bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of altered metabolism (hypothyroidism) on muscle repair in the mdx dystrophic mouse
Authors: McIntosh L. M. , Pernitsky A. N. , Anderson Judy E. 
Published: January 2005

AbstractAfter dystrophic damage, the limb muscles of the mdx mouse recover very effectively compared to muscles in Duchenne muscular dystrophy (DMD) patients. Since thyroid hormone is required for muscle development and integrity, we examined whether a deficiency of the hormone, induced by 0.05% propylthiouracil (PTU) in drinking water over 8 weeks, would be deleterious to the myogenesis and muscle repair in control and mdx mice. Measured metabolic and growth parameters confirmed hypothyroidism in PTU‐treated mice. Histological and morphometric techniques were used to study myogenesis and the repair of the tibialis anterior muscle (TA) after crush injury in mdx mice and their nondystrophic controls (C57B1/10ScSn). After 8 weeks, PTU‐treated TA from mdx mice had larger crush sites and lower myotube density than TA in untreated mdx mice. In unoperated mdx TA, there was a larger proportionate area of active dystrophy and smaller fiber diameter in PTU‐treated than in untreated mdx TA, which suggested that PTU increased the activity of dystrophy as well. In contrast, in control TA neither the regeneration of myotubes or fiber diameter were affected significantly by PTU. Therefore, these results suggest that mdx muscle regeneration is more affected by hypothyroidism than normal muscle repair. This may be due to the larger pool of muscle precursors in mdx than control muscle, and a possible impairment of precursor cell proliferation or fusion during myotube formation. © 1994 John Wiley & Sons, Inc.
Focal myopathy induced by chronic intramuscular heroin injection
Authors: Louis Elan D. , Bodner Russ A. , Challenor Yasoma B. , Brust John C. M. 
Published: January 2005

AbstractA patient developed focal fibrotic myopathy after manry Years of intramuscular heroin use. While such changes have been associated with chronic intramuscular injections of pentazocine and a similar myopathy resulting from chronic intramuscular heroin has not been convincingly described. © 1994 John & Sons, Inc.
Sodium channels accumulate at the tips of injured axons
Authors: England John D. , Gamboni Fabia , Ferguson Michele A. , Levinson S. Rock 
Published: January 2005

AbstractThe axolemmal distribution of voltage‐gated sodium channels largely determines the regions of axonal electrical excitability. Using a wellcharacterized anti–sodium channel antibody, we examined peripheral nerve fibers focally injured by exposure to the neurotoxic agent, potassium tellurite (K2TeO3). Immunocytochemical and radioimmunoassay data showed a focal accumulation of sodium channels within the tips of injured axons. The major increase in sodium channel concentration occurred between 7 and 11 days after toxin exposure; however, immunocytochemically, excess sodium channels persisted in several axonal endings for a much longer time. The accumulation of sodium channels at injured axonal tips may be responsible, in part, for ectopic axonal excitability and the resulting abnormal sensory phenomena (especially pain and paresthesias) which frequently complicate peripheral nerve injury in humans. © 1994 John Wiley & Sons, Inc.
Paramyotonia congenita: Abnormal short exercise test, and improvement after mexiletine therapy
Authors: Jackson Carlayne E. , Barohn Richard J. , Ptacek Louis J. 
Published: January 2005

AbstractThe diagnosis of paramyotonia congenita (PC) can be aided by demonstrating a decrease in compound motor action potential amplitude after exercise and a decrement on repetitive stimulation, following cold exposure. We report a patient with PC who presented with complaints of cold‐induced hand and jaw stiffening, in the absence of any episodes of weakness. Treatment with mexiletine led to resolution of the abnormalities exhibited during a short exercise test and repetitive stimulation following ice bath immersion. Molecular genetic analysis revealed a missense mutation (cytosine to thymidine) on chromosome 17 in the alpha‐subunit of the skeletal muscle sodium channel gene that results in the replacement of threonine with methionine. This case demonstrates that, despite the absence of weakness, the short exercise test following cold exposure can be used to confirm the diagnosis of PC in patients without episodic weakness. Furthermore, improvement of the electrophysiologic abnormalities with mexiletine was documented, corresponding with clinical improvement. © 1994 John Wiley & Sons, Inc.
Botulinum toxin converts muscle acetylcholine receptors from adult to embryonic type
Authors: Költgen Dirk , Ceballos‐Baumann Andres O. , Franke Christian 
Published: January 2005

