bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased [32P]‐phosphorylation of tryptic peptides of erythrocyte spectrin in duchenne muscular dystrophy
Authors: Mabry Michael E. , Roses Allen D. 
Published: January 2005

AbstractIncreased [32P]‐incorporation in tryptic peptides of the erythrocyte membrane protein spectrin Band 2 in Duchenne muscular dystrophy (DMD) was studied in a consecutive series of 10 matched DMD/control pairs. Spectrin was [32P]‐phosphorylated by cyclic AMP‐independent endogenous membrane protein kinase in the presence of [γ‐32P]ATP. [32P]‐labeled spectrin was isolated, purified, and subjected to tryptic cleavage with excess trypsin. The resulting peptides were separated on a high‐resolution 5%/15% stacking SDS‐polyacrylamide gel electrophoresis system. Liquid scintillation counting was performed on sequential slices of unstained gels. A broad [32P]‐labeled band containing a number of [32P]‐polypeptides was found to be more highly [32P]‐phosphorylated in DMD patients than in their matched controls. This band migrated with an apparent molecular mass of 4.8–5.2 kilodaltons and contained approximately 55% of total [32P] radioactivity covalently bound to spectrin peptides. These data demonstrated an increased [32P]‐phosphorylation of an identifiable tryptic peptide fraction in DMD that is consistent with previous reports of increased spectrin Band 2 [32P]‐phosphrylation in DMD.
Nerve conduction velocity varies inversely with height
Authors: Campbell William W. , Ward L. Charles , Swift Thomas R. 
Published: January 2005

AbstractEven when all known factors affecting the determination of nerve conduction velocity are controlled, large individual variations persist. In 40 normal controls, we found that peroneal and sural conduction velocities varied inversely with body height (P < 0.001). This height effect is not due to temperature differences, and it explains almost 50% of the intersubject variability in conduction velocity. We hypothesize that the height influence reflects abrupt, rather than gradual, tapering of axons distally. This mode of tapering may help explain the decrements in conduction velocity from proximal to distal nerve segments and from upper to lower extremities, which have long been observed in clinical electromyography. Clinical recognition of this height effect is important lest one label as abnormal an individual with mildly slowed peripheral nerve conduction velocity solely related to large stature.
Increase of muscle mitochondrial content with age in murine muscular dystrophy
Authors: Silverman Harold , Atwood Harold L. 
Published: January 2005

AbstractComparison of morphological features of gastrocnemius muscle fibers in normal and dystrophic (dy2J) mice during development was undertaken to determine the time course of increased oxidative capacity in dystrophic fibers. Measurements of mitochondrial volume percent and of Z‐line width were made in superficial fast‐twitch fibers using electron microscopy and stereological techniques. Dystrophic fibers develop a progressively higher mitochondrial volume percent than normal fibers after 1 month of age. Z‐line width is positively correlated with mitochondrial volume percent. The results support the hypothesis that progressive changes in muscle fiber properties result from abnormal neural activity (pseudomyotonia) in dystrophic animals.
Stereometric estimation of the area of the freeze‐fractured membrane
Authors: Engel Andrew G. , Fukunaga Hidetoshi , Osame Mitsuhiro 
Published: January 2005

AbstractStereo‐pair micrographs of freeze‐fracture replicas taken at +6 and −6 degrees and enlarged 55,000 diameters were precisely aligned on a digitizing pad linked to a plotter and programmable calculator. A point grid spaced at 0.23 μm was placed over the left photo‐pair. Under stereoscopic observation, matching points were placed by hand on the right photo‐pair for every point in the applied grid that fell over the membrane surface of interest in the left photo‐pair. The x, y coordinates of every point in the two photos were read with the digitizer. These data allowed the calculation of the X, Y, Z coordinates of all points in the untilted object space, 3‐D reconstruction of the analyzed surface, and estimation of the membrane surface area.
Evidence for a motor nerve growth factor
Authors: Slack J. R. , Hopkins W. G. , Pockett S. 
Published: January 2005

AbstractWe review the evidence that a motor nerve growth factor released from muscle has wide ranging effects on the development and maintenance of muscle innervation. The actions of this putative factor on motor neurons are analogous to the actions of the well known nerve growth factor (NGF) on sympathetic and sensory neurons.
Effects of insulin on protein synthesis in muscles from normal and dystrophic mice
Authors: Ballard F. John , Nield Michelle K. , Tomas Frank M. 
Published: January 2005

