Two childhood myopathies with abnormal mitochondria. I. Megaconial myopathy. II. Pleoconial myopathy

Analytical subcellular fractionation of normal human skeletal muscle by sucrose density gradient centrifugation

The principle organelle marker enzymes and various adenosine triphosphatase (ATPase) activities were studied in human skeletal muscle. The reproducibility of each assay was established under optimal and linear assay conditions. Whole homogenates of normal human quadriceps muscle were fractionated by centrifugation on a continuous sucrose density gradient. Gradient fractions were assayed for organelle marker enzymes and frequency-density histograms were constructed for each enzyme. Good resolution of the principal organelles was obtained. Adenosine triphosphatase (ATPase) was assayed under conditions of maximal stimulation by Ca2+, or Mg2+ or Na2+, K+ + Mg2+. The distribution of these activities was compared with those of the organelle marker enzymes. Both Ca2+-ATPase and Mg2+-ATPase were distributed to both the mitochondrial and myofibrillar fractions but could be distinguished by the inhibition of mitochondrial ATPase with sodium azide. The distribution of Na+, K+-activated, Mg2+-dependent ATPase (Na+, K+ ATPase) activity suggested a sarcolemmal localization. The results of electron microscopy of gradient fractions were consistent with the organelle content of the fractions as determined by enzymic analyses. These studies provide reference information for the subsequent investigation of organelle pathology of human muscle disorders.

A clinico-pathological study of chronic hereditary motor neuropathy

Forty cases of chronic hereditary motor neuropathy (CHMN) were divided into five categories according to the distribution of muscle atrophy; they were proximal, facioscapulohumeral, bulbospinal, distal and scapuloperoneal forms. Their clinical features and laboratory data were analysed, and muscle biopsies from 32 of them were studied by histological, histochemical and electron microscopical methods. An attempt at quantitative assessment of the histological changes was also made. All muscle biopsies showed a mixture of neurogenic and 'myopathic' changes in varying proportions. They showed more 'myopathic' changes than Werdnig-Hoffmann's disease, amyotrophic lateral sclerosis and other neurogenic atrophies except Charcot-Marie-Tooth disease. There was marked variation in the average number of atrophied muscle fibers contained in grouped atrophy. Frequently, deranged internal structure of the muscle fibres was revealed both by histochemical and electron microscopical methods. Based on the evidence of heterogeneity of CHMN in respect of genetics, clinical features and histological changes, it was speculated that CHMN represents a group of diseases which involves primarily different parts of the motor units.

"Mitochondrial myopathy" or mitochondrial disease? EEG, ERG, VEP studies in 13 children

Neurophysiological investigations (EEG, ERG, VEP) were carried out in 13 patients with proven "mitochondrial myopathy". There were nine girls and four boys. Varied abnormalities were seen in the EEGs of all cases, and in one patient unusual repetitive bursts of irregular slow waves and spikes were observed. The ERG was abnormal in five of the 12 cases tested, while the VEP (flash) was definitely abnormal in six out of these 12 cases. These neurophysiological findings suggest some involvement of both the brain and the visual system. It seem therefore appropriate that this condition be considered a "mitochondrial disease" affecting many systems rather than only muscles.

Metabolic tapetoretinal degenerations

There are a number of metabolic diseases which cause tapetoretinal degeneration, suggesting that pure pigmentary retinopathy may also be metabolic in nature. On the other hand tapetoretinal degenerations may have various modes of inheritance, so we may conclude that the metabolic disorder at the basis of these diseases is not unique and that tapetoretinal degenerations are heterogenic. In this article, some 450 published reports on tapetoretinal degenerations are reviewed. Based on these reports, the clinical and ocular manifestations, laboratory and histopathological findings, inheritance patterns, and treatments of various syndromes characterized by tapetoretinal degenerations are described. It is hoped that the gathering together of this information in one source will acid in the future understanding of metabolically based eye disease.

