Induction of spheroid cytoplasmic bodies in a rat muscle by local tetanus

Incidence of polysaccharide storage myopathy: necropsy study of 225 horses

Muscle samples were obtained at necropsy from 225 horses and ponies 1 year of age or older. Samples were processed in routine manner and were stained with hematoxylin and eosin and with periodic acid-Schiff for glycogen. Sections were examined for abnormal glycogen content and amylase-resistant complex polysaccharide and for chronic myopathic change (excessive fiber size variation, increase in number of internal nuclei). A total of 101 horses and ponies with lesions of polysaccharide storage myopathy were identified. Age of affected horses ranged from one to 30 years, with a mean of 14.7 years. Mean age of nonaffected horses was 12 years. Incidence of polysaccharide storage myopathy varied depending on breed; Thoroughbreds had the lowest (27%) and draft-related horses had the highest (86%) incidence. Chronic myopathic changes were more severe in polysaccharide storage myopathy-affected horses than in nonaffected horses. Results of this study indicate that polysaccharide storage myopathy is a common disorder of many breeds of horses and ponies.

Recovery from 6 weeks of repeated strain injury to rat soleus muscles

Recovery from chronic strain injury (50 strains daily, five times weekly for 6 weeks to hyperactive soleus muscles) was followed for 3 months in female rats after cessation of chronic hyperactivity induced by pretreatment of the plantar flexor muscles with tetanus toxin. After 6 weeks of repeated strains, muscle mass decreased by 62%, myofiber areas were reduced by 87%, and noncontractile tissue expanded dramatically by 222%. Collagen content increased by almost ninefold (control 40 +/- 3 microg/mg, chronic injury 392 +/- 53 microg/mg), whereas the molar ratio of collagen (pyridinoline) crosslinks to collagen remained the same (control 0.20 +/- 0.01, chronic injury 0.16 +/- 0.01). After 3 months of ambulation, muscle mass returned to normal but myofiber areas remained smaller by 21%, noncontractile tissue was still markedly elevated by 18% with increased collagen content (107 +/- 15 microg/mg), and the molar ratio of crosslinks to collagen increased by 75% during recovery. Thus, rat soleus muscles recovered very slowly and incompletely from chronic strain injuries that produced muscle fibrosis, highlighting the necessity of devising preventative strategies for repeated strain injuries.

Congenital myopathies with inclusion bodies: a brief review

Based on morphological abnormalities, congenital myopathies can be classified into several categories: (1) enzyme histochemically abnormal appearance without structural pathology, e.g., congenital fibre type disproportion or congenital fibre type uniformity; (2) abnormally placed nuclei, e.g. myotubular and centronuclear myopathies; (3) disruption of normal intrinsic structures, largely sarcomeres, e.g. central cores and minicores; (4) abnormal inclusions within muscle fibres. Several such inclusions are derived from pre-existing structures, most notably rods or nemaline bodies. Other derivatives of Z-band material are cytoplasmic bodies and possibly related inclusions as spheroid bodies, sarcoplasmic bodies or Mallory body-like inclusions. These inclusions share accumulation of desmin, the muscle fibre-specific intermediate filament, and of other proteins, some of them physiological, but others quite abnormal. Inclusions without identified precursors are fingerprint bodies, reducing bodies, cylindrical spirals, and Zebra bodies. Experimental models and tissue culture reproduction are necessary to further clarify significance of these inclusions in congenital myopathy pathology.

Cellular responses in exertion-induced skeletal muscle injury

Muscle injury is a common result of muscle exertion caused by overload and over-activity. In this presentation, an attempt was made to discuss models of muscle injury which involve exertion but not excessive strain, although most functional activities of the extremities require some eccentric muscle actions. Muscle injury is characterized by cellular and extracellular matrix responses which appear to be common to all types of muscle trauma -- even in the absence of bleeding. Using tenotomy and functional over-load of the rat hindlimb muscles as examples, illustrations of several of these responses are presented and discussed.

Spheroid body myopathy revisited

Having reported spheroid body myopathy from Indiana (IN) inherited in an autosomal-dominant fashion several years ago, we now describe additional findings from the Oregon branch--briefly recorded earlier--and confirm earlier studies in another clinically affected IN member of this kinship demonstrating identical spheroid bodies within the myopathic muscle specimens. The spheroid bodies also contained increased amounts of desmin, alpha-B crystallin, and ubiquitin within muscle fibers. Our studies now have established that spheroid body myopathy is a member of the growing family of desminopathic neuromuscular conditions.

