bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathophysiology of fasciculations in ALS as studied by electromyography of single motor units
Authors: Conradi Sebastian , Grimby Lennart , Lundemo Gunnar
Published: January 2005

Electromyographic potentials of fasciculations were studied in ten patients with amyotrophic lateral sclerosis (ALS). The EMG recordings were made from the extensor digitorum brevis muscle. The EMG recording was so selective that only one motor unit potential appeared on maximal voluntary effort and on supramaximal electrical stimulation of the peroneal nerve. In a series of fasciculations, the shapes of the EMG potentials varied, while in a series of voluntary twitch activations of electrical nerve stimulations the EMG potentials were mainly constant. Fasciculations were followed by antidromic impulses in the test unit axon as judged from collision tests, and they persisted after lidocaine blockades of the nerve to the muscle. The findings are compatible with a conclusion of distal multifocal triggering of fasciculation. Fasciculating motor units had voluntary firing properties close to those of normal low‐threshold motor units. Widespread fasciculations were abolished by a nonparalytic dose of a synthetic curare derivative (Pavulon) and augmented by administration of neostigmine in two cases. The fasciculations in ALS thus have the same characteristics as experimental fasciculations evoked by cholinesterase inhibitors, and there is reason to believe that the underlying pathophysiological mechanism is similar in the two cases.
Necrosis of capillaries in denervation atrophy of human skeletal muscle
Authors: Carpenter Stirling , Karpati George
Published: January 2005

Gastrocnemius muscles from eight adults with moderate to severe denervation of various causes (excluding vascular diseases), along with biopsy specimens from seven controls, were studied in semithin epoxy resin sections and by electron microscopy. Morphometry showed diminution in the number of capillaries per muscle fiber roughly proportional to the degree of muscle fiber atrophy. The number of capillaries per transverse muscle fiber area tended to increase. By phase microscopy, destroyed capillaries were found in all denervated muscle specimens. Denervated muscle becomes relatively overvascularized, and probably as a result, some capillaries become necrotic. This tends to restore the normal equilibrium between muscle mass and blood supply. The capillary changes of denervation can be distinguished from those in dermatomyositis.
Microgravimetric analysis of nerve edema
Authors: Costello M. L. , Powell H. C. , Myers R. R.
Published: January 2005

A technique for microgravimetric analysis of nerve edema was used to demonstrate increased water content in hexachlorophene neuropathy. The method was modified from one used previously to quantify brain edema by using density gradient columns prepared with two nonaqueous fluids of high and low specific gravity. This method revealed a wide separation between hexachlorophene‐treated and control nerves, Gradient position was then related to specific gravity, which averaged 1.03426 in hexachlorophene‐treated nerves versus 1.04921 for control nerves. This, in turn, was correlated with the percentage of water in the tissue. Water content of hexachlorophene‐intoxicated nerves was approximately 10% greater than control nerves. A major advantage of this technique is its sensitivity in detecting edema in small tissue samples.
Evidence against a generalized membrane defect in dystrophic mice platelets
Authors: Mizobe Fumio , Livett Bruce G.
Published: January 2005

The response of the membrane‐bound enzyme AChE to changes in temperatures was investigated to test the applicability of the “generalized membrane defect” hypothesis proposed for human myotonic and Duchenne muscular dystrophies to the two forms of muscular dystrophy expressed in mice. For intact platelets from homozygous normal and dystrophic mice of both strains, a break (Tc) occurred in the Arrhenius plot of AChE activity at approximately 22 C. Solubilization of membrane‐bound AChE by Triton X‐100 produced a nonlinear Arrhenius plot over the temperature range (7.7 C to 37 C) in normal and dystrophic mice of both strains. However, in the presence of phospholipase A2 + C and Triton X‐100, a linear Arrhenius plot was produced indicating that the membrane‐bound enzyme is normally modulated by a bulk lipid domain as well as by a tightly bound (immobilized) phospholipid domain. The temperature response of platelet AChE from normal and dystrophic mice of both strains was not significantly different. These results showing normal temperature kinetics of AChE do not lend support to the theory of a membrane defect in the platelets of dystrophic mice.
Morphometric analyses of human muscle fiber types
Authors: Sjöström Michael , Ängquist Karl‐Axel , Bylund Ann‐Christin , Fridén Jan , Gustavsson Lennart , Scherstén Tore
Published: January 2005

Fibers from the m. vastus lateralis of 10 middle‐aged men were classified at ultrastrctural level according to the appearance of the sarcomeric M‐band. The Z‐band widths had a two‐peak distribution. One peak was due to type 1 fibers (mean 125 ± 11 nm), the other to type 2 fibers. This latter could be separated into type 2A (101 ± 9 nm) and type 2B (86 ± 8 nm). About 83% of the fibers would have been correctly classified on the basis of the Z‐band width alone. Mitochondrial volumes differed (type 15.6 ± 0.8, 2A 4.0 ± 0.8, and 2B 2.8 ± 0.8%). However, only one third (37%) of the fibers would have been correctly classified if sorted according to this parameter. Mitochondrial volumes in the different fibers were correlated to mitochondrial enzymes, while fiber sizes and numbers were correlated to cytoplasmic variables. The correlations appeared mainly after a training program, suggesting that the relationships between structural and functional parameters are more obvious after adaptation to higher functional demands.
Training‐induced increase in myofibrillar ATPase intermediate fibers in human skeletal muscle
Authors: Schantz Peter , Billeter Rudolf , Henriksson Jan , Jansson Eva
Published: January 2005

