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

In the normal striated muscle, tissue transglutaminase (TG2) content is vestigial. However, this protein's presence has been reported to occur in myoblasts and myotubes during the fetal period. Its increased expression has been also found in the muscle tissue in the course of sporadic inclusion body myositis, as well as in polymyositis (PM) and dermatomyositis (DM), which are considered to be diseases of immunological origin. Based on in vitro studies, a substantial TG2 role in the infiltration of some T cell subsets into inflamed tissues has been suggested lately. In this study, the immunohistochemical reactions in the guinea pig experimental myositis specimens and in the ones from PM/DM patients were compared. The guinea pig tissue specimens were taken from muscles affected by experimental myositis induced by intramuscular injections of: 1/sera from 30 neoplasm patients with no metastases; 2/sera from 10 healthy people; 3/sera from 2 DM patients; 4/neuropeptides (SP, NPY or VIP) and from 5/the muscles affected by the reversed passive Arthus reaction (RPAR). The immunostaining for TG2 revealed substantial presence of this protein in single, damaged muscle fibers and a weak reaction in regenerating fibers appearing in PM/DM patients' specimens. From among experimental myositis specimens, a very intensive reaction appeared only in the damaged and regenerating muscle fibers present in the slides from guinea pig muscles injected with DM patients' sera. Such results suggest some presence of a specific factor(s) (the one(s) responsible for TG2 expression in the damaged muscle fibers) in DM patients' sera. The results suggest that transglutaminase can be a marker of inflammatory myopathies. A probable correlation between TG2 expression in muscles and organismal immunological factors, including the complement activation status, requires additional studies.
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PMID:Can tissue transglutaminase be a marker of idiopathic inflammatory myopathies? 1575 64

Dermatomyositis and polymyositis patients have an increased risk of developing cancers. We have assessed the diagnostic values of serum tumor markers for the detection of solid cancer in dermatomyositis/polymyositis patients. Serum carcinoembryonic antigen, CA15-3, CA19-9, and CA125 were assayed by immunoradiometric methods in 102 dermatomyositis/polymyositis patients. All the patients had complete physical examination, chest X-ray, echocardiogram, gastrointestinal tract endoscopic explorations, thoracoabdomino-pelvic computed tomography scan, and all women had gynecologic examination and mammogram. Exclusion criteria for study were childhood dermatomyositis, inclusion body myositis, myositis associated with a connective tissue disease, prior history of cancer, and the presence of benign conditions known to elevate serum tumor markers. After a median follow-up of 59 months, 10 (9.8%) patients had a solid cancer. Initial elevation of CA125 was associated with an increased risk of developing solid cancer [P = 0.0001 by Fisher's exact test; odds ratio (OR), 29.7; 95% confidence interval (95% CI), 8.2-106.6]. For CA19-9, there was a trend towards a significant association (P = 00.7; OR, 4.5; 95% CI, 1-18.7, respectively). Diagnostic values of elevated CA125 and CA19-9 at screening increased when the study analysis was restricted to patients who developed a cancer within 1 year (P < 0.0001 and P = 0.018, respectively) or to patients without interstitial lung disease (P = 0.00001; OR, 133; 95% CI, 6.5-2733 and P = 0.027; OR, 9; 95% CI, 1.5-53, respectively). Individual comparisons of the baseline and the second CA125 value showed that three of the eight patients with cancers versus 3 of the 76 patients without, displayed an increase of their CA125 level (P = 0.01 by Fisher's exact test). We conclude that CA125 and CA19-9 assessment could be useful markers of the risk of developing tumors for patients with dermatomyositis and polymyositis and should therefore be included in the search for cancer in dermatomyositis/polymyositis patients, especially for patients without interstitial lung disease.
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PMID:Tumor antigen markers for the detection of solid cancers in inflammatory myopathies. 1589 86

Myostatin is a negative regulator of muscle mass and strength. Sporadic inclusion-body myositis (s-IBM) is the most common degenerative muscle disease of older persons and is characterized by pronounced muscle wasting. s-IBM is of unknown etiology and pathogenesis, and it lacks definitive treatment. We have now demonstrated in samples from 12 s-IBM biopsies that: (1) by light and electron microscopic immunocytochemistry, myostatin/myostatin precursor is accumulated within muscle fibers and co-localized with amyloid-beta (Abeta); (2) by immunoblots, both myostatin and myostatin precursor are increased; and (3) by immunoprecipitation, myostatin precursor complexes with Abeta. Our study suggests that myostatin/myostatin precursor, either alone, or bound to Abeta, may play a novel role in the pathogenesis of s-IBM.
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PMID:Myostatin is increased and complexes with amyloid-beta within sporadic inclusion-body myositis muscle fibers. 1598 28

