bluuebunny/crossref_metadata_2025 huggingface dataset:
Sodium channel kinetics in normal and denervated rabbit muscle membrane
Authors: Kirsch G. E. , Anderson M. F.
Published: January 2005

The effects of chornic denervation on sodium (Na) channels in rabbit muscle membrane were determined using intracellular microelectrodes and Vaseline gap voltage clamp techniques. The Hodgkin‐Huxley13 model was used to describe the kinetic and steady‐state parameters of channel activation and fast inactivation. Chronic (7–10 days) denervation was found to cause a decreased resting potential, lowered action potential peak, and fibrillation potentials in rabbit extensor digitorum longus (EDL) muscles. Under voltage clamp conditions, no differences were observed between denervated and normal fibers in the voltage dependence of the steady‐state Na channel activation and fast inactivation curves, or in the time course of development of fast inactivation. However, in denervated fibers, the time course of recovery from fast inactivation was approximately half that measured in normal fibers. Also, whereas depolarizing holding potentials induced a longterm inactivation to varying degrees in normal EDL fibers, denervated EDL fibers and normal soleus fibers were uniformly resistant to prolonged depolarization. These results suggest that the denervation‐induced development of spontaneous activity may be due in part to changes in the mechnisms that control the refractoriness of Na channels.
An examination of some factors influencing creatine kinase in the blood of patients with muscular dystrophy
Authors: Jackson M. J. , Round J. M. , Newham D. J. , Edwards R. H. T.
Published: January 2005

The natural variability of plasma creatine kinase activity has been examined in patients suffering from muscular dystrophy and in normal subjects. The coefficient of variation of the plasma creatine kinase activities was found to be large (approximately 35%) in both patients with Duchenne muscular dystrophy and normal control subjects. A comparison of the plasma activities of creatine kinase with other muscle‐derived enzymes suggests that the cause of this variability is changes in the release of enzymes from muscle. Data obtained concerning the effect of physical activity on plasma creatine kinase activity are contradictory, but several young patients with Duchenne muscular dystrophy and a very high creatine kinase activity (greater than 5000 IU/liter) showed a decreased activity following admission to hospital. An estimate of the rate of efflux of certain kinase from muscle has been made, indicating that young ambulant patients with Duchenne muscular dystrophy have a grossly elevated muscle creatine kinase efflux (495.0 ± 61.3 IU/kg muscle/hr) compared to control subjects (1.4 ± 0.5 IU/kg muscle/hr).
Calcium‐activated protease in hamster cardiomyopathy
Authors: Spalla Milena , Kuo Tuan H. , Wiener Joseph
Published: January 2005

A high calcium‐requiring protease was purified from the hearts of myopathic hamsters. The biochemical properties of the enzyme were studied with [3H]acetylcasein as substrate. Comparison of the enzyme from hamster and rat hearts indicated no species specificity. Increased levels of the enzyme were associated with the development of cardiac lesions in myopathic hamsters.
Calmodulin levels in developing muscle tissues and primary cultures of normal and dystrophic (UM‐X7.1) Hamsters
Authors: Klamut Henry J. , Kotarba Jan A. , Strickland Kenneth P.
Published: January 2005

Calmodulin levels have been assessed in whole muscle and primary culture extracts in order to examine the relationship between calmodulin and the accumulation of calcium in dystrophic hamster muscle tissues. Significant decreases in both normal and dystrophic skeletal muscle, tongue, and heart calmodulin levels were observed between 2 and 12 weeks of age. Dystrophic values, however, tended to be somewhat higher than normal, especially in 12‐week‐old skeletal muscle total and soluble extracts (normal 29.7 and 0.6 and dystrophic 117.0 and 3.1 μg/g wet weight, respectively). No significant differences were observed in dystrophic myoblast (total 2.22‐2.78, soluble 2.85‐3.26 μg/mg protein) or fibroblast (total 2.64‐2.94, soluble 2.54‐3.60 μg/mg protein) calmodulin levels, except for a significant decrease in dystrophic fibroblast levels (total 1.97, soluble 2.18 μg/mg protein) at 7 days in culture. Elevated calmodulin levels in dystrophic muscle are discussed in terms of increases in intracellular Ca2+ concentrations and immature regenerating fibers.
AAEE minimonograph #26: The electrodiagnosis of carpal tunnel syndrome
Authors: Stevens J. Clarke
Published: January 2005

The electrodiagnosis of carpal tunnel syndrome is reviewed, including discussions of old and new techniques of motor and sensory nerve conduction, anomalous innervation, needle electrode examination, and one method of examining a patient with suspected carpal tunnel syndrome. The results of electromyographic testing of 505 patients with carpal tunnel synddrome in Rochester, Minnesota, from 1961 to 1980 are compared with result from previous studies. In the appendixes, a method of performing median motor and sensory nerve conduction studies and Mayo Clinic normal values are provided.
Paramyotonia congenita: Successful treatment with tocainide. Clinical and electrophysiologic findings in seven patients
Authors: Streib Erich W.
Published: January 2005

