bluuebunny/crossref_metadata_2025 huggingface dataset:
Acetylcholine sensitivity in replicating satellite cells
Authors: Eusebi Fabrizio , Molinaro Mario
Published: January 2005

Mononucleate myogenic cells lying within skeletal muscle fiber endomysium, the so‐called satellite cells (SC), isolated from adult leg muscle of normal or dystrophic mice were studied by electrophysiological techniques. Normal SC responded to iontophoretic acetylcholine (ACh) by depolarization even during the replicative phase. Acetylcholine sensitivity increased after cell fusion. Replicating SC from dystrophic muscle did not exhibit and sensitivity to ACh, and neither did embryonic myoblasts.
An electron microscopical study of the T‐system in biopsied muscles from fukuyama type congenital muscular dystrophy
Authors: Miike Teruhisa , Ohtani Yoshinobu , Tamari Hideo , Ishitsu Takateru , Nonaka Ikuya
Published: January 2005

The behavior of the tubular system in muscles from six patients with Fukuyama type congenital muscular dystrophy (FCMD) was examined by electron microscopy using a lanthanum nitrate stain for a comparison with that in Duchenne muscular dystrophy (DMD). In FCMD, many fibers showed morphological changes of the T‐system as follows: aggregated tubular components forming honeycomb‐like structures, focal dilatation of T‐tubules with tangle formation, and numerous longitudinally projecting tubules, which were quite similar to those found in cases with DMD. The fibers with abnormal T‐systems occasionally showed ultrastructural characteristics of regenerating fibers, including excessive ribosome particles, immaturely organized myofibrils, and an increased number of internal nuclei and satellite cells. The present results suggested that there was no qualitative difference in the behavior of the T‐system between FCMD and DMD, and the morphological changes of the T‐system in dystrophic muscles were not primary lesions initiating myonecrosis but reflected the behavior of sarcotubular formation in the process of muscle regeneration.
Myoglobin in rat hind limb muscles after denervation and during reinnervation
Authors: Askmark Håkan , Carlson Marie , Roxin Lars‐Eric
Published: January 2005

Radioimmunoassay of myoglobin (Mb) was performed in rat hind limb muscles after surgical denervation and during reinnervation following cryolesion of the sciatic nerve. Muscles of the contralateral leg served as controls. After resection of the sciatic nerve, decreased Mb concentrations were noted on the fourth day in the tibialis anterior, peroneus longus, and extensor digitorum longus (EDL) muscles. Thereafter, the levels increased up to the last observation on day 32. The increases in Mb levels in the tibialis anterior and EDL muscles were considerably more pronounced (305% and 324%, respectively) than in the peroneus longus and soleus muscles (148% and 137%, respectively). After cryolesion of the sciatic nerve, the Mb concentrations in the tibialis anterior, peroneus longus, and EDL muscles increased, reaching maximal values on days 16–21. The levels then decreased and normal values were observed 2 months postoperatively. The normalization of the Mb levels during reinnervation corresponded fairly well in time with the clinical recovery and neurophysiological findings observed in a previous study.
The development of central cores in both fiber types in tenotomized muscle
Authors: Baker James H.
Published: January 2005

Using the histochemical reaction for myosin adenosine triphosphatase (ATPase), a study of the rat soleus muscle following tenotomy was undertaken. It was demonstrated that both type 2A and 2C fibers undergo degenerative changes following tenotomy. All previous studies have stated that only type 1 fibers were affected and developed central core lesions and that type 2 fibers were somehow protected from the degenerative process. The results of this experiment illustrate that central core lesions will develop in all three fiber types (types 1, 2A, and 2C) of the soleus following tenotomy.
Treatment of refractory chronic demyelinating polyneuropathy with lymphoid irradiation
Authors: Rosenberg Neil L. , Lacy Joseph R. , Kennaugh Ralph C. , Holers V. Michael , Neville Hans E. , Kotzin Brian L.
Published: January 2005

