bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Fibrous 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

Sensory 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

The 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

Authorities 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

After 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

Clonal, 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

Recruitment 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

We 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

To 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

Exertional 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

Electrophysiological 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

As 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

Many 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

Muscles 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

Precise 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

We 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

The 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.
Receptor‐triggered polyphosphoinositide turnover produces less cytosolic free calcium in cultured dysgenic myotubes than in normal myotubes
Authors: Tassin Anne‐Marie , Häggblad Johan , Heilbronn Edith
Published: January 2005

Myotubes prepared from mice with muscular dysgenesis (mdg) were used to further elucidate the putative role of inositol triphosphate (InsP3) in excitation‐contraction (E‐C) coupling of skeletal muscle. The mdg mutation is characterized by an uncoupling of the E‐C coupling. InsP3 production in normal and mdg/mdg myotube cultures and its relation to the levels of cytosolic free calcium were analyzed. Basal and ATP‐stimulated levels of InsP3 were equal in normal and mdg/mdg myotube cultures. In contrast, the transient increases of cytosolic free calcium in mdg/mdg myotubes in culture were generally much lower than those in normal ones. This suggests that the defect in dysgenic myotubes does not rest on the InsP3 formation but on the InsP3‐triggered transduction of excitation and/or the induction of calcium release from internal stores.
The effect of aging on cardiac autonomic and postganglionic sudomotor function
Authors: Low Phillip A. , Opfer‐Gehrking Tonette L. , Proper Carol J. , Zimmerman Irvin
Published: January 2005

Little quantitative information is available on the effects of age on peripheral autonomic function. We studied the effect of age on the heart rate (HR) responses to deep breathing and the Valsalva maneuver in 122 and 155 subjects, respectively, aged 10 to 83 years. The quantitative sudomotor axon reflex test (QSART) was determined in 114 subjects in the same age group. The HR responses were not different between the sexes, but a consistently significant regression with age was demonstrated in response to deep breathing and the Valsalva ratio. The QSART responses were significantly larger in male subjects and were generally lower in older subjects of both sexes but a significant negative regression with age was found only in female subjects. Cardiac vagal function is impaired with age, but postganglionic sympathetic function is little affected by age, suggesting selectivity of effects of aging on autonomic function.
Myogenic cell replication in minced skeletal muscle isografts of Swiss and BALBc mice
Authors: Grounds Miranda D. , McGeachie John K.
Published: January 2005

The onset and pattern of muscle precursor replication in minced skeletal muscle isografts were examined autoradiographically in 22 BALBc and 23 Swiss mice. Tritiated thymidine was injected into mice at various times after grafting to label replicating muscle precursors and regenerated muscle isografts removed 14 days after grafting when labeled precursors had fused into myotubes. Analysis of labeled myotube nuclei in regenerated minced isografts showed a difference between the onset of DNA synthesis in muscle precursors of the two strains, although precursor proliferation peaked around day 5 and was greatly reduced by day 8 in both strains. The onset and duration of muscle precursor replication was similar to that seen in isografts of intact whole muscles: however, precursor proliferation was delayed and protracted compared with injured muscles. This autoradiographic model enables quantitative investigations of muscle precursor behavior in vivo, with clinical potential for improving muscle regeneration after severe injury, transplantation, and some myopathies.
Relation of distribution of conduction velocities to nerve biopsy findings in n‐hexane poisoning
Authors: Yokoyama Kazuhito , Feldman Robert G. , Sax Daniel S. , Salzsider Byron T. , Kucera Jan
Published: January 2005

Distribution of conduction velocities (DCV) of sensory fibers in sural nerve was investigated in three patients with n‐hexane poisoning. Measurements were made at 1–2 months, 4–9 months, and at 11, 23, and 36 months after ending exposure. A sural nerve biopsy was obtained from one of the patients. The results indicated the characteristic changes of n‐hexane toxicity: myelinated nerve fiber degeneration and paranodal swelling, resulting in changes in the fiber diameter distribution. The DCV documented these changes. After removal from toxic exposure, varying degrees of recovery were studied clinically and evaluated with nerve conduction parameters. The DCV reflects the pathological changes in nerve in toxic neuropathy due to n‐hexane.
Antigravity posture for analysis of motor unit recruitment: The “45 degree test”
Authors: Petajan Jack H.
Published: January 2005