Seven patients with paramyotonia congenita (PC) from two families were studied. Voluntary exercise of the hand muscles was performed at different hand temperatures, both before and after treatment with tocainide. All patients developed stiffness, prolonged weakness, and small compound muscle action potentials (CMAPs) following exercise; the temperature at which this occurred was individually different. Two patients with PC and associated episodes of generalized weakness underwent potassium loading. A prolonged exercise test was performed both immediately before and 90 minutes after K‐loading. Exercise‐induced weakness and CMAP‐decline occurred only with high serum K levels. Thiazide treatment in these two patients was ineffective. All seven patients responded well to tocainide. Treatment response and side effects were dose‐dependent. Good clinical improvement has been maintained in all patients for more than 6 months, with relatively small doses of tocainide (400–1200 mg/day).
Electrocardiographic, biochemical, and morphologic abnormalities in dystrophic hamsters with cardiomyopathy
Authors: Bhattacharya Syamal K. , Crawford Alice J. , Pate James W.
Published: January 2005

Electrocardiographic (EKG) changes were investigated in 7‐month‐old dystrophic hamsters (DH) with cardiomyopathy and were correlated with biochemical and histologic aberrations. Abnormally tall R‐I and R‐aVL amplitudes, deep S‐III and S‐aVR waves, and elongated PR‐I, QT‐I, and QRS‐I intervals (all at P <0.0001) were noted in DH compared with normal hamsters. These EKG changes are similar to those seen in Duchenne muscular dystrophy (DMD) and support cardiac hypertrophy (P < 0.001) in DH. Excessive intracellular calcium accumulation in the heart (P < 0.0001), diaphragm (P < 0.001), and rectus femoris (P < 0.05), and elevated plasma creatine kinase concentrations (P < 0.001) were also noted in DH. Histopathology in the cardiac and skeletal muscles of DH included fatty infiltration, centronucleation, and sporadic necrosis with calcium deposition. Observed EKG abnormalities, biochemical alterations, and histological aberrations in the cardiac and skeletal muscles of DH are strikingly similar to those reported in DMD and thus substantiate the relevance of DH as a suitable model for the study of muscular dystrophy and cardiac hypertrophy.
The time course of creatine kinase elevation following concentric needle EMG
Authors: Levin Randy , Pascuzzi Robert M. , Bruns David E. , Boyd James C. , Toly Travis M. , Phillips Lawrence H.
Published: January 2005

The electromyographic (EMG) exam and creatine kinase (CK) are commonly used to evaluate patients with neuromuscular diseases. Prior studies have demonstrated minimal elevation of CK following monopolar needle examination, indicating that a false positive elevation does not occur in normal individuals. We studied the magnitude and time course of CK change resulting from concentric (CNEMG) and monopolar (MNEMG) needle EMG examination on healthy volunteers.

CK increased in all subjects following CNEMG and MNEMG. Statistically significant mean CK elevations over baseline were observed at 4, 8, 12, and 24 hours for CNEMG and at 12 and 24 hours for both MNEMG. Maximum elevation occurred at 12 and 24 hours for both CNEMG (mean, 178% of baseline) and MNEMG (mean, 134% of baseline). CK returned to baseline by 48 to 72 hours. In 25–30% of subjects CK elevation significantly exceeded the normal range.

The magnitude of CK elevation is greater and the time course more prolonged than previously reported. CK measurements should be avoided 4 to 48 hours following CNEMG because of the potential for false positive results. Measurements immediately after and at 72 hours are not affected by the CNEMG or MNEMG. The time course for CK change following MNEMG is similar to CNEMG, but the magnitude is less.
Myopathy complicating the acquired immune deficiency syndrome
Authors: Stern Richard , Dicarlo Edward F.
Published: January 2005

A case of Acquired Immunodeficiency Syndrome complicated by a severe myopathy is reported. All efforts aimed at documenting an infectious etiology for the myopathy were negative. The relationship of myopathy to AIDS is discussed.
High serum levels of creatine kinase: Asymptomatic prelude to distal myopathy
Authors: Galassi Giuliana , Rowland Lewis P. , Hays Arthur P. , Dimauro Salvatore , Hopkins Linton C.
Published: January 2005

Two brothers and an unrelated man had serum creatine kinase values of 3000–8000 units when they were asymptomatic, and there was no weakness on examination. EMG and muscle biopsy showed changes indicative of myopathy. Years later, all three developed weakness that was limited to the gastrocnemius. Because siblings were affected, the disorder can be regarded as a form of muscular dystrophy. The distribution of weakness, serum enzyme changes, and histologic changes resembled an autosomal recessive distal myopathy first described by Miyoshi and differed from many other reported cases of distal myopathy. Our cases also indicate that myopathy may be asymptomatic.
Serum creatine kinase isoenzymes in duchenne muscular dystrophy determined by sensitive enzyme immunoassay methods
Authors: Mokuno Kenji , Riku Shigeo , Sugimura Kimiya , Takahashi Akira , Kato Kanefusa , Osugi Shigeki
Published: January 2005

Serum levels of creatine kinase (CK) isoenzymes (MM, MB, and BB) were measured by sensitive enzyme immunoassay (EIA) methods in 50 patients with Duchenne muscular dystrophy (DMD) and in 39 controls. MM, MB, and BB levels in DMD patients were higher than in controls, and these three levels decreased with advancing age of DMD patients. Serum MB levels showed a good correlation with serum levels of carbonic anhydrase III (CA‐III), but correlated poorly with electrocardiographic findings, suggesting that the main origin of serum MB in DMD is skeletal muscle rather than cardiac muscle.
Aminoglycosides and 3, 4‐diaminopyridine on neuromuscular block caused by botulinum type a toxin
Authors: Molgó Jordi , Lemeignan Madeleine , Thesleff Stephen
Published: January 2005

