bluuebunny/crossref_metadata_2025_split huggingface dataset:
The single‐fiber EMG in chronic demyelinating neuropathy
Authors: Oh Shin J. 
Published: January 2005

AbstractVarious parameters of single‐ fiber electromyography (SFEMG) were studied in 19 patients with electrophysiologically and histologically proven chronic demyelinating neuropathy. The mean duration of disease at the time of testing was four years.Motor nerve conduction in the median nerve was abnormal in all patients, whereas sensory nerve conduction was abnormal in all but one. Needle EMG in the extensor digitorum communis (EDC) muscle showed rare fibrillations and fasciculations and some abnormal motor unit potentials in most of patients. SFEMG in the EDC muscle showed an increased fiber density in seven cases (37%) and minimally abnormal jitter in 14 cases (74%). Single‐fiber action potentials were stable, whereas blocking was rare. Fiber density was significantly increased in patients with fibrillation in the conventional needle EMG.Our study showed that the SFEMG is mildly abnormal in many patients with demyelinating neuropathy and that this test is useful in detecting and quantitating axonal degeneration in demyelinating neuropathy.
31P‐NMR spectroscopy: The metabolic profile of malignant hyperpyrexic porcine skeletal muscle
Authors: Foster Paul S. , Hopkinson Kenneth , Denborough Michael 
Published: January 2005

Abstract31Phosphorus‐NMR spectroscopy may have the potential to help in the noninvasive diagnosis of malignant hyperpyrexia (MH). Changes in the phosphate‐metabolite profile of MH‐susceptible (MHS) skeletal muscle occur more readily under conditions of anoxia than in control muscle. Induction of anoxia caused a rapid fall in intracellular phosphocreatine, an elevation of inorganic phosphate, and finally a diminution of ATP in MHS muscle. The onset of metabolic change was slower in control tissue. Increased oxygen consumption may occur in anoxic MHS muscle, which leads to accelerated glycolysis and a rapid fall in the intracellular high‐energy phosphates. In MHS muscle an abnormality may exist in carbohydrate metabolism linked with poor resynthesis of the high‐energy phosphates, which may be precipitated under anaerobic conditions. Accelerated muscle metabolism is also observed in the presence of 2 mM caffeine and 3% halothane in MHS muscle. Changes in the concentrations of metabolites could be mapped noninvasively under anoxic conditions using topical 31P‐NMR.
Increased resistance of the collagen in avian dystrophic muscle to collagenolytic attack: Evidence for increased crosslinking
Authors: Feit Howard , Kawai Masataka , Mostafapour A. Shanaz 
Published: January 2005

AbstractFibrous collagen from normal (line 412) and dystrophic (line 413) chicken pectoral muscles was examined for susceptibility to bacterial collagenase by a pH‐stat titration method to assess the kinetics of peptide bond hydrolysis. These experiments showed that there was a profound difference in the kinetics of hydrolysis using fibrous collagen purified from normal and dystrophic muscle. Although normal collagen was readily hydrolyzed by the collagenase, dystrophic collagen was not hydrolyzed in the presence of 200 μM Ca and was hydrolyzed slowly in the presence of 5 mM Ca. At this high Ca concentration, the Km for collagenase was six times higher in dystrophic collagen than in normal, whereas the maximum reaction rate (Vmax) remained the same. After CNBr digestion, peptides from both sources were readily hydrolyzed by collagenase in the presence of 200 μM Ca, and there was no noticeble difference in the reaction kinetics. The above results were not modified whether the chicken was sacrificed on day 4 or day 98 posthatching, and the insusceptibility to collagenase preceded the clinical manifestations of dystrophy. The structure of both fibrous and CNBr‐treated collagen from normal and dystrophic muscle was compared. One and two‐dimensional gel electrophoreses showed identical peptide maps. Gel filtration of CNBr peptides showed in the excluded volume the presence of twice as much high‐molecular‐weight (presumably crosslinked) peptides from dystrophic collagen compared with normal. We conclude that the intermolecular crosslinks are more extensively formed in dystrophic collagen and that this increased crosslinking results in the increased resistance of the dystrphic collagen to collagenase.
Small nerve fiber dysfunction in diabetic neuropathy
Authors: Navarro Xavier , Kennedy William R. , Fries Timothy J. 
Published: January 2005

AbstractSensory and autonomic small nerve fiber function was studied in 142 type I diabetics and 45 control subjects. Thermal sensitivity (TS), hot pain sensitivity, and the activity of sweat glands (SGs) were quantitated on the dorsum of the hand and the foot. TS was abnormal in 86% of patients in the foot and 66% in the hand. TS was more sensitive than the hot pain threshold, the number of pilocarpine activated SGs, or the amount of sweat secreted, all of which were abnormal in about 50% of patients for the foot and less than 25% in the hand. Thermal and sweating tests correlated significantly with the scores of abnormal temperature and pinprick sensation obtained by physical examination but not with the duration of the diabetes. TS was also correlated with motor and sensory nerve conduction parameters, but SG number was not. The results indicate that diabetic neuropathy has a variable presentation in different types of nerve fibers.
Effect of motor unit firing pattern on twitches obtained by spike‐triggered averaging
Authors: Nordstrom Michael A. , Miles Timothy S. , Veale John L. 
Published: January 2005

AbstractThe spike‐triggered averaging technique (STA) was used to determine the twitch profile of single motor units in human masseter during a voluntary isometric contraction. The effect of the immediate firing pattern of the unit on the twitch was assessed with a computer program which scanned the unit discharge records and selected valid trigger spikes for the averager on the basis of the interspike intervals preceding and following the trigger spike. Successive averages from the same data using different interval parameters revealed progressively more fusion of twitches as the instantaneous firing rate increased. When the data were averaged with interval parameters similar to those used in earlier studies, some fusion of the twitch profile was also evident. It is therefore likely that the degree of fusion of human motor unit twitches obtained by STA has been underestimated in the past. It is further concluded that masseter motor units are sufficiently fast‐contracting to allow a relatively unfused twitch profile to be obtained with STA, provided trigger spikes are subjected to appropriate rate control.
Optimal stimulus duration for the H reflex
Authors: Panizza M. , Nilsson J. , Hallett M. 
Published: January 2005

AbstractAuthorities advocate different stimulus durations to produce an H reflex. In order to find the optimal stimulus duration for recording H reflexes, the recruitment curves for H reflexes and M responses were studied in 10 healthy subjects. The H reflex was recorded in the upper and lower extremities, and the durations of the electrical stimulus used ranged from 0.1 to 3 msec. The amplitude of the H reflex and the relation between the H reflex and M response changed with stimulus duration. H reflexes are brought out to advantage using a stimulus duration between 0.5 and 1 msec.
Maturation of transmission in reinnervated mouse soleus muscle
Authors: Badke Andreas , Irintchev Andrey P. , Wernig Anton 
Published: January 2005

AbstractAfter the tibial nerve of the mouse was cut unilaterally and immediately resutured, reinnervation of soleus muscle proceeded rapidly and muscle isometric contraction characteristics reached normal levels within 2 months. In contrast, synaptic transmission remained immature since resistance to presynaptic (magnesium) or postsynaptic (curare) blocking solutions remained reduced. Results suggest that release probability and transmitter stores were smaller than normal. To study the effect of training, animals were allowed to run in wheels. Running caused a delay in reinnervation at 18–20 days, which was, however, abolished by 4 weeks. On the other hand, exercise counteracted development of denervation atrophy. The safety margin of transmission in runners was higher than in nonrunners at 4 weeks, indicating enhanced maturation, but was lower at 2 months of reinnervation. These results suggest that recovery of muscle precedes maturation of synaptic transmission.
Protease nexin I, a serpin, inhibits plasminogen‐dependent degradation of muscle extracellular matrix
Authors: Rao J. S. , Kahler C. B. , Baker J. B. , Festoff B. W. 
Published: January 2005

AbstractClonal, fusing, mouse skeletal muscle cells (C2) were grown to the myotube stage (90% confluence) before they were subjected to isotope containing serum‐free media (3H‐proline or 35S‐methionine). C2 myotubes secrete and organize a biosynthetically labeled matrix which adheres to the plastic after removal of myotubes with detergent and ammonium hydroxide. When these homotypic‐labeled myotube matrices were incubated with myo blast‐conditioned media containing high specific activity urokinase‐type plasminogen activator, slow, but clearly detectable, release of label occurred. However, degradation of matrix, with solubilization of label, was accelerated sixfold by addition of human plasminogen to diluted myoblast conditioned media. If protease nexin I, a cellular serine protease inhibitor purified from human fibroblast‐conditioned media, was added (0.2 μg/ml) with plasminogen, inhibition of matrix hydrolysis by 52% occurred. Higher concentrations (0.8 μg/ml or above) of protease nexin I completely inhibited the degradation of extracellular matrix components. A similar protease inhibitor was purified from C2 myotube‐conditioned media, and this molecule also inhibited the plasminogen‐dependent release of extracellular matrix. We propose that protease nexin I inhibits the destruction of myotube matrix by inactivating the plasmin/plasminogen activation system and may be the physiologic regulator of this system during muscle development in vivo.
Altered mechanisms of muscular force generation in lower motor neuron disease
Authors: Reiners Karlheinz , Herdmann Jörg , Freund Hans‐Joachim 
Published: January 2005

AbstractRecruitment and firing rate modulation (FRM) of single motor units (MUs) were evaluated in the first dorsal interosseus muscle in patients with chronic lower motor neuron disorders of primarily neuroaxonal or demyelinating pathology. Residual muscle function was estimated by maximal voluntary force, twitch tension, and compound muscle action potential. The recruitment range of MUs was expanded toward higher relative force levels in all patients. Changes in firing rates per unit force increment were larger in patients with more pronounced muscle atrophy. When this effect was accounted for by calculating FRM for increments of 10% of residual maximal force, patients with subnormal motor nerve conduction velocities showed selective impairment of rate modulation. This was not due to intermittent conduction failure. We conclude that the two force‐generating mechanisms, recruitment and FRM, show unspecific compensatory changes related to the loss of MUs and also alterations that are specifically related to the neuroaxonal or demyelinating nature of the neuropathy.
Mature 98,000‐dalton acid α‐glucosidase is deficient in Japanese quails with acid maltase deficiency
Authors: Suhara Yoshihiro , Ishiura Shoichi , Tsukahara Toshifumi , Sugita Hideo 
Published: January 2005

AbstractWe compared acid α‐glucosidase of acid maltase‐deficient Japanese quails, an animal model of human late‐onset glycogenosis type II, with that of normal controls. Antibody produced in a rabbit against acid α‐glucosidase purified from chicken pectoral muscle cross‐reacted with that of Japanese quails. The presence of a 110K and 98K form of acid α‐glucosidase was confirmed in normal controls by immunoblotting. However the 98K form was absent in the affected quails. Subcellular distribution studies demonstrated that the 98K form, but not the 110K form, was localized in the lysosomes. This suggests that the 110K form is a precursor of the mature 98K form of acid α‐glucosidase. In the affected quails, the 11OK precursor is synthesized, but maturation to the 98K form does not occur or may be extremely deficient.
Slow recovery of central axons in acrylamide neuropathy
Authors: Kaji Ruyji , Liu Yan , Duckett Serge , Sumner Austin J. 
Published: January 2005

AbstractTo study the differential vulnerability of central versus peripheral axons, we observed serial changes in conduction over comparable segments of central and peripheral axons of the primary sensory neuron in 17 rats with acrylamide neuropathy using somatosensory evoked potentials. Central conduction abnormalities persisted even after peripheral conduction and clinical abnormalities had recovered. Morphometric studies showed prompt restoration of the largest‐diameter fibers in the peripheral nerve after clinical recovery but persistent or even more severe loss of large‐ and medium‐sized fibers in the cervical gracile tract. This finding suggests that recovery from central‐peripheral distal axonopathy begins in the largest peripheral axons, perhaps even at the expense of central axons, and that clinical recovery can occur at a time when central conduction remains abnormal. The selective central axonopathy found in certain chronic degenerative disorders may be a consequence of this slow central recovery process associated with chronic or intermittent metabolic derangements.
Magnetic resonance imaging of muscle injury and atrophy in glycolytic myopathies
Authors: Fleckenstein James L. , Peshock Ronald M. , Lewis Steven F. , Haller Ronald G. 
Published: January 2005

AbstractExertional muscle pain, contractures, recurrent rhabdomyolysis, and pigmenturia are common in certain muscle glycolytic disorders. However, the frequency, distribution, and long‐term significance of these findings are poorly understood. First we performed magnetic resonance imaging (MRI) of the extremities as a screening test for the detection of muscle abnormalities incurred in activities of daily living in four patients with myophosphory‐lase deficiency (MPD) and three with muscle phosphofructokinase deficiency (PFKD). MRI findings of abnormal muscles detected upon screening were next compared with changes observed in a prospective study of muscle contractures involving the forearms of four of the patients (two MPD, two PFKD). Screening revealed abnormalities of proximal thigh muscles in three of seven patients, in two of whom (one MPD, one PFKD) a recent history of exertional myalgia coincided with increases in T1 and T2 estimates of isolated thigh muscles. In the third patient (PFKD), focal atrophy of the adductor magnus was present bilaterally. In prospective studies, focal areas of prolonged T1 and T2 appeared in the flexor digitorum superficialis in all four cases and in the flexor digitorum profundus in two cases. Serial imaging suggested that the onset of MRI abnormalities begins within 24 hours of contracture and persists for at least several days and possibly for much longer, with complete recovery apparently the rule. These cases suggests a high prevalence of focal muscle abnormalities in patients with glycolytic myopathies and show the potential of MRI to detect them.
Conduction studies in peripheral cat nerve using implanted electrodes: III. The effects of prolonged constriction on the distal nerve segment
Authors: Krarup Christian , Loeb Gerald E. , Pezeshkpour Gholam H. 
Published: January 2005

AbstractElectrophysiological properties were monitored in detail in chronically constricted peripheral nerves by implanted, multicontact nerve cuff electrodes and correlated with morphometric histology in selected cases. The physiological and histological responses in nerve to a range of constricting cuffs of standard sizes were readily graded. The initial response to any significant constriction was a transient, focal conduction slowing or block at the constriction, followed by more protracted distal effects; the latter ranged from loss of excitability consistent with “dying‐back” degeneration to reductions in conduction velocity consistent with histologically observed atrophy. Smaller myelinated fibers tended to have similar but less pronounced changes than larger diameter fibers. Recordings from ventral and dorsal roots showed that distal degeneration was more pronounced in motor than in sensory fibers of similar caliber. Electronmicroscopical measurements showed that basal laminas were relatively preserved around even the most atrophic and demyelinated axons. Perimeter measurements of the basal lamina could be used to estimate the diameter of the original nerve fiber.
Denervated single myofibers: Neurite interactions and synaptic molecules
Authors: Jay Jeanne C. , Barald Kate F. 
Published: January 2005

AbstractAs a first step in defining the molecular cues that may be important for reinnervation of long‐term denervated muscle, single adult rat muscle fibers that had been denervated from 2 to 24 months in vivo were maintained in culture for 5 days. Embryonic ventral spinal cord explants were added to some of these cultures. Interactions of neurites with individual short‐term (up to 5 months) and long‐term (17–24 months) denervated muscle fibers were compared with neurite interactions in cultures of young adult muscle fibers (from 3 to 5‐month‐old rats) or aged muscle fibers (from 17 to 26‐month‐old rats). We found the following. (1) Three molecules that are found at the neuromscular junction (NMJ)—acetylcholinesterase (AChE), acetylcholine receptors (AChRs), and gelasmin (an acetylcholine receptor clustering factor that is found enriched at NMJ of adult muscle)—were reduced with increasing periods of denervation but not with aging. (2) The number of neurite contacts at junctional regions of muscle fibers that were formed and maintained on cultured muscle fibers depended on denervation time of the muscle in vivo; very few contacts were made or maintained on long‐term denervated fibers. (3) Gelasmin, but not AChE or AChRs, was found at points of neurite contact on all muscle fibers examined, raising the possibility that it may serve as a cue for reinnervation and that its loss from longterm denervated muscle may be, at least in part, involved in the failure of neurite contacts to be made or maintained in culture and possibly in vivo.
Automatic analysis of heart rate variation: I. Method and reference values in healthy controls
Authors: Stålberg Erik V. , Nogués Martin A. 
Published: January 2005

AbstractMany patients referred to an electrophysiological laboratory may have autonomic dysfunction. Some parasympathotic tosts are based on the assessment of heart rate variation induced by breathing, Valsalva maneuver, and standing. We have developed fast and practical computer‐based methods to analyze heart rate variation using standard EMG equipment and a personal computer. For quantitative description we have evaluated different algorithms, both earlier described and new ones. Findings in patients with diabetes have been compared with those obtained from healthy subjects in order to determine the diagnostic utility of the various algorithms. The optimal algorithm has been chosen by this and other criteria, and a reference database from healthy subjects has been developed.
Analysis of dystrophin in fast‐ and slow‐twitch skeletal muscles from mdx and dy2J mice at different ages
Authors: Anderson J. E. , Kao L. , Bressler B. H. , Gruesnstein E. 
Published: January 2005

AbstractMuscles from mdx, control, and dy2J/dy2J mice at different ages were analyzed for dystrophin in an attempt to relate the chronology of the protein expression with the final phenotypes in regenerated, normal, and dystrophic muscle, respectively. Immunostaining and gold staining of electrophoresis gels were carried out in the investigation. At 5, 25, and 219 days of age, control muscles exhibited dystrophin bands in both the fast‐twitch extensor digitorum longus (EDL) and the slow‐twitch soleus (SOL) muscles. Muscles from the mdx mice at comparable age (8,28, and 217 days)never exhibited bands for dystropin, although titin, nesbulin, myosin, and other protein bands were present at intensities comparable to those in control muscles. The dystrophin band was present in both the EDL and SOL from dy2J/dy2J dystrophic mice. As indicated by the present study, the dystrophin dificiency from mdx tissue is not transient. This suggests that dystrophin is not necessary for the success of mdx muscle regeneration.
Sonographic imaging of muscle contraction and fasciculations: A correlation with electromyography
Authors: Walker Francis O. , Donofrio Peter D. , Harpold Gary J. , Ferrell William G. 
Published: January 2005

AbstractPrecise quantitation of fasciculations with EMG is difficult because of their random location and discharge frequency in muscle. We studied the clinical value of real‐time ultrasound in the study of normal voluntary muscle contraction and in the identification of fasciculations in 22 patients. Sonography effectively imaged fasciculations, demonstrating them in both resting and actively contracting extremity muscles and in less accessible muscles such as the tongue. In two instances ultrasound identified fasciculations not apparent on EMG. Analysis of the video images generated quantitative data of fasciculation duration (averaging 500 msec), size, and location and provided unique insight into the process of normal muscle contraction and motor unit physiology.
Spectrum of patients with EMG features of polyradiculopathy without neuropathy
Authors: McGonagle Timothy K. , Levine Steven R. , Donofrio Peter D. , Albers James W. 
Published: January 2005

AbstractWe reviewed the medical records of 233 patients having electrodiagnostic evidence of polyradiculopathy. Patients with polyneuropathy or incomplete diagnostic evaluation were excluded. A clinical diagnosis was secured in 92 of the 118 remaining patients. Patients were separated into three groups based upon the anatomic location of root involvement: extradural (55), intradural‐extraaxial (23), and intraaxial (14). Collectively, patients with intradural‐extraaxial disorders had earlier disease onset, shorter symptom duration, and a higher disability score compared with the intraaxial or extradural groups. Pain was an initial complaint in 50 of 55 patients with extradural lesions, 20 of 23 with intradural‐extraaxial disease, but only in 4 of 14 with intraaxial involvement. CSF abnormalities and reduced compound muscle action potential amplitudes were more common in the intradural‐extraaxial group. We conclude that the anatomic localization of root involvement in patients with polyradiculopathy can be suggested by a combination of clinical, laboratory, and electrodiagnostic features.
Phosphorylase kinase isozymes and phosphorylase in denervated skeletal muscles
Authors: Lawrence John C. , Smith Roderic L. 
Published: January 2005

AbstractThe effects of motor denervation on levels of phosphorylase kinase isozymes and phosphorylase were investigated in rat epitrochlearis, hemidiaphragm, and soleus muscles. Amounts of the proteins were measured after quantitative immunoprecipitation and found to be decreased by as much as 70% 2 weeks after denervation. Unexpectedly, denervation had little, if any, effect on the relative proportions of the two phosphorylase kinase isozymes. Phosphorylase and phosphorylase kinase were decreased by essentially the same extent after denervation, and the effects of denervation were comparable in all three muscles. The decreases in these enzymes explain, at least in part, the marked alterations in glycogen metabolism that occur after motor denervation.