Four patients with refractory or poorly responsive chronic progressive demyelinating polyneuropathy (CPDP) were treated with total lymphoid irradiation (total dose, 2000 rad) in an uncontrolled feasibility study. All patients had previously failed conventional therapy for CPDP, as well as other unconventional treatments. During a follow‐up period of 7 to 12 months after total lymphoid irradiation, there was a profound and sustained suppression of the absolute lymphocyte count and in vitro lymphocyte function, as well as an increase in the ratio of Leu‐2 (suppressor/cytotoxic subset) to Leu‐3 (helper/inducer subset) T cells in the blood. Three of the four patients demonstrated improvement in distal muscle strength, and this was associated with increased functional capabilities in two patients. In contrast, no clinical improvement in sensation was noted in any patient. Nerve conduction studies showed patchy improvement in three patients. The results of this preliminary uncontrolled study indicate that radiotherapy deserves further study in the treatment of CPDP.
Polymyositis: Reduction of acetylcholine receptors in skeletal muscle
Authors: Pestronk Alan , Drachman Daniel B.
Published: January 2005

In polymyositis (PM), neither the precise target nor the mechanism of the attack against skeletal muscle have yet been defined. In this study, we report evidence of a pathologic process involving a membrane component of muscle, acetylcholine receptors (AChRs). Our results show that PM patients have significantly reduced AChRs at neuromuscular junctions, averaging 55% below control values (P < 0.001). Incubation of cultured mammalian muscle cells with sera from PM patients significantly reduced (P < 0.005) the number of surface AChRs and increased their rate of degradation in 7/8 cases (P < 0.005). Similar effects were produced by purified lgG from PM patients. These results demonstrate the presence in PM patients of circulating lgG with functional effects on a component of the surface membrane of skeletal muscle. They suggest that PM and myasthenia gravis may have important features in common.
Tubular aggregates: Sarcoplasmic reticulum origin, calcium storage ability, and functional implications
Authors: Salviati Giovanni , Pierobon‐Bormioli Sandra , Betto Romeo , Damiani Ernesto , Angelini Corrado , Ringel Steven P. , Salvatori Sergio , Margreth Alfredo
Published: January 2005

Muscle biopsy specimens from three patients with an autosomal dominant myopathy and tubular aggregates in both type 1 and type 2 fibers16 were investigated for immunofluorescent staining with antibodies to sarcoplasmic reticulum (SR) Ca‐pump protein and calsequestrin and for Ca2+ loading ability. The results show that type 1 and type 2 fibers are differentially reactive to anti–ca‐pump protein lgG and similarly reactive with affinity‐purified antibody to calsequestrin, which is in agreement with earlier observations in rat skeletal muscle.8 Tubular aggregates, which are shown to be highly reactive with either kind of antibody, appear to be sites of calcium accumulation for oxalatefacilitated adenosine triphosphate (ATP) dependent Ca uptake by chemically skinned fibers and thereby increase markedly the Ca loading capacity of the affected fibers.
PC12 cells stimulate slow‐myosin light chain 2 synthesis in chick breast muscle culture
Authors: Glass Charles A. , Walker Charles , Strohman Richard C.
Published: January 2005

Skeletal muscle fibers developing in vitro synthesize predominantly fast‐myosin light chains, with a small contribution (less than 10%) from slow‐myosin light chain 2. Muscle fibers can be cocultured with a rat adrenal pheochromocytoma‐derived nerve cell line (PC12) known to display properties similar to sympathetic neurons. PC12 cells cultured alone synthesize catecholamines and respond to nerve growth factor by synthesizing acetylcholine and extending neurite structures. They also synthesize significant amounts of acetylcholine in the presence of nonneuronal cell types, including muscle. When cocultures of skeletal muscle fibers and PC12 cells are established, the muscle cells respond with an increased level of slow light chain 2 synthesis. Myosin light chains were identified by two‐dimensional gel electrophoresis and immunoblotting with an antiserum specific to slow light chain 2.
Contractile properties of standard and nerve‐intact muscle grafts in the rat
Authors: Faulkner John A. , Carlson Bruce M.
Published: January 2005