Ca2+-uptake properties of two populations of mitochondria from normal and denervated rat soleus muscle

Ultraturrax- and Nagarse-released populations of mitochondria were characterized with respect to their Ca2+-uptake activities (i) by means of the indirect polarographic technique and (ii) directly by the 45Ca Ruthenium Red-quench method of Reed & Bygrave [(1974) Biochem. J. 140, 143-155]. The denervated-muscle subsarcolemmal and intermyofibrillar mitochondrial fractions displayed markedly decreased rates and capacities for Ca2+ uptake compared with their respective controls. The implications of these findings with respect to the process of cell necrosis are discussed.

Ophthalmoplegia-plus

The occurrence of chronic progressive external ophthalmoplegia, pigmentary retinal dystrophy and cardiac disturbances associated with arachnodactily, sternal deformity, high arched palate and severe myopia is reported. A pedigree analysis of this Jewish-Iranian family strongly suggests that the condition is inherited as autosomal recessive trait. The terminology of the condition and the spectrum of it variable phenotypic expression is described.

Biochemical functioning of mitochondria in normal and denervated mammalian skeletal muscle

Mitochondrial preparations derived from denervated rat skeletal muscle and paired control muscle are characterized with respect to their oxidative and phosphorylative capacities. Our data indicate that there is an impairment within the first 2 energy coupling regions of the respiratory chain and within the ATPase complex itself.

Mitochondrial cytopathy. A multisystem disorder with ragged red fibres on muscle biopsy

Thirteen children with abnormal mitochondria in muscle tissue, and a progressive neurological disorder that affected the cerebrum, cerebellum, extrapyramidal system, vestibular system, retina, upper motor neuron, lower motor neuron, and musculature, are reported. Other signs and symptoms were short stature, diabetes mellitus, cardiopathy, hypoplastic anaemia, glomerulopathy, and renal tubular dysfunction. These symptoms may occur singly or in various combinations and the manifestation may differ even within the same family. The most common clinical picture was that of "ophthalmoplegia plus'. Occurrence in relatives varied from isolated symptoms to the complete syndrome with "ragged red fibres' and is not inconsistent with an autosomal dominant mode of inheritance with variable expressivity. Theories for the pathophysiological basis of this syndrome are discussed and the literature reviewed.

Mitochondrial myopathy

Six clinically affected and 18 asymptomatic members of a six-generation family were investigated clinically, by estimation of serum CK levels, and in some cases by quantitative electromyographic techniques and muscle biopsy. It was concluded that the myopathy was probably inherited as an autosomal dominant trait with variable expression and incomplete penetrance although the possibility of mitochondrial inheritance could not be excluded in view of the almost exclusive transmission through the female line. Eight members of the family with myopathy also had diabetes mellitus, and 2 of these also had cerebellar ataxia. It is suggested that the myopathy, the cerebellar disorder and the diabetes may all be manifestations of the same underlying metabolic defect.

Ophthalmoplegia and ptosis in congenital fiber type disproportion

Bilateral ophthalmoplegia and ptosis is reported for the first time in a patient with a rare neuromuscular disorder, congenital fiber type disproportion (CFTD). The importance of limb muscle biopsy in the diagnostic evaluation is emphasized. A summary is presented of other congenital neuromuscular diseases which may have associated ophthalmoplegia.

Congenital neuromuscular disorder with predominant mitochondrial changes in type II muscle fibers

The muscle biopsy of a young boy presenting a marked hypotrophy of stature and weight, proximal muscle weakness, uncertain gait, and partial hearing loss, showed an abnormal distribution of the mitochondrial activities in type II muscle fibers by histochemical methods. Electron microscopy confirmed the presence of giant mitochondria in these muscle fibers, and at a lesser degree in some type I fibers. These findings contrast with the usual type I predominance of the mitochondrial changes in the different "mitochondrial" myopathies.

