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Query: UMLS:C0027121 (myositis)
 4,538 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is believed that one muscle fiber consists of one fiber type determined by its innervating neuron. In biopsied muscles of Duchenne muscular dystrophy (DMD), however, the author has incidentally found a double-typed fiber which is divided into inner and outer parts. The author termed it a "boiled-egg fiber". The author has examined the appearance rate of the boiled-egg fibers on 682 biopsied muscles obtained from patients with various neuromuscular disorders, and classified the types of the inner and outer parts of the boiled-egg fibers by ATPase staining. Boiled-egg fibers were recognized in 17 cases out of 60 with DMD, 5 out of 146 with other types of muscular dystrophy and 6 out of 94 with myositis. No boiled-egg fiber was found in the remaining 382 cases with other disorders which did not represent necrosis with regeneration of muscle fibers. The total number of boiled-egg fibers was 235 with 192 in DMD and 43 in other disorders. 197 of 235 (83.8%) had the same type for both inner and outer parts and remaining 38 (16.2%) had different types for their inner parts. In 133 of 235 (56.6%), the inner parts were type 2C fibers. Boiled-egg fibers were segmentally found with the length of several hundred micrometers. The above findings suggest that boiled-egg fibers reflect an abnormal regenerating process. It remains to be clarified whether or not inner and outer parts of boiled-egg fibers are double-innervated respectively.
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PMID:[The significance of boiled-egg fibers in biopsied muscles of neuromuscular disorders]. 173 23

Animal models have proven very useful in furthering insight into a number of muscle diseases. Studies of ethanol-fed rats are being used to understand the pathogenetic mechanisms underlying acute and chronic myopathy induced by ethanol. Several animal species, including mice, dogs, and cats, develop X-linked muscular dystrophies, which have genetic defects identical to those of Duchenne muscular dystrophy. As in the human disease, these animals lack dystrophin. They are being used to investigate the mechanisms by which lack of dystrophin results in weakness and to examine myoblast transfer as a treatment modality. A model of eosinophilia-myalgia syndrome has recently been induced in Lewis rats by the feeding of L-tryptophan samples that were implicated in the clinical syndrome in humans, making possible studies of the pathogenesis of this interesting new entity. A dermatomyositis-like syndrome occurs spontaneously in dogs, and polymyositis-like illnesses can be induced in mice by immunization with muscle or following infection with selected viruses, especially enteroviruses. Study of the latter is helping us understand mechanisms in the etiology and pathogenesis of inflammatory myositis and virus-induced autoimmunity.
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PMID:Animal models of myopathy. 177 47

A band phagocytosis, following Z line and I band loss, is described in polymyositis, in epsilon amino caproic acid induced myopathy and in an experimental myositis of guinea pigs. It is far less prominent in Duchenne muscular dystrophy. This form of necrosis is always associated with lesions in the plasma membrane. It is argued that the ensuing ionic equilibration with the extracellular fluid allows activation of a calcium activated proteinase (CAP) which digests the Z line. Breakdown of the myofibrils into individual A bands promotes rapid phagocytosis of the myofibre contents and facilitates regeneration of the muscle.
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PMID:Phagocytosis of the A band following Z line, and I band loss. Its significance in skeletal muscle breakdown. 713 Nov 29

Cytokines have been shown to be potent inducers of major histocompatibility complexes (MHC) class I and II as well as of cell adhesion molecules in muscle tissue cultures, indicating that cytokines may play a role in mediating muscle fiber damage in inflammatory myopathies. We found in 21 cases of autoimmune myositis various amounts of inflammatory cells expressing interleukin (IL)-1 alpha and -beta, IL-2, IL-4, tumor necrosis factor (TNF) -alpha and -beta, and interferon (IFN)-gamma and its receptor. Muscle fibers displayed enhanced expression of IL-1 alpha and -beta, IL-2, and TNF-alpha. Upregulation of cytokines was strongest at sites of cellular infiltration typical for the respective myositis subtype. There was no correlation between the cytokine expression and the grade of inflammation. To a lesser extent, cytokines were also present in Duchenne muscular dystrophy expressed by muscle fibers positive for TNF-alpha and by phagocytic mononuclear cells. Expression of cytokines by the muscle fiber may enable the muscle fiber to induce and mediate the process of autoimmunization and antigen-expression by itself without primary presence of inflammatory cells. Cytokine-expressing muscle fibers may enhance the cytolytic potential of cytotoxic cells and the muscle fiber may serve as source and target.
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PMID:Cytokine expression profile in idiopathic inflammatory myopathies. 878 92

