bluuebunny/crossref_metadata_2025 huggingface dataset:
Uniform frequency of parkinsonian resting tremor in the lips, jaw, tongue, and index finger
Authors: Hunker Chauncey J. , Abbs James H.
Published: January 2005

Parkinsonian resting tremor was examined in the lips, jaw, tongue, and index finger using electromyography (EMG) and displacement transduction. Long‐term spectral averaging of tremor movement and EMG signals revealed that resting tremor frequencies were remarkably uniform across these orofacial and hand structures within the same parkinsonian subjects. However, marked variability in tremor spectral amplitude across structures and subtle moment‐to‐moment variations in tremor period, amplitude, and waveform shape were also observed. Although these observations argue for a central source of tremor, it appears that interactive central and/or peripheral neural circuitry may yield variations in tremor characteristics.
Pharmacokinetic comparison of sinemet and atamet (Generic carbidopa/levodopa): A single‐dose study
Authors: Pahwa R. , Marjama J. , McGuire D. , Lyons K. , Zwiebel F. , Silverstein P. , Ward R. , Koller W. C.
Published: January 2005

We compared the pharmacokinetic and motor responses of Sinemet and Atamet (generic carbidopa/levodopa) in patients with Parkinson's disease. Thirty Parkinson's disease patients (10 previously untreated, 10 with early disease, and 10 with motor fluctuations/dyskinesia) participated in a single‐dose double‐blind study. Following administration of an equivalent oral dose of Sinemet and Atamet on two separate days, we compared the peak plasma concentration, time to peak plasma concentration, area under the curve, total motor score, tapping score, and walking time. The mean time to peak plasma concentration was 49 min with Sinemet and 47 min with Atamet, the mean peak plasma concentration was 1,273 ng/ml with Sinemet and 1,153 ng/ml with Atamet, and the mean area under the curve was 2,295 m̈g/ml/h with Sinemet and 2,330 m̈g/ml/h with Atamet. Similarly, there was no significant difference between total motor score, tapping score, of walking time. In this single‐dose study, there were no significant differences in pharmacokinetic and motor responses between Sinmet and Atamet.
Infiltrating lipoma: A cause of monomelic hypertrophy
Authors: Fetell Michael R. , Duffy Philip E. , Rowland Lewis P.
Published: January 2005

Muscle biopsy and computerized tomography indicated that unilateral enlargement of the gastrocnemius muscle in a 12‐year‐old girl was the result of an infiltrating lipoma. This rare condition may cause diagnostic confusion before EMG and muscle biopsy studies are performed, but it can be readily distinguished from other causes of unilateral muscle enlargement using these methods.
Choline acetyltransferase and acetylcholinesterase in muscular dystrophic mice
Authors: Sung S. C.
Published: January 2005

The activities of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were assayed in various tissues of dystrophic (dy/dy) and normal mice of Bar Harbor strain 129. The brain weights of these dystrophic mice were not significantly different from those of normal mice, but the average body weight of these dystrophic mice was only 66.8% of that of the controls. The activity of CAT (expressed as unit activity per mg of protein) was very similar in the brains of both groups of animals, but the CAT activity (per mg of protein) in the hindlimb muscles of the dystrophic mice was significantly higher than that of the controls. The patterns of AChE activity, as separated by sucrose density gradient centrifugation, were distinctly different in extracts of dystrophic and normal muscle. Compared with controls, decreased activity of the 15‐S and 10‐S forms of AChE, with increased activity of a 4.3‐S forrn of AChE, was observed in dystrophic muscle.
Myosin polymorphism in human skeletal muscles
Authors: Libera Dchem L. Dalla , Margreth A. , Mussini I. , Cerri C. , Scarlato G.
Published: January 2005

Myosins isolated from individual human muscles (primarily normal muscles) were investigated with respect to their structural and catalytic properties. The results indicate unexpected elements of uniformity shared by the several myosins, such as a three‐banded, electrophoretic pattern of light chains in sodium dodecylsulfate (SDS) gels and a low degree of alkaline lability. The pH activity profile and the effect of KCl on myosin ATPase activities were also found to be the same for the myosins from predominantly fast (e.g., vastus lateralis and rectus abdominis) and slow (e.g., soleus and pectoralis minor) muscles. Coelectrophoretic experiments lend further credence to the interrelationship between human myosin light chains and the light chains of rabbit fast‐muscle myosin. However, several kinds of circumstantial evidence, such as that derived from the study of myosin in nemaline myopathy, suggest that one should exercise caution in interpreting these results. On the other hand, human muscle myosins, like those of other mammalian species, can be divided into two main categories according to the peptide composition of tryptic heavy meromyosin (HMM) and the banding pattern of light meromyosin (LMM) paracrystals. These results, which are indicative of differences in the primary structure of the heavy chains, allow us to identify these heavy chains as the main site of heterogeneity among myosins in human muscles.
Early electrophysiologic changes in conduction block
Authors: Trojaborg W.
Published: January 2005

Fibrillation potentials and positive sharp waves were recorded in the paralyzed muscles of 31 patients with a conduction block of more than 14 days' duration. In 75% of the muscles, these effects were attributed to axonal damage in addition to the local demyelinating block, this conclusion being based on changes in the properties of the motor unit found electromyographically when recovery had taken place. In the remaining 25% of the muscles, the denervation‐like activity was thought to be an effect of the local demyelinating block alone. The delay of the sensory action potential recorded above the presumed site of nerve compression most likely arises from a block of the largest myelinated nerve fibers. This assumption is based on the fact that the amplitudes of the fastest‐ and the slower‐conducted components in the patients differed little from corresponding components in the normal nerve.
Experimental autoimmune myasthenia gravis in the rat: A preliminary report
Authors: Krarup Christian , Elfman Lena , Kamieniecka Zofia , Schmalbruch Henning
Published: January 2005