The maximum number of different motor unit action potentials (MUAPs), their firing rates, and total MUAP spikes/second recorded by monopolar needle electrode were determined for the biceps brachii muscle during 45‐degree elbow flexion. There were 4.2 ± 1.6 different MUAPs exceeding 100 μV. Mean firing rate was 10.0 ± 1.7 Hz, and total MUAP spikes/second were 40.3 ± 18. Recordings from 16 patients with neurogenic atrophy (NA) and just detectable weakness revealed corresponding values of 3.1 ± 1.7 different MUAPs, a mean rate of 10.2 ± 1.5 Hz and 30.6 ± 19 total MUAP spikes/second, not different from normal. In these patients, increased force of muscle contraction was required to activate high threshold motor units firing at high rates. In each of 4 patients just able to hold the arm against gravity, 1 or 2 “overdriven” motor units firing at a mean rate > 20 Hz were recorded. In 8 patients with myopathy and just detectable weakness, > 100 total MUAP spikes/second were recorded. Antigravity posture as a reference level of innervation has the advantage that motor unit firing rate is set about that of physiologic tremor (10–13 Hz). Its application was helpful in quantifying recruitment.
Electrophysiologic investigation of thallium poisoning
Authors: Dumitru Daniel , Kalantri Ananthlal
Published: January 2005

Electrophysiologic findings in thallium intoxication are usually untimely, limited in extent, and often uninformative. This report documents serial conduction and electromyographic findings in a case of thallium poisoning, beginning 10 days after symptom onset and ending 24 months later. Initially, the plantar nerves in the foot demonstrated profound axonal loss while the sural and peroneal nerves were essentially normal. The latter two nerves subsequently underwent axonal loss. Two years were required for the sural and peroneal nerves to display recovery. At 24 months, the plantar nerves continue to remain absent. A primarily distal axonopathy, significantly worse in the lower than upper extremities and requiring more than 2 years for recovery, now documents what was previously speculated: the electrophysiologic course of thallium intoxication. Additionally, this case emphasizes the need to examine the plantar nerves of the foot to avoid missing distal axonopathies during the early course of the disease process. The clinical course and pathophysiology of thallium poisoning are also reviewed.
Skeletal muscle pathology in AIDS: An autopsy study
Authors: Wrzolek Monika A. , Sher Joanna H. , Kozlowski Piotr B. , Rao Chandrakant
Published: January 2005

A survey of skeletal muscle pathology in 92 autopsied cases of AIDS revealed microscopic alterations in 64 cases. There were 40 cases of disuse atrophy, 8 of denervation atrophy, 2 of cryptococcal myositis, 1 of Mycobacterium avium intracellulare (MAI) infection and 2 of necrotizing myopathy associated with hyperkalemia. A second group of cases with changes of unknown etiology was found. These were tentatively ascribed to the direct or indirect action of HIV. This category includes 8 cases of inflammatory myopathy, 8 of necrotizing myopathy in absence of a known etiological factor, 3 of extreme atrophy and 4 of “regenerating” myopathy.
Organic arsenic‐induced Guillain‐Barré‐like syndrome due to melarsoprol: A clinical, electrophysiological, and pathological study
Authors: Gherardi Romain K. , Chariot Patrick , Vanderstigel Muriel , Malapert Denis , Verroust Josette , Astier Alain , Brun‐Buisson Christian , Schaeffer Annette
Published: January 2005

