Is muscle glycogenolysis impaired in X-linked phosphorylase b kinase deficiency?

OBJECTIVE

It is unclear to what extent muscle phosphorylase b kinase (PHK) deficiency is associated with exercise-related symptoms and impaired muscle metabolism, because 1) only four patients have been characterized at the molecular level, 2) reported symptoms have been nonspecific, and 3) lactate responses to ischemic handgrip exercise have been normal.

METHODS

We studied a 50-year-old man with X-linked PHK deficiency using ischemic forearm and cycle ergometry exercise tests to define the derangement of muscle metabolism. We compared our findings with those in patients with McArdle disease and in healthy subjects.

RESULTS

Sequencing of PHKA1 showed a novel pathogenic mutation (c.831G>A) in exon 7. There was a normal increase of plasma lactate during forearm ischemic exercise, but lactate did not change during dynamic, submaximal exercise in contrast to the fourfold increase in healthy subjects. Constant workload elicited a second wind in all patients with McArdle disease, but not in the patient with PHK deficiency. IV glucose administration appeared to improve exercise tolerance in the patient with PHK deficiency, but not to the same extent as in the patients with McArdle disease. Lipolysis was higher in the patient with PHK deficiency than in controls.

CONCLUSION

These findings demonstrate that X-linked PHK deficiency causes a mild metabolic myopathy with blunted muscle glycogen breakdown and impaired lactate production during dynamic exercise, which impairs oxidative capacity only marginally. The different response of lactate to submaximal and maximal exercise is likely related to differential activation mechanisms for myophosphorylase.

Symptomatic distal myopathy with cardiomyopathy due to a MYH7 mutation

Mutations in the myosin heavy chain gene (MYH7) can cause several distinct phenotypes depending on the location of the mutation: hypertrophic cardiomyopathy (several exons), myosin storage myopathy (exon 37/39) or Laing distal myopathy (exons 32-36). Here, we describe a unique combination of hypertrophic cardiomyopathy and hypertrophic distal myopathy in a family with a MYH7 Val606Met mutation (exon 16).

Relation between muscle fiber conduction velocity and fiber size in neuromuscular disorders

To determine the relation between muscle fiber conduction velocity (MFCV) and muscle fiber diameter (MFD) in pathological conditions, we correlated invasively measured MFCV values with MFD data obtained from muscle needle biopsies in 96 patients with various neuromuscular disorders. MFCV was significantly correlated with MFD and independent of the underlying disorder. Pathological diameter changes were fiber-type dependent, with corresponding MFCVs. A linear equation expresses the relation well: MFCV (m/s) = 0.043·MFD (μm) + 0.83. We conclude that fiber diameter determines MFCV largely independent of the underlying neuromuscular disorders studied.

Anti-signal recognition particle autoantibodies: marker of a necrotising myopathy

OBJECTIVE

To elucidate the clinical importance of the anti-signal recognition particle (SRP) autoantibody in patients with myositis.

METHODS

Retrospective systematic assessment of the clinical, laboratory and histological characteristics of 23 anti-SRP-positive patients from six European centres. Data were compared with a large group of anti-SRP-negative patients with myositis published previously.

RESULTS

Clinically, patients with anti-SRP autoantibodies often had a severe symmetric proximal muscle weakness resulting in marked disability, dysphagia and highly elevated levels of serum creatine kinase. Three patients had typical dermatomyositis rashes. The disease was associated with the occurrence of extramuscular signs and symptoms including interstitial lung disease. No association was found with an increased risk of cardiac involvement, and the disease carried a reasonably favourable prognosis with most patients responding to treatment. None of the patients had the typical histological features of myositis. Most muscle biopsy specimens showed the presence of necrotic muscle fibres and no inflammatory infiltrates.

CONCLUSIONS

Anti-SRP autoantibodies are associated with a syndrome of a necrotising myopathy in the spectrum of immune-mediated myopathies that differs from typical polymyositis. Further studies are needed to elucidate the pathogenesis and to clarify the role of the anti-SRP autoantibodies in this unique disease.

Hypovitaminosis D-related myopathy in immigrant teenagers

INTRODUCTION

Vitamin D deficiency resulting in a limb-girdle muscle weakness was diagnosed in three veiled immigrant teenage girls.

PATIENTS

Three girls had a progressive muscle weakness and pain during a period varying from 6 months to two years. On examination limb girdle muscle weakness, predominantly of the lower extremities, without other neurological abnormalities was found. Serum examination showed a decreased level of vitamin D and phosphate and an increased alkaline phosphatase, and in two girls decreased calcium and increased parathyroid hormone levels were found. After supplementation with vitamin D, the pain subsided and muscle strength increased within weeks. Serum examination of the female relatives revealed eight persons with hypovitaminosis D, without any complaints.

CONCLUSIONS

Vitamin D deficiency can result in a limb-girdle myopathy in veiled immigrant teenagers in the Netherlands. Vitamin D supplementation leads to rapid recovery of the muscle strength. The female relatives of these patients should be examined too.

