bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selected IgG rapidly induces Lambert–Eaton myasthenic syndrome in mice: Complement independence and EMG abnormalities
Authors: Lambert Edward H. , Lennon Vanda A. 
Published: January 2005

AbstractAntibodies in individual patients with the Lambert–Eaton myasthenic syndrome (LES) differ in their reactivity with mouse motor nerve terminals. Of 26 LES patients' sera injected a single time into mice, 3 caused a highly significant reduction in stimulus‐dependent quantal release (m) of acetylcholine (ACh) (to 6, 33, and 42 quanta per impulse at 1 Hz, respectively; mean for 10 control sera, 100 quanta at 1 Hz). The most potent serum (LES‐A) was fully effective in mice deficient in complement component C5 and in mice depleted of complement components C3→C9 by cobra venom factor. A single i.v. injection of serum reduced m in direct proportion to log dose. Responses to K+ depolarization and increasing concentrations of Ca2+ were like those observed in human LES.With LES‐A serum, or its IgG, m was reduced near maximally in 1 day and plateaued in 3–4 days. Recovery began after day 8; m was in the normal range by day 20–30. Electromyographic (EMG) abnormalities were not seen until m fell below 40 quanta per impulse at 1 Hz. Below 10 quanta, clinical signs of weakness appeared, and the EMG abnormalities were those classically associated with LES: a marked reduction of compound muscle action potential to a single nerve stimulus in rested muscle, a further decrement during stimulation at slow rates, but marked facilitation during rapid repetitive stimulation.
Axonal transport of choline acetyltransferase and 6‐phosphofructokinase activities in genetically diabetic mice
Authors: Calcutt Nigel A. , Willars Gary B. , Tomlinson David R. 
Published: January 2005

AbstractThis study examined the anterograde axonal transport of activities of the cytoplasmic enzymes choline acetyltransferase and 6‐phosphofructokinase in genetically diabetic C57BL/Ks (db/db) mice and their nondiabetic (+/?) littermates. Diabetic mice exhibited marked reductions in the accumulation of both choline acetyltransferase and 6‐phosphofructokinase activity against a constriction of the left sciatic nerve (38% and 51% of nondiabetic values, respectively). Enzyme activities per unit length of unconstricted nerve were not different from those of nondiabetic mice. The nerves of diabetic mice did not accumulate measurable amounts of sorbitol or fructose and showed no myo‐inositol depletion. Thus this study concludes that, in diabetic mice, the deficits in anterograde axonal transport of these two enzymes do not arise from the accumulation of sorbitol and fructose nor from depletion of nerve free myo‐inositol.
The binding of lipoproteins to human muscle cells: Binding and uptake of LDL, HDL, and α‐tocopherol
Authors: Gurusinghe Asitha , de Niese Michael , Renaud Jean‐Francois , Austin Lawrence 
Published: January 2005

AbstractThe specific binding of low‐density lipoprotein (LDL) to cells and its subsequent uptake into these cells is well documented, but little is known of the LDL binding and uptake by skeletal muscle. Lipoproteins are the major transporters of tocopherols, deficiencies of which have been associated with a number of muscle diseases of animals. Their possible implication in human muscle diseases prompted our investigation of LDL and high‐density lipoprotein (HDL) binding and uptake into human muscle cells in culture. Cultured human muscle cells were used at both the myoblast and myotube stage. They were incubated with LDL or HDL which were labelled by protein iodination or with (3H) α‐tocopherol and receptor binding and cell uptake characteristics established. LDL binds to both myoblasts and myotubes, but the binding affinity increases significantly with the more highly differentiated cells. This binding appears to be specific to LDL receptors.The LDL is taken into the muscle cell and protein is degraded, as with other types of cells. HDL also binds to muscle cells, but there is no evidence of internalization. α‐Tocopherol is transferred to muscle‐cells from both LDL and HDL, but the transfer is not dependent on lipoprotein internalization. HDL is effective as a means of transport of α‐tocopherol to muscle cells, but LDL appears to be about one order more effective.
Metabolic myopathy in canine muscle‐type phosphofructokinase deficiency
Authors: Giger Urs , Argov Zohar , Schnall Mitch , Bank William J. , Chance Britton 
Published: January 2005

