bluuebunny/crossref_metadata_2025 huggingface dataset:
The misdiagnosis of unilateral presentations of amyotrophic lateral sclerosis
Authors: O'Reilly Daniel F. , Brazis Paul W. , Rubino Frank A.
Published: January 2005

Fifty‐eight patients with definite amyotrophic lateral sclerosis (ALS) were investigated retrosectivley. Variables investigated included the age of onset of motor symptoms, the sex of the patient, the presenting signs and symptoms, and the initial clinical diagnosis. The patients were separated by mode of onset into five clinical categories: I. Conventional or Classical (31%); II Predominantly bulbar (19%); III. Pseudopolyneuritic (5.2%); IV. Paraparetic (13.8%); and V. Hemiparetic or Mills' Variant (31%) presentations. The average age of onset of symptoms was 55.3 years, with little difference among the clinical groups except for a later age of onset in the bulbar form. The initial diagnosis of ALS was correct in 95% of the patients with a predominantly bilateral mode of onset of symptoms (the conventional, bulbar, and paraparetic groups) but was correct in only 38% of patients with predominantly unilateral onset (hemiparetic) and pseudopolyneutric forms. We suggest that the clinician be aware of these atypical, unilateral forms of ALS in order that an accurate diagnosis may be made.
F response latency determination
Authors: Fisher Morris A.
Published: January 2005

F response latencies were analyzed. Data were obtained from normal subject as well as in sequential studies recorded from the author. Based on series of 10 F responses, mean in comparision to minimal latency values are more reproducible and provide a statistically consistent measure of F wave conduction. The data also indicate an inherent variability in F wave latencies between groups of 10 responses. The results are consistent with F waves in normal subjects discharging from subpopulations of a motoneuron pool.
Membrane alterations in skeletal muscle fibers of dystrophic mice
Authors: Kerr Lynne M. , Sperelakis Nick
Published: January 2005

Skeletal muscle fibers from dystrophic mice and littermate controls (ReJ‐129) were characterized electrically and then injected with an intracellular marker. In this way they could be identified for examination with an electron microscope to correlate the relative time course of electrical and ultrastructural aherations resulting from the dystrophic process. On the average, dystrophic muscle fibers displayed decreased membrane potentials (−59 ± 1.2 vs −79 ± 0.7 mV for normals), decreased specific membrane resistivity (517 ± 27 vs 642 ± 34 Ω‐cm2 for normals), and depressed action potential (AP) maximum rates of rise (+Vmax) (352 ± 9 vs 417 ± 9 V/s for normals) and amplitudes (92 ± 1.2 vs 102 ± 1.0 mV for normals) at an experimentally polarized membrane potential of −90 mV. Membrane resistivity and AP +Vmax were decreased even in those fibers from dystrophic muscles that displayed normal ultrastructure (classified visually and by ratio of sarcoplasmic reticulum to total cell volume). These findings support the membrane hypothesis of muscular dystrophy that membrane lesions are the primary lesion in the disease process.
Clinical investigation in duchenne dystrophy: 2. Determination of the “power” of therapeutic trials based on the natural history
Authors: Brooke Michael H. , Fenichel Gerald M. , Griggs Robert C. , Mendell Jerry R. , Moxley Richard , Miller J. Philip , Province Michael A.
Published: January 2005

A prospective study of 114 patients with DMD provided data for “power” calculations for future therapeutic trials. There was a decline in strength of 0.4 units per year (on a 0‐10 scale). Contractures of the iliotibial bands, hip flexors, and heel cords developed before 6 years. Contractures of other joints accompanied the increased use of wheelchairs. All children walked until 8 years with functional “improvement” between 3–6 years. Children of the same age varied widely in their strength, degree of contracture, and functional abilities. Fifteen percent of the patients appear to have a milder variety of the disease and are termed “outliers.” To test a drug which might slow the disease to 25% of its original rate of progression, two groups (placebo and treatment) of 40 patients each would have to be followed for one year.
Increase of muscle peroxisomal enzymes and myotonia induced by nafenopin, a hypolipidemic drug
Authors: Behrens María Isabel , Soza Marco Antonio , Inestrosa Nibaldo C.
Published: January 2005

The chronic administration of nafenopin, a hypolipidemic drug, induced an increase in catalase and acyl‐CoA oxidase activities in various skeletal muscles, including the gracilis, diaphragm, soles, and extensor digitorum longus. The magnitude of the increase was around 100% for both enzymes in each of the muscles studied in spite of the different basal level. These changes seem to be specific of the peroxisomal enzymes because acetylcholinesterase, which is not peroxisomal, did not follow the same pattern in all the muscles. Concomitant with the increase in muscle peroxisomal enzymes, the skeletal muscles presented an altered electromyogram with prolonged insertional activity, repetitive firing of action potentials, and myotonic runs characteristic of myotonia. Our results suggest a role for peroxisomes in the myotonic disorder.
Multiple sclerosis and hypertrophic demyelinating peripheral neuropathy
Authors: Il Ro Young , Alexander C. Bruce , Oh Shin J.
Published: January 2005

A combination of multiple sclerosis (MS) and hypertrophic demyelinating neuropathy has been reported in a few autopsy studies. We are reporting a unique case of such a combination, which was proved by the sural nerve biopsy. A patient with classical MS on history and findings had areflexia and sensory abnormalities in stocking distribution. The nerve conduction study showed marked abnormalities indicative of demyelinating neuropathy, and sural nerve biopsy was typical of hypertrophic demyelinating neuropathy.
The dual connective tissue system of rat soleus muscle
Authors: Moore M. J.
Published: January 2005

