Pathogenesis of ano-rectal incontinence. A histometric study of the anal sphincter musculature.

Type 1 fibre predominance was found in the external anal sphincter, puborectalis and levator ani muscles of 17 control subjects, and of 16 patients with ano-rectal incontinence. In the external anal sphincter and puborectalis muscles of the control subjects the mean diameter of Type 2 fibres was slightly greater than that of Type 1 fibres, but in the levator ani muscles of control female subjects the mean diameter of Type 1 fibres was much greater than that of Type 2 fibres. In the patients with anorectal incontinence there was marked hypertrophy of fibres of both histochemical types. This was most marked in the puborectalis and external anal sphincter muscles. In 12 of the 16 incontinent patients there were histological and statistical features consistent with a neurogenic disorder. These histometric studies provide a quantitative basis for physiological and pathological studies of these muscles in incontinence and other anorectal disorders.     

A study of vascular permeability in normal skeletal muscle and inflammatory myopathies using a fluorescein dye technique with percutaneous needle biopsy

Percutaneous needle biopsy of the vastus lateralis muscle was performed immediately prior to the intravenous injection of 5 ml of 20% fluorescein sodium, in 2 control subjects and 2 patients with polymyositis. Repeat biopsies were performed 5, 10 and 15 minutes after injection. Similar biopsies were taken prior to, and 10 minutes after, fluorescein injection in 1 control subject and 15 patients with a variety of inflammatory muscle conditions including polymyositis, some of whom were on treatment with corticosteroids. Apart from one patient, with polymyalgia rheumatica, increased penetration of dye was found only in those patients with polymyositis, particularly around areas of cellular infiltration, necrosis and phagocytosis and in the periphery of muscle fibres. Corticosteroid therapy appeared to reduce the amount of dye permeating muscle tissue in patients with polymyositis. It is suggested that reducing the abnormally increased vascular permeability in damaged muscle from patients with polymyositis may represent one mode of action of corticosteroids in this condition, and that the amount of fluorescein permeating muscle may be helpful in the diagnosis where conventional clinical and histological criteria are not conclusive.     

Interleukin‐1 expression in inflammatory myopathies: evidence of marked immunoreactivity in sarcoid granulomas and muscle fibres showing ischaemic and regenerative changes

The most frequent autoimmune adult inflammatory myopathies are dermatomyositis, polymyositis, inclusion body myositis, and sarcoid myopathy. Interleukin‐1 (IL‐1) is a pleiotropic molecule, implicated in the inflammatory process, but also in tissue protection and remodelling. We evaluated the immunocytochemical expression of IL‐1α and β in frozen muscle biopsy specimens from patients with dermatomyositis (15 cases), polymyositis (five cases), inclusion body myositis (five cases) and sarcoid myopathy (five cases). Positive immunoreactivities, were observed in both inflammatory cells and muscle fibres. Specificity of the immunostaining was assessed by Western blot experiments. IL‐1 positive inflammatory cells were rare in polymyositis and inclusion body myositis, moderately abundant in dermatomyositis, and prominent in sarcoid myopathy granulomas. In sarcoid myopathy, 24.6±4.1% inflammatory cells were IL‐1α‐positive and 45.2±2.6% were IL‐1β‐positive. IL‐1 positive muscle fibres were mainly observed in dermatomyositis, usually remote from inflammatory infiltrates. Positive immunostaining for IL‐1 was observed in fibres showing ischaemic punched‐out vacuoles, that correspond to areas of myosinolysis, in atrophic perifascicular fibres, and in fibres located within healing microinfarcts. All NCAM‐positive regenerating fibres were IL‐1 positive. We conclude that: (i) IL‐1 is expressed in granulomas of sarcoid myopathy, which is in keeping with the role ascribed to IL‐1 in the formation of granulomas; (ii) IL‐1 is expressed by muscle fibres undergoing ischaemic damage; and (iii) IL‐1 expression by muscle fibres is associated with myofibrillar protein breakdown and regeneration.     

Partial cytochrome c oxidase deficiency and cytoplasmic bodies in patients with zidovudine myopathy.

A histochemical study of cytochrome c oxidase (CCO) was performed in the muscles from eight patients with full-blown zidovudine myopathy. All patients had ragged-red fibres (total cumulative count: 160) and myofilamentous changes, that predominated in type 1 fibres and included diffuse or punch-out myofibrillar loss (75 affected fibres) and constant cytoplasmic body formation (106 affected fibres). Inflammatory infiltrates were present in four out of eight patients. A partial CCO deficiency (22-47% of fibres; both types 1 and 2 affected) was detected in all cases, and contrasted with the normal or increased succinate dehydrogenase activity observed in most fibres. Among CCO-deficient fibres, 71% were normal on trichrome, but all ragged-red fibres were CCO-negative. Myofilamentous changes were restricted to CCO-deficient fibres. The present study strongly supports the idea that mitochondrial toxicity is the specific mechanism of zidovudine myopathy.     

