Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have been searching for enzyme inhibitors in culture filtrates of microbes and have found leupeptin, antipain, chymostatin, elastatinal, pepstatin, hydroxypepstatin, pepstanone and phosphoramidon as specific inhibitors of serine, thiol, carboxyl and metallo proteases. We found significant activities of aminopeptidases, phosphatase and esterase on surface membranes of various mammalian cells. We discovered bestatin, amastatin, forphenicine, esterastin and ebelactones A and B as specific inhibitors against these enzymes. These inhibitors were proved to bind to cells and modify immune responses. The usefulness of bestatin in cancer treatment has been suggested by clinical studies. It has been shown by several investigators that some endopeptidases such as Ca2+-activated neutral proteases and some other serine proteases may play important roles in muscular dystrophy. In addition to these endopeptidases, we found an abnormal increase in various enzyme activities in dystrophic mice and chickens. Especially, aminopeptidase activities are markedly increased. Moreover, its inhibitor bestatin became interesting on the aspects of its binding to cell surfaces. Bestatin and leupeptin which inhibit Ca2+-dependent protease showed some therapeutic effects against mouse dystrophy. Investigating enzyme activities in synovial fluid of patients with rheumatoid arthritis and osteoarthritis, we found increased activities of aminopeptidases, chymotrypsin-like enzyme, and phosphatase in rheumatoid arthritis but not in osteoarthritis. In chronic hemodialysis patients, RNase activity in serum is markedly elevated. Thus, enzyme inhibitors are increasing their potential usefulness in treatment of various diseases.
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PMID:The relationships between enzyme inhibitors and function of mammalian cells. 704 7

Calcium accumulates in muscles of dystrophic hamsters (DH) and patients with Duchenne muscular dystrophy. Various Ca antagonists were beneficial to the cardiomyopathy of DH, but had only minor effects on skeletal muscle. We administered a new Ca antagonist, diltiazem, 25 mg/kg/day orally to normal and dystrophic hamsters from ages 37 to 92 days. We observed a marked reduction in muscle Ca in DH treated with diltiazem: 73% in the heart, 61% in the diaphragm, and 48% in the rectus femoris. Plasma CK was significantly lower (by 37%) in treated DH, while the elevated rate of noncollagen protein synthesis in the diaphragm was not diminished. Histologically, the most important change was a reduction in Ca deposits in the heart. Diltiazem was well-tolerated by all animals and did not modify Ca content in normal hamsters. This study suggests that diltiazem may have therapeutic value in those conditions that are accompanied by excessive accumulation of Ca in tissues, such as muscular dystrophy.
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PMID:The effects of diltiazem in dystrophic hamsters. 705 11

An early and significant biochemical abnormality in Duchenne's muscular dystrophy is an increase in intracellular calcium. We have found that the "calcium-blocker" drug verapamil inhibits calcium-stimulated efflux of creatine kinase (EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) in vitro from normal human skeletal muscle at therapeutic concentrations. Such a calcium blocker might therefore be useful in the treatment of Duchenne's muscular dystrophy.
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PMID:Verapamil and calcium-stimulated enzyme efflux from skeletal muscle. 708 59

Recently it was reported that calcium-dependent phosphatidic acid synthesis in erythrocyte of patients with myotonic muscular dystrophy (MyD) is markedly impaired when compared to that in control subjects. Using 32P-loaded erythrocytes, we found no significant difference in the levels of 32P-phosphatidic acid synthesized after exposure to calcium and its ionophore A23187 between patients with MyD and controls. In a batch experiment typical of the experiments with 32P, and a twofold increase of phosphatidic acid in both groups was determined by inorganic phosphate measurements. Thus, the specific activity of the 32P-phosphatidic acid increased four- to five-fold in response to calcium Analyses of 32P-polyphosphoinositide breakdown in ghosts and in adenosine triphosphate-depleted erythrocytes also appeared normal for patients with myotonic muscular dystrophy. Possible discrepancies between the results presented here and those reported previously are discussed.
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PMID:Myotonic dystrophy: calcium-dependent phosphatidic acid synthesis in erythrocytes. 730 3

In chicks maintained on a rachitogenic (vitamin D deficient) diet, the number of intestinal absorptive cell calcium-lysosomes is markedly decreased in comparison to normal animals. In addition, the majority (better than 50%) of these rachitic calcium-lysosomes are atypical in their fine structure resembling the lamellar bodies seen in certain diseases (Tay-Sachs disease, Duchenne's muscular dystrophy). Such atypical organelles are characterized by their internal membranous swirls reminiscent of myelin figures. This information appears to be a further indication that lysosomes are normally involved in calcium homeostatic mechanisms and therefore sensitive to circulating vitamin D levels.
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PMID:Ultrastructural changes in the lysosomes of rachitic intestinal absorptive cells. 733 Aug 54

Myotonic muscular dystrophy (MyD) is a systemic genetic disorder that is thought to result from a generalized cellular membrane defect although the exact nature of this defect is unknown. This study examines two calcium-dependent membrane processes that have been observed in erythrocytes from healthy individuals: calcium-stimulated phosphatidic acid accumulation and calcium-induced potassium leak. We find that erythrocytes from MyD patients, in contrast to controls, have markedly impaired phosphatidic acid accumulations while maintaining normal potassium leaks. The calcium uptakes and ATP contents of MyD erythrocytes are not different from controls. We conclude that phospholipid metabolism is altered in MyD erythrocytes. The specificity of this abnormality and its relationship to altered muscular function are not known.
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PMID:Myotonic muscular dystrophy: defective phospholipid metabolism in the erythrocyte plasma membrane. 741 May 51