Autosomal recessive oculopharyngodistal myopathy: a distinct phenotypical, histological, and genetic entity

We present a 25 year follow up of two siblings with autosomal recessive (AR) oculopharyngodistal myopathy. Remarkable in these patients, in comparison with patients with oculopharyngeal muscular dystrophy (OPMD), are the earlier age of onset, severe facial weakness, external ophthalmoplegia early in the course of the disease, and distal weakness in the limbs. Histological features included basophilic-rimmed vacuoles, but the typical OPMD intranuclear filaments were absent. These clinical and histological characteristics are comparable with those of two Japanese patients with AR oculopharyngodistal myopathy. This myopathy has usually been described as an autosomal dominant (AD) muscle disorder. It shares some clinical and histological characteristics with OPMD, but most patients with AD oculopharyngodistal myopathy are genetically different. Here we exclude an expansion of the GCG repeat or any other mutation in the coding region of the PABPN1 gene (responsible for OPMD) in patients with AR oculopharyngodistal myopathy. From this we conclude that AR oculopharyngodistal myopathy is a distinct phenotypical, histological, and genetic entity.

Diagnostic value of MHC class I staining in idiopathic inflammatory myopathies

BACKGROUND

Identification of mononuclear cellular infiltrates in skeletal muscle tissue is the histological cornerstone of the diagnosis of idiopathic inflammatory myopathy (IIM). However, these infiltrates are not always present.

OBJECTIVE

To determine whether MHC class I antigen expression on the sarcolemma, which is absent in normal muscle tissue, is upregulated in IIM and could serve as an additional diagnostic test.

METHODS

Expression of MHC class I antigens was studied in 224 muscle samples of 61 adult patients with IIM (9 dermatomyositis, 23 polymyositis, 29 inclusion body myositis) and 163 controls (normal subjects and patients with various neuromuscular disorders) in a prospective blinded manner.

RESULTS

The sensitivity of the test for diagnosing IIM was 78% (95% confidence interval (CI), 66% to 88%), with a specificity of 95% (91% to 98%). The sensitivity before the start of immunosuppressive treatment was 89% (76% to 96%). The sensitivity was not changed by including all patients who had been on immunosuppressive treatment for less than four weeks before muscle biopsy (sensitivity 90% (79% to 97%)). False positive results were found in only seven controls (4%), six of whom had a muscular dystrophy.

CONCLUSIONS

Detection of sarcolemmal MHC class I is a valid test for IIM. It is not affected by the short term use of immunosuppressive agents (less than four weeks) and it should be incorporated in the histological evaluation when the diagnosis of IIM is under consideration or needs to be excluded.

A locus on chromosome 15q for a dominantly inherited nemaline myopathy with core-like lesions

Nemaline myopathy is a congenital neuromuscular disorder characterized by muscle weakness and the presence of nemaline rods. Five genes have now been associated with nemaline myopathy: alpha-tropomyosin-3 (TPM3), alpha-actin (ACTA1), nebulin (NEB), beta-tropomysin (TPM2) and troponin T (TNNT1). In addition, mutations in the ryanodine receptor gene (RYR1) have been associated with core-rod myopathy. Here we report linkage in two unrelated families, with a variant of nemaline myopathy, with associated core-like lesions. The clinical phenotype consists of muscle weakness in addition to a peculiar kind of muscle slowness. A genome-wide scan revealed a locus for nemaline myopathy with core-like lesions on chromosome 15q21-q23 for both families. Combining the two families gave a two-point LOD score of 10.65 for D15S993. The alpha-tropomyosin-1 gene (TPM1) located within this region is the strongest candidate gene. However, no mutations were found in the protein-coding region of TPM1, although small deletions or mutations in an intron cannot be excluded. The critical region contains few other candidate genes coding for muscle proteins and several genes of unknown function, and has not yet been sequenced completely. The novel phenotype of nemaline myopathy in the two presented families corresponds to an also novel, as yet uncharacterized, genotype.

A new phenotype of autosomal dominant nemaline myopathy

We present a five-generation family with a novel phenotype of autosomal dominant nemaline myopathy not linked to the three genes known to be causative for nemaline myopathy (alpha-tropomyosin-3, nebulin, and alpha-actin). Although there was muscle weakness in the neck flexors and proximal muscles of the limbs, as found in other families, facial, ankle dorsiflexor and respiratory muscles were normal. The most remarkable clinical feature was a peculiar kind of slowness in movement not reported previously in nemaline myopathy.

Congenital fibre type disproportion a time-locked diagnosis: a clinical and morphological follow-up study

This is the first report that describes the clinical and histological findings in a patient suffering from pure congenital fibre type disproportion (CFTD), who had two biopsies with an interval of 16 years. Additionally, we compared the clinical signs and symptoms of the present case to those of 35 CFTD cases reviewed from the literature. From this we conclude that smallness of type I fibre diameter is not a characteristic feature during the course of pure CFTD. This suggests that CFTD is a time-locked diagnosis.

