RESUMO
Aim: Some patients experience statin-associated muscle symptoms (SAMS) and elevated serum concentrations of CK. The relationship between SAMS and biomarkers of muscle damage was examined. Methods: We analyzed 359 consecutive patients taking statins with high CK values. Muscle-related symptoms and biochemical variables, including CK, MB isoenzyme of creatine kinase (CK-MB), troponin and carbonic anhydrase type III were evaluated. Results: SAMS was reported by 181 (50.4%) patients and they had greater BMI (p = 0.021) and a trend toward higher CK-MB values (p = 0.064). The use of simvastatin (OR: 2.24; 95% CI: 1.47-3.42), CK-MB (OR: 1.59; 95% CI: 1.02-2.49) and BMI (OR: 1.06; 95% CI: 1.01-1.10) were independent variables for SAMS. Conclusion: Simvastatin use, BMI and CK-MB were independent markers of SAMS.
Assuntos
Creatina Quinase/sangue , Inibidores de Hidroximetilglutaril-CoA Redutases/efeitos adversos , Doenças Musculares/sangue , Doenças Musculares/induzido quimicamente , Biomarcadores/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
OBJECTIVES: To describe muscle-related statin adverse effects in real-world pediatric practice. STUDY DESIGN: Using prospectively collected quality improvement data from a pediatric preventive cardiology practice, we compared serum creatine kinase (CK) levels among patients prescribed and not prescribed statins, and pre-/poststatin initiation. Multivariable mixed-effect models were constructed accounting for repeated measures, examining the effect of statins on log-transformed CK (lnCK) levels adjusted for age, sex, weight, season, insurance type, and race/ethnicity. RESULTS: Among 1501 patients seen over 3.5 years, 474 patients (14?±?4 years, 47% female) had at least 1 serum CK measured. Median (IQR) CK levels of patients prescribed (n?=?188 patients, 768 CK measurements) and not prescribed statins (n?=?351 patients, 682 CK measurements) were 107 (83) IU/L and 113 (81) IU/L, respectively. In multivariable-adjusted models, lnCK levels did not differ based on statin use (??=?0.02 [SE 0.05], P?=?.7). Among patients started on statins (n?=?86, 130 prestatin and 292 poststatin CK measurements), median CK levels did not differ in adjusted models (? for statin use on lnCK?=?.08 [SE .07], P?=?.2). There was a clinically insignificant increase in CK over time (??=?.08 [SE .04], P?=?.04 per year). No muscle symptoms or rhabdomyolysis were reported among patients with high CK levels. CONCLUSIONS: In a real-world practice, pediatric patients using statins did not experience higher CK levels, nor was there a meaningful CK increase with statin initiation. These data suggest the limited utility to checking CK in the absence of symptoms, supporting current guidelines.
Assuntos
Creatina Quinase/sangue , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Doenças Musculares/induzido quimicamente , Adolescente , Boston , Feminino , Humanos , Masculino , Análise Multivariada , Doenças Musculares/sangue , PediatriaRESUMO
OBJECTIVES: To test whether follow-up testing for very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency uncovers a diagnosis in patients with elevations of C14:1 and C14:2 plasma acylcarnitines after a controlled fasting study performed for clinically suspected hypoglycemia and to compare the acylcarnitine profiles from fasted patients without VLCAD deficiency vs patients with known VLCAD deficiency to determine whether metabolite testing distinguishes these groups. STUDY DESIGN: We performed a retrospective chart review and identified 17 patients with elevated C14:1 and C14:2 plasma acylcarnitine levels after a controlled fast and with testing for VLCAD deficiency (ACADVL sequencing or fibroblast fatty acid oxidation studies). The follow-up testing in all patients was inconsistent with a diagnosis of VLCAD deficiency. We compared the plasma acylcarnitine profiles from these fasted patients vs patients with VLCAD deficiency. RESULTS: C14:1/C12:1 was significantly lower (P < .001) in fasted patients vs patients with VLCAD deficiency. Metabolomics analysis performed in 2 fasted patients and 1 patient with VLCAD deficiency demonstrated evidence for up-regulated lipolysis and ß-oxidation in the fasted state. CONCLUSIONS: Elevations of plasma C14:1 and C14:2 acylcarnitines appear to be a physiologic result of lipolysis that occurs with fasting. Both metabolomics analysis and/or C14:1/C12:1 may distinguish C14:1 elevations from physiologic fasting-induced lipolysis vs VLCAD deficiency.
Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Carnitina/análogos & derivados , Jejum/sangue , Erros Inatos do Metabolismo Lipídico/sangue , Erros Inatos do Metabolismo Lipídico/diagnóstico , Doenças Mitocondriais/sangue , Doenças Mitocondriais/diagnóstico , Doenças Musculares/sangue , Doenças Musculares/diagnóstico , Acil-CoA Desidrogenase de Cadeia Longa/sangue , Adolescente , Carnitina/sangue , Criança , Pré-Escolar , Síndrome Congênita de Insuficiência da Medula Óssea , Feminino , Humanos , Lactente , Masculino , Estudos RetrospectivosRESUMO
INTRODUCTION: Understanding the consequences of cancer for energy metabolism is required in order to define strategies that both prevent and treat malnutrition. Carnitine is essential for lipid energy metabolism. The objective of this study was to assess presurgical plasma carnitine levels in cancer patients and their association with dietary intake, anthropometry, bioelectrical impedance, indirect calorimetry, plasma amino acid levels, and urinary carnitine and nitrogen values. METHODS: This was a prospective study in which two groups were randomly selected: one consisting of esophageal and gastric cancer patients (n = 24) and the other of healthy volunteers (control group, n = 12). RESULTS: Average plasma and urinary carnitine values ranged from 60 to 80 µM and 78 to 124 µM, respectively, in both groups, with no significant difference between them. Moreover, methionine and lysine levels, as well as resting energy expenditure, did not differ between cancer patients and controls. Plasma free carnitine levels, however, were significantly lower in cancer patients, 80 % (p < 0.05) of whom had deficient urinary carnitine excretion, insufficient dietary protein intake, and low body fat reserves. CONCLUSION: Although cancer patients had carnitine deficiency and lower carnitine stores, these did not affect resting energy expenditure, total food intake, or plasma lysine and methionine levels.
Assuntos
Biomarcadores/sangue , Cardiomiopatias/sangue , Carnitina/sangue , Carnitina/deficiência , Hiperamonemia/sangue , Desnutrição/sangue , Doenças Musculares/sangue , Neoplasias/sangue , Adolescente , Adulto , Cardiomiopatias/etiologia , Cardiomiopatias/patologia , Estudos de Casos e Controles , Feminino , Seguimentos , Voluntários Saudáveis , Humanos , Hiperamonemia/etiologia , Hiperamonemia/patologia , Masculino , Desnutrição/etiologia , Desnutrição/patologia , Pessoa de Meia-Idade , Doenças Musculares/etiologia , Doenças Musculares/patologia , Neoplasias/complicações , Neoplasias/patologia , Prognóstico , Estudos Prospectivos , Adulto JovemRESUMO
INTRODUCTION: HMG-CoA reductase inhibitors are the most frequently prescribed drugs for treatment of lipid imbalance, but they have side effects, such as myopathy. Our aim was to assess the effect of simvastatin on the inflammatory process induced by skeletal muscle injury. METHODS: Rats were divided into experimental groups [control group, simvastatin (20 mg/kg) group, group treated with simvastatin (20 mg/kg) and subjected to injury, and group subjected to injury only]. Histological analysis and analyses of creatine kinase activity and C-reactive protein were performed. RESULTS: Animals treated with simvastatin exhibited significantly greater morphological and structural skeletal muscle damage in comparison to the control group and injured animals without treatment. CONCLUSIONS: Although simvastatin has a small anti-inflammatory effect in the early stage after a muscle strain injury, the overall picture is negative, as simvastatin increases the extent of damage to muscle morphology. Further studies are needed.
Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Músculo Esquelético/patologia , Doenças Musculares/tratamento farmacológico , Doenças Musculares/etiologia , Sinvastatina/uso terapêutico , Estresse Mecânico , Análise de Variância , Animais , Proteína C-Reativa/metabolismo , Creatina Quinase/sangue , Modelos Animais de Doenças , Masculino , Músculo Esquelético/efeitos dos fármacos , Doenças Musculares/sangue , Ratos , Ratos WistarRESUMO
Genetic factors can interfere with sporting performance. The identification of genetic predisposition of soccer players brings important information to trainers and coaches for individual training loads adjustment. Different responses to eccentric training could be observed by the genotype referred to as α-actinin-3 (ACTN3) in biomarkers of muscle damage, hormones and inflammatory responses. The aim of this study was to compare acute inflammatory responses, muscle damage and hormonal variations according to the eccentric training in soccer professional athletes with different genetic profiles of ACTN3 (XX, RX and RR). 37 soccer professional athletes (9 XX, 13 RX, 15 RR) were randomly divided into five stations associated to eccentric muscle contraction and plyometrics. Blood samples were taken from athletes pre-eccentric training, immediately after (post), 2- and 4-h post-eccentric training to determine hormone responses (cortisol and testosterone), muscle damage (CK and α-actin), and inflammatory responses (IL-6). After eccentric training, athletes XX presented higher levels for CK (4-h post), α-actin (post and 2-h post) and cortisol (post) compared to RR and RX athletes. However, RR and RX athletes presented higher levels of testosterone (post) and IL-6 (2 h post and 4 h post) compared to athletes XX. The main conclusion of this study is that professional soccer athletes homozygous to ACTN3XX gene are more susceptible to eccentric damage and present a higher catabolic state, demonstrated by metabolic, hormonal and immune responses post an eccentric training, in comparison to ACTN3RR and ACTN3RX groups.
Assuntos
Actinina/genética , Desempenho Atlético , Contração Muscular , Músculo Esquelético/metabolismo , Exercício Pliométrico , Polimorfismo Genético , Futebol , Adulto , Análise de Variância , Biomarcadores/sangue , Brasil , Creatina Quinase/sangue , Predisposição Genética para Doença , Homozigoto , Humanos , Hidrocortisona/sangue , Mediadores da Inflamação/sangue , Interleucina-6/sangue , Masculino , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Doenças Musculares/sangue , Doenças Musculares/genética , Doenças Musculares/fisiopatologia , Fenótipo , Testosterona/sangue , Fatores de Tempo , Adulto JovemRESUMO
A neonate with elevated tetradecenoylcarnitine (C14:1) on the newborn screen was evaluated for possible very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and found to be a carrier. However, his symptom-free mother was subsequently diagnosed with VLCADD. This documents maternal VLCADD causing a positive newborn screening result in an offspring.
Assuntos
Triagem Neonatal/métodos , Acil-CoA Desidrogenase de Cadeia Longa/sangue , Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Carnitina/análogos & derivados , Carnitina/sangue , Síndrome Congênita de Insuficiência da Medula Óssea , Feminino , Genótipo , Humanos , Recém-Nascido , Erros Inatos do Metabolismo Lipídico , Masculino , Erros Inatos do Metabolismo/sangue , Erros Inatos do Metabolismo/diagnóstico , Doenças Mitocondriais/sangue , Doenças Mitocondriais/diagnóstico , Mães , Doenças Musculares/sangue , Doenças Musculares/diagnóstico , FenótipoRESUMO
Eccentric exercise induces muscle damage, but controversy exists concerning the effect of contraction velocity on the magnitude of muscle damage, and little is known about the effect of contraction velocity on the repeated-bout effect. This study examined slow (60 degrees.s(-1)) and fast (180 degrees.s(-1)) velocity eccentric exercises for changes in indirect markers of muscle damage following 3 exercise bouts that were performed every 2 weeks. Fifteen young men were divided into 2 groups based on the velocity of eccentric exercise: 7 in the Ecc60 (60 degrees.s(-1)) group, and 8 in the Ecc180 (180 degrees.s(-1)) group. The exercise consisted of 30 maximal eccentric contractions of the elbow flexors at each velocity, in which the elbow joint was forcibly extended from 60 degrees to 180 degrees (full extension) on an isokinetic dynamometer. Changes in maximal voluntary isometric contraction strength, range of motion, muscle soreness, and plasma creatine kinase activity before and for 4 days after the exercise were compared in the 2 groups using a mixed-model analysis (groupxboutxtime). No significant differences between groups were evident for changes in any variables following exercise bouts; however, the changes were significantly smaller (p<0.05) after the second and third bouts than after the first bout. These results indicate that the contraction velocity does not influence muscle damage or the repeated-bout effect.