The contractile properties of standard and nerve‐intact grafts of extensor digitorum longus muscles of rats were compared in vitro. Fourteen days after grafting, the time to peak tension and the half‐relaxation times of nerve‐intact grafts were shorter than those of standard grafts, but both were longer than control values. By 60 days, these variables attained normal values. At every sample period, the tetanic tensions of nerve‐intact grafts were higher than those of standard grafts. Even at the early sampling periods, the twitch‐tetanic tension ratios of nerve‐intact grafts were close to normal values, whereas those of standard grafts were higher than normal. Stabilized nerve‐intact grafts had a larger mass and greater maximum tetanic tension development than standard grafts, but were more fatigable. Compared with control EDL muscles, stable nerve‐intact grafts show no differences except for lessened fatigability, whereas standard grafts demonstrate significant functional deficits.
HLA‐DR expression, T lymphocyte phenotypes, OKM1 and OKT9 reactive cells in inflammatory myopathy
Authors: Olsson Tomas , Henriksson Karl G. , Klareskog Lars , Forsum Urban
Published: January 2005

Frozen muscle biopsy sections from 13 patients with inflammatory myopathy and from four healthy volunteers were characterized with a double immunohistochemical staining technique, utilizing a panel of antisera to cell surface antigens. The technique enables simultaneous visualization of HLA‐DR reactive cells and other cell types, i.e., T lymphocytes. In inflammatory myopathy, large numbers of HLA‐DR reactive “macrophage/dendritic” cells were shown. Almost all other inflammatory cells and endothelial cells also expressed HLA‐DR, as did the sarcolemma in the vicinity of inflammatory foci. Large numbers of T lymphocytes were detected by αLeu‐1 antibodies. In most instances, Leu‐3a reactive T “helper” lymphocytes dominated over αLeu‐2a reactive T “suppressor/cytotoxic” lymphocytes. Many T lymphocytes of both phenotypes appeared in close contact with HLA‐DR expressing non‐T cells. OKM1 and OKT9 antibodies, labeling macrophages and “proliferating” cells, respectively, were common among inflammatory cells. The findings provides basic data that are important for the understanding of inflammatory myopathy.
Posterior interosseous syndrome revisited
Authors: Carfi Joseph , Ma Dong M.
Published: January 2005

The question of how the supinator syndrome and the posterior interosseous syndrome are (or are not) related has not been well discussed in the literature. The anatomy of the radial nerve and its innervations is quite variable, as are the etiology, presentation, and clinical findings in the lesions of the posterior interosseous nerve. The present study was based on a retrospective review of the electrodiagnostic records of 12 patients with involvement of the deep radial nerve (posterior interosseous nerve) diagnosed at the EMG lab of New York University Medical Center from 1975 to 1983. Two‐thirds of these patients had electrophys iologic abnormalities of the supinator muscle, and in the remainder, the supinator was not involved. All superficial radial nerves had normal evoked mode action potential amplitudes and latencies. We propose that the supinator syndrome is a special case of the posterior interosseous syndrome.
Cultured rat spinal cord neurons: Interaction with motor neuron disease immunoglobulins
Authors: Digby John , Harrison Roger , Jehanli Ahmed , Lunt George G. , Clifford‐Rose F.
Published: January 2005

Conditions have been developed for the culture of rat spinal cord neurons in serum‐free media supplemented with hormones and growth factors. Neurons were identified by immunofluorescence‐labeled antineurofilament antibody, and their growth was monitored by assay of choline acetyltransferase and cholinesterase activities. Activities of these enzymes were considerably higher than those of comparable cultures in serum supplemented media in which there were visibly many more nonneuronal cells. Serum immunoglobulins from patients with motor neuron disease showed enhanced binding to rat spinal cord cells maintained in both serum‐supplemented and serum‐free media, as compared with those from normal healthy individuals. Enhanced binding was more marked with the latter cells, presumably because of the higher proportion of neuronal cells in these cultures. Serum immunoglobulins from patients with other neurologic disorders showed a similar binding to that of the normal controls. The results demonstrate the presence of an immune response to spinal cord cell membrane components in patients with motor neuron disease, although whether the response is primary or secondary in the disease process remains unclear.
Neonatal spinal muscular atrophy presenting as respiratory distress: A clinical variant
Authors: Schapira D. , Swash M.
Published: January 2005

