The adult form of acid maltase (alpha-1,4-glucosidase) deficiency

A novel mutation of the GAA gene in a patient with adult-onset Pompe disease lacking a disease-specific pathology

We herein report a novel compound heterozygous mutation of the acid α-glucosidase (GAA) gene in a 23-year-old man with adult-onset Pompe disease. The patient was admitted for respiratory failure and a highly elevated serum level of creatine kinase (CK). His muscle pathology did not show typical vacuolated fibers; however, globular inclusion bodies with acid phosphatase (ACP) activity was observed. A molecular genetic analysis of the GAA gene revealed a novel compound heterozygous mutation, c.1544 T>A (M515K), combined with a previously reported mutation, c.1309 C>T (R437C). The presence of ACP-positive globular inclusion bodies is a useful diagnostic marker for adult-onset Pompe disease, even when typical vacuolated fibers are absent.

The spectrum of myotonic and myopathic disorders in a pediatric electromyography laboratory over 12 years

This study assessed the spectrum of disorders associated with electrophysiologic myotonia in a pediatric electromyography laboratory. Records of 2234 patients observed in the Electromyography Laboratory at Boston Children's Hospital from 2000-2011 were screened retrospectively for electrophysiologic diagnoses of myotonia and myopathy. Based on electromyography, 11 patients manifested myotonic discharges alone, eight exhibited both myotonic discharges and myopathic motor unit potentials, and 54 demonstrated myopathic motor unit potentials alone. The final diagnoses of patients with myotonic discharges alone included myotonia congenita, paramyotonia congenita, congenital myopathy, and Pompe disease (acid maltase deficiency). The diagnoses of patients with both myotonic discharges and myopathic motor unit potentials included congenital myopathy and non-Pompe glycogen storage diseases. Myotonic discharges are rarely observed in a pediatric electromyography laboratory, but constitute useful findings when present. The presence or absence of concurrent myopathic motor unit potentials may help narrow the differential diagnosis further.

The natural course of non–classic Pompe’s disease; a review of 225 published cases

Pompe's disease is a neuromuscular disorder caused by deficiency of lysosomal acid alpha-glucosidase. Recombinant human alpha- glucosidase is under evaluation as therapeutic drug. In light of this development we studied the natural course of cases not fitting the definition of classic infantile Pompe's disease. Our review of 109 reports including 225 cases shows a continuous spectrum of phenotypes. The onset of symptoms ranged from 0 to 71 years. Based on the available literature, no criteria to delineate clinical sub-types could be established.A common denominator of these cases is that first symptoms were related to or caused by muscle weakness. In general, patients with a later onset of symptoms seemed to have a better prognosis. Respiratory failure was the most frequent cause of death. CK, LDH, ASAT, ALAT and muscle glycogen levels were frequently but not always elevated. In most cases a muscle biopsy revealed lysosomal pathology, but normal muscle morphology does not exclude Pompe's disease. In 10% of the cases in which the enzyme assay on leukocytes was used, a normal alpha-glucosidase activity was reported. Data on skeletal muscle strength and function, pulmonary function, disability, handicap and quality of life were insufficiently reported in the literature. Studies of non-classic Pompe's disease should focus on these aspects, before enzyme replacement therapy becomes generally available.

Replacing acid α-glucosidase in Pompe disease: recombinant and transgenic enzymes are equipotent, but neither completely clears glycogen from type II muscle fibers

Pompe disease (type II glycogen storage disease) is an autosomal recessive disorder caused by a deficiency of lysosomal acid alpha-glucosidase (GAA) leading to the accumulation of glycogen in the lysosomes primarily in cardiac and skeletal muscle. The recombinant human GAA (rhGAA) is currently in clinical trials for enzyme replacement therapy of Pompe disease. Both clinical data and the results of preclinical studies in our knockout model of this disease show that rhGAA is much more effective in resolving the cardiomyopathy than the skeletal muscle myopathy. By contrast, another form of human GAA--transgenic enzyme constitutively produced in liver and secreted into the bloodstream of knockout mice (Gaa-/-)--completely prevented both cardiac and skeletal muscle glycogen accumulation. In the experiments reported here, the transgenic enzyme was much less efficient when delivered to skeletal muscle after significant amounts of glycogen had already accumulated. Furthermore, the transgenic enzyme and the rhGAA have similar therapeutic effects, and both efficiently clear glycogen from cardiac muscle and type I muscle fibers, but not type II fibers. Low abundance of proteins involved in endocytosis and trafficking of lysosomal enzymes combined with increased autophagy in type II fibers may explain the resistance to therapy.