Assuntos
Exercício Físico , Contração Isométrica , Músculo Esquelético/fisiopatologia , Doenças Musculares/etiologia , Adulto , Biomarcadores/sangue , Brasil , Creatina Quinase/sangue , Cotovelo , Articulação do Cotovelo/fisiopatologia , Humanos , Masculino , Força Muscular , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Doenças Musculares/sangue , Doenças Musculares/patologia , Doenças Musculares/fisiopatologia , Dor/etiologia , Amplitude de Movimento Articular , Fatores de Tempo , Adulto JovemRESUMO
OBJECTIVE: The aim of this study was to analyze biochemical markers as indicators of athletic performance, in light of a clinical context and athletic. METHODS: Samples of peripheral blood (8 mL) and urine (50 mL) were collected from 20 marathon athletes at rest and 15 minutes after half marathon. Following, examination of blood, urine and serum markers of renal function, muscle damage and lipidic profile was carried out. RESULTS: Statistical analysis of the results showed a significant increase (p < 0.05) in serum activity of the enzymes CK, CK-MM, CK-MB and LDH, serum creatinine and iron, leukocyte count and neutrophils. Furthermore, triglycerides, VLDL, uric acid in serum showed a significant decrease. CONCLUSION: This study shows that athletes of marathon show changes in biochemical parameters of blood and urine after competing in this modality, which demonstrates the importance of carrying out laboratory tests as diagnosis for silent biochemical disorders.
Assuntos
Biomarcadores/sangue , Biomarcadores/urina , Resistência Física/fisiologia , Corrida/fisiologia , Adulto , Humanos , Rim/fisiologia , Lipídeos/sangue , Masculino , Doenças Musculares/sangue , Descanso , Estatísticas não Paramétricas , Fatores de TempoRESUMO
OBJETIVO: O objetivo do presente estudo foi analisar marcadores bioquímicos como marcadores de desempenho atlético, à luz de um contexto clínico e atlético. MÉTODOS: Foram coletadas amostras de sangue periférico (8 mL) e de urina (50 mL) de 20 maratonistas profissionais em repouso e 15 minutos após meia maratona. Em seguida, realizaram-se hemograma, exame de urina e análise de marcadores bioquímicos de função renal, lesão muscular e lipidograma. RESULTADOS: A análise estatística dos resultados mostrou um aumento significativo (p < 0,05) na atividade sérica das enzimas CK, CK-MM, CK-MB e LDH; na concentração sérica de creatinina, ferro sérico, leucócitos e neutrófilos. Por outro lado, triglicérides, VLDL e ácido úrico sérico apresentaram um decréscimo significativo. CONCLUSÃO: O presente estudo mostra que os atletas analisados apresentam alterações nos parâmetros bioquímicos de sangue e urina após uma prova dessa modalidade, o que demonstra a importância da realização de exames laboratoriais como forma de diagnóstico de distúrbios bioquímicos silenciosos.
OBJECTIVE: The aim of this study was to analyze biochemical markers as indicators of athletic performance, in light of a clinical context and athletic. METHODS: Samples of peripheral blood (8 mL) and urine (50 mL) were collected from 20 marathon athletes at rest and 15 minutes after half marathon. Following, examination of blood, urine and serum markers of renal function, muscle damage and lipidic profile was carried out. RESULTS: Statistical analysis of the results showed a significant increase (p < 0.05) in serum activity of the enzymes CK, CK-MM, CK-MB and LDH, serum creatinine and iron, leukocyte count and neutrophils. Furthermore, triglycerides, VLDL, uric acid in serum showed a significant decrease. CONCLUSION: This study shows that athletes of marathon show changes in biochemical parameters of blood and urine after competing in this modality, which demonstrates the importance of carrying out laboratory tests as diagnosis for silent biochemical disorders.
Assuntos
Adulto , Humanos , Masculino , Biomarcadores/sangue , Biomarcadores/urina , Resistência Física/fisiologia , Corrida/fisiologia , Rim/fisiologia , Lipídeos/sangue , Doenças Musculares/sangue , Descanso , Estatísticas não Paramétricas , Fatores de TempoRESUMO
Antivenom therapy has been ineffective in neutralizing the severe local fast developing tissue damage following snakebite envenoming. Herein, some effects of in situ helium neon (HeNe) laser irradiation on rat nerve-muscle preparation injected with Bothrops jararacussu venom are described. The tibialis anterior muscle was injected with venom diluted in 0.9% saline solution (60 microg/0.02 mL) or saline solution alone. Sixty minutes after venom injection, laser (HeNe) treatment was administered at three incident energy densities: dose 1, a single exposure of 3.5 J cm(-2); dose 2, three exposures of 3.5 J cm(-2); dose 3, a single exposure of 10.5 J cm(-2). Muscle function was assessed through twitch tension recordings whereas muscle damage was evaluated through histopathologic analysis, morphometry of area of tissue affected and creatine kinase (CK) serum levels, and compared to unirradiated muscles. Laser application at the dose of 3.5 J cm(-2) reduced the area of injury by 64% (15.9 +/- 1.5%vs 44.2 +/- 5.7%), decreased the neuromuscular blockade (NMB) by 62% (11.5 +/- 2.5%vs 30.4 +/- 5.2%) and reduced CK levels by 58% (from 455 +/- 4.5% to 190.3 +/- 23.4%) when compared with unirradiated controls. Dose 2 showed a poorer benefit than dose 1, and dose 3 was ineffective in preventing the venom effects. Measurements of the absorbance of unirradiated and irradiated venom solution showed no difference in absorption spectra. In addition, no difference in the intensity of partial NMB in nerve-muscle preparation was shown by unirradiated and irradiated venom. The results indicate that the laser light did not alter venom toxicity. We conclude that HeNe laser irradiation at a dosage of 3.5 J cm(-2) effectively reduces myonecrosis and the neuromuscular transmission blocking effect caused by B. jararacussu snake venom. Thus, low level laser therapy may be a promising tool to minimize the severity of some of the local effects of snake envenoming.
Assuntos
Terapia com Luz de Baixa Intensidade/métodos , Doenças Musculares/radioterapia , Venenos de Serpentes/farmacologia , Animais , Bothrops , Masculino , Doenças Musculares/sangue , Doenças Musculares/enzimologia , Doenças Musculares/patologia , Ratos , Ratos WistarRESUMO
We report a case of severe hypomagnesemia in non-oliguric acute renal failure caused by leptospirosis that required large doses of magnesium replacement during the acute phase of disease. Biochemical studies confirmed kidney-related magnesium wasting and the mechanisms of this defect are discussed. Magnesium imbalance with its attendant clinical complications occurs in leptospirosis and should be monitored and treated aggressively in cases of leptospirosis-induced non-oliguric acute kidney injury.
Assuntos
Leptospirose/complicações , Deficiência de Magnésio/sangue , Deficiência de Magnésio/complicações , Adolescente , Feminino , Humanos , Leptospirose/tratamento farmacológico , Deficiência de Magnésio/tratamento farmacológico , Sulfato de Magnésio/uso terapêutico , Doenças Musculares/sangue , Doenças Musculares/complicações , Fragilidade Osmótica , Penicilina G/uso terapêutico , PotássioRESUMO
The effects of 0.5%, 0.3% and 0.1% w/w concentrations of Senna occidentalis (So) seed mixed with commercial ration were studied in 18 groups of 32 broiler chicks each, from 1 day to 49 days of age. Three groups were fed one of the rations throughout their lives (TL). Three other groups were fed one of the rations from the 1st to the 28th day of life (starter phase, SP), and the final 3 groups were fed one of the rations from the 29th to 49th day (finisher phase, FP). Each experimental group was matched by a control group fed the same diet over the same period but without the inclusion of So. All the animals were killed at 49 days of age, and blood was collected from 10 birds in each group for biochemical studies (ALT, AST, GGT, LDH, UA). A complete necropsy was performed on 3 birds from each group. No significant differences in the biochemical parameters in the serum were found between the control and experimental chicks, but animals treated with 0.5% So in groups FP and TL, gained less weight and chicks that received 0.3% So or 0.5% So in the ration throughout life (TL) had a larger feed conversion ratio. Besides this, degenerative changes were found in the striated skeletal muscle in the chest, in the myocardium and in the liver in the animals that received the higher concentrations of So seeds.