The response of human muscles triceps brachii and vastus lateralis to training, consisting of 18.5 miles a day of skiing with a backpack, 6 days a week for 8 weeks, has been investigated by means of histochemical fiber typing (myofibrillar ATPase) as well as immunohistochemical discrimination of slow and fast myosin (n = 6). A detraining period of 33 weeks was also studied. The percentage of type 2 fibers decreased by 6% in the triceps brachii during training, whereas the intermediate fiber type increased by 4%. No change was found in the distribution of fiber types in the vastus lateralis during training or in both muscles during detraining. The ATPase intermediate fibers also stained intermediately in the immunohistochemical stainings for slow and fast myosin. These results show that transformation of a fraction of the type 2 fibers into the intermediate type may occur as a response to endurace training.
Muscle granulomas following intramuscular injection
Authors: Mrak Robert E.
Published: January 2005

An 8‐month‐old child underwent a muscle biopsy because of hypotonia. The biopsy showed centronuclear myopathy and, in addition, an unusual granulomatous inflammatory infiltrate. The child died of respiratory complications and a complete autopsy failed to reveal further evidence of granulomatous disease. The lesion was reproduced in experimental animals by intramuscular injection of diphtheria and tetanus toxoids and pertussis vaccine. Granular material present in histiocytes in these lesions was shown histochemically to be an aluminum salt.
Branched skeletal muscle fibers not associated with dysfunction
Authors: Brown Lucy M. , Lopez Jose R. , Olsen Jean A. , Rüdel Reinhardt , Simmons Robert M. , Taylor Stuart R. , Wanek Laurel A.
Published: January 2005

We report the occurrence of large clefts and branches in some amphibian vertebrate skeletal muscle fibers. Such fibers can be isolated intact from various skeletal muscles of fully mature animals and apparently are normal in other respects. Electron micrographs showed no signs of degeneration in most fibers. Electrical and mechanical studies revealed that all branches were excitable and able to contract. Branches evidently can arise in the absence of abnormal influences such as experimentally induced overload. The apparent cause may be either fusion or splitting of fibers.
Myofiber differentiation in normal and hypotrophied canine pectineal muscles
Authors: Cardinet George H. , Leong Charlotte L. , Means Penelope S.
Published: January 2005

The myofiber type composition of pectineal muscles was determined in 21 mixed‐breed pups at 1 through 79 days of age and in 22 8‐week‐old‐pups (4 mixed‐breed, 5 greyhound and 5 German shepherd pups with normal muscles, and 8 German shepherd pups with myofiber hypotrophy). Sections were stained for the histochemical demonstration of myofibrillar adenosine triphosphatase by incubation in media at pH 9.8 without preincubation and following preincubation in acid media at pH 4.5 and at pH 4.3. At day 1 most myofibers were type 2C (alkaline and acid stable) while the remainder were type 1A myofibers (alkaline labile; acid stable) which had differentiated prenatally. Subsequently, the number of type 2C myofibers decreased while the number of type 1A and type 2A myofibers (alkaline stable; acid labile at pH 4.5 and pH 4.3) increased. Type 1B myofibers (partially alkaline stable; acid stable) were first observed at day 12 and were variably present through day 79. Type 1B myofibers appeared to be a transition form of type 2C to type 1A differentiation. Type 2B myofibers (alkaline stable; acid stable at pH 4.5; acid labile at pH 4.3) were not observed. Hypotrophied muscles contained more type 2C and fewer type 2A myofibers and all myofiber types were smaller than normal. These results suggest that the pathogenesis of this disorder involves both myofiber growth and differentiation, particularly differentiation of type 2A myofibers.
Muscle function in rheumatic disease patients treated with corticosteroids
Authors: Rothstein Jules M. , Delitto Anthony , Sinacore David R. , Rose Stephen J.
Published: January 2005

Clinical and experimental data indicate that long‐term corticosteroid use leads to atrophy of the type 2 muscle fibers. The purpose of this study was to characterize and quantify the nature of muscle function in rheumatic disease patients who have been on long‐term corticosteroid therapy. Quadriceps function (i.e., peak torque and power) in 19 patients (11 with rheumatoid arthritis, five with systemic lupus erythematosis, and 3 other) and 11 age‐ and activity‐matched normal controls was measured with an isokinetic dynamometer (Cybex II), during four constant velocity movements. Power was significantly lower for the patients at all speeds. At the higher speeds the patients' deficit in power production increased as indicated by a difference in the slopes of power‐velocity regression lines. Measures of peak torque could not be consistently used to differentiate the groups. Patients with rheumatic diseases receiving corticosteroids have a decreased ability to generate muscle power. The method described allows for quantification of these deficits in a clinical setting.
Morphometric analysis of aging skeletal muscle following endurance training
Authors: Silbermann Michael , Finkelbrand Sara , Weiss Anna , Gershon David , Reznick Abraham
Published: January 2005

