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Imidazole myopathy. Production of the myopathy and its dependence on acetylcholine.

An acetylcholine-mediated myopathy has been produced in the soleus muscle of the rat by the daily injection of imidazole, a compound that accelerates the metabolism of adenosine 3':5' cyclic phosphate by activating the enzyme phosphodiesterase. The imidazole-treated muscles were found to have a lowered resting membrane potential. This study suggests that a decrease in resting membrane potential may make skeletal muscle more vulnerable to necrosis by acetylcholine released during normal activity.

Acetylcholine

Agonist-induced myopathy at the neuromuscular junction is mediated by calcium.

Inactivation of cholinesterases at mammalian neuromuscular junctions (nmj) produces extensive muscle "necrosis." Fine-structurally, this myopathy begins near the nmj with an increase in large-diameter vesicles in the soleplasm, the dissolution of Z-disks, dilation of mitochondria, destruction of sarcoplasmic reticulum, and often a highly specific contracture of the muscle under the endplate. Since a Ca++-activated protease which specifically removes Z-disks is known to exist in mammalian skeletal muscle, we tested the possibility that the myopathy after esterase inactivation is due to the prolongation of acetylcholine lifetime and thus of Ca++ influx. We first produced the myopathy near endplates by inactivating esterases with diisopropylfluorophosphate (DFP) followed by nerve stimulation for 1--2 h in vitro. The myopathy was later mimicked by bath application of carbamylcholine without esterase inhibitors. This myopathy could be prevented by inactivating the acetylcholine receptors (AChR) with alpha-bungarotoxin (alpha-BGT) or by removing Ca++ from the bath with EGTA. These results favor the hypothesis that esterase inhibition leads to an agonist-induced myopathy, which is mediated by Ca++ and requires an intact AChR.

Animals

Changes in motor innervation and histochemical pattern of muscle fibers in some congenital myopathies.

Changes in motor innervation were compared with histologic and histochemical pattern of muscle fibers in three biopsies of central core disease, four biopsies of nemaline myopathy, one biopsy of myotubular myopathy, and three biopsies of mitochondrial myopathy. Evidence of collateral reinnervation was obtained only in one biopsy from central core disease. In other biopsies, no structural or ultrastructural abnormality of axis cylinders, myelin, or myoneural junction suggesting denervation were observed. The only relevant change found in centronuclear myopathy and to a lesser extent in nemaline myopathy was an unusual smallness and simplication of motor endings, suggesting delayed or impaired maturation. Muscle fibers strongly reactive for both adenosinetriphosphatase and nicotinamide-adenine dinucleotide diaphorase, observed in central core disease and mitochondrial myopathy, were not associated with increased terminal innervation ratio.

Adolescent

Progressive systemic sclerosis of the gastrointestinal tract and hereditary hollow visceral myopathy: two distinguishable disorders of intestinal smooth muscle.

The purpose of this study was to determine whether progressive systemic sclerosis (PSS) of the gastrointestinal tract and hereditary hollow visceral myopathy are two distinguishable disorders of intestinal smooth muscle. We coded and blindly reviewed 50 specimens of tissue from the small intestine of 15 normal controls, 4 patients with visceral myopathy, 5 patients with PSS and intestinal pseudoobstruction, and 5 patients with PSS but no pseudoobstruction. We determined that there is a fundamental difference between the pathology of these two disorders. In visceral myopathy, the smooth muscle is characterized by vacuolar degeneration and fibrosis. In PSS, smooth muscle fibrosis is present but vacuolar degeneration is absent. Although smooth muscle cells are decreased in number in both disorders, those that are present in PSS are morphologically normal by light microscopy, whereas most of those present in visceral myopathy are degenerated. Visceral myopathy and gastrointestinal PSS are two distinct disorders of smooth muscle which are easily distinguished by conventional light microscopy. Their dissimilar appearances and the familial nature of visceral myopathy suggest that they result from quite different causes.

Adolescent

Hypokalemic vacuolar myopathy of chronic alcoholism. A histological and histochemical study.

Recent reports have emphasized the occurrence of a myopathy in chronic alcoholism associated with hypokalemia. This report of hypokalemic myopathy in a chronic alcoholic, emphasizes the primary myopathic nature of the condition and attributes it to a possible non-specific effect of the hypokalemia on skeletal muscle. It is pointed out, that histological and histochemical changes of muscle in this type of myopathy are indistinguishable from other types of hypokalemic myopathies like periodic paralysis. It is conjectured that in alcoholic myopathy, the underlying disorder might be related to a primary disturbance of potassium metabolism, though in most cases, serum potassium is normal. It is likely that studies aimed at studying total body potassium content and turnover in alcoholic myopathy would help in understanding its pathogenesis and possible relationship to disturbed potassium metabolism.

Adult

Necrotizing myopathy as a remote effect of gastric cancer accompanied with Hashimoto's thyroiditis.