Respiratory distress from diaphragmatic and intercostal muscular weakness was the presenting feature of two neonates with progressive spinal muscular atrophy, leading to death in the first 2 months of life. This atypical feature provides evidence of heterogeneity within the commonly used clarification of type 1 spinal muscular atrophy.
Morphometric studies of normal sural nerves in children
Authors: Ferriere Gerard , Denef Jean‐François , Rodriguez Jorge , Guzzetta Francesco
Published: January 2005

Quantitative histologic studies of biopsies of normal sural nerves were performed on nine children aged 4 days to 17 years. Stereologic computerized procedures were used to determine total endoneurial area, size distribution and number of myelinated, unmyelinated fibers and Schwann cell nuclei per nerve and per square millimeter, and the ratio of myelin thickness to axonal diameter. There was an inverse linear relationship between the number of myelinated fibers per square millimeter and increasing age. A stronger correlation was found between the number of Schwann cell nuclei per nerve (P < 0.01) and per square millimeter (P < 0.001) and the logarithm of age. The slope of myelin thickness/axon diameter regression lines (P < 0.001) changed with age in linear relationship (correlation coefficient: P < 0.001). There were no age‐dependent changes in the number and density of unmyelinated fibers, but the number of unmyelinated axons per Schwann cell subunit decreased with age. Size distribution histograms for myelinated fibers showed a unimodal profile in the newborn. A second peak at 6–7 m̈m appeared at age 3 months, shifting progressively to 9–11 m̈m at 14 years. The distribution of unmyelinated fibers was unimodal, with a peak around 0.8 m̈m, irrespective of age. There were marked individual variations in endoneurial area.
Familial amyloid polyneuropathy
Authors: Koeppen Arnulf H. , Mitzen Edward J. , Hans Mary B. , Peng Shi‐Kaung , Bailey Ronald O.
Published: January 2005

Amyloid fibrils were isolated from the myocardium of two patients with familial amyloid polyneuropathy. The solubilized amyloid fibril whole protein shared immunologic determinants with normal human serum prealbumin (transthyretin), but revealed subtle differences on immunoelectrophoresis and radial immunodiffusion. On sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, amyloid fibril whole protein was resolved into numerous bands that reacted with antitransthyretin on immunoblots. The whole protein also contained peptide fragments of fibronectin, but was devoid of amyloid P protein. An antiserum raised against the whole protein was suitable for immunocytochemistry of amyloid in paraffin sections. In contrast, commercial antitransthyretin, raised against the intact tetrameric protein failed to react with tissue amyloid. Immunochemical and immunocytochemical results support the concept that familial amyloid polyneuropathy with cardiomyopathy is due to infiltration of susceptible tissues by an anomalous transthyretin.
Simultaneous measurement of muscle conduction velocity and emg power spectrum changes during fatigue
Authors: Eberstein Arthur , Beattie Bradley
Published: January 2005

Muscle conduction velocity and mean frequency of the electromyogram (EMG) spectrum were measured simultaneously in the biceps brachii muscles of nine healthy subjects during sustained isometric contraction. Recordings were made at 60% and 70% of the maximum voluntary contraction In all subjects, both conduction velocity and mean frequency decreased during the time period of the fatiguing contractions. Also, the muscle conduction velocity was found to vary linearly with the mean frequency. This demonstrates that the EMG spectral shifts observed during muscle fatigue are due to slowing of the conduction velocity.
Plasma creatine kinase changes after eccentric and concentric contractions
Authors: Newham D. J. , Jones D. A. , Edwards R. H. T.
Published: January 2005