Calf hypertrophy is a typical clinical feature in neuromuscular diseases such as X-linked muscular dystrophies of Duchenne and Becker type and can be seen as an atypical feature in numerous other diseases. The diagnosis of calf hypertrophy usually is based on subjective visual assessment. The aim of this prospective study was to examine the prevalence of calf hypertrophy in a large number of patients with various neuromuscular diseases based on quantitative ultrasound measurement of calf muscle thickness. Additionally, true and pseudohypertrophy should be distinguished according to the absence or presence of abnormal muscle echointensities caused by infiltration of fat tissue. Fifty adult normal controls and 350 patients with various neuromuscular diseases were investigated. Absolute calf hypertrophy was diagnosed if the combined thickness of the gastrocnemius and soleus muscles exceeded the mean value of the control persons by at least 3.0 standard deviations (SD). Relative calf hypertrophy was diagnosed when the ratio of the combined thicknesses of the gastrocnemius and soleus muscles divided by the combined thicknesses of the rectus femoris and vastus intermedius muscles lay at least 3.0 SD below the mean value of the controls. Pseudohypertrophy was present if the echointensities of the gastrocnemius and soleus muscles reached or exceeded 3.0 SD above the mean value of the controls. An absolute hypertrophy of the calves was detected in 80 patients (= 22,9%; 64 true and 16 pseudohypertrophies), 16 patients exhibited a relative hypertrophy of the calves (= 4.6%; 12 true and 4 pseudohypertrophies). A significantly increased portion of both absolute calf hypertrophies and pseudohypertrophies as compared to the control group were found in juvenile proximal spinal muscular atrophy type 3, central core disease, centronuclear myopathy, benign X-linked muscular dystrophy of Becker type, autosomal recessive limb girdle muscular dystrophy, acid maltase deficiency, polymyositis, and granulomatous myositis. A significantly increased number of relative calf hypertrophies was present in juvenile proximal spinal muscular atrophy type 3, facioscapulohumeral muscular dystrophy, and inclusion body myositis. In the majority of the diseases included in the study, calf hypertrophy occurred in at least some patients. In conclusion, calf hypertrophy is a frequent and unspecific clinical feature in many neuromuscular diseases. Ultrasound is a convenient method for the exact definition of calf hypertrophy.
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PMID:Calf enlargement in neuromuscular diseases: a quantitative ultrasound study in 350 patients and review of the literature. 898 Dec 97

Tenascin-C (TN-C) is an extracellular matrix protein expressed during development in several tissues, but restricted to only a few areas in normal adult tissues. By immunizing mice with human fetal myoblasts we generated a monoclonal antibody to TN-C and mapped the epitope to the aminoterminal end containing EGF-like repeats. Using this antibody we detected by immunohistochemistry TN-C in the epimysium and perimysium of human fetal muscles, as well as in nonfibrillar deposits in myoblast cultures. In situ hybridization did not reveal any signal within human fetal muscle groups, suggesting that non-muscle cells synthesize the majority of the tenascin that localizes in and around human fetal muscle. Immunohistochemical analysis of muscle biopsies from Duchenne/Becker muscular dystrophy and myositis patients revealed that TN-C is expressed in skeletal muscle. Although the patterns of TN-C immunoreactivity were quite different in the two disease entities, the endomysial TN-C reactivity in both DMD/BMD and in myositis invariably correlated with the presence of macrophages.
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PMID:Tenascin-C expression correlates with macrophage invasion in Duchenne muscular dystrophy and in myositis. 913 39

We have studied the immunohistochemical expression of 14 different muscle proteins of the basal lamina, sarcolemma and cytoskeleton in primary sarcoglycanopathies (13 cases) and compared it with Duchenne dystrophy (6 cases) and myositis (5 cases). Sarcolemmal proteins (i.e. 4 sarcoglycans, beta-dystroglycan, dystrophin, beta-spectrin) were reduced both in sarcoglycanopathies and Duchenne dystrophy, because of structural and functional impairment of the plasma membrane. Sarcolemmal proteins are poorly expressed in regenerating fibers of all muscle disorders, due to a developmental delay or to an abnormal assembly. Laminins (alpha2 and beta chains) were preserved in all cases while utrophin was expressed in Duchenne muscle but not in sarcoglycanopathies. Regenerating fibers were studied with different markers (i.e. fetal myosin, desmin, vimentin, laminin alpha1). Fetal myosin positive fibers (as well as desmin and laminin alpha1), were significantly higher in Duchenne dystrophy (25%) than in age-matched sarcoglycanopathies (7%). Vimentin, a marker of early regeneration, was expressed at higher level in sarcoglycanopathies than in Duchenne dystrophy, suggesting in the former a lower extent of regeneration or a shorter regeneration cycle.
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PMID:Regeneration in sarcoglycanopathies: expression studies of sarcoglycans and other muscle proteins. 1045 Aug 3