Correlation of single fibre EMG and muscle histochemistry using an open biopsy recording technique

Single fibre electromyographic (SFEMG) recordings were carried out during open muscle biopsy. Nine patients were studied, including 5 with Duchenne muscular dystrophy, 2 with spinal muscular atrophy and 1 each with limb-girdle dystrophy and myotonic dystrophy. Correlations were possible between the SFEMG fibre density determinations and histochemical evidence of grouping in some biopsies, particularly involving Type I fibres. This combined technique permits an improved assessment of the functional state of abnormal muscle.     

Mitochondrial myopathy with multisystem abnormalities and normal ocular movements.

A woman aged 27 years is described with mental retardation, short stature, epilepsy, muscle weakness, chorioretinitis, nerve deafness, ataxia, abnormalities of the electroencephalogram and electrocardiogram, elevated cerebrospinal fluid protein and abnormal carbohydrate metabolism. There was no ophthalmoplegia. Histopathological studies on quadricepts muscle biopsy demonstrated a high proportion of Type I fibres with subsarcolemmal collections of granular material (“ragged-red” fibres). There was also an increase in intracellular lipid. On electron microscopy, abnormal mitochondria containing paracystalline inclusions were seen predominantly in subsarcolemmal regions. The patient differs from other cases of mitochondrial myopathy with this syndrome in having normal ocular movements. Muscle disease in such cases appears to be only one manifestation of a more widespread disorder of tissue metabolism.     

Contrasting histochemical features of various mitochondrial syndromes

A comparative histochemical analysis of the prevalence and cytochrome oxidase staining characteristics of ragged-red fibres in limb skeletal muscles was performed in 19 patients spanning four distinct mitochondrial syndromes: chronic progressive external ophthalmoplegia; myoclonus epilepsy with ragged-red fibres; mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes; and pure limb myopathy. The percentage occurrence of non-ragged red but cytochrome oxidase negative fibres was additionally noted. Ragged-red fibres and cytochrome oxidase-negative fibres were generally more prevalent in the chronic progressive external ophthalmoplegia syndrome than in myoclonus epilepsy ragged-red fibres syndrome or mitochondrial myopathy encephalopathy lactic acidosis and stroke-like episodes syndrome. Isolated cytochrome oxidase-negative fibres were a common finding in each phenotypic syndrome except pure limb myopathy and could involve any of the major fibre types non-specifically. Ragged-red fibres were devoid of cytochrome oxidase activity in chronic progressive external ophthalmoplegia, but commonly displayed activity in the other three syndromes providing a clue to syndromal differentiation on a histochemical basis.     

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.     

Ragged-red fibres detected in paraffin sections by a monoclonal antibody to inner mitochondrial membrane

Summary An immunohistochemical method is reported using the M-II68 monoclonal antibody, which detects mitochondrial accumulations (ragged-red fibres) in routinely processed (formalin-fixed, paraffin-embedded) muscle tissue. Ten cases with electron-microscopically and histochemically proven mitochondrial myopathy featured 4% to 24% ragged-red fibres. In a series of 50 muscle biopsies without mitochondrial myopathy, scattered ragged-red fibres (<0.1%) were present in a few normal and pathological muscles. The immunohistochemical method is specific for mitochondria, does not require frozen tissue and permits rapid examination of large areas. Present address and address for offprint requests: Ludwig-Boltzmann-Institut für Klinische Neurobiologie, Krankenhaus Lainz, Wolkersbergenstrasse, A-1130 Wien. Austria     

Granulomatous polymyositis

An account is given of a pathological condition, more common in women, which presents clinically as a slowly progressive muscular disorder of adult life.The essential histological lesion is an infiltration of the connective tissue sheaths of voluntary muscle by non-specific granulomas composed of epithelioid cells, histiocytes, multinucleated giant cells and lymphocytes. The granulomas are non-caseating and show an outer zone of fibrosis and an inner fine reticulin network. Special stains have failed to detect bacterial, parasitic or fungal agents.Twenty-four cases of chronic granulomatous polymyositis have been previously reported in the literature. Post-mortem findings have, so far, been described in only 1 of these cases. The clinical, electromyographic and pathological findings in a further case are presented. Light-microscopic observations revealed granulomatous lesions in biopsy specimens of deltoid and peroneus brevis muscles. The cytoplasm of many of the multinucleated giant cells in the granulomas contained large amounts of acid mucopolysaccharide. Although there was atrophy of muscle fibres in the vicinity of the lesions, the structure of the fibres was preserved and there was no evidence of abnormal cellular infiltrates in the sarcoplasm. Muscle fibres remote from the lesions showed no abnormalities. The intramuscular nerves showed branching of the subterminal axons, beaded axons, occasional degenerate motor end-plates and large numbers of spherical axonal swellings in the intramuscular nerve bundles.Histochemical studies were incomplete, but there was an apparently normal distribution of glycogen, lipid, lactic dehydrogenase and phosphorylase activity in Type I and Type II fibres.Because of incomplete pathological data, the nosology of this condition, for the time being, must remain uncertain. Some workers consider that it is a form of sarcoidosis restricted to voluntary muscle.     

