bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased rates of myofibrillar protein breakdown in muscle‐wasting diseases
Authors: Warnes Deidre M. , Thomas Frank M. , Ballard F. John
Published: January 2005

The excretion of endogenous creatinine and 3‐methylhistidine by subjects with muscle diseases has been measured in order to assess muscle mass and fractional rates of myofibrillar protein degradation. Increases in the rates of myofibrillar protein breakdown were observed in all subjects with Duchenne, Becker, autosomal recessive Duchenne‐like, and limb‐girdle muscular dystrophy; dystrophia myotonica; myotonia congenita; peroneal muscular atrophy; myasthenia gravis; and central core disease; in some cases of spinal muscular atrophy; but in no cases of facioscapulohumeral muscular dystrophy or dystonia musculorum deformans. All increases in myofibrillar protein breakdown were associated with reductions in muscle proportion below the normal. Muscle‐wasting diseases may respond to therapy directed towards an inhibition of muscle protease activity; the efficacy of such therapy can be monitored by the 3‐methylhistidine–to–creatinine excretion ratio.
Computed tomography of muscle
Authors: Bulcke Jan A. , Crolla Dominique , Termote Jean‐Luc , Baert Albert , Palmers Yvan , van den Bergh Raymond
Published: January 2005

Computed tomography (CT) scans of skeletal muscles of 3 patients with pseudohypertrophic muscular dystrophy are presented. Different patterns of muscle alterations and particualrly of pseudohypertrophy are described. The significance of the radiological findings for clinical examination, electromyography, and needle biopsy is discussed.
The adaptive response of skeletal muscle to increased use
Authors: Salmons S. , Henriksson J.
Published: January 2005

Skeletal muscle undergoes profound changes in morphological, physiological, and biochemical character when subjected to prolonged periods of increased use. Although increased use may be brought about in a variety of ways, the results show consistent features. In particular, endurance exercise and chronic stimulation differ only in degree: the properties which change in response to exercise are also those which change at an early stage of stimulation; the properties which are resistant to change under exercise conditions change only after prolonged stimulation. There is therefore a hierarchy of stability in the properties of skeletal muscle which is revealed in its response to changing functional demands. The adaptive potential of muscle provedes a logical framework for understanding neural influences on the emergence of fiber types during muscle development. It is also relevant to the study of pathological conditions which may involve a sustained departure from normal postural and locomotor patterns of activity.
Penicillamine‐induced myositis in rheumatoid arthritis
Authors: Morgan G. James , McGuire James L. , Ochoa José
Published: January 2005

A patient with rheumatoid arthritis who developed multiple mononeuropathies multiplex was shown to have vasculitis in nerve biopsy, but no evidence of inflammatory muscle disease in muscle biopsy. Treatment with penicillamine caused the rare complication of polymyositis, documented clinically, electrophysiologically, and by light and electron microscopy in a second muscle biopsy. The evidence presented supports the concept that penicillamine may induce polymyositis or aggravate a preexisting low‐grade myositis.
Clinical trial in duchenne dystrophy. I. The design of the protocol
Authors: Brooke Michael H. , Griggs Robert C. , Mendell Jerry R. , Fenichel Gerald M. , Shumate Jack B. , Pellegrino Richard J.
Published: January 2005

Therapeutic trials in muscular dystrophy have often been inconclusive. A protocol has been designed which selects patients with Duchenne muscular dystrophy and permits accurate measurement of their status. An integral part of the protocol is a system for checking on the consistency of the data obtained using a computer program.
Muscle fiber necrosis in murine dystrophy
Authors: Ontell Marcia
Published: January 2005

A sampling technique based on spaced serial ultrathin sections was used to examine the ultrastructure and cytoarchitecture of myofibers, which were necrotic throughout their length, in the dytrophic mutant mouse (C57BI6J/dy2J). Regional variations along the length of the myofibers were described. The necrotic fibers extended the full length of the muscle fascicle and did not branch. In necrotic fibers which were free of invasive cells, the only nuclei found under the basal lamina were peripherally placed, euchromatic myonuclei, or nuclear membrane remnants. In these fibers, the nuclear population was ∼ 14% of the nuclear population of “healthy” fibers from the same animals. No myosatellite cells were observed to be associated with these necrotic fibers. In necrotic fibers, which had undergone foreign cell invasion, the existence of a pleomorphic population of mononucleated invasive cells, many of which had not begun to express phagocytic characteristics, caused considerable confusion, because their appearance tended to mimic that of myonuclei or satellite cells. No heterochromatic nuclei or true myosatellite cells were found associated with necrotic fibers displaying macrophage invasion.
Isometric contractions of normal and spastic human skeletal muscle
Authors: Ismail H. M. , Ranatunga K. W.
Published: January 2005

Isometric contractile properties of human elbow flexor muscles were examined in 27 normal subjects (7 females and 20 males). Contractions of elbow flexors were elicited by application of electrical pulses to the biceps motor points. The tension development was recorded at the wrist with the elbow angle fixed at 90°–100°. The data for the time to peak and time to half relaxation of the twitch, the twitch tension‐to‐tetanus tension ratio, and the posttetanic twitch potentiation are reported. The contractile properties of spastic elbow flexor muscles from 7 subjects who had been hemiparetic for periods ranging from 4 months to 60 months were found to be similar to those of muscles in normal subjects and unaffected muscles in hemiparetic subjects.
An autopsy study of a familial oculopharyngeal muscular dystrophy (OPMD) with distal spread and neurogenic involvement
Authors: Schmitt Horst P. , Krause K.‐H.
Published: January 2005