Impulse‐evoked transmitter release was greatly reduced at frog neuromuscular junctions 3–20 days after botulinum type A toxin (BoTx) poisoning. The reduction in transmitter release was accompanied by an increased variability in the latency between the presynaptic spike and the release of transmitter. The aminoglycoside antibiotics amikacin, gentamycin, and bekanamycin, when applied at concentrations within their therapeutic levels, markedly enhanced the blockade of transmitter release in BoTx‐poisoned junctions. 3,4‐diaminopyridine strongly antagonized the effects of BoTx at early stages of poisoning, and the combined presynaptic effects of BoTx and aminoglycoside antibiotics provided that transmitter release was not completely blocked by the toxin. The antagonism was apparent at all frequencies of stimulation. Since the aminoglycoside antibiotics enhanced the neuromuscular block caused by BoTx, these drugs should be avoided in patients suspected of poisoning by this toxin.
Electrophysiologic evidence of severe distal nerve segment pathology in the guillain–barré syndrome
Authors: Miller Robert G. , Peterson Christina , Rosenberg Neil L.
Published: January 2005

We report the clinical and electrophysiologic findings in 4 patients with Guillain–Barré syndrome (GBS) who, within 48 hours of onset, progressed to flaccid quadriplegia. Evoked muscle action potentials were absent or prolonged in latency and markedly reduced in amplitude within 48 hours of onset of weakness at a time when sensory nerve studies were almost normal. We conclude that pathophysiologic abnormalities may be distal and severe in some patients with GBS and that there is a predilection for motor axons in GBS.
Increased skeletal muscle acetylcholinesterase activity in porcine malignant hyperthermia
Authors: Mickelson James R. , Thatte Hemant S. , Beaudry Terrrence M. , Gallant Esther M. , Louis Charles F.
Published: January 2005

The content and distribution of acetylcholinesterase (AChE) activity in the skeletal muscle disorder malignant hyperthermia (MH) was examined. The AChE activity of sarcolemma membranes isolated from MH‐susceptible (MHS) swine was increased twofold when compared with normal sarcolemma. The total AChE activity of muscle extracts was also doubled in MHS tissue; however, the relative distribution between low‐salt extractable (globular forms) and high‐salt extractable (asymmetric forms) AChE activities were similar in MHS and normal muscle. Our results suggest that, for as yet unexplained reasons, both the sarcolemmal and total AChE activity of skeletal muscle is increased in porcine MH.
Changes in contractile speed of cat motor units during activity
Authors: Dubose Laniel , Schelhorn Teresa B. , Clamann H. Peter
Published: January 2005

Experiments were conducted to measure the extent of contractile changes during phasic activity of different motor units. Motor units of cat medial gastrocnemius were isolated and classified by their mechanical properties as fast and fatigable (FF), fast and fatigue resistant (FR), or slow (S). Single stimuli interpolated between stimulus trains of the fatigue test produced twitches whose shapes were measured at different times during this test. After 30 seconds of fatigue testing, twitch contraction times of 33% of FF units fell into the slow range, i.e., 5 of 17 units had become slower than the fastest slow units. Mean twitch contraction time of FF units increased by 11.8 msec, whereas that of S units decreased by 16.2 msec. We conclude that the mechanical properties of rested motor units change markedly with use and are a poor index for determining the contractile speed of active muscles.
A computer model of denervation‐reinnervation in skeletal muscle
Authors: Cohen Michael H. , Lester James M. , Bradley Walter G. , Brenner John F. , Hirsch Robert P. , Silber Dennis I. , Ziegelmiller Daniel
Published: January 2005

A computer model of the process of denervation and complete reinnervation of skeletal muscle has been developed for the purpose of exploring underlying mechanisms and for use in the development of new clinical and research tools for evaluating neuromuscular disease. Progressive motor neuron death and reinnervation in this model reproduces the fiber‐type grouping, increased fiber density, and minimal increase of motor unit size seen in human chronic denervating diseases. Studies using the model suggest that (1) preferential involvement of motor units of one type could account for the abnormal fiber‐type proportions observed in some diseases, (2) reinnervation by axons innervating adjacent fibers is compatible with single fiber multielectrode studey results in that it does not produce a large increase in motor unit area, and (3) such reinnervation is sufficient to account for the increases in motor unit density that have been observed. The model has also been used in the development and testing of the Codispersion Index a measure of the codistribution of two fiber types, which is useful in detecting fiber‐type grouping.
Detection, characterization, and staging of polyneuropathy: Assessed in diabetics
Authors: Dyck Peter James
Published: January 2005

The reported prevalence of diabetic polyneuropathy varies from 5 to 80%. This unsatisfactory state may relate to evaluation of different patient groups, different minimal criteria for the diagnosis of neuropathy, and different degrees of surveillance. To made matters worse, patients with polyneuropathy tend to be equated ignoring differences in severity. To remedy this situation, four recommendations are made: (1) population‐based patients should be studied, (2) nerve conduction should be used to set minimal criteria for neuropathy because the test is objective, sensitive, and repeatable, (3) validated tests of symptoms and deficits should also be used because clinical manifestations of neuropathy cannot be accurately inferred from electrophysiologic measurements, and (4) approaches to staging severity of neuropathy should be developed and used in expressing abnormality. To this end minimal criteria for the diagnosis of diabetic polyneuropathy have been proposed, and validated tests to assess neuropathic symptoms and sensory deficits have been developed. In this report we also propose a staging approach utilizing nerve conduction and neurologic history and examination and validated tests of neuropathic symptoms and deficits.
Intraoperative electroneurography: Management of ulnar neuropathy at the elbow
Authors: Campbell William W. , Sahni Singh K. , Pridgeon Rhonda M. , Riaz Ghazala , Leshner Robert T.
Published: January 2005