1. We examined the activity of single mechanosensitive ion channels in recordings from cell-attached patches on myoblasts, differentiated myotubes and acutely isolated skeletal muscle fibres from wild-type and mdx and dy mutant mice. The experiments were concerned with the role of these channels in the pathophysiology of muscular dystrophy. 2. The predominant form of channel activity recorded with physiological saline in the patch electrode arose from an approximately 25 pS mechanosensitive ion channel. Channel activity was similar in undifferentiated myoblasts isolated from all three strains of mice. By contrast, channel activity in mdx myotubes was approximately 3-4 times greater than in either wild-type or dy myotubes and arose from a novel mode of mechanosensitive gating. 3. Single mechanosensitive channels in acutely isolated flexor digitorum brevis fibres had properties indistinguishable from those of muscle cells grown in tissue culture. The channel open probability in mdx fibres was approximately 2 times greater than the activity recorded from wild-type fibres. The overall level of activity in fibres, however, was roughly an order of magnitude smaller than in myoblasts or myotubes. 4. Histological examination of the flexor digitorum brevis fibres from mdx mice showed no evidence of myonecrosis or regenerating fibres, suggesting that the elevated channel activity in dystrophin-deficient muscle precedes the onset of fibre degeneration. 5. An early step in the dystrophic process of the mdx mouse, which leads to pathophysiological Ca2+ entry, may be an alteration in the mechanisms that regulate mechanosensitive ion channel activity.
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PMID:Mechanosensitive ion channels in skeletal muscle from normal and dystrophic mice. 753 13

A calcium-dependent proteinase (calpain) has been suggested to play an important role in muscle degradation in Duchenne muscular dystrophy (DMD). In immunohistochemical studies, calpain and its endogenous inhibitor (calpastatin) were located exclusively in the cytoplasm in normal human muscles. The intensity of the staining was stronger in type 1 than in type 2 fibers. Quantitative immunohistochemical study showed an increase of calpain in biopsied muscles from the patients with DMD and Becker muscular dystrophy. Abnormal increases in calpain and calpastatin were demonstrated mainly in atrophic fibers, whereas necrotic fibers showed moderate or weak immunoreactions for the enzymes. Opaque fibers and hypertrophic fibers were negative. Not all dystrophin-deficient muscle fibers necessarily showed a strong reaction for calpain. We suggest that calpain may play an important role in muscle fiber degradation, especially in the early stage of muscle degradation in muscular dystrophy.
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PMID:Immunohistochemical study of calpain and its endogenous inhibitor in the skeletal muscle of muscular dystrophy. 761 37

Duchenne's dystrophy (DMD), a recessive chromosome X-related disease, is the most common and severe form of myopathy. The different theories (vascular, neurogenic, membraneous, calcic and auto-immune) formulated to account for this disease have not been swept away by the discovery of the DMD gene and the deficient protein, dystrophin, since the exact cellular role played by the latter is still unknown. Our work on skeletal muscle has demonstrated a mitochondrial deficiency of the calcium-specific protein, calmitine, in degenerating muscle of myopathic persons and animals. Considering its great affinity for calcium, this protein specific to skeletal muscle could be essential to mitochondrial calcium regulation and thus to the functioning of the entire muscle cell. Its deficiency in Duchenne's and Becker type muscular dystrophy could be due to a mitochondrial genome alteration solely accountable for muscular degeneration. This hypothesis challenges the supposedly essential but still undefined role that researchers have attributed to dystrophin.
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PMID:Muscular degeneration in Duchenne's dystrophy may be caused by a mitochondrial defect. 766 33

In various neuromuscular diseases, the most significant muscle degeneration is muscle fiber necrosis as seen in Duchenne muscular dystrophy (DMD). A certain membrane instability is probably responsible for muscle fiber necrosis, because defects in membrane proteins have been proposed to associate with progressive muscular dystrophies including dystrophin in DMD, a 50 KD subunit of dystrophin associated glycoprotein (DAG) in severe childhood autosomal recessive muscular dystrophy (SCARMD), and subunit M of laminin (merosin) in congenital muscular dystrophy and dy mouse. The vulnerable muscle surface membrane may permit extracellular calcium influx into the sarcoplasm resulting in focal myofibrillar hypercontraction (opaque fiber) and activation of proteases such as calpain and cathepsins. The muscle fiber then undergoes necrosis and allows macrophage invasion, followed by muscle fiber regeneration. Focal myofibrillar degeneration involving rimmed vacuole (RV) formation is an another striking muscle fiber degeneration seen in various neuromuscular diseases including inclusion body myositis (IBM) and distal myopathy with rimmed vacuole formation (DMRV). Abnormal accumulation of ubiquitin, beta-amyloid protein precursor and tau protein has been described in IBM by Askanas et al. The similar findings are also recognizable in DMRV and in an experimentally induced myopathy after long-term chloroquin administration to rat. Therefore, if we clarify the pathomechanism of degenerative process involved in the rimmed vacuole formation, the results may provide some insights into the understanding the process involved in amyloid plaque formation in Alzheimer's disease.
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PMID:[Muscle pathologic diagnosis--mechanism in muscle fiber degeneration]. 777 35


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