bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractMyotubes 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

AbstractLittle 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

AbstractThe 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

AbstractDistribution 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

AbstractThe 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

AbstractElectrophysiologic 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

AbstractA 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

AbstractA 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

AbstractA 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

AbstractWe 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

AbstractSpike‐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

AbstractNumerous 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

AbstractMaximum 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

AbstractA 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

AbstractTwo 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

AbstractWe 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

AbstractIn 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

AbstractA 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

AbstractDuchenne 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

AbstractPreviously, 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.