AbstractProtein synthesis in soleus and extensor digitorum logus (EDL) muscles was measured in vitro to test the hypothesis that the lack of muscle protein accumulation in dystrophic conditions could be caused by a reduced sensitivity to insulin. We demonstrate that physiological insulin concentrations stimulate protein synthesis in soleus muscles from normal mice but not from muscles obtained from dystrophic (dy) animals. The difference is lost at very high insulin concentrations (1 μM) and could not be shown at any concentration with EDL muscles. These results, together with the reported reduced inhibitory effect of insulin on protein synthesis in dystrophic hamsters and on protein breakdown in dystrophic mice, suggest, that protein metabolism in certain muscles from dystrophic animals may be less responsive to the anabolic effects of insulin.
The CO‐dispersion index for the measurement of fiber type distribution patterns
Authors: Lester James M. , Silber Dennis I. , Cohen Michael H. , Hirsch Robert P. , Bradley Walter G. , Brenner John F. 
Published: January 2005

AbstractThere is a need for a practical and statistically manageable quantitative index of fiber type co‐dispersion in skeletal muscle to allow investigation of the distribution of motor units in normal muscle and their rearrangement in pathological states. A new measure for this purpose, the Co‐Dispersion Index (CDI), is introduced. This measure is based on contingency table analysis of nearest‐neighbor relationships between muscle fibers. The CDI has a continuous range of values from −1 to +1, in which larger negative values indicate a greater tendency toward regular intermixing of fibers of different types, and larger positive values a greater segregation of fiber types. CDI evaluation overcomes the limitations of previously published quantitative methods for codispersion measurement and is well correlated with subjective human estimates of fiber type grouping.
Axonal regeneration in wobbler motor neuron disease: Quantitative histologic and axonal transport studies
Authors: Mitsumoto Hiroshi 
Published: January 2005

AbstractThe regenerative capacity of the cervical anterior horn cells was studied at 4 and 7 days following forelimb nerve crush in 19 Wobbler mice and 18 normal littermates. Quantitative histologic and radiolabeled axonal transport techniques showed that the axotomized neurons of the wobbler mouse supported active axonal elongation. However, the average axon outgrowth rate determined by histologic technique was diminished by 25% and the fastest axon outgrowth rate determined by axonal transport technique was also decreased by 30% in wobbler mice as compared to controls. The distal labeled peak was absent in the wobbler mouse at 7 days, indicating that the regeneration rate of individual axons was widely dispersed. Histologic studies also showed that the wobbler axons grew slowly. This study suggests that axonal regeneration does occur in motor neurons undergoing a primary neuronopathy. However, the regenerative capacity was reduced and this appears to reflect an impairment of functional integrity in the anterior horn cells of the wobbler mouse.
Ligature‐induced injury in peripheral nerve: Electrophysiological observations on changes in action potential characteristics following blockade of potassium conductance
Authors: Waxman Stephen G. , Kocsis Jeffery D. , Eng Douglas L. 
Published: January 2005

AbstractThe effects of the potassium channel blocking agent 4‐aminopyridine (4‐AP) on action potential properties were studied in chronically injured rat sciatic nerves. In normal, mature myelinated fibers, application of 4‐AP does not lead to any significant change in action potential waveform or firing pattern in response to single stimuli. In contrast, application of 4‐AP to nerves injured by the placement of loose ligatures results in the appearance of late rippled components in the compound action potential. This alteration in waveform is present at the injury site, but not at nerve segments proximal or distal to this region. Paired stimulation experiments demonstrate that this oscillation of the whole nerve resporse reflects repetitive firing in response to single stimuli following application of 4‐AP. Intra‐axonal recording following 4‐AP application demonstrates bursts of action potentials, with several spikes of reduced amplitude arising from a depolarizing potential following the initial spike. Refractory period for the late spike is grater than that of the primary action potential. These results demonstrate that potassium channels are present and functional in chronically injured nerves, where blockage of these channels results in repetitive firing in response to single stimuli.
Measurement of junctional acetylcholine receptors in myasthenia gravis: Clinical correlates
Authors: Pestronk Alan , Drachman Daniel B. , Self Steven G. 
Published: January 2005

