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Parasite Versus Host: Pathology and Disease
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
No discussion of metaplasia is complete without mentioning nematodes in the genus Trichinella. In this case, fully differentiated skeletal muscle cells are reprogrammed into very different cells. Several species in this genus (see Figure 2.26) share a bizarre life cycle in which the same mammal can serve as both definitive and intermediate host. The most important species in humans is T. spiralis, usually acquired by consuming undercooked pork or meat from certain wild game, including bear and boar meat.
Striated MusclesSkeletal and Cardiac Muscles
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Cardiac muscle is striated, but the pattern is not as ordered as in skeletal muscle. The striations are similar to those of skeletal muscle cells, being made up of sarcomeres (between Z lines) containing thick myosin filaments (in the A band) and thin actin filaments (in the I band), which are attached to the Z lines. Compared with skeletal muscle, cardiac muscle cells are shorter and thicker and form branching networks with intercalated discs between the ends of adjacent fibres that contain low-electrical-resistance gap junctions. Cardiac muscle functions as a syncytium due to the presence of low-resistance connections between adjacent cells, and when an action potential is generated, the atria or the ventricles contract together. The mechanical connections that prevent the cells from pulling apart include the desmosomes and fascia adherens.
Measurement of Transmembrane Potential in the Study Of Systemic Disease*
Published in Richard C. Niemtzow, Transmembrane Potentials and Characteristics of Immune and Tumor Cell, 2020
J. Hamilton Licht, Hardin Jones
Welt et al. observed high intracellular sodium and chloride in erythrocytes from uremic individuals and the term “sick cells” was subsequently coined.12 In part to determine whether the “sick cell” syndrome applied to skeletal muscle cells in severely ill patients, Cunningham et al.20 examined normal and severely ill subjects, eight of whom had uremia. They measured skeletal muscle Em and intracellular electrolytes and observed that in uremic individuals muscle cells have high intracellular sodium and chloride concentrations and low Em. In other studies of skeletal muscle in uremia, low intracellular potassium was also observed.27 The fundamental cell membrane defect(s) was not identified in these studies, but inferences were made. Both groups noted a disparity between Em calculated using the Goldman Equation (Equation 1) and measured Em. This disparity may have been due either to enhanced permeability of the cell membrane to sodium or to decreased activity of membrane sodium- potassium-ATPase.20, 27 The latter hypothesis is supported by in vitro studies of erythrocytes from uremic individuals and ATPase preparations from uremic brains.2, 36, 37
A review of surgical management of progressive myogenic ptosis
Published in Orbit, 2023
Royce B. Park, Sruti S. Akella, Vinay K. Aakalu
Oculopharyngeal muscular dystrophy (OPMD) is a slowly progressive disease involving symmetric blepharoptosis, dysphagia, and proximal muscle weakness.3 It is inherited in an autosomal dominant pattern and its onset is insidious, typically manifesting during the fifth or sixth decade of life.3 French Canadians (Quebec), Hispanic New Mexicans, and Israeli Bukhara Jewish populations are most prevalently affected by OPMD.13 The condition is diagnosed through molecular genetic testing and manifests as a myopathy affecting skeletal muscle cells.38 The levator palpebrae superioris and pharyngeal muscles are often most severely impaired, but the disease can also involve other extraocular muscles and limb muscle groups.38 Patients will compensate for progression of ptosis with contraction of the frontalis muscle and “backward head tilt.”38 Meanwhile, the orbicularis oculi muscle and Bell’s phenomenon are fairly well-preserved in OPMD patients.3 Surgical techniques described include blepharoplasty, levator advancement, frontalis sling, and combined aponeurosis-Muller muscle advancement.12
Effects of acute endurance exercise on follistatin-like 1 and apelin in the circulation and metabolic organs in rats
Published in Archives of Physiology and Biochemistry, 2022
Michihiro Kon, Yuko Tanimura, Hideo Yoshizato
Consistent with the results of our study, the increase in the secretion of FSTL1 to the circulation due to a single bout of endurance exercise has been also recently reported in a previous study (Görgens et al. 2013). However, to date, it has not been clarified which tissues affect the endurance exercise-induced increase in the secretion of FSTL1. We demonstrated here that acute endurance exercise did not increase the levels of FSTL1 in skeletal muscle, adipose, heart, and liver tissues. In a previous study, skeletal muscle cell contraction caused by electrical pulse stimulation, used as an in vitro exercise model, was reported to not affect the secretion and mRNA expression of FSTL1 in skeletal muscle cells (Görgens et al. 2013). Collectively, these results suggested that although acute endurance exercise could increase the circulating levels of FSTL1, the increase in the secretion of FSTL1 might not be derived from skeletal muscle, adipose, heart, and liver tissues. Noted, FSTL1 has been recognised to be expressed in multiple tissues (Adams et al. 2010). Therefore, FSTL1 derived from other organs, save for the tissues observed in this study, may be associated with the elevated secretion of FSTL1.
Bidirectional regulation of genistein on the proliferation and differentiation of C2C12 myoblasts
Published in Xenobiotica, 2020
Mailin Gan, Dongli Yang, Yuan Fan, Jingjing Du, Linyuan Shen, Qiang Li, Yanzhi Jiang, Guoqing Tang, Mingzhou Li, Jinyong Wang, Xuewei Li, Shunhua Zhang, Li Zhu
Skeletal muscle is an important tissue in animals, and it accounts for 30–40% of total body weight (Shen et al., 2016). Skeletal muscle cells of vertebrates are contractile, multinucleated cells that undergo a complex differentiation process during their development. The majority of myocytes are derived from the paraxial mesodermal somites. These mesodermal progenitor cells proliferate and subsequently withdraw from the cell cycle. They then differentiate into myotubes and myofibers; this maturation is driven by the muscle-specific factors (Sabourin & Rudnicki, 2000). Under the control of neural regulation, skeletal muscle and bones constitute the motor system, and skeletal muscle also a main metabolic organ and endocrine organ (Abe et al., 2016; Schnyder & Handschin, 2015). Skeletal muscle participates in glucose utilization, muscle glycogen synthesis, and fatty acid oxidation. It also synthesizes and secretes many active factors in the regulation of cell biological processes. The function of skeletal muscle is closely related to many diseases, including dyskinesia, muscle atrophy, insulin resistance, and obesity (Reynolds et al., 2016; Wu & Ballantyne, 2017).