Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1762617 (weakness)
 37,932 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myopathy is usually a non-fatal muscle disease involving skeletal muscle weakness, tenderness and pain with the possibility of the plasma creatinine kinase elevation. There are many different types of myopathies, some of which are genetic, inflammatory, or related to endocrine dysfunction. Also, numerous drugs have been reported to possess myotoxic effect. Myopathy is included among the potential side-effects and toxicities associated with the lipid lowering agents, particularly 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors. However, the precise mechanism of statin-induced muscle toxicity remains unclear. The muscle-related side-effects reported with lipid-lowering drugs are significant but quite rare (0.1%), when used in monotherapy; while the incidence of steroid-induced myopathy has varied from 7 to 60%% and chronic alcoholic myopathy seems to be common complication of alcoholism affecting approximately 50% of patients, respectively. This review focuses on the differential pathophysiological grounds of these muscular injuries induced by statins, fibrates, as well as some other agents: corticosteroids or alcohol. A wide spectrum of possible mechanisms and hypotheses including muscle enzyme defects, changes in mitochondrial function and intracellular metabolism, the influence on the cell membrane stability and drug interactions involving P-glycoprotein or cytochrome P 450 system have been presented.
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PMID:Drug-induced myopathies. An overview of the possible mechanisms. 1584 74

Hb-M is a very rare hemoglobinopathy in the Indian subcontinent. We report a family with Hb-M with lifelong cyanosis from the Ratnagiri district in western India. The propositus was a 11-year-old female child with a history of increasing cyanosis exacerbated by fever and weakness. Similar complaints were also noted in her mother and five maternal family members. There was no history of cardiac illness or exposure to drugs and chemicals. The methemoglobin level was 39.3% in the propositus and 21.1% in her mother with normal NADH-methemoglobin reductase activity. Abnormal absorption peaks by spectroscopic analysis, presence of hemoglobin instability, and a slow-moving band on starch gel electrophoresis supported the presence of Hb-M. Automated DNA sequence analysis of the beta globin gene showed a C-->T substitution at codon 63. This leads to a substitution of histidine (CAT) by tyrosine (TAT) at the beta 63 (E7) position, similar to Hb-M Saskatoon. We have named this variant as Hb-M(Ratnagiri).
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PMID:Congenital methemoglobinemia caused by Hb-MRatnagiri (beta-63CAT-->TAT, His-->Tyr) in an Indian family. 1592 17

Reduction of low-density lipoprotein cholesterol (LDL) concentration has become the primary goal and a standard of care in the practice of cholesterol management. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, are the most frequently prescribed lipid lowering agents on the market. As more information is learned through the results of clinical trials, LDL goals become more stringent and difficult to attain. Large doses of high-potency statins, sometimes given in combination with other lipid-lowering agents, are frequently necessary to achieve these goals. As a result, the frequency of adverse effects from statin therapy may be expected to increase, and less common adverse effects may occur more often. As statins are used more aggressively, rare and possibly dangerous adverse effects must be identified, especially those that are becoming more frequently encountered. Increased awareness may lead to earlier diagnosis and management of diseases that may be caused by the statins. We describe a 58-year-old man who was hospitalized with idiopathic pancreatitis 4 months after starting simvastatin therapy. His oral drug therapy was withheld, and he was treated with bowel rest. The patient was discharged on hospital day 5, and his oral drug regimen, including simvastatin, was resumed. He was admitted again 16 months later with a second diagnosis of acute pancreatitis and was discharged after 3 days of bowel rest with no oral drug therapy. Simvastatin was restarted on discharge, but the patient stopped taking it after experiencing muscle soreness and weakness in his arms. He recalled having similar arm pain that preceded the previous episode of acute pancreatitis. All other causes of the pancreatitis had been ruled out; thus, the correlation between simvastatin-induced myalgia and onset of acute pancreatitis on two separate occasions made simvastatin the suspected instigating agent. Pancreatitis is a rare adverse effect of statin therapy, but it has been documented in several case reports involving most of the statins. Continued reporting is necessary to increase awareness of this rare adverse effect of simvastatin so that it may be promptly managed or avoided in the future.
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PMID:A case of simvastatin-associated pancreatitis and review of statin-associated pancreatitis. 1650 23

