological shapes. Quantifying the mechanical output of these cells enables us to assay cardiac activity in a dish. Objective: We sought to develop a computational platform that integrates analytical approaches to quantify the mechanical output of single micropatterned cardiac myocytes from microscopy videos...
April 11, 2017: Circulation Research
https://www.readbyqxmd.com/read/28394039/elasticity-of-the-transition-state-leading-to-an-unexpected-mechanical-stabilization-of-titin-immunoglobulin-domains
#18
Guohua Yuan, Shimin Le, Mingxi Yao, Hui Qian, Xin Zhou, Jie Yan, Hu Chen
The giant protein titin plays a critical role in regulating the passive elasticity of muscles, mainly through the stochastic unfolding and refolding of its numerous immunoglobulin domains in the I-band of sarcomeres. The unfolding dynamics of titin immunoglobulin domains at a force range greater than 100 pN has been studied by atomic force microscopy, while that at smaller physiological forces has not been measured before. By using magnetic tweezers, it is found that the titin I27 domain unfolds in a surprising non-monotonic force-dependent manner at forces smaller than 100 pN, with the slowest unfolding rate occurring around 22 pN...
April 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28393762/engineering-a-functional-three-dimensional-human-cardiac-tissue-model-for-drug-toxicity-screening
#19
Hong Fang Lu, Meng Leong, Tze Lim, Ying Ping Chua, Jia Kai Lim, Chan Du, Andrew C A Wan
Cardiotoxicity is one of the major reasons for clinical drug attrition. In vitro tissue models that can provide efficient and accurate drug toxicity screening are highly desired for preclinical drug development and personalized therapy. Here, we report the fabrication and characterization of a human cardiac tissue model for high throughput drug toxicity studies. Cardiac tissues were fabricated via cellular self-assembly of human transgene-free iPSC-derived cardiomyocytes in pre-fabricated polydimethylsiloxane molds...
April 10, 2017: Biofabrication
https://www.readbyqxmd.com/read/28392437/a-model-of-cardiac-contraction-based-on-novel-measurements-of-tension-development-in-human-cardiomyocytes
#20
Sander Land, So-Jin Park-Holohan, Nicolas P Smith, Cristobal G Dos Remedios, Jonathan C Kentish, Steven A Niederer
Experimental data from human cardiac myocytes at body temperature is crucial for a quantitative understanding of clinically relevant cardiac function and development of whole-organ computational models. However, such experimental data is currently very limited. Specifically, important measurements to characterize changes in tension development in human cardiomyocytes that occur with perturbations in cell length are not available. To address this deficiency, in this study we present an experimental data set collected from skinned human cardiac myocytes, including the passive and viscoelastic properties of isolated myocytes, the steady-state force calcium relationship at different sarcomere lengths, and changes in tension following a rapid increase or decrease in length, and after constant velocity shortening...
April 7, 2017: Journal of Molecular and Cellular Cardiology
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