An 81‐year‐old man from a family with a history of oculopharyngeal muscular dystrophy (OPMD) involving 6 members over 4 generations is described. The patient first noted drooping of his eyelids at the age of 65. Dysphagia and dysarthria occurred soon thereafter. At age 78, impairment of gait developed and progressive wasting occurred in the limbs with an initial distal distribution. Electromyography of several limb muscles displayed a mixed myopathic and neurogenic pattern with giant potentials. Examination at autopsy revealed slight loss of neurons in the anterior horns of the spinal cord, with scanty ghost cells, neuronophagia, and central chromatolysis. By light microscopy the limb muscles showed moderate small‐group atrophy with severe myopathy and target fibers. The viscerocranial muscles, including the ocular, vocal, and tongue muscles, demonstrated only myopathic change with the typical features of progressive muscular dystrophy. Advanced replacement by fibrous connective tissue and fat had occurred in both the viscerocranial and the lower limb muscles. The significance of neurogenic involvement in OPMD is discussed.
Canine muscle fiber types and susceptibility of masticatory muscles to myositis
Authors: Orvis Julia Stephens , Cardinet George H.
Published: January 2005

The myofiber type composition was studied in 42 different muscles of the dog to determine if there are unique features that might explain the preferential involvement of the muscles of mastication by inflammatory myopathies. The principal myofiber types for most muscles studied were type 1 and type 2A and, to a lesser extent, type 2C, wherease the dorsal group of muscles innervated by the mandibular nerve (Mm. temporalis, masseter, pterygoideus lateralis, pterygoideus medialis, tensor tympani, and tensor veli palatini) was composed only of type 2C myofibers and a variant of the type 1 myofiber whose staining intensity was not fully reversed after preincubation in acid media. The distribution of this myofiber type composition was associated with the innervation and embryologic development of the dorsal muscles innervated by the mandibular nerve. This unique myofiber type composition could provide the basis for the preferential susceptibility of these muscles to agents (e.g., immune and/or infectious) that produce myositis; however, further studies are required to assess that possiblity.
A possible role for glucocorticoids in denervation atrophy
Authors: DuBois Debra C. , Almon Richard R.
Published: January 2005

Skeletal muscle atrophies after denervation. Glucocorticoids also cause skeletal muscle to atrophy. The data presented in this report demonstrate that after denervation there is a significant increase in the number of glucocorticoid receptors in the cytosol of skeletal muscle of rats. The results are consistent with the hypothesis that a skeletal muscle atrophies after denervation because it becomes hypersensitive to glucocorticoids.
Changes in the forms of the components of the troponin complex during regeneration of injured skeletal muscle
Authors: Dhoot Gurtej K. , Perry S. Victor
Published: January 2005

Using the immunoperoxidase technique, antibodies to the fast components of the troponin complex stained all regenerating cells after localized alcohol injury to rat skeletal muscle. Antibodies to slow troponin components stained only some of these cells. About 6 weeks after injury with the nerve intact, the fast and slow forms of the troponin components were located in different cells. During the later stages of regeneration, staining for myosin ATPase correlated with the staining with antibodies to fast and slow troponin components. A similar staining pattern was also observed in the early stages of regeneration of muscle denervated at the time of injury. In this case, antibodies to fast skeletal muscle troponin components continued to stain all the cells 10 weeks after injury. Injured denervated muscle cells stained equally dark by myosin ATPase after preincubation at pH 9.4 over this period. None of the regenerating myotubes in denervated muscle stained for myosin ATPase after preincubation at pH 4.3.
D‐penicillamine‐associated myasthenia gravis: Immunological and electrophysiological studies
Authors: Fawcett Peter R. W. , McLachlan Sandra M. , Nicholson Louise V. B. , Argov Zohar , Mastaglia Frank L.
Published: January 2005

Immunological and electrophysiological features were investigated in a patient with rheumatoid arthritis who developed myasthenic symptoms after 10 months of treatment with D‐penicillamine (D‐pen). After an initial rise, acetylcholine receptor (AChR) antibodies gradually fell from 24.4 nmole α‐bungarotoxin bound/liter to 1.8 nmole/liter following withdrawal of the drug, and this was associated with clinical and electrophysiological improvement. Immunoglobulin synthesis by peripheral blood lymphocytes cultured with pokeweed mitogen and D‐pen was significantly increased at D‐pen concentrations of 10–100 μg/ml in 2 patients with D‐pen associated myasthenia gravis and 1 out of 3 normal individuals. Furthermore, lymphocytes from 1 myasthenic patient synthesized detactable AChR antibodies in vitro, and the amount of receptor antibody produced was increased in the presence of the drug. This effect was most marked at a concentration of 10 μg/ml which is thought to approximate the concentration in vivo. Our results confirm the in vivo findings of others that D‐pen may have different effects on immunoglobulin production in different individuals and may also enhance the synthesis of at least 1 autoantibody, the AChR antibody.
Dual type of facilitation at the neuromuscular junction of the frog
Authors: Hort‐Legrand Claudine , Metral Stéphane
Published: January 2005