At the elbow the ulnar nerve may be compressed either in the retrocondylar groove or at the cubital tunnel. Optimal surgical therapy should be directed at the specific site of involvement. Intraoperative electroneurography performed in conjunction with 19 ulnar nerve explorations helped localize the precise site of compression. Of the primary procedures, abnormality was at the retrocondylar groove in 9, cubital tunnel in 4, both locations in 3, and at an unusual distal point in 1; 12 anterior subcutaneous transpositions, 4 cubital tunnel releases, and 1 distal decompression resulted. Intraoperative studies helped identify residual compression in two patients undergoing reexploration. Although routine electrodiagnosis may localize an ulnar neuropathy to the elbow, reliably separating retrocondylar from cubital tunnel compression is more difficult. Preoperatively, percutaneous serial short increment studies were more accurate than simple “inching” in predicting the site of compression.
Protron spin‐lattice relaxation time of duchenne dystrophy skeletal muscle by magnetic resonance imaging
Authors: Matsumura Kiichiro , Nakano Imaharu , Fukuda Nobuo , Ikehira Hiroo , Tateno Yukio , Aoki Yoshiro
Published: January 2005

By means of proton MRI, the spin‐lattice relaxation times (T1 values) of pelvic and leg muscles were measured in Duchenne muscular dystrophy (DMD) patients and normal controls. The bound water fraction (BWF) was calculated from the T1 value obtained. In normal children, the T1 value decreased, and BWF increased with age. In DMD, the T1 value rapidly decreased, from an abnormally high value in the early stages, with the progress of the disease. This reduction of the T1 value in DMD was not the same for all muscles; it was most prominent in the gluteus maximus and least prominent in the sartorius and gracilis muscles. BWF was below normal in the early stages of DMD. It is suggested that both regenerating and degenerating muscle fibers, together with the increased muscle water content, cause the high T1 value and low BWF in the early stages of DMD, whereas replacement of muscle by fat causes the decreased T1 value in the advanced stages.
Progressive myotonia in foals resembling human dystrophia myotonica
Authors: Reed Stephen M. , Hegreberg Gerald A. , Bayly Warwick M. , Brown Christopher M. , Paradis Mary R. , Clemmons Roger M.
Published: January 2005

A severe and progressive neuromuscular disorder accompanied by clinical, electrophysiological, and pathological features resembling human dystrophia myotonica was observed in three foals. This disorder was apparent as early as 1 month of age and involved progressive skeletal muscle dysfunction, initially characterized by proximal muscle hypertrophy and hypertonicity with subsequent muscle stiffness, weakness, and atrophy. Multisystem involvement was manifested in one case by testicular hypoplasia, early cataract formation, and borderline glucose intolerance. Prolonged dimpling of these large rear‐limb muscles was elicited by percussion. Myotonic discharges were identified by electromyography. Percussion dimpling and the typical myotonic discharges persisted after neuromuscular blockade. Distinctive histologic muscle changes included ring fibers, sarcoplasmic mass formation, variation in fiber diameter size, and internally positioned nuclei.
Polysaccharide storage myopathy
Authors: Thompson A. J. , Swash M. , Cox E. L. , Ingram D. A. , Gray A. , Schwartz M. S.
Published: January 2005

In a woman with a slowly progressive adult onset proximal myopathy, muscle biopsy showed storage of PAS positive material in type 1 fibers. This material consisted of a branched chain polysaccharide associated with a mucoprtein. No abnormality of glygogen‐pathway enzymes was detected. This suggested that this polysccharide accumulation occurred because the polysaccharide was laid down in a non 7hyphen;bioavailable form. The clinical and histochemical features in this patient and in the few similar reported cases indicate that polysaccharide storage myopathy is a distinct entity that is allied to the glycogen storage myopathies.
Effects of denervation on spectrin concentration in avian skeletal muscle
Authors: Gregorio Carol C. , Hudecki Michael S. , Pollina Catherine M. , Repasky Elizabeth A.
Published: January 2005

The effect of denervation on avian muscle α‐spectrin was examined in fast and slow muscles. Using immunofluorescence, the surgically denervated fast‐twitch posterior latissimus dorsi (PLD) exhibited a significant increase in spectrin antigen associated with the sarcolemma and within the sarcoplasm compared with the contralateral innervated control muscle. Using gel electrophoresis followed by immunoblotting, we found a two‐ to three‐fold increase in the levels of spectrin in the denervated PLD over that found in the innervated PLD. These levels were comparable to those found previously in slow and dystrophic muscle. The intrafiber distribution of spectrin is similar between the denervated PLD and the slow‐tonic anterior latissimus dorsi (ALD). When spectrin was examined in dystrophic PLD muscle, denervation was found to have no effect. These results support our hypothesis that the concentration of spectrin within muscle fibers reflects the physiological state of those fibers. Changes in spectrin concentration may be a useful probe to study the various alterations in physical parameters found among fast, slow, dystrophic, and denervated fibers.
Jamaican neuropathy: An electrophysiological study
Authors: Barkhaus Paul E. , Morgan Owen
Published: January 2005