In chronic experimental myasthenia gravis (EAMG) in rat, the decrement of electrical and mechanical responses evoked by maximal repetitive (3–167/sec) stimuli to the nerve was greater in the slow‐twitch soleus (SOL) than in the fast‐twitch extensor digitorum longus (EDL) muscle. Excitation‐contraction coupling was impaired in moderate to severe EAMG, as evidenced by a diminished staircase phenomenon and by diminished posttetanic potentiation (PTP) of twitch tension in two EDLs. The only morphologic abnormality observed was an increase in length of the endplates in the EDLs of those animals that had had an acute phase of EAMG. The latter had more than a 90% reduction in the amplitude of the action potential and in the twitch tension of the EDL when stimuli were applied to the nerve. Stimuli applied directly to the muscle evoked a tetanic tension that was one‐third of normal. The staircase and PTP were normal. Necrosis occurred in the endplate and in the adjacent segment of muscle fiber; outside the endplate region, the muscle fiber was normal.
Elements in muscle measured in vivo and in vitro with X‐ray spectrometry
Authors: Yarom Rena , Havivi Yael , Notowitz Luta , Friedman Margalit , Gorodetsky Raphael , Zeimer Ran
Published: January 2005

Calcium, iron, copper, and zinc concentrations in muscle were measured in vivo by x‐ray spectrometry (XRS). The undersurface of the tongue was examined in cardiomyopathic and in normal hamsters. Values were compared to in‐vitro analyses of various muscles from the same groups of animals using XRS and chemical analysis. Blood tests as well as histologic and histometric examinations were also performed. The correlated results show that XRS is a relatively sensitive and practical method for measuring chemical elements in muscle, and that it could be developed into a useful clinical test in certain neuromuscular and myocardial diseases. An interesting incidental finding was that, though all the examined muscles of myopathic animals had pathologic changes, only the tongue and myocardium, which are composed exclusively of red fibers, showed excessive calcium accumulation. This suggests either that the basic genetic aberration is not directly related to the oxidative metabolism, or that white muscles have a more efficient system for dealing with calcium overload.
Neuroanastomosis of orthotopically transplanted palmaris longus muscles
Authors: Maxwell L. C. , Faulkner J. A. , Markley J. M. , Winborn D. R.
Published: January 2005

Palmaris longus (PML) muscles of rhesus monkeys were transplanted, with or without anastomosis of the median nerve, to the nerve stump of the autograft. Because PML autografts revascularize spontaneously, vascular anastomoses were not performed. Muscle fibers regenerated in all autografts with neuroanastomosis, but in only three of eight autografts without neuroanastomosis. Five autografts without neuroanastomosis were replaced by noncontractile connective tissue. Growth and differentiation of muscle fibers into three fiber types and development of capillarity were analyzed histochemically, and succinate oxidase activity of whole‐muscle homogenates was determined. None of these measures reached values for control PML muscles within 100 days of transplantation. In comparison to control muscles, autografts had slower times to peak tension and less absolute tension, but similar tension per square centimeter of muscle fiber cross‐sectional area. Monkey PML autografts with neuroanastomosis were similar in structure and function to cat extensor digitorum longus autografts that had not had neuroanastomosis.
F chronodispersion: A new electrophysiologic method
Authors: Panayiotopoulos Chrysostomos P.
Published: January 2005

We have introduced the term F chronodispersion to denote the scatter or dispersion of the relative latencies of statistically significant numbers of consecutively recorded F waves. Five patients with chronic renal failure and five control subjects were studied. The two groups were matched for age, sex, proximal and distal motor conduction velocity, and latency of fast F waves plotted against distance traveled. We found that the extent of F chronodispersion of the deep peroneal nerve did not exceed 7.5 msec in control subjects, while it was longer than this value in all uremic patients studied. Measurements of this type may prove to be a useful diagnostic tool for cases in which traditional electrophysiologic measurements are normal.
The autosomal recessive (Becker) form of myotonia congenita
Authors: Erich Kuhn S. , Fiehn Walter , Seiler Dieter , SchröDer Joachim‐Michael
Published: January 2005

In the last two decades, two genetically distinct forms of myotonia congenita have been identified—an autosomal dominant and an autosomal recessive form. The purpose of this review is to describe the features that enable us to distinguish between these two forms in the absence of sufficient genetic data. Thus far, it can be concluded that the only probable difference between the two forms is in the fatty‐acid pattern of muscle phospholipids. Clinical, histologic, ultrastructural, and electromyographic investigation may prove helpful, but they alone cannot provide a reliable means of identifying the genotype in an individual patient.
Type III glycogenosis with multicore structures
Authors: Pellissier S. J. F. , de Barsy Th. , Faugere M. C. , Rebuffel P.
Published: January 2005