End‐plate potentials were recorded intracellularly at the frog neuromuscular junction. Facilitation produced by conditioning shocks applied to the motor nerve was studied in two different ways: using either low‐frequency trains in Mg‐blocked preparations or using brief high‐frequency trains followed by a test shock of variable latency in D‐tubocurarine‐blocked preparations. In both cases, two distinctly different types of motor end‐plates were observed. The first type showed a low quantum content and a marked facilitation without depression, while the second type showed a high quantum content, a poor facilitation, and a marked depression. The physiological significance of these findings is discussed.
Fragmentation analysis of normal and dystrophic avian muscle
Authors: Feit Howard , Stauver Marguerite , Domke Robert , Shay Jerry W.
Published: January 2005

A difference between normal and dystrophic avian muscle was demonstrated by comparing the patterns of fragmentation of muscle during homogenization. Fragmentation was monitored by morphological methods and by viscometry. This method of fragmentation analysis depends on the principle that the viscosity of a suspension is an exponential function of the partial volume fraction occupied by the suspended particles; the more a tissue is fragmented into smaller pieces, the greater the viscosity of the resulting homogenate. Increasing the duration of homogenization of either fresh muscle in buffer or glycerinated muscle in relaxing solution gradually increased the viscosity of the homogenate of normal muscle, whereas the viscosity of the homogenate of dystrophic muscle remained approximately constant. This difference in viscosity indicated that dystrophic muscle was sheared into larger pieces which were resistant to further fragmentation. Electron microscopic examination showed that the homogenate of dystrophic muscle contained rows of sarcomeres, whereas normal muscle was sheared into amorphous masses of myofilaments.
Myotonic electromyographic activity in complexus muscles of normal and dystrophic chicks
Authors: Entrikin Richard K , Randall William R. , Wilson Barry W.
Published: January 2005

Myotonic‐like, “dive‐bomber” discharges were recorded from complexus (“hatching”) muscles of both normal and dystrophic chicks at 5 days exovo and were recordable from dystrophic, but not from normal, pectoralis major muscles at 28 days ex ovo. The complexus muscle, therefore, provides the opportunity to study in young, normal animals, a from of electrophysiological activity previously considered a sign of neuromuscular abnormality.
Reduced axonal transport of 10S acetylcholinesterase in dystrophic mice
Authors: Brimijoin Stephen , Schreiber Patricia A.
Published: January 2005

Extracts of extensor digitorum longus muscle, atria, brain, and sciatic nerve from phenotypically normal and dystrophic ReJ/129 mice were subjected to sucrose density gradient ultracentrifugation, and the amounts of acetylcholinesterase (AChE) activity associated with each major enzyme form were determined. Normal muscle showed approximately equivalent amounts of the 4S, 10S, and 16S forms of AChE, while dystrophic muscle was relatively deficient in 10S AChE and relatively oversupplied with 4S AChE. This abnormality was not present in the other tissues examined. However, as measured by the 24‐hour accumulation of enzye activity proximal to a ligature on the sciatic nerve, the axonal transport of 10S AChE was only about one third as great in dystrophic as in normal nerve. This result is consistent with the view that the reduction in the amount of this enzyme form in dystrophic muscle could be related to disturbances in a transport‐dependent trophic interaction between nerve and muscle.
Beneficial effects of transplanting normal limb‐bud mesenchyme into dystrophic mouse muscles
Authors: Law Peter K.
Published: January 2005

A new technique is being developed to remedy muscle weakness of hereditary myopathies. Mesenchymal cells dissected from limb‐buds of day‐12 normal mouse embryos were transplanted into the right solei of 20‐day‐old normal or dystrophic C56BL/6J‐dy2J mice. Host and donors were immunocompatible. Unoperated left solei served as controls. Sham control solei receiving similar surgical treatment but no mesenchyme transplant did not differ from contralateral, unoperated solei. Six to seven months postoperatively the test solei (8 normal and 15 dystrophic) exhibited greater cross‐sectional area, total fiber number, and twitch and tetanus tensions than their contralateral controls. Test dystrophic solei contained more normal‐appearing and less abnormal‐appearing fibers than their controls. Their mean fiber resting potential was intermediate between those of normal and dystrophic controls. There is no difference in twitch time course between test and control solei. The results indicate that such transplantation improves the structure and function of the dystrophic muscles.
Autophagic degradation in human skeletal muscle target fibers
Authors: Mrak Robert E. , Saito Akitsugu , Evans Owen B. , Fleischer Sidney
Published: January 2005

Target fibers are a reliable histological sign of denervating processes in human skeletal muscle biopsies, although their pathogenesis remains obscure. We describe here autophagic multivesicular bodies at the center of target fibers. In addition, mitochondrial swelling and disintegration was observed in the intermediate zone surrounding the target center, which corresponds to the zone of dark staining with oxidative histochemical techniques seen with light microscopy. Honeycomb figures were present at the target center and at the fiber surface. These findings suggest that target fibers are a catabolic or involutional response to muscle denervation.
Segmental necrosis in tenotomized muscle fibers
Authors: Baker James H.
Published: January 2005