Mitochondrial myopathy in Marinesco-Sjögren syndrome

ABSTRACT. Myopathy represents one of the major features of Marinesco-Sjögren syndrome (MSS). Seven patients with MSS from three different families were studied with morphological and neurophysiological methods. In two patients ragged-red fibres were found after Gomori trichrome staining. Transmission electron microscopy (EM) showed that subsarcolemmal accumulation of abnormal mitochondria regularly occurred and in one patient paracrystalline inclusion bodies were found. The EMG showed myopathic changes while the nerve condition velocities were normal. A delayed normalization of exercised-induced hyperlactatemia was noted. These findings show that mitochondrial myopathic changes are present in MSS.     

MORPHOMETRIC APPROACHES TO PERIFASCICULAR ATROPHY IN MUSCLE BIOPSY: DO THEY HELP TO DIAGNOSE POLYMYOSITIS?

The sizes of muscle fibres in the peripheral and central parts of fascicles were compared in biopsies from patients with polymyositis/dermatomyositis, patients with slowly progressing muscular dystrophies and normal controls. Of three quantitative parameters tested, perifascicular atrophy factor gave the best discrimination between the patient groups. This factor is obtained by subtracting the atrophy factor of the peripheral fibres from that of the central ones. In polymyositis, the values tend to be negative as a result of atrophy affecting selectively the peripheral fibres, whereas in dystrophies the values are usually close to zero or positive. For the comparison between polymyositis and muscular dystrophy, the test based on perifascicular atrophy factor has an estimated sensitivity of 83% and a specificity of 65%. This quantitative method is thus able to increase sensitivity of the diagnosis of polymyositis over that attained by the subjective evaluation, even at the cost of a sizeable false-positive rate.     

Histochemical features of ragged-red fibres in diseased skeletal muscles

In the present communication, the activity of 24 oxidoreductases, transferases, isomerases and hydrolases was examined histochemically in ragged-red fibres of human skeletal muscle specimens. The biopsy material was obtained from patients with neuromuscular diseases caused by an abnormally metabolic functioning of the muscle mitochondria. The granular accumulations of the ragged-red fibres were characterized by an impressive activity of all mitochondrial and most non-mitochondrial enzymes examined, whether participating in the aerobic or in the anaerobic pathways. With the exception of mitochondrialMg²⁺ -stimulated ATPase, acid phosphatase and AMP-aminohydrolase, there was no activity of the other hydrolytic enzymes studied in these regions. The strong activity of mitochondrial ATPase points to the presence of loosely coupled and/or uncoupled mitochondria. Ragged-red fibres that exhibited a diffuse and corpuscular activity of acid phosphatase, were always undergoing necrotic changes. A dsorption studies with diluted enzyme solutions demonstrated that the granular accumulations display a specific, moderate affinity for glycolytic enzymes.     

The perifascicular atrophy factor an aid in the histological diagnosis of polymyositis

19 biopsies of polymyositis patients were compared with 19 matched controls. The presence of smaller fibres in the periphery of the fascicles has been analyzed quantitatively using a perifascicular atrophy factor. The thinner fibres are multiplied by a factor from 1-4, considering their significance for the diagnosis of fibre atrophy. The value obtained with this method from centrally located fibres as related to the value from peripherally located ones is called the perifascicular atrophy factor. If this is less than -300 a myopathy of the group of the polymyositis/dermatomyositis can be assumed. 47 per cent of dermatomyositis biopsies and none of the controls were below this range     

PATHOGENESIS OF LONGITUDINAL SPLITTING OF MUSCLE FIBRES IN NEUROGENIC DISORDERS AND IN POLYMYOSITIS

Longitudinal splitting of muscle fibres has been studied in the biopsies of eighteen patients with neurogenic disorders, and of twenty with polymyositis. In neurogenic disorders splitting predominantly affects hypertrophied fibres, and is probably due to mechanical overload induced by normal loads imposed on a weakened muscle. A similar phenomenon occurs in hypertrophied fibres in chronic polymyositis. However, in acute, or active polymyositis an appearance resembling fibre splitting can result from sequestration of necrotic segments within a fibre and also from regeneration occurring within intact sarcolemmal tubes after segmental sub-endomysial necrosis. These different processes, which can be distinguished by light and ultrastructural criteria, are important compensatory factors in neuromuscular disorders.     

