bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aging rat neuromuscular junnctions: A morphometric study of cholinesterase‐stained whole mounts and ultrastructure
Authors: Cardasis Constance A. , LaFontaine Donna M. 
Published: January 2005

AbstractPrevious morphological studies of the adult rat soleus neuromuscular junction (NMJ) indicate that its ultrastructure changes with age, a consequence of a dynamic, ongoing remodeling of pre‐ and postsynaptic elements. With aging, the balance between axonal sprouting and withdrawal appears to shift in favor of denervation. Here we have examined the extent and direction of the remodeling process during the adult life of the rat (5–111 weeks) by quantificatation and morphometry of NMJ structure as seen in electron microscopic composites and in cholinesterase (ChE) stained whole mounts.We have found that the net effect of axonal sprouting and withdrawal on the entire NMJ region varies with age: at 5–12 weeks there is rapid growth and maturation; at 12–48 weeks slower growth occurs, and at 48–82 weeks there is a gradual shift in direction to result in progressive loss of synaptic contact in individual NMJs; finally, at 82–111 weeks, there is loss of entire NMJs with some continued reinnervation at others. The diaphragm NMJ also exhibits continuous structural remodeling; however, between 82–111 weeks many changes in the ChE staining pattern appear abruptly.
Deficient function of the sarcoplasmic reticulum in patients susceptible to malignant hyperthermia
Authors: Condrescu Madalina , López José R. , Medina Pablo , Alamo Lorenzo 
Published: January 2005

AbstractCalcium uptake and (Ca2+ + Mg2+)‐ATPase were measured in sarcoplasmic reticulum (SR) vesicles prepared from muscles of eight patients susceptible to malignant hyperthermia (MH) and eight control subjects. Intracellular resting free calcium level of some of the studied subjects was also determined. Both calcium uptake capacity and (Ca2+ + Mg2+)‐ATPase activity were significantly lower in SR prepared from MH‐susceptible patients than from normal subjects. Besides, in these MH‐susceptible patients myoplasmic free Ca2+ was increased. These results corroborate previous suggestions that abnormal function of the SR membrane was related to the MH syndrome.
Contractile and EMG studies of murine myotonia (mto) and muscular dystrophy (dy/dy)
Authors: Entrikin Richard K. , Abresch Richard T. , Sharman Robert B. , Larson Douglas B. , Levine Neil A. 
Published: January 2005

AbstractThis report focuses on the myotonic (mto) mouse, an autosomal recessive neuromuscular mutant first described in 1982. Studies in vivo confirmed the presence of hindlimb rigidity during walking and typical myotonic electromyographic (EMG) discharges that persisted after nerve transection and complete neuromuscular blockade. Studies of the contractility of mto muscles in vitro revealed reduced peak isometric tetanic tension and greatly prolonged relaxation times. Tubocurarine did not affect tension parameters, but did antagonize the delayed relaxation in vitro. On the basis of EMG studies alone this mutant can accurately be described as myotonic. Reduction of the contractile abnormalities by tubocurarine in vitro, however, poses further questions regarding the nature of the disorder. Although the more familiar dystrophic mouse (dy/dy) has been termed “myotonic” by some, the new mto mutant differs from it in all aspects examined.
Single fiber electromyography in chronic progressive external ophthalmoplegia
Authors: Krendel David A. , Sanders Donald B. , Massey Janice M. 
Published: January 2005

AbstractWe have reviewed the electromyographic (EMG) studies of 17 patients with chronic progressive external ophthalmoplegia (CPEO). In 13 of 17 patients, conventional concentric needle EMG demonstrated a “myopathic” pattern, usually predominating in the shoulder muscles. Single‐fiber EMG showed increased jitter and/or blocking in at least one muscle in 13 of 16 patients. Jitter was increased in the frontalis muscle in 10 of 13 patients and in an arm muscle in 5 of 12. When both muscles were tested, jitter was greater in the frontalis muscle in 5 patients and in the arm muscle in 2. These observations demonstrate that it may be difficult to distinguish myasthenia gravis from CPEO by EMG. The frequency with which abnormal jitter is found in CPEO suggests that, in addition to a mild generalized myopathy, a primary defect in neuromuscular transmission may be present.
Bilateral anterior interosseous nerve syndromes associated with cytomegalovirus infection
Authors: Dunne John W. , Prentice David A. , Stewart‐Wynne Edward G. 
Published: January 2005