Evaluation of muscle glycogen content by 13C NMR spectroscopy in adult-onset acid maltase deficiency

Muscle glycogen storage was measured by in vivo, natural abundance 13C nuclear magnetic resonance spectroscopy in distal and proximal lower limb segments of patients suffering from adult-onset acid maltase deficiency. Interleaved T1-weighted acquisitions of glycogen and creatine served to quantify glycogen excess. For acid maltase deficient patients (n=11), glycogen:creatine was higher than controls (n=12), (1.20+/-0.39 vs. 0.83+/-0.18, P=0.0005). Glycogen storage was above the normal 95% confidence limits in at least one site for 7/11 patients. The intra-individual coefficient of reproducibility was 12%. This totally atraumatic measurement of glycogen allows repeated measurement at different muscle sites of acid maltase deficient patients, despite selective fatty replacement of tissue. This could provide an additional parameter to follow the development of disease in individual patients, including in the perspective of forthcoming therapeutic trials. It may also offer an appropriate tool to study the role of glycogen accumulation in progression of the pathology.

Metabolic myopathies. A diagnostic evaluation

This article briefly reviews the initial approach to the patient suspected of having metabolic myopathy. Diagnostic highlights include relevant points of history, physical examination, blood work-up, forearm ischemic exercise test, electrophysiologic testings and muscle biopsy. The diagnostic evaluation is discussed in detail in separate articles.

Acid maltase deficiency and related myopathies

There are 11 glycogen diseases (GSD), nine of which are associated with myopathy. Most of these glycogen storage myopathies are associated with dynamic symptoms and signs in that the major neuromuscular complaints are exercise-induced muscle pain, cramps, and myoglobinura (e.g., GSD V or McArdle's disease associated with myophosphorylase deficiency). The other types of glycogen storage myopathies are considered static in that they are associated with fixed weakness rather than dynamic symptoms and signs. The static glycogen storage myopathies include: GSD I or Pompe's disease (acid maltase or (-glucosidase deficiency), GSD II or Cori-Forbes disease (debranching enzyme deficiency), and GSD IV or Andersen's disease (branching enzyme deficiency). This article reviews the clinical, laboratory, electrophysiologic, histopathologic, and pathogenesis of these static GSD myopathies.

Neuromuscular disorders and acute respiratory failure

This article discusses the assessment and management of rapidly progressive weakness due to neuromuscular disorders. The authors review elements helpful in determining the causes of weakness including pertinent history and laboratory studies. Disorders are classified according to the level of the motor unit involved and triage/management decisions are described. In addition, respiratory function assessment is reviewed. The latter part of this article is devoted to evaluation and management of two of the most common disorders, Guillain-Barré syndrome and myasthenia gravis.

Myopathies in the intensive care unit

Myopathies that occur in the intensive care unit can be divided into preexisting myopathies or newly acquired myopathies that develop in the intensive care unit. Myotonic dystrophy is an example of a preexisting myopathy that may render patients susceptible to acute respiratory failure following surgical procedures and anaesthesia. A group of myopathies that develop within the intensive care unit have been labelled acute necrotizing myopathy of intensive care, thick filament myopathy and acute steroid myopathy. Corticosteroids and nondepolarizing muscle blocking agents may play a role in their development.