Rat soleus muscle has two types of connective tissue associated with it which do not overlap except at the myotendinous junction. One, an areolar type, is restricted mainly to the spaces between muscle fibers and the other, a regular dense type, is located only beyond the ends of muscle fibers in structures called microtendons. The definitive tendon of a muscle thus represents the accumulation of all the microtendons, one of which is contributed by each muscle fiber. The diameter distributions were the same for collagen fibrils from areolar tissue and microtendons but different from tendon collagen. Marked changes occur in the diameter distribution of the microtendon collagen as it passes into and blends with that of the tendon.
Clinical electrophysiology of infantile botulism
Authors: Cornblath David R. , Sladky John T. , Sumner Austin J.
Published: January 2005

Infantile botulism is a recently recognized cause of acute hypotonic paresis and respiratory failure in young infants. Electrophysiological testing has proven useful in early diagnosis in suspected cases by demonstrating abnormal neuromuscular transmission as is known to occur in botulism. Twenty‐five infants with bacteriologically proven botulism were studied by uniform methods in our laboratory and characteristic electrophysiological abnormalities were found. Repetitive stimulation at 20 and 50 Hz was the most specific single test; 23 patients (92%) showed incremental responses. Stimulation at low rates was less specific. Concentric needle electromyography provided useful supplemental information. Short‐duration, low‐amplitude motor unit potentials were prominent in 22 patients (92%) accompanied by abnormal spontaneous activity in 13 patients (54%). Compound muscle action potential amplitudes were usually reduced, but motor and sensory conduction studies were otherwise normal. Electrodiagnostic testing demonstrated one or more characteristic abnormalities in all cases of infantile botulism. This constellation of electrophysiological abnormalities, combined with an appropriate clinical picture, was so distinctive as to allow early presumptive diagnosis of infant botulism, before the results of bacteriological testing were available.
Severe childhood muscular dystrophy affecting both sexes and frequent in tunisia
Authors: Ben Hamida Mongi , Fardeau Michel , Attia Neïla
Published: January 2005

The authors reported a large study of 93 children presenting a severe form of progressive muscular dystrophy. The first clinical symptoms were noticed between 3 to 12 years. The atrophy affects, predominantly, the girdle and truncal muscles. The hypertrophy of the calves is almost consistent. The progression of the disease is severe, often like that of the Duchenne type. In most of the cases, inability to walk occurs between 10 and 20 years. The serum creatine kinase activity is markedly high in the first stages of the disease. There is a necrotic regenerative pattern at muscle biopsy, associated with a marked type 1 predominance. The disease appears to be inherited as an autosomal recessive trait, with equal distribution among the two sexes. There is a marked variability in the intensity of symptoms and in the severity of the course of the disease from one sibling to another, and from one family to another. This disease is frequent in Tunisia and seems to be related to the high degree of consanguinity in this country.
The in vitro effects of D‐penicillamine upon anti‐achr production by thymic and peripheral blood lymphocytes from patients with myasthenia gravis
Authors: Scadding Glenis K. , Calder Linda , Newsom‐Davis John
Published: January 2005

D‐Penicillamine added to lymphocyte cultures from myasthenia gravis patients infrequently and inconsistently stimulated anti‐AChR production. This usually occurred in the presence of pokeweed mitogen (PWM), and often only at a single concentration of D‐penicillamine which varied among patients. The change was typically paralleled by an increase in total IgG production of similar magnitude, suggesting that the effect was nonspecific. D‐penicillamine did not affect AChR expression in cultured thymic adherent cells. These data provide no evidence that penicillamine induces myasthenia gravis by direct stimulation of anti‐AChR antibody‐producing cells.
Immunohistochemical demonstration of β‐enolase in human skeletal muscle
Authors: Ibi Tohru , Sahashi Ko , Kato Kanefusa , Takahashi Akira , Sobue Itsuro
Published: January 2005

We have localized β‐enolase activity in human skeletal muscle fiber using the immunohistochemical method (two‐step method). The first immunoreagent was rabbit anti‐human β‐enolase serum raised in New Zealand white rabbit, and the second was peroxidase conjugated staphylococcal protein A. The immunohistochemical reaction for β‐enolase was noted higher in type 2 fiber, which demonstrates the low oxidative and high glycolytic enzyme activity, than in type 1 fiber.
Double staining of the muscle fibers and interstitial tissue components for automatic analysis of muscle biopsies
Authors: Hantaï Daniel , Albe Xavier , Fardeau Michel
Published: January 2005

A staining technique is presented in order to facilitate the automatic analysis of muscle biopsies. It renders possible the visualization on the same section of the myofibrillary adenosine‐triphosphatase (ATPase) activity under the microscope with transmitted light, and of the fluorescent staining of fibronectin which marks the outlines of the muscle fibers by a simple switch to ultraviolet (UV) light.
Peripheral neuropathy in osteosclerotic myeloma: Clinical and electrodiagnostic improvement with chemotherapy
Authors: Donofrio P. D. , Albers J. W. , Greenberg H. S. , Mitchell B. S.
Published: January 2005