Large mitochondria in a pituitary adenoma with hyperprolactinemia

A 27-year-old woman with amenorrhea following cessation of birth control pills was found to have a pituitary tumor which was secreting large amounts of prolactin. Many tumor cells had large mitochondria, the diameter of which ranged between 7 and 12 mu. Some tumor cells also displayed oncocytic transformation, and a few were definite oncocytes. The pathogenesis of mitochondrial swelling in pituitary tumors is discussed and the possible roles of prolonged intake of steroids and/or ischemia are suggested.

Myoclonus epilepsy associated with ragged-red fibres (mitochondrial abnormalities ): disease entity or a syndrome? Light-and electron-microscopic studies of two cases and review of literature

A report is given of an association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in 2 patients. They had suffered from gradually increasing bursts of myoclonus since the wage of 14 and childhood, respectively. The other striking clinical features included generalized convulsions, mental deterioration, intention tremor, ataxia, muscular atrophy and deformity of feet. Muscle biopsies revealed ragged-red fibres in both cases. On electron microscopy these fibres contained subsarcolemnal aggregations of abundant abnormal mitochondria with proliferation of inner membranes or paracrystalline inclusions. One of these patients showed elevated blood lactate and pyruvate with an increased lactate/pyruvate ration, apparently of primary origin. These 2 cases resemble those reported briefly by Tsairis et al. (1974). An association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in these 2 patients is unlikely to be coincidental but may represent one nosological entity. This myoclonus epilepsy syndrome associated with ragged-red fibres is compared with other possibly related mitochondrial encephalomyopathies.

Neuropathy and mitochondrial myopathy

It has been stated that peripheral neuropathy can be a feature of so-called ophthalmoplegia-plus syndrome, but to date only one case of hypertrophic neuropathy has been reported. This study is concerned with the clinical, electrophysiological, and pathological observations in a 37-year-old man with progressive external ophthalmoplegia and a ragged-red fiber myopathy associated with severe sensorimotor neuropathy. Histological and morphometric studies of the sural nerve revealed a marked loss of large myelinated fibers and an occasional degenerating axon. Residual fibers had disproportionately thin myelin sheaths in relation to axon calibers. In contrast to the muscle biopsy findings, no mitochondrial paracrystalline inclusions were observed in the nerve. However, the number of mitochondria per square micron of Schwann cell cytoplasm was elevated when compared with values obtained from normal subjects and a patient with a chronic neuropathy. These findings may indicate an alteration of mitochondrial function common to muscle fibers and Schwann cells which, in nerves, could lead to axon loss and abnormality of myelination.

Autosomal dominant Kearns-Sayre syndrome

External ophthalmoplegia, retinal pigmentary degeneration, and heart block constitute the Kearns-Sayre syndrome. Skeletal muscle weakness, deafness, ataxia and endocrine disturbances also may occur. We examined 15 members in two generations of a family with autosomal dominant Kearns-Sayre syndrome. Seven had external ophthalmoplegia, six had electrocardiographic abnormalities, six had limb weakness nad six patients were normal. A deltoid muscle biopsy specimen from one patient contained typical "ragged-red fibers," abnormal lipid accumulation, and mitochondria increased in size and number, containing inclusions. The study demonstrated: (1) the marked variability in genetic expression; (2) the need to examine family members to discover asymptomatic patients and to establish an otherwise unrecognized hereditary pattern; and (3) the absence of specific and consistent biochemical abnormalities.

Ultrastructural study of globular inclusions in human skeletal muscle mitochondria

Limb muscle biopsies from a patient with Luft's disease and a patient with a slowly progressive neuromuscular disorder since infancy revealed by conventional electron microscopy the presence of globular inclusions in the mitochondria as one of the most prominent morphological findings. Electron cytochemical studies on fresh tissue blocks showed no cytochrome c oxidase activity within the globular inclusions. The study of strontium uptake supported by either NAD and flavo-protein linked substrates in freshly isolated mitochondria fractions showed no electron-dense needles within the globular inclusions. Attempts to remove the inclusions with pepsin and with pronase on ultrathin sections failed but they were partially and totally removed by treatment of the sections with hydrogen peroxide. Freeze fracture studies showed the globular inclusions consisted of amorphous and lamellar material. The results suggest that the globular inclusions in muscle mitochondria may consist primarily of lipid.