A case of an infantile type III glycogenosis (Forbes disease), confirmed by morphologic and biochemical studies, had light‐microscopic, histochemical, and electron‐microscopic evidence of multicore structures and type 1 fiber predominance with hypotrophy. This association is discussed with relation to the unusual clinical findings. The authors conclude that two distinct disease entities—Forbes disease and multicore myopathy—may coexist.
Myoadenylate deaminase deficiency
Authors: Shumate Jack B. , Katnik Richard , Ruiz Martha , Kaiser Kenneth , Frieden Carl , Brooke Michael H. , Carroll James E.
Published: January 2005

Myoadenylate deaminase (adenosine monophosphate deaminase—AMPDA) was recently shown to be deficient in a group of patients by use of a histochemical and biochemical method based on the elaboration of ammonia by this enzyme as it deaminates 5′ AMP. We have confirmed the utility of this histochemical method and the existence of persons deficient in AMPDA through the use of an unrelated assay technique. The lack of enzyme activity is not associated with any inhibitory activity in the muscles of patients with this disorder. The clinical diversity of these patients suggests that this lack may represent a normal variant or a subclinical state rather than an actual disease. The occurrence of AMPDA deficiency in both sexes points to possible autosomal inheritance.
Muscle breakdown and repair in polymyositis: A case study
Authors: Edwards H. T. , Wiles C. M. , Round J. M. , Jackson M. J. , Young A.
Published: January 2005

Muscle breakdown and repair were measured by metabolic balance techniques in a patient with polymyositis who was being treated with prednisolone and azathioprine. Changes in body muscle mass that had been estimated from nitrogen and phosphorus balances correlated with anthropometric assessments of thigh muscle mass and quadriceps strength. Decline in muscle strength was associated with a net rate of muscle breakdown of 148 g/day. Recovery was associated with a net rate of muscle repair of up to 100 g/day. Early reduction in corticosteroid treatment appeared to enhance the rate of repair. Changes in the isometric contraction force of the quadriceps muscle (but not in clinical symptoms, plasma creatine kinase [CK] or erythrocyte sedimentation rate [ESR]) were found to reliably indicate whether the muscle was in a state of breakdown or repair. Treatment of the individual patient may be quantitatively monitored by metabolic balance studies or, more simply, by measurement of muscle strength.
Contractile responses of rat fast‐twitch and slow‐twitch muscles to glucocorticoid treatment
Authors: Gardiner Phillip F. , Edgerton V. Reggie
Published: January 2005

In an attempt to determine whether chronic glucocorticoid treatment affects speed‐ and strength‐related properties of fast‐twitch muscle and slow‐twitch muscle, in‐situ contractile properties of soleus and gastrocnemius muscles were measured in rats after 14 days on a regimen of triamcinolone acetonide injected at a dosage of 2 mg/kg/day. No effects on contractile speed or strength were noted for either muscle. The time to peak tension in soleus muscle was significantly longer in the treated group (43.0 ± 1.0 msec) than in the control group (38.7 ± 0.7 msec); however, this was attributed to a prolongation of “active state” duration, as suggested by the fact that treated muscles also showed significantly elevated twitch‐tetanus ratios. The treatment‐induced enhancement of the specific twitch tension was more pronounced in the gastrocnemius muscles (198% ± 19% of control) than in the soleus muscles (153% ± 9% of control). The difference in response to steroid treatment may reflect structural and functional difference in fast‐ and slow‐muscle membrane systems.
Morphologic changes in extraocular muscles of the dystrophic hamster
Authors: Percy D. H. , Thakar J. H. , Strickland K. P.
Published: January 2005

Cardiomyopathic hamsters (UM‐X7.1 strain) have demonstrable myopathy involving both skeletal and cardiac muscle. In addition, they have multiple ocular abnormalities. In this study, extraocular muscles were examined by light and electron microscopy. Changes observed within affected muscle fibers were variable and included coagulation necrosis, lysis of myofibrils, mitochondrial changes, and infiltration by phagocytic cells. Regenerative changes included duplication of myoblast nuclei, proliferation of sarcoplasmic reticulum, and myofibrillogenesis. The lesions are presumably myogenic in origin. The cardiomyopathic hamster may be useful as an animal model for certain types of ocular myopathy in man.
Increased endoneurial fluid pressure in galactose neuropathy
Authors: Myers Robert R. , Costello Michael L. , Powell Henry C.
Published: January 2005

Edema and increased endoneurial fluid pressure developed in peripheral nerves of rats that received a diet containing 40% galactose during a study of the role of sugar alcohols in producing neuropathy. Fluid pressure was elevated starting in the third month and progressed to a fivefold increase over control values by the fifth month. Microscopic examination confirmed the presence of edema as predicted by the sorbitol theory, which is often invoked to explain the pathogenesis of diabetic neuropathy.
Defective oxidative metabolism of myodystrophic skeletal muscle mitochondria
Authors: Lee C. P. , Martens M. E. , Jankulovska L. , Neymark M. A.
Published: January 2005

A small‐scale procedure for preparing tightly coupled intact skeletal muscle mitochondria from myodystrophic (myd/myd) mice is described. Mitochondrial preparations derived from heart, liver, and skeletal muscle of myd/myd and their littermate (+/?) controls are characterized with respect to their cytochrome content and their oxidative and phosphorylative capacities. Our data indicate that there is an impairment in the NADH CoQ region of the respiratory chain of myodystrophic skeletal muscle mitochondria. Both heart and liver mitochondria of myd/myd exhibited normal activities of respiratory chain‐linked oxidative phosphorylation.
Experimental myotonia induced in denervated muscles by 2,4‐D
Authors: Eberstein Arthur , Goodgold Joseph
Published: January 2005