A patient with a severe remote‐effect polyneuropathy and other paraneoplastic features of osteosclerotic myeloma improved dramatically with melphalan and prednisone treatment. Serial electrodiagnostic studies provided an objective means of following the response to therapy and documented the improvement. We believe this represents the first reported patient with multifocal osteosclerotic myeloma and a myelomatous polyneuropathy responding to melphalan and prednisone.
Relationship of genotype and in vitro contractility in mdg/mdg ↔ +/+ “mosaic” myotubes
Authors: Peterson Alan , Pena Sergio
Published: January 2005

Muscular dysgenesis (mdg) in the mouse is an autosomal recessive lethal disorder that is manifested by a gross failure of skeletal muscle development. In vitro mdg/mdg myoblasts proliferate normally and fuse successfully into myotubes, but these myotubes fail to contract either spontaneously or in response to physiological stimuli despite the presence of effective contractile elements and an ability to propagate action potentials normally. We have determined that mdg/mdg and +/+ myoblasts are capable of fusing in vitro to form “mosaic”myotubes which typically express an apparently normal contractile phenotype. Electrophoretic analysis of the relative activities of myotube glucosephosphate isomerase (GPI‐1) isozymes provided a means of estimating the proportions of myonuclei of each genotype within individual myotubes. Only a very small proportion of genotypically normal myonuclei were required for expression of an apparently normal contractile phenotype.
The size of the myofibers in mature grafts of the mouse extensor digitorum longus muscle
Authors: Thomas Denise , Klueber Kathleen , Bourke Dianna , Ontell Marcia
Published: January 2005

The histochemical profile of stabilized orthotopically grafted mouse extensor digitorurn longus muscles (EDL) and fiber type diameter distribution in the graft was compared with control muscles. Histochemical fiber typing, based on myofibrillar ATPase reactions, indicated that type 1 fiber accounted for < 1%, type 2a fibers for 30%, and type 2b fibers for 69% of the total fiber population of the graft. In control muscles of 56‐day‐old and 156‐day‐old mice, type 1 fibers accounted for <1%, type 2a fibers for 36%, and type 2b fibers for 63% of the total fiber population of normal muscles. The regenerating myofibers in stabilized grafts failed to achieve the normal fiber diameter. The type 2b fibers exhibited greater growth inhibition than did type 2a fibers.
Pre‐ and postnatal growth and protein turnover in four muscles of the rat
Authors: Kelly Frank J. , Lewis Sheena E. M. , Anderson Paul , Goldspink David F.
Published: January 2005

Developmental growth and associated changes in protein turnover and nucleic acid concentrations have been studied in four individual skeletal muscles. They have also been related to changes in the whole animal. The growth rates of both fast and slow muscle types progressively diminished from the fetus to old age. Similarly, the fractional rates of protein synthesis (measured in vivo) and breakdown in each muscle type declined with age; the changes in the former correlating with decreases in the ribosomal capacities of the muscles. Throughout, fast muscles possessed lower turnover rates. The mean half‐lives of mixed proteins were 12.0, 14.4, 13.5, and 7.2 days in the extensor digitorum longus (EDL), gastrocnemius, diaphragm, and soleus muscles, respectively, 310 days postpartum. Muscle atrophy was found at 735 days, at which stage the decreased protein synthetic rate in the soleus was due to a fall in the ribosomal capacity, while that in the EDL was attributable to a decreased synthetic rate per ribosome.
Is the F wave elicited in a select group of motoneurons?
Authors: Kimura Jun , Yanagisawa Hideo , Yamada Thoru , Mitsudome Akihisa , Sasaki Hiroyuki , Kimura Akio
Published: January 2005

The F wave represents only a small percentage of the motoneuron pool invaded antidromically by any single impulse. We studied 22 median nerves from 11 healthy subjects to determine whether the recurrent discharges are preferntially generated in a select group of motoneurons with certain physiologic characteristics. Partial excitation of the nerve elicited the F wave with no consistent bias toward either the lower or higher threshold motor fibers. When the fast conducting axons were progressively blocked using a collision technique, the F wave continued to appear in the remaining slow conducting axons which escaped the collision. We conclude that the recurrent discharges occur in approximately 1% of antidromically activated motoneurons irrespective of their peripheral excitability or conduction characteristics.
The effect of stretch removal on muscle weight and proteolytic enzyme activity in normal and dystrophic chicken muscles
Authors: Day Ronald K. , Ashmore C. Robert , Lee Yu Bang
Published: January 2005

Hypertrophy was induced in the patagialis (PAT) muscle of 6‐week‐old normal and dystrophic chicks by passive stretch for 1 week. Stretch was then removed and muscle weights and activities of the proteolytic enzymes cathepsin C, cathepsin D, and leucine aminopeptidase (LAPase) were measured after 3, 5, 7, 10, and 14 days. In both genotypes, weights of stretch‐released muscles dropped progressively for 7 days relative to control muscles, after which they were not significantly different. At the time of stretch release, proteolytic enzyme activities were approximately twice as high in stretched normal muscles as in normal control muscles. In dystrophic chicks there was no difference in activities between stretched and control muscles. However, the activities of the enzymes in dystrophic muscles were already about 4 times higher than in normal control muscles. After stretch release, the enzyme activities in normal muscle progressively fell for 10 days, after which they were not different from normal control muscles. In dystrophic muscles the enzyme activities remained elevated and were not different from dystrophic control muscle activities at any time. We conclude that degradative enzyme activities in normal muscle closely parallel changes in muscle weight, whereas in dystrophic muscle proteolytic enzymes remain elevated and constant whether the muscle is gaining or losing weight.
Gastroparesis in neonatal myotonic dystrophy
Authors: Bodensteiner John B. , Grunow John E.
Published: January 2005

