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Chemical Materials Used in the Lab
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Chemical materials used in the lab are classified under three categories: Materials used in the manual preparation of muscle histochemistry (Table 5.1) such as hematoxylin and eosin (H&E) stain, Gomori trichrome (GT), periodic acid-Schiff (PAS), oil red, Congo red, and oxidative enzymatic reactions. These materials are prepared by the technologist specialist following a fixed formulated protocol. Our manual protocol is described in Chapter 7.Materials used in the preparation of muscle immunohistochemistry. These materials are ready-to-use antibody kits, manufactured by several companies (such as Leica), and prepared by the technologist via automated immunostainer (such as Ventana). These antibody kits have fixed expiration dates and require system detection kits and bulk fluids to run them in the immunostainer. Table 5.2 lists the antibodies commonly used in neuromuscular diagnosis. Many of these antibodies are used to diagnose muscle dystrophy diseases such as dystrophinopathies, sarcoglycanopathies, and dysferlinopathy. Major histocompatibility stain (MHC) is another commonly used antibody in pathological practice that helps in the diagnosis of inflammatory myopathy subsets. Further details about these stains are described in Chapter 7.Materials used in the preparation of nerve tissue and electron microscopy (Table 5.3).
Diseases of the Peripheral Nerve and Mononeuropathies
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Diana Mnatsakanova, Charles K. Abrams
It is important to assess for the different etiologies of foot drop: Lower motor neuron: L5 radiculopathy.Lumbosacral plexopathy.Sciatic neuropathy.Anterior horn cell lesion: Spinal muscular atrophy.Motor neuron diseases.Amyotrophic lateral sclerosis (also look for UMN signs).Upper motor neuron: Stroke or tumor.Distal myopathy: Dysferlinopathy.Myotonic dystrophy.Inclusion body myositis.
Structural and ultrastructural changes in the skeletal muscles of dysferlin-deficient mice during postnatal ontogenesis
Published in Ultrastructural Pathology, 2022
O. N. Chernova, I. A. Chekmareva, M. O. Mavlikeev, I. A. Yakovlev, A. P. Kiyasov, R.V. Deev
Dysferlin is a protein located in sarcolemma and a t-tubule system encoded by the DYSF gene. Dysferlin is responsible for many functions in muscle fibers, such as the repair of damaged sarcolemma, vesicle fusion, cell adhesion, intercellular signaling,1–5 myoblast fusion6 and t-tubule reorganization during myogenesis.3,7,8 Normally, in sarcolemmal rupture, calcium ions trigger synaptic vesicle fusion with membrane “patch” formation. Without dysferlin, vesicular trafficking to the site of rupture is impaired. Progressive sarcolemma disruption results in necrosis of skeletal muscles with fibrosis and lipoidosis.9 Moreover, the lack of dysferlin expression decreases lysosomal exocytosis.10 Mutations in the DYSF gene cause inherited autosomal-recessive muscle dystrophies called dysferlinopathies. This group of disorders includes three clinical phenotypes: limb-girdle muscular dystrophy (LGMD) R2 (OMIM 254130), Myoshi muscular dystrophy (OMIM 253601) and distal myopathy with anterior tibial onset (OMIM 606678). These patients usually manifest limb-girdle muscle weakness in the second decade of life.11 Approximately 5% of previously described patients develop asymptomatic hyperCPKemia.12,13 This finding indicates a probable prolonged subclinical course of dysferlinopathies. As dysferlinopathy is an orphan disease (prevalence of 7.4:1000000),14 the absence of clinical manifestations prevents patients from being within the health care system. Moreover, studying dysferlinopathy pathogenesis at early stages is almost impossible due to the traumatic nature of muscle biopsy in asymptomatic pediatric patients.
An update on diagnostic options and considerations in limb-girdle dystrophies
Published in Expert Review of Neurotherapeutics, 2018
Corrado Angelini, Laura Giaretta, Roberta Marozzo
Sanger sequencing of genomic DNA of individual genes is largely used in mutation detection, however, should be used especially when clinical features or protein testing suggest which gene should be screened: in this way a large number of LGMD cases can be molecularly diagnosed. Sanger sequencing of cDNA may also be required for identifying deep intronic or elusive exonic variants disrupting the correct splicing, which are over 10% of total pathogenetic mutations. However, this analysis requires a muscle biopsy, even if mRNA may also be successfully extracted from blood in dysferlinopathy.