Aging of skeletal muscle in the hindleg of the mouse is accompanied by a progressive increase in the amount of the interstitial tissue and especially that of lipid cells and fibroblasts. Quantitative analysis indicates that there was a nonsignificant increase in the total number of muscle fibers per unit area, perhaps due to a splitting process. The proportion of high oxidative fibers was decreased to a nonsignificant degree, and the remaining high oxidative fibers underwent a significant compensatory hypertrophy. Concomitantly, the number of low oxidative fibers increased significantly. This study revealed that endurance training in young animals induced morphometric changes very similar to those noticed in intact aging animals (i.e., splitting phenomenon, hypertrophy of high oxidative fibers, and an increased proportion of low oxidative fibers). It also became apparent that the skeletal muscle of old animals lacks the capacity to respond to enforced training, except for a further increase in the proportion of low oxidative fibers. It appears that aging muscle is unable to adapt to changing environmental circumstances.
Respiratory improvement by muscle training in adult‐onset acid maltase deficiency
Authors: Martin Richard J. , Sufit Robert L. , Ringel Steven P. , Hudgel David W. , Hill Patricia L.
Published: January 2005

A patient with progressive involvement of respiratory function from adult‐onset acid maltase deficiency is reported. The decrement in objective and subjective waking and sleeping respiratory variables was significantly reversed by inspiratory muscle training. This training was accomplished simply by breathing against inspiratory resistors for 15 minutes twice a day. Inspiratory muscle training may prove valuable in other patients with progressive neuromuscular disorders that involve respiratory muscle function.
Intracellular elemental content of cardiac and skeletal muscle of normal and dystrophic hamsters
Authors: Smith Nancy K. R. , Morris Sidra S. , Richter Michael R. , Cameron Ivan L.
Published: January 2005

To test the hypothesis that the genetic lesion causing muscular dystrophy might be reflected in an abnormal intracellular elemental content, the elemental content of individual cardiac and skeletal muscle fibers in 50‐day‐old male control and cardiomyopathic BIO 53.58 hamsters was determined. The technique of electron probe x‐ray microanalysis of freeze‐dried tissue was employed. No electrolyte content differences were found between control and diseased animals for nuclei, myofibrillar cytoplasm, or mitochondrially‐enriched cytoplasm of cardiac myocytes. Sulfur was elevated in dystrophic cardiac myocytes and was the only element significantly different in heart tissue of control and cardiomyopathic animals. Sulfur was also elevated in dystrophic soleus muscle fibers. The pattern of electrolyte content of these cells reflected a mixture of normal cells and damaged cells with altered electrolyte content. In this hamster model, alteration of electrolyte content of myocytes appears to be a result of the disease process and not an inherent characteristic of muscular dystrohy. The elevated sulfur in dystrophic hamster myocytes reflects a biochemical lesion which deserves further study.
Hypertrophic form of peroneal muscular atrophy (PMA): Unusual nerve conduction results
Authors: Streib Erich W. , Sun Sallie F. , Kimberling William , Smith Stephen A.
Published: January 2005

A family with a hypertrophic form of peroneal muscular atrophy (PMA) was studied with typical clinical and electrophysiological abnormalities in the propositus and her child. The propositus' fater was asymptomatic and slowing of nerve conduction velocities was limited to the peroneal nerves. Actual parentage was confirmed by 22 different serologic and electrophoretic marker systems.
Membrane protein phosphorylation in the intact erythrocytes of genetically dystrophic hamsters
Authors: Johnson Robert M.
Published: January 2005

Membrane protein phosphorylation has been measured in both normal and dystrophic (BIO 53.58) hamsters. After radiolabeling intact erythrocytes with exogenous 32Pi, band 3 polypeptides from dystrophic hamsters had increased incorporation of 32P, compared to age‐matched controls. This was verified by membrane protein fractionation. The use of intact cell phosphorylation avoids many of the sources of experimental variability noted in experiments with isolated membranes. This work, using an animal model for the disease, supports the hypothesis of a generalized membrane defect in the muscular dystrophies.
Heterogeneity of type 1 skeletal muscle fibers revealed by monoclonal antibody to slow myosin
Authors: Shafiq Saiyid A. , Shimizu Teruo , Fischman Donald A.
Published: January 2005

Monoclonal antibodies (McAbs) were generated against slow myosin from the chicken anterior latissimus dorsi (ALD) muscle and their reactivity was checked against fast (pectoralis), slow (ALD), cardiac (ventricular), and smooth (gizzard) myosins by radioimmunoassay (RIA), immunoautoradiography (immunoblots), and indirect immunofluorescence techniques. In RIAs, the McAb (ALD‐58) described in this article reacted specifically with slow myosin, with only a weak cross‐reactivity to cardiac myosin. In immunoblots against whole muscle homogenates and purified myosins, it bound selectively to the 200 Kd myosin heavy chain band. The ALD‐58 antibody stained the fibers of the ALD muscle uniformly but gave three grades of reactions (strong, weak, and negative), with histochemically identified type 1 fibers of sartorius and gastrocnemius muscles demonstrating the immunological heterogeneity of myosins in type 1 skeletal muscle fibers.
31P‐NMR studies of normal and dystrophic chicken muscle
Authors: Pettegrew Jay , Minshew Nancy , Feit Howard
Published: January 2005

Phosphorus‐31 nuclear magnetic resonance (31P‐NMR) analysis was performed on normal (line 412) and dystrophic (line 413) superficial pectoralis muscles excised from chickens between 15 and 116 days after hatching. An apparent alteration in dystrophic muscle energy metabolism was abolished by pretreatment with curare and was attributed to muscle hyperexcitability. Time‐dependent 31P‐NMR studies demonstrated no apparent difference in the overall tissue adenosine triphosphatase (ATPase) activity of dystrophic as compared to normal muscle. After 55 days of age, a resonance signal attributed to serine ethanolamine phosphodiester (SEPDE) was observed only in dystrophic muscle. Adding the paramagnetic cation Mn2+ to the buffer surrounding the muscle resulted in an approximate 80% decrement in the dystrophic SEPDE signal without apparent alteration of the other phosphatic signals in either the normal or dystrophic muscle. This would argue against any generalized membrane defect in dystrophic chicken muscle and suggest that SEPDE is in a compartment accessible to Mn2+.
Failure of neuromuscular transmission and contractility during muscle fatigue
Authors: Pagala Murali K. D. , Namba Tatsuji , Grob David
Published: January 2005