Myotonic dystrophy in the neonate is commonly accompanied by facial diplegia, generalized muscular hypotonia, talipes equinovarus, and muscular respiratory failure. The gastrointestinal manifestations of this disease include poor sucking, choking, regurgitation, aspiration, and swallowing difficulties. Gastroparesis can be a major contributor to the feeding difficulties experienced by these infants. We report on an infant with congenital myotonic dystrophy in whom a severe gastric motility problem was alleviated by metoclopramide therapy. This smooth muscle manifestation may be an important and potentially remediable source of morbidity in these infants.
A freeze‐fracture analysis of intramembrane particle densities on dystrophic hamster heart sarcolemma
Authors: Graham Kathryn A. , Shivers Richard R. , Atkinson Burr G.
Published: January 2005

The intramembrane particle (IMP) profile of control and dystrophic (Bio 14.6) hamster cardiac muscle plasma membrane was assessed in freeze‐fracture replicas to determine whether this animal model of muscular dystrophy exhibits the same membrane characteristics found in skeletal muscle from other more thoroughly studied dystrophic animals, and to test the hypothesis that the plasma membrane of the cardiac muscle cell is the site of a defect associated with the disease. Samples of cardiac muscle tissue from hamsters ranging in age from 1 to 13 months were freeze‐fractured. Intramembrane particle numbers were determined for all tissue samples by counting randomly selected areas of Phyphen; and E‐face surfaces. Up to the age of 1 month, the particle density was the same in both strains of hamster, after which time, the population of IMPs was about 30% lower in dystrophic than in normal heart sarcolemma. This 30% difference in particle frequency in dystrophic hamster heart membrane is consistent with values published for cell membrane from other muscular dystrophies and supports the theory that there is a defect in the plasma membrane of dystrophic cells. In addition, this study has shown for the first time that a presumed membrane defect related to muscular dystrophy (reduced number of IMPs) may be present throughout the life of the animal (1–13 months), and expressed in every cell sampled.
Phosphoglycerate kinase deficiency myopathy: Biochemical and immunological studies of the mutant enzyme
Authors: Bresolin Nereo , Miranda Armand , Chang Hai Won , Shanske Sara , DiMauro Salvatore
Published: January 2005

A new phosphoglycerate kinase variant (PGK New Jersey) has been purified from muscle and cultured fibroblasts of a patient with recurrent myoglobinuria. The mutant enzyme had higher than normal affinity for adenosine triphosphate (ATP) and 3‐phosphoglycerate, and a shift of the pH optimum towards the acidic side. Antibodies raised against PGK purified from normal muscle were used to evaluate the presence of immunologically cross‐reacting enzyme protein in tissues from the patient. Immunodiffusion and an antibody consumption test showed the presence of reduced amounts of cross‐reacting material in the patient's muscle. Several PGK variants have been characterized in asymptomatic individuals or in patients with hemolytic anemia. The biochemical features of PGK New Jersey, the only known variant associated with recurrent myoglobinuria, distinguish this mutant enzyme from others.
Healing‐over in skeletal muscles of the guinea pig following induced injury
Authors: Furukawa Kenichiro
Published: January 2005

Electrical membrane properties of cremaster muscle fibers of the guinea pig were determined before and after sectioning, using the microelectrode method. After sectioning, the membrane was depolarized to a maximum level within 5 minutes and the original level was reverted to within 60 minutes. Following restoration of the membrane potential, the spatial distribution of electrotonic potential indicated an electrical sealing at the cut end, and an action potential could be evoked. Therefore, it would appear that the cremaster muscle possesses the healing‐over phenomenon. This process was dependent on temperature and [Ca2+]0 and was not affected by pretreatment of actinomycin D, a protein synthesis inhibitor. This healing‐over process also occurs in the extensor digitorium longus (EDL) muscle of the guinea pig but not in the diaphragm. These results indicate that some mammalian skeletal muscle fibers possess the healing‐over phenomenon, as is observed in cardiac muscle fibers.
Congenital canine myasthenia gravis: I. Deficient junctional acetylcholine receptors
Authors: Oda Kenichiro , Lambert Edward H. , Lennon Vanda A. , Palmer Anthony C.
Published: January 2005

The neuromuscular junction was studied during growth in two breeds of dog with a congenital familial from of myasthenia gravis (CMG): the Jack Russell terrier and the springer spaniel. Light microscopy revealed no difference in endplate size or nerve terminal morphology in agematched CMG dogs and unaffected littermates. At all ages there was in individual muscle fibers of CMG dogs an approximately 75% lower postsynaptic membrane density of acetylcholine receptors (AChR). There was no evidence that this abnormality had an autoimmune basis. Measurements of miniature endplate potential amplitude in relation to fiber diameter revealed that the low density of AChR in the postsynaptic membrane of CMG dogs remained constant and did not change with the marked progression of muscle weakness during growth. Antigenic determinants of AChR were deficient in CMG muscle to the same extent as α‐bungarotoxin (αBT) binding sites. Thus, a low density of AChR in the muscle's postsynaptic membrane appears to be the principal abnormality of CMG. The data suggest that the normal increase in number of acetylcholine (ACh) quanta released by nerve impulse may not fully compensate for the reduction in depolarization produced by a single quantum as the muscle fiber diameter increases. This could cause progression of weakness during growth. In addition to being a useful animal model of a rare form of CMG that resembles one form of human CMG, canine CMG offers a unique model for investigating events of synaptogenesis at the neuromuscular junction.
Congenital canine myasthenia gravis: II. Acetylcholine receptor metabolism
Authors: Oda Kenichiro , Lennon Vanda A. , Lambert Edward H. , Palmer Anthony C.
Published: January 2005