AbstractTo assess the postsynaptic consequences of botulinum toxin injection into muscle we characterized the nicotinic acetylcholine receptor (nAChR) with the patch clamp technique, using adult mouse muscle after destruction of the nerve ending and after treatment with botulinum toxin (BoTX). In both, embryonic channels with a conductance of 30 and 34 pS could be identified, whereas on adult control muscle nAChR channels had a conductance of 48 pS. The mean open times were 1.2 ms for the channels in control, 2.5 ms in denervated, and 2.4 ms in BoTX‐treated muscle. The dose–response curves of the maximal acetylcholine‐elicited currents showed a Km of 60 μmol/L for denervated, 70 μmol/L for BoTX‐treated, and 100 μmol/L for control muscle. Destruction of the nerve ending and inhibition of acetylcholine release by BoTX has the same effect as far as the increase of sensitivity of the muscle to acetylcholine is concerned. In contrast to single‐fiber EMG findings in patients treated for focal dystonia no distant changes could be found in the control muscle of the BoTX‐treated animals. © 1994 John Wiley & Sons, Inc.
Statistical errors and their effect on electrodiagnostic medicine
Authors: Rivner Michael H. 
Published: January 2005

AbstractFailure to demonstrate abnormalities on diagnostic tests in patients felt certain to have a disease is all too common, especially when symptoms are mild to moderate. One strategy used in such cases is to perform multiple tests hoping that one will confirm the clinical suspicion. An example of this strategy is found in carpal tunnel syndrome where multiple tests are often used to confirm the diagnosis. Unfortunately, this approach is often erroneous. Since no diagnostic test can perfectly discriminate between normal and abnormal, critical values are set at levels where most subjects are correctly classified. Using this methodology, approximately 2.5% of patients who are normal will be mistakenly called abnormal. This type I error, is additive when additional independent tests are performed. Since no two tests for a single condition are completely independent, the total error is less than the sum of the individual errors for each test. Even after accounting for interdependency, the total error of combined tests may be unacceptably high. If a single, highly discriminating, test is not available and multiple tests are used, abnormalities in more than a single test are needed to distinguish between normals and abnormals. © 1994 John Wiley & Sons, Inc.
Diagnostic tests: A statistical review
Authors: Schulzer Michael 
Published: January 2005

AbstractCommon measures of the accuracy of diagnostic tests are reviewed. It is shown that the actual performance (predictive value) of these tests depends not only on their sensitivity and specificity, but also on the prevalence of the disease in the population tested (Bayes' theorem). The effect of an inaccurate “gold standard” on the calibration of a new diagnostic test is discussed. Receiver operating characteristic (ROC) curves are introduced as a tool for selecting an optimal cutpoint for a test, and for comparing different tests. Schemes are given for combining tests to improve their accuracy. When multiple continuous measurements are available, methods of discriminant analysis (and logistic regression) are shown to provide measurement combinations with improved accuracy. Examples and key references are provided. © 1994 John Wiley & Sons, Inc.
Postexercise phosphocreatine resynthesis is slowed in multiple sclerosis
Authors: Kent‐Braun Jane A. , Sharma Khema R. , Miller Robert G. , Weiner Michael W. 
Published: January 2005

AbstractTo determine whether skeletal muscle oxidative metabolism is impaired in multiple sclerosis (MS), 31 phosphorus magnetic resonance spectroscopy was used to measure the rate of intramuscular phosphocreatine (PCr) resynthesis following exercise in MS and controls. Thirteen MS patients underwent intermittent isometric tetanic contractions of the dorsiflexor muscles elicited by stimulation of the peroneal nerve. Eight healthy control subjects performed voluntary isometric exercise of the same muscles. During exercise, there were no differences between groups in the fall of either PCr or pH. However, the half‐time (T‐1/2) of PCr recovery following exercise was significantly longer in MS (2.3 ± 0.3 min) compared to controls (1.2 ± 0.1 min, P < 0.02). These data provide evidence of slowed PCr resynthesis following exercise in MS, which indicates impaired oxidative capacity in the skeletal muscle of this group. This finding suggests that intramuscular changes consistent with deconditioning may be important in the altered muscle function of persons with MS. © 1994 John Wiley & Sons, Inc.
Electrical myotonia of rabbit skeletal muscles by HMG‐CoA reductase inhibitors
Authors: Sonoda Yoshito , Gotow Tsukasa , Kuriyama Masaru , Nakahara Keiichi , Arimura Kimiyoshi , Osame Mitsuhiro 
Published: January 2005