A mitochondrial myopathy with a deficiency of respiratory chain NADH-CoQ reductase activity

This paper presents data on two sisters with a mitochondrial myopathy characterised by weakness, marked exercise intolerance and a fluctuating lactic acidaemia. Both patients also experienced episodes of increased weakness which could be brought on by unaccustomed activity, going without food or by taking small quantities of alcohol. Metabolic studies during exercise showed a marked and sudden rise in blood lactate and pyruvate levels. Biochemical studies in one case showed that mitochondrial respiratory rates were markedly decreased with all NAD-linked substrates tested but were normal with succinate and with TMPD + ascorbate. The mitochondrial cytochrome components were normal as determined by low temperature spectroscopy and the addition of uncoupler did not enhance state 3 respiratory rates utilising NAD-linked substrates. It was concluded, therefore, that the mitochondrial lesion was located at the level of the NADH-CoQ reductase complex.

Mitochondrial abnormalities of late motor neuron degeneration following poliomyelitis and other neurogenic muscular atrophies

A case of late motor neuron degeneration following poliomyelitis with abnormal mitochondria in muscle fibers is presented with two additional cases of systemic neurogenic muscular atrophy (Charcot-Marie-Tooth disease). Muscle biopsy revealed a neurogenic pattern of variable severity in all cases. Subsarcolemmal zones of hyperactivity and hyperpositive intermyofibrillar collections of granular material present in a variable proportion of type I fibers were demonstrated by oxidative enzymes. Ultrastructurally they corresponded to abnormal mitochondria, with paracrystalline inclusions in one case. The finding is discussed in the light of the previous literature on mitochondrial myopathies. Mitochondrial alterations are not specific and their significance in neurogenic conditions is debated.

[Muscle biopsy in progressive external ophthalmoplegia (author's transl)]

In skeletal muscle biopsies of nine patients with progressive external ophthalmoplegia of unknown origin "ragged red" fibers can be demonstrated. The occurrence of these abnormal fibers does not correlate with clinical muscle weakness, or additional signs of the ophthalmoplegia plus syndrome. Rarely, "ragged red" fibers are seen in other neuromuscular disorders but usually these are associated with various structural alterations. Numerous "ragged red" fibers in an otherwise normal muscle provide an essential criterion in establishing the diagnosis of the ophthalmoplegia plus syndrome.

On the pathogenesis of mitochondrial myopathies. An experimental study

The intra-arterial injection of 2-4 dinitrophenol, an uncoupler of oxidative phosphorylation, resulted in the production of ragged red fibers. The ultrastructure of these fibers showed intramitochondrial paracrystalline inclusions, laminar and fingerprint bodies. Antimycin A and oligomycin injection (which inhibit mitochondrial respiration) only caused swelling and disruption of the mitochondria. An increase in muscle lactic acid, decrease in ATP, glycogen and phosphocreatine was observed after the injection of all these agents. This indicates that lactic acidosis has no significant role in the pathogenesis of mitochondrial pathology. It is concluded that mitochondrial changes are a morphological expression of uncoupled but intact mitochondrial respiration.

Transvascular endomyocardial biopsy in infants and small children. Myocardial findings in 10 cases of cardiomyopathy

Transvascular endomyocardial biopsy specimens from nine children with congestive cardiomyopathy and one with hypertrophic cardiomyopathy were studied by light microscopy using sections 1 mu thick cut from Epon embedded tissue and by electron microscopy. There was a disparity between the severity of the physiologic impairment and the morphologic abnormalities. Interstitial fibrosis was present only in the one case in which significant viral antibody titers were obtained. The sizes of the cardiac muscle cells varied abnormally in all specimens. Cardiac muscle cells in two patients contained abnormal mitochondria, and a leptomeric fibril was found in one patient. Virologic cultures of the tissues were negative and no viral particles were identified by electron microscopy. An attempt was made to correlate the clinical and pathologic findings.