A partial deficiency of cytochrome c oxidase in chronic progressive external ophthalmoplegia

A partial deficiency of cytochrome oxidase has been found in 7 patients with chronic progressive external ophthalmoplegia and proximal myopathy or craniosomatic abnormalities. Muscle biopsies from all these patients showed morphological mitochondrial abnormalities (“ragged red” fibres) and cytochemical assay of cytochrome oxidase showed that these fibres contained no demonstrable enzyme activity. The incidence of cytochrome oxidase-negative fibres was greater than that of “ragged-red” fibres suggesting that the enzyme defect preceded the development of morphological mitochondrial changes. Biochemical analysis of skeletal muscle mitochondrial fractions from 3 patients revealed in 1 case a significantly lower concentration of cytochrome aa₃ and a decreased ratio of cytochrome oxidase/succinate-cytochrome c reductase. Fasting blood metabolites were elevated in 2 patients. We suggest that partial cytochrome oxidase deficiency is the underlying defect in mitochondrial myopathy associated with the oculocraniosomatic syndromes.     

Two novel mutations in PEO1 (twinkle) gene associated with chronic external ophthalmoplegia

Maintenance and replication of mitochondrial DNA require the concerted action of several factors encoded by nuclear genome. The mitochondrial helicase Twinkle is a key player of replisome machinery. Heterozygous mutations in its coding gene, PEO1, are associated with progressive external ophthalmoplegia (PEO) characterised by ptosis and ophthalmoparesis, with cytochrome c oxidase (COX)-deficient fibres, ragged-red fibres (RRF) and multiple mtDNA deletions in muscle. Here we describe clinical, histological and molecular features of two patients presenting with mitochondrial myopathy associated with PEO. PEO1 sequencing disclosed two novel mutations in exons 1 and 4 of the gene, respectively. Although mutations in PEO1 exon 1 have already been described, this is the first report of mutation occurring in exon 4.     

A qualitative and quantitative study of the ultrastructure of regenerating muscle fibres in Duchenne muscular dystrophy and polymyositis

Quantitative and qualitative ultrastructural analyses were made of selected small muscle fibres from muscle biopsies from 23 patients with Duchenne muscular dystrophy (DMD) and 10 with polymyositis. It is argued that the fibres selected were regenerating. The myofibrillar content of the fibres was similar in both samples. In both there was considerable misalignment of the myofibrils but their orientation tended to improve as the content increased. The mitochondrial content was similar in the two samples but there were more ultrastructural abnormalities in the DMD population. The concentration of glycogen was elevated and the sarcoplasmic reticulum (SR) was much more commonly dilated in the DMD patients. Dilated SR is the prenecrotic change seen most frequently in mature muscle fibres in DMD and seems to be the first ultrastructural manifestation of the disease process. Its occurrence in the regenerating fibres suggest that the primary genetic lesion is being recapitulated in successive generations of fibres.     

Patterns of abnormal histochemical fibre type differentitation in human muscle biopsies.

The histochemical profile of individual human skeletal muscle fibres was analysed by correlating mitochondrial oxidative enzyme activity and that of myofibrillar ATPase at pH 9.5 and after pre-incubation at pH 4.3 and pH 4.6. In normal control muscle, only a small percentage of fibres did not conform to one or other of the normal variants of Type I and Type II fibres. In biopsies from early cases of Werdnig-Hoffmann disease, the denervated fibre populations contained many abnormal Type I and Type II fibres, including "IIc" fibres, but the basic distinction between Type I and Type II was preserved. However, in infantile spinal muscular atrophy patients aged two years and over, this distinction was progressively lost, leading to the total dedifferentiation of the atrophied fibres. In the Kugelberg-Welander form of spinal muscular atrophy, many of the constituent fibres of re-innervated groups displayed normal or near-normal histochemical profiles, but chronically denervated fibres became totally dedifferentiated. In Duchenne dystrophy, the spectrum of histochemical types appeared to be more continuous due to the emergence of fibres with properties intermediate between those of the normal variants, but the basic distinction between Type I and Type II fibres was preserved in the majority of cases. The percentage of severely abnormal fibres was higher in Type II than Type I and probably contributed to the observed decrease in the overall proportion of Type II fibres. Although very small atrophied fibres were observed in biopsies from cases of Becker and Duchenne dystrophy, these did not show the total dedifferentiation seen in the chronically denervated fibres in cases of spinal muscular atrophy.