Genotype-phenotype correlation in adult-onset acid maltase deficiency

We performed a clinical, biochemical, and genetic study in 16 patients from 11 families with adult-onset acid maltase deficiency. All patients were compound heterozygotes and carried the IVS1(-13T --> G) transversion on one allele; the second allele harbored either a deletion of a T at position 525 in exon 2 (7 probands, 64%) or a deletion of exon 18 (1 proband, 9%). Deterioration of handicap was related to age, and decrease in vital capacity to duration of the symptomatic stage. Respiratory insufficiency was never the first manifestation. The levels of activity of serum creatine kinase and of alpha-glucosidase in peripheral blood cells or muscle were helpful for the diagnosis, but did not have prognostic value. The adult form of acid maltase deficiency appears to be both clinically and genetically rather homogeneous; decrease of alpha-glucosidase activity is the final common pathway leading to destruction of muscle fibers and progression of muscle weakness over a period of years.

Clinical variability in adult-onset acid maltase deficiency: report of affected sibs and review of the literature

Acid maltase deficiency (AMD) is a rare cause of muscle disease in adult patients. The present report of 2 sibs and review of 36 previously reported cases illustrates the vast clinical variability in adult-onset AMD. This is 1 of only 3 reports to document tongue weakness and enlargement in an adult with AMD. The presenting signs and symptoms usually include progressive limb weakness, restrictive lung disease, or both. Consistent supportive abnormalities include a modest elevation in serum CK, a reduction in the forced vital capacity, and abnormal spontaneous activity (that is, myotonic discharges or fibrillations) in resting muscles during needle electromyography. The clinical spectrum is also extended to include distal limb weakness, scapular winging, asymmetric muscle weakness, and tongue involvement.

Hereditary distal myopathy with granulo-filamentous cytoplasmic inclusions containing desmin, dystrophin and vimentin

A 56-year-old female and her 34-year-old daughter presented with a predominantly distal myopathy affecting the peroneal and calf muscles, neck flexors and hand muscles. Both patients and two other daughters had cardiac arrhythmias, three requiring the insertion of cardiac pacemakers. Skeletal muscle biopsies revealed a complex myopathic process with granular degeneration, rimmed vacuoles and eosinophilic cytoplasmic inclusions. Ultrastructurally, the inclusions were composed of electron dense granular material and filaments forming linear masses beneath the sarcolemma and rounded masses within the cytoplasm of the fibres. Immunohistochemistry revealed labelling of the inclusions for desmin, dystrophin and vimentin, but not for alpha-actinin, spectrin, utrophin or myosin heavy chains. This family shows a hereditary distal myopathy with some features in common with previously-reported cases in which biopsies showed cytoplasmic inclusion bodies containing desmin. This group of diseases is clinically and pathologically heterogeneous. In the present cases, the accumulation of cytoplasmic filaments may reflect a generalised disturbance of filamentous protein metabolism rather than a specific disorder of desmin.

Familial cardiomyopathy, mental retardation and myopathy associated with desmin-type intermediate filaments

The clinical and morphological findings of a familial case affected by mental retardation, severe biventricular hypertrophic cardiomyopathy and vacuolar myopathy are reported. The phenotype of this patient is similar to that described by other authors, in which a lysosomal glycogen storage disease with normal acid maltase levels was suspected. However, in our case the vacuoles were stained by several antibodies directed against various sarcolemmal proteins, such as dystrophin and spectrin, and therefore, were not of lysosomal origin. Some of these vacuoles were clearly derived from the splitting of the fibres and invagination of the extracellular space; autophagic vacuoles were not observed. The accumulation of desmin-type, intermediate filaments was demonstrated on immunocytochemistry both in the skeletal and cardiac muscles. A brother of the propositus was also affected by mental retardation, severe cardiomyopathy and died suddenly at the age of 24 yr. A cardiomyopathy and mental subnormality were also present in other male cousins of the proband, while sudden death occurred in several females relatives, whose intelligence was normal. None of these latter individuals was available for further investigation. This report expands the spectrum of desmin associated myopathy and cardiomyopathy to include a familial condition with associated mental retardation.

