Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The childhood type fo dermatomyositis, which occurs in children and young adults, shows a specific constellation of pathologic changes in muscle. Capillary necrosis leads to capillary loss, generally starting on the periphery of muscle fascicles. Electron microscopy discloses undulating tubules in endothelial cells, lymphocytes, pericytes, and pseudosatellite cells. The muscle fiber damage is coextensive with capillary damage and probably results from progressive ischemia. The muscle cells, before atrophying, show mitochondrial elongation, Z disk streaming, focal myofibrillary loss, and occassionally selective thick filament loss. Muscle cell necrosis is rare and limited to infarctlike lesions. Inflammatory infiltrates, if present, occur only in connective tissue septa. The cause of the capillary damage has not been determined.
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PMID:The childhood type of dermatomyositis. 18 70

The inflammatory myopathies encompass a group of heterogenous muscle diseases which have in common an acquired myopathy with histological signs of endomysial inflammation. We present evidence based on recently emerged clinical, histologic, immunopathologic, demographic and therapeutic observations that these myopathies comprise three major and distinct groups: polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis (IBM). Immune-mediated mechanisms characteristic for each group appear to play a primary role in the pathogenesis of these diseases. In DM there is an intramuscular microangiopathy mediated by the C5b-9 membranolytic attack complex, leading sequentially to loss of capillaries, muscle ischemia, muscle fiber necrosis and perifascicular atrophy. In contrast, in PM and IBM the muscle fiber injury is initiated by sensitized CD8+ cytotoxic T cells that recognize MHC-I restricted muscle antigens, leading to phagocytosis and fiber necrosis. Among the viruses implicated in the cause of inflammatory myopathies, only the retroviruses, HIV, HTLV-1 and simian retroviruses, have been convincingly associated with PM. Retroviruses, therefore, appear to be the leading group of viruses capable of triggering these diseases. The treatment of inflammatory myopathies has been largely empirical. A detailed therapeutic plan based on our experience with a large number of patients is presented. Patients with bona fide PM or DM respond to steroids to some degree and for some period of time. In contrast, patients with IBM do not respond to any therapy and the disease should be suspected when a patient with presumed PM has failed treatment. Methotrexate and cyclophosphamide are disappointing. Cyclosporine and Azathioprine are commonly used but they are of uncertain benefit. Plasmapheresis is ineffective. High-dose intravenous immunoglobulin is a promising new therapeutic modality.
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PMID:Clinical, immunopathologic, and therapeutic considerations of inflammatory myopathies. 142 35

Muscle biopsies from 57 patients with dermatomyositis or polymyositis were histologically evaluated and compared with the disease's clinical course. Perifascicular atrophy, perivascular infiltrates and tubular inclusions in endothelial cells were significantly more frequent in young patients with dermatomyositis. On the other hand, in adult polymyositis, which evolves more slowly, necrosis with slight muscular atrophy and perinecrotic infiltrates was observed. This division into two groups was clear when the clinical evolution and histological patterns were compared. The mean age of each group was different, but there was a large overlap. Two different pathogenetic mechanisms can be envisaged: primary involvement of muscle capillaries with muscle ischemia in young patients with dermatomyositis and primary involvement of muscle fibers in adults afflicted with polymyositis.
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PMID:[Histopathologic aspects of polymyositis and dermatomyositis. Correlation with the clinical course. Study of 57 cases]. 269 97

Ten of 17 muscle biopsy specimens from 15 patients with childhood dermatomyositis (DM) showed distinct perifascicular atrophy. The atrophic fibers showed the following characteristics: (1) decreased cytochrome c oxidase (CCO) activity, (2) rare positive reaction with acridine orange (AO) staining, (3) type 2C reaction in 7.9% (0.4-17.5%) of the fibers, (4) an increased number of activated satellite cells, (5) mitochondria which were increased in number but decreased in size, (6) a significantly decreased CCO activity in isolated mitochondria (51.6 +/- 30.3 nmol/min per mg mitochondrial protein) as compared with that in the controls (103.6 +/- 41.5). The major pathogenetic mechanism in muscles in childhood DM is thought to be ischemia due to involvement of the microvasculature. The presence of type 2C fibers and increased numbers of activated satellite cells reflect a focal repair process taking place concomitantly in the damaged myofibers. Mitochondrial enzyme defect, especially CCO deficiency is present not only in genetic disorders with mitochondrial involvement but in other neuromuscular disorders including inflammatory myopathies.
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PMID:Perifascicular atrophic fibers in childhood dermatomyositis with particular reference to mitochondrial changes. 285 14

