Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alcoholic myopathy occurs in up to two thirds of alcohol misusers and is characterized by selective atrophy of type II (anaerobic, fast-twitch) fibers; type I (aerobic, slow twitch) fibers are relatively unaffected. Both clinical and animal studies have indicated that skeletal muscle RNA content is reduced in response to ethanol exposure, and contributes to impaired protein synthesis. We hypothesized that the reduction in muscle RNA may be due to raised ribonuclease (RNase) activities that enhance RNA catabolism. To test this hypothesis, we measured the total tissue and plasma RNase activities as well as the activities of general (RNase A) and specific or "restriction" RNases (T1L, T2L) in ethanol-treated rats. Chronically treated rats were fed a nutritionally complete liquid diet with 35% of calories as ethanol. Weight-matched controls were pair-fed with isocaloric glucose. Rats were killed at time-points up to 6 weeks. For comparative purposes, the effect of acute (24 hr) starvation was also analyzed in a second group of rats relative to a group of control rats allowed free access to food and water over 24 hr. Results showed that the type II fiber-predominant plantaris muscle exhibited a significant increase in total RNase, RNase A and RNase T1L activities (increases ranged from +59% to +196%; P-values between 0.025 and 0.01) concomitant with large falls in RNA and protein content. In contrast, none of the RNase activities measured in the type I fiber-predominant soleus muscles were significantly affected; compositional changes were also smaller in the soleus. This effect was independent of reduced nutrition. In conclusion, the raised total RNase, RNase A and RNase T1L activities may contribute to the type II fiber-specific reduction in total RNA in chronically ethanol-treated rats. In turn, this may contribute to the alterations in cellular protein metabolism seen under these treatments.
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PMID:Skeletal muscle ribonuclease activities in chronically ethanol-treated rats. 966 Mar 15

Alcohol misusers frequently have difficulties in gait, and various muscle symptoms such as cramps, local pain and reduced muscle mass. These symptoms are common in alcoholic patients and have previously been ascribed as neuropathological in origin. However, biochemical lesions and/or the presence of a defined myopathy occur in alcoholics as a direct consequence of alcohol misuse. The myopathy occurs independently of peripheral neuropathy, malnutrition and overt liver disease. Chronic alcoholic myopathy is characterized by selective atrophy of Type II fibres and the entire muscle mass may be reduced by up to 30%. This myopathy is arguably the most prevalent skeletal muscle disorder in the Western Hemisphere and occurs in approximately 50% of alcohol misusers. Alcohol and acetaldehyde are potent inhibitors of muscle protein synthesis, and both contractile and non-contractile proteins are affected by acute and chronic alcohol dosage. Muscle RNA is also reduced by mechanisms involving increased RNase activities. In general, muscle protease activities are either reduced or unaltered, although markers of muscle membrane damage are increased which may be related to injury by reactive oxygen species. This supposition is supported by the observation that in the UK, alpha-tocopherol status is poor in myopathic alcoholics. Reduced alpha-tocopherol may pre-dispose the muscle to metabolic injury. However, experimental alpha-tocopherol supplementation is ineffective in preventing ethanol-induced lesions in muscle as defined by reduced rates of protein synthesis and in Spanish alcoholics with myopathy, there is no evidence of impaired alpha-tocopherol status. In conclusion, by a complex series of mechanisms, alcohol adversely affects skeletal muscle. In addition to the mechanical changes to muscle, there are important metabolic consequences, by virtue of the fact that skeletal muscle is 40% of body mass and an important contributor to whole-body protein turnover.
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PMID:Alcoholic skeletal muscle myopathy: definitions, features, contribution of neuropathy, impact and diagnosis. 1178 53