Jamaican neuropathy (JN) is a common disorder in Jamaica and has characteristics similar to neurological diseases found in other tropical areas. JN is a clinical syndrome and occurs in two forms: spastic and ataxic. This is the first known electrophysiological study of this disease. In the spastic group of JN, peripheral electrophysiological findings were mostly normal, suggesting a central cause for their symptoms. The only patinet with the ataxic form of JN had a chronic axonal peripheral neuropathy.
The myotonic mouse mutant ADR: Physiological and histochemical properties of muscle
Authors: Reininghaus Jutta , Füuchtbauer Ernst‐Martin , Bertram Kordula , Jockusch Harald
Published: January 2005

The muscle physiology and histochemistry of a hereditary neuromuscular syndrome of the mouse, “arrested development of righting response” (ADR), was studied. The speed of single twitches of fast ADR limb muscles was normal up to an age of about 60 days but decreased at later ages. At any age between 10 and 120 days postnatal, fast and slow muscles of the mutant displayed after‐contractions of 1–3 (5) seconds duration. These coincided with electrical after‐activity of muscle, as demonstrated by electromyography, After‐contractions and EMG signals were suppressed by the membrane‐stabilizing drug tocainide. These physiological data suggest that ADR is a myotonia. With a few exceptions, limb and trunk muscles of ADR animals showed a uniform oxidative phenotype with a lack of large diameter glycolytic fibers. The histochemical muscle phenotype of the ADR mouse was partially reversed by a long‐term treatment with tocainide.
Neonatal androgen maintains sexually dimorphic muscles in the absence of innervation
Authors: Fishman Renata B. , Breedlove S. Marc
Published: January 2005

We examined the site of androgen action in maintaining the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) and its target perineal muscles, the bulbocavernosus (BC) and levator ani (LA), in rats. To determine whether androgen action on SNB motoneurons is crucial for BC/LA survival, we removed SNB cells in newborn female rats by lumbosacral spinalectomy, administered testosterone propionate (TP) on days 1 and 3 of life, and examined for the presence of BC/LA muscles in adulthood. BC/LA muscles were present in all TP‐treated spinalectomized females, and staining of these muscles with alpha‐bungarotoxin or for acetylcholinesterase showed no evidence of cholinergic innervation. Thus, complete neonatal denervation of the BC/LA does not prevent TP from sparing these muscles, suggesting that androgen acts directly upon BC/LA muscles to maintain them during development. This androgenic maintenance of the BC/LA may be crucial for the survival of SNB motoneurons.
Microneurography for the recording and selective stimulation of afferents: An assessment
Authors: Calancie Blair M. , Stein R. B.
Published: January 2005

The purpose of this study was to examine whether a microneurography electrode could record from and then selectively stimulate the same afferent fiber in cat sural and tibial nerves. Fiber activity was recorded distally with microneurography needle electrodes and proximally with hook electrodes. Records from the hook electrodes allowed the waveform shape and latency following natural stimulation to be compared with that produced by electrical stimuli delivered through the needle electrode. The action potentials from approximately 50% of the recorded fibers failed to propagate beyond the needle electrode. When propagation did occur and the comparison could be made, only 25% of the afferents recorded could be selectively stimulated. This relatively low success rate suggests that a typical microneurography needle is not particularly good for selectively stimulating identified afferents. Thus in human experiments, attempts to microstimulate identified afferents may often include stimulation of unidentified alternative, or additional, afferent fibers at thresholds of sensory perception.
Altered blood rheology in the pathogenesis of diabetic and other neuropathies
Authors: Simpson Leslie O.
Published: January 2005

Although a substantial literature confirms the abnormal flow properties of diabetic blood, only in a few papers has the vasculitis of diabetic neuropathy been considered to have a hemorheological cause. It is proposed that the pathogenesis of nerve lesions involves an interaction between the specialized nerve vascular system and focal ischemic lesions resulting from rheologically induced stasis. The proposition is extended into other conditions with abnormal blood rheology such as hypothyroidism, uremia, dysglobulinemia, polyarteritis nodosa, and lepromatous leprosy. It is concluded that the treatment of such polyneuropathies should include an agent which would improve the flow properties of the blood.
EMG computerized analysis of localized fatigue in duchenne muscular dystrophy
Authors: Frascarelli Massimo , Rocchi Letizia , Feola Isidoro
Published: January 2005

EMG power spectra obtained during a sustained isometric contraction were analyzed in a group of 10 children affected by Duchenne muscular dystrophy (DMD) and compared with those obtained in a control group of 5 normal children. In myopathic subjects the isometric contraction caused an increase of the total power, a progressive increase of power of the lower frequencies, a decrease of that of the higher frequencies, and a shift downward of the median frequency. In normal children an increase of the total power without a significant median frequency shift was noted.