Immunoreactive class 1 and class 2 major histocompatibility complex gene products (MHCP) and beta 2 microglobulin (beta 2 MG) were demonstrated by microscopic immunocytochemistry in cryostat sections of skeletal muscle biopsies of 67 patients with various neuromuscular diseases. Diagnoses included normal muscle, chronic partial denervation, Duchenne dystrophy, polymyositis, dermatomyositis, inclusion body myositis, and miscellaneous neuromuscular diseases. Normal mature muscle fibers did not express MHCP, but blood vessels showed both class 1 and 2 MHCP and beta 2 MG. Regenerating muscle fibers showed consistent sarcolemmal class 1 MHCP expression irrespective of the disease. In polymyositis, the majority of extrafusal muscle fibers of most patients showed strong sarcolemmal class 1 MHCP expression. In dermatomyositis, muscle fibers situated either in perifascicular or in randomly clustered distribution revealed strong class 1 MHCP reactivity. In inclusion body myositis, scattered small clusters of muscle fibers were positive for class 1 MHCP. In polymyositis and inclusion body myositis, particularly strong class 1 MHCP expression was invariably seen in nonnecrotic muscle fibers partially invaded by lymphocytes whose cytotoxic effects are believed to be class 1 MHCP restricted. Factors or agents that trigger class 1 MHCP expression are presumed also to sensitize lymphocytes to muscle fibers in these diseases, but their identity remains obscure at this time. In dermatomyositis, the expression of MHCP in perifascicular muscle fibers and in areas of capillary loss may represent the triggering of MHCP expression by a nonspecific cellular stress reaction, in this case probably low-grade ischemia.
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PMID:Expression of immunoreactive major histocompatibility complex products in human skeletal muscles. 327 73

We describe 2 patients in whom juvenile dermatomyositis (DM) was associated with well defined clinical polyneuropathies, and review the clinical and serological data. Light and electron microscopy were used to study muscle and nerve tissues from one patient. Neuropathy in our patients was associated with ulcerative skin lesions and elevated serum levels of factor VIII related antigen. Light microscopic studies of muscle revealed perifascicular atrophy and microinfarcts consistent with juvenile DM. Light microscopy of the affected sural nerve showed axonal degeneration. Electron microscopy of the same nerve demonstrated capillary endothelial inclusions characteristic of those observed as manifestations of early endothelial injury in juvenile DM muscle tissue. Polyneuropathy in patients with juvenile DM is a rare complication and is likely due to ischemia secondary to endothelial damage.
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PMID:Polyneuropathy in juvenile dermatomyositis. 897 68

A sixty-two-year-old woman with chronic dermatomyositis (DM) receiving steroid monotherapy developed coronary artery stenosis. She had lung fibrosis and complained of dyspnea, but no ischemia was suggested by electrocardiogram. Ateriographic findings and clinical symptoms of coronary artery disease in DM have not been previously reported.
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PMID:Coronary artery disease in dermatomyositis. A case report. 763 23

In patients with dermatomyositis (DM) the earliest lesion is microvasculopathy mediated by deposition of C5b-C9 membranolytic attack complex (MAC) on intramuscular capillaries. This leads sequentially to muscle ischemia, necrosis of muscle fibers, and muscle weakness. High-dose intravenous immunoglobulin (IVIG), which can modulate complement-dependent tissue damage in animal models, has been shown to be effective in the treatment of patients with DM. We used an in vitro C3 uptake assay to examine 55 coded sera from 13 patients with DM and 5 patients with other non-complement-mediated neuromuscular diseases, before and after treatment with IVIG or placebo. Patients with active DM had a significantly higher baseline C3 uptake compared with the others (geometric mean 12,190 vs 3,090 cpm). Post-IVIG but not post-placebo sera inhibited the C3 uptake, without depleting the complement components, by 70.6-93.4%. The maximum inhibition of C3 uptake occurred within hours after IVIG infusion, started to rebound 2 d later, and reached pretreatment levels after 30 d. The serum levels of SC5b-9 complex production were high at baseline but normalized after IVIG therapy. Repeat biopsies from muscles of improved patients showed disappearance of C3b NEO and MAC deposits from the endomysial capillaries and restoration of the capillary network. We conclude that IVIG exerts its beneficial clinical effect by intercepting the assembly and deposition of MAC on the endomysial capillaries through the formation of complexes between the infused immunoglobulins and C3b, thereby preventing the incorporation of activated C3 molecules into C5 convertase. These findings provide the first serological and in situ evidence that IVIG modulates complement attack in a human disease.
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PMID:High-dose intravenous immunoglobulin exerts its beneficial effect in patients with dermatomyositis by blocking endomysial deposition of activated complement fragments. 796 20