Acetylcholine receptor (AChR) metabolism was studied in muscle from juvenile and adult dogs with congenital myasthenia gravis (CMG) and their unaffected littermates. Although the amount of AChR in the junctional region of innervated CMG muscle fibers was 25% of normal, or less, denervation of CMG fibers resulted in the appearance of AChR in extrajunctional membranes at as high a concentration as in denervated normal fibers. The rate of degradation of junctional AChR in CMG fibers explanted to organ culture did not differ significantly from normal. In monolayer cultures derived from enzyme‐dissociated CMG muscle, myotubes of normal morphology developed, and the synthesis and degradation of AChR did not differ from normal. Addition of sera from dogs with the acquired autoimmune form of MG accelerated the degradation of AChR on cultured myotubes, but CMG dog sera were without effect. These data suggest that the low junctional membrane density of AChR in CMG does not reflect a primary inability of muscle to synthesize AChR, nor an accelerated degradation of AChR in the postsynaptic membrane, but rather a low insertion rate of AChR in the postsynaptic membrane.
Control of myofibrillar ATPase activity and force in myodystrophic muscle
Authors: Mobley Bert A. , Reddy Y. S. , Feeback Daniel L. , Bodensteiner John B. , Bokhari Masuda , Robinson R. D. , Clark Ronald
Published: January 2005

Myofibrillar ATPase activity was measured as a function of the free calcium concentration in skeletal muscles of control and myodystrophic mice. In addition, the force developed in skinned extensor digitorum longus (EDL) fibers of control and myodystrophic mice was measured as a function of the free calcium concentration, and a histomorphometric study was performed on soleus and EDL muscles of control and myodystrophic mice. The results showed that the myofibrillar ATPase activity and the force‐generating mechanisms of control and myodystrophic muscles were controlled to the same relative degree by equivalent concentrations of calcium ions. Upon maximal activation of the ATPase activities, we measured 18% less activity in myodystrophic muscles than in control muscles. Maximal activation of the force‐generating capacity in skinned fibers showed there was no significant difference in force produced in the control compared to myodystrophic fibers. The histomorphometric study revealed no alteration in the relative distribution of different fiber types in myodystrophic compared to control muscles. However, the histomorphometry did reveal a larger slow (type 1) relative cellular area compared to total cross‐sectional area in myodystrophic muscle than in controls. We propose that the lower ATPase activity but equal force‐generating capacity of myodystrophic muscles compared to control muscles is due to myodystrophic muscles being composed of a greater fraction of myofibrils from slow (type 1) fibers than control muscles.
Morphology of stable muscle grafts of rats: Effects of gender and muscle type
Authors: Clark Kathryn I. , White Timothy P.
Published: January 2005

Our purpose was to quantify morphological characteristics of extensor digitorum longus (EDL) and soleus (SOL) muscle grafts in female (N =8) and male (N = 8) rats. Muscles were grafted orthotopically, with the nerve remaining intact, and were studied 56 days later. The mass of EDL and SOL grafts and control muscles of females was 60% to 65% of male values; this difference was directly related to gender differences in body mass. The fiber composition of EDL and SOL grafts did not differ from control, and no gender effects were noted. The mean fiber area (MFA) of control EDL and SOL muscles of females averaged 65% of male values. The MFA of grafts did not differ due to gender, and averaged 60% of control value for SOL and 70% for EDL grafts. We conclude there are no substantial differences in the regenerative capacity of EDL and SOL muscles grafted with the nerve intact.
Effects of isaxonine on skeletal muscle reinnervation in the rat: An electrophysiologic evaluation
Authors: Pecot‐Dechavassine Monique , Mira Jean‐Claude
Published: January 2005

Electrophysiologic detection of the first signs of gastrocnemius muscle reinnervation shows that after a single localized freezing of the rat sciatic nerve, isaxonine does not significantly increase the rate of axonal regeneration. However, this drug does significantly enhance axonal sprouting, as it induces an increase of 50% in the number of muscle fibers with multiple innervation 10–30 days after freezing. After 30 days, the proportion of multiinnervated fibers decreases in both the control and isaxonine‐treated rats, and the differences between them gradually disappear.
Parvalbumin in cross‐reinnervated and denervated muscles
Authors: Müntener Markus , Berchtold Martin W. , Heizmann Claus W.
Published: January 2005

The extensor digitorum longus (EDL) muscle was cross‐reinnervated by the soleus (SOL) nerve, leading to the well‐known transformation toward a slow muscle. Nine weeks after the operation, the quantitative analysis of the Ca2+‐binding protein, parvalbumin (PV), using highperformance liquid chromatography, showed a threefold reduction of PV in the cross‐reinnervated EDL muscle. Denervation of the EDL muscle, which leads to an increase of the half‐relaxation time, resulted in a 20% decrease of the PV concentration within 4 days. This significant lower PV level was detectable prior to any change of the myofibrillar adenosine triphosphatase (ATPase). Normal PV concentrations were reached after 9 weeks following self‐reinnervation of the EDL muscle. The experiments support the view that PV is involved in the relaxation of rat fast skeletal muscles and that its expression is dependent on nerve—muscle interaction. Since PV changes preceded histochemical changes after denervation, this protein may be a sensitive marker for early stages of neuromuscular disturbances.
Differential effects of α‐latrotoxin on mouse nerve endings and fibers
Authors: Mallart Alberto , Haimann Claudia
Published: January 2005