AbstractIn vivo 31phosphorus nuclear magnetic resonance spectroscopy (P‐NMR) on the anterior tibialis muscle was used to investigate the metabolic myopathy of inherited muscle‐type phosphofructokinase (PFK) deficiency in four (homozygous) dogs who had mild exercise intolerance, rare muscle cramps, increased serum creatine kinase activity, but no myoglobinuria. During isometric muscle work induced by indirect electrical stimulation, and subsequent recovery, changes in the ratio of phosphocreatine (PCr) and inorganic phosphates (Pi) were comparable in muscle of PFK‐deficient and normal dogs and indicated a large capacity for arobic oxidative phosphorylation in canine muscle. The progressive accumulation of sugar phosphates (PME) during graded exercise clearly demonstrated the glycolytic block in PFK‐deficient dogs. During a muscle contracture, induced by acute muscle stimulation, PFK‐deficient muscle became completely depleted of PCr and ATP, accumulated large amounts of PME, and recovered very slowly. We conclude that PFK‐deficient dogs have a metabolic myopathy that demonstrated some but not all the features recognized in the human disorder.
Scanning electron microscopic study of denervated and reinnervated neuromuscular junction
Authors: Matsuda Yoshiro , Oki Sadaaki , Kitaoka Kenji , Nagano Yoji , Nojima Motoo , Desaki Junzo 
Published: January 2005

AbstractMorphological changes of the subneural apparatus (SNA) during denervation and reinnervation are demonstrated using the hamster peroneus Iongus muscie. One week after nerve section, synaptic grooves (SGs) were more shallow, with lowered sarcoplasmic ridges. After 4 weeks, the whole SNA area was elevated above the sarcolemma as a flat plate, which persisted as a fusiform bulge for more than 8 weeks. There was a rapid and progressive decrease in the number of junctional folds (JFs) and slit‐to‐pit transformation of their openings. There was no trace of the SNA after 16 weeks. By 4 weeks after nerve suture, SGs were flattened but did not form the plate‐like elevation. Many shallow pit‐like JFs still persisted. At 10 weeks, deep SGs started to be restored with an increased number of deep slit‐like JFs. The SNA recovered its normal structural organization by the week 20. However, a few pit‐like vestigial JFs were present outside the groove.
AAEE case report #17: Peripheral neuropathy in monoclonal gammopathy of undetermined significance
Authors: Donofrio Peter D. , Kelly John J. 
Published: January 2005

AbstractMonoclonal gammopathy of undetermined significance (MGUS) is the most common paraproteinemia associated with polyneuropathy. Although the clinical and electrodiagnostic manifestations most resemble those of chronic inflarnmatory demyelinating polyneuropathy, some patients manifest a pure sensory neuropathy or neuronopathy. The M protein is usually IgM, and its concentration in serum is low. Nerve pathology from patients with demyelinating disease shows a reduction of large myelinated fibers and segmental demyelination with remyelination. In some cases, the M protein possesses antibody activity against components of the myelin sheath or axon. These neuropathies may respond to treatment with steroids, immunosuppressant agents, and plasma exchange.
Calcium sensitivity of fast‐and slow‐twitch human muscle fibers
Authors: Ruff Robert L. 
Published: January 2005

AbstractMuscle fibers from the lateral gastrocnemius muscles of five normal adult males were chemically skinned (sarcolemma disrupted) and each fiber was divided into two parts for histochemical determination of fiber type and calcium‐induced tension measurements. The calcium concentration associated with half‐maximal tension was 2.5 μM for fast‐twitch and 1.3–1.4 μM for slow‐twitch fibers. Fast‐oxidative‐glycolytic (type 2A) and fast‐glycolytic (type 2B) fibers had similar calcium sensitivities. Maximum tensions (kg/ cm2) were 2.24 for fast‐twitch and 2.19 for slow‐twitch fibers.
Porcine malignant hyperthermia: Halothane effects on force generation in skeletal muscles
Authors: Gallant Esther M. , Goettl Virginia M. 
Published: January 2005

AbstractHalothane‐induced malignant hyperthermia (MH) is thought to result from a defect in the regulation of cytosolic calcium concentration in MH‐susceptible (MHS) skeletal muscle. Such a defect might be expected to alter the time course of contractile responses. To test this hypothesis, isolated intact cell bundles from external intercostal and common digital extensor muscles of normal and MHS pigs were stimulated electrically to elicit twitch and tetanic tension in the presence and absence of halothane (2.5%). Time intervals measured for both twitches and tetani were (1) the latent period between the stimulus and tension increase, (2) the time to peak tension, and (3) the half‐relaxation time. In contrast to previous reports, halothane had no effect on any measured time course parameter of twitches of either type of normal or MHS muscle, nor did the twitches of MHS and normal muscles differ in any parameter in the absence of halothane. However, the tetanic tension relaxation in both types of MHS muscle was markedly slowed by halothane, whereas in normal muscles there was little change. The slower rate of relaxation induced by halothane in MHS muscles suggests that halothane, either directly or indirectly, enhances the release or slows the removal of calcium in intact MHS muscles following maximal activation. This slowed tetanus relaxation could be of use in identification of MHS individuals.
Myasthenic U‐shaped decrement in multifocal cervical radiculopathy
Authors: Gilchrist James M. , Sanders Donald B. 
Published: January 2005