Experimental (-) emetine myopathy. Ultrastructural and morphometric observations

The ultrastructural changes induced by (-) emetine hydrochloride were studied in two skeletal muscles of the rat. (-) Emetine was administered at a dose level of 2 mg/kg for periods ranging from one to four weeks. Changes were noted after the one week stage and were progressive with all muscle components appearing to be affected. Myofibrillar changes included Z line streaming, rod formation, myofilament loss and contraction clumping. Mitochondrial degeneration was detected, but the most striking feature of the induced myopathy was the extensive membrane proliferation. The membranes were considered to be involved in the isolation of sarcoplasmic constitutents in the production of autophagic vacuoles. Morphometry was carried out in order to quantify some of the changes in the fibre components.

The early effects of ischemia upon skeletal muscle mitochondria

The effects of early ischemia were studied in the anterior tibial muscle of Sprague-Dawley rats after 2--24 hr of tourniquet compression at the thigh. Ragged-red fibers, moth-eaten fibers, cores and targets were seen in tissue examined by enzyme histochemistry and electron microscopy. Giant mitochondria, abnormalities of cristal arrangement, crystalloids, osmiophilic inclusion bodies and myeloid figures were dominant features of the mitochondrial reaction. The results of this experiment indicate that early ischemia induces a variety of changes described in other neuromuscular conditions such as dystrophy and the "mitochondrial myopathies". The pathogenesis of these changes and their relationship to human disease of muscle is discussed.

Hereditary distal myopathy with onset in early infancy. Observation of a family

The study of a family affected with hereditary distal myopathy with onset in early infancy is presented. Complete neurological examination was necessary in several members of the two last generations to discover the existence of the abnormalities of which they were unaware. The propositus was the most affected member of the family iwth distal paresis of the upper and lower extremities and selective paresis of the deltoid muscles. In addition he had kyphoscoliosis, talipes valgus and limitation of mobility of several joints. The onset of the disease was estimated as before the age of 2 when the child started walking. There was no progression of the disease. Clinical examination suggested a myopathic origin of the condition. A sural nerve biopsy was normal. Light-microscopy histochemical studies disclosed a predominance of type I fibres which were at the same time hypotrophic. Subsarcolemmal deposits of mitochondria were present although they were scanty and of normal ultrastructural appearance. In view of the morphological presentation it is postulated that this disease should be classified within the groups of myopathies accompanied by disproportion of fibres and selective atrophy of type I fibres.

The syndrome of carnitine deficiency: morphological and metabolic correlations in two cases

Two cases of systemic carnitine deficiency are described. In both patients, carnitine concentration was lower than normal in serum and muscle tissue. In the first case, the illness began at age 35; the clinical manifestations were only muscular. In the second case, the illness began in childhood; there were intermittent episodes of hepatic enlargement and coma. An excessive lipid content was present in muscle tissue, especially in type 1 fibers, of both cases, and in the liver of the second patient. Ultrastructural studies of muscle tissue revealed important changes of mitochondria. During muscular exercise, aerobic and anaerobic metabolism were investigated. For a given relative work intensity, these patients showed abnormally high blood lactic acid concentration and lactic acid/pyruvic acid ratios. These data, together with the morphological alterations observed in mitochondria, suggest an impaired function of the respiratory chain, leading to a shift of the red/ox potential of the tissue towards a non reduced state.

Further studies of mitochondrial and lipid storage myopathies

Further observations on a family with facioscapulohumeral (FSH) muscular dystrophy due to mitochondrial myopathy, and on a case with lipid storage myopathy are reported. One member of the family with FSH muscular dystrophy died due to a viral pneumonia, during which she developed gross hyperlacticacidaemia and acidosis. Autopsy examination showed that the mitochondrial morphological abnormality was restricted to the skeletal muscle. Two other members of the family, who also had mitochondrial myopathy, have developed a cerebellar syndrome. The skeletal muscle carnitine level in the propositus of this family was normal. A woman with lipid storage myopathy has been shown to have skeletal muscle carnitine deficiency, the plasma carnitine level being only slightly lower than normal.