A young woman suffering from sleeping sickness was treated with melarsoprol. Thirty‐eight days after the first administration of this organo‐arsenic compound, myalgias, distal paresthesias and rapidly progressive weakness developed in all four limbs. Electrophysiological studies were misleading for Guillain‐Barré syndrome. Neuropathological data included massive distal wallerian degeneration in peripheral nerves and abnormalities in dorsal ganglia and spinal cord where vacuolation of anterior horn cells and axonal neurofilamentous masses were observed. Very high concentrations of arsenic were found in the spinal cord, contrasting with undetectable levels in peripheral nerves. Our findings are consistent with an arsenic neuronopathy manifested by initial proximal demyelination and delayed distal axonal damage. Renal and hepatic dysfunctions, which were implicated in the toxic arsenic accumulation, should be systematically detected before administration of melarsoprol. The diagnosis of Guillain‐Barré syndrome must be considered with caution in patients treated with this compound.
Effect of neural activity on skeletal muscle phosphoproteins
Authors: Nicholson Garth A. , Hawkins Scott , McLeod James G.
Published: January 2005

A number of phosphoproteins were found in the soluble fraction of rat skeletal muscle by two‐dimensional polyacrylamide gel electrophoresis (PAGE). The pattern of some of these phosphoproteins differed in fast (extensor digitorum longus, EDL) or slow (soleus) muscles, was dependent on normal innervation, and was altered with denervation. In order to determine if the pattern was maintained by electrical activity or trophic factors, we compared the effect of electrical block by local neural application of tetrodotoxin with the effect of complete nerve section. Both methods produced similar alterations in phosphoproteins, indicating that the pattern is dependent on nerve activity, not trophic factors. Such phosphoproteins are possible mediators of neural activity on gene expression.
Acetylcholinesterase histochemistry in the non‐endplate region of skeletal muscles and effect of denervation
Authors: Nakano Satoshi , Akiguchi Ichiro , Yasuda Yuzuru , Nakamura Shigenobu , Kameyama Masakuni , Kimura Jun
Published: January 2005

We measured acetylcholinesterase (AChE) in the non‐endplate region of rat muscle, documenting its intrinsic activity within muscle fibers, as well as the extrinsic level in the capillaries and endomysium. When each muscle was considered as a whole, intrinsic AChE activity detected within the fibers was stronger in the fast‐twitch extensor digitorum longus than in the slow‐twitch soleus. Analysis of individual muscle fibers also showed the same tendency with a higher value in the fast‐twitch type II fibers than in the slow‐twitch type I fibers. On the average, 73% of the fibers showed intermediate or strong enzymatic activity in the fast‐twitch muscle, whereas 56% of the slow‐twitch muscle had only low activity. Sectioning or ligation of the sciatic nerve resulted in nearly complete abolition of the enzyme in the non‐endplate region of the denervated muscles within 7 days, suggesting that nerve transmission regulates AChE activity not only in the endplate, as is well known, but also outside this region. Human skeletal muscles showed the same pattern of AChE activity in the non‐endplate region as seen in rat muscles.
The estimation of motor unit twitch tensions in the human masseter muscle by spike‐triggered averaging
Authors: McMillan A. S. , Sasaki K. , Hannam A. G.
Published: January 2005

Spike‐triggered averaging (STA) has been used to extract twitch profiles of single motor units (SMU) within the human masseter muscle. However, the reported twitch tensions may have been biased by thevoluntary firing frequency of the SMUs, the complex architecture ofthe muscle, and by the biomechanical linkage of the jaw. In this study, a rigid STA paradigm was used to record spike‐triggered “measured tensions” (STMTs) for 32 SMUs in the masseter musclesof four subjects. STMTs were recorded at two different orientations of a force transducer placed between the incisor teeth. The STMTs produced by each unit were used to calculate jaw torque. STMTs were also recorded in 11 units with differing degrees of muscle coactivation. STMTs for each unit varied according to the orientation of the force transducer. However, no systematic changes in STMTs occurred with reciprocal changes in the jaw moment arm. STMTs could be altered significantly by different degrees of muscle co‐activation. The use of STA as a method for determining SMU tension in the human masseter muscle appears to be highly task‐dependent and in the presence of co‐activation may be inappropriate.
Enhancement of peripheral nerve regeneration
Authors: Seckel Brooke R.
Published: January 2005