Rats were denervated in one hind limb and injected with 2,4‐dichlorophenoxyacetic acid (2,4‐D). Isotonic tetanic contractions of the muscles treated with 2,4‐D after more than 10 days of denervation revealed prolonged relaxation times similar to those of the intact side and characteristic of clinical myotonia. No myotonic discharges were observed in the muscles denervated for more than 10 days and treated with 2,4‐D. The increase in threshold for action potential generation secondary to denervation is suggested as the factor limiting the initiation of the repetitive discharges.
Chloroquine‐induced cytosomes with curvilinear profiles in muscle
Authors: Neville Hans E. , Maunder‐Sewry Caroline A. , McDougall Jennifer , Sewell John R. , Dubowitz Victor
Published: January 2005

A patient with systemic lupus erythematosus (SLE) was treated with chloroquine therapy for four years after the onset of her illness. Nine years after cessation of chloroquine, muscle weakness developed as part of the SLE. Four muscle biopsies performed for diagnostic purposes revealed varying degrees of inflammatory change as well as distinctive cytosomes with curvilinear profiles (CCPs). These CCPs were identical to those reported in Batten disease, a degenerative disorder of children which has a clinical course different from SLE. The CCPs seen in this case of SLE are thought to result from the effect of chloroquine on membrane systems within muscle cells. This report calls attention to the fact that CCPs are not unique to Batten disease but may also occur in muscle of SLE patients treated with chloroquine.
The importance of serum pyruvate kinase in neuromuscular diseases and carrier states
Authors: Sage Jacob , Inati Yakub , Samaha Frederick
Published: January 2005

Serum pyruvate kinase activity was measured in several myopathic and denervating illnesses as well as in 86 potential carriers of Duchenne dystrophy. These data showed that in potential Duchenne carriers, the serum pyruvate kinase assay is more sensitive in younger patients, especially those under 20 years of age.
Motor neuron firing range, axonal conduction velocity, and muscle fiber histochemistry in neuromuscular diseases
Authors: Borg J. , Grimby Lennart , Hannerz Jan
Published: January 2005

The voluntary discharge properties and axonal conduction velocity of single motor units were studied in patients with neuromuscular diseases with retained differentiation of the muscle fibers into type 1 and type 2, and in patients with late‐onset hereditary distal myopathy in which muscle fibers have only intermediate histochemical properties. In the patients with muscle fiber differentiation, the findings were similar to those in normal subjects; that is, there was a continuum between motor units which fired tonically at low rates and had a low axonal conduction velocity, and motor units which fired phasically at high rates and had a high axonal conduction velocity. In the patients without muscle fiber differentiation, all motor units had intermediate firing properties and a low axonal conduction velocity. It is suggested that in chronic pathologic states, the differentiation of the muscle fiber histochemistry remains only as long as the differentiation of the motor neurons remains.
Types of human intrafusal muscle fibers
Authors: Kucera Jan , Dorovini‐Zis K.
Published: January 2005

The histochemical and fine structural profiles of human intrafusal muscle fibers were studied. Spindles were located in freshly frozen specimens taken from biopsied normal external intercostal muscles, and periodic 10‐ and 50‐μm‐thick cross sections were processed alternately for enzyme histochemical and electron microscopic examination. Nuclear bag fibers were of two types, bag1 and bag2, histochemically, and they displayed two distinct types of ultrastructure. Nuclear chain fibers were histochemically and ultrastructurally homogeneous. Regional differences in enzymatic staining and ultrastructure occurred along individual intrafusal fibers. Human bag1 and bag2 fibers appear to be analogous to the two types of nuclear bag fiber identified in animal spindles and are considered to have different roles in spindle function. The presence of three types of intrafusal fibers should be taken into account when studying spindle abnormalities in human neuromuscular disorders.
Physical probes of biological membranes in studies of the muscular dystrophies
Authors: Barchi R. L.
Published: January 2005

This review deals with recent physical approaches to the study of biomembranes. First, current concepts of the structure and dynamic organization of biological membranes are considered. The theoretical basis and practical application of various physical probe techniques are then discussed with specific reference to their usefulness in studies of these membranes. Particular emphasis is given to electron spin resonance and fluorescence techniques and to the potential difficulties encountered in their use and interpretation. Finally, reports applying these physical probes to various aspects of the human muscular dystrophies are reviewed and our current information in this area is summarized.
Facilitatory effects of 4‐aminopyridine on neuromuscular transmission in disease states
Authors: Kim Yong I. , Goldner Marcia M. , Sanders Donald B.
Published: January 2005

The in vitro effects of 4‐aminopyridine (4‐AP) on neuromuscular transmission were determined by microelectrode techniques in intercostal muscles from patients with myasthenia gravis (MG) and the Eaton‐Lambert syndrome (ELS), and in forelimb muscles from rats with experimental autoimmune myasthenia gravis (EAMG). In MG and EAMG, the amplitudes of miniature endplate potentials (MEPPs) and endplate potentials (EPPs) were reduced, and there was increased sensitivity to the blocking action of d‐tubocurarine (dTc). In ELS, MEPP amplitude was normal but the average number of acetylcholine quanta released by nerve impulses was reduced, causing subthreshold EPPs. In EAMG muscle, 4‐AP produced dose‐dependent increases in EPP amplitude and in the duration of indirectly elicited muscle action potentials but no changes in MEPP amplitude and resting membrane potential. 4‐AP completely reversed the postsynaptic blockade produced by dTc and EAMG. 4‐AP appears to facilitate neuromuscular transmission in EAMG, MG, and ELS by increasing the neurally evoked transmitter release, thus overcoming either the pre‐ or the postsynaptic neuromuscular blockade.
Peripheral neuropathy associated with disulfiram administration
Authors: Olney Richard K. , Miller Robert G.
Published: January 2005