In previous studies of muscle fatigue, tension was monitored from whole muscle, while action potentials were recorded from a few muscle fibers. To compare more accurately changes in these responses, an in vitro fluid electrode technique was employed to record the action potential of whole muscle simultaneously with tension during fatigue induced by nerve stimulation in the rat extensor digitorum longus (EDL), soleus, and diaphragm muscles. In each muscle, tension declined from the start of stimulation, while action potential amplitude initially increased slightly and then declined most rapidly in EDL, more slowly in diaphragm, and most slowly in soleus. Direct stimulation of the fatigued muscle produced the greatest increase in tension in EDL, next in diaphragm, and least in soleus. These results indicate that while failure of excitation‐contraction coupling or of the contractile mechanism is the initial cause of fatigue in all the muscles studied, and remains the predominant cause throughout in the soleus muscle, failure of neuromuscular transmission plays an important role in fatigue after the first 15 seconds in EDL, and to a lesser extent, after the first 90 seconds in diaphragm.
Changes in muscle contractile properties and neural control during human muscular fatigue
Authors: Bigland‐Ritchie B. , Woods J. J.
Published: January 2005

The factors limiting force production and exercise endurance time have been briefly described, together with some of the changes occurring at various sites within the muscle and central nervous system. Evidence is presented that, in fatigue of sustained maximal voluntary contractions (MVC) executed by well‐motivated subjects, the reduction in force generating capacity need not be due to a decline in central nervous system (CNS) motor drive or to failing neuromuscular transmission, but can be attributed solely to contractile failure of the muscles involved. However, despite this conclusion, both the integrated electromyogram (EMG) and the mean firing rate of individual motor units do decline progressively during sustained MVC. This, however, does not necessarily result in loss of force since the parallel slowing of muscle contractile speed reduces tetanic fusion frequency. It is suggested that the range of motoneuron firing rates elicited by voluntary effort is regulated and limited for each muscle to the minimum required for maximum force generation, thus preventing neuromuscular transmission failure and optimizing motor control. Such a CNS regulating mechanism would probably require some reflex feedback from the muscle.
Immunohistochemical study of myoglobin in neuromuscular diseases
Authors: Kagawa Noriko , Hizawa Kazuo
Published: January 2005

The localization of myoglobin (Mb) in skeletal muscle in various neuromuscular diseases was studied by an immunoperoxidase technique. The immunoreactivity of Mb was shown to be well preserved in muscle fibers that showed denervation atrophy or vacuolar degeneration, as well as in muscle fibers with apparently normal structure. Marked decrease or loss of Mb immunoreactivity was observed in muscle fibers with hyaline degeneration or floccular necrosis, where there was irreversible disruption of the muscle fibers. On the other hand, regenerated fibers showed variable immunostaining for Mb. Most regenerated fibers showed little or no immunostaining but some showed staining as strong as apparently normal fibers. These findings in various neuromuscular diseases suggested that the elevation of serum Mb in patients with these diseases was ascribed to its release from severely injured, necrotic muscle fibers. The immunohistochemistry for Mb was shown to be useful to evaluate plasma membrane injury and characterize muscle degeneration.
Pseudo‐anterior interosseous nerve syndrome
Authors: Wertsch Jacqueline J. , Sanger James R. , Matloub Hani S.
Published: January 2005

The anterior interosseous nerve syndrome (AINS) is well known. A case is presented that had electromyographic findings limited to the distri‐bution of the anterior interosseous nerve. A small area of sensory loss and slight asymmetry of amplitudes noted on median nerve conduction studies were inconsistent with an AIN syndrome. An antecubital level partial median nerve compromise primarily involving the bundles that form the anterior interosseous nerve was surgically noted. This case illustrates that localization of a peripheral nerve lesion must include consideration of the internal topography of peripheral nerves.
Activity of 2′3′‐cyclic‐nucleotide 3′‐phosphodiesterase and content of PO protein in the peripheral nervous system of the dystrophic mouse and chicken
Authors: Lewis Lorraine N. , Mezel Catherine
Published: January 2005

To investigate whether various myelin markers could detect pathological changes in myelination, the activity of 2′‐3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP) and the level of PO protein were compared in the peripheral nervous system (PNS) of the dystrophic mouse and chicken and their phenotypically normal siblings. The same comparison was made for subcellular fractions of these nerves. The level of PO protein and the activity of CNP were normal in the spinal roots of sciatic nerves of the 129B6F1/Jdy/dy strain of dystrophic mouse. These parameters were slightly but significantly lower in the spinal roots of the 129REJ/dy/dy strain of dystrophic mouse. These results suggest that the 129B6F1/Jdy/dy mutant and the 129REJ/dy/dy mutant mouse might not have the same type of biochemical abnormality in their PNS. The specific activity of CNP and the proportion of PO protein increased significantly in the various regions of the PNS of 1‐day‐old chicks when compared to that of the 18‐day‐old embryos. Subcellular fractionation of peripheral nerves indicated that these components were enriched in the crude myelin fraction. These results support the conclusion that PO protein and CNP are suitable markers of myelinogenesis in the PNS of the chick. These parameters were normal in the line 413 dystrophic chicken. These results do not support the conclusion of a systemic membrane defect in the PNS of the dystrophic mouse and chicken.
Protein degradation in cultured skeletal muscle from duchenne muscular dystrophy patients
Authors: Neville Hans E. , Harrold Sharon
Published: January 2005