A study of the soleus muscle of the rat along its entire length during the first week following tenotomy was undertaken. Within the first few days the affected fibers of the soleus underwent a complete morphological reorganization. Portions of fibers near the tendons were Invaded by and replaced with a large population of phagocytes. Previous studies have implied that the number of sarcomeres in series is reduced, but it has not been demonstrated from what portion of the fiber the sarcomeres are revoved. Sections of fibers taken from the mid‐belly region demonstrated a progressive degenerative process over the first few days. Myofibrils across the entire width of the affected fibers underwent dissolution and degeneration. Fibers with central core lesions could be found by the seventh day after tenotomy, however, at this stage the peripheral myofibrils were new, and the fibers had begun the regenerative process which continued until normal fiber histology was restored.
Mallory body‐like inclusions in a hereditary congenital neuromuscular disease
Authors: Fidzianska Anna , Goebel Hans H. , Osborn Mary , Lenard Hans G. , Osse Günter , Langenbeck Ulrich
Published: January 2005

Subsequent to an earlier report on clinical and light microscopic data, peculiar Mallory body‐like inclusions are described in muscle fibers of three genetically linked children. These Mallory body‐like inclusions were unlike other well‐defined intramuscular inclusions, such as nemaline, cytoplasmic, fingerprint, or sarcoplasmic bodies, but morphologically quite similar to hepatic Mallory bodies, because they were composed of three components: granular material and two types of filaments. Evidence is presented that these inclusions may contain desmin, the intermediate filament type characteristic of muscle. The exclusive appearance of these Mallory body‐like inclusions in muscle biopsy specimens from theree genetically related children of a large kinship emphasizes the uniqueness of these Mallory body‐like inclusions in these muscle fibers as well as the special form of this congenital neuromuscular disorder.
Ultrastructure of the developing myotendinous junction of genetic dystrophic chickens
Authors: Sweeny Philip Randolph
Published: January 2005

This paper presents an ultrastructural study of the changes occurring within the tendon and at the insertion of the developing gastrocnemius of White Leghorn chickens and the dystrophic lines 413 and 423 from Davis, CA. The study revealed that the Davis lines contained abnormalities in these areas as early as 13 d in ovo with progressive deterioration to 19 d in ovo. The fibroblasts, collagen, and myofibers showed significant alterations as early as 13 in ovo. Fibroblasts contained abnormal mitochondria and altered Golgi bodies. At day 19, many were ruptured. The average diameter of collagen fibrils was smaller in the dystrophic chickens and myofibers showed a variety of alterations, some of which were severe. The details of these alterations are described and their possible relationship with the etiology of genetic muscular dystrophy is discussed.
Acute abdominal rhabdomyolysis after body building exercise: Is there a “rectus abdominus syndrome?”
Authors: Schmitt H. P. , Bersch W. , Feustel H. P.
Published: January 2005

Report of a 19‐year‐old man who was admitted to the hospital after vigorous exercise with signs of the “acute abdomen” syndrome. Since intestinal reasons for the complaints were excluded, a myocardial infarction was considered. However, the excessively increased serum CK levels indicated a disorder of the voluntary muscles. A biopsy taken from the rectus abdominis revealed typical features of acture rhabdomyolysis, which was obviously restricted to the rectus abdominis. Together with a somewhat later observed autopsy case of a young male with acute abdominal rhabdomyolysis, also restricted to the rectus abdominis, this case gives rise to discuss, whether there exists a “rectus abdominis syndrome” analogous to the anterior tibial syndrome.
Acetylcholine receptor turnover in clonal muscle cells: Role of plasmin and effects of protease inhibitors
Authors: Romstedt Karl , Beach Robert L. , Festoff Barry W.
Published: January 2005

Characteristics of acetylcholine receptors were evaluated in G8‐1, a continuous skeletal muscle line. Peak binding of 125I‐α‐bungarotoxin was in 10‐day‐old contractile myotubes at 4‐8 nm. Turnover was studied using two different methods; both indicated half‐times as little as half as long as previously reported for primary cultures. The effects of a variety of protease inhibitors on receptor turnover were assessed to determine if G8‐1 receptors were less stable or turned over faster because of increased neutral protease activity. Leupeptin, antipain, and chloroquine markedly slowed receptor degradation. Inhibitors of plasmin or plasminogen activator had definite but less dramatic effects on receptor turnover. Results from studies in which plasmin was increased in the tissue culture media indicated that a small but definite acceleration of receptor turnover occurred. In clonal G8‐1 cells, total number of acetylcholine receptors is controlled by negative feedback and although the major pathway for receptor degradation is lysosomal, plasmin may play a role in initiating receptor internalization.
Interaction of monoclonal antibodies to torpedo acetylcholine receptor with the receptor of skeletal muscle
Authors: Souroujon Miry C. , Mochly‐Rosen Daria , Gordon Adrienne S. , Fuchs Sara
Published: January 2005

