A clinical and histological study of Ullrich's disease (congenital atonic-sclerotic muscular dystrophy)

Clinical characteristics recognized in five cases with Ullrich's disease included muscle weakness and wasting, striking contracture of proximal (sclerotic) joints and hyperflexibility of distal (atonic) joints since an early infantile stage, and slowly progressive course. The biopsied muscles demonstrated myopathic changes including a remarkable variation in fiber size, notably proliferated endomysial connective tissue, increased myofibers with centralized nuclei and a few necrotic fibers with active phagocytosis. On histochemical examination, no specific intracytoplasmic structural abnormalities such as nemaline bodies, cores and myotubes were recognized. Although both type 1 and 2 fibers were distributed in checkerboard pattern in most muscle fascicles, type 1 fiber predominance or type 2 fiber deficiency was common in severely damaged muscles, suggesting the presence of some kind of neural influence exerting on the myopathic process as the disease progressed. Since it still remains uncertain whether this disorder belongs to the muscular dystrophies, or to other neuromuscular or mesodermal diseases, we would rather label it Ullrich's disease then Ullrich's muscular "dystrophy" until its pathogenesis becomes clear.

The significance of type 2C muscle fibers in Duchenne muscular dystrophy

Undifferentiated type 2C fibers, which are dark on ATPase staining with both alkaline and acid preincubation, comprised on average 16.1% of the muscle fibers in 12 patients with Duchenne muscular dystrophy (DMD). Many of type 2C fibers had characteristics of regenerating fibers: basophilic cytoplasm, vesicular nuclei with occasional prominent nucleoli, high alkaline phosphatase and nonspecific esterase activity, and also high oxidative enzyme activity at the periphery of the fiber. A localized high acetylcholinesterase activity suggested the presence of a neuromuscular junction in some of the type 2C fibers. In serial sections, histochemical reactions characteristic of the type 2C fiber were present in segments of a single fiber, which in other parts was either a type 1 or a type 2 fiber. Since most of the opaque (hyaline, dark) fibers, which previously have been thought to be precursors of necrotic fibers, behaved as differentiated type 1 or type 2 fibers, the presence of type 2C fibers in DMD may not reflect "dedifferentiation" of fiber type, but rather indicate an active regenerating process. It remains unknown whether the type 2C fiber segments in DMD develop into fully differentiated functional fibers or remain as incompletely regenerated fibers.

Familial distal myopathy with rimmed vacuole and lamellar (myeloid) body formation

Three cases from 2 families had muscle weakness with predilection for distal extremities, predominantly affecting the tibialis anterior muscles, and onset in early adulthood. The disorder seemed to be inherited through an autosomal recessive trait. The EMG demonstrated a myopathic pattern and CPK was mildly elevated. The striking finding in their muscle biopsies was the presence of "rimmed" vacuoles which had acid phosphatase-positive autophagic activity and which contained numerous concentric lamellar bodies in various forms (myeloid and cabbage bodies). Despite rapid clinical progression, not only necrotic fibers with phagocytosis, as seen in Duchenne dystrophy, but also evidence of regeneration were virtually absent. Continuous destruction of myofibrils by activation of certain lysosomal proteolytic enzymes might be responsible for the production of atrophic fibers.

Suppression of calcium-induced removal of the Z-line by a thiol-protease inhibitor, E-64-c

A new thiol-protease inhibitor, E-64-c (N-[N-(L-3-carboxyoxirane-2-carbonyl)-L-leucyl]-isoamylamine), specifically suppressed the disappearance of the Z-line terminal by calcium in rat soleus muscle. This results suggests that calcium-activated neutral protease (CANP) may be involved in such calcium-mediated degeneration of myofilaments.

Heterogeneous expression of myosin light chain 1 in a human slow-twitch muscle fiber

Heterogeneous expression of myosin light chain 1 was observed in a human slow-twitch muscle fiber on two dimensional gel electrophoresis. Three spots were found around the L1 region and one of them corresponded to fast type L1. The nature of the heterogeneity is discussed.

Alexander disease: clinical, electrodiagnostic and radiographic studies

A 10-month-old boy with Alexander disease is described. He was clinically characterized by early onset of megalencephaly, psychomotor retardation, spasticity and recurrent seizure attacks. Pathological examination of the biopsied cerebrum revealed a large number of Rosenthal fibers in the white matter and beneath the pia in association with advanced demyelination. The motor nerve conduction velocity was remarkably delayed, suggesting a possible change of the peripheral nerve. The computerized tomography demonstrated megalencephaly and bilateral symmetrical low density areas in the cerebral white matter, particularly in the frontal region. The preferential involvement of frontal lobes was also confirmed by electroencephalogram and brain scan. The preferential damage of the frontal region in the early stage of the disease may be an important clue to a diagnosis of Alexander disease by computerized tomography, brain scan and electroencephalogram.

Duchenne muscular dystrophy: unusual activation of single fibers in vitro

Single skinned fibers were prepared from muscle biopsies of patients with Duchenne muscular dystrophy (DMD) and other neuromuscular diseases. The activation of the contractile system by calcium or strontium ion and the function of the sarcoplasmic reticulum were studied. In many fibers of the biopsy specimens from patients with DMD, activation by strontium revealed a pattern intermediate between those shown by the usual type 1 and type 2 fibers. These fibers were generally of smaller diameter and produced less maximal tension than type 1 and 2 fibers. The study of muscle of newborn animals suggests that this unusual pattern of activation might reflect either arrested development or incomplete regeneration after muscle necrosis in the disease.