AbstractHMG‐CoA reductase (HCR) inhibitors are effective cholesterol‐lowering agents in the treatment of hypercholesterolemia. Using intracellular microelectrodes, we studied the pathomechanism of myotonia experimentally induced in rabbits by HCR inhibitors, simvastatin, and pravastatin. The external intercostal muscle of rabbits showed some electrophysiologic characteristics of myotonia including repetitive firing after administration of simvastatin (50 mg/kg per day, for 4 weeks). The relative chloride conductance, though reduced in both, was more affected in simvastatin‐administered muscles. In normal muscles perfused with a solution containing the inhibitors, both simvastatin and pravastatin produced membrane hyperexcitability with repetitive firing similar to that seen in simvastatin‐administered rabbits. The minimum concentrations required to cause repetitive firing was 0.3 mg/L for simvastatin and 30 mg/L for pravastatin. These results indicate that HCR inhibitors induce some characteristics of myotonia by blocking the chloride channel in the muscle membrane. © 1994 John Wiley & Sons, Inc.
The origin of muscle fasciculations and cramps
Authors: Layzer Robert B. 
Published: January 2005

AbstractThe anatomic site of origin of muscle fasciculations and cramps has been debated for many years. Many authors have argued for a central origin of the abnormal discharges in the anterior horn cells. However, most of the evidence favors a very distal origin in the intramuscular motor nerve terminals. The factors giving rise to these discharges are not well understood. Fasciculations may be related to chemical excitation of motor nerve terminals, whereas cramps may result from mechanical excitation of motor nerve terminals during muscle shortening. © 1994 John Wiley & Sons, Inc.
Possible role of apamin‐sensitive K+ channels in myotonic dystrophy
Authors: Behrens María Isabel , Jalil Patricio , Serani Alejandro , Vergara Fernando , Alvarez Osvaldo 
Published: January 2005

AbstractMyotonic muscular dystrophy is a genetic disease characterized mainly by muscle atrophy and myotonia, a repetitive electrical activity of muscle. In the present study, the possible role of apamin‐sensitive K+ channels in the genesis of myotonia was investigated. Apamin is a peptide from bee venom that specifically blocks small conductance Ca2+‐activated K+ channels. The injection of a small amount of apamin (20–30 μl, 10 μmol/L) into the thenar muscle of myotonic dystrophy patients decreased the basal electrical activity during the electromyogram in the 6 patients studied. Myotonic discharges after muscle percussion were more difficult to trigger and of smaller intensity and duration. In 2 controls and in 2 patients with generalized myotonia, as well as in 1 patient with myotonia congenita (where the defect is in chloride channels), apamin had no effect. These results suggest that apamin‐sensitive K+ channels participate in the mechanism that generates myotonia in myotonic dystrophy. © 1994 John Wiley & Sons, Inc.
Central nervous system involvement in multifocal demyelinating neuropathy with persistent conduction block
Authors: Péréon Yann , Jardel J. , Guillon B. , Guihéneuc P. 
Published: January 2005