The action of α‐latrotoxin (α‐LTx), the major toxic component from black widow spider venom, was studied on mammalian motor nerve endings and fibers. Electrophysiologic recordings of presynaptic and postsynaptic responses at early stages after the application of different doses of α‐LTx showed massive transient increases in transmitter release and changes in the configuration of presynaptic currents. Later, a loss of invasion of terminals by nerve impulses occurred, whereas the impulse conduction in nerve fibers was unmodified. These results support the idea of a selective effect of α‐LTx on presynaptic membrane excitability.
Localization of calcium‐activated neutral protease (CANP) in the peripheral nerve
Authors: Kamakura Keiko , Ishiura Shoichi , Fujita Takehisa , Nonaka Ikuya , Sugita Hideo
Published: January 2005

Localization of calcium‐activated neutral protease (CANP) in the rat peripheral nerve was studied by an indirect immunofluorescent method, using rabbit antiserum against CANP extracted from chicken skeletal muscle. Its specificity to CANP, as well as its cross‐reactivity with rat CANP, were confirmed by the Ouchterlony immunodiffusion procedure and immunoreplica method. CANP was demonstrated in the axon, but not in the myelin sheath or endoneurium. We could not conclude whether or not CANP in axons exists in association with neurofilaments.
Phospholipid methylation in skeletal muscle membranes
Authors: Kuncl Ralph W. , Drachman Daniel B. , Kishimoto Yasuo
Published: January 2005

Phospholipid methylation is thought to modulate such vital cellular processes as calcium transport, receptor function, and membrane microviscosity. As these processes are fundamental to the function of muscle cells and are thought to be altered in disease states, we have characterized several features of phospholipid methylation reactions in skeletal muscle and have defined appropriate assay conditions. In rat leg muscle, methyltransferase activity was assayed radiometrically by measuring the incorporation of methyl groups from S‐adenosyl‐L‐[methyl‐3H]methionine into membrane phospholipids, the methylated derivatives of which were separated by thin‐layer chromatography. Contrary to previous investigations of whole muscle, phospholipid methyltransferase activity was clearly present in skeletal muscle membranes, being highly localized in sarcoplasmic reticulum and present to a lesser extent in sarcolemma. Both the reaction products and the reaction kinetics were consistent with sequential methylation of phospholipids by two methyltransferase enzymes. S‐adenosylhomocysteine and its analogues were potent inhibitors of phospholipid methylation in sarcoplasmic reticulum. The predominant localization of phospholipid methytransferase activity in sarcoplasmic reticulum suggests that its functional role in skeletal muscle may be in calcium transport.
In vivo P‐NMR spectroscopy: Muscle energy exchange in paramyotonia patients
Authors: Lehmann‐Horn Frank , Höpfel Dieter , Rüdel Reinhardt , Ricker Kenneth , Küther Gerald
Published: January 2005

Using phosphorus nuclear magnetic resonance spectroscopy, we studied the muscle metabolism in four patients with paramyotonia congenita as reflected in the PC/Pi and PC/ATP ratios. At normal body temperature, all results were indistinguishable from controls. After cooling to 29°C muscle temperature and a single 2‐sec maximum contraction, the forearm muscles were stiff. At this stage, no decrease in the ATP content could be detected. In >50% of the experiments with patients, an additional peak occurred transiently at the resonant frequency for monophosphates. After a working period at 29°C muscle temperature, the paramyotonic muscles were paralyzed, but displayed spectra similar to those obtained at normal body temperature and full working capability. Intracellular pH was close to 7 in paramyotonic muscle under all conditions examined.
Isolated myofibers from rat skeletal muscle in suspension: Cellular morphology and calcium homeostasis
Authors: Zuurveld Judith G. E. M. , Veerkamp Jacques H. , Wirtz Peter
Published: January 2005

Myofiber suspensions with 80% viability (morphological intactness) were prepared from rat m. flexor digitorum brevis by a 6‐hour collagenase treatment. The viable fibers had intact sarcolemmas and generally showed continuous basal laminae. The intracellular compartments exhibited normal muscular morphology. The suspended myofibers showed good tolerance against extracellular calcium (up to 30 mM), but were susceptible to 15mM EGTA. Calcium ionophore A23187 induced contraction, with loss of viability in both calcium‐containing and nominally calcium‐free Krebs‐Ringer medium. EGTA prevented the ionophore effect, but the muscle cells collapsed as soon as calcium was replenished. A calcium paradox, as observed with perfused heart, could not be induced in isolated skeletal myocytes. This suspended cell system should provide a useful tool for investigating relationships between metabolic parameters and muscle physiology. The extracellular environment can be manipulated easily, and cellular responses of individual skeletal muscle fibers can be measured and visualized.
Post‐tetanic responses in creatine‐depleted rat edl muscle
Authors: Mainwood Graham W. , De Zepetnek Joanne Totosy
Published: January 2005