AbstractThe occurrence of bilateral brachial mononeuropathies presenting as anterior interosseous nerve syndromes in association with cytomegalovirus mononucleosis in an otherwise healthy adult is reported, a relationship not previously described.
Somatosensory evoked response evaluation of cervical spondylytic myelopathy
Authors: Perlik Stuart J. , Fisher Morris A. 
Published: January 2005

AbstractThere were 13 patients with cervical spondylytic myelopathy (CSM) evaluated. All had extradural defects with distortion of the cervical cord and partial or complete obstruction of myelographic dye. Posterior tibial scalp (SSEPs) were absent or delayed in all 13, whereas median SSEPs were abnormal in 9. Median SSEP abnormalities were limited to those with cord lesions at C5‐C6 or above. There were eight patients with associated radiculopathies confirmed by electromyography. No meaningful differences in SSEPs were noted between those with or without root injury. Surgery confirmed the level of cord injury in 10CSM is common with a high morbidity. The results indicate SSEPs using leg stimulation can be a sensitive indicator of cord injury in these patients and that the more commonly used arm stimulation is of value primarily for localizing the level of the myelopathy.
Electrophysiologic follow‐up in whipple's disease
Authors: Martínez A. Cruz , González P. , Garza E. , Bescansa E. , Anciones B. 
Published: January 2005

AbstractNeurologic and electrophysiologic findings in a 57‐year‐old man with Whipple's disease are reported. The patient had severe proximal weakness and weight loss of more than 20 kg. Conventional electromyography and nerve conduction studies suggested mild neuropathy in distal segments of lower limbs and myopathy in proximal muscles. Automatic analysis of the electromyogram in proximal muscles was consistent with myopathy. Conduction velocity of muscle fibers in situ showed low propagation velocity of the impulse. Weakness, weight loss, and all the electrophysiologic parameters improved after treatment, including a compression of the peroneal nerve at the knee, perhaps related to weight loss (slimmer's paralysis).
Detection of muscle injury in humans with 31‐P magnetic resonance spectroscopy
Authors: McCully Kevin K. , Argov Zohar , Boden Barry P. , Brown Richard L. , Bank William J. , Chance Britton 
Published: January 2005

AbstractStrenuous exercise can result in muscle injury that may persist for 2 weeks. Our purpose was to determine if muscle injury can be detected with 31‐P magnetic resonance spectroscopy. Normal subjects performed repeated lengthening contractions with either arms or legs designed to result in mild muscle injury. One hour after the arm exercise, there was a significant increase in the inorganic phosphate to phosphocreatine ratio (Pi/PCr), with the maximum increase in Pi/PCr occurring 1 day postexercise (0.12 ± 0.01 to 0.21 ± 0.05). Pi/PCr remained elevated for 3–10 days. Similar results were seen following the leg exercise protocol. ATP/(Pi+PCr) decreased in all the arm exercised subjects. Exercise protocols that did not contain lengthening contractions did not result in changes of Pi/PCr or ATP/(Pi+PCr). Patients with various neuromuscular diseases with evidence of muscle damage (elevated CK, muscle soreness, and histopathological findings) also showed increased Pi/PCr at rest. We conclude that elevated Pi/PCr at rest can reflect nonspecific muscle damage in normal and diseased subjects.
F/M ratios in polyneuropathy and spastic hyperreflexia
Authors: Fisher Morris A. 
Published: January 2005

AbstractThe ratios of F to M amplitudes were determined by dividing the mean amplitude of 15 F‐waves (mF AMP) by the maximum evoked motor response amplitude recording from the abductor pollicis brevis and calf muscles. Data were compared from age‐matched control subjects and patients with polyneuropathies or spastic hyperreflexia. In comparison to normals, mF AMP/M—but not mF AMP—values were increased at statistically significant levels in all patient groups. M amplitudes were decreased (versus normal, P < 0.005) in the patients with either peripheral or central lesions. In these patients, the normal significant correlation between mF AMP and M amplitudes may be disrupted, whereas the data suggest that increased mF AMP ratios in neuropathies are related to their duration. These results indicate that mF AMP/M ratios can be increased not only with increased central excitability but also in peripheral neuropathies. Although mechanisms may differ, the data are consistent with a similar physiological response to peripheral and central injury and emphasize that M amplitudes may be decreased with central lesions.
Sympathetic skin response in diabetic peripheral neuropathy
Authors: Niakan Enayat , Harati Yadollah 
Published: January 2005

