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Approach to Neuromyopathy
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Neurological impairments in patients with malignancies can arise from several factors including chemotherapy, malnutrition, infection, or direct tumor invasion. One of the paraneoplastic complications is neuromyopathy. Subacute sensory and motor neuropathy is commonly associated with small-cell lung cancer but may also occur in other malignancies, including breast cancer, sarcoma, leukemia, and Hodgkin lymphoma. Muscle biopsy findings vary from necrotizing autoimmune myopathy (NAM) associated neuropathic change to predominant type II atrophy, to findings suggestive for nerve vasculitis. CD68-stained macrophages and MHC class-I are always expressed. Rimmed vacuoles and protein aggregate are typically not found in muscle fibers. In few patients, the muscle looks healthy while the inflammation only exists in the perimysium. In this case, further inflammatory markers should be used to identify the type of inflammation.
Skeletal Muscle
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The cell membrane of the muscle fiber is the sarcolemma and has the ionic properties characteristic of excitable cells, manifested as a resting membrane voltage of about –90 mV and the ability to generate and propagate a muscle action potential. The sarcolemma is coated on the outside by a basement membrane formed largely of glycoproteins, and each muscle fiber is surrounded by a delicate layer of connective tissue, the endomysium (Figure 9.1). Groups of about 10 to more than 100 muscle fibers are bundled together into fascicles, the number of muscle fibers in a fascicle being larger in muscles that produce greater force, with less fineness of control. Fascicles are surrounded, in turn, by another layer of connective tissue, the perimysium. The whole muscle is ensheathed by a dense layer of irregular connective tissue, the epimysium.
Fascial Anatomy
Published in David Lesondak, Angeli Maun Akey, Fascia, Function, and Medical Applications, 2020
There are many types of collagen, and almost 90% of the collagen of the muscles can be found in the perimysium.16,17 Although there are parallel collagen fibers in the deep fascia, there are other layers that have different fiber orientation. This allows force transmission to occur in a variety of multidirectional planes.18,19 Also, mechanical load and tension increase collagen synthesis and make it more resistant to load stress.
Histological and immunohistochemical study of the effect of ozone versus erythropoietin on induced skeletal muscle ischemia-reperfusion injury in adult male rats
Published in Ultrastructural Pathology, 2022
Magdy F. Gawish, Sally A. Selim, Alyaa A. Abd El-Star, Samah M. Ahmed
Control group showed long cylindrical non-branched muscle fibers with acidophilic cytoplasm, transverse striations, and multiple peripheral elongated nuclei. Muscle fibers were separated by delicate connective tissue called the endomysium and muscle bundles were separated by perimysium (Figure 3a). IR group exhibited disrupted muscle fibers with loss of striation, increased endomysial spaces, and central dark stained nuclei. Edema was observed as wide separation of the muscle bundles (Figure 3b). Degenerative changes were observed as some muscle fibers showed hyalinization of the sarcoplasm and nuclear clumps (Figure 3c). Extravasation and congested blood vessels between the damaged skeletal muscle fibers were also detected (Figure 3d). Post-reperfusion ozone-treated group revealed most of the muscle fibers appeared relatively normal with peripheral flat nuclei, cross-striations, narrow endomysial spaces, and blood vessel in the perimysium while some fibers with central nuclei were present (Figure 3e). Post-reperfusion EPO-treated group showed most of muscle fibers appeared regular with narrow endomysial spaces, cross-striations, and peripheral flat nuclei (Figure 3f). The recovering post-reperfusion without treatment showed muscle fibers were disarranged with central nuclei and widely separated (Figure 3g). Also, waviness of muscle fibers with numerous vesicular nuclei was observed in other sections (Figure 3h).
Development of a finite-element muscle model accounting for transverse loading
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
M. Maamir, L. Chèze, B. Fréchède
Using a commonly described active–passive 3D continuum material law, our FE muscle model showed an adequate behaviour in axial loading. However, in order to reproduce the experimental transverse/longitudinal coupling behaviour previously reported, it required some additional control of the activation. Limitations of our single muscle model include that it does not account so far for the significant pennation angle of the gastrocnemius muscle (30°). Further, as muscle fibres’ density is not currently controlled for in the material model, transverse geometrical effects resulting in e.g. a dynamic decrease or increase in the PCSA induce slight but uncontrolled changes in the axial muscle force. Further investigation and refinement of the model is thus also required regarding e.g. the modelling of the transverse behaviour of the 3D passive component, the modelling of the aponeurosis and of its attachment to the perimysium.
Metalloproteinases in disease: identification of biomarkers of tissue damage through proteomics
Published in Expert Review of Proteomics, 2018
Cristina Herrera, Teresa Escalante, Alexandra Rucavado, Jay W. Fox, José María Gutiérrez
Exudate proteomic analysis from mice injected with SVMPs also underscored the presence of fragments of types XII, XIV and XV collagens. The former two are fibril-associated collagens with interrupted triple helices (FACITs) and play a role in the supramolecular organization of fibrillar collagens [91]. In skeletal muscle, these FACITs connect muscle BM with the connective tissue components of epimysium and perimysium [92,93]. Type XV collagen, on the other hand, acts as a BM organizer [94]. Both types VI and XV collagens are degraded to a higher extent by hemorrhagic SVMPs than by non-hemorrhagic enzymes, suggesting that their hydrolysis might be implicated in the mechanical weakening of the capillary wall which causes hemorrhage [58]. Figure 5 summarizes the main targets of SVMPs in the BM and surrounding matrix components.