Genetic characteristics of myoadenylate deaminase deficiency

Two types of myoadenylate deaminase (MAD) deficiency have been described, primary or inherited, and secondary or acquired MAD deficiency. In this study, we investigated whether secondary MAD deficiency is indeed acquired or merely coincidental. We demonstrated the same underlying molecular defect, a C34T transition, in both types of deficiency. Furthermore, the same frequency of the mutant MAD allele was found in the general population as in patients with neuromuscular complaints. We therefore conclude that in the Dutch population, secondary MAD deficiency is merely a "coincidental" finding, and that MAD deficiency is a harmless genetic variant.

Complex regional pain syndrome type I (RSD): pathology of skeletal muscle and peripheral nerve

BACKGROUND

Reflex sympathetic dystrophy (RSD) (recently reclassified as complex regional pain syndrome type I) is a syndrome occurring in extremities and, when chronic, results in severe disability and untractable pain. RSD may be accompanied by neurologic symptoms even when there is no previous neurologic lesion. There is no consensus as to the pathogenic mechanism involved in RSD. To gain insight into the pathophysiology of RSD, we studied histopathology of skeletal muscle and peripheral nerve from patients with chronic RSD in a lower extremity.

METHODS

In eight patients with chronic RSD, an above-the-knee amputation was performed because of a nonfunctional limb. Specimens of sural nerves, tibial nerves, common peroneal nerves, gastrocnemius muscles, and soleus muscles were obtained from the amputated legs and analyzed by light and electron microscopy.

RESULTS

In all patients, the affected leg showed similar neurologic symptoms such as spontaneous pain, hyperpathy, allodynia, paresis, and anesthesia dolorosa. The nerves showed no consistent abnormalities of myelinated fibers. In four patients, the C-fibers showed electron microscopic pathology. In all patients, the gastrocnemius and soleus muscle specimens showed a decrease of type I fibers, an increase of lipofuscin pigment, atrophic fibers, and severely thickened basal membrane layers of the capillaries.

CONCLUSION

In chronic RSD, efferent nerve fibers were histologically unaffected; from afferent fibers, only C-fibers showed histopathologic abnormalities. Skeletal muscle showed a variety of histopathologic findings, which are similar to the histologic abnormalities found in muscles of patients with diabetes.

Laminin-alpha2 (merosin), beta-dystroglycan, alpha-sarcoglycan (adhalin), and dystrophin expression in congenital muscular dystrophies: an immunohistochemical study

Muscle biopsies of 13 congenital muscular dystrophy (CMD) patients were investigated for the expression of laminin-alpha2 (merosin), beta-dystroglycan, alpha-sarcoglycan (adhalin) and dystrophin. Expression of these proteins was normal in six out of eight patients with pure-CMD, in three non-Japanese patients clinically resembling Fukuyama-CMD (F-CMD), and in two patients with Walker-Warburg syndrome (WWS). The two 'pure'-CMD patients with white matter hypodensity showed severely decreased laminin-alpha2 expression and normal expression of the other proteins. Our findings in the non-Japanese patients, clinically resembling F-CMD, are different from those in Japanese cases with F-CMD in the literature. Consequently, our patients suffer from WWS or from another yet undetermined form of CMD.

Favourable clinical course in an infant with severe deficiency of complex III of the respiratory chain combined with less severe deficiencies of complexes I, II and IV

An infant with severe deficiency of complex III combined with less severe deficiencies of complexes I, II and IV of the mitochondrial respiratory chain in skeletal muscle tissue presented with intra-uterine growth retardation, generalized hypotonia and delayed motor development. In the following 3.5 years muscle tone and motor development gradually normalized whereas the lactic acidosis and enzyme activities did not improve.

CONCLUSION

This report documents a favourable clinical course in a child with combined respiratory chain deficiency despite persistent biochemical abnormalities.

Multicore myopathy with restrictive cardiomyopathy

A 10-y-old girl is presented who suffered mild muscular weakness and exercise intolerance from the age of 1 y onwards, with progression appearing from the age of about 8 y. Multicore myopathy and restrictive cardiomyopathy were diagnosed. Literature concerning the coexistence of multicore myopathy and cardiomyopathy is reviewed.