The modifications observed in DMD children were explained by a decrement of the firing rate of the more damaged fast twitch motor units. This decrease was probably induced by a relative predominance of activity of the slow twitch motor units, which are less damaged by the pathological process.
Linkage studies in facioscapulo‐humeral muscular dystrophy
Authors: Padberg George W. , Klasen Eduard C. , Volkers Willem S. , De Lange Gerda G. , Wintzen Axel R.
Published: January 2005

Possible linkage between the locus for autosomal dominant facioscapulohumeral muscular dystrophy and the locus for the constant region of the heavy chains of the IgG immunoglobulins (Gm) was tested in 1 kindred (23 affected and 18 unaffected sibs) using the polymorphic DNA probe D14S1, which is known to be closely linked with Gm. No linkage between the loci for the disease and the probe was found, and the lod scores suggested that the locus for facioscapulohumeral muscular dystrophy is not situated on the distal part of the long arm of chromosome 14.
HLA‐DR‐expressing cells and T‐lymphocytes in sural nerve biopsies
Authors: Schrøder Henrik D. , Olsson Tomas , Solders Gäran , Kristensson Krister , Link Hans
Published: January 2005

Thirty‐five sural nerve biopsies were stained immunohistochemically for HLA‐DR antigen. HLA‐DR was expressed on nonmyelinating Schwann cells, macrophages, vascular endothelium, and perineurium. By means of double immunofluorescence staining the identity of the HLA‐DR presenting structures was confirmed. HLA‐DR expression was found in all biopsies and thus was not restricted to any particular type of neuropathy. The HLA‐DR expression appeared to correlate with severity and activity of the neuropathy. HLA‐DR‐expressing macrophages wrapping myelinated fibers were prominent in primary demyelinating neuropathies. T‐cells were found in 6 out of 15 nerves examined. Their presence correlated with moderate to strong HLA‐DR expression of nonmyelinating Schwann cells, and they occurred during active disease.
AAEE minimonograph #30: Electrophysiologic studies of myoclonus
Authors: Shibasaki Hiroshi
Published: January 2005

Definition as well as classification of myoclonus and electrophysiologic methods for investigating myoclonus were reviewed. Among the electrophysiologic techniques currently available in most laboratories, the EEG‐EMG polygraph is the most essential one and can provide us with the most important information. Jerk‐locked averaging and evoked potential studies are useful for further investigating the pathophysiology of myoclonus and can be performed by using the same recording electrodes as those used for the polygraph. Jerk‐locked evoked potentials and double‐stimulation evoked potentials can be employed only for further investigating how cerebral cortex is involved in the generation of certain myoclonia. All these techniques can be used in proper combinations depending on the clinical features of the myoclonus in question, the purpose of the study, and the facilities available in each laboratory. These techniques also will be useful for following the clinical course during the treatment with antimyoclonus agents.
Conduction studies in peripheral cat nerve using implanted electrodes: II. The effects of prolonged constriction on regeneration of crushed nerve fibers
Authors: Krarup Christian , Loeb Gerald E. , Pezeshkpour Gholam H.
Published: January 2005

Arrays of chronically implanted electrodes were used to examine the time course of elongation and maturation of peripheral nerve fibers in the cat after crush of the tibial nerve in the proximal calf. Regeneration after crush alone was compared with crush 5 mm proximal to a tight constriction of the nerve. Regeneration was monitored by the progression of excitability along the electrode arrays on the tibial and plantar nerves. The sensitivity was sufficient to record the averaged activity in single nerve fibers allowing detection of the earliest regeneration. The diameters of the fastest regenerating fibers were estimated from the conduction velocity proximal to the site of crush. Both after crush alone, and after crush constriction, small myelinated fibers regenerated in front of large fibers. The rate of elongation after crush alone was 3.2 mm/day, whereas it was slower (P < 0.02) distal to crush + constriction (2.2 mm/day). In both lesions, the extrapolated delay to onset of regeneration was 8 days. In observations up to 300 days after crush, maturation was delayed or impaired by the constriction, and the compound nerve action potential had a smaller amplitude and a dispersed shape. Transverse sections of nerves after crush + constriction showed a diminished number of large and an increased number of small fibers compared with crush alone, possibly due to persistent branching of regenerated fibers. After both crush alone and crush + constriction, regenerated fibers had similar g ratios, suggesting that myelination developed fully in fibers of diminshed diameters.
Muscular dystrophy in a litter of golden retriever dogs
Authors: Kornegay Joe N. , Tuler Sheila M. , Miller Doris M. , Levesque Donald C.
Published: January 2005

Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described. Initial clinical signs included stilted gait and simultaneous advancement of their pelvic limbs. Further gait restriction and muscle hypertrophy eventually occurred. Serum creatine kinase was dramatically elevated (>10,000 U/L). There were persistent “spontaneous” high‐frequency discharges (pseudomyotonia) on electromyographic evaluation. Features of both muscle fiber degeneration (hyaline fibers, myophagocytosis) and regeneration (small basophilic fibers) were seen on light microscopy. Similar ultrastructural changes (fiber hypercontraction, increased myoblasts) were present. On morphometric histochemical evaluation, mean fiber diameter of both type 1 and 2 fibers was increased compared with controls in two of three muscles examined. There was no apparent fiber type predominance. Scattered ragged red fibers were seen, but this appeared to be a nonspecific finding of either muscle fiber regeneration or degeneration. These findings and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.
Relationship of age and sex to sensory conduction of the median nerve at the carpal tunnel and association of slowed conduction with symptoms
Authors: Nathan Peter A. , Meadows Kenneth D. , Doyle Linda S.
Published: January 2005