This study was undertaken to determine whether the large delayed creatine kinase (CK) rise, previously only reported in normal subjects after stepping exercise, was caused by the eccentric or concentric contractions. On separate occasions, five normal subjects performed the same amount of total work by walking either up (mainly concentric contractions) or down (mainly eccentric contractions) a treadmill inclined at 13°. After uphill walking, peak plasma CK values of 60–200 IU/liter occurred 24 hours after exercise. Downhill walking resulted in peak values of 700–1500 IU/liter 4–7 days later. It is concluded that it is the eccentric contractions that are responsible for the large enzyme efflux.
Noninvasive measurement of spinal cord conduction: Review of presently available methods
Authors: Eisen Andrew A.
Published: January 2005

The ability to measure spinal cord conduction velocity noninvasively is limited by available methodology. Surface recording of small spinal potentials, although feasible in infants and young children, is problematical in adults, especially when recording over the cervical spine. On the other hand, indirect methods designed to improve the signal‐to‐noise ratio, which include recording of somatosensory cortical evoked potentials, F‐waves, or other muscle responses, are limited by the unproven assumptions necessary in calculating spinal conduction. Additionally, each method has its own particular limitations. The majority of presently available noninvasive methods take a restricted, or no, account of conduction through the motor pathways. Despite these often serious limitations, each of the reviewed methods does play a useful clinical role in the electrophysiologic investigation of cord disease that is not visible radiologically. Knowledge of them allows for sufficient diversity to tackle most relevant problems until an ideal physiologic method is developed.
Effect of exercise on the motor unit
Authors: Edström Lars , Grimby Lennart
Published: January 2005

The motoneuron part of this review deals with the changes in recruitment and firing rates of the motor unit types upon changes from a physically inactive life to endurance or strength training. The muscle fibers react to prolonged exercise by adaptation to a higher level of performance. A matter of discussion is the prerequisites for a transformation between the basic muscle fiber types, slow twitch and fast twitch, during voluntary (transsynaptic) activity, which is demonstrated after artificial nerve stimulation. The review includes current knowledge of muscle fiber transformation as an adaptive response to increased usage either by electrical stimulation or by transsynaptic neuronal activity. The metabolic adaptation related to increased endurance is reviewed with special reference to effects on muscle fibers. The increase in strength as a result of high resistance training is mainly the result of increased muscle cross‐section. Whether this is solely the result of an increase in size of individual fibers or an increased fiber number is a controversial matter.
Effects of stretch and starvation on glucose uptake of rat soleus and extensor digitorum longus muscles
Authors: Shoji Shin'ichi
Published: January 2005

To examine the effects of stretch and starvation on muscle carbohydrate metabolism, glucose uptake was measured using [3H]3‐O‐methylglucose. Glucose uptake was higher in the stretched condition, and more so in soleus muscle than in extensor digitorum longus. After 4 days of starvation, glucose uptake decreased significantly in soleus muscle, but in extensor digitorum longus muscle, glucose uptake per noncollagen protein increased.
[3H]Nitrendipine receptors as markers of a class of putative voltage‐sensitive Ca2+ channels in normal human skeletal muscle and in muscle from duchenne muscular dystrophy patients
Authors: Desnuelle Claude , Renaud Jean‐François , Delpont Eric , Serratrice Georges , Lazdunski Renaud Delpont , Lazdunski Michel
Published: January 2005

Properties of nitrendipine receptors have been analyzed in skeletal muscle from normal young boys and boys with Duchenne muscular dystrophy (DMD). The dissociation constant (Kd) of the complex formed by nitrendipine with its specific receptors was 0.5 ± 0.1 nM in dystrophic muscle and 0.4 ± 0.1 nM in normal muscle. Maximum binding capacities Bmax were 403 ± 80 and 460 ± 60 fmol/mg protein in DMD and normal muscle, respectively. These results suggest that nitrendipine binding sites on nitrendipine‐sensitive Ca2+ channel binding sites are not altered in Duchenne muscular dystrophy.
Selective synthesis and degradation of slow skeletal myosin heavy chains in developing muscle fibers
Authors: Dhoot Gurtej K.
Published: January 2005

