bluuebunny/crossref_metadata_2025_split huggingface dataset:
Staircase, fatigue, and caffeine in skeletal muscle in situ
Authors: Macintosh Brian R. , Kupsh Christine C. 
Published: January 2005

AbstractThe specific locus of impairment in excitation‐contraction coupling that is associated with skeletal muscle fatigue has not been identified. In the present study the phenomena of staircase and fatigue were studied in the rat gastrocnemius muscle in situ, and the effect of caffeine (50 mg kg‐1) given prior to or during 5 minutes of stimulation was observed. A 10 Hz indirect stimulation resulted in a staircase response that proceeded for 10.4 ± 1.6 (x ± SD) seconds, reaching a peak force value that was 70–75% higher than the initial contraction. After 5 minutes of stimulation and 20 minutes of rest, the staircase response was longer (17 ± 3.1 seconds) and proceeded more slowly when the stimulation regimen was repeated. Caffeine accelerated the fatigue and reversed the effect of fatigue on the staircase response. Since caffeine enhances the release of Ca2+ from terminal cisternae, it is postulated that the accelerated fatigue in the presence of caffeine is indicative of a reduced availability of Ca2+ for release. This hypothesis would also explain the slower progression of staircase in the fatigued muscle.
Rods in the terminal cisternae of skeletal muscle
Authors: Dulhunty Angela Fay 
Published: January 2005

AbstractThe purpose of the study was to investigate rod‐like structures (rods) in the terminal. Cisternae membrane of freeze fracture replicas of fast‐ and slow‐twitch mammalian muscle. The 9 × 50 nm rods crossed the junctional gap perpendicular to the T‐tubule membrane and terminated near indentations. Rods are likely to have a structural basis because (1) grooves were seen in the complimentary membrane leaflet, (2) rods were seen in tissue fixed in 0.5, 5, or 6% glutaraldehyde or 5% acrolein, (3) rods were seen in tissue fractured over a range of temperatures from −40 to −196°C, (4) the number of rods was correlated with the contractile properties of fibers, and (5) the density of rods increased when fibers were depolarized before fixation. The rods are in a unique location that would allow them to participate in excitation‐contraction coupling, perhaps by transmitting an electrical signal from the T‐tubule membrane to calcium release sites in the terminal cisternae.
Histochemical localization of carbonic anhydrase in normal and diseased human muscle
Authors: Peyronnard Jean‐Marie , Charron Louise F. , Messier Jean‐Pierre , Lavoie Jeanne , Faraco‐Cantin Féliciana , Dubreuil Martin 
Published: January 2005

AbstractA method is described for histological localization of carbonic anhydrase (CA) in sections of frozen human muscle using the rapid and inexpensive histochemical technique of Hansson. Results obtained in normal subjects indicate clearly that CA reactive fibers are of type 1. Similarly, abnormalities seen with CA in the muscle biopsy of a patient presenting with type 1 fiber hypotrophy and preponderance duplicated almost exactly those observed with the actinomyosine adenosine triphosphatase and the reduced nicotin‐amide adenine dinucleotide dehydrogenase reactions. Observations of grouped CA‐positive muscle fibers in a case of chronic neurogenic atrophy suggest that, like other enzymes, CA expression in muscle is under neurogenic control.
Hexahydrocarbon effects on intermediate filament organization in human fibroblasts
Authors: Durham Heather D. , Peñta Sergio D. J. , Ecobichon Donald J. 
Published: January 2005

AbstractWe reported previously that 2,5‐hexanedione (2,5‐HD), the neurotoxic metabolite of methyl‐n‐butylketone (MnBK) and n‐hexane, induced aggregation of intermediate filaments of the vimentin type in cultured fibroblasts. To determine if these findings have relevance to the mechanism by which these hexacarbons induce their filamentous axonopathy, it was necessary to show that only those hexacarbon analogues that induce focal accumulation of neurofilaments in nerve fibers do aggregate intermediate filaments in fibroblasts. We report here that the nonneurotoxic hexacarbons, 1,6‐hexanediol and 2,4‐hexanedione (2,4‐HD), had no primary effect on intermediate filament distribution in fibroblasts, although the profound, nonspecific cytotoxicity of the latter controverted comparisons with equimolar, effective concentrations of 2,5‐HD. Fibroblasts did not metabolize MnBK to 2,5‐HD sufficiently to induce reproducible aggregation of intermediate filaments in these cells in culture.
Association between biochemical and physiological properties in single motor units
Authors: Hamm Thomas M. , Nemeth Patti M. , Solanki Lata , Gordon Debra A. , Reinking Robert M. , Stuart Douglas G. 
Published: January 2005