AbstractThere were 72 diabetic patients with clinical evidence of sensorimotor peripheral neuropathy investigated to determine the sensitivity of the sympathetic skin response test (SSR) for detection of sudomotor dysfunction and its correlation with other autonomic function tests, autonomic symptoms, and degree of peripheral neuropathy. Nerve conduction velocities (NCV) were abnormal in all patients, SSR was absent in 60 of 72 patients (83%), Valsalva test was abnormal in 32 of 67 patients (48%) who had the test, and 6 of 72 (9%) had orthostatic hypotension. Statistically significant correlation was found between the Valsalva test abnormality, the degree of peripheral neuropathy, and the SSR in our patients. All patients with orthostatic hypotension had an absent SSR and an abnormal Valsalva test. Most patients had one or more autonomic signs or symptoms. Orthostatic dizziness only correlated with SSR, however. These results suggest that subdomotor activity detected by sympathetic skin response is a valuable test for investigation of dysautonomia in diabetic peripheral neuropathy.
Single fiber EMG in juvenile idiopathic scoliosis
Authors: Trontelj Jož V. , Fernandez José M. 
Published: January 2005

AbstractA single fiber EMG (SFEMG) study was performed in 51 patients with idiopathic juvenile scoliosis of moderate degree (mean 23.8° of Cobb), aged 7–18 years (mean 13.2 years). The findings in the extensor digitorum communis muscle (EDC) include a moderate but significant increase in fiber density (mean 2.02, ± 0.21, P < 0.001), a mild but significant (P < 0.001) neuromuscular transmission abnormality (7.6% of fibers showed increased jitter and 4.5% intermittent blocking), and a moderately prolonged mean interspike interval (mean 0.98 msec, ±0.20, P < 0.005) in EDC. Five of the patients had normal fiber density, 9 had a normal jitter study, and further 7 had a normal mean interspike interval. However only one had all the parameters normal. The paraspinal and intercostal muscles at the apex of the scoliotic curvature examined in some of the patients showed similar abnormalities. The study thus suggests the existence of a subclinical systemic neuromuscular disorder in nearly all of our patients with idiopathic scoliosis, which might have a pathogenetic significance.
A model of the differing change in motor and sensory action potentials over distance
Authors: Kincaid John C. , Minnick Katherine A. , Pappas Steven 
Published: January 2005

AbstractClinically recorded motor and sensory nerve responses show different degrees of change in response size over distance along a nerve. We describe a computer model to investigate possible causes of this phenomenon. Effects of the range of conduction velocity in a nerve and the size of the constituent action potentials forming the recorded response are evaluated. We conclude that the broader duration of the motor unit potential is the predominant factor in accounting for motor nerve responses showing less change over distance than sensory responses. The contributions of temporal dispersion and phase cancellation are also discussed.
α‐Glucosidase isoenzymes in normal and acid maltase‐deficient human skeletal muscles
Authors: Usuki Fusako , Ishiura Shoichi , Nonaka Ikuya , Sugita Hideo 
Published: January 2005

AbstractOne acid α‐glucosidase and two neutral α‐glucosidases were separated from human skeletal muscle by DEAE‐cellulose column chromatography. The appearance of the two human neutral α‐glucosidase isoenzymes was found to be age dependent. We called them “fetal” and “adult” neutral α‐glucosidases. The biochemical properties of the fetal and adult types of neutral α‐glucosidase appeared to be similar to those previously reported for neutral α‐glucosidases AB and C, respectively. The neutral α‐glucosidase activity in the column eluate of the infantile acid maltase deficiency (AMD; 5‐month‐old) muscle was completely of the adult type, whereas 18% of the total neutral α‐glucosidase activity in age‐matched control muscle was of the fetal type. In contrast, the eluate of the late‐onset AMD (32‐year‐old) muscle contained both the adult and fetal neutral α‐glucosidases, 68 and 32%, respectively.
Motor unit estimates in the biceps‐brachialis in amyotrophic lateral sclerosis
Authors: Strong Michael J. , Brown William F. , Hudson Arthur J. , Snow Robert 
Published: January 2005

