免疫荧光检测抗肌萎缩蛋白诊断肌营养不良症的临床应用

目的 采用免疫荧光技术对Duchenne型肌营养不良症（Duchenne muscular dystrophy,DMD),Becker型肌营养不良症（Becker muscular dystrophy,BMD)，面肩肱型肌营养不良症（facioscapulohumeral muscular dystrophy,FSHD)以及神经性肌萎缩患者骨骼肌细胞膜的dystrophin蛋白进行检测，为临床诊断、分类肌营养不良症提供简便的实验方法。方法 对47例患者选择3种dystrophin 的鼠抗单克隆抗体、羊抗和兔抗多克隆抗体，分别进行免疫荧光技术检测。结果 16例DMD患者均为阴性染色；11例BMD患者为弱阳性染色；10例FSHD和10例神经性肌萎缩患者均为阳性染色。结论 检测肌营养不良症患者骨骼肌膜dystrophin蛋白，有助于肌营养不良症的临床诊断和分型。     

Postischemic skeletal muscle injury: patterns of injury in relation to adequacy of reperfusion

Ischemia-induced skeletal muscle injury was studied in rats subjected to tourniquet hindlimb ischemia for 3, 4, or 5 hr. The extent of injury was evaluated morphologically after 5 or 20 hr of reperfusion by a dye exclusion test using Evans blue/albumin (EBA) and a histochemical stain for calcium, Alizarin red S (ARS). In addition, the distribution of Evans blue in the postischemic muscle served as a means for detecting areas of defect reperfusion--no reflow. The combination of EBA and ARS allowed easy and reproducible quantification of induced injury in adequately reperfused areas. In areas of no reflow none of the markers used were useful. Muscle cells in these areas appeared structurally well preserved even 20 hr after release of the tourniquet and no cytoplasmic calcium accumulation could be demonstrated in muscle cells by staining with ARS. In many of these areas, however, ARS-positive structures were found between muscle cells, distributed in a pattern corresponding to the capillary network. The nature of these structures, constituting a morphological correlate to the no-reflow phenomenon, is unclear. It is concluded that for the proper evaluation of postischemic skeletal muscle injury, a suitable marker allowing estimation of the adequacy of the reperfusion must be used.     

Utility of dystrophin and utrophin staining in childhood muscular dystrophy

To determine the utility of dystrophin and utrophin staining in the differential diagnosis of childhood muscular dystrophy. Fifty muscle biopsies of histologically confirmed cases of childhood muscular dystrophy, below 16 years of age, were stained immunohistochemically for dystrophin and utrophin. All the 30 muscle biopsies of patients with Duchenne muscular dystrophy (DMD) showed all or majority of muscle fibers deficient for dystrophin and positive for utrophin. In the 4 female DMD carriers there was mosaic pattern of staining for dystrophin and reciprocal positivity for utrophin. All the muscle biopsies of patients with other childhood onset muscular dystrophies were positive for dystrophin and negative for utrophin. This study shows that dystrophin staining differentiates DMD and DMD carriers from other childhood muscular dystrophies and utrophin staining is of no added value. Utrophin up-regulation may compensate for structural deficiency in dystrophic muscle.     

Platelet-derived growth factor and its receptors are related to the progression of human muscular dystrophy: an immunohistochemical study