AbstractA middle‐aged man with lymphomatous meningitis developed acute cervical radiculopathy. Repetitive stimulation of an affected nerve revealed a “U‐Shaped” decrement. The decrement was absent 10 days later. We hypothesize that the decrement was secondary to simultaneous denervation of many motor units and disappeared as denervation became complete in those motor units.
Ankle dorsiflexor twitch properties in malignant hyperthermia
Authors: Quinlan John G. , Iaizzo Paul A. , Lambert Edward H. , Gronert Gerald A. 
Published: January 2005

AbstractA noninvasive method to diagnose malignant hyperthermia (MH) was sought. To this end, in vivo isometric twitch properties of the ankle dorsi‐flexor muscles were studied in three groups: (1) MH‐susceptible patients (n = 12), (2) relatives (n = 12) of MH‐susceptible patients who were judged to be MH resistant, and (3) a group of normal volunteers (n = 42) chosen from the community. Twitch properties were studied under resting state conditions and with 1 or 2 Hz stimulation to produce the negative staircase twitch response. There was a high degree of overlap between the ranges of the measured twitch parameters of all groups. Thus, the techniques presented in this study have no value in diagnosing susceptibility to MH. Several physiological features of human isometric twitch properties were demonstrated: (1) slowing of twitch speed with advancing age, (2) strong positive correlation between body weight and twitch torque, and (3) a negative staircase response typical of that described in other mammalian twitch studies.
Malignant hyperthermia: Effects of halothane on the surface membrane
Authors: Iaizzo Paul A. , Lehmamn‐Horn Frank , Taylor Stuart R. , Gallant Esther M. 
Published: January 2005

AbstractWe studied the electrical properties of intact muscle fibers from normal and malignant hyperthemia‐susceptible (MHS) pigs. Resting membrane potentials, action potentials, and current‐voltage relationships were measured with without the presence of halothane. There were no changes in the resting potentials or the specific membrane conductances at any concentration of halothane in either the normal or MHS fibers. The current‐voltage relationships of normal and MHS fibers did not differ. Contractures were observed in MHS muscle when the concentration of halothane was ≥0.8%. These halothane‐induced contractures were not associated with depolarization of the surface membrane. Contractures were not observed in normal muscle even at concentrations of 6.0% halothane. In contrast, halothane altered the shape of the action potentials of both MHS and normal fibers. However these changes were significantly greater in MHS fibers, occurred at much lower concentrations, and were partially prevented by preincubation in 10 μM dantrolene.
Myophosphorylase B deficiency and malignant hyperthermia
Authors: Isaacs Hyam , Badenhorst Margaret E. , Sautoy Cheryl Du 
Published: January 2005

AbstractA 6‐year‐old boy was examined with the dual purpose of establishing whether he had malignant hyperthermia (MH) and to investigate his complaint of excessive muscle fatiguability. In the course of such investigations, McArdle's disease was diagnosed, and the patient was also identified as an MH‐positive reactor.
Principal component analysis of the features of concentric needle EMG motor unit action potentials
Authors: Nandedkar Sanjeev D. , Sanders Donald B. 
Published: January 2005

AbstractMotor unit action potentials (MUAPs) were recorded from the biceps muscle of normal subjects and of patients with nerve of muscle diseases. Principal component analysis of the MUAP amplitude, area, area/amplitude ratio, duration, and the number of turns and phases produced three components that among them contained 90% of the variance of the data set. Thus the dimensionality of data was reduced from six to three. The first component reflected changes in the size of the MU, whereas the second reflected variations in the arrival time at the recording electrode of the action potentials of muscle fibers in the motor unit. The third factor reflected local loss of muscle fibers within the MU territory. Patterns of variations in the three components were different in patients with neuropathy and myopathy.
Studies of water permeability and proteins of erythrocyte membranes in patients with Duchenne muscular dystrophy
Authors: Benga Gheorghe , Popescu Octavian , Pop Victor I. , Ionescu Iulian , Muresan Ana , Borza Victoria , Hodâacrnâu Adriana , Popescu Mihai , Serbu Ana Maria , Benga Ileana 
Published: January 2005