Very few cases of peripheral neuropathy as a complication of disulfiram therapy have been described. The clinical and electrodiagnostic features of two patients who developed a severe peripheral neuropathy during disulfiram administration are reported. Evidence is presented which suggests that disulfiram causes a dying‐back axonal neuropathy.
Chloride efflux measurements in mammalian skeletal muscle
Authors: Hayward B. S. , Barchi R. L.
Published: January 2005

A rapid sampling technique has been used to resolve the components of 36Cl efflux from isolated extensor digitorum longus (EDL) muscles of young rats. Four distinct fluxes with apparent rate constants of 4.40 ± 0.02 min−1 (k1), 1.30 ± 0.04 min−1 (k2), 0.24 ± 0.04 min−1, (k3), and 0.048 ± 0.05 min−1 (k4) at 30°C were identified. Together, these fluxes accounted for the movement of more than 98% of exchangeable muscle chloride (Cl) ions. The muscle compartment associated with the fastest flux (k1) contained 23% ± 2% of the total muscle Cl corresponding to the extracellular space as determined with inulin or mannitol. The compartment associated with k2 accounted for 71% of the intracellular volume, and k2 was assumed to represent 36Cl efflux across the surface membrane. The rate constant k2 was temperature‐dependent with a Q10 of 1.11 between 5°C and 30°C. Acromatic carboxylic acids known to block sarcolemmal Cl conductance (Gcl) specifically lowered k2 by 25% at 30°C, as did replacement of external Cl with nitrate.
Genetics of congenital nemaline myopathy
Authors: Kondo Kiyotaro , Yuasa Tatsuhiko
Published: January 2005

Family patterns for 50 reported probands with congenital nemaline myopathy were compared with expected patterns derived from various possible genetic hypotheses. The disease had a high mortality in childhood but remained clinically stationary after this period. Some normal relatives showed nemaline rods on muscle biopsy. Chromosomes were normal in the two cases in which they were examined. Prenatal exposures appeared irrelevant to this disease. Autosomal recessive and X‐linked recessive or dominant modes of inheritance were not compatible with the observed patterns, which could be explained by an autosomal dominant mode with a reduced penetrance. Normal relatives who carried rods were presumably unaffected heterozygotes of the same gene. The genetic ratio (the proportion of affected siblings) was 0.3, being short of the expected value, 0.5, probably because of the presence of these asymptomatic rod‐bearing heterozygotes. While the pressure of natural selection was great in the patients who died or were severely disabled, the gene could be passed to the next generation by mildly affected patients or heterozygotes who remained unaffected.
On the ultrastructure of primary cultures of normal and dystrophic hamster tongue muscle
Authors: Thakar J. H. , Thede A. , Strickland K. P.
Published: January 2005

Primary cultures, prepared from the tongue muscle of 1‐day‐old normal and dystrophic (UM‐X7.1 strain) hamsters, were examined under the electron microscope after 6 to 8 days in vitro when myotube development was in progress. Myotubes from normal tongue showed development similar to that of muscle of other tissues and species grown in culture. Compared to myotubes of normal cultures, those of dystrophic cultures showed a number of differences. The sarcoplasmic reticulum and mitochondria showed areas of dilation or swelling and poor development. The density of ribosomes and polyribosomes was less, Z‐band formation was primitive or absent, myofibrillar formation was less, and its organization was poor. Also, spontaneous contractions in dystrophic myotubes were few and irregular. These differences agree well with those reported for heart cells from the dystrophic (cardiomyopathic) hamster grown in culture.
Disorders of lipid metabolism in muscle
Authors: Di Mauro Salvatore , Trevisan Carlo , Hays Arthur
Published: January 2005

At rest and during sustained exercise, lipids are the main source of energy for muscle. Free fatty acids become available to muscle from plasma free fatty acids and triglycerides, and from intracellular triglyceride lipid droplets. Transport of long‐chain fatty acyl groups into the mitochondria requires esterification and de‐esterification with carnitine by the “twin” enzymes carnitine palmityltransferase (CPT) I and II, bound to the outer and inner faces of the inner mitochondrial membrane. Carnitine deficiency occurs in two clinical syndromes. (1) In the myopathic form, there is weakness; muscle biopsy shows excessive accumulation of lipid droplets; and the carnitine concentration is markedly decreased in muscle but normal in plasma. (2) In the systemic form, there are weakness and recurrent episodes of hepatic encephalopathy; muscle biopsy shows lipid storage; and the carnitine concentration is decreased in muscle, liver, and plasma. The etiology of carnitine deficiency is not known in either the myopathic or the systemic form, but administration of carnitine or corticosteroids has been beneficial in some patients. “Secondary” carnitine deficiency may occur in patients with malnutrition, liver disease, chronic hemodialysis, and, possibly, mitochondrial disorders. CPT deficiency causes recurrent myoglobinuria, usually precipitated by prolonged exercise or fasting. Muscle biopsy may be normal or show varying degrees of lipid storage. Genetic transmission is probably autosomal recessive, but the great male predominance (20/21) remains unexplained. In many cases, lipid storage myopathy is not accompanied by carnitine or CPT deficiency, and the biochemical error remains to be identified.
Normal and dystrophic embryonic chicken pectoralis muscle cultures: I. Cell differentiation, protein synthesis, and enzyme levels
Authors: Young Ronald B. , McConnell David G. , Suelter Clarence H. , Phillips Teresa A.
Published: January 2005