Muscle pain and weakness are frequent complaints in patients receiving 3-hydroxymethylglutaryl coenzymeA (HMG CoA) reductase inhibitors (statins). Many patients with myalgia have creatine kinase levels that are either normal or only marginally elevated, and no obvious structural defects have been reported in patients with myalgia only. To investigate further the mechanism that mediates statin-induced skeletal muscle damage, skeletal muscle biopsies from statin-treated and non-statin-treated patients were examined using both electron microscopy and biochemical approaches. The present paper reports clear evidence of skeletal muscle damage in statin-treated patients, despite their being asymptomatic. Though the degree of overall damage is slight, it has a characteristic pattern that includes breakdown of the T-tubular system and subsarcolemmal rupture. These characteristic structural abnormalities observed in the statin-treated patients were reproduced by extraction of cholesterol from skeletal muscle fibres in vitro. These findings support the hypothesis that statin-induced cholesterol lowering per se contributes to myocyte damage and suggest further that it is the specific lipid/protein organization of the skeletal muscle cell itself that renders it particularly vulnerable.
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PMID:Statin therapy induces ultrastructural damage in skeletal muscle in patients without myalgia. 1679 20

Central core disease is a nonprogressive or slowly progressive congenital myopathy with a variable degree of hypotonia and axial and proximal muscle weakness that is histologically characterized by areas devoid of oxidative enzyme activity, resulting from an absence or low numbers of mitochondria in these regions (central core). A 10-month-old, male, pony foal was examined because of stiff gait, marked contractures of the distal portion of the limbs, flexion deformities of the hooves, and moderate hypotonia that had been present from birth. The foal had increased creatine kinase (282 U/liter; reference interval 10-135 U/liter), lactate dehydrogenase (1,188 U/liter; reference interval 150-450 U/liter), and aspartate transaminase (377 U/liter; reference interval <290 U/liter) activities, suggesting muscle disease. Muscle biopsy was performed. In cytochrome oxidase-, succinate dehydrogenase-, and reduced nicotinamide adenine dinucleotide tetrazolium reductase-reacted sections, the dominant morphologic feature was the absence of oxidative enzyme activity in the cores. By use of immunohistochemical technique with a monoclonal antibody against desmin, the cores were clearly delineated and a desmin network was present within the cores. Ultrastructurally, the core areas were characterized by preserved sarcomeres with irregular Z-lines, with some streaming or zigzag appearance and abnormal sarcoplasmic reticulum profiles and T-tubules. Lack of mitochrondria within central cores was observed. Diagnosis of myopathy with central cores was made.
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PMID:Myopathy with central cores in a foal. 1684 6

Muscle toxicity is one adverse reaction reported with the use of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins). This toxicity may include asymptomatic elevations of muscle enzymes, weakness, myalgia, and myositis. High doses of statins, or the combination of statins with other anti-cholesterol medications, increase the risk of toxicity. In addition, case reports of systemic and autoimmune reactions such as lupus, nephritis, vasculitis, and myositis, suspected to be associated with statins, have been reported. Our 76-year-old patient demonstrates a case of serologically and biopsy-proven inflammatory polymyositis, combined with a statin toxic myopathy. His symptoms and enzyme abnormalities resolved with both the removal of the statin medication and the institution of immunosuppressive therapy. Investigation of muscle enzyme elevation and weakness that do not resolve with statin removal is warranted. Certain muscle biopsy findings, including mononuclear cell infiltrate, distinguish the etiology as inflammatory/possibly autoimmune and do not suggest statin myopathy.
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PMID:A case of atorvastatin combined toxic myopathy and inflammatory myositis. 1703 67

Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase occasionally cause myopathy characterized by weakness, pain, and elevated serum creatine phosphokinase (CK). In this study, we investigated the effects of simvastatin, an HMG-CoA reductase inhibitor, on the viability and insulin-like growth factor-1 (IGF-1) signaling in differentiating C2C12 mouse myoblast cells. Simvastatin decreased cell viability and CK activity, a marker of myogenesis, in differentiating cells in a dose-dependent manner. Although the simvastatin-induced decrease in viability in proliferating and differentiated cells was completely abolished by mevalonate or geranylgeranyl-pyrophosphate, the inhibitory effects of simvastatin in differentiating cells were not abolished by mevalonate or isoprenoid derivatives of mevalonate. Moreover, the sensitivity of differentiating cells to simvastatin regarding cell viability was about 7 times higher than that of proliferating cells. After induction of differentiation in the presence of 1 microM simvastatin for 2 days, IGF-1-induced activation of ERK1/2 and Akt was significantly decreased. Although mRNA expression of the IGF-1 receptor beta-chain (IGF-1R beta) did not change, protein level of the 200 kDa IGF-1Rbeta precursor was significantly increased by simvastatin in a dose-dependent manner. Mevalonate did not abolish the effect of simvastatin on IGF-1Rbeta expression. These results suggest that simvastatin decreases IGF-1 signaling via a regulation of the post-translational modification of IGF-1Rbeta in an HMG-CoA reductase inhibition-independent manner.
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PMID:Simvastatin reduces insulin-like growth factor-1 signaling in differentiating C2C12 mouse myoblast cells in an HMG-CoA reductase inhibition-independent manner. 1732 94