Numerous factors eternal to the nerve cell can support and enhance nerve regeneration after injury. The definition of these factors and the elucidation of their mechanisms of action are the central goals of much contemporary neurobiologic research. This research will hopefully lead to the discovery of factors that will prove to be therapeutically beneficial for patients with either peripheral nervous system (PNS) injury or central nervous system (CNS) injury. This article reviews the biology of the regeneration response of the nerve to injury and discusses many of the factors that enhance nerve growth. Finally, the nerve guide or nerve regeneration chamber model for the evaluation of putative nerve regeneration enhancing agents in vivo is also discussed.
Fibrillation potential amplitude and muscle atrophy following peripheral nerve injury
Authors: Kraft George H.
Published: January 2005

Maximum peak‐to‐pek fibrillation potential amplitude was measured in 69 subjects between 7 days and 10½ years post complete or partial peripheral nerve injury. Mean amplitude during the first 2 months was 612 μV; third and fourth months 512 μV, fifth and sixth months 320 μV. After the first year, no population of fibrillation potentials greater than 100 μV was recorded. The sciatic nerve was sectioned in 13 guinea pigs and animals studied up to 17 weeks. Fibrillation potential amplitude in gastrocnemius muscles declined paralleling that in humans. By the end of the study, type l fibers had lost almost half of their initial diameter and type II fibers had atrophied more than twice this amount. Fibrillation potential amplitude may be useful in estimating the time post nerve injury and appears to correlate with the surface area and fiber diameter of a type I muscle fiber.
Multiple‐pulse stimulation and dantrolene in malignant hyperthermia
Authors: Quinlan John G. , Wedel Denise J. , Iaizzo Paul A.
Published: January 2005

A potentially fatal condition, yet preventable, malignant hyperthermia (MH) lacks a satisfactory noninvasive diagnostic test. Studying the effects of intravenous dantrolene (3 mg/kg) on electrically stimulated skeletal muscle, we found that this approach does not conclusively distinguish between normal humans and those susceptible to malignant hyperthermia but nonetheless yielded important information about the action of dantrolene in man and in MH. Supramaximal single‐and multiple‐pulse stimulation of the common peroneal nerve produced stable torque responses of the dorsiflexor muscles (monitored in vivo), which dantrolene suppressed. With the multiple‐pulse stimulation (5–6 pulses) this torque suppression was significantly less in MH‐susceptible subjects than in control subjects. This distinction, also observed in MH swine, confirms this animal as a good model for human MH. That dantrolene's effect in MH can be more completely reversed with high frequency stimulation is intriguing; presumably, excitation‐contraction coupling differs in MH and normal muscle.
Concurrence of malignant hyperthermia and congenital abnormalities
Authors: Isaacs Hyam , Gericke George
Published: January 2005

Two children about to undergo corrective surgery were required to be investigated for malignant hyperthermia (MH). These investigations arose out of concern by the anesthetist who had obtained a history of unexplained pyrexial reactions to anaesthetic in other members of the family. Because over the years we have encountered several children with multiple congenital abnormalities who have been found to be susceptible to MH, we stressed the advizability of biopsying not only the patient but also the patient's parents. Positive responses for MH were obtained in the patients and in one of the parents on each occasion. The hypothesis of intrauterine MH with its pharmacogenetic propensity for heat production is considered as a possible etiological factor which may cause abnormalities of a congenital nature.
AAEM minimonograph #35: Clinical experience with transcranial magnetic stimulation
Authors: Eisen Andrew A. , Shtybel Wayne
Published: January 2005

We elicited motor evoked potentials (MEPs) using transcortical magnetic stimulation in 150 control subjects aged 14 to 85 years and 275 patients with a variety of diseases. There were no significant side effects.