Normal (line 200) and dystrophic (line 307) embryonic chicken pectoralis muscle cells were studied in cell culture over a period of 2 weeks. During the first 4 days, normal and dystrophic cultures exhibited similar developmental increases in the number of nuclei within multinucleated myotubes; however, dystrophic muscle cells degenerated approximately twice as fast as normal cells once the initial burst of myoblast fusion was complete. The apparent synthesis rate of nonmyofibrillar proteins was similar in normal and dystrophic cells throughout development, but the apparent synthesis rates of myosin heavy chain and the myofibrillar protein fraction were 50%–90% higher in dystrophic muscle cultures once maturity had been reached (days 6–14). The specific activities of creatine kinase and phosphofructokinase were not affected by the dystrophic condition; however, specific activity of AMP‐deaminase was depressed 25%–40% in the dystrophic muscle cultures.
Normal and dystrophic embryonic chicken pectoralis muscle cultures: II. Ultrastructural comparison
Authors: McConnell David G. , Young Ronald B. , Suelter Clarence H.
Published: January 2005

Ultrastructural comparison was made between dystrophic and normal chicken breast muscle cells which had been isolated from 12‐day‐old embryos and cultured for up to 14 days. All electron microscopic examinations were conducted in the absence of any knowledge as to the dystrophic or normal origin of the cells, or the day on which the cells had been harvested from culture. The same blind procedures were applied to attempts to reconstruct from electron micrographs the correct sequence of days for a particular experiment and to identify the origin of the cells as normal or dystrophic. No consistent differences between normal and dystrophic cells were apparent either in extent of differentiation, such as the formation of mature sarcomeres, or in degenerative properties, such as disintegrating mitochondria, lipid aggregations, or extracellular debris. In light of metabolic and developmental differences in these cultures, the absence of ultrastructural differences was attributed in part to the presence of cells with widely different degrees of integrity, differentiation, and degeneration in both normal and dystrophic cultures.
Normal and dystrophic embryonic chicken pectoralis muscle cultures: III. Viral infection of normal cell cultures
Authors: McConnell David G. , Gardner M. Elizabeth , Tuomari Anne V. , Young Ronald B. , Suelter Clarence H.
Published: January 2005

Twelve‐day normal and dystrophic chick embryo breast muscle cells were cultured for up to 14 days, using normal embryo extract in the culture medium. Fluorodeoxyuridine was added on day 3 to suppress fibroblast overgrowth. Three of 6 experiments with normal cells were severely infected with avian leucosis/sarcoma (ALS) virus particles. The findings appear to lend support to the suggestion that the ALS virus is a mitochondriophage. Infected cultures demonstrated a depressed rate of total protein synthesis as reflected by incorporation of [3H]leucine. Extractable protein and total protein content were also depressed within several days after ALS particles were identified. These findings reinforce caution in acceptance of the common assumption that viral infections are an unavoidable and metabolically benign component of muscle cell cultures.
Growth of neonatal hamster skeletal muscle in culture
Authors: Tautu Constantin , Jasmin Gaëtan , Solymoss Béla C.
Published: January 2005

Quantitative procedures for cell dissociation, selective plating, and growth conditions were adapted to neonatal hamster muscle in order to obtain cultures with a predictable evolution and sufficient differentiated myofibers. Normal and myopathic cultures were compared with regard to cell yield, myogenic cell fusion, and muscle differentiation. This technique is proposed for comparative studies of in vitro myogenesis in normal and myopathic hamsters.
Creatine kinase isozyme transition in chicks with hereditary muscular dystrophy
Authors: Stewart Patricia A. , Percy Maire E. , Chang Lebe S. , Thompson Margaret W.
Published: January 2005

In both normal chicks and chicks with hereditary muscular dystrophy the BB (brain) and MB (hybrid) isozymes were the predominant forms of creatine kinase (CK) activity in embryonic skeletal muscle. As myogenesis progressed, activity due to the MM (muscle) isozyme progressively increased, and by 1 week ex ovo, the MM isozyme accounted for approximately 97% of total muscle activity in both genotypes. During this time, the proportion of the MM isozyme was slightly but significantly lower in dystrophic muscles. After hatching the proportion of the MB isozyme and its total activity decreased in normal muscle, but increased in dystrophic pectoral muscle, and by 5 months ex ovo, the MB isozyme accounted for 10% of total CK activity. Prior to hatching there was no consistent difference in total CK activity between normal and dystrophic tissues, but by 1 week after hatching and thereafter, total CK activity was significantly lower in dystrophic pectoral muscle.
Disorders of neuromuscular transmission other than myasthenia gravis
Authors: Swift Thomas R.
Published: January 2005