The loss of contractile protein in Duchenne muscular dystrophy could result from low rates of synthesis, abnormally high rates of protein degradation, or a combination of both. We measured overall protein degradation rates in cultured human muscle cells obtained at biopsy from patients with Duchenne dystrophy or various muscle diseases and normal subjects. Measurements were performed on confluent cultures exhibiting no growth and containing a mixed cell population of myoblasts, fibroblasts, and multinucleated myotubes. Using a new doubleisotope labeling protocol, we found protein degradation rates in all three groups to be similar (KD = 0.0171–0.0176 hr−1), suggesting no detectable abnormality of overall protein degradation in cells derived from Duchenne dystrophy patients.
Familial neuromuscular disease with tubular aggregates
Authors: Pierobon‐Bormioli Sandra , Armani Mario , Ringel Steven P. , Angelini Corrado , Vergani Ludovica , Betto Romeo , Salviati Giovanni
Published: January 2005

We have studied four members of a family in which five individuals of both sexes in three generations have mild weakness and muscle aching. Serum creatine kinase (CK) and/or aldolase were mildly to moderately elevated. Tubular aggregates were present in all patients in all fiber types. Type 1 fiber predominance and type 2 hypotrophy or atrophy was noted in three biopsies. Fiber splitting was prominent in two cases. Electron microscopic studies confirm that the tubular aggregates originate from muscle sarcoplasmic reticulum (SR). The presence of T tubules making contacts with some tubules inside the collection of tubular aggregates is suggestive of their derivation from terminal cisternae.
Initiation of differentiation into skeletal muscle fiber types
Authors: Dhoot Gurtej K.
Published: January 2005

A monoclonal antibody directed against a slow isoform of a 100‐K myofibrillar protein has been used to study the differentiation of muscle fibers in the fast and slow muscles of the rat. Immunohistochemical studies have shown that initiation of differentiation into fast and slow muscle fibers occurs very early during development. The distribution pattern of cell types in different muscles is unique and is also determined very early during fetal muscle development. It is concluded that motor innervation is probably not essential to initiate differentiation into distinct muscle fiber types.
Effects of thyroid hormones on the biochemical specialization of human muscle fibers
Authors: Salviati Giovanni , Zeviani Massimo , Betto Romeo , Nacamulli Davide , Busnardo Benedetto
Published: January 2005

The effects of thyrotoxicosis and of hypothyroidism on human muscle have been studied on single fiber preparations. In thyrotoxic muscle, the ratio between fibers showing the fast type of myofibrillar protein isoforms (fast fibers) and fibers showing the slow type (slow fibers) is increased, as is the percentage of fibers with incomplete segregation of fast and slow myosin (intermediate fibers). Furthermore, in fast fibers, the volume and, to a greater extent, the rate of Ca transport of sarcoplasmic reticulum (SR) are increased, without changes in the affinity for Ca2+ of the Ca‐pump or in its sensitivity to the cyclic adenosine monophosphate (cAMP) dependent protein kinase system. These effects are completely reversed by the removal of thyroid hormones, as demonstrated by hypothyroid muscles. It is suggested that in human muscle cells thyroid hormones are critical for the expression of fast genes and for SR Ca transport.
Transient conduction block following acute peripheral nerve ischemia
Authors: Parry Gareth J. , Cornblath David R. , Brown Mark J.
Published: January 2005

We studied the effects of transient focal ischemia on the electrophysiologic function of rat sciatic nerves. Focal and generalized impairment of impulse conduction, measured by falling evoked muscle and nerve compound action potential amplitudes, occurred within 10 minutes of femoral artery occlusion. Conduction failure reached a nadir at 45–60 minutes and then improved to normal within 24 hours. Fastest motor and mixed nerve conduction velocities were reduced less than 15% of baseline values during the period of acute conduction block. There were no detectable morphological abnormalities at the site of conduction failure. Transient ischemia produces reversible conduction block without evident structural changes. The fall in amplitude without significant conduction slowing implies that slower conducting myelinated fibers are relatively more sensitive to the effect of acute ischemia.
Somatosensory evoked potentials in motor neuron disease
Authors: Bosch E. Peter , Yamada Thoru , Kimura Jun
Published: January 2005

We studied median somatosensory evoked potentials (SEPs) in an unselected series of 30 patients with sporadic motor neuron disease (MND). SEPs were affected in 17 patients (57%), with a higher incidence of abnormality in amyotrophic lateral sclerosis and bulbar palsy than in progressive muscular atrophy. In a majority of patients, simultaneous bilateral stimulation of the median nerve revealed a delay or absence of scalp‐recorded central N32 and/or N60, leaving the earlier peaks intact. In the remaining cases, the N19 peak was asymmetrically prolonged. These findings suggest common involvement of somatosensory pathways in MND, either at cortical or subcortical levels, and correlate with neuropathologic reports of neuronal degeneration beyond the primary motor system.
Type 2 fiber predominance in muscle cramp and exertional myalgia
Authors: Telerman‐Toppet Nicole , Bacq Michèle , Khoubesserian Patrick , Coërs Christian
Published: January 2005