AbstractA newly developed technique for estimating the number of motor units in the biceps‐brachialis muscles and for studying the innervation patterns of motor units in the same muscles has been applied to the study of 17 patients with amyotrophic lateral sclerosis (ALS). Although severe motor unit losses were seen in many ALS cases, in most there were clear indications of increases in innervation densities, linked potentials, and blocking. This technique provides a powerful new tool for quantitatively assessing the extent of motor unit losses and the accompanying changes in innervation patterns in ALS.
Halothane‐caffeine contracture testing in neuromuscular diseases
Authors: Heiman‐Patterson Terry D. , Rosenberg Henry , Fletcher Jeffrey E. , Tahmaoush Albert J. 
Published: January 2005

AbstractThe association of malignant hyperthermia (MH) with neuromuscular disorders has been recognized since 1970. These disorders include central core disease, Duchenne muscular dystrophy, myotonia congenita, myotonic dystrophy, nonspecific myopathies, and King–Denborough syndrome. In order to assess the anesthetic risk of MH in the neuromuscular population, we performed halothane and caffeine contracture testing for MH susceptibility on biopsied muscle removed from 25 consecutive neuromuscular patients during diagnostic evaluation. Positive contracture tests were found in 7 to 18 patients with myopathic disorders and 3 to 7 patients with neurogenic disorders. Two of our patients had anesthetic events suggesting MH. These findings suggest that myopathic and neuropathic disorders share pathogenic mechanisms with MH, resulting in positive contracture tests and possibly leading to clinical events during anesthesia. Although there is controversy regarding the interpretation of a positive contracture test, contracture testing remains the most widely accepted test for MH susceptibility. Thus, a variety of neuromuscular disorders may be associated with MH susceptibility, and caution should be exercised during anesthesia in this group of patients.
Slow sodium channel inactivation in mammalian muscle: A possible role in regulating excitability
Authors: Ruff R. L. , Simoncini L. , Stüuhmer W. 
Published: January 2005

AbstractSodium currents were recorded in rat fast and slow twitch muscle fibers. Changes in the membrane potential around the resting potential produced slow changes in the sodium current amplitude due to alterations of the slow inactivation process that was increased by steady depolarization and removed by prolonged hyperpolarization. In contrast, classical fast inactivation was not operative around the resting potential, and depolarizations of greater than 20 mV were required to close half of the channels by fast inactivation. Because slow inactivation is operative around the resting potential of mammalian muscle fibers, it may partially explain why small depolarizations, such as those that occur in some patients with periodic paralysis, can reduce excitability.
Stimulus artifact compensation using biphasic stimulation
Authors: Nilsson Jan , Ravits John , Hallett Mark 
Published: January 2005

AbstractThe feasibility of using biphasic stimulation as a method of reducing stimulus artifact was explored in several different circumstances. Sensory and muscle evoked potentials were compared using monophasic and biphasic constant‐current stimuli. The monophasic stimulus was a negative rectangular pulse with a duration of 0.1–0.2 msec. The biphasic stimulus was a negative rectangular pulse of 0.1–0.2 msec duration followed, after a variable delay, by a positive rectangular pulse of the same duration and variable amplitude. When the conducting distances were long, stimulus artifact did not disturb either monophasically or biphasically evoked potentials. When the conducting distances were short, stimulus artifact occurred with monophasic stimulation but could be diminished readily using biphasic stimulation. The method can be accomplished easily using standard instruments with dual stimulators.
Noncoordinate expression of M band proteins in slow and fast embryonic chick muscles
Authors: Grove Barbara Kay , Thornell Lars‐Eric 
Published: January 2005

AbstractThe expression of the myosin‐associated M band proteins myomesin and M protein in differentiating muscle fibers in the anterior latissimus dorsi (ALD) and posterior latissimus dorsi (PLD) muscles during embryonic chicken development was examined by immunocytochemistry using monoclonal antibodies. Early in the embryonic development of both muscles, both myomesin and M protein are expressed in primary and secondary myotubes. However, beginning at 10 days in ovo, M protein is gradually suppressed first in primary, then in secondary, presumptive slow‐tonic type 3 fibers. M protein is transiently suppressed in presumptive fast‐twitch type 2 fibers derived from primary myotubes but continuously expressed in those derived from secondary myotubes. Thus, initially all myotubes have a common intrinsic M band composition with respect to myomesin and M protein, whereas at later stages the expression of M protein is fiber‐type specific. Intrafusal spindle fibers, which are segregated from extrafusal fibers around 14 days in ovo, have a heterogeneous M band composition atypical of extrafusal fibers.
Molecular genetics in muscular dystrophy research: Revolutionary progress
Authors: Stedman Hansell , Sarkar Satyapriya 
Published: January 2005