Soft tissue repair capacity after oxygen-derived free radical-induced damage in one hindlimb of the rat

Oxygen-derived free radicals are suspected to play an important role in the pathogenesis of inflammation and ischemia/reperfusion of an extremity. In this study we investigated the repair capacity of a free radical-damaged hindlimb of the rat and the effect of the anti-oxidant N-acetyl-L-cysteine (NAC). In nonanesthetized rats (n = 39), the left hindlimb was continuously infused intra-arterially (1 ml/hr) for 24 hr with the free radical donor tert-butylhydroperoxide (tert-BuOOH, 25 mM). Subsequently the infusion system was disconnected and the repair of soft tissue damage was observed with special attention to various pain tests, vascular permeability ((99m)Tc-IgG scintigraphy), and histology for a maximum period of 6 weeks. In 12 of these tert-BuOOH-infused rats the antioxidant NAC was injected intraperitoneally. Six of the NAC-treated rats were killed after 24 hr of infusion, while the remaining 6 rats were disconnected, reinjected with NAC, and observed for 1 week. Tert-BuOOH infusion for 24 hr led to significantly increased pain sensations, vascular permeability, and histological damage. Treatment with NAC significantly reduced pain sensations and vascular permeability, though not to control levels. One week after disconnection, tissue damage was almost completely repaired in the NAC-treated rats. In the untreated rats, repair took longer but histology and vascular permeability were completely normalized within the observation period. Soft tissue damage, induced by 24-hr infusion of the free radical donor tert-BuOOH, showed spontaneous repair within 6 weeks. The antioxidant NAC significantly reduced the soft tissue damage and shortened the repair period.

Myopathology in patients with a Noonan phenotype

Two patients with a Noonan phenotype and progressive hypertrophic obstructive cardiomyopathy are described, in whom abnormal histopathological changes in striated musculature were detected. In both patients an increased density of muscle spindles was found at biopsy. The significance of an increased density of muscle spindles in patients with Noonan phenotype can only be speculated. The question is raised of whether these changes are a distinct feature within the spectrum of patients with Noonan phenotype.

Congenital muscular dystrophy: a review of the literature

Congenital muscular dystrophy (CMD) is a condition in which there are already at birth, marked hypotonia, generalized muscle weakness and frequently multiple contractures. CMD has recently been classified into four categories: CMD I, the classical or "pure' CMD without severe impairment of intellectual development; CMD II, the Fukuyama type CMD with muscle and structural brain abnormalities; CMD III and IV with muscle, eye and brain abnormalities; the milder Finnish type CMD (CMD III) and the severe Walker-Warburg syndrome (CMD IV). Data of the literature concerning those different CMD types have been reviewed and are presented with emphasis on signs and symptoms, clinical course, laboratory, neurophysiological, radiological, morphological and genetic characteristics.

Lethal infantile mitochondrial disease with isolated complex I deficiency in fibroblasts but with combined complex I and IV deficiencies in muscle

A 2-month-old boy died of a lethal infantile mitochondrial disease with severe lactic acidosis and involvement of the CNS. Histochemical analysis of skeletal muscle showed that cytochrome c oxidase staining was lacking in all muscle fibers but was present in arterioles. Ragged red fibers were not seen, but some fibers showed excessive staining for succinate dehydrogenase. Biochemical analysis revealed a combined complex I and IV deficiency in skeletal muscle but only a complex I deficiency in his fibroblasts. Two-dimensional native SDS electrophoresis confirmed these enzymatic findings at the protein level. Analysis of mitochondrial translation products in fibroblasts revealed no abnormalities, and analysis of mitochondrial DNA in muscle showed no depletion, large-scale deletions, or frequently occurring point mutations. We conclude that this disease must have been the result of either a nuclear DNA mutation in a gene controlling the expression or assembly of both complex I and the muscle-specific isoform of complex IV or, alternatively, a heteroplasmic point mutation in a mitochondrial tRNA, which codon is used more often by mtDNA encoded subunits of complex I than by mtDNA encoded subunits of complex IV. A different degree of heteroplasmy in skeletal muscle and fibroblasts would then explain the curious heterogeneous tissue expression of defects in this patient.

Deficiency of the voltage-dependent anion channel: a novel cause of mitochondriopathy

A patient with a deficient voltage-dependent anion channel (VDAC) is reported, presenting clinically with psychomotor retardation and minor dysmorphic features. Biochemical studies on muscle mitochondria showed impaired rates of pyruvate oxidation and ATP production; however, no specific deficient activity of one of the mitochondrial enzymes was involved. Western blotting experiments indicated an almost complete VDAC deficiency in skeletal muscle. The only moderately decreased VDAC content in the patient's fibroblasts might indicate that VDAC is expressed in a tissue-specific manner. The deficiency is likely caused by a mutation in the HVDAC1 gene or by a distributed posttranslational modification. This is the first described deficiency of a component of the outer mitochondrial membrane associated with the pyruvate oxidation pathway. Defects in this membrane should be considered as a possible cause of otherwise unexplained mitochondrial disorders.