Intracytoplasmic vacuoles in alpha W fibers of dystrophic chicken muscle--probable early pathologic event initiates massive fiber necrosis

An electron-microscopic study on dystrophic chicken white muscle, posterior latissimus dorsi (PLD), was performed with histochemical identification of three fiber types of beta R (red), alpha R and alpha W (white) fibers to evaluate the pathophysiology in fiber necrosis. As seen in histochemically stained sections, vacuolar formation in the cytoplasm, an outstanding pathologic feature in chicken dystrophy, was recognized in the alpha W fibers by electron microscopy. The vacuole was membrane-bound and thought to originate from coalescence or dilatation of extensively proliferated sarcotubular system. There was evidence of a delay in fiber type transformation from alpha R to alpha W in dystrophic white muscle, while the initial pathologic event of sarcotubular system proliferation might be expressed only after muscle fibers had attained histochemical characteristics of alpha W fibers. Localized myofibrillar degeneration was encountered in the vicinity of the vacuole with focal membrane defect. An influx of extracellular fluid through the vacuolated sarcotubular system into the sarcoplasm may activate certain proteases, such as calcium-dependent protease because the extracellular fluid contains high concentration of calcium ion. The activated protease then degrades structural protein, especially Z-line protein, followed by fiber necrosis with phagocytosis.

Anastomoses of transverse tubules with terminal cisternae in polymyositis

Abnormal transverse or T tubules spatially continuous with sarcoplasmic reticulum (SR), as visualized with a lanthanum (La) tracer, were found in biopsy specimens from nine patients with polymyositis whose serum enzyme (creatine phosphokinase [CPK]) levels were elevated before the time of biopsy. On comparison with the T system in more than 50 control subjects without CPK elevation, it became apparent that presumed anastomoses of T tubules with SR were the most consistent anatomical correlates of the enzyme leakage. Two types of anastomoses were seen on the basis of passage of La: first, early segmental dilation of T tubules and perpendicular continuations with SR; and second, focal proliferation of T tubules forming "T tubule networks" and then anastomosing with SR at the periphery of the networks. The latter is considered to be a concurrent repair process for the injured triads. Lanthanum did not penetrate freely through the plasma membrane of necrotized muscle fibers. It is concluded that junctional sites between T tubules and SR may be the primary sites of leakage of sarcoplasmic enzymes in polymyositis.

Calcium-activated neutral protease. Its localization in the myofibril, especially at the Z-band

Calcium-activated neutral protease (CANP) was demonstrated in myofibrils, especially at the Z-band in chicken glycerinated myofibrils, by an immunofluorescent method. The amount of CANP bound to myofibrils was approximately 4 percent of that contained in the whole muscle homogenate. No immunological difference was recognized between the myofibril-bound CANP and the soluble one when examined by Ouchterlony's immunodiffusion analysis. A possible role of myofilbril-bound CANP in the physiological turnover of the myofibrillar proteins is discussed.

Werdnig-Hoffmann disease: proposal of a pathogenetic mechanism

Light and electron microscopic study and morphometric analysis were performed on the spinal cords and roots from six cases of acute Werdnig-Hoffmann disease and four control cases, in search of the pathogenesis of the selective motor neuron changes considered primarily responsible for Werdnig-Hoffman disease. This investigation posits a centrifugal traction mechanism based upon the discovery of cylindrical outgrowths of glial bundles, selective loss of large myelinated fibers, and axonal degeneration in the proximal portion of anterior spinal roots (and to a lesser extent in posterior spinal roots) in all six disease cases. This traction mechanism exerts principally upon anterior spinal nerve roots and can account for morphologic and morphometric data characteristically ascribed to Werdnig-Hoffmann disease.

Satellite cells and muscle regeneration in diseased human skeletal muscles

By virtue of the lanthanum nitrate staining technique applied to biopsied muscle we are able to demonstrate interaction between satellite cells and parent myofibers, as well as development of premyocytes from activated satellite cells. The process of regeneration in diseased muscle appears to differ from that described in experimental myogenesis. Transformation of activated satellite cells to two types of premyocytes in the process of muscle regeneration seems to rely primarily on the state of innervation and recovery rate of the parent cell after injury. Activated satellite cells are characterized morphologically by proliferation of caveolae, first on the parent fiber side, and early T-tubule and myofilament formation and central displacement. In diseased human muscle the satellite cells appear to play significant roles in muscle regeneration both as a source of reinforcement for failing metabolism in the parent cell and as potential replacements for the necrotic segment of the parent cell. This study also demonstrates that the satellite cells are capable of developing into independent myocytes which may fuse with or replace the parent cell, dependent upon the type and extent of the injury sustained. Abnormal fusion among premyocytes or with their parent fiber, resulting in formation of split-or ring-fibers, becomes conceivable when both innervation and recovery from the injury of the parent cell are delayed. Thus, myotube formation, characteristic of usual myogenesis, seldom takes place in the regenerative process instituted by satellite cells in diseased human skeletal muscles.

Muscle pathology in cytochrome c oxidase deficiency

Muscle biopsies from 16 patients with cytochrome c oxidase (CCO) deficiency were examined morphologically. Two siblings had the fatal infantile form. The muscle of the older sister at the age of 5 months had numerous ragged-red fibers (RRF) and increased numbers of lipid droplets; at 28 days the brother had no RRF suggesting that the RRF formed later than 28 days. The muscle pathology in two patients with the benign infantile form improved as they grew older; numbers of RRF, lipid droplets and glycogen particles decreased and CCO activity increased in the second biopsy. In the encephalomyopathic form, RRF were seen in 5 of 12 muscles mostly in patients more than 6 years of age. Muscle spindles and blood vessel walls in the biopsies from three patients with rapid clinical aggravation had no CCO activity, suggesting that enzyme activity differed from tissue to tissue (tissue specificity).