AbstractThe contribution of “reverse genetic” strategies to neuromuscular disease research is evident in the progression of breakthroughs that have recently culminated in the cloning of the Duchenne muscular dystrophy (DMD) cDNA. The resultant improvements in our understanding of the genetic basis of Becker muscular dystrophy (BMD) and DMD serve as models for similar investigation of other heritable disorders. These genetic advances have outpaced concurrent work on the molecular pathogenesis of the dystrophic process, with the curious result that inferences about the DMD protein's amino acid sequence have preceded any information about its function or intracellular localization. In recognition that this foundation sets the stage for the rapid elucidation of the disease's pathogenesis, we review the experimental basis of such advances, with reference to relevant progress in basic myology, pathology, and molecular biology. We conclude with a view towards the ultimate clinical implications of these experimental break‐throughs.
Effects of glucocorticoids on motor units in cat hindlimb muscles
Authors: Robinson Andrew J. , Clamann H. Peter 
Published: January 2005

AbstractThe purpose of this study was to examine the effects of glucocorticoid treatment on the contractile, electrical and fatigue properties of isolated motor units of identified type. Although it is known that glucocorticoid administration induces atrophy and weakness most strongly in fast, pale muscles and to a lesser extent in red muscle, the relationship between steroid effects and motor unit type is not known. Properties of medial gastrocnemious (MG) and soleus (SOL) motor units were studied in normal cats and in cats treated with triamcinolone acetonide (3–4 mg/kg body weight for 10–16 days). Glucocorticoid treatment produced weakness preferentially in fast‐twitch motor units. This suggests that catabolic steroids cause a reduction in the amount of contractile protein and hence contractile strength of motor units in inverse proportion to their relative activity or degree of use.
Reversible proximal conduction block underlies rapid recovery in Guillain‐Barré syndrome
Authors: Berger Alan R. , Logigian Eric L. , Shahani Bhagwan T. 
Published: January 2005

AbstractThree patients with Guillain‐Barré syndrome underwent electrophysiological examination prior to and during a period of rapid clinical recovery. In each case, improved strength of the abductor digiti minimi coincided with electrophysiologic evidence of a marked reversal of proximal conduction block. In contrast, the degree of distal conduction block remained relatively unchanged after stimulation at the wrist, elbow, axilla, and Erb's point. These findings indicate that rapid motor recovery, early in the course of Guillain‐Barré syndrome, can result from reversal of proximal conduction block and explains the often noted dissociation between clinical improvement and conventional distal nerve conduction studies.
Fatigue‐related changes in neuromuscular excitability of rat hindlimb muscles
Authors: Enoka Roger M. , Rankin Lucinda L. , Joyner Michael J. , Stuart Douglas G. 
Published: January 2005

AbstractBrief repetitive trains of supramaximal nerve stimulation produce intermittent muscle activation and, in time, a progressive decline in force (i.e., neuromuscular fatigue) and depression of the electromyogram (EMG). These changes may include within‐train reductions in EMG due to a failure of neuromuscular propagation.13The aim of the present study was to investigate changes in EMG during a 360‐second stimulus regimen designed to fatigue soleus and extensor digitorum longus muscles of anesthetized rats by activating the muscle with repetitive trains of 40 Hz stimuli. Measurements included peak force for each tetanus, variation of the within‐train EMG (coefficient of variation for area), and magnitude of the first EMG waveform (area) of each train. Fatigue was characterized as the relative decline in force over the course of the test. The responses of the test muscles were categorized, based on an absolute scale of fatigability, into five groups: potentiated, nonfatigable, low fatigability, intermediate fatigability, and high fatigability. Fatigable muscles (low, intermediate, and high fatigability groups) demonstrated a decreased EMG magnitude and an increased EMG‐area variation with repetitive activation. This increased variation, however, was nonmonotonically related to fatigability such that the leastandmost fatigable muscles had the smallest within‐train EMG variation. We suggest that these data can be explained by considering the EMG (compound muscle action potential) as a stochastic process that represents a composite of single‐fiber events (axonal to sarcolemmal transmission) with variable probabillities.