The total creatine content of rat extensor digitorum longus (EDL) muscles is reduced from 26.7 m̈mol·g−1 to 5.2 m̈mol·g−1 after 4 weeks on a diet containing b̃‐guanidinopropionate. The resting muscles of these animals contain only 5% of the normal creatine phosphate and about 30% of the normal adenosine triphosphate (ATP). Isometric twitch and brief tetanic responses are not significantly different from normal. However, following a 1‐second tetanus, the normal twitch potentiation (+80%) is reversed in depleted muscles (−40%). The initial suppression lasts 1–2 seconds and is followed by a small delayed potentiation (+25%). Relaxation rate, which is normally increased following a tetanus, is considerably reduced in depleted muscles. Reversal of potentiation appears to be due to a suppression of twitch activation. The suppression may result from a transient fall in ΔGATP, which is thought to be a critical parameter in the uptake of Ca++ by the sarcoplasmic reticulum (SR).
Sequential urinary Nτ‐methylhistidine to creatinine ratios in premature infants
Authors: Burgoyne Judith L. , Fitzgerald Anne , Dahlenburg Geoffrey W. , Haslam Ross R. , Tomas Frank M. , Ballard F. John
Published: January 2005

The present study was undertaken to establish normal values of the Nτ‐methylhistidine to creatinine excretion ratio in very premature infants, to observe changes with postnatal age, and to determine whether or not reliable data on this index of myofibrillar protein breakdown could be obtained from untimed urine samples without recourse to the 24‐ hour collections used previously. The normal range (95% confidence limits) of the molar excretion ratio for unstressed infants was established to be between 0.0248 and 0.0440. Narrower limits of variability occurred when nutrient intake was controlled at a satisfactory level or when comparisons were between sequential urine samples from single infants. No diurnal changes could be detected. We conclude that analyses of Nτ‐methylhistidine and creatinine on spot urine samples permit the calculation of an excretion ratio that is reproducible both within and between individual infants and that should be useful in assessing changes in myofibrillar protein breakdown caused by differences in clinical, pharmacologic, or nutritional status.
31P‐NMR Studies on an animal model of human defective muscle glycolysis
Authors: Kuwabara Takeo , Yuasa Tatsuhiko , Miyatake Tadashi
Published: January 2005

Sequential metabolic changes in leg muscles of a model of defective muscle glycolysis that was produced by intraaortic injection of sodium iodoacetate were observed by in vivo 31P‐NMR spectroscopy with a surface coil. Spectra obtained from iodoacetate‐treated muscles presenting exercise‐induced cramp showed decreased levels of phosphocreatinine (PCr) and adenosine triphosphate (ATP) and an accumulation of sugar phosphate. The chemical shift of inorganic phosphate (Pi) resonance, which reflects the intracellular pH of the contracted muscles, showed a milder shift to the acidic condition than those of controls. In vivo 31P‐NMR study showed dynamic information on the muscle energetics under defective glycolytic conditions.
Insulin binding in denervated muscle
Authors: Donaldson Deirdre , Evans Owen B. , Harrison Robert W.
Published: January 2005

Insulin binding was measured in rat muscle following denervation. There was a 40% reduction in the number of high‐affinity insulin receptors, with no change in the insulin binding Kd. Selected muscles showed a 40%–60% reduction in weight during this period. The down regulation in the number of insulin receptors may contribute to the mechanism of muscle atrophy following denervation.
Calcium paradox in skeletal muscles: Physiologic and microscopic observations
Authors: Soza Marco , Karpati George , Carpenter Stirling
Published: January 2005

Immersion of rat hemidiaphragms in Ca2+‐free Krebs solution (KS) containing Ca2+ chelator in vitro leads to separation of basal lamina from the plasma membrane, as well as transient contracture and rapid loss of twitch response [calcium paradox (CP) phase 1]. Subsequent immersion in regular KS results in necrosis of muscle fibers accompanied by slowly increasing contracture (CP phase 2). This contracture could be prevented or reduced by using either Ca2+‐free KS or calcium channel blockers, but not by dantrolene sodium, implying that after drastic reduction of extracellular and sarcolemmal Ca2+ during CP phase 1, the sarcolemma has lost its ability to control normal Ca2+ fluxes. Contracture did not develop at 21°C. CP is a convenient model to study calciuminduced muscle cell death and the role of Ca2+ in maintaining sarcolemmal integrity.
Adverse effect of verapamil in a patient with the lambert‐eaton syndrome
Authors: Krendel David A. , Hopkins Linton C.
Published: January 2005

A patient with the Lambert‐Eaton syndrome (LES) and small cell lung cancer developed respiratory failure several hours after verapamil was given. Improvement in respiratory function did not occur when guanidine was given, but was delayed until verapamil was discontinued 3 days later. Although other factors may have contributed to the clinical deterioration of our patient, the temporal relationship to verapamil and the theoretical danger of calcium channel blockade lead us to believe that the drug should be used cautiously in LES.
Neuropathy associated with cryoglobulinemia
Authors: Lippa Carol F. , Chad David A. , Smith Thomas W. , Kaplan Melvin H. , Hammer Kathryne
Published: January 2005

A patient with severe subacute sensory ataxia was found to have an IgM (kappa) cryoglobulin. Clinical, electrophysiologic, and sural nerve biopsy studies indicated that axonal degeneration and segmental demyelination both played a role in the pathogensis of this neuropathy. Corticosteroid therapy was associated with notable clinical improvement and a 50% decrease in cryoglobulin concentration.
Duchenne dystrophic muscle develops lesions in long‐term coculture with mouse spinal cord
Authors: Peterson Edith R. , Masurovsky Edmund B. , Spiro Alfred J. , Crain Stanley M.
Published: January 2005