A histochemical and electron microscopic study of skeletal muscle in an adult case of Chédiak-Higashi syndrome

To clarify the muscle pathology findings of a 39-year-old female Chédiak-Higashi syndrome (CHS) case with diffuse limb muscle atrophy, histochemical and electron microscopic studies were performed. In addition to neurogenic muscle atrophy due to the peripheral neuropathy, the most striking change seen by light microscopy was the widespread appearance of acid phosphatase-positive granules in many normal-looking muscle fibers. Coincident with the histochemical findings, electron microscopy showed many autophagic vacuoles containing glycogen particles and membranous structures in almost all muscle fibers. Although further studies are necessary, diffuse distribution of acid phosphatase-positive granules (autophagic vacuoles) in the skeletal muscle may reflect one of the generalized lysosomal abnormalities in CHS.

Histochemical and ultrastructural pathology of skeletal muscle in a patient with abetalipoproteinemia

Pathological examination was carried out of the skeletal muscle of an 8-year-old boy with abetalipoproteinemia. The patient complained of diarrhea, and showed a deficiency of betalipoprotein, decreased fat-soluble vitamins, acanthocytosis and a mild increase in serum creatine kinase. The prominent histochemical finding was punctate deposits of acid phosphatase activity in most fibers. Ultrastructural lesions revealed a number of giant lysosomes. Although these pathological findings seemed to be related to vitamin E deficiency, other pathological findings such as concentric laminated bodies or filamentous bodies were also observed. The clinical course and the changes in the pathological findings in our patient after long-term vitamin E therapy need to be observed.

Adult acid maltase deficiency

A 30-year-old man was referred for neurologic evaluation because of elevated creatine kinase. He had noted symptoms of proximal arm and distal leg weakness for several years, and, on examination, he had weakness in a scapuloperoneal distribution. An electromyogram showed myotonic discharges in the paraspinous muscles, and a muscle biopsy revealed severe vacuolar myopathy. Biochemical analysis of muscle showed acid maltase deficiency. The patient's only brother had childhood-onset acid maltase deficiency and died of respiratory failure at age 27. Acid maltase deficiency may have heterogeneous presentations within a family, and adult AMD can present as a scapuloperoneal neuromuscular syndrome.

Vacuolar myositis with expression of both MHC class I and class II antigens on skeletal muscle fibers

We describe here a 10-year-old patient with high levels of serum IgE and inflammatory myopathy whose muscle fibers exhibit excessive autophagy. Previous studies have demonstrated surface expression of class I MHC antigens on muscle fibers from patients with inflammatory myopathy. The muscle fibers of this patients showed marked expression of both class I and class II MHC antigens. The reaction products were demonstrated not only on sarcolemma but also in and around some vacuoles. Both CD4-positive and CD8-positive T-lymphocytes were noted in inflammatory exudates surrounding these fibers but B-lymphocytes were rare. We hypothesize that myocyte expression of both class I and class II antigens may play a role in the pathogenesis of this new type of inflammatory myopathy.

Japanese quail and human acid maltase deficiency: a comparative study

A morphological study was carried out on the skeletal muscle of a mutant Japanese quail with acid maltase deficiency (AMD). The affected quails began to experience difficulty in lifting their wings about 6 weeks after hatching. Four weeks after hatching, before symptoms appeared, alpha-1, 4-glucosidase activity in skeletal muscle was decreased to less than 10% of the control level, and muscle fibers possessed many vacuoles containing periodic acid Schiff (PAS) positive material which was digested by diastase, and showed high acid phosphatase activity. Although both red and white muscles were involved, the pectoralis superficialis (PS, white) muscle was preferentially affected, showing intracytoplasmic vacuoles, variation in fiber size and fatty tissue replacement relatively early in the disease. The quails' disease closely resembled human late onset AMD in the slow clinical course, the presence of residual acid alpha-glucosidase activity and the muscle pathology. This mutant quail seems a useful model for elucidation of the muscle degeneration in human AMD (glycogen storage disease type 2).