A cross‐sectional study of 471 randomly selected employees from 4 industries was performed to assess the prevalence of slowing of sensory conduction of the median nerve at the carpal tunnel as well as the effect of age and sex on slowing. The association between slowed conduction and symptoms of carpal tunnel syndrome (CTS) was also evaluated. Slowing was identified in 17% of the subjects and in 11% of the hands. The prevalence and the severity of slowing increased with increasing age of the subjects. Slowed conduction occurred more often among the women in the study, but this was shown to be an effect of age and not of sex. Slowing occurred six times more often in hands with symptoms of CTS than in those not reporting symptoms.
Use of motor units in relation to muscle fiber type and size in man
Authors: Jakobsson Finnbogi , Borg Kristian , Edström Lars , Grimby Lennart
Published: January 2005

The use of the musculus tibialis anterior during walking and the type and size of its muscle fibers were determined in 15 young normal subjects (29 ± 4 years) and in 13 old healthy subjects (70 ± 3 years). In the average step cycle 16 ± 6% of the maximal surface EMG was recorded during the swing phase and 44 ± 15% during 100 msec at the heel strike. Single motor unit recordings showed that low‐ threshold units fired at 10–15 Hz during the swing and at 20–25 Hz during the heel strike peak. Usually, high‐threshold units did not participate in the ordinary step cycle. A significantly higher mean use was found in the old subjects as compared with the young ones presumably due to lower muscle power in relation to body weight. In the young subjects 76 ± 7% of the muscle fibers were type 1 and 22 ± 7% were type 2A. In the old subjects 84 ± 9% were type 1 and 15 ± 8% were type 2A. In the young subjects the mean cross‐sectional area of type 1 fibers was 3950 ± 950 μm2 and of type 2 fibers was 8070 ± 1850 μm2. In the old subjects the corresponding numerals were 4050 ± 890 μm2 and 5700 ± 1970 μm2, respectively. The significance of physiological variations in use for muscle fiber type composition and size is discussed.
Effects of excessive use of remaining muscle fibers in prior polio and LV lesion
Authors: Borg Kristian , Borg Jörgen , Edström Lars , Grimby Lennart
Published: January 2005

Twenty‐three subjects with weakness of musculus tibialis anterior (TA) due to prior poliomyelitis (n = 19) or prior LV lesion (n = 4) were examined regarding the use of remaining TA motor units during walking and the consequences of long‐term overuse for the TA muscle fibers. Subjects with an excessive overuse exhibited almost only type 1 muscle fibers and with marked hypertrophy. Subjects who did not use remaining TA fibers because of too‐severe paralysis had a normal fiber type differentiation and fiber atrophy. The use of remaining TA motor units was correlated to the type 1 muscle fiber percentage (r = 0.69) and to the type 1 fiber size (r = 0.78). Identical changes were observed in subjects with prior poliomyelitis and in subjects with prior LV lesion and were, thus, not specific for poliomyelitis. The changes in fiber type composition may be explained by a transition of type 2 to type 1 muscle fibers in accordance with previously reported experimental transneuronal stimulation through inplanted electrodes in animals.
Denervation‐induced proliferative changes of triads in rabbit skeletal muscle
Authors: Salvotri Sergio , Damiani Ernesto , Zorzato Francesco , Volpe Pompeo , Pierobon Sandra , Quaglino Daniela , Salviati Giovanni , Margreth Alfredo
Published: January 2005

Protein compositional and functional differences exist between longitudinal and junctional sarcoplasmic reticulum (SR) in relation to Ca transport and to Ca release. In light of this knowledge, we have reinvestigated the effects of denervation on SR of rabbit gastrocnemius, a predominantly fast muscle. Electron microscopy of 2‐weeks denervated muscle showed proliferation of transverse tubules (TT), forming junctional contacts with SR terminal cisternae (TC). At coincident periods, the yield of muscle microsomes was increased, and their fractionation by sucrose‐density centrifugation demonstrated a relative increase of heavy vesicles. Thin‐section electron microscopy of heavy SR from denervated muscle showed an increased number of vesicles containing calsequestrin (CS) as compared with control muscle. Electrophoretic analysis confirmed the relative decrease of Ca‐ATPase protein and the striking increase of CS both in total microsomes and in heavy SR vesicles. Calcium loading and Ca‐ATPase activity as well as the density of Ca‐ATPase protein were decreased to a similar extent (20–30%) in denervated muscle microsomes. Stimulation of Ca‐ATPase activity by Ca‐ionophore A23187 showed that the vesicles were tightly sealed. When probed by competitive ELISA with antibody to SR Ca‐ATPase from pure fast muscle, the Ca‐ATPase of denervated microsomes was found to be highly cross reactive. Cleveland's peptide maps of the Ca‐ATPase protein after partial digestion with S. aureus V8 protease also showed no significant change after denervation. Changes in cholesterol content and in the ratio of Mg‐ATPase to Ca‐ATPase activity of denervated muscle microsomes indicated a 4‐fold increase of TT protein, i.e., from about 3% to not more than 12% of total protein, at 2 weeks after denervation. All these changes were totally reversed upon reinnervation of muscle fibers, and the consequent muscle recovery, as obtained by nerve crushing instead of nerve sectioning. From these results, we conclude that denervated adult fast muscle, similarly to immature fast muscle, contains more junctional SR. However, the molecular and catalytic properties of the Ca‐ATPase are unaffected by denervation.
Calcium currents and asymmetric charge movement in malignant hyperpyrexia
Authors: Lamb Graham D. , Hopkinson Kenneth C. , Denborough Michael A.
Published: January 2005

