bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limitations of the spike‐triggered averaging technique
Authors: Calancie Blair , Bawa Parveen 
Published: January 2005

AbstractThe spike‐triggered averaging technique, when used to obtain the twitch profile of a single motor unit, requires the maintenance by the subject of that unit's minimal rhythmic firing rate, which is typically between 8 and 12 pulses/sec. Literature on the rate—tension relationship of cat motor units shows that some twitches may start to fuse atstimulus rates as low as 2 pulses/sec. This fusion changes the mechanical characteristics of the observed apparent twitch from those of the unfused twitch. The present work has assessed the changes in contraction time, half‐relaxation time, and twitch amplitude of slow versus fast twitch cat single motor units, when these units are demonstrating varying degrees of fusion of tension. As the stimulus rate applied to cat single motor units increased to those typically used during spike‐triggered averaging, the values of all three twitch parameters decreased, with this decrease being more prominent for slow‐contracting versus fast‐contracting units.
Decreased water permeability of erythrocyte membranes in patients with duchenne muscular dystrophy
Authors: Serbu Ana Maria , Marian Alice , Popescu Octavian , Pop Victor I. , Borza Victoria , Benga Ileana , Benga Gheorghe 
Published: January 2005

AbstractThe water proton relaxation times of erythrocytes (T′2a) from 15 Duchenne muscular dystrophy (DMD) patients and age‐matched controls have been determined by a pulse nuclear magnetic resonance technique. Statistically significant higher values of T′2a were noted for the DMD erythrocytes, both in the presence or absence of p‐chloromercuribenzene sulfonate, a potent inhibitor of water diffusion through erythrocyte membrane. As the values of T′2a are inversely related to the water permeability, the results indicate a decreased permeability of erythrocyte membrane in DMD. The findings are discussed in relation to the molecular mechanisms of water diffusion across erythrocyte membrane and in regard to the general problem of membran abnormalities in DMD.
Serum carbonic anhydrase III in myotonic dystrophy
Authors: Mokuno Kenji , Riku Shigeo , Matsuoka Yukihiko , Kato Kanefusa 
Published: January 2005

AbstractSerum carbonic anhydrase III (CAIII) levels were determined by means of an enzyme immunoassay method and were compared with serum creatine kinase (CK) and muscle‐specific enolase (MSE) levels in 33 patients with myotonic dystrophy. Serum CAIII levels were elevated in all 33 patients, whereas serum CK and MSE levels were elevated in 12 and 10 patients, respectively. Serum CAIII levels showed a good correlation with CK levels, but a poor one with MSE levels. There was no obvious correlation between the serum CAIII level and the duration of illness or the age of the patient. These results suggest that serum CAIII is probably a more sensitive marker than CK and MSE in myotonic dystrophy and may also reflect the type 1 fiber abnormality more predominantly observed in myotonic dystrophy.
Superficial peroneal nerve conduction studies for electromyographic diagnosis
Authors: Levin Kerry H. , Stevens J. Clarke , Daube Jasper R. 
Published: January 2005

AbstractA new standardized surface technique for conduction studies of the superficial peroneal nerve was developed and applied to 35 normal subjects and 63 patients with peroneal mononeuropathies, lumbar radiculopathies, sciatic neuropathies, lumbosacral plexopathies, or peripheral neuropathies. The response amplitude was greater than 5 μV and the response peak latency was less than 4.1 msec in all normal subjects; however, 8.6% of normal subjects had at least one unelicitable superficial peroneal nerve response (6% of all limbs tested). These data were compared with those of previous studies. Although this technique did not improve the diagnosis of peroneal neuropathy, it did distinguish lumbosacral plexopathy and sciatic neuropathy from L5 radiculopathy and served as a second, easily approachable, sensory conduction study of the leg.
A mathematical analysis of creatine kinase activity in the course of duchenne muscular dystrophy
Authors: Pernice W. , Guggolz M. A. , Guggolz M. , Beckmann R. , Wais U. 
Published: January 2005

AbstractRecently, clinical follow‐up studies have shown that the age of first symptoms and the speed of progress may vary considerably in Duchenne muscular dystrophy (DMD). Prognostic factors would be of interest not only for the patients themselves, but also for the selection of DMD patients for therapeutic studies. Creatine kinase (CK) activity reflects the dystrophic degeneration of the muscle cells. Therefore, the coherence of the course of CK activity and its relationship to the clinical state was investigated with the aid of a heuristic mathetmatical formula. Two constants were calculated, b and c The data of 88 DMD patients proved the validity of the mathematical formula. Constant b seemed to be of no clinical relevance. The height of constant c was related to the age at which the ability to walk was lost (r = −0.76). This constant provides an objective individual assessment of the prognosis in DMD. In addition, the mathematical analysis of the CK course opens the way for a prospective CK estimation, which is relevant for the evaluation of therapeutic trials.
Muscle membrane excitation and impulse propagation velocity are reduced during muscle fatigue
Authors: Milner‐Brown H. S. , Miller Robert G. 
Published: January 2005

AbstractIn order to determine whether or not impulse propagation was impaired during muscle fatigue, evoked muscle compound potentials (MCP) and twitches were recorded, both before and after fatigue, from the first dorsal interosseus (FDI), adductor pollicis (AP), and anterior tibialis (AT) muscles following supramaximal ulnar and peroneal nerve stimulation, respectively. The muscles were fatigued by maintaining maximum voluntary isometric, index finger abduction, thumb adduction, or ankle dorsiflexion for 1–5 minutes. FDI was most markedly altered, with reduced MCP amplitude (mean 32%) and increased MCP duration (mean 47%) after only 1 minute. After fatigue of longer duration (3–5 minutes), there were corresponding reductions in both the MCP amplitudes and the twitch tensions recorded from both the FDI and ankle dorsiflexors. We conclude that (1) a reduction in both the level of excitation and impulse propagation velocity of muscle membranes occurs during muscle fatigue, and (2) the magnitude of this reduced membrane function and its contribution to the mechanisms underlying fatigue depend both on the duration and degree of fatigue, as well as on the intrinsic properties of the particular muscle.
Simulation and analysis of the electromyographic interference pattern in normal muscle. Part I: Turns and amplitude measurements
Authors: Nandedkar Sanjeev D. , Sanders Donald B. , Stålberg Erik V. 
Published: January 2005

AbstractThe electromyographic (EMG) interference pattern (IP) was simulated by adding together motor unit action potentials (MUAPs) of different sizes that had been recorded by a concentric needle EMG electrode. The number of turns (NT) of the simulated IP increased with the number of MUAP discharges. The mean amplitude (MA) difference between successive turns in the IP increased when large amplitude MUAPs were added. Our analysis demonstrates that the MA of the IP is determined mainly by the amplitude of large MUAPs in the signal and that large amplitude spikes are more likely to be generated by single large amplitude MUAPs than by summation of several small amplitude MUAPs.
Endoneurial sodium accumulation in galactosemic rat nerves
Authors: Mizisin Andrew P. , Myers Robert R. , Powell Henry C. 
Published: January 2005

AbstractMicrodrop samples of endoneurial fluid and serum from galactosemic rats were analyzed with energy dispersive spectrometry (EDS). The sodium concentration of endoneurial fluid from galactose‐fed rats (295 meq/liter) was nearly twice that of age‐matched controls (152 meq/liter) and indicates that sodium is present in an osmotically significant concentration that is capable of causing the edema and increased endoneurial fluid pressure (EFP) associated with galactose neuropathy. It is suggested that accumulation of endoneurial sodium is linked to the movement of sugar into the endoneurium.
Facioscapulohumeral muscular dystrophy: The choice of a biopsy site
Authors: Bodensteiner John B. , Schochet Sydney S. 
Published: January 2005

AbstractThe utilization of so‐called standard muscles for biopsy in patients with the clinical features of facioscapulohumeral muscular dystrophy (FSH) often results in nondiagnostic pathologic findings. Five patients are presented who had biopsies of the supraspinatus muscle in addition to one of the standard muscles. The supraspinatus muscle was diagnostic in all five cases. The findings suggest that the supraspinatus muscle should be considered as the biopsy site of first choice in those patients in whom the clinical picture suggests facioscapulohumeral‐type muscular dystrophy.
Role of glucocorticoids in the response of rat leg muscles to reduced activity
Authors: Jaspers Stephen R. , Tischler Marc E. 
Published: January 2005

AbstractAdrenalectomy did not prevent atrophy of rat soleus muscle during 6 days of tail cast suspension. Cortisol treatment enhanced this atrophy and caused atrophy of the weight‐bearing soleus and both extensor digitorum longus (EDL) muscles. Unloading led to increased sarcoplasmic protein concentration in the soleus, but cortisol administration increased the myofibrillar (+stromal) protein concentration in both muscles. Suspension of hindlimbs of adrenalectomized animals led to faster protein degradation, slower sarcoplasmic protein synthesis, and faster myofibrillar protein synthesis in the isolated soleus, whereas with cortisol‐treated animals, the difference in synthesis of myofibrillar proteins was enhanced and that of sarcoplasmic proteins was abolished. Both soleus and EDL of suspended, cortisol‐treated animals showed faster protein degradation. It is unlikely that any elevation in circulating glucocorticoids was solely responsible for atrophy of the soleus in this model, but catabolic amounts of glucocorticoids could alter the response of muscle to unloading.
Electrophysiologic denervation changes of human muscle fibers in motoneuron diseases
Authors: Uchitel Osvaldo D. , Dubrovsky Alberto L. 
Published: January 2005

AbstractMuscle denervation and reinnervation by sprouting of the surviving motoneurons characterizes diseases (MND). In mammalian muscles, experimental denervation induces the appearance of extrajunctional acetylcholine (ACh) receptors and tetrodotoxin (TTX) resistant action potentials (AP). These denervation changes have been investigated in muscle biopsies from 10 MND patients and in 2 traumatically denervaed normal human muscles. Extrajunctional ACh sensitivity was present in 113 of the 140 (73%) fibers from MND muscles studied. In 50 of 84 (70%) ACh‐sensitive fibers, no TTX‐resistant AP were present. The remaining fibers (30%) showed small regenerative responses. In contrast, all the traumatically denervatedmuscle fibers showed extrajunctional ACh sensitivity and TTX‐resistant AP. Histochemical analysis of the biopsies showed no direct correlation between the frequency of ACh‐sensitive fibers and that of the atrophic or normal‐appearing fibers. The absence of TTX‐resistant AP in ACh‐sensitive fibers and its lack of correlation with the histochemical criteria of denervation suggest the presence of a state of innervation in MMD, where the motoneuron is not able to maintain its fully trophic influence on the muscle fiber membrane.
Creatine kinase isoforms following isometric exercise
Authors: Clarkson Priscilla M. , Apple Fred S. , Byrnes William C. , McCormick Kathleen M. , Triffletti Philip 
Published: January 2005

AbstractThe present study assessed creatine kinase (CK) activity, CK MM isoforms, and muscle soreness following an exercise regimen designed to induce skeletal muscle damage. Eight college‐age subjects performed 40 maximal isometric contractions of the knee extensor muscles (10‐second contraction/20‐second rest). Serum samples and soreness ratings were taken prior to and 2, 6, 18, and 24 hours after the exercise. The CK MM1 and CK MM3 isoforms were determined by flatbed isoelectric focusing (IEF). In serum, the MM1 isoform (the pure gene product) is considered to be evidence of newly released CK from muscle, as upon entering the plasma, the CK MM1 is converted to MM2 and then MM3. A significant increase in serum CK activity was found at 6 hours and remained elevated at 24 hours. CK MM1 increased significantly at 2 hours, peaked at 6 hours, then approached baseline. Soreness did not increase significantly until 18 hours. Analysis of CK isoforms in serum can provide an earlier indicator of skeletal muscle damage than total CK or perception of soreness and may be useful in tracking the time course of skeletal muscle damage and repair.
The effect of isometric short‐term electrical stimulation on denervated muscle
Authors: Nix Wilfred A. , Dahm M. 
Published: January 2005

AbstractElectrical stimulation was applied daily for 20 minutes to denervated rabbit extensor digitorum longus muscle. One group was stimulated with short tetani, another with 1‐Hz frequency, using isometric contractions for both. Tetanic stimulation induced severe fibrosis and is harmful to denervated muscle. One Hertz stimulation retarded denervation‐induced fatigue and atrophy, as well as slowing of contraction time.
Management of end stage respiratory failure in duchenne muscular dystrophy
Authors: Bach John R. , O'Brien John , Krotenberg Robert , Alba August S. 
Published: January 2005

AbstractThere were 31 Duchenne patients placed on overnight mouth intermittent positive pressure ventilation for severe respiratory insufficiency at the average age of 19.9 years. Most patients had vital capacities less than 200 cc at their last evaluations. Of these, 23 patients are alive at the average age of 27 years and live in the community, although they are dependent on assisted ventilation 24 hours a day. There were 8 patients who died at the average age of 30 years. Although normocapnic during the day, the presence of symptomatic nocturnal hypoventilation or pCO2 over 55 mmHg documented by continuous overnight capnograph study indicates the need for introducing overnight respiratory assistance. Mouth intermittent positive pressure ventilation alone or in combination with other techniques of ventilatory assistance can prolong life while allowing optimal function, attainment of higher levels of education, and home management of patients with Duchenne muscular dystrophy.
Molecular analysis of human muscular dystrophies
Authors: Davies K. E. , Forrest S. , Smith T. , Kenwrick S. , Ball S. , Dorkins H. , Patterson M. 
Published: January 2005

AbstractThe ability to map disease loci using restriction fragment legth polymorphisms (RFLPs) identified by DNA probes has revolutionized molecular genetics. Duchenne and Becker muscular dystrophies have been shown to be localized within the same very small region of Xp21 on the human X chromosome. The mutation itself should soon be identified at the DNA level, which will permit a detailed analysis of the molecular defect at the biochemical level. Rapid progress has also been made in the study of myotonic dystrophy on chromosome 19. DNA markers closely linked to the mutant locus have been identified, making antenatal diagnosis possible in informative families. Autosomal recessive muscular dystrophies are more difficult to study, but the means to localize even these mutations is being developed. The next decade shold prove to be an exciting one for those involved in the molecular analysis and clinical management of human muscular dystrophies.
The pattern of involvement of adult‐onset acid maltase deficiency at autopsy
Authors: van der Walt Jon D. , Swash Michael , Leake Janet , Cox Elaine L. 
Published: January 2005

AbstractThe autopsy findings in a clinically and biochemically documented case of adult‐onset acid maltase deficiency presenting with limb girdle myopathy are presented. The skeletal muscles, tongue, extraocular and smooth muscles of gut and arterioles showed a vacuolar myopathy, most severely affecting proximal skeletal muscles. Muscle spindles were severely affected in all muscles. The heart showed basophilic degeneration and a vacuolar myopathy. The visceral organs and nervous system were morphologically normal. Possible mechanisms for this differential involvement of muscles and tissues are discussed.
Repeated stimulation of the dystrophic mouse neuromuscular junctions
Authors: Tremblay Jacques P. , Grégoire Laurent , Sasseville Rachelle , Belhumeur Celine 
Published: January 2005

AbstractMorphometric changes produced by repeated stimulation of the neuromuscular junctions (NMJs) have been studied by electron microscopy in 769 profiles of normal, heterozygous dystrophic, and dystrophic mice. The study indicates that in animals not stimulated but anesthetized for 40 min, there is no significant difference in the profile area between the normal, the heterozygous dystrophic, and dystrophic mice. There is also no significant difference between these three groups in the number of clear vesicles and of coated vesicles per m̈m2 of terminal. Following stimulation, the profile area of NMJs is not significantly increased in the normal and in the heterozygous dystrophic mice. However, the profile area is increased by 50% in the dystrophic animals. This is perhaps due to changes in the shape of the nerve terminal in stimulated dystrophic animals. However, the number of the clear vesicles per m̈m2 is significantly reduced to a similar extent in the three groups. These results indicate that the recycling of vesicular membrane is normal in dystrophic animals.
Frequency of bifurcated muscle fibers in hyperthrophic rat soleus muscle
Authors: Snow Mikel H. , Chortkoff Ben S. 
Published: January 2005

AbstractThe total number of bifurcated and nonbifurcated fibers were counted in rat soleus muscles induced to hypertrophy by surgical ablation of the gastrocnemius and plantaris muscles. Sham‐operated and normal soleus muscles served as controls. Every muscle fiber within the entire muscle was individually examined and counted with the aid of a dissecting microscope following a 10–12 hour nitric acid digestion of the connective tissue. The results show that the total number of muscle fibers in the hypertrophic soleus did not differ significantly from the control. The frequency of bifurcated fibers observed in the control muscles was significantly greater than has been previously reported, and their frequency in the hypertrophic muscles, although slightly increased, was not significantly different from control values. These data confirm that fiber hypertrophy is not accompanied by hyperplasia, and they further suggest that bifurcated fibers probably play an insignificant role during muscle adaptation to hypertrophy due to their very low frequency.
Adynamia episodica hereditaria with myotonia: A non‐inactivating sodium current and the effect of extracellular pH
Authors: Lehmann‐Horn Frank , Küther Gerald , Ricker Kenneth , Grafe Peter , Ballanyi Klaus , Rüdel Reinhardt 
Published: January 2005

AbstractTo study the mechanism of periodic paralysis, we investigated the properties of intact muscle fibers biopsied from a patient who had adynamia episodica hereditaria with electromyographic signs of myotonia. When the potassium concentration in the extracellular medium, [K]e, was 3.5 mmol/l, force of contraction, membrane resting potential, and intracellular sodium activity were normal, but depolarizing voltage clamp steps revealed the existence of an abnormal inward current. This current was activated at membrane potentials less negative than −80 mV, reached a maximum within 50 msec, and was not inactivated with time. The inward current was completely and reversibly blocked by tetrodotoxin, which indicates that it was carried by sodium ions. In a solution containing 9 mmol/l potassium, normal muscle would depolarize to −63 mV and yet be capable of developing full tetanic force upon stimulation. The muscle from the patient depolarized to −57 mV and became inexcitable, i.e., it was paralyzed. A contracture did not develop. Lowering of the extracellular pH did not influence the resting potential, but it effectively antagonized or prevented the paralytic effect of high [K]e by changing the inactivation characteristics of the sodium channels. Hydrochlorothiazide, which had a therapeutic effect on the patient, did not prevent paralysis in vitro. An abnormal rise of the intracellular sodium activity was recorded when the extracellular potassium concentration was raised to 10 mmol/l.
The effect of DDB on dystrophic hamsters: An in vivo and in vitro study
Authors: Shen Ding‐Guo , Araki Makoto , Higuchi Itsuro , Matsumoto Kazuko , Tamai Masaharu , Liu Keng‐Tao , Sugita Hideo 
Published: January 2005

AbstractDimethl‐4, 47′‐dimetoxy‐5, 6, 5′–6′‐dimethylenedioxybiphenyl‐2, 2′‐dicarboxylate (DDB) is a synthetic analogue of Schizandrin C, an active compound isolated from a Chinese herb, Fructus schizandrae. We administered this compound to dystrophic hamsters in vivo for 31 days. This led to a 61% reduction of the calcium content, a 86% reduction of the area of calcium deposits, and a 52% reduction of the area of necrosis of cardiac muscle. However, skeletal muscle necrosis was not significantly improved. No clear change in plasma creatine kinase (CK) was observed. In an in vitro incubation study, the rate of CK release and tetanus tension of the extensor digitorum longus muscle of dystrophic hamsters were not substantially changed by the addition of DDB. This study suggests that DDB has some effect on cardiac necrosis, and that it might be useful for treatment of the cardiac involvement in patients with muscular dystrophy or other conditions with accompaning Ca accumulation.
Effect of spinal cord TRH deficiency on lower motorneuron function in the rat
Authors: van den Bergh Peter , Kelly John J. , Adelman Lester , Munsat Theodore L. , Jackson Ivor M. D. , Lechan Ronald M. 
Published: January 2005

AbstractThyrotropin‐releasing hormone (TRH), present in high concentrations in the mammalian spinal cord, exerts excitatory effects on the alpha‐motorneuron (AMN) via axodendritic contacts. We used the neurotoxin 5,7‐dihydroxytryptamine (5,7‐DHT) to deplete TRH from the ventral horn of the spinal cord of adults rats to determine whether the tripeptide may be trophic to the AMN. The rats were studied blindly and sequentially for 11 weeks. Motor performance remained normal by clinical and electrophysiologic assessments. AMN counts were not reduced in the lumbar cord, and gastrocnemius muscle showed no evidence of denervation in treated rats. We conclude that in the adult rat chronic ventral horn TRH deficiency does not lead to AMN degeneration and is not associated with a significant alteration of AMN function.
Increased serum myosin light chain 3 level in neuromuscular diseases
Authors: Konagaya Mosaaki , Konagaya Yoko , Horikawa Hirosei , Takayanagi Tetsuya 
Published: January 2005

AbstractA radioimmunoassay for human skeletal muscle myosin light chain 3 (MLC‐3) was developed. The serum level of MLC‐3 was evaluated in 143 patients suffering from neuromuscular diseases. Increased MLC‐3 level was observed in muscular dystrophies. There were significant positive correlations between serum levels of MLC‐3 and creatin kinase (CK) in Duchenne and limb‐girdle type muscular dystrophy, but the regression lines were different. Patients with neurogenic amyotrophy, especially amyotrophic lateral sclerosis, also showed elevated MLC‐3 levels with or without high CK, and the frequency of increase in MLC‐3 was greater than that of CK. The results of the present study suggest that circulating MLC might be a useful marker for muscle breakdown not merely in myopathies but in neurogenic disorders.