Congenital muscular dystrophy and severe central nervous system atrophy in two siblings

Severe degenerative features of the nervous system of a hitherto unknown kind, associated with a neuromuscular disorder with histopathological features of congenital muscular dystrophy, are reported in two female siblings. The clinical profile was characterized by generalized hypotonia followed by spastic tetraplegia, contractures, polyneuropathy, lack of cognitive development and progressive microcephaly. There as no involvement of the eyes. Neuropathological examination of the brain of one sibling, who died at the age of 30 months, revealed subtotal loss of neurons in the cerebral and cerebellar cortex and in the ventral pons, and secondary loss of myelin in the cerebral and cerebellar subcortical white matter. Sural nerve biopsy in the other sibling, who had a similar neurological affection, showed a lack of large myelinated fibers.

White matter abnormalities in congenital muscular dystrophy

Central nervous system (CNS) characteristics were examined in seventeen patients with autosomal recessive classic or "pure" congenital muscular dystrophy (CMD). In three patients, neuroradiological examination (CT/MRI) indicated hypodense white matter areas. Two out of these three patients had epilepsy (seizures and epileptic discharges on their EEG). Only two of the remaining patients had epileptic EEG discharges, but without clinical seizures. By comparing our results to data in the literature, we could conclude that the classic or "pure" form of CMD can be subdivided into two subtypes, i.e. those with and those without white matter hypodensities. A mild form of epilepsy or an epileptic predisposition on EEG can be part of the subtype with white matter hypodensities.

Immunophenotyping of congenital myopathies: disorganization of sarcomeric, cytoskeletal and extracellular matrix proteins

We have studied the expression and distribution patterns of the intermediate filament proteins desmin and vimentin, the sarcomere components titin, nebulin and myosin, the basement membrane constituents collagen type IV and laminin, and the reticular layer component collagen type VI in skeletal muscle of patients with "classic" congenital myopathies (CM), using indirect immunofluorescence assays. In all biopsy specimens obtained from patients with central core disease (CCD), nemaline myopathy (NM), X-linked myotubular myopathy (XLMTM) and centronuclear myopathy (CNM), disease-specific desmin disturbances were observed. Vimentin was present in immature fibres in severe neonatal NM, and as sarcoplasmic aggregates in one case of CNM, while the amounts of vimentin and embryonic myosin, observed in XLMTM, decreased with age of the patients. Abnormal expression of myosin isoforms was found in several CM biopsies, although the organization of myosin and other sarcomere components was rarely disturbed. Basement membrane and reticular layer proteins were often prominently increased in severe cases of CM. We conclude that (i) desmin is a marker for individual types of CM and might be used for diagnostic purposes; (ii) the expression patterns of the differentiation markers desmin, vimentin and embryonic myosin in XLMTM, point either to a postnatal muscle fibre maturation or to a variable time-point of maturational arrest in individual patients; (iii) the correlation between the distribution patterns of extracellular matrix proteins and clinical presentation points to a role of these proteins in pathophysiology of CM.

Coxsackie B1 virus-induced murine myositis: a correlative study of muscular lesions and serological changes

We investigated the role of humoral factors in the pathogenesis of Coxsackie B1 virus-induced murine myositis (CB1-myositis). At 2, 4 and 8 weeks after inoculation, serum was studied for circulating immune complexes (CIC) (Raji-cell assay), haemolytic complement activity (CH50 titre) and anticytoplasmic autoantibodies (Western blotting, immunoprecipitation) in relation to degree of mononuclear cell infiltration and muscle fibre necrosis. At 2, 4 and 8 weeks, cell infiltration correlated positively to muscle fibre necrosis. From 2 weeks on, moderate quantities of CIC were found in nearly all CB1-inoculated mice, but without correlation to histological changes. Except for a positive correlation of CH50 titre to muscle necrosis at 4 weeks (r = 0.60; P = 0.02), CH50 titres did not correlate to muscle lesions. Anticytoplasmic and other known autoantibody specificities were absent. In conclusion, first, in CB1-myositis CIC occurred from 2 weeks on, but no correlative evidence was found for their involvement in pathogenesis, neither for that of complement nor for anticytoplasmic autoantibodies. Secondly, cell infiltration correlated positively to muscle necrosis, underscoring the importance of cellular mechanisms. Thus, our data do not support, or conclusively exclude, a role for humoral processes in CB1-myositis.

Coxsackie B1 virus-induced murine myositis: relationship of disease severity to virus dose and antiviral antibody response

Inoculation of Coxsackie B1 virus (CB1) in newborn CD1 Swiss mice induces a chronic myositis of proximal hindlimb muscles (CB1 myositis). To study the possible role of the virus dose, and of antiviral antibodies in the development of CB1 myositis, we infected groups of newborn mice with six CB1 doses, ranging from 30 to 10,000 plaque forming units (pfu); after 4 and 8 weeks we determined morbidity and antiviral antibody titer, and quantified histopathological changes. At 4 weeks, morbidity and mononuclear cell infiltration differed significantly for the various groups, with the most prominent changes in 300 pfu animals. At 4 and 8 weeks diseased animals had significantly higher antibody titers than clinically unaffected animals, and at 4 weeks myopathic and infiltrative changes correlated positively with the serum antibody titer. Our data indicate that the virus dose plays a pathogenic role in CB1 myositis, and they suggest further study on the role of humoral immune mechanisms in the early phase of CB1 myositis.