This study has examined the immunological localization of platelet-derived growth factor (PDGF)-A, PDGF-B, and PDGF receptor (PDGFR) alpha and beta to clarify their role in the progression of muscular dystrophy. Biopsied frozen muscles from patients with Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and congenital muscular dystrophy (CMD) were analysed immunohistochemically using antibodies raised against PDGF-A, PDGF-B, and PDGFR alpha and beta. Muscles from two dystrophic mouse models (dy and mdx mice) were also immunostained with antibodies raised against PDGFR alpha and beta. In normal human control muscle, neuromuscular junctions and vessels were positively stained with antibodies against PDGF-A, PDGF-B, PDGFR alpha and PDGFR beta. In human dystrophic muscles, PDGF-A, PDGF-B, PDGFR alpha and PDGFR beta were strongly immunolocalized in regenerating muscle fibres and infiltrating macrophages. PDGFR alpha was also immunolocalized to the muscle fibre sarcolemma and necrotic fibres. The most significant finding in this study was a remarkable overexpression of PDGFR beta and, to a lesser extent, PDGFR alpha in the endomysium of DMD and CMD muscles. PDGFR was also overexpressed in the interstitium of muscles from dystrophic mice, particularly dy mice. Double immunolabelling revealed that activated interstitial fibroblasts were clearly positive for PDGFR alpha and beta. However, DMD and CMD muscles with advanced fibrosis showed very poor reactivity against PDGF and PDGFR. Those findings were confirmed by immunoblotting with PDGFR beta. These findings indicate that PDGF and its receptors are significantly involved in the active stage of tissue destruction and are associated with the initiation or promotion of muscle fibrosis. They also have roles in muscle fibre regeneration and signalling at neuromuscular junctions in both normal and diseased muscle.     

Canine X-linked muscular dystrophy in a family of Grand Basset Griffon Vendéen dogs

Three related Grand Basset Griffon Vendéen (GBGV) dogs, two male and one female, with poor locomotion and muscle pain on palpation, were humanely destroyed at approximately 2 months of age and submitted for necropsy. Histopathological examination of skeletal muscles showed hyaline hypereosinophilic myofibres, hypertrophy and atrophy, calcification, necrosis, and mild proliferation of endomyseal connective tissue, as well as small basophilic fibres with internalized nuclei in rows, indicating regeneration. Immunohistochemical labelling for the carboxy-terminal domain of dystrophin, performed on skeletal muscle from one of the male dogs, was negative, whereas it was positive in skeletal muscle from a normal control dog. Both parents were clinically unaffected. These findings confirmed the diagnosis of canine X-linked muscular dystrophy (CXMD). To the authors' knowledge, this is the first report of CXMD in the GBGV breed, and one of very few cases in a female dog.     

Dystrobrevin deficiency at the sarcolemma of patients with muscular dystrophy

Mutations in the genes encoding dystrophin or dystrophin-associated proteins are responsible for Duchenne muscular dystrophy or various forms of limb-girdle muscular dystrophies respectively. We have recently cloned the gene for the murine 87 kDa postsynaptic protein dystrobrevin, a dystrophin-associated protein. Anti-dystrobrevin antibodies stain the sarcolemma in normal skeletal muscle indicating that dystrobrevin co-localises with dystrophin and the dystrophin- associated protein complex. By contrast, dystrobrevin membrane staining is severely reduced in muscles of Duchenne muscular dystrophy patients, consistent with dystrobrevin being a dystrophin-associated protein. Interestingly, dystrobrevin staining at the sarcolemma is dramatically reduced in patients with limb-girdle muscular dystrophy arising from the loss of one or all of the sarcoglycan components. Normal dystrobrevin staining is observed in patients with other forms of limb- girdle muscular dystrophy where dystrophin and the rest of the dystrophin-associated protein complex are normally expressed and in other neuromuscular disorders. Our results show that dystrobrevin- deficiency is a generic feature of dystrophies linked to dystrophin and the dystrophin-associated proteins. This is the first indication that a cytoplasmic component of the dystrophin-associated protein complex may be involved in the pathogenesis of limb-girdle muscular dystrophy.      

Investigation of a female manifesting Becker muscular dystrophy.

Females manifesting Becker muscular dystrophy (BMD) are even more rarely observed than for the allelic condition Duchenne muscular dystrophy. The male proband has typical BMD with greatly raised CK activity and a myopathic muscle biopsy. His mother experienced walking difficulties from 35 years of age and has a myopathy with marked calf hypertrophy, a raised CK, and a myopathic muscle biopsy. Dystrophin analysis was undertaken on both the proband and his mother. Immunoblotting showed a protein of normal size but of reduced abundance in both. Immunocytochemical analysis in the proband indicated that the majority of the fibres showed weak dystrophin labelling and in his mother both dystrophin positive and dystrophin negative fibres were present. Non-random X inactivation at locus DXS255, was observed in DNA isolated from peripheral lymphocytes of the mother. Neither extended multiplex PCR performed on DNA from the proband nor analysis of lymphocyte derived mRNA showed a structural alteration in the dystrophin gene suggesting that an unusual mutation was responsible for BMD in this family.     

