Search results for "Sarcoplasm"
showing 10 items of 26 documents
Paradoxical effect of increased diastolic Ca(2+) release and decreased sinoatrial node activity in a mouse model of catecholaminergic polymorphic ven…
2012
Background— Catecholaminergic polymorphic ventricular tachycardia is characterized by stress-triggered syncope and sudden death. Patients with catecholaminergic polymorphic ventricular tachycardia manifest sinoatrial node (SAN) dysfunction, the mechanisms of which remain unexplored. Methods and Results— We investigated SAN [Ca 2+ ] i handling in mice carrying the catecholaminergic polymorphic ventricular tachycardia–linked mutation of ryanodine receptor (RyR2 R4496C ) and their wild-type (WT) littermates. In vivo telemetric recordings showed impaired SAN automaticity in RyR2 R4496C mice after isoproterenol injection, analogous to what was observed in catecholaminergic polymorphic ventricul…
Expression Profile of Stress Proteins, Intermediate Filaments, and Adhesion Molecules in Experimentally Denervated and Reinnervated Rat Facial Muscle
1997
The immunohistochemical profiles of ubiquitin, heat shock protein 70, alpha-B-crystallin, desmin, vimentin, neural cell adhesion molecule (N-CAM), and tenascin in rat facial muscle were studied after permanent denervation by transection of the facial plexus on one side and compared with findings after immediate reinnervation by hypoglossal-facial nerve anastomosis subsequent to transection on the contralateral side. Levator labii muscle samples were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery. Normal levator labii muscle fibers showed physiological expression of desmin and alpha-B-crystallin. Denervated rat facial muscle displayed distinct up-regulation of ubiquiti…
Impaired Binding to Junctophilin-2 and Nanostructural Alteration in CPVT Mutation
2021
Rationale: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare disease, manifested by syncope or sudden death in children or young adults under stress conditions. Mutations in the Ca 2+ release channel/RyR2 (type 2 ryanodine receptor) gene account for about 60% of the identified mutations. Recently, we found and described a mutation in RyR2 N-terminal domain, RyR2 R420Q . Objective: To determine the arrhythmogenic mechanisms of this mutation. Methods and Results: Ventricular tachycardias under stress conditions were observed in both patients with catecholaminergic polymorphic ventricular tachycardia and knock-in mice. During action potential recording (by patch-clamp in …
Tracking Ca
2019
We characterize thus-far elusive domain rearrangements of a calcium-transporting ATPase in the native membrane.
Aging-induced Up-regulation of Nuclear Binding Activities of Oxidative Stress Responsive NF-kB Transcription Factor in Mouse Cardiac Muscle
1996
The accumulation of lipofuscin to cardiomyocytes is a classical parameter of aging and is believed to reflect oxidative stress. NF-kB transcription factor complex is one of the cellular sensors which responds to oxidative stress and regulates gene expression. Our purpose was to study whether aging affects the level and distribution of DNA binding activities of NF-kB transcription factors both in cardiac sarcoplasm and nuclear extracts. We used electrophoretic mobility shift assays (EMSA) to characterize the DNA binding activities of NF-kB and two other transcription factors. AP-1 and Sp-1, in the myocardium of 4 months and 24 months old male and female NMRI-mice. The protein levels of p50, …
When tubules aggregate
2011
Within muscle fibres, tubules appear as microtubules, transverse tubules, and different components of the sarcotubular system, the latter consisting of longitudinal tubules and lateral or terminal sacs which, at special junctional connections, are situated on both sides of transverse tubules forming triads. Pathological structures related to the transverse tubules are honeycomb structures, both the transverse tubules and the honeycomb ones being labelled by extracellularly applied lanthanum [1] or potassium ferrocyanide [2], thus, indicating an open connection between the interior of the muscle fibres and the extracellular space. Dyads or multiple incomplete or complete forms of triads, pen…
Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles
2016
International audience; This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no dif…
Increased calcium influx is responsible for the sustained mechanical tone in colon from dystrophic (mdx) mice
2001
Abstract Background & Aims: Proximal colon from dystrophic mice develops spontaneous tone increment, but the mechanisms involved in its development have not been investigated. This study examined whether alterations in the properties of cell membrane calcium channels and/or sarcoplasmic reticular (SR) Ca 2+ -adenosine triphosphatase (ATPase) contribute to tone development. Methods: Effects of calcium-free solution, nifedipine, pinaverium (calcium channel blockers), and cyclopiazonic acid (CPA; SR Ca 2+ -ATPase inhibitor) on the contractile activity of colon from mdx and control mice were determined. Results Calcium-free solution abolished spontaneous contractions in both preparations, but d…
Controlled Release of Metformin Hydrochloride from Core-Shell Nanofibers with Fish Sarcoplasmic Protein
2019
Ficai, Anton/0000-0002-1777-0525; Karademir, Betul/0000-0003-1762-0284 WOS:000503463400074 PubMed ID: 31658758 Background and Objectives: A coaxial electrospinning technique was used to produce core/shell nanofibers of a polylactic acid (PLA) as a shell and a polyvinyl alcohol (PVA) containing metformin hydrochloride (MH) as a core. Materials and Methods: Fish sarcoplasmic protein (FSP) was extracted from fresh bonito and incorporated into nanofiber at various concentrations to investigate the influence on properties of the coaxial nanofibers. The morphology, chemical structure and thermal properties of the nanofibers were studied. Results: The results show that uniform and bead-free struct…
Nemaline myopathy with intranuclear rods--intranuclear rod myopathy.
1997
Among the different nosological forms of nemaline/rod myopathy, one morphological variant is marked by intranuclear rods in addition to sarcoplasmic rods. Such patients fall into two categories: firstly, adults and secondly, young infants suffering from the severe form. Intranuclear rods indicate unfavourable prognosis. Recently, intranuclear rods without sarcoplasmic rods have also been encountered. Intranuclear rods, largely solitary, are often found large in size with the ultrastructural lattice pattern of sarcoplasmic rods and Z-disks. They contain alpha-actinin and actin. The origin of intranuclear rods is still enigmatic. Their presence within nuclei without sarcoplasmic rods points t…