Ultrastructural immunocytochemical localization of electron-transport enzymes in mitochondrial myopathy

Ultrastructural localization of mitochondrial electron transport enzymes in biopsied muscle from a patient with mitochondrial myopathy was studied. We applied the immunoelectron microscopic technique using colloidal-gold labeled antibodies. The results demonstrated a very distinct and dense labeling by gold particles of complexes I, III, and IV in the inner mitochondrial membrane. The density of gold particles reacted to complex IV was cleanly decreased. This result was correlated with the decreased biochemical activity of complex IV. Labeling on the paracrystalline inclusions was substantially decreased in abnormal giant mitochondrial, but gold particles were extensively confined on the membrane of cristae surrounding the inclusions.     

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 histocemical 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.     

Fragmentation analysis of normal and dystrophic avian muscle

A difference between normal and dystrophic avian muscle was demonstrated by comparing the patterns of fragmentation of muscle during homogenization. Fragmentation was monitored by morphological methods and by viscometry. This method of fragmentation analysis depends on the principle that the viscosity of a suspension is an exponential function of the partial volume fraction occupied by the suspended particles; the more a tissue is fragmented into smaller pieces, the greater the viscosity of the resulting homogenate. Increasing the duration of homogenization of either fresh muscle in buffer or glycerinated muscle in relaxing solution gradually increased the viscosity of the homogenate of normal muscle, whereas the viscosity of the homogenate of dystrophic muscle remained approximately constant. This difference in viscosity indicated that dystrophic muscle was sheared into larger pieces which were resistant to further fragmentation. Electron microscopic examination showed that the homogenate of dystrophic muscle contained rows of sarcomeres, whereas normal muscle was sheared into amorphous masses of myofilaments.     

Pathological findings of the sural nerve in mitochondrial encephalomyopathy

We examined the muscle and peripheral nerve of a 55-year-old woman with familial mitochondrial encephalomyopathy. In the gastrocnemius muscle, many ragged red fibers and mitochondria containing paracrystalline inclusions in those fibers were observed by light and electron microscopy, respectively. Histopathological studies of the sural nerve revealed a marked decrease in the number of large myelinated fibers. Electron microscopic studies showed an accumulation of glycogen particles and mitochondria containing abnormal, structurally obscure cristae in the Schwann cell cytoplasm. These results suggest that the cause of loss of the large myelinated fibers may be some disturbance of metabolism in the Schwann cells due to mitochondrial dysfunction.     

Pathological Findings of the Sural Nerve in Mitochondrial Encephalomyopathy

Abstract: We examined the muscle and peripheral nerve of a 55–year-old woman with familial mitochondrial encephalomyopathy. In the gastrocnemius muscle, many ragged red fibers and mitochondria containing paracrystalline inclusions in those fibers were observed by light and electron microscopy, respectively. Histopathological studies of the sural nerve revealed a marked decrease in the number of large myelinated fibers. Electron microscopic studies showed an accumulation of glycogen particles and mitochondria containing abnormal, structurally obscure cristae in the Schwann cell cytoplasm. These results suggest that the cause of loss of the large myelinated fibers may be some disturbance of metabolism in the Schwann cells due to mitochondrial dysfunction.     

Defects in muscle fiber growth in fatal infantile cytochrome c oxidase deficiency

In addition to numerous ragged-red fibers in the muscle from a female infant with fetal infantile cytochrome c oxidase deficiency, the muscle fibers were small in caliber with electron microscopic characteristics of immaturity; the satellite cells were significantly increased in number to 31.3% as compared with those in controls, 8.4 +/- 1.6% (p less than 0.001). In the culture system, the biopsied muscle showed markedly reduced growth despite the presence of numerous satellite cells which are known to act as myoblasts in muscle regeneration, and formed fewer numbers of myotubes containing poorly organized myofibrils and mitochondria with no cytochrome c oxidase activity. A defect in myogenesis and a paucity in repair process in severe form may account for the progressive course and a fatal outcome.     