AbstractMotor units from the cat tibialis posterior muscle were examined for an association between physiological and biochemical properties. Functionally isolated motor units were categorized on the basis of their physiological properties. This was followed by quantitative microbiochemical analysis of single muscle fibers from each unit, identified in cross sections using the glycogen‐depletion method. The activities of malate dehydrogenase and β;‐hydroxyacyl‐CoA dehydrogenase distinguished between fatigable (type FF) and fatigue‐resistant (types FR and S) units. The activities of both lactate dehydrogenase and adenylokinase were higher in fast‐than in slow‐contracting units. Cluster analyses, based on both physiological and biochemical properties alone, produced groupings identical to types FF, FR, and S. The association between physiological and biochemical properties substantiates the idea that biochemically distinct groups of motor units correspond to physiologically identifiable groups.
Schwann cell‐conditioned medium supports neurite outgrowth and survival of spinal cord neurons in culture
Authors: Bosch E. Peter , Assouline Jose G. , Pantazis Nicholas J. , Lim Ramon Lim 
Published: January 2005

AbstractThe effect of Schwann cell‐conditioned medium (SCM) on the development in vitro of spinal cord neurons was studied. Spinal cord neurons from 18‐day‐old rat embryos were cultured in serum‐free conditioned medium obtained from confluent rat Schwann cells. In cultures fed SCM, the cells developed typical neuronal morphology and were identified by indirect immunofluorescence using a monoclonal antibody to neurofilament protein. SCM stimulated neurite outgrowth and supported survival of spinal cord neurons. Preliminary characterization suggests that the neurotrophic factor in SCM appears to be a protein with a molecular weight greater than 8000 daltons.
Hypoglossal nerve conduction in normal subjects
Authors: Redmond Michael D. , Di Benedetto Margarete 
Published: January 2005

AbstractA nerve conduction method is demonstrated for cranial nerve XII, the hypoglossal nerve. Submandibular surface stimulation is performed while recording over the anterior surface of the tongue. There were 30 normal adult subjects and 60 hypoglossal nerves studied. Evoked response parameters are reported as follows: mean latency 2.2 ± 0.4 msec, mean amplitude 3.8 ± 1.6 mV (baseline to peak, best of 5 responses). This nerve conduction method is reliable and should expand the electrophysiological assessment of XII cranial nerve motor function.
Effects of immobilization on rat hind limb muscles under non‐weight‐bearing conditions
Authors: Jaspers Stephen R. , Fagan Julie M. , Satarug Soisungwan , Cook Paul H. , Tischler Marc E. 
Published: January 2005

AbstractDorsiflexion of one unloaded hind limb caused hypertrophy of the soleus relative to weight‐bearing controls and faster growth of the plantaris and gastrocnemius muscles relative to the contralateral freely moving muscles. Unloading of the soleus muscle diminished primarily myofibrillar proteins whereas stretching increased all proteins. Stretching the soleus increased RNA, accelerated, especially, in vitro synthesis of sarcoplasmic proteins, and diminished in vitro proteolysis. Both in vivo and in vitro results showed slower synthesis and faster degradation in the freely moving than in the weight‐bearing soleus muscle, faster synthesis and slower degradation in the stretched than in the freely moving soleus muscle, and faster degradation in the stretched than in the weight‐bearing soleus muscle. Hence, stretching of the soleus muscle prevented changes in mass and protein metabolism produced by unloading. Shortening of the extensor digitorum longus muscle produced less muscle growth, slowed in vitro protein synthesis, and lowered RNA relative to the contralateral, freely moving muscle.
Assessment of thoracic paraspinal muscles in the diagnosis of ALS
Authors: Kuncl Ralph W. , Cornblath David R. , Griffin John W. 
Published: January 2005