Several monoclonal antibodies (mcAbs) elicited against the nicotinic acetylcholine receptor (AChR) from Torpedo react also with skeletal muscle AChR. Such mcAbs were used to define antigenic determinants on muscle AChR and to elucidate their effect on muscle AChR functions. Primary chick muscle cultures were used as a model for skeletal muscle. Of the four mcAbs studies only mcAb 5.5, which is directed against the cholinergic site in Torpedo AChR, blocks the binding of α‐bungarotoxin (α‐β) to AChR in chick muscle cultures and inhibits carbamylcholine‐induced sodium transport in these cells. The interaction of mcAb 5.5 with the cholinergic site on muscle AChR demonstrates the conservation of this site. Two mcAbs, 5.5 and 5.34, each of a different antigenic specificity but both directed against conformation‐dependent antigenic determinants, accelerate the degradation of AChR in muscle cultures. From the reactivity of the various mcAbs with Triton‐solubilized and membranous AChR it appears that there are some antigenic differences between the detergent solubilized and membranous forms of the receptor.
Effect of denervation on glycogen metabolism in fast and slow muscle of rat
Authors: Moruzzi Emma Villa , Bergamini Ettore
Published: January 2005

The postdenervation changes in glycogen metabolism were explored in fast (extensor digitorum longus, EDL), and slow (soleus, S) muscle of rat. During the first 12–14 hours after denervation, glycogen accumulates to a similar content in the two muscles, an effect reproduced by paralysis. Increase in the molecular weight of glycogen and decrease in the turnover rate of similar degree occur. During the ensuring 12–24 hours the glycogen concentration decreases in EDL (but not in S). This decrease is influenced by factors such as muscle type, longer or shorter nerve stump, age, and previous training of the animal. In both EDL and S, the rate of glucose incorporation into glycogen and the glycogen synthase [l/(l + D)] activity were depressed by denervation. The cAMP concentration increased 36 hours after denervation. This may have consequences on the muscle sensitivity to hormones. In fact, at this time, insulin did not increase glycogen synthase l activity or the glycogen content (with the exception of glycogen in S) and the effects of epinephrine on glycogen metabolism became more significant.
Membrane crystals of Ca2+‐ATPase in sarcoplasmic reticulum of normal and dystrophic muscle
Authors: Dux Laszlo , Martonosi Anthony N.
Published: January 2005

Two‐dimensional crystalline arrays of the Ca2+ transport ATPase develop after treatment of sarcoplasmic reticulum vesicles with Na3VO4. The dimensions of the crystal lattice are similar in sarcoplasmic reticulum membranes isolated from normal and genetically dystrophic human, mouse, and chicken muscles. These observations indicate similar requirements for ATPase‐ATPase interactions in sarcoplasmic reticulum of normal and dystrophic muscles and lessen the likelihood of a molecular defect of the Ca2+ pump in the various forms of genetic muscular dystrophies.
Susceptibility of mouse skeletal muscles to exercise injuries
Authors: Salminen Antero , Vihko Veikko
Published: January 2005

The susceptibility to exercise‐induced myopathy was studied by histological and biochemical methods in various skeletal muscles of mice 3–4 days after a single bout of prolonged running. The degree of exercise injuries varied greatly in different muscles. Soleus and the red deep parts of quadriceps femoris were the most severely affected muscles. Extensive or scattered necrosis of muscle fibers was associated with focal inflammation and a five‐ to nine‐fold increase in the activity of β‐glucuronidase in these muscles. Slight necrotic changes and a two‐ to three‐fold increase in the activity of β‐glucuronidase were observed in tibialis anterior, plantaris, and the red deep parts of gastrocnemius. A statistically significant increase in β‐glucuronidase activity was also observed in the white distal part of quadriceps femoris, biceps femoris, gracilis, extensor digitorum longus, and peroneal muscles but necrotic lesions were infrequent in these muscles. The degree of exercise injuries is probably affected by the different recruitment of muscles during running and by the anatomical location of muscles in separate compartments, which could expose them to differnt levels of ischemic compression by postexercise edema.
Divalent cations and temperature dependent block of impulse propagation at the frog neuromuscular junction
Authors: Eusebi Fabrizio , Miledi Ricardo
Published: January 2005

End‐plate potentials were recorded from superficial muscle fibers of the frog sartorius nerve‐muscle preparation. Exposure of the preparation to a medium containing a high divalent cation concentration, produced a temperature dependent failure of neuromuscular transmission. Failure of transmission developed in an “all‐or‐none” mode and was reversed by decreasing the bath temperature or divalent cation concentration. This blockage of the neurotransmission is attributed to a presynaptic block of impulse propagation.
Cylindrical spirals in skeletal muscle: A further observation with clinical, morphological, and biochemical analysis
Authors: Gibbels Ellen , Henke Ursula , Schädlich Hans‐J. , Haupt Walter F. , Fiehn Walter
Published: January 2005

Cylindrical spirals are abnormal uniform membranous inclusions in skeletal muscle, usually confined to type 2 fibers. Hitherto, only five cases have been published with various clinical syndromes. Here, a case is presented for the first time with detailed electrophysiological, histometrical, and biochemical analysis: a 60‐year‐old man with slowly progressing polyneuropathy confirmed by electrophysiological findings, and a history of diabetes, alcoholism, nicotine abuse, and weight reduction. In various muscle biopsies, large aggregates of cylindrical spirals were found almost exclusively in type 2B fibers. Obviously, the aggregates were derived from abnormal perinuclear and, therefore, mainly subsarcolemmal tubulovesicular structures. Morphometrical, histochemical, and biochemical analysis of muscle revealed no further information about the nature of these inclusions. They were not present in skin biopsy containing subcutaneous nerves.
The effect of spinal cord transection on motor units in cat medial gastrocnemius muscles
Authors: Mayer R. F. , Burke R. E. , Toop J. , Walmsley B. , Hodgson J. A.
Published: January 2005