The normal tissue tropism of adeno-associated virus (AAV) is poorly defined, although the majority of humans test seropositive for this virus. Eighty-five muscle biopsy specimens were tested for AAV genomes; AAV DNA was identified in 17% of normal and 10% of Duchenne muscular dystrophy muscle biopsy specimens, but in only 3% of peripheral blood samples. AAV genomes were absent from all 37 muscle biopsy specimens from patients with myositis tested. Muscle is a major target organ for AAV, and infection is associated with autoimmune disease of muscle.
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PMID:Adeno-associated virus in normal and myositis human skeletal muscle. 1113 97

Dysferlin deficiency is being increasingly recognized in limb-girdle dystrophy and distal myopathy but its role in the development of muscle pathology is still poorly understood. For this purpose, 26 muscle biopsies from 25 dysferlinopathy patients were analysed by routine histochemistry and by immunohistochemistry with eight different antibodies, and scored for inflammatory response and type of cell infiltrate, fibre degeneration and regeneration, fibre type composition and severity of histopathological changes. In cases with an advanced-stage dystrophic pattern we observed type 1 fibre predominance exceeding 80%, suggesting a selective loss of type 2 fibres or a conversion process. The extent of muscle fibre regeneration and degeneration in dysferlinopathy was intermediate between sarcoglycanopathy and Duchenne dystrophy or myositis, suggesting a rather aggressive course of the disease. An increased inflammatory response was observed in the majority of our patients (16/26), who also showed an active dystrophic pattern. Type and localization of cellular infiltrates suggest that inflammatory reaction is secondary to necrosis. Major histocompatibility complex (MHC) class I molecules were overexpressed in dysferlinopathy, mainly in association with fibre phagocytosis and regeneration; their occasional expression in non-necrotic fibres might represent a marker of ongoing necrosis. Muscle inflammation might be triggered by the structurally altered membrane consequent to dysferlin defect.
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PMID:Muscle pathology in dysferlin deficiency. 1244 62

Neuromuscular disorders are frequently seen in our clinical practice, though no certain data are available in this regard. This prospective, observational study which was done as a partial fulfillment of M.Phil (Pathology) degree in BSMMU. The study was undertaken at the Department of Pathology of Bangabandhu Shiekh Mujib Medical University from August 1999 to December 2000 to study the histomorphological pattern of neuromuscular disorders in a selected group of patients attending the neuromedicine, paediatrics and medicine departments of BSMMU. Another purpose of this study was to evaluate the diagnostic utility of muscle biopsy and clinico-pathologic correlation in the diagnosis of neuromuscular disorders. In this study, 55 cases of clinically diagnosed neuromuscular disorders of different kinds were included. Detail clinical history was obtained in all the cases. Clinical diagnosis were made on the basis of history, physical examination, reports of routine and special laboratory tests whenever available. Muscle biopsy was performed in all the cases and histological changes could be identified in 42 cases. In the remaining thirteen undiagnosed cases; eight cases revealed 'essentially normal muscle tissue' and five cases were inadequate for histological evaluation. So, the later two categories were not included for further analysis. Among the histologically diagnosed 42 cases of neuromuscular disorders, basically two different classes of diseases were identified; 1) Dystrophic type of muscular diseases 64.28% and 2) Non dystrophic (acquired) type of neuromuscular diseases such as Inflammatory myopathy 21.82% and Neurogenic muscular atrophy 7.14%. Within the dystrophic group the maximum number of diseases were diagnosed as Duchenne muscular dystrophy 21.49%, Primary myopathy-unclassified 19.04%, Baker muscular dystrophy 4.76% and Limb girdle muscular dystrophy 4.76% etc. Properly executed muscle biopsy is usually the most useful and effective technique for diagnosis of neuromuscular diseases in cases where immunohistochemical, genetic and electron microscopic examination is not possible.
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PMID:A study of histopathological pattern of neuromuscular disorders with clinico-pathologic correlation. 1467 16


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