AbstractThe distribution of muscle involvement, assessed clinically and electromyographically, was analyzed prospectively in 55 consecutive amyotrophic lateral sclerosis (ALS) patients and in 54 patients with other predominantly motor syndromes, some of whom were referred with suspected ALS. In ALS patients, distal limb muscles and thoracic paraspinal muscles were affected most frequently, more so than proximal limb and cranial muscles. The incidence of bulbar symptoms in ALS was greater in women than in men. These patterns suggest selective vulnerability of specific neuronal populations. The vulnerability of truncal muscles, illustrated by thoracic paraspinal wasting or head and shoulder drooping, was a helpful differential sign in diagnosing ALS. Thoracic paraspinal electromyography was especially valuable in distinguishing ALS from other disorders, such as combined cervical and lumbar spondylotic amyotrophy or polymyositis, which may masquerade as ALS. The finding of denervation atrophy on biopsy of thoracic paraspinal muscles was diagnositic in difficult cases. Because the thoracic paraspinal muscles are frequently affected in ALS and spared in spondylotic amyotrophy, their assessment provides a practical strategy in differentiating ALS from other motor syndromes.
Spinal irradiation does not inhibit distal axonal sprouting
Authors: Pamphlett Roger S. 
Published: January 2005

AbstractIn an attempt to determine the relative importance of the nerve cell body and of the axon in initiating and controlling axonal regeneration, nerve cell bodies were irradiated and the ability of the distal axon to sprout was examined. Mice were subjected to either 25 or 50 Gray (Gy) of x‐irradiation localized to the lumbar spinal cord. After times varying from 1 day to 6 months after irradiation, a sublethal dose of botulinum toxin (BoTx) was injected into the calf muscles of one leg. The soleus muscle was examined histologically after times varying from 1 week to 6 months after injection, and BoTx‐induced ultraterminal axonal sprouting was assessed by the number of motor endplates showing sprouts, the length of the sprouts, and the long term endplate morphology. Apart from some irradiated subgroups having slightly shorter sprout length, no significant differences were found between irradiated and nonirradiated groups. The results suggest either that the processes in the nerve cell body responsible for initiating and supporting axonal growth are resistant to large doses of irradiation, or that growth regulatory mechanisms in the distal axon are under local control.
Molecular genetics in basic myology: A rapidly evolving perspective
Authors: Stedman Hansell , Sarkar Satyapriya 
Published: January 2005

AbstractMyology has greatly benefited from the recent unification of concepts in molecular, cellular, and developmental biology. The interplay between intrinsic and extrensic factors in determining the physiologic characteristics of individual myofibers has emerged as an important theme. Of special note is the manner in which the study of contractile protein gene structure and expression has contributed to our understanding of the development and ultimate plasticity of the contractile apparatus. As mechanistic models of normal myogenesis achieve increasing sophistication, the opportunities for understanding the pathogenesis of progressive muscle disfunction improve. In this article we review recent progress in basic myology which will be of interest to clinicians studying the heritable neuromuscular disorders.
Spontaneous reinnervation of a free muscle flap
Authors: Sardo Marialyn J. , Upton Joseph , Jones H. Royden , Seckel Brooke Rutledge 
Published: January 2005

AbstractA latissimus dorsi muscle flap was used to repair a servere traumatic avulsion defect of the dorsum of the foot in 3‐year‐old girl. The severed peroneal nerve apparently regenerated across a large gap and spontaneously reinnervated the denervated muscle flap. This resulted in a functional flap as demonstrated clinically and electromyographically. Surgical methods of muscle reinnervation and the influence of neurotrophic factors are discussed.
Longitudinal structure and innervation of two mammalian hindlimb muscles
Authors: Manzano Gilberto , McComas Alan J. 
Published: January 2005

AbstractThe possibility of a topographic relationship between the spinal cord and the longitudinal axis of a muscle has been explored in two mammalian hamstring muscles: the rat semitendinosus (ST) and biceps femoris (BF). In both muscles the fibers did not extend the full length of the respective muscles but were arranged in longitudinal arrays. There were two such arrays in BF and three in ST; monopolar recordings revealed that each array had a transverse band of endplates extending across the middle part. By stimulating ventral nerve roots in the lumbosacral outflow, it was found that L5 made the greatest contribution to the innervation of both ST or BF was there any evidence of a topographic relationship between the spinal cord and the muscle belly.
Patterns of selective involvement of thigh muscles in neuromuscular disease
Authors: Schwartz Martin S. , Swash Michael , Ingram David A. , Davis Graham R. , Thompson Alan J. , Thakkar Chandra , Hart Geoffrey 
Published: January 2005