An autopsy case of a 74-year-old male who had shown clinically hypothyroidism due to chronic atrophic thyroiditis (Hashimoto's thyroiditis), and pathologically necrotizing myopathy as a remote effect of gastric cancer was reported. Morphological features of this necrotizing myopathy was those of carcinomatous myopathy rather than those of hypothyroid or diabetic myopathy. As for the pathogenesis of the necrotizing myopathy (as a Group IV of polymyositis of Walton and Adams), the malignancy might have played an important role as a trigger of the secondary immunological abnormality upon a pre-existing longstranding immune disorder of Hashimoto's thyroiditis. Pseudomembranous colitis, which was thought to be related to antibiotics. (Lincomycin), was also briefly discussed.

Adenocarcinoma

TUBA4A Pathogenic Variant Manifesting With Adulthood-Onset Genetic Myasthenic Syndrome, Myopathy, and Infertility.

OBJECTIVES: TUBA4A pathogenic variants are associated with ALS, frontotemporal dementia, spastic ataxia, spasticity, ataxia, Parkinson's disease, female infertility, macrothrombocytopenia, and myopathy. Four recently reported patients with TUBA4A neonatal/childhood onset myopathy had also a decrement on repetitive nerve stimulation (RNS), but such a finding was not further characterized. We describe a patient with a TUBA4A pathogenic variant with adulthood-onset genetic myasthenic syndrome accompanied by myopathy and infertility to highlight the neuromuscular junction defect as the main feature of the patient's phenotype. METHODS: We reviewed the patient's clinical and laboratory findings and performed transcriptomic analysis on the patient's muscle. RESULTS: A 53-year-old woman with infertility of unknown etiology manifested fatigability and proximal upper limb muscle weakness in her mid-30s, followed by lower limb involvement. Her examination showed proximal muscle weakness and fatigability but spared facial muscles. CK values were mildly elevated. Anti-AChR, MuSK, P/Q-type calcium channel, and LRP4 antibodies were absent. 2 Hz RNS showed decrement (-14% to -48%) in limb muscles that improved with 3,4-dyaminopyridine (3,4-DAP). Facilitation (231%) occurred in the trapezius. Muscle biopsy showed patchy loss of oxidative enzyme reactivity and no C5b9 or IgG at neuromuscular junctions. Whole genome sequencing identified a heterozygous known TUBA4A pathogenic variant (c.850G>A, p.Glu284Lys). Patient improved with 3,4-DAP and albuterol. DISCUSSION: TUBA4A p.Glu284Lys can lead to treatable myasthenic syndrome with postsynaptic and likely presynaptic involvement, as suggested by the patient's electrophysiological findings and response to therapy. This patient expands the TUBA4A-disorder spectrum to include overlapping myasthenic syndrome-myopathy and shows that neuromuscular disease and infertility can occur within the same patient.

Humans

Investigations on the inheritance of nemaline myopathy.

Extensive investigations on 11 patients with nemaline myopathy (six index patients, five relatives), their parents, and some healthy relatives were carried out. In one family, nemaline myopathy was inherited as an autosomal dominant trait. No linkage between the locus of nemaline myopathy and the locus of seven informative genetic markers (out of 25 investigated markers) was found. In two families an autosomal recessive inheritance could be demonstrated with certainty. In these families, both parents of each index patient had rods and an increased number of fibers with internal nuclei. In two other families, one or both parents of each index patient had an increased number of fibers with internal nuclei, also indicating the possibility of autosomal recessive inheritance in these cases. It can be concluded that there are two types of nemaline myopathy. However, these two diseases could not be separated on a clinical or histopathological basis.

Adolescent

Acute carcinomatous myopathy associated with ovarian carcinoma.

A case of acute, fatal, rapidly progressive pure myopathy associated with ovarian carcinoma is described. The first symptoms of carcinomatous myopathy occurred 8 months after surgical treatment and combined chemotherapy. The patient died 2 months after onset of myopathy. The clinical and pathologic findings of the myopathy are discussed.

Adult

Further investigations on benign myopathy with autosomal dominant inheritance.

Six members of a family suffered from benign myopathy over four generations. The clinical, laboratory, electromyographic, histological and genetic data were consistent with benign myopathy with autosomal dominant inheritance. Congenital torticollis was a feature in one patient. Linkage studies revealed no linkage between the locus of this myopathy and the locus of any of 17 genetic markers investigated. This family was of Polish descent, which indicates a widespread occurrence of this benign hereditary myopathy. The data presented are a strong argument in favor of a specific new disease entity.

Adipose Tissue

The pattern of urinary catecholamines and their metabolites in Duchenne myopathy, in relation to disease evolution.

In this report we have tried to determine whether or not catecholamines are involved in the progressive muscular dystrophy. Catecholamines and their metabolites were studied in urines of children with Duchenne disease or other forms of myopathy (limb-girdle and facio-scapulo humeral myopathies). Catecholamine deaminated metabolites were normal in either form of myopathy; in contrast, Duchenne patients, contrarily to other children, eliminated excessive amounts of most amines (catecholamines and methoxylated amines) in relation to age and degree of disease evolution. Our results indicate that catecholamines are not the primary factors involved in the pathogenesis of Duchenne myopathy, but are rather secondary to some disease effects. It is suggested that the high excretion of catecholamines and their methoxylated amine metabolites observed in severely affected Duchenne boys might be related to thermoregulatory process or/and to alterations in some enzymatic systems.