Long-term blocking of calcium channels in mdx mice results in differential effects on heart and skeletal muscle

The disease mechanisms underlying dystrophin-deficient muscular dystrophy are complex, involving not only muscle membrane fragility, but also dysregulated calcium homeostasis. Specifically, it has been proposed that calcium channels directly initiate a cascade of pathological events by allowing calcium ions to enter the cell. The objective of this study was to investigate the effect of chronically blocking calcium channels with the aminoglycoside antibiotic streptomycin from onset of disease in the mdx mouse model of Duchenne muscular dystrophy (DMD). Treatment in utero onwards delayed onset of dystrophic symptoms in the limb muscle of young mdx mice, but did not prevent degeneration and regeneration events occurring later in the disease course. Long-term treatment had a positive effect on limb muscle pathology, reduced fibrosis, increased sarcolemmal stability, and promoted muscle regeneration in older mice. However, streptomycin treatment did not show positive effects in diaphragm or heart muscle, and heart pathology was worsened. Thus, blocking calcium channels even before disease onset does not prevent dystrophy, making this an unlikely treatment for DMD. These findings highlight the importance of analyzing several time points throughout the life of the treated mice, as well as analyzing many tissues, to get a complete picture of treatment efficacy.     

Segmental myofiber necrosis in myotonic dystrophy - An immunoperoxidase study of immunoglobulins in skeletal muscle.

Because serum immunoglobulin G levels are low in patients with myotonic dystrophy, it was hypothesized that it might be catabolized within abnormal muscle fibers. Accordingly, immunohistochemical stains for immunoglobulins were performed on muscle sections derived at biopsy or autopsy from patients with myotonic dystrophy, other forms of muscular dystrophy, nondystrophic muscle disease, or normal muscle. Positive staining for immunoglobulins was found only in necrotic segments of myofibers (in 7 of 19 dystrophic and 6 of 27 nondystrophic subjects), and it is believed that the staining was due to nonspecific diffusion. However, staining reactions distinguished between incipient necrosis and artifactual contraction bands and allowed us to study segmental myofiber necrosis, comparing its frequency in the various muscle diseases. Segmental myofiber necrosis was present in 4 of 16 cases of myotonic dystrophy. The relevance of this finding to the clinical and morphologic features of myotonic dystrophy is discussed.     

Muscle histology in fetuses at risk for Duchenne muscular dystrophy

Quadriceps muscle samples taken from four therapeutically aborted male fetuses (16 to 21 weeks gestation) at risk of developing Duchenne muscular dystrophy have been examined histologically. Two of the four samples were indistinguishable from normal fetal muscle of comparable gestation. A slight increase in variability of fibre size and in mean fibre diameter was found in the third fetus. The fourth fetus, of 16 weeks gestation, showed a marked increase in variability of fibre size and in mean fibre diameter. There was also a significant number of hyaline fibres present. These changes are so similar to those reported in early pre-clinical Duchenne muscular dystrophy, that it is suggested they represent the earliest histological signs of the disorder which is already manifest in utero .     

Mosaic expression of dystrophin in symptomatic carriers of Duchenne's muscular dystrophy

