Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of age and sex on the induction of chronic EAMG was analysed. Aged male rats, immunized with Torpedo acetylcholine receptor (tAChR), showed no clinical signs of disease or AChR loss. Immunization of young male Brown Norway (BN) rats resulted in both clinical signs of disease and 65% AChR loss. In contrast, both young and aged female BN rats showed comparable AChR loss (58% and 50%, respectively), although aged female rats did not develop clinical signs of disease. Differences in antibody titres, isotype distribution, fine specificity or complement activation could not account for the observed resistance. These results suggest that resistance against EAMG in aged rats is due to resistance of the AChR against antibody-mediated degradation, or to mechanisms able to compensate for AChR loss.
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PMID:Age- and sex-related resistance to chronic experimental autoimmune myasthenia gravis (EAMG) in Brown Norway rats. 901 Feb 75

Susceptibility to experimental autoimmune myasthenia gravis (EAMG) was found to decrease with aging in both Lewis and Brown Norway (BN) rats. In this study, the difference in susceptibility between young and aged Lewis and BN rats was used to analyze factors determining the clinical severity of EAMG. The incidence and severity of muscular weakness did not correlate with acetylcholine receptor (AChR) loss nor with the ability of antibodies to interfere with AChR function. Aged rats showed significantly lower anti-rat AChR antibody titers than young rats and developed less severe or no clinical signs of disease. In individual young or aged rats, however, no significant correlation was found between the clinical signs of disease and anti-rat AChR titer. Neuromuscular transmission was found to change with aging as measured by single-fiber electromyography (SFEMG). In aged BN rats, increased jitter and blockings were found even before EAMG induction. Despite this disturbed neuromuscular transmission, these aged BN rats were clinically resistant against induction of EAMG. The results of this study indicate that the age-related susceptibility to EAMG is influenced by factors determined by the immune attack as well as mechanisms at the level of the neuromuscular junction.
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PMID:Age-related susceptibility to experimental autoimmune myasthenia gravis: immunological and electrophysiological aspects. 927 Jun 63

We examined the age-related association in skeletal muscle between atrophy and expression of mRNAs encoding both the gamma-subunit of the nicotinic acetylcholine receptor (AChR), and myogenin, a transcription factor that upregulates expression of the gamma-subunit promoter. Gastrocnemius and biceps brachii muscles were collected from young (2-mo-old), adult (18-mo-old), and old (31-mo-old) Fischer 344/Brown Norway F1 generation cross male rats. In the gastrocnemius muscles of old vs. young and adult rats, lower muscle mass was accompanied by significantly elevated AChR gamma-subunit and myogenin mRNA levels. In contrast, the biceps brachii muscle exhibited neither atrophy nor as drastic a change in AChR gamma-subunit and myogenin mRNA levels with age. Expression of the AChR epsilon-subunit mRNA did not change with age in either gastrocnemius or biceps brachii muscles. Thus changes in skeletal muscle AChR gamma-subunit and myogenin mRNA levels may be more related to atrophy than to chronological age in old rats.
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PMID:Expression of acetylcholine receptor mRNAs in atrophying and nonatrophying skeletal muscles of old rats. 980 97

Experimental autoimmune myasthenia gravis (EAMG) is a T cell-dependent, Ab-mediated autoimmune disease induced in rats by a single immunization with acetylcholine receptor (AChR). Although polarized Th1 responses have been shown to be crucial for the development of mouse EAMG, the role of Th cell subsets in rat EAMG is not well established. In the present work we show that while the incidence and severity of EAMG are similar in Lewis (LEW) and Brown-Norway (BN) rats, strong differences are revealed in the immune response generated. Ag-specific lymph node cells from LEW rats produced higher amounts of IL-2 and IFN-gamma than BN lymph node cells, but expressed less IL-4 mRNA. IgG1 and IgG2b anti-AChR isotype predominated in BN and LEW rats, respectively, confirming the dichotomy of the immune response observed between the two strains. Furthermore, although IL-12 administration or IFN-gamma neutralization strongly influenced the Th1/Th2 balance in BN rats, it did not affect the disease outcome. These data demonstrate that a Th1-dominated immune response is not necessarily associated with disease severity in EAMG, not only in rats with disparate MHC haplotype but also in the same rat strain, and suggest that in a situation where complement-fixing Ab can be generated as a consequence of either Th1- or Th2-mediated T cell help, deviation of the immune response will not be an adequate strategy to prevent this Ab-mediated autoimmune disease.
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PMID:Experimental autoimmune myasthenia gravis may occur in the context of a polarized Th1- or Th2-type immune response in rats. 1035 65