Disorders of neuromuscular transmission in humans are caused by a wide variety of agents including systemic diseases, drugs, environmental toxins, animal envenomation, cations, and hormones. Some are genetically determined. Many are of unknown etiology. All such disorders interfere with one or more events in the sequence whereby a nerve impulse excites a muscle action potential. In many disorders of neuromuscular transmission, abnormal fatigue occurs, and some cases respond dramatically to treatment. Investigation of the microphysiology, microanatomy, and pharmacology of both normal and diseased neuromuscular junctions has increased our knowledge of these disorders.
Activity, molecular forms, and cytochemistry of cholinesterases in developing rat diaphragm
Authors: Brzin Miro , Sketelj Janez , Tennyson Virginia M. , Kiauta Tomaz , Budininkas‐Schoenebeck Mary
Published: January 2005

Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were studied in the diaphragm of early postnatal rats, using radiometric determination of enzyme activities, velocity sedimentation for separation of molecular forms, and electron microscopic cytochemistry to localize enzymes. AChE activity did not change significantly during the first 2 months after birth. The level of 16 S AChE was high at early stages, but decreased to adult levels between days 19 and 32 after birth. In newborn and 8‐day‐old rats, 16 S and 13 S AChE were present in both endplate and extrajunctional muscle. In newborn muscle, BuChE activity was higher than AChE activity, but decreased 6‐fold by day 32. Newborn muscle contained 16 S, 10 S, and 4 S BuChE. The principal form throughout development was 4 S BuChE, but all forms diminished as total BuChE activity decreased with maturation. At early postnatal neuromuscular junctions, end product of both AChE and BuChE was present in the cleft, as well as in Schwann cells. More Schwann cells were present in early stages than in later stages, and this might account for part of the later decrease of BuChE activity measured biochemically.
Biochemical functioning of mitochondria in normal and denervated mammalian skeletal muscle
Authors: Joffe Maureen , Savage Nerina , Isaacs Hyam
Published: January 2005

Mitochondrial preparations derived from denervated rat skeletal muscle and paired control muscle are characterized with respect to their oxidative and phosphorylative capacities. Our data indicate that there is an impairment within the first 2 energy coupling regions of the respiratory chain and within the ATPase complex itself.
Lupus myositis
Authors: Foote Robert A. , Kimbrough Stephen M. , Stevens J. Clarke
Published: January 2005

Eleven patients met rigid criteria for having both polymyositis and systemic lupus erythematosus (SLE). The patients differed little in clinical features when compared with patients who had SLE and polymyositis in a previously reported series. The overall mortality rate of 18% and the finding that 56% of survivors were asymptomatic at latest follow‐up (average four years) suggest that the prognosis for this subgroup of patients may be more favorable than that for patients with rheumatoid arthritis and scleroderma complicated by polymyositis and may be comparable to the prognosis of the overall group of patients with polymyositis.
Muscle histochemistry in congenital muscular dystrophy with central nervous system involvement
Authors: Nonaka Ikuya , Sugita Hideo , Takada Kuniyasu , Kumagai Komei
Published: January 2005

Muscles from 13 patients with clinical characteristics of congenital muscular dystrophy and central nervous system involvement (Fukuyama type) (FCMD) were examined using morphometric and fiber type analysis. The muscles from patients aged 5 months to 3 years demonstrated small‐calibered fibers with increased variation in fiber size, connective tissue proliferation, and scattered necrotic and regenerating fibers. Groups of atrophic fibers were absent. Both type 1 and type 2 fibers were affected, though type 1 fibers predominated and type 2B fibers decreased as the disease progressed. The muscle changes were apparently progressive, affecting not only the limbs but also the intercostal, diaphragm, and cardiac muscles. Although there was no qualitative difference in the muscle histochemistry between FCMD and Duchenne muscular dystrophy (DMD), there was a greater proportion of type 2C fibers and fibrosis was present at the early infantile stage of FCMD.
Myotonic muscular dystrophy: Morphology, histochemistry, and growth characteristics of cultured skin fibroblasts
Authors: Hartwig Geoffrey B. , Miller Sara E. , Frost Arlo P. , Roses Allen D.
Published: January 2005

The genetic defect in myotonic muscular dystrophy (MyD) is expressed in several tissues. Evidence of the expression of this defect in MyD fibroblasts was sought by comparing them with normal fibroblasts. Reports describing increased alcianophilia and metachromasia in MyD fibroblasts could not be confirmed. Furthermore, no differences were observed with phase contrast microscopy or scanning and transmission electron microscopy, in histochemical studies, in growth characteristics, or in 35S‐sulfate incorporation studies.
Electrical stimulation of denervated muscle prevents decreases in oxidative enzymes
Authors: Nemeth Patti M.
Published: January 2005

The influence of muscular contraction on the oxidative enzymes and the diameters of muscle fibers was investigated. Soleus muscles of guinea pigs were denervated for four weeks. The denervated fibers showed a reduction in the intensity of staining for β‐hydroxybutyrate dehydrogenase, cytochrome oxidase, succinate dehydrogenase, and NADH‐dependent tetrazolium reductase. Denervation also resulted in a decrease in fiber diameter. Denervated soleus muscles were electrically stimulated to contract over a four‐week period at a frequency normally received by slow contracting muscles. Electrical stimulation caused the stain intensity of histochemical reactions for oxidative enzymes to appear to be normal or greater than normal in 90% of the denervated fibers. Stimulation also caused 69% of the denervated fibers to be of normal or greater than normal size. The results demonstrate that contraction of denervated muscle by electrical stimulation prevents the loss of oxidative enzymes and the atrophy associated with denervation.
Changes in membrane structure following tenotomy of the rat soleus muscle
Authors: Baker James H. , Baldwin Kate M.
Published: January 2005