Hypophysectomy mitigates skeletal muscle fiber damage in hamster dystrophy

Ablation of the pituitary gland by a radiofrequency lesion markedly retarded the musculoskeletal growth of young dystrophic hamsters. The prevalence of centronucleated muscle fibers, which is a reliable cumulative index of the microscopic pathological expression of dystrophy, was drastically reduced in quadriceps muscles of 35- and 45-day-old hypophysectomized dystrophic hamsters, compared with sham-operated controls. Mitigation of skeletal muscle fiber damage by musculoskeletal growth retardation may also occur in human dystrophy.     

Direct neuronal and macroglial versus indirect macrophagic labeling in transplants of fetal neural tissue incubated with gold particles

In a recent light microscopic study based on the transplantation of fetal cells previously incubated with gold-loaded Sendai viruses, S. C. Ardizzoni, A. Michaels, and G. W. Arendash (1988, Science 239: 635-637) proposed that fetal neurons could migrate out into an adult host brain. This result was puzzling in view of several previous contradictory studies, and the light microscopic identification of labeled cells as neurons could be questioned. The present study was therefore undertaken to replicate this study but using electron microscopy to definitely identify migrating gold-labeled elements. Analysis was performed in a model of thalamic transplantation in which previous labeling studies, using thymidine or horseradish peroxidase, had failed to demonstrate any neuronal migration. Gold particles combined with wheat germ agglutinin peroxidase were used to label the fetal tissue prior to transplantation. Fetal cells did incorporate the protein gold complex, and the gold particles were visualized in transplants up to at least 2.5 months after grafting. Electron microscopy analysis reveals that the gold particles are internalized and retained in the lysosomes of grafted neurons and glial cells. In no transplant could labeled grafted neurons be observed intermingled with host neurons, outside the limits of the transplant. In contrast, heavily labeled macrophages were observed surrounding the transplants and sometimes migrating away from the transplant-host interface into the host tissue. These macrophages, presumably of host origin, can be recognized at the light microscopic level by their yellowish staining, a cellular characteristic already noted by Ardizzoni et al. for gold-labeled migrating elements.     

Fatal infantile muscle phosphorylase deficiency

A premature female infant born of a consanguineous union exhibited joint contractures and signs and symptoms of perinatal asphyxia. A muscle biopsy examined by light microscopic, histochemical, and electron microscopic techniques exhibited changes of muscle phosphorylase deficiency and glycogenosis, identical to those of McArdle's disease. Postmortem ultrastructural examination of liver and heart did not reveal lysosomal storage. This case and one previously reported example of fatal infantile phosphorylase deficiency suggest that the clinical spectrum of McArdle's disease may be broader than previously recognized.     

Localization of sodium channel subtypes in adult rat skeletal muscle using channel-specific monoclonal antibodies

Five monoclonal antibodies specific for the 260 kDa subunit of the rat skeletal muscle sodium channel were used to probe the distribution of this channel in adult muscle. All the antibodies reacted with the surface membrane of fast- and slow-twitch fibers in the rat anterior tibial and soleus muscles. Immunoreactivity was also present in the endplate region; this was significantly more intense than that in the surrounding extrajunctional membrane. At the electron microscopic level, this junctional immunoreactivity could be traced uniformly throughout the secondary folds of the post-synaptic membrane. Three of the monoclonal antibodies (A/B2, F/E4, and I/E3) exhibited an additional distinct immunoreactivity pattern, staining the interior of selected fibers in the anterior tibial muscle that were subsequently identified as slow-twitch fibers. An identical reactivity pattern was observed with most of the soleus muscle fibers. In longitudinal sections of slow fibers examined at the light microscopic level, transversely oriented, regularly spaced doublets of fluorescence were localized at the junction of the A and I bands in each sarcomere. In permeabilized slow fibers exposed to A/B2 and examined at the electron microscopic level, internal reactivity was associated exclusively with the membranes of the T-tubular system. A/B2 also strongly stained a transversely oriented pattern within cardiac muscle fibers exhibiting the characteristics of the T-tubular system in that tissue. We conclude that at least 3 subpopulations of sodium channels are present in adult skeletal muscle: those in the sarcolemma of fast and slow fibers, those in slow-twitch fiber T-tubular membranes, and those in the T-tubular system of fast fibers. The channels in the slow fiber T-system apparently share common epitopes with those in the T-system of cardiac fibers.