Aneurysms and vacuolar degeneration of cerebral arteries in late-onset acid maltase deficiency

We present a case of late-onset acid maltase deficiency (AMD) with pronounced involvement of the liver and skeletal muscles. In addition, and in contrast to other adult cases of AMD, the case presented here shows CNS pathology with hypodense and hyperintense white matter areas on CT and MRI scans, and myelin changes ranging from focal areas of demyelination to necrosis. Neuropathologic changes seem to be related to unusual vascular pathology consisting of vacuolar degeneration of small and large arterial blood vessels. Vacuoles of varying size, partly filled with granular PAS-positive material, were found in pericytes and smooth muscle cells of arterial vessel walls. Electron microscopy revealed lysosomal and cytoplasmic free glycogen in smooth muscle cells in the intima of large cerebral arteries as well as in pericytes of arterioles and capillaries. Accumulation of glycogen locally was associated with severe cellular damage and necrosis. The formation of a great number of small aneurysms of intracerebral arteries is thought to be the result of cell damage in the vessel walls.

Clinical heterogeneity and treatment response in inclusion body myositis

Inclusion body myositis has been described as an inflammatory myopathy with distinctive clinical and pathologic features that is refractory to treatment. Ten cases of inclusion body myositis, as defined by histopathologic findings, were reviewed to determine whether the clinical characteristics are different in patients whose disease has been defined by light and electron microscopic studies compared with those whose disease has been defined by light microscopic studies alone. The clinical characteristics of both groups of patients were similar, and 2 patients have had excellent responses to treatment. Although inclusion body myositis represents a histologic subset of polymyositis, from a clinical perspective, it must be considered a nonspecific designation. Despite a generally poor prognosis, therapeutic intervention is still warranted.

Late-onset acid maltase deficiency associated with intracranial aneurysm

The autopsy findings in a patient with late-onset acid maltase deficiency who died following rupture of a basilar artery aneurysm are reported. The patient developed muscular weakness and wasting at the age of 20 years and died 9 years later after suddenly falling into a coma. At autopsy a giant fusiform aneurysm was found in the basilar artery which had ruptured at the base of the pons, leading to a large haematoma in the pons. The cerebral arteries and arterioles showed extensive vacuolar degeneration of smooth muscle cells in the media. It is suggested that the aneurysm was induced by fragility of the arterial wall due to this smooth muscle change.

Km mutant of acid alpha-glucosidase in a case of cardiomyopathy without signs of skeletal muscle involvement

A male patient is reported with a mutation of acid alpha-glucosidase causing an altered Km toward natural substrates. Cardiac arrhythmia was found at 12 years of age, and he died of heart failure at 15 years. No skeletal muscle involvement was observed either clinically or histologically. Acid alpha-glucosidase activity in fibroblasts was moderately low (43% of the control mean) with normal Km for 4-methylumbelliferyl alpha-D-glucoside. The hydrolysis of glycogen was markedly decreased (14% of the control mean), and the Km for maltose was increased 4-fold and for glycogen 5-fold. The biosynthesis and the posttranslational processing of the mutant enzyme appeared normal, but the total amount of the enzyme was lower than normal. This mutant enzyme comigrated with normal acid alpha-glucosidase on starch gel electrophoresis, and not with the rare isozyme, acid alpha-glucosidase 2. A possible role of this mutant enzyme in the pathogenesis of this disease and the relationship to glycogenesis II are discussed.

X-linked myopathy with excessive autophagy: a new hereditary muscle disease

We report on 3 brothers with a myopathy that also affected their maternal grandfather and great-uncle. Characteristic features are onset in early childhood, very slow progression, normal life expectancy, weakness of proximal limb muscles, especially in the legs, elevation of serum creatine kinase, and no cardiac or intellectual involvement. In biopsy material muscle fibers are almost never necrotic but show excessive autophagic activity and exocytosis of the phagocytosed material. We suggest that this family has an undescribed type of congenital myopathy, for which we propose the name X-linked myopathy with excessive autophagy.