We studied the properties of whole medial gastrocnemius (MG) and soleus muscles, and of 74 individual MG motor units in three cats with long‐term complete low thoracic spinal transection (TS). All animals remained paraplegic and there was considerable atrophy of MG and soleus muscles. Motor units in the MG pool were readily classified into the same groups, types FF, F(int), FR, and S, found in normal MG, but tetanic force outputs and mean fiber areas for the corresponding muscle fiber types were decreased in all unit types as were isometric twitch contraction times. The proportion of type F(int) motor units was greater (19.0%) than expected from normal samples (5.8%) and this was also true of the corresponding type 2AB muscle fibers (6.9% in TS vs 3.3% in controls). In addition, FR and S units were less numerous (17.5% each) than in control muscles (23.0% and 25.2%, respectively), and histochemical examination revealed a similar decrease in the percentage of type 2A (11.6%) and 1 (16.4%) fibers compared with controls (20.0% and 30.5%, respectively). The changes found in chronic paraplegic atrophy were different in some details from those found after chronic simple limb immobilization.
The effect of denervation on mammalian sarcolemmal proteins and glycoproteins
Authors: Leung Wing Nang , Jeffrey Peter L. , Rostas John A. P.
Published: January 2005

The effects of surgical denervation on proteins and glycoproteins of sarcolemmal membranes have been investigated using sarcolemmal fractions prepared from mixed rat muscles. Denervation did not cause any gross change in the protein composition but some consistent quantitative changes were detected. Denervation caused a significant increase in the binding of 125l‐labeled concanavalin A (ConA), Ricinus communis agglutinin (RCA120), and wheat germ agglutinin (WGA) to intact membranes. This increased binding appears to be brought about by two mechanisms: the synthesis of more binding‐sites with the same apparent KD and the unmasking of previously cryptic binding sites. The activity of sialyl‐, galactosyl‐, and N‐acetylglucosaminyltransferases in the sarcolemmal fractions increased, whereas fucosyl‐glycoprotein‐transferase activity decreased following denervation. Kinetic analysis of the sialyl‐ and galactosyltransferase activities showed that the change was due to an increase in Vmax with no change in Km. These results are consistent with an increase in the turnover of sarcolemmal glycoproteins following denervation.
Accessory nerve stimulation in the assessment of myasthenia gravis
Authors: Schumm Fritz , Stöhr Manfred
Published: January 2005

Repetitive nerve stimulation (5/second) was done at the median nerve at the wrist and at the accessory nerve just behind the sternocleidomastoid muscle before and 20 seconds to 5 minutes after tetanic nerve stimulation (1 minute). Since the degree of the neuromuscular block depends on the body temperature these investigations were done successively at skin temperatures of 32°C and 36°C. A comparison of the results obtained revealed the highest rate of pathologic decrement with posttetanic accessory nerve stimulation (32°C = 77%, 36°C = 87%), whereas with posttetanic median nerve stimulation pathological results were obtained in a significantly lower proportion (32°C = 50%, 36°C = 60%). The advantages of the stimulation of the accessory nerve for the detection of partial neuromuscular block are: 1. The superficially located accessory nerve allows for supramaximal stimulation with rather low stimulus intensities (6–20 mA). 2. Since the accessory nerve is mainly a motor nerve, the stimulation is less painful than the stimulation of a mixed nerve. 3. Stimulation of a proximal nerve is more sensitive for detecting a defect in neuromuscular transmission than stimulation of a distal nerve. 4. There is no risk of a pneumothorax and of a traumatic nerve lesion as there is with stimulation of the brachial plexus by needle electrodes.
Early effects in vitro of the muscular dysgenesis mutation on nervous tissue in the mouse
Authors: Wieczorek David F.
Published: January 2005

Muscular dysgenesis (mdg), a disease expressed in embryonic mice, severely affects the formation and differentiation of skeletal musculature. The focus of this investigation was an analysis of dysgenic nervous tissue with special attention centered on interactions between muscle and nerve cells in vitro. Results indicate that mdg/mdg spinal cord cells can form functional neuromuscular junctions in nervehyphen;muscle cocultures and induce contractions in dysgenic muscle. However, dysgenic spinal cord cells induce fewer myotubes to contract and result in a delayed induction of dysgenic myotube contractile activity. Furthermore, mdg/mdg nervous tissue, or its conditioned medium, is associated with a higher incidence of morphologically abnormal myotube contractures. The results from this investgation demonstrate that there are functional abnormalities in both dysgenic muscle and nervous tissues which are stable and expressed for up to 3 weeks in vitro.
Single fiber electromyography in the differential diagnosis of myopathic limb girdle syndromes and chronic spinal muscular atrophy
Authors: Shields Robert W.
Published: January 2005

