Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1762617 (weakness)
 37,932 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nemaline myopathy occurred sporadically in a 59-year-old woman. She had slowly progressive weakness. A muscle biopsy specimen showed nemaline rods, increased variation in fiber size, apparent loss of Type IIb fiber differentiation, and a "moth-eaten" pattern of the intermyofibrillar network. At least 44 cases of this disorder have been reported. Clinically, they showed several different modes of onset, patterns of muscle group involvement, and rates of progression. There was a suggestion of familial involvement in at least half. In addition to the presence of nemaline rods, pathological abnormalities of muscle biopsy specimens were quite variable. Results of recent biochemical studies have shown abnormal myosin in a patient with rod myopathy. A hypothesis is proposed that relates the diverse clinical and histological features of this disease to a hereditary molecular abnormality of myosin synthesis.
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PMID:Nemaline myopathy. 58 Jul 14

Patients with thyroid deficiency often complain of muscular weakness, exercise intolerance, cramps and excessive fatiguability. Hypothyroidism induces a metabolic myopathy, with a fall of the energetic production, and especially of the mitochondrial metabolism. This is due to a global inhibition of the main oxidative pathways (substrate incorporation, substrate oxidation) and of the respiratory chain. A diminished energetic consumption is partially related to a transition in the myosin isoforms, which express a slower ATPase, and to an impairment of the trans-sarcolemic transports. Exercise intolerance could be due to an abnormal recruitment of several metabolic pathways, such as glycolysis, related to the mitochondrial metabolism impairment, and including an abnormal accumulation of protons and monovalent phosphate ions, which are involved in the alteration of the actin-myosin interaction, and also by an abnormal Ca++ metabolism. The decreased number of NA+/K+ ATPase dependent pumps could imply an abnormal intracellular Na+ level and explain the frequent disorders of the membrane excitability.
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PMID:[Hypothyroid myopathy. Physiopathological approach]. 133 62

This report provides a preliminary sketch of the results obtained in a two-dimensional time resolved X-ray diffraction study of "live" frog sartorius muscles undergoing isometric tetani. These results demonstrate the recently developed capability to record time resolved (10 msec time resolution), two-dimensional X-ray diffraction diagrams throughout the cycle of contraction. The correlation between the time courses of the diffraction features in the whole of the diffraction diagram establishes a sequence of structural events, which suggest that during the transition from rest to the plateau of tension and the subsequent recovery, the following sequence of events takes place: a) Following the activation phase, which is best monitored by the increase of intensity on the second actin layer line at 18.0 nm spacing (5), there is the onset of three dimensional disorder due to the filaments losing their axial alignment and the myosin heads rotating azimuthally and moving radially outwards. A set of low-angle layer lines, following the actin based spacings seen in rigor (i.e., at spacings of ca. 36.5-37.5, 24.0 and 18.0 nm) become visible and those at ca. 24.0 and 18.0 nm appear to increase in intensity during this phase with a time course that cannot be determined accurately because of the proximity of the neighbouring first, second and third myosin layer lines and the weakness of these diffraction features. Whether the first of these layer lines increases or not is difficult to ascertain. Moreover, proper account of the loss in crystallinity during the development of tension must be made before the comparisons in intensity between the rest and peak of tension states have any significance. Nevertheless, these features together with the behaviour of the equatorial reflections and the meridional region of the third myosin layer line indicate that a sizeable fraction of the crossbridges may become axially disposed with an actin based periodicity. The formation of this complex does not immediately result in the generation of tension. The labelling of the thin filaments is also reflected in the main actin layer lines at 5.9 and 5.1 nm. b) The tension generating phase is monitored by the intensity changes in the meridional region of the third myosin layer line, which are best explained by a change in the orientation/conformation of the tension bearing crossbridges, (which probably adopt a more perpendicular orientation to the filament axis). c) At the end of stimulation, the crossbridges return to an axial spacing and axial orientation (although not yet azimuthal) similar to the one at rest.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Two-dimensional time resolved X-ray diffraction of muscle: recent results. 175 57

The authors report a case of hypothyroid hypertrophic myopathy consecutive to mantle irradiation for Hodgkin's disease. A rise in TSH level is frequent after mantle irradiation and it justifies prolonged monitoring of these patients' thyroid function, in view of the risk of patent hypothyroidism and perhaps cancer. The patient's age, the pre-irradiation lymphography and the chemotherapy associated with radiotherapy are all factors that influence the incidence of thyroid dysfunction, but there is no agreement concerning their relative importance. Hypertrophic myopathies due to hypothyroidism are rare, and their dramatic clinical presentation contrasts with an almost normal muscle histology. Alterations of energy metabolism and changes in the properties of myosin induced by hormonal deficiency account for the muscular weakness of these patients. On the other hand, the mechanism of muscle hypertrophy remains controverted, the most probable theory being and increase in the number of myotubes. Following irradiation, notably for Hodgkin's disease, the frequency of hypothyroidism requires a regular and systematic laboratory follow-up. Replacement therapy must be instituted if the basal TSH level increases, even if the T4 level is normal.
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PMID:[Hypothyroid hypertrophic myopathy following mantle irradiation for Hodgkin's disease. A case]. 189 13