A deficiency of the protein dystrophin is known to be the cause of Duchenne's muscular dystrophy. To examine the expression of dystrophin in symptomatic female carriers of this X-linked recessive disorder, we performed immunohistochemical studies on muscle-biopsy specimens from three such carriers, using an antiserum raised against a synthetic peptide fragment of dystrophin. In all three carriers, most individual muscle fibers reacted either strongly or not at all to the antiserum for dystrophin; only 2 to 8 percent of fibers showed partial immunostaining. This mosaic staining pattern was present on both cross-sectional and longitudinal muscle specimens. Although the mosaic pattern was seen in all fiber types, more than 80 percent of type 2B and 2C fibers from two of the carriers did not react with the antiserum. Similar studies in nine normal subjects showed consistently strong staining of all muscle fibers. No muscle fibers from 31 patients with Duchenne's muscular dystrophy reacted with the antiserum. We conclude that symptomatic carriers of Duchenne's muscular dystrophy can be identified by a distinct mosaic pattern in the immunohistochemical staining of the surface membrane of skeletal-muscle specimens. This finding may have practical implications for genetic counseling, although it remains to be shown whether the same staining pattern will be found in muscle specimens from asymptomatic carriers of Duchenne's muscular dystrophy.     

Cytofluorometric determination of nuclear DNA in heart muscles of patients with muscular dystrophy

The degree of DNA-polyploidy of cardiac muscle cells was investigated by cytofluorometry in 4 cases of progressive muscular dystrophy (DMP) and 2 cases of myotonic dystrophy (DM), and the results were compared with those for non-dystrophic hearts of normal or increased weight. The heart muscle cells from all patients with these forms of dystrophy showed marked nuclear DNA hyperploidy reaching 16c, irrespective of cardiac hypertrophy or atrophy. In the non-dystrophic group, DNA hypertrophy corresponding to that of dystrophy was only detected in cases of marked cardiac hypertrophy exceeding a weight of 400 g. The wasting of the respiratory musculature, deformity of the thorax and cardiac muscular atrophy appeared to be the principal factors causing DNA polyploidy in patients with muscular dystrophy.     

Ocular myopathies

Ocular myopathies are manifested by primary and progressive involvement of extraocular muscles. In most cases of involvement of extra-ocular muscles a biopsy from somatic muscles studied by histochemistry and electron microscopy permits to make the diagnosis of the underlying condition. The two main clinico-pathological types of ocular myopathies are the oculocraniosomatic syndrome (Kearns-Sayre syndrome) and oculopharyngeal muscular dystrophy. The oculocraniosomatic syndrome is a multisystemic disorder and its histopathological hallmark is the presence of ragged-red muscle fibres which contain aggregates of abnormal mitochondria, often with paracrystalline inclusions. In the oculopharyngeal muscular dystrophy are observed muscle fibres with rimmed vacuoles and intranuclear tubular filamentous inclusions about 8.5 nm in external diameter. The rimmed vacuoles may occur in other muscle diseases but the intranuclear inclusions appear to be specific for oculopharyngeal muscular dystrophy. Their nature is unknown.     

Distinction between Duchenne and other muscular dystrophies by ribosomal protein synthesis.

Ribosome concentration, ribosome distribution on sucrose density gradients, and in-vitro ribosomal amino-acid incorporation (noncollagen and collagen synthesis) were studied in muscle biopsy samples obtained from 30 patients with Duchenne muscular dystrophy, seven patients with Becker muscular dystrophy, and 10 with facioscapulohumeral muscular dystrophy. Ribosome concentration was normal in Duchenne and facioscapulohumeral and decreased in Becker muscular dystrophy. Distribution of ribosomes in sucrose density gradients showed abnormalities (sharp monosomal peak and fewer polyribosomes) only in Duchenne muscular dystrophy and was normal in the other two types. In-vitro amino-acid incorporation of ribosomes in Duchenne muscular dystrophy revealed high collagen and low noncollagen synthesis of the heavy polyribosomes. This abnormality is controlled by an undetermined enzymatic factor belonging to the soluble enzyme fraction. Supplementation of the dystrophic heavy polyribosomes with normal soluble enzymes restored the synthesis of collagen to that of the controls. Heavy polyribosomes extracted from normals or from carriers produce proportionately more collagen in the presence of soluble enzyme fraction from Duchenne muscular dystrophy than in the presence of their homologous enzymes. In Becker muscular dystrophy, both noncollagen and collagen synthesis of the heavy polyribosomes were increased, under the influence of ribosomal factors. The different protein synthesis in Duchenne and Becker muscular dystrophies suggests that these conditions are non-allelic. In facioscapulohumeral muscular dystrophy the changes in protein synthesis occurred only in the early stage of the disease and consisted of increased noncollagen synthesis of the light polyribosomes, while the heavy polyribosomes had normal activity including collagen synthesis. This reaction was controlled by ribosomal factors.     

