bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium paradox in skeletal muscles: Physiologic and microscopic observations
Authors: Soza Marco , Karpati George , Carpenter Stirling 
Published: January 2005

AbstractImmersion of rat hemidiaphragms in Ca2+‐free Krebs solution (KS) containing Ca2+ chelator in vitro leads to separation of basal lamina from the plasma membrane, as well as transient contracture and rapid loss of twitch response [calcium paradox (CP) phase 1]. Subsequent immersion in regular KS results in necrosis of muscle fibers accompanied by slowly increasing contracture (CP phase 2). This contracture could be prevented or reduced by using either Ca2+‐free KS or calcium channel blockers, but not by dantrolene sodium, implying that after drastic reduction of extracellular and sarcolemmal Ca2+ during CP phase 1, the sarcolemma has lost its ability to control normal Ca2+ fluxes. Contracture did not develop at 21°C. CP is a convenient model to study calciuminduced muscle cell death and the role of Ca2+ in maintaining sarcolemmal integrity.
Adverse effect of verapamil in a patient with the lambert‐eaton syndrome
Authors: Krendel David A. , Hopkins Linton C. 
Published: January 2005

AbstractA patient with the Lambert‐Eaton syndrome (LES) and small cell lung cancer developed respiratory failure several hours after verapamil was given. Improvement in respiratory function did not occur when guanidine was given, but was delayed until verapamil was discontinued 3 days later. Although other factors may have contributed to the clinical deterioration of our patient, the temporal relationship to verapamil and the theoretical danger of calcium channel blockade lead us to believe that the drug should be used cautiously in LES.
Neuropathy associated with cryoglobulinemia
Authors: Lippa Carol F. , Chad David A. , Smith Thomas W. , Kaplan Melvin H. , Hammer Kathryne 
Published: January 2005

AbstractA patient with severe subacute sensory ataxia was found to have an IgM (kappa) cryoglobulin. Clinical, electrophysiologic, and sural nerve biopsy studies indicated that axonal degeneration and segmental demyelination both played a role in the pathogensis of this neuropathy. Corticosteroid therapy was associated with notable clinical improvement and a 50% decrease in cryoglobulin concentration.
Duchenne dystrophic muscle develops lesions in long‐term coculture with mouse spinal cord
Authors: Peterson Edith R. , Masurovsky Edmund B. , Spiro Alfred J. , Crain Stanley M. 
Published: January 2005

AbstractWhen strips of human skeletal muscle from biopsies of normal children and donors with Duchenne muscular dystrophy (DMD) are explanted in organotypic coculture with fetal mouse spinal cord, many regenerating muscle fibers develop, become innervated, and maintain a remarkable degree of mature structure and function for more than 3–6 months in vitro. Sequential light microscopy in correlation with electron‐microscopic and electrophysiologic analyses showed that despite cross‐species innervation, these human muscle fibers develop stable cross‐striations, peripherally positioned myonuclei, and mature, functional motor endplates. Of special interest is the onset of significant progressive abnormalities, e.g., unusual focal myofibrillar lesions, in substantial numbers of innervated mature DMD muscle fibers after 2–4 months in culture. The focal myofibrillar lesions were not detected in normal muscle fibers maintained as long as 6 months in coculture, nor are they comparable to the generalized loss of cross‐striations observed in muscle atrophy following in vitro denervation of mature DMD fibers.
AAEE Minimonograph #25: Single‐fiber electromyography in myasthenia gravis
Authors: Sanders Donald B. , Howard James F. 
Published: January 2005

AbstractSingle‐fiber electromyography (SFEMG) demonstrates abnormal jitter in virtually all (99%) patients with myasthenia gravis (MG). One muscle, the extensor digitorum communis, is abnormal in most patients with this disease, but to obtain the maximum diagnostic sensitivity, it may be necessary to examine other muscles, especially ones that are more involved clinically. There is no one muscle that will be more abnormal in every patient with MG. The muscle(s) to be tested must be selected based on the distribution of weakness in the individual patient. Abnormal jitter is also seen in diseases of nerve and muscle; these diseases must be excluded by other electrophysiologic and clinical examinations before diagnosing MG. If neuronal or myopathic disease is present, increased jitter does not indicate that MG is also present. However, if jitter is normal in a muscle with definite weakness, the weakness is not due to MG. When abnormal neuromuscular transmission has been demonstrated by repetitive nerve stimulation, the finding of abnormal jitter does not add to the diagnosis, though it may be useful in providing baseline values for comparison with the results of subsequent studies. SFEMG is most valuable clinically in the patient with suspected MG in whom other tests of neuromuscular transmission and antiacetylcholine receptor antibody titers are normal. Serial measurements of jitter can be useful in following the course of disease and in assessing the effect of treatment, but the results from these studies must always be interpreted in light of the overall clinical picture.
Potassium channel blockers and impulse propagation in murine motor endplate disease
Authors: Bournaud Roland , Mallart Alberto 
Published: January 2005

AbstractAn electrophysiologic study has been performed on motor nerves of mice affected with hereditary “motor endplate disease” (MED). Bath application of potassium channel blockers, such as tetraethylammonium and 3,4‐diaminopyridine, which are almost without effect on the monophasic compound action potential of normal nerves, considerably enhanced the action potential duration in nerves from mutant mice. Furthermore, external current recordings from motor endings revealed an absence of the K‐dependent waveform component in MED mice, which indicates a similar K current intensity in the terminal part of the endings and in the heminode. These observations suggest that in the mutant, unlike in normal mice, K channels play a role in action potential electrogenesis. Possible relationships with paranodal dysmyelination are discussed.
Double‐step repetitive stimulation in myasthenia gravis
Authors: Gilchrist James M. , Sanders Donald B. 
Published: January 2005

AbstractThe double‐step technique of repetitive nerve stimulation was compared with repetitive nerve stimulation to a distal and a proximal muscle and with single fiber needle electromyography in 10 patients with myasthenia gravis. We conclude that the double‐step technique is slightly more sensitive than repetitive nerve stimulation to a proximal muscle but only 60% as sensitive as single fiber electromyography in demonstrating abnormal neuromuscular transmission in myasthenia gravis.
Serotonin uptake in blood platelets of duchenne muscular dystrophy patients
Authors: Arora Ramesh C. , Meltzer Herbert Y. , Kuncl Ralph W. , Morgan Juliet , Cohen Louis 
Published: January 2005

AbstractSerotonin (5‐HT) uptake was studied in the blood platelets of 10 patients with Duchenne‐type muscular dystrophy (DMD) and 7 age‐matched controls. Vmax (maximum number of uptake sites) of platelet 5‐HT uptake in the DMD patients was significantly less than that of the normal controls. There was no difference in the affinity for 5‐HT (Km) between the two groups. There was a significant negative correlation between serum creatine kinase activity and Km of 5‐HT uptake in blood platelets of these patients. However, no correlation was found between Km or Vmax and ambulatory status of DMD.
Changes in guinea pig muscle histology in response to reduced bobility
Authors: Leiveseth Gunnar , Tindall Alex , Myklebust Reidar 
Published: January 2005

AbstractDorsiflexion of one hind foot has been prevented in guinea pigs by means of a light prosthesis. The gastrocnemius and soleus muscles of both hind legs have been removed after a period of 2 weeks, and the fiber cross‐sectional areas of type 1 and 2 fibers in both muscles have been measured Comparison of the values in normal and affected muscles shows that the limited reduction in free movement of the foot led to a significant atrophy in types 1 and 2 fibers in both muscles.The use of this simple prosthesis appears to have no effect on any other function of the leg except for the restriction of the lengthening of gastrocnemius and soleus muscles, and the results show that some of the hypotheses about the muscle atrophy seen in fully immobilized limbs cannot account for the changes observed in the present experiments and seem to be of limited validity.
Glucocorticoid excess induces preferential depletion of myosin in denervated skeletal muscle fibers
Authors: Rouleau Guy , Karpati George , Carpenter Stirling , Soza Marco , Prescott Steve , Holland Paul 
Published: January 2005

AbstractThe combined effects of dexamethasone treatment (1 mg/Kg/day) plus denervation (DEX‐DEN), were studied at 7, 13, and 28 days by microscopic, biochemical, and physiological techniques in plantaris and soleus muscles of adult rats. The results were compared with corresponding dexamethasone‐treated (DEX) and denervated (DEN) muscles and appropriate controls. There was a significantly more marked atrophy of all fiber types in the DEX‐DEN plantares at 7 and 13 days than in either DEX or DEN muscles. The degree of atrophy was greatest in type 2B fibers in DEX‐DEN plantares. Electron microscopy revealed a severe preferential depletion of thick myofilaments in DEX‐DEN plantares and solei but not in DEX or DEN muscles. The thick myofilament depletion in DEX‐DEN muscles occurred in addition to a severe overall reduction of myofibrillar caliber. Gel electrophoresis showed a marked preferential decrease of myosin heavy chain in DEX‐DEN plantares and solei, but not in either DEX or DEN muscles. Myosin light chains were also markedly reduced in DEX‐DEN plantares and solei. In vitro physiological studies showed a marked reduction of the denervation‐induced twitch potentiation in DEX‐DEN solei. Maximal tetanic tension (20 Hz stimulation) per gram weight of muscle as well as the twitch‐tetanus ration was significantly reduced only in DEX‐DEN solei in relation to controls. Myosin depletion in DEX‐DEN muscles may be due to a severe preferential inhibition of its synthesis coupled with an accelerated catabolism.
Effects of acidosis on tension development in mammalian skeletal muscle
Authors: Ranatunga K. W. 
Published: January 2005

AbstractEffect of carbon dioxide acidosis on the tension development in a rat skeletal muscle (extensor digitorum longus) was examined at different temperatures. Experiments were done in vitro and with direct stimulation, mostly at constant temperatures between 30–35°C and 12–20°C. A decrease of saline pH (8.0 to 6.5) with carbon dioxide increased the twitch and the tetanic tensions and enhanced the tension relaxation in experiments done at high temperatures. At low temperatures the same procedure decreased the tetanic tension and enhanced the tension relaxation. An increased tetanic tension at the high temperatures and a decreased tetanic tension at the low temperatures were also obtained at constant saline pH, with procedures known to decrease intracellular pH. The observations made at higher temperatures are discussed in relation to human muscle performance in exercise.
Syringomyelia: Electrophysiologic aspects
Authors: Veilleux Martin , Stevens J. Clarke 
Published: January 2005

AbstractThe clinical and EMG findings in 44 patients with syringomyelia who were seen at the Mayo Clinic between 1976 and 1985 are presented. In 10 of the patients, somatosensory evoked potentials (SEPs) of the upper and lower extremities were obtained. All 44 patients had radiographic or surgical evidence of a cervical syrinx. The most common abnormality on nerve conduction studies was a reduced hypothenar compound muscle action potential amplitude (23 patients). Abnormal findings on needle electromyography were present in 33 patients and included sparse fibrillation potentials, reduced motor unit potential (MUP) recruitment, and chronic neurogenic MUP changes in muscles innervated by the C‐5, T‐1 roots, with the most pronounced changes in small hand muscles. Ulnar and median nerve SEPs were usually normal in the presence of a dissociated sensory loss and were usually abnormal when all sensory modalities were impaired. Abnormalities of tibial nerve SEPs were frequent and were related to impaired proprioceptive sensation in the lower extremities.
Trial of a cysteine proteinase inhibitor, EST, in experimental chloroquine myopathy in rats
Authors: Sugita Hideo , Higuchi Itsuro , Sano Motoki , Ishiura Shoichi 
Published: January 2005

AbstractThe administration of 50 mg/kg/day of chloroquine to rats for 8 weeks produced the chloroquine myopathy characterized by autophagic vacuole formation and increases in lysosomal enzymes, especially cathepsins B & L. Coadministration of 10 mg/kg/day of a potent cysteine proteinase inhibitor, EST, and chloroquine prevented the induction of the chloroquine myopathy. Rats already suffering from the chloroquine myopathy were treated with 10 mg/kg/day of EST together with chloroquine injections for 5 weeks and also recovered remarkably from the myopathy. Thus, EST may be beneficial for myopathies associated with autophagic vacuoles.
AAEE case report #13: Diabetic amyotrophy
Authors: Chokroverty Sudhansu 
Published: January 2005

AbstractA case fulfilling the criteria for the diagnosis of diabetic amyotrophy is reported. Based on the clinical and electrodiagnostic features, it is concluded that diabetic amyotrophy is a recognizable clinical entity that can be differentiated from other diabetic neuropathies. The site of the lesion and the pathogenesis in diabetic amyotrophy remain controversial. The usual course of the illness is one of gradual improvement over weeks to months.
Canine masticatory muscle disorders: A study of 29 cases
Authors: Shelton G. Diane , Cardinet George H. , Bandman Everett 
Published: January 2005

AbstractThe histopathologic features in temporalis muscle biopsies from 29 dogs with masticatory muscle disorders were characterized and used for their subgrouping: 2 without lesions, 3 with nonspecific changes, 7 with neurogenic atrophy, and 16 with myositis. The immunocytochemical and immunochemical features of the muscle biopsies and sera from those dogs were compared among the histopathologic subgroupings and compared with biopsies and sera from healthy dogs and dogs with polymyositis. Of the 14 biopsies from dogs with masticatory muscle myositis, 12 had immune complexes limited to type 2M fibers, whereas 13 of 16 sera samples had detectable antibodies against type 2M fibers. The immune complex deposition was found only in biopsies of dogs with masticatory muscle myositis, and the antibodies were detected in the sera of only one dog that did not have masticatory muscle myositis. Immunoblot assays revealed that the antibodies were most often directed against a 185 K protein, myosin heavy chain, and a band that appeared to be LC2‐M (myosin light chain 2‐masticatory).
Temperature dependence of contraction characteristics in developing rat muscles
Authors: Wylie S. R. , Ranatunga K. W. 
Published: January 2005

AbstractContractions of rat extensor digitorum longus (EDL, a fast muscle) and soleus (SOL, a slow muscle muscles of different ages 1–4 weeks) were recorded in vitro with direct stimulation and at different temperatures (range 35–10°C). Twitch tension in 4‐week‐old EDL muscle increased in cooling from 35 to 20°C (cooling potentiation); the tension decreased in further cooling below 20°C. This pattern of temperature dependence of twitch tension was seen in fast muscles of all ages (1–4 weeks). Twitch tension in 4‐week‐old SOL muscle decreased monotonically in cooling from 35 to 10°C (cooling depression). This pattern of cooling depression was not clearly evident in younger SOL muscles. There was a marked hysteresis in the temperature dependence of twitch tension in the 1‐week‐old SOL muscles. Tetanic tension was depressed by low temperature in both EDL and SOL muscles at 1 week and at 4 weeks of age. Results show that the processes concerned with contractile activation are nearly fully developed in the fast muscle fibers at an early age (1 week), whereas they develop later in the slow muscle fibers.
Immunohistochemical localization of AMP deaminase in rimmed vacuoles in human skeletal muscle
Authors: Higuchi Itsuro , Ishiura Shoichi , Nonaka Ikuya , Sugita Hideo 
Published: January 2005

AbstractHigh AMP deaminase reactivity was detected in the rimmed vacuoles in skeletal muscles in adult onset acid maltase deficiency and distal myopathy with rimmed vacuole formation histochemically as well as immunohistochemically. Acid phosphatase activity was positive but myosin ATPase activity was negative in the vacuoles. AMP deaminase found in rimmed vacuoles does not seem to be associated with myosin but is possibly bound to lysosomes or other related organelles in accordance with the proliferation of autophagic vacuoles.
Histoenzymatic profile of human muscle cultured in monolayer and innervated de novo by fetal rat spinal cord
Authors: Vita Giuseppe , Askanas Valerie , Martinuzzi Andrea , Engel W. King 
Published: January 2005

AbstractWe examined histoenzymatic characteristics of human muscle fibers grown in monolayer culture and innervated de novo in culture for 60–90 days by fetal rat spinal cord neurons. Serial cryostat cross sections were obtained using a freshly frozen sandwich of adult rat muscle and cultured human muscle. An Advanced degree of morphologic and histoenzymatic maturation of cultured human muscle was reached after innervation. In contrast to aneurally cultured human muscle fibers, the innervated muscle fibers were smaller in diameter and had myonuclei preferentially located at the periphery of the fiber. The innervated fibers contained a well‐developed intermyofibrillar network revealed by the NADH‐TR and SDH reactions. Phosphorylase activity was strong to moderate in most muscle fibers. Although most of the innervated cultured muscle fibers were still not fully differentiated into two histochemical fiber types because they had strong ATPase activity after both alkaline and acid preincubation, a few of them had an ATPase profile similar to type 2 fibers in human adult muscle and had reciprocal staining with phosphorylase and NADH‐TR reactions. This is the first evidence of differentiation into different histochemical fiber types of human muscle cultured in monolayer and innervated de novo by fetal rat spinal cord.
AAEE case report #14: Neuralgic amyotrophy (acute brachial neuropathy)
Authors: Subramony S. H. 
Published: January 2005

AbstractNeuralgic amyotrophy is characterized by acute onset of arm pain, followed after a variable interval by flaccid paralysis in the distribution of the brachial plexus on one or sometimes both sides. Electromyography reveals findings suggestive of an axonal degeneration process affecting various portions of the brachial‐plexus or individual nerves emanating from it, sometimes difficult to localize to discrete cords, trunks, or nerves. Diagnosis is established by excluding other causes, including compression and vasculitides. Prognosis for recovery is excellent.
Chloroquine myopathy and myasthenia‐like syndrome
Authors: Sghirlanzoni Angelo , Mantegazza Renato , Mora Marina , Pareyson Davide , Cornelio Ferdinando 
Published: January 2005

AbstractA young woman on chronic corticosteroid treatment for systemic lupus erythematosus developed a myasthenia‐like syndrome 7 weeks after starting chloroquine therapy. Discontinuation of chloroquine allowed symptomatic and immunological remission within 6 months. Ocular symptoms reappeared following a second short course of chloroquine. A motor‐point biopsy revealed a vacuolar myopathy with membranous bodies in intramuscular nerves. We discuss the possible role of chloroquine in the pathogenesis of a myasthenia‐like syndrome.
Simulation of concentric needle EMG motor unit action potentials
Authors: Nandedkar Sanjeev D. , Sanders Donald B. , Stälberg Erik V. , Andreassen Steen 
Published: January 2005

AbstractComputer simulations of motor unit action potentials (MUAPs) as measured by a concentric needle (CN) electromyography (EMG) electrode in normal motor units (MUs) indicated that the MUAP amplitude is determined mainly by the proximity of the electrode to the closest muscle fiber. The area and duration of the simulated MUAPs were affected by all muscle fibers in front of the active recording surface but mainly by those that were less than 2 and 2.5 mm, respectively, from the active recording surface. The MUAP area was also affected by the proximity of the electrode to the closest muscle fiber. The number of phases of the simulated MUAPs increased when the dispersion of the arrival times of individual muscle fiber APs at the electrode was increased. Increased temporal dispersion of APs decreased the MUAP amplitude and area slightly but did not affect the MUAP duration. It is inferred that different features of the CN MUAP are determined by the distribution of muscle fibers within different portions of the MU territory and thus provide complementary information about the MU architecture.
Hexosaminidase a activity and amyotrophic lateral sclerosis
Authors: Gudesblatt Mark , Ludman Mark D. , Cohen Jeffrey A. , Desnick Robert J. , Chester Sara , Grabowski Gregory A. , Caroscio James T. 
Published: January 2005

AbstractAbnormalities of GM2 ganglioside metabolism owing to hexosaminidase A (Hex A) deficiency have been associated with ALS phenotypes. The clinical features described in these ALS patients with Hex A deficiency include early onset, positive family history, and/or long disease duration. In an attempt to determine prospectively the incidence of Hex A deficiency within an ALS population, the records of The Mount Sinai Medical Center ALS Clinic were reviewed to select those patients with “atypical” ALS (total N = 52), i.e. onset before age 35, positive family history, and/or disease duration greater than 90 months. The control group (total N = 50), “typical” ALS patients, did not fulfill any of these historical criteria. Hex A activity determined in isolated peripheral blood leukocytes was normal in all typical ALS patients (mean 67.3%). Hex A deficiency was not found in any atypical ALS patients. Thus, Hex A deficiency apparently is an unusual etiology of typical or atypical ALS but is of medical and genetic importance in individual families.
Continuous motor unit activity confined to the upper extremities
Authors: Tandan Rup , Fries Timothy J. 
Published: January 2005

AbstractWe report a patient with clinical vermiform motor activity, muscle cramps, delayed relaxation of grip, and continuous motor unit discharges who developed mild symmetric symptoms in the upper extremities following a viral infection. Treatment with carbamazepine produced considerable symptomatic improvement. Needle electromyography (EMG) in several muscles showed irregular grouped spontaneous discharges composed of potentials resembling normal motor units. The discharges occurred asynchronously in distal muscles with identical and different peripheral nerve innervation but were not seen in more proximal muscles innervated by the same nerves. Our EMG findings indicate an origin of this spontaneous activity in the terminal branched motor nerves.