The 26S proteasome system is involved in eliminating various proteins, including ubiquitinated misfolded/unfolded proteins, and its inhibition results in cellular accumulation of protein aggregates. Intramuscle-fiber ubiquitinated multiprotein-aggregates are characteristic of sporadic inclusion-body myositis (s-IBM) muscle fibers. Two major types of aggregates exist, containing either amyloid-beta (Abeta) or phosphorylated tau (p-tau). We have now asked whether abnormalities of the 26S proteasome contribute to s-IBM pathogenesis and whether the multiprotein aggregates have features of aggresomes. Using cultured human muscle fibers we also studied the effect of amyloid-beta precursor protein (AbetaPP) overexpression on proteasome function and the influence of proteasome inhibition on aggresome formation. We report that in s-IBM muscle biopsies 26S proteasome subunits were immunodetected in the gamma-tubulin-associated aggresomes, which also contained Abeta, p-tau, ubiquitin, and HSP70. In addition, a) expression of proteasome subunits was greatly increased, b) the 20Salpha proteasome subunit co-immunoprecipitated with AbetaPP/Abeta, and c) the three major proteasomal proteolytic activities were reduced. In cultured muscle fibers, AbetaPP-overexpressing fibers displayed diminished proteasomal proteolytic activities, and addition of proteasome inhibitor strikingly increased aggresome formation. Accordingly, proteasome dysfunction in s-IBM muscle fibers may play a role in accumulation of misfolded, potentially cytotoxic proteins and may be induced by increased intracellular AbetaPP/Abeta.
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PMID:Proteasome inhibition and aggresome formation in sporadic inclusion-body myositis and in amyloid-beta precursor protein-overexpressing cultured human muscle fibers. 1604 36

Dermatomyositis, polymyositis, inclusion body myositis and myositis overlap syndromes are systemic immune disorders of unknown origin with muscle weakness and elevated values of creatinkinase in the serum. Muscle biopsy is pivotal for a proper clinical diagnosis. Extramuscular findings at the skin, the joints or internal organs (lung, heart) are characteristic for the different clinical presentations of dermato- or polymyositis and are usually absent in inclusion body myositis. With the exception of inclusion body myositis myositis-associated autoantibodies are frequently present and associated with distinct clinical manifestations (e. g. antisynthetase syndrome). The rate of malignancy is elevated for several years after onset of myositis. Especially in polymyositis an appropriate differential diagnosis of infectious, endocrine, metabolic or neuromuscular causes of muscle disease is necessary. Glucocorticosteroids are the first choice of treatment in dermato- or polymyositis. Methotraxate, azathioprine, cyclophosphamamide, i.v. immunoglobulins and other drugs are used in diseases courses with continuous high dose requirement of corticosteroids.
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PMID:[Inflammatory muscle diseases: dermatomyositis, polymyositis, and inclusion body myositis]. 1620 Apr 4

This guideline presents recommendations for the diagnosis and treatment of dermatomyositis, polymyositis and sporadic inclusion body myositis (sIBM) according to the best available evidence. Characteristic skin abnormalities can be sufficient for the diagnosis of dermatomyositis. In case of doubt, a skin biopsy is advisable. A muscle biopsy is indicated when other examinations are inconclusive and the musculature is involved. The working group considers screening for cancer to be required in adults with dermatomyositis and presents recommendations for the way that this should be done. At least one-third of all patients with polymyositis has, or will develop, an associated inflammatory connective tissue disease. If a patient with a connective tissue disease develops symmetrical, proximal muscle weakness in the course of weeks or months, this may be assumed to be due to polymyositis. In the absence ofpre-existing connective tissue disease, demonstration of a mononuclear cell infiltrate in muscle tissue is a prerequisite for the diagnosis ofpolymyositis. The histopathology of muscle tissue is used as the gold standard for the diagnosis of sIBM. The practice guideline presents criteria for the concept 'activity' of myositis. Disease activity serves as a guideline for the treatment of polymyositis and dermatomyositis. The treatment of choice for dermatomyositis and polymyositis is high-dose prednisone. Physical activity does not have a negative effect on the course of these diseases. The long-term prognosis ofdermatomyositis and polymyositis is not well known. The clinical course of sIBM is slowly progressive.
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PMID:[The practice guideline 'Dermatomyositis, polymyositis and sporadic inclusion body myositis']. 1620