Cortex‐to‐target muscle latencies measured 20.2±1.6 ms (thenar),14.2 ± 1.7 ms(extensor digitorum communis), 9.4 ± 1.7 ms(biceps), and 27.2 ± 2.9 ms (tibialis anterior). Central motor delay between the cortex and the C‐7 and L‐5 measured 6.7 ± 1.2 ms and 13.1 ± 3.8 ms, respectively. Mean spinal cord motor conduction velocity measured 65.4 m/s. MEP amplitude expressed as a percentage of the maximum M wave was never less than 20% of the M wave. A value of less than 10% is considered abnormal. MEP latency increases linearly with age and central motor delay is longer in older subjects. Compound muscle action potentials and absolute MEP amplitudes decrease linearly with age.

In multiple sclerosis (MS), MEP latency and central delay were often very prolonged. The MEP was more sensitive than the SEP in MS. In amyotrophic lateral sclerosis, MEP latencies were only modestly prolonged; the characteristic abnormality was reduced amplitude. When pseudobulbar features predominated MEPs were often absent. The MEP was of normal latency in Parkinson's disease, but age‐related amplitude was often increased. MEP latency and amplitude were normal in Huntington's disease. Abnormal MEPs persisted several months after stroke despite good functional recovery. The MEP could be used to advantage to demonstrate proximal conduction slowing and block in demyelinating neuropathies. In plexopathy, ability to elicit an MEP several days after onset of paresis was good evidence of neuronal continuity in motor fibers.
Responses of intercostal muscle biopsies from normal subjects and patients with myasthenia gravis
Authors: Pagala Murali K. D. , Nandakumar N. V. , Venkatachari S. A. T. , Ravindran K. , Namba Tatsuji , Grob David
Published: January 2005

In order to evaluate the mechanisms of weakness in muscles of patients with myasthenia gravis (MG), intercostal muscle biopsies were obtained from 9 normal subjects and 6 MG patients, and the compound muscle action potential (AP) and tension responses to nerve and muscle stimulation, and contracture responses on exposure to caffeine, were monitored in vitro. In normal muscle, on stimulation of the nerve or muscle at 30 to 100 Hz, the AP responses showed decrement in amplitude, one‐third of which was attributable to failure of neuromuscular transmission and two‐thirds to failure of muscle membrane excitation. On stimulation at 1 to 5 Hz, the AP responses showed very little decrement, while the contractile responses showed significant fade in tension, due to failure of E‐C coupling or contractility.

In muscle from patients with generalized MG, stimulation of the nerve at all frequencies (1 to 100 Hz) caused much greater decrement in APs and fade in tension responses than in normal muscle, due mainly to failure of neuromuscular transmission. However, at 100 Hz, 40% of the decrement in APs was due to failure of muscle membrane excitation, and at 1 to 5 Hz, 40% of the fade in tension was due to failure of E‐C coupling or contractility, as in normal muscle. On direct stimulation the contraction and half‐relaxation times were slower and the tetanic tension was smaller than in normal muscle, especially in the MG patient with thymoma. Caffiene‐induced contractures were smaller in MG muscle than in normal muscle. These results indicate that while the weakness of MG muscle than in normal muscle. These results indicate that while the weakness of MG muscle is due mainly to failure of neuromuscular transmission, it is also partly due to reduced E‐C coupling or contractility.
Familial amyloid polyneuropathy: Alanine‐for‐threonine substitution in the transthyretin (prealbumin) molecule
Authors: Koeppen Arnulf H. , Wallace Margaret R. , Benson Merrill D. , Altland Klaus
Published: January 2005

A previously reported family with amyloid polyneuropathy (FAP) was reinvestigated to determine the type of mutation in the transthyretin (prealbumin) molecule. Transthyretin was isolated from amyloid‐laden myocardium and serum, and tryptic peptides were resolved by high‐performance liquid chromatography. Amino acid sequencing of an anomalous peptide revealed an alanine‐for‐threonine substitution corresponding to position No. 60 of the transthyretin monomer. Detection of the FAP gene in asymptomatic carriers was accomplished by hybrid isoelectric focusing of transthyretin in the presence of dithiothreitol and high concentrations of urea, and by Southern blotting of Pvull‐digested leukocyte deoxyribonucleic acid. This type of FAP was found to be identical to the previously described Appalachian amyloid. Patients with FAP and their asymptomatic gene‐carrying offspring had significantly reduced levels of serum transthyretin and retinol‐binding protein.
Different localization of dystrophin in developing and adult human skeletal muscle
Authors: Wessels Andy , Ginjaar Ieke B. , Moorman Antoon F. M. , Van Ommen Gert‐Jan B.
Published: January 2005