Many of the histological characteristics of neuromuscular disorders, including central core lesions and nemaline rods, can be produced experimentally by tenotomy of the soleus muscle in the rat. Using the freeze fracture technique, a decrease in the number of intramembrane particles of both the P and E faces of the plasma membranes of tenotomized soleus muscle fibers was observed. While many of the degenerative changes which occur after tenotomy are known, the causes of the degeneration are still unknown. The decrease in intramembrane particles may reflect some significant change in the function of the plasma membrane resulting in the appearance of the degenerative changes which follow tenotomy.
X‐ray diffraction from striated muscles and nerves in normal and dystrophic mice
Authors: Kurg Teorin , Stinson Robert H. , Millman Barry M.
Published: January 2005

The structure of striated muscle (thick and thin filaments, filament lattice, and collagen), peripheral nerve myelin, and tendon collagen were studied in tissues from dystrophic and normal mice using small‐angle x‐ray diffraction. There were increases in the amount of disorganized tissue in the dystrophic mice, and the time course of the changes was monitored over the first 42 weeks of life. As the dystrophic mice became older, the contractile apparatus of the muscles appeared to atrophy, while the amount of collagen increased. In general, the molecular structure and packing appeared to remain unchanged as the disease progressed, although changes in the relative amounts and the organization of proteins were noted. In both normal and dystrophic mice, the collagen periodicity (65.7 nm) was 2% smaller when detected in muscle tissue compared with that detected in tendon tissue.
Isolated proximal median neuropathy
Authors: Roth G. , Ludy J.‐P. , Egloff‐Baer S.
Published: January 2005

Four cases are described in which the patients developed an isolated lesion of the median nerve in the proximal part of the arm during sleep. In the three patients that were available for follow‐up the course was favorable with complete recovery in several months. The causes of the lesions are unknown; several factors that could have played roles in causing the lesions are discussed.
Endogenous cathepsin B Inhibitor activity in normal and myopathic red and white skeletal muscle
Authors: Spanier Arthur M. , Bird John W. C.
Published: January 2005

Despite extensive biochemical and morphological studies on the degenerative muscle diseases, the primary chemical lesions are still obscure, both in humans and animals. In this report we examine the activities of the lysosomal endoproteinase cathepsin B and its endogenous inhibitor(s) in the red and white skeletal muscles of guinea pigs with a nutritional muscular myopathy induced by vitamin E deficiency. We observed a twofold increase (P < 0.005) in the activity of cathepsin B in the white skeletal muscles of the vitamin E‐deficient (E−) animals over that of the normal (N) and control (E+) groups. Assessment of the activity of endogenous cathepsin B inhibitor revealed a one and a half times greater amount of inhibitor in N when compared to E−; this difference in inhibitor activity applied to both red (masseter) and white (medial head, gastrocnemius) muscle. When the specific activity of cathepsin B in the E−tissue was corrected for inhibitor activity, the corrected value was not significantly different from either the E+ or the N tissue.
Drug evaluation in muscular dystrophy of the chicken
Authors: Entrikin Richard K. , Patterson Gary T. , Wilson Barry W.
Published: January 2005

A high‐capacity, step‐wise system for drug evaluation in chickens with inherited muscular dystrophy has been developed. This report details the protocol and presents the first results from a rapid evaluation of the ameliorative effects of drugs on the impaired righting ability of dystrophic chicks. Of 31 compounds evaluated, only methysergide and corticosterone significantly increased righting ability.
Single fiber electromyography in chronic renal failure
Authors: Konishi Tetsuro , Nishitani Hiroshi , Motomura Shunji
Published: January 2005

Nineteen patients with chronic renal failure receiving intermittent hemodialysis had single fiber electromyography studies of their extensor digitorum communis muscles. Jitter values were abnormal, more so in men than in women. The jitter abnormalities tended to improve after intermittent hemodialysis treatments lasting longer than 1 year.
Paucity and disorganization of presynaptic membrane active zones in the lambert‐eaton myasthenic syndrome
Authors: Fukunaga Hidetoshi , Engel Andrew G. , Osame Mitsuhiro , Lambert Edward H.
Published: January 2005

Presynaptic membrane active zones are related to synaptic vesicle exocytosis, and the large intramembrane particles in these zones may represent voltage‐sensitive calcium channels. We tested the hypothesis that an abnormality of the zones is associated with the low probability of quantal release in the Lambert‐Eaton myasthenic syndrome (LEMS). Freeze‐fractured presynaptic membranes were studied in nine patients with LEMS (227 end‐plates) and in 14 controls (148 end‐plates). Satisfactory replicas of 94 LEMS and 83 control presynaptic membrane P‐faces were obtained. Presynaptic membrane areas were estimated by stereometric analysis. The LEMS samples showed a marked decrease in active zones and active zone particles per unit area. The average number of particles per active zone was also reduced. Clusters of large particles were observed with increased frequency in the LEMS samples. These may have arisen by aggregation of active zone particles. There was no decrease in the overall density of intramembrane particles not associated with active zones or clusters. The distribution of these particles according to size resembled the control distribution except for a small decrease in the frequency of 5.3–5.8 nm particles. The findings can explain the reduced quantal release in LEMS, and strongly suggest that active zone particles are targets of the pathogenic autoantibodies recently demonstrated in this disease.