Assuntos
Galinhas , Plantas Tóxicas/toxicidade , Doenças das Aves Domésticas/induzido quimicamente , Sementes/química , Senna/química , Animais , Relação Dose-Resposta a Droga , Fígado/efeitos dos fármacos , Fígado/patologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/patologia , Doenças Musculares/sangue , Doenças Musculares/induzido quimicamente , Doenças Musculares/patologia , Doenças das Aves Domésticas/sangue , Doenças das Aves Domésticas/patologia , Aumento de Peso/efeitos dos fármacosRESUMO
Uracoan rattlesnake (Crotalus vegrandis) venom was subjected to chromatographic, electrophoretic, biochemical and in vivo haemorrhagic analysis. A haemorrhagic toxin (Uracoina-1) active on skin at the site of inoculation in mice was purified by Mono Q2 anion-exchange chromatography and size exclusion (SE) high-performance liquid chromatography. The purified preparation was a protein of M(r) 58,000 as revealed by sodium dodecyl sulphate--polyacrylamide gel electrophoresis under denatured conditions and with silver staining. The use of EDTA, EGTA and 1,10-phenanthroline inhibited haemorrhagic and proteolytic activities. Inhibitors of serine proteinases such as PMSF and TCLK had no effect on the haemorrhagic fraction. Uracoina-1 hydrolyses casein, hide powder azure and fibrinogen have an optimal pH of 8.2. It rapidly digests the A alpha-chain of fibrinogen. Thermal denaturation of Uracoina-1 after exposure at 60 degrees C for 15 min led to inactivation of the haemorrhagic activity. In addition, Uracoina-1 is myotoxic, lacking haemolytic, defibrinating and lethal effects. The N-terminal amino acid sequence (20 residues) was determined.
Assuntos
Venenos de Crotalídeos/química , Venenos de Crotalídeos/isolamento & purificação , Proteínas/isolamento & purificação , Viperidae , Sequência de Aminoácidos , Animais , Fracionamento Químico , Cromatografia por Troca Iônica , Creatina Quinase/sangue , Venenos de Crotalídeos/antagonistas & inibidores , Venenos de Crotalídeos/farmacologia , Venenos de Crotalídeos/toxicidade , Crotalus , Eletroforese em Gel de Poliacrilamida , Inibidores Enzimáticos/farmacologia , Hemorragia/induzido quimicamente , Concentração de Íons de Hidrogênio , Injeções Intradérmicas , Injeções Intramusculares , Masculino , Camundongos , Dados de Sequência Molecular , Doenças Musculares/sangue , Doenças Musculares/induzido quimicamente , Proteínas/antagonistas & inibidores , Proteínas/farmacologia , Pele/efeitos dos fármacosAssuntos
Síndrome da Imunodeficiência Adquirida/complicações , Doenças Musculares/etiologia , Zidovudina/uso terapêutico , Síndrome da Imunodeficiência Adquirida/sangue , Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Pré-Escolar , Creatina Quinase/sangue , Feminino , Humanos , Assistência de Longa Duração , Doenças Musculares/sangue , Zidovudina/efeitos adversosRESUMO
The authors describe a family (mother, son and two daughters) with mitochondrial myopathy. The mother was asymptomatic. Two daughters had lactic acidosis and myoclonic epilepsy, mild dementia, ataxia, weakness and sensory neuropathy. The son suffered one acute hemiplegic episode due to an ischemic infarct in the right temporal region. All the patients studied had hypertension. EEG disclosed photomyoclonic response in the proband patient. Muscle biopsy disclosed ragged-red fibers and abnormal mitochondria by electron microscopy. Biochemical analysis showed a defect of cytochrome C oxidase in mitochondria isolated from skeletal muscle. Several clinical and genetic aspects of the mitochondrial encephalomyopathies are discussed.