When strips of human skeletal muscle from biopsies of normal children and donors with Duchenne muscular dystrophy (DMD) are explanted in organotypic coculture with fetal mouse spinal cord, many regenerating muscle fibers develop, become innervated, and maintain a remarkable degree of mature structure and function for more than 3–6 months in vitro. Sequential light microscopy in correlation with electron‐microscopic and electrophysiologic analyses showed that despite cross‐species innervation, these human muscle fibers develop stable cross‐striations, peripherally positioned myonuclei, and mature, functional motor endplates. Of special interest is the onset of significant progressive abnormalities, e.g., unusual focal myofibrillar lesions, in substantial numbers of innervated mature DMD muscle fibers after 2–4 months in culture. The focal myofibrillar lesions were not detected in normal muscle fibers maintained as long as 6 months in coculture, nor are they comparable to the generalized loss of cross‐striations observed in muscle atrophy following in vitro denervation of mature DMD fibers.
AAEE Minimonograph #25: Single‐fiber electromyography in myasthenia gravis
Authors: Sanders Donald B. , Howard James F.
Published: January 2005

Single‐fiber electromyography (SFEMG) demonstrates abnormal jitter in virtually all (99%) patients with myasthenia gravis (MG). One muscle, the extensor digitorum communis, is abnormal in most patients with this disease, but to obtain the maximum diagnostic sensitivity, it may be necessary to examine other muscles, especially ones that are more involved clinically. There is no one muscle that will be more abnormal in every patient with MG. The muscle(s) to be tested must be selected based on the distribution of weakness in the individual patient. Abnormal jitter is also seen in diseases of nerve and muscle; these diseases must be excluded by other electrophysiologic and clinical examinations before diagnosing MG. If neuronal or myopathic disease is present, increased jitter does not indicate that MG is also present. However, if jitter is normal in a muscle with definite weakness, the weakness is not due to MG. When abnormal neuromuscular transmission has been demonstrated by repetitive nerve stimulation, the finding of abnormal jitter does not add to the diagnosis, though it may be useful in providing baseline values for comparison with the results of subsequent studies. SFEMG is most valuable clinically in the patient with suspected MG in whom other tests of neuromuscular transmission and antiacetylcholine receptor antibody titers are normal. Serial measurements of jitter can be useful in following the course of disease and in assessing the effect of treatment, but the results from these studies must always be interpreted in light of the overall clinical picture.
Potassium channel blockers and impulse propagation in murine motor endplate disease
Authors: Bournaud Roland , Mallart Alberto
Published: January 2005

An electrophysiologic study has been performed on motor nerves of mice affected with hereditary “motor endplate disease” (MED). Bath application of potassium channel blockers, such as tetraethylammonium and 3,4‐diaminopyridine, which are almost without effect on the monophasic compound action potential of normal nerves, considerably enhanced the action potential duration in nerves from mutant mice. Furthermore, external current recordings from motor endings revealed an absence of the K‐dependent waveform component in MED mice, which indicates a similar K current intensity in the terminal part of the endings and in the heminode. These observations suggest that in the mutant, unlike in normal mice, K channels play a role in action potential electrogenesis. Possible relationships with paranodal dysmyelination are discussed.
Double‐step repetitive stimulation in myasthenia gravis
Authors: Gilchrist James M. , Sanders Donald B.
Published: January 2005

The double‐step technique of repetitive nerve stimulation was compared with repetitive nerve stimulation to a distal and a proximal muscle and with single fiber needle electromyography in 10 patients with myasthenia gravis. We conclude that the double‐step technique is slightly more sensitive than repetitive nerve stimulation to a proximal muscle but only 60% as sensitive as single fiber electromyography in demonstrating abnormal neuromuscular transmission in myasthenia gravis.
Serotonin uptake in blood platelets of duchenne muscular dystrophy patients
Authors: Arora Ramesh C. , Meltzer Herbert Y. , Kuncl Ralph W. , Morgan Juliet , Cohen Louis
Published: January 2005

Serotonin (5‐HT) uptake was studied in the blood platelets of 10 patients with Duchenne‐type muscular dystrophy (DMD) and 7 age‐matched controls. Vmax (maximum number of uptake sites) of platelet 5‐HT uptake in the DMD patients was significantly less than that of the normal controls. There was no difference in the affinity for 5‐HT (Km) between the two groups. There was a significant negative correlation between serum creatine kinase activity and Km of 5‐HT uptake in blood platelets of these patients. However, no correlation was found between Km or Vmax and ambulatory status of DMD.
Changes in guinea pig muscle histology in response to reduced bobility
Authors: Leiveseth Gunnar , Tindall Alex , Myklebust Reidar
Published: January 2005

Dorsiflexion of one hind foot has been prevented in guinea pigs by means of a light prosthesis. The gastrocnemius and soleus muscles of both hind legs have been removed after a period of 2 weeks, and the fiber cross‐sectional areas of type 1 and 2 fibers in both muscles have been measured Comparison of the values in normal and affected muscles shows that the limited reduction in free movement of the foot led to a significant atrophy in types 1 and 2 fibers in both muscles.

The use of this simple prosthesis appears to have no effect on any other function of the leg except for the restriction of the lengthening of gastrocnemius and soleus muscles, and the results show that some of the hypotheses about the muscle atrophy seen in fully immobilized limbs cannot account for the changes observed in the present experiments and seem to be of limited validity.