We describe a 72- year-old patient with a ten year history of anti-PM-Scl positive systemic sclerosis associated with inclusion-body myositis. While the association of dermatomyositis and polymyositis with anti-PM-Scl positive systemic sclerosis is frequently reported, inclusion-body myositis was, to the best of our knowledge, only previously described once in association with anti-PM-Scl-positive systemic sclerosis. The distinction between inclusion-body myositis and other forms of inflammatory myopathy, like the histopathologically well distinguishable polymyositis or dermatomyositis, is relevant because of the poor response of inclusion- body myositis to immunosuppressive treatment. Our case underlines that in patients with anti-PM-Scl-positive systemic sclerosis and treatment resistant progressive myopathy the diagnosis of inclusion body myositis should be considered.
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PMID:[PM-Scl antibody positive systemic sclerosis associated with inclusion-body myositis]. 1624 33

The idiopathic inflammatory myopathies (IIM) are systemic connective tissue diseases in which autoimmune pathology is suspected to promote chronic muscle inflammation and weakness. We have performed low to high resolution genotyping to characterize the allelic profiles of HLA-A, -B, -Cw, -DRB1, and -DQA1 loci in a large population of North American Caucasian patients with IIM representing the major clinicopathologic groups (n = 571). We confirmed that alleles of the 8.1 ancestral haplotype were important risk markers for the development of IIM, and a random forests classification analysis suggested that within this haplotype, HLA-B*0801, DRB1*0301 and/ or closely linked genes are the principal HLA risk factors. In addition, we identified several novel HLA factors associated distinctly with 1 or more clinicopathologic groups of IIM. The DQA1*0201 allele and associated peptide-binding motif (KLPLFHRL) were exclusive protective factors for the CD8+ T cell-mediated IIM forms of polymyositis (PM) and inclusion body myositis (IBM) (pc < 0.005). In contrast, HLA-A*68 alleles were significant risk factors for dermatomyositis (DM) (pc = 0.0021), a distinct clinical group thought to involve a humorally mediated immunopathology. While the DQA1*0301 allele was detected as a possible risk factor for IIM, PM, and DM patients (p < 0.05), DQA1*03 alleles were protective factors for IBM (pc = 0.0002). Myositis associated with malignancies was the most distinctive group of IIM wherein HLA Class I alleles were the only identifiable susceptibility factors and a shared HLA-Cw peptide-binding motif (AGSHTLQWM) conferred significant risk (pc = 0.019). Together, these data suggest that HLA susceptibility markers distinguish different myositis phenotypes with divergent pathogenetic mechanisms. These variations in associated HLA polymorphisms may reflect responses to unique environmental triggers resulting in the tissue pathospecificity and distinct clinicopathologic syndromes of the IIM.
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PMID:Immunogenetic risk and protective factors for the idiopathic inflammatory myopathies: distinct HLA-A, -B, -Cw, -DRB1 and -DQA1 allelic profiles and motifs define clinicopathologic groups in caucasians. 1626 9

Sporadic inclusion-body myositis (s-IBM), the most common muscle disease of older persons, is of unknown cause and there is no successful treatment. We summarize our most recent findings in s-IBM muscle fibers, which demonstrate abnormalities of the ubiquitin-proteasome system, and abnormal accumulation, misfolding and aggregation of proteins. We propose that these changes, possibly provoked by the aging intra-muscle fiber cellular milieu, and aggravated by the oxidative stress, play a key pathogenic role in s-IBM. This evidence strongly suggests that mechanisms other than the immune/inflammatory response play the important role in s-IBM muscle fiber degeneration.
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PMID:Sporadic inclusion-body myositis: a proposed key pathogenetic role of the abnormalities of the ubiquitin-proteasome system, and protein misfolding and aggregation. 1631 67

The diagnostic aspects of sporadic inclusion-body myositis (s-IBM), and a few comments on our own approach to its treatment, are presented to foster the goals of this symposium, which was organized to provoke new ideas concerning the cause and treatment of this currently unsolvable disease. s-IBM is the most common, progressive, debilitating muscle disease beginning in persons over age 50 years, and it is more common in men. Diagnostic parameters reviewed are clinical, muscle-biopsy histochemistry, electrophysiologic and CSF evaluations. Overall, the degenerative phenomena in s-IBM muscle fibers seem to be the major cause of the progressive, unstoppable weakness, rather than the lymphocytic inflammation. Available treatments are of only slight, temporary benefit for only some s-IBM patients, indicating a desperate need for definitive therapies.
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PMID:Inclusion-body myositis: clinical, diagnostic, and pathologic aspects. 1643 41


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