During fetal development of fast skeletal muscles in the rat, three types of cells could be identified using a monoclonal antibody to slow skeletal muscle myosin heavy chain. Presumptive type I cells stained positive for slow forms of skeletal myosin heavy chain and a previously described protein5 of an apparent molecular weight of 100 KD, whereas presumptive type 2B cells did not stain for either of these peptides. Presumptive type 2A cells, on the other hand, did not stain for slow isoform of 100‐K protein, but did stain positive for slow skeletal myosin heavy chain. There was a progressive suppression or degradation of slow skeletal myosin heavy chain in presumptive type 2A cells during subsequent fetal development, so that it was almost undetectable in most animals at birth. Soleus, a slow muscle, however, did not show clear differentiation into presumptive type I and type 2 cells until 4 days after birth.
Porcine malignant hyperthermia: Cell injury enhances halothane sensitivity of biopsies
Authors: Gallant Esther M. , Fletcher Thomas F. , Goettl Virginia M. , Rempel William E.
Published: January 2005

A possible relationship between muscle cell injury or deterioration and enhanced halothane sensitivity was studied by monitoring mechanical responses of skeletal muscles from normal pigs and pigs susceptible to malignant hyperthermia (MH). Increased time postbiopsy and decreased maximum control tetanic tension both correlated significently with enhanced sensitivity to halothane. In both normal and MHsusceptible (MHS) muscles, greater halothane sensitivity was observed in cut cell than in intact cell bundles and in low tetanic tension as compared to high tension preparations. Subsequent to halothane exposure, twitches of high tension (≥ 1.75 kg · cm −2) intact bundles of both normal and MHS muscles were potentiated. Tetani of normal intact bundles were not altered, whereas those of MHS bundles were depressed after halothane exposure. Control twitch‐to‐tetanus ratios (twitch ratios) were higher in MHS (0.23) than in normal (0.12) intact bundles. According to discriminant analysis, the best distinction between normal and MHS muscles, either cut or intact, was obtained by comparing halothane‐induced changes in tetanic tension and control twitch ratios.
Targeting of lysosomal enzymes: N‐Acetylglucosamine‐1‐Phosphotransferase during muscle development
Authors: Den Halina , Shanske Sara , Dimauro Salvatore
Published: January 2005

It has been previously shown by morphological techniques and measurements of lysosomal enzyme levels that the I cell mutation is expressed in myoblasts but not in myotubes or mature muscle fibers. These findings suggested the possibility of developmental regulation of the affected enzyme, UDP‐N‐acetylglucosamine: lysosomal enzyme N‐acetylglucosamine‐phosphotransferase. In this article, we examine this possibility by measuring the phosphotransferase activity at various stages of muscle differentiation in three different animal species (human, chick, rat). Although activity of the enzyme is consistently higher in myoblasts than in myotubes or mature muscle, the difference in the levels of activity at these three states of muscle differentiation varies widely in the three species examined. We further found that the phosphotransferase activity was absent in the muscle of an I cell patient, in spite of normal muscle morphology. This indicates the presence of a mannose‐6‐phosphate‐independent mechanism for lysosomal enzyme targeting in muscle and other unaffected tissues. The existence of such a pathway cannot be explained by lack of the necessary enzyme, as the phosphotransferase is present at a comparable level in normal muscle of three different species (human, chick, rat).
Disturbances of neural conduction in isolated frog nerves following exposure to strong electric fields
Authors: Eickhorn Roland , Haverkampf Klaus , Antoni Hermann
Published: January 2005