AbstractThe characteristics of water permeability of erythrocytes from 54 Duchenne muscular dystrophy (DMD) patients and age‐matched controls have been determined by a pulse nuclear magnetic resonance (NMR) technique. A decreased permeability of erythrocyte membrane in DMD was definitely found at all temperatures between 15 and 42°C, with normal values for the activation energy of water diffusion. No differences between DMD and control subjects in the pattern of erythrocyte membrane polypeptides separated by two‐dimensional electrophoresis could be detected. The findings are discussed in relation to the molecular mechanisms of water diffusion across erythrocyte membrane and the problem of erythrocyte membrane abnormalities in DMD. A new interpretation of erythrocyte membrane alterations is proposed based on the recent findings regarding the molecular pathology of DMD.
Biochemical characteristics of free and junctional sarcoplasmic reticulum and of transverse tubules in human skeletal muscle
Authors: Damiani Ernesto , Barillari Alfredo , Tobaldin Gianantonio , Pierobon Sandra , Margreth Alfredo 
Published: January 2005

AbstractThe microsomal fraction of normal human skeletal muscle was subfractionated by isopycnic sucrose‐density centrifugation, using the procedure originally described by Saito et al.38 for rabbit fast muscle, and specific markers of the junctional face membrane of terminal cisternae (TC) (ryanodine receptor, high‐molecular‐weight feet proteins and membrane‐associated calcium‐binding protein calsequestrin), of the sarcoplasmic reticulum (SR) Ca‐pump membrane (chicken antibody to rabbit Ca‐ATPase), and of transverse tubules (TT) (dihydropiridine receptor, membrane cholesterol), respectively. The results show that isolated TC from human skeletal muscle share extensive morphological characteristics, protein composition, as well as Ca‐release properties with rabbit TC, as tested with an inhibitor (Ruthenium red) and an activator (doxorubicin) of SR Ca‐release. The Ca‐pump membrane of human muscle SR, in distinction to rabbit fast muscle SR, showed a relatively low specific activity of the Ca‐ATPase, as expected from the mixed fiber composition of human muscles, but shared the presence of minor protein components, such as a Con A binding protein of about 57 kDa and blue‐staining peptides in the 170–120 kDa range of molecular weights. Human muscle TT, as isolated from the same sucrose gradient, demonstrated a high affinity (3H)‐dihydropiridine binding activity in the range of previously reported values for purified TT from rabbit skeletal muscle.
Electrodiagnosis of human colchicine myoneuropathy
Authors: Kuncl Ralph W. , Cornblath David R. , Avila Orlando , Duncan Greg 
Published: January 2005

AbstractColchicine may produce a neuromuscular disorder even when given in customary doses. We report the electrodiagnostic features in eight pathologically proven cases of colchicine‐induced myoneuropathy. Myopathic motor unit potentials and early recruitment were found in proximal limb and truncal muscles, frequently with fibrillations, positive sharp waves, or complex repetitive discharges. These electromyographic findings correlated with the course of the weakness, which rapidly resolved within weeks of drug discontinuation, indicating that the major functional disturbance in the patients was myopathy. The accompanying signs of axonal neuropathy persisted longer, with little functional consequence. Although often misrecognized as polymyositis, colchicine myoneuropathy was identifiable by the rapid clinical and electrophysiologic improvement following drug withdrawal as well as by its distinctive morphology.
Mdx muscle grafts retain the mdx phenotype in normal hosts
Authors: Morgan Jennifer E. , Coulton Gary R. , Partridge Terence A. 
Published: January 2005

AbstractWhole muscle grafts were made between mdx and normal mice to investigate whether the mdx myopathic lesion is intrinsic to mdx muscle or is a property of its environment. Grafts were examined between 20 and 101 days. Unequivocal necrotic muscle fibers and/or newly formed basophilic myotubes were noted in 8 of 16 grafts of mdx muscle made in normal hosts but in none of 16 grafts of normal muscle made in mdx hosts. In older grafts, the proportion of centrally nucleated fibers and variability of fiber diameter were both higher in mdx muscle grafted into normal hosts than in normal muscle grafted into either mdx or normal hosts. Analysis of the glucose‐6‐phosphate isomerase (GPI) isoenzyme content of the grafts indicated that the muscle formed was predominantly of donor origin. These findings provide evidence that the mdx lesion is a primary myopathy rather than secondary to an extramuscular primary lesion.
Effect of diltiazem on 2,4‐D‐induced myotonia in rats
Authors: Al‐Rajeh Saad , Iyer Vasudeva , Olson William H. 
Published: January 2005