AbstractIn 14 patients with limb girdle muscular dystrophy, polymyositis, and type 3 spinal muscular atrophy, CT scans of the thigh muscles were correlated with single fiber EMG studies in vastus lateralis, semimembranosus and biceps femoris muscles. There was a relation between the extent of CT scan abnormality and increased fiber density in the three muscles studied, except in the most severely affected muscles in which in some muscles the fiber density values were lower than expected. These results were independent of the underlying pathology. Correlative CT/SFEMG studies provide insights into the pattern of selective involvement of certain muscles in neuromuscular disorders.
Muscle function in patients with primary hyperparathyroidism
Authors: Joborn Charlotte , Rastad Jonas , Stålberg Erik , Åkerström Göran , Ljunghall Sverker 
Published: January 2005

AbstractThe muscle contraction of the anterior tibial muscle was investigated by measurements of electrically stimulated and computer‐analyzed muscle twitches in 18 unselected patients with primary hyperparathyroidism (HPT) and in 20 healthy control persons. The HPT patients had a lower muscle twitch tension (TT) at single stimulation, compared with the control group [76 ± 24 N (SD) and 99 ± 33 N respectively, P < 0.05]. At high‐frequency stimulation the difference in muscle force increased, and at 20 Hz stimulation the force in the HPT patients was 73% of that in the controls (P < 0.01). There were no differences between the HPT patients and the control persons in neither contraction time nor half relaxation time at single muscle twitch nor in twitch potentiation after 20 and 90 seconds maximal voluntary contraction. The results indicate that patients with primary HPT have an impaired muscle function of probable importance for their symptoms of weakness and generalized fatigue.
The thoracic outlet syndrome: Controversies, overdiagnosis, overtreatment, and recommendations for management
Authors: Cuetter Albert C. , Bartoszek David M. 
Published: January 2005

AbstractThis review is an objective critique of the thoracic outlet syndrome, with emphasis on the need to separate true neurogenic and vascular syndromes from nonspecific ones. Major controversies in the diagnosis and management of thoracic outlet syndromes are discussed, with an analysis of major pitfalls encountered in the diagnosis and treatment of patients with nonspecific syndromes. Recommendations to improve diagnostic methods in patients with chronic neurovascular abnormalities in the upper extremities are outlined.
Autosomal recessive motor and sensory neuropathy with excessive myelin outfolding
Authors: Ohnishi Akio , Murai Yoshiyuki , Ikeda Masato , Fujita Tsutomu , Furuya Hirokazu , Kuroiwa Yoshigoro 
Published: January 2005

AbstractTwo Japanese persons with consanguinous parents had a motor and sensory neuropathy of the hypertrophic type with excessive myelin outfolding in the myelinated fibers. A morphometric analysis of the biopsied sural nerve was made. Excessive myelin outfolding, segmental demyelination, and re‐myelination and decrease in the density of both large and small myelinated fibers were evident. Using linear regression, myelin spiral length was shorter relative to axonal area. These patients may have a new variant of hereditary motor sensory neuropathy.
Localization of dystrophin in cultures of human muscle
Authors: Ecob‐Prince Marion S. , Hill Mark A. , Brown Aileen E. 
Published: January 2005

AbstractDystrophin is a protein present in normal human muscle but absent in patients with Duchenne muscular dystrophy (DMD). Using a specific antibody, we have investigated the expression of dystrophin in human muscle which had regenerated in culture in the presence of nerve cells. Dystrophin was present and was correctly localized in the cultures of normal muscle but was absent from cultures of muscle from patients with DMD. Its control and function can now be studied.
Modulation of the bulbocavernosus reflex during voiding: Loss of inhibition in upper motor neuron lesions
Authors: Sethi Rajesh K. , Bauer Stuart B. , Dyro Frances M. , Krarup Christian 
Published: January 2005

AbstractThe bulbocavernosus reflex (BCR) is a sacral segmental reflex which is suppressed throughout most of micturition. The BCR was evaluated by recording the associated EMG activity using a concentric needle electrode placed in the external urethral sphincter. The influence of the central nervous system (CNS) on the BCR was studied in 29 neurologically normal individuals and in 33 patients with upper motor neuron (UMN) lesions and voiding dysfunction. Ninety percent (26/29) of the neurologically normal patients did not have a BCR during most of micturition. By comparison, all the patients with an UMN lesion had a positive BCR beginning early during voiding. The finding of suprasegmental modulation of the BCR during voiding demonstrated by external urethral sphincter EMG was a more sensitive although slightly less specific sign of UMN bladder dysfunction than detrusor sphincter dyssynergia; uninhibited bladder contractions were neither sensitive nor specific for UMN lesions.
Sparing of the flexor carpi ulnaris in ulnar neuropathy at the elbow
Authors: Campbell William W. , Pridgeon Rhonda M. , Riaz Ghazala , Astruc Juan , Leahy Marilyn , Crostic E. Gay 
Published: January 2005