Myotonic dystrophy kinase is a component of neuromuscular junctions

The clinical manifestation of myotonic dystrophy (DM) is correlated to the extent of expansion of an unstable [CTG]n DNA motif. Recent studies have demonstrated that this trinucleotide motif forms part of the last, 3' untranslated exon of a gene which potentially encodes multiple protein isoforms of a serine/threonine protein kinase (myotonic dystrophy protein kinase, DM-PK). We report here on the development of antisera against synthetic DM-PK peptide antigens and their use in biochemical and histochemical studies. Immunoreactive DM-kinase protein of 53 kD is present at low levels in skeletal and cardiac muscle extracts of DM patients and normal controls. Immunohistochemical staining revealed that DM-PK is localised prominently at sites of neuromuscular and myotendinous junctions (NMJs and MTJs) of human and rodent skeletal muscles. Furthermore, very low levels of immunoreactive DM-PK protein are present in the sarcoplasm of predominantly type I fibres in various muscles. Strikingly, presence of the protein can also be demonstrated for NMJs of muscular tissues of adult and congenital cases of DM, with no gross changes in structural organisation. Our findings provide a basis for further characterisation of the role of the kinase in protein assembly processes or signal mediation at synaptic sites and ultimately for the understanding of the complex pathophysiology of DM.

Congenital muscular dystrophy. A study on the variability of morphological changes and dystrophin distribution in muscle biopsies

Histomorphological and histochemical variability was studied in muscle specimens from 30 patients with congenital muscular dystrophy (CMD). We found involvement of the central nervous system in 8 patients (Fukuyama CMD, F-CMD), involvement of the brain and the eyes in 5 patients (muscle, eye and brain disease, MEB-D) and hypodense white matter on the CT scans of 2 patients with (sub)normal intelligence (occidental-type cerebromuscular dystrophy, O-CMD). No morphological hallmarks were found to differentiate these subgroups. Only fat cell infiltration was found to be increased with increasing age in 'pure' CMD (pure-CMD). The morphological data did not appear to be correlated with the clinical severity or type of dystrophy (pure-CMD, F-CMD, MEB-D and O-CMD). Immunohistochemistry with dystrophin, vimentin and desmin antibodies in 14 patients (6 pure-CMD, 5 F-CMD, 2 MEB-D and 1 O-CMD) showed a normal expression pattern.

Dystrophic myopathy of the diaphragm in a neonate with severe respiratory failure during infectious episodes

In this study a boy is described who showed slight postnatal asphyxia related to isolated dystrophic diaphragmatic musculature. Development was complicated by several periods of bronchopneumonia necessitating artificial respiration each time.

Congenital muscular dystrophy with eye and brain malformations in six Dutch patients

From four Dutch families six patients, who have congenital muscular dystrophy, involvement of the central nervous system and of the eyes, or the so-called "muscle, eye and brain disease" (MEB-D), are reported. Two patients are still alive, in four autopsy could be performed. The clinical and morphological data of our patients are compared to those described in recent literature. The progression of the disease was rapid in five of our six patients. Our study supports the idea that within the MEB-D syndrome there are at least two different types of clinical expression, one with a rapid progression as described by Dobyns et al 1989 (9) and one with a slower progression as described in most patients of Santavuori et al 1989 (23). The study also confirms the autosomal recessive mode of inheritance of MEB-D.

Familial adult-onset muscular dystrophy with leukoencephalopathy

We report on 3 siblings with an adult-onset, predominantly distal muscle weakness. In the female index patient this was associated with epilepsy and a progressive spastic ataxic gait, while the 2 other siblings had no appreciable clinical nervous system involvement. Additional investigations revealed muscular dystrophy and leukoencephalopathy in all 3 siblings. We conclude that this familial adult-onset muscular dystrophy associated with leukoencephalopathy represents a newly recognized autosomal recessive syndrome.

Neuropathological findings in muscle-eye-brain disease (MEB-D). Neuropathological delineation of MEB-D from congenital muscular dystrophy of the Fukuyama type

Congenital muscular dystrophy (CMD) associated with cerebro-ocular dysplasia named muscle-eye-brain disease (MEB-D) is described in two sisters. Progressive hypotonia, mental retardation and severe visual failure appeared immediately after birth. Pathological examination demonstrated muscular dystrophy, hydrocephalus, type II lissencephaly and defective eye development of foetal origin. The great similarity of the clinical and neuropathological picture of both sisters is in agreement with an autosomal recessive inheritance. Neuropathological distinction between Fukuyama-CMD and MEB-D is a more severe and earlier cerebral developmental defect and the association with ocular dysplasia in MEB-D.