In patients complaining of muscle cramps and exertional myalgia, we found a significant decrease of type 1 muscle fiber proportion in comparison with a control group. The possible mechanism of this change is discussed.
Structure of motor nerve terminals in chickens with hereditary muscular dystrophy
Authors: Gunther Joan S. , Letinsky Michael S.
Published: January 2005

The structure and size of 1‐week to 1‐year‐old normal (line 412) and dystrophic (line 413) chicken motor nerve terminals were studied using combined pre‐ and postsynaptic histologic endplate staining. The main result is that adult dystrophic terminals have abnormal structure and are significantly smaller than normal. These differences occurred progressively during development. At 1 week ex ovo, dystrophic motor nerve terminals were similar to normals in size and appearance. By 8 weeks, differences between normal and dystrophic terminal size and structural organization began to emerge. Qualitatively, beginning at 8 weeks and becoming more frequent by 1 year of age (the endpoint of this study), dystrophic motor endplates differed from normal in having: (1) generally smaller synaptic boutons, often separated by extremely thin branching interconnectives; (2) increasing incidence of multiple innervation; and (3) frequent occurrences of apparent partial or total denervation, terminal sprouting, and reinnervation.
Decreased parvalbumin contents in skeletal muscles of C57BL/6J(dy2J/dy2J) dystrophic mice
Authors: Klug Gary , Reichmann Heinz , Pette Dirk
Published: January 2005

Parvalbumin content is decreased by 40% in hindlimb muscles of adult (3.5 months) dystrophic mice when compared to normal mice of the same age. The concentration of parvalbumin in the dystrophic muscles resembles that of immature muscles of 4‐week‐old normal mice. The reduction may contribute to an elevation of sarcoplasmic free CA2+, which could stimulate various Ca2+‐dependent processes related to the disease.
Pulmonary function and electromyographic study of respiratory muscles in myotonic dystrophy
Authors: Jammes Y. , Pouget J. , Grimaud C. , Serratrice G.
Published: January 2005

Ten adult myotonic dystrophy patients underwent measurements of lung function, maximal dynamic and static ventilatory efforts, and respiratory muscle electromyography (EMG). EMG studies were performed during spontaneous breathing or when subjects breathed through high inspiratory or expiratory resistive loads. Present results show that (1) a moderate restriction of lung volumes with hypoxemia plus normocapnia is often observed; (2) patients sustain dynamic ventilatory efforts more easily than static work; and (3) abnormalities in respiratory muscle EMG exist with spontaneous expiratory and inspiratory intercostal activities during quiet breathing and changes in muscular response to resistive loads. Inspiratory loading evokes contraction of expiratory muscles, with a marked decrease in inspiratory activities. Expiratory resistive loads prolong the diaphragmatic contraction throughout the expiratory time, and in some patients, relaxation of the diaphragm does not occur during the loaded run. These EMG data suggest that the reciprocal inhibition among respiratory neurons is enhanced in myotonic dystrophy and that myotonia also occurs in the diaphragm when loads oppose its relaxation.
Muscle energy metabolism in duchenne dystrophy studied by 31P‐NMR: Controlled trials show no effect of allopurinol or ribose
Authors: Griffiths Richard D. , Cady Ernest B. , Edwards Richard H. T. , Wilkie Douglas R.
Published: January 2005

31P nuclear magnetic resonance (NMR) was used to investigate the resting energy metabolism of the calf muscle in boys with Duchenne's muscular dystrophy. Reductions in the phosphocreatine/adenosine triphosphate (PCr/ATP) and the PCr/Pi ratios were found, but ATP as a fraction of the total mobile phosphorus signal was not reduced, and intracellular pH was normal in the Duchenne muscle. Attempts at quantitation of the NMR signal suggested that the reduced total phosphorus signal seen in the Duchenne muscle was a result of muscle fiber loss only and that the muscle fiber ATP concentration was probably normal in the diseased tissue. An exercise study in one 7‐year‐old boy with Duchenne's dystrophy demonstrated that the muscle had a normal ability to break down and resynthesize phosphocreatine. Presented here are the first reported trials of the effects of two putative therapeutic agents on energy metabolism determined by NMR in Duchenne's muscular dystrophy.
Distribution of different fiber types in human skeletal muscles: Why is there a difference within a fascicle?
Authors: Sjöström Michael , Downham David Y. , Lexell Jan
Published: January 2005

The proportions of different fiber types (type 1 and type 2) on the borders of fascicles are shown to differ from the proportions internally. This finding is based on the analysis of a total of 245 fascicles from whole cross‐sections of the vastus lateralis muscle from 13 men, aged from 26–80 years. Generally, the difference is more marked in the young than in the old. It is argued that the causes of this difference are likely to be local factors in the muscle.
Fetal myosin immunoreactivity in human dystrophic muscle
Authors: Schiaffino Stefano , Gorza Luisa , Dones Ivano , Cornelio Ferdinando , Sartore Saverio
Published: January 2005

We report immunofluorescence observations on normal and dystrophic human muscle using an antibody (anti‐bF) raised against bovine fetal myosin and specific for fetal myosin heavy chains. In rat skeletal muscle, anti‐bF was previously found to react selectively with myosin isoforms expressed during fetal and early postnatal development and in regenerating muscles.11 Anti‐bF stained most fibers in human fetal and neonatal muscle, whereas only nuclear chain fibers of muscle spindles were labeled in normal adult muscle. In muscle biopsies from patients with Duchenne's muscular dystrophy, numerous extrafusal fibers were stained: some were small regenerating fibers, others were larger fibers presumably resulting from previous regenerative events. Fetal myosin immunoreactivity in Duchenne's dystrophy appears to reflect the reexpression of fetal‐specific myosin isoforms and provides a new valuable tool for identifying regenerating fibers and following their destiny in dystrophic muscle.
Motor neuropathy associated with a facilitating myasthenic syndrome
Authors: Subramony S. H. , Mitsumoto H. , Mishra S. K.
Published: January 2005

We report a patient with progressive muscle weakness, areflexia, and no sensory loss. Electromyography revealed normal sensory nerve conductions, mild slowing of motor nerve conduction velocities, low amplitude compound muscle action potentials, a neuromuscular transmission defect characterized by prominent facilitation, and diffuse fibrillation potentials. Muscle biopsies showed acute denervation atrophy, and at autopsy, there was anterior horn cell loss and gliosis in the spinal cord. The findings suggest the coexistence of a motor neuropathy and a facilitating myasthenic syndrome.
Isolation and characterization of sarcoplasmic reticulum from normal and dystrophic chicken
Authors: Kawamoto Richard M. , Baskin Ronald J.
Published: January 2005

Purified sarcoplasmic reticulum vesicles from normal and dystrophic chicken skeletal muscle have been isolated by a procedure employing pressure disruption of a microsomal suspension. The dystrophic sarcoplasmic reticulum (SR) exhibited reduced Ca+ + transport and phosphoenzyme formation, but the Ca + + ‐ATPase activity was normal. Normal and dystrophic SR showed similar lipid profiles, except for a significant increase in free fatty acids in the dystrophic SR. Investigations involving the interaction of oleic acid with normal SR showed fatty acids can induce conditions similar to those found in dystrophic SR.
Treatment of hypersomnolence in myotonic dystrophy with a CNS stimulant
Authors: van De Meché Frans G. A. , Boogaard Jan M. , van Den Berg Bart
Published: January 2005

A 42‐year‐old man with myotonic dystrophy developed severe hypersomnolence during the year prior to admission for acute respiratory insufficiency. However, his hypersomnolence could be attributed to a central dysfunction, and during a follow‐up period of 3 years, was successfully treated with methylphenidate.
A trial of flunarizine in the treatment of duchenne muscular dystrophy
Authors: Dick David J. , Gardner‐medwin David , Gates Peter G. , Gibson Mary , Simpson Judy M. , Walls Timothy J.
Published: January 2005

Twenty‐seven boys with Duchenne muscular dystrophy (DMD) entered a double‐blind controlled trial of treatment with the calcium antagonist flunarizine. They were matched for age and disability. At monthly intervals, muscle power, functional ability, locomotor score, contractures, and forced vital capacity were measured by a team not involved in clinical care. Over a period of 1 year, flunarizine in a dose of up to 0.25 mg/kg/day had no effect on the clinical course of the disease.
The influence of skeletal muscle reinnervation on experimentally induced myotonia
Authors: Al‐sulaiman Abdulsalam , Al‐Rajeh Saad , Iyer Vasudeva
Published: January 2005

Earlier studies have shown that prior denervation of muscle prevents myotonia induced by 2,4‐dichlorophenoxy acetic acid (2,4‐D) both in vivo and in vitro. This work studied the effect of reinnervation on 2,4‐D myotonia. Twenty Sprague‐Dawley rats were injected with 2,4‐D at specific intervals following unilateral sciatic nerve crushing; the gastrocnemius muscle on both sides was studied electromyographically to assess myotonia and to document denervation and reinnervation. All the rats gradually became amyotonic following denervation; myotonia reappeared during reinnervation. Myotonic discharges were no longer detectable 1 week after nerve crushing, but returned completely within 3 weeks. Blocking axoplasmic transport with colchicine had essentially the same effect on myotonia. A reciprocal temporal relationship was noted between the occurrence of fibrillations and myotonic discharges. These findings substantiate the view that innervation is essential to maintain the muscle membrane in a state that will support myotonic discharges.
The muscle slice—A new preparation for the characterization of β‐adrenergic binding in fast‐ and slow‐twitch skeletal muscle
Authors: Watson ‐Wright Wendy M. , Wilkinson Michael
Published: January 2005

A new procedure is presented that characterizes the specific binding of the β‐adrenergic antagonist, [3H]CGP‐12177, to thick (1 mm) slices from fast‐twitch [extensor digitorum longus (EDL)] and slow‐twitch (soleus) mouse skeletal muscle. Binding is reversible, saturable, stereospecific, of high affinity, and subject to agonist‐induced desensitization, indicating that it is to β‐adrenoreceptors and not to other sites. In both muscles, the majority of specific binding is to the β2‐receptor subtype. Bmax is approximately twice as high in the soleus (5.64 ± 0.52 fmol/mg wet weight) as in the EDL (2.66 ± 0.29 fmol/mg wet weight) (P < 0.05), whereas affinity is higher in the fast‐twitch (Kd = 0.30 ± 0.08 nM) than the slow‐twitch muscle (Kd = 0.45 ± 0.08 nM). The minimal tissue disruption associated with this procedure, as well as its speed, simplicity and relatively low cost, suggest that the slice preparation may prove to be invaluable for the future study of β‐adrenergic receptor binding and associated responses in skeletal muscle.
Induction of spheroid cytoplasmic bodies in a rat muscle by local tetanus
Authors: Chou Samuel M. , Mizuno Yoshihiko
Published: January 2005

The term “cytoplasmic body” or “spheroid body” myopathy refers to a heterogeneous group of familial or sporadic diseases characterized primarily by the presence of abundant spheroid or cytoplasmic bodies in the muscles. The morphogenesis of these inclusions remains unclear. This article describes the induction and evolution of spheroid cytoplasmic bodies (SCBs) in the rat plantaris muscle (PL) with local tetanus, which was induced in rats by the injection of a minute amount of tetanus toxin. In contrast to the tetanized soleus muscle (SOL), which developed core fibers (central cores, minicore, target fiber, targetoid fiber, and rods), the tetanized PL produced numerous SCBs with a predictable time course. They were induced in both type 1 and 2 fibers of PL, which is composed predominantly (95%) of type 2 fibers, in contrast to SOL (85% type 1 fibers). Factors inducing SCBs may include immobilization, shortening, intact innervation, and disuse atrophy.
Automatic analysis of the electromyographic interference pattern. Part II: Findings in control subjects and in some neuromuscular diseases
Authors: Nandedkar Sanjeev D. , Sanders Donald B. , Stålberg Erik V.
Published: January 2005

The electromyographic (EMG) interference pattern (IP) was measured in the biceps muscle of 16 normal male and 17 normal female subjects. The activity, upper centile amplitude (UCA), and the number of small segments (NSS) (defined in a companion paper) were measured from 500‐msec epochs of the IP. The normal values of these features were defined separately for men and women by plotting the UCA and NSS values against activity for each epoch and defining an area on these plots, called a “cloud,” that contained more than 90% of the datum points from each study. The mean deviation of the individual datum points from the overall mean values was also calculated for each study. A study in one muscle is considered to be normal if more than 90% of the datum points from that muscle are within the normal clouds and the deviation values are within their normal range. In patients with neuropathy, the characteristic pattern was increased UCA with normal or decreased NSS. In patients with myopathy, NSS was increased and the UCA was normal or decreased. In all studies, the interpretations of the IP from the plots agreed with qualitative assessments of the IP made independently by an electromyographer. The use of these features to understand and quantitate the changes in the motor units produced by disease is demonstrated by serial studies performed in a patient with motor neuron disease.
Disorders of neuromuscular transmission in infants and children
Authors: Cornblath David R.
Published: January 2005

Disorders of neuromuscular transmission in infants and children can be divided into two groups. The first group includes conditions similar to those seen in adults: autoimmune myasthenia gravis, Lambert‐Eaton myasthenic syndrome, and botulism. The second includes several disorders that are unique to this age group, such as the congenital myasthenias and infantile botulism. This review discusses the diseases of neuromuscular transmission found in the pediatric population, with emphasis on electrodiagnosis. The distinctive clinical and electrophysiologic features allow the clinician to identify these illnesses correctly, so that appropriate treatment can be instituted or further specialized investigation can be undertaken.
The exercise test in periodic paralysis
Authors: McManis Philip G. , Lambert Edward H. , Daube Jasper R.
Published: January 2005

Of 21 patients with clinically definite hypokalemic, hyperkalemic, or normokalemic periodic paralysis, 15 (71%) had a greater than normal increase in compound muscle action potential amplitude during 2–5 minutes of intermittent strong voluntary contraction of the muscle. This increase was followed by a progressive decline in amplitude, which was greater than in a control population and which was most rapid during the first 20 minutes after exercise. The amplitude often decreased to a level below the preexercise level. A similar response was seen in six of nine patients with periodic paralysis secondary to disorders such as thyrotoxicosis. This test may have value in the identification of patients with periodic paralysis.
AAEE Case report #12: Common peroneal mononeuropathy at the fibular head
Authors: Wilbourn Asa J.
Published: January 2005

Common peroneal monoeuropathies, usually located at the fibular head, are one of the many causes of foot‐drop, a condition often evaluated in the electromyography laboratory. If appropriate nerve conduction studies are performed and particular muscles studied on needle myography, a satisfactory diagnosis can almost always be provided for what may be a perplexing problem clinically. With all peroneal mononeuropathies, the compound muscle action potential amplitude of the peroneal motor tibialis anterior nerve conduction studies, stimulating distal to the fibular head, is a semiquantitative measure of the number of viable fibers supplying the tibialis anterior and allows for accurate prognostication regarding the foot‐drop.
Acute arsenic intoxication presenting as guillainbarréa‐like syndrome
Authors: Donofrio Peter D. , Wilbourn Asa J. , Albers James W. , Do Lisa Rogers, , Salanga Virgilio , Greenberg Harry S.
Published: January 2005

Arsenic‐induced polyneuropathy is traditionally classified as an axonal‐loss type, electrodiagnostically resulting in low amplitude or absent sensory and motor responses, relatively preserved proximal and distal motor conduction rates, and distal denervation. We report four patients with a subacute onset progressive polyradiculoneuropathy following high‐dose arsenic poisoning. In three patients, early electrodiagnostic testing demonstrated findings suggestive of an acquired segmental demyelinating polyradiculoneuropathy. Serial testing confirmed evolution into features of a distal dying‐back neuropathy. We hypothesize that arsenic toxicity and the resultant biochemical derangement of the peripheral nerve cell leads to subtle changes in axonal function that produce, initially, segmental demyelination and eventually distal axonal degeneration. Acute arsenic toxicity must be suspected in patients with clinical and electrodiagnostic features supporting Guillain‐Barré syndrome.