We studied mitochondrial function in inflammatory myopathies, using cytochrome c oxidase (COX) reaction on muscle biopsy samples from 30 patients (15 with dermatomyositis, 12 with polymyositis, and 3 with inclusion body myositis) and 30 age-matched controls. We also performed immunocytochemistry for COX II and COX IV subunits in 7 of these patients who had COX deficiency. COX-deficient fibers were a constant finding in patients or controls older than 65 years and the percentage of COX-deficient fibers correlated with age in both patients and controls. Focal COX deficiency was found in 24 patients (13 of 15 with dermatomyositis, 8 of 12 with polymyositis, and 3 of 3 with inclusion body myositis) and 18 controls. The percentages of COX-deficient fibers were higher in patients with inflammatory myopathies (range: 0-4.7%; mean: 1.2%) than in age-matched controls (range: 0-1.9%; mean: 0.4%) (P < 0.01). In the subgroup of patients under age 65, COX-deficient fibers were more frequent in dermatomyositis than in polymyositis (mean: 0.8% vs 0.2%, P = 0.02). In patients with dermatomyositis, capillary loss correlated positively with COX deficiency (P < 0.02). Immunocytochemistry for COX II and IV showed that 82% of COX-negative fibers were COX II-negative and 26% were COX IV-negative, suggesting that proteins encoded by mitochondrial DNA are predominantly, but not exclusively, involved in COX deficiency. We conclude that mitochondrial dysfunction and COX deficiency can occur in inflammatory myopathies. Such a mitochondrial dysfunction is not solely related to the aging process. We suggest that muscle ischemia contributes to mitochondrial dysfunction in dermatomyositis.
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PMID:Cytochrome c oxidase deficiencies in the muscle of patients with inflammatory myopathies. 874 Feb 35

Immune-mediated mechanisms appear to play a primary role in the pathogenesis of polymyositis (PM) and dermatomyositis (DM). The serum of patients with active DM has high levels of circulating complement fragments C3b, C4b, and C5b-9 membranolytic attack complex (MAC) and demonstrates a very high C3 uptake in an vitro assay system. The MAC and the immune complex-specific C3bNEO fragment are deposited on the endomysial capillaries early in the disease and lead sequentially to loss of capillaries, muscle ischemia, muscle fiber necrosis, and perifascicular atrophy. In contrast, in PM the muscle fiber injury is initiated by sensitized CD8+ cytotoxic T cells that recognize heretofore unknown and probably endogenous muscle antigens in the context of major histocompatibility complex (MHC) class I expression. A restricted (oligoclonal) pattern of T-cell receptor with prominence of Va1, Vb6, and Vb15 genes is noted within the endomysial infiltrates suggesting that the T-cell response is antigen driven. In both PM and DM, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 are upregulated in the endomysial endothelial cells and function as ligands for the leukocyte integrins leukocyte function-associated antigen (LFA)-1 and very late activating antigen (VLA)-4, allowing activated lymphocytes to adhere to the endothelial cells and migrate to the muscle fibers. Among viruses, only the retroviruses human immunodeficiency virus (HIV) and human T-cell lymphotropic virus (HTLV)-1 have been convincingly shown to trigger PM, which is mediated by nonviral-specific, cytotoxic CD8+ cells. The treatment of inflammatory myopathies remains empirical. Many patients respond to steroids to some degree and for some period of time. Azathioprine, methotrexate, cyclosporine, cyclophosphamide, and plasmapheresis can be of mild to moderate benefit. High-dose intravenous immunoglobulin (IVIg) is a promising therapeutic modality for some patients resistant to therapies. In a controlled study, IVIg was effective in DM not only in improving the clinical symptoms but also in reversing the underlying immunopathology. The role of IVIg in PM and IBM is under study in control trials.
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PMID:Immunopathogenesis of inflammatory myopathies. 896 19


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