Localization of O-GlcNAc-modified proteins in neuromuscular diseases

O-linked N-acetylglucosamine (O-GlcNAc) is a ubiquitous post-translational modification of nucleocytoplasmic proteins that induces the attachment of N-acetylglucosamine to serine or threonine residues of a protein. In contrast to other protein glycosylations, this modification is highly reversible and, similar to phosphorylation, it plays important roles in various cell signals. Here, we immunolocalized O-GlcNAc-modified proteins in muscle biopsy specimens from 40 patients with neuromuscular diseases and controls. In normal muscle fibers, O-GlcNAc was found along plasma membranes and in nuclei. Diffuse and increased cytoplasmic staining of O-GlcNAc was detected in (1) regenerating muscle fibers in muscular dystrophy, myositis, and rhabdomyolysis; (2) a proportion of atrophic fibers in myositis, such as those found in perifascicular regions in dermatomyositis; and (3) vacuolated fibers in sporadic inclusion body myositis (s-IBM) and distal myopathy with rimmed vacuoles (DMRV). Target formations in neurogenic muscular atrophy were O-GlcNAc positive. Increase of O-GlcNAc glycosylation could be associated with the stress response, as these lesions have been shown to be positive for several stress markers. Vacuolar rims in s-IBM and DMRV were sometimes sharply lined by O-GlcNAc-positive deposits, which reflects myonuclear breakdown occurring from the disease.     

Hypotonic medium increases calcium permeant channels activity in human normal and dystrophic myotubes

Duchenne muscular dystrophy (DMD) is characterized by the absence of dystrophin and an elevated intracellular calcium level. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique. The present study shows, on human co-cultured normal and dystrophic muscle cells, the evidence for an increased activity of calcium permeant cationic mechano-sensitive channels under hypotonic medium stimulation. This activity was particularly enhanced in DMD cells. The hypotonic medium induced drastic changes in the single-channel activity characteristics, which are: a large increase of the calcium over potassium permeability ratio; and a great enhancement of the quantity of current crossing through these channels. These channels could contribute to a significant calcium entry, which could participate in the abnormal calcium homeostasis observed in DMD muscle.     

Opioid receptors in skeletal muscle of normal and dystrophic mice

Autoradiography was used to investigate the presence of opioid receptors in soleus, extensor digitorum longus (EDL) and diaphragm muscles in two strains (C57BL/6J and C57BL/10) of mice which can inherit muscular dystrophy. Binding sites for two radiolabelled opioid ligands [125I]beta-endorphin and [3H]naloxone, were seen in a few muscle fibres in the normal mice. However, a significantly greater number of fibres exhibited the binding sites in the dystrophic individuals of both strains. The binding sites were not restricted to the endplate regions but were present over the entire surface in these fibres.     

Cytofluorometric Determination of Nuclear DNA in Heart Muscles of Patients with Muscular Dystrophy

The degree of DNA polyploidy of cardiac muscle cells was investigated by cytofluorometry in 4 cases of progressive muscular dystrophy (DMP) and 2 cases of myotonic dystrophy (DM), and the results were compared with those for non dystrophic hearts of normal or increased weight. The heart muscle cells from all patients with these forms of dystrophy showed marked nuclear DNA hyperploidy reaching 16c, irrespective of cardiac hypertrophy or atrophy. In the non dystrophic group, DNA hypertrophy corresponding to that of dystrophy was only detected in cases of marked cardiac hypertrophy exceeding a weight of 400 g. The wasting of the respiratory musculature, deformity of the thorax and cardiac muscular atrophy appeared to be the principal factors causing DNA polyploidy in patients with muscular dystrophy. Acta Pathol Jpn 39: 566 572,1989.