Desmin-related neuromuscular disorders

Desmin, the intermediate filament protein of skeletal muscle fibers, cardiac myocytes, and certain smooth muscle cells, is a member of the cytoskeleton linking Z-bands with the plasmalemma and the nucleus. The pathology of desmin in human neuromuscular disorders is always marked by increased amounts, diffusely or focally. Desmin is highly expressed in immature muscle fibers, both during fetal life and regeneration as well as in certain congenital myopathies, together with vimentin. Desmin is also enriched in neonatal myotonic dystrophy and small fibers in infantile spinal muscular atrophy. Focal accretion of desmin may be twofold, in conjunction with certain inclusion bodies, cytoplasmic and spheroid bodies, and in a more patchy fashion, granulofilamentous material. Both lesions have been found in certain families, affected by a myopathy and/or cardiomyopathy. Other proteins, e.g., dystrophin, vimentin, actin, ubiquitin, and alpha-B crystallin, may also be overexpressed. Desmin pathology may be genetically regulated or may merely reflect profoundly impaired metabolism of several proteins within myofibers.

Cytoplasmic body myopathy: familial cases with accumulation of desmin and dystrophin. An immunohistochemical, immunoelectron microscopic and biochemical study

Muscle biopsy samples from five patients with cytoplasmic body myopathy (CBM) were investigated by immunohistochemical (antibodies to desmin, actin, dystrophin, spectrin, alpha actinin and utrophin), immunoelectron microscopic (antibodies to desmin, actin and dystrophin) and biochemical (desmin, dystrophin, actin and utrophin western blots) methods. Using immunofluorescence it was shown that the centers of cytoplasmic bodies (CB) were stained by anti-actin, anti-utrophin and three different anti-dystrophin antibodies. The peripheries were labeled by the anti-desmin antibody. Moreover, fibers containing CB showed a markedly increased staining of their entire sarcoplasm with the anti-desmin antibody. Using immunoelectron microscopy it was shown that anti-dystrophin antibodies selectively stained the external limit of the central granular region. Anti-desmin antibody labeled the filamentous halo, and anti-actin antibody stained the central core and the radiating filaments. Biochemical studies showed storage of desmin and dystrophin, both of normal molecular weight. Our results suggest that CBM should be considered along with a wider group of intermediate filament pathologies that include desmin-storage myopathies.

Disruption of intermediate filament organization leads to structural defects at the intersomite junction in Xenopus myotomal muscle

In mature striated muscle, intermediate filaments (IFs) are associated with the periphery of Z-discs and sites of myofibril-membrane attachment. Previously T. Schultheiss, Z. X. Lin, H. Ishikawa, I. Zamir, C. J. Stoeckert and H. Holtzer (1991) J. Cell Biol. 114, 953) reported that the disruption of IF organization in cultured chick myotubes had no detectable effect on muscle cell structure. Cultured muscle is not, however, under the mechanical loads characteristic of muscle in situ. The dorsal myotomal muscle (DMM) of the Xenopus tadpole provides an accessible model system in which to study the effects of mutant IF proteins on an intact, functional muscle. DNAs encoding truncated forms of Xenopus vimentin or desmin were injected into fertilized Xenopus eggs. Embryos were allowed to develop to the tadpole stage and then examined by confocal or electron microscopy. DMM cells containing the truncated IF polypeptides displayed disorganized IF systems. While the alignment of Z-lines appeared unaffected, cells accumulating mutant IF polypeptides displayed abnormal organization at the intersomite junction. Myocyte termini are normally characterized by deep invaginations of the sarcolemma. In myocytes expressing mutated IF polypeptides, these membrane invaginations were reduced or completely absent. Furthermore, the attachment of myofibrils to the junctional membrane was often aberrant or completely disrupted. These results suggest that in active muscle IFs play an important role in the organization and/or stabilization of myofibril-membrane attachment sites.