AbstractWe report the case of a 27 year‐old man treated for bilateral optic neuritis 5 and 3 years before who within a few months developed sensori‐ motor disorders of the arms and legs Characterized by asymmetric distribution and distal prominence. In addition to sensorimotor defects, which were particularly marked in the left arm and right leg, clinical examination showed nearly generalized areflexia. Electrophysiological studies revealed a rnultifocal neuropathy with persistent distal and proximal conduction blocks associated with a considerable slowing of motor nerve conduction, as well as central nervous system involvement indicated by motor‐, somatosensory‐, and visual‐evoked potentials. CSF analysis showed a mildly elevated protein level; anti‐GM, activity was negative. Sural nerve biopsy revealed onion–bulb‐like formations, and cerebral MRI showed a small, isolated, and aspecific high signal for white matter. First described by Lewis and Sumner in 1982, rnultifocal neuropathy with persistent conduction blocks may be associated with central demyelination. Our case is compared with 3 similar ones in the literature, and the favorable effects of steroid therapy are emphasized. © 1994 John Wiley & Sons, Inc.
Treatable gait disorder and polyneuropathy associated with high titer serum IgM binding to antigens that copurify with myelin‐associated glycoprotein
Authors: Pestronk Alan , Choksi Rati , Bieser Karen , Goldstein Jonathan M. , Adler Charles H. , Caselli Richard J. , George Edwin B. 
Published: January 2005

AbstractWe studied clinical and electrodiagnostic features of 9 patients with very high titers (>1:10, 000) of serum IgM binding to a CNS myelin antigen (CMA) preparation that copurified with myelin‐associated glycoprotein (MAG). We found that 8 of the 9 patients had a combined syndrome of gait ataxia and polyneuropathy (GAPN) with late‐age onset (mean = 70 years of age). In the 8 GAPN patients progressive difficulty with ambulation led to significant functional disability and frequent falling. Examination showed a wide‐based unsteady gait, especially when standing still or turning. There was mild‐to‐moderate distal sensory loss with involvement of joint position sense only in the toes. Motor changes, when present, were mild and mainly involved distal leg musculature. Treatment of 5 GAPN patients resulted in clear improvement of 2 after intravenous human immunoglobulin and of 3 others after other immunodulating agents. Immune‐mediated GAPN syndromes with high titers of serum IgM binding to CMA appear to be treatable causes of gait disorders in older patients. © 1994 John Wiley & Sons, Inc.
Quantitative sweat testing using acetylcholine for direct and axon reflex mediated stimulation with silicone mold recording; controls versus neuropathic diabetics
Authors: Stewart John D. , Nguyen Dang Minh , Abrahamowicz Michal 
Published: January 2005

AbstractSweat glands were stimulated by iontophoresed acetylcholine (ACh). Using a two‐chamber capsule, one group of sweat glands was stimulated directly by ACh, and another stimulated indirectly via axon reflexes. Sweat droplets were recorded with a silicone mold and counted by a dissecting microscope and a computerized scanner. Responses from 32 diabetics with generalized somatic peripheral neuropathy were compared with 32 controls. Counting sweat droplets by computerized scanning was more accurate than by microscope. The numbers of droplets, their total areas, and mean areas were all larger in the direct response. Counts of droplet numbers was more diagnostically useful than measuring the total area and the mean areas of the droplets. There was a high correlation between droplet numbers of the direct and the indirect sweat responses. Droplet number counts of the direct response had a slightly higher diagnostic yield than those of the technically more complicated indirect response: for a specificity of 95%, the direct response had a sensitivity of 55%, the indirect being 50%. © 1994 John Wiley & Sons, Inc.
Serial neurophysiological studies of intramuscular botulinum‐A toxin in humans
Authors: Hamjian John A. , Walker Francis O. 
Published: January 2005

AbstractTo characterize the time course of intramuscular botulinum toxin–induced paresis, we serially performed electrophysiological measurements and recorded the sonographic size of an extensor digitorum brevis (EDB) muscle in 10 human subjects before and after injecting the EDB with 10 units of botulinum‐A toxin. All EDB CMAPs decreased within 48 h, with peak decline at day 21 (8.3 ± 3.1 mV to 3.0 ± 0.9 mV). Decline of mean rectified voltage during maximal voluntary contraction of the EDB paralleled the change in CMAP amplitude. Average decrements to 2‐Hz repetitive stimulation never exceeded 6% (day 42) and exercise failed to facilitate Significantly CMAP amplitude. Atrophy peaked at day 42. The F‐wave to M‐wave ratio increased at day 2; silent periods did not change. Our findings confirm a primary peripheral action of the toxin, but a superimposed, transient central effect of the drug cannot be excluded. Intramuscular injections into EDB provide a useful model for studying chemodenervation effects. © 1994 John Wiley & Sons, Inc.
Transfer function analysis of respiratory sinus arrhythmia: A measure of autonomic function in diabetic neuropathy
Authors: Freeman Roy , Cohen Richard J. , Saul J. Philip 
Published: January 2005