We report a novel homozygous mutation responsible for NADH-b(5)R deficiency in a family from Ratnagiri district in western India with recessive congenital methemoglobinemia (RCM) type I. The propositus was a 20-year-old female with a history of increasing cyanosis exacerbated by fever and weakness. There was no history of cardiac illness or exposure to drugs and chemicals. The methemoglobin level was 38.0% in the propositus with 70% reduction in NADH-b(5)R activity. Spectroscopic analysis of the hemolysate showed normal peaks suggesting absence of Hb-M. There was no hemoglobin instability and G6PD activity was normal. This novel G-->A homozygous mutation at codon 143 in exon 5 was identified by SSCP followed by DNA sequencing and results in a glycine to aspartic acid substitution in the cytochrome b(5) reductase protein. This mutation, which is located outside the FAD and NADH binding domain, leads to mild cyanosis. Investigations of the family members revealed that both the parents and a brother of the propositus were heterozygous for the G143D mutation.
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PMID:A novel G143D mutation in the NADH-cytochrome b5 reductase gene in an Indian patient with type I recessive hereditary methemoglobinemia. 1796 95

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are lipid-lowering agents widely employed for atherosclerosis prevention. HMG-CoA reductase blockade reduces skeletal muscle coenzyme Q(10) (CoQ(10)) levels and mitochondrial respiratory chain activities and may produce mild to severe skeletal muscle myopathy. This study investigated whether high-dose statin treatment would result in measurably decreased exercise capacity in older men and women. Maximal oxygen consumption, aerobic endurance, oxygen uptake kinetics, maximal strength, muscular power, and muscular endurance were measured before and after 12 weeks of statin treatment (simvastatin, 80 mg/day) in nine men and one woman, ages 55-76 years, with LDL-cholesterol levels >3.3 mmol/l (mean = 4.2 +/- 0.2 mmol/l). Myalgia symptoms were assessed every 4 weeks. As expected, statin treatment resulted in significant decreases in LDL- and total-cholesterol levels (P < 0.01) with no significant changes in HDL-cholesterol or triglyceride levels. No significant changes were observed in aerobic capacity, endurance, oxygen kinetics or any measures of muscle function. No subject reported symptoms of myalgia, cramps, or weakness during the study. In the absence of myalgia or myopathic symptoms, high-dose simvastatin treatment did not impair exercise capacity in hyperlipidemic older individuals. We conclude that decreases in intramuscular CoQ(10), in most patients on high dose statin treatment may not be clinically relevant, due to inter-individual variability in the degree of CoQ(10) depletion, sensitivity of muscle to decreases in CoQ(10), or both.
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PMID:High-dose statin use does not impair aerobic capacity or skeletal muscle function in older adults. 1942 52

Hydroxymethylglutaryl-coenzyme A reductase inhibitors or statins are the most effective medications for reducing elevated concentrations of low-density lipoprotein cholesterol (LDL-C). Statins reduce cardiac events in patients with coronary artery disease and previously healthy persons. Current recommendations for LDL-C treatment goals indicate that more patients will be treated with higher doses of these medications. Statins have been extremely well-tolerated in controlled clinical trials but are increasingly recognized to produce skeletal muscle myalgia, cramps, and weakness. The reported frequency of such mild symptoms is not clear, and muscle performance has not been examined with these medications. Accordingly, the present investigation, the Effect of Statins on Skeletal Muscle Function and Performance (STOMP) study, will recruit approximately 440 healthy persons. Participants will be randomly assigned to treatment with atorvastatin 80 mg/d or placebo. Handgrip, elbow and knee isometric and isokinetic strength, knee extensor endurance, and maximal aerobic exercise performance will be determined at baseline. Participants will undergo repeat testing after 6 months of treatment or after meeting the study definition of statin myalgia. This study will determine the effect of statins on skeletal muscle strength, endurance, and aerobic exercise performance and may ultimately help clinicians better evaluate statin-related muscle and exercise complaints.
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PMID:A randomized clinical trial to assess the effect of statins on skeletal muscle function and performance: rationale and study design. 2062 64


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