In both control pigs and pigs susceptible to malignant hyperpyrexia (MH), the size of the calcium current (ICa) and the amount of asymmetric charge movement varied considerably between different gracilis muscle fibers but appeared to vary in parallel. The mean amount of both ICa and charge movement were slightly but significantly smaller in MH‐susceptible (MHS) muscle compared with normal muscle. Halothane (1% v/v) reduced both parameters by almost 50%. One interpretation of the data is that the signal, which couples depolarization to calcium release from the sarcoplasmic reticulum, is abnormal in MHS muscle.
Delayed‐onset muscle damage and lipid peroxidation in man after a downhill run
Authors: Maughan Ronald J. , Donnelly Alan E. , Gleeson Michael , Whiting Paul H. , Walker Kim A. , Clough Peter J.
Published: January 2005

Lipid peroxidation initiated by free radical reactions is associated with tissue necrosis in a variety of conditions. We have measured serum lipid peroxide concentrations (as total thiobarbituric acid‐reactive substances, TBARS) and creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities and subjective muscle soreness in 16 men before and after a 45‐minute downhill treadmill run. TBARS concentrations and enzyme activities were increased after exercise, with peak values observed at 6 hours (TBARS, LDH) or 24 hours (CK, AST) after exercise. Serum LDH activity returned to preexercise levels by 48 hours after exercise and TBARS by 72 hours after exercise: CK and AST activities remained elevated 72 hours after exercise. Leg mucle soreness also increased, with the greatest degree of soreness seen at 24 or 48 hours after exercise. Subjects with the greatest increase in CK, LDH, and AST also showed the highest serum TBARS concentration. This suggests a possible relationship between free radical generation and exercise‐induced muscle damage.
The quadriceps femoris muscle in 20–70‐year‐old subjects: Relationship between knee extension torque, electrophysiological parameters, and muscle fiber characteristics
Authors: Stålberg E. , Borges O. , Ericsson M. , Essén‐Gustavsson B. , Fawcett P. R. W. , Nordesjö L. O. , Nordgren B. , Uhlin R.
Published: January 2005

Comparisons have been made between torque (isometric and isokinetic), electrophysiological (SFEMG, Macro EMG), and muscle fiber characteristics in the vastus laterlis muscle of both legs in healthy subjects aged between 20 and 70 years. Torque was greater in males and decreased with age in both sexes. Multifactorial analysis showed a positive correlation between torque, body surface area, and mean fiber area. These variables explained only about 30–40% of the torque changes. The electrophysiological parameters (Marco EMG amplitudes and fiber density) revealed evidence of reinnervation, indicating preceeding denervation and therefore loss of motor units. It was concluded that this fall out of motor units also contributes to the reduction in torque, when compensatory reinnervation begins to fall. Other factors, such as reduction in muscle fiber contractility, metabolic factors, and central factors, may also play a role in age‐related reduction in torque.
Acquired inflammatory demyelinating polyneuropathies: Clinical and electrodiagnostic features
Authors: Albers James W. , Kelly John J.
Published: January 2005

The acquired demyelinating polyneuropathies include acute (AIDP, Guillain‐Barré syndrome, GBS) and chronic (CIDP, dysproteinemic) forms which differ primarily in their temporal profile. They are inflammatory‐demyelinating diseases of the peripheral nervous system and likely have an immunologic pathogenesis. Although these neuropathies usually have a characteristic presentation, the electromyographer plays a central role in their recognition, since the demyelinating component of the neuropathy, which greatly reduces the differential diagnosis, is often first identified in the electromyography laboratory. In AIDP, the electromyographer, in addition to establishing the diagnosis, can sometimes predict the prognosis. Recognition of the chronic and dysproteinemic forms of acquired demyelinating polyneuropathy is important since they are treatable. The dysproteinemic forms also may be associated with occult systemic disorders that also may require treatment, independent of the neuropathy.
Diverse electrophysiological spectrum of the Lambert–Eaton myasthenic syndrome
Authors: Oh Shin J.
Published: January 2005

Among 13 patients with the Lambert–Eaton myathenic syndrome (LEMS), three different patterns on the repetitive nerve stimulation test were observed at the time of initial testing. Type 1 pattern, seen in one patient, had low normal CMAP amplitude, decremental response at the low rate of stimulation (LRS), and relatively normal response at the high rate of stimulation (HRS). Type 2, seen in nine patients, had the classical triad: low CMAP amplitude, decremental response at LRS, and incremental response at HRS. Type 3, seen in three patients, showed low CMAP amplitude, decremental response at LRS, and initial decremental response at HRS. We believe that these three patterns represent different degrees of blocking in LEMS, from the mildest in type 1 to the most severe in type 3. Since types 1 and 3 can be misinterpreted as myasthenia gravis patterns, they must be recognized in LEMS and an incremental response documented by prolonged stimulation at HRS.
Electrodiagnostic evolution of carcinomatous sensory neuronopathy
Authors: Donofrio Peter D. , Alessi Anthony G. , Albers James W. , Knapp Robert H. , Blaivas Mila
Published: January 2005

Sensory neuronopathy is a well‐recognized remote effect of carcinoma. We report the clinical and electrodiagnostic evolution of a sensory neuronopathy in a patient with carcinoma of the lung. Serial electrophysiologic studies suggest transformation from normal peripheral nerve function through early posterior root involvement to absent sensory nerve function. Diffuse motor conduction abnormalities occurred late in the disease, perhaps reflecting motor axon changes associated with disuse.