AbstractWe measured the number of acetylcholine receptors (AChRs) at neuromuscular junctions (NMJs) in motor point biopsies from 76 patients with myasthenia gravis (MG) and 49 control subjects, using an α‐bungarotoxin binding technique. The mean number of AChRs/NMJ was significantly lower (P < 0.001) in muscles of MG patients (deltoid 0.7 ± 0.1 × 107) than in controls (2.1 × 0.2 × 107). None of the control muscles had fewer than 0.9 × 107 AChRs/NMJ, and 75% of MG muscles were below that level. Conversely, 88% of controls had 1.5% × 107 or more AChRs/NMJ, whereas only one of the MG muscles (2.5%) was at or above that level. The reduction of AChRs correlated approximately with the clinical severity of weakness (P < 0.02). Patients with focal weakness had reduced numbers of AChRs/NMJ in clinically strong muscles. The only other condition in which junctional AChRs were reduced was polyositis. These findings in a large sample of patients confirm the reduction of junctional AChRs in MG, the relationship of available junctional AChRs to clinical manifestations, and the systemic nature of the disorder even in cases with focal weakness. Measurement of AChRs can be useful diagnostically in situations where other tests are inconclusive.
Plasma exchange in chronic inflammatory demyelinating polyradiculoneuropathy
Authors: Donofrio Peter D. , Tandan Rup , Albers James W. 
Published: January 2005

AbstractEleven consecutive patients with progressive chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) underwent plasma exchange. Eight patients were previously unresponsive to prednisone, two were started on prednisone with plasma exchange, and one did not receive corticosteroids. Electrodiagnostic studies revealed evidence of an acquired demyelinating polyradiculoneuropathy with varying degrees of axonal degeneration. Neurologic impairment was monitored using conventional functional status index. Five patients demonstrated substantial clinical improvement, beginning 2 days to 3 weeks after initiating plasma exchange. Two additional patients improved following a second course of plasma exchange, and four patients demonstrated minimal or no change. Comparison of responding and onresponding patients showed no differences related to the presence or absence of antecedent illness, duration of disease, duration of maximum weakness, or severity of impairment prior to plasma exchange. Responders had significantly prolonged F‐response and motor distal latencies compared to nonresponders. Results in this unselected, consecutive patient trial suggest a temporal relationship between plasma exchange and clinical improvement in some patients with progressive CIDP.
Peripheral nerve in type III glycogenosis: Selective involvement of unmyelinated fiber schwann cells
Authors: Powell Henry C. , Haas Richard , Hall Christopher L. , Wolff Jon A. , Nyhan William , Brown Barbara I. 
Published: January 2005

AbstractElectron microscopy of intramuscular nerves in biopsy material from a child with glycogenosis type III showed massive glycogen accumulation in the Schwann cells of unmyelinated nerve fibers. Other cells, including Schwann cells of myelinated fibers, perineurial cells, endoneurial fibroblasts, endothelial cells, and pericytes, were not similarly affected.
The ischemic exercise test in normal adults and in patients with weakness and cramps
Authors: Coleman Rosalind A. , Stajich Jeffrey M. , Pact Virginia W. , Pericak‐Vance Margaret A. 
Published: January 2005

AbstractData from 23 normal men and women were used to derive 95% confidence limits for maximum changes in ammonia and lactate values following ischemic forearm exercise. Most normal subjects raised serum lactate and ammonia concentrations more than 20 mg/dl and 100 μg/dl, respectively over baseline values. No significant correlations were found among age, sex, duration of exercise, or estimate of work performed and the maximum ammonia and lactate values achieved. When 70 patients with complaints of weakness, fatigue, or cramps were evaluated, the ischemic exercise test identified 5 patients who proved to have defects in glycolysis or purine metabolism. The test also distinguished those patients with type III glycogen storage disease who lacked debrancher enzyme activity in muscle.
Antimuscle and antiacetylcholine receptor antibodies in myasthenia gravis
Authors: Penn Audrey S. , Schotland Donald L. , Lamme M. S. Stella 
Published: January 2005