Single fiber electromyography (SFEMG) of the extensor digitorum communis muscle was performed on 20 patients with either myopathic limb girdle syndromes (LGS) or chronic spinal muscular atrophy (CSMA) to assess its value in the differential diagnosis of these disorders. Neurologic examinations (muscle biopsies, standard electromyography, or both) were reviewed in 16 patients and resulted in diagnosing LGS in 11 patients and CSMA in 5 patients. In four patients, discordance between EMG and biopsy, or mixed features of myopathy and neuropathy in either test, resulted in an indeterminate diagnosis. Two groups were discerned from SFEMG, one with higher fiber density, jitter, and percentage of abnormal pairs consistent with neuropathy and another with lower values consistent with myopathy. In all 16 patiets, SFEMG confirmed the initial diagnosis, and in the four patients with indeterminate diagnoses, SFEMG suggested diagnoses of LGS in two patients and CSMA in two patients. Single fiber electromyography may be a useful diagnostic aid in the differential diagnosis of myopathic LGS and CSMA.
Nerve regeneration in exogenous cerebral ganglioside‐treated rats
Authors: Sebille Alain
Published: January 2005

Intraperitoneal injection of 50 mg/kg of exogenous cerebral gangliosides resulted in a statistically significant (23%) increase (compared with saline‐injected controls) in the tetanic isometric tension of the rat plantaris muscle 7 days after section of the fourth lumbar root (L4). In a second experiment, intraperitoneal‐injected exogenous gangliosides were found to have no effect on axonal regeneration following cryoinjury to the sciatic nerve. These results lead to the possibility of an early enhancement of muscular collateral sprouting in partially denervated muscles under an intraperitoneal‐injected ganglioside mixture treatment.
Motor axon loop: An electroneurographic response
Authors: Roth G. , Egloff‐Baer S.
Published: January 2005

A new kind of response to the stimulation of the median and ulnar nerves was observed in 10 patients. It is a motor unit showing a late latency in response to a weak stimulus and then suddenly a normal latency when the intensity is increased to a critical level. These two responses can be evoked at any level of a distinct nerve segment, the difference between their latencies being constant. The late response cannot be elicited below this segment and the normal response cannot be elicited above this segment. Its F‐latency is delayed and does not vary when the late response changes in a normal one. The conduction velocity along the axon seems normal. We propose the hypothesis of a motor axon loop along the nerve, with the recurrent portion traveling in the “grandes ellipses” or the classical anastomosis. These kinked axons are probably congenital; their frequency is still unknown.
Temperature sensitivity of tension development in a fast‐twitch muscle of the rat
Authors: Elmubarak Murtada H. , Ranatunga K. W.
Published: January 2005

Isometric contractions of the biceps brachii (short head) muscle in the rat were recorded in vitro with direct stimulation and at different temperatures (range, 35°C–10°C). In confirmation of our previous findings from fast extensor digitorum longus and slow soleus muscles, the time and rate parameters of the twitch and the tetanus showed an increased temperature sensitivity below 20°C. The dependence on the initial muscle length of the rate of rise of tetanic tension was examined at 27°C and at 15°C. When represented as a percentage of the tetanic tension at each length, the rate of rise was independent of muscle length at both temperatures. Our interpretation of this particular observation is that the increased cooling depression of the rate of tension rise below 20°C is not associated with a qualitative change in its underlying basis.
Myofibrillar M‐line structure in normal and dystrophic hamster muscle
Authors: Eppenberger Monika E. , Schoenenberger Ronnie , Eppenberger Hans M.
Published: January 2005

The presence of the specific myofibrillar M‐line marker, myomesin, in isolated myofibrils and cryosections of skeletal and heart muscle as well as its appearance during differentiation in skeletal and heart muscle cell cultures of normal and dystrophic hamsters were evaluated. By means of the indirect immunofluorescence technique employing antibodies against chicken M‐line proteins, the appearance of antigen localized in the M‐line was investigated. No difference could be found between the M‐line structure of normal and dystrophic animals. The results suggest that the M‐line proteins, apparently relatively stable, are not primarily affected by the disease.
Differentiation in dystrophic muscle cultures from mice of different ages
Authors: Bryers Paul S. , Ecob Marion S.
Published: January 2005

Muscle from dystrophic (129 ReJ dy/dy) mice, aged 1, 2, 3, 4, and 6 months, was cocultured with normal embryonic mouse spinal cord. Cultures were scored for regeneration (myotubes) and differentiation (cross‐striated or contracting fibers) over a 28‐day period. Although muscle from dystrophic mice of all ages was able to regenerate, the ability to differentiate decreased with the increasing age of the mouse. Muscle from litter‐mate control mice of different ages regenerated and differentiated equally well.
The clinical role of somatosensory evoked potential studies: A critical appraisal
Authors: Aminoff Michael J.
Published: January 2005

The clinical utility and limitations of somatosensory evoked potential (SEP) studies are reviewed. Somatosensory evoked potentials may help to identify a lesion in the sensory pathways, but do not indicate its nature. In multiple sclerosis subjects, the SEP findings may help to establish that there is a multiplicity of lesions, but multimodality evoked potentials abnormalities may occur in other disorders. Somatosensory evoked potential abnormalities do not reflect either the severity or the prognosis of cervical spondylosis and do not reliably permit early recognition of the totality of traumatic cord lesions, while the role of SEPs in monitoring cord function intraoperatively awaits definition. Somatosensory evoked potentials do not reliably indicate the individual prognosis after severe head injury, and discrepancies in published findings suggest that their use in the evaluation of brain death is premature. In hereditary spinocerebellar degenerations, SEP abnormalities may reflect central or peripheral pathology. Somatosensory evoked potentials can be used to determine conduction velocity in peripheral nerves and to identify inaccessible proximal lesions of these nerves, but the findings may lead to misleading conclusions about brachial plexus lesions, especially if pre‐ and postganglionic lesions coexist.
A morphometric study of intrafascicular vessels of mammalian sciatic nerve
Authors: Bell Mary A. , Weddell A. G. M.
Published: January 2005