Frog sciatic nerves were isolated and the middle portion of each exposed to condenser discharges (field strength up to 1000 V/cm; time constants 0.2–8.0 ms) through the bathing fluid. The ability of the nerve to propagate action potentials (AP) was examined by stimulating the proximal end and recording the AP from the distal end of the exposed section. The fraction of the nerve fibers remaining propagative was estimated from the amplitude (or the area) of the compound AP. Strong discharges brought about a total block of propagation lasting for up to 30 minutes, followed by slow, but almost complete, restitution. The restitution was exponential against time and depended on the field strength and duration of the discharge. Discharges equal in energy but different in their voltage—condenser combinations had markedly different actions, with stronger effects being found at higher voltages and vice versa. Hence, the described effects are unlikely to be caused by dissipation of thermal energy only. Other mechanisms (ionic imbalance, dielectric breakdown, punch through) are discussed.
Developmental study of α‐glucosidases in japanese quails with acid maltase deficiency
Authors: Usuki Fusako , Ishiura Shoichi , Sugita Hideo
Published: January 2005

In Japanese quails with late‐onset acid maltase deficiency (AMD), the activity of acid α‐glucosidase was severely reduced to approximately 16% of the normal level from an embryonic age. The kinetic characteristics and inhibition by Zn indicated that the residual activity was responsible for the intrinsic activity of acid α‐glucosidase. However, in affected embryos, the glycogen content and other lysosomal enzyme activities were normal, despite the low acid α‐glucosidase activity. In a separate study, we found the existence of two age‐dependent neutral α‐glucosidases— “embryonic” and “adult” α‐glucosidases. In affected quails, the transition from the embryonic neutral α‐glucosidase to the adult type was not influenced by the disease. The activity toward maltose and glycogen of the embryonic neutral α‐glucosidase may explain the normal glycogen content in the affected embryos.
Clinical investigation in duchenne dystrophy. VI. Double‐blind controlled trial of nifedipine
Authors: Moxley Richard T. , Brooke Michael H. , Fenichel Gerald M. , Mendell Jerry R. , Griggs Robert C. , Miller J. Philip , Province Michael A. , Patterson Victor ,   CIDD Group
Published: January 2005

Excessive accumulation of intracellular calcium in Duchenne muscular dystrophy (DMD) may be a necessary step in the process that causes muscle damage in this disease. Because of this possibility, a controlled trial of the calcium channel blocking agent nifedipine was undertaken. One hundred and five patients were randomized and treated in a double‐blind manner for 18 months. Muscle strength, contractures, functional ability, cardiopulmonary changes, and laboratory data were monitored. The dose of nifedipine was 0.75‐1 mg/kg/day in the first 6 months and 1.5‐2 mg/kg/day for the next 12 months. Satisfactory blood levels of nifedipine were attained. The study had a power greter than 0.99 to detect a slowing of the illness to 25% of its original rate of progression. No significant improvement was demonstrated in the treated group. One or more of the frequent mild side effects of flushing, dizziness, and leg edema, often associated with the use of nifedipine in adults, occurred transiently in approximately one‐half of the patients in the nifedipine group and in 21% of the placebo group. Four patients died, two on nifedipine and two on placebo. This study demonstrates that nifedipine is safe to administer in children, but that it is without beneficial effect on the course of DMD.
Neuralgic amyotrophy: An increasingly diverse entity
Authors: England John D. , Sumner Austin J.
Published: January 2005

We describe nine cases of neuralgic amyotrophy whose clinical and electrophysiologic findings suggest lesions of individual peripheral nerves or peripheral nerve branches occurring singly (mononeuropathy) or in various combinations (mononeuropathy multiplex). There were four occurrences of isolated denervation of the pronator teres muscle; four occurrences of anterior interosseous nerve lesions; three occurrences of lateral antebrachial cutaneous nerve lesions; two occurrences of long thoracic nerve lesions; and one occurrence each of a median nerve trunk lesion, a median palmar cutaneous branch lesion, a suprascapular nerve lesion, and an axillary nerve lesion. “Neuralgic” pain was a prominent feature in all cases, and the location of the pain correlated with the location of the nerve lesions. We hypothesize that the specific course of certain nerves (especially their location across joints) selectively exposes them to mild focal trauma that increases their susceptibility to this disease. Whatever the etiology, this entity is considerably more diverse than generally appreciated.
Dantrolene sodium is able to reduce the resting ionic [Ca2+]i In muscle from humans with malignant hyperthermia
Authors: López José R. , Medina Pablo , Alamo Lorenzo
Published: January 2005