Adolescent

[Congenital centronuclear myopathy. Two morphological variants in one family (author's transl)].

This report deals with a family in which the mother and her two daughters suffer from a congenital, slowly progressive neuromuscular disease. Histological, histochemical and ultrastructural observations of the mother's muscle biopsy reveal the characteristics of the centronuclear myopathy. In this case central nuclei and pericentronuclear abnormalities of muscle fibers are found in almost all fibers. Biopsies obtained of the two daughters show alterations especially of type I-fibers, which often are smaller than normal. The presence of these two forms of centronuclear myopathy in one family indicates that these may be only different morphological types of states of one illness. Additionally, other structural findings (rod bodies, core like regions) emphasize the similarities with other congenital slowly progressive myopathies (nemaline myopathy, central core disease).

Adenosine Triphosphatases

Further studies of mitochondrial and lipid storage myopathies.

Further observations on a family with facioscapulohumeral (FSH) muscular dystrophy due to mitochondrial myopathy, and on a case with lipid storage myopathy are reported. One member of the family with FSH muscular dystrophy died due to a viral pneumonia, during which she developed gross hyperlacticacidaemia and acidosis. Autopsy examination showed that the mitochondrial morphological abnormality was restricted to the skeletal muscle. Two other members of the family, who also had mitochondrial myopathy, have developed a cerebellar syndrome. The skeletal muscle carnitine level in the propositus of this family was normal. A woman with lipid storage myopathy has been shown to have skeletal muscle carnitine deficiency, the plasma carnitine level being only slightly lower than normal.

Adolescent

Metabolic implications of distal atrophy. Carbohydrate metabolism in centronuclear myopathy.

Centronuclear myopathy, like myotonic dystrophy, is characterized by muscle wasting and type 1 fiber atrophy. To determine whether this disorder might include a derangement in carbohydrate metabolism similar to that in myotonic dystrophy, 3 comparably wasted patients with centronuclear myopathy, myotonic dystrophy, and neurogenic atrophy were investigated. The patient with centronuclear myopathy had mild glucose intolerance and hypoinsulinemia after oral glucose ingestion in bold contrast to the normal glucose tolerance and hyperinsulinemia observed in the myotonic dystrophy patient. No abnormality was seen in oral glucose tolerance in the patient with neurogenic atrophy, and all 3 patients had normal insulin tolerance. Forearm insulin infusion demonstrated normal stimulation of muscle glucose uptake in the patients with centronuclear myopathy and neurogenic atrophy in contrast to the markedly diminished response to insulin seen in the patient with myotonic dystrophy. These data indicate that neither distal wasting or type 1 fiber atrophy are responsible for the abnormalities in carbohydrate metabolism in myotonic dystrophy.

Adult

Inflammatory myopathy, IgA deficiency, and intestinal malabsorption.

Two IgA-deficient children with inflammatory myopathy and intestinal malabsorption were evaluated. The myopathy was characterized by weakness of facial and proximal limb muscles, increased serum concentrations of lactic dehydrogenase and creatine phosphokinase, and histologic evidence of inflammation and degeneration of muscle fibers. Features of the intestinal abnormality were blunted villi, interstitial inflammation, and reduction in IgA-containing plasma cells and IgA content of epithelial cells. The myopathy and malabsorption improved with corticosteroid treatment. Circulating antibodies to striated muscle could not be demonstrated in either patient, but one had antibodies to milk and chicken serum proteins. We speculate that IgA deficiency may predispose to the development of inflammatory myopathy.

Autoantibodies

Fatal neonatal nemaline myopathy with multiple congenital anomalies.

The clinical course and autopsy findings in a patient with fatal neonatal nemaline myopathy are described. A hypotonic infant required mechanical ventilatory support immediately following delivery and developed progressive congestive heart failure. He had mild facial dysmorphism, a high-arched palate, clinodactyly, short first metacarpals, abnormal dermatoglyphics, simian creases, and bilateral talipes varus. Light and electron microscopic study of a muscle biopsy was diagnostic of nemaline myopathy. Autopsy revealed a papillary muscle anomaly, myocardial scarring, and hepatic fibrosis. The severe clinical impairment in this infant and the unusual associated anomalies are compared with other examples of nemaline myopathy. Nemaline myopathy is a cause of respiratory insufficiency in the neonatal period.

Abnormalities, Multiple

[Familial form of centronuclear myopathy in the adult].

Two adult cases of centronuclear myopathy are described in a family from French Guyana. One of them, aged 23, has a slight weakness despite hypertrophic muscles. A typical picture of centronuclear myopathy was seen on muscle biopsy with atrophy of type I fibers and hypertrophy of II A fibers. His uncle, aged 53, had a progressive weakness of the lower limbs for the last 25 years, with also a pattern of centronuclear myopathy, but with more dystrophic features and atrophy of both type I and II A fibers. The mode of inheritance is dominant. These two cases are compared with the previously published reports. The pathogenesis of centronuclear myopathy is discussed.

Adult