Force and fatigue in human type I muscle fibres. A surface EMG study in patients with congenital myopathy and type I fibre predominance

An isometric ischaemic intermittent m.biceps brachii exercise test is performed by 4 patients suffering from congenital myopathies which are characterized by a 100% type I fibre predominance, and by 26 healthy volunteers. Thirty contractions per minute are made at an 80% of maximal voluntary contraction level. It is found that type I muscle fibres have a fourfold lower force-generating capacity than type II muscle fibres. The EMG amplitude shows that more EMG voltage is needed per unit force in the patients with 100% type I fibres compared with controls. Under standardized fatiguing circumstances the power density frequency spectrum shows a weaker shift to lower frequencies in patients with 100% type I muscle fibres compared with controls. The muscle fibre conduction velocity (MFCV) of type I muscle fibres shows no decline during ischaemic exercise indicating an unimpaired muscle membrane excitability.

Fatigue in type I fiber predominance: a muscle force and surface EMG study on the relative role of type I and type II muscle fibers

The relative proportions of fiber types within muscle and the characteristics of these fiber types are important determinants of the surface electromyogram (SEMG) during fatigue. In this study, patients suffering from congenital myopathy characterized by a strong type I fiber predominance were studied. Six patients with 95-100% type I fibers, 2 patients with 80% type I fibers, and 12 healthy volunteers participated in an ischemic, isomeric, intermittent exercise test of m. quadriceps femoris at 80% MVC. Considering the results of the morphometric analysis of muscle biopsy specimen and of the anthropometric estimated muscle-bone volume, it was found that type I muscle fibers had a lower force generating capacity than type II fibers. The initial conduction velocity along the muscle fiber membrane (MFCV) was low in patients with 95-100% type I fibers. During the ischemic exercise test, the 95-100% type I fibers showed less fatigability than type II fibers, which was reflected by a nearby absent decrease of the muscle membrane excitability as measured by the MFCV, and only a slight increase of the SEMG amplitude compared with patients having 80% type I fibers and controls. The absence of a definite MFCV decrease was related to the nearby lacking lactate formation in 95-100% type I fibers.

MELAS syndrome. Report of two patients, and comparison with data of 24 patients derived from the literature

We present two unrelated MELAS patients, and compare them with 24 patients derived from the literature. In most patients the stroke-like features of the MELAS syndrome occur late in the course of the disease. The diagnosis is based on characteristic clinical symptoms, presence of lactic acidemia, mitochondriopathy in muscle, and low density lesions on cerebral CT, most frequently occurring in the posterior and parieto-temporal regions. In some cases, a metabolic defect could not be demonstrated, in other cases a partial deficiency of various respiratory chain enzymes was found.

Postnatal centralization of muscle fibre nuclei in centronuclear myopathy

Postnatal centralization of muscle fibre nuclei, which were previously located subsarcolemmally, is described in a case of centronuclear myopathy (CNM) in a male patient with generalized muscle weakness since birth. A muscle biopsy was taken at the age of 11 months; no particular abnormalities were observed at this stage apart from an unusual variation in fibre size. A distinctly below average muscle fibre diameter, increased endomysial connective tissue, and features typical for CNM were found in a biopsy taken 9 yr later. Immunohistochemical studies using antibodies to desmin, vimentin, laminin and type IV collagen revealed altered staining patterns compared with normal fibres. The abnormalities in the patterns of cytoskeletal proteins point to a defective regulation of the composition and organization of the cytoskeletal network during development, paralleled by abnormalities in the extracellular matrix.

Cell loss and shrinkage in the nucleus basalis Meynert complex in Alzheimer's disease

Marked neuron loss in the nucleus basalis of Meynert complex (NBMC) in Alzheimer's disease has repeatedly been reported in the literature. However, most of these studies quantitated only magnocellular, hyperchromatic (putative cholinergic) neurons of just a small part of the NBMC, and counts were expressed as numerical density. Applying a 3-dimensional-sampling design throughout the entire rostrocaudal extent of the NBMC and sampling neurons regardless of their size and staining characteristics, an overall neuron loss of only 15.5% was demonstrated for the whole NBMC. Neuron loss varied from 0% rostrally in the NBMC up to 36% in the most caudal part of the nucleus basalis of Meynert. Moreover, a significant increase in the number of small-sized neurons and a significant decrease in the number of large, putative cholinergic neurons could be detected, suggesting that apart from neuron loss neuron shrinkage appears to be another characteristic neuropathological feature of this degenerating cholinergic NBMC system. Preservation of these magnocellular cholinergic neurons in shrunken form renders it likely that cholinergic dysfunction, characteristic of Alzheimer's disease, may be responsive to neurotrophic influences.