Desmin pathology in neuromuscular diseases

Desmin is an intermediate filament protein that in striated muscle is normally located at Z-bands, beneath the sarcolemma, and prominently at neuromuscular junctions. It is abundant during myogenesis and in regenerating fibers, but decreases in amount with maturation; in regenerating and denervated muscle fibers it is co-expressed with vimentin. Aggregates of desmin occur as nonspecific cytoplasmic bodies or cytoplasmic spheroid complexes, similar to the aggregates of keratin filaments in Mallory bodies or the neurofilament aggregates in Lewy bodies. In all three instances, alpha-B crystallin may be associated with desmin. There are now increasing numbers of neuromuscular disorders in which abnormal amounts of desmin, some abnormally phosphorylated, feature prominently in muscle fibres. Several of these diseases, including spheroid body myopathy, granulo-filamentous body myopathy and the dystrophinopathies, are familial. Ultrastructural and immunohistochemical studies of desmin have considerably broadened our understanding of the pathology of the cytoskeleton in muscle fibers and in certain hereditary neuromuscular diseases.

Inclusions in familial cytoplasmic body myopathy are stained by anti-dystrophin antibodies

We report here for the first time positive anti-dystrophin labelling of inclusions in three cases belonging to the same family affected by familial cytoplasmic body myopathy (CBM). Inclusions are also stained, as reported previously, by anti-actin antibodies. The anti-desmin reaction was negative in the centre of cytoplasmic bodies (CB) but showed an enhancement of staining in the peripheral part. Abnormal sarcoplasmic staining of fibres with CB was also observed with that antibody. Anti-vimentin antibody labelling was negative. At present, the significance of this labelling by anti-dystrophin antibodies is unknown, but will open new fields for further investigations in an attempt to understand CB pathogenesis.

Experimental emetine myopathy: enzyme histochemical, electron microscopic, and immunomorphological studies

Ipecac, containing emetine hydrochloride, is used by patients with anorexia nervosa to induce vomiting. Its chronic usage may result in a myopathy and a cardiomyopathy, the former marked by cytoplasmic bodies. We studied myopathological changes after daily injections of female Wistar rats with emetine hydrochloride intraperitoneally for periods of 4, 5, 9, and 10 weeks. The extensor digitorum longus muscle and the soleus muscle showed core-like lesions, streaming of the z-discs, nemaline bodies, cytoplasmic bodies, and spheroid cytoplasmic bodies. Immunomorphological studies revealed increased amounts of desmin. During a period of repair, i.e., 2, 4, and 6 weeks after termination of emetine application, these myopathological alterations faded while proliferation of the T-tubular system, i.e., honeycomb structures, was more often prevalent. Pathological features completely disappeared between 6 and 12 weeks of recovery.

Soleus-specific myopathy induced by passive stretching under local tetanus

Twenty-four adult albino rats were injected with tetanus toxin into the right gastrocnemius muscle and then subjected to sustained dorsiflexion of the right ankle joint for 2 to 14 days. Histologic examinations of the soleus after this procedure showed myopathic changes, characterized by variations in fiber diameters, myonecrosis with opaque fibers, interstitial fibrosis, and small groups of regenerated fibers. Electron microscopy revealed derangement of T-tubules immediately adjacent to the sarcolemma in the early degenerative stage. The size and wet weight of soleus increased compared to that of the control side between 2 and 5 days post-tetanus. Serum GOT, LDH, and creatine kinase (CK) levels were elevated especially in the early degenerative stages. Peri- and endomysial fibrosis developed gradually from about 3 days post-tetanus. Pathomechanisms inducing these changes were discussed.

Desmin and actin associated with cytoplasmic bodies in skeletal muscle fibers: immunocytochemical and fine structural studies, with a note on unusual 18- to 20-nm filaments

In a fine structural and immunocytochemical study, the latter performed on semithin sections of epoxy resin embedded skeletal muscle fibers, three types of cytoplasmic bodies were identified in a case of cytoplasmic body myopathy: (1) The first type, the classical type, showed a central core and a light halo with radiating actin filaments at the periphery. (2) The second type, the spheroid body was characterized by irregularly arranged granular masses associated with intermediate filaments. Desmin immunoreactivity occurred in the central and peripheral parts, where filaments of intermediate size were visualized by electron microscopy. Desmin immunoreactivity was noted also at the Z-bands of striated annulets, within areas of disordered myofibrils, such as sarcoplasmic masses, and in atrophic muscle fibers. (3) The third type of the cytoplasmic body was composed mainly of large masses of uneven granularity and electron density. The center of this type reacted to anti-actin antibody suggesting that the 5- to 6-nm filaments, which ultrastructurally proved to be a major component, were of the actin type. By contrast, neither intermediate filaments nor actin microfilaments were found by electron microscopy in cytoplasmic bodies in a second case where no immunoreaction to desmin or actin occurred. Anti-vimentin antibody stained only the cytoplasm of endomysial cells, but not the inclusion bodies. Some other, unusual inclusions with 18- to 20-nm tubulo-filamentous structures have to be distinguished from the various types of filaments in cytoplasmic bodies. It is concluded, that pleomorphism and heterogeneity of "cytoplasmic bodies" have to be taken into consideration when classifying cytoplasmic body myopathies.