The pattern of involvement of adult-onset acid maltase deficiency at autopsy

The autopsy findings in a clinically and biochemically documented case of adult-onset acid maltase deficiency presenting with limb girdle myopathy are presented. The skeletal muscles, tongue, extraocular and smooth muscles of gut and arterioles showed a vacuolar myopathy, most severely affecting proximal skeletal muscles. Muscle spindles were severely affected in all muscles. The heart showed basophilic degeneration and a vacuolar myopathy. The visceral organs and nervous system were morphologically normal. Possible mechanisms for this differential involvement of muscles and tissues are discussed.

Acid maltase deficiency in the Japanese quail; early morphological event in skeletal muscle

The skeletal muscle of Japanese quails with acid maltase deficiency (AMD) was studied morphologically at various developmental stages, from the 16th embryonal day up to 3 months after hatching. Membrane-bound glycogen particles began to appear in the affected skeletal muscle at the 16th embryonal day. In normal embryonic muscles, a certain amount of free glycogen particles was observed but they were not membrane-bound. Therefore, this is the earliest morphological event in the muscle of Japanese quails with AMD. In muscle at 3 weeks after hatching, the initial focal degeneration of myofibrils was recognizable but it was not associated with autophagic vacuoles. Quails with AMD developed muscle weakness and difficulty in lifting their wings at about 3 months after hatching: then numerous autophagic vacuoles were present. The formation of large autophagic vacuoles followed by fiber loss and fatty replacement seemed to contribute to the progressive muscle weakness. The study of Japanese quail with AMD will greatly facilitate the elucidation of the pathogenetic mechanism and is also a useful model for therapeutic trials in human AMD.

Lysosomal storage in human skeletal muscle

Skeletal muscle is involved symptomatically in two lysosomal storage diseases, acid maltase deficiency and a similar condition in which enzyme levels are normal. Asymptomatic storage in skeletal muscle cells is found in Batten-Kufs' disease (ceroid lipofuscinosis), Fabry's disease, and mannosidosis, as well as in rare patients with an unidentified storage disease. Other cell types (vascular endothelium, smooth muscle, fibroblasts, satellite cells) within the confines of the biopsy specimen may reveal storage in other diseases. The differential diagnosis involves predominantly both normal and abnormal conditions in which acid phosphatase activity is prominent in cells.

Adult onset acid maltase deficiency. Distribution and progression of clinical and pathological abnormality in a family

The adult onset form of acid maltase deficiency (Type IIb) clinically affects only skeletal muscle. Proximal weakness is more severe in legs than arms and involvement of respiratory muscles is prominent in about a third of the cases. In three siblings with the disease, the severity of limb weakness was related to age and duration of disease. Respiratory muscle involvement was a feature in two of the patients. The pathological abnormality was more marked in quadriceps than deltoid, and was strikingly patchy in distribution within these muscles. In one case, vacuolar change was not evident by light microscopy in two quadriceps biopsies taken 2 years apart. There is thus a spectrum of clinical and pathological expression of the disorder even in a single sibship.

Comparative pathology of the canine model of glycogen storage disease type II (Pompe's disease)

The pathology of canine glycogen storage disease type II (acid alpha-glucosidase deficiency, GSD II) was studied in three genetically related Lapland dogs and compared to the pathology of human GSD II (McKusick 23230). Canine GSD II closely parallels the infantile form of the human disease, except for the presence of oesophageal dilatation. Generalized glycogen storage particularly affected muscular tissues (skeletal, oesophageal, cardiac and smooth muscle). The altered cells showed glycogen accumulation in the cytosol and in autophagic membrane-bound vacuoles (glycogenosomes). They also showed increased acid phosphatase activity consistent with the lysosomal nature of this storage disorder. The cytopathology in canine and human GSD II appears to evolve from segregation of glycogen during regular cellular autophagy, phagolysosomal accumulation of the undigested glycogen, and eventually rupture of distended glycogenosomes. This study indicates that the usefulness of canine GSD II as an animal model of human disease, extends to the area of pathogenesis.