AbstractA common misconception attributes sparing of the flexor carpi ulnaris (FCU) in ulnar neuropathy at the elbow (UNE) to its innervating branch arising “at or above the elbow.” We examined the relationship of FCU branches to the medial epicondyle (ME) and humeroulnar aponeurotic arcade (HUA) in 30 cadaver elbows. In only three did the first FCU branch arise at or proximal to the ME. In 36 UNE cases with fibrillations in the first dorsal interosseous, the FCU was normal in 10, mildly abnormal in 11, and severely abnormal in 15. FCU involvement correlated with the severity of the neuropathy and with whether compression was retroepicondylar or at the HUA. We conclude that sparing of the FCU in UNE is unrelated to the level of origin of its innervating branch, but rather is related to the internal neural topography and to the severity and level of compression.
Functional evaluation of acute vincristine toxicity in rat skeletal muscle
Authors: Di Gregorio Franco , Favaro Giorgio , Fiori Mario G. 
Published: January 2005

AbstractVincristine sulfate (VCR) was administered intravenously to rats at doses of 0.25, 0.5, and 0.75 mg/kg. During the first week following VCR treatment, extensor digitorum longus (EDL) muscle contraction strength and fiber electrophysiologic parameters were measured. At all doses tested, VCR strongly reduced twitch and tetanic tension. EDL fiber resting membrane potential was affected in a dose‐dependent manner, and membrane depolarization was associated with the loss of excitability. Local membrane hyperpolarization by intracellular current application restored the capacity to produce action potential (AP). However, to elicit APs with a normal rate of rise, polarizing current had to be maintained for 3–5 minutes, indicating that the removal of Na+ channel inactivation followed a slow kinetics. Minor alterations in spontaneous synaptic transmission and in evoked transmission during high‐frequency repetitive stimulation were seen only at the highest dose. It is suggested that VCR impairs skeletal muscle function by affecting primarily the contractile apparatus, whereas sarcolemmal alterations are evident at increased doses of the drug.
Excitation contraction coupling in normal and mdx mice
Authors: Hollingworth Stephen , Marshall Michael W. , Robson Eliska 
Published: January 2005

AbstractThe protein dystrophin is absent from patients with Duchenne muscular dystrophy and from the muscles of mdx mice. Recent studies have shown that dystrophin is located at the surface membrance and at the triadic junction, where it is associated with the transverse tubular membrane. Since the triadic junction is the site of excitation‐contraction (EC) coupling, we have investigated whether intramembrane charge movement, a step in EC coupling, is modified by the absence of dystrophin. Charge movements are thought to arise from the transverse tubular membrane and to underlie the dependence of sarcoplasmic reticulum Ca2+ release on transverse tubular membrane potential. We find no differences between intramembrane charge movements or passive membrane electrical properties measured in muscles from mdx mice compared with normal mice. If dystrophin does play a role in EC coupling, that role is likely to be subsequent to the charge movement step.
Excessive plasma K+ increase after ischemic exercise in myotonic muscular dystrophy
Authors: Wevers Ron A. , Joosten Ed M. G. , van de Biezenbos J. B. Margot , Theewes Ad G. M. , Veerkamp Jacques H. 
Published: January 2005

AbstractChanges in plasma electrolyte levels upon ischemic forearm exercise were studied in myotonic muscular dystrophy (MyD) patients, disease control groups, and healthy volunteers. Significant differences were observed in the pH and the concentrations of creatine kinase and Na+ before exercise between healthy volunteers and MyD patients. In comparison with healthy volunteers a lower pH and higher concentrations of both CK and Na+ were found in MyD patients. The concentrations of K+, inorganic phosphate, lactate, and ammonia increase upon exercise in all groups. The mean increase in plasma K+ for healthy volunteers amounted to 0.8 mM (=23%). In MyD patients a significantly higher increase in plasma K+ was found [mean 2.2 mM (= 65%)]. No abnormal release of K+ from muscular tissue was found in the disease control groups. Data on the postexercise increase in the concentration of other muscular constituents such as creatine kinase, inorganic phosphate, or creatine exclude the possibility of a generally increased membrane permeability in MyD. The abnormally high increase of plasma K+ upon muscular exercise seems to be specific for MyD and may be related to the biochemical defect in this disease.