AbstractThe sera of 134 patients were examined for antimuscle antibodies by immunofluorescence (IF). These derived from 77 myasthenics, 30 myasthenics with thymoma, 6 patients with thymoma and no clinical evidence of myasthenia, and 21 patients with other autoimmune or neuromuscular diseases. Three separate patterns of antimuscle antibodies could be identified in the myasthenic sera by examination of the relaxed glycerinated myofibrils by both IF and phase‐contrast optics: A‐band (9 with thymoma, 1 without), I‐band (11 with thymoma, 17 without), and a mixed A plus I pattern (5 with thymoma, 3 without). Seventy‐seven myasthenic serum samples (24 with thymoma, 53 without) were available for evaluation of antibodies to acetylcholine receptor (antiAChR) by radioimmunoassay. Ninety‐one percent reacted with crude human receptor extract and 80% with receptor extracted from denervated rat muscle. There was no correlation between the titers of anti‐AChR and the presence or staining patterns of antimuscle antibodies, but patients without anti‐AChR did not have antimuscle antibodies. Myasthenics with thymoma had the highest prevalence of anti‐AChR (237sol;24) and of antimuscle antibodies (257sol;30), and 15 of the 20 positives stained A‐bands alone or with I‐band, as compared to 4 of 21 positive reactions in those without tumor. Immunoabsorption, which removed or significantly reduced anti‐AChR, did not alter antimuscle reactivity. The discrepancies between anti‐AChR levels and the presence and types of antimuscle antibodies suggest that these are independent autoantibodies. Current theories of immunopathogenesis implicate altered thymic antigens or a major breakdown in immune regulation, either of which could explain their production.
Comparison of distal sympathetic with vagal function in diabetic neuropathy
Authors: Low Phillip A. , Zimmerman Bruce R. , Dyck Peter J. 
Published: January 2005

AbstractWe measured distal sympathetic and vagal function in 73 consecutive patients with diabetic neuropathy seen at the Mayo Autonomic Reflex Laboratory. Postganglionic sympathetic failure measured proximally within the foot occurred as commonly as vagal failure (58% and 55%, respectively) and‐occurred much more frequently than did orthostatic hypotension (26%). Either vagal or distal sympathetic abnormalities occurred in isolation in about one in six patients with diabetic neuropathy. We conclude that distal sympathetic failure and vagal failure occur with equal frequency when sensitive and quantitative recording methods are used and that it is advantageous to test both systems, as only one may be involved in some patients.
Lack of cold sensitivity in hyperkalemic periodic paralysis
Authors: Subramony S. H. , Wee Abelardo S. , Mishra Shri K. 
Published: January 2005

AbstractThe nosologic distinction between paramyotonia congenita and hyperkalemic periodic paralysis is somewhat blurred. Muscle membrane inexcitability induced by cooling seems to be characteristics of paramyotonia congenita. The effect of cooling on the maximal compound muscle action potential (CMAP) in patients with paramyotonia congenita was compared to that in patients with hyperkalemic periodic paralysis. Diminution in CMAP amplitude and area, which was observed in paramyotonia congenita, did not occur in hyperkalemic periodic paralysis. We suggest that this effect of cooling on the CMAP can be utilized in the differentiation of these two syndromes.
Humoral factors in peripheral nerve disease
Authors: Toyka Klaus V. , Heininger Kurt 
Published: January 2005

AbstractHumoral factors including soluble substances transported by the blood stream and factors released at a target tissue may play a role in diseases of the peripheral nervous system. Various criteria have to be met in order to accept humoral factors as potential pathogens. In this review these general criteria are discussed, including the evidence provided by plasma exchange therapy, demonstration of circulating or deposited autoantibodies and immune complexes, identification of antigenic molecules, animal model diseases, passive transfer experiments, and the demonstration of circulating factors not directed against specific targets. In acute, chronic, and chronic relapsing inflammatory polyneuropathies, and in the polyneuropathy associated with monoclonal gammopathy, humoral factors have been identified, but their exact pathogenic role is not fully understood. In the Lambert‐Eaton myasthenic syndrome, a disorder of the motor nerve terminal, pathogenic IgG‐antibodies have been demonstrated by passive transfer experiments. In the experimental animal model disorders, the acute and chronic variants of experimental allergic neuritis, humoral factors including antibodies to myelin basic proteins and galactocerebroside and nonspecific humoral factors may all contribute to the ultimate peripheral nerve damage, but their relative importance in relation to cell‐mediated immune reactions is not yet clear.
Sensory potentials and sural nerve biopsy: A Model evaluation
Authors: Schoonhoven Ruurd , Schellens Ronald L. L. A. , Stegeman Dick F. , Gabreëls‐Festen Anneke A. W. M. 
Published: January 2005

