摘要:

AbstractThe myofiber type composition of pectineal muscles was determined in 21 mixed‐breed pups at 1 through 79 days of age and in 22 8‐week‐old‐pups (4 mixed‐breed, 5 greyhound and 5 German shepherd pups with normal muscles, and 8 German shepherd pups with myofiber hypotrophy). Sections were stained for the histochemical demonstration of myofibrillar adenosine triphosphatase by incubation in media at pH 9.8 without preincubation and following preincubation in acid media at pH 4.5 and at pH 4.3. At day 1 most myofibers were type 2C (alkaline and acid stable) while the remainder were type 1A myofibers (alkaline labile; acid stable) which had differentiated prenatally. Subsequently, the number of type 2C myofibers decreased while the number of type 1A and type 2A myofibers (alkaline stable; acid labile at pH 4.5 and pH 4.3) increased. Type 1B myofibers (partially alkaline stable; acid stable) were first observed at day 12 and were variably present through day 79. Type 1B myofibers appeared to be a transition form of type 2C to type 1A differentiation. Type 2B myofibers (alkaline stable; acid stable at pH 4.5; acid labile at pH 4.3) were not observed. Hypotrophied muscles contained more type 2C and fewer type 2A myofibers and all myofiber types were smaller than normal. These results suggest that the pathogenesis of this disorder involves both myofiber growth and differentiation, particularly differentiation of type 2A

ISSN:0148-639X    

DOI:10.1002/mus.880050902

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractJunctional processes are found in the junctional gap of couplings in skeletal, cardiac, and vascular smooth muscle cells. Visualization of the structure of junctional processes is greatly facilitated by the use of a tilting specimen stage and stereoscopic analysis. Relatively small changes of tilt angle create a spectrum of images for the same junctional process which can range from that of an amorphous electron‐opaque body to a distinct linear structure (“pillar”). In both striated and smooth muscles, pillars connect the sarcolemma with the limiting membrane of junctional sarcoplasmic reticulum (J‐SR). In addition, in vascular smooth muscle cells, pillars join the J‐SR with surface‐connect

ISSN:0148-639X    

DOI:10.1002/mus.880050903

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractStereo‐pair micrographs of freeze‐fracture replicas taken at +6 and −6 degrees and enlarged 55,000 diameters were precisely aligned on a digitizing pad linked to a plotter and programmable calculator. A point grid spaced at 0.23 μm was placed over the left photo‐pair. Under stereoscopic observation, matching points were placed by hand on the right photo‐pair for every point in the applied grid that fell over the membrane surface of interest in the left photo‐pair. Thex, ycoordinates of every point in the two photos were read with the digitizer. These data allowed the calculation of the X, Y, Z coordinates of all points in the untilted object space, 3‐D reconstruction of the analyzed surface, and estimation of the membran

ISSN:0148-639X    

DOI:10.1002/mus.880050904

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractPresynaptic 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

ISSN:0148-639X    

DOI:10.1002/mus.880050905

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractTwo cases of proven thallium poisoning were studied with special reference to the neuromuscular changes. These cases showed a consistent pattern of symptomatology of peripheral sensorimotor neuropathy, encephalopathy, and alopecia. Light and electron microscopic studies of the sural nerve biopsies exhibited mainly axonal degeneration without concomitant segmental demyelination. The densities of both large and small myelinated fibers were mildly decreased. Biopsied peroneus brevis muscles showed distinct features of focal muscle fiber necrosis which has not been reported before. Muscle fibers with prominent central nucleation and fiber splitting were frequently seen. These findings are compatible with myopathic changes. In spite of the existence of severe axonal degeneration and muscle atrophy on clinical observation, no neurogenic muscle changes were found.

ISSN:0148-639X    

DOI:10.1002/mus.880050906

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractHuman skeletal muscle tropomyosin and troponin C were assessed for potential changes in quantity and subunit composition during development and in Becker muscular dystrophy. The proteins were purified or separated into subunits by ion‐exchange chromatography. The fetal and dystrophic sources yielded less of these proteins than the adult and also contained additonal types of tropomyosin chains. The findings may have implications for the disease process and emphasize the feasibility of direct preparative study of human muscl

ISSN:0148-639X    

DOI:10.1002/mus.880050907

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe amino acid sequences of the human skeletal muscle tropomyosins were elucidated. Of the three α‐types identified, the major fraction (identical to the single myocardial species) differed by 23 and 25 amino acid residues from the two minor α‐forms and by 42 residues from β‐tropomyosin. The two β‐components differed only by deletion of the C‐terminal residue in the minor fraction. These sequences will facilitate analysis of tropomyosin from developmental and di

ISSN:0148-639X    

DOI:10.1002/mus.880050908

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractPatients with different myotonic syndromes were evaluated for the presence of transient decrease of muscle fiber excitability. The evoked compound muscle action potential (CMAP) was recorded from the hypothenar eminence; single, supramaximal stimuli were applied to the ulnar nerve at the wrist before and after various periods of voluntary, isometric exercise of the hand muscles. A variable decline of the CMAP after exercise was present in all subjects with myotonia. The results were similar to those obtained with rapid repetitive nerve stimulation.

ISSN:0148-639X    

DOI:10.1002/mus.880050909

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

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

ISSN:0148-639X    

DOI:10.1002/mus.880050910

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe electrophysiologic studies in a case of infant botulism show a variety of abnormalities including tetanic and post‐tetanic facilitation (PTF) of the small single evoked muscle action potential. The enlarged amplitude of the single evoked muscle action potential following a 10‐second tetanic nerve stimulation persisted up to 21 minutes. The prolongation of PTF is a unique feature of botul

ISSN:0148-639X    

DOI:10.1002/mus.880050911

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY