线粒体肌病与线粒体脑肌病的酶组织化学和超微结构改变

目的：探讨原发性线粒体肌病与脑肌病的病理特征及临床特点。方法：对11例原发性线粒体肌病与脑肌病患者的临床表现，酶组织化学及超微结构进行分析，结果：11例MGT染色均发现有不整红边纤维（RRF），其中单纯表现为肌无力的患者7例，合并中构神经系统受累者4例，RRF出现比例为6．4％－10．3％，电镜观察11例，9例表现为线粒体数目增多，形态异常，嵴排列紊乱等。均可见线粒体内类结晶状包涵体。2例线粒体改变只见数量增多，未见其他异常。结论：光镜下酶组化染色发现典型RRF，对线粒体肌病与脑肌病的初步论断有重要价值。电镜观察肌膜下线粒体异常增多且形态异常，特别是线粒体内类结晶状包涵体的出现，对本病的确诊有重要意义。     

MELAS型线粒体脑肌病伴糖尿病1例报告

本文报告一例36岁男患,临床表现为类脑卒中样发作,智能、听力低下,头痛,言语障碍,肌阵挛发作等。血液与CSF丙酮酸、乳酸含量明显增高。血、尿、CSF糖含量明显增高。头部CT见左颞叶低密度区及脑萎缩。肌肉组化检查见RRF、CCO染色阴性纤维,电镜见巨大线粒体及类结晶样包涵体。诊断MELAS型线粒体脑肌病伴糖尿病。     

线粒体脑肌病的临床、病理与神经电生理

目的探讨线粒体脑肌病的临床、肌肉病理及神经电生理特点，以便早期诊断。方法对6例确诊的线粒体脑肌病患者的临床表现、肌肉组织光镜和超微结构改变以及神经电生理改变进行了回顾性分析。结果本组患者的临床特征主要以运动不耐受，阵挛、抽搐发作，精神障碍，共济失调为主。6例患者中4例发现破碎红纤维（RRF），其平均比例为5．3％；超微结构观察有线粒体异常及糖原颗粒沉积，其中有2例发现有典型晶格状包涵体。以癫痫发作为主要临床表现的患者脑电图明显异常；肌电图以神经源性改变4例，占本组病例的4／6；听觉诱发电位（BAEP）、体感诱发电位（SEP）异常3例，占3／6。结论线粒体脑肌病的临床表现复杂多样，诊断主要依赖于临床特征分析和肌肉活检；电镜超微结构改变为线粒体病的主要诊断依据；神经电生理改变对病理损伤累及范围和程度方面有一定的参考价值。     

线粒体脑肌病的临床、病理及影像学特点

目的探讨线粒体脑肌病(ME)的临床、病理及影像学特点。方法回顾性分析20例ME患者的临床资料。结果本组中,慢性进行性眼外肌麻痹(CPEO)7例;肌阵挛性癫痫伴破碎红纤维(MERRF)6例;线粒体脑肌病伴乳酸中毒以及卒中样发作(MELAS)5例;Leigh综合征(LS)2例。临床表现为眼睑下垂7例(35%),肢体无力12例(60%),癫痫10例(50%),卒中样发作5例(25%)和精神智能障碍9例(45%)。8例患者血肌酸激酶升高;7例患者行血乳酸水平检查,均不同程度增高。EMG显示肌源性损害8例,神经源性损害4例,周围神经损害2例,正常6例。头颅MRI表现为脑萎缩、脑白质变性和不符合血管分布的卒中样改变。骨骼肌病理可见破碎红纤维(RRF)和SDH染色肌间小血管强染(SSV);细胞色素C氧化酶(COX)酶活性减低或缺失。电镜下线粒体结构和/或数量异常。结论 ME临床表现复杂多样,多有骨骼肌和脑受累。RRF和SSV是ME主要病理表现。     

线粒体肌病和线粒体脑肌病组织化学及电镜的研究

本文报告了2例线粒体肌病、3例线粒体脑肌病(MALES1例、MER-RF2例)。所有病例的速冻连续切片的GT染色均见有RRF。在HE—NADH—TR、ATP酶、PAS、、磷酸化酶及SND染色中均见有RRF样增强纤维。细胞色素C氧化酶染色中有2例的切片出现阴性染色肌纤维、考虑为复合体Ⅳ活性低下,余3例染色正常。电镜下观察到除有大量形态异常的线粒体外,并在这些线粒体内见有结晶状、板层状及同心圆样的包涵体。     

线粒体肌病与脑肌病的神经心理学特征

线粒体肌病和脑肌病的骨骼肌活检均有线粒体形态异常。用琥珀酸脱氢酶染色后,4％以上的肌纤维外周出现线粒体聚集,称线粒体肌病;累及中枢神经系统的谓之线粒体脑肌病。脑肌病综合征包括:(1)眼肌麻痹、视网膜病变和心脏传导阻滞的Kearns—Sayre综合征;(2)伴有蓬毛样红纤维(RRF)的肌阵挛癫痫;(3)线粒体脑病,乳酸酸中毒和卒中样发作(MELAS)。神经心理学检查的目的,在于确定     

青年脑出血与线粒体脑肌病的关系

目的 研究青年脑出血与线粒体脑肌病(MEM)的关系。方法 对4例与线粒体脑肌病有关的青年脑出血患者的肌活检标本进行电镜观察、Gomori组化染色、血乳酸测定及肌电图检测。结果 4例青年脑出血患者的肌活检标本均可见不整红边纤维(RRF)，血乳酸值增高，线粒体形态异常。结论 提示部分青年脑出血患者发病与MEM有关。     

硒蛋白-P在线粒体疾病患者不整红边纤维中的特异表达及相关作用

目的研究硒蛋白P与琥珀酸脱氢酶、细胞色素C氧化酶的关系及它们在线粒体疾病患者不整红边纤维(raggedredfiber,RRF)中的表现和作用。方法(1)研究对象:线粒体疾病患者14例,其中Kearns Sayre综合征患者1例,线粒体脑肌病、乳酸酸中毒伴卒中样症状者4例,肌阵挛癫伴RRF1例,慢性进行性眼外肌麻痹6例,肢带型线粒体病2例;5例对照,其中多发性肌炎2例,其他神经肌病3例。全部患者均经临床、病理、分子生物学DNA分析确诊。(2)开放式肌肉活检。(3)连续切片,经组织化学、免疫组织化学染色分析。结果患者RRF的肌浆中硒蛋白-P显著表达,琥珀酸脱氢酶活性增强,细胞色素C氧化酶活性增强、减弱或缺陷。结论硒蛋白-P在对抗线粒体氧化损伤、保护线粒体机能方面可能充当了重要角色,可以作为病理学评价线粒体机能和诊断RRF的指标。     

16例MELAS临床、神经影像与肌肉病理研究

目的探讨线粒体脑肌病并乳酸血症与卒中样发作(MELAS)的临床、影像学及肌肉病理特点。方法对16例MELAS患者的临床表现、影像学及肌肉病理特点进行分析。结果患者主要临床表现为卒中样癫发作(87.5%),其次为头痛、呕吐和智能减退等;头颅MRI提示脑实质片状异常信号,不按血管供应区分布;肌肉活检见破碎红纤维(RRF)。结论MELAS是一种具有特殊临床、影像学表现的线粒体脑肌病,其诊断依赖于肌肉活检病理和基因诊断。     

线粒体脑肌病伴高乳酸血症和卒中样发作综合征的肌肉病理和电镜特征

目的探讨线粒体脑肌病伴高乳酸血症和卒中样发作(MELAS)综合征的肌肉病理和电镜特征。方法收集2013年1月-2019年1月郑州大学第五附属医院和郑州大学第一附属医院经肌肉病理和基因测序同时确诊的33例MELAS综合征的资料,对他们肌肉病理和电镜结果进行回顾性分析。结果光镜下25例改良Gomori染色可见破碎红纤维; 28例SDH染色可见破碎蓝纤维,氧化酶活性明显增高; 26例可见肌间小动脉血管壁深染(strongly succinatedehydrogenase-reactive,SSV),即SSV现象,其中2例未见到破碎蓝纤维和破碎红纤维; 22例COX染色光镜下见到氧化酶活性消失或减低,即COX阴性肌纤维。15例患者行电镜检查,均可见到线粒体的数量和结构异常,线粒体内结晶样包涵体呈"停车场"样排列。结论破碎红纤维(RRF)、SSV现象和COX阴性肌纤维是MELAS综合征主要的肌肉活检病理改变;线粒体内结晶样包涵体呈"停车场"样排列是MELAS综合征电镜的典型改变,这些特征对MELAS综合征的诊断具有十分重要的价值。     

A study of mitochondrial electron transfer chain in myotonic dystrophy

Ragged-red fibers (RRFs) are mainly seen in mitochondrial myopathy and related to biochemical defects in electron transfer chain on some occasions. Recently, some papers reported the occurrence of RRFs in the biopsied muscle of myotonic dystrophy (MyD). To examine whether the mitochondrial function is disturbed in MyD, we have studied the biopsied muscles of 12 cases with MyD (10 males and 2 females averaging 38 years of age) morphologically and mainly biochemically. RRFs, ranging from 2--20% of the muscle fibers, were identified in 5 out of 12 cases. On electron microscopy, these fibers had aggregated abnormally enlarged mitochondria with dene bodies, concentrically whirled membranous cristae and paracrystalline inclusions. Clinically, 4 of 5 cases with RRFs had mild to moderate and only 2 of 7 without RRFs had ophthalmoplegia. Bicycle ergometer exercise test showed abnormal increase of lactate/pyruvate ratio in three cases with RRFs. Histochemically, cytochrome c oxidase (CCO) activity was absent selectively in all of the RRFs. Immunohistochemical staining showed the presence of CCO protein by using monoclonal antibody which was specific to CCO subunit IV. Biochemical study with crude muscle extract of 11 cases of MyD showed decreases in NADH dehydrogenase, NADH CoQ reductase, succinate CoQ reductase (SCR), CCO, carnitine actyl transferase activities in most of cases regardless RRFs. To avoid the influence possibly derived from the various stages of muscle degeneration in the biopsied specimens, we calculated the ratio of the enzyme activities compared with succinate dehydrogenase which was located in the electron transfer chain and did not show any statistical difference regardless of RRFs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnosis of mitochondrial diseases: clinical and histological study of sixty patients with ragged red fibers

BACKGROUND: Mitochondrial diseases are caused by mutations in mitochondrial or nuclear genes, or both and most patients do not present with easily recognizable disorders. The characteristic morphologic change in muscle biopsy, ragged-red fibers (RRFs) provides an important clue to the diagnosis. MATERIALS AND METHODS: Demographic data, presenting symptoms, neurological features, and investigative findings in 60 patients with ragged-red fibers (RRFs) on muscle biopsy, seen between January 1990 and December 2002, were analyzed. The authors applied the modified respiratory chain (RC) diagnostic criteria retrospectively to determine the number of cases fulfilling the diagnostic criteria of mitochondrial disease. RESULTS: The most common clinical syndrome associated with RRFs on muscle biopsy was progressive external ophthalmoplegia (PEO) with or without other signs, in 38 (63%) patients. Twenty-six patients (43%) had only external ophthalmoplegia, 5 (8%) patients presented with encephalomyopathy. Specific syndromes were the presenting feature in 8 (13%), Kearns-Sayre syndrome (KSS) in 4 and myoclonus epilepsy with ragged-red fibers (MERRF) in 4. Myopathy was the presenting feature in 5 (8%) and 4 presented with infantile myopathy. Of the 60 patients, 18 (30%) had proximal muscle weakness. Two patients with KSS and one patient with myopathy had complete heart block necessitating pace making. When the modified RC diagnostic criteria were applied, only 26 (43%) patients had one other major criterion in addition to RRFs for the diagnosis of mitochondrial diseases. The remaining 34 (57%) patients with RRFs on muscle biopsy had only some clinical features suggestive of RC disorder but did not fulfill the clinical criteria (of the modified diagnostic criteria) for the diagnosis of mitochondrial diseases. CONCLUSION: In patients with clinical features suggestive of RC disorder, demonstration of RRFs on muscle biopsy helps in confirming the diagnosis of mitochondrial disease in only a subgroup of patients.     

Cytochrome c oxidase activity is deficient in blood vessels of patients with myoclonus epilepsy with ragged-red fibers

Summary More than half of the intramuscular blood vessels in muscle biopsies from five patients with myoclonus epilepsy with ragged-fibers (MERRF) who had a point mutation in mitochondrial DNA at the tRNA^Lys region were darkly stained with succinate dehydrogenase (SDH) stain, showing the morphologic characteristics of strongly SDH-reactive blood vessels (SSV), but they had no cytochrome c oxidase (CCO) activity. By electron cytochemistry, the mitochondria in the smooth muscle cells of SSV had no CCO activity. On the other hand, SSV in muscle biopsies from patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) had normal CCO activity as shown by light and electron microscopy. The defect in CCO activity in the arteriolar smooth muscle cells and in muscle fibers suggests that CCO deficiency is related to the pathophysiology of MERRF.     

Peripheral neuropathy in two children with mitochondrial encephalomyopathy]

Peripheral neuropathy (PN) associated with mitochondrial encephalomyopathy (MEM) has been reported in adult patients, while children with both conditions are rare. Electrophysiological and pathological studies disclosed evidence of PN in a 3-year-old girl and an 8-year-old boy with MEM. In both patients, peripheral nerve conduction velocities were reduced, while amplitudes of evoked potentials were normal. No ragged red fibers were found in the biopsy muscle, while most of the muscle fibers showed poor activity with histochemical staining for cytochrome c oxidase (CCO). Biochemical studies revealed deficiency of CCO in both cases. In the latter patient, CCO activity was also absent in the intramuscular peripheral nerve using CCO staining, and histopathological studies of the sural nerve revealed a marked decrease in the number of large myelinated fibers and an unusual accumulation of the mitochondria in the Schwann cell cytoplasm. These results may support the hypothesis that a common pathogenesis exists in both peripheral nerve and muscle due to mitochondrial dysfunction.     

Autopsied case with MERRF/MELAS overlap syndrome accompanied by stroke‐like episodes localized to the precentral gyrus

We present an autopsied case with A8344G‐mutated myoclonus epilepsy with ragged red fibers (MERRF)/mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes (MELAS) overlap syndrome accompanied by stroke‐like episodes localized to the precentral gyrus. A 16‐year‐old Japanese woman suddenly experienced repetitive consciousness disturbances with increased serum lactate and creatine kinase levels. Magnetic resonance imaging showed abnormal intensity of bilateral precentral gyrus. She was clinically diagnosed as having a mitochondrial disorder and the A8344G mutation was detected in mitochondrial DNA. At 17 years of age, she died from congestive heart failure secondary to a third episode of lactic acidosis. Neuropatho‐logically, multifocal laminar necrosis, which is responsible for stroke‐like episodes in MELAS, was seen in the frontal cortex including the precentral gyrus, but there was no neuronal loss and gliosis in the basal ganglia, cerebellum, and brainstem, which were compatible with MERRF. Hypertrophy of the vascular smooth muscle and choroidal epithelium were seen, and were strongly visualized by an anti‐mitochondrial antibody. Skeletal muscles showed uneven muscular diameters, increased central nuclei, and ragged red fibers (RRFs). Decreased cytochrome c oxidase (COX) activity and strongly succinate dehydrogenase (SDH)‐reactive blood vessels were also noted. Stroke‐like episodes in MERRF/MELAS overlap syndrome are thought to be rare in the frontal cortex including the precentral gyrus. Only two cases of MERRF/MELAS overlap syndrome with A8344G mutation, including this case, have shown stroke‐like episodes in the frontal lobes. Other than the A8344G mutation and frontal lobe involvement, they had a high degree of similarity in terms of presence of RRFs, gastrointestinal dysfunction, and lack of typical MERRF neuropathology. In conclusion, this is an important case describing the clinical spectrum associated with A8344G‐mutated MERRF/MELAS overlap syndrome.     