AbstractCompound action potentials (CAPs) were recorded from the sural nerve prior to nerve biopsy in patients with various kinds of polyneuropathy. A previously developed volume conductor model for the CAP is applied to analyze the recorded CAPs in close relation with the morphological findings in the biopsy. First, the fiber diameter histograms obtained from the biopsy are used to simulate CAPs by assuming a linear relation between fiber diameter and propagation velocity. It is concluded that the simulated CAPs deviate systematically from the recorded CAPs. Next, the assumption of a linear diameter‐velocity relation is left, and the assumed fiber velocity distribution is adapted to obtain optimal model reconstructions of the recorded CAPs. It is concluded that the model is capable of reconstructing the recorded CAPs, including slow components and small polyphasic potentials in the case of severe fiber loss. It is demonstrated how the diameter histogram and the optimal velocity distribution can be combined to an empirical estimate of the diameter‐velocity relation.
The muscle fiber conduction velocity and power spectra in familial hypokalemic periodic paralysis
Authors: Zwarts Machiel J. , van Weerden Tiemen W. , Links Thera P. , Haenen Harry T. M. , Oosterhuis Hans J. G. 
Published: January 2005

AbstractSurface EMG has been used to determine the average muscle fiber conduction velocity (MFCV) and power spectra of the m. biceps of 10 patients and 15 asymptomatic offspring of a large kinship with familial hypokalemic periodic paralysis (HOPP). The MFCV of the patients was 3.37 ± 0.35 m/sec (mean ± SD, n = 9), the median frequency (Fmed) of the power spectra was 55.0 ± 5.8 Hz (mean ± SD, n = 9), both values are significantly (P0.001, Student's t‐test) lower than control values: MFCV = 4.55 ± 0.33 m/sec; Fmed = 88.6 ± 15.5 Hz (mean ± SD). In 6 of the 15 asymptomatic relatives, the surface EMG results were also abnormal. It is concluded that the MFCV is reduced in familial HOPP. This results in a predominantly low‐frequency content of the power spectra, thereby providing a new model for studying the relationship between the MFCV and the frequency spectrum of surface EMG. Asymptomatic relatives that have inherited the disease probably can be detected with this method.
Differential response of the dog quadriceps muscle to external skeletal fixation of the knee
Authors: Lieber Richard L. , Fridëan Jan O. , Hargens Alan R. , Danzig Larry A. , Gershuni David H. 
Published: January 2005

AbstractThe change in muscle fiber size and fiber percentage was studied in three heads of the dog quadriceps following 10 weeks of immobilizationg using an external skeletal fixator. Muscle biopsy morphometric analysis revealed that muscle fiber atrophy was greatest for the vastus medialis and least for the rectus femoris. The atrophic response for type 1 fibers was, in order from most to least atrophied: VM > VL > RF, whereas for type 2 fibers the corresponding order was VM = VL > RF. An increase in connective tissue was also observed for all muscles. These results are discussed in terms of skeletal muscle architecture, initial fiber‐type distribution, and level of use. As a result, predictions are made as to the muscles that are most vulnerable to disuse atrophy, namely the postural muscles that contain a relatively large proportion of slow muscle fibers and cross a single joint. Conversely, those that are least susceptable to atrophy are those that are not used as postural muscles, that cross multiple joints, and that are predominantly composed of fast muscle fibers.
A myasthenic syndrome with congenital paucity of secondary synaptic clefts: CPSC Syndrome
Authors: Smit L. M. E. , Hageman G. , Veldman H. , Molenaar P. C. , Oen B. S. , Jennekens F. G. I. 
Published: January 2005

AbstractTwo cases of a newly recognized myasthenic syndrome were investigated (CPSC syndrome). The course of the disease was observed for periods of 6 and 3 years. In infancy, exacerbations of the symptoms occurred during febrile illness, but thereafter the clinical course was stable and the children appeared to be only slightly handicapped. Biopsies were taken from the intercostal muscle in both patients. Microelectrode studies revealed small Mepp amplitudes. Light microscopy demonstrated predominance of type I fibers and focal type‐grouping. There was a lowered cholinesterase activity and frequent branching of preterminal axons. Electron microscopy revealed that there were few, if any, folds of the postsynaptic membrane and that there were no signs of degeneration. Methods for localization of acetylcholine receptors (AChR) revealed a deficiency and altered distribution of AChRs at these postsynaptic membranes and the occurrence of extrajunctional AChRs in some muscle fibers. It is concluded that the syndrome is a clinicopathological entity, characterized morphologically by a congenital paucity of secondary synaptic clefts (CPSC syndrome).