Intrafascicular vessel profiles were measured with a Quantimet image analyzer in 1‐μm transverse sections of sciatic nerves of rats and compared with those of (“white”) skeletal muscle. Blood vessels occupy the same percentage of the total tissue area in nerve and muscle tissues. The nerve, however, has much larger capillaries (about 1.7 ×) spaced farther apart (about 2.5 ×). Comparison of 3½ month with 1‐year‐old rats showed that muscle capillaries increased in diameter (slightly, but significantly) at maturity, but those of the nerve decreased (also significantly). Vascular percentages of total tissue areas did not change. Nerve and muscle samples from monkey, rabbit, mouse, and cat show that the same striking pattern of large, widely spaced vessels distinguishes the nerve from other tissues. Minor interspecies variations exist. The nerve may contain as much blood as the muscle but its angioarchitecture suggests a lower exchange capacity.
Elevated ammonia release from dystrophic chicken muscle cell and fibroblast cultures
Authors: Young Ronald B. , Hopkins Linda H. , Fleming George D.
Published: January 2005

The activity of adenosine monophosphate (AMP)‐aminohydrolase, the major NH3‐producing enzyme in skeletal muscle, was approximately 35% lower in 7‐day dystrophic muscle cell cultures than in normal muscle cells cultures. However, the release rate of NH3 from dystrophic muscle cells was 45% higher than that from normal muscle cells. The reasons for this apparent discrepancy are not clear. To determine indirectly if deamination of amino acids from protein degradation contributed to NH3 release, cells were incubated with 100 μg/ml of the protease inhibitor, leupeptin. Leupeptin reduced the rate of NH3 release by only 18.8% in normal muscle cells and 16% in dystrophic muscle cells. The release of NH3 was also higher from dystrophic chicken fibroblast cultures.
Sensory group la proximal conduction velocity
Authors: Eisen Andrew , Hoirch Maureen , White James , Calne Donald
Published: January 2005

The fastest median and ulnar velocities derived by recording motor and mixed nerve action potentials, F waves, H‐reflexes, and somatosensory evoked potentials (SEPs) were compared. H‐reflex recording was facilitated by employing selective group la excitation during voluntary muscular contraction. Mixed nerve, SEP, and H velocities, considered to predominantly reflect group la conduction, measured 63.2 ± 3.2 m/sec, 63.4 ± 4.5 m/sec, and 67.2 ± 4.3 m/sec, respectively, between the wrist and elbow. Conventional motor conduction velocity was significantly slower (58.3 ± 5.1 msec), but F velocity, which although nonuniform is also a measure of motor conduction, was 68.4 m/sec. Mean F latency was considered more reliable and representative than minimum F latency. F and H velocities accelerated proximally by 4.5 m/sec. They complement each other when evaluating motor and sensory group la conduction. The H‐reflex and SEP use identical stimulus characteristics and when simultaneously recorded allow direct comparison of the fastest conducting peripheral and central sensory pathways.
Nifedipine relieves exercise‐exacerbated myalgias
Authors: Sufit Robert L. , Peters Henry A.
Published: January 2005

Three women with exercise‐exacerbated myalgias refractory to usual medications are described who responded favorably when the calcium channel blocker, nifedipine, was administered. The side effects were dose‐related and prevented complete resolution of the symptoms. Three potential mechanisms of action are suggested for these effects.
An insulin receptor defect in murine muscular dystrophy
Authors: Hofmann William W.
Published: January 2005

A study has been made of the I125 insulin binding and postbinding effects on excised soleus muscles from the 129 ReJ strain of dystrophic mice. Results are compared with those in sex‐ and weight‐matched controls. The data suggest that, in the range of physiological hormone concentrations, the affinity of insulin receptors on dystrophic muscles is less than normal and that the insulin‐dependent uptake of both 2‐deoxyglucose (2‐DG) and aminoisobutyric acid (AIB) is impaired. These findings are taken to indicate that many of the biochemical and electrophysiological abnormalities observed in murine dystrophy could arise from some genetic defect in the receptor proteins controlling uptake of raw materials.
Conduction block in compression neuropathy: Recognition and quantification
Authors: Olney Richard K. , Miller Robert G.
Published: January 2005

Previous reports of conduction block in compression neuropathy have used the amplitude difference of the compound muscle action potential (CMAP) comparing proximal with distal stimulation. The present study was undertaken to determine if area reduction of the proximal CMAP provides diagnostic information that is not included in amplitude reduction, particularly in distinguishing conduction block from temporal dispersion. Digitized, integrated area measurements were compared with amplitude and, as a convenient estimate of area, the calculated Mindex (1/2 duration x amplitude). Amplitude reduction did not reliably distinguish conduction block from temporal dispersion in compression neuropathy. Both in the investigation of conduction block and in the management of compression neuropathy, integrated area measurement allows for the more accurate identification and quantification of conduction—a usually reversible cause for weakness in compression neuropathy.