A mitochondrial encephalomyopathy with cardiomyopathy. A case revealing a defect of complex I in the respiratory chain

We describe a 16-year-old Japanese girl with a mitochondrial encephalomyopathy who presented with progressive dementia, limb weakness and atrophy, episodic vomiting, generalized convulsions, myoclonic seizures, and hypertrophic cardiomyopathy. CT scan revealed transient focal low density areas in her occipital and parietal lobes, and cerebellar atrophy. The clinical features were consistent with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Microscopically, most of muscle fibers in the skeletal muscles and heart were occupied by markedly increased mitochondria. Polarographic studies on mitochondria isolated from postmortem heart muscle showed severe impairment of oxidation of NADH-linked substrates in contrast to normal succinate oxidation. The rotenone-sensitive NADH-coenzyme Q reductase activity was markedly decreased in heart, skeletal muscle and liver mitochondria. The biochemical investigations have led to the identification of a defect of complex I in the respiratory chain. Reported cases of a defect of complex I have revealed pure myopathy, encephalopathy or encephalomyopathy. The reason for a varied clinical expression of a single defect remains to be clarified.     

Mitochondrial myopathy of cerebro-hepato-renal (Zellweger) syndrome

The muscles of four infants with cerebro-hepato-renal (Zellweger) syndrome were studied during life and/or at necropsy. A mitochondrial myopathy was demonstrated, similar to mitochondrial alterations demonstrated in liver and brain in this disease. Muscle fibers with red-staining subsarcolemmal aggregates were identified with Gomori trichrome stain in two cases. Subsarcolemmal and intermyofibrillar zones of increased concentrations of NADH-TR, SDH, and cytochrome-c-oxidase activity were demonstrated histochemically in all four cases. Degenerative and cytoarchitectural changes in muscle fibers were not found. Ultrastructural studies showed large aggregates of mitochondria and increased lipid in the subsarcolemmal and intermyofibrillar spaces. Degenerative changes in mitochondria and lipid also were demonstrated, but paracrystalline inclusions were not seen. The distribution of these changes was not uniform between patients or between different muscles in the same patient. The diaphragm was affected more severely than proximal or distal muscles of the extremities. Direct involvement of muscle mitochondria in this disease may interfere with energy metabolism and contribute to the clinical findings of hypotonia, weakness, and respiratory insufficiency. The muscle biopsy with histochemistry and electron microscopy may be used as a diagnostic adjunct in suspected cases, but the variation encountered dictates dictates caution in the interpretation of negative findings.     

Mitochondrial encephalomyopathy (focal cytochrome c oxidase deficiency) with transient episodes of muscle weakness and elevation of serum creatine kinase activity

A 17-year-old boy who had mitochondrial encephalomyopathy with focal deficiency of cytochrome c oxidase (CCO) activity is described. He experienced 3 episodes of muscle weakness, fatigability, nausea, vomiting and concomitant increase of serum creatine kinase activity, at the age of 13, 15 and 17 years. During interval there was no muscle weakness and the serum creatine kinase activity was within normal range. Increased levels of lactic acid and pyruvic acid were observed in the blood and cerebrospinal fluid. After an aerobic exercise test, lactic acid and pyruvic acid in the blood increased to an abnormally high level, and the arterial blood became acidic (pH 7.297). On EEG, occasional intermittent irregular theta activities were observed in the anterior region, but there were no abnormalities on CT and MRI in the central nervous system. In the biopsied muscle, ragged-red fibers comprised 20% on modified Gomori-trichrome staining and a number of fibers with no CCO activity were scattered throughout. The CCO activity in the mitochondria isolated from the biopsied muscle was reduced to 49.2 nmol/min/mg protein (normal range 144.7-355.8), while other mitochondrial enzyme activities in the electron transport system were normal. From these data, the patient was considered to have a unique form of mitochondrial encephalomyopathy. By the administration of a large amount of coenzyme Q10, episodes of muscle weakness and nausea, and an increase of lactic acid and pyruvic acid in the blood after aerobic exercise test were no longer observed.