Respiratory failure as initial symptom of acid maltase deficiency

Nine patients with adult onset acid maltase deficiency were seen at the Nijmegen University Hospital and the St Elisabeth Hospital, Tilburg , during the period 1970-1982. Five of these patients developed respiratory failure, and in four this was the initial symptom. The occurrence of respiratory failure as an early symptom of this muscular disease is discussed.

Myopathy due to juvenile acid maltase deficiency affecting exclusively the type I fibres

The clinical and laboratory findings of a patient with juvenile acid maltase deficiency are presented. The patient died from respiratory muscle weakness at age 31 years. Muscle biopsy shortly prior to his death showed remarkable vacuolation affecting exclusively type I fibres and mild myopathic changes of both types of muscle fibres, while the muscle biopsy at age 26 years had shown no evidence of acid maltase deficiency.

Acid maltase deficiency: treatment of respiratory insufficiency with cuirass respirator

Three patients with the late-onset form of acid maltase deficiency showed a gradual weakening of proximal limb and trunk muscles leading to severe respiratory insufficiency. Considerable deterioration of pulmonary function occurred owing to a vicious cycle of hypoventilation and exhaustion. Treatment by nocturnal cuirass ventilation with tailor-made shells was successful. The muscle weakness still progressed very slowly but there were no more respiratory problems.

Inclusion body myositis. Clinical, biological and ultrastructural study

A 48-year-old patient presented for the past 4 years an amyotrophy of the quadriceps and moderate involvement of the truncal and pelvic girdle muscles. The CK level was elevated (10 times the normal rate) and the EMG revealed a fibrillation pattern on relaxation, myotonic bursts on needle insertion and reduced activity during contraction. The histological study of the muscle biopsy showed nuclear cytoplasmic inclusion bodies and pseudo-myelinic membranes. The case was classified in the inclusion body myositis group. Analysis of the other published cases underlines the variety of the clinical, biological and electromyographical aspects and abnormalities.

Changes in nervous tissue in bovine generalized glycogenosis type II

Generalized Glycogenosis type II has been diagnosed in seven calves from a herd of cattle maintained at the Murdoch University Veterinary School Farm. The syndromes seen are equivalent to the infantile and childhood forms of the disease in humans. In the brain and spinal cord of the calves acid alpha-glucosidase activity was depressed and glycogen deposition was markedly increased. Swelling, vacuolation and glycogen deposition was present in neurones of the central and autonomic nervous systems and retina, in glia and in Schwann cells and fibroblasts within peripheral nerves. The distribution was similar to that seen in human cases. The glycogen was both membrane bound and free within the cytoplasm. Changes similar to those seen in axonal dystrophy were present and some nerve fibres showed Wallerian degeneration. Evidence of nerve cell destruction and nerve cell loss were not seen and the predominant clinical signs were related to muscle weakness.

Cylindrical spirals in human skeletal muscle

Muscle biopsies from two patients revealed that numerous type 2 fibers contained large abnormal areas filled with cylindrical spirals. The cytochemical profile of these cylindrical spirals was sufficiently characteristic that they could be distinguished from tubular aggregates. Their electron microscopic appearance was unmistakable. Their origin and significance are uncertain. The diverse nature of the patients' conditions (cramps and malignancy, and an unusual form of spinocerebellar degeneration) indicate that these abnormal structures are not disease specific.

Adult-onset acid maltase deficiency: a postmortem study

In a postmortem study of a patient with adult-onset acid maltase deficiency (AMD), morphological abnormalities were confined to skeletal muscle and consisted of a vacuolar myopathy. Acid maltase activity, however, was approximately 6% of normal in muscle, liver, and brain, and 3% of normal in heart. Kinetic characteristics, and inhibition by antibodies and Zn++, showed that the residual activity was "authentic" acid maltase. Neutral maltase activity was normal in muscle and liver, but decreased in brain (55% of normal) and heart (19% of normal). Although the relative decrease of acid maltase was similar in different tissues, absolute residual activity was lowest in skeletal muscle: this may explain the selective involvement of this tissue in late-onset AMD.