Freeze-fracturing studies of mitochondrial myopathy. A correlated clinical, biochemical and morphological investigation

Freeze-fracture studies of pathologically changed mitochondria in situ from muscle biopsies of a 9.5-year-old girl with a mitochondrial myopathy were correlated with clinical, biochemical and histochemical investigations. In the ultrathin sections giant mitochondria with densely packed cristae membranes - often reoriented to concentric circles - and, in addition, paracrystalline mitochondrial inclusions were found. The freeze fracture faces of such transformed mitochondria and preparations of their inner and outer membranes provided a morphological insight in the macromolecular structure of the mitochondrial membrane under such pathological conditions. The results lead to the hypothesis that part of the transformed mitochondria stay active functionally for an extended period by maintaining the delimitation from the cytoplasm and by preserving the macromolecular membrane architecture. This hypothesis could explain the slow progression of the myogenic symptoms.

Weakness associated with the pathological presence of lipid in skeletal muscle: a detailed study of a patient with carnitine deficiencey

A patient with muscular weakness demonstrating pathological lipid accumulation and abnormal mitochondria in skeletal muscle has been studied. The lipid accumulation and mitochondrial changes are thought to be related to the established deficiency of carnitine in this patient's muscle. The symptoms of muscular weakness associated with lipid accumulation in the skeletal muscle in the absence of complaint of muscle cramps or myglobinuria are thought to be diagnostic of carnitine deficiency. The failure of the sarcoplasmic reticulum to accumulate Ca2+ is discussed. The patient's strength responded dramatically when propranolol was added to his steroid therapy.

Cardiac biopsy in skeletal myopathy: report of a case with myocardial mitochondrial abnormalities

Transvenous right ventricular endomyocardial biopsy in an 11-yr-old boy with a proximal skeletal myopathy and a cardiomyopathy, has shown a major increase in mitochondrial size and numbers on electron-microscopic morphometry, with formation of unique ring-shaped mitochondria in cardiac muscle cells. The significance of this finding and the use of cardiac biopsy in children are discussed.

Ragged-red fibers. A biochemical and morphological study

Histochemical, ultrastructural and biochemical studies were performed on muscle biopsy specimens from a 30-year-old man with proximal limb weakness. Modified Gomori trichome stains of anterior tibial muscle revealed accumulations of red-staining material in the subsarcolemmal and intermyofibrillar regions of virtually every fiber (ragged-red fibers); these accumulations were rich in oxidative enzymes. Electron microscopy of this muscle showed that the red-staining areas consisted of large collections of abnormal-appearing mitochondria. Mitochondria isolated from the quadriceps muscle showed lack of respiratory control with alpha-glycerophosphate as substrate. However, the lack of respiratory control with alpha-glycerophosphate must be interpreted with caution since the quadriceps muscle was severely degenerated, and biochemical alterations of mitochondria may occur secondary to muscle degeneration itself. Nevertheless, this is the second reported case of lack of respiratory control with alpha-glycerophosphate in a patient with ragged-red fibers. Further interpretation of this defect and its significance must await more studies to determine whether this muscle mitochondrial abnormality is a common finding in the disorders in which ragged-red fibers are encountered.

Idiopathic cardiomyopathy and skeletal muscle abnormality

The skeletal muscle of three cases presenting with idiopathic congestive cardiomyopathy has been studied, histologically, histochemically, ultramicroscopically, and electromyographically. In all three there is clinical evidence of skeletal muscle weakness, and in all three, pathologic changes were found in the muscle. These changes were different in each case and varied from mitochondrial myopathy to spinal atrophy to vacuolar myopathy. Other reported cases of cardiomyopathy demonstrating skeletal muscle pathology are discussed.