Galanin-like immunoreactivity within Ch2 neurons in the vertical limb of the diagonal band of Broca in aging and Alzheimer's disease

The neuropeptide galanin is known to inhibit the evoked release of acetylcholine in ventral hippocampus of the rat. Co-localization of this peptide with choline acetyltransferase in neurons of the cholinergic septal nuclei has been demonstrated in the rat and non-human primate. The severe deficiency of the cholinergic hippocampal projection system arising mainly from the vertical limb nucleus of the diagonal band of Broca, also referred to as Ch2 region, is a constant finding in Alzheimer's disease, a disorder which is neuropathologically characterized by the appearance of senile plaques, neurofibrillary tangles and congophilic angiopathy in neo- and archicortical structures. In the present study for the first time galanin immunoreactivity in the human Ch2 region is morphologically investigated and related to the severity of hippocampal plaques and neurofibrillary tangles in Alzheimer's disease. An inverse relationship between decreasing galanin immunoreactivity in the Ch2 region and amounts of senile plaques and neurofibrillary tangles in the hippocampus is indicated. Considering the cholinergic deficiency in Alzheimer's disease as a secondary phenomenon to primary cortical and hippocampal lesions, and realizing the inhibitory effect of galanin upon acetylcholine release in hippocampus, this preliminary study suggests that a decreased galanin immunoreactivity in Ch2 in Alzheimer's disease, reflects a possible negative feedback mechanism to a degenerating cholinergic projection system.

Neuromuscular investigations in retinitis pigmentosa

Five patients with primary pigmentary dystrophy of the retina (retinitis pigmentosa) were tested on the integrity of their neuromuscular system. Clinical, electrophysiological and biochemical abnormalities were not found. A skeletal muscular biopsy was performed and histochemical, electron-microscopical and biochemical investigations were carried out. Only aspecific or minimal abnormalities were found. The mitochondrial functioning was especially explored and was found intact. Skeletal muscle examination is of no use in the study of retinitis pigmentosa.

The rigid spine syndrome

Four patients are reported, 3 females and 1 male, with (as a prominent symptom of muscle disease) limitation of flexion of cervical and dorsolumbar spine. The nosological classification of these cases is discussed. In two patients there was evidence of an inclusion body myositis. At necropsy one of these patients had a remarkable distribution of muscle changes.

Chronic inflammatory demyelinating polyneuropathy in two siblings

A familial occurrence of chronic inflammatory demyelinating polyneuropathy is reported. The diagnostic problems in distinguishing the progressive form of this disease in childhood from hereditary motor and sensory neuropathy types I and III are discussed. Criteria for a definite diagnosis of chronic inflammatory demyelinating polyneuropathy are proposed.

A mitochondrial encephalomyopathy: the first case with an established defect at the level of coenzyme Q

A patient is presented who had therapy-resistant epileptic seizures from the 7th day of life. Examination at the age of 17 months revealed a mentally retarded boy with epileptic seizures, generalised myoclonic contractions, and abnormal ocular movements. A cerebral CT scan showed central and cortical atrophy. Lactate levels in serum, cerebrospinal fluid and urine were elevated, the pyruvate level was raised in serum. A quadriceps muscle biopsy revealed aspecific morphologic signs of a myopathy. Biochemical analysis showed decreased substrate oxidation rates in the mitochondria associated with low rates of ATP production. Total and free carnitine levels were decreased. Investigation of the respiratory chain revealed a defect in the proximal part of respiratory chain involving the region of coenzyme Q. Based on clinical and chemical data it is likely that the patient is suffering from a multi-system disorder.

Treatment of leptomeningeal dissemination of medulloblastoma. Report of a case with a long-term survival

A case report is presented of a boy suffering from medulloblastoma with grade IV spinal cord involvement and a survival of almost 3 years after the occurrence of spinal metastases. A review is given of the literature, with special attention to diagnostic procedures (CSF determinations, myelography) and therapeutic regimens.

Generalized hypertrophic myopathy associated with chorioretinal dystrophy and struma lymphomatosa--a case report

A case is reported of a girl suffering from generalized hypertrophic myopathy and chorioretinal dystrophy since early infancy. A muscle biopsy taken at age seven revealed a general enlargement of the muscle fibers with a concomitant extensive degeneration of myofibrils. At age fourteen, the patient developed a struma lymphomatosa (Hashimoto). This report is the first describing an association of these three diseases.

Deficiency of cytochromes b and aa3 in muscle from a floppy infant with cytochrome oxidase deficiency

A girl was presented suffering from generalised weakness and cardiorespiratory insufficiency. She succumbed at the age of 5 months. Lactate levels were elevated in serum, cerebrospinal fluid and urine. Histopathological examination revealed a mitochondrial myopathy. In muscle tissue the cytochrome oxydase activity was strongly reduced. The content of cytochromes b and aa3 was very low. At autopsy a cardiomyopathy was found.

Multiple pterygium syndrome. A report of two unrelated cases

Clinical description as well as differential diagnosis are presented of two unrelated patients with the so-called Multiple Pterygium Syndrome. In literature pathological alterations of muscle structures in some patients have been described. In our two patients no evidence was found for a neuromuscular disease, nor for a disease state of the central nervous system.