AbstractMyotonia is characterized by prolonged contraction (delay in onset of relaxation) of skeletal muscle fibers with characteristic electromyographic findings. Calcium channel blocking drugs may be expected to reduce myotonia, should they promote the onset of relaxation in a contracted skeletal muscle. This study was aimed at evaluating the effect of diltiazem, a calcium channel blocking agent, on myotonia induced by 2,4‐dichlorophenoxyacetic acid (2,4‐D).In rat diaphragm, exposed to 2.5 mM 2,4‐D in a tissue bath, myotonia was quantified by documenting the contraction time in response to direct stimulation with supramaximal electric stimuli. At the peak of myotonia, different concentrations of diltiazem were added to the tissue bath and the effect on evoked contraction studied over a period of 6 minutes. A concentration of 5 × 10−5M was found to be the most effective, causing a decrease in contraction time of more than 90% in 3 minutes in 100% of specimens (n = 7).The above findings raise the possibility of using diltiazem as an antimyotonic agent.
Changes in muscle fiber conduction velocity, mean power frequency, and mean EMG voltage during prolonged submaximal contractions
Authors: Arendt‐Nielsen Lars , Mills Kerry R. , Forster Allan 
Published: January 2005

AbstractAverage muscle fiber conduction velocity, mean power frequency, and mean EMG voltage have been measured in human vastus lateralis during prolonged isometric knee extensions at 10, 20, 30, and 40% of the maximum knee extension force. During contractions at 10 and 20% of maximum force, conduction velocity and mean power frequency rose as the contraction progressed, whereas the conduction velocity and mean power frequency fell at 30 and 40% of the maximum force. The mean EMG voltage rose during the contractions, with steeper increases for higher forces. It is argued that two principal factors influence the EMG during prolonged submaximal contractions: firstly, the fatigue of current active motor units, and, secondly, recruitment of fresh motor units. These factors act in opposition to muscle fiber conduction velocity. Recruitment gives an increase in average conduction velocity, whereas fatigue provokes a slowing in conduction velocity.
Electromyography in congenital nemaline myopathy
Authors: Wallgren‐Pettersson Carina , Sainio Kimmo , Salmi Tapani 
Published: January 2005

AbstractTo clarify the discrepancies between earlier reports of electromyography (EMG) in congenital nemaline myopathy (CNM), conventional electromyography was done on 13 patients with CNM, and results were compared with those of 18 earlier EMG examinations of the same patients. Fiber density was measured in 10 patients with a computerized method and neuro‐muscular jitter in 3 with single‐fiber EMG. With age, the EMG abnormality progressed, and “neuropathic” EMG features developed in distal muscles. In 9 of 10 patients fiber density was higher than normal. In two of three patients jitter was abnormal. Motor (13 of 13 patients) and sensory (3 of 3 patients) nerve conduction velocities were normal. Our results seem to explain the conflicting reports of EMG in CNM. We conclude that active degeneration and regeneration of muscle fibers takes place in CNM and suggest that the “neuropathic” motor unit potentials seen in our patients may be secondary to myopathic disease activity.
Cross‐reactivity of an antineurofilament antibody with a troponin‐T isoform
Authors: Takagi Michito , Takano‐Ohmuro Hiromi , Nakamura Toshitaka , Kawahara Hajime , Shimizu Teruo , Obinata Takashi , Kohama Kazuhiro 
Published: January 2005

AbstractHistochemical examination has revealed that a monoclonal antibody raised against the 200‐kilodalton (kd) subunit of neurofilament reacts not only with neural tissue but with type 1 and type 2C fibers of skeletal muscle. To identify the cross‐reactive substance(s), rat soleus muscle, which includes type 1 and type 2C fibers, was separated into a soluble fraction and an insoluble myofibrillar fraction. Western blot analysis demonstrated that the antibody reacted with 30‐kd and 36‐kd polypeptides in the soluble fraction and with a 38‐kd polypeptide in the insoluble fraction. We isolated a fraction that contained the 38‐kd polypeptide from the insoluble fraction. The material in this fraction bound to F‐actin. Two‐dimensional electrophoresis of the fraction showed that the 38‐kd polypeptide was part of the group of isoforms of troponin‐T, which was identified by a monoclonal antibody developed against troponin‐T. Thus, we conclude that this antineurofilament antibody recognizes one of the isoforms of troponin‐T in type 1 and type 2C fibers.