Involvement of respiratory muscles in cytoplasmic body myopathy--a pathology study

A muscle biopsy and autopsy study of a child who died at 14 months of respiratory failure is described. A diagnosis of infantile cytoplasmic body myopathy was made due to the high percentage of cytoplasmic bodies (CBs), particularly in respiratory muscles. No pathological abnormalities were found in the central nervous system, peripheral nerves or visceral organs. Immunohistochemical studies suggested that the central core of CBs was stained for fibrillary actin, being surrounded by a positive signal for desmin. A differential diagnosis as to other conditions involving proliferation of CBs is discussed.

Transient cytoplasmic bodies in muscle of three infants with Werdnig-Hoffmann disease

We present three instances in which cytoplasmic bodies in muscle fibers were associated with Werdnig-Hoffmann disease. The children presented within the first 6 weeks of life with clinical symptoms and laboratory studies indicative of infantile spinomuscular atrophy (ISMA). Initial muscle biopsies in each case revealed signs of muscle immaturity and cytoplasmic bodies but lacked features of denervation. Follow-up biopsies in 2 cases revealed changes typical of ISMA, but cytoplasmic bodies were no longer present. A follow-up biopsy was not available in the third child who also had a clinical course consistent with ISMA. We discuss the pathogenesis of cytoplasmic bodies and their significance in association with Werdnig-Hoffmann disease.

Inclusion body myositis: the mumps virus hypothesis

The resemblance of the filamentous inclusions in inclusion body myositis (IBM) to mumps virus nucleoproteins and the report of immunoreactivity of the inclusions for mumps virus antigens have implicated the mumps virus in the etiology of IBM. We tested the mumps virus hypothesis by in-situ hybridization with a cDNA probe specific for the mumps virus nucleocapsid gene, and immunocytochemically with antibodies against "soluble" and "viral" mumps antigens. The tests were performed on muscle specimens (IBM, 20; acid maltase deficiency, 4; chloroquine myopathy, 2; nonweak control subjects, 5) and mumps virus-infected and uninfected HEp-2 cells. The in-situ hybridization study showed a strong specific signal in the infected HEp-2 cells but no specific signal in IBM, other myopathies, or nonweak control subjects. The immunocytochemical study showed specific binding of the antimumps antibodies to the infected HEp-2 cells but demonstrated only nonspecific binding of these antibodies around rimmed vacuoles in IBM, acid maltase deficiency, and chloroquine myopathy. These studies cast doubt on the mumps hypothesis of IBM.

The spectrum of cytoplasmic body myopathy: report of a congenital severe case

A 6-year-old girl presented with a myopathy--she was floppy since birth and developed progressive respiratory failure for which she required mechanical ventilation at age 6 months. Biopsy showed cytoplasmic bodies in about 15% of both type 1 and 2 muscle fibers. Of the 18 cases of cytoplasmic body myopathy (CBM) reported in the literature, 3 had symptoms at birth and in all of them the course was benign. Four clinical patterns emerged; a) congenital severe, b) congenital benign, c) juvenile severe and d) adult severe forms.

Ultrastructural pathology in emetine-induced myopathy

Progressive myopathy developed in two women who consumed ipecac syrup containing emetine hydrochloride to induce vomiting as part of their anorexia nervosa. Muscle biopsy specimens were characterized by severe disruption of the sarcomeres. The ultrastructural spectrum extended from "Z-band streaming" to the formation of cytoplasmic bodies and also comprised abnormalities of the sarcotubular system, thus suggesting that muscle weakness may be related to both sarcomeric and sarcotubular lesions in this self-inflicted myopathy. It is tempting to suggest that muscle weakness may be correlated with or based on the pathology in sarcomeres and the sarcotubular system. As the myopathy is clinically reversible upon discontinuation of ipecac consumption the morphological findings should also be potentially reversible. Experimentally induced emetine myopathy may, thus, serve as a useful model to study morphological dynamics of sarcomeric lesions, which may be observed separately or simultaneously in a variety of spontaneously occurring human neuromuscular disorders.