Duchenne and Becker muscular dystrophy are caused by defects in dystrophin synthesis. Using affinity‐purified polyclonal anti‐dystrophin antibodies, we have studied immunohistochemically the subcellular localization of dystrophin in embryonic, fetal, and adult human skeletal muscle. In the embryonic stages dystrophin first appears in the sarcoplasm at the peripheral ends of the myotubes, immediately adjacent to the tendons, whereas in fetal stages dystrophin is found throughout the entire myofibers. In agreement with literature data, in adult muscle dystrophin expression was found to be restricted to the sarcolemma. The sarcoplasmic localization in embryonic and fetal tissue and the sarcolemmal localization of dystrophin in mature muscle suggests the accumulation of dystrophin in the cytoplasm prior to its integration into the membrane. These results increase our knowledge of the ontogenesis of dystrophin and may lead to a better understanding of the great diversity in pathological cases of Duchenne and Becker muscular dystrophy.
Neonatal mammalian spinal cord neurons and motoneurons in monolayer culture
Authors: Krieger Charles , Kim Seung U.
Published: January 2005

Previously, embryonic tissues have been used to produce monolayer cultures containing mammalian spinal cord neurons (SCN) and motoneurons (MN) for studies of the pathophysiology of motoneuron diseases. We demonstrate here that viable SCN and MN were observed in dissociated cultures from neonatal rat and mouse. These SCN and MN produced neurites and expressed acetylcholinesterase, neuron‐specific enolase and neurofilament protein. These results indicate that cultured postnatal SCN and MN are capable of survival, neurite extension, and phenotypic expression in culture.
X‐Irradiation improves mdx mouse muscle as a model of myofiber loss in DMD
Authors: Wakeford Susan , Watt Diana J. , Partridge Terence A.
Published: January 2005

The mdx mouse, although a genetic and biochemical homologue of human Duchenne muscular dystrophy (DMD), presents a comparatively mild histopathological and clinical phenotype. These differences are partially attributable to the greater efficacy of regeneration in the mdx mouse than in DMD muscle. To lessen this disparity, we have used a single dose of X‐irradiation (16 Gy) to inhibit regeneration in one leg of mdx mice. The result is an almost complete block of muscle fiber regeneration leading to progressive loss of muscle fibers and their replacement by loose connective tissue. Surviving fibers are mainly peripherally nucleated and, surprisingly, of large diameter. Thus, X‐irradiation converts mdx muscle to a model system in which the degenerative process can be studied in isolation from the complicating effect of myofiber regeneration. This system should be of use for testing methods of a leviating the myofiber degeneration which is common to mdx and DMD.
Study on the erythrocytes from myotonic dystrophy with multi‐nuclear NMR
Authors: Kuwabara Takeo , Yuasa Tatsuhiko , Ohno Takao , Yamamuro Manabu , Miyatake Tadashi
Published: January 2005

We have studied the water permeability through membranes, the function of the Na pump, and glucose metabolism of erythrocytes of patients with myotonic muscular dystrophy (MyD) using 1H–, 23Na, and 13C‐NMR techniques. A significant decrease in water permeability was recognized in the MyD erythrocyte membrane, and impaired Na pumping was suspected to be correlated with the former biochemical abnormalities in band III protein of MyD erythrocyte membrane. Significant acceleration of glycolysis in the erythrocyte for the first 160 minutes was also recognized in MyD: however, the production of lactate showed no difference between MyD and controls. The increased glucose uptake in MyD may be compensatory to the diminished pumping mechanism, but further information, such as inorganic phosphate permeability and the activity of the rate‐limiting enzyme of erythrocyte glycosis, is needed.