AbstractStandard techniques measuring heart rate (HR) variability do not account for its dependence on the rate and depth of respiration or measure the time relationship between changes in lung volume and HR. We used transfer function analysis to determine the magnitude and time relationship of the HR response to a known change in lung volume in controls and diabetics. This technique demonstrated significant differences between controls and diabetics with varying degrees of autonomic dysfunction. Specifically, reduced supine vagal and increased supine sympathetic HR modulation was found with progression of the autonomic neuropathy. In response to postural change the normal diabetics displayed impaired sympathetic HR modulation. Transfer function analysis yields new insight into the sequence of changes that occur with diabetic autonomic neuropathy and provides an accurate, easily comprehensible measurement of respiratory induced HR variability.© 1995 John Wiley &Sons, Inc.
Sympathetic skin response (SSR) is abnormal in multiple sclerosis
Authors: Elie B. , Loubo'Jtin J. P. 
Published: January 2005

AbstractAs the function of the autonomic nervous system is often compromised in multiple sclerosis (MS), different standardized tests are used to detect disseminated abnormalities in cardiovascular autonomic functions. Sympathetic skin response (SSR), a slow wave generated in deep layers of the skin, is induced by reflex activation of sudomotor sympathetic efferent fibers. SSR was studied in 70 patients classified into different categories according to the diagnostic criteria for MS. We also obtained pattern reversal visually evoked potentials and brainstem auditory evoked potentials as well as somatosensory evoked potentials (by median and posterior tibial nerve stimulation). SSR was abnormal in 66 patients (94.2%), including abnormal foot latency with normal hand latency in 30 (42.8%), delayed foot and hand latencies in 30 (42.8%), and no response in 6 (8.6%). The percentages of SSR abnormalities were similar in the different patient categories. Pathological SSR were more common than abnormal evoked potentials in suspected and probable MS. SSR appears to be a simple and effective means of assessing sympathetic sudomotor outflow disturbances in MS, providing a valuable addition to current electrophysiological procedures for the detection of MS lesions.© 1995 John Wiley &Sons, Inc.
Site and mechanics of failure in normal and dystrophin‐deficient skeletal muscle
Authors: Law Douglas J. , Tidball James G. , Caputo Angelo 
Published: January 2005

AbstractPartial or complete tearing of skeletal muscle occurs both in acute muscle injury and in some pathological muscle conditions. Despite the impact of such tearing on normal muscle function, few studies have examined the site or mechanism of muscle injury at cellular or subcellular levels of organization. The present study determines the ultrastructural location and mechanical conditions of tensile failure in normal mouse extensor digitorum longus muscles. All of these muscles failed near a myotendinous junction (MTJ), but within the muscle fibers, in a transverse plane coincident with the edge of an A‐band. The breaking stress averaged 5.71 × 105 N/m2 for muscles stimulated tetanically during lengthening, and 5.01 × 105 N/m2 for unstimulated muscles. Breaking strain averaged 135%, and showed no dependence on the state of activation of the muscle. The energy absorbed by each muscle averaged 362.5 mJ/g in unstimulated muscle, and 613.2 mJ/g in the stimulated samples. In addition to the failure properties of normal muscle, the effect of dystrophin deficiency on the site and conditions of failure was determined using muscle from mdx mice, which lack dystrophin. The absence of dystrophin had no detectable effect on the stress, strain, or energy absorbed, regardless of the state of muscle activation. Unstimulated mdx muscle failed in the plane of an A‐band, but tetanic stimulation produced failure in the reticular lamina of the tendon, just external to the MTJ, in 75% of the fibers in the mdx muscles. Although dystrophin's cytoplasmic location makes it unlikely that this unique mode of failure is due directly to the absence of the protein, failure in the reticular lamina may result from a difference in load distribution that accompanies the response of mdx muscle to dystrophin deficiency.© 1995 John Wiley &Sons, Inc.