Malignant hyperthermia (MH) is a hereditary myopathy, triggered when susceptible patients are exposed to a depolarizing muscle relaxant and/or potent volatile anesthetics. We have studied the effects of dantrolene on the free [Ca2+]i of intercostal muscle biopsies obtained from two MH‐susceptible patients before and after administration of dantrolene orally (2.5 mg/kg for 3 days) and intravenously (1.0 mg/kg 2 hours before the biopsy). The free [Ca2+]i was measured by Ca2+‐selective microelectrodes. The mean resting free [Ca2+]i in the MH‐susceptible muscle before dantrolene treatment was 0.42 ± 0.01 μM (mean ± SEM, n = 12). The administration of dantrolene reduced this value to 0.27 ± 0.01 μM (n = 14). There was no detectable difference in the resting membrane potential after dantrolene. These results represent the first direct demonstration that dantrolene is able to reduc the resting free [Ca2+]i in skeletal muscle of MH‐susceptible patients.
Demyelination in vivo by Guillain‐Barré Syndrome and other human serum
Authors: Brown Mark J. , Rosen Janet L. , Lisak Robert P.
Published: January 2005

Serum from patients with acute inflammatory polyneuropathy (the Guillain‐Barré syndrome, GBS) demyelinates peripheral nerves in vivo more intensely than control human serum. To clarify the processes leading to demyelination we injected rat sciatic nerves with serum from GBS and control subjects in the presence of complement and examined the sequential morphologic changes over 7 days. One day after injection, five of six GBS sera but none of seven control sera caused vesicular demyelination; 3–5 days after injection both GBS and control sera produced macrophage‐mediated demyelination. These observations suggest that GBS serum can initiate acute myelin injury through a humoral mechanism that is disease associated. This response appears to be distinct from delayed cell‐mediated serum‐induced demyelination that is not disease specific.
The neurophysiologic investigation of small fiber neuropathies
Authors: Jamal Goran A. , Hansen Stig , Weir Andrew I. , Ballantyne John P.
Published: January 2005

We have applied our technique for the measurement of thermal thresholds to 25 patients referred with symptoms and signs of small fiber peripheral neuropathy in whom conventional electrophysiological indices were individually within the range of normal values for our laboratory. Vibration threshold determinations were also within normal range. Significant abnormalities of thermal thresholds were noted in all patients.

The results indicate that the technique provides an accurate, easily performed and reproducible index of function in small Aδ and C groups of nerve fibers.
Prostaglandin E2 and the regulation of protein degradation in skeletal muscle
Authors: Barnett J. G. , Ellis S.
Published: January 2005

We tested the influence of PGE2 on protein degradation in isolated mouse and rat muscles. PGE2 had no influence on protein degradation rate in mouse muscles under several different incubation conditions and over a dose range of 28 nM to 28 μM. Furthermore, neither PGE2 (2.8 μM) nor arachidonic acid (5 μM) influenced protein degradation in rat muscles under incubation conditions identical to those previously reported. The biological activity of our PGE2 was confirmed with the rat stomach fundic strip preparation. We question the contention that PGE2 regulates protein degradation in skeletal muscle.
Staircase, fatigue, and caffeine in skeletal muscle in situ
Authors: Macintosh Brian R. , Kupsh Christine C.
Published: January 2005

The 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

The 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

A 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

We 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

Motor 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

The 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

A 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

Dorsiflexion 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

The 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

In 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

Myology 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

A 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

The 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.