Lipid storage myopathy with normal carnitine levels

A 28-year-old female, who showed a floppy baby syndrome during early infancy, had a non-progressive proximal muscle weakness with easy fatiguability since childhood. Two muscle specimens biopsied at the age of 28 years revealed myriads of 1-3-mum wide abnormal spaces containing neutral fat in type I and type II fibers. Both biopsies demonstrated a type I fiber preponderance. Electron microscopy demonstrated lipid excess and normal mitochondria by simple inspection. The mitochondrial area and sarcotubular membrane profile concentration in morphometry of longitudinal sections were also normal. Cross-sections, however, revealed a slight decrease of the individual mitochondrial size and of the sarcotubular membrane profile concentration . Serum and muscle carnitine levels and the muscle carnitine palmityltransferase level were all within normal range. Besides carnitine deficiency other biochemical defects can occur in lipid storage myopathy, which represents a syndrome rather than a unique disease entity.

[Mitochondrial changes of the skeletal muscle in the peroneal muscular atrophy (Charcot-Marie-Tooth disease). Histological and electron microscopic studies (author's transl)]

This report deals with two sisters (38 and 44 years old) suffering from Charcot-Marie-Tooth disease. Muscle biopsies were taken from the deltoid and the rectus femoris. In one of the cases a sural nerve biopsy was also made. Light microscopy showed only slight myopathic changes. The histochemical reactions disclosed an increase in lipid deposition and in NADH-TR activity of type 1 fibres. Electron microscopy showed abnormal mitochondrial aggregates, which were surrounded inconstantly by glycogen deposits, especially in subsarcolemmal space. Many of the atypical mitochondria showed paracristalline inclusions within the cristae. The significance of these findings is discussed and compared with similar reports in the literature.

Myopathy with mitochondrial inclusion bodies: histological and metabolic studies

Apparently new information about a metabolic abnormality has been obtained by measuring biochemical and respiratory responses to controlled exercise in a patient with abnormal mitochondria in muscle fibres. A male patient (49 years old) presented with bilateral ptosis of 15 to 20 years' duration and weakness for one to two years. Biopsies from the deltoid and triceps muscles were subjected to histological, histochemical, and electron microscopical examination. Routine histology showed only minor changes; 2-5% of muscle fibres had pale borders in which there were aggregates of mitochondria and 1-5% of fibres showed atrophy. Histochemical examination showed increased activity of succinic dehydrogenase in mitochondria and lactate dehydrogenase in cytoplasm. Electron microscopy showed crystalline inclusions in many subsarcolemmal mitochondria. Metabolites were studied during and after exercise on an ergometer and revealed remarkable differences from normal. Blood lactate rose to 12·5 μmol/ml and pyruvate to 0·39 μmol/ml compared with up to 4·0 and 0·16 μmol/ml respectively in controls exercising to a comparable percentage of capacity. Concentrations of ketone-bodies and free fatty acids fell during and after exercise, while they rose in the controls. These observations imply a major mitochondrial defect which causes dramatic biochemical changes in fuel supply in blood during exercise. The changes suggest that fat metabolism was accelerated (in this patient) and was related to a block of carbohydrate utilization as fuel.

Chronic benign congenital myopathy: fingerprint body type

The term “benign congenital myopathy” describes a group of muscle disorders characterized by proximal or diffuse muscle weakness, a relatively non-progressive course, normal serum muscle enzyme assays and the presence of a distinctive morphological feature. We report here a 55 year old woman, with fingerprint body myopathy who exhibits all of the above features. She has been affected from birth, able to walk since the age of 12, and has not deteriorated in the past thirty years. Muscle biopsy reveals fatty infiltration, numerous small fibers undergoing structural change, good differentiation into type I and II fibers, and excessive intracellular lipid and lipochrome. Only on electron microscopic study is the distinctive feature of numerous subsarcolemmal round to ovoid fingerprint bodies observed. Many fibers also contain large collections of tubular aggregates, filamentous bodies, and autophagic vacuoles.

The fingerprint bodies are similar to the ones described by A. Engel in a 5 year old girl. Thus, a rare opportunity is provided to study an individual who has had this disease for over fifty years.