We examined serum cardiac myosin light chain I (LCI), serum creatine kinase (CK) levels and left ventricular function in patients with muscular dystrophy and secondary cardiac involvement. LCI levels were determined by a two-site immunoradiometric assay method in 25 patients with muscular dystrophy and 10 normal subjects. This study included 15 patients with Duchenne muscular dystrophy (DMD), 8 patients with Fukuyama type congenital muscular dystrophy (FCMD) and 2 sisters with non-Fukuyama type congenital muscular dystrophy (nFCMD). We measured the value of left ventricular fractional shortening (FS) using echocardiography. All patients with DMD and FCMD showed moderate or severe skeletal muscle weakness. The mean values of LCI were significantly higher in patients with DMD (11.0 +/- 8.3 ng/ml, p less than 0.01) and in patients with FCMD (1.6 +/- 1.4 ng/ml, p less than 0.05) than in normal subjects (0.3 +/- 0.2 ng/ml). In patients with DMD, LCI level correlated closely with CK level (r = 0.81, p less than 0.01) but not with FS (r = 0.35, n.s.). In patients with FCMD, LCI level correlated significantly with CK level (r = 0.75, p less than 0.05) but not with FS (r = 0.44, n.s.). Close correlation between LCI and CK levels was thought to result from the cross reaction between cardiac LCI and myosin light chains of skeletal muscle in the assay method we used. Two siblings with nFCMD showed mild skeletal muscle weakness. A 22-year-old sister with mild left ventricular dysfunction (FS = 0.41) showed high level of CK (4794/U/L) and mild elevation of LCI (7.3 ngml).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Clinical significance of serum cardiac myosin light chain I in patients with muscular dystrophy]. 225 17

Two-dimensional gel electrophoresis (2DE) was used to compare the protein composition of human muscle biopsies that were shown by histochemical staining to be deficient in either type 1 or type 2 fibers. Distinct quantitative differences were found in the myofibrillar protein composition of muscle from a 43-year-old woman with proximal limb weakness that showed almost total absence of type 1 fibers and muscle from a 2.5-year-old girl with congenital myopathy in which there was severe lack of type 2 fibers. These data indicate that human type 1 and type 2 muscle fibers express distinct isoforms of myosin light chains and alpha-tropomyosin.
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PMID:The expression of myosin light chains and tropomyosin in human muscle biopsies with histochemical type 1 and type 2 fiber deficiency. 232 42

We measured the intrinsic mechanical properties and protein content of single skinned muscle fibers obtained from patients who had Duchenne muscular dystrophy. To check for possible nonspecific changes caused by muscle disease per se, we also studied the properties of muscle fibers obtained from patients exhibiting severe muscle weakness due to polymyositis. Relative to control fibers obtained from 4 patients with normal or nonmyopathic muscle, we found no significant changes in the ability of muscle fibers from the patients with Duchenne muscular dystrophy or polymyositis to generate active tension in response to calcium or resting tension in response to stretch. In addition, we found no significant changes in the concentrations of the major contractile proteins myosin and actin, of the elastic protein titin, or of the structural proteins nebulin and alpha-actinin. In contrast, immunocytochemical studies showed that dystrophin was absent in the biopsy specimens from the patients with Duchenne muscular dystrophy, but localized at the cell membrane in all of the other muscle biopsy specimens used in this study. These results indicate that myofibrils assemble and function normally in Duchenne muscular dystrophy. Therefore, the absence of dystrophin, which is the primary biochemical defect in this disease, leads to clinical weakness by causing the breakdown of muscle fibers that were once capable of generating normal force, while the surviving fibers exhibit normal contractility.
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PMID:Single skinned muscle fibers in Duchenne muscular dystrophy generate normal force. 236 Aug

Isolated single myocytes were prepared from myocardium of developing ventricular aneurysms and from myocardium within the scar of chronic ventricular aneurysms. The morphology and function of the individual cells were compared. The cells from developing aneurysms were rod-shaped, with a distinct sarcomeric structure, but did not contract even in the presence of high calcium concentrations. The sarcomere length was significantly higher than that of cells from chronic aneurysms and approached the theoretical point at which no contraction can occur. Cells from chronic aneurysms were either rod-shaped and contractile, or rounded due to hypercontracture of the myofilaments. Electron microscopy of cells from developing aneurysms confirmed the presence of elongated sarcomeres, a loss of the actin-myosin interdigitation, and damage to the contractile proteins which was particularly evident in the thin filaments. Cells with similar characteristics have also been isolated from a ruptured, ischaemic papillary muscle. These changes, which are due either to ischaemia or to overstretching of cells, may account for the weakness of the wall of developing aneurysms and be a cause of rupture or enlargement.
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PMID:Morphological and functional characteristics of myocytes isolated from human left ventricular aneurysms. 259 43

Absence of thick filaments from the A bands in tissue giving apparently normal histochemical reactions for myosin ATPase, was seen in a case of acute onset muscle weakness progressing rapidly to quadriplegia with cerebral involvement. There was also widespread degeneration of interstitial structures and much phagocytosis. The dissociation of structure and function of the thick filaments suggests that a selective injury occurred within the myosin molecule. The etiology of the condition although clinically suggestive of a polyneuropathy remains pathologically uncertain. Toxic, immunological or viral causation may be responsible.
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PMID:Thick filament degeneration in a case of acute quadriplegia. 644 66

Antibodies to human skeletal muscle myosin were detected in 90% of sera from patients with polymyositis by radioimmunoassay using purified human myosin as antigen, and the mean titre was 4.24 X 10(-10)M. The incidence and the mean titre of anti-myosin antibodies were significantly higher than in patients without polymyositis. Anti-myosin antibody titres correlated with steroid therapy in polymyositis patients. Titres in untreated patients with polymyositis correlated with the severity of muscle weakness. Radioimmunoassay for anti-myosin antibodies should prove to be useful in the diagnosis of polymyositis and the evaluation of clinical state.
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PMID:Radioimmunoassay for antibodies to human skeletal muscle myosin in serum from patients with polymyositis. 686 76


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